Power supply circuit and power supply device

Abstract

To provide a power supply circuit and a power supply device capable of reducing a conduction loss and controlling an OR connection switch by a simple method.SOLUTION: In a power supply device 1, a power supply circuit 100 comprises: a main transformer 20 that has a first primary side coil 21 and a first secondary side coil 22; a primary side main switch part 10; a first secondary side rectification part 30; an OR connection switch 40 in which a body diode is arranged in such a direction that a backflow of current from an output terminal is prevented; and a drive transformer 50 that has a second primary side coil 51 and a second secondary side coil 52, the second primary side coil 51 being connected in parallel with the first secondary side coil 22, one end of the second secondary side coil 52 being connected with a gate electrode of the OR connection switch 40, the other end of the second secondary side coil 52 being connected with an anode (a source electrode) of the body diode in the OR connection switch 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply circuit and a power supply device. [Background technology]

[0002] Conventionally, power supply devices have been known that have a redundant configuration in which multiple power supply circuits (converters) are connected in parallel. Such power supply devices are provided with a selective shutdown circuit to prevent a drop in output voltage when one of the multiple power supply circuits fails.

[0003] FIG. 5 is a circuit diagram showing a conventional power supply device 9 and a power supply circuit 900. As shown in FIG. 5, the conventional power supply device 9 has multiple power supply circuits 900 connected in parallel, each of which includes a converter unit CONV and an OR diode 940 provided on the output side of the converter unit CONV and oriented to block current from flowing from the output terminal toward the converter unit CONV. The OR diodes 940 in each power supply circuit 900 form a selective cutoff circuit SCC, with their cathodes connected to each other to form an OR circuit. This prevents a drop in output voltage even if one of the multiple power supply circuits fails. It also prevents current from flowing back toward the failed power supply circuit from other power supply circuits, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 209238 Summary of the Invention [Problem to be solved by the invention]

[0005] Recently, there has been a demand for power supply devices that can reduce conduction loss. To address this issue, it has been considered to use switching elements, which have lower conduction loss than diodes, instead of OR diodes, which have relatively large conduction losses due to voltage drop (see, for example, Patent Document 1). However, to turn on the switching element, a voltage exceeding the output voltage must be applied to the gate electrode, and the gate voltage must be increased using, for example, a floating auxiliary power supply. Therefore, when the output voltage is large (for example, several hundred volts), it is not easy to supply a voltage exceeding the output voltage to control the OR connection switch.

[0006] Therefore, the present invention has been made to solve such problems, and aims to provide a power supply circuit that is capable of reducing conduction loss and capable of controlling an OR connection switch in a simple manner, and to provide a power supply device that includes such a power supply circuit. [Means for solving the problem]

[0007] The power supply circuit of the present invention is characterized by comprising: a main transformer having a first primary coil and a first secondary coil; a primary main switch section connected to the first primary coil and composed of a switching element; a first secondary rectifier section connected to the first secondary coil; an OR connection switch having a body diode oriented so as to prevent reverse current flow from an output terminal; and a drive transformer having a second primary coil and a second secondary coil, the second primary coil being connected in parallel with the first secondary coil, one end of the second secondary coil being connected to a gate electrode of the OR connection switch and the other end being connected to the body diode of the OR connection switch.

[0008] In addition, when a drive transformer or main transformer has three or more terminals, such as when it has a center tap, "one end" of the drive transformer or main transformer refers to at least one of the three or more terminals, and "the other end" refers to at least one of the three or more terminals other than the terminal at "one end."

[0009] A power supply device according to the present invention includes a plurality of power supply circuits according to the present invention, and the output terminals of the plurality of power supply circuits are connected to each other. [Effects of the Invention]

[0010] The power supply circuit and power supply device of the present invention are provided with an OR connection switch whose body diode is oriented so as to prevent current from flowing back from the output terminal, and therefore can reduce conduction loss due to forward voltage drop compared to when a diode is used to prevent current from flowing back from the output terminal.

[0011] Furthermore, the power supply circuit and power supply device of the present invention include a drive transformer having a second primary coil and a second secondary coil, the second primary coil connected in parallel with the first secondary coil, one end of the second secondary coil connected to the gate electrode of the OR connection switch and the other end connected to the body diode of the OR connection switch, so that when an electromotive force is generated in the first secondary coil, a voltage is applied to the second primary coil, and the OR connection switch can be turned on by the induced voltage generated in the second secondary coil. Therefore, even when the output voltage is large, there is no need to use an auxiliary power supply to supply a voltage exceeding the output voltage, and it is possible to control the OR connection switch 40 by the simple method of providing a drive transformer.

[0012] Furthermore, the power supply circuit and power supply device of the present invention include a drive transformer having a second primary coil and a second secondary coil, the second primary coil being connected in parallel with the first secondary coil, one end of the second secondary coil being connected to the gate electrode of the OR connection switch, and the other end being connected to the body diode of the OR connection switch. Therefore, it is possible to control the on / off of the OR connection switch without changing the configuration of the main transformer to turn on the OR connection switch. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a circuit diagram showing a power supply device 1 and a power supply circuit 100 according to Embodiment 1. Note that the reference character RL indicates a load, and the diode shown in the OR connection switch reference character 40 indicates a body diode. [Figure 2] 2 is a circuit diagram illustrating the operation of the power supply circuit 100 when switching elements Q2 and Q3 are turned on. FIG. [Figure 3] 2 is a circuit diagram illustrating the operation of the power supply circuit 100 when switching elements Q1 and Q4 are turned on. FIG. [Figure 4] FIG. 10 is a circuit diagram showing a power supply device 2 and a power supply circuit 102 according to a second embodiment. [Figure 5] 1 is a circuit diagram showing a conventional power supply device 9 and a power supply circuit 900. Note that reference numeral 910 denotes a primary side main switch unit, reference numeral 920 denotes a transformer, reference numeral 921 denotes a primary side coil, reference numeral 922 denotes a secondary side coil, and reference numeral 930 denotes a secondary side rectifier unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] The power supply circuit and power supply device of the present invention will be described below based on the embodiments shown in the drawings. Note that the embodiments described below do not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0015] [Embodiment 1] 1. Configuration of power supply device 1 according to embodiment 1 Fig. 1 is a circuit diagram showing a power supply device 1 and a power supply circuit 100 according to a first embodiment. As shown in Fig. 1, the power supply device 1 according to the first embodiment includes a plurality of power supply circuits 100 (two in the first embodiment) connected in parallel. Each power supply circuit 100 is provided with a pair of output terminals Te3, Te4, and an OR connection switch 40 having a body diode cathode connected to the output terminal Te3, and the output terminals Te3 are connected to each other, and the output terminals Te4 are connected to each other. As a result, the cathodes of the body diodes of the OR connection switches 40 are connected to each other to form an OR circuit, which constitutes a selective shutoff circuit SCC.

[0016] The power supply circuit 100 according to the first embodiment includes a primary-side main switch unit 10, a main transformer 20, a first secondary-side rectifier unit 30, an OR switch 40, a drive transformer 50, a second secondary-side rectifier unit 60, an input capacitor C1, an output capacitor C2, a pair of input terminals Te1 and Te2, and a pair of output terminals Te3 and Te4. The primary-side main switch unit 10, the main transformer 20, and the first secondary-side rectifier unit 30 form a converter unit CONV. The power supply circuit 100 according to the first embodiment is, for example, a DC-DC converter.

[0017] Of the pair of input terminals Te1 and Te2, the input terminal Te1 is connected to a DC power supply (not shown), and the input terminal Te2 is connected to a reference potential, and receives an input voltage (DC voltage) Vin. The input terminal Te1 is also connected to a power supply line L1.

[0018] Of the pair of output terminals Te3 and Te4, the output terminal Te3 is the high-side output terminal and the output terminal Te4 is the low-side output terminal, and they output an output voltage Vout. The output terminal Te3 is connected to the power supply line L2, and the output terminal Te4 is connected to the power supply line L3.

[0019] The primary-side main switch unit 10 is a full-bridge drive circuit in which serially connected switching elements Q1 and Q2 and serially connected switching elements Q3 and Q4 are connected in parallel. The midpoint (connection point) of the switching elements Q1 and Q2 is connected to one end of a first primary-side coil 21, and the midpoint of the serially connected switching elements Q3 and Q4 is connected to the other end of the first primary-side coil 21. The drain electrode of the switching element Q1 (Q3) is connected to the high-side input terminal Te1, and the source electrode is connected to the drain electrode of the switching element Q2 (Q4). The drain electrode of the switching element Q2 (Q4) is connected to the source electrode of the switching element Q1 (Q3), and the source electrode is connected to a reference potential. The switching elements Q1, Q2, Q3, and Q4 may be, for example, n-type MOSFETs (n-type field-effect transistors), but other suitable switching elements such as IGBTs may also be used. In the first embodiment, a full-bridge type drive circuit is used as the primary side main switch section 10, but a half-bridge type or other appropriate drive circuit may be used.

[0020] The input capacitor C1 has one end connected to the power supply line L1 and the other end connected to the low-side input terminal Te2 and the reference potential, and smoothes the DC voltage.

[0021] The main transformer 20 has a first primary coil 21 and a first secondary coil 22. In the main transformer 20, when a voltage supplied from the primary main switch unit 10 is applied to the first primary coil 21, an electromotive force converted in accordance with a winding ratio is generated in the first secondary coil 22. The first secondary coil 22 is connected to a first secondary rectifier unit 30.

[0022] The first secondary-side rectifier 30 has rectifier diodes D1, D2, D3, and D4, and is a full-bridge rectifier circuit in which the rectifier diodes D1 and D2 connected in series and the rectifier diodes D3 and D4 connected in series are connected in parallel. The midpoint of the rectifier diodes D1 and D2 (the wiring between the rectifier diodes D1 and D2) is connected to one end of the first secondary-side coil 22 and one end of the second primary-side coil 51 of the drive transformer 50, and the midpoint of the rectifier diodes D3 and D4 is connected to the other end of the first secondary-side coil 22 and the other end of the second primary-side coil 51 of the drive transformer 50. The cathodes of the rectifier diodes D1 and D3 are connected to the power supply line L2. The anode of the rectifier diode D1 is connected to the cathode of the rectifier diode D2, one end of the first secondary coil 22, and one end of the second primary coil 51. The anode of the rectifier diode D2 is connected to the power supply line L3. The cathode of the rectifier diode D3 is connected to the power supply line L2. The anode of the rectifier diode D3 is connected to the cathode of the rectifier diode D4, the other end of the first secondary coil 22, and the other end of the second primary coil 51. The anode of the rectifier diode D4 is connected to the power supply line L3. In the first embodiment, a full-bridge rectifier circuit is used as the first secondary-side rectifier unit 30, but a half-bridge rectifier circuit or any other appropriate rectifier circuit may be used.

[0023] The output capacitor C2 is disposed between the high-side power supply line L2 and the low-side power supply line L3, and smoothes the output voltage.

[0024] The ORing switch 40 (switch Q5) is an n-type MOSFET connected to the high-side output terminal Te3 via the power supply line L2. The ORing switch 40 has an anode (source electrode of the MOSFET) of its body diode connected to the first secondary-side rectifier 30. The cathode (drain electrode of the MOSFET) of the body diode is connected to the output terminal Te3. In other words, the body diode is oriented so as to prevent reverse current flow from the high-side output terminal Te3 toward the first secondary-side rectifier 30. The gate electrode of the ORing switch 40 is connected to the second secondary-side coil 52 of the drive transformer 50 via the second secondary-side rectifier 60. When an electromotive force is generated in the first secondary-side coil 22 of the main transformer 20, a voltage is applied to the second primary-side coil 51 of the drive transformer 50, which induces an electromotive force in the second secondary-side coil 52, applying a voltage to the gate electrode. This turns on the gate electrode.

[0025] The drive transformer 50 has a second primary coil 51 and a second secondary coil 52, and the second primary coil 51 is connected in parallel with the first secondary coil 22. One end of the second secondary coil 52 is connected to the gate electrode of the OR connection switch 40 via the second secondary rectifier 60, and the other end is connected to the anode (source electrode) of the body diode in the OR connection switch 40 and the power supply line L2.

[0026] The second secondary rectifier 60 is a half-wave rectifier circuit having a diode D5 and a capacitor C3. The second secondary rectifier 60 is connected between the second secondary coil 52 and the gate electrode of the OR connection switch 40. The anode of the diode D5 is connected to one end of the second secondary coil 52, and the cathode is connected to the gate electrode of the OR connection switch 40 and the capacitor C3. The capacitor C3 has one end connected to the cathode of the diode D5 and the gate electrode of the OR connection switch 40, and the other end connected to the other end of the second secondary coil 52 and the power supply line L2.

[0027] Next, the operation of the power supply circuit according to embodiment 1 will be described. Fig. 2 is a circuit diagram shown to explain the operation of the power supply circuit 100 when switching elements Q2 and Q3 are turned on. Fig. 3 is a circuit diagram shown to explain the operation of the power supply circuit 100 when switching elements Q1 and Q4 are turned on.

[0028] When switching elements Q2 and Q3 are turned on, as shown in FIG. 2, a voltage as indicated by the solid line in FIG. 2 is applied to the first primary coil 21 of the main transformer 20. At this time, the main transformer 20 generates an electromotive force in the first secondary coil 22 according to the winding ratio (see the dashed line in FIG. 2). The electromotive force generated in the first secondary coil 22 is rectified by the first secondary rectifier 30, converted into a DC voltage by the output capacitor C2, and applied to the source electrode of the ORing switch 40. In addition, a voltage is applied to the second primary coil 51. The voltage applied to the second primary coil 51 generates an induced voltage in the second secondary coil 52 of the drive transformer 50, which is rectified by the second secondary rectifier 60, converted into a DC voltage, and applied to the gate electrode of the ORing switch 40. At this time, the capacitor C3 of the second secondary rectifier 60 is charged. As a result, the ORing switch 40 is turned on, and the voltage from the first secondary coil 22 passes through the ORing switch 40 and is applied to the output terminal Te3.

[0029] When the switching elements Q1 and Q4 are turned on, a voltage as shown by the solid line in FIG. 3 is applied to the first primary coil 21 of the main transformer 20. At this time, an electromotive force corresponding to the winding ratio is generated in the first secondary coil 22 of the main transformer 20 in the direction shown by the dashed line in FIG. 3. The electromotive force generated in the first secondary coil 22 is rectified by the first secondary rectifier 30, converted to a DC voltage by the output capacitor C2, and applied to the ORing switch 40. Furthermore, a voltage is applied from the first secondary coil 22 to the second primary coil 51 of the drive transformer 50, and an electromotive force is induced in the second secondary coil 52. However, since this voltage is the reverse voltage of the diode D5 of the second secondary rectifier 60, no voltage is applied to the gate electrode of the ORing switch 40. However, a voltage is applied from the capacitor C3, which was charged when the switching elements Q1 and Q4 were turned on, and the gate electrode of the ORing switch 40 remains on.

[0030] If a malfunction occurs on the primary side and no voltage is applied to the first primary coil 21, no electromotive force is generated in the first secondary coil 22, and no voltage is applied to the output terminal Te3. Furthermore, since no voltage is applied to the drive transformer 50, the gate electrode of the OR connection switch 40 is not turned on (when the switching elements Q1, Q2, Q3, and Q4 are turned off, no voltage is applied after the capacitor C3 is discharged). Therefore, the OR connection switch 40 acts as a diode, preventing current from flowing back from another power supply circuit to the converter unit CONV.

[0031] 2. Effects of the power supply device 1 and the power supply circuit 100 according to the first embodiment The power supply device 1 and power supply circuit 100 according to the first embodiment are provided with an OR connection switch 40 having a body diode oriented to prevent current from flowing from the output terminal Te3 toward the first secondary side rectification unit 30, thereby reducing conduction loss due to forward voltage drop compared to when a diode is used.

[0032] Furthermore, the power supply device 1 and power supply circuit 100 according to the first embodiment include a drive transformer 50 having a second primary coil 51 and a second secondary coil 52, the second primary coil 51 being connected in parallel with the first secondary coil 22, one end of the second secondary coil 52 being connected to the gate electrode of the OR connection switch 40, and the other end being connected to the body diode of the OR connection switch 40. Therefore, when an electromotive force is generated in the first secondary coil 22, a voltage is applied to the second primary coil 51, and an induced voltage generated in the second secondary coil 52 turns on the OR connection switch 40. Therefore, even when the output voltage is large, there is no need to use an auxiliary power supply to supply a voltage exceeding the output voltage, and it is possible to control the OR connection switch 40 using the simple method of providing the drive transformer 50.

[0033] Furthermore, the power supply device 1 and power supply circuit 100 according to the first embodiment include the drive transformer 50, which eliminates the need to change the configuration of the main transformer 20 in order to turn on the OR connection switch 40. Therefore, it is possible to control the on / off of the OR connection switch simply by using a relatively small transformer, without changing the specifications of the main transformer 20, which is large and difficult to change in configuration.

[0034] Furthermore, the power supply device 1 and power supply circuit 100 according to the first embodiment include the second secondary rectification unit 60 connected between the second secondary coil 52 and the gate electrode of the OR connection switch 40, and therefore the voltage applied to the second secondary coil 52 can be rectified and converted into a DC voltage to be used as the voltage applied to the gate electrode of the OR connection switch 40. Therefore, the on / off of the OR connection switch 40 can be controlled in accordance with the voltages applied to the first primary coil 21 and the first secondary coil 22.

[0035] Furthermore, according to the power supply device 1 and power supply circuit 100 of embodiment 1, the second secondary rectification unit 60 includes a diode D5 (rectification element) having an anode connected to one end of the second secondary coil 52 and a cathode connected to the gate electrode of the OR connection switch 40, and a capacitor C3 connected between the cathode of the diode D5 and the other end of the second secondary coil 52. This makes it possible, with a small number of components, to use the electromotive force generated in the second secondary coil 52 as a voltage used to turn on and off the OR connection switch 40. Furthermore, since the capacitor C3 is included, the power charged when the switching elements Q1 and Q4 are turned on can be maintained as a voltage when the switching elements Q2 and Q3 are turned on, thereby keeping the OR connection switch 40 on.

[0036] Furthermore, according to the power supply device 1 and power supply circuit 100 of embodiment 1, the cathode of the body diode in the OR connection switch 40 is connected to the high-side output terminal Te3 of the pair of output terminals, so that it is possible to reliably protect the high-side side, which is likely to be significantly affected when current flows back from another power supply circuit.

[0037] Furthermore, in the power supply device 1 and power supply circuit 100 according to the first embodiment, the OR connection switch 40 is a field effect transistor, which results in a lower voltage drop and reduced conduction loss than in the case of a diode. Also, less drive power is required to turn on the gate.

[0038] Furthermore, according to the power supply device 1 of the first embodiment, since the output terminals of the multiple power supply circuits 100 are connected to each other, it is possible to configure a selective cutoff circuit for preventing a drop in output voltage when one of the multiple power supply circuits fails, and it is also possible to prevent current from flowing back from other power supply circuits toward the failed power supply circuit.

[0039] [Embodiment 2] 4 is a circuit diagram showing a power supply device 2 and a power supply circuit 102 according to embodiment 2. The power supply device 2 and the power supply circuit 102 according to embodiment 2 basically have the same configuration as the power supply device 1 and the power supply circuit 100 according to embodiment 1, but the configuration of the second secondary side rectification unit is different from that of the power supply device 1 and the power supply circuit 100 according to embodiment 1. In the power supply device 2 and the power supply circuit 102 according to embodiment 2, the second secondary side rectification unit 62 is a center-tap type full-wave rectification type rectification circuit (see FIG. 4).

[0040] The second secondary side rectifier 62 includes diodes D5 and D6 and a capacitor C3. The anode of the diode D5 is connected to one end of the second secondary coil 52, and the cathode of the diode D5 is connected to the capacitor C3, the gate electrode of the OR switch 40, and the cathode of the diode D6. The anode of the diode D6 is connected to the other end of the second secondary coil 52, and the cathode of the diode D6 is connected to the capacitor C3, the gate electrode of the OR switch 40, and the cathode of the diode D5. One end of the capacitor C3 is connected to the cathodes of the diodes D5 and D6 and the gate electrode of the OR connection switch 40, and the other end of the capacitor C3 is connected to the power supply line L2 and the center tap of the second secondary coil 52.

[0041] In the second secondary side rectifier 62, even when the switching elements Q1 and Q4 are turned on, the electromotive force generated in the second secondary side coil 52 passes through the diode D6 of the second secondary side rectifier 60, is converted to DC by the capacitor C3, and is applied to the gate electrode of the OR connection switch 40. Therefore, when an electromotive force is generated in the second secondary side coil 52, the OR connection switch 40 can be kept on. Since the OR connection switch 40 can be kept on without relying on the charging of the capacitor C3, this is suitable when the interval between on / off switching of the primary side main switch unit 10 is relatively long.

[0042] In the second embodiment, a center-tap rectifier circuit is used as the second secondary side rectifier 62, but it may also be a bridge rectifier circuit using four diodes, or a rectifier circuit consisting of two sets of half-wave rectifier circuits connected in series, or any other suitable full-wave rectifier circuit.

[0043] As described above, the power supply device 2 and power supply circuit 102 of the second embodiment differ in the configuration of the second secondary side rectification unit from the power supply device 1 and power supply circuit 100 of the first embodiment, but like the power supply device 1 and power supply circuit 100 of the first embodiment, they are provided with an OR connection switch 40 whose body diode is oriented to prevent current from flowing from the output terminal Te3 toward the first secondary side rectification unit 30, thereby reducing conduction loss due to forward voltage drop compared to when a diode is used.

[0044] Furthermore, the power supply device 2 and power supply circuit 102 according to the second embodiment include a drive transformer 50 having a second primary coil 51 and a second secondary coil 52, the second primary coil 51 being connected in parallel with the first secondary coil 22, one end of the second secondary coil 52 being connected to the gate electrode of the OR connection switch 40, and a center tap being connected to the body diode of the OR connection switch 40. Therefore, when a voltage is applied to the first secondary coil 22, a voltage is applied to the second primary coil 51, and an induced voltage generated in the second secondary coil 52 turns on the OR connection switch 40. Therefore, even when the output voltage is large, there is no need to use an auxiliary power supply for supplying a voltage exceeding the output voltage, and it is possible to control the OR connection switch 40 using the simple method of providing the drive transformer 50.

[0045] Furthermore, according to the power supply device 2 and power supply circuit 102 of embodiment 2, the second secondary side rectification unit 62 is a full-wave rectification circuit, so that the on / off of the OR connection switch 40 can be controlled even when the interval between on / off switching of the primary side main switch unit 10 is relatively long.

[0046] The power supply device 2 and power supply circuit 102 of embodiment 2 have the same configuration as the power supply device 1 and power supply circuit 100 of embodiment 1 except for the configuration of the second secondary side rectification section, and therefore have the corresponding effects of the power supply device 1 and power supply circuit 100 of embodiment 1.

[0047] Although the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0048] (1) The positions, sizes, etc. described in the above embodiments (including the modified examples; the same applies below) are merely examples and can be changed within the scope that does not impair the effects of the present invention.

[0049] (2) In each of the above embodiments, the power supply device includes two power supply circuits, but the present invention is not limited to this. Three or more power supply circuits may be included.

[0050] (3) In the above embodiments, field-effect transistors (MOSFTs) are used as switching elements, but the present invention is not limited to this. IGBTs, thyristors, triacs, and other suitable switching elements can be used as switching elements.

[0051] (4) In the above embodiments, the ORing switch is disposed on the high side, but the present invention is not limited to this. The ORing switch may be disposed on the low side. In this case, the anode of the body diode is on the output terminal side, and the cathode is on the first secondary-side rectifier side.

[0052] (5) In the above embodiments, an LLC resonant converter is used as the converter (DC-DC converter), but the present invention is not limited to this. A forward converter, a flyback converter, or any other suitable converter may be used as the converter (DC-DC converter). [Explanation of symbols]

[0053] 1,2,9...power supply unit, 10,910...primary side main switch unit, 20,920...main transformer, 21,921...first primary side coil, 22,922...first secondary side coil, 30,930...first secondary side rectifier unit, 40,940...OR connection switch, 50...drive transformer, 51...second primary side coil, 52...second secondary side coil, 60,62...second secondary side rectifier unit, 100,102,900...power supply circuit, C3...capacitor, D5,D6...diode, Q1,Q2,Q3,Q4...switching element, Te1,Te2...input terminal, Te3,Te4...output terminal

Claims

1. a main transformer having a first primary coil and a first secondary coil; a primary side main switch unit connected to the first primary side coil and configured with a switching element; a first secondary-side rectifier connected to the first secondary-side coil; an OR connection switch having a body diode oriented in such a direction as to prevent a current from flowing backward from the output terminal; a drive transformer having a second primary coil and a second secondary coil, the second primary coil being connected in parallel with the first secondary coil, one end of the second secondary coil being connected to a gate electrode of the OR connection switch and the other end being connected to the body diode of the OR connection switch; a second secondary rectifier connected between the second secondary coil and the gate electrode of the OR connection switch, the second secondary-side rectifier is a full-wave rectifier circuit, The drive transformer is a center tapped transformer, the output terminals are a pair of output terminals, a cathode of the body diode of the OR connection switch connected to a high-side output terminal of the pair of output terminals;

2. 2. The power supply circuit according to claim 1, wherein the OR connection switch is a field effect transistor.

3. a power supply circuit according to claim 1 or 2; A power supply device characterized in that output terminals of a plurality of said power supply circuits are connected to each other.

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