Rotary electric machine controller

Abstract

To quickly discharge multiple DC link capacitors which smooth the DC voltages of multiple inverters used to control drive of an open-winding type rotary electric machine, while keeping the circuit size from becoming large.SOLUTION: A rotary electric machine controller releases a first contact S1 and a second contact S2 and connects a third contact S3 in a rapid discharge control of flowing a current to a rapid discharge resistor R3 and performs switching control on the second inverter 2 in a motoring mode of providing electric power to a rotary electric machine 80 and performs switching control on the first inverter 1 in a regenerative mode of receiving electric power from the rotary electric machine 80. Also, charges of a first current link capacitor C1 and a second current link capacitor C2 are discharged by a rapid discharge resistor R3.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine control device that drives and controls a rotating electrical machine having a multi-phase open winding via a first inverter and a second inverter.

Background Art

[0002] Japanese Patent Laid-Open No. 2016-86578 discloses a motor drive system (9) including a DC power supply (10), an AC rotating electrical machine (8), and an inverter (7) that converts power between DC and AC (reference numerals in parentheses in the background art refer to those in the cited document). The DC side of the inverter (7) and the DC power supply (10) are connected via a contactor (12), and the electrical connection between the inverter (7) and the DC power supply (10) can be interrupted by opening the contactor (12). A DC link capacitor (13) that smoothes the voltage on the DC side of the inverter (7) is provided between the contactor (12) and the inverter (7). Even when the contactor (12) is opened while the inverter (7) is operating, charges accumulate in the DC link capacitor (13). For example, even when the electrical connection to the high-voltage DC power supply (10) is interrupted, a relatively high voltage continues to be applied to the DC side of the inverter (7) until the DC link capacitor (13) discharges.

[0003] Therefore, a discharge circuit is provided in parallel with the DC link capacitor (7) to quickly discharge the residual charge of the DC link capacitor (13). The discharge circuit is composed of a series circuit of a discharge resistor (50) and a switching element (55). When the switching element (55) is controlled to be in the on state, the positive and negative sides of the DC link capacitor (13) are connected via the discharge resistor (50), and the residual charge flows through the discharge resistor (50) and is converted into heat and consumed. To quickly discharge the residual charge, the resistance value of the discharge resistor (50) is relatively small, and the value of the current flowing through the discharge circuit is large. For this reason, the switching element (50) and the discharge resistor (50) often have a relatively large size.

[0004] Japanese Patent Application Laid-Open No. 2018-196177 discloses a rotating electrical machine control device that drives and controls a rotating electrical machine (40) having a multi-phase open winding (41U, 41V, 41W) via a first inverter (20) and a second inverter (30). A first DC power supply (10) is connected to the first inverter (20) via first contactors (SMR1, SMR2), and a second DC power supply (42) is connected to the second inverter (30) via second contactors (SMR3, SMR4). Further, a first DC link capacitor (51) is provided on the DC side of the first inverter (20), and a second DC link capacitor (52) is provided on the DC side of the second inverter (30).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a system for driving an open-winding rotating electrical machine as disclosed in Japanese Patent Application Laid-Open No. 2018-196177, a plurality of DC link capacitors are also provided. For this reason, it is necessary to provide a plurality of discharge circuits for discharging the DC link capacitors as in the system disclosed in Japanese Patent Application Laid-Open No. 2016-86578. As described above, since the value of the current flowing through the discharge circuit is relatively large, the circuit elements constituting the discharge circuit are likely to have a relatively large physical size, which easily leads to an increase in the size of the circuit and an increase in cost.

[0007] In view of the above, it is desirable to provide a technique for quickly discharging a plurality of DC link capacitors that smooth the voltages on the DC sides of a plurality of inverters that drive and control an open-winding type rotating electrical machine while suppressing an increase in circuit scale.

Means for Solving the Problems

[0008] A rotating electrical machine control device that drives and controls a rotating electrical machine having a plurality of open windings of a plurality of phases via a first inverter and a second inverter, in view of the above, is such that the first inverter is connected to a first DC power supply via a first contactor, the second inverter is connected to a second DC power supply electrically independent of the first DC power supply via a second contactor, a first DC link capacitor that smoothes the voltage on the DC side of the first inverter is connected between the first contactor and the first inverter, a second DC link capacitor that smoothes the voltage on the DC side of the second inverter is connected between the second contactor and the second inverter, a rapid discharge circuit in which a rapid discharge resistor and a third contactor are connected in series is further connected in parallel to the first DC link capacitor, the first inverter and the second inverter each have a leg for one phase of alternating current configured by a series circuit of an upper switching element and a lower switching element, the first inverter is connected to the first DC power supply and one end side of the plurality of open windings of a plurality of phases and converts power between DC on the side of the first DC power supply and alternating current of a plurality of phases, the second inverter is connected to the second DC power supply and the other end side of the plurality of open windings of a plurality of phases and converts power between DC on the side of the second DC power supply and alternating current of a plurality of phases, the rotating electrical machine control device can control each of the first inverter and the second inverter independently of each other, and in the rapid discharge control for flowing a current through the rapid discharge resistor, the first contactor and the second contactor are opened and the third contactor is connected, and while switching control is performed on the second inverter in the power running mode for supplying power to the rotating electrical machine, switching control is performed on the first inverter in the regeneration mode for receiving power from the rotating electrical machine, and the charges of the first DC link capacitor and the second DC link capacitor are discharged by the rapid discharge resistor.

[0009] According to this configuration, both the first DC link capacitor and the second DC link capacitor can be discharged using one rapid discharge circuit connected in parallel to the first DC link capacitor. Since only one rapid discharge circuit through which a large current flows is provided for the two DC link capacitors, an increase in the circuit scale can be suppressed. That is, according to this configuration, while suppressing an increase in the circuit scale, a plurality of DC link capacitors that smooth the voltage on the DC side of each of a plurality of inverters for driving and controlling an open-wound rotating electrical machine can be rapidly discharged. That is, according to this configuration, while suppressing an increase in the circuit scale, a plurality of DC link capacitors that smooth the voltage on the DC side of each of a plurality of inverters for driving and controlling an open-wound rotating electrical machine can be rapidly discharged.

[0010] Further features and advantages of the rotating electrical machine control device will become clear from the following description of exemplary and non-limiting embodiments with reference to the drawings.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of a rotating electrical machine control device that drives and controls a rotating electrical machine having a multi-phase open winding will be described with reference to the drawings. FIG. 1 is a schematic circuit block diagram of a rotating electrical machine drive system 100 including a rotating electrical machine control device 10. The rotating electrical machine 80 to be driven is, for example, a driving power source for wheels in a vehicle such as an electric vehicle or a hybrid vehicle. The rotating electrical machine 80 is an interior permanent magnet synchronous motor (IPMSM) having a stator in which a plurality of phase (N-phase where N is an arbitrary natural number, and in this embodiment, a three-phase form with N = 3 is exemplified) stator coils 8 are arranged, and a rotor in which permanent magnets are arranged. In this embodiment, the rotating electrical machine 80 is an open-winding type rotating electrical machine having a plurality of phase (three-phase in this embodiment) stator coils 8 (open windings). Here, the open winding means that, for example, the windings of a plurality of phases are not physically connected to each other at the neutral point, and the windings of a plurality of phases are physically arranged independently of each other. Such a configuration is well-known, and in this embodiment, the illustration of the stator, rotor, permanent magnets, etc. is omitted. One inverter that is independently controlled and converts power between direct current and alternating current of a plurality of phases (here, three phases) is connected to each end of the stator coil 8. That is, the first inverter 1 is connected to one end side of the stator coil 8, and the second inverter 2 is connected to the other end side of the stator coil 8. Hereinafter, when it is not necessary to distinguish between the first inverter 1 and the second inverter 2, they will be simply referred to as inverters for explanation.

[0013] The inverter is configured to have a plurality of switching elements 5. As the switching element 5, an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a HEMT (High Electric Mobility Transistor), etc. are used. FIG. 1 exemplifies a form in which an IGBT is used as the switching element 5. In the present embodiment, the first inverter 1 and the second inverter 2 are inverters having the same circuit configuration using the same type of switching element 5.

[0014] Each of the two inverters has a leg for one-phase alternating current configured by a series circuit of an upper-stage switching element 51 and a lower-stage switching element 52. In each of the legs of multiple phases, the side including the upper-stage switching element 51 is referred to as the upper-stage arm, and the side including the lower-stage switching element 52 is referred to as the lower-stage arm. Also, each switching element 5 is provided with a freewheel diode in parallel with the direction from the negative electrode to the positive electrode (the direction from the lower stage to the upper stage) defined as the forward direction. Note that in the case of using a body diode or using the reverse conduction in a transistor of a wide bandgap semiconductor composed of enhancement-mode gallium nitride (E-GaN), such a form of freewheel diode may not be provided.

[0015] Also, in the present embodiment, the two inverters are each connected to an independent DC power supply. Therefore, the first floating ground, which is the negative electrode on the DC side of the first inverter 1, and the second floating ground, which is the negative electrode on the DC side of the second inverter 2, are independent of each other. Also, between the inverter and the DC power supply, a DC link capacitor (smoothing capacitor) for smoothing the DC voltage (DC link voltage) is provided respectively.

[0016] Specifically, the first inverter 1 has a first DC link capacitor C1 connected to smooth the first DC link voltage on the DC side, the DC side is connected to the first DC power supply 3, and the AC side is connected to one end side of a plurality of phase stator coils 8, and converts power between DC and a plurality of phases of AC. The second inverter 2 has a second DC link capacitor C2 connected to smooth the second DC link voltage on the DC side, the DC side is connected to the second DC power supply 4, and the AC side is connected to the other end side of a plurality of phase stator coils 8, and converts power between DC and a plurality of phases of AC.

[0017] The rated voltage of the DC power supply is from 48 volts to 800 volts, preferably about 200 to 800 volts. The DC power supply is composed of, for example, a secondary battery (battery) such as a nickel-metal hydride battery or a lithium-ion battery, or a power storage element such as an electric double layer capacitor.

[0018] Also, a first DC link voltage sensor 31 for detecting the first DC link voltage is provided on the DC side of the first inverter 1, and a second DC link voltage sensor 41 for detecting the second DC link voltage is provided on the DC side of the second inverter 2.

[0019] The DC power supply is connected to the inverter via a contactor so that the electrical connection with the inverter can be disconnected. Specifically, the first inverter 1 is connected to the first DC power supply 3 via a first contactor S1, and the second inverter 2 is connected to a second DC power supply 4 electrically independent of the first DC power supply 3 via a second contactor S2. The first contactor S1 and the second contactor S2 are, for example, relays, and are controlled to open and close by a rotating electrical machine control device 10 or a vehicle control device (not shown). Note that the relay may be a mechanical relay or a semiconductor relay (SSR: Solid State Relay).

[0020] The DC link capacitor is arranged on the inverter side with a contactor interposed therebetween, and is arranged so that the electrical connection with the DC power supply can be disconnected by opening and closing the contactor. On the other hand, the DC link capacitor is always connected to the inverter.

[0021] One of the DC power supplies is connected to an in-vehicle device 9 different from the rotating electrical machine 80 (including the inverter) via a contactor and supplies power to the in-vehicle device 9 as well. In the present embodiment, the first DC power supply 3 is connected to an in-vehicle device 9 (auxiliary machine 90, voltage converter 60, third DC power supply 6) different from the rotating electrical machine 80, the first inverter 1, and the second inverter 2 via the first contactor S1 and supplies power to the in-vehicle device 9.

[0022] The third DC power supply 6 is a DC power supply having a rated voltage lower than that of the first DC power supply 3 and the second DC power supply 4, for example, a DC power supply having a rated voltage of 12 volts or 24 volts. The third DC power supply 6 is, for example, an in-vehicle battery mounted on a vehicle having only a conventional internal combustion engine as a driving force source for wheels, and is a lead-acid battery. When distinguished by the rated voltage, the first DC power supply 3 and the second DC power supply 4 are high-voltage DC power supplies or high-voltage batteries, and the third DC power supply 6 is a low-voltage DC power supply or a low-voltage battery.

[0023] In a vehicle having a conventional internal combustion engine as a driving force source, the in-vehicle battery has been charged by power supplied from, for example, an alternator that generates electricity using a part of the power of the internal combustion engine. However, in a hybrid vehicle or an electric vehicle equipped with a rotating electrical machine as a driving force source for wheels, the above-described high-voltage battery is mounted. Therefore, the in-vehicle battery is charged by the power supplied from the high-voltage battery without mounting a generator such as an alternator. Also in the present embodiment, the third DC power supply 6 is supplied with power from the first DC power supply 3. However, as described above, since the rated voltage of the first DC power supply 3, which is a high-voltage battery, is higher than that of the third DC power supply 6, which is a low-voltage battery, the voltage is stepped down by the voltage converter 60 (step-down converter), and power is supplied from the first DC power supply 3 to the third DC power supply 6. The voltage converter 60 is a so-called DC / DC converter, and preferably an isolated DC / DC converter using a transformer in consideration of insulation from the first DC power supply 3.

[0024] When the rated voltages of the first DC power supply 3 and the second DC power supply 4 are approximately 200 to 400 volts, as shown in FIG. 1, the output voltage of the first DC power supply 3 may be directly provided to auxiliary machines 90 such as in-vehicle air conditioners and electric oil pumps. However, when the rated voltage of the first DC power supply 3 exceeds 40 volts, power may be supplied to the auxiliary machines 90 via a step-down converter in some cases. Therefore, the in-vehicle device 9 directly connected to the first DC power supply 3 may include only the voltage converter 60 without including the auxiliary machines 90, unlike the form illustrated in FIG. 1. Further, the voltage converter 60 is not limited to a form that outputs a single voltage, and may have a multi-port output configuration in which, for example, a plurality of coils are provided on the secondary side of a transformer to output a plurality of voltages (the voltage values may be the same).

[0025] As shown in FIG. 1, a first discharge resistor R1 and a rapid discharge circuit 7 are connected in parallel to the first DC link capacitor C1, and a second discharge resistor R2 is connected in parallel to the second DC link capacitor C2. The rapid discharge circuit 7 is constituted by a series circuit of a third discharge resistor R3 and a third contactor S3. The first discharge resistor R1 and the second discharge resistor R2 function as passive discharge resistors (for example, about several tens of kiloohms). The third discharge resistor R3 is an active discharge resistor that functions when the third contactor S3 is closed and connected, and is a so-called rapid discharge resistor. The resistance value of the third discharge resistor R3 is about 1 / 100 of that of the passive resistor, for example, about several hundreds to 1 kiloohm. The third contactor S3 may be a relay like the first contactor S1 and the second contactor S2, or may be a switching element such as a power transistor. The third contactor S3 is also controlled to be opened and closed by the rotating electrical machine control device 10 or a vehicle control device (not shown).

[0026] The passive discharge resistor is constantly connected to the DC side of the inverter and discharges the charge remaining in the DC link capacitor. Since the passive discharge resistor is constantly connected to the DC side of the inverter, it has a relatively large resistance value so that the loss is small. The resistance value is set to a relatively large value within the range where the charge remaining in the DC link capacitor can be discharged (including discharging so as not to accumulate) within a specified time.

[0027] The third discharge resistor R3, which is an active discharge resistor (rapid discharge resistor), does not function when the rotating electrical machine drive system 100 is operating normally because the third contactor S3 is open. When the rotating electrical machine drive system 100 stops, the charge accumulated in the DC link capacitor (for example, the first DC link capacitor C1) is rapidly discharged through the third discharge resistor R3 when the third contactor S3 is connected. The active discharge resistor is not constantly connected to the DC side of the inverter and is only connected when rapid discharge is required. For this reason, it has a relatively small resistance value so that the DC link voltage becomes equal to or lower than a specified value within a specified discharge time without considering the loss.

[0028] Note that the first discharge resistor R1 and the third contactor S3 may be connected in parallel, and the third discharge resistor R3 may be connected in series to the parallel circuit. In this case, when the third contactor S3 is open, the series circuit of the first discharge resistor R1 and the third discharge resistor R3 (resistance value: R1 + R3) functions as a passive discharge resistor. Also, when the third contactor S3 is connected, the series circuit of the third discharge resistor R3 and the third contactor S3 functions as a rapid discharge circuit 7. The active discharge resistor (rapid discharge resistor) is the third discharge resistor R3, similar to the form illustrated in FIG. 1.

[0029] The rotating electrical machine 80 can function as both a motor and a generator. The rotating electrical machine 80 converts the power from the DC power source into motive power via the inverter (power running). Alternatively, the rotating electrical machine 80 converts the rotational driving force transmitted from a wheel or the like into electric power and charges the DC power source via the inverter (regeneration).

[0030] As shown in FIG. 1, the inverter is controlled by a rotating electrical machine control device 10. The rotating electrical machine control device 10 can independently control each of the first inverter 1 and the second inverter 2. When the first inverter 1 and the second inverter 2 are controlled such that the waveform of the AC voltage output from the first inverter 1 and the phase of the AC voltage output from the second inverter 2 are different by 180 degrees (π), the amplitude of the AC voltage can be doubled. That is, a higher driving force can be obtained compared to the case where the rotating electrical machine 80 is driven by one inverter. Naturally, not only such a phase difference, but the rotating electrical machine control device 10 can control each of the first inverter 1 and the second inverter 2 in different control methods.

[0031] The control methods include a method of switching control of the inverter by pulse width modulation control, a method of switching control of the inverter by rectangular wave control, a shutdown control in which all switching elements of the inverter are turned off, and an active short circuit control in which all switching elements 5 on one side of the upper stage and the lower stage are turned off and all switching elements 5 on the other side are turned on. In addition, for the active short circuit control, there are a lower stage active short circuit control in which all upper stage switching elements 51 of one inverter are turned off and all lower stage switching elements 52 are turned on, and an upper stage active short circuit control in which all upper stage switching elements 51 of one inverter are turned on and all lower stage switching elements 52 are turned off. Also, in pulse width modulation control and rectangular wave control, there are a power running mode and a regeneration mode.

[0032] The rotation electric machine control device 10 is constructed with a logic circuit such as a microcomputer as a core member. The rotation electric machine control device 10 controls the rotation electric machine 80 based on the current of the rotation electric machine 80. The current of the rotation electric machine 80 is determined according to the target torque (torque command) of the rotation electric machine 80 provided from other control devices such as a vehicle control device (not shown). For example, the rotation electric machine control device 10 performs current feedback control using the vector control method based on the target torque of the rotation electric machine 80, and controls the rotation electric machine 80 via an inverter. In the vector control method, the actual current (U-phase current Iu, V-phase current Iv, W-phase current Iw) flowing through the rotation electric machine 80 is coordinate-transformed into vector components (d-axis current Id, q-axis current Iq) in the d-axis, which is the direction of the magnetic field (magnetic flux) generated by the permanent magnet arranged on the rotor of the rotation electric machine 80, and the q-axis, which is the direction orthogonal to the d-axis (the direction advanced by an electrical angle of π / 2 with respect to the direction of the magnetic field), and feedback control is performed. In FIG. 3 and the like, the current flowing through the stator coil 8 in this vector coordinate system is shown as a vector “i mot ”.

[0033] The actual current flowing through the stator coil 8 of each phase of the rotation electric machine 80 is detected by the current sensor 82, and the magnetic pole position at each point in time of the rotor of the rotation electric machine 80 is detected by the rotation sensor 81 such as a resolver or an inductive position sensor. The rotation electric machine control device 10 performs coordinate transformation in the three-phase to two-phase coordinate transformation unit 55 based on the detection result (θ (magnetic pole position, electrical angle)) of the rotation sensor 81. The rotation electric machine control device 10 executes current feedback control using the detection result (U-phase current Iu, V-phase current Iv, W-phase current Iw) of the current sensor 82 and the detection result (θ, ω (rotation speed, angular velocity)) of the rotation sensor 81. The rotation electric machine control device 10 is configured to have various functional units for current feedback control, and each functional unit is realized by the cooperation of hardware such as a microcomputer and software (program).

[0034] FIG. 2 schematically shows the energy flow in a vehicle during normal operation, and FIG. 3 shows the relationship between the voltage vector of the inverter and the current vector flowing through the stator coil 8 in the dq-axis orthogonal coordinate system during normal operation. As shown in FIG. 2, the first contactor S1 and the second contactor S2 are closed, power is supplied from the first DC power supply 3 to the first inverter 1, and power is supplied from the second DC power supply 4 to the second inverter 2. Then, current is supplied to the stator coil 8 (open winding) via the first inverter 1 and the second inverter 2, and the rotating electrical machine 80 outputs torque. The voltage vector of the first inverter 1 and the voltage vector of the second inverter 2 are vectors with opposite directions.

[0035] When losses are not considered, let the output power from the first DC power supply 3 be P b1 , the output power from the second DC power supply 4 be Pb 2 , the AC output power output from the first inverter 1 be P INV1 , the AC output power output from the second inverter 2 be P INV2 , the AC output power output from the two inverters be P INV , and the driving force (torque) output from the rotating electrical machine 80 be P mot . Then, the following formula (1) holds.

[0036] P b1 +P b2 =P INV1 +P INV2 =P INV =P mot ···(1)

[0037] For example, in the vector diagram shown in FIG. 3, a form in which P INV1 and P INV2 are the same is illustrated, but the outputs of the two inverters can be freely selected. That is, the rotating electrical machine control device 10 can appropriately set the distribution between P INV so that P INV1 and P INV2 do not change.

[0038] Further, the first DC link capacitor C1 is charged by the power supplied from the first DC power source 3, and the second DC link capacitor C2 is charged by the power supplied from the second DC power source 4. Although not shown in FIG. 2, power is also supplied from the first DC power source 3 to the in-vehicle device 9.

[0039] By the way, for example, when a running vehicle stops such as for parking, the first contactor S1 and the second contactor S2 are opened. At this time, the first DC link capacitor C1 and the second DC link capacitor C2 are in a high-voltage charged state and electric charges are accumulated. Therefore, even if the electrical connections to the first DC power source 3 and the second DC power source 4 are cut off, the voltage across the first DC link capacitor C1 and the second DC link capacitor C2 remains relatively high. Assuming a case where repair or the like is to be performed, it is preferable to quickly discharge the first DC link capacitor C1 and the second DC link capacitor C2. However, if the above-described rapid discharge circuit 7 is arranged in parallel for both the first DC link capacitor C1 and the second DC link capacitor C2, the cost will increase. This is because the resistance value of the rapid discharge resistor (third discharge resistor R3) is relatively small as described above, and the value of the current flowing through the rapid discharge circuit 7 is large, so the rapid discharge resistor (third discharge resistor R3) and the third contactor S3 often have a relatively large physical size.

[0040] Therefore, in the present embodiment, both the first DC link capacitor C1 and the second DC link capacitor C2 are discharged using one rapid discharge circuit 7 connected in parallel to the first DC link capacitor C1, thereby suppressing an increase in the circuit scale. The rotating electrical machine control device 10 executes rapid discharge control for passing a current through the rapid discharge resistor (third discharge resistor R3). Specifically, the rotating electrical machine control device 10 first opens the first contactor S1 and the second contactor S2 and connects the third contactor S3. When the first contactor S1 and the second contactor S2 are opened, the inflow of electric charges from the first DC power source 3 and the second DC power source 4 stops. Then, when the third contactor S3 is connected, the discharge of at least the first DC link capacitor C1 is started.

[0041] The rotating electrical machine control device 10 further performs switching control on the second inverter 2 in a power running mode to supply power to the rotating electrical machine 80, and performs switching control on the first inverter 1 in a regeneration mode to receive power from the rotating electrical machine 80. The second contactor S2 is open, and power is not supplied from the second DC power supply 4 to either the second inverter 2 or the second DC link capacitor C2. Then, power is supplied to the second inverter 2 not from the second DC power supply 4 but from the second DC link capacitor C2. The rotating electrical machine control device 10 converts the DC power supplied from the second DC link capacitor C2 into AC power by performing switching control on the second inverter 2 in the power running mode and supplies it to the stator coil 8. The power supplied from the second DC link capacitor C2 is supplied as AC power to the first inverter 1 via the stator coil 8. The rotating electrical machine control device 10 supplies the power from the second DC link capacitor C2 to the DC side of the first inverter 1 by performing switching control on the first inverter 1 that has received AC power from the stator coil 8 in the regeneration mode. A rapid discharge circuit 7 is connected to the DC side of the first inverter 1, and the power supplied from the second DC link capacitor C2 is consumed by the third discharge resistor R3. Thereby, the second DC link capacitor C2 is discharged.

[0042] FIG. 4 schematically shows the energy flow during rapid discharge, and FIG. 5 shows the relationship between the voltage of the inverter and the current flowing through the stator coil 8 during rapid discharge in the dq-axis orthogonal coordinate system.

[0043] As shown in FIG. 4, the charge of the second DC link capacitor C2 is supplied to the stator coil 8 via the second inverter 2. Since a current flows through the stator coil 8, the rotating electrical machine 80 may generate torque. However, the voltage vector “V inv2 ” of the second inverter 2 that is switched and controlled in the power running mode and the voltage vector “V inv1” and the synthetic vector (the vector indicated by the broken line in Fig. 5) with “, and the current vector “i flowing through the stator coil 8 mot ” is 90 degrees different in direction and the inner product becomes zero. By controlling the first inverter 1 and the second inverter 2 by the rotating electrical machine control device 10, the output of the rotating electrical machine 80 can be set to 0 watt. Thereby, the rotating electrical machine 80 can be controlled so as not to generate torque. In other words, in the rapid discharge control, the rotating electrical machine control device 10 controls the first inverter 1 and the second inverter 2 so that the sum of the torque generated in the rotating electrical machine 80 via the first inverter 1 and the torque generated in the rotating electrical machine 80 via the second inverter 2 becomes zero. Note that since there is a possibility that a minute torque is generated due to an error or the like, it is preferable that a braking force is applied to the wheels by a braking device (not shown).

[0044] As shown in Fig. 4, the charge of the second DC link capacitor C2 is supplied from the stator coil 8 to the rapid discharge circuit 7 via the first inverter 1, and is consumed in the rapid discharge circuit 7 together with the charge from the first DC link capacitor C1. That is, both the first DC link capacitor C1 and the second DC link capacitor C2 are discharged by one rapid discharge circuit 7.

[0045] Hereinafter, the rotating electrical machine control device described above will be briefly summarized.

[0046] As one aspect, a rotating electrical machine control device that drives and controls a rotating electrical machine having a multi-phase open winding via a first inverter and a second inverter, wherein the first inverter is connected to a first DC power supply via a first contactor, the second inverter is connected to a second DC power supply electrically independent of the first DC power supply via a second contactor, a first DC link capacitor for smoothing the voltage on the DC side of the first inverter is connected between the first contactor and the first inverter, a second DC link capacitor for smoothing the voltage on the DC side of the second inverter is connected between the second contactor and the second inverter, a rapid discharge circuit in which a rapid discharge resistor and a third contactor are connected in series is further connected in parallel to the first DC link capacitor, the first inverter and the second inverter each have a leg for one phase of alternating current configured by a series circuit of an upper switching element and a lower switching element, the first inverter is connected to the first DC power supply and one end side of the multi-phase open winding to convert power between DC on the first DC power supply side and multi-phase alternating current, the second inverter is connected to the second DC power supply and the other end side of the multi-phase open winding to convert power between DC on the second DC power supply side and multi-phase alternating current, the rotating electrical machine control device can control each of the first inverter and the second inverter independently of each other, and in the rapid discharge control for flowing a current through the rapid discharge resistor, the first contactor and the second contactor are opened and the third contactor is connected, and the second inverter is switched and controlled in a power running mode for supplying power to the rotating electrical machine, and the first inverter is switched and controlled in a regeneration mode for receiving power from the rotating electrical machine, so that the charges of the first DC link capacitor and the second DC link capacitor are discharged by the rapid discharge resistor.

[0047] According to this configuration, both the first DC link capacitor and the second DC link capacitor can be discharged using one rapid discharge circuit connected in parallel to the first DC link capacitor. Since only one rapid discharge circuit through which a large current flows is provided for the two DC link capacitors, an increase in circuit scale can be suppressed. That is, according to this configuration, while suppressing an increase in circuit scale, a plurality of DC link capacitors that smooth the voltage on the DC side of each of a plurality of inverters for driving and controlling an open-winding type rotating electrical machine can be rapidly discharged. That is, according to this configuration, while suppressing an increase in circuit scale, a plurality of DC link capacitors that smooth the voltage on the DC side of each of a plurality of inverters for driving and controlling an open-winding type rotating electrical machine can be rapidly discharged.

[0048] Further, in the rapid discharge control, it is preferable that the rotation electric machine control device controls the first inverter and the second inverter such that the sum of the torque generated in the rotation electric machine via the first inverter and the torque generated in the rotation electric machine via the second inverter becomes zero.

[0049] In a situation where rapid discharge of the DC link capacitor is required, the vehicle is stopped or parked. Therefore, it is preferable that no torque is transmitted to the wheels. According to this configuration, since the plurality of inverters are controlled such that the total value of the torques generated in the rotation electric machine via the plurality of inverters becomes zero, the torque transmitted to the wheels can be made zero.

Explanation of Reference Numerals

[0050] 1: First inverter 2: Second inverter 3: First DC power supply 4: Second DC power supply 5: Switching element 7: Rapid discharge circuit 8: Stator coil (open winding) 10: Rotation electric machine control device 51: Upper-stage switching element 52: Lower-stage switching element 80: Rotating electrical machine C1: First DC link capacitor C2: Second DC link capacitor R3: Third discharge resistor (rapid discharge resistor) S1: First contactor S2: Second contactor S3: Third contactor

Claims

1. A rotating electric machine control device that drives and controls a rotating electric machine having a plurality of open windings via a first inverter and a second inverter, the first inverter is connected to a first DC power source via a first contactor; the second inverter is connected via a second contactor to a second DC power source that is electrically independent of the first DC power source; a first DC link capacitor is connected between the first contactor and the first inverter to smooth a voltage on a DC side of the first inverter; a second DC link capacitor is connected between the second contactor and the second inverter to smooth a voltage on a DC side of the second inverter; a rapid discharge circuit in which a rapid discharge resistor and a third contactor are connected in series is further connected in parallel to the first DC link capacitor; The first inverter and the second inverter each have a leg for one AC phase that is configured by a series circuit of an upper-stage switching element and a lower-stage switching element, the first inverter is connected to the first DC power source and one end side of the open winding of the multiple phases to convert power between DC on the side of the first DC power source and AC on the multiple phases; the second inverter is connected to the second DC power source and the other end side of the open winding of the multiple phases to convert power between DC on the side of the second DC power source and AC on the multiple phases; The rotating electric machine control device includes: The first inverter and the second inverter are independently controllable, In the rapid discharge control in which a current flows through the rapid discharge resistor, The first contactor and the second contactor are opened and the third contactor is connected, The second inverter is switched and controlled in a powering mode for supplying electric power to the rotating electric machine, and the first inverter is switched and controlled in a regenerative mode for receiving electric power from the rotating electric machine, a rapid discharge resistor that discharges electric charges from the first DC link capacitor and the second DC link capacitor;

2. 2. The rotating electric machine control device according to claim 1, wherein in the rapid discharge control, the first inverter and the second inverter are controlled so that the sum of the torque generated in the rotating electric machine via the first inverter and the torque generated in the rotating electric machine via the second inverter becomes zero.

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