Power conversion device and drive system

Abstract

The present invention provides a power conversion device and drive system that can improve the charging efficiency of a DC power source using an AC power source. [Solution] The power conversion circuit 4 has inverters 8 and 9 and a switching circuit 10. The first inverter 8 is connected to one end of windings 3U, 3V, and 3W via a first output line 13. The second inverter 9 is connected to the other end of windings 3U, 3V, and 3W via a second output line 14. The switching circuit 10 is connected to the second output line 14. When the switching circuit 10 is in a neutral state, windings 3U, 3V, and 3W are star-connected. When the switching circuit 10 is in an open state, windings 3U, 3V, and 3W are open-connected. The power conversion circuit 4 has a semi-switch 22. When the DC power supply 2 is charged by an external device 16, the power conversion circuit 4, including the semi-switch 22, forms a semi-bridgeless PFC 20.

Description

Technical Field

[0006] , , , ,

[0001] The disclosure in this specification relates to a power conversion device and a drive system.

Background Art

[0002] Patent Document 1 discloses a power conversion device including a first inverter connected to one end of a winding of a rotating electric machine and a second inverter connected to the other end of the winding. The first inverter and the second inverter are capable of converting the power supplied from a DC power source to the rotating electric machine. The description of the prior art document is incorporated herein by reference as an explanation of the technical elements in this specification.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to charge a DC power source, an AC power source may be connected to the first inverter or the second inverter. When the power supplied from the AC power source to the DC power source is converted from AC power to DC power by the first inverter or the second inverter, there is a concern that the charging efficiency of the DC power source by the AC power source may decrease. From the above viewpoints, or from other viewpoints not mentioned, further improvement is required for the power conversion module.

[0005] One object of the disclosure is to provide a power conversion device and a drive system capable of improving the charging efficiency of a DC power source by an AC power source.

Means for Solving the Problems

[0006] One aspect of the disclosure is A power converter (4) that converts the power supplied from a DC power source (2) to a rotating electric machine (3), A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between star connection and open connection, A charging connection section (23) to which an AC power supply (16) for charging a DC power supply is connected, With an AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), It is a power conversion device equipped with [a specific feature / ability].

[0007] According to the power conversion device described above, the bridgeless component, together with at least one of the first inverter, the second inverter, and the switching circuit, forms a bridgeless type power factor correction circuit. In this configuration, when an AC power source is connected to the charging connection, the power factor of the power converted from AC power to DC power is easily improved by the bridgeless type power factor correction circuit. Therefore, the charging efficiency of the DC power source by the AC power source can be increased.

[0008] One form of disclosure is, Rotating electric machine (3) and A power converter (4) that converts the power supplied from a DC power source (2) to a rotating electric machine, A drive system (1) that includes a power converter and drives a rotating electric machine, A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between star connection and open connection, A charging connection section (23) to which an AC power supply (16) for charging a DC power supply is connected, With an AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), It is a drive system equipped with [a specific feature / feature].

[0009] According to the above drive system, similar to the above power conversion device, the charging efficiency of a DC power supply using an AC power supply can be improved.

[0010] The various embodiments disclosed in this specification employ different technical means to achieve their respective objectives. The claims and the reference numerals in parentheses in this section are illustrative in their correspondence with the embodiments described later and are not intended to limit the technical scope. The objectives, features, and effects disclosed in this specification will become clearer by referring to the subsequent detailed description and the accompanying drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the power conversion circuit and drive system in the first embodiment. [Figure 2] This figure shows an example of an operating point map for a rotating electric machine. [Figure 3] This diagram shows a star-connection drive. [Figure 4] This diagram shows an open-connection drive. [Figure 5] This diagram shows a power conversion circuit in which a semi-bridgeless PFC is formed. [Figure 6] This is a flowchart showing the procedure for power conversion control. [Figure 7] This diagram shows the current flowing through the V-phase winding when the AC voltage is positive. [Figure 8] This diagram shows the current flowing from the V-phase winding to the smoothing capacitor. [Figure 9] This diagram shows the current flowing through the W-phase winding when the AC voltage is negative. [Figure 10]It is a diagram showing the current flowing from the W-phase winding to the smoothing capacitor. [Figure 11] It is a diagram showing a power conversion circuit and a drive system in the second embodiment. [Figure 12] It is a diagram showing a power conversion circuit in which a totem-pole bridgeless PFC is formed. [Figure 13] It is a flowchart showing the procedure of power conversion control. [Figure 14] It is a diagram showing the current flowing through the V-phase winding when the AC voltage is a positive voltage. [Figure 15] It is a diagram showing the current flowing from the V-phase winding to the smoothing capacitor. [Figure 16] It is a diagram showing the current flowing through the W-phase winding when the AC voltage is a negative voltage. [Figure 17] It is a diagram showing the current flowing from the W-phase winding to the smoothing capacitor.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a plurality of embodiments will be described based on the drawings. In each embodiment, corresponding components may be denoted by the same reference numerals, and redundant explanations may be omitted. When only a part of the configuration is described in each embodiment, the configuration of other embodiments described previously can be applied to other parts of the said configuration. Also, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of multiple embodiments can be partially combined with each other as long as there is no problem with the combination.

[0013] The power conversion module of this embodiment is applied to, for example, a moving body having a rotating electric machine as a drive source. The moving body is, for example, an electric vehicle such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a flying body such as an electric vertical take-off and landing aircraft or a drone, a ship, construction machinery, agricultural machinery, etc.

[0014] (First Embodiment) First, based on Figure 1, we will explain the general configuration of the drive system for the mobile body.

[0015] <Motorization system for mobile vehicles> As shown in Figure 1, the drive system 1 for the mobile body includes a DC power supply 2, a rotating electric machine 3, and a power conversion circuit 4.

[0016] The DC power supply 2 may be, for example, a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The DC power supply 2 may also convert AC power to DC power for output. The DC power supply 2 supplies power to the rotating electric machine 3. The DC power supply 2 may be formed by including an energy storage device as a secondary battery.

[0017] Rotating electric machine 3 is an open-winding type rotating electric machine with an open neutral point. Rotating electric machine 3 has a U-phase winding 3U, a V-phase winding 3V, and a W-phase winding 3W. Hereafter, the U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W may be simply referred to as windings 3U, 3V, and 3W. Rotating electric machine 3 is a multi-phase rotating electric machine. For example, rotating electric machine 3 is a three-phase rotating electric machine.

[0018] The rotating electric machine 3 functions, for example, as a drive source for a moving body, i.e., an electric motor. If the moving body is a vehicle, the rotating electric machine 3 generates torque to drive drive wheels (not shown). The rotating electric machine 3 is not limited to an electric motor. The rotating electric machine 3 may be a motor-generator having both electric motor and generator functions, or it may be a generator.

[0019] The power conversion circuit 4 performs power conversion between the DC power supply 2 and the rotating electric machine 3. The power conversion circuit 4 corresponds to a power conversion device. The power conversion circuit 4 is a three-phase power conversion device. The drive system 1 is a common power supply system that supplies power from a common DC power supply 2 to two inverters 8 and 9, which will be described later, in order to drive the rotating electric machine 3. The drive system 1 may have only one common DC power supply 2, or it may have multiple common DC power supplies 2, as illustrated in Figure 1. The drive system 1 may also have a power supply switch, such as an SMR (not shown), between the DC power supply 2 and the power conversion circuit 4. SMR is an abbreviation for System Main Relay. When the power supply switch is turned on, power can be supplied from the DC power supply 2 to the rotating electric machine 3, and when the power supply switch is turned off, the power supply from the DC power supply 2 to the rotating electric machine 3 is cut off.

[0020] <Power Conversion Circuit> Next, the power conversion circuit 4 will be described based on Figure 1. Figure 1 shows an example of the power conversion circuit 4. The power conversion circuit 4 illustrated in Figure 1 includes power lines 5 and 6, a smoothing capacitor 7, inverters 8 and 9, and a switching circuit 10.

[0021] Power line 5 is a high-potential power line. Power line 5 is connected to the positive terminal of the DC power supply 2. Power line 5 corresponds to the positive terminal path. Power line 5 is sometimes referred to as the positive terminal power line, P line, etc. Power line 5 has wiring 5A. Wiring 5A is a part of the wiring that makes up power line 5. Wiring 5A is the wiring that connects the first inverter 8 and the second inverter 9 of power line 5. Power line 6 is a low-potential power line. Power line 6 is connected to the negative terminal of the DC power supply 2. Power line 6 corresponds to the negative terminal path. Power line 6 is sometimes referred to as the negative terminal power line, N line, etc. Power line 6 has wiring 6A. Wiring 6A is a part of the wiring that makes up power line 6. Wiring 6A is the wiring that connects the first inverter 8 and the second inverter 9 of power line 6. Power lines 5 and 6 are composed of busbars, for example, made of metal plate material.

[0022] The smoothing capacitor 7 primarily smooths the DC voltage supplied from the DC power supply 2. The smoothing capacitor 7 is located between power lines 5 and 6. The positive terminal of the smoothing capacitor 7 is connected to power line 5 between the DC power supply 2 and inverters 8 and 9. The negative terminal of the smoothing capacitor 7 is connected to power line 6 between the DC power supply 2 and inverters 8 and 9. The smoothing capacitor 7 is connected in parallel to inverters 8 and 9.

[0023] Inverters 8 and 9 are DC-AC conversion circuits. Inverters 8 and 9 are three-phase inverter circuits. The first inverter 8 corresponds to the first inverter, and the second inverter 9 corresponds to the second inverter. The first inverter 8 is configured with three phase upper and lower arm circuits 8HL. The upper and lower arm circuits 8HL are sometimes referred to as legs. The upper and lower arm circuits 8HL have an upper arm 8H and a lower arm 8L. The upper arm 8H and lower arm 8L are connected in series between power lines 5 and 6, with the upper arm 8H on the power line 5 side.

[0024] The connection point between the upper arm 8H and the lower arm 8L is connected to the corresponding phase winding in the rotating electric machine 3 via the first output line 13. The first output line 13 corresponds to the first path. The first inverter 8 has six arms. Each arm is configured with a switching element such as a semiconductor element. The number of switching elements constituting each arm is not particularly limited. There may be one or more. In the case of multiple switching elements, the multiple switching elements connected in parallel to each other are driven on and off at the same timing by a common gate drive signal (drive voltage).

[0025] The first inverter 8 has a first arm switch 8S. The first arm switch 8S is a switching element that constitutes each arm. The first arm switch 8S corresponds to the first switch. In the example shown in Figure 1, an n-channel type MOSFET is used as the first arm switch 8S. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the upper arm 8H, the drain terminal of the first arm switch 8S is connected to the power line 5. In the lower arm 8L, the source terminal of the first arm switch 8S is connected to the power line 6. The source terminal of the first arm switch 8S in the upper arm 8H and the drain terminal of the first arm switch 8S in the lower arm 8L are interconnected.

[0026] Each of the first arm switches 8S has a freewheeling diode 8D connected in antiparallel. Diode 8D may be a parasitic diode (body diode) of the first arm switch 8S, or it may be a separate diode. The anode terminal of diode 8D is connected to the source terminal of the corresponding first arm switch 8S, and the cathode terminal is connected to the drain terminal.

[0027] The second inverter 9 has the same configuration as the first inverter 8. The second inverter 9 is configured with three phase upper and lower arm circuits 9HL. The upper and lower arm circuits 9HL have an upper arm 9H and a lower arm 9L. The upper arm 9H and the lower arm 9L are connected in series between power lines 5 and 6, with the upper arm 9H on the power line 5 side.

[0028] The connection point between the upper arm 9H and the lower arm 9L is connected to the winding of the corresponding phase in the rotating electric machine 3 via the second output line 14. The second output line 14 corresponds to the second path. The second inverter 9 also has six arms. Each arm is configured with a switching element. The number of switching elements constituting each arm is not particularly limited; there may be one or more.

[0029] The second inverter 9 has a second arm switch 9S. The second arm switch 9S is a switching element that constitutes each arm. The second arm switch 9S corresponds to the second switch. In the example shown in Figure 1, an n-channel type second arm switch 9S is used as the second arm switch 9S. In the upper arm 9H, the drain terminal of the second arm switch 9S is connected to the power line 5. In the lower arm 9L, the source terminal of the second arm switch 9S is connected to the power line 6. The source terminal of the second arm switch 9S in the upper arm 9H and the drain terminal of the second arm switch 9S in the lower arm 9L are interconnected. A recirculating diode 9D is connected in antiparallel to each of the second arm switches 9S.

[0030] As described above, the high-potential terminals (drain terminals) of the upper arms 8H and 9H of inverters 8 and 9 are connected to power line 5. The low-potential terminals (source terminals) of the lower arms 8L and 9L are connected to power line 6. The node where the upper arm 8H and lower arm 8L connect is connected to one end of the winding of the corresponding phase via the first output line 13, and the node where the upper arm 9H and lower arm 9L connect is connected to the other end of the winding of the corresponding phase via the second output line 14. Specifically, node U1 of the U-phase upper and lower arm circuit 8HL is connected to one end of the U-phase winding 3U, and node U2 of the U-phase upper and lower arm circuit 9HL is connected to the other end of the U-phase winding 3U. Node V1 of the V-phase upper and lower arm circuit 8HL is connected to one end of the V-phase winding 3V, and node V2 of the V-phase upper and lower arm circuit 9HL is connected to the other end of the V-phase winding 3V. Node W1 of the W-phase upper and lower arm circuit 8HL is connected to one end of the W-phase winding 3W, and node W2 of the W-phase upper and lower arm circuit 9HL is connected to the other end of the W-phase winding 3W.

[0031] Note that the switching elements constituting inverters 8 and 9 are not limited to the MOSFETs described above. For example, IGBTs may be used. IGBT stands for Insulated Gate Bipolar Transistor. In the case of IGBTs, a freewheeling diode is also connected in antiparallel.

[0032] The power conversion circuit 4 may have a snubber circuit. The snubber circuit may be connected in parallel to the upper and lower arm circuits 8HL and 9HL. For example, the snubber circuit is formed by including capacitors and resistors.

[0033] The switching circuit 10 can switch the connections of windings 3U, 3V, and 3W between a star connection and an open connection. The star connection is sometimes referred to as a Y connection. The open connection is sometimes referred to as an H connection. The switching circuit 10 can transition between a neutral state and an open state. In the power conversion circuit 4, when the switching circuit 10 is in the neutral state and the second inverter 9 is in the off state, windings 3U, 3V, and 3W are connected in a star configuration. In this case, the switching circuit 10 forms the neutral point of the star connection. In the power conversion circuit 4, when the switching circuit 10 is in the open state, windings 3U, 3V, and 3W are connected in an open configuration. In this case, the switching circuit 10 opens the neutral point of windings 3U, 3V, and 3W.

[0034] The switching circuit 10 is connected to the second output line 14, but not to the first output line 13. The switching circuit 10 is connected to the second output line 14 on the opposite side from the first inverter 8 via the rotating electric machine 3. The rotating electric machine 3 is driven by the first inverter 8 when it is Y-connected by the switching circuit 10.

[0035] The switching circuit 10 includes a changeover switch 10S, a changeover diode 10D, a changeover wire 11, and a changeover connection point 12. The changeover wire 11 is connected to windings 3U, 3V, and 3W, respectively. For example, the changeover wire 11 is connected to the second output wire 14 in each of the three phases. The changeover wires 11 provided in each of the three phases are connected at the changeover connection point 12. The changeover connection point 12 forms the neutral point of windings 3U, 3V, and 3W when the switching circuit 10 is in the neutral point state.

[0036] The changeover switch 10S is provided on the changeover line 11 for each of the three phases. The changeover switch 10S for the U phase is connected to the U phase winding 3U in a way that allows power to pass through. The changeover switch 10S for the V phase is connected to the V phase winding 3V in a way that allows power to pass through. The changeover switch 10S for the W phase is connected to the W phase winding 3W in a way that allows power to pass through.

[0037] The changeover switch 10S is a semiconductor switch. A semiconductor switch is made by forming a switching element on a semiconductor chip. The changeover switch 10S can interrupt the switching line 11. The changeover switch 10S can transition between a closed state and an open state. In the closed state, the changeover switch 10S makes the windings 3U, 3V, 3W and the switching connection point 12 conductive. In the open state, the changeover switch 10S interrupts the conductivity between the windings 3U, 3V, 3W and the switching connection point 12.

[0038] The changeover switch 10S illustrated in Figure 1 is an n-channel type MOSFET. A switching diode 10D is connected in antiparallel to the changeover switch 10S. The switching diode 10D may be a parasitic diode of the changeover switch 10S, or it may be provided separately from the parasitic diode. The anode terminal of the switching diode 10D is connected to the source terminal of the changeover switch 10S, and the cathode terminal is connected to the drain terminal. The changeover switch 10S is positioned on the switching line 11 such that the drain terminal is on the winding 3U, 3V, 3W side and the source terminal is on the switching connection point 12 side. In other words, the forward direction of the switching diode 10D is positioned from the switching connection point 12 toward the winding 3U, 3V, 3W.

[0039] The changeover switch 10S can switch the switching circuit 10 between a neutral state and an open state. In the switching circuit 10, when all changeover switches 10S are closed, the switching circuit 10 becomes a neutral state. In the power conversion circuit 4, when all changeover switches 10S are closed and all second arm switches 9S in the second inverter 9 are turned off, windings 3U, 3V, and 3W are connected in a star configuration. When all changeover switches 10S are open, the switching circuit 10 becomes an open state. In the power conversion circuit 4, when all changeover switches 10S are open, windings 3U, 3V, and 3W are connected in an open configuration.

[0040] The first arm switch 8S and the second arm switch 9S are different types of switching elements. For example, the first arm switch 8S is a switching element with lower switching loss than the second arm switch 9S. The switching loss of the first arm switch 8S tends to be lower than that of the second arm switch 9S. For example, the first arm switch 8S is formed including a SiC semiconductor. In the first arm switch 8S, elements such as vertical elements are formed on a semiconductor substrate formed including SiC. SiC is silicon carbide. The second arm switch 9S is formed including a Si semiconductor. In the second arm switch 9S, elements such as vertical elements are formed on a semiconductor substrate formed including Si. Si is silicon.

[0041] The changeover switch 10S is the same type of switching element as the first arm switch 8S, but a different type of switching element than the second arm switch 9S. For example, the changeover switch 10S is formed including a SiC semiconductor. The changeover switch 10S is a lower-loss switching element than the second arm switch 9S. The changeover switch 10S is a switching element with losses equivalent to those of the first arm switch 8S.

[0042] The power conversion circuit 4 has a semicircular wire 21 and a semicircular switch 22. The semicircular wire 21 connects the switching circuit 10 and the power line 6. For example, the semicircular wire 21 connects the switching connection point 12 and the wiring 6A in a conduction manner. The semicircular switch 22 is provided on the semicircular wire 21. The semicircular switch 22 can interrupt the semicircular wire 21. The semicircular switch 22 can transition between a closed state and an open state. In the closed state, the semicircular switch 22 makes the switching circuit 10 and the wiring 6A conductive. The closed state of the semicircular switch 22 corresponds to the conduction state. In the open state, the semicircular switch 22 makes the switching circuit 10 and the wiring 6A conductive. The open state of the semicircular switch 22 corresponds to the interruption state. The semicircular switch 22 is sometimes referred to as a switch or switching switch.

[0043] The semi-switch 22 is formed by including switching elements such as semiconductor elements. The semi-switch 22 is sometimes referred to as a switch or on / off switch. The semi-switch 22 may also be formed by including a mechanical switch. A mechanical switch is a switch that has mechanical contacts.

[0044] The power conversion circuit 4 has a charging terminal 23, a charging switch 24, and a charging line 25. The charging terminal 23 is a terminal for connecting external equipment 16 (see Figure 5). The charging terminal 23 corresponds to the charging connection part. The charging terminal 23 is connected to the windings 3U, 3V, 3W and the switching circuit 10 via the charging line 25, etc. For example, the charging terminal 23 is connected to the second output line 14 via the charging line 25. The charging terminal 23 is connected to the second output line 14 of two phases. For example, the charging terminal 23 is connected to the second output line 14 of the V phase and the W phase.

[0045] The charging switch 24 is provided on the charging line 25. The charging switch 24 can interrupt the charging line 25. The charging switch 24 can transition between a closed state and an open state. In the closed state, the charging switch 24 connects the external device 16 and the DC power supply 2 via the power converter 4, enabling power flow. In the open state, the charging switch 24 interrupts the power flow between the external device 16 and the DC power supply 2. The charging switch 24 is formed by including a switching element such as a semiconductor element. The charging switch 24 may also be formed by including a mechanical switch. When the rotating electric machine 3 is running, the charging switch 24 is in the open state.

[0046] As illustrated in Figure 1, the power conversion circuit 4 may include a control unit (CTR) 15. The control unit 15 may be configured to include, for example, a processor 15a, memory 15b, and storage 15c. The processor 15a performs various processes by accessing memory 15b. Memory 15b is a rewritable volatile storage medium. Memory 15b is, for example, RAM. RAM is an abbreviation for Random Access Memory. Storage 15c is a rewritable non-volatile memory. Storage 15c may be implemented by at least one type of non-transitory tangible storage medium, such as semiconductor memory, magnetic media, and optical media. Storage 15c may include multiple types of storage media, such as ROM and flash memory. ROM is an abbreviation for Read Only Memory.

[0047] The storage 15c stores a program 15d that is executed by the processor 15a. The program 15d constructs multiple functional units by having the processor 15a execute multiple instructions. The processing performed by the control unit 15 may be realized by software processing, where the processor 15a executes the program 15d described above, or by hardware processing using dedicated electronic circuits. It may also be realized by a combination of software and hardware processing. The program 15d includes a program for executing the inverter control processing described later.

[0048] The control unit 15 may include, for example, a drive command generation unit (not shown) and a drive circuit unit. The drive command generation unit controls inverters 8 and 9. The drive command generation unit generates drive commands (command signals) to control the on / off state of arm switches 8S and 9S and outputs them to the drive circuit unit. The drive command generation unit generates drive commands based on drive requests for the rotating electric machine 3, such as torque command values ​​input from a higher-level ECU (not shown), and signals detected by various sensors. The various sensors may include current sensors, rotation angle sensors, voltage sensors, etc. (not shown).

[0049] The drive command generation unit controls the changeover switch 10S and the charging switch 24. The drive command generation unit generates drive commands to control the on / off state of the changeover switch 10S and the charging switch 24 and outputs them to the drive circuit unit. The drive circuit unit is sometimes referred to as the driver. Based on the drive commands, the drive circuit unit can independently control the on / off state of the arm switches 8S, 9S, the changeover switch 10S, and the charging switch 24. For convenience, in Figure 1, the signal lines for transmitting drive signals from the control unit 15 to each switching element are omitted.

[0050] <Star connection drive and open connection drive> Next, star-connection drive and open-connection drive will be described based on Figures 2, 3, and 4. Figure 2 shows an example of an operating point map of a rotating electric machine with rotational speed on the horizontal axis and torque on the vertical axis. Figure 3 shows a star-connection drive. Figure 4 shows an open-connection drive. For convenience, the control unit 15 is omitted in Figures 3 and 4.

[0051] As shown in Figure 2, the drive range of the rotating electric machine 3 is divided into two ranges based on rotational speed and torque. One of the drive ranges is the star connection drive range. The star connection drive range is the normal operating range. The other drive range is the open connection drive range. The open connection drive range is a range with higher rotational speed or higher torque than the star connection drive range.

[0052] When the operating point is in the star-connection drive region, the control unit 15 performs star-connection drive control. In star-connection drive, the rotating electric machine 3 is driven with windings 3U, 3V, and 3W connected in a star configuration. The control unit 15 controls the arm switches 8S, 9S and the changeover switch 10S so that windings 3U, 3V, and 3W are in a star-connection state. Specifically, as shown in Figure 3, the control unit 15 turns on all the changeover switches 10S to put the switching circuit 10 into a neutral state. It also turns off all the second arm switches 9S. Then, it controls the first arm switch 8S of the first inverter 8 according to the drive request, etc.

[0053] Figure 3 shows one of the energizing patterns in a star connection drive. The dashed arrows in Figure 3 show an example of a current path. In Figure 3, the current path is shown when the first arm switch 8S of the U-phase upper arm 8H and the first arm switch 8S of the W-phase lower arm 8L are turned ON. The current flows in the following order: U-phase upper arm 8H → node U1 → U-phase winding 3U → U-phase changeover switch 10S → changeover connection point 12 → W-phase changeover switch 10S → W-phase winding 3W → node W1 → W-phase lower arm 8L. Thus, in a star connection drive, current flows through the changeover circuit 10.

[0054] When the operating point is in the open-connection drive region, the control unit 15 performs open-connection drive control. In open-connection drive, the rotating electric machine 3 is driven with windings 3U, 3V, and 3W in an open connection state. The control unit 15 turns off all changeover switches 10S to open the changeover circuit 10. That is, the control unit 15 opens the neutral point of the changeover circuit 10. By opening the neutral point, open-connection circuits of the U-phase upper and lower arm circuits 8HL and 9HL are formed via the U-phase winding 3U. Similarly, open-connection circuits of the V-phase upper and lower arm circuits 8HL and 9HL are formed via the V-phase winding 3V. Open-connection circuits of the W-phase upper and lower arm circuits 8HL and 9HL are formed via the W-phase winding 3W. The control unit 15 considers each phase as an independent open-connection circuit and controls the applied voltage for each phase.

[0055] Figure 4 shows one of the energizing patterns in open-connection drive. The dashed arrows in Figure 4 show an example of a current path. In Figure 4, the current path is shown when the first arm switch 8S of the W-phase lower arm 8L and the second arm switch 9S of the W-phase upper arm 9H are turned ON. The current flows in the following order: W-phase upper arm 9H → node W2 → W-phase winding 3W → node W1 → W-phase lower arm 8L. In this way, in open-connection drive, current flows without going through the changeover switch 10S.

[0056] As described above, the power conversion circuit 4 is configured to be switchable between star connection drive and open connection drive. The power conversion circuit 4 is configured to perform star connection drive. The power conversion circuit 4 is configured to perform open connection drive. By performing open connection drive instead of star connection drive, it is possible to output in a higher rotational speed range or a higher torque range.

[0057] <Charging using a power conversion circuit> Next, charging using the power conversion circuit 4 will be explained based on Figure 5. Figure 5 shows a circuit configuration with external devices connected. In Figure 5, the external devices are shown in a simplified manner.

[0058] As shown in Figure 5, the external device 16 is connected to the charging terminal 23. The external device 16 is connected to the DC power supply 2 via the power conversion circuit 4. The external device 16 is a separate element from the elements that make up the drive system 1. For example, the external device 16 is an AC power supply. Examples of AC power supplies include household power, commercial power, and charging devices. The AC power supply can supply AC power to the power conversion circuit 4. The external device 16 can charge the DC power supply 2 with AC power via the power conversion circuit 4. The power conversion circuit 4 can function as an AC-DC converter. The power conversion circuit 4 converts the AC power from the external device 16 into DC power.

[0059] The control unit 15 performs power conversion control, which is the control of the power conversion circuit 4. Power conversion control includes rotation control and charging control. Rotation control is the control for driving the rotating electric machine 3. Rotation control includes star control and open control. In star control, the inverters 8, 9 and the switching circuit 10 are controlled so that the rotating electric machine 3 is driven in a star connection. In open control, the inverters 8, 9 and the switching circuit 10 are controlled so that the rotating electric machine 3 is driven in an open connection. Charging control is the control for charging the DC power supply 2 by an external device 16.

[0060] The control unit 15 performs power conversion control through power conversion control processing. The control unit 15 repeatedly executes power conversion control processing at predetermined intervals. The control unit 15 has the function of executing each step of the power conversion control processing. The power conversion control processing will be explained with reference to the flowchart in Figure 6.

[0061] In step S101 shown in Figure 6, the control unit 15 determines whether or not to perform rotational control. For example, when the vehicle is running, the control unit 15 decides to perform rotational control in order to drive the rotating electric machine 3. If rotational control is to be performed, the control unit 15 proceeds to step S108 and performs rotational control. As rotational control, the control unit 15 performs star control, open control, etc., depending on the drive range of the rotating electric machine 3.

[0062] If rotation control is not performed, the control unit 15 proceeds to step S102. In step S102, the control unit 15 determines whether or not to charge the DC power supply 2. For example, the control unit 15 determines whether or not the vehicle is stopped moving, and whether or not an external device 16 is connected to the charging terminal 23. If the vehicle is stopped moving and an external device 16 is connected to the charging terminal 23, the control unit 15 determines to charge the DC power supply 2.

[0063] When charging the DC power supply 2, the control unit 15 performs charge control processing in steps S103 to S105. In the charge control processing, the power conversion circuit 4 is controlled so that the external device 16 charges the DC power supply 2. The control unit 15 drives the power conversion circuit 4 so that it functions as an AC-DC converter. The power conversion circuit 4 is driven to rectify the AC current from the external device 16 into DC current. The function in the control unit 15 that performs the processing in steps S103 to S105 corresponds to the bridgeless control unit.

[0064] In step S103 of the charge control process, the control unit 15 turns on the semi-switch 22. The control unit 15 closes the semi-switch 22 by switching it from an open state to a closed state, etc. In step S104, the control unit 15 turns on the charge switch 24. The control unit 15 closes the charge switch 24 by switching it from an open state to a closed state, etc.

[0065] In step S105, the control unit 15 performs a charging process. During the charging process, the inverters 8 and 9 and the switching circuit 10 are controlled so that the external device 16 charges the DC power supply 2. The control unit 15 drives the power conversion circuit 4, which functions as an AC-DC converter, to form a semi-bridgeless PFC 20. The semi-bridgeless PFC 20 is a semi-bridgeless type power factor correction circuit. PFC stands for Power Factor Correction. The semi-bridgeless PFC 20 is a type of bridgeless power factor correction circuit. A bridgeless type power factor correction circuit is sometimes called a bridgeless PFC. The semi-switch 22 corresponds to a bridgeless component.

[0066] As shown in Figures 7 to 10, the semi-bridgeless PFC 20 is formed by including windings 3U, 3V, and 3W, a smoothing capacitor 7, a first inverter 8, a switching circuit 10, and a semi-switch 22. In the semi-bridgeless PFC 20, windings 3U, 3V, and 3W function as reactors for temporarily storing electrical energy. Current for storing energy in windings 3U, 3V, and 3W, and current for supplying energy from windings 3U, 3V, and 3W to the smoothing capacitor 7, flows through the first arm switch 8S and diode 8D. The switching diode 10D connects the power line 6 and the second output line 14, thereby fixing the potential of the second output line 14 to the potential of the power line 6.

[0067] For example, if the AC voltage of the external device 16 is a positive voltage, the control unit 15 turns off the second inverter 9 and opens the switching circuit 10, driving the first inverter 8 so that current flows to store energy in windings 3U, 3V, and 3W. In this case, as shown in Figure 7, for example, the current from the external device 16 flows in the order of V-phase winding 3V → V-phase lower arm 8L → W-phase lower arm 8L → W-phase winding 3W. In this way, energy is stored in the V-phase winding 3V by the current from the external device 16. The control unit 15 turns on the first arm switch 8S at the V-phase lower arm 8L. The control unit 15 may or may not turn on the first arm switch 8S at the W-phase lower arm 8L.

[0068] After energy is stored in windings 3U, 3V, and 3W by a positive voltage, the control unit 15 drives the first inverter 8 so that the energy from windings 3U, 3V, and 3W is supplied to the smoothing capacitor 7. In this case, for example as shown in Figure 8, the current from the V-phase winding 3V flows in the following order: V-phase upper arm 8H → smoothing capacitor 7 → W-phase lower arm 8L → W-phase winding 3W. In this way, the smoothing capacitor 7 is charged by the energy stored in the V-phase winding 3V. The control unit 15 may or may not turn on the first arm switch 8S at the V-phase upper arm 8H and the W-phase lower arm 8L.

[0069] When the smoothing capacitor 7 is charged, the control unit 15 drives the first inverter 8 so that current flows to store energy in the windings 3U, 3V, and 3W, thereby charging the DC power supply 2 by discharging the smoothing capacitor 7. For example, as shown in Figure 7, current flows from the smoothing capacitor 7 to the DC power supply 2. In this case, since the power line 6 and the W-phase second output line 14 are conductive via the semi-switch 22 and the switching diode 10D, the negative terminal potential of the DC power supply 2 and the lowest potential of the AC voltage from the external equipment 16 are fixed, which makes it easier to improve EMI in the power converter 4. EMI stands for Electro-Magnetic Interference.

[0070] Furthermore, if the AC voltage of the external device 16 is a negative voltage, the control unit 15 drives the first inverter 8 so that current flows to store energy in the windings 3U, 3V, and 3W. In this case, for example as shown in Figure 9, the current from the external device 16 flows in the order of W-phase winding 3W → W-phase lower arm 8L → V-phase lower arm 8L → V-phase winding 3V. In this way, energy is stored in the W-phase winding 3W by the current from the external device 16. The control unit 15 turns on the first arm switch 8S at the W-phase lower arm 8L. The control unit 15 may or may not turn on the first arm switch 8S at the V-phase lower arm 8L.

[0071] After energy is stored in windings 3U, 3V, and 3W due to a negative voltage, the control unit 15 drives the first inverter 8 so that the energy from windings 3U, 3V, and 3W is supplied to the smoothing capacitor 7. In this case, for example as shown in Figure 10, the current from the W-phase winding 3W flows in the following order: W-phase upper arm 8H → smoothing capacitor 7 → V-phase lower arm 8L → V-phase winding 3V. In this way, the smoothing capacitor 7 is charged by the energy stored in the W-phase winding 3W. The control unit 15 may or may not turn on the first arm switch 8S at the W-phase upper arm 8H and the V-phase lower arm 8L.

[0072] When the smoothing capacitor 7 is charged by a negative voltage, the DC power supply 2 is charged by the discharge of the smoothing capacitor 7, just as when the smoothing capacitor 7 is charged by a positive voltage. For example, as shown in Figure 9, current flows from the smoothing capacitor 7 to the DC power supply 2. In this case, since the power line 6 and the V-phase second output line 14 are conducted via the semi-switch 22 and the switching diode 10D, the negative terminal potential of the DC power supply 2 and the lowest potential of the AC voltage from the external device 16 are fixed, which makes it easier to improve EMI in the power converter 4.

[0073] Returning to Figure 6, in step S102, if the DC power supply 2 is not charged, the control unit 15 proceeds to step S106 and turns off the semi-switch 22. The control unit 15 turns off the semi-switch 22 by switching it from the closed state to the open state, etc. In step S107, the control unit 15 turns off the charging switch 24. The control unit 15 turns off the charging switch 24 by switching it from the closed state to the open state, etc.

[0074] <Summary of the First Embodiment> According to this embodiment, the semi-switch 22 forms a bridgeless PFC together with at least one of the first inverter 8, the second inverter 9, and the switching circuit 10. In this configuration, when an external device 16 is connected to the charging terminal 23, the power factor of the power converted from AC power to DC power is easily improved by the bridgeless PFC. Therefore, the charging efficiency of the DC power supply 2 by the external device 16 can be increased.

[0075] According to this embodiment, the semi-switch 22 is a switch capable of conducting and disconnecting the power line 6 and the switching circuit 10, forming a semi-bridgeless PFC 20. In the semi-bridgeless PFC 20, the potential of the second output line 14 is fixed to the potential of the power line 6 via the switching diode 10D and the semi-switch 22. Therefore, the semi-switch 22 can improve EMI. For example, the semi-switch 22 can improve EMC performance. EMC stands for Electro-Magnetic Compatibility.

[0076] According to this embodiment, the semi-switch 22 is connected to the second output line 14 via the switching circuit 10 so as to form a semi-bridgeless PFC 20 together with the first inverter 8 of the first inverter 8 and the second inverter 9. In this configuration, the semi-bridgeless PFC 20 can be formed by including the first arm switch 8S, which has smaller switching losses among the first arm switch 8S and the second arm switch 9S. Therefore, losses that occur in conjunction with driving the semi-bridgeless PFC 20 can be reduced.

[0077] According to this embodiment, the semi-switch 22 is connected to windings 3U, 3V, and 3W via the switching circuit 10 so that windings 3U, 3V, and 3W become the reactance of the semi-bridgeless PFC 20. In this configuration, windings 3U, 3V, and 3W can be used as reactors for the semi-bridgeless PFC 20. Therefore, it is not necessary to provide a dedicated reactor for the semi-bridgeless PFC 20 in the power conversion circuit 4. Consequently, the power conversion circuit 4 can be made smaller and lighter.

[0078] In the semi-bridgeless PFC20, the larger the inductance of winding 3U, 3V, 3W, the greater the electrical energy stored in winding 3U, 3V, 3W when charging the DC power supply 2. In large rotating electric machines 3, the inductance of winding 3U, 3V, 3W tends to be large. Also, in large rotating electric machines 3, the capacitance to ground of power conversion circuits 4 and other components tends to be large. For this reason, in large rotating electric machines 3, when connecting external equipment 16 to the charging terminal 23, the touch current increases, raising concerns that the energy stored in winding 3U, 3V, 3W and power conversion circuit 4 may reduce worker safety.

[0079] Therefore, in this embodiment, it is preferable to use a semi-bridgeless PFC 20 for the power conversion circuit 4 for driving a relatively small rotating electric machine 3. In a relatively small rotating electric machine 3, the inductance of the windings 3U, 3V, 3W tends to be small, and the capacitance to ground of the power conversion circuit 4 tends to be small. As a result, the energy stored in the windings 3U, 3V, 3W and the power conversion circuit 4 tends to be small. Consequently, the safety level for the worker can be increased when charging the DC power supply 2. An example of a relatively small rotating electric machine 3 is a motor for a compressor.

[0080] According to this embodiment, the control unit 15 controls the semi-switch 22, inverters 8 and 9, and the switching circuit 10 so that the semi-switch 22 forms a bridgeless PFC together with the inverters 8 and 9 and the switching circuit 10. In this configuration, the control unit 15 performs a charging process, which increases the charging efficiency of the DC power supply 2 by the external device 16.

[0081] (Second Embodiment) This embodiment is a modification based on a prior embodiment, and the description of the prior embodiment can be applied by reference. In the prior embodiment, a semi-bridgeless type was used as the power factor correction circuit, but it is not limited to this. In this embodiment, a totem-pole bridgeless type may be used as the power factor correction circuit.

[0082] <Power Conversion Circuit> Figure 11 shows a power conversion circuit 4 according to this embodiment. The power conversion circuit 4 shown in Figure 11 has a charging coil 31, a charging terminal 33, a charging switch 34, and a charging line 35. The charging terminal 33, charging switch 34, and charging line 35 have the same configuration as the charging terminal 23, charging switch 24, and charging line 25 of the first embodiment described above. However, the charging terminal 33 is connected to the first output line 13 via the charging line 35, etc. The charging terminal 33 is connected to the first output line 13 of two phases. For example, the charging terminal 33 is connected to the first output line 13 of the V phase and the W phase.

[0083] The charging coil 31 is a coil provided on the charging line 35. The charging coil 31 is sometimes referred to as a winding. The charging coil 31 is provided on the charging line 35 between the charging switch 24 and the first output line 13. The charging coil 31 is connected to one of the two phases of the first output line 13. For example, the charging coil 31 is connected to the W phase first output line 13. The inductance of the charging coil 31 is equal to or greater than the inductance of the winding 3U, 3V, 3W. For example, the inductance of the winding 3U, 3V, 3W is 100μH to 400μH. In contrast, the inductance of the charging coil 31 is 200μH to 1mH.

[0084] <Charging using a power conversion circuit> As shown in Figure 12, the external device 16 is connected to the charging terminal 33. The control unit 15 performs power conversion control processing, similar to the first embodiment described above. The power conversion control processing will be explained with reference to the flowchart in Figure 13.

[0085] In steps S201 to S203, S205, and S206 shown in Figure 13, the control unit 15 performs the same processing as in steps S101, S102, S104, S107, and S108 of the first embodiment. However, in the rotation control in step S206, the control unit 15 drives the arm switches 8S and 9S in a high-frequency band. For example, in rotation control, the arm switches 8S and 9S are driven in a high-frequency band including 10kHz.

[0086] In step S202, when charging the DC power supply 2, the control unit 15 performs charge control processing in steps S203 and S204, similar to steps S103 to S105 of the first embodiment described above. The function in the control unit 15 that performs the processing in steps S203 and S204 corresponds to the bridgeless control unit.

[0087] The control unit 15 turns on the charging switch 34 in step S203 of the charging control process, and then performs the charging process in step S204. The control unit 15 drives the power conversion circuit 4, which functions as an AC-DC converter, to form a totem-pole bridgeless PFC 30. The totem-pole bridgeless PFC 30 is a totem-pole bridgeless type power factor correction circuit. The totem-pole bridgeless PFC 30 is a type of bridgeless power factor correction circuit. The charging coil 31 corresponds to a bridgeless component.

[0088] The control unit 15 drives the arm switches 8S and 9S in a low-frequency band during the charging process. The low-frequency band is a frequency band lower than the high-frequency band used for rotation control. For example, during the charging process, the arm switches 8S and 9S are driven in a low-frequency band that includes 60Hz.

[0089] As shown in Figures 14 to 17, the totem-pole bridgeless PFC 30 is formed by including windings 3U, 3V, and 3W, a smoothing capacitor 7, a first inverter 8, a switching circuit 10, and a charging coil 31. In the totem-pole bridgeless PFC 30, the charging coil 31 stores electrical energy. The charging coil 31 functions as a reactor in the totem-pole bridgeless PFC 30. The charging coil 31 corresponds to a totem-pole reactor. Current for storing energy in the charging coil 31 and current for supplying energy from the charging coil 31 to the smoothing capacitor 7 flow through the first arm switch 8S and the diode 8D.

[0090] For example, if the AC voltage of the external device 16 is a positive voltage, the control unit 15 turns off the second inverter 9 and drives the first inverter 8 so that a current flows to store energy in the charging coil 31. In this case, as shown in Figure 14, for example, the current from the external device 16 flows in the order of charging coil 31 → W-phase lower arm 8L → V-phase lower arm 8L. In this way, energy is stored in the charging coil 31 by the current from the external device 16. The control unit 15 turns on the first arm switch 8S at the W-phase lower arm 8L. The control unit 15 may or may not turn on the first arm switch 8S at the V-phase lower arm 8L.

[0091] After energy is stored in the charging coil 31 by a positive voltage, the control unit 15 drives the first inverter 8 so that the energy from the charging coil 31 is supplied to the smoothing capacitor 7. In this case, for example as shown in Figure 15, the current from the charging coil 31 flows in the order of W-phase upper arm 8H → smoothing capacitor 7 → V-phase lower arm 8L. In this way, the smoothing capacitor 7 is charged by the energy stored in the charging coil 31. The control unit 15 may or may not turn on the first arm switch 8S at the W-phase upper arm 8H and the V-phase lower arm 8L.

[0092] When the smoothing capacitor 7 is charged, the control unit 15 drives the first inverter 8 so that a current flows through the charging coil 31 to store energy, thereby charging the DC power supply 2 through the discharge of the smoothing capacitor 7. For example, as shown in Figure 14, current flows from the smoothing capacitor 7 to the DC power supply 2.

[0093] Furthermore, if the AC voltage of the external device 16 is a negative voltage, the control unit 15 drives the first inverter 8 so that a current flows to store energy in the charging coil 31. In this case, for example, as shown in Figure 16, the current from the external device 16 flows in the order of charging coil 31 → W-phase upper arm 8H → V-phase upper arm 8H. In this way, energy is stored in the charging coil 31 by the current from the external device 16. The control unit 15 turns on the first arm switch 8S at the V-phase upper arm 8H. The control unit 15 may or may not turn on the first arm switch 8S at the W-phase upper arm 8H.

[0094] After energy is stored in the charging coil 31 by a negative voltage, the control unit 15 drives the first inverter 8 so that the energy from the charging coil 31 is supplied to the smoothing capacitor 7. In this case, for example as shown in Figure 17, the current from the charging coil 31 flows in the order of V-phase upper arm 8H → smoothing capacitor 7 → W-phase lower arm 8L. In this way, the smoothing capacitor 7 is charged by the energy stored in the charging coil 31. The control unit 15 may or may not turn on the first arm switch 8S at the V-phase upper arm 8H and the W-phase lower arm 8L.

[0095] When the smoothing capacitor 7 is charged by a negative voltage, the DC power supply 2 is charged by the discharge of the smoothing capacitor 7, just as when the smoothing capacitor 7 is charged by a positive voltage. For example, as shown in Figure 16, current flows from the smoothing capacitor 7 to the DC power supply 2.

[0096] Returning to Figure 6, if the DC power supply 2 is not charged in step S202, the control unit 15 proceeds to step S205 and turns off the charging switch 24.

[0097] <Summary of the First Embodiment> According to this embodiment, the charging coil 31 is a reactor that connects the first output line 13 and the charging terminal 23, forming a totem pole bridgeless PFC 30. In the totem pole bridgeless PFC 30, the charging coil 31 functions as a dedicated reactor for temporarily storing energy when charging the DC power supply 2. For this reason, a reactor with specifications that increase the charging efficiency of the DC power supply 2 by the power conversion circuit 4 can be used as the charging coil 31.

[0098] According to this embodiment, the charging coil 31 is connected to the first output line 13 so as to form a totem pole bridgeless PFC 30 together with the first inverter 8 of the first inverter 8 and the second inverter 9. In this configuration, the totem pole bridgeless PFC 30 can be formed by including the first arm switch 8S, which has smaller switching losses than the first arm switch 8S and the second arm switch 9S. Therefore, losses incurred in driving the totem pole bridgeless PFC 30 can be reduced. Consequently, even if efficiency is required for charging the DC power supply 2 with AC power, the DC power supply 2 can be charged with high efficiency by forming the totem pole bridgeless PFC 30 including the first arm switch 8S.

[0099] (Other embodiments) The disclosures in this specification and drawings are not limited to the exemplary embodiments. The disclosures include the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to combinations of parts and / or elements shown in the embodiments. The disclosures are implementable in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures include those in which parts and / or elements of the embodiments have been omitted. The disclosures include substitutions or combinations of parts and / or elements between one embodiment and another. The scope of the disclosed technical areas is not limited to the descriptions of the embodiments. Some of the scope of the disclosed technical areas are indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0100] The disclosures in the specification and drawings are not limited by the claims. The disclosures in the specification and drawings encompass the technical ideas described in the claims and extend to a wider and more diverse range of technical ideas than those described in the claims. Therefore, a variety of technical ideas can be extracted from the disclosures in the specification and drawings without being bound by the claims.

[0101] When an element or layer is referred to as "on top of," "connected," "linked," or "joined," it may be directly on top of, connected to, or joined to another element or layer, and there may also be intervening elements or layers. In contrast, when an element is referred to as "directly on top of," "directly connected," "directly linked," or "directly joined" to another element or layer, there is no intervening element or layer. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.).

[0102] As used in this specification, the term "and / or" includes any combination and all combinations relating to one or more of the enumerated items relating to the relevant item. That is, the statement A and / or B means at least one of A and B, and may include A only, B only, or both A and B.

[0103] Spatially relative terms such as "inside," "outside," "back," "below," "low," "above," and "high" are used here to facilitate descriptions of the relationship between one element or feature and other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawing is turned upside down, an element described as "below" or "directly below" another element or feature will be oriented "above" the other element or feature. Thus, the term "below" can encompass both up and down orientations. The device may also be oriented in other directions (it may be rotated 90 degrees or in other directions), and the spatially relative descriptors used in this specification will be interpreted accordingly.

[0104] In each of the above embodiments, bridgeless components such as the semi-switch 22 and the charging coil 31 may be connected to either the first output line 13 or the second output line 14. That is, the bridgeless PFC may be formed by including either the first inverter 8 or the second inverter 9. For example, in the first embodiment, the switching circuit 10 and the semi-switch 22 may be connected to the first output line 13. That is, the semi-bridgeless PFC 20 may be formed by including the second inverter 9. Also, in the second embodiment, the charging coil 31 and the charging terminal 23 may be connected to the second output line 14. That is, the totem pole bridgeless PFC 30 may be formed by including the second inverter 9.

[0105] In each of the above embodiments, the switching circuit 10 does not need to have a switching diode 10D, as long as it has a switching switch 10S. For example, in the first embodiment, in the semi-bridgeless PFC 20 formed including the switching circuit 10, the potential of the second output line 14 does not need to be fixed to the potential of the power line 6. In this configuration, the bridgeless PFC is formed including the switching circuit 10 and the semi-switch 22.

[0106] In each of the above embodiments, the switches 8S, 9S, 10S, and 22 can have any configuration as long as they are switches capable of interrupting the current. For example, the first arm switch 8S and the second arm switch 9S may be of the same type of switching element. Also, the switching loss of the second arm switch 9S may be less than the switching loss of the first arm switch 8S. Furthermore, the changeover switch 10S may be of the same type of switching element as at least one of the first arm switch 8S and the second arm switch 9S, or it may be a different type of switching element from at least one of them. (Disclosure of technical ideas) This specification discloses several technical concepts, as described in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts. (Technical thought 1) A power converter (4) that converts the power supplied from a DC power source (2) to a rotating electric machine (3), A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between a star connection and an open connection, A charging connection section (23) to which an AC power supply (16) for charging the DC power supply is connected, With the AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), A power converter equipped with the following features. (Technical thought 2) The aforementioned bridgeless component is The power conversion device according to technical concept 1, comprising a switch capable of conducting and disconnecting the negative electrode path (6) connected to the negative electrode of the DC power supply and the switching circuit, and a semi-switch (22) that forms a semi-bridgeless power factor correction circuit as the bridgeless power factor correction circuit. (Technical Thought 3) The second inverter is connected to the DC power supply via the first inverter, The power conversion device according to technical concept 2, wherein the semi-switch is connected to the second path via the switching circuit so as to form the semi-bridgeless power factor correction circuit together with the first inverter, which is one of the first inverters. (Technical Thought 4) The power conversion device according to technical concept 2 or 3, wherein the semi-switch is connected to the winding via the switching circuit such that the winding becomes the reactance of the semi-bridgeless power factor correction circuit. (Technical Thought 5) The aforementioned bridgeless component is The power conversion device according to technical concept 1, comprising a reactor connecting one of the first path and the second path to the charging connection part, the totem pole reactor (31) forming a totem pole bridgeless type power factor correction circuit as the bridgeless type power factor correction circuit. (Technical Thought 6) The second inverter is connected to the DC power supply via the first inverter, The power conversion device according to technical concept 5, wherein the totem pole reactor is connected to the first path so as to form the totem pole bridgeless type power factor correction circuit together with the first inverter. (Technical Thought 7) The power conversion device according to technical concept 5 or 6, wherein the loss caused by driving the first switch (8S) of the first inverter is less than the loss caused by driving the second switch (9S) of the second inverter. (Technical Thought 8) A power conversion device according to any one of technical ideas 1 to 7, comprising a bridgeless control unit (S103 to S105) that controls the bridgeless component, the first inverter, the second inverter, and at least one of the switching circuit, such that the bridgeless component forms the bridgeless type power factor correction circuit together with at least one of the first inverter, the second inverter, and the switching circuit. (Technical Thought 9) Rotating electric machine (3) and A power converter (4) that converts the power supplied from a DC power source (2) to the rotating electric machine, A drive system (1) comprising the power converter, which drives the rotating electric machine, A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between a star connection and an open connection, A charging connection section (23) to which an AC power supply (16) for charging the DC power supply is connected, With the AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), A drive system equipped with this feature. [Explanation of Symbols]

[0107] 1…Drive system, 2…DC power supply, 3…Rotating electric machine, 3U,3V,3W…Winding, 4…Power conversion circuit, 6…Power line, 8…First inverter, 8S…First arm switch, 9…Second inverter, 9S…Second arm switch, 10…Switching circuit, 13…First output line, 14…Second output line, 16…AC power supply, 20…Semi-bridgeless PFC, 22…Semi-switch, 23…Charging terminal, 30…Totem pole bridgeless PFC, 31…Charging coil.

Claims

1. A power converter (4) that converts the power supplied from a DC power source (2) to a rotating electric machine (3), A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between star connection and open connection, A charging connection section (23) to which an AC power supply (16) for charging the DC power supply is connected, With the AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), A power converter equipped with the following features.

2. The aforementioned bridgeless component is The power conversion device according to claim 1, comprising a switch capable of conducting and disconnecting the negative electrode path (6) connected to the negative electrode of the DC power supply and the switching circuit, the switch (22) forming a semi-bridgeless power factor correction circuit as the bridgeless power factor correction circuit.

3. The second inverter is connected to the DC power supply via the first inverter. The power conversion device according to claim 2, wherein the semi-switch is connected to the second path via the switching circuit so as to form the semi-bridgeless power factor correction circuit together with the first inverter among the first and second inverters.

4. The power conversion device according to claim 2 or 3, wherein the semi-switch is connected to the winding via the switching circuit such that the winding becomes the reactance of the semi-bridgeless power factor correction circuit.

5. The aforementioned bridgeless component is The power conversion device according to claim 1, comprising a reactor connecting one of the first path and the second path to the charging connection part, the totem pole reactor (31) forming a totem pole bridgeless type power factor correction circuit as the bridgeless type power factor correction circuit.

6. The second inverter is connected to the DC power supply via the first inverter. The power converter according to claim 5, wherein the totem pole reactor is connected to the first path so as to form the totem pole bridgeless type power factor correction circuit together with the first inverter.

7. The power conversion device according to claim 5 or 6, wherein the loss caused by driving the first switch (8S) of the first inverter is smaller than the loss caused by driving the second switch (9S) of the second inverter.

8. The power conversion device according to any one of claims 1, 2, or 5, further comprising a bridgeless control unit (S103 to S105) that controls the bridgeless component, the first inverter, the second inverter, and at least one of the switching circuit, such that the bridgeless component forms the bridgeless type power factor correction circuit together with the first inverter, the second inverter, and at least one of the switching circuit.

9. Rotating electric machine (3) and A power converter (4) that converts the power supplied from the DC power source (2) to the rotating electric machine, A drive system (1) comprising the power converter that drives the rotating electric machine, A first inverter (8) is connected to one end of the winding of the rotating electric machine via a first path (13), A second inverter (9) is connected to the other end of the winding via a second path (14), A switching circuit (10) that can switch the winding connection between star connection and open connection, A charging connection section (23) to which an AC power supply (16) for charging the DC power supply is connected, With the AC power supply connected to the charging connection, bridgeless components (22, 31) together with the first inverter, the second inverter, and at least one of the switching circuits form a bridgeless type power factor correction circuit (20, 30), A drive system equipped with this feature.

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