JP3821156B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device used in various electronic devices, and particularly as a non-contact power supply device used in small portable devices such as cordless phones, mobile phones, PHS, camera-integrated video, personal computers and the like. The present invention relates to a useful power supply device.

  2. Description of the Related Art Generally, a power supply apparatus that obtains an output on a secondary side by resonating the voltages of a primary coil of a switching transformer and capacitors connected to both ends of the coil is known.

  As means for obtaining a stabilized output on the secondary side, various circuit configurations for controlling the primary side, circuit configurations for controlling the secondary side, and the like are used.

  First, as a means for controlling the primary side, a control circuit is provided on the primary side, and as one of means for stabilizing oscillation, the gate signal of the switching element is transferred to the switching element by an impedance circuit composed of a series circuit of a resistor and a diode. FIG. 15 is a circuit diagram illustrating a conventional power supply apparatus that feeds back to the output and controls and stabilizes the on / off period of switching. According to the figure, the input power source 1 is a DC voltage rectified and smoothed from a commercial power source, and a series circuit of a capacitor 2 and a starting circuit composed of a resistor 2 is connected to both ends of the input power source 1 and the primary of the switching transformer. A series circuit of the side coil 4 and the switching element 5 is connected, and a capacitor 6 is connected to both ends of the primary side coil 4 of the switching transformer.

  Further, the connection point between the resistor 2 and the capacitor 3 is connected to the drain of the switching element 5 through a series circuit of the resistor 7 and the diode 8, and is connected to the gate of the switching element 5 through the control winding 9 of the switching transformer.

  Further, a capacitor 11 is connected to both ends of the secondary coil 10 of the switching transformer, and a capacitor 13 is connected via a diode 12 so that an output is obtained at both ends of the capacitor 13. Further, the load side after the secondary coil 10 of the switching transformer can be separated, and an output can be obtained as required.

  Next, the operation of the conventional power supply apparatus will be described. First, when the input power source 1 is applied, the capacitor 3 starts to be charged via the resistor 2. The voltage of the capacitor 3 is input to the gate of the switching element 5 via the control winding 9 of the switching transformer. When the threshold voltage of the gate is reached, the switching element 5 starts to conduct. As a result, a voltage is induced in the control winding 9 of the switching transformer and the secondary coil 10 of the switching transformer, and the gate voltage of the switching element 5 further increases due to the voltage rise in the control winding 9 of the switching transformer. Is completely turned on instantaneously by the positive feedback action.

  For this reason, the current of the primary coil 4 of the switching transformer, that is, the drain current of the switching element 5 increases linearly, and energy is stored in the primary coil 4 of the switching transformer. When the switching element 5 is completely turned on, the impedance of the resistor 7 and the diode 8 (or the impedance circuit 15 shown in FIG. 15 instead of the impedance circuit 14 may be used), that is, the voltage of the capacitor 3, that is, the switching element 5 Begins to discharge the gate voltage. By such a feedback action, when the gate voltage of the switching element 5 falls below the threshold voltage, the switching element 5 is rapidly turned off.

  When the switching element 5 is turned off, the voltage induced in the primary coil 4 of the switching transformer is inverted, and at the same time, resonance with the capacitor 6 occurs. When the resonance voltage is inverted again, the switching element 5 is driven to turn on again through the control winding 9 of the switching transformer. At the same time, resonance occurs between the secondary coil 10 of the switching transformer and the capacitor 11 on the secondary side, and a DC output is supplied to the secondary load 16 by the rectifying / smoothing circuit of the diode 12 and the capacitor 13. It was a thing.

  Next, a conventional technique for controlling the output on the secondary side will be described with reference to the circuit diagram of FIG. According to the figure, reference numeral 20 denotes a primary side power supply unit, which is composed of a DC input power source 21, a high frequency current generation circuit 22 connected thereto, a primary side resonance capacitor 23, and a primary side coil 24. , 25 is a secondary side power supply unit, which is provided in a separate housing from the primary side power supply unit 20 and is connected to the secondary side coil 26 and both ends of the secondary side coil 26. 27, a secondary rectifier 28, an output capacitor 29 having one end connected to the secondary rectifier 28 and the other end connected to the secondary coil 26, and further includes an output stabilization circuit 30 and the output. The capacitor 29 was connected, and a secondary load (not shown) was connected to the output stabilization circuit.

  As described above, since the above-described conventional technique controls either the primary side or the secondary side, it is used as a power supply device for a general electronic device and the primary side and the secondary side are different. It is also used in a non-contact type power supply device provided on the body.

  However, the circuit configuration of FIG. 15 is the reverse of the diode 8 used for feedback in the conventional configuration as described above due to resonance of the primary coil 4 of the switching transformer when the switching element 5 is turned off. Since a high voltage in the direction is applied, a high withstand voltage is required. Further, since the impedance of the control circuit is very high, the reverse leakage current of the diode 8 greatly affects the switching operation of the switching element 5, and the diode 8 needs to have a very low reverse leakage current. It becomes. Moreover, in order to operate at a high frequency of several hundred kHz, a device capable of high frequency switching is required. However, a diode satisfying such characteristics is very difficult to manufacture and is expensive in cost.

  Further, the circuit configuration of FIG. 16 has a problem that a large power loss occurs in the output stabilization circuit 30 in order to obtain an accurate output.

  The present invention provides a power supply apparatus that can solve the above-described problems and obtain an efficient and stable secondary output.

In order to solve the above problems, a power supply device of the present invention includes an input power supply, a series circuit of a primary coil and a switching element of a switching transformer connected to both ends of the input power supply, and both ends of the primary coil. A primary side resonance capacitor connected to the primary side coil, a secondary side coil of the switching transformer opposed to the primary side coil, a secondary side resonance capacitor connected to both ends of the secondary side coil, and an impedance variable circuit And a power detection device that controls the variable impedance circuit based on the output of the output detection means. With the above configuration, by controlling the impedance of the impedance variable circuit, the power stored in the secondary resonance capacitor is adjusted, and the output can be controlled with high accuracy.

  In the case of controlling the secondary side, a series circuit of a capacitor and an impedance variable circuit is connected to both ends of the secondary side coil, and an output detection circuit for detecting the output of the secondary side coil is provided. The impedance variable circuit is controlled by the output of the output detection circuit.

  With the above configuration, it is possible to realize a power supply device that can keep the secondary side output extremely stable against fluctuations in the input voltage and output state.

(Embodiment 1)
An embodiment of the power supply device of the present invention will be described below with reference to FIG.

  In the figure, a control circuit is provided on the primary side. According to the figure, the input power supply 31 is a DC voltage rectified and smoothed from a commercial power supply, and a resistor 32 and a capacitor 33 are connected to both ends of the input power supply 31. And a series circuit of the primary coil 34 of the switching transformer and the switching element 35 are connected, and a capacitor 36 is connected to both ends of the primary coil 34 of the switching transformer.

  The connection point between the resistor 32 and the capacitor 33 is connected to one end of the control winding 37 of the switching transformer, and the other end is connected to the gate of the switching element 35.

  Further, the discharge circuit 40 including the control transistor 38 and the resistors 39a and 39b is driven by the signal of the control winding 37 of the switching transformer, and the electric charge of the capacitor 33 is discharged. A capacitor 42 is connected to both ends of the secondary coil 41 of the switching transformer and a capacitor 44 is connected via a diode 43 so that an output is obtained at both ends of the capacitor 44. Further, the load side after the secondary coil 41 of the switching transformer is separable and can obtain an output as required.

  Next, the operation will be described. When the input power supply 31 is applied, the capacitor 33 starts to be charged via the resistor 32. The voltage of the capacitor 33 is input to the gate of the switching element 35 via the control winding 37 of the switching transformer. When this voltage reaches the threshold voltage of the gate, the switching element 35 starts to conduct. As a result, a voltage is induced in the control winding 37 of the switching transformer and the secondary coil 41 of the switching transformer, and the gate voltage of the switching element 35 further increases due to the voltage rise of the control winding 37 of the switching transformer. Is completely turned on instantaneously by the positive feedback action.

  For this reason, the current of the primary coil 34 of the switching transformer, that is, the drain current of the switching element 35 increases linearly, and energy is stored in the primary coil 34 of the switching transformer. At this time, when the voltage of the control winding 37 of the switching transformer reaches the threshold voltage of the control transistor 38, the control transistor 38 is instantly turned on and starts discharging the capacitor 33 through the resistor 39b.

  Due to such a feedback action, when the gate voltage of the switching element 35 falls below the threshold voltage, the switching element 35 is rapidly turned off (in this embodiment, a field effect transistor (FET) is connected to the switching element 35). Since the threshold voltage is used, the threshold voltage becomes the gate cutoff voltage. When a transistor is used as the switching element, the base voltage of the transistor becomes the threshold voltage).

  When the switching element 35 is turned off, the voltage induced in the primary coil 34 of the switching transformer is inverted, and at the same time, resonance with the capacitor 36 occurs. When the resonance voltage is inverted again, the switching element 35 is driven to turn on again through the control winding 37 of the switching transformer. Similarly to the conventional example of FIG. 15, the secondary side coil 41 of the switching transformer and the capacitor 42 resonate on the secondary side at this time, and the DC output is supplied to the load 45 by the rectifying / smoothing circuit of the diode 43 and the capacitor 42. To supply.

(Embodiment 2)
FIG. 2 is a circuit configuration diagram of another embodiment. The difference from the embodiment of FIG. Unnecessary spike voltage generated in the control winding 37 of the switching transformer is applied to the gate of the switching element 35 and may adversely affect switching turn-on and turn-off operations. For this reason, the clamp circuit 48 clamps the voltage applied to the gate by the forward voltage drop (VF) of the diode 47 to remove unnecessary spike voltage.

  Here, the element used for the clamp circuit 48 to correct the temperature change of the threshold value of the gate voltage of the switching element 35 is not a single diode but a plurality of diodes, a Zener diode, or a combination circuit thereof. You may do it.

  In each of the above embodiments, the output is determined by the on / off period of the switching operation. As described above, the ON period is the time from when the switching element 35 is turned on until the voltage of the capacitor 33 is discharged through the resistor 39b and the threshold voltage of the switching element 35 is interrupted. The off period is the time from when the switching element 35 is turned off until the voltage of the capacitor 33 is charged from the input power supply 31 via the resistor 32 and reaches the threshold voltage of the switching element 35.

  Therefore, it can be seen that the output is determined by the charge / discharge time of the capacitor 33. Accordingly, the resistor 32 for charging / discharging the capacitor 33 or the resistor 39b can be a variable resistor, and the output can be arbitrarily set.

  As described above, in each of the above embodiments, one end of the control winding of the switching transformer is connected to the connection point of the series circuit of the resistor and the capacitor connected between the input power supplies, and the other end of the control winding is switched. Since the discharge circuit connected to the control terminal of the element and driven by the signal of the control winding of the switching transformer is connected to the one end of the control winding, when configuring the oscillation circuit and the control circuit on the primary side, Without using a withstand voltage diode and without the influence of reverse leakage current, the operation can be stabilized and the switching operation close to the ideal can be achieved. It is something that can be done.

(Embodiment 3)
FIG. 3 is a circuit configuration diagram of another embodiment of the present invention. According to the figure, the input power source 51 is a DC voltage rectified and smoothed from a commercial power source or a DC power source such as a car battery. A resistor 52 and a capacitor 53 are connected in series at both ends, and a resistor 54 is connected in parallel with the capacitor 53. Further, a series circuit of a primary coil 55 and a switching element 56 of the switching transformer is connected to both ends of the input power supply, and a capacitor 57 is connected to both ends of the primary coil 55 of the switching transformer.

  The connection point between the resistor 52 and the capacitor 53 is connected to one end of the control winding 58 of the switching transformer, and the other end of the control winding 58 is connected to the gate of the switching element 56.

  Further, a peak voltage control in which a series circuit of a resistor 59 and a resistor 60 is connected between the drain and source of the switching element 56, and the transistor 62 and the resistor 63 are connected via a constant voltage diode 61 from the connection point of the resistor 59 and the resistor 60. The circuit 64 is configured, and the collector of the transistor 62 is connected to the connection point between the resistor 52 and the capacitor 53.

  Further, a capacitor 66 is connected to both ends of the secondary coil 65 of the switching transformer and a capacitor 68 is connected via a diode 67 so that an output is obtained at both ends of the capacitor 68. Further, the load side after the secondary coil 65 of the switching transformer is separable, and an output can be obtained if necessary.

  Next, the operation will be described. First, when the input power supply 51 is applied, the capacitor 53 starts to be charged via the resistor 52. The voltage of the capacitor 53 is input to the gate of the switching element 56 via the control winding 58 of the switching transformer. When the threshold voltage of the gate is reached, the switching element 56 starts to conduct.

  As a result, a voltage is induced in the control winding 58 of the switching transformer and the secondary coil 65 of the switching transformer, and the gate voltage of the switching element 56 further increases due to the voltage rise in the control winding 58 of the switching transformer. Is completely turned on instantaneously by the positive feedback action.

  For this reason, the current of the primary coil 55 of the switching transformer, that is, the drain current of the switching element 56 increases linearly, and energy is stored in the primary coil 55 of the switching transformer. At this time, since the voltage of the capacitor 53 is fixed at a certain voltage by the divided voltage of the resistors 52 and 54, the gate voltage of the switching element 56 is also limited by this voltage. Therefore, the drain current is also limited by the limitation of the gate voltage due to the characteristics of the FET, and as a result, the drain-source voltage increases.

  As a result, the voltage of the primary coil 55 of the switching transformer decreases, and at the same time, the voltage of the control winding 58 of the switching transformer also decreases, so that the gate voltage of the switching element 56 decreases and the threshold voltage is interrupted. 56 quickly turns off. In this embodiment, since a field effect transistor (FET) is used as the switching element, the threshold voltage is a gate cutoff voltage. When a bipolar transistor is used as the switching element, the base voltage is the threshold voltage. Voltage.

  When the switching element 56 is turned off, the voltage induced in the primary coil 55 of the switching transformer is inverted, and at the same time, resonance with the capacitor 57 occurs. At this time, the drain-source voltage of the switching element 56 rises in a sine wave shape due to the resonance phenomenon. When the peak value of the drain-source voltage of the switching element 56 is Vp,

At this time, the peak voltage control circuit 64 operates to perform negative feedback control so as to lower the voltage of the capacitor 53, so that Vp is controlled to be constant for each switching pulse. When the resonance voltage is inverted again, the switching element 56 is driven to turn on again through the control winding 58 of the switching transformer. At this time, resonance also occurs between the secondary coil 65 of the switching transformer and the capacitor 66 on the secondary side, and a DC output is supplied to the secondary load by the rectifying and smoothing circuit of the diode 67 and the capacitor 66.

  As described above, the peak value Vp of the resonance voltage is controlled so as to be always constant for each switching pulse even when the input power supply 51 varies. Therefore, the output voltage generated in the secondary coil 65 of the switching transformer is always constant as shown in FIG. 4, and a very stable voltage can be supplied to the secondary output.

  FIG. 5 is a characteristic diagram showing the relationship between the input voltage and the output power, and shows that the output power is kept constant by being controlled by the peak voltage control circuit 64.

(Embodiment 4)
FIG. 6 is a circuit configuration diagram of one embodiment of the present invention, which is a development example of the embodiment of FIG. 3. Only the differences from the embodiment of FIG. 3 will be described. The output of the peak voltage control circuit 64, that is, the transistor 62 The collector is directly connected to the gate of the switching element 56 and has the same effect as the embodiment of FIG.

(Embodiment 5)
FIG. 7 is a circuit configuration diagram of a peak voltage control circuit which is a main part of one embodiment of the present invention, and the configuration of other circuit portions is the same as the circuit configuration of FIG. The peak voltage control circuit 64a is configured using a comparator (or operational amplifier) 69 and a reference voltage 70 instead of the transistor 62 and the constant voltage diode 61 of FIG. 3, and has the same effect as the embodiment of FIG. It is.

  The above description has been given of the control circuit provided on the primary side. Next, an embodiment in which the control circuit is provided on the secondary side will be described.

(Embodiment 6)
FIG. 8A is a circuit configuration diagram of an embodiment of a power supply device provided with a control circuit on the secondary side. Reference numeral 71 denotes a primary power supply unit, which includes a DC input power supply 72, a high-frequency current generation circuit 73, The secondary side coil 74 is composed of a secondary side coil 74 and a primary side resonance capacitor 75, and 76 is a secondary side power supply unit, a secondary side coil 77, a secondary side resonance capacitor 78, an impedance variable circuit 79, and a secondary side rectifier. 80, an output capacitor 81, and an output detection circuit 82. The impedance variable circuit 79 is inserted between the secondary resonance capacitor 78 and the secondary coil 77 and connected to both ends of the output capacitor 81. The output detection circuit 82 is controlled.

  The operation of the non-contact type DC power supply device configured as described above will be described.

  A high frequency current generated by the high frequency current generating circuit 73 flows through the primary side coil 74, and a high frequency voltage is generated in the primary side coil 74 by this current. This high frequency voltage becomes a sine wave due to a resonance phenomenon between the primary side resonance capacitor 75 and the inductance of the primary side coil 74.

  A voltage waveform similar to the sine wave is generated in the secondary coil 77, but the portion corresponding to the half wavelength is blocked by the secondary rectifier 80. The blocked half-wave power is temporarily stored in the secondary resonance capacitor 78 and transmitted to the output at the next oscillation period. The characteristics of the output voltage and current at this time are shown in FIG.

  When an impedance is inserted in series with the secondary resonance capacitor 78, the characteristics of the output voltage and current change as shown in FIG. 9B depending on the impedance. Therefore, when the output voltage or current is detected by the output detection circuit 82 and the impedance of the impedance variable circuit 79 is controlled so as to be constant, the power accumulated in the secondary side resonance capacitor 78 is adjusted, and the output is accurate. It can be controlled well.

  8B and 8C show specific examples of the impedance variable circuit 79, FIG. 8B shows a parallel circuit of a transistor 83 and a diode 84, and FIG. 8C uses a field effect transistor 85. FIGS. 8D, 8E, and 8F show specific examples of the output detection circuit 82. FIG.

  FIG. 8 (d) is composed of a transistor 86 and resistors 87 and 88 for supplying a divided output voltage to the base, and FIG. 8 (e) uses an error amplifier 89. Is an output current detection circuit that detects the output current of the transistor 90.

  In the figure, (A) is a terminal portion for receiving an output for control from the output voltage (current) detection circuit to the impedance variable circuit 79, and (B) is an input voltage (current) to the impedance variable circuit 79. The output terminal part of a detection circuit is shown.

  Reference numerals 91, 92, and 93 denote resistors, and reference numeral 89a denotes a reference battery that generates a reference voltage.

  As described above, in this embodiment, by providing the secondary side resonance capacitor 78 with the variable impedance circuit 79 and the output detection circuit 82, it is possible to stabilize the output that has been very difficult to stabilize in the past and to produce a highly accurate output. The obtained power supply device can be realized.

(Embodiment 7)
FIG. 10 is a circuit diagram of an embodiment of the present invention. According to the figure, the primary side is connected to an AC power source 94 through a rectifying and smoothing circuit of a rectifier circuit 95, a capacitor 96, and a primary switching element 97. The primary side coil 98 is connected, and the control circuit 99 is connected to the primary switching element 97 to constitute a constant power oscillation circuit stabilized on the primary side.

  Further, on the secondary side of the switching transformer, the transistor (FET) 101 is connected to the secondary side coil 100 via the capacitor C1, and the capacitor 103, the resistor 104, and the output are connected to the secondary side coil 100 of the switching transformer via the diode 102. Terminal 105 is connected. Further, the transistor 106 is connected to the transistor (FET) 101 via the resistor 104, and the transistor 106 is connected from the base to the output terminal 110 via the resistor 107 via the resistor 107 and the transistor 109. By connecting the transistor (FET) 101 in series, the energy transmitted to the load side is changed by changing the impedance of the transistor (FET) 101, and constant voltage constant current control is performed.

  In this configuration, the voltage obtained by the secondary coil 100 of the switching transformer and the capacitor C1 is rectified and smoothed by the diode 102 and the capacitor 103, and this output is connected to the output terminals 105 and 110 via the detection resistor 108. Always stabilized. A battery or the like is connected to the external load 111, and the state of the external load (battery or the like) 111 is monitored by the output current switching circuit 112, and the transistor 109 is driven as shown in FIG. The current is switched to rapid charging or trickle charging, and the external load 111 is optimally charged.

(Embodiment 8)
FIG. 12 shows another embodiment of the present invention, which is an improvement of the embodiment of FIG.

  In the embodiment of FIG. 10, constant voltage current control is performed by changing the impedance of the transistor (FET) 101. However, during fast charging, the transistor (FET) 101 is completely turned on and the maximum output is achieved. And the maximum power is supplied to the external load 111. It corresponds to the f line and the g line in the output characteristic diagram of FIG. 11 and is filled with the i line (rapid charge region). At this time, since the transistor 101 is in the on state, the impedance between the drain and the source is very small and the heat generation is kept low.

  However, in the trickle charge, when the external load 111 is fully charged, the output current switching circuit 112 turns off the transistor 109, a current flows through the detection resistor 108, and when the voltage across the transistor 106 reaches the threshold voltage of the transistor 106, the transistor 106 Is turned on, the transistor (FET) 101 is operated to be turned off, and the output has a constant current drooping characteristic to limit the output current. Charging is performed at h line (trickle charge region) in the output characteristic diagram of FIG. At this time, since the transistor (FET) 101 operates in the active region, the impedance between the drain and the source is increased, the heat generation of the transistor (FET) 101 is very large, and the power consumption is also increased. This example corresponds to this example.

  Only the difference between the present embodiment and FIG. 10 will be described. Instead of the capacitor C1, a first capacitor C2 is connected between both ends of the secondary coil 100, and a transistor (FET) 101 and a second capacitor C3 are connected in parallel with the first capacitor C2. In addition to providing a circuit, the sum of the capacities of the first and second capacitors is substantially the same as the capacity of the capacitor C1 in FIG.

  Also with the above configuration, the voltage obtained by the secondary coil 100 of the switching transformer, the first capacitor C2, and the second capacitor C3 is rectified and smoothed by the diode 102 and the capacitor 103, and this output is output via the detection resistor 108. Connected to the terminals 105 and 110, the current is always stabilized, and the transistor (FET) 101 is completely turned on at the time of rapid charging as in the embodiment of FIG. Is supplied with maximum power. It corresponds to a line and b line in the output characteristic diagram of FIG. 13, and is charged by e line (rapid charging region). At this time, since the transistor (FET) 101 is in the ON state, the impedance between the drain and the source is very small and the heat generation is kept low.

  Further, in trickle charging, when the battery of the external load 111 is fully charged, the output current switching circuit 112 turns off the transistor 109, current flows through the detection resistor 108, and the voltage at both ends becomes the threshold voltage of the transistor 106. When reached, the transistor 106 is turned on and operates to turn off the transistor (FET) 101, and the output has a constant current drooping characteristic to limit the output current. The c-line (trickle charge region in the output characteristic diagram of FIG. ) Is charged. At this time, since the transistor (FET) 101 operates in the active region, the impedance between the drain and the source becomes large, and the heat generation of the transistor (FET) 101 becomes very large, but the capacitors C2 and C3 are connected in parallel. Since it is provided, the capacitance C1 = C2 + C3 of the prior art is obtained, and the current flowing through each capacitor is shared by i2 and i3. Since the current flowing through each capacitor is a high-frequency current, it is determined by the switching frequency and the capacitance of the capacitor. However, if the impedance between the drain and source of the transistor (FET) 101 is constant, the current i1 flowing through the capacitor C1 in FIG. The relationship of the current i3 flowing through the capacitor C3 is i1> i3. Therefore, in this circuit, the heat generation of the transistor (FET) 101 is intended to be kept low.

  Here, since the dynamic range of the output is reduced, the load line (d line in FIG. 13) due to the first capacitor C2 is taken into consideration, so that the trickle charge region (c line in FIG. 13) can be secured. , C3 are appropriately set.

(Embodiment 9)
FIG. 14 is a circuit configuration diagram of another embodiment of the present invention. According to FIG. 14, the input power source 113 is a DC voltage rectified and smoothed from a commercial power source, and a primary side coil 115 and a capacitor are connected via a switching unit 114. 116 is connected to a parallel circuit to form a primary power supply device 117.

  In addition, the secondary power supply device 118 connects the capacitor 120a and the switching element 120 in series to both ends of the secondary coil 119, and connects a series circuit of a diode 121 and a capacitor 122, and a pulse width controller 123, An output is supplied to the load via the constant voltage control unit 124 and the constant current control unit 125.

  Next, the circuit configuration will be described in detail along with the operation. In the primary side power supply device 117, when the input power supply 113 is applied, the switching unit 114 operates to supply a high frequency current to the primary side coil 115. At the same time, the primary side coil 115 resonates with the capacitor 116 and induces a high frequency voltage.

  Further, the voltage induced in the primary coil 115 is induced in the opposing secondary coil 119, and when the switching element 120 is off, the secondary coil 119 and the capacitor 120a do not resonate and the primary coil Only the voltage induced from 115 is obtained, and when the switching element 120 is on, resonance occurs between the secondary coil 119 and the capacitor 120a, and a high output is obtained.

  Further, the output that is not resonated with the resonated voltage is averaged by the time ratio of the on period and the off period, and is rectified and smoothed by the diode 121 and the capacitor 122, and an output is obtained at both ends of the capacitor 122.

  Further, a signal is transmitted from the constant voltage control unit 124 to the pulse width control unit 123 so that the voltage obtained at the capacitor 122 is always constant. Here, the pulse width control unit 123 is controlled by a constant frequency, and is controlled so as to lengthen the ON period of the output pulse when the output voltage decreases and to increase the ON period of the switching element 120, that is, the ON period of the capacitor 120a. The secondary coil 119 and the capacitor 120a have a longer resonance period and act to increase the voltage.

  On the contrary, when the output voltage rises, the ON period of the output pulse is controlled to be shortened, and the resonance period between the secondary coil 119 and the capacitor 120a is shortened to act to lower the voltage.

  In addition, a signal is transmitted from the constant current control unit 125 to the pulse width control unit 123 so that the current supplied to the load is always constant, and when the output current decreases, the ON period of the output pulse is lengthened, and the switching element 120 The ON period of the capacitor 120a, that is, the ON period of the capacitor 120a is controlled to be long, and the resonance period between the secondary coil 119 and the capacitor 120a is lengthened to act to increase the current.

  Conversely, when the output current increases, the ON period is controlled to be shortened, and the resonance period between the secondary coil 119 and the capacitor 120a is shortened to act to reduce the current.

  Thus, by controlling the on / off period of the switching pulse by the pulse width control unit 123, the on / off period of the capacitor 120a is controlled, the output voltage and the output current are controlled, and the constant voltage and constant current output to the load Supply.

  Note that the constant voltage control unit 124 and the constant current control unit 125 may be configured to use either one of them depending on the load that requires constant voltage or constant current.

  As described above, according to the present invention, the first capacitor and the switching element are connected in series to both ends of the coil on the secondary side, and the second capacitor is connected via the diode from the connection point between the coil and the first capacitor. And a constant voltage control unit or a constant current control unit, and a pulse width control unit for controlling on / off of the switching element by a signal from the constant voltage control unit or the constant current control unit. Since the output of the secondary coil 119 and the capacitor 120a is controlled by on / off control, the output is obtained. Therefore, the transistor (FET) 101 shown in FIG. This can contribute to downsizing of the apparatus.

  As described above, the power supply device of the present invention can obtain a power supply device that can control the primary side or control the secondary side to obtain a stable output.

  In particular, (1) one end of a control winding of a switching transformer is connected to a connection point of a series circuit of a resistor and a capacitor connected between input power supplies, and the other end of the control winding is connected to a control terminal of a switching element. In the case where a discharge circuit driven by a signal of the control winding of the switching transformer is connected to the one end of the control winding, a high voltage diode is used when the oscillation circuit and the control circuit are configured on the primary side. It can be used without any influence of reverse leakage current, can stabilize the operation, and can perform a switching operation close to ideal, and can realize a highly reliable power supply device with inexpensive components. Is.

  (2) Further, in the case where a clamp circuit is provided, an unnecessary spike voltage can be removed by clamping the voltage applied to the gate of the switching element.

  (3) Further, a primary coil of the switching transformer and a switching element are connected in series at both ends of the input power supply, and further, a first resistor and a capacitor are connected in series between the input power supplies, and in parallel with the capacitor. 2 is connected, the connection point of the first resistor and the capacitor is connected to one end of the control winding of the switching transformer, and the other end of the control winding of the switching transformer is connected to the control terminal of the switching element. As a means for connecting and discharging the capacitor, a voltage detection unit for detecting a peak voltage by resistance-dividing from the drain of the switching element, and a transistor and a resistor through a constant-voltage diode from the resistance-divided connection point When a peak voltage control circuit comprising a control unit is provided, when an oscillation circuit and a control circuit are configured on the primary side It is possible to control for each pulse of switching, in which it is possible it is accurate stabilization operation to obtain the switching characteristics and the output characteristics close to the ideal.

  (4) The primary coil supplied with the high-frequency current and the secondary coil mounted in a casing different from the primary coil are opposed to each other, and the secondary coil is In the power supply device for transmitting power to the secondary coil, a series circuit of a capacitor and an impedance variable circuit connected to both ends of the secondary coil, and output detection means for detecting an output from the secondary coil are provided, In the case where the impedance variable circuit is controlled by the output of the output detecting means, by controlling the impedance of the impedance variable circuit, the power stored in the secondary resonance capacitor is adjusted, and the output can be controlled with high accuracy. Is.

  (5) Furthermore, in the case where an output current switching circuit connected to the output detection means is provided to control the output detection means, the charging current can be switched between quick charge or trickle charge (normal charge). Is.

  (6) Furthermore, in the case where another capacitor is connected in parallel to the series circuit of the capacitor that is connected to both ends of the secondary coil and the transistor that is an impedance variable circuit, heat generation during trickle charging can be suppressed. This contributes to the miniaturization of the power supply device by eliminating the need for a heat sink and reducing the size of the transistor.

  (7) On the secondary side, a first capacitor and a switching element are connected in series to both ends of the coil, and a second capacitor is connected via a diode from the connection point between the coil and the first capacitor. A constant voltage control unit or a constant current control unit, and a pulse width control unit that controls on / off of the switching element by a signal from the constant voltage control unit or the constant current control unit. Since the output is obtained by controlling the resonance between the secondary coil and the capacitor so as to obtain an output, it is not controlled by analog control, so it generates little heat and contributes to the miniaturization of the apparatus.

  (8) Further, in the case where the primary side coil and the secondary side coil are provided in different casings, the non-contact type power supply device is useful for portable electronic devices such as cordless telephones.

The circuit block diagram of one Example of the power supply device of this invention Circuit configuration of other embodiment Circuit configuration of other embodiment Output characteristics Input voltage vs. output power characteristics Circuit configuration of other embodiment Circuit configuration diagram of main part of other embodiment (A) is a circuit configuration diagram of the other embodiment, (b) is a specific circuit configuration diagram of the impedance variable circuit that is the main part, (c) is a specific circuit diagram of the impedance variable circuit that is the main part. (D) is a specific circuit configuration diagram of the output detection circuit as the main part, (e) is a specific circuit configuration diagram of the output detection circuit as the main part, and (f) is the same circuit diagram. Specific circuit configuration diagram of the output detection circuit 8A is an output voltage-current characteristic diagram of the power supply device of FIG. 8A, and FIG. Circuit configuration of other embodiment Output characteristics Circuit configuration of other embodiment Output characteristics Circuit configuration of other embodiment Circuit diagram of conventional power supply Circuit configuration diagram of another conventional power supply device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input power supply 2 Resistance 3 Capacitor 4 Primary side coil 5 Switching element 6 Capacitor 7 Resistance 8 Diode 9 Control winding 10 Secondary side coil 11 Capacitor 12 Diode 13 Capacitor 14 Impedance circuit 15 Impedance circuit 16 Load 20 Primary side power supply part DESCRIPTION OF SYMBOLS 21 DC input power supply 22 High frequency current generation circuit 23 Primary side resonance capacitor 24 Primary side coil 25 Secondary side power supply part 26 Secondary side coil 27 Secondary side resonance capacitor 28 Secondary side rectifier 29 Output capacitor 30 Output stabilization circuit 31 Input Power Supply 32 Resistor 33 Capacitor 34 Primary Coil 35 Switching Element 36 Capacitor 37 Control Winding 38 Control Transistor 39a Resistor 39b Resistor 40 Discharge Circuit 41 Secondary Coil 42 Capacitor 43 Diode 44 Densator 45 Load 46 Resistor 47 Diode 48 Clamp circuit 51 Input power source 52 Resistor 53 Capacitor 54 Resistor 55 Primary coil 56 Switching element 57 Capacitor 58 Control winding 59 Resistor 60 Resistor 61 Constant voltage diode 62 Transistor 63 Resistor 64 Peak voltage control circuit 64a Peak voltage control circuit 65 Secondary coil 66 Capacitor 67 Diode 68 Capacitor 69 Comparator 70 Reference voltage 71 Primary power supply 72 DC input power supply 73 High frequency current generation circuit 74 Primary coil 75 Primary resonance capacitor 76 Secondary Side power supply unit 77 Secondary side coil 78 Secondary side resonance capacitor 79 Impedance variable circuit 80 Secondary side rectifier 81 Output capacitor 82 Output detection circuit 83 Transistor 84 Diode 85 Electric field Fruit transistor 86 Transistor 87 Resistor 88 Resistor 89 Error amplifier 89a Reference battery 90 Transistor 91 Resistor 92 Resistor 93 Resistor 94 AC power supply 95 Rectifier circuit 96 Capacitor 97 Primary switching element 98 Primary coil 99 Control circuit 100 Secondary coil 101 Transistor (FET)
DESCRIPTION OF SYMBOLS 102 Diode 103 Capacitor 104 Resistance 105 Output terminal 106 Transistor 107 Resistance 108 Detection resistance 109 Transistor 110 Output terminal 111 External load 112 Output current switching circuit 113 Input power supply 114 Switching part 115 Primary side coil 116 Capacitor 117 Primary side power supply device 118 2 Secondary power supply device 119 Secondary coil 120 Switching element 120a Capacitor 121 Diode 122 Capacitor 123 Pulse width controller 124 Constant voltage controller 125 Constant current controller C1 Capacitor C2 First capacitor C3 Second capacitor

Claims (3)

An input power source, a series circuit of a primary side coil and a switching element of a switching transformer connected to both ends of the input power source, a primary side resonance capacitor connected to both ends of the primary side coil, and the primary A secondary coil of the switching transformer opposed to the side coil, a series circuit of a secondary resonance capacitor and an impedance variable circuit connected to both ends of the secondary coil, and an output from the secondary coil. A power supply apparatus comprising: an output detection means for detecting; and controlling the impedance variable circuit by an output of the output detection means. The power supply apparatus according to claim 1, further comprising an output current switching circuit connected to the output detection means, wherein the output current switching circuit controls the output detection means. The power supply device according to claim 2, wherein another capacitor is connected in parallel to a series circuit of a capacitor connected to both ends of the secondary coil and an impedance variable circuit.

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