JP5673068B2 - Vehicle drive device - Google Patents

Description

  The present invention relates to a vehicle drive device that drives a vehicle with a motor, and more particularly to a device that controls a motor in accordance with the rotational phase of the motor.

  Vehicles driven by a motor, such as a hybrid vehicle that travels using an engine and a motor, and an electric vehicle that travels using a motor, are widely used. Such a vehicle includes a motor drive circuit that controls the rotation state of the motor by adjusting electric power supplied to the motor, and a control unit that controls the motor drive circuit.

  The motor drive circuit includes a DCDC converter that boosts the voltage of the battery, and an inverter that converts DC power output from the DCDC converter into AC power and supplies the AC power to the motor. The motor drives the vehicle by generating torque with AC power supplied from the motor drive circuit. The control unit controls the DCDC converter and the inverter so that the motor generates torque according to the running state of the vehicle and the driving operation.

  2. Description of the Related Art Generally, a motor used in a vehicle includes a rotor that rotates about its shaft, and a field winding that generates a rotating magnetic field around the rotor. In order to generate a rotating magnetic field corresponding to the rotation of the rotor, a current synchronized with the rotation phase of the rotor is supplied to the field winding. Therefore, the control unit controls the inverter so that the alternating current flowing through the power supply line from the inverter to the field winding of the motor is synchronized with the rotational phase of the rotor.

  In a general inverter having a plurality of switching elements and performing PWM (Pulse Width Modulation) control, when such synchronous control is performed, when the motor stops and the motor stops, a specific switching element is Current concentrates and the temperature of the switching element rises.

  The following Patent Documents 1 to 3 describe an inverter that drives a motor for driving a vehicle and a control method therefor. In the control method described in Patent Literature 1, when the motor is in a locked state, the motor is alternately rotated in the forward direction and the reverse direction, thereby avoiding an overheating state of the switching element of the inverter. In the control methods described in Patent Documents 2 and 3, when the motor is locked, the torque generated by the motor is limited to avoid an overheating state of the switching element of the inverter.

JP 2006-238560 A JP 2004-350442 A JP-A-11-122703

  When the vehicle enters a steep slope or tries to climb on an obstacle such as a curbstone, the wheel and the motor may be locked. As a result, current concentrates on a specific switching element included in the inverter, and the switching element may be overheated. In such a case, in the prior art, the overheated state of the switching element is avoided by limiting the torque generated by the motor. However, this control allows an increase in the torque of the motor and does not cancel the locked state by the increase in torque.

  The present invention prevents a power converter such as an inverter from being overheated when a vehicle driving motor is in a rotation restricted state, and forms a state in which an increase in motor torque is allowed. With the goal.

The present invention includes a power converter that converts DC power into AC power by switching, a motor that drives a vehicle with three-phase AC power supplied from the power converter, and the power according to the rotational phase of the motor. A control unit that performs switching of the conversion unit and controls the motor, and the power conversion unit includes three switching element pairs, each of which includes two switching elements connected in series. DC power is supplied to both ends of the series connection path formed by the power supply, AC power is supplied to the motor from a series connection point of each switching element pair, and the control unit flows between the power conversion unit and the motor 3 as an alternating current phase is synchronized with the rotational phase of the motor, it performs switching of the power conversion unit, wherein the motor is rotating When a limiting condition, and controls the motor so that the rotation phase of the motor to a target phase corresponding to the rotational phase of the motor at that time reaches the target phase, of the switching element pairs of the three pairs The current flowing through one pair of switching elements is zero, and each of the other two pairs of switching elements has a phase in which one of the two switching elements connected in series is switched on. It is characterized by.

The present invention also provides a power converter that converts DC power into AC power by switching, a motor that drives a vehicle with AC power supplied from the power converter, and the power conversion according to the rotational phase of the motor. And a control unit that controls the motor, and the control unit has a target phase according to the switching state of the power conversion unit at that time when the motor is in a rotation limited state. The control unit includes torque command value determining means for determining a torque command value for the motor according to a driving operation of the vehicle, and the torque command value is set to the torque command value. In response to the switching of the power conversion unit, the torque command value determining means When the rotation phase of the motor reaches the target phase by the control of the control unit when the rotation restricted state is reached, a value larger than the upper limit value when the motor is not in the rotation restricted state is set as the upper limit value. The torque command value is determined .

  In the vehicle drive device according to the present invention, preferably, the power conversion unit includes three switching element pairs each including two switching elements connected in series, and a series connection path formed by each switching element pair. DC power is supplied to both ends of the switch, and AC power is supplied to the motor from a series connection point of each switching element pair.

  In the vehicle drive device according to the present invention, preferably, the control unit includes torque command value determining means for determining a torque command value for the motor according to a driving operation of the vehicle, and according to the torque specified value. Switching the power converter, and the torque command value determining means is configured to control the control unit when the motor is in the rotation restricted state, when the rotational phase of the motor reaches the target phase. In addition, the torque command value is determined with an upper limit value that is larger than the upper limit value when the motor is not in the rotation limit state.

  In the vehicle drive device according to the present invention, preferably, the control unit includes means for determining whether or not the element is in an overheated state based on a temperature of the element included in the power conversion unit, The torque command value determining means is configured to determine whether the element is not in the overheat state after the control of the control unit when the motor is in the rotation limit state. The torque command value is determined with an upper limit value that is larger than the upper limit value when not in a state.

  In the vehicle drive device according to the present invention, preferably, the control unit includes means for determining whether or not the element is in a temperature rising state based on a temperature of the element included in the power conversion unit, The motor is controlled so that the rotational phase of the motor reaches the target phase when it is determined that the motor is in a rotational restricted state and the element is in the temperature rising state.

  In the vehicle drive device according to the present invention, preferably, the control unit reduces the torque generated by the motor when the motor is in the rotation restricted state, and the vehicle is caused by a difference in height on a running surface. The motor is rotated based on the movement of.

  In addition, the vehicle drive device according to the present invention preferably includes an inclination sensor that detects an inclination angle of the traveling surface of the vehicle, and the control unit detects that the vehicle is inclined on the basis of a detection value by the inclination sensor. A means for determining whether or not the motor is positioned, and when the motor is in the rotation restricted state and it is determined that the vehicle is positioned on an inclined surface, the torque generated by the motor is reduced; The motor is rotated based on the movement of the vehicle due to the inclination of the running surface.

  In the vehicle drive device according to the present invention, preferably, the control unit increases a torque generated by the motor when the motor is in the rotation restricted state, and the vehicle is driven by the increase in the torque. The motor is rotated based on the movement.

  According to the present invention, when the motor for driving the vehicle is in the rotation restricted state, the power conversion unit such as the inverter is prevented from being overheated, and a state in which an increase in the motor torque is allowed is formed. can do.

It is a figure which shows the structure of an electric vehicle drive device. It is a figure which shows the example of the relationship between a phase detection value and a three-phase alternating current. It is a figure which shows the time characteristic of the upper limit with respect to a torque command value, and the time characteristic of a torque command value. It is a flowchart of rotation restriction cancellation control. It is a figure which shows the example of a target phase acquisition table. It is a flowchart of rotation restriction cancellation control using an inclined surface. 10 is a flowchart of rotation restriction cancellation control according to an application example. It is a flowchart of rotation restriction cancellation control using an inclined surface. It is a flowchart of rotation restriction cancellation control concerning a modification. It is a figure which shows the example of a target phase acquisition table. It is a figure which shows the structure of a hybrid vehicle drive device.

  FIG. 1 shows a configuration of an electric vehicle driving apparatus according to an embodiment of the present invention. The DCDC converter 12 and the inverter 14 shown in FIG. 1 correspond to the motor drive circuit described above. The electric vehicle drive device generates torque in the motor generator 18 based on the electric power supplied from the battery 10, accelerates the vehicle with the torque, and charges the battery 10 with the generated electric power based on the regenerative braking by the motor generator 18. .

  The driving operation unit 24 includes an accelerator pedal, a brake pedal, and the like, and gives a command to the control unit 26 based on a user operation. The control unit 26 controls the DCDC converter 12 and the inverter 14 based on a command from the driving operation unit 24, a vehicle speed, and the like, and performs acceleration or regenerative braking of the vehicle.

  During acceleration of the vehicle, DCDC converter 12 boosts the output voltage of battery 10 and outputs the boosted voltage to inverter 14. Inverter 14 converts the DC power output from DCDC converter 12 into AC power, and outputs the AC power to motor generator 18. The motor generator 18 generates torque by the AC power output from the inverter 14 and applies the torque to the power transmission mechanism 20. The power transmission mechanism 20 transmits the torque applied from the motor generator 18 to the wheels 22. Thereby, the vehicle is accelerated based on the electric power supplied from the battery 10.

  During regenerative braking, motor generator 18 outputs AC power based on regenerative braking power generation to inverter 14. Inverter 14 converts AC power output from motor generator 18 into DC power, and outputs the DC power to DCDC converter 12. The DCDC converter 12 steps down the voltage output from the inverter 14 and applies the stepped down voltage to the battery 10. Thereby, the battery 10 is charged based on the electric power generated by the motor generator 18.

  Specific configurations and operations of the inverter 14 and the motor generator 18 will be described. The inverter 14 includes three pairs of switching elements 16u, 16v, and 16w. Here, the switching element pair includes two IGBTs (Insulated Gate Bipolar Transistors) in which one emitter terminal is connected to the other collector terminal. A diode 16-3 is connected between the collector terminal and the emitter terminal of the IGBT 16-1 on the upper side of the circuit diagram and the IGBT 16-2 on the lower side of the circuit diagram so that the anode terminal is connected to the emitter terminal.

  The collector terminal of the IGBT 16-1 on the upper side of the circuit diagram of the switching element pair 16u, 16v and 16w provided in the inverter 14 is connected in common, and the common connection end is connected to the positive terminal on the boost output side of the DCDC converter 12. . The emitter terminals of the IGBTs 16-2 on the lower side of the circuit diagram of the switching element pairs 16u, 16v, and 16w are also connected in common, and the common connection terminal is connected to the negative terminal on the boost output side of the DCDC converter 12. .

  The switching element pairs 16 u, 16 v and 16 w correspond to the three-phase power transmission lines U, V and W leading to the motor generator 18. That is, the power transmission line of the corresponding phase is connected to the connection point of the upper IGBT 16-1 and the lower IGBT 16-2 in each switching element pair.

  The IGBT of each switching element pair is switched by the control unit 26. As a result, the inverter 14 performs DC / AC conversion between the DCDC converter 12 and the motor generator 18. That is, the inverter 14 converts the DC power output from the DCDC converter 12 into three-phase AC power according to the magnitude relationship between the voltage on the boost side of the DCDC converter 12 and the voltage between the power transmission lines U, V, and W. And the three-phase AC power is output to the motor generator 18. Further, the inverter 14 converts the three-phase AC power based on the power generation of the motor generator 18 into the DC power according to the magnitude relationship between the voltage on the boost side of the DCDC converter 12 and the voltage between the power transmission lines U, V and W. And the DC power is output to the DCDC converter 12.

  Here, an example is shown in which an IGBT is used as a switching element forming each of the switching element pairs 16u, 16v, and 16w. However, the switching element includes other thyristors, triacs, bipolar transistors, field effect transistors, and the like. A semiconductor element may be used.

  The motor generator 18 includes a rotor that rotates about its shaft, and a three-phase field winding that generates a rotating magnetic field around the rotor. The power transmission lines U, V and W are connected to a three-phase field winding. The motor generator 18 also includes a resolver 28 that detects its rotational phase. The resolver 28 outputs the rotation phase detection value as a phase detection value to the control unit 26. The phase detection value is defined in the range of 0 ° to 360 °. The phase detection value repeats a change of increasing from 0 ° to 360 ° with the rotation of the motor generator 18, reaching 360 °, and increasing from 0 ° to 360 ° again. Further, when the motor generator 18 rotates in the reverse direction, the phase detection value changes from 360 ° to 0 ° with the rotation of the motor generator 18, reaches 0 °, and decreases again from 360 ° to 0 °. repeat.

  The control unit 26 obtains a torque command value based on a command from the driving operation unit 24, a vehicle speed, and the like. The control unit 26 performs PWM control on the three pairs of switching elements using the torque command value and the phase detection value, and each of the power transmission lines U, V, and W is synchronized with the phase detection value. Iu, Iv and Iw are flowed.

  FIG. 2 illustrates the relationship between the phase detection value and the three-phase alternating currents Iu, Iv, and Iw. In FIG. 2, the horizontal axis indicates the phase detection value, and the vertical axis indicates the three-phase alternating currents Iu, Iv, and Iw. Here, it is assumed that the rotational phase of motor generator 18 is defined to increase as the vehicle moves backward. The polarities of the three-phase alternating currents Iu, Iv, and Iw are positive in the direction from the inverter 14 toward the motor generator 18. The three-phase alternating currents Iu, Iv, and Iw change in a sine wave shape with respect to the change in the phase detection value. The mutual phase difference between the three-phase alternating currents Iu, Iv and Iw is 120 °. The maximum value Im of the three-phase alternating currents Iu, Iv and Iw has a value corresponding to the torque command value.

  According to such control, a three-phase alternating current synchronized with the rotational phase of the motor generator 18 flows through the motor generator 18. As a result, the motor generator 18 is synchronously driven according to the rotational phase. The current flowing through the motor generator 18 has a magnitude corresponding to the torque command value, and the motor generator 18 generates torque according to the torque command value.

  A process in which the control unit 26 sets the torque command value will be described. The control unit 26 stores a time characteristic of an upper limit value with respect to the torque command value. FIG. 3A illustrates the time characteristic of the upper limit value with respect to the torque command value. This time characteristic is based on the time when the accelerator pedal is depressed, and defines the time change of the upper limit value thereafter. From time 0 to time t1, the upper limit value increases with time and reaches the maximum torque value M at time t1. The upper limit value maintains the torque maximum value M from time t1 to time t2, and the upper limit value decreases from the torque maximum value M to the continuous output possible value T between time t2 and time t3. After time t3, the upper limit value is a continuously outputable value T.

  The torque command value is set to a larger value as the amount of depression of the accelerator pedal is larger under the condition that the upper limit value is not exceeded. For example, as shown in FIG. 3B, when the amount of depression of the accelerator pedal is increased as time elapses from time 0, the torque command value becomes the upper limit value at time τ1 between time t1 and time t2. Reaches the maximum torque value M, and then the torque command value changes to the same value as the upper limit value.

  According to such a time characteristic of the upper limit value of the torque command value, the time during which the torque command value becomes the torque maximum value M is limited to the time t2-t1 or less. As a result, an excessive current flows through the IGBT of the inverter 14 and the IGBT is prevented from being overheated.

  However, such control may cause the following problems. For example, the wheel 22 and the motor generator 18 may be locked due to the vehicle approaching a steep slope, climbing over an obstacle, fitting the wheel 22 into a recessed portion of the traveling surface, or the like. At this time, the time when the torque command value becomes the torque maximum value M is limited to the time t2-t1 or less, but the current is still concentrated on a specific one of the six IGBTs, so that the IGBT tends to be overheated. It is in.

  Further, when the amount of depression of the accelerator pedal by the user is not sufficient, for example, as shown in FIG. 3C, when the torque command value reaches the continuously output possible value T at time τ2 after time t3, The command value does not become larger than the continuous output possible value T. In this case, the motor generator 18 cannot generate sufficient torque, and it may be difficult to avoid a state where the motor generator 18 is locked.

  In view of such a problem, the electric vehicle driving apparatus according to the present embodiment executes rotation restriction cancellation control described below. According to the rotation restriction cancellation control, the switching element of the inverter 14 is avoided from being overheated, and the torque of the motor generator 18 can be increased.

  FIG. 4 shows a flowchart of processing executed by the control unit 26 in the rotation restriction cancellation control. The control unit 26 obtains the rotation speed of the motor generator 18 based on the time change of the phase detection value output from the resolver 28 (S101). Then, based on the rotational speed of the motor generator 18 and the torque command value, it is determined whether or not the motor generator 18 is in a rotation restricted state (S102). Here, the rotation restricted state refers to a state where the wheel 22 and the motor generator 18 are locked and stopped, as well as a case where the wheel 22 and the motor generator 18 are slightly rotating, that is, a case where the torque command value exceeds a predetermined torque threshold value. Regardless, this includes a state in which the rotational speed of the motor generator 18 is equal to or lower than a predetermined rotational speed threshold. Whether or not the motor generator 18 is in the rotation limit state is determined based on whether or not the rotation speed is equal to or less than the rotation speed threshold value under the condition that the torque command value exceeds the torque threshold value.

  When it is determined that the motor generator 18 is in the rotation restricted state, the control unit 26 obtains a target phase based on the phase detection value read from the resolver 28 (S103). Here, the target phase refers to the rotational phase of the motor generator 18 in which the electrical load of the IGBT is reduced and the overheated state of the IGBT is avoided. The control unit 26 stores a target phase acquisition table representing the correspondence between the numerical range of the phase detection value and the target phase. In step S103, the control unit 26 refers to the target phase acquisition table and corresponds to the phase detection value. Ask for. As will be described later, the control unit 26 executes control for adjusting the rotational phase of the motor generator 18 to the target phase by moving the vehicle using the inclination of the traveling surface and the like, and avoids the overheated state of the IGBT of the inverter 14.

  FIG. 5 illustrates a target phase acquisition table when there is a relationship as shown in FIG. 2 between the phase detection value and the three-phase alternating currents Iu, Iv, and Iw. In this target phase acquisition table, the phase detection values are divided in an angle range of 60 °, and the angle obtained by adding 120 ° to the central value of the angle range of each division is set as the target phase.

  As is apparent from FIG. 2, the magnitude of the specific two-phase current among the three-phase alternating currents Iu, Iv, and Iw is 0.5 Im or more within the angular range of each section of the target phase acquisition table. For example, in the range of 0 ° or more and less than 60 °, the magnitude of the W-phase current is 0.5 Im or more, and the magnitude of the U-phase current is more than 0.5 Im. In the range of 60 ° or more and less than 120 °, the magnitude of the V-phase current is 0.5 Im or more, and the magnitude of the W-phase current is more than 0.5 Im. In the range from 120 ° to less than 180 °, the magnitude of the U-phase current is 0.5 Im or more, and the magnitude of the V-phase current exceeds 0.5 Im. As described above, when the magnitude of a specific two-phase current among the three-phase alternating currents Iu, Iv, and Iw is 0.5 Im or more, the IGBT through which the two-phase current flows is likely to be overheated.

  That is, when U-phase current Iu is 0.5 Im or more and V-phase current Iv is −0.5 Im or less, IGBT 16-1 on the upper side of switching element pair 16u and IGBT 16-2 on the lower side of switching element pair 16v. Is turned on for a longer time than other IGBTs are turned on, and current concentrates on these IGBTs.

  Similarly, when V-phase current Iv is 0.5 Im or more and W-phase current Iw is −0.5 Im or less, IGBT 16-1 on the upper side of switching element pair 16v and IGBT 16- on the lower side of switching element pair 16w. 2 concentrates the current. When W-phase current Iw is 0.5 Im or more and U-phase current Iu is −0.5 Im or less, IGBT 16-1 on the upper side of switching element pair 16w and IGBT 16-2 on the lower side of switching element pair 16u. Current concentrates on. Further, when the current flows in the opposite direction with respect to these states where the current concentrates on a specific IGBT, the IGBTs on which the current concentrates are interchanged.

  Here, the principle that an overheated state of the IGBT is avoided by setting an angle obtained by adding 120 ° to the central value of the angle range of each section as a target phase will be described with reference to FIG. For example, in the range D where the rotational phase detected as the phase detection value is 60 ° or more and less than 120 °, the V-phase current Iv has a value of the threshold value 0.5 Im or more, and the W-phase current is less than the threshold value −0.5 Im. Has a value. Therefore, current concentrates on the IGBT 16-1 on the upper side of the switching element pair 16v and the IGBT 16-2 on the lower side of the switching element pair 16w.

  On the other hand, when the rotation phase is the central value + 120 ° of the range D, that is, 210 °, the current is concentrated on the IGBT 16-1 on the upper side of the switching element pair 16w and the IGBT 16-2 on the lower side of the switching element pair 16u. To do. Further, the V-phase current is 0, and no current flows through the two IGBTs of the switching element pair 16v.

  Therefore, when the motor generator 18 is in the rotation limited state and the phase detection value is in the range D, the IGBT in which the current concentrates is changed by adjusting the rotation phase to 210 °. Similarly, when the phase detection value is within another angle range listed in the target phase acquisition table, the IGBT in which the current concentrates is changed by matching the rotation phase to each target phase. Thereby, it is possible to avoid the overheated state of the IGBT in which the current is concentrated when the motor generator 18 is in the rotation restricted state.

  Under such a principle, the control unit 26 reduces the torque generated by the motor generator 18 and moves the vehicle by the height difference formed by the inclination of the traveling surface, the obstacle, the recessed portion of the traveling surface, and the like. The wheel 22 is rotated to adjust the rotation phase of the motor generator 18 to the target phase (S104 and S105).

  More specifically, the control unit 26 decreases the torque command value by a predetermined decrease amount to decrease the torque generated by the motor generator 18 (S104), and whether or not the phase detection value has reached the target phase. Is determined (S105). When the phase detection value has not reached the target phase, the control unit 26 returns to step S104 and further decreases the torque command value. On the other hand, when the phase detection value reaches the target phase, the control unit 26 sets the torque command value as a rotation limit cancellation torque value larger than the continuous output possible value T, and generates a torque of the rotation limit cancellation torque value in the motor generator 18. (S106). The rotation limit cancellation torque value is, for example, the maximum torque value M shown in FIG.

  On the other hand, if the control unit 26 determines in step S102 that the motor generator 18 is not in the rotation restricted state, the control unit 26 performs torque according to the time characteristic of a predetermined upper limit value as illustrated in FIG. Normal control for setting the command value is executed (S107).

  According to such control, when the motor generator 18 is in the rotation restricted state, the rotation phase of the motor generator 18 is adjusted to the target phase. As a result, it is possible to prevent the specific switching element from being overheated and to cause the motor generator 18 to generate a larger torque for eliminating the rotation limit state.

  Here, as shown in steps S104 and S105 of FIG. 4, the torque generated by the motor generator 18 is reduced, the vehicle is moved by the height difference formed by the inclination of the running surface, etc., and the motor generator 18 rotates. The control for adjusting the phase to the target phase has been described. In addition to such control, the torque generated by the motor generator 18 may be increased to move the vehicle in the up-and-down direction so that the rotational phase of the motor generator 18 matches the target phase.

  The rotation restriction cancellation control shown in the flowchart of FIG. 4 uses the movement of the vehicle due to the height difference formed by the inclination of the traveling surface. Such control is preferably performed positively when the vehicle is located on an inclined surface such as a slope. Therefore, as shown in the flowchart of FIG. 6, it is determined whether or not the vehicle is located on the inclined surface, and processing that uses the inclined surface when it is determined that the vehicle is located on the inclined surface is performed. May be executed. Here, the same processes as those in the flowchart shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

  When the control unit 26 determines in step S102 that the motor generator 18 is in the rotation restricted state, the control unit 26 reads the detected tilt angle value from the tilt sensor 30 that detects the tilt angle of the traveling surface with respect to the horizontal plane. Then, based on the comparison between the detected tilt angle value and the predetermined angle threshold value, it is determined whether or not the vehicle is positioned on the tilted surface (SA101). That is, the control unit 26 determines that the vehicle is positioned on the inclined surface when the detected tilt angle value exceeds a predetermined angle threshold value, and determines that the vehicle is positioned when the detected tilt angle value is equal to or smaller than the angle threshold value. It is determined that it is not located on the inclined surface. This angle threshold is determined in advance based on an angle range in which the vehicle can move in the downward direction of the slope by gravity.

  When the control unit 26 determines that the vehicle is located on the inclined surface, the control unit 26 obtains the target phase based on the phase detection value read from the resolver 28 (S103), and executes the processes after step S104. On the other hand, if it is determined that the vehicle is not located on the inclined surface, the control unit 26 performs normal control (S107).

  According to such a process, when the vehicle is positioned on the inclined surface, control for adjusting the rotational phase of the motor generator 18 to the target phase is performed by moving the vehicle using the inclined surface. On the other hand, normal control is executed when the vehicle is not located on the inclined surface. Thereby, the process using the inclined surface can be surely executed.

  Next, an application example in which control based on IGBT temperature detection is added to the rotation restriction cancellation control shown in FIG. 4 will be described. FIG. 7 shows a flowchart of processing executed by the control unit 26 in such rotation restriction cancellation control. The same processes as those in the flowchart shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

  If the control unit 26 determines in step S102 that the motor generator 18 is in the rotation restricted state, the control unit 26 obtains an estimated temperature value of each IGBT (SA201). This estimated temperature value is obtained based on the detected values of the refrigerant temperature sensor 34 and the current sensor 32. The refrigerant temperature sensor 34 is a sensor that detects the temperature of the refrigerant flowing through the refrigerant pipe provided in the casing of the inverter 14. The current sensor 32 is a sensor that detects the three-phase alternating currents Iu, Iv, and Iw.

  The control unit 26 determines whether or not the temperature estimated value (hereinafter referred to as the maximum temperature estimated value) of the IGBT having the largest temperature estimated value exceeds a specified value (SA202). When the maximum temperature estimated value is equal to or less than the specified value, the control unit 26 performs normal control (SA203) and returns to step S101. On the other hand, when the maximum temperature estimated value exceeds the specified value, the process proceeds to step S103.

  According to steps SA201 to SA203, normal control is executed until the estimated temperature value of the IGBT having the highest temperature exceeds the specified value. On the other hand, when the estimated temperature value of the IGBT having the highest temperature exceeds the specified value and the IGBT is in a temperature rising state that may lead to an overheating state, the rotation phase of the motor generator 18 is adjusted to the target phase after step S103. The process is executed. As a result, when there is a possibility that the rotation restriction state can be eliminated by the normal control, the control unit 26 continues the normal control without executing the processes after step S103.

  Further, after the rotational phase of the motor generator 18 reaches the target phase in step S105 (S105), the control unit 26 determines whether or not the maximum temperature estimated value exceeds a specified value (SA204). When the estimated maximum temperature is equal to or less than the specified value, the torque command value is set as the rotation limit cancellation torque value, and the motor generator 18 is caused to generate the torque of the rotation limit cancellation torque value (S106). On the other hand, when the estimated temperature value exceeds the specified value, the control unit 26 executes normal control. According to such a process, although the rotational phase of the motor generator 18 is adjusted to the target phase, normal control is executed when there is an overheated IGBT. This ensures the protection of the IGBT.

  Here, as shown in steps S104 and S105 of FIG. 7, the torque generated by motor generator 18 is reduced, the vehicle is moved in the downward direction by the inclination of the running surface, and the rotational phase of motor generator 18 is set to the target phase. The control to match the above has been described. In addition to such control, the torque generated by the motor generator 18 may be increased to move the vehicle in the up-and-down direction so that the rotational phase of the motor generator 18 matches the target phase. In this case, it is preferable to make the specified value in step SA202 of the flowchart of FIG. 7 smaller than when the control for reducing the torque is executed.

  In addition, it may be determined whether or not the vehicle is located on an inclined surface, and processing that uses the inclined surface may be executed when it is determined that the vehicle is located on the inclined surface. In this case, as shown in the flowchart of FIG. 8, step SA101 for determining whether or not the vehicle is located on the inclined surface is inserted between step S102 and step SA201. Here, the same processes as those in the flowchart shown in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted.

  When the control unit 26 determines in step S102 that the motor generator 18 is in the rotation restricted state, the control unit 26 reads the detected tilt angle value from the tilt sensor 30 that detects the tilt angle of the traveling surface with respect to the horizontal plane. Then, based on the comparison between the detected tilt angle value and the predetermined angle threshold value, it is determined whether or not the vehicle is positioned on the tilted surface (SA101). When the control unit 26 determines that the vehicle is located on the inclined surface, the control unit 26 obtains the estimated temperature value of each IGBT (SA201), and executes the processes after step SA202. On the other hand, if it is determined that the vehicle is not located on the inclined surface, the control unit 26 performs normal control (S107).

  Further, here, a target phase acquisition table having an angle obtained by adding 120 ° to the central value of the angle range of each section as a target phase is taken up. Instead of such a target phase acquisition table, a target phase acquisition table having an angle obtained by subtracting 120 ° from the central value of the angle range of each section as a target phase may be used.

  Furthermore, instead of using the target phase acquisition table, the control unit 26 may execute a function calculation algorithm using the detected angle value as an independent variable and the target phase as a dependent variable. This function calculation algorithm is programmed in advance based on the target position acquisition table.

  Next, rotation restriction cancellation control according to a modification will be described. FIG. 9 shows a flowchart of processing executed by the control unit 26 in the rotation restriction cancellation control according to the modification. The same processes as those in the flowchart shown in FIG.

  The rotation restriction cancellation control is executed to cancel the rotation restriction state when the rotation phase of the motor generator 18 is within the current peak range. Here, the current peak range refers to an angular range in which the rotational phase at which one of the three-phase alternating currents Iu, Iv, and Iw has a maximum value is a central value. When there is a relationship as shown in FIG. 2 between the phase detection value and the three-phase alternating currents Iu, Iv and Iw, the current peak control ranges are 0 °, 60 °, 120 °, 180 °, 240 ° and Each of 360 ° is set as a central value, and is a range up to ± Δ away from each. Here, Δ is an angle range determined according to the design, for example, 20 °.

  If the control unit 26 determines in step S102 that the motor generator 18 is in the rotation restricted state, it determines whether or not the phase detection value is within the current peak range (SA301). When it is determined that the phase detection value is not within the current peak range, normal control is executed (S107). On the other hand, when it is determined that the phase detection value is within the current peak range, the control unit 26 proceeds to step S103.

  FIG. 10 illustrates the target phase acquisition table used in step S103. In this target phase acquisition table, the phase detection value is defined in the current peak range in the range of the phase detection value between 0 ° and less than 360 °, and the angle obtained by adding 90 ° to the center value of each current peak range is the target phase. Has been.

  The principle by which the overheated state of the IGBT is avoided by setting the angle obtained by adding 90 ° to the center value of each current peak range as the target phase will be described. When the three-phase alternating currents Iu, Iv, and Iw have positive maximum values, currents concentrate on the IGBTs 16-1 on the upper side of the switching element pairs 16u, 16v, and 16w, respectively. Further, when the three-phase alternating currents Iu, Iv, and Iw have negative maximum values, currents concentrate on the IGBTs 16-2 below the switching element pairs 16u, 16v, and 16w, respectively. When the rotational phase of the motor generator 18 is changed by 90 ° in these states, the current that has been the maximum value until then becomes zero. For example, as is clear from FIG. 2, the three-phase alternating currents Iu, Iv, and Iw have maximum values when the rotational phases detected as phase detection values are 0 °, 120 °, and 240 °, respectively. The rotation phase is 0 when 90 ° is added to each rotation phase. Therefore, current concentration on the pair of switching elements that has passed the maximum current is avoided.

  Note that the rotation restriction cancellation control described here also determines whether or not the vehicle is positioned on an inclined surface between Step SA301 and Step S103, as in the rotation restriction cancellation control shown in the flowcharts of FIGS. It is good also as performing determination of. In this case, when it is determined that the vehicle is positioned on the inclined surface, control for adjusting the rotational phase of the motor generator 18 to the target phase is performed by movement of the vehicle using the inclined surface. On the other hand, when it is determined that the vehicle is not located on the inclined surface, normal control is executed.

  Further, similarly to the rotation restriction cancellation control shown in the flowcharts of FIG. 7 and FIG. 8, processing is performed between step SA301 and step S103 to obtain the IGBT temperature estimated value with the largest temperature estimated value as the maximum temperature estimated value. In addition, normal control may be executed when the maximum temperature estimated value exceeds a predetermined value, and processing after step S103 may be executed when the maximum temperature estimated value is equal to or less than the predetermined value.

  Similarly to the rotation restriction cancellation control shown in the flowcharts of FIGS. 7 and 8, after the rotational phase of the motor generator 18 reaches the target phase (S105), the torque command value is rotationally restricted in accordance with the maximum temperature estimated value. It is good also as selectively performing control (S106) used as cancellation torque value, or normal control (S107).

  Further, in the above description, the target phase acquisition table with the angle obtained by adding 90 ° to the central value of each current peak range as the target phase is taken up. Instead of such a target phase acquisition table, a target phase acquisition table having an angle obtained by subtracting 90 ° from the center value of each current peak range as a target phase may be used.

  The electric vehicle driving apparatus has been described above as an embodiment of the present invention. The present invention may be used in a hybrid vehicle drive device. FIG. 11 shows the configuration of the hybrid vehicle drive apparatus. The same components as those of the electric vehicle drive device shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  Motor generator MG2 in this hybrid vehicle drive apparatus accelerates the vehicle and performs regenerative braking. The MG2 inverter 36 performs DC-AC conversion between the DCDC converter 12 and the motor generator MG2. MG2 inverter 36 and motor generator MG2 have the same configuration and function as inverter 14 and motor generator 18 in the electric vehicle drive apparatus shown in FIG.

  The hybrid vehicle driving apparatus further starts the engine 40 and generates electric power by the driving force of the engine 40, and an MG1 inverter 38 that performs DC / AC conversion between the DCDC converter 12 and the motor generator MG1. Is provided. MG1 inverter 38 and motor generator MG1 also have the same configuration and function as inverter 14 and motor generator 18 in the electric vehicle driving apparatus shown in FIG.

  The shafts of engine 40 and motor generators MG1 and MG2 are attached to torque dividing mechanism 42. The torque dividing mechanism 42 applies torque between them. For the torque dividing mechanism 42, for example, a planetary gear unit including a sun gear, a ring gear, and a planetary gear is used. Further, a power transmission mechanism 20 is attached to the shaft of motor generator MG2. For example, a differential gear that reduces the rotational speed of the wheels 22 with respect to the rotational speed of the shaft of the motor generator MG2 is used for the power transmission mechanism 20.

  Torque dividing mechanism 42 transmits the torque generated by at least one of engine 40 and motor generator MG2 to power transmission mechanism 20 by adjusting the rotational states of engine 40, motor generator MG1 and motor generator MG2. Further, torque is transmitted between engine 40 and motor generator MG1.

  DCDC converter 12, MG2 inverter 36 and motor generator MG2 operate in the same manner as DCDC converter 12, inverter 14 and motor generator 18 shown in FIG. 1, and motor generator MG2 is based on the power supplied from battery 10. Torque is generated, the vehicle is accelerated with the torque, and the battery 10 is charged with generated power based on regenerative braking by the motor generator MG2.

  In the hybrid vehicle drive apparatus, as in the electric vehicle drive apparatus shown in FIG. 1, when the motor generator MG2 is in the rotation restricted state, the rotation restriction shown in FIG. 4, FIG. 6, FIG. 7, FIG. Control is executed. Thus, it is possible to avoid a specific switching element included in MG2 inverter 36 from being overheated, and to generate a larger torque in motor generator MG2 for eliminating the rotation restriction state.

  10 battery, 12 DCDC converter, 14 inverter, 16u, 16v, 16w switching element pair, 16-1, 16-2 IGBT, 16-3 diode, 18 motor generator, 20 power transmission mechanism, 22 wheels, 24 driving operation unit, 26 control unit, 28 resolver, 30 tilt sensor, 32 current sensor, 34 refrigerant temperature sensor, 36 MG2 inverter, 38 MG1 inverter, 40 engine, 42 torque dividing mechanism.

Claims (9)

A power converter that converts DC power to AC power by switching;
A motor that drives the vehicle with three-phase AC power supplied from the power converter;
Switching the power conversion unit according to the rotational phase of the motor, and a control unit for controlling the motor,
The power converter is
Three switching element pairs each having two switching elements connected in series are provided, DC power is supplied to both ends of a series connection path formed by each switching element pair, and the motor is connected to the motor from the series connection point of each switching element pair. AC power to
The control unit is
Switching the power conversion unit so that a three-phase alternating current flowing between the power conversion unit and the motor is synchronized with the rotation phase of the motor;
When the motor is in a rotation restricted state, the motor is controlled so that the rotation phase of the motor reaches a target phase corresponding to the rotation phase of the motor at that time ,
The target phase is
Of the three pairs of switching elements, the current flowing through one pair of switching elements is zero, and for each of the other two pairs of switching elements, one of the two switching elements connected in series is turned on. It is a phase where switching elements are switched,
The vehicle drive device characterized by the above-mentioned. A power converter that converts DC power to AC power by switching;
A motor that drives the vehicle with AC power supplied from the power converter;
Switching the power conversion unit according to the rotational phase of the motor, and a control unit for controlling the motor,
The control unit is
When the motor is in a rotation limited state, the motor is controlled so that the rotation phase of the motor reaches a target phase corresponding to the switching state of the power conversion unit at that time ,
The control unit is
A torque command value determining means for determining a torque command value for the motor according to a driving operation of the vehicle;
Switching the power converter according to the torque command value,
The torque command value determining means includes
A value larger than an upper limit value when the motor is not in the rotation restricted state when the rotation phase of the motor reaches the target phase by the control of the control unit when the motor is in the rotation restricted state. The torque command value is determined with the upper limit as
The vehicle drive device characterized by the above-mentioned. The vehicle drive device according to claim 2,
The power conversion unit includes three pairs of switching elements each including two switching elements connected in series,
DC power is supplied to both ends of the series connection path formed by each pair of switching elements,
AC power is supplied to the motor from a series connection point of each switching element pair.
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to claim 1 ,
The control unit is
A torque command value determining means for determining a torque command value for the motor according to a driving operation of the vehicle;
Switching the power converter according to the torque command value,
The torque command value determining means includes
A value larger than an upper limit value when the motor is not in the rotation restricted state when the rotation phase of the motor reaches the target phase by the control of the control unit when the motor is in the rotation restricted state. The torque command value is determined with the upper limit as
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to any one of claims 2 to 4 ,
The control unit is
Means for determining whether the element is in an overheated state based on the temperature of the element included in the power conversion unit;
The torque command value determining means includes
From the upper limit value when the motor is not in the rotation limit state when it is determined that the element is not in the overheat state after control of the control unit when the motor is in the rotation limit state. The torque command value is determined with a larger value as an upper limit value,
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to any one of claims 1 to 5,
The control unit is
Means for determining whether or not the element is in a temperature rising state based on the temperature of the element included in the power conversion unit;
Controlling the motor so that the rotational phase of the motor reaches the target phase when it is determined that the motor is in a rotational restricted state and the element is in the temperature rising state;
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to any one of claims 1 to 6,
The control unit is
When the motor is in the rotation restricted state, the torque generated by the motor is reduced, and the motor is rotated based on the movement of the vehicle due to a height difference on a running surface;
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to any one of claims 1 to 7,
An inclination sensor for detecting an inclination angle of the traveling surface of the vehicle;
The control unit is
Means for determining whether the vehicle is located on an inclined surface based on a detection value by the inclination sensor;
When it is determined that the motor is in the rotation restricted state and the vehicle is located on an inclined surface, the torque generated by the motor is reduced, based on the movement of the vehicle due to the inclination of the traveling surface. Rotating the motor;
The vehicle drive device characterized by the above-mentioned. In the vehicle drive device according to any one of claims 1 to 6,
The control unit is
When the motor is in the rotation restricted state, the torque generated by the motor is increased, and the motor is rotated based on the movement of the vehicle due to the increase in the torque.
The vehicle drive device characterized by the above-mentioned.

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