JP2016144339A - Power supply device and ac adapter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device capable of improving conversion efficiency, and an AC adapter.SOLUTION: The power supply device comprises an H bridge, a first inductor, a second inductor, a first capacitor, a transformer, a rectifier and a control part. The H bridge is connected in parallel with first and second switches that are connected in series, third and fourth switches that are connected in series, and two bridge capacitors that are connected in series. The first inductor is connected in series between a connection point of the first and second switches and an AC power source. One terminal of the second inductor is connected to a connection point of the third and fourth switches. One terminal of the first capacitor is connected to a neutral point of the two bridge capacitors. The transformer includes: a primary coil that is connected in series between the other terminal of the second inductor and the other terminal of the first capacitor; and a secondary coil that is coupled to the primary coil in an electromagnetic manner. The rectifier is connected to the secondary coil of the transformer. The control part controls switching signals to be given to the switches.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a power supply device and an AC adapter.

  Devices such as digital home appliances and OA devices are equipped with a power supply device for obtaining DC power from a commercial AC power supply. As a power supply device for obtaining DC power from an AC power supply, one having three circuits of a diode rectifier circuit, a power factor correction circuit (PFC), and a DC / DC converter is known. For example, FIG. 11 shows a circuit configuration of a conventional power supply device. The diode rectifier circuit rectifies the AC voltage and converts it into a DC voltage. Since the voltage rectified by the diode rectifier fluctuates greatly like the AC voltage, a smoothing capacitor is connected to smooth the voltage. When a smoothing capacitor is connected, the rectifier operates so that the diode conducts only when the AC voltage is higher than that of the smoothing capacitor. For this reason, the current flowing into the rectifier from the AC power source has a waveform with a poor power factor having an amplitude only near the AC voltage peak. The PFC circuit is connected between the diode rectifier circuit and the smoothing capacitor to improve the power factor. The DC / DC converter converts the DC voltage obtained by the rectifier circuit and the PFC circuit into a desired voltage.

Jun-Ho Kim et al, “Analysis and Design of Boost-LLC Converter for High Power Density AC-DC Adapter”, ECCE Asia 2013, pp6-11

However, in a multi-stage circuit, the loss of the entire circuit is the sum of the losses generated in each circuit. For this reason, a power supply device to which a multi-stage circuit is applied has a limit in improving the efficiency of the power supply device as a whole even if the efficiency of each circuit is good.
An object of this invention is to provide the power supply device and AC adapter which can improve the conversion efficiency for obtaining DC power supply from AC power supply.

  According to the embodiment, the power supply device includes an H bridge, a first inductor, a second inductor, a first capacitor, a transformer, a rectifier, and a control unit. In the H-bridge, first and second switches connected in series, third and fourth switches connected in series, and two bridge capacitors connected in series are connected in parallel. The first inductor is connected in series between the connection point of the first and second switches and the AC power supply. One end of the second inductor is connected to the connection point of the third and fourth switches. One end of the first capacitor is connected to the neutral point of the two bridge capacitors. The transformer has a primary winding connected in series between the other end of the second inductor and the other end of the first capacitor, and a secondary winding electromagnetically coupled to the primary winding. The rectifier is connected to the secondary winding of the transformer. A control part controls the switching signal given to each switch.

FIG. 1 is a diagram illustrating a configuration example of a power supply device according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of a control device in the power supply device according to the first embodiment. FIG. 3 is a schematic diagram for explaining voltage waveforms in each part of the power supply circuit of the power supply device according to the first embodiment. FIG. 4A shows the voltage Vab, the voltage Vbn, the current Iall, the current It, and the current Iac in the power supply circuit of the power supply device according to the first embodiment. FIG. 4B shows a waveform of the voltage Vab. FIG. 4C shows a waveform of the voltage Vbn. FIG. 4D shows a waveform of the current Iall. FIG. 4E shows a waveform of the current It. FIG. 4F shows the waveform of the current Iac. FIG. 5 is a diagram illustrating a first example of the A modulation rate and the B modulation rate with respect to the AB voltage modulation rate. FIG. 6 is a diagram illustrating a second example of the A modulation rate and the B modulation rate with respect to the AB voltage modulation rate. FIG. 7 is a diagram illustrating the gain characteristics of the voltage with respect to the switching frequency. FIG. 8 is a diagram illustrating a configuration example of the power supply device according to the second embodiment. FIG. 9 is a diagram illustrating a configuration example of the power supply device according to the third embodiment. FIG. 10 is a diagram illustrating a modification of the power supply device according to the third embodiment. FIG. 11 is a diagram illustrating a circuit configuration example of a conventional power supply device.

Hereinafter, embodiments will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration example of a power supply device 1 according to the first embodiment.
The power supply device 1 includes a power supply circuit 11 and a control device (control unit) 12. In the power supply device 1, the control device 12 controls the power supply circuit 11 to convert AC power from the AC power supply 2 into DC power supplied to the load 3. The power supply device 1 can be realized as an AC adapter by providing a plug connected to the AC power supply 2 and a plug connected to the load 3.

The power supply circuit 11 includes a first inductor L1, an H bridge 21, a second inductor L2, a transformer T, a first capacitor C1, a rectifier 22, an input voltage detection unit (first voltage detection means) 23, and a power supply current detection unit (current). A detection unit) 24, a capacitor voltage detection unit (second voltage detection unit) 25, and an output voltage detection unit (third voltage detection unit) 26.
The H bridge 21 includes switching elements (switches) S1P, S1N, S2P, S2N, diodes D1P, D1N, D2P, D2N, and bridge capacitors Cdc1, Cdc2.

  The H bridge 21 includes first and second switching elements S1P and S1N connected in series, third and fourth switching elements S2P and S2N connected in series, and first and second switching elements connected in series. Bridge capacitors Cdc1 and Cdc2 are connected in parallel to each other. In the following description, as shown in FIG. 1, in the H bridge 21, a connection point between the first switching element S1P and the second switching element S1N connected in series is a point A, and a third switching element S2P connected in series is used. A connection point between the first switching capacitor S2N and the fourth switching element S2N is a point B, and a connection point (neutral point) between the first bridge capacitor Cdc1 and the second bridge capacitor Cdc2 connected in series is an N point.

  That is, the source terminal of the first switching element S1P is connected to the drain terminal of the second switching element S1N via the point A. The source terminal of the third switching element S2P is connected to the drain terminal of the fourth switching element S2N via point B. The drain terminal of the first switching element S1P is connected to the drain terminal of the third switching element S2P. The source terminal of the second switching element S1N is connected to the source terminal of the fourth switching element S2N.

  One end of the first and second bridge capacitors Cdc1 and Cdc2 connected in series is connected to the drain terminal of the first switching element S1P and the drain terminal of the third switching element S2P. The other ends of the first and second bridge capacitors Cdc1 and Cdc2 connected in series are connected to the source terminal of the second switching element S1N and the source terminal of the fourth switching element S2N.

  Diodes D1P, D1N, D2P, and D2N are connected in parallel to the switching elements S1P, S1N, S2P, and S2N, respectively. The switching elements S1P, S1N, S2P, and S2N are self-extinguishing elements and can be MOSFETs or the like. For example, N-type field effect transistors (MOSFETs) can be used for the switching elements S1P, S1N, S2P, and S2N. The diodes D1P, D1N, D2P, and D2N may be replaced with body diodes such as MOSFETs. The gate terminals of the switching elements S1P, S1N, S2P, and S2N are connected to the control device 12. Each of the switching elements S1P, S1N, S2P, and S2N is turned on / off by a switching signal that the control device 12 gives to the gate terminal.

  The first inductor L <b> 1 is connected in series between the AC power supply 2 and the point A of the H bridge 21. The second inductor L2, the primary winding T1 of the transformer T, and the first capacitor C1 are defined by the points B and N in the H bridge 21 (the midpoint between the first bridge capacitor Cdc1 and the second bridge capacitor Cdc2). In between, they are connected in series.

  A rectifier 22 is connected to the secondary winding T2 of the transformer T. The rectifier 22 is composed of a switching element such as a diode or a MOSFET. In the configuration example illustrated in FIG. 1, the rectifier 22 includes a fifth diode D5 and a sixth diode D6. The anode terminals of the fifth diode D5 and the sixth diode D6 are connected to both ends of the secondary winding T2 of the transformer T, respectively. The cathode terminals of the fifth diode D5 and the sixth diode D6 are connected to each other. A capacitor Cout is connected between the connection point of each cathode terminal of the fifth diode D5 and the sixth diode D6 and the middle point of the secondary winding T2 of the transformer T. The diodes D5 and D6 and the capacitor Cout constitute a rectifying / smoothing circuit. A load 3 is connected in parallel to the capacitor Cout.

The input voltage detector 23 detects the AC power supply voltage Vac input from the AC power supply 2 to the power supply circuit 11. The input voltage detection unit 23 is connected in parallel to both ends of the AC power supply 2. The input voltage detection unit 23 outputs a detection value indicating an instantaneous value of the power supply voltage Vac to the control device 12.
The power source current (inductor current) detection unit 24 detects an AC power source current (inductor current) Iac that flows to the AC power source 2. The power supply current detection unit 24 is connected in series between the AC power supply 2 and the first inductor L1, for example. The power supply current detector 24 outputs a detection value indicating an instantaneous value of the power supply current Iac to the control device 12.

  The capacitor voltage detector 25 detects the voltage (capacitor voltage) Vdc applied to the first and second bridge capacitors Cdc1 and Cdc2 connected in series in the H bridge 21. The capacitor voltage detection unit 25 is connected in parallel to both ends of the first and second bridge capacitors Cdc1 and Cdc2 connected in series. Capacitor voltage detection unit 25 outputs a detection value indicating an instantaneous value of capacitor voltage Vdc to control device 12.

  The output voltage detection unit 26 detects the output voltage Vout of the second capacitor Cout. The output voltage detection unit 26 is connected in parallel to both ends of the second capacitor Cout on the load 3 side. Since the second capacitor Cout is connected in parallel to the load 3, the output voltage Vout detected by the output voltage detection unit 26 is an output voltage output to the load 3. The output voltage detection unit 26 outputs a detection value indicating an instantaneous value of the output voltage Vout to the control device 12.

Next, a configuration example of the control device 12 will be described.
The control device 12 turns on and off the four switching elements of the H bridge 21 from current and voltage information detected by each part of the power supply circuit 11. The control device 12 controls the output voltage as well as the power factor in the power supply circuit 11 by turning on and off the four switching elements.

  The control device 12 controls on / off of the four switching elements so that the power supply current Iac having the same phase as the AC power supply voltage Vac flows based on the AC power supply voltage Vac, the AC power supply current Iac, and the capacitor voltage Vdc as power factor control. To do. Further, the control device 12 controls the four switching operations so as to eliminate the deviation from the output voltage command value (set value of the output voltage) with respect to the output voltage Vout based on the detected value of the output voltage Vout. Controls on / off of the element.

FIG. 2 is a block diagram illustrating a configuration example of the control device 12.
As shown in FIG. 2, the control device 12 is roughly divided into a power factor control unit 12A and an output voltage control unit 12B.
First, the configuration of the power factor control unit 12A will be described.
The power factor control unit 12A includes a capacitor voltage setting unit 31, a subtraction unit 32, a voltage controller (AVR) 33, a PLL (phase-locked loop) 34, a sine wave generation unit 35, a multiplication unit 36, a subtraction unit 37, and current control. An ACR 38, a division unit 39, a double processing unit 40, a subtraction unit 41, a limit processing unit 42, a subtraction unit 43, and a switching signal generation unit 51.

Capacitor voltage setting unit 31 sets a voltage command value Vdc_ref for capacitor voltage Vdc. Capacitor voltage setting unit 31 outputs a preset voltage command value Vdc_ref to subtraction unit 32.
Subtraction unit 32 calculates deviation vdc_dif by subtracting voltage command value Vdc_ref set by capacitor voltage setting unit 31 from capacitor voltage Vdc detected by capacitor voltage detection unit 25. The subtraction unit 32 outputs the calculated deviation Vdc_dif (= Vdc−Vdc_ref) to the voltage controller (AVR) 33.
The voltage controller (AVR) 33 generates an amplitude command value Iac_amp_Ref for the AC power supply current (inductor current) Iac by a PI calculation based on the deviation Vdc_dif calculated by the subtractor 32. The voltage controller 33 outputs the generated amplitude command value Iac_amp_ref to the multiplication unit 36.

The PLL 34 detects the phase ωt of the power supply voltage Vac detected by the power supply voltage detection unit 23. The PLL 34 outputs the detected phase ωt of the power supply voltage to the sine wave generation unit 35.
The sine wave generation unit 35 generates a sine wave sin ωt having the same phase as the power supply voltage phase ωt detected by the PLL 34. The sine wave generation unit 35 outputs the generated sine wave sin · ωt to the multiplication unit 36.

The multiplier 36 multiplies the amplitude command value Iac_amp_ref and the sine wave sin ωt. Multiplier 36 calculates current command value Iac_ref having the same phase as power supply voltage Vac by multiplying amplitude command value Iac_amp_ref and sine wave sin ωt. Multiplication unit 36 outputs the calculated current command value Iac_ref to subtraction unit 37.
The subtractor 37 subtracts the value of the power supply current (inductor current) Iac detected by the power supply current detector 24 from the current command value Iac_ref calculated by the multiplier 36. The subtraction unit 37 outputs the calculated deviation Iac_dif (= Iac_ref−Iac) to the current controller (ACR) 38.

The current controller (ACR) 38 generates an output voltage command value Vab_ref for the output voltage Vab between AB in the H bridge 21 by PI calculation based on the deviation Iac_dif calculated by the subtractor 37. The current control unit 38 outputs the generated output voltage command value Vab_ref to the division unit 39.
The divider 39 divides the output voltage command value Vab_ref acquired from the current controller (ACR) 38 by the value of the capacitor voltage Vdc detected by the capacitor voltage detector 25. The division unit 39 outputs the ratio of the calculated output voltage command value Vab_ref and the capacitor voltage Vdc to the double processing unit 40 as a modulation factor command value D (= Vab_ref / Vdc).

The double processing unit 40 doubles the modulation factor command value D supplied from the division unit 39. The double processing unit 40 outputs the doubled modulation factor command value to the subtraction unit 41. The subtracting unit 41 subtracts the modulation factor 1 from the modulation factor command value that has been doubled by the double processing unit 40. The subtraction unit 41 outputs the subtracted value to the limit processing unit 42.
The limit processing unit 42 limits the value given from the subtracting unit 41. This is because the modulation rate range cannot exceed ± 1. The limit processing unit 42 outputs the value subjected to the limit processing as the modulation factor command value Da to the switching signal generation unit 51 and the subtraction unit 43.

  The subtracting unit 43 generates the modulation rate command value Db by subtracting the modulation rate command value Da from the doubled modulation rate command value calculated by the double processing unit 40. The subtractor 43 outputs the generated modulation factor command value Db to the switching signal generator 51.

  The switching signal generation unit 51 acquires the modulation rate command value Da and the modulation rate command value Db. The switching signal generation unit 51 performs each switching of the power supply circuit 11 based on the modulation rate command values Da and Db generated by the power factor control unit 12A and a carrier signal Sc of a triangular wave carrier provided from an output voltage control unit 12B described later. A switching signal to be supplied to the element is generated. A configuration example of the switching signal generation unit 51 will be described later.

Next, the configuration of the output voltage control unit 12B will be described.
In the configuration example illustrated in FIG. 2, the output voltage control unit 12B includes an output voltage setting unit 61, a subtraction unit 62, a voltage controller (AVR) 63, a carrier generation unit 64, and a switching signal generation unit 51.

The output voltage setting unit 61 sets an output voltage command value Vout_ref for the output voltage Vout. The output voltage setting unit 61 outputs the output voltage command value Vout_ref for the preset output voltage Vout to the subtraction unit 62.
The subtractor 62 calculates the deviation Vout_dif by subtracting the output voltage command value Vout_ref set by the output voltage setting unit 61 from the output voltage Vout detected by the output voltage detector 26. The subtraction unit 62 outputs the calculated deviation Vout_dif (= Vout−Vout_ref) to the voltage controller (AVR) 63.

The voltage controller (AVR) 63 generates the carrier frequency fc by PI calculation based on the deviation Vout_dif acquired from the subtracting unit 62. The voltage controller 63 outputs the generated carrier frequency fc to the carrier generation unit 64.
The carrier generation unit 64 generates a carrier signal Sc of a triangular wave carrier having a carrier frequency fc received from the voltage controller (AVR) 63. The carrier generation unit 64 outputs the generated carrier signal Sc to the switching signal generation unit 51.

Next, the configuration of the switching signal generation unit 51 will be described.
The switching signal generation unit 51 includes comparators 71 and 72 and NOT circuits 73 and 74. Modulation rate command values Da and Db are input from the power factor control unit 12A to the switching signal generation unit 51, and the carrier signal Sc is input from the output voltage control unit 12B.

  The modulation factor command value Da is input to the non-inverting input terminal of the comparator 71. The carrier signal Sc generated by the carrier generation unit 64 is input to the inverting input terminal of the comparator 71. The comparator 71 compares the modulation factor command value Da with the carrier signal Sc and outputs a switching signal S1P_PWM having a value of “1” or “0”. For example, the comparator 71 outputs a switching signal S1P_PWM of “1” when Sc <Da, and outputs a switching signal S1P_PWM of “0” when Sc ≧ Da.

The comparator 71 outputs the generated switching signal S1P_PWM to the gate terminal of the first switching element S1P, and outputs the switching signal S1P_PWM to the NOT circuit 73.
The NOT circuit 73 generates the second switching signal S1N_PWM by inverting the switching signal S1P_PWM supplied from the comparator 71. The NOT circuit 73 outputs the generated second switching signal S1N_PWM to the gate terminal of the second switching element S1N.

  Further, the modulation factor command value Db is input to the non-inverting input terminal of the comparator 72. A carrier signal Sc of a triangular wave carrier generated by the carrier generator 64 is input to the inverting input terminal of the comparator 72. The comparator 72 compares the modulation factor command value Db with the carrier signal Sc and outputs a switching signal S2P_PWM having a value of “1” or “0”. For example, the comparator 72 outputs a switching signal S2P_PWM of “1” when Sc <Db, and outputs a switching signal S2P_PWM of “0” when Sc ≧ Db.

The comparator 72 outputs the generated switching signal S2P_PWM to the gate terminal of the third switching element S2P and outputs the switching signal S2_PWM to the NOT circuit 74.
The NOT circuit 74 generates the fourth switching signal S2N_PWM by inverting the switching signal S2P_PWM received from the comparator 72. The NOT circuit 74 outputs the generated second switching signal S2N_PWM to the gate terminal of the fourth switching element S1N.
With the above configuration, the control device 12 controls the on / off of the four switching elements in the H bridge 21 of the power supply circuit 11.

Next, the operation principle of the power supply device 1 configured as described above will be described.
The power supply device 1 includes a power supply circuit 11 including an H bridge 21 and a control device 12. The H bridge 21 includes four switching elements and bridge capacitors Cdc1 and Cdc2. The control device 12 outputs a switching signal for each switching element generated based on the voltage (capacitor voltage) Vdc charged in the first and second bridge capacitors Cdc1 and Cdc2. By such control of the control device 12, the power supply circuit 11 can output an arbitrary voltage whose upper limit is the voltage of the bridge capacitors Cdc1 and Cdc2 as an output voltage.

  As a method for outputting a voltage by switching, PWM (Pulse Width Modulation), PDM (Pulse Density Modulation), or the like is used. Various known methods such as carrier comparison and hysteresis comparator can be applied to the PWM and PDM generation methods. Note that the method of charging the capacitor of the H-bridge 21 and the voltage control method thereof can be realized using an AC power supply voltage.

  FIG. 3 is a schematic diagram for explaining voltage waveforms in each part of the power supply circuit 11. FIG. 4 is a diagram showing the relationship between the voltage and current in each part of the power supply circuit 11. FIG. 4A shows the voltage Vab, voltage Vbn, current Iall, current It, and current Iac in the power supply circuit 11. FIG. 4B shows a voltage waveform of the line voltage (between AB) voltage Vab. FIG. 4C shows a voltage waveform of the voltage Vab between BN. FIG. 4D shows a waveform of the current Iall. FIG. 4E shows a waveform of the current It. FIG. 4F shows the waveform of the current Iac.

  A differential voltage between the output voltage Vab between AB in the H bridge 21 and the power supply voltage Vac of the AC power supply 2 is applied to the first inductor L1 connected in series between the point A of the H bridge 21 and the AC power supply 2. . Here, a case is considered in which a voltage corresponding to the AC power supply voltage is output from the H bridge 21 in a direction to cancel the AC power supply voltage Vac.

  As shown in FIG. 3, the output voltage Vab between AB in the H bridge 21 includes a harmonic component due to switching and a low frequency component of 50 Hz or 60 Hz of the output voltage. The AC voltage to be output is the same 50 Hz or 60 Hz output as the AC power supply. On the other hand, the switching frequency of each switching element controlled by the control device 12 uses a frequency of several tens to several hundreds of kilohertz which is sufficiently higher than that.

  The H bridge 21 outputs a sine wave voltage of 50 to 60 Hz by PWM of several tens to several hundreds of kiloHz. This is the output voltage Vab between AB in the H-bridge 21. When the sine wave voltage as described above is generated by the H-bridge 21, the voltages generated by the bridges of the first and second switching elements S1P and S1N and the bridges of the third and fourth switching elements S2P and S2N are symmetric. In many cases, in the power supply circuit 11, the bridge of the first and second switching elements S1P and S1N outputs most of the sine wave, and the ON ratio of the bridge of the third and fourth switching elements S2P and S2N is 50. It is controlled to maintain about%.

  A difference between the AC power supply voltage Vac and the output voltage Vab of the H bridge 21 is applied to the first inductor L1. Since the inductance of the first inductor L1 connected in series to the H bridge 21 is large, the high frequency component of the output voltage Vab between AB of the H bridge 21 is attenuated, and the low frequency of 50 Hz or 60 Hz included in the output voltage Vab of the H bridge 21 is reduced. The difference between the frequency component and the power supply voltage Vac is applied.

  On the other hand, the voltage (voltage between BN) Vbn applied to the second inductor L2, the primary winding T1 of the transformer T, and the first capacitor C1 is equal to the third and fourth switching elements S2P and S2N in the H bridge 21. This is the difference voltage between the output voltage at point B, which is the connection point, and the intermediate (point N) potential between the first and second bridge capacitors Cdc1 and Cdc2. The bridge of the third and fourth switching elements S2P and S2N in the H bridge 21 is controlled so that the ON ratio is about 50% as described above.

  For this reason, as shown in FIG. 4C, the voltage Vbn between BN in the H-bridge 21 is “+1/1/2” with respect to the intermediate potential (= ½ Vdc) of the first and second bridge capacitors Cdc1 and Cdc2. 2Vdc "or" -1 / 2Vdc "is output at a ratio of about 50%. As a result, only the high frequency component due to switching is applied to the second inductor L2 and the primary winding T1 of the transformer T.

  That is, the magnitude of the difference between the low frequency component of the output voltage Vab of the H bridge 21 applied to the first inductor L1 and the AC power supply voltage Vac can be arbitrarily adjusted by controlling the output voltage Vab of the H bridge 21. It is. Therefore, the magnitude of the current flowing through the first inductor L1, that is, the magnitude of the current flowing from the AC power supply 2 into the power supply device 1 can be adjusted by controlling the low frequency component of the output voltage Vab of the H bridge 21. Using this characteristic, the power supply device 1 operates as a rectifier and a PFC by controlling the switching of each switching element in the H bridge 21.

  A high frequency voltage is applied to the second inductor L2 and the primary winding T1 of the transformer T. The high frequency voltage applied to the primary winding T1 of the transformer T is excited by the secondary winding T2 of the transformer T. The voltage excited by the secondary winding T2 of the transformer T is rectified by the rectifier 22 and smoothed by the capacitor Cout, thereby becoming a DC voltage and supplied to the load 3. Thereby, the power supply device 1 operates as a power source for AC / DC conversion.

  The load voltage connected to the secondary winding T2 of the transformer T is determined by the magnitude of the high-frequency voltage applied to the primary winding T1 of the transformer T. A high-frequency voltage obtained from the BN of the H bridge 21 is applied to each of the primary winding T1 and the second inductor L2 of the transformer T. For this reason, the harmonic voltage applied to the primary winding T1 of the transformer T is a voltage divided by the second inductor L2.

  The voltage applied to the second inductor L2 and the primary winding T1 of the transformer T is a high-frequency voltage generated by switching of the H bridge 21. The frequency of the high-frequency voltage varies depending on the switching frequency of the switching element. Since the second inductor L2 has a constant inductor, the impedance changes depending on the frequency. By utilizing this characteristic, the voltage Vbn between BN is controlled to adjust the voltage applied to the transformer T by adjusting the voltage applied to the second inductor L2, thereby controlling the load voltage (output voltage). . That is, the power supply device 1 operates as a DC / DC converter by controlling the switching of the third and fourth switching elements S2P and S2N in the H bridge 21.

Next, charging of the first and second bridge capacitors Cdc1 and Cdc2 in the H bridge 21 and a voltage control method thereof will be described.
First, at start-up, the first and second bridge capacitors Cdc1 and Cdc2 are not charged at all. In this state, when the AC power supply 2 is connected to the power supply device 1, the power supply voltage Vac from the AC power supply 2 is applied between AB of the H bridge 21 via the first inductor L 1 and the like. If the capacitor is not charged at all, a diode connected in parallel to each switching element is ignited by the applied AC voltage Vac, and each diode is connected to the first and second bridge capacitors Cdc1 and Cdc2. Operates as a full-wave rectifier circuit.

  The first and second bridge capacitors Cdc1 and Cdc2 are charged to about the peak value of the AC power supply voltage Vac. Here, when the first and second bridge capacitors Cdc1 and Cdc2 are charged up to the power supply voltage Vac of the AC power supply, the H bridge 21 can output a voltage corresponding to the power supply voltage of the AC power supply voltage. As described above, the inductor current (power supply current) flowing through the first inductor L1 can be controlled by controlling the output voltage Vab of the H bridge 21. The control device 12 can supply active power to the power supply circuit 11 by controlling the inductor current (power supply current) flowing through the first inductor L1 so as to have a current in phase with the AC power supply voltage.

  Here, it is assumed that the first inductor L1 has an impedance of only several percent with respect to the rated capacity of the power supply device 1. For this reason, the voltage applied to the first inductor L1 for current control is about several percent of the AC power supply voltage. That is, the output voltage Vab of the H bridge 21 includes a component for canceling the AC power supply voltage Vac and a voltage for controlling the current of the first inductor L1, but the voltage for controlling the current is several percent. For this reason, most of the output voltage Vab of the H bridge 21 is a sinusoidal voltage approximate to the AC power supply voltage Vac.

  Therefore, most of the effective power obtained by controlling the power supply current (inductor current) in phase with the AC power supply 2 to flow into the power supply circuit 11 is supplied to the H bridge 21. When a current is supplied from the AC power supply 2 to the H bridge 21 in the direction of supplying power, the capacitor voltage Vdc in the H bridge 21 increases. On the other hand, if a current is supplied in a direction in which power is supplied from the H bridge 21 to the AC power supply 2, the capacitor voltage Vdc of the H bridge 21 decreases. Therefore, the power supply device 1 can control the capacitor voltage in the H bridge 21 by the control device 12 controlling the power supply current component in phase with the AC power supply voltage.

Next, an operation (output voltage control) for supplying power from the output voltage Vab of the H bridge 21 to the secondary side via the transformer T will be described.
As described above, the charging and power of the first and second bridge capacitors Cdc1 and Cdc2 from the AC power source 2 by the output voltage Vab of the H bridge 21 (that is, the difference voltage between the points A and B shown in FIG. 1). With rate control. The AB voltage Vab needs to be a sinusoidal voltage, but the voltages at points A and B need not necessarily be sinusoidal PWM.

5 and 6 show a modulation rate command value (A modulation rate) Da for point A voltage, a modulation rate command value (B modulation rate) Db for point B voltage, and a modulation rate command for voltage between AB (line-to-line). An example of a value (inter-AB voltage modulation factor) D is shown.
FIG. 5 shows that when Vac = 100 [Vrms], Vdc = 300 [v], and Vab = 120 [Vpeak], the A modulation rate Da and B when the AB voltage modulation rate D is about 0.4. The modulation rate Db is shown.
In the example shown in FIG. 5, if the AB voltage modulation rate D is about 0.4, the B modulation rate Db is zero. When the B modulation rate Db is zero, the B point voltage outputs an intermediate potential (= 1/2 Vdc) between the first and second bridge capacitors Cdc1 and Cdc2 with an ON ratio of around 50%. On the other hand, the point A voltage outputs a sine wave having a maximum modulation rate of 0.8.

  FIG. 6 shows A modulation rates Da and B when the line voltage modulation rate D is about 0.8 when Vac = 100 [Vrms], Vdc = 300 [v], and Vab = 120 [Vpeak]. The modulation rate Db is shown. The A modulation factor Da is limited to ± 1.0. When the line voltage modulation factor D is 0.8, the A modulation factor Da exceeds 1.0. For this reason, the A modulation factor Da has a waveform in which the peak bottom is crushed as shown in FIG. The amount of collapse of the peak bottom of the A modulation factor Da is compensated by increasing the B modulation factor Db.

  That is, the control device 12 of the power supply device 1 controls the line voltage with the A modulation factor as much as possible so that the B point voltage maintains a PWM of around 50%. For this reason, when the A modulation rate Da exceeds ± 1.0, the control device 12 of the power supply device 1 controls the line voltage with the B modulation rate Db being zero in the range where the A modulation rate Da is within ± 1.0. The amount of A modulation factor Da exceeding ± 1.0 is compensated by increasing the B modulation rate Db.

  The voltage Vbn applied between the second inductor L2, the transformer T, and the first capacitor C1 is a difference voltage between the B point voltage and the midpoint voltage of the first and second bridge capacitors Cdc1 and Cdc2. For this reason, when the third and fourth switching elements S2P and S2N operate at an ON ratio of about 50%, the voltage Vbn is the same voltage as that of a known LLC converter. When the voltage Vbn is an ON ratio in the vicinity of 50%, it is possible to contribute to a reduction in the number of input filters and a reduction in size, and an inverter circuit can be connected between BN without a drive circuit.

FIG. 7 is a diagram illustrating a gain characteristic of a voltage transmitted to the secondary side of the transformer T with respect to the switching frequency fc for the third and fourth switching elements S2P and S2N. FIG. 7 shows gain characteristics when the third and fourth switching elements S2P and S2N operate at an ON ratio of around 50%.
On the higher frequency side than the resonance frequency of the second inductor L2 and the first capacitor C1, the gain is lowered by increasing the switching frequency of the third and fourth switching elements S2P and S2N. The output can be lowered by lowering the gain. Conversely, by lowering the switching frequency of the third and fourth switching elements S2P and S2N, the gain can be increased and the output can be increased.

  As described above, the power supply device 1 according to the first embodiment performs charging of the bridge capacitors Cdc1 and Cdc2 from the system voltage and control of the power factor of the alternating current in the entire H bridge 21 of the power supply circuit 11, and The power transmission (output voltage control) to the secondary side of the transformer T is controlled by the half of the B side of the H bridge. In the above-described power supply circuit 11, the third and fourth switching elements S2P and S2N also serve as two power conversion operations. As a result, the power supply circuit 11 has a reduced number of circuit stages as compared with the circuit of the conventional power supply device shown in FIG. 11, for example, and the number of parts can be reduced and loss can be suppressed.

  That is, the power supply device according to the first embodiment can realize a PFC operation for controlling the input current and a rectifier operation for controlling the capacitor voltage of the H bridge by adjusting the low frequency component of the output voltage of the H bridge. In addition, by changing the switching frequency of the switching elements (third and fourth switching elements) constituting the half bridge of the H bridge connected to the transformer, the DC / DC converter operation for controlling the load voltage is performed. realizable. Therefore, the power supply device according to the first embodiment can realize the three circuit functions of the rectifier, the PFC, and the DC / DC converter in the conventional power supply circuit shown in FIG. Loss and number of parts can be reduced.

(Second Embodiment)
Next, a second embodiment will be described.
FIG. 8 is a diagram illustrating a configuration example of the power supply device 101 according to the second embodiment.
As illustrated in FIG. 8, the power supply device 101 according to the second embodiment includes a power supply circuit 111 and a control device 112. The control device 112 can be realized with the same configuration as the control device 12 shown in FIG. 2 described in the first embodiment. In the configuration shown in FIG. 8, components that can be realized by the same components as those described in the first embodiment shown in FIG.

  The power supply circuit 111 shown in FIG. 8 includes a point where the first and second bridge capacitors Cdc1 and Cdc2 are replaced with a bridge capacitor Cdc, a point B of the H bridge 21 and one end of the bridge capacitor (the H bridge negative side or the H bridge side). The second inductor L2, the primary winding T1 of the transformer T, and the first capacitor C1 are connected in series to the positive electrode side), and is different from the power supply circuit 11 shown in FIG. 1 described in the first embodiment. .

  That is, the power supply apparatus 101 according to the second embodiment performs PWM control on the first and second switching elements S1P and S1N side and the third and fourth switching elements S2P and S2N side in the H bridge 21 with the first embodiment. It can be realized by similar control. However, in the power supply circuit 111 of the power supply device 101 according to the second embodiment, the first capacitor C1 has both functions of a resonance converter and a DC cut-off. For this reason, the power supply circuit 111 is slightly different from the power supply circuit 11 described in the first embodiment in the selection of constants.

  In the power supply device 101, the voltage Vbn ′ applied to the second inductor L2, the primary winding T1 of the transformer T, and the first capacitor C1 is the third and fourth switching elements S2P and S2N in the H bridge 21. Is the difference voltage between the output voltage at point B, which is the connection point, and the potential at one end of one bridge capacitor Cdc.

  Also in the power supply device 101 according to the second embodiment, the bridge of the third and fourth switching elements S2P and S2N in the H bridge 21 is controlled so that the ON ratio is about 50%. The voltage Vbn ′ in the H bridge 21 of the power supply circuit 111 outputs “+ Vdc” or “−Vdc” at a ratio of about 50% with respect to the potential (= Vdc) of one bridge capacitor Cdc. Also in this case, only the high-frequency component due to switching is applied to each of the second inductor L2 and the primary winding T1 of the transformer T.

  Therefore, also in the power supply device 101 according to the second embodiment, the magnitude of the difference between the low frequency component of the output voltage Vab of the H bridge 21 applied to the first inductor L1 and the AC power supply voltage Vac is as follows. Can be arbitrarily adjusted by controlling the output voltage Vab. That is, the magnitude of the inductor current (power supply current) flowing through the first inductor L1 can be adjusted by controlling the low frequency component of the output voltage Vab of the H bridge 21. With this characteristic, the power supply device 101 operates as a rectifier and a PFC by controlling switching of each switching element of the H bridge 21.

  The voltage applied to the second inductor L2 and the primary winding T1 of the transformer T is a high-frequency voltage generated by switching of the H bridge 21. The frequency of the high-frequency voltage varies depending on the switching frequency of the third and fourth switching elements. Since the second inductor L2 has a constant inductor, the impedance changes depending on the frequency. Using this characteristic, the voltage applied to the second inductor L2 can be adjusted by controlling the voltage Vbn ′ to adjust the voltage applied to the transformer T, thereby controlling the load voltage (output voltage). That is, the power supply device 101 operates as a DC / DC converter by controlling the switching of the third and fourth switching elements S2P and S2N in the H bridge 21.

  As described above, the power supply apparatus according to the second embodiment can realize the PFC operation for controlling the input current and the rectifier operation for controlling the capacitor voltage of the H bridge, and can change the switching frequency of the half bridge of the H bridge. By doing so, it is possible to realize a DC / DC converter operation for controlling the load voltage. Therefore, according to the second embodiment, the number of parts constituting the circuit can be reduced, and a power supply apparatus with low loss and high conversion efficiency can be realized.

(Third embodiment)
Next, a third embodiment will be described.
In the third embodiment, only differences from the first embodiment will be described.

FIG. 9 is a diagram illustrating a configuration of a power supply device 201 according to the third embodiment.
The power supply device 201 includes a power supply circuit 211 and a control device 212. Instead of detecting the output voltage Vout related to the load 3, the power supply circuit 211 detects the voltage Vout ′ using the voltage detection tertiary winding T <b> 3 in the transformer T. The control device 212 varies the switching frequency of the third and fourth switching elements S2P and S2N based on the voltage Vout ′ detected using the voltage detection tertiary winding T3, thereby outputting the load to the load 3 The voltage Vout is controlled.

  That is, the power supply circuit 211 includes a load voltage detection unit 226 instead of the output voltage detection unit 26 shown in FIG. The load voltage detection unit 226 includes a tertiary winding T3 of the transformer T, a rectifier circuit, and a voltage detection unit. The tertiary winding T3 of the transformer T is electromagnetically coupled to the primary winding T1. The tertiary winding T3 of the transformer T detects a voltage appearing at the transformer T. The rectifier circuit rectifies the voltage detected by the tertiary winding T3. For example, the rectifier circuit includes two diodes and a capacitor. The voltage detector detects the voltage Vout ′ rectified by the rectifier circuit.

  The voltage appearing at the secondary winding T2 and the tertiary winding T3 of the transformer T is determined by the voltage applied to the primary winding T1 of the transformer T. The voltage appearing in the secondary winding T2 of the transformer T and the voltage appearing in the tertiary winding T3 exhibit the same behavior. Therefore, even if the output voltage Vout applied to the load 3 connected to the secondary winding T2 of the transformer T is not directly detected, a tertiary winding is added and the voltage detected using the tertiary winding. By controlling based on this, it becomes possible to control the load voltage Vout on the secondary side of the transformer T.

  The control device 212 is often configured with reference to the primary side potential. For this reason, components such as an insulation amplifier are required to detect the secondary side voltage. In contrast, by controlling the switching frequency by the voltage Vout ′ detected by adding the tertiary winding T3 to the transformer T, the control can be realized without additional components such as an insulation amplifier.

Moreover, although the above-mentioned 3rd Embodiment was demonstrated as the power supply circuit 211 which deform | transformed the power supply circuit 11 demonstrated in 1st Embodiment, 3rd Embodiment is the power supply circuit demonstrated in 2nd Embodiment. 111 may be applied.
FIG. 10 is a diagram illustrating a modification of the power supply device according to the third embodiment.
The power supply device 301 includes a power supply circuit 311 in which a load voltage detection unit 326 including a tertiary winding of a transformer is added instead of the output voltage detection unit 26 of the power supply circuit 111 described in the second embodiment.

  That is, the load voltage detection unit 326 of the power supply circuit 311 shown in FIG. 10 can be realized by the same configuration as the load voltage detection unit 226 shown in FIG. That is, in the power supply device 301, the load voltage detection unit 326 of the power supply circuit 311 detects the voltage Vout ′ using the voltage detection tertiary winding T <b> 3 in the transformer T. The control device 312 of the power supply device 301 varies the switching frequency of the third and fourth switching elements S2P and S2N based on the voltage Vout ′ detected by the load voltage detection unit 326, thereby outputting the load voltage Vout output to the load 3. To control.

  According to the third embodiment as described above, the three circuit functions of the rectifier, the PFC, and the DC / DC converter can be realized by a power supply circuit including one H bridge, and without additional components such as an insulation amplifier. A power supply device can be realized. As a result, the power supply device according to the third embodiment can realize a reduction in the number of components and a low loss.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1, 101, 201, 301 ... Power supply device 11, 111, 211, 311 ... Power supply circuit 12, 112, 212, 312 ... Control device (control part), 12A ... Power factor control part, 12B ... Output voltage control part , 21 ... H bridge, 22 ... rectifier, 23 ... input voltage detector (first voltage detector), 24 ... power supply current detector (current detector), 25 ... capacitor voltage detector (second voltage detector) ), 26... Output voltage detector (third voltage detector), 226, 326... Load voltage detector, C1... First capacitor, Cdc1... First bridge capacitor, Cdc2. Bridge capacitor, L1 ... first inductor, L2 ... second inductor, S1N ... second switching element (switch), S1P ... first switching element (switch), S2 ... fourth switching element (switch), S2P ... third switching element (switch), T ... transformer, T1 ... 1 winding, T2 ... 2 windings, T3 ... 3 winding.

Claims (7)

An H-bridge in which a first and a second switch connected in series, a third and a fourth switch connected in series, and two bridge capacitors connected in series are connected in parallel;
A first inductor connected in series between a connection point of the first and second switches and an AC power source;
A second inductor having one end connected to a connection point of the third and fourth switches;
A first capacitor having one end connected to a neutral point of the two bridge capacitors;
A transformer having a primary winding connected in series between the other end of the second inductor and the other end of the first capacitor, and a secondary winding electromagnetically coupled to the primary winding;
A rectifier connected to the secondary winding of the transformer;
A control unit for controlling a switching signal given to each switch;
A power supply apparatus comprising: An H bridge in which a first and a second switch connected in series, a third and a fourth switch connected in series, and a bridge capacitor are connected in parallel;
A first inductor connected in series between a connection point of the first and second switches and an AC power source;
A second inductor having one end connected to a connection point of the third and fourth switches;
A first capacitor having one end connected to one end of the bridge capacitor;
A transformer having a primary winding connected in series between the other end of the second inductor and the other end of the first capacitor and a secondary winding electromagnetically coupled to the primary winding;
A rectifier connected to the secondary winding of the transformer;
A control unit for controlling a switching signal given to each switch;
A power supply apparatus comprising: First voltage detection means for detecting a power supply voltage of the AC power supply;
Current detection means for detecting a power supply current flowing through the first inductor;
Second voltage detecting means for detecting a capacitor voltage of the H bridge;
A third voltage detecting means for detecting a load voltage output from the rectifier,
The control unit generates a signal for driving each switch of the H bridge using the power supply voltage, the power supply current, the capacitor voltage, and the load voltage.
The power supply device according to claim 1, wherein the power supply device is a power supply device. A tertiary winding is provided on the transformer,
The third voltage detecting means detects the load voltage by a tertiary winding provided in the transformer;
The power supply device according to claim 3, wherein: The control unit controls a capacitor voltage of the H bridge by controlling a switching signal given to each switch so that a power supply current flowing through the first inductor is in phase with a power supply voltage of the AC power supply.
The power supply device according to any one of claims 1 to 4, wherein the power supply device is provided. The control unit controls a load voltage output from the rectifier by controlling a frequency of a switching signal applied to the third and fourth switches;
The power supply device according to any one of claims 1 to 5, wherein the power supply device is any one of the above.   The AC adapter which has a power supply device in any one of the said Claims 1 thru | or 6.