Drive device

Abstract

A drive device includes a first motor including a first stator coil, a second motor including a second stator coil, a first inverter, a second inverter, a selector switch, a disconnect switch, and a controller. The first inverter is connected with the first stator coil, and the second inverter is connected with the second stator coil. The change-over switch connects the first stator coil to either the neutral point or the second inverter. The disconnect switch disconnects the second stator coil from the second inverter. The controller is capable of switching between a dual mode in which the first stator coil is connected to the second inverter and the disconnect switch is turned on, and a single mode in which the first stator coil is connected to the neutral point.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a drive device including two motors and two inverters. Background Art

[0002] There is known an open-winding type motor in which two inverters are connected to one motor. One end of the stator coil of the open-winding type motor is connected to the first inverter, and the other end is connected to the second inverter. A drive device in which two inverters are connected to one open-winding type motor is sometimes referred to as a dual-inverter type. The dual-inverter type can increase the voltage applied to the stator coil compared to a drive device using one inverter. The dual-inverter type can output high torque with high utilization efficiency. Here, high utilization efficiency means low power loss. A dual-inverter type drive device is exemplified in Japanese Unexamined Patent Application Publication No. 2023-25679. Summary of the Invention

[0003] In electric vehicles and hybrid vehicles, there is known a drive device (two-motor / two-inverter drive device) including two motors and two inverters connected to each motor. In a conventional two-motor / two-inverter drive device, each inverter independently drives each motor. For example, the first motor and the first inverter drive the front wheels, and the second motor and the second inverter drive the rear wheels.

[0004] This specification provides a drive device improved to be able to use a two-motor / two-inverter drive device also as a dual-inverter type, with a wide range of applications.

[0005] The drive device disclosed in this specification includes: a first motor having a first stator coil, a second motor having a second stator coil, a first inverter, a second inverter, a changeover switch, a disconnect switch, and a controller.

[0006] The first inverter is connected to the first stator coil,

[0007] The second inverter is connected to the second stator coil.

[0008] The changeover switch connects the first stator coil to either the neutral point or the second inverter.

[0009] The disconnect switch can disconnect the second stator coil from the second inverter.

[0010] The controller controls the changeover switch and the disconnect switch.

[0011] The controller can switch between a dual mode and a single mode. In the dual mode, the first stator coil is connected to the second inverter by the changeover switch and the disconnect switch is opened. In the single mode, the first stator coil is connected to the neutral point by the changeover switch.

[0012] In addition, in single mode, the disconnect switch can be open or closed.

[0013] In single mode, the controller 40 can control the first motor (first inverter) and the second motor (second inverter) independently. The single mode corresponds to the conventional 2-motor / 2-inverter type drive device. In dual mode, the first inverter and the second inverter are connected to the stator coil of the first motor. At this time, the drive device can be used as a dual-inverter type drive device. In dual mode, high torque can be obtained from the first motor. The technology disclosed in this specification can realize a drive device that can be used in both 2-motor / 2-inverter type and dual-inverter type. The applicable range of the drive device disclosed in this specification is wide. In other words, the power utilization efficiency of the drive device disclosed in this specification is high.

[0014] The first stator coil of the first motor may also include a first sub-coil and a second sub-coil connected in series.

[0015] In this case, the changeover switch can be configured to connect the midpoint of the first sub-coil and the second sub-coil to the neutral point.

[0016] In addition, when the first stator coil is connected to the second inverter, the ends of the series connection of the first sub-coil and the second sub-coil are connected to the second inverter. In dual mode, the first sub-coil and the second sub-coil are used, and only the first sub-coil is used in single mode. High torque can be obtained in dual mode. The number of turns of the coil used in single mode becomes smaller, so the inductance of the first motor becomes smaller. As a result, the loss in the high-speed region becomes smaller.

[0017] The drive device disclosed in this specification may further include an engine and a planetary gear.

[0018] The ring gear of the planetary gear is connected to the first motor.

[0019] The sun gear of the planetary gear is connected to the second motor.

[0020] The planet carrier of the planetary gear is connected to the engine.

[0021] If the dual mode is selected and the engine is stopped, high torque can be obtained in EV mode. If the single mode is selected and the engine and the second motor are stopped, although the output torque is low, high utilization efficiency can be obtained. If the single mode is selected, the engine is operated, and the first motor and the second motor are operated, it is equivalent to the conventional hybrid system.

[0022] The details and further improvements of the technology disclosed in this specification are described in the following "Detailed Description of the Invention". BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals denote like parts, where:

[0024] Figure 1 is a circuit diagram of the drive device of the first embodiment;

[0025] Figure 2 is a circuit diagram of the drive device of the second embodiment;

[0026] Figure 3 is a block diagram of the drive device of the third embodiment;

[0027] Figure 4 is a nomogram of the drive device of the third embodiment (single mode / low torque EV driving);

[0028] Figure 5 is a nomogram of the drive device of the third embodiment (dual mode / high torque EV driving);

[0029] Figure 6 is a nomogram of the drive device of the third embodiment (single mode / high torque HV driving). Detailed Description of the Embodiments

[0030] First Embodiment

[0031] Figure 1 A circuit diagram showing the drive device 2 of the first embodiment is presented. The drive device 2 includes a first motor 10, a second motor 20, a first inverter 31, a second inverter 32, a changeover switch 38, a disconnection switch 39, and a controller 40. The drive device 2 can cause the first motor 10 and the second motor 20 to output torque respectively, and can also stop one of the first motor 10 and the second motor 20 and output torque from the other. The drive device 2 having two motor output shafts is applicable to electric vehicles and hybrid vehicles. In an electric vehicle as an example, the first motor 10 drives the front wheels and the second motor 20 drives the rear wheels. In a hybrid vehicle as an example, the first motor 10, the second motor, and the engine are linked to the wheels via a planetary gear. The drive device 202 suitable for a hybrid vehicle will be described later.

[0032] The first inverter 31 includes three series-connected bodies each having two switching elements. The three series-connected bodies are connected in parallel with a DC power supply 50. The switching elements are controlled by the controller 40. Figure 1 The arrowed dashed lines indicate signal lines. If the controller 40 appropriately turns on and off the six switching elements, an alternating current is output from the midpoint of the series-connected body. The second inverter 32 has the same circuit configuration as the first inverter 31. The three series-connected bodies of the second inverter 32 are also connected in parallel with the DC power supply 50. Since the configuration of the inverter is well-known, detailed description thereof is omitted.

[0033] Both the first motor 10 and the second motor 20 are three-phase AC motors. Three AC terminals of the first inverter 31 are connected to the first motor 10. The first motor 10 includes three first stator coils 11, and the three AC terminals of the first inverter 31 are respectively connected to one ends of the three first stator coils 11. The other ends of the first stator coils 11 are connected to the second inverter 32 and the neutral point 12 via a changeover switch 38. The changeover switch 38 includes a first switch 38a and a second switch 38b. The first switch 38a is connected between the first stator coil 11 and the AC terminal of the second inverter 32, and the second switch 38b is connected between the first stator coil 11 and the neutral point 12. If the first switch 38a is closed, the first stator coils 11 are respectively connected to the respective AC terminals of the second inverter 32. If the first switch 38a is opened, the first stator coils 11 are disconnected from the second inverter 32. If the second switch 38b is closed, the first stator coils 11 are respectively connected to the neutral point 12. The other ends of the plurality of first stator coils 11 are connected to each other at the neutral point 12. If the second switch 38b is opened, the first stator coils 11 are disconnected from the neutral point 12. The changeover switch 38 is controlled by a controller 40.

[0034] The controller 40 controls the first switch 38a and the second switch 38b such that if one is opened, the other is closed. That is, the changeover switch 38 connects the other end of the first stator coil 11 to either the neutral point or the second inverter 32. More specifically, the changeover switch 38 connects the other end of the first stator coil 11 to either the neutral point or the AC terminal of the second inverter 32.

[0035] Three AC terminals of the second inverter 32 are connected to the second motor 20. The second motor 20 includes three second stator coils 21, and each AC terminal of the second inverter 32 is connected to one end of the three second stator coils 21. The other ends of the plurality of second stator coils 21 are connected to each other at the neutral point 22. A disconnection switch 39 is connected between the AC terminal of the second inverter 32 and the second stator coil 21. If the disconnection switch 39 is opened, the second motor 20 is disconnected from the second inverter 32.

[0036] The controller 40 controls the changeover switch 38 and the disconnection switch 39. The controller 40 closes the first switch 38a of the changeover switch 38, opens the second switch 38b, and opens the disconnection switch 39. At this time, the other ends of the first stator coils 11 of the first motor 10 are connected to the AC terminals of the second inverter 32, and the second motor 20 is disconnected from the second inverter 32. Hereinafter, this state is referred to as the dual mode. In addition, at this time, the neutral point 12 is disconnected from the first stator coils 11.

[0037] In addition, the controller 40 turns on the first switch 38a of the changeover switch 38 and closes the second switch 38b. At this time, the other end of the first stator coil 11 of the first motor 10 is disconnected from the second inverter 32 and connected to the neutral point 12. Hereinafter, this state is referred to as the single mode. In addition, in the single mode, the disconnection switch 39 can be closed or opened. If the disconnection switch 39 is closed, the second motor 20 is connected to the second inverter 32. The first motor 10 is driven by the first inverter, and the second motor 20 is driven by the second inverter 32. The first motor 10 and the second motor 20 are driven independently.

[0038] The controller 40 selects either the dual mode or the single mode. In the dual mode, the AC terminal of the first inverter 31 is connected to one end of the first stator coil 11, and the AC terminal of the second inverter 32 is connected to the other end of the first stator coil 11. If the controller 40 appropriately turns on and off the switching elements of the first inverter 31 and the second inverter 32, the first motor 10 outputs a high torque. At this time, the output of the first motor 10 is larger than the output when one inverter drives one motor. The control rules of the two inverters in the dual mode can adopt well-known technologies.

[0039] In the dual mode, a high torque can be obtained with high utilization efficiency. Here, high utilization efficiency means low power loss during motor driving. In addition, in the dual mode, the second motor 20 cannot be used.

[0040] In the single mode, the AC terminal of the first inverter 31 is connected to one end of the first stator coil 11, and the other end is connected to the neutral point 12 via the changeover switch 38. At this time, the first stator coil 11 is disconnected from the AC terminal of the second inverter 32. If the disconnection switch 39 is closed, the AC terminal of the second inverter 32 is connected to the second stator coil 21 of the second motor 20. In the single mode, the first inverter 31 drives the first motor 10, and the second inverter 32 drives the second motor 20. In the single mode, the first motor 10 and the second motor 20 can be controlled independently. In the single mode, the maximum output torque of the first motor 10 is lower than that in the dual mode, but in the single mode, two motors can be driven with high utilization efficiency.

[0041] The drive device 2 of the first embodiment can obtain an output torque with high utilization efficiency from the low torque range to the high torque range by switching between the dual mode and the single mode. Since the drive device 2 can switch between the dual mode and the single mode, the applicable range is expanded. In other words, the power utilization efficiency of the drive device 2 is high.

[0042] The drive device 2 is suitable for an electric vehicle (or a hybrid vehicle) using two motors. In an application example of the drive device 2, the output shaft of one of the first motor 10 and the second motor 20 is connected to the front wheels, and the output shaft of the other is connected to the rear wheels.

[0043] In an electric vehicle capable of selecting four-wheel drive and two-wheel drive, an example of the flexible use of dual mode and single mode is as follows. When traveling in four-wheel drive, the controller 40 selects the single mode. Moreover, the controller 40 closes the disconnection switch 39. The controller 40 controls the first inverter 31 and the second inverter 32 respectively. That is, one of the first motor 10 and the second motor 20 drives the front wheels, and the other drives the rear wheels. The controller 40 can also select such a dual mode when traveling on a road where skidding is likely to occur. Since it is four-wheel drive, it is not easy to skid.

[0044] When traveling in two-wheel drive with high torque, the controller 40 selects the dual mode. The controller 40 controls the first inverter 31 and the second inverter 32 so that the AC output of the first inverter 31 and the AC output of the second inverter overlap at the first stator coil 11 of the first motor 10. By controlling the two inverters in this way, the first motor 10 outputs high torque with high utilization efficiency.

[0045] When traveling in two-wheel drive with low torque, the controller 40 selects the single mode. In addition, the controller 40 drives one of the first inverter 31 and the second inverter 32 and stops the other. Since only one inverter and one motor are used, the utilization efficiency of the drive device 2 becomes high.

[0046] Second Embodiment

[0047] Figure 2 The circuit diagram showing the drive device 102 of the second embodiment. In the drive device 102, the first motor 110 is different from that of the first embodiment. In the drive device 102, the structure other than the first motor 110 is the same as that of the drive device 2 of the first embodiment.

[0048] The first stator coil 111 of the first motor 110 includes a first sub-coil 111a and a second sub-coil 111b connected in series. In addition, the first motor 110 has a plurality of first stator coils 111, and each of the plurality of first stator coils 111 includes a first sub-coil 111a and a second sub-coil 111b connected in series.

[0049] The first switch 38a of the changeover switch 38 is connected between the other end of the first stator coil 111 (the first sub-coil 111a + the second sub-coil 111b) and the AC terminal of the second inverter 32. The second switch 38b is connected between the midpoint of the first sub-coil 111a and the second sub-coil 111b and the neutral point 12. In the single mode, the midpoint of the first sub-coil 111a and the second sub-coil 111b is connected to the neutral point 12. In the dual mode, the other end of the series connection of the first sub-coil 111a and the second sub-coil 111b is connected to the AC terminal of the second inverter 32. In addition, one end of the series connection of the first sub-coil 111a and the second sub-coil 111b is always connected to the AC terminal of the first inverter 31.

[0050] The case of driving the first motor 110 in the dual mode is the same as that of the first embodiment. In other words, in the dual mode, current flows through the series connection of the first sub-coil 111a and the second sub-coil 111b. In the case of driving the first motor 110 in the single mode, only current flows through the first sub-coil 111a in the first motor 110. In the single mode, the number of windings of the first stator coil 111 of the first motor 110 is reduced, so the inductance of the first motor 110 is reduced. Therefore, the first motor 110 can cope with a higher speed range.

[0051] Third Embodiment

[0052] The drive device 202 of the third embodiment will be described. The drive device 202 of the third embodiment adds an engine 204 and a planetary gear 250 to the drive device 2 of the first embodiment. In addition, the drive device 202 is used as a drive device for a hybrid vehicle.

[0053] Figure 3 A schematic diagram showing the drive device 202. In Figure 3 only the first motor 10 and the second motor 20 are drawn for the drive device 2 of the first embodiment, and other components of the drive device 2 are omitted from the illustration.

[0054] The planetary gear 250 includes a sun gear 251, a planet carrier 252, and a ring gear 253. The sun gear 251 is connected to the output shaft of the second motor 20. The planet carrier 252 is connected to the output shaft of the engine 204. The ring gear 253 is connected to the output shaft of the first motor 10. In Figure 3 the ring gear 253 is drawn to also serve as the rotor (i.e., the output shaft) of the first motor 10.

[0055] An output gear 254 is fixed to the ring gear 253, and the output gear 254 is engaged with a drive shaft 256 via an idler gear 255. A wheel (not shown) is connected to the front end of the drive shaft 256.

[0056] Figure 4 - Figure 6A nomogram representing the drive device 202. Figure 4 This is the nomogram during EV driving at low torque. "EV driving" refers to a mode where the engine is stopped and only the motor is used for driving. In contrast, "HV driving" refers to a mode where both the engine and the motor are used for driving. As can be seen from the Figure 3 schematic diagram, Figure 4 the rotational speed of the ring gear of

[0057] is proportional to the rotational speed of the axle. In the case of low torque / EV driving, the controller 40 selects the single mode. Moreover, the controller 40 stops the engine 204 and the second inverter 32, and drives the first motor 10 (the first inverter 31) (see Figure 4 ). At this time, only the output torque of the first motor 10 contributes to the total output torque of the drive device 202.

[0058] In the case of high torque / EV driving, the controller 40 selects the dual mode. Moreover, the controller 40 stops the engine 204 and drives the first motor 10 through the first inverter 31 and the second inverter 32 (see Figure 5 ). At this time, the output torques of the first motor 10 and the second motor 20 respectively contribute to the total output torque of the drive device 202.

[0059] In the case of high torque / HV driving, the controller 40 selects the single mode. The controller 40 closes the disconnection switch 39. Moreover, the controller 40 drives the engine 204, the first motor 10 (the first inverter 31), and the second motor 20 (the second inverter 32) (see Figure 6 ). The controller 40 independently controls the first motor 10 (the first inverter 31) and the second motor 20 (the second inverter 32) respectively according to the magnitude of the target torque. At this time, the output torques of the engine 204, the first motor 10, and the second motor 20 respectively contribute to the total output torque of the drive device 202. In addition, the second motor 20 may sometimes be driven in the reverse direction due to the reaction force of the driving force of the first motor 10. At this time, the second motor 20 functions as a generator to generate electricity. The electricity generated is supplied to the first inverter 31 or stored in the battery.

[0060] As described above, the drive devices 2 and 102 of the embodiment can respond from low torque to high torque with high power utilization efficiency. The drive device 202 of the third embodiment can also respond from low torque to high torque with high power utilization efficiency in the same way as the drive devices 2 and 102.

[0061] Points to note regarding the technology described in the embodiment are described. The drive device 202 of the third embodiment may also include the drive device 102 instead of the drive device 2. In addition, the drive device 202 may also be applied to machinery other than hybrid vehicles. That is,Figure 3 In this case, another driven device may be engaged with the output gear 254 instead of the drive shaft 256.

[0062] In the single mode, the controller 40 may also not use the second motor 20 (the second inverter 32). Additionally, when the second motor 20 (the second inverter 32) is not used in the single mode, the controller 40 may either close or open the disconnection switch 39. If the disconnection switch 39 is opened, the second inverter 32 is disconnected from the second motor 20, and the second motor 20 does not operate. Even if the disconnection switch 39 is closed, as long as all the switching elements of the second inverter 32 are kept open, the second motor 20 does not operate.

[0063] If the characteristics of the drive device of the embodiment are expressed in more detail, the characteristics of the drive device of the embodiment are as described below. The first motor 10 includes a plurality of first stator coils 11, and the second motor 20 includes a plurality of second stator coils 21. The first inverter 31 and the second inverter 32 each include a plurality of AC terminals. The plurality of AC terminals of the first inverter 31 are respectively connected to one end of each of the plurality of first stator coils 11. The changeover switch 38 connects the other ends of the plurality of first stator coils 11 to either the neutral point 12 or the AC terminal of the second inverter 32 and disconnects from the other. The plurality of second stator coils 21 are respectively connected to the plurality of AC terminals of the second inverter 32. The disconnection switch 39 disconnects the plurality of second stator coils 21 from the plurality of AC terminals of the second inverter 32.

[0064] In the dual mode, the controller 40 disconnects the other end of the first stator coil 11 from the neutral point 12 and connects it to the AC terminal of the second inverter 32. Additionally, the controller 40 disconnects the second stator coil 21 from the second inverter 32. In the single mode, the controller 40 connects the other end of the first stator coil 11 to the neutral point 12.

[0065] In the drive device 102 of the second embodiment, the first stator coil 111 includes a first sub-coil 111a and a second sub-coil 111b. The first sub-coil 111a and the second sub-coil 111b are connected in series. The changeover switch 38 can switch between a first state and a second state. In the first state, the midpoint of the first sub-coil 111a and the second sub-coil 111b is connected to the neutral point 12, and the first sub-coil 111a and the second sub-coil 111b are disconnected from the second inverter 32. In the second state, the other end of the first stator coil 111 (i.e., the series connection of the first sub-coil 111a and the second sub-coil 111b) is connected to the AC terminal of the second inverter 32, and the first stator coil 111 is disconnected from the neutral point 12. The first state corresponds to the single mode, and the second state corresponds to the dual mode. As described above, in the dual mode, the disconnection switch 39 is opened.

[0066] As described above, specific examples of the present invention have been explained in detail. However, these are merely illustrative and do not limit the claims. The technology described in the claims includes technologies obtained by various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or through various combinations, and are not limited to the combinations recited in the claims at the time of filing. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and has technical utility by achieving one of these purposes itself.

Claims

1. A driving device, wherein: The driving device comprises: A first motor, the first motor having a first stator coil; a second motor, the second motor having a second stator coil; a first inverter connected to the first stator coil; a second inverter connected to the second stator coil; a switching switch, wherein the switching switch connects the first stator coil to either a neutral point or the second inverter; a disconnect switch, the disconnect switch disconnecting the second stator coil from the second inverter; as well as a controller, wherein the controller controls the switching switch and the circuit breaker, The controller switches between a dual mode and a single mode. In the dual mode, the first stator coil is connected to the second inverter through the switching switch and the circuit breaker is opened. In the single mode, the first stator coil is connected to the neutral point through the switching switch.

2. The driving device according to claim 1, wherein: The first stator coil includes a first sub-coil and a second sub-coil connected in series, The switch connects a middle point between the first sub-coil and the second sub-coil to the neutral point.

3. The driving device according to claim 1 or 2, wherein: The drive device further includes an engine and a planetary gear. The first motor is connected to the ring gear of the planetary gear. The second motor is connected to the sun gear of the planetary gear. The engine is connected to the planetary carrier of the planetary gear.

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