JP3590152B2 - DC power supply - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a DC power supply that rectifies and smoothes input AC power and supplies DC power to a load, and more particularly to a smoothing circuit of the DC power supply.
[0002]
[Prior art]
In order to convert the input AC (AC) power into DC (DC) power and supply it to the load, full-wave rectification is generally performed by a diode bridge. After that, the ripple is reduced or eliminated through a smoothing circuit. As a smoothing circuit for that purpose, a capacitor input type and a choke input type are well known.
[0003]
FIG. 14 is a circuit diagram showing an example of a rectifying / smoothing circuit of a capacitor input type. DC power obtained by full-wave rectifying AC power input from a commercial 50 Hz or 60 Hz AC power supply 31 by a diode bridge 32 and smoothing by a smoothing capacitor C4. The power is output to the load 33.
FIG. 15 is a waveform diagram showing an example of the voltage or current of each unit when the load 33 is a non-inductive, for example, a resistive load.
[0004]
FIGS. 15A and 15B are waveform diagrams of the voltage (current is the same) on the input side and the output side of the diode bridge 32 when the smoothing capacitor C4 is not connected. The input voltage (current) has a large ripple as shown in FIG.
When the smoothing capacitor C4 is connected as shown in FIG. 14, the voltage between its terminals, that is, the ripple of the voltage (current) input to the load 33 is greatly reduced as shown in FIG.
[0005]
[Problems to be solved by the invention]
However, since the frequency of the AC power supply 31, which is a commercial power supply, is low, the capacity of the smoothing capacitor C4 must be set large in order to reduce the ripple. However, the current for charging the smoothing capacitor C4 is as shown in FIG. Flows only when the instantaneous value of the voltage of the full-wave rectification shown in (c) exceeds the instantaneous value of the voltage between the terminals of the smoothing capacitor C4 shown in (C) of FIG. The corner is narrow. Therefore, the ineffective power increases, and the effective power decreases.
[0006]
Since a large-capacity capacitor must be charged at a small conduction angle, the average current value flowing to the load 33 in a short time as shown in the waveform diagram of the AC current on the input side shown in FIG. Since a large peak current, which is several times to ten and several times as large as the above, flows, the power factor is deteriorated, the life of the smoothing capacitor C4 is shortened, and high frequency noise is generated. Therefore, the instantaneous drop of the power supply voltage of the AC power supply 31 and the high-frequency noise adversely affect other devices connected to the same AC line.
[0007]
Although not shown, the choke input type rectifying / smoothing circuit provided with a choke coil between the diode bridge 32 and the smoothing capacitor C4 shown in FIG. 14 has a lower output voltage with respect to the load than the capacitor input type. The inductivity of the coil and the reduction of the output voltage act in combination to increase the conduction angle, and accordingly the peak current on the AC power supply 31 side is reduced and the power factor is improved.
[0008]
However, also in this case, since the frequency of the AC power supply 31 is low, a choke coil having an inductance of several mH or more (which becomes larger as the required current value becomes smaller) is required, although it depends on the required current value of the load 33. Become. Therefore, there is a problem that the DC power supply device is increased in weight and size, and the cost is significantly increased.
[0009]
The present invention has been made in view of the above points, and has as its object to suppress the weight, size, and cost of a DC power supply device, and to improve the power factor.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a DC power supply that rectifies and smoothes AC input power and supplies DC power to a load, wherein a diode bridge that full-wave rectifies AC input power, and an output terminal of the diode bridge. One of the positive and negative lines connecting the input end of the load is a common line, the other is a hot line for the common line, and first and second choke coils connected in series to the hot line are provided. It is as follows.
[0011]
That is, a smoothing capacitor having one end connected to a connection point between the first choke coil and the second choke coil, and switching for charging the smoothing capacitor connected between the other end of the smoothing capacitor and the common line. A voltage is detected by detecting a voltage at a connection point between a first choke coil and a second choke coil or an input terminal on the hot line side of the load, and a parallel circuit of a diode for discharging the element and the smoothing capacitor to a load. And a switching control circuit for outputting a drive signal for opening and closing the switching element at high speed to the switching element only during a period in which the instantaneous value of the voltage is larger than the DC voltage excluding the ripple from the detection voltage. .
[0012]
Alternatively, a smoothing capacitor connected between a connection point between the first choke coil and the second choke coil and a common line, a switching element for charging the smoothing capacitor, and discharging from the smoothing capacitor to the load. Any one of a connection point between the first choke coil and the second choke coil, an input terminal on the hot line side of the load, or a terminal on the hot line side of the smoothing capacitor. A switching control circuit that detects a voltage at one location and outputs a drive signal to open and close the switching element at high speed only during a period in which the instantaneous value of the detected voltage is greater than the DC component voltage excluding the ripple component from the detected voltage. And a primary coil for receiving a drive signal output by the switching control circuit, and a drive signal input terminal for the switching element. In which the drive transformer consisting of the connected secondary coils provided.
[0013]
Alternatively, a smoothing capacitor connected between a connection point between the first choke coil and the second choke coil and a common line, a switching element for charging the smoothing capacitor, and discharging from the smoothing capacitor to the load. Any one of a connection point between the first choke coil and the second choke coil, an input terminal on the hot line side of the load, or a terminal on the hot line side of the smoothing capacitor. A switching control circuit that detects a voltage at one location and outputs a drive signal to open and close the switching element at high speed only during a period in which the instantaneous value of the detected voltage is greater than the DC component voltage excluding the ripple component from the detected voltage. A leak resistor connected between the drive signal input terminals of the switching element, and one end of the leak resistor and the switching resistor. It is provided with a and CR coupling circuit comprising a coupling capacitor connecting the output of the drive signal control circuit.
[0014]
In the DC power supply device described above, the first and second choke coils are formed from one end of one choke coil having an intermediate tap to the intermediate tap and from the intermediate tap to the other end, and the intermediate tap of the choke coil is It may be a connection point between the first choke coil and the second choke coil.
[0015]
Alternatively, at least one of the positive and negative output terminals of the diode bridge, the positive and negative input terminals of the load, or the connection point between the first choke coil and the second choke coil and the common line. It is preferable to provide a small-capacity capacitor for bypassing high-frequency noise.
Further, the load may be a constant voltage DC / DC converter.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
In the embodiments described below, a case will be described in which a negative line is a common line, a positive line is a hot line, and a transistor is used as a switching element. When an FET (field effect transistor) or a MOS-FET is used as a switching element, the emitter, base, and collector of the transistor may be read as a source, a gate, and a drain, respectively.
[0017]
FIG. 1 is a circuit diagram showing an example of a configuration of a first embodiment of a DC power supply device according to the present invention, and includes a diode bridge 2 forming a rectifying unit, and first and second units forming a smoothing unit. It comprises choke coils CH1 and CH2, which are choke coils, a smoothing capacitor C1, a parallel circuit 4 of a transistor Q1 and a diode D1, and a switching control circuit (SWCC) 5.
[0018]
The diode bridge 2 converts the AC power input from the AC power supply 1 into full-wave rectified DC power, and supplies the DC power to the load 3 via the smoothing unit.
The negative output terminal of the diode bridge 2 and the negative input terminal of the load 3 are directly connected by a common line, and the hot line connecting the positive output terminal of the diode bridge 2 and the positive input terminal of the load 3 includes a choke coil. CH1 and CH2 are connected in series.
[0019]
A connection point A between the choke coils CH1 and CH2 is connected to a positive terminal of a smoothing capacitor C1, and a parallel circuit 4 of a transistor Q1 and a diode D1 is connected between the negative terminal and a common line.
Since a current flows in a direction in which the smoothing capacitor C1 discharges through the diode D1 constituting the parallel circuit 4, the NPN transistor Q1 has an emitter connected to the common line and a collector connected to the negative terminal of the smoothing capacitor C1, respectively. When the base is more positive than the common line, a current flows in a direction for charging the smoothing capacitor C1.
[0020]
The switching control circuit 5 having the common terminal connected to the common line inputs the voltage at the connection point A of the choke coils CH1 and CH2 to its detection terminal, and further smoothes the instantaneous value of the input detection voltage and the detection voltage. Compared with the DC voltage from which the ripple component has been removed, only the period when the instantaneous value of the detected voltage is higher, for example, a frequency of several KHz to several hundred KHz, which is much higher than the frequency of the AC power supply 1 Is output from its output terminal to the base of the transistor Q1 to open and close the transistor Q1 at high speed.
[0021]
FIG. 2 is a waveform diagram showing an example of each instantaneous value of the voltage and current of each part of the DC power supply device shown in FIG. 1. FIGS. 2A, 2B and 2C are diode bridges, respectively. 2 is a voltage waveform diagram of the input side, the output side, and the connection point A, that is, the positive terminal of the smoothing capacitor C1, wherein (D) and (E) show the input side current of the diode bridge 2 and the charging current of the smoothing capacitor C1. The respective waveform diagrams are shown.
[0022]
Vd indicated by broken lines in (B) and (C) of FIG. 2 are the voltages of the respective DC components. Strictly speaking, there is a difference due to the voltage drop due to the resistance component of the choke coil CH1. Since they are slight, they can be considered the same. ΔV shown in FIG. 2C is a peak-to-peak value of ripple.
[0023]
The charging current of the smoothing capacitor C1 flowing through the choke coil CH1 is at a frequency much higher than the frequency of the AC power supply 1 or a frequency twice as high as that of the AC power supply 1 (by full-wave rectification) as shown in FIG. Since the switching is performed, even if the inductance is a small value, it works sufficiently as a choke input type, and instead of slightly lowering the output voltage to the load 3, the conduction angle is changed as shown in FIG. And its peak current is greatly reduced.
[0024]
That is, during the charging period in which the instantaneous value of the voltage at the connection point A is higher than the voltage between the terminals of the common line of the smoothing capacitor C1, the current for charging the smoothing capacitor C1 via the choke coil CH1 is far higher than the frequency of the AC power supply 1. Since the switching is performed at a higher frequency, the inductance of the choke coil CH1 can be much smaller than that of a normal choke input type, and the size and weight can be reduced.
[0025]
Further, the discharge current of the smoothing capacitor C1 is supplied to the load 3 via the choke coil CH2 and the diode D1. Even if the choke coil CH1 is small and lightweight, its effect is great, so that the frequency is twice the frequency of the AC power supply 1. The choke coil CH2, which is expected to have a choke effect, can also be reduced in size and weight.
Therefore, both the choke coils CH1 and CH2 are reduced in size and weight, and the cost can be significantly reduced.
[0026]
The reason why the starting terminal of the switching control circuit 5 is connected to the hot line on the output side of the diode bridge 2 is to obtain the power of the power supply at the initial stage when the power is turned on. The DC voltage obtained by removing the ripple component from the detection voltage input to the terminal operates as power supply power.
[0027]
A small-capacity capacitor Cp for high-frequency bypass connected between the positive and negative output terminals of the diode bridge 2, between the positive and negative input terminals of the load 3, or between the connection point A and the common line as shown by a broken line is: If at least one or two places are provided at least at the most effective place, the high frequency noise caused by the switching of the charging current according to the drive signal shown in FIG. An adverse effect on the load 3 can be prevented.
[0028]
For example, as shown in FIG. 2D, the high frequency noise due to the switching of the charging current of the smoothing capacitor C1 by the transistor Q1 does not appear in the current of the AC power supply 1. The same applies to the current of the load 3 not shown.
[0029]
FIG. 3 is a circuit diagram showing an example of the configuration of the second embodiment of the DC power supply device according to the present invention. The difference from the first embodiment shown in FIG. 1 is that the choke coils CH1 and CH2 are different from each other. Instead of detecting the voltage at the connection point A, the voltage at the input terminal of the load 3 on the hot line side, that is, the voltage at the positive input terminal is input and used as the detected voltage. The description is omitted.
[0030]
The voltage waveform at the positive input terminal of the load 3 is smaller than the voltage waveform at the connection point A shown in FIG. 2C by the amount of ripple ΔV that has passed through the choke coil CH2. The operation of the circuit 5 is exactly the same, and so is its effect.
[0031]
FIG. 4 is a circuit diagram showing an example of the configuration of the third embodiment of the DC power supply device. The difference from the first embodiment shown in FIG. 1 is that the first and second choke coils CH1 are different from the first embodiment. , CH2, a single choke coil CH3 provided with an intermediate tap B is connected in series to a hot line, and other identical portions are denoted by the same reference numerals and description thereof is omitted.
[0032]
That is, the left side from the intermediate tap B of the choke coil CH3 corresponds to the first choke coil CH1, the right side from the intermediate tap B corresponds to the second choke coil CH2, and the intermediate tap B is the first and second choke coils. It corresponds to the connection point A of CH1 and CH2. The major difference in performance is that the left and right coils of the intermediate tap B are magnetically coupled to each other.
[0033]
According to the result of an experimental circuit configuration, the positive / negative of the load 3 is better in the case where the intermediate tap B is provided and one choke coil in which the two left and right coils are magnetically coupled is used. The ripple reduction effect between the input terminals was excellent.
Further, the use of one choke coil reduces the size and weight and is superior in cost as compared with the case of using two choke coils, and is superior to the second embodiment shown in FIG. It goes without saying that a similar effect can be obtained when applied.
[0034]
The first to third embodiments described above with reference to FIGS. 1, 3 and 4 are respectively based on the invention described in claim 1, and include a parallel circuit 4 including a transistor Q1 and a diode D1. The smoothing capacitor C1 is connected to the connection point A or the intermediate tap B on the hot line side on the common line side, and the output terminal of the switching control circuit 5 is directly connected to the base of the transistor Q1.
[0035]
FIG. 5 is a circuit diagram showing an example of the configuration of the fourth embodiment of the DC power supply device. The difference from the first embodiment shown in FIG. 1 is that the output terminal of the switching control circuit 5 and the transistor Instead of directly connecting to the base of Q1, a drive transformer 6 in which a primary coil and a secondary coil are DC-insulated is provided, and a drive signal is transmitted through the transformer 6.
[0036]
That is, the primary coil of the drive transformer 6 is connected between the output terminal of the switching control circuit 5 and the common line, and the secondary coil is connected between the base and the emitter of the transistor Q1, which is between the input terminals of the switching element. When the output terminal of the switching control circuit 5 is positive with respect to the common line, the base of the transistor Q1 is set to be positive with respect to its emitter. (There is no problem even if the polarity of the secondary coil is reversed.)
[0037]
FIG. 6 is a circuit diagram showing an example of the configuration of the fifth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that of the first embodiment (FIG. 1). As in the third embodiment (FIG. 4), one choke coil CH3 having an intermediate tap B is provided instead of the first and second choke coils CH1 and CH2. Is the same as in the fourth embodiment.
[0038]
Therefore, the operations and effects of the fourth and fifth embodiments shown in FIGS. 5 and 6 are exactly the same as those of the first and third embodiments (FIGS. 1 and 4), respectively, and will be described in detail. Is omitted.
Although not particularly shown, in the fourth and fifth embodiments, the detection terminal of the switching control circuit 5 is connected to the hot line side of the load 3 as in the second embodiment shown in FIG. It goes without saying that the same operation and effect can be obtained by connecting to the input terminal.
[0039]
However, the output transformer of the switching control circuit 5 is not directly connected to the base of the transistor Q1, but the drive transformer 6 that insulates both of them directly is provided, so that the parallel circuit 4 including the transistor Q1 and the diode D1 is connected. There is an effect that the smoothing capacitor C1 is always provided on the common line side, that is, it is not necessary to directly connect the emitter of the transistor Q1 to the common line.
[0040]
FIG. 7 is a circuit diagram showing an example of the configuration of the sixth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that a parallel circuit comprising a transistor Q1 and a diode D1 is provided. 4, the negative terminal of the smoothing capacitor C1 is connected to the common line, and the connection point A between the positive terminal and the first and second choke coils CH1 and CH2. And that the parallel circuit 4 is connected between them.
[0041]
As shown in FIG. 7, even if the emitter of the transistor Q1 is separated from any of the common line and the hot line and set at a floating level, the secondary coil of the drive transformer 6 is connected between the base and the emitter. Then, since the secondary coil is insulated from the primary coil in a DC manner, there is no possibility that a trouble such as destruction of the transistor Q1 may occur, and the secondary coil operates normally.
[0042]
Although not particularly shown, also in the sixth embodiment, as in the second embodiment (FIG. 3), the detection terminal of the switching control circuit 5 is connected to the input terminal of the load 3 on the hot line side. Thus, the voltage may be detected without any problem.
[0043]
FIG. 8 is a circuit diagram showing an example of the configuration of the seventh embodiment of the DC power supply device. The difference from the sixth embodiment shown in FIG. Instead of connecting to the connection point A between the first and second choke coils CH1 and CH2, it is connected to the positive terminal of the smoothing capacitor C1 and the voltage between the terminals is detected.
[0044]
In the seventh embodiment shown in FIG. 8, the instantaneous value of the detected voltage is slightly different from the instantaneous value of the voltage at the connection point A, but the instantaneous value of the charging current and the instantaneous value of the discharging current flow through the smoothing capacitor C1. , The voltage drop due to the transistor Q1 or the diode D1 is small, and is ignored compared to the voltage (for example, 100 V to 140 V) in which the AC power of the AC power supply 1 is full-wave rectified by the diode bridge 2 and charges the smoothing capacitor C1. I can do it.
[0045]
The fourth to seventh embodiments described above with reference to FIGS. 5 to 8 are according to the second aspect of the present invention. The drive signal output from the switching control circuit 5 is transmitted through the drive transformer 6. To the transistor Q1 which is a switching element.
Also, in the sixth and seventh embodiments (FIGS. 7 and 8), similarly to the fifth embodiment (FIG. 6), the first and second choke coils CH1 and CH2 are connected to the intermediate tap B. Can be replaced with a single choke coil CH3.
[0046]
FIG. 9 is a circuit diagram showing an example of the configuration of the eighth embodiment of the DC power supply device. The difference from the fourth embodiment shown in FIG. 5 is that the primary coil and the secondary coil are different from each other. Instead of the drive transformer 6 which is insulated from the direct current, a CR coupling circuit 7 comprising a capacitor C2 which is a coupling capacitor whose input side and the output side are also insulated from the direct current and a resistor R1 which is a leak resistance is provided. The driving signal output from the switching control circuit 5 via the coupling circuit 7 is transmitted to the transistor Q1.
[0047]
That is, as shown in FIG. 9, the resistor R1 is connected between the base and the emitter of the transistor Q1, which is between the drive signal input terminals of the switching element, and the base terminal of the resistor R1 is connected to the output terminal of the switching control circuit 5. And a capacitor C2 for cutting off the direct current is connected, and the constant, which is the product of the capacitance value of the capacitor C2 and the resistance value of the resistor R1, is set to be larger than the reciprocal (cycle) of the frequency of the drive signal. .
[0048]
Therefore, the operation and effects are exactly the same as those of the drive transformer 6 used in the fourth embodiment (FIG. 5).
Also, in the ninth to eleventh embodiments shown in FIGS. 10 to 12, respectively, the driving transformer 6 in the fifth to seventh embodiments shown in FIGS. 6 to 8 is replaced with a CR coupling circuit 7. Therefore, as in the eighth embodiment (FIG. 9), the operation and effect are completely the same, and the same portions are denoted by the same reference numerals and description thereof will be omitted.
[0049]
The eighth to eleventh embodiments described above with reference to FIGS. 9 to 12 are according to the third aspect of the present invention, and the drive signal output from the switching control circuit 5 is transmitted to the CR coupling circuit 7. The signal is transmitted to the transistor Q1 as a switching element via the switching element.
Also, in the tenth and eleventh embodiments (FIGS. 11 and 12), the first and second choke coils CH1 and CH2 can be replaced with one choke coil CH3 having an intermediate tap B. .
[0050]
The above-described first to eleventh embodiments and their respective modified circuits (not shown) use two or one choke coil to increase the conduction angle as compared with the capacitor input type, and the AC power supply 1 It has the characteristics of reducing the inductance of the choke coil, small size, light weight and low cost by switching the charging current of the smoothing capacitor C1 at high speed while having the choke input type characteristic to suppress the peak current from ing.
[0051]
However, the DC power output from these DC power supplies has a reduced or eliminated ripple component, but the output voltage has a constant voltage with respect to input voltage fluctuations of the AC power supply 1 and current fluctuations flowing through the load 3. There is no gender.
Further, since the common line and the hot line connected to the load 3 are completely floating with respect to the AC power supply 1 whose one side is grounded to the ground, there is a possibility that touching any line may cause an electric shock. .
[0052]
Therefore, if the load 3 has only a problem of flicker due to the commercial frequency, for example, an illumination lamp of a TV studio, a stage where TV is relayed, a stadium, or the like, the constant voltage property is hardly a problem and the electric shock is not affected. Since there is no fear, the effect of using a relatively small-capacity choke coil to reduce the ripple in response to the large power demand and reducing the capacity of the smoothing capacitor along with it is extremely large.
As described above, although it is effective for certain limited applications, it is dangerous to use it for many general applications as it is, and it is not suitable for applications requiring constant voltage characteristics.
[0053]
However, if a DC / DC converter having a constant voltage characteristic is generally connected as a load, there is no problem in terms of the constant voltage characteristic. In particular, a DC / DC converter in which the input side and the output side are insulated, for example, switching Connecting a regulator eliminates the risk of electric shock.
[0054]
FIG. 13 is a circuit diagram illustrating an example of a configuration of a switching regulator that is a constant voltage DC / DC converter in which input and output sides combined as a load 3 are insulated from each other.
The operation and effects of the switching regulator shown in FIG. 13 are well known, and therefore will be briefly described.
[0055]
DC power input to the positive and negative terminals of the input side Vin is turned on / off at high speed by a transistor (or FET) Q2 which is a switching element connected in series with the primary coil Np of the transformer 10. The AC power induced in the secondary coil Ns of the transformer 10 is converted into DC power rectified and smoothed by a rectifying and smoothing circuit 11 including a rectifying diode D2, a commutating diode D3, a choke coil CH4, and a smoothing capacitor C3. It is output from the positive and negative terminals of Vout.
[0056]
The control circuit 12 that outputs a driving pulse to the transistor Q2 detects the voltage Vout of the DC power to be output, and increases the on-duty ratio of the driving pulse if the output voltage is lower than a preset output voltage, and decreases the on-duty ratio if the output voltage is higher. Thus, even if the input voltage or the output current fluctuates, control is performed so that the set output voltage is maintained.
[0057]
Such a DC / DC converter is connected as the load 3, that is, the DC power supply according to the present invention is used in combination with the DC / DC converter as the DC power supply, and the purpose is to provide constant-voltage DC power output from the DC / DC converter. By outputting to an apparatus or a device, it is possible to safely cope with a wide range of applications.
[0058]
In the embodiments described above, all the negative lines are common lines, and the positive lines are hot lines. However, even if the positive lines are common lines and the negative lines are hot lines, If the polarities of the smoothing capacitor C1 and the diode D1 and the direction of the current flowing through the transistor Q1 are reversed, it goes without saying that the present invention can be applied in exactly the same manner.
[0059]
【The invention's effect】
As described above, the DC power supply according to the present invention is small, lightweight, inexpensive, and has an improved power factor.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an example of a first embodiment of a DC power supply device according to the present invention.
FIG. 2 is a waveform diagram showing an example of a voltage or a current of each unit of the DC power supply device shown in FIG.
FIG. 3 is a circuit diagram showing an example of a second embodiment of the DC power supply device according to the present invention.
FIG. 4 is a circuit diagram showing an example of a third embodiment of the DC power supply device.
FIG. 5 is a circuit diagram illustrating an example of a fourth embodiment of a DC power supply device.
FIG. 6 is a circuit diagram illustrating an example of a fifth embodiment of a DC power supply device.
FIG. 7 is a circuit diagram illustrating an example of a sixth embodiment of a DC power supply device.
FIG. 8 is a circuit diagram illustrating an example of a seventh embodiment of a DC power supply device.
FIG. 9 is a circuit diagram illustrating an example of an eighth embodiment of a DC power supply device.
FIG. 10 is a circuit diagram illustrating an example of a ninth embodiment of a DC power supply device.
FIG. 11 is a circuit diagram illustrating an example of a DC power supply device according to a tenth embodiment;
FIG. 12 is a circuit diagram illustrating an example of an eleventh embodiment of a DC power supply device.
FIG. 13 is a circuit diagram showing an example of a DC / DC converter connected to the DC power supply according to the present invention.
FIG. 14 is a circuit diagram showing a conventional capacitor input type rectifying / smoothing circuit.
15 is a waveform chart showing an example of a voltage or a current of each part of the rectifying / smoothing circuit shown in FIG.
[Explanation of symbols]
1: AC power supply 2: Diode bridge 3: Load 4: Parallel circuit 5: Switching control circuit 6: Drive transformer 7: CR coupling circuit A: Connection point B: Middle tap C1: Smoothing capacitor C2: Capacitor (coupling capacitor)
Cp: small-capacity capacitor CH1: first choke coil CH2: second choke coil CH3: choke coil with an intermediate tap D1: diode Q1: transistor (switching element)
R1: resistance (leak resistance)

Claims (6)

In a DC power supply that rectifies and smoothes AC input power and supplies DC power to a load,
A diode bridge for full-wave rectification of the AC input power;
Of the positive and negative lines connecting the output terminal of the diode bridge and the input terminal of the load, one of them is a common line, and the other is a hot line for the common line.
First and second choke coils connected in series to the hot line;
A smoothing capacitor having one end connected to a connection point between the first choke coil and the second choke coil;
A parallel circuit connected between the other end of the smoothing capacitor and the common line, a switching element for charging the smoothing capacitor and a diode for discharging the smoothing capacitor to the load.
A voltage at a connection point between the first choke coil and the second choke coil or a voltage at an input terminal on the hot line side of the load is detected, and an instantaneous value of the detected voltage is a direct current obtained by removing a ripple component from the detected voltage. And a switching control circuit for outputting a drive signal for opening and closing the switching element at a high speed to the switching element during a period greater than a minute voltage . In a DC power supply that rectifies and smoothes AC input power and supplies DC power to a load,
A diode bridge for full-wave rectification of the AC input power;
Of the positive and negative lines connecting the output terminal of the diode bridge and the input terminal of the load, one of them is a common line, and the other is a hot line for the common line.
First and second choke coils connected in series to the hot line;
A smoothing capacitor connected between the connection point between the first choke coil and the second choke coil and the common line, a switching element for charging the smoothing capacitor, and discharging from the smoothing capacitor to the load; A series circuit consisting of a parallel circuit with a diode for causing
Detecting the voltage at any one of the connection point between the first choke coil and the second choke coil, the input terminal on the hot line side of the load or the hot line side terminal of the smoothing capacitor, A switching control circuit that outputs a drive signal for opening and closing the switching element at a high speed only during a period in which the instantaneous value of the detection voltage is larger than a DC component voltage excluding a ripple component from the detection voltage;
A DC power supply device comprising: a primary coil for inputting a drive signal output by the switching control circuit; and a drive transformer including a secondary coil connected between drive signal input terminals of the switching element. In a DC power supply that rectifies and smoothes AC input power and supplies DC power to a load,
A diode bridge for full-wave rectification of the AC input power;
Of the positive and negative lines connecting the output terminal of the diode bridge and the input terminal of the load, one of them is a common line, and the other is a hot line for the common line.
First and second choke coils connected in series to the hot line;
A smoothing capacitor connected between the connection point between the first choke coil and the second choke coil and the common line, a switching element for charging the smoothing capacitor, and discharging from the smoothing capacitor to the load; A series circuit consisting of a parallel circuit with a diode for causing
Detecting the voltage at any one of the connection point between the first choke coil and the second choke coil, the input terminal on the hot line side of the load or the hot line side terminal of the smoothing capacitor, A switching control circuit that outputs a drive signal for opening and closing the switching element at a high speed only during a period in which the instantaneous value of the detection voltage is larger than a DC component voltage excluding a ripple component from the detection voltage;
A CR coupling circuit comprising a leak resistor connected between the drive signal input terminals of the switching element and a coupling capacitor connecting one end of the leak resistor and an output terminal of the drive signal of the switching control circuit is provided. Characteristic DC power supply. The DC power supply device according to any one of claims 1 to 3,
The first and second choke coils are formed from one end of one choke coil having an intermediate tap to the intermediate tap and from the intermediate tap to the other end,
A DC power supply device, wherein an intermediate tap of the choke coil is a connection point between the first choke coil and the second choke coil. The DC power supply according to any one of claims 1 to 4,
At least one of between the positive and negative output terminals of the diode bridge, between the positive and negative input terminals of the load, or between the connection point between the first choke coil and the second choke coil and the common line. A direct-current power supply device comprising a small-capacity capacitor for bypassing high-frequency noise at one location. The direct-current power supply according to any one of claims 1 to 5,
A DC power supply, wherein the load is a constant voltage DC / DC converter.

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