Power supply device

Abstract

The invention provides a power supply device which can fully protect overvoltage generated by resonance voltage generated when a power supply is started. An overvoltage protection circuit (5) connected between a first DC bus (11) and a second DC bus (12) includes a semiconductor switch (52). An overvoltage protection circuit (5) protects an inverter circuit (6), which is a circuit device, from an overvoltage operation when a semiconductor switch (52) is turned on. The drive circuit (9) is a circuit that drives the semiconductor switch (52). The drive circuit (9) is supplied with drive power by supplying power to the power supply terminal (PT), and the drive circuit (9) is brought into a drivable state in which the semiconductor switch (52) can be turned on during a first period from the start of the supply of power to the power supply terminal (PT) to the start of the rise of the DC voltage to 1 / 2 of the period of resonance generated in the closed circuit (CL), and the drive circuit (9) is brought into a driven state in which the semiconductor switch (52) can be turned on during a second period from the start of the supply of power to the power supply terminal (PT) to the start of the rise of the DC voltage. The closed circuit (CL) includes a power source (200), a capacitor (4), and an inductor (3).

Description

TECHNICAL FIELD

[0001] The present application relates to a power supply device that supplies electric power to a load. BACKGROUND

[0002] In Patent Literature 1 (Japanese Patent Application Publication No. 2020-124104), a power supply device is disclosed as one of power supply devices that supply electric power to a load. In the power supply device of Patent Literature 1, sometimes an electrolytic capacitor as a smoothing capacitor is not used, and a film capacitor having a smaller capacitance than the electrolytic capacitor is used. In an overvoltage protection circuit provided in the power supply device, a period from when a power source is turned on to when a drive circuit that drives the overvoltage protection circuit becomes a state in which the overvoltage protection circuit can turn on or off a semiconductor switch is sometimes longer than 1 / 2 of a period of an LC resonance voltage generated across the capacitor. SUMMARY

[0003] PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] If the period from when the power source is turned on to when the drive circuit becomes the state in which the overvoltage protection circuit can turn on or off is longer than 1 / 2 of the LC resonance period, sometimes the overvoltage protection circuit cannot act at a time when the power supply device is started and reaches an overvoltage. In particular, in a structure in which a power source that supplies drive electric power to the drive circuit is shared with a power source that supplies electric power to the power supply device, sometimes the overvoltage protection circuit cannot catch up with an overvoltage state.

[0005] In the power supply device, there is a problem of sufficiently protecting an overvoltage generated due to a resonance voltage generated at the time of starting the power source.

[0006] MEANS FOR SOLVING THE PROBLEMS

[0007] The power supply device of the first aspect includes a first DC bus to which a DC voltage is applied and a second DC bus having a lower potential than the first DC bus, and a capacitor connected between the first DC bus and the second DC bus, and converts DC power supplied to the first DC bus and the second DC bus to supply power to a load. The power supply device includes a power supply terminal, an inductor, a circuit device, an overvoltage protection circuit, and a drive circuit. The inductor is inserted into a wiring path from the power supply terminal to which power is supplied from a power supply to the first DC bus and the second DC bus. The circuit device is connected between the first DC bus and the second DC bus. The overvoltage protection circuit is connected between the first DC bus and the second DC bus, includes a semiconductor switch, and operates to protect the circuit device from an overvoltage when the semiconductor switch is turned on. The drive circuit is a circuit that drives the semiconductor switch. By supplying power to the power supply terminal, the drive circuit is supplied with drive power, and during a first period from when a DC voltage starts to rise in conjunction with the start of power supply to the power supply terminal to 1 / 2 of a period of resonance generated in a closed circuit including the power supply, the capacitor, and the inductor, the drive circuit becomes a drivable state in which the semiconductor switch can be turned on.

[0008] In the power supply device of the first aspect, the overvoltage protection circuit is driven by the drive circuit that becomes a drivable state in which the semiconductor switch can be turned on during a first period from when a DC voltage starts to rise to 1 / 2 of a period of resonance generated in a closed circuit. As a result, before the circuit device reaches an overvoltage due to resonance at the time of DC voltage rise, the semiconductor switch of the overvoltage protection circuit is turned on, overvoltage applied to the circuit device is suppressed, and the reliability of overvoltage protection for the power supply device can be improved.

[0009] Regarding the power supply device of the second aspect, on the basis of the power supply device of the first aspect, the line voltage between the first DC bus and the second DC bus is compared with a threshold voltage higher than the line voltage at the time of stabilization, and when the line voltage exceeds the threshold voltage, the drive circuit turns on the semiconductor switch.

[0010] Regarding the power supply device of the third aspect, on the basis of the power supply device of the first aspect or the second aspect, the circuit device is an inverter circuit connected between the first DC bus and the second DC bus and including a semiconductor element.

[0011] The power supply device according to the fourth aspect is the power supply device according to any one of the first to third aspects, wherein the power supply device has a first power supply circuit that supplies power to the drive circuit during a prescribed period including the first period, in association with the supply of power to the power supply terminal, and in the first power supply circuit, a first output voltage of the first power supply circuit reaches a voltage satisfying the drivable state during the first period.

[0012] The power supply device according to the fifth aspect is the power supply device according to the fourth aspect, further comprising a second power supply circuit that supplies power to the drive circuit during a second period after the prescribed period, and in the second power supply circuit, a second output voltage of the second power supply circuit reaches a voltage satisfying the drivable state after the first period and before the end of the prescribed period.

[0013] In the power supply device according to the fifth aspect, by using a power supply circuit having higher efficiency than the first power supply circuit for the second power supply circuit, it is possible to reduce the loss of the power supply circuit.

[0014] The power supply device according to the sixth aspect is the power supply device according to the fifth aspect, wherein the first power supply circuit is stopped after the second output voltage of the second power supply circuit reaches the voltage satisfying the drivable state.

[0015] In the power supply device according to the sixth aspect, by stopping the first power supply circuit after the second output voltage of the second power supply circuit reaches the voltage satisfying the drivable state, it is possible to reduce the power consumption in the first power supply circuit.

[0016] The power supply device according to the seventh aspect is the power supply device according to the fifth or sixth aspect, wherein the power capacity of the first power supply circuit is smaller than the power capacity of the second power supply circuit.

[0017] In the power supply device according to the seventh aspect, by reducing the power capacity of the first power supply circuit, it is possible to reduce the cost and size of the first power supply circuit. As a result, it is possible to suppress the increase in the cost and size of the power supply system that combines the first power supply circuit and the second power supply circuit to a lower level.

[0018] The power supply device according to the eighth aspect is the power supply device according to any one of the fifth to seventh aspects, further comprising a diode having an anode to which the second output voltage of the second power supply circuit is applied and a cathode to which the first output voltage of the first power supply circuit is applied, and the drive circuit is configured to receive the supply of power from the cathode of the diode.

[0019] The power supply device according to the ninth aspect is the power supply device according to any one of the fourth to eighth aspects, wherein the first power supply circuit includes a Zener diode and a current-limiting element or a current-limiting circuit that limits a current flowing through the Zener diode.

[0020] The power supply device according to the tenth aspect is the power supply device according to the ninth aspect, wherein the current-limiting circuit is a constant-current circuit.

[0021] The power supply device according to the eleventh aspect is the power supply device according to any one of the first to tenth aspects, wherein the power source is an alternating-current power source, and a rectifier that rectifies an alternating voltage of the alternating-current power source into a direct-current voltage is inserted in a wiring path from the power source terminal to the first direct-current bus and the second direct-current bus. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic view showing an example of the structure of the power supply device of the first embodiment.

[0023] Figure 2 is a schematic view showing another example of the structure of the power supply device of the first embodiment.

[0024] Figure 3 is a schematic view showing another example of the structure of the power supply device of the first embodiment.

[0025] Figure 4 is a schematic view showing another example of the structure of the power supply device of the first embodiment.

[0026] Figure 5 is a schematic view showing another example of the structure of the power supply device of the first embodiment.

[0027] Figure 6 is a block diagram showing an example of the structure of the power supply device of the second embodiment.

[0028] Figure 7 is a circuit diagram showing an example of the structure of the power supply device of the third embodiment.

[0029] Figure 8 is a circuit diagram of the voltage detection circuit, the power supply circuit for the comparator, and the direct-current portion voltage comparator of Figure 7

[0030] Figure 9 is a circuit diagram of the first power supply circuit, the second power supply circuit, and the power source switching portion of Figure 7

[0031] Figure 10 is a circuit diagram showing another example of the first power supply circuit.​​

[0032] Figure 11 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0033] Figure 12 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0034] Figure 13 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0035] Figure 14 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0036] Figure 15 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0037] Figure 16 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0038] Figure 17 FIG. 6 is a circuit diagram showing another example of the first power supply circuit. Figure 7

[0039] Figure 18

[0040] Figure 19 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0041] Figure 20 FIG. 6 is a circuit diagram showing another example of the first power supply circuit.

[0042] Figure 21 FIG. 6 is a circuit diagram showing another example of the first power supply circuit. DETAILED DESCRIPTION

[0043] <First Embodiment>

[0044] (1) Overall Configuration

[0045] Figure 1 FIG. 6 is a circuit diagram showing another example of the first power supply circuit. Figure 1 ​​The power supply device 1 includes a power terminal PT that supplies power from the power source 200, and a first DC bus 11 and a second DC bus 12 to which a DC voltage is applied. The potential of the second DC bus 12 is lower than that of the first DC bus. Additionally, the power supply device 1 includes a capacitor 4 connected between the first DC bus 11 and the second DC bus 12. The power supply device 1 converts the power supplied to the first DC bus 11 and the second DC bus 12 to supply power to the load 100.

[0046] In order to apply DC voltage to the first DC bus 11 and the second DC bus 12, for example, Figure 1 Like the power supply device 1, the power supply 200 uses AC power, and a rectifier 2 is inserted in the wiring path from the power supply terminal PT to the first DC bus 11 and the second DC bus 12 to rectify the AC voltage of the power supply 200 into DC voltage. However, the power supply 200 is not limited to AC power. For example, the power supply 200 can also be a DC power supply. In the case that the power supply 200 is a DC power supply, the rectifier 2 is omitted, for example.

[0047] The power supply device 1 includes an inductor 3, which is inserted into the wiring path from the power supply terminal PT to the first DC bus 11 and the second DC bus 12. The inductor 3 included in the power supply device 1 can be a single unit or multiple units. Figure 1 In the power supply device 1 shown, inductors 3 are connected in series to the first DC bus 11. Figures 2 to 5 An example is shown where inductor 3 is inserted into a wiring path from power supply terminal PT to the first DC bus 11 and the second DC bus 12. For example, in Figure 2 The diagram shows an example where rectifier 2 is a bridge rectifier circuit that rectifies single-phase AC, and inductor 3 is connected in series to the first DC bus 11. Figure 2 The inductor 3 shown is inserted at the output side of the DC voltage of a bridge rectifier circuit that rectifies single-phase AC. For example, in Figure 3 The diagram shows an example where rectifier 2 is a bridge rectifier circuit that rectifies three-phase AC, and inductors 3 are connected in series to the first DC bus 11. Figure 3 The inductor 3 shown is inserted at the output side of the DC voltage of the bridge rectifier circuit that rectifies three-phase AC. Figure 2 as well as Figure 3 The diagram shows an example of inductor 3 inserted into a wiring path from rectifier 2, which is closer to the first DC bus 11 than the power supply terminal PT, to the first DC bus 11. Furthermore, in Figure 2 as well as Figure 3In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage.

[0048] For example, in Figure 4 In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage. Figure 4 The insertion position of the inductor 3 shown in FIG. 1 is the input side of the AC voltage of the bridge rectifier circuit that rectifies single-phase AC. For example, in Figure 4 In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage. Figure 4 The insertion position of the inductor 3 shown in FIG. 1 is the input side of the AC voltage of the bridge rectifier circuit that rectifies single-phase AC. For example, in Figure 4 In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage. Figure 5 In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage. Figure 4 In the example shown in FIG. 1, the inductor 3 is inserted into the first DC bus 11, but the inductor 3 can also be inserted into the second DC bus 12 on the output side of the DC voltage of the bridge rectifier circuit. Further, the inductor 3 can also be inserted into both the input side of the AC voltage of the bridge rectifier circuit and the output side of the DC voltage.

[0049] Figure 1 The power supply device 1 shown in FIG. 1 further includes an inverter circuit 6, an overvoltage protection circuit 5, and a drive circuit 9 as circuit devices. The inverter circuit 6 as a circuit device is connected between the first DC bus 11 and the second DC bus 12. Here, as a circuit device, the inverter circuit 6 is cited as an example, but the circuit device is not limited to the inverter circuit 6, and can be a circuit device other than the inverter circuit 6 as long as it is a circuit device to which the line voltage applied between the first DC bus 11 and the second DC bus 12 is supplied.

[0050] The overvoltage protection circuit 5 is connected between the first DC bus 11 and the second DC bus 12. The overvoltage protection circuit 5 includes a semiconductor switch 52. The overvoltage protection circuit 5 performs protection circuit operation when the semiconductor switch 52 is turned on (in Figure 1The overvoltage protection circuit 5 turns off the semiconductor switch 52 without flowing a current below a prescribed voltage at which the overvoltage protection is not performed. Here, the overvoltage refers to a voltage at which the circuit device cannot normally operate or the circuit device is damaged. Therefore, the prescribed voltage becomes a voltage that is smaller than the overvoltage and larger than the line-to-line voltage between the first DC bus 11 and the second DC bus 12 at the steady state. In addition, the object to be protected from the overvoltage can be the capacitor 4 or the rectifier 2.

[0051] The drive circuit 9 is supplied with the drive power by supplying the power to the power terminal PT. The drive circuit 9 is configured to be able to turn on the semiconductor switch 52 in a drivable state in a first period from when the DC voltage starts to rise accompanying the start of the power supply to the power terminal PT, to when the resonance generated in the closed circuit CL is 1 / 2 cycle. The closed circuit CL is a closed circuit including the power supply 200, the capacitor 4, and the inductor 3. In Figure 1 The closed circuit CL is indicated by a double-dotted line in the drawing.

[0052] When the power supply to the power terminal PT is started, the line-to-line voltage Vb between the first DC bus 11 and the second DC bus 12 starts to rise from zero or a very small voltage in the power supply device 1. Figure 1 In the power supply device 1, the rectifier 2 starts to apply the DC voltage to the first DC bus 11 and the second DC bus 12. In a case where the amount of charge accumulated in the capacitor 4 becomes small due to the temporary stop of the power supply to the power terminal PT, when the power supply to the power terminal PT is started, the line-to-line voltage Vb between the first DC bus 11 and the second DC bus 12 starts to rise from zero or a very small voltage. In this way, when the DC voltage applied to the first DC bus 11 and the second DC bus 12 changes, the series resonance caused by the capacitance component of the capacitor 4 and the inductance component of the inductor 3 is generated in the closed circuit CL. In addition to the capacitor 4 and the inductor 3, there are the capacitance component, the inductance component, and the resistance component in the closed circuit CL, but the series resonance is generated because the capacitor 4 and the inductor 3 are arranged in series in the closed circuit CL.

[0053] The drive circuit 9 is supplied with the power from the first DC bus 11 and the second DC bus 12. Therefore, in a case where the DC voltage between the first DC bus 11 and the second DC bus 12 is zero or very small and close to zero, the drive circuit 9 cannot turn on the semiconductor switch 52. Such a state can be said to be an undrivable state.

[0054] The series resonance generated in the closed circuit CL as the power supply to the power terminal PT is started rises from the DC voltage and reaches a peak at the 1 / 2 period of the resonance period. Therefore, if the drive circuit 9 becomes the drivable state during a first period from the rise of the DC voltage to the 1 / 2 period of the resonance generated in the closed circuit CL, the semiconductor switch 52 can be turned on before the voltage superimposed due to the series resonance reaches the peak. As a result, the semiconductor switch 52 of the overvoltage protection circuit 5 can be turned on before the inverter circuit 6 as the circuit device reaches an overvoltage due to the resonance at the time of the rise of the DC voltage, thereby suppressing the application of the overvoltage to the inverter circuit 6. The power supply device 1 thus configured can improve the reliability of the overvoltage protection of the overvoltage protection circuit 5.

[0055] Further, in the case where the power supply 200 is an alternating current power supply, depending on the line voltage phase at the time of the start of the power supply and the power supply frequency, there is a condition in which an overvoltage is easily generated. The condition with respect to the phase is the vicinity of the phase in which the voltage after the rectification of the alternating current power supply voltage becomes the maximum, and in a single-phase alternating current power supply, becomes the vicinity of 90° or 270°. Further, the lower the power supply frequency is compared to the resonance frequency, the more easily an overvoltage is generated in the vicinity of these phases. Further, in a three-phase alternating current power supply, the phase voltage phase easily becomes an overvoltage in the vicinity of 30°, 90°, 150°, 210°, 270°, and 330°.

[0056] (2) Action of the drive circuit 9

[0057] The line voltage Vb between the first DC bus 11 and the second DC bus 12 is compared with a first threshold voltage Vt1 higher than the line voltage Vb at the time of stability, and the drive circuit 9 turns on the semiconductor switch 52 when the line voltage Vb exceeds the first threshold voltage Vt1. Here, the time of stability means the time at which the vibration of the DC voltage due to the resonance generated in the closed circuit CL converges.

[0058] (3) Example of the circuit device

[0059] The circuit device is the inverter circuit 6 connected between the first DC bus 11 and the second DC bus 12 and including the semiconductor element Q.

[0060] (4) Capacitor 4

[0061] The capacitor 4 does not have a capacity that smoothens the voltage fluctuation generated at the first DC bus 11 and the second DC bus 12 due to the rectifier 2, but has a capacity that suppresses the voltage fluctuation generated by the switching of the inverter circuit 6. In other words, the capacitor 4 is not a smoothing capacitor as in a general electrolytic capacitor, but is provided to remove the high frequency component generated in the inverter circuit 6. Therefore, the capacitor 4 has a small capacity. For example, in a case where the alternating current rectified by the rectifier 2 is single phase, the upper limit of the capacity of the capacitor 4 is a capacity in which the maximum value of the voltage across the capacitor 4 is twice or more the minimum value. Also, in a case where the alternating current rectified by the rectifier 2 is three phase, in a case where the power source voltage of the power source 200 rectified by the rectifier 2 is Vac, and the maximum power of the alternating current power output from the inverter circuit 6 is Pmax, the upper limit of the capacity C of the capacitor 4 is given by C < 350 x 10 -6 x (Pmax / Vac 2 ).

[0062] However, if the capacity of the capacitor 4 is very small, a very large voltage ripple is generated in the capacitor 4 due to the switching of the inverter circuit 6. Therefore, a capacity for suppressing the voltage ripple to a certain degree is required. As a reference, a capacity of 10 or less of the ripple of the capacitor voltage generated by the switching operation of the inverter circuit 6 with respect to the average voltage of the capacitor is required.

[0063] (5) Method of determining the time until the drive circuit 9 becomes drivable

[0064] The line voltage between the first DC bus 11 and the second DC bus 12 can be actually measured at the time of power on, 1 / 2 of the resonance period of the generated resonance phenomenon can be determined, and a time shorter than 1 / 2 of the determined resonance period can be determined as the time until the drive circuit 9 becomes drivable.

[0065] Also, a parasitic inductance component is generally present between the power terminal PT and the power source 200. The resonance period in the case where such a parasitic inductance component is present is longer than the resonance period of the closed circuit having only the inductor 3 and the capacitor 4. Therefore, the resonance period can be calculated from the inductance value of the inductor 3 and the capacity value of the capacitor 4, and the time until the drive circuit 9 becomes drivable can be determined so as to be 1 / 2 or less of the calculated resonance period. If thus determined, the drive circuit 9 is made drivable in a time shorter than the time determined by actual measurement as described above, but this is in the direction of improving safety, so there is no problem.

[0066] For example, the resonance period T in a case where the power source 200 supplies single phase alternating current to the power terminal PT is given by the formula T = 2π(LC) 1 / 2 .

[0067] For example, when power supply 200 supplies three-phase AC to power terminal PT, such as Figure 5 As shown, the inductances of the inductors 3 on each phase of the AC side of the rectifier 2 are set to L1, L2, and L3. The circuit that charges the capacitor 4 when the power is on becomes a closed circuit with the two phases having the largest line-to-line voltage between the first DC bus 11 and the second DC bus 12 as the current path. With the inductances of the inductors 3 in these two phases being L1 and L2, and the capacitance of the capacitor 4 being C, the period T of the resonance generated by the inductors 3 and capacitor 4 is T = 2π((L1 + L2)·C). 1 / 2 Provided.

[0068] <Second Implementation>

[0069] (6) Overall structure

[0070] Figure 6 An example of the structure of the power supply device 1 according to the second embodiment is shown. Figure 6 The power supply device 1 includes a power supply terminal PT that supplies power from the power source 200, a first DC bus 11 and a second DC bus 12 to which DC voltage is applied, an inductor 3, a capacitor 4, an inverter circuit 6 as a circuit device, an overvoltage protection circuit 5, and a drive circuit 9. Figure 6 These structures of the second embodiment shown are similar to Figure 1 The structure of the first embodiment shown is the same, so the description is omitted here.

[0071] The power supply device 1 of the second embodiment includes a first power supply circuit 301 and a second power supply circuit 302. The first power supply circuit 301 and the second power supply circuit 302 are circuits that operate by receiving DC power from the first DC bus 11 and the second DC bus 12. The first power supply circuit 301 supplies power to the drive circuit 9 for a predetermined period, including a first period, along with power supply to the power terminal PT. The second power supply circuit 302 supplies power to the drive circuit 9 for a second period after the predetermined period. In other words, the power supply device 1 switches between supplying power to the drive circuit 9 from the first power supply circuit 301 until the predetermined period has elapsed, and then supplying power to the drive circuit 9 from the second power supply circuit 302 after the predetermined period.

[0072] The first power supply circuit 301 is configured to cause the first output voltage output to the drive circuit 9 to reach a voltage satisfying the drivable state during the first period. The second power supply circuit 302 outputs a second output voltage to the drive circuit 9. The first power supply circuit 301 stops after the second output voltage of the second power supply circuit 302 reaches a voltage satisfying the drivable state. The power capacity of the first power supply circuit 301 is smaller than the power capacity of the second power supply circuit 302. The first power supply circuit 301 is a dedicated power supply circuit that supplies power to the minimum necessary circuit including the drive circuit 9 for turning on and off the semiconductor switch 52. In contrast, the second power supply circuit 302 is a multipurpose power supply circuit that supplies power to the drive circuit 9 and also supplies power to circuits other than the circuit necessary for turning on and off the semiconductor switch 52. The first power supply circuit 301 is a dedicated power supply circuit that supplies power to the above-described minimum necessary circuit, and thus it is easy to cause the first output voltage to rise at high speed.

[0073] The first power supply circuit 301 can not be provided as in the second embodiment, but can be configured by one power supply circuit having the functions of the first power supply circuit 301 and the second power supply circuit 302. However, in this case, the one power supply circuit is configured to cause the first output voltage output to the drive circuit 9 to reach a voltage satisfying the drivable state during the first period, and is configured to supply power to circuits other than the drive circuit 9 also after the prescribed period. Thus, the one power supply circuit has to be a large-scale and high-performance circuit with large power consumption.

[0074] (7) Detailed Configuration

[0075] (7-1) Switching of the First Power Supply Circuit 301 and the Second Power Supply Circuit 302

[0076] Figure 6 The power supply device 1 includes a power supply switching section 303 for switching the first power supply circuit 301 and the second power supply circuit 302. The power supply switching section 303 outputs a stop signal for stopping the first power supply circuit 301 after the second output voltage of the second power supply circuit 302 reaches a voltage satisfying the drivable state. The first power supply circuit 301 stops the output of the first output voltage when the stop signal is received from the power supply switching section 303.

[0077] In order for the power supply switching section 303 to determine the timing of stopping the first power supply circuit 301, Figure 6The power supply device 1 includes a power supply circuit voltage comparator 304. The second output voltage of the second power supply circuit 302 is supplied to the power supply switching section 303 and the power supply circuit voltage comparator 304. Since the second output voltage reaches a voltage satisfying a drivable state, the power supply switching section 303 is able to operate with the second output voltage of the second power supply circuit 302. The power supply circuit voltage comparator 304 compares the switching threshold value and the second output voltage. If the second output voltage becomes equal to or higher than the switching threshold value, the second output voltage becomes a voltage satisfying a drivable state. When the second output voltage becomes equal to or higher than the switching threshold value, the power supply circuit voltage comparator 304 outputs a signal for stopping the output of the first output voltage of the first power supply circuit 301.

[0078] The power supply device 1 includes a comparator power supply circuit 305 that supplies power to the power supply circuit voltage comparator 304 and the DC section voltage comparator 306. The comparator power supply circuit 305 receives the supply of power from the first power supply circuit 301 and the second power supply circuit 302. The comparator power supply circuit 305 first operates with the first output voltage of the first power supply circuit 301, and then operates with the second output voltage of the second power supply circuit 302, to supply power to the power supply circuit voltage comparator 304. Therefore, the power supply circuit voltage comparator 304 is able to operate more quickly compared to a case in which the power supply circuit voltage comparator 304 operates with only the second output voltage of the second power supply circuit 302 without using the first output voltage of the first power supply circuit 301.

[0079] (7-2) Switching of turning on and off of the drive circuit 9

[0080] Figure 6 The power supply device 1 illustrated in FIG. 1 includes a voltage detection circuit 8. The voltage detection circuit 8 is connected between the first DC bus 11 and the second DC bus 12. The voltage detection circuit 8 has resistors 81, 82 connected in series between the first DC bus 11 and the second DC bus 12. The resistors 81, 82 divide the line voltage between the first DC bus 11 and the second DC bus 12. The voltage across the resistor 81 after the line voltage is divided is output to the DC section voltage comparator 306. The DC section voltage comparator 306 compares with a first threshold voltage Vtl that is higher than the line voltage at the time of stabilization. When the line voltage is higher than the first threshold voltage Vtl, the DC section voltage comparator 306 outputs a signal for turning on the semiconductor switch 52 to the drive circuit 9. When the line voltage is equal to or lower than the first threshold voltage Vtl, the DC section voltage comparator 306 outputs a signal for turning off the semiconductor switch 52 to the drive circuit 9.

[0081] (7-3) Overvoltage protection circuit 5

[0082] The overvoltage protection circuit 5 has a resistor 51 and a semiconductor switch 52 connected in series with each other. One end of the resistor 51 is connected to the first DC bus 11, and the other end of the resistor 51 is connected to one end of the semiconductor switch 52. The other end of the semiconductor switch 52 is connected to the second DC bus 12. The semiconductor switch 52 is a semiconductor switch that can be freely turned on and off, and is, for example, a transistor. As the transistor that can be applied to the semiconductor switch 52, there are, for example, a bipolar transistor (BJT), an insulated gate bipolar transistor (IGBT), and a field effect transistor (FET). In the case where the semiconductor switch 52 is an N-channel IGBT, the emitter is connected to the second DC bus 12, and the collector is connected to the other end of the resistor 51. A voltage signal that switches on and off the overvoltage protection circuit 5 is output from the drive circuit 9 to the gate of the insulated gate bipolar transistor. In the overvoltage protection circuit 5, since the resistor 51 mainly consumes power, a semiconductor element with a small power capacity can be used compared to an overvoltage protection circuit using a Zener diode.

[0083] <Third Embodiment>

[0084] (8) Overall Configuration

[0085] Figure 7 An example of the configuration of the power supply device 1 of the third embodiment is shown in FIG. 8. Figure 7 The power supply device 1 of the third embodiment has a power supply terminal PT that supplies power from the power source 200, a first DC bus 11 and a second DC bus 12 to which a DC voltage is applied, an inductor 3, a capacitor 4, an inverter circuit 6 as a circuit device, an overvoltage protection circuit 5, and a drive circuit 9. Figure 6 These configurations of the third embodiment shown in FIG. 8 are the same as those of the first embodiment shown in FIG. 1. Figure 1

[0086] Figure 7 The power supply device 1 of the third embodiment shown in FIG. 8 has a voltage detection circuit 8, a first power supply circuit 301, a second power supply circuit 302, a power supply switching section 303, a power supply circuit voltage comparator 304, a comparator power supply circuit 305, and a DC section voltage comparator 306. Figure 7 These configurations of the third embodiment shown in FIG. 8 are the same as those of the second embodiment shown in FIG. 4. Figure 6

[0087] (8-1) Supplying DC power to the first DC bus 11 and the second DC bus 12

[0088] A DC voltage is applied from the rectifier 2 to the first DC bus 11 and the second DC bus 12 shown in FIG. 8. Figure 7 The rectifier 2 shown in FIG. 8 is supplied with power from the power source 200 in three-phase AC. Figure 7 The rectifier 2 shown in FIG. 8 is supplied with power from the power source 200 in three-phase AC.​​Figure 7 The rectifier 2 is a rectifier circuit that rectifies three-phase alternating current. The rectifier circuit that constitutes the rectifier 2 is a three-phase bridge rectifier circuit constituted by six diodes Dl. Here, as the rectifier 2, a three-phase bridge rectifier circuit is exemplified, but the rectifier 2 is not limited to the three-phase bridge rectifier circuit. The rectifier 2 can also use, for example, a single-phase bridge rectifier circuit.

[0089] In Figure 7 An inductor 3 is inserted in series in the first DC bus 11. The inductor 3 is provided to reduce high-order harmonics generated in a DC link constituted by the first DC bus 11 and the second DC bus 12. Further, as to the position where the inductor 3 is inserted, as well as in the first embodiment, it can also be provided at the second DC bus 12, or between the power supply 200 and the rectifier 2.

[0090] In Figure 7 In the first DC bus 11 of the power supply device 1 of Figure 7 In the second DC bus 12 of the power supply device 1 of

[0091] (8-2) Inverter circuit 6

[0092] Figure 7 The inverter circuit 6 shown in FIG. 1 is a circuit that converts the direct current power supplied to the first DC bus 11 and the second DC bus 12 into three-phase alternating current power and supplies the three-phase alternating current power. Figure 7 The load 100 shown in FIG. 1 is an inductive load. In Figure 7 In the load 100 shown in FIG. 1, as an example of the inductive load, a three-phase alternating current motor is shown. Figure 7 The inverter circuit 6 shown in FIG. 1 is a circuit that converts the direct current power supplied to the first DC bus 11 and the second DC bus 12 into three-phase alternating current power and supplies the three-phase alternating current power.

[0093] The upper arm UA includes three semiconductor switches. The upper arm UA includes, for example, three transistors as the semiconductor switches. The transistor is, for example,Figure 7 These are N-channel insulated-gate bipolar transistors (IGBTs), Qup, Qvp, and Qwp. Hereinafter, the IGBT is sometimes abbreviated as IGBT. The collectors of each IGBT Qup, Qvp, and Qwp are connected to the first DC bus 11, the emitters are connected to the load 100, and the gates are connected to the gate driver 21. Freewheeling diodes Dup, Dvp, and Dwp are connected in reverse parallel with IGBTs Qup, Qvp, and Qwp, respectively. In other words, the cathodes of each freewheeling diode Dup, Dvp, and Dwp are connected to the collectors of each IGBT Qup, Qvp, and Qwp, and the anodes of each freewheeling diode Dup, Dvp, and Dwp are connected to the emitters of each IGBT Qup, Qvp, and Qwp.

[0094] The lower arm DA has three semiconductor switches. For example, the lower arm DA may have three transistors as semiconductor switches. Figure 2 As shown, the transistors are N-channel insulated-gate bipolar transistors (IGBTs) Qun, Qvn, and Qwn. The emitters of each IGBT Qun, Qvn, and Qwn are connected to the second DC bus 12, the collectors are connected to the load 100, and the gates are connected to the gate driver 21. Freewheeling diodes Dun, Dvn, and Dwn are connected in reverse parallel with IGBT Qun, Qvn, and Qwn, respectively. In other words, the cathodes of each freewheeling diode are connected to the collectors of each IGBT Qun, Qvn, and Qwn, and the anodes of each freewheeling diode are connected to the emitters of each IGBT Qun, Qvn, and Qwn. The output from the emitter of IGBT Qup and the collector of IGBT Qun is provided to the U phase of the load 100. The output from the emitter of IGBT Qvp and the collector of IGBT Qvn is provided to the V phase of the load. The output from the emitter of IGBT Qwp and the collector of IGBT Qwn is provided to the W phase of the load 100.

[0095] (8-3) Voltage detection circuit 8

[0096] Voltage detection circuit 8 is used to detect the voltage generated between the first DC bus 11 and the second DC bus 12. Voltage detection circuit 8 detects the line-to-line voltage generated between the first DC bus 11 and the second DC bus 12 between capacitor 4 and inverter circuit 6. Voltage detection circuit 8 includes resistors 81 and 82 connected in series between the first DC bus 11 and the second DC bus 12. Voltage detection circuit 8 outputs the voltage across resistor 81 to DC voltage comparator 306. DC voltage comparator 306 compares this voltage with a first threshold voltage Vt1.

[0097] (8-4) Basic structure of overvoltage protection circuit 5

[0098] Figure 7 The overvoltage protection circuit 5 shown is basically a circuit including a semiconductor switch 52 and a resistor 51 connected in series between the first DC bus 11 and the second DC bus 12. In the overvoltage protection circuit 5, the resistor 51 and the semiconductor switch 52 are connected in series between the first DC bus 11 and the second DC bus 12. Figure 2 In the overvoltage protection circuit 5, one end of the resistor 51 is connected to the first DC bus 11. The other end of the resistor 51 is connected to one end of the semiconductor switch 52. The other end of the semiconductor switch 52 is connected to the second DC bus 12. In the overvoltage protection circuit 5, the resistor 51 is connected to the first DC bus 11, and the semiconductor switch 52 is connected to the second DC bus 12, but the positions of the resistor 51 and the semiconductor switch 52 can be exchanged. Figure 7 In the overvoltage protection circuit 5, one end of the resistor 51 is connected to the first DC bus 11. The other end of the resistor 51 is connected to one end of the semiconductor switch 52. The other end of the semiconductor switch 52 is connected to the second DC bus 12. In the overvoltage protection circuit 5, the resistor 51 is connected to the first DC bus 11, and the semiconductor switch 52 is connected to the second DC bus 12, but the positions of the resistor 51 and the semiconductor switch 52 can be exchanged. Figure 7 In the power supply device 1, the semiconductor switch 52 is an N-channel IGBT. The collector is connected to the other end of the resistor 51, the emitter is connected to the second DC bus 12, and the gate is connected to the drive circuit 9. In the overvoltage protection circuit 5, a current flows in the first current path CP1 when the semiconductor switch 52 is turned on. By causing a current to flow in the first current path CP1, power is consumed by the resistor 51, and the inverter circuit 6 is protected from an overvoltage.

[0099] (8-4-1) Detailed structure of overvoltage protection circuit 5

[0100] Figure 7 The overvoltage protection circuit 5 shown further includes a diode 53 connected in reverse parallel with the resistor 51. The cathode of the diode 53 is connected to the first DC bus 11, and the anode is connected to one end of the semiconductor switch 52. When the semiconductor switch 52 is turned off, a current flowing in the first current path (the resistor 51 and the semiconductor switch 52) is cut off. When there is an inductive component in a circuit including the overvoltage protection circuit 5, an electromotive force occurs that causes a voltage to be generated across the resistor 51. The diode 53 clamps the voltage generated across the resistor 51 to prevent a large voltage from being generated across the resistor 51 due to the semiconductor switch 52 being turned off. In the overvoltage protection circuit 5, the diode 53 is provided, but an overvoltage protection circuit 5 in which such a diode 53 is omitted can also be used in the power supply device 1. Figure 7 In the overvoltage protection circuit 5, the diode 53 is provided, but an overvoltage protection circuit 5 in which such a diode 53 is omitted can also be used in the power supply device 1.

[0101] (8-4-2) Overvoltage protection of overvoltage protection circuit 5

[0102] The line-to-line voltage generated between the first DC bus 11 and the second DC bus 12 is compared with the first threshold voltage Vtl by the DC portion voltage comparator 306. When the line-to-line voltage exceeds the first threshold voltage Vtl, a signal to turn on the semiconductor switch 52 is sent from the DC portion voltage comparator 306 to the drive circuit 9. When the semiconductor switch 52 of the overvoltage protection circuit 5 is turned on, current flows in the first current path CP1 (the resistor 51 and the semiconductor switch 52) to suppress overvoltage, thereby protecting the inverter circuit 6. When the line-to-line voltage becomes lower than the second threshold voltage Vt2 which is lower than the first threshold voltage Vtl, the semiconductor switch 52 is turned off, and the overvoltage protection circuit 5 stops operating.

[0103] (8-4-3) Comparator power supply circuit 305

[0104] Figure 8 An example of the circuit structure of the comparator power supply circuit 305 is shown. The comparator power supply circuit 305 has resistors Rl, R2, R3, and a parallel regulator Ul. When at least one of the first power supply circuit 301 and the second power supply circuit 302 operates, a voltage is applied to one end of the resistor Rl from at least one of the first power supply circuit 301 and the second power supply circuit 302, which will be described later. For example, when the DC voltage is started to be applied to the first DC bus 11 and the second DC bus 12, the first output voltage is first applied from the first power supply circuit 301, and then the second output voltage is applied from the second power supply circuit 302. The cathode of the parallel regulator Ul is connected to the other end of the resistor Rl, and the anode of the parallel regulator Ul is connected to the common line COM. The potential of the common line COM becomes the same potential as the second DC bus 12. The reference terminal of the parallel regulator Ul is supplied with a voltage divided by the resistors R2 and R3 connected in series between the other end of the resistor Rl and the common line COM. A constant voltage is generated across the parallel regulator Ul (between the cathode and the anode). The value of the constant voltage generated across the parallel regulator Ul is determined by the resistors R2 and R3. A voltage for driving is output from the connection point of the other end of the resistor Rl and the cathode of the parallel regulator Ul to the power supply circuit voltage comparator 304 and the DC portion voltage comparator 306. In the comparator power supply circuit, instead of the parallel regulator, a Zener diode, a three-terminal regulator, or the like can be used.

[0105] (8-4-4) Voltage detection circuit 8

[0106] In Figure 8 An example of the circuit structure of the voltage detection circuit 8 is shown in FIG. 8-4-4. Figure 8The voltage detection circuit 8 shown is provided with a capacitor Cl in addition to the resistors 81, 82 already explained. The capacitor Cl is connected between the connection point of the resistors 81, 82 and the second DC bus 12. The capacitor Cl has, for example, a function of removing high-frequency noise generated at the connection point of the resistor 81, the resistor 82.

[0107] (8-4-5) DC portion voltage comparator 306

[0108] Figure 8 An example of the circuit structure of the DC portion voltage comparator 306 is shown. Figure 8 The DC portion voltage comparator 306 shown is a hysteresis comparator using an operational amplifier U2. Also, in this case, an example using the operational amplifier U2 is explained, but the DC portion voltage comparator 306 can be configured using a comparator instead of the operational amplifier U2. The DC portion voltage comparator 306 is provided with the operational amplifier U2, resistors R5, R6, R7, R8, R9, and capacitors C2, C3. One end of the resistor R5 and the resistor R9 is connected to the connection point of the parallel-connected voltage regulator U1 and the resistor R1. In other words, a constant voltage (comparator power supply voltage) is applied from the comparator power supply circuit 305 to one end of the resistors R5, R9. The resistors R5, R6 are connected in series to each other, one end of the resistor R6 is connected to the other end of the resistor R5, and the other end of the resistor R6 is connected to the common line COM. The resistor R7 is connected between the connection point of the resistors R5, R6 and the non-inverting input terminal (+) of the operational amplifier U2. As a result, the voltage obtained by dividing the output voltage of the comparator power supply circuit 305 with the resistors R5, R6 is supplied to the non-inverting input terminal (+).

[0109] Also, the capacitor C2 is connected between the non-inverting input terminal (+) of the operational amplifier U2 and the common line COM. Also, the connection point of the resistors 81, 82 is connected to the inverting input terminal (-) of the operational amplifier U2. The resistor R8 is connected between the output terminal of the operational amplifier U2 and the non-inverting input terminal (+), and the capacitor C3 is connected in parallel to the resistor R8. The other end of the resistor R9 is connected to the output terminal of the operational amplifier U2. In addition, the capacitor C3 is used to adjust the transient waveform of the voltage when the voltage at the non-inverting input terminal (+) of the operational amplifier U2 changes due to the hysteresis action, and is selected as needed.

[0110] When the voltage at the non-inverting input terminal (+) is higher than a predetermined value than the voltage at the connection point of resistors 81 and 82, the DC voltage comparator 306 outputs a high-level signal to the drive circuit 9. Conversely, when the voltage at the non-inverting input terminal (+) is lower than a predetermined value than the voltage at the connection point of resistors 81 and 82, the DC voltage comparator 306 outputs a low-level signal to the drive circuit 9. The voltage higher than the predetermined value of the voltage at the non-inverting input terminal (+) becomes the first threshold voltage Vt1 used to determine whether to connect the semiconductor switch 52 of the overvoltage protection circuit 5. The voltage lower than the predetermined value of the voltage at the non-inverting input terminal (+) becomes the second threshold voltage Vt2 used to determine whether to disconnect the semiconductor switch 52 of the overvoltage protection circuit 5.

[0111] (8-4-6) Power switching unit 303

[0112] exist Figure 9 An example of the circuit structure of the power switching unit 303 is shown. Figure 9 The power switching unit 303 shown includes a resistor R10, an optocoupler Ph1, and a switch SW1. In the power switching unit 303, the resistor R10, the light-emitting diode of the optocoupler Ph1, and the switch SW1 are connected in series between the output terminal of the second power circuit 302 and the common line COM. The signal output from the power circuit voltage comparator 304 is provided to the switch SW1. The output signal of the power circuit voltage comparator 304 is a signal used to cause the power switching unit 303 to output a stop signal.

[0113] When the output signal of the power supply circuit voltage comparator 304 becomes high, the switch SW1 is turned on, and current flows through the resistor R10 and the light-emitting element of the optocoupler Ph1. When the output signal of the power supply circuit voltage comparator 304 becomes low, the switch SW1 is turned off, and current does not flow through the light-emitting element. When current flows through the light-emitting element, the light-receiving element of the optocoupler Ph1 (between the two output terminals) is turned on. Through the conduction of the light-receiving element of the optocoupler Ph1, the first power supply circuit 301 is stopped.

[0114] (8-4-7) First power supply circuit 301

[0115] exist Figure 9 An example of the circuit structure of the first power supply circuit 301 is shown. Figure 9 The first power supply circuit 301 shown includes a constant current circuit 307, a Zener diode Z1 for limiting the operating voltage, a capacitor C4, and a Zener diode Z2 for gate drive power. The constant current circuit 307 is connected to the output terminal of the optocoupler Ph1. When the optocoupler Ph1 is turned on, the constant current circuit 307 does not operate; when the optocoupler Ph1 is not turned on, the constant current circuit 307 operates, outputting a first output voltage from the first power supply circuit 301.

[0116] A constant current circuit 307, a Zener diode Zl, and a Zener diode Z2 are connected in series between the first DC bus 11 and the second DC bus 12. The Zener diode Z2 is connected in parallel to the capacitor C4. The Zener diodes Zl, Z2 are connected in such a manner that the cathode is made higher in potential than the anode. The constant current circuit 307 is a current limiting circuit which limits the current flowing through the Zener diodes Zl, Z2. The constant current circuit 307 and the Zener diodes Zl, Z2 are connected in series with each other. When the constant current circuit 307 is operating, a first output voltage is output from the connection point of the anode of the Zener diode Zl and the cathode of the Zener diode Z2. The cathode of the Zener diode Z2 is connected to the drive circuit 9.

[0117] Here, the breakdown voltage VZ2 of the Zener diode Z2 becomes the first output voltage of the first power supply circuit in the drivable state. In the case where the voltage of the capacitor C4 at the time of power-on is zero, if the current of the constant current circuit is IC1 and the static capacitance of the capacitor C4 is CC4, the time Δtl required until the voltage of the capacitor C4 reaches VZ2 is represented by the relation of Δtl = CC4-VZ2 / IC1. Therefore, by making the static capacitance CC4 the minimum capacitance required for the drive circuit, it is possible to reduce the start-up time of the first output voltage or the current required.

[0118] (8-4-7-1) One configuration example of the constant current circuit 307

[0119] Figure 9 One example of the circuit structure of the constant current circuit 307 is shown in Fig. 8-4-7-1. Figure 9 The constant current circuit 307 shown includes resistors Rll and R12, a parallel regulator U3, a MOS transistor Trl, and a diode D2. One end of the resistor Rll is connected to the first DC bus 11, and the other end of the resistor Rll is connected to the cathode of the parallel regulator U3. The anode of the parallel regulator U3 is connected to the cathode of the Zener diode Zl. The drain of the MOS transistor Trl is connected to the first DC bus 11, and the source of the MOS transistor is connected to one end of the resistor R12. The other end of the resistor R12 is connected to the anode of the parallel regulator U3 (cathode of the Zener diode Zl). The reference terminal of the parallel regulator U3 is connected to the source of the MOS transistor Trl. The gate of the MOS transistor Trl is connected to the anode of the parallel regulator U3. The cathode of the diode D2 is connected to the drain of the MOS transistor Trl, and the anode of the diode D2 is connected to the source of the MOS transistor Trl. The two output terminals of the optocoupler Phl are connected to the anode and cathode of the parallel regulator U3.

[0120] In the state where both output terminals of the opto-coupler Phl are non-conducting, the voltage generated between the anode and the cathode of the parallel regulator U3 is applied between the gate and the source of the MOS transistor Trl, and the MOS transistor Trl becomes a conducting state. A constant current flows between the drain and the source of the MOS transistor Trl which has become a conducting state, and the current flowing between the drain and the source flows into the cathode of the Zener diode Zl through the resistor R12.

[0121] When both output terminals of the opto-coupler Phl become a conducting state, no voltage is generated between the anode and the cathode of the parallel regulator U3, and therefore the MOS transistor Trl becomes a cut-off state. Therefore, the constant current through the MOS transistor Trl is cut off. The cathode of the Zener diode Z2 is connected to the first DC bus 11 through the resistor Rl and the output terminals of the opto-coupler Phl. However, the resistance value of the resistor Rl l is very large compared to the resistance value of the resistor R12, and the current flowing through the resistor Rl l is extremely small. Therefore, the output power of the first power supply circuit 301 supplied from both ends of the Zener diode Z2 also becomes extremely small, and becomes a stop operation state.

[0122] (8-4-7-2) Other configuration example of the first power supply circuit 301

[0123] Figure 10 Another example of the circuit structure of the first power supply circuit 301 is shown. The first power supply circuit 301 shown in Fig. 8-4-7-1 is provided with Figure 10 the resistor 14, the Zener diode Zl, the capacitor C4, and the Zener diode Z2 for the gate drive power supply. The resistor R14, the Zener diode Zl, and the Zener diode Z2 are connected in series between the first DC bus 11 and the second DC bus 12. The Zener diode Z2 is connected in parallel to the capacitor C4. The Zener diodes Zl and Z2 are connected reversely. The resistor 14 is a current limiting element which limits the current flowing through the Zener diodes Zl and Z2. The resistor 14 and the Zener diodes Zl and Z2 are connected in series to each other. The first output voltage is output from the connection point of the anode of the Zener diode Zl and the cathode of the Zener diode Z2. The cathode of the Zener diode Z2 is connected to the drive circuit 9.

[0124] (8-4-7-3) Other configuration example of the first power supply circuit 301

[0125] Figure 11 Another example of the circuit structure of the first power supply circuit 301 is shown. Figure 11 the first power supply circuit 301 shown in Fig. 8-4-7-1 and Figure 9 the first power supply circuit 301 shown in Fig. 8-4-7-1 is provided with the constant current circuit 307, the Zener diode Zl, the capacitor C4, and the Zener diode Z2 for the gate drive power supply. Figure 11 the first power supply circuit 301 shown in Fig. 8-4-7-1 and Figure 9The difference in the first power supply circuit 301 is that a Zener diode Z3 is used instead of the parallel voltage regulator U3. The cathode of the Zener diode Z3 is connected to the other end of resistor R11 and the gate of MOS transistor Tr1. The anode of the Zener diode Z3 is connected to the other end of resistor R12 and the cathode of Zener diode Z1. The constant voltage generated across the Zener diode Z3 causes a constant current to flow through MOS transistor Tr1 and resistor R12. When the two output terminals of the optocoupler Ph1 in the power switching section 303 are in the on state, the constant current circuit 307 stops working; when the output terminals are in the off state, the constant current circuit 307 works, which is consistent with... Figure 9 The first power supply circuit 301 is the same.

[0126] In addition, such as Figure 12 , Figure 13 as well as Figure 14 As shown, the first power supply circuit 301 can also be derived from... Figure 9 , Figure 10 as well as Figure 11 The first power supply circuit 301 shown removes the Zener diode Z1 and connects the portion after the Zener diode Z1 is removed via wiring. However, without the Zener diode Z1, compared to with the Zener diode Z1, current flows to the first power supply circuit 301 from a state with a lower DC voltage, resulting in increased power consumption in the first power supply circuit 301. Regarding the configuration... Figure 12 , Figure 13 as well as Figure 14 The various parts of the first power supply circuit 301 shown are used for... Figure 9 , Figure 10 as well as Figure 11 The parts represented by the same labels in the first power supply circuit 301 shown are the same.

[0127] (8-4-8) Second power supply circuit 302

[0128] exist Figure 9 An example of the circuit structure of the second power supply circuit 302 is shown. Figure 9The second power supply circuit 302 shown includes a diode D3, a resistor R13, an electrolytic capacitor C5, and a switching power supply SM. The diode D3, the resistor R13, and the electrolytic capacitor C5 are connected in series between the first DC bus 11 and the second DC bus 12. The diode D3, the resistor R13, and the electrolytic capacitor C5 constitute a primary side circuit of the switching power supply. The anode of the diode D3 is connected to the first DC bus 11, and the cathode of the diode D3 is connected to one end of the resistor R13. The other end of the resistor R13 is connected to one end of the electrolytic capacitor C5, and the other end of the electrolytic capacitor C5 is connected to the second DC bus 12. A voltage generated across the electrolytic capacitor C5 is supplied to the switching power supply SM, and the switching power supply SM generates a second output voltage between the second DC bus 12 and an output terminal SMo. In addition, as for the diode D3, in a case where a variation in DC voltage does not become a problem for the operation of the switching power supply SM, the diode D3 can be omitted, and the resistor R13 can be directly connected to the first DC bus 11. In addition, the resistor R13 can be a PTC (Positive Temperature Coefficient) thermistor.

[0129] (8-4-8-1) Switching power supply SM

[0130] In Figure 15 one example of a circuit structure of the switching power supply SM is shown. Figure 15 The switching power supply SM shown is a flyback converter. The switching power supply SM includes a transformer T1, a control circuit CC1, a switching section SW2, a diode D5, and an electrolytic capacitor C6. A closed circuit including the electrolytic capacitor C5 and the switching section SW2 is formed on a primary side of the transformer T1. By turning on and off the switching section SW2, a pulse voltage is generated, and an alternating voltage is generated on a secondary side of the transformer.

[0131] In Figure 15 the secondary side of the transformer T1, only a power supply output required for turning on and off the semiconductor switch 52 is shown, but as a power supply for the gate driver 401 and the like for the inverter circuit 6, in addition to a circuit required for overvoltage protection, a plurality of power supply outputs can be provided.

[0132] (8-4-9) Selection of outputs of the first power supply circuit 301 and the second power supply circuit 302

[0133] Figure 9An example of a circuit configuration for selecting the outputs of the first power supply circuit 301 and the second power supply circuit 302 is shown. The circuit for selecting the outputs of the first power supply circuit 301 and the second power supply circuit 302 is composed of a diode D4. The diode D4 has an anode to which the second output voltage of the second power supply circuit 302 is applied and a cathode to which the first output voltage of the first power supply circuit 301 is applied. The drive circuit 9 receives the supply of power from the cathode of the diode D4. In order to select the outputs of the first power supply circuit 301 and the second power supply circuit 302 with such a simple configuration of one diode D4 and supply to the drive circuit 9, the first output voltage of the first power supply circuit 301 and the second output voltage of the second power supply circuit 302 are set in the following manner. When the first power supply circuit 301 is operating, the first output voltage of the first power supply circuit is set to be greater than the second output voltage of the second power supply circuit 302. Therefore, when the first power supply circuit 301 is operating, the diode D4 is reverse-biased, and thus the first output voltage of the first power supply circuit 301 is applied to the drive circuit 9. When the operation of the first power supply circuit 301 is stopped, in other words, when the constant current circuit 307 is stopped, the second output voltage of the second power supply circuit 302 is greater than the first output voltage of the first power supply circuit 301. Therefore, when the operation of the first power supply circuit 301 is stopped, the diode D4 is forward-biased (the second output voltage is greater than the first output voltage), and thus the second output voltage of the second power supply circuit 302 is applied to the drive circuit 9.

[0134] In addition, as for the selection of the power supply circuit, as shown in Figure 16 FIG. 6, it can also be performed by a selection switch SSW that switches between the first power supply circuit 301 and the second power supply circuit 302. When the power supply is not on, the selection switch SSW connects the first power supply circuit 301 to the drive circuit 9. In addition, during the period in which power is supplied from the second power supply circuit 302 to the drive circuit 9, the selection switch SSW connects the second power supply circuit 302 to the drive circuit 9. The power for switching the selection switch SSW can be the second output voltage of the second power supply circuit 302 or another output voltage of the second power supply circuit 302. However, in the case where the configuration is such that switching between the first power supply circuit 301 and the second power supply circuit 302 is performed by the selection switch SSW, the first power supply circuit 301 also operates when the second power supply circuit 302 is connected to the drive circuit 9, and thus the loss is greater than in the case where the first power supply circuit 301 is stopped.

[0135] A closed circuit including a diode D5 and an electrolytic capacitor C6 is formed on the secondary side of the transformer Tl. The alternating voltage generated on the secondary side of the transformer Tl is half-wave rectified by the diode D5, and smoothed by the electrolytic capacitor C6. The voltage across the electrolytic capacitor C6 is the second output voltage of the second power supply circuit 302.

[0136] (8-4-10) Controller 400 and gate driver 401

[0137] Figure 7 The illustrated power supply device 1 includes a controller 400 and a gate driver 401. The gate driver 401 is a circuit that outputs a drive signal to the gates of the IGBTs Qup, Qvp, Qwp, Qun, Qvn, and Qwn. The controller 400 includes the power supply circuit voltage comparator 304, the DC portion voltage comparator 306, and the microcomputer 320 that have been described. The gate driver 401 is controlled by the microcomputer 320. Further, the microcomputer 320 controls the drive circuit 9. The microcomputer 320 is provided with a control arithmetic device and a storage device. The control arithmetic device can use a processor such as a CPU. The control arithmetic device reads out a program stored in the storage device and performs control of the prescribed device / circuit and arithmetic of data in accordance with the program. Further, the control arithmetic device can write an arithmetic result in the storage device or read out information stored in the storage device in accordance with the program.

[0138] (8-4-11) Drive circuit 9

[0139] Figure 17 An example of the circuit structure of the drive circuit 9 is shown. Figure 17 The illustrated drive circuit 9 includes a gate driver integrated circuit U4 and resistors R18 and R19. The VDD terminal of the gate driver integrated circuit U4 is applied with the first output voltage of the first power supply circuit 301 or the second output voltage of the second power supply circuit 302. The GND terminal of the gate driver integrated circuit U4 is connected to the common line COM.

[0140] The output terminal of the gate driver integrated circuit U4 is connected to one end of the resistor R18, and the other end of the resistor R18 is connected to the semiconductor switch 52. Further, the resistor R19 is connected between the other end of the resistor R18 and the common line COM. When the on-off signal of the DC portion voltage comparator 306 is at the low level, the output terminal of the gate driver integrated circuit U4 becomes at the high level, and the semiconductor switch 52 is on. When the on-off signal of the DC portion voltage comparator 306 is at the high level, the output terminal of the gate driver integrated circuit U4 becomes at the low level, and the semiconductor switch 52 is off. Further, when the output terminal of the gate driver integrated circuit U4 is at the high level, the output voltage becomes substantially the same voltage as the VDD terminal. Therefore, the gate voltage when the semiconductor switch 52 is on becomes substantially the same voltage as the VDD terminal.

[0141] (8-4-12) Stop signal output from the power supply switching portion 303

[0142] In Figure 18The stop signal output from the power supply switching section 303, the first output voltage of the first power supply circuit 301, and the second output voltage of the second power supply circuit 302 are shown in FIG. 6. Further, as shown in FIG. 6, the output of the first power supply circuit 301 and the output of the second power supply circuit 302 are connected via the diode D4. Therefore, even if the first power supply circuit 301 stops operating, the first output voltage of the first power supply circuit 301 does not become lower than the first output voltage of the second power supply circuit 302. Figure 9 Further, as shown in FIG. 6, the output of the first power supply circuit 301 and the output of the second power supply circuit 302 are connected via the diode D4. Therefore, even if the first power supply circuit 301 stops operating, the first output voltage of the first power supply circuit 301 does not become lower than the first output voltage of the second power supply circuit 302. Figure 17 Further, as shown in FIG. 6, the output of the first power supply circuit 301 and the output of the second power supply circuit 302 are connected via the diode D4. Therefore, even if the first power supply circuit 301 stops operating, the first output voltage of the first power supply circuit 301 does not become lower than the first output voltage of the second power supply circuit 302.

[0143] In Figure 18 the power supply 200 to the power supply terminal PT is started. Along with the start of the power supply of the power supply 200 to the power supply terminal PT, the first output voltage of the first power supply circuit 301 and the second output voltage of the second power supply circuit 302 start rising. The first output voltage of the first power supply circuit 301 sharply rises, and at time t2, reaches a voltage that enables the drive circuit 9 to become a drivable state that enables the semiconductor switch 52 to be turned on. However, at this time, the second output voltage of the second power supply circuit 302 has not reached a voltage that enables the drive circuit 9 to become a drivable state. When a certain time elapses and becomes time t3, the second output voltage of the second power supply circuit 302 reaches a voltage that enables the drive circuit 9 to become a drivable state. At time t3, the second output voltage sufficiently exceeds a voltage that enables the drive circuit 9 to become a drivable state at time t4, and the power supply switching section 303 outputs a stop signal to the first power supply circuit 301.

[0144] In the third embodiment, the first output voltage of the first power supply circuit 301 or the second output voltage of the second power supply circuit 302 is supplied to the VDD terminal of the gate driver integrated circuit U4, and is output as a voltage of a high level of the gate driver integrated circuit U4. Further, the voltage output from the gate driver integrated circuit U4 is applied to the gate of the semiconductor switch 52. In the case where the semiconductor switch 52 is an N-channel type IGBT, the voltage applied to the gate must be of a size that does not become excessively large due to the collector current flowing through the collector-emitter voltage of the IGBT when the IGBT is turned on. If the gate voltage is insufficient, the collector-emitter voltage becomes large, the loss becomes large, and thus heat destruction of the semiconductor switch is caused. Therefore, in the third embodiment, the voltage that enables the drive circuit 9 to become a drivable state can also be said to be a voltage that enables the semiconductor switch to be turned on without heat destruction.

[0145] <Fourth Embodiment>

[0146] (9) Overall Structure

[0147] Figure 19 An example of the structure of the power supply device 1 of the fourth embodiment is shown. Figure 19The power supply device 1 of the fourth embodiment has a power supply terminal PT that supplies electric power from the power supply 200, a first DC bus 11 and a second DC bus 12 to which a DC voltage is applied, an inductor 3, a capacitor 4, an inverter circuit 6 as a circuit device, an overvoltage protection circuit 5, and a drive circuit 9. In the configuration of the power supply device 1 of the fourth embodiment, the power supply terminal PT that supplies electric power from the power supply 200, the first DC bus 11 and the second DC bus 12 to which a DC voltage is applied, the inductor 3, the capacitor 4, and the inverter circuit 6 are configured similarly to the power supply device 1 of the first embodiment, so the description thereof is omitted here.

[0148] (10) Detailed Configuration

[0149] (10-1) Overvoltage Protection Circuit 5

[0150] Figure 19 The overvoltage protection circuit 5 of the fourth embodiment shown in FIG. 4 has a resistance R20 and an NPN-type bipolar transistor (BJT) Tr2. The overvoltage protection circuit 5 is a series circuit of the resistance R20 and the bipolar transistor Tr2. One end of the resistance R20 is connected to the first DC bus 11, and the other end of the resistance R20 is connected to the collector of the bipolar transistor Tr2. The emitter of the bipolar transistor Tr2 is connected to the second DC bus 12, and the base is connected to the anode of a Zener diode Z4. In the overvoltage protection circuit 5 of the fourth embodiment, the bipolar transistor Tr2 is the semiconductor switch 52. Figure 19

[0151] (10-2) Drive Circuit 9

[0152] Figure 19 The drive circuit 9 of the fourth embodiment shown in FIG. 4 has a resistance R21 and a Zener diode Z4. The drive circuit 9 is a series circuit of the resistance R21 and the Zener diode Z4. One end of the resistance R21 is connected to the first DC bus 11, and the other end of the resistance R21 is connected to the cathode of the Zener diode Z4. The anode of the Zener diode Z4 becomes the output terminal of the overvoltage protection circuit 5. The output terminal of the drive circuit 9 is connected to the base of the bipolar transistor Tr2.

[0153] The Zener voltage of the Zener diode Z4 becomes the threshold voltage that turns on the bipolar transistor Tr2 as the semiconductor switch 52 at the time of overvoltage protection. The resistance R21 of the drive circuit 9 is selected as the current required to flow through the bipolar transistor Tr2 as the semiconductor switch 52 at the time of overvoltage protection.

[0154] As the voltage of the DC portion (the first DC bus 11 and the second DC bus 12) rises, the bipolar transistor Tr2 can be made drivable before the 1 / 2 resonance period of the closed circuit CL, and overvoltage protection can be implemented. In addition, the resistance R21 as the current-limiting element can be replaced with​Figure 9 , Figure 11 The constant current circuit 307 is the same as that shown in FIG. 3. In the constant current circuit 307, the parts denoted by the same reference numerals as those of the constant current circuit 307 shown in FIG. 3 are the same. Also, by providing the drive circuit 9 using the second power supply circuit 302 at the time of stabilization, driving with suppressed power consumption can be performed (refer to FIG. 4). Figure 20 Figure 20 In the drive circuit 9, the parts denoted by the same reference numerals as those of the power supply switching section 303 and the constant current circuit 307 shown in FIG. 3 are the same. A voltage is supplied from the second power supply circuit 302 to the bipolar transistor Tr2 through the diode D6. In addition, the second power supply circuit 302 is connected to one terminal of the resistor R10, and the optocoupler Phl is connected to the other terminal of the resistor R10. In this case, the circuit for supplying a drive current through the current-limiting element (resistor R20) or the constant current circuit 307 and the Zener diode Z4 functions in the same manner as the first power supply circuit 301. Figure 9 Figure 21 (11) Characteristics Figure 21 Figure 9 (11-1)

[0155] In the power supply device 1 of the first to third embodiments, during a first period from the start of the rise of the direct-current voltage applied to the first direct-current bus 11 and the second direct-current bus 12 up to the 1 / 2 period of the resonance generated in the closed circuit CL (refer to FIG. 2), the drive circuit 9 becomes a drivable state in which the semiconductor switch 52 can be turned on. In the power supply device 1, the overvoltage protection circuit 5 is driven by such a drive circuit 9. It is possible to turn on the semiconductor switch 52 of the overvoltage protection circuit 5 before the inverter circuit 6 as a circuit device reaches an overvoltage due to the resonance at the time of the rise of the direct-current voltage applied to the first direct-current bus 11 and the second direct-current bus 12. As a result, it is possible to suppress the application of an overvoltage to the inverter circuit 6, and it is possible to improve the reliability of the overvoltage protection with respect to the power supply device 1.

[0156] (11-2)

[0157] The power supply device 1 of the second or third embodiment is provided with the second power supply circuit 302 that supplies electric power to the drive circuit 9 during a second period after a prescribed period. In the second power supply circuit 302, the second output voltage reaches a voltage that satisfies the drivable state at the time t4 after the second output voltage of the second power supply circuit 302 reaches the voltage that satisfies the drivable state. In the power supply device 1, the first power supply circuit 301 is stopped at the time t4. Figure 1

[0158] (11-2)

[0159] The power supply device 1 of the second or third embodiment is provided with the second power supply circuit 302 that supplies electric power to the drive circuit 9 during a second period after a prescribed period. In the second power supply circuit 302, the second output voltage reaches a voltage that satisfies the drivable state at the time t4 after the second output voltage of the second power supply circuit 302 reaches the voltage that satisfies the drivable state. In the power supply device 1, the first power supply circuit 301 is stopped at the time t4. Figure 18 Figure 18 ​​​​​In this context, the specified period is from time t2 to time t4. After time t4 is the second period, which essentially involves the second power supply circuit 302 supplying power to the drive circuit 9. By stopping the first power supply circuit 301 after the second output voltage of the second power supply circuit 302 reaches a voltage sufficient for a driveable state, the power consumption in the first power supply circuit 301 can be reduced. Specifically, in the case of… Figure 9 In the power supply device 1 with the structure shown, the power consumption of the first power supply circuit 301 can be limited to the necessary minimum.

[0160] (11-3)

[0161] In the power supply device 1 of the second or third embodiment, the power capacity of the first power supply circuit 301 dedicated to the drive circuit 9 is less than the power capacity of the second power supply circuit. By reducing the power capacity of the first power supply circuit 301, the period until the first output voltage of the first power supply circuit 301 reaches the voltage that satisfies the driveable state can be shortened.

[0162] (11-4)

[0163] In the power supply device 1 of the third embodiment, such as Figure 9 As shown, the output of the first power supply circuit 301 and the output of the second power supply circuit 302 are connected via diode D4. Therefore, the length of the period until the first power supply circuit 301 becomes drivable in the first period is not affected by the electrolytic capacitor C6 (see reference) on the output side of the second power supply circuit 302. Figure 15 The power supply device 1 of the third embodiment can prevent the increase in the rise time of the output voltage of the first power supply circuit 301 caused by charging the electrolytic capacitor C6 in addition to the capacitor C4.

[0164] (12) Variation

[0165] (12-1) Variation A

[0166] In the third embodiment described above, such as Figure 10 The example shown illustrates the use of resistor R14 as a current-limiting element. However, current-limiting elements are not limited to resistors. For example, a variable resistor or a PTC (Positive Temperature Coefficient) thermistor can be used as a current-limiting element.

[0167] (12-2) Variation B

[0168] In the third embodiment described above, such as Figure 9 and Figure 11As shown, a case where a constant current circuit 307 is used for the current limiting circuit is described. However, the current limiting circuit is not limited to the constant current circuit. The current limiting circuit has, for example, a current clamping circuit.

[0169] (12-3) Modification C

[0170] In the first to third embodiments described above, the inverter circuit 6 is described as an example of the circuit device. However, the circuit device is not limited to the inverter circuit 6. The circuit device has, for example, a DC-DC converter. In this case, the load becomes a direct current load.

[0171] The embodiments of the present disclosure are described above, but it should be understood that various changes in the form, details, and the like can be made without departing from the spirit and scope of the present disclosure recited in the claims.

[0172] Explanation of Reference Numerals

[0173] 1: power supply device;

[0174] 2: rectifier;

[0175] 3: inductor;

[0176] 4: capacitor;

[0177] 5: overvoltage protection circuit;

[0178] 6: inverter circuit (example of circuit device);

[0179] 9: drive circuit;

[0180] 11: first direct current bus;

[0181] 12: second direct current bus;

[0182] 52: semiconductor switch;

[0183] 301: first power supply circuit;

[0184] 302: second power supply circuit;

[0185] 307: constant current circuit (example of current limiting circuit);

[0186] D4: diode;

[0187] PT: power supply terminal;

[0188] R14: resistor (example of current limiting element);

[0189] Z1, Z2: Zener diode.

[0190] Prior Art Documents

[0191] Patent Literature

[0192] Patent Literature 1: Japanese Patent Application Laid-Open No. 2020-124104

Claims

1. A power supply device (1) comprising: a first DC bus (11) to which a DC voltage is applied and a second DC bus (12) with a potential lower than that of the first DC bus; and a capacitor (4) connected between the first DC bus and the second DC bus, the power supply device converting the power supplied to the first DC bus and the second DC bus to supply power to a load. The power supply device includes: Power supply terminal (PT), which receives power from the power source; An inductor (3) is inserted into the wiring path from the power supply terminal to the first DC bus and the second DC bus; Circuit device (6) is connected between the first DC bus and the second DC bus; An overvoltage protection circuit (5), connected between the first DC bus and the second DC bus, and including a semiconductor switch (52), wherein the overvoltage protection circuit protects the circuit device from overvoltage when the semiconductor switch is turned on; and The driving circuit (9) drives the semiconductor switch. By supplying power to the power supply terminal, driving power is supplied to the driving circuit. During a first period from the start of the rise of the DC voltage accompanying the start of power supply to the power supply terminal to half a cycle of the resonance generated in the closed circuit, the driving circuit becomes an drivable state capable of turning on the semiconductor switch, which includes the power supply, the capacitor, and the inductor.

2. The power supply device (1) according to claim 1, wherein, The line-to-line voltage between the first DC bus and the second DC bus is compared with a threshold voltage that is higher than the stable line-to-line voltage. When the line-to-line voltage exceeds the threshold voltage, the driving circuit turns on the semiconductor switch.

3. The power supply device (1) according to claim 1 or 2, wherein, The circuit device is an inverter circuit (6) connected between the first DC bus and the second DC bus and containing semiconductor elements.

4. The power supply device (1) according to any one of claims 1 to 3, wherein, The power supply device has a first power supply circuit (301) that supplies power to the power supply terminal and to the drive circuit during a predetermined period, including the first period. In the first power supply circuit, during the first period, the first output voltage of the first power supply circuit reaches a voltage that satisfies the driveable state.

5. The power supply device (1) according to claim 4, wherein, The power supply device has a second power supply circuit (302) that supplies power to the drive circuit during a second period after the predetermined period. In the second power supply circuit, after the first period and before the end of the specified period, the second output voltage of the second power supply circuit reaches the voltage that satisfies the driveable state.

6. The power supply device (1) according to claim 5, wherein, The first power supply circuit stops after the second output voltage of the second power supply circuit reaches the voltage that satisfies the driveable state.

7. The power supply device (1) according to claim 5 or 6, wherein, The power capacity of the first power supply circuit is smaller than that of the second power supply circuit.

8. The power supply device (1) according to any one of claims 5 to 7, wherein, The power supply device includes a diode (D4) having an anode to which the second output voltage of the second power supply circuit is applied, and a cathode to which the first output voltage of the first power supply circuit is applied. The drive circuit is configured to receive a power supply from the cathode of the diode.

9. The power supply device (1) according to any one of claims 4 to 8, wherein, The first power supply circuit includes a Zener diode (Z2) and a current-limiting element (R14) or a current-limiting circuit (307). The current-limiting element or the current-limiting circuit limits the current flowing through the Zener diode.

10. The power supply device (1) according to claim 9, wherein, The current limiting circuit is a constant current circuit (307).

11. The power supply device (1) according to any one of claims 1 to 10, wherein, The power source is an AC power source, and a rectifier (2) is inserted in the wiring path from the power source terminal to the first DC bus and the second DC bus. The rectifier (2) rectifies the AC voltage of the AC power source into the DC voltage.

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