JPH10271848A - Power device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power device having small input current distortion and higher power supply efficiency to a load circuit from an AC power source, by the use of a smaller number of parts. SOLUTION: Diodes D3 -D6 are bridge-connected to constitute a full-wave rectifier. A filter capacitor C1 is connected between the DC output ends of the full-wave rectifier. The series circuit of a pair of switching elements Q1 , Q2 is connected in parallel to the capacitor C1 , and both switching elements Q1 , Q2 are turned on and off alternately by a high frequency. To both switching elements Q1 , Q2 , diodes D1 , D2 are connected in reverse parallel respectively. Between both ends of an AC power source Vs, the series circuit of a pair of capacitors C52 , C53 is connected, and a load circuit 1 is connected between the connection point of the switching elements Q1 , Q2 and that of the capacitors C52 , C53 . Capacitors C51 , C54 are connected in parallel to at least one of the diodes D3 -D4 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a DC voltage obtained by rectifying and smoothing an AC power supply to a high frequency and supplying it to a load.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
There is a configuration shown in FIG. 36 described in Japanese Patent Publication No. 11056. This power supply device is an AC power supply Vs which is a commercial power supply.
Has a function as a chopper circuit for obtaining DC power and reducing input current distortion by rectifying and smoothing the DC power, and a function as an inverter circuit for converting DC power into a high frequency and supplying it to the load circuit 1. includes a full wave rectifier with four diodes D ₁ to D ₄ and bridge connection as a rectifying element, an AC power source Vs between the AC input ends of the full-wave rectifier is connected via an inductor L _2, a full-wave rectifier capacitor C ₁ for smoothing is connected between the DC output ends. Further, a pair of diodes D ₁ and D ₂ constituting one arm of the full-wave rectifier are respectively connected to switching elements Q ₁ and D _2.
1 and Q ₂ are connected in parallel, and a series circuit of a DC cut capacitor C ₃₀ and a load circuit 1 is connected between both ends of the switching element Q ₂ .

[0003] The operation of this power supply will be briefly described. The switching elements Q ₁ and Q ₂ are controlled by a control circuit (not shown) so that they are not turned on at the same time but are turned on and off alternately. The switching frequency of the switching elements Q ₁ and Q ₂ (switching frequency) is set to a frequency sufficiently higher than the frequency (power supply frequency) of the AC power supply Vs. Now, when the polarity of the voltage V _in of the AC power source Vs is the period of the direction indicated by an arrow in the figure, the switching element Q ₁ is is on, the AC power source Vs → diode D ₃ → the switching element Q ₁ → inductor L ₂ → Current flows through the path of AC power supply Vs. In this case the energy in the inductor L ₂ are accumulated. Next, when the switching element Q ₁ is turned off, the inductor L ₂ → AC power source Vs → diode D ₃ →
A path of the capacitor C ₁ → the diode D ₂ → inductor L _2, the energy stored in the inductor L ₂ is released. In other words, the inductor L ₂ to the voltage V _in of the AC power supply Vs
, And the capacitor C ₁ is connected to the power supply voltage Vs
Charge at a higher voltage. With such an operation, it functions as a step-up type chopper circuit that obtains a DC power supply obtained by boosting the AC power supply Vs.

On the other hand, a high frequency voltage is applied to the load circuit 1 when the switching elements Q ₁ and Q ₂ are turned on and off alternately. That is, when the ON switching element Q _1, a current flows through a path of the capacitor C ₁ → switching element Q ₁ → load circuit 1 → capacitor C ₃₀ → capacitor C _1, the capacitor C ₃₀ → load when the switching element Q ₂ is turned on The current flows through the path of the circuit ₁ → the switching element Q ₂ → the capacitor C ₃₀ , and the direction of the current flowing through the load circuit 1 alternates by turning on and off the switching elements Q ₁ and Q ₂ . Such an operation functions as an inverter circuit. Here, when the ON switching element Q _1, flowing through the current the same direction as a current and an inverter circuit as a chopper circuit to the switching element Q _1.

During a period _{in which} the polarity of the voltage Vin of the AC power supply Vs is opposite to the direction indicated by the arrow in the figure, the switching element Q ₂
Will be used as a chopper circuit. In other words, at the time of the on-the switching element Q _2, AC power supply Vs →
Inductor L ₂ → Switching element Q ₂ → Diode D
₄ → A current flows through the path of the AC power supply Vs and the inductor L ₂
Energy is accumulated, when the off-switching element Q _2, the inductor L ₂ → diode D ₁ → capacitor C ₁
→ the path of the diode D ₄ → AC power source Vs → inductor L _2, the energy stored in the inductor L ₂ is being released.

As described above, the switching elements Q ₁ , Q
Reference numeral ₂ is used for both the boost chobber circuit and the inverter circuit. As described above, since the switching elements Q ₁ and Q ₂ are shared between the chobber circuit and the inverter circuit, the number of components constituting the circuit is relatively small, the circuit configuration is simple, and the circuit can be provided at a relatively low cost. It has the advantage of becoming.

On the other hand, Japanese Patent Application Laid-Open No. 4-193
A configuration shown in FIG. 37 described in Japanese Patent Publication No. 066 is also known. This arrangement is provided with a full wave rectifier with four diodes D ₃ to D ₆ of the rectifying element is bridge-connected, the AC power source Vs through a filter circuit 2 'to the AC input ends of the full-wave rectifier is connected . A smoothing capacitor C having a relatively large capacity is provided between the DC output terminals of the full-wave rectifier D.
_1, a series circuit of capacitors C ₃ and C ₃ ′ having a relatively small capacity and a series circuit of switching elements Q ₁ and Q _{2 formed} of transistors are connected in parallel to the capacitor C ₁ . Diodes D ₁ and D ₂ are connected in anti-parallel to the switching elements Q ₁ and Q ₂ , respectively.
The load circuit 1 is connected between the connection point of the capacitors C ₃ and C ₃ ′ and the connection point of the switching elements Q ₁ and Q ₂ , and the connection point of the capacitors C ₃ and C ₃ ′ is connected to the diodes D ₅ and D ₆ . Connected to a connection point.

As in the conventional configuration shown in FIG. 36, FIG.
In the configuration shown in ( ₁₎ , the switching elements Q ₁ and Q ₂ are alternately turned on and off by a control circuit (not shown) so as not to be turned on at the same time. The switching frequency is set sufficiently higher than the power supply frequency. Now, when the polarity of the voltage Vin of the AC power supply Vs is _in the direction indicated by the arrow in the figure,
When the switching element Q ₁ is turned on, the AC power supply Vs →
A current flows through the path of the filter circuit 2 ′ → the diode D ₃ → the switching element Q ₁ → the load circuit 1 → the filter circuit 2 ′ → the AC power supply Vs, and the current can flow directly from the AC power supply Vs to the load circuit 1. Also, the voltage V of the AC power supply Vs
When the polarity of the _in is the period of the opposite direction to the arrow in the figure, when the switching element Q ₂ is turned on, the AC power source Vs → filter circuit 2 '→ load circuit 1 → switching element Q ₂ →
A current flows through the path of the diode D ₄ → the filter circuit 2 ′ → the AC power supply Vs, and the current can flow directly from the AC power supply Vs to the load circuit 1.

Here, the capacitances of the capacitors C ₃ and C ₃ ′ are set so as to completely discharge the electric charge during the switching period of the switching elements Q ₁ and Q ₂ . Therefore,
The input current can flow at a high frequency from the AC power supply Vs over almost the entire period of the AC power supply Vs. In this configuration, since the current flows directly from the AC power supply Vs to the load circuit 1, the load circuit 1
There is an advantage that power supply efficiency is high because there are no multiple power conversion processes in the power supply path to the power supply. The switching element Q ₁ do not have the function of raising than the voltage V _in of the AC power source Vs to the voltage across the capacitor C _1, and can be relatively low voltage across the capacitor C _1,
It is possible to lower the voltage applied to the circuit elements such as Q _2, resulting in some advantage can be provided at low to low cost breakdown voltage of the circuit elements.

[0010]

[SUMMARY OF THE INVENTION However, in the circuit configuration of the former, in the process for supplying power from an AC power source Vs to the load circuit 1, the steps of charging the capacitor C ₁ through the function as a chopper circuit from the AC power source Vs ,
2 the process of applying a high frequency voltage to the load circuit 1 through functions as an inverter circuit for the power supply the capacitor C ₁
Since there are two power conversion processes, the efficiency of power supply from the AC power supply Vs to the load circuit 1 is the product of the efficiency of each power conversion process, and the power supply efficiency limit is sufficiently increased. Cannot do it.

Further, although the inductor L ₂ provided in order to provide a function as a chopper circuit, even though not an essential element in order to reduce the input current distortion, by the inductor L ₂ is present This leads to an increase in the number of parts and a loss of power, leading to a reduction in power supply efficiency. On the other hand, in the latter configuration, as described above, there is an advantage that the power conversion process is small and the power supply efficiency is higher than that of the former configuration. The current can flow directly from the AC power supply Vs to the load circuit 1 only when each of the switching elements Q ₁ and Q ₂ is turned on in each half cycle of the AC power supply Vs, and when the other switching element is turned on. Even if Q ₁ and Q ₂ are turned on, it is not possible to flow a current directly from the AC power supply Vs to the load circuit 1. That is, the peak value of the current passing through the filter circuit 2 'is increased, which causes a problem that the size of the filter circuit 2' is increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce input current distortion and increase power supply efficiency from an AC power supply to a load circuit while using a simple circuit configuration. A power supply device is provided.

[0013]

According to a first aspect of the present invention, there is provided a full-wave rectifier configured by bridge-connecting rectifying elements and performing full-wave rectification on an AC power supply, and a smoothing rectifier connected between a DC output terminal of the full-wave rectifier. And a first switching element and a second switching element connected in parallel to the first capacitor and alternately turned on and off at a frequency higher than the power supply frequency of the AC power supply.
Switching element, the first switching element and the second switching element.
A series circuit of a second capacitor and a third capacitor connected between both ends of an AC power supply, and a first switching element; And a load circuit connected between a connection point of the second switching element and a connection point of the second capacitor and the third capacitor, and is connected in parallel to at least one of the rectifying elements constituting the full-wave rectifier. And a fourth capacitor. According to this configuration, the input current can flow over almost the entire power supply cycle, and one of the switching elements can be switched during one switching operation cycle of the switching elements.
Since the input current will flow twice by turning on each time,
Since the input current distortion is small and the power can be directly supplied from the AC power supply to the load circuit, the power supply efficiency increases. In addition, when a peak value of the input current is small and a filter circuit for blocking high frequency is provided in an input section from the AC power supply, a small filter circuit can be used. Furthermore, the number of parts is relatively small and the configuration is simple.

According to a second aspect of the present invention, a load circuit includes a transformer and a load connected to a secondary side of the transformer, and both ends of a primary winding of the transformer are both ends of the load circuit. In this configuration, since the load circuit has a transformer configuration, it is possible to remove a low-frequency component from a load provided on the secondary side of the transformer and flow a constant load current. Further, if the impedance on the primary side of the transformer is increased, the inrush current can be further reduced.

According to a third aspect of the present invention, the load circuit is connected between the first inductor, the discharge lamp connected in series to the first inductor, and the non-power supply side terminal of the discharge lamp, and resonates together with the first inductor. A fifth capacitor constituting a circuit is provided, and both ends of a series circuit of the first inductor and the discharge lamp become both ends of a load circuit. According to this configuration, since no transformer is used, there is no loss due to the transformer, and power supply efficiency to the load is further increased. In addition, when there is no load, a path for charging the first capacitor is not formed, so that when there is no load, the rush current becomes almost zero.

According to a fourth aspect of the present invention, there is provided a control circuit capable of adjusting an on / off switching frequency of the first switching element and the second switching element.
According to this configuration, it is possible to adjust the input current or the power supplied to the load while keeping the ON period of the switching element substantially constant. Therefore, if the load is a discharge lamp, control of dimming, preheating, starting, lighting, and the like can be performed. Further, when the power supplied to the load suddenly changes and stress is applied to the circuit components, this can be avoided by changing the switching frequency.

According to a fifth aspect of the present invention, there is provided a control circuit capable of adjusting the ON periods of the first switching element and the second switching element. According to this configuration, it is possible to adjust the input current or the power supplied to the load while keeping the switching frequency substantially constant.
Therefore, if the load is a discharge lamp, dimming is performed,
Control such as preheating, starting, and lighting can be performed. Further, when the power supplied to the load suddenly changes and stress is applied to the circuit components, this can be avoided by changing the switching frequency.

According to a sixth aspect of the present invention, there is provided a means for detecting a voltage between both ends of the first capacitor, and the control circuit controls the control circuit so as to suppress a rise in the voltage between both ends of the first capacitor based on the detected voltage. The first switching element and the second switching element are controlled. According to this configuration, when the voltage between both ends of the first capacitor abnormally rises, the operation of the switching element is stopped or the output to the load is reduced, thereby preventing the circuit element from being stressed. can do. In addition, if the increase in the voltage across the first capacitor is suppressed and kept substantially constant, the power supply to the load is stabilized. Therefore, if the load is a discharge lamp, an optical output with less flicker can be obtained.

According to a seventh aspect of the present invention, the control circuit includes means for detecting a voltage corresponding to the voltage applied to the transformer, and the control circuit controls the first circuit so as to suppress an increase in the voltage applied to the transformer based on the detected voltage. And the second switching element. According to this configuration, when the applied voltage to the load rises abnormally or when the load is short-circuited, the operation of the switching element is stopped, or the output to the load is reduced, so that the It is possible to prevent stress from being applied.

The invention according to claim 8 further comprises means for detecting the voltage across the fourth capacitor, and the control circuit keeps the output to the load circuit substantially constant based on the voltage across the fourth capacitor. The first switching element and the second
Are controlled. According to this configuration, since the output to the load can be kept substantially constant, stable operation of the load can be expected. In particular, when the load is a discharge lamp, an optical output with less flicker can be obtained.

According to a ninth aspect of the present invention, there is provided a means for detecting a current flowing in a load circuit, wherein the first switching element and the second switching element maintain the current flowing in the load circuit substantially constant based on the detected current. It controls the elements. According to this configuration, even when the voltage of the AC power supply fluctuates, the current supplied to the load can be made substantially constant, so that stable operation of the load can be expected. In particular,
When the load is a discharge lamp, the fluctuation of the lamp current can be reduced to obtain an optical output with less flicker.

According to a tenth aspect of the present invention, there is provided means for varying the capacity of the fourth capacitor. According to this configuration, the input current can be adjusted according to the load, and the input current distortion can be reduced. For example, even when the load is a discharge lamp and dimming or switching of the load output is performed, the input current distortion can be reduced. According to an eleventh aspect, the load circuit includes a plurality of loads. According to this configuration, a plurality of loads can be driven simultaneously.

According to a twelfth aspect of the present invention, in parallel with one of the first switching element and the second switching element,
Alternatively, a second load circuit is connected in parallel with the first capacitor. According to this configuration, the output to the second load circuit can be made substantially constant without special control, so that stable driving can be performed while simultaneously driving a plurality of loads. In particular, when the load is a discharge lamp, an optical output with less flicker can be obtained. Further, even if one of the discharge lamps comes off, the other discharge lamp can be kept on.
Further, the power supplied to each load can be set to an appropriate ratio. Also, even if the voltage of the AC power supply fluctuates,
The load current as a whole can be almost constant,
By reducing the pulsating current of the lamp current, a light output with less flicker can be obtained.

According to a thirteenth aspect of the present invention, at least one of the first switching element and the second switching element is self-excited by feedback of a current flowing through a load circuit. According to this configuration, the drive circuit of the switching element can be simplified or eliminated, so that the number of components can be further reduced. For example, if a transformer is provided in a load circuit and feedback is performed using an inductor provided on the secondary side of the transformer, the circuit automatically stops when an abnormality such as no load occurs. In addition, if the driving of one switching element is self-excited and the driving of the other switching element is separately controlled by an external signal, the power supplied to the load can be controlled. Control such as dimming and stopping can be easily performed.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in (Embodiment 1) FIG. 1, in this embodiment, like the conventional structure shown in FIG. 37, a full-wave which constitutes the four diodes D ₃ to D ₆ of the rectifying element is bridge-connected comprising a rectifier, AC power source Vs between the AC input ends of the full-wave rectifier is connected, the capacitor C ₁ for smoothing between the DC output ends of the full-wave rectifier is connected. The diode D ₃ to D each pair of diodes D ₃ constituting each arm _6, D ₄ and D _5, D 4 single capacitor C ₅₁ -C ₅₄ with the series circuit of ₆ constituting the full-wave rectifier Are connected in parallel. Each capacitor C _51, C ₅₄ at both ends of one of the series circuit diode D ₃ of the capacitor C ₅₁ ~C _54, D ₆
The AC power supply Vs is connected to both ends of the series circuit of the intermediate capacitors C ₅₂ and C ₅₃ .

A series circuit of switching elements Q ₁ and Q ₂ composed of transistors is connected between both ends of the capacitor C ₁ , and diodes D ₁ and D ₂ are connected in anti-parallel to the switching elements Q ₁ and Q ₂ , respectively. Is done. Load circuit 1
Is inserted between the connection point of the switching elements Q ₁ and Q _{2 and} the connection point of the capacitors C ₅₂ and C ₅₃ . Here, the load circuit 1 is inductive and configured to have a function of accumulating current energy. Although the switching elements Q ₁ and Q ₂ are shown as npn-type transistors in FIG. 1, the purpose is to make it easier to understand the direction of the current, and other switching elements such as MOSFT may be used as described later. The good is, of course. The switching elements Q ₁ and Q ₂ are controlled by a control circuit (not shown) so that they are not turned on at the same time but turned on and off alternately.
The point that the repetition frequency (switching frequency) of ON / OFF of the switching elements Q ₁ and Q ₂ is set to a frequency sufficiently higher than the frequency (power supply frequency) of the AC power supply Vs is the same as the conventional configuration.

Next, the operation will be described. First, the AC power supply Vs
Of the voltage Vin _in the direction indicated by the arrow in FIG.
This direction is referred to as positive polarity). FIGS. 2 to 7 show one cycle of the switching operation of the switching elements Q ₁ and Q ₂ during the steady operation.
2 to 7, the current paths are indicated by broken lines and alternate long and short dash lines. The capacitor C ₁ is assumed to be charged immediately after the power is turned on.

Since the capacitor C ₁ is charged as described above, as shown in FIG. 2, when the switching element Q ₁ is turned on and the switching element Q ₂ is turned off, the capacitor C ₁ → the switching element Q ₁ → the load. A current flows through the path of the circuit 1 → the capacitor C ₅₃ → the capacitor C ₅₄ → the capacitor C ₁ and the current flows through the load circuit 1. Further, in the steady state charge of the capacitor C _51, C ₅₂ is discharged in a path of the capacitor C ₅₁ → the switching element Q ₁ → load circuit 1 → capacitor C ₅₂ → the capacitor C _51.

The capacitance of the capacitor C _51, C ₅₄ is set to a small volume to the extent that finishes releasing charges within the on period of the switching element Q _1, Q _2, when the electric charge of the capacitor C ₅₁ finishes releasing, As shown in FIG. 3, a current flows through the path of the AC power supply Vs → the diode D ₃ → the switching element Q ₁ → the load circuit 1 → the capacitor C ₅₃ → the AC power supply Vs. That is, the input current from the AC power supply Vs flows. Also, the capacitor C ₅₂ → the diode D ₃ → the switching element Q ₁
→ current flows in the route of the load circuit 1 → capacitor C ₅₂ (capacitor C _52, C ₅₃ is set larger capacity than the capacitors C _51, C _54). Energy is stored in the load circuit 1 during the periods shown in FIGS.

Next, when the switching element Q ₁ is turned off, as shown in FIG. 4, the load circuit 1 → capacitor C ₅₂ →
Capacitor C ₅₁ → Capacitor C ₁ → Diode D ₂ → Current flows in the path of load circuit 1 and load circuit 1 →
A current flows through the path of the capacitor C ₅₃ → the capacitor C ₅₄ → the diode D ₂ → the load circuit 1, and the energy stored in the load circuit 1 is released. Capacitor C ₁ is charged during this period. In this period, the switching element Q
₂ may be on or off.

[0031] When the energy stored in the load circuit 1 is released (switching element Q ₂ up to this point are controlled to be turned on), as shown in FIG. 5, the capacitor C ₁ as a power source, Capacitor C ₁ → Capacitor C ₅₁
→ Capacitor C ₅₂ → Load circuit 1 → Switching element Q ₂
→ current flows through a path of capacitor C _1. Current also flows through the path of the capacitor C ₅₃ → the load circuit 1 → the switching element Q ₂ → the capacitor C ₅₄ → the capacitor C ₅₃ . That is, a current flows through the load circuit 1 in a direction opposite to that before.

[0032] Thereafter, the charge of the capacitor C ₅₄ finishes releasing, as shown in FIG. 6, the capacitor C ₅₂ from the AC power source Vs → load circuit 1 → the path of the switching element Q ₂ → diode D ₆ → AC power source Vs Electric current flows. That is,
During this period, the input current from the AC power supply Vs flows. At the same time, a current flows through the path of the capacitor C ₅₃ → the load circuit 1 → the switching element Q ₂ → the diode D ₆ → the capacitor C ₅₃ . Here, energy is accumulated in the load circuit 1 during the periods shown in FIGS.

Next, when the switching element Q ₂ is turned off, as shown in FIG. 7, the load circuit 1 → the diode D ₁ →
The path of capacitor C ₁ → capacitor C ₅₄ → capacitor C ₅₃ → load circuit 1 and load circuit 1 → diode D ₁ →
The energy stored in the load circuit 1 is released through the path of the capacitor C ₅₁ → the capacitor C ₅₂ → the load circuit 1. Capacitor C ₁ is charged during this period. At this time, the switching element Q ₁ is may be off in on.

The conditions for forming the current path shown in FIG.
The added voltage of the voltage across the series circuit of the capacitors C ₅₃ and C _{54 and} the voltage across the series circuit of the load circuit 1 is the capacitor C
_{1 and} the voltage across the load circuit 1 is higher than the voltage across the series circuit of the capacitors C ₅₁ and C ₅₂ , and the energy stored in the load circuit 1 is released ( the time switching element Q ₁ so far is controlled to be turned on), will return to the state shown in FIG.

Although the above operation has been described for the case where the AC power supply Vs has a positive polarity, the operation is substantially the same when the AC power supply Vs has a negative polarity. However, when the AC power supply Vs has a positive polarity, a path passing through the diodes D ₃ and D ₆ is formed as a path through which current flows from the AC power supply Vs to the load circuit 1, whereas the AC power supply Vs has a negative polarity. In this case, the path changes to a path passing through the diodes D ₄ and D ₅ .

As described above, the switching elements Q ₁ , Q
_The alternating current flows through the load circuit 1 by the repetition of the on / off operation of ₂ . Further, since a path passing through the AC power supply Vs is formed during one cycle of the switching of the switching elements Q ₁ and Q ₂ , the input current from the AC power supply Vs can flow at a high frequency, and the input current distortion increases. Can be prevented. Moreover, as is apparent from the above-described operation, in both the period in which the AC power supply Vs has the positive polarity and the period in which the AC power supply Vs has the negative polarity, the AC power supply Vs receives the power from the AC power supply Vs during the ON periods of the switching elements Q ₁ and Q ₂ . Since there is a period during which the input current flows, the peak value of the input current can be reduced.

Incidentally, the circuit shown in FIG. 8 can be used as the load circuit 1. The circuit shown in FIG. 8 uses a combination of the AC power supply Vs and the filter circuit 2 in place of the AC power supply Vs shown in FIG. That is, both ends of the AC power supply Vs in FIG. 1 correspond to the output terminals of the filter circuit 2 in the configuration shown in FIG. Further, MOSFETs are used as the switching elements Q ₁ ′, Q ₂ ′ instead of the parallel circuit of the switching elements Q ₁ , Q ₂ and the diodes D ₁ , D ₂ . In this case, the functions of the diodes D ₁ and D ₂ are realized by parasitic diodes inside the MOSFET. With this configuration, if a transistor and a diode are used, four parts are required, but two parts are required, which leads to a reduction in the number of parts.

The filter circuit 2 has a turn ratio of 1:
A line choke LF ₁ with two windings of ₁ ,
Comprises a capacitor C ₂₃ connected between one end of the two windings at both ends of the AC power source Vs, an inductor LF ₂ connected in series to one of the windings. This filter circuit 2 constitutes a low-pass filter that passes a power supply frequency and blocks a switching frequency. By providing such a filter circuit 2, the high-frequency component of the input current can be suppressed to prevent high-frequency noise from flowing into the AC power supply Vs, and the input current waveform becomes close to a sine wave, and the input power factor Can be increased.

On the other hand, the load circuit 1 includes a leakage transformer T ₁ , a discharge lamp La ₁ such as a fluorescent lamp as a load having one end of each filament connected to both ends of a secondary winding of the leakage transformer T ₁ , a capacitor C ₂ Metropolitan of the discharge lamp La for connected preheating between the other end of the _first filament (or resonance). In the load circuit 1, both ends of the primary winding of the leakage transformer T ₁ becomes the input end. That is, one end of the primary winding of the leakage transformer T ₁ is connected to a connection point of the capacitor C _52, C _53, the other end is connected to a connection point of the switching elements Q ₁ ', Q _2'. Capacitor C ₂ constitute a resonance circuit together with the leakage Indatansu leakage transformer T _1.

FIG. 9 shows the operation waveform of each part of the circuit shown in FIG.
Shown in In the Figure is shown the operation of one cycle of the AC power source Vs, Fig. (A) the input voltage V _in and the input current I _in of the AC power source Vs, Fig. (B) The connection point of the capacitor C _51, C ₅₂ voltage, FIG (c) shows a Ranbu current flowing through the discharge lamp La _1. Lamp current apparent discharge lamp La ₁ from figures are not significantly affected by the voltage component of the AC power source Vs. Input current (FIG. (C)) from the AC power source Vs in FIG. 9 and the switching elements Q ₁ ', Q _2' relation (FIG between off of (a) the switching element Q ₁ ', (b)
Indicates a switching element Q ₂ ′). As is clear from FIG. 9, the input current flows during the ON period of any of the switching elements Q ₁ ′ and Q ₂ ′.

In the circuit of this embodiment, the number of components is relatively small, which leads to downsizing and cost reduction. Moreover, the input current can be reduced input current distortion by flowing a high frequency, and it is possible to obtain a high input power factor substantially in proportion to the input current to the voltage of the AC power source V _in. The switching element Q ₁ ', Q _2' the input current from the AC power source Vs in the switching cycle can flow twice (the switching elements Q ₁ ', Q _2' flowing once for), the peak value of the input current Can be reduced. As a result, high frequency components can be blocked even if the filter circuit 2 is small. In addition, since there is a process of directly supplying power from the AC power supply Vs to the load circuit 1, the power supply efficiency increases accordingly.

[0042] (Embodiment 2) In Embodiment 1, although the respective diodes D _3, D ₆ capacitors C _51, C ₅₄ were connected in parallel, as shown in FIG. 11, be omitted capacitor C ₅₁ Good. In this configuration, the input current distortion is slightly larger than in the first embodiment because there is no power supply process from the capacitor _C51 to the load circuit 1 (the process in FIG. 2). Can be suppressed, and the number of parts is reduced as compared with the first embodiment. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIG. 12, capacitors C ₅₅ and C ₅₆ are further added to the configuration of Embodiment 1, and all the diodes D forming a full-wave rectifier are provided. ₃ capacitor C relative to D _6
51, in which the C ₅₄ -C ₅₆ are connected in parallel. According to this configuration, the current flowing through the capacitor C _51, C ₅₄ ~C ₅₆ connected in parallel to the diode D ₃ to D ₆ are approximately half as compared with the capacitor C _51, C ₅₄ in the configuration shown in FIG. 1 since made, it will reduce the stress on the capacitor C _51, C ₅₄ ~C _56. Other configurations and operations are the same as those of the first embodiment.

[0044] (Embodiment 4) This embodiment, as shown in FIG. 13, without using a leakage transformer T ₁ and transformer T _2, the inductor L ₁ and the discharge lamp La ₁ connected in series, the discharge lamp La It is used the load circuit 1 and a capacitor C ₂ to the non-power supply side of _one of the filaments. This configuration also makes up a resonance circuit by an inductor L ₁ and capacitor C _2. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 5) As shown in FIG. 14, this embodiment has the same configuration as that of the embodiment 1 shown in FIG. 1, and the leakage transformer T shown in FIG. ₁ , a discharge lamp La ₁ and a capacitor C ₂ are used. In FIG. 14, the illustration of the filter circuit 2 is omitted.

In FIG. 14, a control circuit 3 for controlling the on / off of the switching elements Q ₁ ′ and Q ₂ ′ is shown.
Is illustrated. This embodiment is different from the first embodiment in that the control circuit 3 includes switching elements Q ₁ ′, Q
_The point is that the power supply to the load circuit 1 can be adjusted by using a device that can arbitrarily control a switching frequency, an ON time, a duty ratio, and the like for turning on and off the ₂ '. That is, the light output of the discharge lamp La ₁ is enabled can be a dimming control regulation. Here, the above-described control of the on-time means that the on-time is changed (generally, the off-time is kept constant), and the control of the duty ratio means that the ratio between the on-time and the off-time is made constant while the frequency is kept constant. Means to change.

That is, the control of the switching frequency means that the switching elements Q ₁ ′ and Q ₂ ′ are turned on and off as shown in FIG.
Means to shift to the on / off state. In the illustrated example, the switching frequency is shifted to the high frequency side. When in this manner varies the switching frequency, the relationship between the resonance frequency and the switching frequency of the resonant circuit is formed by the leakage inductance and the capacitor C ₂ of the leakage transformer T _1, the discharge lamp L
The power supplied to a ₁ changes, and the light output of the discharge lamp La ₁ can be controlled. The control of the duty ratio means that the switching elements Q ₁ ′ and Q ₂ ′ are turned on and off as shown in FIG.
Means to shift to the on / off state. That is, the ratio between the on-time and the off-time is controlled while keeping the frequency constant. In the illustrated example, the duty ratio of the switching element Q ₁ ′ is reduced, and the duty ratio of the switching element Q ₂ ′ is increased. . With such control, the amount of input power from the AC power supply Vs can be changed, and as a result, the power supplied to the load circuit 1 can be adjusted.

Further, both the switching frequency and the duty ratio are controlled, and the switching elements Q ₁ ′ and Q ₂ ′ are turned on and off as shown in FIG. 17A, for example, as shown in FIG. 17B. The state may be shifted to an on / off state. Other configurations and operations are the same as those of the first embodiment. (Embodiment 6) This embodiment shows a control example when the discharge lamp La1 provided in the load circuit ₁ is turned on. Process for lighting the discharge lamp La ₁ having a filament (hot cathode) is a preheating → start → lighting, mainly energized filament preheating process, the discharge by applying a high voltage between the two filaments in the starting process It is started and the rated lighting is performed after the start of discharge.

The above steps are performed by the switching element Q in the circuit configuration of the first embodiment shown in FIG. 8 (actually, the circuit configuration including the control circuit 3 as in the fifth embodiment shown in FIG. 14). _This is realized by controlling ₁ ′ and Q ₂ ′ as shown in FIG. Figure 18 is a controls the switching frequency for the resonant frequency of the resonant circuit composed by the leakage inductance and the capacitor C ₂ of the leakage transformer T _1, are set high switching frequency.

[0050] At the time preheating are lowering the applied voltage of the greatly advance, the two ends of the discharge lamp La ₁ between the resonance frequency and the switching frequency is set high switching frequency as in FIG. (A). During start-up to reduce the difference between the resonant frequency by lowering the switching frequency than during preheating as in FIG (b), increasing the voltage applied to both ends of the discharge lamp La _1. In this manner, when the discharge lamp La ₁ with the lights, because the resonant frequency of the load circuit 1 is shifted to a lower frequency, drawing a switching frequency as the lamp current required for rated lighting of the discharge lamp La ₁ is obtained As shown in (c), the switching frequency is further reduced at the time of lighting (the switching frequency is lower than at the time of starting, but the relationship between the time of starting and the time of lighting is not always the same).

As described in the fifth embodiment, the power supplied to the discharge lamp La ₁ can be adjusted by controlling the on / off duty ratio of the switching elements Q ₁ ′ and Q ₂ ′. As shown in FIG. 19, by changing only the duty ratio without changing the switching frequency, preheating is performed by the control of FIG. 19A, and starting is performed by the control of FIG. The rated lighting may be performed by the control of.

Further, as shown in FIG. 20, the on / off switching frequency and the duty ratio of the switching elements Q ₁ ′ and Q ₂ ′ may be controlled simultaneously. In this case, preheating is performed by the control of FIG. 7A, starting is performed by the control of FIG. 7B, and rated lighting is performed by the control of FIG. (Embodiment 7) In this embodiment, as shown in FIG. 21, in the circuit configuration of the embodiment 1, the voltage detecting circuit 5a for outputting a voltage proportional to the voltage across the diode D _3, D _6,
5b is added. The voltage detection circuit 5a, the output voltage of the 5b are alternatively selected by the changeover switch elements SW _2, it is smoothed by the capacitor C ₃₂ after the output voltage selected is rectified by the diode D _31. Voltage across the capacitor C ₃₂ is input to the control circuit 3. Further, the changeover switch elements SW ₂ is switched according to the polarity of the AC power source Vs detected by the power supply polarity determination circuit 4.

The power supply polarity determining circuit 4 includes a voltage detecting circuit 5
The polarity of the AC power supply Vs is determined based on the output voltages a and 5b. That is, the voltage detection circuit 5a, 5b is because detecting the potential difference between the end of the potential and the ground potential of the AC power source Vs (negative electrode potential of the capacitor C _1), both the voltage detecting circuit 5a,
The polarity of the AC power supply Vs can be known based on the output of 5b.

[0054] the construction described above, the voltage across the capacitor C ₃₂ is from will reflect the voltage across the diode D _3, D _6, it is possible to know the operational state of the circuit by the voltage. Therefore, the control circuit 3 performs control according to the operation state of the circuit by changing the switching frequency and the duty ratio for turning on and off the switching elements Q ₁ ′ and Q ₂ ′ according to the voltage across the capacitor C _32. .

The waveform of each part of the circuit shown in FIG. 21 is shown in FIG.
Shown in FIG (a) is an AC power supply voltage his type of Vs, Fig (b) is a voltage detection circuit 5a selected by the changeover switch elements SW ₂ which is controlled by the power supply polarity determination circuit 4,
The output voltage of 5b, FIG (c) is a voltage across V _C32 of the capacitor C _32. In FIG. 7B, a period Ta is a period during which the output voltage of the voltage detection circuit 5a is selected,
b indicates a period during which the output voltage of the voltage detection circuit 5b is selected. As apparent from FIG. 22, it is possible to know about the peak value near or zero cross point of the AC power source Vs by the voltage across the capacitor C _32.

However, when controlling so as to improve the crest factor (crest factor) of the lamp current of the discharge lamp La ₁ , the peak value of the AC power supply Vs near the peak value of the AC power supply Vs based on the change in the voltage across the capacitor C _32. The switching frequency may be set low, and the switching frequency may be set high near the zero-cross point of the AC power supply Vs. Further, the duty ratio may be controlled instead of the switching frequency. In this case, the duty ratio is set to 5 near the peak value of the AC power supply Vs.
0%, and the ratio between the ON period and the OFF period may be increased near the zero cross point of the AC power supply Vs. further,
The switching frequency and the duty ratio may be changed simultaneously. If the crest factor is reduced in this way, the discharge lamp L
The flicker of the light output of a ₁ can be reduced.

In order to prevent the circuit components such as the switching elements Q ₁ ′, Q ₂ ′ and the capacitor C ₁ from being destroyed by the over voltage, the over voltage may be detected by the voltage across the capacitor C _32. It is possible. That is, the Agego the voltage across the capacitor C ₃₂ becomes abnormally high, the switching element Q ₁ ', Q _2' if stops oscillation, it is possible to avoid damage due to overvoltage. Other configurations and operations are the same as those of the first embodiment.

By the way (Embodiment 8), in the circuit configuration of embodiment 1, at a light load as in the case of performing the dimming the discharge lamp La _1, there may be a pause period occurs in the input current. That is, when the dimming degree increases (that is, when the optical output decreases), the pause period of the input current increases, and the input current distortion increases. Similarly, when the load increases, a large change occurs near the zero crossing point of the input current (the polarity of the input current is inverted while the input current is flowing), and a discontinuous waveform appears, so that the input current distortion increases. Will do. As described above, in a usage mode in which the load increases and decreases, the input current waveform changes due to the increase and decrease in the load.

Therefore, in this embodiment, as shown in FIG. 23, in the circuit configuration of the first embodiment, an AC switch (transistors Tr ₂₁ , Tr ₂₂₎ including diode bridges DB ₂₁ , DB ₂₂ and transistors Tr ₂₁ , Tr ₂₂ is used. _A diode bridge DB ₂₁ , DB ₂₂
Are connected in parallel to the DC output terminals of the switching elements and non-polarized switching elements) and capacitors C ₆₁ and C ₆₂ are connected in parallel to the capacitors C ₅₁ and C ₅₄ , respectively. In this circuit, the on-off of the transistor Tr _21, Tr _22, selects the condition used alone capacitors C _51, C _54, and a state of parallel connection of the capacitor C _61, C ₆₂ in the capacitor C _51, C _54.

In this configuration, when the load becomes large and the input current waveform is distorted, capacitors C ₆₁ and C ₆₂ are connected in parallel with capacitors C ₅₁ and C ₅₄ to increase the combined capacitance, thereby increasing the capacitance of capacitor C _51. , by increasing the voltage generated at both ends of the C _54, it is possible to approximate the input current waveform to a sine wave. The transistors Tr ₂₁ and Tr ₂₂ are normally turned on and off at the same time, but only one of them may be turned on and off as needed.

Further, as shown in FIG.
A configuration may be adopted in which capacitors C ₆₁ and C ₆₂ are connected in series to ₅₁ and C ₅₄ , and an AC switch having the same configuration as that shown in FIG. 23 is connected to capacitors C ₆₁ and C ₆₂ . In this configuration, the transistors Tr ₂₁ and Tr ₂₂ are normally turned on, and the transistors Tr ₂₁ and Tr ₂₂ are turned off at light load, and the capacitors C ₆₁ and C ₆₂ are connected in series to the capacitors C ₅₁ and C ₅₄ to combine them. By reducing the capacitance, the voltage generated at both ends of the series circuit of the capacitors C ₅₁ and C ₅₄ and C ₆₁ and C ₆₂ can be reduced to make the input current waveform closer to a sine wave.

The circuit configurations shown in FIG. 23 and FIG. 24 are effective as switching means when _one discharge lamp La ₁ is required to have two types of output characteristics. In the present embodiment, the switching element Q ₁ by the control circuit 3 ', Q _2' exemplifies the case where the magnitude of the load is increased or decreased in accordance with the control of the on-off of the transistor Tr _2, the control circuit 3
Is determined according to the control state of the switching elements Q ₁ ′ and Q ₂ ′. Other configurations and operations are the same as those of the first embodiment.

[0063] As described above, to control the switching element Q ₁ ', Q _2' in accordance with the voltage across the capacitor C _54, by or by varying the impedance of the capacitor C _54, a discharge lamp La ₁ lamp Fluctuation in current can be suppressed, and fluctuation in optical output can be suppressed to prevent flickering or to improve input current distortion.

(Embodiment 9) In this embodiment, as shown in FIG. 25, in addition to the configuration of Embodiment 5 shown in FIG.
The magnitude of the load is detected by a current detector 6 provided in the load circuit 1, and the control circuit 3 determines the on / off switching frequency and duty ratio of the switching elements Q ₁ ′ and Q ₂ ′ based on the output of the current detector 6. By controlling the discharge lamp La ₁
This suppresses fluctuations in the lamp current flowing through the lamp. The current detection unit 6 is realized by a device that inserts a low resistance into a circuit and uses a voltage between both ends, or a device that uses a secondary output of a current transformer.

However, during a period in which the lamp current is relatively large, the switching frequency is increased to control the lamp current so as to reduce the lamp current, thereby suppressing the fluctuation of the lamp current and the fluctuation of the light output. . Other configurations and operations are the same as those of the first embodiment. (Embodiment 10) As shown in FIG.
In the configuration of the embodiment 5 shown in FIG. 14, divide the voltage across the capacitor C ₁ minute from a parallel connection of a series circuit of two resistors R _10, R ₁₁ across the capacitor C _1,
The voltage obtained by dividing the voltage and a preset reference voltage V _ref
Large and small compared determined by Konbareta CP ₄ and, according to the output of the comparator CP _4, the switching element Q ₁ ', Q _2' is for controlling on and off of. The purpose of this embodiment detects the no-load conditions due to the discharge lamp half-wave lighting state at the end of life of La ₁ (so-called Emiresu state) and the end of life and the discharge lamp La ₁ is out, the output to the load circuit 1 To stop or reduce.

[0066] Thus, in the configuration shown in FIG. 26, Emiresu state and the capacitor C ₁ across the voltage in a no-load state increases resistance R _10, the reference voltage the voltage at the connection point of R ₁₁ V _ref
Exceeding the output of the comparator CP ₄ becomes H level, the control circuit 3 is the switching element Q ₁ ',
The on / off of Q ₂ ′ is stopped or the output is reduced to bring the discharge lamp La ₁ into the dimming lighting state.

[0067] The detection of Emiresu state and unloaded state, rather than the voltage across the capacitor C _1, as shown in FIG. 27, the detecting winding n ₃ provided leakage transformer T _1,
Signal level induced voltage obtained through the diode D ₃₂ of the detection winding n ₃ and the reference voltage V _ref and the comparator C
It may be employed which compares the P _4. In this case, the comparator CP ₄ because the voltage that reflects the instantaneous value of the current flowing in the primary winding of the leakage transformer T ₁ is input, so as to capture the output of the control circuit 3 in the comparator CP ₄ at a predetermined timing It is.

[0068] Further, as shown in FIG. 28, may be compared with the voltage across the reference voltage V _ref of the resistor R ₁₂ connected in series to the source of the switching element Q ₂ 'in the comparator CP _4. Also in this case, since the comparator CP ₄ detects the instantaneous value of the source current of the switching element Q ₂ ′, the control circuit 3 takes in the output of the comparator CP _{4 at} a predetermined timing.

In the configuration of the present embodiment, when the discharge lamp La ₁ comes off and goes into a no-load state, or when the discharge lamp La ₁ is consumed by the emitter of the filament of the discharge lamp La _{1, the} discharge lamp La ₁ is driven only by a half-wave of the AC power supply Vs. In the Emiless state where the light is no longer lit, it is possible to prevent the elements such as the switching elements Q ₁ ′ and Q ₂ ′ from being stressed and broken. (Embodiment 11) In each of the embodiments described above, the configuration of the separately-excited control type in which the switching elements Q ₁ and Q ₂ (Q ₁ ′, Q ₂ ′) are controlled by the control circuit 3 has been described. ,
As shown in FIG. 29, the switching elements Q ₁ and Q ₂ are self-excited.

[0070] That is, a pair of feedback windings n _31, n ₃₂ to leakage transformer T _1, a leakage transformer T ₁
The winding directions of the feedback windings n ₃₁ and n ₃₂ are set so that the switching elements Q ₁ and Q ₂ alternately turn on and off according to the direction of the current flowing through the primary winding. However, at the time of starting, the switching element Q is provided by a separately provided starting means 12.
Force ₂ on.

Self-excitation control is also possible with the configuration shown in FIG. In this configuration, by inserting the inductor L ₁ to the secondary winding of the leakage transformer T ₁ to the load circuit 1, a pair of feedback windings n _33, n ₃₄ to the inductor L _1, the feedback winding n _33, n ₃₄ is connected between the base and the emitter of the switching elements Q ₁ and Q ₂ . In this configuration, the switching element Q in accordance with the direction of the current flowing through the inductor L _1
1, Q ₂ are are decided winding direction of the feedback winding n _33, n ₃₄ to alternate on and off. In this circuit configuration,
When the discharge lamp La ₁ is out, the oscillation because no current flows through the inductor L ₁ has the advantage of automatically stopped. In this circuit configuration as well, similarly to the circuit configuration shown in FIG. 29, an activation unit 12 is separately required. According to the configuration of the present embodiment, there is no need to provide a control signal from the outside and the control circuit 3 is not required, and thus there is an advantage that the number of components is small. Other configurations and operations are described in the first embodiment.
Is the same as

(Twelfth Embodiment) In the present embodiment, as shown in FIG.
₁ is self-excited and the switching element Q ₂ ′ composed of MOSFET is separately excited by a control signal from the control circuit 3 ′. The switching element Q ₁ is turned on and off by receiving the induced voltage of the feedback winding n ₃₅ provided in the leakage transformer T _1.

In this circuit configuration, since the control circuit 3 ′ is provided, the on / off operation of the switching elements Q ₁ and Q ₂ ′ is controlled to reduce the output to the load circuit 1 or stop the output. If only one switching element Q ₂ ′ is controlled, such a function can be realized, so that two switching elements Q ₁ , Q ₂ (Q
₁ ′, Q ₂ ′), the number of parts is reduced as compared with the case of separately controlled excitation. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 13) In this embodiment, as shown in FIG. 32, a plurality (two in the illustrated example) of discharge lamps L
This is an example in which load circuits 1 having a ₁ La ₂ are used, and these load circuits 1 can be employed in any of the above-described embodiments. The load circuit 1 shown in FIG. 32A connects one end of one filament of _two discharge lamps La ₁ and La ₂ , and includes a preheating winding n ₃₆ provided between the other ends of the leakage transformer T _1. By connecting, two discharge lamps La ₁ and La ₂ are connected in series,
The series circuit of the discharge lamps La ₁ and La ₂ is connected to the secondary winding of the leakage transformer T ₁ and the discharge lamps La ₁ and L 2 are connected.
a single capacitor C ₂ to a series circuit of a ₂ are connected in parallel.

The load circuit 1 shown in FIG.
This corresponds to a configuration in which two load circuits 1 of the first embodiment shown in FIG. 8 are connected in parallel. In other words, the two leakage transformer T _11, the primary winding between the T ₁₂ are connected in parallel, each leakage transformer T _11, respectively the secondary winding of T ₁₂ Hokago lamp La
₁ and La ₂ are connected in parallel, and each discharge lamp La ₁ ,
Capacitors C ₂₁ and C for resonance between the filaments of La _2
22 connected.

[0076] Load circuit 1 shown in FIG. 32 (c), rather than a leakage transformer T ₁ using the conventional transformer T _2,
A series circuit consisting of an inductor L ₁₁ and the discharge lamp La ₁ Tokyo,
And a series circuit of an inductor L ₁₂ discharge lamp La ₂ Metropolitan are those having a structure in which parallel connection to the secondary winding of the transformer T _2, each of the discharge lamps La _1, of La ₂ is between the filaments for resonance The capacitors C ₂₁ and C ₂₂ are connected.

The load circuit 1 shown in FIG. 32D has two discharge lamps La ₁ and La ₂ connected to the secondary side of the leakage transformer T ₁ via a balancer L ₃ . That is, leakage of the one end of the secondary winding of the transformer T ₁ is connected to the tap of the balancer L _3, respectively discharge lamp La between the other end of each end and leakage secondary winding of the transformer T ₁ of the balancer L _{3 1} and La ₂ are connected. In addition, each discharge lamp L
Resonant capacitors C ₂₁ and C ₂₂ are connected between the filaments a ₁ and La ₂ , respectively. In this configuration, a resonance circuit is formed by the capacitors C ₂₁ and C ₂₂ , the leakage inductance of the leakage transformer T ₁ , and the inductance of the balancer L ₃ .

[0078] Load circuit 1 shown in FIG. 32 (e) is a conventional inductor L ₁ for resonance in the primary winding of the transformer T ₂ are connected in series, a secondary winding provided on the inductor L ₁ discharging lamp L
It is used as a preheating winding for applying a preheating current to the filaments a ₁ and La ₂ . Here, the inductor L ₁ is provided with three secondary windings is used as the preheating winding. The two discharge lamps La ₁ and La ₂ have one end connected to one filament and the other end connected to the secondary winding of the inductor L ₁ via the capacitor C ₄₁ . The discharge lamp La _1, respectively to other filaments of La ₂ via a capacitor C _42, C ₄₃ 2 winding of the inductor L ₁ is connected. A parallel circuit of a series circuit of the discharge lamps La ₁ and La ₂ and a resonance capacitor C ₂ is connected between the secondary windings of the transformer T ₂ . In this configuration, the inductor L
Resonant circuit is formed by ₁ and a capacitor C _2.

By using the load circuit 1 configured as described above, it becomes possible to light a plurality of discharge lamps La ₁ and La ₂ . FIGS. 32A and 32B show the load circuit 1 including _two discharge lamps La ₁ and La ₂ .
A similar connection configuration can be adopted in the case of three or more lamps. The configuration other than the load circuit 1 can adopt the circuit configuration of each of the above-described embodiments.

(Embodiment 14) As shown in FIG. 33, this embodiment differs from the configuration of Embodiment 1 shown in FIG.
A series circuit of a load circuit 1a and the capacitor C _3a of DC blocking is obtained by parallel connection in addition to the one switching element Q ₂ '. Load circuit 1a includes the same manner as the load circuit 1 is connected to the discharge lamp La _1a of the secondary side of the leakage transformer T _1a, the configuration of connecting the capacitor C _2a for resonance between the filaments of the discharge lamp La _1a.

The operation relating to the load circuit 1 is the operation described in the first embodiment, and the load circuit 1a operates in the same manner as the conventional configuration shown in FIG. Load circuit 1a in steady state
The operation relating to will be briefly described. Now, when the switching element Q ₁ ′ is turned on, a current flows through the path of the capacitor C ₁ → the switching element Q ₁ ′ → the load circuit 1a → the capacitor C _3a → the capacitor C ₁ . During this period, the capacitor C _3a
Is charged.

On the other hand, immediately after the switching element Q ₁ ′ is turned off and the switching element Q ₂ ′ is turned on, the energy stored in the load circuit 1 a (leakage transformer T _{1 a} ) is released and the load circuit 1 a → A current flows through the path of the capacitor C _3a → the parasitic diode of the switching element Q ₂ ′ → the load circuit 1a. Thereafter, when the energy of the load circuit 1a is released, the discharge of the capacitor C _3a is started, and the capacitor C _3a → the load circuit 1a → the switching element Q ₂ ′ →
A current flows through the path of the capacitor _C3a , and a current flows in the load circuit 1a in a direction opposite to that of the current.

Next, when the switching element Q ₂ ′ is turned off and the switching element Q ₁ ′ is turned on, the load circuit 1
a → parasitic diode of the switching element Q ₁ ′ → capacitor C ₁ → capacitor C _3a → energy stored in the load circuit 1a (leakage transformer T _1a ) is released through the path of the load circuit 1a. When energy stored in the load circuit 1a is released, the switching element Q from the capacitor C _1
The state returns to the state where the current flows through the load circuit 1a through ₁ ', and the direction of the current flowing through the load circuit 1a is reversed.
That is, the switching elements Q ₁ ′ and Q ₂ ′ are turned on and off, so that an alternating high-frequency current flows through the load circuit 1 a.

Thus, the above operation is performed by the capacitor C
_This is an operation of a half-bridge type inverter circuit using ₁ as a power supply, and a circuit including the load circuit 1a and the capacitor _C3a has no function of reducing input current distortion. That is, since the lamp current of the discharge lamp La _1a depends on the power supply voltage of the inverter circuit, the lamp current of the discharge lamp La _1a becomes substantially constant if the capacity of the capacitor C _{1 serving as} the power supply is sufficiently large. As a result, the combined light output of the two discharge lamps La ₁ and La _1a has more fluctuation than the combined light output of the _two discharge lamps La ₁ and La ₂ having the circuit configuration shown in FIG. Less. This is because, in the configuration shown in FIG. 32A, the light outputs of both the discharge lamps La ₁ and La ₂ fluctuate and change in the same direction, whereas in the present embodiment, one of the discharge lamps La ₁ and La ₂ changes. This is because the light output of La ₁ fluctuates, but the light output of the other discharge lamp La _1a does not fluctuate.

In the configuration of the present embodiment, even if one of the two discharge lamps La ₁ and La _1a comes off, the remaining discharge lamps will remain lit. For example, discharge lamp L
When a _1a is deviated, the resonance frequency of the resonance circuit formed by the inductance on the primary side of the leakage transformer T _1a and the capacitor C _2a is adjusted to be slightly advanced with respect to the switching frequency, so that the remaining frequency is reduced. Discharge lamp La
_The current flowing through the switching elements Q ₁ ′ and Q ₂ ′ when ₁ is turned on can be a combined current of a leading phase and a lagging phase, which is smaller than the lagging current flowing when only the discharge lamp La ₁ is turned on. The peak value of the current flowing through the switching elements Q ₁ ′, Q ₂ ′ can be suppressed.

If the frequency characteristics of the two discharge lamps La and La _1a are slightly shifted, a change in power supply and a change in load can be prevented.
The output can be kept almost constant. Other configurations and operations are the same as those of the first embodiment. (Embodiment 15) In this embodiment, as shown in FIG.
In the configuration of the first embodiment shown in FIG.
A lamp La ₃ for direct current lighting is connected between both ends of ₁ via a switching element Tr ₃ . Lamp La ₃
For example, an incandescent light bulb or the like can be used.

In this configuration, the lamp current flowing through the lamp La ₃ is substantially constant if the capacity of the capacitor C ₁ is sufficiently large. Therefore, the fluctuation of the combined light output of the discharge lamp La ₁ and the lamp La ₃ is as follows. This is less than when the circuit configuration shown in FIG. In this circuit configuration, by turning on and off the switching element Tr _3, it is possible to arbitrarily control the ratio of the light output of the discharge lamp La ₁ and the lamp La _3. Other configurations and operations are the same as those of the first embodiment.

In each of the above embodiments, the discharge lamp La ₁ lit by high-frequency alternating current is exemplified as the load, but the load is not limited to the discharge lamp La ₁ . When DC power is required to be supplied to the load, a DC voltage obtained by rectifying the secondary output of the leakage transformer T ₁ with the full-wave rectifier DB ₁ is applied to the load 5 as shown in FIG. The load circuit 1 may be configured to perform

The technical ideas of the above-described embodiments can be used in appropriate combinations.

[0090]

According to the first aspect of the present invention, there is provided a full-wave rectifier configured by bridge-connecting rectifying elements for full-wave rectification of an AC power supply, and a first smoothing rectifier connected between the DC output terminals of the full-wave rectifier. , A first switching element and a second switching element connected in parallel to the first capacitor and alternately turned on and off at a frequency higher than the power supply frequency of the AC power supply, and a first switching and a second switching element And a pair of rectifiers different from the rectifier connected in parallel to each other, and a second rectifier connected between both ends of the AC power supply.
And a load circuit connected between a connection point between the first switching element and the second switching element and a connection point between the second and third capacitors. And a fourth capacitor connected in parallel to at least one of the rectifying elements constituting the full-wave rectifier. The input current can be passed over substantially the entire power supply cycle, and the switching element is provided. During one cycle of the switching operation, each switching element is turned on once and the input current is caused to flow twice, so that the input current distortion is small and power can be supplied directly from the AC power supply to the load circuit. Therefore, there is an advantage that the power supply efficiency is increased. In addition, during one cycle of the switching operation of the switching elements, each switching element is turned on once and the input current is caused to flow twice, so that the peak value of the input current is small and the high frequency blocking for the input section from the AC power supply is performed. When a filter circuit is provided, there is an advantage that a small filter circuit can be used. Furthermore, there is an advantage that the number of parts is relatively small and the configuration is simple.

According to a second aspect of the present invention, the load circuit includes a transformer and a load connected to a secondary side of the transformer, and both ends of a primary winding of the transformer are both ends of the load circuit. Since the load circuit has a transformer configuration,
There is an advantage that a constant load current can flow by removing low frequency components to the load provided on the next side. Also, if the impedance on the primary side of the transformer is increased, there is an advantage that the inrush current can be further reduced.

According to a third aspect of the present invention, the load circuit is connected between the first inductor, the discharge lamp connected in series to the first inductor, and the non-power supply side terminal of the discharge lamp, and the load circuit resonates with the first inductor. A fifth capacitor constituting a circuit is provided, and both ends of a series circuit of the first inductor and the discharge lamp serve as both ends of a load circuit. Since no transformer is used, there is no loss due to the transformer, and the load is reduced. There is an advantage that the power supply efficiency to the power supply is further increased. In addition, since no path for charging the first capacitor is formed when there is no load, there is an advantage that the rush current becomes almost zero when there is no load.

According to a fourth aspect of the present invention, there is provided a control circuit capable of adjusting the on / off switching frequency of the first switching element and the second switching element.
There is an advantage that the input current can be adjusted or the power supplied to the load can be adjusted while keeping the ON period of the switching element substantially constant. As a result, if the load is a discharge lamp, control of dimming, preheating, starting, lighting, and the like can be performed. Further, when the power supplied to the load suddenly changes and stress is applied to the circuit components, this can be avoided by changing the switching frequency.

According to a fifth aspect of the present invention, there is provided a control circuit capable of adjusting the ON periods of the first switching element and the second switching element, and the input current is adjusted while the switching frequency is kept substantially constant. This has the advantage that the power supplied to the load can be adjusted. As a result, if the load is a discharge lamp, dimming, control of preheating, starting, lighting, and the like can be performed. Further, when the power supplied to the load suddenly changes and stress is applied to the circuit components, this can be avoided by changing the switching frequency.

According to a sixth aspect of the present invention, there is provided a means for detecting a voltage between both ends of the first capacitor, wherein the control circuit controls the second circuit so as to suppress a rise in the voltage between both ends of the first capacitor based on the detected voltage. The first switching element and the second switching element are controlled, and when the voltage across the first capacitor rises abnormally, the operation of the switching element is stopped or the output to the load is reduced. In addition, there is an advantage that stress can be prevented from being applied to the circuit components. Further, if the increase in the voltage across the first capacitor is suppressed to be kept substantially constant, there is an advantage that the power supplied to the load is stabilized. As a result, even if the load is a discharge lamp, an optical output with less flicker can be obtained.

The invention according to claim 7 includes means for detecting a voltage corresponding to the voltage applied to the transformer, and the control circuit controls the first circuit so as to suppress an increase in the voltage applied to the transformer based on the detected voltage. Control the switching element and the second switching element, and when the voltage applied to the load abnormally rises or when the load is short-circuited, the operation of the switching element is stopped or the output to the load is stopped. Has the advantage that it is possible to prevent stress on the circuit components.

The invention according to claim 8 is provided with means for detecting the voltage across the fourth capacitor, and the control circuit keeps the output to the load circuit substantially constant based on the voltage across the fourth capacitor. The first switching element and the second
Since the output to the load can be kept substantially constant, there is an advantage that stable operation of the load can be expected. In particular, when the load is a discharge lamp, an optical output with less flicker can be obtained.

According to a ninth aspect of the present invention, there is provided a means for detecting a current flowing in a load circuit, wherein the first switching element and the second switching element maintain the current flowing in the load circuit substantially constant based on the detected current. Since the element controls the element and the supply current to the load can be made substantially constant even when the voltage of the AC power supply fluctuates, there is an advantage that stable operation of the load can be expected. In particular, when the load is a discharge lamp, the fluctuation of the lamp current can be reduced to obtain an optical output with less flicker.

The tenth aspect of the present invention comprises means for varying the capacity of the fourth capacitor, and has the advantage that the input current can be adjusted according to the load and the input current distortion can be reduced. There is. For example, even when the load is a discharge lamp and dimming or switching of the load output is performed, the input current distortion can be reduced. Claim 1
The invention of the first aspect has a load circuit including a plurality of loads, and has an advantage that a plurality of loads can be driven simultaneously.

According to a twelfth aspect of the present invention, in parallel with one of the first switching element and the second switching element,
Alternatively, the second load circuit is connected in parallel with the first capacitor, and the output to the second load circuit can be made substantially constant without any special control, so that it is stable while simultaneously driving a plurality of loads. There is an advantage that a suitable drive is possible. In particular, when the load is a discharge lamp, an optical output with less flicker can be obtained. Further, even if one of the discharge lamps comes off, the other discharge lamp can be kept on.
Further, the power supplied to each load can be set to an appropriate ratio. Also, even if the voltage of the AC power supply fluctuates,
The load current as a whole can be almost constant,
By reducing the pulsating current of the lamp current, a light output with less flicker can be obtained.

According to a thirteenth aspect of the present invention, at least one of the first switching element and the second switching element is self-excited by feedback of a current flowing through a load circuit. Since it can be simplified or eliminated, there is an advantage that the number of parts can be further reduced. For example, if a transformer is provided in a load circuit and feedback is performed using an inductor provided on the secondary side of the transformer, the circuit automatically stops when an abnormality such as no load occurs. In addition, if the driving of one switching element is self-excited and the driving of the other switching element is separately controlled by an external signal, the power supplied to the load can be controlled. Control such as dimming and stopping can be easily performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is an operation explanatory view of the above.

FIG. 5 is an operation explanatory view of the above.

FIG. 6 is an operation explanatory view of the above.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is a circuit diagram showing a specific configuration of the above.

9 is an operation explanatory diagram of the circuit shown in FIG. 8;

FIG. 10 is an operation explanatory diagram of the circuit shown in FIG. 8;

FIG. 11 is a circuit diagram showing a second embodiment of the present invention.

FIG. 12 is a circuit diagram showing a third embodiment of the present invention.

FIG. 13 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 14 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 15 is an explanatory diagram of the operation of the above.

FIG. 16 is an operation explanatory view of the above.

FIG. 17 is an operation explanatory view of the above.

FIG. 18 is an operation explanatory view showing Embodiment 6 of the present invention.

FIG. 19 is a diagram illustrating the operation of the above.

FIG. 20 is an explanatory diagram of the operation of the above.

FIG. 21 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 22 is an explanatory diagram of the above operation.

FIG. 23 is a circuit diagram showing Embodiment 8 of the present invention.

FIG. 24 is a circuit diagram showing another example of the above circuit.

FIG. 25 is a circuit diagram showing a ninth embodiment of the present invention.

FIG. 26 is a circuit diagram showing a tenth embodiment of the present invention.

FIG. 27 is a circuit diagram showing another example of the above circuit.

FIG. 28 is a circuit diagram showing another example of the above circuit.

FIG. 29 is a circuit diagram showing Embodiment 11 of the present invention.

FIG. 30 is a circuit diagram showing another example of the circuit.

FIG. 31 is a circuit diagram showing a twelfth embodiment of the present invention.

FIG. 32 is a circuit diagram showing various circuit examples according to Embodiment 13 of the present invention.

FIG. 33 is a circuit diagram showing a fourteenth embodiment of the present invention.

FIG. 34 is a circuit diagram showing a fifteenth embodiment of the present invention.

FIG. 35 is a circuit diagram showing another example of a load according to the present invention.

FIG. 36 is a circuit diagram showing a conventional example.

FIG. 37 is a circuit diagram showing another conventional example.

[Explanation of symbols]

1 the load circuit 3 control circuit Vs AC power D ₁ to D ₆ diodes _{Q 1 ~Q 4, Q 1 '} , Q 2' switching element C ₁ capacitor C ₅₁ -C ₅₄ capacitor

Claims (13)

[Claims] 1. A full-wave rectifier configured by bridge-connecting a rectifying element and performing full-wave rectification on an AC power supply, a first smoothing capacitor connected between a DC output terminal of the full-wave rectifier, and a first capacitor. A first switching element and a second switching element connected in parallel to a capacitor and alternately turned on and off at a frequency higher than the power supply frequency of the AC power supply, and the first switching element and the second switching element connected in parallel to the first switching element and the second switching element, respectively. A pair of rectifier elements different from the rectifier element, a series circuit of a second capacitor and a third capacitor connected between both ends of the AC power supply, and a connection point of the first switching element and the second switching element. A load circuit connected between a connection point of the second capacitor and the third capacitor; and a load circuit connected to at least one of the rectifying elements constituting the full-wave rectifier. And a fourth capacitor connected in a column. 2. A load circuit comprising: a transformer;
2. A load connected to the secondary side, wherein both ends of a primary winding of the transformer are both ends of a load circuit.
The power supply as described. 3. The load circuit includes a first inductor and a first inductor.
And a fifth capacitor connected between the non-power supply side terminals of the discharge lamp and a first inductor to form a resonance circuit together with the first inductor, wherein the first inductor and the discharge lamp are connected in series. 2. The power supply device according to claim 1, wherein both ends of the circuit are both ends of the load circuit. 4. The power supply device according to claim 2, further comprising a control circuit capable of adjusting an on / off switching frequency of the first switching element and the second switching element. 5. The power supply device according to claim 2, further comprising a control circuit capable of adjusting an on-period of the first switching element and the second switching element. 6. A control circuit comprising: means for detecting a voltage across the first capacitor; wherein the control circuit controls the first switching element and the first switching element so as to suppress an increase in the voltage across the first capacitor based on the detected voltage. The power supply device according to claim 4 or 5, wherein the power supply device controls the second switching element. 7. A control device comprising: means for detecting a voltage corresponding to the voltage applied to the transformer, wherein the control circuit controls the first switching element and the second switching element to suppress an increase in the voltage applied to the transformer based on the detected voltage. The power supply device according to claim 2, wherein the power supply device controls two switching elements. 8. A control circuit for detecting a voltage between both ends of a fourth capacitor, wherein the control circuit controls the first switching so as to keep the output to the load circuit substantially constant based on the voltage between both ends of the fourth capacitor. 6. The device according to claim 4, wherein the device and the second switching device are controlled.
The power supply as described. 9. A method comprising: means for detecting a current flowing in a load circuit; and controlling the first switching element and the second switching element to keep the current flowing in the load circuit substantially constant based on the detected current. The power supply device according to claim 4 or 5, wherein: 10. The power supply device according to claim 2, further comprising means for varying a capacity of the fourth capacitor. 11. The power supply device according to claim 2, wherein the load circuit includes a plurality of loads. 12. A second load circuit is connected in parallel with one of the first switching element and the second switching element or in parallel with the first capacitor. 3. The power supply device according to 3. 13. The power supply according to claim 2, wherein at least one of the first switching element and the second switching element is self-excited by feedback of a current flowing through a load circuit. apparatus.