Drive device

Abstract

To provide a drive device of a wide application range by improving a two-motor / two-inverter drive device so as to be utilized also as a dual inverter.SOLUTION: A drive device disclosed in the present description comprises a first motor including a first stator coil, a second motor including a second stator coil, a first inverter, a second inverter, a changeover switch, a cut-off switch, and a controller. The first inverter is connected to the first stator coil, and the second inverter is connected to the second stator coil. The changeover switch connects the first stator coil to any one of a neutral point of the second inverter. The cut-off switch disconnects the second stator coil from the second inverter. The controller is capable of switching a dual mode, in which the first stator coil is connected to the second inverter and the cut-off switch is opened, and a single mode in which the first stator coil is connected to the neutral point.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] An open winding type motor in which two inverters are connected to one motor is known. One end of the stator coil of the open winding type motor is connected to a first inverter, and the other end is connected to a second inverter. A drive device in which two inverters are connected to one open winding type motor is sometimes called a dual inverter type. The dual inverter type can increase the voltage applied to the stator coil compared to a drive device that uses one inverter. The dual inverter type can output high torque with high utilization efficiency. Here, high utilization efficiency means low power loss. Patent Document 1 illustrates an example of a dual inverter type drive device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-25679 A Summary of the Invention [Problem to be solved by the invention]

[0004] In electric vehicles and hybrid vehicles, a drive system (two-motor / two-inverter drive system) that has two motors and two inverters connected to each motor is known. In a conventional two-motor / two-inverter drive system, each inverter drives each motor independently. 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.

[0005] This specification improves the two-motor / two-inverter drive device so that it can also be used as a dual inverter, providing a drive device with a wide range of applications. [Means for solving the problem]

[0006] The driving 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 cutoff switch, and a controller. The first inverter is connected to the first stator coil, and the second inverter is connected to the second stator coil. The changeover switch connects the first stator coil to either a neutral point or the second inverter. The cutoff switch can disconnect the second stator coil from the second inverter. The controller controls the changeover switch and the cutoff switch. The controller can switch between a dual mode in which the changeover switch connects the first stator coil to the second inverter and opens the cutoff switch, and a single mode in which the changeover switch connects the first stator coil to the neutral point. In the single mode, the cutoff switch may be either open or closed.

[0007] In the single mode, the controller 40 can control the first motor (first inverter) and the second motor (second inverter) separately. The single mode corresponds to a conventional two-motor / two-inverter type drive device. In the 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 the 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 for both the two-motor / two-inverter type and the dual-inverter type. The drive device disclosed in this specification has a wide range of applications. In other words, the drive device disclosed in this specification has good power utilization efficiency.

[0008] The first stator coil of the first motor may include a first sub-coil and a second sub-coil connected in series. In this case, the changeover switch may be configured to connect a midpoint between the first sub-coil and the second sub-coil to a neutral point. When the first stator coil is connected to the second inverter, an end of the series connection of the first sub-coil and the second sub-coil is connected to the second inverter. In the dual mode, the first sub-coil and the second sub-coil are used, and in the single mode, only the first sub-coil is used. In the dual mode, a high torque is obtained. In the single mode, the number of turns of the coil used is reduced, so that the inductance of the first motor is reduced, and as a result, the loss in the high rotation range is reduced.

[0009] The drive device disclosed in this specification may further include an engine and a planetary gear. A first motor is connected to a ring gear of the planetary gear, and a second motor is connected to a sun gear of the planetary gear. An engine is connected to a carrier of the planetary gear. If the dual mode is selected and the engine is stopped, high torque is obtained in EV mode. If the single mode is selected and the engine and the second motor are stopped, the output torque is low but high utilization efficiency is obtained. If the single mode is selected and the engine is operated and the first motor and the second motor are operated, it becomes equivalent to a conventional hybrid system.

[0010] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a circuit diagram of a drive device according to the first embodiment. [Diagram 2] FIG. 11 is a circuit diagram of a drive device according to a second embodiment. [Diagram 3] FIG. 11 is a block diagram of a drive device according to a third embodiment. [Figure 4] FIG. 11 is a collinear diagram of the drive system of the third embodiment (single mode / low torque EV driving). [Diagram 5]FIG. 11 is a collinear diagram of a drive system according to a third embodiment (dual mode / high torque EV driving). [Figure 6] FIG. 11 is a collinear diagram of the drive system of the third embodiment (single mode / high torque HV running). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) FIG. 1 shows a circuit diagram of a drive device 2 of a first embodiment. 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 cutoff switch 39, and a controller 40. In the drive device 2, each of the first motor 10 and the second motor 20 can output torque, and one of the first motor 10 and the second motor 20 can be stopped and torque can be output from the other. The drive device 2 having two motor output shafts is applied to an electric vehicle or a hybrid vehicle. 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 an engine are linked to the wheels via planetary gears. A drive device 202 suitable for a hybrid vehicle will be described later.

[0013] The first inverter 31 includes three sets of two switching elements connected in series. The three sets of series connections are connected in parallel to a DC power supply 50. The switching elements are controlled by a controller 40. The dotted arrows in FIG. 1 indicate signal lines. When the controller 40 appropriately turns on and off the six switching elements, AC is output from the midpoint of the series connections. The second inverter 32 has the same circuit structure as the first inverter 31. The three sets of series connections of the second inverter 32 are also connected in parallel to a DC power supply 50. The structure of an inverter is well known, so a detailed description will be omitted.

[0014] Both the first motor 10 and the second motor 20 are three-phase AC motors. The 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 each of the three AC terminals of the first inverter 31 is connected to one end of each of the three first stator coils 11. The other end of the first stator coil 11 is 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. When the first switch 38a is closed, each of the first stator coils 11 is connected to each of the AC terminals of the second inverter 32. When the first switch 38a is opened, the first stator coil 11 is disconnected from the second inverter 32. When the second switch 38b is closed, each of the first stator coils 11 is connected to the neutral point 12. The other ends of the multiple first stator coils 11 are connected to each other at the neutral point 12. When 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.

[0015] The controller 40 is configured such that when one of the first switch 38a and the second switch 38b 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 end of the second inverter 32.

[0016] The three AC terminals of the second inverter 32 are connected to the second motor 20. The second motor 20 is equipped with three second stator coils 21, and each AC terminal of the second inverter 32 is connected to one end of each of the three second stator coils 21. The other ends of the multiple second stator coils 21 are connected to each other at a neutral point 22. A cutoff switch 39 is connected between the AC terminal of the second inverter 32 and the second stator coil 21. When the cutoff switch 39 is opened, the second motor 20 is cut off from the second inverter 32.

[0017] The controller 40 controls the changeover switch 38 and the cutoff switch 39. The controller 40 closes the first switch 38a of the changeover switch 38, opens the second switch 38b, and opens the cutoff switch 39. At this time, the other end of the first stator coil 11 of the first motor 10 is connected to the AC end of the second inverter 32, and the second motor 20 is cut off from the second inverter 32. This state is hereinafter referred to as a dual mode. At this time, the neutral point 12 is cut off from the first stator coil 11.

[0018] Further, the controller 40 opens the first switch 38a and closes the second switch 38b of the changeover switch 38. 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. This state is hereinafter referred to as a single mode. In addition, in the single mode, the disconnecting switch 39 may be closed or open. When the disconnecting 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 individually.

[0019] The controller 40 selects either the dual mode or the single mode. In the dual mode, the AC end of the first inverter 31 is connected to one end of the first stator coil 11, and the AC end of the second inverter 32 is connected to the other end of the first stator coil 11. When 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 high torque. The output of the first motor 10 at this time is larger than the output when one motor is driven by one inverter. The control rules for the two inverters in the dual mode may use known techniques.

[0020] In the dual mode, high torque can be obtained with high efficiency. Here, high efficiency means low power loss when the motor is driven. In the dual mode, the second motor 20 cannot be used.

[0021] In the single mode, the AC end 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 end of the second inverter 32. When the disconnection switch 39 is closed, the AC end 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 individually. In the single mode, the maximum output torque of the first motor 10 is lower than that in the dual mode, but the single mode can drive two motors with high utilization efficiency.

[0022] The drive unit 2 of the first embodiment can obtain output torque with high utilization efficiency from low to high torque ranges by switching between dual mode and single mode. The drive unit 2 can switch between dual mode and single mode, which expands the range of application. In other words, the drive unit 2 has good power utilization efficiency.

[0023] The drive unit 2 is suitable for an electric vehicle (or a hybrid vehicle) that uses two motors. In one application example of the drive unit 2, one of the output shafts of the first motor 10 and the second motor 20 is connected to the front wheels, and the other output shaft is connected to the rear wheels.

[0024] In an electric vehicle that can select between four-wheel drive and two-wheel drive, an example of how to use the dual mode and the single mode is as follows. When traveling in four-wheel drive, the controller 40 selects the single mode. The controller 40 then closes the cutoff 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 may select such a dual mode when traveling on a road that is prone to slipping. Because it is four-wheel drive, it is less likely to slip.

[0025] When traveling with two-wheel drive and 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 are overlapped 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.

[0026] When the vehicle is driven in two-wheel drive and with low torque, the controller 40 selects the single mode. 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 unit 2 is increased.

[0027] Second Embodiment Fig. 2 shows a circuit diagram of a driving device 102 of a second embodiment. The driving device 102 differs from the first embodiment in the first motor 110. The configuration of the driving device 102 other than the first motor 110 is the same as that of the driving device 2 of the first embodiment.

[0028] 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. 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.

[0029] The first switch 38a of the changeover switch 38 is connected between the other end of the first stator coil 111 (first subcoil 111a+second subcoil 111b) and the AC end of the second inverter 32. The second switch 38b is connected between the midpoint of the first subcoil 111a and the second subcoil 111b and the neutral point 12. In the single mode, the midpoint of the first subcoil 111a and the second subcoil 111b is connected to the neutral point 12. In the dual mode, the other end of the series connection of the first subcoil 111a and the second subcoil 111b is connected to the AC end of the second inverter 32. Note that one end of the series connection of the first subcoil 111a and the second subcoil 111b is always connected to the AC end of the first inverter 31.

[0030] The case where the first motor 110 is driven in the dual mode is the same as the case of the first embodiment. In other words, in the dual mode, a current flows through the series connection of the first sub-coil 111a and the second sub-coil 111b. When the first motor 110 is driven in the single mode, a current flows only through the first sub-coil 111a in the first motor 110. In the single mode, the number of windings in the first stator coil 111 of the first motor 110 is reduced, and therefore the inductance of the first motor 110 is reduced. Therefore, the first motor 110 can handle a higher rotation speed range.

[0031] (Third embodiment) A drive unit 202 of a third embodiment will be described. The drive unit 202 of the third embodiment is obtained by adding an engine 204 and a planetary gear 250 to the drive unit 2 of the first embodiment. The drive unit 202 is also used as a drive unit for a hybrid vehicle.

[0032] Fig. 3 shows a skeleton diagram of the driving device 202. In Fig. 3, only the first motor 10 and the second motor 20 of the driving device 2 of the first embodiment are illustrated, and other components of the driving device 2 are omitted from the illustration.

[0033] The planetary gear 250 includes a sun gear 251, a carrier 252, and a ring gear 253. The sun gear 251 is connected to the output shaft of the second motor 20. The 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 FIG. 3, the ring gear 253 is depicted as also serving as the rotor (i.e., the output shaft) of the first motor 10.

[0034] 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 idle gear 255. A wheel (not shown) is connected to the end of the drive shaft 256.

[0035] Fig. 4 to Fig. 6 show nomograms of the drive unit 202. Fig. 4 shows a nomogram when the vehicle is running in EV mode with low torque. "EV running" refers to a mode in which the engine is stopped and the vehicle runs only on the motor. In contrast, "HV running" refers to a mode in which the vehicle runs using both the engine and the motor. As can be seen from the skeleton diagram in Fig. 3, the rotation speed of the ring gear in Fig. 4 is proportional to the rotation speed of the axle.

[0036] In the case of low torque / EV driving, the controller 40 selects the single mode. Then, the controller 40 stops the engine 204 and the second inverter 32, and drives the first motor 10 (first inverter 31) (see FIG. 4). At this time, only the output torque of the first motor 10 contributes to the total output torque of the drive device 202.

[0037] In the case of high torque / EV driving, the controller 40 selects the dual mode. Then, the controller 40 stops the engine 204 and drives the first motor 10 with the first inverter 31 and the second inverter 32 (see FIG. 5). At this time, the output torques of the first motor 10 and the second motor 20 each contribute to the total output torque of the drive device 202.

[0038] In the case of high torque / HV running, the controller 40 selects the single mode. The controller 40 closes the cutoff switch 39. Then, 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 FIG. 6). The controller 40 controls the first motor 10 (the first inverter 31) and the second motor 20 (the second inverter 32) independently 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 contribute to the total output torque of the drive device 202. Note that the second motor 20 may be reverse-driven by receiving a reaction force of the driving force of the first motor 10. At this time, the second motor 20 functions as a generator and generates electricity. The generated electricity is supplied to the first inverter 31 or stored in a battery.

[0039] As described above, the driving devices 2 and 102 of the embodiments can handle torques from low to high with high power utilization efficiency. The driving device 202 of the third embodiment can also handle torques from low to high with high power utilization efficiency, similar to the driving devices 2 and 102.

[0040] Points to note regarding the technology described in the embodiment will be described. The driving device 202 of the third embodiment may include the driving device 102 instead of the driving device 2. The driving device 202 may also be applied to machines other than hybrid vehicles. That is, in FIG. 3, another driven device may be engaged with the output gear 254 instead of the drive shaft 256.

[0041] In the single mode, the controller 40 may not use the second motor 20 (second inverter 32). Furthermore, when the second motor 20 (second inverter 32) is not used in the single mode, the controller 40 may either close or open the cutoff switch 39. When the cutoff switch 39 is open, the second inverter 32 is cut off from the second motor 20, and the second motor 20 does not operate. Even if the cutoff switch 39 is closed, if all switching elements of the second inverter 32 are kept off, the second motor 20 does not operate.

[0042] The features of the driving device of the embodiment are described in more detail 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. Each of the plurality of AC terminals of the first inverter 31 is connected to one end of each of the plurality of first stator coils 11. The changeover switch 38 connects the other end of each 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 it from the other. The plurality of second stator coils 21 are connected to each of the plurality of AC terminals of the second inverter 32. The cutoff switch 39 cuts off each of the plurality of second stator coils 21 from each of the plurality of AC terminals of the second inverter 32.

[0043] 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 end of the second inverter 32. The controller 40 also disconnects the second stator coil 21 from the second inverter 32. In the single 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 end of the second inverter 32.

[0044] In the driving 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 end 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 cutoff switch 39 is opened.

[0045] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0046] 2, 102, 202: Drive unit 10, 110: First motor 11, 111: First stator coil 12, 22: Neutral point 20: Second motor 21: Second stator coil 31: First inverter 32: Second inverter 38: Changeover switch 38a: First switch 38b: Second switch 39: Cutoff switch 40: Controller 50: DC power supply 111a: First sub-coil 111b: Second sub-coil 204: Engine 250: Planetary gear 251: Sun gear 252: Carrier 253: Ring gear 254: Output gear 255: Idle gear 256: Drive shaft

Claims

1. a first motor having a first stator coil; a second motor including a second stator coil; a first inverter connected to the first stator coil; a second inverter connected to the second stator coil; a changeover switch that connects the first stator coil to either a neutral point or the second inverter; a cutoff switch that disconnects the second stator coil from the second inverter; A controller for controlling the changeover switch and the cutoff switch; It is equipped with The controller switches between a dual mode in which the changeover switch connects the first stator coil to the second inverter and opens the cutoff switch, and a single mode in which the changeover switch connects the first stator coil to the neutral point.

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

3. It also has an engine and planetary gears. The first motor is connected to a ring gear of the planetary gear, The second motor is connected to a sun gear of the planetary gear, The engine is connected to the carrier of the planetary gear.

3. The drive device according to claim 1 or 2.

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