Vehicular drive device

Abstract

According to the present invention, when there has been a heat generation request, a vehicle is stopped, and a start determination unit has determined that a start is possible, a control device implements a first heat generation mode in which a drive transmission mechanism is put into a transmission state, an inverter is operated so as not to cause a rotor to rotate, and the inverter and a rotary electric machine are energized to cause the inverter and the rotary electric machine to generate heat, but when there has been a heat generation request, the vehicle is stopped, and the start determination unit has determined that a start is not possible, the control device implements a second heat generation mode in which the drive transmission mechanism is put into a non-transmission state, the inverter is operated so as to cause the rotor to rotate, and the inverter and the rotary electric machine are energized to cause the inverter and the rotary electric machine to generate heat.

Description

Vehicle drive device

[0001] The present invention relates to a vehicle drive device including a rotating electric machine, an inverter that controls the rotating electric machine, a drive transmission mechanism that transmits the driving force of the rotating electric machine to wheels, and a control device that controls the inverter and the drive transmission mechanism.

[0002] Japanese Unexamined Patent Application Publication No. 2020-114137 (Patent Document 1) discloses a warm-up control device for a vehicle. The warm-up control device for a vehicle in Patent Document 1 includes a motor, an inverter, a cooling water circuit through which cooling water for cooling the inverter circulates, and a control unit that controls the inverter. When there is a warm-up request, the control unit is configured to execute warm-up control for recovering heat generated in the inverter by energization with cooling water and supplying it to a device that requires warm-up. In Patent Document 1, when the inverter is energized while the motor is not rotating during a stop, current concentrates in a specific phase among the U phase, V phase, and W phase, and as a result, it is described as a problem that the current value of the inverter needs to be reduced so as not to exceed the cooling limit, resulting in insufficient heat quantity. And a technique for suppressing such insufficient heat quantity is disclosed in Patent Document 1.

[0003] Japanese Unexamined Patent Application Publication No. 2020-114137

[0004] By the way, in a vehicle stop state where the vehicle is stopped, the vehicle may continue to stop for some time thereafter, or the vehicle may start soon thereafter. And in the latter case, it is desirable that the vehicle can be started quickly. Therefore, when executing a heat generation mode in which the inverter and the rotating electric machine are heated by energizing the inverter and the rotating electric machine in a vehicle stop state, it is desired not only to easily ensure an appropriate amount of heat generation, but also to be able to quickly start the vehicle when the vehicle starts. However, Patent Document 1 does not describe this point.

[0005] Therefore, when executing the heat generation mode in a vehicle stop state, it is desired to realize a technology that can easily ensure an appropriate amount of heat generation and can quickly start the vehicle as needed.

[0006] The vehicle drive system according to this disclosure comprises a rotating electric machine with a rotor, an inverter for controlling the rotating electric machine, a drive transmission mechanism for transmitting the driving force of the rotating electric machine to the wheels, and a control device for controlling the inverter and the drive transmission mechanism, wherein the drive transmission mechanism is configured to change between a transmission state in which the driving force of the rotating electric machine is transmitted to the wheels and a non-transmission state in which the driving force of the rotating electric machine is not transmitted to the wheels, and the control device includes a starting determination unit for determining whether or not the vehicle can start when the vehicle is stopped, and the state in which there is a demand for heat generation by the vehicle is defined as a heat generation demand state, and the control device determines whether or not the vehicle can start when the heat generation demand state and the vehicle If the vehicle is stopped and the starting determination unit determines that there is a possibility of starting, the drive transmission mechanism is set to the transmission state, and the inverter is operated so as not to rotate the rotor, thereby energizing the inverter and the rotating electric machine to execute a first heat generation mode that generates heat in the inverter and the rotating electric machine. If the heat generation request state is met and the vehicle is stopped, and the starting determination unit determines that there is no possibility of starting, the drive transmission mechanism is set to the non-transmission state, and the inverter is operated so as to rotate the rotor, thereby energizing the inverter and the rotating electric machine to execute a second heat generation mode that generates heat in the inverter and the rotating electric machine.

[0007] With this configuration, heat generation can be performed even when the vehicle is stopped in either the first or second heat generation mode. When it is determined that there is a possibility of the vehicle starting, the first heat generation mode, in which the drive transmission mechanism is in a transmission state, is executed, allowing the vehicle to start quickly when it is about to start. When it is determined that there is no possibility of the vehicle starting, the second heat generation mode, in which the drive transmission mechanism is in a non-transmission state and the rotor rotates, is executed, which can minimize the uneven distribution of heat generation among the phases in the inverter and rotating electric machine. Therefore, it is possible to increase the amount of heat generated while protecting the inverter and rotating electric machine, and it is easier to ensure an appropriate amount of heat generation. In addition, in the second heat generation mode, it is also possible to increase the amount of heat generated by utilizing the heat generated due to the frictional resistance of the drive transmission mechanism (including the resistance of oil stirring due to friction with the oil) in the range in which the rotation of the rotor is transmitted.

[0008] As described above, this configuration makes it easier to ensure an appropriate amount of heat is generated when the heat generation mode is executed while the vehicle is stopped, and also allows the vehicle to be started quickly when necessary.

[0009] Further features and advantages of the vehicle drive system will become clear from the following description of the embodiments described with reference to the drawings.

[0010] A schematic diagram showing an example of a vehicle equipped with a vehicle drive system. A diagram showing an example of the arrangement configuration of the separation mechanism. A diagram showing another example of the arrangement configuration of the separation mechanism. A diagram showing an example of the inverter control system. A diagram explaining current vectors. A flowchart showing an example of the heat generation mode selection process. A time chart showing an example of the control behavior when the second heat generation mode is executed. A time chart showing another example of the control behavior when the second heat generation mode is executed. A flowchart showing an example of fail-safe processing. A flowchart showing another example of fail-safe processing.

[0011] Embodiments of vehicle drive systems will be described with reference to the drawings. In this specification, the term "rotating electric machine" is used as a concept that includes motors, generators, and, if necessary, motor-generators that perform both motor and generator functions.

[0012] The vehicle 100 on which the vehicle drive unit 10 is installed is an electric vehicle equipped with a rotating electric motor 4 as a driving force source for the wheels W, such as a battery electric vehicle (BEV). The vehicle drive unit 10 transmits the driving force of the rotating electric motor 4 to the wheels W to move the vehicle 100. Figure 1 illustrates a case in which the vehicle drive unit 10 is configured to transmit only the driving force of the rotating electric motor 4 to the wheels W. Another driving force source (for example, an internal combustion engine) may be provided in the vehicle 100, and the vehicle drive unit 10 may be configured to transmit the driving force of this other driving force source to the wheels W as well.

[0013] As shown in Figures 1 and 4, the vehicle drive system 10 includes a rotating electric machine 4 equipped with a rotor 41, an inverter 7 that controls the rotating electric machine 4, a drive transmission mechanism 5 that transmits the driving force of the rotating electric machine 4 to the wheels W, and a control device 1 that controls the inverter 7 and the drive transmission mechanism 5. The control device 1 controls the rotating electric machine 4 via the inverter 7.

[0014] The rotating electric machine 4 is electrically connected to a DC power source 6 (see Figure 4), such as a battery or capacitor, via an inverter 7. The rotating electric machine 4 generates driving force by operating using the power stored in the DC power source 6. The rotating electric machine 4 also charges the DC power source 6 by generating electricity using the driving force transmitted to it (for example, the driving force transmitted from the wheel W).

[0015] The rotating electric machine 4 includes a stator 42, and the rotor 41 is rotatably supported by a non-rotating member (for example, a case housing the rotating electric machine 4) relative to the stator 42. The rotor 41 is fixed to the rotor shaft 40 and rotates integrally with the rotor shaft 40. Coils 43 (stator coils) are wound around the stator 42. In this embodiment, the rotating electric machine 4 is a rotating electric machine driven by three-phase alternating current, and three-phase coils 43 are wound around the stator 42. Figure 4 illustrates a configuration in which the three-phase coils 43 are connected in a star configuration.

[0016] In this embodiment, the rotating electric machine 4 is a permanent magnet type synchronous rotating electric machine (PMSM), and the rotor 41 is equipped with permanent magnets (not shown). The rotating electric machine 4 may be a synchronous rotating electric machine other than a permanent magnet type. For example, an electrically excited synchronous rotating electric machine (EESM) can be used as the rotating electric machine 4, in which case coils (rotor coils) are wound around the rotor 41. Furthermore, the rotating electric machine 4 may be an induction rotating electric machine instead of a synchronous rotating electric machine.

[0017] The drive transmission mechanism 5 includes, for example, a transmission shaft and gears. The drive transmission mechanism 5 may also include engagement devices such as a clutch and a brake. The drive transmission mechanism 5 transmits the driving force of the rotating electric machine 4 to the wheels W connected to the output shaft 59 (drive shaft) via the output shaft 59. The drive transmission mechanism 5 is configured to transmit the driving force of the rotating electric machine 4 to one or more wheels W.

[0018] The configuration of the drive transmission mechanism 5 is not limited to the form shown in Figure 1, but in the example shown in Figure 1, the drive transmission mechanism 5 is configured to transmit the driving force of the rotating electric machine 4 to a pair of wheels W (left and right wheels W). Therefore, in the example shown in Figure 1, the drive transmission mechanism 5 includes a differential gear mechanism 55 that distributes the rotation transmitted from the rotating electric machine 4 to a pair of wheels W via a pair of output shafts 59. In addition, in the example shown in Figure 1, the drive transmission mechanism 5 includes a transmission 50 that changes the speed of the rotation transmitted from the rotating electric machine 4 and transmits it to the differential gear mechanism 55. The transmission 50 is, for example, a reduction gear such as a parallel shaft gear type or a planetary gear type. In Figure 1, a configuration in which the rotating electric machine 4 is arranged on a different axis from the output shaft 59 is illustrated, but it is also possible to configure the rotating electric machine 4 to be arranged coaxially with the output shaft 59.

[0019] The drive transmission mechanism 5 is configured to change between a transmission state in which the driving force of the rotating electric machine 4 is transmitted to the wheel W, and a non-transmission state in which the driving force of the rotating electric machine 4 is not transmitted to the wheel W. Specifically, the drive transmission mechanism 5 includes a disconnection mechanism 51 (see Figures 2 and 3) provided in the power transmission path between the rotating electric machine 4 and the wheel W, which can disconnect the rotating electric machine 4 from the wheel W. The disconnection mechanism 51 selectively interrupts the power transmission path between the rotating electric machine 4 and the wheel W. When the power transmission path between the rotating electric machine 4 and the wheel W is connected and not interrupted by the disconnection mechanism 51, the drive transmission mechanism 5 is in a transmission state, and when the power transmission path is interrupted by the disconnection mechanism 51, the drive transmission mechanism 5 is in a non-transmission state. The state of the drive transmission mechanism 5 (specifically, the state of the disconnection mechanism 51) is controlled by the control device 1. While the vehicle 100 is running, the drive transmission mechanism 5 is basically in a transmission state.

[0020] In the simplified diagrams shown in Figures 2 and 3, the lines connecting the DC power supply 6 and the rotating electric machine 4 via the inverter 7 represent the power transmission path, and the lines connecting the rotating electric machine 4 and the output shaft 59 via the drive transmission mechanism 5 represent the power (torque) transmission path. The disconnection mechanism 51 may be provided at any position that allows the drive transmission mechanism 5 to change between a transmission state and a non-transmission state. In the example shown in Figure 2, the disconnection mechanism 51 is provided in the power transmission path between the transmission 50 and the output shaft 59. When the arrangement configuration of the disconnection mechanism 51 shown in Figure 2 is applied to the vehicle drive system 10 illustrated in Figure 1, the disconnection mechanism 51 is provided, for example, in the power transmission path between the transmission 50 and the differential gear mechanism 55. In the example shown in Figure 3, the disconnection mechanism 51 is provided in the power transmission path between the rotating electric machine 4 and the transmission 50. When the arrangement configuration of the disconnection mechanism 51 shown in Figure 3 is applied to the vehicle drive system 10 illustrated in Figure 1, the disconnection mechanism 51 is provided, for example, in the power transmission path between the rotor shaft 40 and the transmission 50.

[0021] As the disengagement mechanism 51, for example, an engagement device (clutch) such as a friction engagement device or a meshing engagement device can be used. In this case, the drive transmission mechanism 5 changes state between a transmission state and a non-transmission state by engaging and disengaging the engagement device. The engagement device may be a brake or a one-way clutch. Furthermore, the disengagement mechanism 51 may be composed of a combination of multiple devices, such as a combination of an engagement device and a planetary gear mechanism.

[0022] As shown in Figure 4, the inverter 7 is configured to convert power between DC and multi-phase (three-phase in this embodiment) AC. The inverter 7 generates AC power to be supplied to the rotating electric machine 4. The inverter 7 is composed of multiple switching elements. Power transistors such as IGBTs (Insulated Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), and HEMTs (High Electron Mobility Transistors) are used as switching elements. The inverter 7 has multiple arms, each composed of a series circuit of an upper switching element and a lower switching element. Multiple arms are connected in parallel to form a bridge circuit. In the example shown in Figure 4, the inverter 7 has one arm corresponding to each of the three phases, and the three arms are connected in parallel to form a bridge circuit.

[0023] The midpoints of each arm of the inverter 7 (the connection points between the upper and lower switching elements) are connected to a coil 43, and the inverter 7 supplies multi-phase (three-phase in this embodiment) AC power to the coil 43. A DC link capacitor 63 (smoothing capacitor) is provided on the DC side of the inverter 7 (i.e., between the inverter 7 and the DC power supply 6) to smooth the voltage on the DC side of the inverter 7. A contactor 60, which is composed of a relay or the like, is also provided on the DC side of the inverter 7. The contactor 60 is positioned between the DC link capacitor 63 and the DC power supply 6. When the contactor 60 is closed (on), the DC power supply 6 and the inverter 7 are electrically connected, and when the contactor 60 is open (off), the electrical connection between the DC power supply 6 and the inverter 7 is interrupted. The on / off state of the contactor 60 is controlled by the control device 1 or another device (for example, a vehicle control device that controls the entire vehicle 100 in an integrated manner).

[0024] The vehicle drive system 10 is configured to generate the necessary heat in the vehicle 100 using the inverter 7 and the rotating electric machine 4. The heat generated by the inverter 7 and the rotating electric machine 4 is used in heat utilization equipment installed in the vehicle 100 (for example, a heating system in the passenger compartment or a temperature controller for a DC power source 6 such as a battery). In other words, the inverter 7 and the rotating electric machine 4 are used as heat sources for heat utilization equipment.

[0025] Although details are omitted, the vehicle drive system 10 is equipped with a heat transfer medium circuit through which a heat transfer medium (heat exchange medium) circulates. The heat transfer medium may be a water-based heat transfer medium or a non-water-based (for example, fluorine-based) heat transfer medium. An example of a water-based heat transfer medium is antifreeze (cooling water) called LLC (Long Life Coolant). The heat transfer medium circuit is arranged so as to pass through a first heat exchange section where heat exchange takes place between the heat transfer medium and the rotating electric machine 4, a second heat exchange section where heat exchange takes place between the heat transfer medium and the inverter 7, and a third heat exchange section where heat exchange takes place between the heat transfer medium and the heat utilization equipment. Heat is transferred from the rotating electric machine 4 to the heat transfer medium by heat exchange in the first heat exchange section, heat is transferred from the inverter 7 to the heat transfer medium by heat exchange in the second heat exchange section, and heat is transferred from the heat transfer medium to the heat utilization equipment by heat exchange in the third heat exchange section.

[0026] Furthermore, the heat exchange between the heat transfer medium and the objects to be heated (in this case, the rotating electric machine 4, the inverter 7, and the heat utilization equipment) in the heat exchange section may be carried out directly or indirectly (for example, via another heat transfer medium such as oil or gas). For example, when the rotating electric machine 4 is cooled by oil, the first heat exchange section can be configured to perform heat exchange between the heat transfer medium and the oil. In this case, the heat exchange between the heat transfer medium and the rotating electric machine 4 in the first heat exchange section is carried out indirectly via the oil.

[0027] The control device 1 controls the switching of an inverter 7, which is composed of multiple switching elements, to cause the inverter 7 to convert power between DC and multi-phase (three-phase in this embodiment) AC. The control device 1 is composed of logic circuits such as a microcomputer as its core component. Each function of the control device 1 (for example, the function of the launch determination unit 2, which will be described later) is realized through the cooperation of hardware such as a microcomputer and software (program). The control mode of the inverter 7 by the control device 1 is not limited to the following, but the control mode of the inverter 7 in this embodiment will be described below.

[0028] The control device 1 controls the rotating electric machine 4 via the inverter 7 by vector control using an orthogonal vector coordinate system consisting of a d-axis aligned with the direction of the magnetic field (direction of magnetic flux) of the rotor 41 and a q-axis perpendicular to the d-axis. When the rotating electric machine 4 is a permanent magnet type synchronous rotating electric machine, as in this embodiment, or when the rotating electric machine 4 is a wound field type synchronous rotating electric machine, the direction of the field magnetic flux is the d-axis. Also, when the rotating electric machine 4 is an induction rotating electric machine, the direction of the secondary magnetic flux generated in the rotor 41 is the d-axis.

[0029] The control device 1 controls the rotating electric machine 4 via the inverter 7 so that the rotating electric machine 4 outputs a target torque. Here, the target torque is the target output torque of the rotating electric machine 4. The torque that is required to be transmitted to the wheel W is defined as the wheel requirement torque, and the target torque is set to, for example, the torque obtained by converting the wheel requirement torque into torque at the rotating electric machine 4 (specifically, the torque obtained by dividing the wheel requirement torque by the total gear ratio of the power transmission path from the rotating electric machine 4 to the wheel W). The target torque is determined by the control device 1, or by another device that can communicate with the control device 1 (for example, the vehicle control device described above). In the latter case, the target torque determined by the other device is provided to the control device 1.

[0030] The target torque is the torque requested by the vehicle 100. The target torque is determined, for example, in response to driving operations by the driver, or in response to commands from a system such as a driver assistance system or an autonomous driving system. The vehicle 100 is equipped with sensors that detect information necessary to determine the target torque. For example, the vehicle 100 is equipped with sensors that detect driving operations by the driver (accelerator operation, brake operation, steering operation, etc.) and sensors that detect the vehicle status (vehicle speed of the vehicle 100, acceleration of the vehicle 100, etc.).

[0031] The control device 1 is configured to perform a current determination process and a PWM signal generation process. The current determination process is a process that determines the d-axis current Id and the q-axis current Iq according to the target torque. In this embodiment, in the current determination process, the d-axis current Id and the q-axis current Iq are determined by normal control or inefficient control, which will be described later. The d-axis current Id and the q-axis current Iq are two-phase currents in a dq-axis orthogonal coordinate system. Specifically, the d-axis current Id is the d-axis component of the current vector representing the current (in this embodiment, the armature current) flowing through the rotating electric machine 4 (specifically, the coil 43), and the q-axis current Iq is the q-axis component of the said current vector. That is, the composite vector Idq of the d-axis current Id and the q-axis current Iq (see Figure 5) is the current vector described above.

[0032] The control device 1 selectively executes normal control and inefficient control in the current determination process. In this embodiment, normal control is maximum torque control, which determines the phase (current phase) of the composite vector Idq so that the output torque of the rotating electric machine 4 is maximized for the same current. Maximum torque control makes it possible to generate the target torque with the minimum current (composite vector Idq of the minimum magnitude). Normal control may be a control other than maximum torque control. Maximum efficiency control can be exemplified as a control other than maximum torque control. While maximum torque control is a control that determines the composite vector Idq so that the current is minimized for the same output torque, maximum efficiency control is a control that determines the composite vector Idq so that the loss is minimized for the same output torque.

[0033] Inefficient control is a control method that increases the losses of the rotating electric machine 4 compared to normal control. Specifically, in inefficient control, the magnitude of the composite vector Idq of the d-axis current Id and the q-axis current Iq for the same target torque is increased compared to normal control. A specific example of the operating point of the rotating electric machine 4 in inefficient control will be explained with reference to Figure 5. Figure 5 shows the equitorque line L1, the maximum torque control line L2, the voltage limit ellipse L3, and the current limit circle L4. The equitorque line L1 represents the trajectory of the composite vector Idq that the rotating electric machine 4 outputs to a certain target torque. The maximum torque control line L2 represents the trajectory of the composite vector Idq determined by maximum torque control. The voltage limit ellipse L3 represents the limit determined according to the DC voltage of the inverter 7 (the voltage of the DC power supply 6 in the example shown in Figure 4) and the rotational speed of the rotating electric machine 4. The current limit circle L4 represents the limit determined according to the rated current of the rotating electric machine 4. The operating point of the rotating electric machine 4 must be inside the voltage-limiting ellipse L3 and the current-limiting circle L4.

[0034] In this embodiment, under normal control, the operating point of the rotating electric machine 4 is determined by maximum torque control. Therefore, in Figure 5, the intersection of the equitorque line L1 and the maximum torque control line L2 becomes the operating point (first operating point P1) under normal control. That is, the d-axis current Id and q-axis current Iq at the first operating point P1 become the d-axis current Id and q-axis current Iq that are determined according to the target torque under normal control.

[0035] In inefficient control, the operating point of the rotating electric machine 4 is determined to be a point different from the first operating point P1 on the equitorque line L1 (a point with a different current phase from the first operating point P1). That is, in inefficient control, the operating point of the rotating electric machine 4 is determined to be a point moved along the equitorque line L1 from the first operating point P1. This makes it possible to output the same target torque to the rotating electric machine 4 as in normal control, while making the magnitude of the composite vector Idq larger than in normal control. The second operating point P2 and third operating point P3 in Figure 5 show examples of operating points in inefficient control. The d-axis current Id and q-axis current Iq at the second operating point P2 and third operating point P3 are the d-axis current Id and q-axis current Iq that are determined according to the target torque in inefficient control.

[0036] The second operating point P2 is an operating point (hereinafter referred to as the "retarding operating point") that is set so that the d-axis current Id is a value on the positive side (field strengthening side) compared to the first operating point P1. The third operating point P3 is an operating point (hereinafter referred to as the "advancing operating point") that is set so that the d-axis current Id is a value on the negative side (field weakening side) compared to the first operating point P1. For example, the operating point that allows for greater losses in the rotating electric machine 4 from among the retarding operating point such as the second operating point P2 and the advancing operating point such as the third operating point P3 can be determined as the operating point of the rotating electric machine 4 in inefficient control.

[0037] In inefficient control, the losses of the rotating electric machine 4 (especially copper losses) can be increased by increasing the magnitude of the composite vector Idq compared to normal control. Preferably, in inefficient control, the composite vector Idq (the operating point of the rotating electric machine 4) is determined such that the losses of the rotating electric machine 4 (including copper losses and iron losses) are greater than in normal control. For example, the operating point of the rotating electric machine 4 in inefficient control can be determined as the operating point of the rotating electric machine 4 that can increase the losses of the rotating electric machine 4 (including copper losses and iron losses) more than the operating point on the retard side or the advance side. Generally, the iron loss of the rotating electric machine 4 is greater at the retard side operating point than at the advance side operating point, making it easier to increase the losses of the rotating electric machine 4 (including copper losses and iron losses).

[0038] The PWM signal generation process generates a switching signal for PWM (Pulse Width Modulation) control of the inverter 7 based on the d-axis current Id and q-axis current Iq determined by the current determination process. The switching signal is a control signal (on / off signal) that controls the switching of the switching elements of the inverter 7. The switching signal is, for example, a gate drive signal. Between the control device 1 and the inverter 7, a driver (drive circuit) is provided, for example, which amplifies the voltage of the switching signal output from the control device 1, increases the driving force, and supplies it to the inverter 7.

[0039] PWM control is a control method that modulates the pulse width (on-time) of the control signal of a switching element. In the PWM signal generation process, a PWM signal, which is a switching signal for PWM control, is generated based on the carrier frequency. Specifically, in the PWM signal generation process, a voltage command (in this embodiment, a three-phase voltage command) is generated based on the d-axis current Id and q-axis current Iq determined by the current determination process. Then, a PWM signal with a pulse waveform of the carrier frequency is generated from the generated voltage command. For example, a PWM signal is generated from the voltage command by a carrier comparison method that compares the voltage command with the carrier signal of the carrier frequency.

[0040] In this embodiment, voltage commands are generated by performing current feedback control during the PWM signal generation process. Current feedback control is performed based on the rotational position of the rotor 41 (in this embodiment, the magnetic pole position of the field), the rotational speed of the rotor 41, and the current flowing through the coils 43 of each phase. In the example shown in Figure 4, the current flowing through the coils 43 is detected by a current sensor 61, and the rotational position and rotational speed of the rotor 41 are detected by a rotation sensor 62, such as a resolver or an inductive position sensor.

[0041] In current feedback control, a voltage command is generated based on the deviation between the current command and the feedback current, for example, by performing proportional-integral control or proportional-integral-derivative control. Specifically, the d-axis current Id and q-axis current Iq determined by the current determination process become the two-phase current command. The current flowing through the coils 43 of each phase is converted into a two-phase feedback current by coordinate transformation (three-phase to two-phase coordinate transformation). Then, a d-axis voltage command is generated based on the deviation between the d-axis current command and the d-axis feedback current, and a q-axis voltage command is generated based on the deviation between the q-axis current command and the q-axis feedback current. The two-phase voltage commands of the d-axis and q-axis are converted into a three-phase voltage command by coordinate transformation (two-phase to three-phase coordinate transformation).

[0042] While the vehicle 100 is in motion, the control device 1 selectively executes normal control and inefficient control according to whether there is a demand for heat generation by the vehicle 100 as described below. Here, a state where there is a demand for heat generation by the vehicle 100 is referred to as a "heat generation demand state". The control device 1 executes normal control when it is not in the heat generation demand state, and executes inefficient control when it is in the heat generation demand state. For example, when it is determined that the amount of heat required for the heat utilization equipment described above (for example, the amount of heat required for heating the passenger compartment or the amount of heat required for warming up the DC power supply 6 such as a battery) is insufficient, or when it is determined that it is necessary to warm up the oil (lubricating oil) housed in the case of the vehicle drive device 10, it is determined that there is a demand for heat generation (that is, it is determined that it is in the heat generation demand state). Whether there is a demand for heat generation may be determined by the control device 1 or by another device (for example, the vehicle control device described above) that can communicate with the control device 1. In the latter case, the determination result of whether there is a demand for heat generation by the other device is provided to the control device 1.

[0043] As shown in FIG. 4, the vehicle 100 is provided with an accelerator device 30, a brake device 31, a parking brake 32, and a shift device 33. Although not shown in the figure, the vehicle 100 is provided with sensors for detecting the operating state (for example, the operating amount) of the accelerator device 30, sensors for detecting the operating state (for example, the operating amount) of the brake device 31, sensors for detecting the operating state of the parking brake 32, and sensors for detecting the operating state (for example, the selected shift position) of the shift device 33.

[0044] The accelerator device 30 is a device that is operated to input an acceleration demand, such as an accelerator pedal. The brake device 31 is a device that is operated to input a braking demand, such as a brake pedal. The shift device 33 is a device that is operated to select a shift position, such as a shift lever or a shift switch. The shift positions of the vehicle 100 include a driving range (drive range) and a non-driving range (non-drive range).

[0045] The driving range is a range in which driving force (here, the torque of the rotating electric machine 4) is transmitted to the wheels W, such as the forward range and the reverse range. The forward range is a range in which driving force in the direction of moving the vehicle 100 forward is transmitted to the wheels W. The reverse range is a range in which driving force in the direction of moving the vehicle 100 backward is transmitted to the wheels W.

[0046] The non-driving range is a range in which driving force is not transmitted to the wheels W, such as the parking range and the neutral range. The parking range is a range in which driving force is not transmitted to the wheels W and the wheels W are locked. The parking range is used, for example, when the vehicle 100 is parked. The neutral range is a range in which driving force is not transmitted to the wheels W and the wheels W are not locked. The neutral range is used, for example, when the vehicle 100 is towed.

[0047] The parking brake 32 is a brake used when parking, which is different from the brake (service brake) operated by the brake device 31. The parking brake 32 includes, for example, an operating part for operating and releasing the brake, such as a lever, a pedal, a switch, etc. The parking brake 32 may be manually operated and released, or may be automatically operated and released. In the latter case, the parking brake 32 is operated and released in conjunction with, for example, a shift position change operation by the shift device 33. Note that the parking brake 32 is at least conceptually distinguished from the service brake, and a brake that functions as both the service brake and the parking brake 32 may be provided in the vehicle 100.

[0048] As shown in FIG. 4, the control device 1 includes a start determination unit 2. The start determination unit 2 determines the presence or absence of the possibility of starting the vehicle 100 in a vehicle stop state where the vehicle 100 is stopped. Here, the "vehicle stop state" means a state where the wheels W are not actively driven. Therefore, in the present embodiment, a state where the rotational speed of the wheels W is zero is regarded as the vehicle stop state, but a state where the wheels W are rotating at an extremely low speed, such as the state immediately before the vehicle 100 stops or the state where the vehicle 100 is sliding down a slope, may also be included in the vehicle stop state.

[0049] If a state where the rotational speed of the wheels W is zero is defined as a vehicle stopped state, then, for example, if the rotational speed corresponding to the vehicle speed detected by the sensor can be considered zero (i.e., if it falls within an error range that includes zero), the vehicle is determined to be stopped. Also, if a state where the wheels W are rotating at an extremely low speed is included in the vehicle stopped state, then, for example, if the rotational speed corresponding to the vehicle speed detected by the sensor is below a set value, the vehicle is determined to be stopped. Whether or not the vehicle is stopped may be determined by the control device 1, or by another device that can communicate with the control device 1 (for example, the vehicle control device described above). In the latter case, the determination result of whether or not the vehicle is stopped by the other device is provided to the control device 1.

[0050] The starting determination unit 2 determines whether or not the vehicle 100 is capable of starting based on the state of each part of the vehicle 100, such as the detection results of the sensors and the control state of the vehicle 100. Signals necessary for determining whether or not the vehicle is capable of starting are input to the control device 1 from sensors or other devices (for example, the vehicle control device described above). For example, signals necessary for determining whether or not the accelerator device 30 is being operated (for example, a signal representing the amount of accelerator operation or accelerator opening), signals necessary for determining whether or not the brake device 31 is being operated (for example, a signal representing the amount of brake operation), signals necessary for determining the operating state of the parking brake 32 (for example, a signal indicating whether or not the parking brake 32 is operating), and signals necessary for determining the shift position of the vehicle 100 (for example, a signal representing the shift position) are input to the control device 1.

[0051] The method for determining whether or not the vehicle can start is not limited to this, but in this embodiment, the starting determination unit 2 determines that the vehicle cannot start if at least one of the following conditions is met: the accelerator device 30 and brake device 31 of the vehicle 100 are not being operated, the parking brake 32 of the vehicle 100 is engaged, and the shift position of the vehicle 100 is in the non-driving range. If the starting determination unit 2 does not determine that the vehicle cannot start, it determines that the vehicle can start. In this way, by determining whether or not the vehicle can start based on the operating state of devices operated by the driver, such as the accelerator device 30, it is possible to determine whether or not the vehicle can start considering the driver's intention to drive. The result of the determination of whether or not the vehicle can start is used to determine which of the first and second heat generation modes to execute, as will be explained later with reference to Figure 6. Therefore, by determining whether or not the vehicle can start as described above, it is possible to appropriately generate heat by selecting a heat generation mode according to the driver's intention to drive in situations where there is a demand for heat generation while the vehicle is stopped.

[0052] Here, "the accelerator device 30 and the brake device 31 are not being operated" means that neither the accelerator device 30 nor the brake device 31 is being operated (for example, neither the accelerator pedal nor the brake pedal is being pressed). Also, the "non-driving range" in the state where "the shift position of the vehicle 100 is in a non-driving range" can be the parking range, or the parking range or the neutral range.

[0053] Furthermore, "determining that launch is not possible as a condition" includes both configurations where launch is deemed impossible if that condition is met, and configurations where launch is deemed impossible if that condition is met in addition to other conditions. In the latter configuration, the conditions for determining launch is impossible become stricter because the other conditions are included in the conditions for determining launch is impossible.

[0054] For example, the condition for determining that there is no possibility of starting can be included in the statement, "at least one of the following states is that the parking brake 32 of the vehicle 100 is engaged and the shift position of the vehicle 100 is in a non-driving range": that "at least one" is actually "both". Furthermore, the condition for determining that there is no possibility of starting can be included in the statement that the shift position is not being changed (for example, that the shift lever or shift switch is not being operated). In this case, for example, the starting determination unit 2 can be configured to determine that there is no possibility of starting if the accelerator device 30 and brake device 31 of the vehicle 100 are not being operated, at least one of the following states is that the parking brake 32 of the vehicle 100 is engaged and the shift position of the vehicle 100 is in a non-driving range (or both states are present), and the shift position is not being changed.

[0055] The following describes an example of the processing performed by the control device 1 when a heat generation request is made, with reference to Figure 6. Note that in Figure 6, the step of acquiring the signals necessary for determination (sensor signals, vehicle signals, etc.) is omitted, but the signals necessary for each determination are acquired as appropriate.

[0056] If the control device 1 is in a heat generation request state and the vehicle is not stopped (step #01: Yes, step #02: No), it puts the drive transmission mechanism 5 into a transmission state and executes the third heat generation mode (steps #14, step #15). The third heat generation mode is a mode in which the inverter 7 is operated to drive the rotating electric machine 4 by inefficient control, thereby energizing the inverter 7 and the rotating electric machine 4 and generating heat.

[0057] The control device 1 continues to execute the third heat generation mode (step #15) as long as it is determined that a heat generation request state is in effect (step #16: Yes). Then, when the control device 1 determines that a heat generation request state is not in effect (step #16: No), it terminates the third heat generation mode. In the example shown in Figure 6, if it is determined that a heat generation request state is in effect after the start of the third heat generation mode (step #16: Yes), the process returns to step #15. However, alternatively, if it is determined that a heat generation request state is in effect (step #16: Yes), the process may return to step #02, and the determination of whether or not the vehicle is stopped (step #02) may be performed again.

[0058] If the control device 1 is in a heat generation request state and the vehicle is stopped, and the start determination unit 2 determines that it is possible to start (step #01: Yes, step #02: Yes, step #03: Yes), it sets the drive transmission mechanism 5 to the transmission state and executes the first heat generation mode (steps #11, #12). The first heat generation mode will be described later. While the control device 1 is determined to be in a heat generation request state (step #13: Yes), and the vehicle is stopped, and the start determination unit 2 determines that it is possible to start (step #02: Yes, step #03: Yes), it continues to execute the first heat generation mode (step #12). Then, if the control device 1 determines that it is no longer in a heat generation request state (step #13: No), it terminates the first heat generation mode.

[0059] Furthermore, if the control device 1 determines that the vehicle is not stopped before it is determined that it is not in a heat generation request state (step #13: Yes, step #02: No), it will execute the third heat generation mode while keeping the drive transmission mechanism 5 in the transmission state (steps #14, step #15). In this case, the first heat generation mode is canceled and the third heat generation mode is executed.

[0060] Furthermore, if the control device 1 determines that the vehicle is stopped and there is no possibility of starting before it is determined that there is no heat generation request state (step #13: Yes, step #02: Yes, step #03: No), it sets the drive transmission mechanism 5 to a non-transmission state and executes the second heat generation mode (steps #04, step #05). The second heat generation mode will be described later. In this case, the first heat generation mode is canceled and the second heat generation mode is executed. Thus, in the example shown in Figure 6, if the control device 1 is in a heat generation request state and the vehicle is stopped, and the determination by the starting determination unit 2 changes from there to there is no possibility of starting while the first heat generation mode is being executed, it cancels the first heat generation mode and executes the second heat generation mode.

[0061] If the control device 1 is in a heat generation request state and the vehicle is stopped, and the starting determination unit 2 determines that there is no possibility of starting (step #01: Yes, step #02: Yes, step #03: No), it sets the drive transmission mechanism 5 to a non-transmission state and executes the second heat generation mode (steps #04, #05). While the control device 1 is determined to be in a heat generation request state (step #06: Yes), if the starting determination unit 2 determines that there is no possibility of starting (step #09: No), it continues to execute the second heat generation mode (step #05). Then, when the control device 1 determines that there is no heat generation request state (step #06: No), it terminates the second heat generation mode. When terminating the second heat generation mode, the control device 1 performs rotor stop control to stop the rotation of the rotor 41 (step #07), and then sets the drive transmission mechanism 5 to a transmission state (step #08). In step #07 and step #10 described later, the control device 1 controls the rotating electric machine 4 to generate a torque in the direction that stops the rotation of the rotor 41, thereby stopping the rotation of the rotor 41.

[0062] Furthermore, if the control device 1 determines that there is a possibility of starting before it is determined that there is no heat generation request state (step #06: Yes, step #09: Yes), it performs rotor stop control to stop the rotation of the rotor 41 (step #10), and then executes the first heat generation mode with the drive transmission mechanism 5 in the transmission state (step #11, step #12). In this case, the second heat generation mode is canceled and the first heat generation mode is executed. Thus, in the example shown in Figure 6, if the control device 1 is in a heat generation request state and the vehicle is stopped, and the determination by the starting determination unit 2 changes from no possibility of starting to possibility of starting while the second heat generation mode is being executed, it cancels the second heat generation mode and executes the first heat generation mode.

[0063] The first heat generation mode is a mode in which the inverter 7 is operated in such a way that the rotor 41 does not rotate, thereby energizing the inverter 7 and the rotating electric machine 4 and generating heat in the inverter 7 and the rotating electric machine 4. When the first heat generation mode is executed, the drive transmission mechanism 5 is in a transmission state. Here, "in such a way that the rotor 41 does not rotate" includes both preventing the rotor 41 from rotating by preventing the rotating electric machine 4 from outputting torque, and preventing the rotor 41 from rotating by setting the torque output by the rotating electric machine 4 to a magnitude that does not cause the rotor 41 to rotate.

[0064] In this embodiment, the control device 1 operates the inverter 7 in the first heat generation mode so that the rotating electric machine 4 does not output torque. Specifically, the inverter 7 drives the rotating electric machine 4 by inefficient control so that the rotating electric machine 4 does not output torque. The current phase of the rotating electric machine 4 is set to a phase (0 degrees or 180 degrees) in which the rotating electric machine 4 does not generate torque. That is, the target torque of the rotating electric machine 4 is set to zero, and the rotating electric machine 4 is driven at an operating point in which the d-axis current Id is positive or negative and the q-axis current Iq is zero. In this way, in the first heat generation mode, the inverter 7 and the rotating electric machine 4 are heated without generating torque by not flowing the q-axis current Iq which contributes to the torque of the rotating electric machine 4, and instead flowing the d-axis current Id which does not contribute to the torque of the rotating electric machine 4.

[0065] The second heat generation mode is a mode in which the inverter 7 is operated to rotate the rotor 41, thereby energizing the inverter 7 and the rotating electric machine 4, and generating heat in the inverter 7 and the rotating electric machine 4. When the second heat generation mode is in operation, the drive transmission mechanism 5 is in a non-transmission state. In the second heat generation mode, the control device 1 controls the rotating electric machine 4 so that the rotor 41 does not over-rotate.

[0066] In the first heat generation mode, the rotor 41 does not rotate, so the energized state (current value) of each of the three-phase coils 43 does not change. Therefore, DC current flows through each of the three-phase coils 43, and the current tends to concentrate in one of the phases determined by the rotation angle of the rotor 41. In contrast, in the second heat generation mode, the rotor 41 rotates, so the energized state (current value) of each of the three-phase coils 43 changes. Therefore, a time-varying current (for example, a three-phase AC current) can be passed through the three-phase coils 43, and the uneven distribution of heat generation in each phase of the inverter 7 and rotating electric machine 4 can be minimized.

[0067] Thus, in the second heat generation mode, the uneven distribution of heat generation in each phase of the inverter 7 and the rotating electric machine 4 can be minimized. As a result, the timing at which the inverter 7 and the rotating electric machine 4 reach their thermal limits can be delayed, and the current values ​​supplied to the inverter 7 and the rotating electric machine 4 can be increased, making it easier to secure a larger amount of heat generation in the inverter 7 and the rotating electric machine 4. From the viewpoint of securing a larger amount of heat generation, it is preferable for the control device 1 to be configured to drive the rotating electric machine 4 by inefficient control in the second heat generation mode.

[0068] In the second heat generation mode, the drive transmission mechanism 5 is in a non-transmission state and the rotor 41 is rotated. Therefore, in the second heat generation mode, it is possible to increase the amount of heat generated by utilizing the heat generated due to the frictional resistance of the drive transmission mechanism 5 in the range in which the rotation of the rotor 41 is transmitted (including the resistance of oil stirring due to friction with the oil, the same applies hereinafter). When the drive transmission mechanism 5 is equipped with a disconnection mechanism 51, as in the example shown in Figures 2 and 3, it is possible to secure a large amount of heat generated in the second heat generation mode by utilizing the heat generated due to the frictional resistance in the disconnection mechanism 51, for example.

[0069] Furthermore, as shown in the example in Figure 2, when the disconnection mechanism 51 is provided in the power transmission path between the transmission 50 and the output shaft 59, in the second heat generation mode in which the drive transmission mechanism 5 is in a non-transmission state, the rotating members constituting the transmission 50 rotate in conjunction with the rotor 41. Therefore, in the second heat generation mode, it is possible to secure a large amount of heat by utilizing the heat generated due to frictional resistance in the transmission 50, such as friction between gears and heat generated by the agitation (stirring) of oil (oil contained in the case housing the drive transmission mechanism 5) by the gears. In addition, since the rotational load on the rotor 41 is larger compared to when the transmission 50 does not rotate in conjunction with the rotor 41, there is also the advantage that it is easier to secure a large amount of heat by increasing the losses of the rotating electric machine 4.

[0070] On the other hand, as shown in the example in Figure 3, when the disconnection mechanism 51 is provided in the power transmission path between the rotating electric machine 4 and the transmission 50, the transmission 50 does not rotate in conjunction with the rotor 41 in the second heat generation mode, when the drive transmission mechanism 5 is in a non-transmission state. In this case, in the second heat generation mode, the oil contained in the case can be prevented from being scattered by the rotation of the rotating members constituting the transmission 50. Therefore, for example, if the amount of heat that can be recovered from the oil is reduced when the relatively low-temperature oil scattered by the rotation of the rotating members constituting the transmission 50 mixes with the relatively high-temperature oil after the rotating electric machine 4 has been cooled, the reduction in the amount of heat that can be recovered can be suppressed by providing the disconnection mechanism 51 as shown in the example in Figure 3.

[0071] Figure 7 shows an example of control behavior during the execution of the second heat generation mode. In Figure 7, a heat generation request state is assumed at time t1, and the heat generation request state is no longer assumed at time t3. Furthermore, in Figure 7, a situation is assumed in which it is determined that there is no possibility of starting during the time range shown. When the heat generation request state is assumed at time t1, the control device 1 switches the drive transmission mechanism 5 from the transmission state to the non-transmission state. In Figure 7 and Figure 8, which will be referred to later, the dashed line in the graph representing the state of the drive transmission mechanism 5 represents the command value, and the solid line represents the actual change in state.

[0072] The control device 1 starts the second heat generation mode at time t2 after the drive transmission mechanism 5 switches from a transmission state to a non-transmission state. In the example shown in Figure 7, the control device 1 assumes that in the second heat generation mode, it controls the rotating electric machine 4 to rotate the rotor 41 by controlling the rotational speed of the rotating electric machine 4. In the rotational speed control, the torque of the rotating electric machine 4 is controlled to converge the rotational speed of the rotor 41 to a target rotational speed. In the example shown in Figure 7, the target rotational speed of the rotor 41 is maintained at a constant value while the second heat generation mode is being executed.

[0073] When the control device 1 realizes at time t3 that the heat generation requirement state has been eliminated, it executes rotor stop control to stop the rotation of the rotor 41. Then, at time t4, after the rotation of the rotor 41 has stopped, the control device 1 switches the drive transmission mechanism 5 from a non-transmission state to a transmission state.

[0074] Figure 8 shows another example of the control behavior during the execution of the second heat generation mode. In Figure 8, a heat generation request state is assumed at time t11, and the heat generation request state is no longer assumed at time t13. Furthermore, in Figure 8, a situation is assumed in which it is determined that there is no possibility of starting during the time range shown. When the heat generation request state is assumed at time t11, the control device 1 switches the drive transmission mechanism 5 from the transmission state to the non-transmission state.

[0075] The control device 1 starts the second heat generation mode at time t12 after the drive transmission mechanism 5 switches from a transmission state to a non-transmission state. In the example shown in Figure 8, the control device 1 is assumed to intermittently drive the rotating electric machine 4 in the second heat generation mode, alternating between driving and coasting. In the example shown in Figure 8, during the period when the rotating electric machine 4 is driven, the rotating electric machine 4 is made to output torque (in this case, a constant torque) to increase the rotational speed of the rotor 41 to the first target rotational speed. During the period when the rotating electric machine 4 is coasting, the output torque of the rotating electric machine 4 is set to zero, thereby reducing the rotational speed of the rotor 41 to a second target rotational speed lower than the first target rotational speed. In the example shown in Figure 8, the second target rotational speed is set to a rotational speed higher than zero.

[0076] During the coasting period of the rotating electric machine 4, the rotational speed of the rotor 41 decreases due to friction, etc. Even during the coasting period of the rotating electric machine 4, by driving the rotating electric machine 4 with inefficient control so that it does not output torque (i.e., driving the rotating electric machine 4 with zero torque control), the inverter 7 and the rotating electric machine 4 can be heated even during the coasting period.

[0077] When the control device 1 realizes at time t13 that the heat generation requirement state has ended, it executes rotor stop control to stop the rotation of the rotor 41. Then, at time t14, after the rotation of the rotor 41 has stopped, the control device 1 switches the drive transmission mechanism 5 from a non-transmission state to a transmission state.

[0078] In this embodiment, the fact that the drive transmission mechanism 5 is configured to change between a transmission state and a non-transmission state is utilized not only for executing the second heat generation mode but also for fail-safe processing. Specifically, in at least one of the following cases, the control device 1 is configured to set the drive transmission mechanism 5 to a non-transmission state: when it becomes impossible to control the inverter 7 to prevent the rotor 41 from rotating during the execution of the first heat generation mode, and when it becomes impossible to control the torque of the rotating electric machine 4 while the vehicle 100 is running. In this embodiment, the control device 1 sets the drive transmission mechanism 5 to a non-transmission state in either of these two cases.

[0079] Figure 9 shows an example of fail-safe processing performed by the control device 1. This fail-safe processing is performed when the inverter 7 cannot be controlled to prevent the rotor 41 from rotating during the execution of the first heat generation mode, and the drive transmission mechanism 5 is set to a non-transmission state. That is, when the control device 1 is unable to control the inverter 7 to prevent the rotor 41 from rotating during the execution of the first heat generation mode (step #20: Yes), and the drive transmission mechanism 5 is in a transmission state (step #21: Yes), the drive transmission mechanism 5 is set to a non-transmission state (step #22).

[0080] For example, if the inverter 7 fails (for example, a single-phase short-circuit failure), if the rotation sensor 62 fails, or if the current sensor 61 fails, it may become impossible to control the inverter 7 to prevent the rotor 41 from rotating. The control device 1 determines whether a failure has occurred in the inverter 7, etc., based on, for example, the current detected by the current sensor 61, or based on diagnostic information provided by a diagnostic circuit installed in the drive circuit, etc. Then, if the control device 1 determines that a failure has occurred in the inverter 7, etc., it determines that it has become impossible to control the inverter 7 to prevent the rotor 41 from rotating.

[0081] If the inverter 7 fails to control the rotor 41 to prevent it from rotating, for example, current may flow to an unintended phase coil 43, potentially generating unintended torque in the rotating electric machine 4. If this unintended torque is transmitted to the wheels W, it may cause unintended vehicle behavior 100 or shocks due to the parking lock mechanism stopping the rotation of the wheels W. In this embodiment, if the control device 1 fails to control the inverter 7 to prevent the rotor 41 from rotating during the execution of the first heat generation mode, the drive transmission mechanism 5 is set to a non-transmission state. Therefore, even if unintended torque is generated in the rotating electric machine 4, that torque will not be transmitted to the wheels W.

[0082] Figure 10 shows another example of fail-safe processing performed by the control device 1. This fail-safe processing is a process that puts the drive transmission mechanism 5 into a non-transmission state if the torque of the rotating electric machine 4 becomes uncontrollable while the vehicle 100 is in motion. That is, if the control device 1 becomes uncontrollable of the torque of the rotating electric machine 4 while the vehicle 100 is in motion (step #30: Yes), and the drive transmission mechanism 5 is in a transmission state (step #31: Yes), then the control device 1 puts the drive transmission mechanism 5 into a non-transmission state (step #32).

[0083] For example, if a failure (e.g., a single-phase short-circuit failure) occurs in the inverter 7 while the vehicle 100 is in motion, the control device 1 may open the contactor 60 and perform active short-circuit control or shutdown control. The control device 1 may also perform active short-circuit control or shutdown control if the contactor 60 opens due to an impact or failure on the vehicle 100.

[0084] Active short-circuit control is a control method that recirculates current between the rotating electric machine 4 and the inverter 7. In active short-circuit control, for example, all upper switching elements of the inverter 7 are turned off while all lower switching elements of the inverter 7 are turned on, or all upper switching elements of the inverter 7 are turned on while all lower switching elements of the inverter 7 are turned off. In shutdown control, all switching elements of the inverter 7 are turned off.

[0085] When the control device 1 performs active short-circuit control or shutdown control while the vehicle 100 is in motion, it can be said that the control device 1 is unable to control the torque of the rotating electric machine 4. In this embodiment, when the control device 1 performs active short-circuit control or shutdown control while the vehicle 100 is in motion (in other words, when the conditions for performing these controls are met), it determines that the torque of the rotating electric machine 4 is uncontrollable. In this embodiment, when the torque of the rotating electric machine 4 is uncontrollable while the vehicle 100 is in motion, the control device 1 puts the drive transmission mechanism 5 into a non-transmission state, thereby disconnecting the rotating electric machine 4, which is in a state where the torque cannot be controlled, from the wheel W. This makes it possible to avoid the vehicle 100's behavior becoming unstable due to unintended torque changes in the rotating electric machine 4.

[0086] Furthermore, while the rotating electric machine 4 is being pulled along by the wheel W due to active short-circuit control, the rotating electric machine 4 generates heat. However, when the control device 1 performs active short-circuit control, it can disconnect the rotating electric machine 4 from the wheel W as described above, thereby preventing the rotating electric machine 4 from being pulled along by the wheel W for an extended period and allowing the rotating electric machine 4 to be stopped relatively early. This makes it possible to avoid overheating and damage to the rotating electric machine 4 caused by being pulled along by the wheel W for an extended period.

[0087] [Other Embodiments] (1) In the above embodiment, a configuration was described as in which the control device 1 puts the drive transmission mechanism 5 into a non-transmission state in at least one of the following cases: when the inverter 7 cannot be controlled to prevent the rotor 41 from rotating during the execution of the first heat generation mode, and when the torque of the rotating electric machine 4 cannot be controlled while the vehicle 100 is running. However, the present disclosure is not limited to such a configuration, and the control device 1 may also be configured not to put the drive transmission mechanism 5 into a non-transmission state in either of these cases.

[0088] (2) In the above embodiment, the starting determination unit 2 was described as having a configuration in which it determines that there is no possibility of starting, on the condition that the accelerator device 30 and brake device 31 of the vehicle 100 are not being operated and the parking brake 32 of the vehicle 100 is engaged, and the shift position of the vehicle 100 is in a non-driving range. However, the present disclosure is not limited to such a configuration, and the conditions for determining that there is no possibility of starting may be more relaxed.

[0089] (3) The configurations disclosed in each of the embodiments described above can be applied in combination with configurations disclosed in other embodiments (including combinations of embodiments described as other embodiments), as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed in this specification are merely illustrative in all respects. Therefore, various modifications can be made as appropriate without departing from the spirit of this disclosure.

[0090] [Summary of this embodiment] The following is a summary of the embodiment relating to the vehicle drive system described above.

[0091] The vehicle drive system (10) comprises a rotating electric machine (4) equipped with a rotor (41), an inverter (7) that controls the rotating electric machine (4), a drive transmission mechanism (5) that transmits the driving force of the rotating electric machine (4) to the wheels (W), and a control device (1) that controls the inverter (7) and the drive transmission mechanism (5), wherein the drive transmission mechanism (5) is configured to change between a transmission state in which the driving force of the rotating electric machine (4) is transmitted to the wheels (W) and a non-transmission state in which the driving force of the rotating electric machine (4) is not transmitted to the wheels (W), and the control device (1) includes a starting determination unit (2) that determines whether or not the vehicle (100) can start when the vehicle (100) is stopped, and the state in which there is a demand for heat generation by the vehicle (100) is defined as a heat generation demand state, and the control device (1) controls the heat generation If the vehicle is in a heat-requiring state and is stopped, and the starting determination unit (2) determines that there is a possibility of starting, the drive transmission mechanism (5) is set to the transmission state, and the inverter (7) is operated so as not to rotate the rotor (41), thereby energizing the inverter (7) and the rotating electric machine (4) to execute a first heat-generating mode in which the inverter (7) and the rotating electric machine (4) generate heat. If the vehicle is in a heat-requiring state and is stopped, and the starting determination unit (2) determines that there is no possibility of starting, the drive transmission mechanism (5) is set to the non-transmission state, and the inverter (7) is operated so as to rotate the rotor (41), thereby energizing the inverter (7) and the rotating electric machine (4) to execute a second heat-generating mode in which the inverter (7) and the rotating electric machine (4) generate heat.

[0092] With this configuration, heat can be generated even when the vehicle is stopped in either the first or second heat generation mode. When it is determined that there is a possibility of the vehicle (100) starting, the first heat generation mode is executed in which the drive transmission mechanism (5) is in a transmission state, allowing the vehicle (100) to start quickly when it is ready to move. When it is determined that there is no possibility of the vehicle (100) starting, the second heat generation mode is executed in which the drive transmission mechanism (5) is in a non-transmission state and the rotor (41) is rotated, which helps to minimize the uneven distribution of heat generation in each phase of the inverter (7) and rotating electric machine (4). As a result, the amount of heat generated can be increased while protecting the inverter (7) and rotating electric machine (4), making it easier to ensure an appropriate amount of heat generation. In addition, in the second heat generation mode, it is also possible to increase the amount of heat generated by utilizing the heat generated due to the frictional resistance of the drive transmission mechanism (5) in the range in which the rotation of the rotor (41) is transmitted (including the resistance of oil stirring due to friction with the oil).

[0093] As described above, this configuration makes it easier to ensure an appropriate amount of heat is generated when the heat generation mode is executed while the vehicle is stopped, and also makes it possible to quickly start the vehicle (100) as needed.

[0094] Here, it is preferable that the control device (1) discontinues the second heat generation mode and executes the first heat generation mode if, while the heat generation request state and the vehicle is stopped, the determination by the starting determination unit (2) changes from "no possibility of starting" to "possibility of starting" while the second heat generation mode is being executed, and if, while the heat generation request state and the vehicle is stopped, the determination by the starting determination unit (2) changes from "possibility of starting" to "no possibility of starting" while the first heat generation mode is being executed, the first heat generation mode and executes the second heat generation mode.

[0095] According to this configuration, even if the determination of whether or not the vehicle (100) can start changes during the execution of either the first heat generation mode or the second heat generation mode, an appropriate heat generation mode can be executed according to the changed possibility of starting.

[0096] Furthermore, it is preferable for the starting determination unit (2) to determine that there is no possibility of starting, provided that the accelerator device (30) and brake device (31) of the vehicle (100) are not being operated, the parking brake (32) of the vehicle (100) is engaged, and the shift position of the vehicle (100) is in a non-driving range.

[0097] When starting a vehicle (100) from a stationary position, for example, the brake device (31) is turned on, followed by the release of the parking brake (32) and a change in the shift position from a non-driving range to a driving range, after which the accelerator device (30) is turned on. With this configuration, it is possible to appropriately determine whether or not the vehicle (100) can start moving based on the operations performed when starting the vehicle (100) from a stationary position and the changes in the state at the time of starting.

[0098] Furthermore, in at least one of the following cases, where the inverter (7) cannot be controlled to prevent the rotor (41) from rotating while the first heat generation mode is being executed, or where the torque of the rotating electric machine (4) cannot be controlled while the vehicle (100) is in motion, the control device (1) preferably sets the drive transmission mechanism (5) to the non-transmission state.

[0099] With this configuration, the fact that the drive transmission mechanism (5) is configured to change between a transmission state and a non-transmission state can be effectively utilized not only for executing the second heat generation mode but also for other purposes. For example, if the inverter (7) cannot be controlled to prevent the rotor (41) from rotating while the first heat generation mode is being executed, the control device (1) can be configured to put the drive transmission mechanism (5) into a non-transmission state. In this case, even if the rotor (41) rotates unintentionally due to such a state, the rotation of the rotor (41) will not be transmitted to the wheels (W), thereby reducing the possibility of the vehicle (100) moving even though the vehicle is stationary. Also, if the torque of the rotating electric machine (4) cannot be controlled while the vehicle (100) is running, the control device (1) can be configured to put the drive transmission mechanism (5) into a non-transmission state. In such a case, the rotating electric machine (4) can be disconnected from the wheels (W). Therefore, it becomes possible to avoid the vehicle (100) becoming unstable due to unintended torque changes in the rotating electric machine (4), and to avoid damage to the rotating electric machine (4) due to it being continuously pulled around by the wheels (W).

[0100] The vehicle drive system relating to this disclosure only needs to be able to achieve at least one of the effects described above.

[0101] 1: Control device, 2: Start determination unit, 4: Rotating electric machine, 5: Drive transmission mechanism, 7: Inverter, 10: Vehicle drive system, 30: Accelerator device, 31: Brake device, 32: Parking brake, 41: Rotor, 100: Vehicle, W: Wheel

Claims

1. A vehicle drive system comprising: a rotating electric machine equipped with a rotor; an inverter for controlling the rotating electric machine; a drive transmission mechanism for transmitting the driving force of the rotating electric machine to the wheels; and a control device for controlling the inverter and the drive transmission mechanism, wherein the drive transmission mechanism is configured to change between a transmission state in which the driving force of the rotating electric machine is transmitted to the wheels and a non-transmission state in which the driving force of the rotating electric machine is not transmitted to the wheels; the control device includes a starting determination unit for determining whether or not the vehicle can start when the vehicle is stopped, and the state in which there is a demand for heat generation by the vehicle is defined as a heat generation demand state; and when the heat generation demand state is in place and the vehicle is stopped, and the starting determination unit has determined that there is a possibility of starting, the control device executes a first heat generation mode in which the drive transmission mechanism is set to the transmission state, the inverter is operated so as not to rotate the rotor, and power is supplied to the inverter and the rotating electric machine, thereby generating heat in the inverter and the rotating electric machine. A vehicle drive device that, when the heat generation request state is met and the vehicle is stopped, and the start determination unit determines that there is no possibility of starting, sets the drive transmission mechanism to the non-transmission state, operates the inverter to rotate the rotor, and energizes the inverter and the rotating electric machine to generate heat in the inverter and the rotating electric machine, thereby executing a second heat generation mode.

2. The vehicle drive device according to claim 1, wherein the control device, in the heat generation request state and the vehicle stopped state, if the determination by the starting determination unit changes from no possibility of starting to possibility of starting while the second heat generation mode is being executed, discontinues the second heat generation mode and executes the first heat generation mode; and in the heat generation request state and the vehicle stopped state, if the determination by the starting determination unit changes from possibility of starting to no possibility of starting while the first heat generation mode is being executed, discontinues the first heat generation mode and executes the second heat generation mode.

3. The vehicle drive system according to claim 1 or 2, wherein the starting determination unit determines that there is no possibility of starting, provided that the vehicle's accelerator and brake devices are not being operated and at least one of the following conditions is met: the vehicle's parking brake is engaged and the vehicle's shift position is in a non-driving range.

4. In at least one of the following cases, the control device puts the drive transmission mechanism into the non-transmission state: when the inverter cannot be controlled to prevent the rotor from rotating during the execution of the first heat generation mode, and when the torque of the rotating electric machine cannot be controlled while the vehicle is in motion.

Images