Auxiliary circuit, power conversion device, and motor unit

Abstract

This auxiliary circuit has a conversion unit, a drive power source unit, and a resonance unit, and is used in a power conversion device which converts an input voltage applied between a positive electrode line and a negative electrode line into an output voltage. The auxiliary circuit comprises an auxiliary switching unit, an auxiliary drive unit, and an auxiliary power source unit. The conversion unit has a leg including a high-side switching element and a low-side switching element connected in series between the positive electrode line and the negative electrode line, and converts an input voltage into an output voltage by switching on / off the high-side switching element and the low-side switching element. The drive power source unit generates a drive voltage used for on / off control of the high-side switching element and the low-side switching element on the basis of the input voltage. The resonance unit has a resonance inductor, and a resonance capacitor connected to a main connection point which is a connection point between the high-side switching element and the low-side switching element. The auxiliary switching unit has an auxiliary switching element provided between the main connection point and the resonance inductor. If the auxiliary switching element is on, a current flows between the main connection point and the resonance inductor. The auxiliary drive unit has an auxiliary driver for on / off control of the auxiliary switching element. The auxiliary power source unit has an auxiliary power source capacitor for generating an operation voltage of the auxiliary driver. When the auxiliary switching element is off and the high-side switching element is off, if the low-side switching element is turned on, a current flows from the drive power source unit through the auxiliary power source capacitor to the main connection point.

Description

Auxiliary circuits, power conversion devices, motor units

[0001] The technology disclosed herein relates to an auxiliary circuit used in a power conversion device, the power conversion device, and a motor unit.

[0002] Patent Document 1 discloses a resonant inverter device that includes an inverter circuit, a resonant circuit connected to an output terminal of the inverter circuit, and a control circuit that controls the inverter circuit and the resonant circuit.

[0003] The inverter circuit has a main circuit for each phase and a capacitor. In the main circuit for each phase, a main switching element connected to the positive terminal of the power supply and a main switching element connected to the negative terminal of the power supply are connected. A diode is connected in parallel with each of these two main switching elements. The capacitor is connected in parallel with the main switching element in the main circuit for each phase. The resonant circuit has a plurality of auxiliary switching elements and a resonant inductor.

[0004] In this resonant inverter, by switching on and off multiple auxiliary switching devices, the capacitor is appropriately charged and discharged by the resonant current between the inductor and the capacitor. This allows zero-voltage switching to be achieved. It also reduces losses that occur when the main switching devices are turned on or off.

[0005] Patent Document 1 does not disclose or suggest how to generate the operating voltage of an auxiliary driver (not disclosed in Patent Document 1) that controls the on / off of an auxiliary switching element that switches the connection between a resonant inductor and a capacitor.

[0006] For example, in order to generate the operating voltage of the auxiliary driver, it is conceivable to provide a separate power supply (e.g., a floating power supply with an isolation transformer) that independently generates the operating voltage of the auxiliary driver based on the input voltage input to the power conversion device, separate from a drive power supply unit that generates the operating voltage of the drive driver (a driver that controls the on / off of the main switching element) based on the input voltage input to the power conversion device. However, when such an independent separate power supply is provided, it becomes difficult to reduce the size and cost of the circuit.

[0007] Japanese Patent Application Laid-Open No. 2003-18876

[0008] The technology disclosed herein aims to provide an auxiliary circuit that can generate an operating voltage for an auxiliary driver without providing a separate independent power supply such as a floating power supply.

[0009] The technology disclosed herein relates to an auxiliary circuit used in a power conversion device that has a conversion unit, a drive power supply unit, and a resonance unit and converts an input voltage applied between a positive electrode line and a negative electrode line into an output voltage. The auxiliary circuit includes an auxiliary switching unit, an auxiliary drive unit, and an auxiliary power supply unit. The conversion unit has legs including a high-side switching element and a low-side switching element connected in series between the positive electrode line and the negative electrode line, and converts the input voltage into the output voltage by switching the high-side switching element and the low-side switching element on and off. The drive power supply unit generates a drive voltage based on the input voltage that is used to control the on and off of the high-side switching element and the low-side switching element. The resonance unit includes a resonance inductor and a resonance capacitor connected to a main connection point that is a connection point between the high-side switching element and the low-side switching element. The auxiliary switching unit has an auxiliary switching element provided between the main connection point and the resonance inductor, and is configured so that current flows between the main connection point and the resonance inductor when the auxiliary switching element is on. The auxiliary driving unit has an auxiliary driver that controls the on / off of the auxiliary switching element. The auxiliary power supply unit has an auxiliary power supply capacitor for generating an operating voltage for the auxiliary driver, and is configured so that when the auxiliary switching element and the high-side switching element are off and the low-side switching element is turned on, a current flows from the driving power supply unit to the main connection point via the auxiliary power supply capacitor.

[0010] According to the technology disclosed herein, the auxiliary power capacitor can be charged using the drive voltage generated by the drive power supply unit. Therefore, the auxiliary power capacitor can generate the operating voltage for the auxiliary driver. Thus, according to the technology disclosed herein, the operating voltage for the auxiliary driver can be generated without providing a separate, independent power supply such as a floating power supply (a power supply with an isolation transformer).

[0011] FIG. 1 is a block diagram showing the configuration of a motor unit of embodiment 1. FIG. 2 is a circuit diagram showing the configuration of an auxiliary circuit of embodiment 1. FIG. 3 is a waveform diagram for explaining a first operation of the power conversion device (an operation of turning off a low-side switching element and then turning on a high-side switching element). FIG. 4 is a waveform diagram for explaining a second operation of the power conversion device (an operation of turning off a high-side switching element and then turning on a low-side switching element). FIG. 5 is a circuit diagram showing the configuration of a power conversion device of modified example 1 of embodiment 1. FIG. 6 is a circuit diagram showing the configuration of a power conversion device of modified example 2 of embodiment 1. FIG. 7 is a circuit diagram showing the configuration of a power conversion device of modified example 3 of embodiment 1. FIG. 8 is a circuit diagram showing the configuration of a power conversion device of modified example 4 of embodiment 1. FIG. 9 is a circuit diagram showing the configuration of a power conversion device of embodiment 2. FIG. 10 is a circuit diagram showing the configuration of a power conversion device of embodiment 3.

[0012] Hereinafter, the embodiments will be described in detail with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components. Each figure is a schematic diagram and is not necessarily an exact illustration. The same reference numerals are used to designate the same or equivalent parts in the figures, and their descriptions are incorporated herein by reference.

[0013] (Embodiment 1) Fig. 1 is a block diagram showing the configuration of a motor unit 1 according to embodiment 1. The motor unit 1 is connected to a power supply 11 and includes a motor 12 and a power conversion device 10. The power supply 11 is a DC power supply. The power supply 11 is formed by a battery such as a lithium-ion battery or a nickel-metal hydride battery. The motor 12 is a three-phase AC brushless motor.

[0014] The power conversion device 10 is connected to a power supply 11 and a motor 12. The power conversion device 10 converts a power supply voltage supplied from the power supply 11 into a desired output voltage and uses the output voltage to drive the motor 12. The power conversion device 10 includes a conversion unit 20, a drive power supply unit 25, a control power supply unit 26, n drive units 30 (n is an integer of 1 or more), a resonance unit 40, n auxiliary circuits 50, and a control unit 55.

[0015] The input voltage input to the power conversion device 10 is a DC power supply voltage supplied from a power supply 11, which is a DC power supply. The output voltage output from the power conversion device 10 is a three-phase AC voltage. The above n is 3. The positive electrode line L1 is connected to the positive electrode of the power supply 11. The negative electrode line L2 is connected to the negative electrode of the power supply 11. The negative electrode line L2 is grounded.

[0016] A smoothing capacitor C1 is connected between the positive electrode line L1 and the negative electrode line L2. The smoothing capacitor C1 smoothes the power supply voltage (DC power supply voltage) applied between the positive electrode line L1 and the negative electrode line L2. Specifically, the smoothing capacitor C1 reduces ripples in the power supply and absorbs surge voltages. For example, the smoothing capacitor C1 is formed by an electrolytic capacitor.

[0017] [Conversion Unit] The conversion unit 20 has n legs 21. The n legs 21 have the same configuration. Each leg 21 includes a high-side switching element SWH, a low-side switching element SWL, a high-side freewheeling diode DH, and a low-side freewheeling diode DL. The conversion unit 20 converts the input voltage into an output voltage by switching on and off the high-side switching element SWH and the low-side switching element SWL included in the legs 21.

[0018] <Switching Elements> The high-side switching element SWH and the low-side switching element SWL are connected in series between the positive electrode line L1 and the negative electrode line L2. One end (collector or drain) of the high-side switching element SWH is connected to the positive electrode line L1. The other end (emitter or source) of the high-side switching element SWH is connected to one end (collector or drain) of the low-side switching element SWL. The other end (emitter or source) of the low-side switching element SWL is connected to the negative electrode line L2. Hereinafter, the high-side switching element SWH and the low-side switching element SWL will be collectively referred to as "switching element SW."

[0019] The switching element SW is turned on and off in response to a drive signal (voltage) supplied to a control terminal (gate) of the switching element SW. Specifically, when the voltage at the control terminal of the switching element SW exceeds a threshold voltage, the switching element SW switches from off to on. When the voltage at the control terminal of the switching element SW falls below the threshold voltage, the switching element SW switches from on to off. Examples of the switching element SW include field effect transistors (FETs) such as metal oxide semiconductor field effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), and the like.

[0020] <Freewheeling Diode> The high-side freewheeling diode DH is connected in parallel to the high-side switching element SWH. The forward direction of the high-side freewheeling diode DH is from the main connection point P2 to the positive electrode line L1. The low-side freewheeling diode DL is connected in parallel to the low-side switching element SWL. The forward direction of the low-side freewheeling diode DL is from the negative electrode line L2 to the main connection point P2. Hereinafter, the high-side freewheeling diode DH and the low-side freewheeling diode DL will be collectively referred to as the "freewheeling diode DF." The freewheeling diode DF may be a parasitic diode that is parasitic on the switching element SW, or may be a diode element configured separately from the switching element SW.

[0021] <Main Connection Point> In leg 21, the output line L3 is connected to the main connection point P2, which is the connection point between the high-side switching element SWH and the low-side switching element SWL. The "connection point between the high-side switching element SWH and the low-side switching element SWL" refers to a point located on the connection line that electrically connects the high-side switching element SWH and the low-side switching element SWL. The same applies to the following "connection points."

[0022] The conversion unit 20 has three legs 21 corresponding to the three phases of the motor 12. A main connection point P2 in the leg 21 corresponding to the U-phase of the motor 12 is connected to an output line L3 connected to an input terminal of the U-phase of the motor 12. A main connection point P2 in the leg 21 corresponding to the V-phase of the motor 12 is connected to an output line L3 connected to an input terminal of the V-phase of the motor 12. A main connection point P2 in the leg 21 corresponding to the W-phase of the motor 12 is connected to an output line L3 connected to an input terminal of the W-phase of the motor 12.

[0023] [Drive Power Supply Unit] The drive power supply unit 25 generates a drive voltage based on the input voltage. The drive voltage is a voltage used to control the on / off of the high-side switching element SWH and the low-side switching element SWL. The drive voltage (DC voltage) generated by the drive power supply unit 25 is supplied to the drive line L25.

[0024] For example, the drive power supply unit 25 is composed of a regulator, an input smoothing capacitor that smoothes the input voltage of the regulator, an output smoothing capacitor that smoothes the output voltage of the regulator, etc. The regulator may be a series regulator or a switching regulator. For example, the input voltage is 280 V, and the drive voltage is 15 V.

[0025] [Control Power Supply Unit] The control power supply unit 26 generates an operating voltage for the control unit 55 based on the drive voltage generated by the drive power supply unit 25. The configuration of the control power supply unit 26 is similar to the configuration of the drive power supply unit 25. For example, the operating voltage (DC voltage) of the control unit 55 is 3.3 V.

[0026] [Driver Unit] The n driver units 30 correspond to the n legs 21. Each of the n driver units 30 operates based on a drive voltage generated by the drive power supply unit 25 and controls the on / off of the high-side switching element SWH and the low-side switching element SWL included in the leg 21 corresponding to that driver unit 30. Each of the n driver units 30 has a similar configuration. FIG. 2 is a circuit diagram showing the configuration of the auxiliary circuit 50 of the first embodiment. As shown in FIG. 2, the driver unit 30 includes a high-side driver unit 31 and a low-side driver unit 35.

[0027] <High Side Drive Unit> The high side drive unit 31 controls the on / off of the high side switching element SWH. The high side drive unit 31 includes a high side driver 32, a high side power supply unit 33, and a high side output resistor element .

[0028] <<High-Side Driver>> The high-side driver 32 has a positive terminal and a negative terminal. A voltage for turning on the high-side switching element SWH (the operating voltage of the high-side driver 32) is applied to the positive terminal of the high-side driver 32. A voltage for turning off the high-side switching element SWH (a voltage serving as a reference potential) is applied to the negative terminal of the high-side driver 32.

[0029] The high-side driver 32 supplies the voltage of the positive terminal or the voltage of the negative terminal to the control terminal of the high-side switching element SWH by connecting one of the positive terminal and the negative terminal to the control terminal of the high-side switching element SWH in response to control by the control unit 55. This operation switches the signal level (voltage) of the drive signal supplied from the high-side driver 32 to the control terminal of the high-side switching element SWH, thereby switching the high-side switching element SWH on and off.

[0030] One end of a high-side power supply capacitor C33 (described later) is connected to the positive terminal of the high-side driver 32. A voltage generated in the high-side power supply capacitor C33 (the operating voltage of the high-side driver 32) is applied to the positive terminal of the high-side driver 32. A main connection point P2 is connected to the negative terminal of the high-side driver 32, and the voltage at the main connection point P2 is applied to the negative terminal of the high-side driver 32.

[0031] <High-Side Power Supply Unit> The high-side power supply unit 33 has a high-side power supply capacitor C33. The high-side power supply capacitor C33 is a capacitor for generating an operating voltage for the high-side driver 32. The high-side power supply unit 33 is configured so that, when the high-side switching element SWH is off and the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 to the main connection point P2 via the high-side power supply capacitor C33.

[0032] The high-side power supply unit 33 includes a high-side power supply diode D33 and a high-side power supply resistor element R33 in addition to a high-side power supply capacitor C33. The high-side power supply unit 33 forms a bootstrap circuit.

[0033] The high-side power supply capacitor C33 is connected between the drive power supply unit 25 and the main connection point P2. Specifically, one end of the high-side power supply capacitor C33 is connected to the drive line L25 via a high-side power supply diode D33 and a high-side power supply resistor element R33. The other end of the high-side power supply capacitor C33 is connected to the main connection point P2.

[0034] The high-side power supply diode D33 is connected between the drive power supply unit 25 and the high-side power supply capacitor C33. The forward direction of the high-side power supply diode D33 is from the drive power supply unit 25 to the high-side power supply capacitor C33. The high-side power supply resistor R33 is connected in series with the high-side power supply diode D33 between the drive power supply unit 25 and the high-side power supply capacitor C33. Specifically, the anode of the high-side power supply diode D33 is connected to the drive line L25 via the high-side power supply resistor R33. The cathode of the high-side power supply diode D33 is connected to one end of the high-side power supply capacitor C33.

[0035] <High-Side Output Resistor Element> The high-side output resistor element 34 is connected between the output terminal of the high-side driver 32 and the control terminal (gate) of the high-side switching element SWH.

[0036] <Low-Side Drive Unit> The low-side drive unit 35 controls the on / off of the low-side switching element SWL. The low-side drive unit 35 includes a low-side driver 36 and a low-side output resistor element 37.

[0037] <<Low-Side Driver>> The configuration of the low-side driver 36 is similar to the configuration of the high-side driver 32. A voltage for turning on the low-side switching element SWL (the operating voltage of the low-side driver 36) is applied to the positive terminal of the low-side driver 36. A voltage for turning off the low-side switching element SWL (a voltage serving as a reference potential) is applied to the negative terminal of the low-side driver 36.

[0038] The low-side driver 36 supplies the voltage of the positive terminal or the voltage of the negative terminal to the control terminal of the low-side switching element SWL by connecting one of the positive terminal and the negative terminal to the control terminal of the low-side switching element SWL in response to control by the control unit 55. This operation switches the signal level (voltage) of the drive signal supplied from the low-side driver 36 to the control terminal of the low-side switching element SWL, thereby switching the low-side switching element SWL on and off.

[0039] One end of the high-side power supply capacitor C33 is connected to the positive terminal of the low-side driver 36. The voltage generated in the high-side power supply capacitor C33 is applied to the positive terminal of the low-side driver 36. The negative terminal of the low-side driver 36 is connected to the negative line L2. The voltage on the negative line L2 is applied to the negative terminal of the low-side driver 36. In this way, the voltage generated in the high-side power supply capacitor C33 is supplied not only to the positive terminal of the high-side driver 32 but also to the positive terminal of the low-side driver 36. The high-side power supply capacitor C33 is a capacitor for generating the operating voltage of the high-side driver 32 and the operating voltage of the low-side driver 36.

[0040] <Low-Side Output Resistor Element> The low-side output resistor element 37 is connected between the output terminal of the low-side driver 36 and the control terminal (gate) of the low-side switching element SWL.

[0041] [Resonance Unit] The resonance unit 40 includes a resonance inductor 41 , a resonance power supply capacitor 42 , a first resonance diode 43 , a second resonance diode 44 , and n resonance capacitors 45 .

[0042] <Resonant Inductor and Resonant Power Supply Capacitor> Resonant power supply capacitor 42 is connected to resonant inductor 41. Specifically, one end of resonant inductor 41 is connected to n auxiliary circuits 50. The other end of resonant inductor 41 is connected to one end of resonant power supply capacitor 42. The other end of resonant power supply capacitor 42 is connected to negative line L2. Resonant power supply capacitor 42 is connected between resonant inductor 41 and negative line L2.

[0043] <Resonant Diodes> The first resonant diode 43 and the second resonant diode 44 are connected in series between the positive electrode line L1 and the negative electrode line L2. The first resonant diode 43 is connected to the positive electrode line L1. The second resonant diode 44 is connected to the negative electrode line L2. The resonant inductor 41 and n auxiliary circuits 50 are connected to a resonant node P4, which is the node between the first resonant diode 43 and the second resonant diode 44. The forward direction of the first resonant diode 43 is from the resonant node P4 to the positive electrode line L1. The forward direction of the second resonant diode 44 is from the negative electrode line L2 to the resonant node P4.

[0044] <Resonant Capacitor> The n resonant capacitors 45 correspond to the n legs 21. Each of the n resonant capacitors 45 is connected to a main connection point P2 (a connection point between the high-side switching element SWH and the low-side switching element SWL) in the leg 21 corresponding to that resonant capacitor 45. Specifically, one end of the resonant capacitor 45 is connected to the main connection point P2. The other end of the resonant capacitor 45 is connected to the negative line L2. The resonant capacitor 45 is connected in parallel with the low-side switching element SWL between the main connection point P2 and the negative line L2.

[0045] 1, n auxiliary circuits 50 correspond to the n legs 21. Each of the n auxiliary circuits 50 has a similar configuration. As shown in FIG. 2, the auxiliary circuit 50 includes an auxiliary switching unit 60, an auxiliary driving unit 70, and an auxiliary power supply unit 80.

[0046] <Auxiliary Switching Unit> The auxiliary switching unit 60 has an auxiliary switching element 61. The auxiliary switching element 61 is provided between the main connection point P2 and the resonant inductor 41. The auxiliary switching unit 60 is configured so that a current flows between the main connection point P2 and the resonant inductor 41 when the auxiliary switching element 61 is on.

[0047] The auxiliary switching unit 60 has a first auxiliary switching element 61a and a second auxiliary switching element 61b. The first auxiliary switching element 61a and the second auxiliary switching element 61b are provided between the main connection point P2 and the resonant inductor 41. The auxiliary switching unit 60 is configured so that when the first auxiliary switching element 61a is on and the second auxiliary switching element 61b is off, a current flows from the main connection point P2 to the resonant inductor 41, and when the first auxiliary switching element 61a is off and the second auxiliary switching element 61b is on, a current flows from the resonant inductor 41 to the main connection point P2. The first auxiliary switching element 61a corresponds to the auxiliary switching element 61 described above.

[0048] Specifically, the auxiliary switching unit 60 has a first auxiliary switching element 61a and a second auxiliary switching element 61b, as well as a first auxiliary diode 62a, a second auxiliary diode 62b, a third auxiliary diode 62c, and a fourth auxiliary diode 62d.

[0049] The first auxiliary switching element 61 a and the second auxiliary switching element 61 b ​​are connected in parallel between the main connection point P2 and the resonant inductor 41 .

[0050] The first auxiliary diode 62a is connected between the first auxiliary switching element 61a and the resonant inductor 41. The forward direction of the first auxiliary diode 62a is from the first auxiliary switching element 61a to the resonant inductor 41. The second auxiliary diode 62b is connected in parallel with the first auxiliary switching element 61a between the main connection point P2 and the first auxiliary diode 62a. The forward direction of the second auxiliary diode 62b is from the first auxiliary diode 62a to the main connection point P2.

[0051] The third auxiliary diode 62c is connected between the second auxiliary switching element 61b and the resonant inductor 41. The forward direction of the third auxiliary diode 62c is from the resonant inductor 41 to the second auxiliary switching element 61b. The fourth auxiliary diode 62d is connected in parallel with the second auxiliary switching element 61b between the main connection point P2 and the third auxiliary diode 62c. The forward direction of the fourth auxiliary diode 62d is from the main connection point P2 to the third auxiliary diode 62c.

[0052] Specifically, one end (collector or drain) of the first auxiliary switching element 61a is connected to the main connection point P2. The other end (emitter or source) of the first auxiliary switching element 61a is connected to the anode of the first auxiliary diode 62a. The cathode of the first auxiliary diode 62a is connected to the resonant connection point P4. The anode of the second auxiliary diode 62b is connected to the other end of the first auxiliary switching element 61a. The cathode of the second auxiliary diode 62b is connected to one end of the first auxiliary switching element 61a.

[0053] One end (collector or drain) of the second auxiliary switching element 61b is connected to the cathode of the third auxiliary diode 62c. The other end (emitter or source) of the second auxiliary switching element 61b is connected to the main connection point P2. The anode of the third auxiliary diode 62c is connected to the resonant connection point P4. The anode of the fourth auxiliary diode 62d is connected to the other end of the second auxiliary switching element 61b. The cathode of the fourth auxiliary diode 62d is connected to one end of the second auxiliary switching element 61b.

[0054] The configurations of the first auxiliary switching element 61 a and the second auxiliary switching element 61 b ​​are similar to that of the switching element SW. When the voltage at the control terminal of the first auxiliary switching element 61 a exceeds a threshold voltage, the first auxiliary switching element 61 a switches from off to on, and when the voltage at the control terminal of the first auxiliary switching element 61 a falls below the threshold voltage, the first auxiliary switching element 61 a switches from on to off. The operation of the second auxiliary switching element 61 b ​​is similar to that of the first auxiliary switching element 61 a.

[0055] The configurations of the first auxiliary switching element 61 a and the second auxiliary diode 62 b may be similar to the configurations of the switching element SW and the free wheeling diode DF. The configurations of the second auxiliary switching element 61 b ​​and the fourth auxiliary diode 62 d may be similar to the configurations of the switching element SW and the free wheeling diode DF.

[0056] <Auxiliary Driving Unit> The auxiliary driving unit 70 has an auxiliary driver 71. The auxiliary driver 71 controls the on / off of the auxiliary switching element 61. The auxiliary driving unit 70 has a first auxiliary driver 71a, a second auxiliary driver 71b, a first auxiliary output resistor element 72a, and a second auxiliary output resistor element 72b. The first auxiliary driver 71a corresponds to the auxiliary driver 71 described above.

[0057] <<First Auxiliary Driver>> The first auxiliary driver 71a controls the on / off of the first auxiliary switching element 61a. The configuration of the first auxiliary driver 71a is similar to that of the high-side driver 32. A voltage for turning on the first auxiliary switching element 61a (the operating voltage of the first auxiliary driver 71a) is applied to the positive terminal of the first auxiliary driver 71a. A voltage for turning off the first auxiliary driver 71a (a voltage serving as a reference potential) is applied to the negative terminal of the first auxiliary driver 71a.

[0058] The first auxiliary driver 71a supplies the voltage at the positive terminal or the voltage at the negative terminal to the control terminal of the first auxiliary switching element 61a by connecting one of the positive terminal and the negative terminal to the control terminal of the first auxiliary driver 71a in response to control by the control unit 55. This operation switches the signal level (voltage) of the drive signal supplied from the first auxiliary driver 71a to the control terminal of the first auxiliary switching element 61a, thereby switching the first auxiliary switching element 61a on and off.

[0059] The positive terminal of the first auxiliary driver 71a is connected to one end of a first auxiliary power supply capacitor 81a (described later). The voltage generated in the first auxiliary power supply capacitor 81a is applied to the positive terminal of the first auxiliary driver 71a. The negative terminal of the first auxiliary driver 71a is connected to the connection point between the first auxiliary switching element 61a and the first auxiliary diode 62a. The negative terminal of the first auxiliary driver 71a is connected to the voltage at the connection point between the first auxiliary switching element 61a and the first auxiliary diode 62a.

[0060] <<First Auxiliary Output Resistor>> The first auxiliary output resistor 72a is connected between the output terminal of the first auxiliary driver 71a and the control terminal (gate) of the first auxiliary switching element 61a. The first auxiliary output resistor 72a corresponds to the "auxiliary output resistor 72 connected between the output terminal of the auxiliary driver 71 and the control terminal of the auxiliary switching element 61."

[0061] <<Second Auxiliary Driver>> The second auxiliary driver 71b controls the on / off of the second auxiliary switching element 61b.

[0062] The second auxiliary driver 71b controls the on / off of the second auxiliary switching element 61b. The configuration of the second auxiliary driver 71b is similar to that of the high-side driver 32. A voltage for turning on the second auxiliary switching element 61b (the operating voltage of the second auxiliary driver 71b) is applied to the positive terminal of the second auxiliary driver 71b. A voltage for turning off the second auxiliary driver 71b (a voltage serving as a reference potential) is applied to the negative terminal of the second auxiliary driver 71b. In response to control by the control unit 55, the second auxiliary driver 71b connects one of its positive and negative terminals to the control terminal of the second auxiliary driver 71b, thereby supplying one of the voltages at the positive and negative terminals to the control terminal of the second auxiliary switching element 61b. This operation switches the signal level (voltage) of the drive signal supplied from the second auxiliary driver 71b to the second auxiliary switching element 61b, thereby switching on and off the second auxiliary switching element 61b.

[0063] The positive terminal of the second auxiliary driver 71b is connected to one end of a second auxiliary power supply capacitor 81b (described later). The voltage generated in the second auxiliary power supply capacitor 81b is applied to the positive terminal of the second auxiliary driver 71b. The negative terminal of the second auxiliary driver 71b is connected to the main connection point P2 and receives the voltage at the main connection point P2.

[0064] <<Second Auxiliary Output Resistor>> The second auxiliary output resistor 72b is connected between the output terminal of the second auxiliary driver 71b and the control terminal (gate) of the second auxiliary switching element 61b.

[0065] [Auxiliary Power Supply Unit] The auxiliary power supply unit 80 has an auxiliary power supply capacitor 81. The auxiliary power supply capacitor 81 is a capacitor for generating an operating voltage for the auxiliary driver 71. The auxiliary power supply unit 80 is configured so that, when the auxiliary switching element 61 and the high-side switching element SWH are both off and the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 via the auxiliary power supply capacitor 81 toward the main connection point P2.

[0066] The auxiliary power supply unit 80 has a first auxiliary power supply capacitor 81a and a second auxiliary power supply capacitor 81b. The first auxiliary power supply capacitor 81a is a capacitor for generating an operating voltage for the first auxiliary driver 71a. The second auxiliary power supply capacitor 81b is a capacitor for generating an operating voltage for the second auxiliary driver 71b. The first auxiliary power supply capacitor 81a corresponds to the auxiliary power supply capacitor 81 described above.

[0067] The auxiliary power supply unit 80 is configured so that when the first auxiliary switching element 61a and the second auxiliary switching element 61b are off and the high-side switching element SWH is off, and the low-side switching element SWL is turned on, current flows from the drive power supply unit 25 via the first auxiliary power supply capacitor 81a and the second auxiliary power supply capacitor 81b toward the main connection point P2.

[0068] Specifically, the auxiliary power supply 80 includes a first auxiliary power supply capacitor 81a, a second auxiliary power supply capacitor 81b, a first auxiliary power supply diode 82a, a first auxiliary power supply resistor 83a, a second auxiliary power supply diode 82b, and a second auxiliary power supply resistor 83b. The first auxiliary power supply capacitor 81a, the first auxiliary power supply diode 82a, and the first auxiliary power supply resistor 83a form a bootstrap circuit. Similarly, the second auxiliary power supply capacitor 81b, the second auxiliary power supply diode 82b, and the second auxiliary power supply resistor 83b form a bootstrap circuit.

[0069] <<First Auxiliary Power Supply Capacitor>> The first auxiliary power supply capacitor 81a is connected between the connection point between the first auxiliary switching element 61a and the first auxiliary diode 62a and the drive power supply unit 25. Specifically, one end of the first auxiliary power supply capacitor 81a is connected to the drive line L25 via the first auxiliary power supply diode 82a and the first auxiliary power supply resistor element 83a. The other end of the first auxiliary power supply capacitor 81a is connected to the connection point between the first auxiliary switching element 61a and the first auxiliary diode 62a.

[0070] <<First Auxiliary Power Diode and First Auxiliary Power Resistor>> The first auxiliary power diode 82a is connected between the drive power supply unit 25 and the first auxiliary power capacitor 81a. The forward direction of the first auxiliary power diode 82a is from the drive power supply unit 25 to the first auxiliary power capacitor 81a. The first auxiliary power resistor 83a is connected in series with the first auxiliary power diode 82a between the drive power supply unit 25 and the first auxiliary power capacitor 81a. Specifically, the anode of the first auxiliary power diode 82a is connected to the drive line L25 via the first auxiliary power resistor 83a. The cathode of the first auxiliary power diode 82a is connected to one end of the first auxiliary power capacitor 81a.

[0071] <<Second Auxiliary Power Supply Capacitor>> The second auxiliary power supply capacitor 81b is connected between the main connection point P2 and the drive power supply unit 25. Specifically, one end of the second auxiliary power supply capacitor 81b is connected to the drive line L25 via a second auxiliary power supply diode 82b and a second auxiliary power supply resistor element 83b. The other end of the second auxiliary power supply capacitor 81b is connected to the main connection point P2.

[0072] <<Second Auxiliary Power Diode and Second Auxiliary Power Resistor>> The second auxiliary power diode 82b is connected between the drive power supply unit 25 and the second auxiliary power capacitor 81b. The forward direction of the second auxiliary power diode 82b is from the drive power supply unit 25 to the second auxiliary power capacitor 81b. The second auxiliary power resistor 83b is connected in series with the second auxiliary power diode 82b between the drive power supply unit 25 and the second auxiliary power capacitor 81b. Specifically, the anode of the second auxiliary power diode 82b is connected to the drive line L25 via the second auxiliary power resistor 83b. The cathode of the second auxiliary power diode 82b is connected to one end of the second auxiliary power capacitor 81b.

[0073] The first auxiliary power diode 82a corresponds to "an auxiliary power diode 82 connected between the drive power supply unit 25 and the auxiliary power capacitor 81, with the forward direction being from the drive power supply unit 25 to the auxiliary power capacitor 81." The first auxiliary power resistor 83a corresponds to "an auxiliary power resistor 83 connected in series with the auxiliary power diode 82 between the drive power supply unit 25 and the auxiliary power capacitor 81."

[0074] Various Sensors and Storage Unit The power conversion device 10 is provided with various sensors (not shown) and a storage unit (not shown). Examples of the various sensors include a current sensor that detects three-phase current flowing through the motor 12, and a rotation angle sensor that detects the rotation angle of the motor 12. Various pieces of information obtained by the various sensors are transmitted to the control unit 55. The storage unit stores various pieces of information used for control in the power conversion device 10.

[0075] [Control Unit] The control unit 55 is connected to each part of the power conversion device 10 so that signals can be transmitted, and controls each part of the power conversion device 10 to control the operation of the power conversion device 10 based on information obtained by various sensors, information stored in the memory unit, information provided from the outside, etc.

[0076] For example, the control unit 55 includes a processor and a memory that stores various programs for operating the processor. The processor executes the various programs stored in the memory to realize various functions of the control unit 55.

[0077] The control unit 55 controls the n drive units 30 so that the input voltage is converted into a desired output voltage by turning on and off the switching elements SW in the n legs 21. For example, the control unit 55 controls the high-side driver 32 and the low-side driver 36 of the n drive units 30 to control the on and off of the high-side switching elements SWH and low-side switching elements SWL of the n legs 21 so that the rotational speed of the motor 12 becomes the target rotational speed (so that an output voltage for making the rotational speed of the motor 12 become the target rotational speed is supplied to the motor 12).

[0078] The control unit 55 controls the n auxiliary circuits 50 so as to reduce losses (switching losses) that occur when switching the switching elements SW in the n legs 21 on and off. The control unit 55 controls the auxiliary drivers 71 (first auxiliary driver 71 a and second auxiliary driver 71 b) of the n auxiliary circuits 50 to control the on / off of the auxiliary switching elements 61 (first auxiliary switching element 61 a and second auxiliary switching element 61 b) of the auxiliary circuits 50 so as to perform zero-voltage switching in the n legs 21.

[0079] [Charging Operation of Auxiliary Power Supply Capacitors] Next, the charging operation of the auxiliary power supply capacitors 81 (first auxiliary power supply capacitor 81a and second auxiliary power supply capacitor 81b) in the auxiliary circuit 50 will be described with reference to FIG.

[0080] When the auxiliary switching element 61 (first auxiliary switching element 61a and second auxiliary switching element 61b) is off and the high-side switching element SWH is off, if the low-side switching element SWL is turned on, current flows from the drive power supply unit 25 to the auxiliary power supply unit 80 via the drive line L25.

[0081] A portion of the current flowing into the auxiliary power supply 80 passes through the first auxiliary power supply resistor 83a, the first auxiliary power supply diode 82a, and the first auxiliary power supply capacitor 81a in this order in the auxiliary power supply 80, and then passes through the second auxiliary diode 62b in the auxiliary switching unit 60. Thereafter, a portion of the current flowing into the auxiliary power supply 80 passes through the main connection point P2 and the low-side switching element SWL in the on state in this order, and flows into the negative line L2. In this way, a charging path for the first auxiliary power supply capacitor 81a is formed, and the first auxiliary power supply capacitor 81a is charged.

[0082] The remainder of the current that has flowed into auxiliary power supply 80 passes through second auxiliary power supply resistor 83b, second auxiliary power supply diode 82b, and second auxiliary power supply capacitor 81b in this order in auxiliary power supply 80. Thereafter, the remainder of the current that has flowed into auxiliary power supply 80 passes through main connection point P2 and low-side switching element SWL in the on state in this order, and flows into negative line L2. In this way, a charging path for second auxiliary power supply capacitor 81b is formed, and second auxiliary power supply capacitor 81b is charged.

[0083] [Operation of Power Conversion Device] Next, the operation of the power conversion device 10 will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a waveform diagram for explaining a first operation of the power conversion device 10 (an operation of turning on the high-side switching element after turning off the low-side switching element). Fig. 4 is a waveform diagram for explaining a second operation of the power conversion device 10 (an operation of turning on the low-side switching element after turning off the high-side switching element).

[0084] 3 and 4, the drive signal supplied from the high-side driver 32 to the high-side switching element SWH is referred to as a "high-side drive signal SSH," and the drive signal supplied from the low-side driver 36 to the low-side switching element SWL is referred to as a "low-side drive signal SSL." The drive signal supplied from the first auxiliary driver 71a to the first auxiliary switching element 61a is referred to as a "first auxiliary drive signal S61a," and the drive signal supplied from the second auxiliary driver 71b to the second auxiliary switching element 61b is referred to as a "second auxiliary drive signal S61b."

[0085] In Figures 3 and 4, the current flowing through the high-side switching element SWH is referred to as the "high-side switching current iSWH," the current flowing through the low-side switching element SWL is referred to as the "low-side switching current iSWL," and the current flowing through the low-side freewheeling diode DL is referred to as the "low-side diode current iDL."

[0086] 3 and 4, the current flowing through the resonant unit 40 (resonant inductor 41) and leg 21 via the auxiliary circuit 50 is referred to as the "resonant current i50," and the voltage of each phase (e.g., U-phase) of the motor 12, which is the voltage at the main connection point P2, is referred to as the "motor voltage VM." The direction of the resonant current i50 from the resonant inductor 41 toward the main connection point P2 is referred to as the "positive" direction.

[0087] [First Operation of Power Conversion Device] A first operation of the power conversion device 10 (an operation of turning on the high-side switching element after turning off the low-side switching element) will be described with reference to FIG. 3 .

[0088] At time t1, the signal level of the low-side drive signal SSL changes from high to low, and the low-side switching element SWL changes from on to off.

[0089] At time t2, the low-side switching element SWL is turned off, and the low-side diode current iDL (regenerative current) starts to flow.

[0090] At time t3, the signal level of the second auxiliary drive signal S61b changes from low to high, and the second auxiliary switching element 61b changes from off to on.

[0091] At time t4, the second auxiliary switching element 61b turns on, and the resonant current i50 starts to flow from the resonant inductor 41 of the resonant unit 40 toward the main connection point P2 of the leg 21. This causes the low-side diode current iDL to gradually decrease. During the period from time t4 to time t8, the resonant current i50 gradually increases from zero, reaches its maximum value, and then gradually decreases to zero.

[0092] At time t5, the rising resonant current i50 reaches the motor current iM. The motor current iM is the current flowing through each phase (e.g., the U-phase) of the motor 12. This causes the low-side diode current iDL to become zero. Then, the motor voltage VM begins to rise from zero.

[0093] At time t6, the decreasing resonant current i50 reaches the motor current iM. At this time, the motor voltage VM reaches the DC voltage VDC. The DC voltage VDC is the input voltage applied between the positive electrode line L1 and the negative electrode line L2. As a result, the voltage at the main connection point P2 becomes the same as the voltage at the positive electrode line L1, and the potential difference across the high-side switching element SWH becomes zero.

[0094] At time t6, the signal level of the high-side drive signal SSH changes from low to high, and the high-side switching element SWH changes from off to on while the potential difference across the high-side switching element SWH is zero.

[0095] At time t6, the signal level of the second auxiliary drive signal S61b changes from high to low, and the second auxiliary switching element 61b changes from on to off.

[0096] At time t7, the high-side switching element SWH is turned on, and the absolute value of the high-side switching current iSWH becomes the motor current iM. That is, the motor current iM starts to flow through the high-side switching element SWH.

[0097] At time t8, the resonant current i50 becomes zero, and the first operation of the power conversion device 10 (the operation of turning off the low-side switching element and then turning on the high-side switching element) ends.

[0098] In this way, zero-voltage switching of the high-side switching element SWH can be performed in the first operation of the power conversion device 10. This makes it possible to reduce switching loss in the high-side switching element SWH.

[0099] [Second Operation of Power Conversion Device] A second operation of the power conversion device 10 (an operation of turning off the high-side switching device and then turning on the low-side switching device) will be described with reference to FIG. 4 .

[0100] At time t1, the signal level of the high-side drive signal SSH changes from high to low, and the high-side switching element SWH changes from on to off.

[0101] At time t2, high-side switching element SWH turns off, the motor current starts discharging resonance capacitor 45, and motor voltage VM starts to decrease.

[0102] At time t3, the signal level of the first auxiliary drive signal S61a changes from low to high, and the first auxiliary switching element 61a changes from off to on.

[0103] At time t4, the first auxiliary switching element 61a is turned on, and a resonant current i50 starts to flow from the resonant capacitor 45 to the resonant inductor 41 via the main connection point P2 of the leg 21.

[0104] At time t5, motor voltage VM reaches "half of DC voltage VDC." This suppresses the increase in resonant current i50. From time t5 onward, motor voltage VM gradually decreases to zero. When motor voltage VM reaches zero, the voltage at main connection point P2 becomes the same as the voltage at negative line L2, and the potential difference across low-side switching element SWL becomes zero.

[0105] At time t6, the resonant current i50 becomes zero, and the low-side diode current iDL starts to flow.

[0106] At time t7, the signal level of the low-side drive signal SSL changes from low to high, and the low-side switching element SWL changes from off to on while the potential difference across the low-side switching element SWL is zero.

[0107] At time t7, the signal level of the first auxiliary drive signal S61a changes from high to low, and the first auxiliary switching element 61a changes from on to off.

[0108] At time t8, the low-side switching element SWL is turned on, and the absolute value of the low-side switching current iSWL becomes the motor current iM. That is, the motor current iM starts to flow through the low-side switching element SWL.

[0109] The second operation of the power conversion device 10 (the operation of turning on the low-side switching element after turning off the high-side switching element) ends.

[0110] In this way, zero-voltage switching of the low-side switching element SWL can be performed in the second operation of the power conversion device 10. This makes it possible to reduce switching loss in the low-side switching element SWL.

[0111] Effect of First Embodiment As described above, in the motor unit 1 of the first embodiment, the auxiliary power supply unit 80 is configured so that when the auxiliary switching element 61 is off and the high-side switching element SWH is off, and the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 via the auxiliary power supply capacitor 81 to the main connection point P2 (the connection point between the high-side switching element SWH and the low-side switching element SWL).

[0112] With the above configuration, the auxiliary power supply capacitor 81 can be charged using the drive voltage generated by the drive power supply unit 25. This allows the auxiliary power supply capacitor 81 to generate the operating voltage for the auxiliary driver 71. In this way, the operating voltage for the auxiliary driver 71 can be generated without providing a separate independent power supply such as a floating power supply.

[0113] It is not necessary to provide a separate power supply (for example, a power supply having an isolation transformer) that independently generates an operating voltage for the auxiliary driver 71 based on the input voltage input to the power conversion device 10, in addition to the drive power supply unit 25 that generates a drive voltage (operating voltage for the drive unit 30) based on the input voltage input to the power conversion device 10. Therefore, the auxiliary circuit can be made smaller and less expensive than when a separate power supply such as the one described above is provided.

[0114] 5 is a circuit diagram showing the configuration of a power conversion device 10A according to Modification 1 of Embodiment 1. The power conversion device 10A according to Modification 1 of Embodiment 1 differs from the power conversion device 10 of Embodiment 1 in the configuration of the resonant unit 40. The other configurations of the power conversion device 10A according to Modification 1 of Embodiment 1 are similar to the configurations of the power conversion device 10 of Embodiment 1.

[0115] In the first variant of the first embodiment, in addition to the configuration of the resonant section 40 shown in Figures 1 and 2, the resonant section 40 includes a resonant power supply capacitor 42 connected between the positive electrode line L1 and the resonant inductor 41, and n resonant capacitors 45 each connected between the positive electrode line L1 and the main connection point P2 in the n legs 21.

[0116] [Advantages of Modification 1 of First Embodiment] With the motor unit 1 of Modification 1 of the first embodiment, advantages similar to those of the motor unit 1 of the first embodiment can be obtained.

[0117] In the motor unit 1 of the first modification of the first embodiment, the voltage (voltage across both ends) of the resonant power supply capacitor 42 can be quickly set to "half the input voltage" immediately after power is turned on. This makes it possible to stabilize the operation of the power conversion device 10A at startup.

[0118] In the motor unit 1 according to the first modification of the first embodiment, the resonant capacitor 45 can be disposed near the switching element SW, which makes it possible to easily arrange wiring between the switching element SW and the resonant capacitor 45 on the control board (not shown).

[0119] (Second Modification of First Embodiment) Fig. 6 is a circuit diagram showing the configuration of a power conversion device 10B according to a second modification of the first embodiment. The power conversion device 10B according to the second modification of the first embodiment differs from the power conversion device 10 according to the first embodiment in the configuration of the resonant section 40. The power conversion device 10B according to the second modification of the first embodiment includes a resonant voltage sensor 91 and a power supply voltage sensor 92. The resonant voltage sensor 91 detects the voltage (voltage across both ends) of the resonant power supply capacitor 42. The power supply voltage sensor 92 detects the input voltage. The other configuration of the power conversion device 10B according to the second modification of the first embodiment is similar to the configuration of the power conversion device 10 according to the first embodiment.

[0120] [Resonance Unit] In the second modification of the first embodiment, in the resonance unit 40, the resonant power supply capacitor 42 is connected between the positive electrode line L1 and the resonant inductor 41. The n resonance capacitors 45 are connected between the positive electrode line L1 and the main connection points P2 of the n legs 21. The other configuration of the resonance unit 40 of the second modification of the first embodiment is the same as the configuration of the resonance unit 40 of the first embodiment.

[0121] [Effects of Modification 2 of First Embodiment] With the motor unit 1 of Modification 2 of the first embodiment, the same effects as those of the motor unit 1 of the first embodiment can be obtained.

[0122] In the motor unit 1 of the second modification of the first embodiment, the power conversion device 10B can be appropriately started while monitoring the voltage of the resonant power supply capacitor 42 detected by the resonant voltage sensor 91 and the input voltage detected by the power supply voltage sensor 92.

[0123] 7 is a circuit diagram showing the configuration of a power conversion device 10C according to Modification 3 of Embodiment 1. The power conversion device 10C according to Modification 3 of Embodiment 1 differs from the power conversion device 10 according to Embodiment 1 in the configuration of the n auxiliary circuits 50. The power conversion device 10C according to Modification 3 of Embodiment 1 includes n driving diodes 27. The other configurations of the power conversion device 10C according to Modification 3 of Embodiment 1 are similar to the configuration of the power conversion device 10 according to Embodiment 1.

[0124] [Auxiliary Circuit] In the third modification of the first embodiment, in each of the n auxiliary circuits 50, the auxiliary power supply unit 80 has a third auxiliary power supply diode 82c in addition to the configuration of the auxiliary power supply unit 80 shown in Fig. 2. The other configuration of the auxiliary circuit 50 of the third modification of the first embodiment is similar to the configuration of the auxiliary circuit 50 of the first embodiment.

[0125] One end of the third auxiliary power diode 82c is connected to the drive power supply unit 25 (drive line L25 in this example). The forward direction of the third auxiliary power diode 82c is from one end to the other end. The first auxiliary power diode 82a and the first auxiliary power resistor 83a are connected between one end (anode) of the third auxiliary power diode 82c and the first auxiliary power capacitor 81a. The second auxiliary power diode 82b and the second auxiliary power resistor 83b are connected between the other end (cathode) of the third auxiliary power diode 82c and the second auxiliary power capacitor 81b.

[0126] [Driving Diodes] The n driving diodes 27 correspond to the n driving units 30, respectively. Each of the n driving diodes 27 is connected between the high-side power supply unit 33 of the driving unit 30 corresponding to that driving diode 27 and the driving power supply unit 25 (driving line L25 in this example). The forward direction of each of the n driving diodes 27 is from the driving power supply unit 25 to the high-side power supply unit 33. Specifically, the anode of the driving diode 27 is connected to the driving line L25. The cathode of the driving diode 27 is connected to one end of the high-side power supply capacitor C33 via the high-side power supply resistor element R33 and the high-side power supply diode D33 of the high-side power supply unit 33.

[0127] [Advantages of Modification 3 of First Embodiment] With the motor unit 1 of Modification 3 of the first embodiment, advantages similar to those of the motor unit 1 of the first embodiment can be obtained.

[0128] In the motor unit 1 of Modification 3 of Embodiment 1, the provision of the third auxiliary power diode 82c makes it easy to reduce the difference between the "voltage generated in the first auxiliary power capacitor 81a" and the "voltage generated in the second auxiliary power capacitor 81b" (to make these voltages equal to each other), which makes it easy to reduce the difference in operation between the first auxiliary driver 71a and the second auxiliary driver 71b (for example, the time difference between charging and discharging the control terminal of the auxiliary switching element 61).

[0129] In the motor unit 1 of the third modification of the first embodiment, by providing n drive diodes 27, it is possible to easily reduce the difference in the "voltages generated in the high-side power supply capacitors C33" included in each of the n drive units 30 (to make these voltages the same), thereby easily reducing the difference in operation of each of the n drive units 30 (for example, the time difference between charging and discharging the control terminals of the switching elements SW).

[0130] 8 is a circuit diagram showing the configuration of a power conversion device 10D according to a fourth modification of the first embodiment. The power conversion device 10D according to the fourth modification of the first embodiment differs from the power conversion device 10 according to the first embodiment in the configuration of the n auxiliary circuits 50. The other configurations of the power conversion device 10D according to the fourth modification of the first embodiment are the same as the configurations of the power conversion device 10 according to the first embodiment.

[0131] [Auxiliary Circuit] In the fourth modification of the first embodiment, in each of the n auxiliary circuits 50, the auxiliary power supply unit 80 is configured so that a portion of the current flowing from the drive power supply unit 25 to the high-side power supply capacitor C33 in the high-side power supply unit 33 included in the drive unit 30 corresponding to the auxiliary circuit 50 flows to the main connection point P2 via the second auxiliary power supply capacitor 81 b.

[0132] In this example, the auxiliary power supply unit 80 of the fourth modification of the first embodiment has an auxiliary power line L8 instead of the second auxiliary power diode 82b and the second auxiliary power resistor 83b shown in Figure 2. The auxiliary power line L8 connects one end of the second auxiliary power capacitor 81b to one end of the high-side power supply capacitor C33 (the connection point between the high-side power supply capacitor C33 and the high-side power supply diode D33). The remaining configuration of the auxiliary power supply unit 80 of the fourth modification of the first embodiment is similar to the configuration of the auxiliary power supply unit 80 of the first embodiment.

[0133] [Effects of Modification 4 of First Embodiment] With the motor unit 1 of Modification 4 of the first embodiment, the same effects as those of the motor unit 1 of the first embodiment can be obtained.

[0134] In the motor unit 1 of the fourth modification of the first embodiment, the second auxiliary power supply diode 82b and the second auxiliary power supply resistor 83b shown in Fig. 2 can be omitted, thereby making it possible to reduce the size of the auxiliary circuit 50.

[0135] 9 is a circuit diagram showing the configuration of a power conversion device 10E of embodiment 2. The power conversion device 10E of embodiment 2 differs from the power conversion device 10 of embodiment 1 in the configurations of the auxiliary switching units 60 and the auxiliary power supply units 80 in each of the n auxiliary circuits 50. The other configurations of the power conversion device 10E of embodiment 2 are similar to the configurations of the power conversion device 10 of embodiment 1.

[0136] [Auxiliary Switching Unit] In the second embodiment, in each of the n auxiliary circuits 50, the auxiliary switching unit 60 has a first auxiliary switching element 61a, a second auxiliary switching element 61b, a first auxiliary diode 62a, and a second auxiliary diode 62b.

[0137] The first auxiliary switching element 61a and the second auxiliary switching element 61b are connected in series between the main connection point P2 and the resonant inductor 41. The second auxiliary switching element 61b is connected between the first auxiliary switching element 61a and the resonant inductor 41.

[0138] The first auxiliary diode 62a is connected between the resonant inductor 41 and an auxiliary connection point P6, which is the connection point between the first auxiliary switching element 61a and the second auxiliary switching element 61b. The forward direction of the first auxiliary diode 62a is from the auxiliary connection point P6 toward the resonant inductor 41. The second auxiliary diode 62b is connected between the main connection point P2 and the auxiliary connection point P6. The forward direction of the second auxiliary diode 62b is from the auxiliary connection point P6 toward the main connection point P2.

[0139] Specifically, one end (collector or drain) of the first auxiliary switching element 61a is connected to the main connection point P2. One end (collector or drain) of the second auxiliary switching element 61b is connected to the resonant connection point P4. The other end (emitter or source) of the first auxiliary switching element 61a is connected to the other end (emitter or source) of the second auxiliary switching element 61b. The anode of the first auxiliary diode 62a is connected to the auxiliary connection point P6. The cathode of the first auxiliary diode 62a is connected to the resonant connection point P4. The anode of the second auxiliary diode 62b is connected to the auxiliary connection point P6. The cathode of the second auxiliary diode 62b is connected to the main connection point P2.

[0140] Auxiliary Power Supply Unit In the second embodiment, in each of the n auxiliary circuits 50, the auxiliary power supply unit 80 has one auxiliary power supply capacitor 81. The auxiliary power supply capacitor 81 is provided to generate an operating voltage for the first auxiliary driver 71a and an operating voltage for the second auxiliary driver 71b. The auxiliary power supply unit 80 is configured so that, when the first auxiliary switching element 61a and the second auxiliary switching element 61b are off and the high-side switching element SWH is off, if the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 via the auxiliary power supply capacitor 81 to the main connection point P2.

[0141] In the second embodiment, the auxiliary power supply capacitor 81 is connected between the drive power supply unit 25 and the auxiliary connection point P6. The positive terminal of the first auxiliary driver 71a and the positive terminal of the second auxiliary driver 71b are connected to one end of the auxiliary power supply capacitor 81, and the voltage generated in the auxiliary power supply capacitor 81 is applied to them. The negative terminal of the first auxiliary driver 71a and the negative terminal of the second auxiliary driver 71b are connected to the auxiliary connection point P6, and the voltage at the auxiliary connection point P6 is applied to them.

[0142] [Charging Operation of Auxiliary Power Supply Capacitor] The following describes the charging operation of the auxiliary power supply capacitor 81 in the auxiliary circuit 50 of embodiment 2. When the auxiliary switching element 61 (first auxiliary switching element 61a and second auxiliary switching element 61b) is off and the high-side switching element SWH is off, if the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 to the auxiliary power supply unit 80 via the drive line L25.

[0143] The current flowing into auxiliary power supply 80 passes sequentially through auxiliary power supply resistor 83, auxiliary power supply diode 82, and auxiliary power supply capacitor 81 in auxiliary power supply 80, and then passes sequentially through auxiliary connection point P6 and second auxiliary diode 62b in auxiliary switching unit 60. Thereafter, the current flowing into auxiliary power supply 80 passes sequentially through main connection point P2 and low-side switching element SWL in the on state, and flows into negative line L2. In this way, a charging path for auxiliary power supply capacitor 81 is formed, and auxiliary power supply capacitor 81 is charged.

[0144] [Effects of Second Embodiment] The motor unit 1 of the second embodiment can achieve the same effects as the motor unit 1 of the first embodiment.

[0145] In the motor unit 1 of the second embodiment, the third auxiliary diode 62c and the fourth auxiliary diode 62d shown in Fig. 2 can be omitted, thereby making it possible to reduce the size of the auxiliary circuit 50.

[0146] In the motor unit 1 of the second embodiment, the second auxiliary power diode 82b and the second auxiliary power resistor 83b shown in Fig. 2 can be omitted, thereby making it possible to reduce the size of the auxiliary circuit 50.

[0147] 10 is a circuit diagram showing the configuration of a power conversion device 10F of embodiment 3. The power conversion device 10F of embodiment 3 differs from the power conversion device 10 of embodiment 1 in the configuration and processing of the n auxiliary circuits 50. The other configurations and processing of the power conversion device 10F of embodiment 3 are similar to the configurations and processing of the power conversion device 10 of embodiment 1.

[0148] [Auxiliary Switching Unit] In the third embodiment, the auxiliary switching unit 60 in each of the n auxiliary circuits 50 includes one auxiliary switching element 61, a first auxiliary diode 62 a, a second auxiliary diode 62 b, a third auxiliary diode 62 c, and a fourth auxiliary diode 62 d. The first auxiliary diode 62 a, the second auxiliary diode 62 b, the third auxiliary diode 62 c, and the fourth auxiliary diode 62 d form a diode bridge circuit.

[0149] The first auxiliary diode 62a is connected between the main connection point P2 and one end (emitter or source) of the auxiliary switching element 61. The forward direction of the first auxiliary diode 62a is from the main connection point P2 to the auxiliary switching element 61. The second auxiliary diode 62b is connected between the other end (collector or drain) of the auxiliary switching element 61 and the resonant inductor 41. The forward direction of the second auxiliary diode 62b is from the auxiliary switching element 61 to the resonant inductor 41.

[0150] The third auxiliary diode 62c is connected between the resonant inductor 41 and one end of the auxiliary switching element 61. The forward direction of the third auxiliary diode 62c is from the resonant inductor 41 to the auxiliary switching element 61. The fourth auxiliary diode 62d is connected between the other end of the auxiliary switching element 61 and the main connection point P2. The forward direction of the fourth auxiliary diode 62d is from the auxiliary switching element 61 to the main connection point.

[0151] Specifically, one end of the auxiliary switching element 61 is connected to the cathode of the first auxiliary diode 62a and the cathode of the third auxiliary diode 62c. The other end of the auxiliary switching element 61 is connected to the anode of the second auxiliary diode 62b and the anode of the fourth auxiliary diode 62d. The main connection point P2 is connected to the anode of the first auxiliary diode 62a and the cathode of the fourth auxiliary diode 62d. The resonant connection point P4 is connected to the anode of the third auxiliary diode 62c and the cathode of the second auxiliary diode 62b.

[0152] [Auxiliary Driving Unit] In the second embodiment, in each of the n auxiliary circuits 50, the auxiliary driving unit 70 has one auxiliary driver 71 and one auxiliary output resistor element 72. The auxiliary driver 71 controls the on / off of the auxiliary switching element 61 in response to control by the control unit 55. For example, in the operation of the power conversion device 10 shown in Figures 3 and 4, the auxiliary switching element 61 is controlled to be on during a period in which the first auxiliary switching element 61a or the second auxiliary switching element 61b is on, and to be off during a period in which the first auxiliary switching element 61a and the second auxiliary switching element 61b are off.

[0153] Auxiliary Power Supply Unit In the third embodiment, each of the n auxiliary circuits 50 includes one auxiliary power supply capacitor 81. The auxiliary power supply capacitor 81 is provided to generate the operating voltage of one auxiliary driver 71. The auxiliary power supply unit 80 is configured such that, when the first auxiliary switching element 61 a and the second auxiliary switching element 61 b ​​are off and the high-side switching element SWH is off, and the low-side switching element SWL is turned on, a current flows from the drive power supply unit 25 via the auxiliary power supply capacitor 81 toward the main connection point P2.

[0154] In the third embodiment, the auxiliary power supply capacitor 81 is connected between the drive power supply unit 25 and the connection point between the other end of the auxiliary switching element 61 and the fourth auxiliary diode 62d. The positive terminal of the auxiliary driver 71 is connected to one end of the auxiliary power supply capacitor 81. The voltage generated in the auxiliary power supply capacitor 81 is applied to the positive terminal of the auxiliary driver 71. The negative terminal of the auxiliary driver 71 is connected to the connection point between the other end of the auxiliary switching element 61 and the fourth auxiliary diode 62d. The voltage at the connection point between the other end of the auxiliary switching element 61 and the fourth auxiliary diode 62d is applied to the negative terminal of the auxiliary driver 71.

[0155] [Charging Operation of Auxiliary Power Supply Capacitor] The following describes the charging operation of the auxiliary power supply capacitor 81 in the auxiliary circuit 50 of embodiment 3. When the low-side switching element SWL is turned on while the auxiliary switching element 61 (first auxiliary switching element 61a and second auxiliary switching element 61b) is off and the high-side switching element SWH is off, a current flows from the drive power supply unit 25 to the auxiliary power supply unit 80 via the drive line L25.

[0156] The current flowing into auxiliary power supply unit 80 passes through auxiliary power supply resistor element 83, auxiliary power supply diode 82, and auxiliary power supply capacitor 81 in this order, and then passes through fourth auxiliary diode 62d in auxiliary switching unit 60. Thereafter, the current flowing into auxiliary power supply unit 80 passes through main connection point P2 and low-side switching element SWL in the on state in this order, and flows into negative line L2. In this way, a charging path for auxiliary power supply capacitor 81 is formed, and auxiliary power supply capacitor 81 is charged.

[0157] [Effects of Third Embodiment] The motor unit 1 of the third embodiment can achieve the same effects as the motor unit 1 of the first embodiment.

[0158] In the motor unit 1 of the third embodiment, the second auxiliary switching element 61b shown in Fig. 2 can be omitted, thereby making it possible to reduce the size of the auxiliary circuit 50.

[0159] (Other Embodiments) In the above description, "power supplied from the power supply 11, which is a DC power supply," has been given as an example of the input voltage. However, the input voltage is not limited to this. For example, the input voltage may be a DC voltage obtained by rectifying an AC voltage supplied from the power supply 11, which is an AC power supply, using a converter.

[0160] In the above description, the control unit 55 may be configured by a single processor or by multiple processors.

[0161] The above-described embodiments may be implemented in appropriate combinations. The above-described embodiments are essentially preferred examples and are not intended to limit the scope of the technology disclosed herein, its applications, or its uses.

[0162] As described above, the technology disclosed herein is useful as an auxiliary circuit, a power conversion device, a motor unit, and the like.

[0163] 1 Motor unit 10, 10A, 10B, 10C, 10D, 10E,10F Power conversion device 11 Power supply 12 Motor 20 Conversion unit 21 Leg SWH High-side switching element SWL Low-side switching element DH High-side freewheeling diode DL Low-side freewheeling diode P2 Main connection point 25 Drive power supply unit 26 Control power supply unit 27 Drive diode 30 Drive unit 31 High-side drive unit 32 High-side driver 33 High-side power supply unit C33 High-side power supply capacitor D33 High-side power supply diode R33 High-side power supply resistor 34 High-side output resistor 35 Low-side drive unit 36 ​​Low-side driver 37 Low-side output resistor 40 Resonant unit 41 Resonant inductor 42 Resonant power supply capacitor 43 First resonant diode 44 Second resonant diode 45 Resonant capacitor 50 Auxiliary circuit 55 Control unit 60 Auxiliary switching unit 61 Auxiliary switching element 61a First auxiliary switching element 61b 82a First auxiliary power supply diode 82b Second auxiliary power supply diode 82c Third auxiliary power supply diode 82d Fourth auxiliary power supply diode P6 Auxiliary connection point 70 Auxiliary drive unit 71 Auxiliary driver 71a First auxiliary driver 71b Second auxiliary driver 72 Auxiliary output resistor 72a First auxiliary output resistor 72b Second auxiliary output resistor 80 Auxiliary power supply unit 81 Auxiliary power supply capacitor 81a First auxiliary power supply capacitor 81b Second auxiliary power supply capacitor 82 Auxiliary power supply diode 82a First auxiliary power supply diode 82b Second auxiliary power supply diode 82c Third auxiliary power supply diode 83 Auxiliary power supply resistor 83a First auxiliary power supply resistor 83b Second auxiliary power supply resistor 91 Resonance voltage sensor 92 Power supply voltage sensor L1 Positive electrode line L2 Negative electrode line L3 Output line C1 Smoothing capacitor

Claims

1. An auxiliary circuit for use in a power conversion device having a conversion unit, a drive power supply unit, and a resonance unit, which converts an input voltage applied between a positive electrode line and a negative electrode line into an output voltage, the auxiliary circuit comprising: an auxiliary switching unit, an auxiliary drive unit, and an auxiliary power supply unit; the conversion unit has a leg including a high-side switching element and a low-side switching element connected in series between the positive electrode line and the negative electrode line, and converts the input voltage into the output voltage by switching on and off the high-side switching element and the low-side switching element; the drive power supply unit generates a drive voltage used to control the on and off of the high-side switching element and the low-side switching element based on the input voltage; the resonance unit has a resonance inductor and a resonance capacitor connected to a main connection point which is a connection point between the high-side switching element and the low-side switching element; the auxiliary switching unit has an auxiliary switching element provided between the main connection point and the resonance inductor, and is configured such that when the auxiliary switching element is on, a current flows between the main connection point and the resonance inductor; the auxiliary driving unit has an auxiliary driver that controls the on / off of the auxiliary switching element; and the auxiliary power supply unit has an auxiliary power supply capacitor for generating an operating voltage for the auxiliary driver, and when the auxiliary switching element and the high-side switching element are off and the low-side switching element are on, a current flows from the driving power supply unit via the auxiliary power supply capacitor to the main connection point.

2. An auxiliary circuit according to claim 1, wherein the auxiliary switching section has a first auxiliary switching element and a second auxiliary switching element provided between the main connection point and the resonant inductor, and is configured so that when the first auxiliary switching element is on and the second auxiliary switching element is off, a current flows from the main connection point to the resonant inductor, and when the first auxiliary switching element is off and the second auxiliary switching element is on, a current flows from the resonant inductor to the main connection point; the auxiliary drive section has a first auxiliary driver that controls the on / off of the first auxiliary switching element and a second auxiliary driver that controls the on / off of the second auxiliary switching element; the auxiliary power supply section has a first auxiliary power supply capacitor for generating an operating voltage for the first auxiliary driver and a second auxiliary power supply capacitor for generating an operating voltage for the second auxiliary driver, the auxiliary switching element being the first auxiliary switching element, the auxiliary driver being the first auxiliary driver, and the auxiliary power supply capacitor being the first auxiliary power supply capacitor.

3. The auxiliary circuit of claim 2, wherein said auxiliary power supply unit is configured such that, when said first auxiliary switching element and said second auxiliary switching element are off and said high-side switching element is off, when said low-side switching element is turned on, a current flows from said drive power supply unit via said first auxiliary power supply capacitor and said second auxiliary power supply capacitor to said main connection point.

4. In the auxiliary circuit of claim 3, the first auxiliary switching element and the second auxiliary switching element are connected in parallel between the main connection point and the resonant inductor, and the auxiliary switching section comprises: a first auxiliary diode connected between the first auxiliary switching element and the resonant inductor, with a forward direction being the direction from the first auxiliary switching element to the resonant inductor; a second auxiliary diode connected in parallel with the first auxiliary switching element between the main connection point and the first auxiliary diode, with a forward direction being the direction from the first auxiliary diode to the main connection point; a third auxiliary diode connected between the second auxiliary switching element and the resonant inductor, with a forward direction being the direction from the resonant inductor to the second auxiliary switching element; and a fourth auxiliary diode connected in parallel with the second auxiliary switching element between the main connection point and the third auxiliary diode, with a forward direction being the direction from the main connection point to the third auxiliary diode; and the first auxiliary power capacitor is connected between the connection point of the first auxiliary switching element and the first auxiliary diode and the drive power supply section, The second auxiliary power capacitor is connected between the main connection point and the drive power supply unit.

5. The auxiliary circuit of claim 4, wherein the auxiliary power supply unit comprises: a first auxiliary power supply diode connected between the drive power supply unit and the first auxiliary power supply capacitor, the forward direction being from the drive power supply unit to the first auxiliary power supply capacitor; a first auxiliary power supply resistance element connected in series with the first auxiliary power supply diode between the drive power supply unit and the first auxiliary power supply capacitor; a second auxiliary power supply diode connected between the drive power supply unit and the second auxiliary power supply capacitor, the forward direction being from the drive power supply unit to the second auxiliary power supply capacitor; and a second auxiliary power supply resistance element connected in series with the second auxiliary power supply diode between the drive power supply unit and the second auxiliary power supply capacitor.

6. An auxiliary circuit according to claim 5, wherein said auxiliary power supply section has a third auxiliary power supply diode whose forward direction is from one end connected to said drive power supply section to the other end, said first auxiliary power supply diode and said first auxiliary power supply resistance element are connected between one end of said third auxiliary power supply diode and said first auxiliary power supply capacitor, and said second auxiliary power supply diode and said second auxiliary power supply resistance element are connected between the other end of said third auxiliary power supply diode and said second auxiliary power supply capacitor.

7. An auxiliary circuit according to claim 2, wherein the on / off of said high side switching element is controlled by a high side drive unit, said high side drive unit having a high side driver which controls the on / off of said high side switching element, and a high side power supply unit which has a high side power supply capacitor for generating an operating voltage for said high side driver, and which is configured so that when said high side switching element is off and said low side switching element is on, a current flows from said drive power supply unit to said main connection point via said high side power supply capacitor, and said auxiliary power supply unit is configured so that a part of the current flowing from said drive power supply unit to said high side power supply capacitor in said high side power supply unit flows to said main connection point via said second auxiliary power supply capacitor.

8. An auxiliary circuit according to claim 1, wherein the auxiliary switching section has a first auxiliary switching element and a second auxiliary switching element provided between the main connection point and the resonant inductor, and is configured such that when the first auxiliary switching element is on and the second auxiliary switching element is off, a current flows from the main connection point to the resonant inductor, and when the first auxiliary switching element is off and the second auxiliary switching element is on, a current flows from the resonant inductor to the main connection point; the auxiliary driving section has a first auxiliary driver that controls the on / off of the first auxiliary switching element and a second auxiliary driver that controls the on / off of the second auxiliary switching element; the auxiliary power supply capacitor is provided for generating an operating voltage for the first auxiliary driver and an operating voltage for the second auxiliary driver, the auxiliary switching element is the first auxiliary switching element, and the auxiliary driver is the first auxiliary driver.

9. An auxiliary circuit according to claim 8, wherein the first auxiliary switching element and the second auxiliary switching element are connected in series between the main connection point and the resonant inductor, the second auxiliary switching element is connected between the first auxiliary switching element and the resonant inductor, the auxiliary switching section has: a first auxiliary diode connected between the resonant inductor and an auxiliary connection point which is the connection point between the first auxiliary switching element and the second auxiliary switching element, and whose forward direction is from the auxiliary connection point to the resonant inductor, and a second auxiliary diode connected between the main connection point and the auxiliary connection point, and whose forward direction is from the auxiliary connection point to the main connection point, and the auxiliary power supply capacitor is connected between the drive power supply section and the auxiliary connection point.

10. An auxiliary circuit as claimed in claim 1, wherein the auxiliary switching section comprises: a first auxiliary diode connected between the main connection point and one end of the auxiliary switching element, the forward direction being the direction from the main connection point to the auxiliary switching element; a second auxiliary diode connected between the other end of the auxiliary switching element and the resonant inductor, the forward direction being the direction from the auxiliary switching element to the resonant inductor; a third auxiliary diode connected between the resonant inductor and one end of the auxiliary switching element, the forward direction being the direction from the resonant inductor to the auxiliary switching element; and a fourth auxiliary diode connected between the other end of the auxiliary switching element and the main connection point, the forward direction being the direction from the auxiliary switching element to the main connection point; and the auxiliary power supply capacitor is connected between the connection point between the other end of the auxiliary switching element and the fourth auxiliary diode and the drive power supply section.

11. A power conversion device comprising: n auxiliary circuits, each of which is an auxiliary circuit according to any one of claims 1 to 10; the conversion unit; the drive power supply unit; and the resonance unit, wherein n is an integer equal to or greater than 1; the conversion unit has n legs, each of which is a leg; the resonance unit has the resonance inductor and n resonance capacitors, each of which is a resonance capacitor and corresponds to the n legs; and the n auxiliary circuits each correspond to the n legs.

12. A motor unit comprising: a motor; and the power conversion device according to claim 11 that drives the motor.

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