Drive system

Abstract

The invention provides a drive system capable of performing discharge control for discharging from a capacitor with a simple circuit configuration. A drive system for an electric motor vehicle, which drives a travel motor having a plurality of phases having a first coil group and a second coil group configured so as to include common teeth by means of the power of a battery, is provided with: a drive circuit that drives the first coil group and the second coil group, and drives the first coil group and the second coil group; a first inverter connected to the first coil group and a second inverter connected to the second coil group for each phase of the driving motor; and a control unit that controls at least one of the connection state between the first inverter and the first coil group and the connection state between the second inverter and the second coil group when there is a discharge request for the capacitor in a state in which the capacitor connected in parallel between the positive and negative electrodes of the storage battery and the storage battery are electrically cut off. Thus, the first coil group and the second coil group of the same phase are subjected to discharge control in which magnetic fluxes in opposite directions are generated.

Description

Technical Field

[0001] The present invention relates to a drive system. Background Art

[0002] Conventionally, a system for driving a motor such as a driving motor of an electric vehicle has been proposed (for example, see Japanese Patent Application Laid-Open No. 2011-259570). Summary of the Invention

[0003] Relatedly, to release the power stored in capacitors installed in drive circuits, technologies have been proposed, such as connecting a resistor to the capacitor to dissipate the power as heat, or controlling the d-axis current in vector-controlled motors to dissipate the power using the motor's coils. However, connecting a resistor increases the number and size of components, and vector control of the motor requires a current sensor and a high-performance computer. Consequently, conventional technologies have made it difficult to achieve discharge control from capacitors with a simple circuit configuration.

[0004] An object of an aspect of the present invention is to provide a drive system capable of controlling discharge from a capacitor with a simple circuit configuration.

[0005] One embodiment of the present invention is a drive system for an electric vehicle, which uses power from a battery to drive a driving motor having multiple phases, wherein the phases have a first coil group and a second coil group configured to include common teeth, wherein the drive system comprises: a drive circuit, which has a first inverter connected to the first coil group and a second inverter connected to the second coil group for each phase of the driving motor; and a control unit, which controls at least one of the connection state between the first inverter and the first coil group and the connection state between the second inverter and the second coil group when a capacitor connected in parallel between the positive and negative poles of the battery is electrically disconnected from the battery and when there is a discharge request for the capacitor, thereby performing discharge control to cause the first coil group and the second coil group of the same phase to generate magnetic flux in opposite directions.

[0006] According to the aspect of the present invention, discharge control from a capacitor can be performed with a simple circuit configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram showing an example of the configuration of a drive system according to this embodiment.

[0008] Figure 2 This is a diagram schematically showing the configuration of a magnetic circuit of a travel motor according to the present embodiment.

[0009] Figure 3 This is a diagram schematically showing the phase configuration of the coils of the traction motor according to the present embodiment.

[0010] Figure 4 This is a diagram showing an example of the configuration of a drive circuit according to this embodiment.

[0011] Figure 5 This is a diagram showing an example of the flow of operations of the control device according to this embodiment.

[0012] Figure 6 1 is a diagram showing an example of reverse phase discharge control performed by the control unit according to the present embodiment.

[0013] Figure 7 This is a diagram showing an example of a current path in reverse phase discharge control according to the present embodiment.

[0014] Figure 8 It is a diagram showing a modified example of the configuration of the drive system according to the present embodiment. DETAILED DESCRIPTION

[0015] [Overall structure of the drive system]

[0016] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0017] Figure 1 1 is a diagram showing an example of the configuration of a drive system 1 according to this embodiment. In one example of this embodiment, the drive system 1 is applied to an electric vehicle.

[0018] The drive system 1 includes a control device 10 , a travel motor 20 , a battery 30 , and a drive circuit 40 .

[0019] The control device 10 includes a control unit 110 and a storage unit 120 .

[0020] The control unit 110 includes, for example, a CPU (central processing unit), and provides various functions based on programs and data stored in the storage unit 120 .

[0021] The storage unit 120 includes a storage element such as a nonvolatile semiconductor memory, and stores programs and data for operating the control unit 110 .

[0022] The travel motor 20 includes a rotor 21, a coil 22, and a stator 23, and is driven based on the control of the control device 10. For a specific example of the structure of the travel motor 20, refer to Figure 2 To explain.

[0023] Figure 2 1 is a diagram schematically showing the configuration of a magnetic circuit of the travel motor 20 according to the present embodiment.

[0024] In this embodiment, the travel motor 20 is a so-called two-phase open winding switching motor. In one example of this embodiment, the travel motor 20 is composed of two-phase coils 22, α-phase and β-phase, which are shifted in phase by 90 degrees.

[0025] In the travel motor 20, the first coil group L1 and the second coil group L2 are wound around the teeth 23 of a certain phase. Specific examples of the first coil group L1 and the second coil group L2 will be described.

[0026] The stator 23 includes teeth 23 - 1 of the α-phase and teeth 23 - 2 of the β-phase.

[0027] An α-phase coil 221 - 1 (coil α 1 ) and an α-phase coil 221 - 2 (coil α 2 ) are wound around the α-phase tooth 23 - 1 .

[0028] The α-phase coil 221 - 1 (coil α 1 ) is also referred to as the α-phase first coil group L 1 , and the α-phase coil 221 - 2 (coil α 2 ) is also referred to as the α-phase second coil group L 2 .

[0029] A β-phase coil 222 - 1 (coil β1 ) and a β-phase coil 222 - 2 (coil β2 ) are wound around the β-phase tooth 23 - 2 .

[0030] The β-phase coil 222 - 1 (coil β1 ) is also referred to as the β-phase first coil group L1 , and the β-phase coil 222 - 2 (coil β2 ) is also referred to as the β-phase second coil group L2 .

[0031] That is, the travel motor 20 includes a plurality of phases including a first coil group L1 and a second coil group L2 configured to include common teeth.

[0032] The α-phase coil 221 - 1 (coil α1) and the α-phase coil 221 - 2 (coil α2) are Figure 2 β-phase coil 222-1 (coil β1) and β-phase coil 222-2 (coil β2) generate magnetic flux in the A direction. Figure 2 The magnetic flux is generated in the B direction. The A direction and the B direction are orthogonal to each other.

[0033] The traction motor 20 of this embodiment is a so-called two-phase motor (also called a spatial phase quadrature motor). The α-phase coil 221-1 (coil α1) and the α-phase coil 221-2 (coil α2) of the traction motor 20 are wound around a common tooth 23 (α-phase tooth 23-1) and are magnetically coupled to each other. Furthermore, the β-phase coil 222-1 (coil β1) and the β-phase coil 222-2 (coil β2) are wound around a common tooth 23 (β-phase tooth 23-2) and are magnetically coupled to each other.

[0034] In the driving motor 20, the direction of generation of the α-phase magnetic flux ( Figure 2 A direction) and the direction of the magnetic flux of the β phase ( Figure 2 The B directions) are orthogonal to each other, so there is no magnetic interference between the phases.

[0035] The coils 22 of the travel motor 20 are so-called open-ended windings. Therefore, the travel motor 20 can switch the electrical connection state between the coils 22 by a switching circuit external to the travel motor 20 .

[0036] For example, the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) can be connected in series or in parallel.

[0037] Likewise, the β-phase coil 222 - 1 (coil β 1 ) and the β-phase coil 222 - 2 (coil β 2 ) can be connected in series or in parallel.

[0038] That is, the travel motor 20 can be said to include a plurality of phases including a first coil group L1 and a second coil group L2 , the connection state of which can be switched between a series connection in which the coils are connected in series and a parallel connection in which the coils are connected in parallel.

[0039] Furthermore, the first coil group L1 and the second coil group L2 can also be said to be open windings in which a plurality of phases are connected to the inverter (drive circuit 40 ) independently of each other.

[0040] According to the thus configured travel motor 20 , the current of each phase can be controlled individually, and thus control can be performed in consideration of overheating of a specific phase or the like.

[0041] Figure 3 1 is a diagram schematically showing the phase configuration of the coil 22 of the travel motor 20 according to the present embodiment. As described above, the phase of the α phase and the phase of the β phase are orthogonal to each other.

[0042] Here, the phase difference δ between the coils 22 wound around the common stator 23 will be described.

[0043] The phase difference δα between the α-phase coil 221 - 1 (coil α1 ) and the α-phase coil 221 - 2 (coil α2 ) is 0. Similarly, the phase difference δβ between the β-phase coil 222 - 1 (coil β1 ) and the β-phase coil 222 - 2 (coil β2 ) is 0.

[0044] Therefore, when the same current flows through the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) to generate magnetic fluxes in opposite directions, the magnetic fluxes cancel each other out, and the magnetic flux of the entire α-phase tooth 23 - 1 becomes 0 (zero).

[0045] Similarly, when currents of the same magnitude flow through the β-phase coil 222 - 1 (coil β1 ) and the β-phase coil 222 - 2 (coil β2 ) to generate magnetic fluxes in opposite directions, the magnetic fluxes cancel each other out, and the magnetic flux of the entire β-phase tooth 23 - 2 becomes 0 (zero).

[0046] return Figure 1 The four coils 22 of the travel motor 20 , namely, the α-phase coil 221 - 1 (coil α1 ), the α-phase coil 221 - 2 (coil α2 ), the β-phase coil 222 - 1 (coil β1 ), and the β-phase coil 222 - 2 (coil β2 ), are each configured as an open winding.

[0047] The battery 30 includes a secondary battery and the like, and supplies electric power for traveling to the traveling motor 20 .

[0048] The capacitor 50 is connected in parallel with the battery 30 between the positive electrode and the negative electrode of the battery 30 , and temporarily stores the electric power generated between the positive electrode and the negative electrode of the battery 30 .

[0049] That is, capacitor 50 is connected in parallel between the positive and negative electrodes of battery 30 .

[0050] A battery contactor 31 is provided between the battery 30 and the capacitor 50 . The battery contactor 31 interrupts the supply of power from the battery 30 under control of a higher-level system (not shown). In other words, the battery contactor 31 disconnects the electrical connection between the battery 30 and the capacitor 50 .

[0051] For example, the host system disconnects the battery contactor 31 when the control of the electric vehicle equipped with the drive system 1 is stopped (for example, when the driver operates the control stop switch), when the high-voltage electrical systems such as the battery 30, the drive circuit 40, and the driving motor 20 are being repaired, or when an accident such as a collision occurs.

[0052] When the battery contactor 31 is in the conductive state (ON state), the potential difference between the two electrodes of the capacitor 50 is equal to the voltage between the positive and negative electrodes of the battery 30. In the following description, the voltage between the positive and negative electrodes of the battery 30 is also referred to as the battery voltage VBatt.

[0053] The battery voltage VBatt when the battery contactor 31 is turned off is also referred to as the battery final voltage VBattf. That is, the voltage between the electrodes of the capacitor 50 immediately after the battery contactor 31 is turned off is equal to the battery final voltage VBattf.

[0054] The drive circuit 40 is connected to each of the open-ended coils 22 of the travel motor 20 . The drive circuit 40 controls the connection state of the coils 22 and the transfer of power between the battery 30 and the travel motor 20 under the control of the control device 10 .

[0055] More specifically, the drive circuit 40 changes the connection between the α-phase coil 221-1 (coil α1) and the α-phase coil 221-2 (coil α2), and the connection between the β-phase coil 222-1 (coil β1) and the β-phase coil 222-2 (coil β2), to either a series connection or a parallel connection. Based on the control of the control device 10, the drive circuit 40 supplies electric power from the battery 30 to the traction motor 20, or supplies electric power generated by the traction motor 20 to the battery 30 (e.g., regeneration).

[0056] For a specific example of the structure of the drive circuit 40, refer to Figure 4 To explain.

[0057] Figure 4 1 is a diagram showing an example of the configuration of the drive circuit 40 according to the present embodiment. The drive circuit 40 includes a first inverter 41 and a second inverter 42 .

[0058] The first inverter 41 is connected to the α-phase coil 221 , and the second inverter 42 is connected to the β-phase coil 222 .

[0059] The first inverter 41 includes an eleventh inverter 411 and a twelfth inverter 412 .

[0060] The eleventh inverter 411 includes a first switch 411A, a second switch 411B, a third switch 411C, and a fourth switch 411D configured as an H-bridge, and drives the α-phase coil 221 - 1 (coil α 1 ).

[0061] The twelfth inverter 412 includes a first switch 412A, a second switch 412B, a third switch 412C, and a fourth switch 412D configured as an H-bridge, and drives the α-phase coil 221 - 2 (coil α 2 ).

[0062] As described above, the α-phase coil 221 - 1 (coil α 1 ) constitutes the first coil group L 1 , and the α-phase coil 221 - 2 (coil α 2 ) constitutes the second coil group L 2 .

[0063] Similarly, regarding the β phase, the second inverter 42 includes a twenty-first inverter 421 and a twenty-second inverter 422 .

[0064] The twenty-first inverter 421 includes a first switch 421A, a second switch 421B, a third switch 421C, and a fourth switch 421D configured as an H-bridge, and drives the β-phase coil 222 - 1 (coil β1 ).

[0065] The twenty-second inverter 422 includes a first switch 422A, a second switch 422B, a third switch 422C, and a fourth switch 422D configured as an H-bridge, and drives the β-phase coil 222 - 2 (coil β2 ).

[0066] As described above, the β-phase coil 222 - 1 (coil β1 ) constitutes the first coil group L1 , and the β-phase coil 222 - 2 (coil β2 ) constitutes the second coil group L2 .

[0067] That is, the drive circuit 40 includes a first inverter (e.g., the eleventh inverter 411, the twenty-first inverter 421) connected to the first coil group L1 and a second inverter (e.g., the twelfth inverter 412, the twenty-second inverter 422) connected to the second coil group L2 for each phase of the driving motor 20.

[0068] [Switching the Connection State of Coil 22]

[0069] The first connection changeover switch 413 is disposed between the eleventh inverter 411 and the twelfth inverter 412. The first connection changeover switch 413 is switched between an on state and an off state under the control of the control device 10, thereby switching the connection state between the α-phase coil 221-1 (coil α1) and the α-phase coil 221-2 (coil α2) to either a parallel connection or a series connection.

[0070] (1) When the coil 22 is connected in parallel

[0071] Control device 10 turns off first connection switch 413. When first connection switch 413 is turned off, eleventh inverter 411 and twelfth inverter 412 are electrically disconnected. As a result, eleventh inverter 411 drives α-phase coil 221-1 (coil α1), while twelfth inverter 412 drives α-phase coil 221-2 (coil α2).

[0072] More specifically, control device 10 turns on first switch 411A and fourth switch 411D, and turns off second switch 411B and third switch 411C, for eleventh inverter 411. As a result, a current path is established between first switch 411A and fourth switch 411D for α-phase coil 221-1 (coil α1).

[0073] The control device 10 turns on the first switch 412A and the fourth switch 412D and turns off the second switch 412B and the third switch 412C in the twelfth inverter 412. As a result, a current path is formed between the first switch 412A and the fourth switch 412D for the α-phase coil 221-2 (coil α2).

[0074] When electric power is supplied from the battery 30 or capacitor 50 to the traction motor 20, a drive current flows from the first switch 411A to the fourth switch 411D in the α-phase coil 221-1 (coil α1) of the eleventh inverter 411. Similarly, a drive current flows from the first switch 412A to the fourth switch 412D in the α-phase coil 221-2 (coil α2) of the twelfth inverter 412.

[0075] like Figure 4 As shown, the end of the α-phase coil 221 - 1 (coil α 1 ) connected to the first switch 411A is marked with a black circle. The end of the α-phase coil 221 - 2 (coil α 2 ) connected to the first switch 412A is marked with a black circle.

[0076] When a drive current flows from the side of the black circle indicated in coil 22 , the direction of the magnetic flux generated in the α-phase tooth 23 - 1 due to the drive current flowing through the α-phase coil 221 - 1 (coil α 1 ) is aligned with the direction of the magnetic flux generated in the α-phase tooth 23 - 1 due to the drive current flowing through the α-phase coil 221 - 2 (coil α 2 ).

[0077] That is, the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) generate magnetic flux in the same direction in the stator 23 .

[0078] When the directions of the drive currents flowing through the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) are reversed, the control device 10 reverses the on / off states of the switches of the eleventh inverter 411 and the twelfth inverter 412 from the above-described states.

[0079] As described above, the control device 10 connects the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) in parallel and controls the drive currents thereof.

[0080] Note that the parallel connection structure of the coils 22 in the second inverter 42 is similar to that of the first inverter 41 except that the second inverter 42 operates at a phase shifted by 90 degrees relative to the first inverter 41 , and therefore its description is omitted.

[0081] (2) When the coil 22 is connected in series

[0082] The control device 10 turns on the first connection switch 413 and turns off the third switch 411C and the fourth switch 411D of the eleventh inverter 411 and the first switch 412A and the second switch 412B of the twelfth inverter 412 .

[0083] When the first connection changeover switch 413 is turned on, the eleventh inverter 411 and the twelfth inverter 412 are electrically connected.

[0084] As a result, the first inverter 41 forms an H-bridge including the first switch 411A, the second switch 411B, the third switch 412C, and the fourth switch 412D.

[0085] The control device 10 switches the first switch 411A and the fourth switch 412D, and the second switch 411B and the third switch 412C, into pairs and switches them between on and off. As a result, the α-phase coil 221 - 1 (coil α 1 ) and the α-phase coil 221 - 2 (coil α 2 ) are driven in a series connection.

[0086] [Charging mode function]

[0087] Here, a case will be described in which the first inverter 41 and the second inverter 42 are used as a charging circuit when an external charger (not shown) charges the battery 30 in a so-called plug-in electric vehicle.

[0088] Generally, a charging circuit connected to an external charger is configured to include a reactor and a switching element for voltage regulation, and an isolation transformer.

[0089] As described above, the travel motor 20 of the present embodiment is configured with spatial phase quadrature and open windings. Therefore, by electrically disconnecting the α phase and the β phase and independently controlling them, different functions can be imparted between the phases.

[0090] For example, the traction motor 20 can make the α phase function as an insulation transformer and the β phase function as a reactor.

[0091] The drive circuit 40 of the present embodiment causes the coil 22 of the first inverter 41 to function as an isolation transformer, and causes the coil 22 of the second inverter 42 to function as a reactor.

[0092] (1) When the coil 22 of the second inverter 42 functions as a reactor

[0093] The drive circuit 40 includes a disconnect switch 424 in the second inverter 42. The disconnect switch 424 includes a first disconnect switch 424A and a second disconnect switch 424B.

[0094] The first disconnect switch 424A is connected in series with the β-phase coil 222 - 1 (coil β 1 ), and the second disconnect switch 424B is connected in series with the β-phase coil 222 - 2 (coil β 2 ).

[0095] To enable coil 22 of second inverter 42 to function as a charging reactor, control device 10 opens circuit breakers 424 (first circuit breaker 424A and second circuit breaker 424B). As a result, one end of β-phase coil 222-1 (coil β1) and one end of β-phase coil 222-2 (coil β2) are both open.

[0096] By connecting each phase of an external charger to one end of coil 22 opened by disconnect switch 424 , β-phase coil 222 - 1 (coil β1 ) and β-phase coil 222 - 2 (coil β2 ) can function as charging reactors.

[0097] As an example, using a charger connection circuit (not shown), the U phase of the external charger is connected to one end of the β-phase coil 222 - 1 (coil β1 ), the V phase is connected to the midpoint of the second connection changeover switch 423 , and the W phase is connected to one end of the β-phase coil 222 - 2 (coil β2 ).

[0098] Note that, in this case, each switching element of the second inverter 42 functions as an inverter that converts the electric power supplied from the external charger into a charging current for the battery 30 .

[0099] (2) When the coil 22 of the first inverter 41 functions as an insulating transformer

[0100] When charging the battery 30 with electric power supplied from an external charger, it is preferable that the external charger (not shown) is electrically insulated from the battery 30 .

[0101] For example, when an external charger is connected to the second inverter 42 side, if an isolation transformer is disposed between the second inverter 42 and the battery 30 , the second inverter 42 and the battery 30 can be electrically isolated.

[0102] When the drive system 1 is charged from an external charger, the first inverter 41 functions as an isolation transformer.

[0103] The drive circuit 40 includes a disconnect switch 414 in the first inverter 41. The disconnect switches 414 include a first disconnect switch 414A and a second disconnect switch 414B. The first disconnect switch 414A is located on the positive electrode side (high potential side) of the battery 30 in the power supply wiring between the eleventh inverter 411 and the twelfth inverter 412. The second disconnect switch 414B is located on the negative electrode side (low potential side) of the battery 30 in the power supply wiring between the eleventh inverter 411 and the twelfth inverter 412.

[0104] When the control device 10 causes the coil 22 of the first inverter 41 to function as an isolation transformer, it opens the disconnect switches 414 (the first disconnect switch 414A and the second disconnect switch 414B). As a result, the power supply wiring of the eleventh inverter 411 is isolated from the power supply wiring of the twelfth inverter 412.

[0105] As described above, α-phase coil 221-1 (coil α1) and α-phase coil 221-2 (coil α2) are wound around a common tooth 23 (α-phase tooth 23-1) and are magnetically coupled to each other. Therefore, AC power supplied to twelfth inverter 412 from an external charger connected to second inverter 42 is transferred from α-phase coil 221-2 (coil α2) to α-phase coil 221-1 (coil α1) via magnetic coupling. As a result, the power transferred to α-phase coil 221-1 (coil α1) is charged into battery 30.

[0106] That is, the first inverter 41 functions as an isolation transformer, electrically insulating the second inverter 42 side from the battery 30 , and transmitting electric power through magnetic coupling.

[0107] As described above, the first inverter 41 and the second inverter 42 of the present embodiment function as a circuit for driving the travel motor 20 , and also function as a circuit for charging the battery 30 when an external charger is connected.

[0108] That is, the drive circuit 40 of this embodiment can also serve as a charging reactor, inverter, and insulation transformer. Therefore, compared with a case where these functions are configured as a circuit dedicated to charging, the number of components can be reduced, thereby achieving weight reduction and price reduction.

[0109] [Discharge Control by Control Device 10]

[0110] Next, the discharge control performed by the control device 10 will be described. The control device 10 of this embodiment controls the travel motor 20 based on a request from the electric vehicle's host system (e.g., a power plant control system). For example, the request from the host system includes a discharge request RD. The discharge request RD is an instruction to the control device 10 to discharge the power stored in the capacitor 50 while the battery contactor 31 is disconnected.

[0111] For an example of the flow of the discharge control operation of the control device 10, refer to Figure 5 To explain.

[0112] Figure 5 This is a diagram showing an example of the flow of operations of the control device 10 according to the present embodiment.

[0113] (Step S10 ) The control unit 110 of the control device 10 determines whether there is a discharge request RD from the host system. If the control unit 110 determines that there is no discharge request RD (Step S10 ; No), the process proceeds to Step S20 .

[0114] (Step S20 ) When there is no discharge request RD, the control unit 110 performs normal control.

[0115] Here, normal control refers to general control other than discharge control. The control unit 110 returns the process to step S10 and continues to determine whether the discharge request RD is present.

[0116] On the other hand, when the control unit 110 determines in step S10 that the discharge request RD is present (step S10 ; YES), the process proceeds to step S30 .

[0117] (Step S30) The control unit 110 performs discharge control when there is a discharge request RD. The discharge control performed by the control unit 110 in this embodiment is also referred to as reverse phase discharge control. An example of reverse phase discharge control is shown in FIG. Figure 6 .

[0118] Figure 6This diagram illustrates an example of reverse-phase discharge control performed by the control unit 110 of this embodiment. The control unit 110 connects the coils 22 of the second inverter 42 in parallel. The control unit 110 groups the first switch 421A and the fourth switch 421D of the twenty-first inverter 421, and the third switch 422C and the second switch 422B of the twenty-second inverter 422 (also referred to as the first group), to control the on / off states. Furthermore, the control unit 110 groups the third switch 421C and the second switch 421B of the twenty-first inverter 421, and the first switch 422A and the fourth switch 422D of the twenty-second inverter 422 (also referred to as the second group), to control the on / off states.

[0119] The control unit 110 is as follows Figure 6 As shown in [A], the on and off states of the first and second groups are reversed and controlled. Figure 7 The current path CP is shown.

[0120] Figure 7 : is a diagram showing an example of a current path CP in the reverse phase discharge control of this embodiment. Figure 7 , the case where the first group is turned on and the second group is turned off is shown (for example, Figure 6 An example of the current path CP of the state in the interval from time t1 to time t2).

[0121] In this example, the first current path CP21 and the second current path CP22 are formed by reverse phase discharge control.

[0122] like Figure 6 As shown in [B], when first current path CP21 and second current path CP22 are formed, first current iβ1 flows through β-phase coil 222-1 (coil β1), and second current iβ2 flows through β-phase coil 222-2 (coil β2). The flow of first current iβ1 and second current iβ2 results in power consumption due to copper loss and switching loss in the circuit.

[0123] As described above, in the discharge control (reverse phase discharge control), the battery contactor 31 is turned off, so that the power from the battery 30 is not supplied. Therefore, the power of the capacitor 50 is consumed, as shown in FIG. Figure 6 As shown in [C], the voltage across the capacitor 50 (ie, the capacitor voltage vc) decreases.

[0124] The direction of the first current iβ1 and the direction of the second current iβ2 are opposite to each other. As described above, the phase difference δβ between the β-phase coil 222-1 (coil β1) and the β-phase coil 222-2 (coil β2) is 0 (zero). Therefore, the magnetic flux generated by the currents flowing through these coils 22 cancel each other out, and no magnetic flux is generated by the coils 22 as a whole.

[0125] That is, the control unit 110 prevents the coils 22 of the second inverter 42 (the β-phase coil 222 - 1 (coil β1 ), the β-phase coil 222 - 2 (coil β2 )) from generating magnetic flux and allows the first current iβ1 and the second current iβ2 to flow.

[0126] As described above, the α-phase coil 221 - 1 (coil α 1 ) constitutes the first coil group L 1 , and the α-phase coil 221 - 2 (coil α 2 ) constitutes the second coil group L 2 .

[0127] Furthermore, the β-phase coil 222 - 1 (coil β1 ) constitutes the first coil group L1 , and the β-phase coil 222 - 2 (coil β2 ) constitutes the second coil group L2 .

[0128] Specifically, the drive system 1 controls the currents so that they flow in opposite phases through the magnetically coupled first coil group L1 and second coil group L2. With this configuration, the magnetic fluxes generated by the coils 22 cancel each other out, allowing the high-voltage power supply system (e.g., capacitor 50) to be discharged without generating torque in the traction motor 20.

[0129] Generally, when using vector control to control the traction motor 20, it is necessary to sense the rotation angle of the rotor 21 and perform feedback calculations based on the sensed rotation angle. In this case, feedback calculations based on the sensed rotation angle are necessary to prevent the traction motor 20 from generating torque during discharge control.

[0130] On the other hand, the drive system 1 of this embodiment does not rely on vector control, and can discharge without causing the driving motor 20 to generate torque by controlling the direction of the discharge current simply by the winding structure and magnetic design of the coil 22 .

[0131] It should be noted that in the above example, the control unit 110 discharges the capacitor 50 by operating the second inverter 42, but the present invention is not limited to this. The control unit 110 may also discharge the capacitor 50 by operating the first inverter 41. In addition, the control unit 110 may discharge the capacitor 50 by operating both the first inverter 41 and the second inverter 42.

[0132] That is, when there is a discharge request for the capacitor 50, the control unit 110 controls the connection state between the first inverter (for example, the eleventh inverter 411, the twenty-first inverter 421) and the first coil group L1, and the connection state between the second inverter (for example, the twelfth inverter 412, the twenty-second inverter 422) and the second coil group L2, respectively, thereby performing discharge control so that the first coil group L1 and the second coil group L2 of the same phase generate magnetic fluxes in opposite directions.

[0133] As an example, the host system outputs a discharge request RD when an accident such as a collision occurs. For example, the discharge request is generated when a collision of an electric vehicle is detected.

[0134] According to the drive system 1 that performs reverse discharge control as described above, even if the sensor for sensing the rotation angle of the rotor 21 is no longer usable due to an impact such as a collision, or the relatively high-performance computer required for feedback calculation does not operate, discharge can be performed without causing the driving motor 20 to generate torque.

[0135] [Structure of the Operating Power Supply of the Control Device 10]

[0136] like Figure 1 As shown, the control device 10 can operate using a backup power supply based on power supplied from the capacitor 50 in addition to the control power supplied from the host system (for example, a low-voltage power supply for control supplied from a so-called 12V battery).

[0137] That is, at least the circuit that performs discharge control in the control unit 110 operates using either the power supplied from the control power supply that drives other circuits of the control unit 110 or the power supplied from the capacitor 50 .

[0138] Furthermore, the circuit for controlling the driving of the travel motor 20 and the circuit for controlling the discharge (reverse-phase discharge control) of the control unit 110 of the control device 10 may be configured as separate circuits.

[0139] In this case, the above-mentioned auxiliary power supply is supplied to at least the circuit that performs discharge control (reverse-phase discharge control).

[0140] That is, at least the circuit that performs discharge control in the control unit 110 can operate using the power supplied from the capacitor 50. According to the drive system 1 configured in this way, even if the control power supplied from the host system fails due to a malfunction, a collision, etc., at least the discharge control operation can be continued.

[0141] [Variation]

[0142] Figure 8This diagram shows a modified example of the configuration of the drive system 1 according to this embodiment. In the above embodiment, the drive circuit 40 and the control device 10 are configured as separate devices. While the above embodiment describes a case where the control unit 110 of the control device 10 performs discharge control (reverse-phase discharge control), this is not limiting.

[0143] The present modification differs from the above-described embodiment in that, among the functions of the control unit 110 , at least a discharge control unit 460 that performs discharge control (reverse-phase discharge control) is provided in the drive circuit 40 .

[0144] The drive circuit 40 may include a gate drive circuit for transistors (for example, the first switch 421A to the fourth switch 422D) constituting the first inverter 41 and the second inverter 42 .

[0145] When the gate driving circuit is configured in the driving circuit 40 as described above, the discharge control unit 460 that performs discharge control (reverse phase discharge control) may be configured integrally with the gate driving circuit.

[0146] Here, integration refers to a situation where the gate drive circuit and the circuit structure of the discharge control unit 460 are on the same substrate, or a situation where the gate drive circuit and the circuit structure of the discharge control unit 460 are on different substrates, and these substrates are connected to each other via jumper wires and removable (or non-removable) stacking connectors.

[0147] In addition, the drive circuit 40 may be housed in a housing (casing) for waterproofing, dustproofing, and enhanced strength. In this case, integration means that the gate drive circuit and the circuit of the discharge control unit 460 are configured in the same housing.

[0148] That is, at least the discharge control unit 460 that performs discharge control in the control unit 110 is provided integrally with the gate drive circuits of the transistors constituting the first inverter 41 and the second inverter 42 .

[0149] Generally, the control device 10 is configured with a computer having relatively high computing performance because relatively complex calculations are required to drive the travel motor 20 .

[0150] Meanwhile, as described above, discharge control (reverse-phase discharge control) effectively utilizes the characteristics of the coils 22 of the traction motor 20: their spatial phases are orthogonal, and the phase difference δ between the coils 22 of each phase is 0 (zero). Specifically, discharge control (reverse-phase discharge control) allows the capacitor 50 to be discharged while suppressing the generation of magnetic flux and preventing the traction motor 20 from generating torque, simply by passing current through the coils 22 of the traction motor 20. In other words, discharge control (reverse-phase discharge control) can be implemented using a relatively simple circuit that simply turns on or off predetermined switches in the first inverter 41 and the second inverter 42.

[0151] Therefore, the discharge control unit 460 can be easily integrated with the gate driving circuit.

[0152] In the drive system 1 of this variant, the gate drive circuits of the transistors constituting the first inverter 41 and the second inverter 42 are integrated with the discharge control unit 460. Therefore, even if the sensor for sensing the rotation angle of the rotor 21 cannot be used due to an impact such as a collision, or the relatively high-performance computer required for feedback calculation does not operate, discharge can be performed without causing the driving motor 20 to generate torque.

[0153] While the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the specific configuration is not limited to the embodiments and modifications may be made as appropriate without departing from the spirit of the present invention. The configurations described in the embodiments may also be combined.

[0154] It should be noted that each component included in each device in the above-described embodiments may be implemented by dedicated hardware, or may be implemented by a memory and a microprocessor.

[0155] It should be noted that each component of each device may be composed of a memory and a CPU (Central Processing Unit), and a program for realizing the function of each component of each device may be downloaded to the memory and executed to realize the function.

Claims

1. A drive system for an electric vehicle, wherein a plurality of phases of a traction motor are driven by power from a battery, wherein the phases have a first coil group and a second coil group configured to include common teeth, wherein: The drive system comprises: a drive circuit including, for each phase of the travel motor, a first inverter connected to the first coil group and a second inverter connected to the second coil group; as well as a control unit that, when a capacitor connected in parallel between the positive and negative electrodes of the battery is electrically disconnected from the battery and when there is a discharge request for the capacitor, controls at least one of the connection state between the first inverter and the first coil group and the connection state between the second inverter and the second coil group, thereby performing discharge control so that the first coil group and the second coil group of the same phase generate magnetic flux in opposite directions.

2. The drive system according to claim 1, wherein: The first coil group and the second coil group are open-type windings in which a plurality of phases are independently connected to an inverter.

3. The drive system according to claim 1, wherein: The discharge request is generated when a collision of the electric vehicle is detected.

4. The drive system according to claim 1, wherein: At least the circuit that performs the discharge control in the control unit can operate using the power supplied from the capacitor.

5. The drive system according to claim 4, wherein: At least the circuit that performs the discharge control in the control unit operates using either power supplied from a control power supply that drives other circuits in the control unit or power supplied from the capacitor.

6. The drive system according to claim 1, wherein: At least a discharge control unit that performs the discharge control among the control units is provided in gate drive circuits of transistors constituting the first inverter and the second inverter.

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