Control device, control method, and program

Abstract

[Problem] To improve the warm-up performance of a battery. [Solution] A control device converts DC power of a battery into multi-phase AC power and performs vector control on a motor for a vehicle, and causes a d-axis current to flow through the motor to warm up the battery, which supplies power to the motor. When the temperature of the battery is equal to or lower than a predetermined value, the control device causes the rotor of the motor to rotate in a direction in which the current value of the phase having the largest d-axis current among the multiple phases decreases in a stopped state, and thereby causes the d-axis current for warm-up to flow.

Description

Control device, control method, and program

[0001] The present invention relates to a control device, a control method, and a program.

[0002] Patent Document 1 discloses a control device for a motor for vehicle travel.

[0003] This control device sets the q-axis current value for vector control of the motor to zero when the vehicle is stopped, or to a current value that generates driving torque allowing the vehicle to creep when braking is released, and sets a d-axis current value that allows battery warm-up operation. The d-axis current value is set to increase as the battery temperature decreases.

[0004] Japanese Patent Application Laid-Open No. 2012-165526

[0005] In this control device, depending on the position of the motor rotor when the vehicle is stopped, there are cases where the d-axis current value cannot be increased, and improvement of battery warm-up performance is required.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a control device, a control method, and a program capable of improving battery warm-up performance.

[0007] According to an aspect of the present invention, there is provided a control device that converts DC power of a battery into AC power of a plurality of phases to perform vector control on a vehicle motor, and warms up the battery that supplies power to the motor by passing a d-axis current through the motor, wherein when the temperature of the battery is equal to or lower than a predetermined value, the rotor of the motor is rotated in a direction in which the current value of the phase having the largest d-axis current among the plurality of phases decreases in a stopped state, so that the d-axis current for warm-up is passed through the motor.

[0008] According to one aspect of the present invention, in a stationary state, the current value of the phase with the largest d-axis current decreases as the rotor rotates. When the motor is not rotating, the rotor position does not change, so a large current continues to flow through the same phase, and the temperature of the phase with the largest d-axis current becomes the highest. If only the current flowing through this phase is large, the temperature of this phase will become too high, and it will not be possible to supply d-axis current for warming up. In contrast, the control device rotates the rotor in such a way that the current value of the phase with the largest d-axis current decreases, thereby suppressing the temperature rise of this phase while increasing the current supplied to the other phases.

[0009] Therefore, it becomes possible to increase the overall d-axis current flowing through the motor. This makes it possible to improve the battery's warm-up performance.

[0010] Figure 1 shows a vehicle equipped with the control device according to this embodiment. Figure 2 shows the refrigerant flow during normal operation. Figure 3 shows the refrigerant flow during warm-up operation. Figure 4 shows the d-axis current. Figure 5 shows the temperature of the coils in each phase. Figure 6 is a flowchart showing the operation of the control unit.

[0011] The control device 10 according to an embodiment of the present invention will be described below with reference to the attached drawings. The present invention includes, but is not limited to, the following configurations.

[0012] Figure 1 shows a vehicle 26 equipped with the control device 10 according to this embodiment. Figure 2 shows the flow of refrigerant during normal operation. Figure 3 shows the flow of refrigerant during warm-up operation.

[0013] As shown in Figure 1, the control device 10 according to this embodiment warms up the battery 22 that supplies power to the motor 20 for vehicle drive by supplying a d-axis current to the motor 20.

[0014] An example of a vehicle 26 on which the control device 10 is installed is an electric vehicle. An electric vehicle includes a motor 20 that drives the vehicle 26 when it is running, and a battery 22 that supplies power to the motor 20.

[0015] The battery 22's charge and discharge performance deteriorates at low temperatures. When charge and discharge performance deteriorates, for example, the charging time for the battery 22 increases. Therefore, the battery 22 is warmed at low temperatures to suppress performance degradation.

[0016] The vehicle 26, equipped with the control device 10, includes the aforementioned battery 22 and an inverter 30 that converts the DC power of the battery 22 into AC power. The vehicle 26 is equipped with a motor 20 that rotates the wheels T of the vehicle 26 using AC power supplied from the inverter 30, and the control device 10 controls the motor 20.

[0017] (Cooling passage) The vehicle 26 is also equipped with a cooling passage 40 (for example, a refrigerant circulation passage) through which the refrigerant flows. The cooling passage 40 allows the refrigerant to flow between the inverter 30, the motor 20, the radiator 42, and the battery 22. The cooling passage 40 has a first switching valve 46 that switches the flow of refrigerant from the motor 20 to the radiator 42 or the battery 22, and a second switching valve 48 that switches the flow of refrigerant from the radiator 42 or the battery 22 to the inverter 30. The first switching valve 46 and the second switching valve 48 operate, for example, according to a switching signal from the control device 10.

[0018] (Normal operating state) As shown in Figure 2, in a normal operating state 50, such as during driving, when the heat of the inverter 30 and motor 20 may rise, the control device 10 switches the second switching valve 48 so that the refrigerant from the radiator 42 flows to the inverter 30. The control device 10 also switches the first switching valve 46 so that the refrigerant from the motor 20 flows to the radiator 42.

[0019] As a result, the refrigerant circulates between the inverter 30, the motor 20, and the radiator 42, releasing the heat generated in the inverter 30 and the motor 20 through the radiator 42 to cool the inverter 30 and the motor 20.

[0020] (Battery warm-up state) As shown in Figure 3, in the battery warm-up state 52, in which the low-temperature battery 22 is warmed, the control device 10 switches the first switching valve 46 so that the refrigerant from the motor 20 flows to the battery 22. The control device 10 also switches the second switching valve 48 so that the refrigerant from the battery 22 flows to the inverter 30.

[0021] As a result, the refrigerant circulates between the inverter 30, motor 20, and battery 22, and the heat generated by the inverter 30 and motor 20 warms the battery 22. In other words, by suppressing overheating of a specific phase, current limitations due to the inverter's temperature threshold are avoided, making it possible to increase the total d-axis current of all phases. Consequently, both the internal heat generated by the battery and the heat generated by the inverter can be used for warming up, and by using this in conjunction with refrigerant path switching, warming efficiency can be improved.

[0022] (Battery) As shown in Figures 1 to 3, the battery 22 is composed of a secondary battery capable of charging and discharging high voltage. The battery 22 is such that, for example, the coolant from the cooling passage 40 flows along its outer surface. The battery 22 is capable of heat exchange with the coolant from the cooling passage 40.

[0023] The battery 22 has a temperature sensor S that detects the battery temperature of the battery 22. The temperature sensor S outputs the detected battery temperature to the control device 10.

[0024] (Motor) The motor 20 is a three-phase AC motor that operates on three-phase alternating current. In the motor 20, for example, the coolant in the cooling passage 40 flows along the outer surface. The motor 20 has a U-phase coil 100 (see Figure 5), a V-phase coil 102 (see Figure 5), and a W-phase coil 104 (see Figure 5).

[0025] The output shaft of the motor 20 is connected to the wheel T via a gear mechanism G having a park lock mechanism PL. The gear mechanism G has multiple gears that mesh with each other. The gear mechanism G reduces the rotation of the motor 20 and transmits it to the wheel T.

[0026] The park lock mechanism PL prevents the rotation of each gear, making the wheels T unable to rotate, when the shift switch (e.g., shift lever) of the vehicle 26 is set to park. When the parking is released, the park lock mechanism PL allows the rotation of each gear, making the wheels T rotatable.

[0027] The motor 20 has a rotation sensor RS that detects the rotation of a rotor (not shown) of the motor 20. The rotation sensor RS detects the rotation of the rotor by detecting the rotation angle of the rotor. The rotation sensor RS outputs the detected rotation angle to the control device 10.

[0028] (Inverter) The inverter 30 is composed of an electronic circuit including a power transistor that controls the power supply to the motor 20. In the inverter 30, for example, the power transistor is cooled by the coolant in the cooling passage 40.

[0029] The inverter 30 converts the DC current from the battery 22 into three-phase AC current according to the control signal from the control device 10 and outputs it to the motor 20. The inverter 30 changes the phase of the output three-phase AC current according to the control signal from the control device 10.

[0030] The inverter 30 supplies the U-phase current 70 (see Figure 4), which constitutes a three-phase alternating current, to the U-phase coil 100 of the motor 20. The inverter 30 supplies the V-phase current 72 (see Figure 4) to the V-phase coil 102 of the motor 20. The inverter 30 supplies the W-phase current 74 (see Figure 4) to the W-phase coil 104 of the motor 20.

[0031] (Control Unit) The control unit 10 is composed of a microcomputer, which is a computer equipped with a CPU, RAM, ROM, input / output interface, etc. The control unit 10 performs various processes and executes control methods by having the CPU read and execute a program stored in the ROM. The control unit 10 can also be composed of multiple microcomputers.

[0032] The control device 10 operates the inverter 30 with the control signal it outputs, converting the DC power from the battery 22 into three-phase AC power with multiple phases to vector control the motor 20. The control device 10 changes the control signal it outputs to the inverter 30 based, for example, on the amount the accelerator pedal is pressed.

[0033] Furthermore, when warming up the battery 22 while the vehicle is stopped, the control device 10 sets the cooling passage 40 to a battery warm-up state 52 (see Figure 3). The control device 10 also supplies a d-axis current to the motor 20 that does not generate rotational torque. As a result, the control device 10 generates heat in the motor 20 and the inverter 30 that supplies power to the motor 20, and transfers that heat to the battery 22 via the refrigerant in the cooling passage 40, thereby warming the battery 22.

[0034] At this time, the control device 10 can increase the amount of heat generated by the motor 20 and inverter 30 by increasing the d-axis current, thereby accelerating the warming up of the battery 22.

[0035] (d-axis current) Here, the d-axis current will be explained using Figures 4 and 5.

[0036] Figure 4 shows the d-axis current. Figure 5 shows the temperature of the coils in each phase.

[0037] Figure 4 shows the d-axis current corresponding to the rotation angle of the rotor of the motor 20. The curves shown in Figure 4 show the current changes of each phase corresponding to the d-axis current. The relationship between the rotor rotation angle and the d-axis current of each phase differs depending on the configuration of the motor 20. The d-axis current consists of the U-phase current 70, which flows through the U-phase coil 100 of the motor 20, the V-phase current 72, which flows through the V-phase coil 102, and the W-phase current 74, which flows through the W-phase coil 104.

[0038] As shown in Figure 4, when the vehicle is stopped, the control device 10 may not be able to increase the d-axis current that can be supplied to the motor 20 depending on the rotor position. An example of a situation where the d-axis current cannot be increased is the U-phase concentrated position 80 where the U-phase current 70 is maximized at either a positive or negative value (in other words, the absolute value of the U-phase current 70 is maximized). Another example of a situation where the d-axis current cannot be increased is the V-phase concentrated position 82 where the V-phase current 72 is maximized at either a positive or negative value (in other words, the absolute value of the V-phase current 72 is maximized). Furthermore, an example of a situation where the d-axis current cannot be increased is the W-phase concentrated position 84 where the W-phase current 74 is maximized at either a positive or negative value (in other words, the absolute value of the W-phase current 74 is maximized).

[0039] Specifically, for example, when the rotor stops at the U-phase concentrated position 80 where the U-phase current 70 reaches a maximum with a polarity of "+" or "-", the control device 10 cannot further increase the U-phase current 70.

[0040] Here, the control device 10 needs to maintain the relationship between the phase currents 70, 72, and 74 so as not to generate rotational torque in the motor 20. For this reason, the control device 10 cannot increase the V-phase current 72 and the W-phase current 74 either, and cannot promote warming-up of the battery 22.

[0041] On the other hand, when the rotor stops at a position other than the position where each phase current 70, 72, 74 reaches a maximum, the control device 10 can increase each of the phase currents 70, 72, 74 within a range that does not generate rotational torque in the motor 20. In this case, the d-axis current supplied to the coils of each phase of the motor 20 increases as a whole, leading to an increased amount of heat generation, so that warming-up of the battery 22 can be promoted.

[0042] An example of the case where the rotor stops at a position other than the position where each phase current 70, 72, 74 reaches a maximum is the U-phase zero position 88 where the U-phase current 70 becomes "0".

[0043] As shown in FIG. 5, in a first stopped state 90 where the rotor stops at the U-phase concentrated position 80, the temperature of the U-phase coil 100 of the motor 20 becomes higher than the temperatures of the V-phase coil 102 and the W-phase coil 104.

[0044] On the other hand, in a second stopped state 92 where the rotor stops at the U-phase zero position 88, the temperatures of the V-phase coil 102 and the W-phase coil 104 become higher than the temperature of the U-phase coil 100. Since the V-phase current 72 flowing through the V-phase coil 102 and the W-phase current 74 flowing through the W-phase coil 104 are smaller than the maximum values (see FIG. 4), the temperatures of the V-phase coil 102 and the W-phase coil 104 are lower than the temperature of the U-phase coil 100 in the first stopped state 90.

[0045] Here, the V-phase current 72 flowing through the V-phase coil 102 and the W-phase current 74 flowing through the W-phase coil 104 are smaller than the maximum value. Therefore, the V-phase current 72 and the W-phase current 74 have a margin that allows the currents to be increased up to the maximum value. Accordingly, the control device 10 can increase the V-phase current 72 and the W-phase current 74 to the maximum values while maintaining the relationship among the phase currents 70, 72, and 74 so as not to generate rotational torque in the motor 20. In this way, reducing the inter-phase temperature difference may reduce the long-term risk of material deterioration.

[0046] When the V-phase current 72 and the W-phase current 74 are increased, the total amount of d-axis current supplied to the coils of each phase of the motor 20 increases, resulting in a larger amount of heat generation, thus making it possible to promote warming-up of the battery 22. When increasing each phase current, control is performed to maintain the overall phase relationship between phases and keep the torque at zero.

[0047] (Description of Operation) The operation of the control device 10 will be described with reference to the drawings. FIG. 6 is a flowchart showing the operation of the control device 10.

[0048] The control device 10 acquires the battery temperature of the battery 22 from the temperature sensor S (step S10). The control device 10 determines whether or not the acquired battery temperature is equal to or lower than a predetermined value set in advance (step S12). The predetermined value is a temperature determined based on the charge and discharge performance of the battery 22, and is, for example, the temperature of the battery 22 at which the charging performance sharply decreases.

[0049] In step S12, if the acquired battery temperature exceeds the predetermined value, the control device 10 terminates this process. In step S12, if the acquired battery temperature is equal to or lower than the predetermined value, the control device 10 outputs switching signals to the first switching valve 46 and the second switching valve 48 of the cooling passage 40 to form a battery warm-up state 52 (step S13). Further, the control device 10 acquires a vehicle stop state (step S14), and determines whether or not the vehicle 26 is stopped (step S16).

[0050] The stationary state is obtained, for example, from a vehicle speed sensor (not shown) and a park lock mechanism PL installed on the vehicle 26. Whether or not the vehicle is stationary is determined by whether the vehicle speed obtained from the vehicle speed sensor is "0" and whether or not the park lock mechanism PL is in a locked state that prevents the wheels T from rotating. If the vehicle speed is "0" and the park lock mechanism PL is in a locked state, the control device 10 determines that the vehicle is stationary.

[0051] In step S16, if it is determined that the vehicle is not stopped, the control device 10 terminates this process. In step S16, if it is determined that the vehicle is stopped, the control device 10 obtains the rotation angle of the motor 20 rotor from the rotation sensor RS (step S18), and based on the obtained rotation angle, obtains the phase with the largest d-axis current among the multiple phases (step S20). To obtain the phase with the largest d-axis current, for example, a database is used in which the relationship between the rotation angle of the motor 20 rotor shown in Figure 4 and the U-phase current 70, V-phase current 72, and W-phase current 74 as d-axis currents is digitized. The control device 10 is equipped with a recording unit that records the acquisition logs of rotation angle information from the rotation sensor RS and the acquisition logs of each phase current value from the inverter 30, and identifies the phase with the largest d-axis current based on the logs.

[0052] Furthermore, the control device 10 determines whether the acquired rotation angle is within a predetermined range (step S22).

[0053] As shown in Figure 4, the predetermined range consists of a first predetermined range 110, a second predetermined range 112, a third predetermined range 114, a fourth predetermined range 116, a fifth predetermined range 118, and a sixth predetermined range 120, each defined around the rotation angle of each phase convergence position 80, 82, and 84. Each predetermined range 110, 112, 114, 116, 118, and 120 is defined within a range of several degrees before and after the rotation angle of each phase convergence position 80, 82, and 84. Each predetermined range 110, 112, 114, 116, 118, and 120 is defined within a range where the current value of the corresponding phase current (70, 72, 74) does not fall below the current value of the other phase currents (70, 72, 74).

[0054] To give an example, the first predetermined range 110 is determined around the rotation angle of the U-phase concentration position 80. The first predetermined range 110 is determined within a range of several degrees before and after the rotation angle of the U-phase concentration position 80. This first predetermined range 110 is determined within a range in which the current value of the U-phase current 70 does not fall below the current value of the V-phase current 72 and the current value of the W-phase current 74.

[0055] In step S22, if the acquired rotation angle is not within any of the predetermined ranges (110, 112, 114, 116, 118, 120), the control device 10 terminates this process. In step S22, if the acquired rotation angle is within any of the predetermined ranges (110, 112, 114, 116, 118, 120), the control device 10 rotates the rotor of the motor 20 in the direction that reduces the current value of the phase with the largest d-axis current (step S24). In step S24, the control device 10 rotates the rotor of the motor 20 by a predetermined angle set in advance.

[0056] The predetermined angle is a value set in advance within a range where, even when the rotor is rotated, the current value of the phase with the largest d-axis current does not become smaller than the current values ​​of the other phases. Furthermore, the predetermined angle is greater than or equal to the minimum angle detectable by the resolution of the rotation sensor RS that detects the rotation of the rotor, and is set according to the specifications of the rotation sensor RS. In addition, the predetermined angle is less than or equal to the play in the gear mechanism G that transmits the rotational force of the motor 20. The angle less than or equal to the play is the angle less than or equal to the angle at which the gear mechanism G can rotate freely due to its play. That is, the angle of play in the gear mechanism G is the relative angle that is permissible due to the meshing gap, tooth surface clearance, mounting errors, etc., and as an example of an embodiment, it includes a range such as 0.1° to 1°.

[0057] As a result, after the park lock mechanism PL forms a locked state, the control device 10 rotates the rotor in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases. Part or all of this control can be executed on an in-vehicle device or in the cloud / server.

[0058] To illustrate with an example, if the rotation angle of the stationary rotor is within the first predetermined range 110, the control device 10 acquires the U-phase current 70 as the phase with the largest d-current because the current value of the U-phase current 70 as the d-axis current is largest at the acquired rotor rotation angle. Furthermore, since the rotor rotation angle is within the first predetermined range 110, the control device 10 outputs a control signal to the inverter 30 to rotate the rotor by a predetermined angle in the direction that decreases the current value of the U-phase current 70 as the d-axis current.

[0059] If the rotor's rotation angle is smaller than the rotation angle indicated by the U-phase concentration position 80, the control device 10 rotates the rotor by a predetermined angle in the direction that reduces the rotor's rotation angle, so that the current value (absolute value of the current) of the U-phase current 70 decreases.

[0060] On the other hand, if the rotor's rotation angle is greater than the rotation angle indicated by the U-phase concentration position 80, the control device 10 rotates the rotor by a predetermined angle in the direction that increases the rotor's rotation angle, so that the current value (absolute value of the current) of the U-phase current 70 decreases.

[0061] In this case, the predetermined angle is greater than or equal to the minimum angle detectable by the resolution of the rotation sensor RS. Therefore, the rotor's rotation angle is controlled with high precision. Furthermore, the predetermined angle is less than or equal to the play in the gear mechanism G. Therefore, the motor 20 is rotated without rotating the wheel T.

[0062] Here, depending on the stopping conditions when the vehicle 26 is stopped, it may not be possible to rotate the rotor in the same direction as the direction of travel before stopping. In this case, while the vehicle is stopped, control is performed to rotate the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases, but it is possible that the current value may become larger than before rotation.

[0063] Thus, if the d-axis current value becomes larger than before rotation when the rotor is rotated after stopping, the control device 10 outputs a control signal to the inverter 30 again to return the rotor to its position before rotation.

[0064] Then, the control device 10 sets the warm-up d-axis current (step S26), and flows the set warm-up d-axis current to the motor 20 (step S28), thereby ending this process. The warm-up d-axis current is the current obtained by multiplying the d-axis current corresponding to the rotation angle after the rotor has been rotated by a predetermined angle in the direction in which the current value of the d-axis current decreases by an increase.

[0065] As a result, the U-phase coil 100 of the motor 20 receives a warm-up d-axis current which is the U-phase current 70 corresponding to the rotation angle after rotation multiplied by an increase. The V-phase coil 102 receives a warm-up d-axis current which is the V-phase current 72 corresponding to the rotation angle after rotation multiplied by an increase. The W-phase coil 104 receives a warm-up d-axis current which is the W-phase current 74 corresponding to the rotation angle after rotation multiplied by an increase.

[0066] (Operation and Effects) The main operations and effects of the control device 10 configured as described above will be summarized below.

[0067] (1) The control device 10 converts the DC power of the battery 22 into AC power of multiple phases to vector control the motor 20 for the vehicle, and also warms up the battery 22 that supplies power to the motor 20 by supplying a d-axis current to the motor 20. When the temperature of the battery 22 is below a predetermined value (step S12), the control device 10 rotates the rotor of the motor 20 in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases (step S24) while the vehicle is stationary (step S16), and supplies a d-axis current for warming up (step S26). That is, while the vehicle is stationary, the control device 10 has means to control the rotor of the motor 20 so that the current value of the phase with the largest d-axis current changes in a predetermined decreasing direction by changing the rotation angle of the rotor of the motor 20, and supplies a d-axis current for warming up set by said means.

[0068] (8) The control method is a method of converting the DC power of the battery 22 into AC power of multiple phases to vector control the motor 20 for the vehicle, and also warming up the battery 22 that supplies power to the motor 20 by flowing a d-axis current to the motor 20. The control method is as follows: When the temperature of the battery 22 is below a predetermined value (step S12), in a stationary state (step S16), the rotor of the motor 20 is rotated in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases (step S24) to flow a d-axis current for warming up (step S26).

[0069] (9) The program is a computer-executable program that converts the DC power of the battery 22 into AC power of multiple phases to vector control the motor 20 for the vehicle, and also warms up the battery 22 that supplies power to the motor 20 by supplying a d-axis current to the motor 20. The program instructs the computer to perform a procedure to supply a warm-up d-axis current by rotating the rotor of the motor 20 in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases (step S24) when the temperature of the battery 22 is below a predetermined value (step S12), while the vehicle is stationary (step S16).

[0070] According to this embodiment, in a stationary state, the current value of the phase with the largest d-axis current decreases as the rotor of the motor 20 rotates. When the motor 20 is not rotating, the rotor position does not change, so a large current continues to flow through the same phase, and the temperature of the phase with the largest d-axis current becomes the highest. If only the current flowing through this phase is large, the temperature of this phase will become too high, and it will not be possible to supply d-axis current for warming up. In contrast, the control device 10 rotates the rotor so that the current value of the phase with the largest d-axis current decreases, thereby suppressing the temperature rise of this phase while increasing the current supplied to the other phases. In other words, the rotation of the rotor of the motor 20 reduces the current value of a specific phase, suppressing the temperature rise of that phase. As a result, the inverter 30 and protection limits (current limits due to temperature rise) are released, and the total sum of d-axis currents that can be supplied to all phases increases. That is, in response to the problem that constant d-axis control regardless of rotor position has low warming efficiency, the present invention improves warming efficiency by utilizing rotor position dependence to increase the supply current to all phases while avoiding the temperature rise of a specific phase. (c) When used in conjunction with refrigerant path switching, warm-up efficiency can be improved.

[0071] In this way, it becomes possible to increase the overall d-axis current flowing through the motor 20. This makes it possible to improve the warm-up performance of the battery 22.

[0072] Furthermore, the control device 10, the control method implemented by the control device 10, and the program of the control device 10 can enhance the warm-up function of the battery 22. As a result, the control device 10 and the like can improve the charge and discharge efficiency of the battery 22 without using a PTC (Positive Temperature Coefficient) heater or the like to warm the battery 22. In other words, when this control is applied to a vehicle, the battery can reach the required temperature in a short time without using a PTC or the like which was conventionally required, thus contributing to a reduction in the vehicle's energy consumption and load weight.

[0073] In addition to the method of transferring heat from the motor 20 and inverter 30 to the battery 22 using a coolant, a method of warming up the battery 22 by increasing the current supplied to the motor 20 can also be described as a method of warming up the battery 22 by its own heat generated during power supply.

[0074] (2) In the control device 10, the motor 20 is a three-phase AC motor that operates on three-phase AC power, and the multiple phases are three-phase. When the rotation angle of the rotor is within a predetermined range (110, 112, 114, 116, 118, 120) (step S22), the control device 10 rotates the rotor in a direction that decreases the current value of the phase with the largest d-axis current among the three phases (step S24).

[0075] In this embodiment, the current value of the phase with the largest d-axis current decreases as the rotor rotates, making it possible to increase the current that can be increased for that phase, and also to increase the current of all phases, including that phase.

[0076] This makes it possible to efficiently warm up the battery 22.

[0077] (3) The control device 10 is installed in a vehicle 26 equipped with a park lock mechanism PL that can create a locked state in which the park wheels T cannot rotate while the vehicle is stationary. After the park lock mechanism PL has created a locked state (step S16), the control device 10 rotates the rotor in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases (step S24).

[0078] In this embodiment, even if the rotor rotates slightly when the park lock mechanism PL forms a locked state, the control device 10 rotates the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases. As a result, the control device 10 can improve the warm-up performance of the battery 22, as described above.

[0079] (4) When the control device 10 rotates the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases, it rotates the rotor by a predetermined angle (step S24).

[0080] In this embodiment, the control device 10 rotates the rotor by a predetermined angle when rotating the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases, making it possible to rotate the rotor by a preset appropriate angle.

[0081] (5) When the control device 10 rotates the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases, it rotates the rotor at an angle less than or equal to the play in the gear mechanism G that transmits power from the motor 20 (step S24).

[0082] In this embodiment, the rotor is rotated by an angle less than or equal to the play in the gear mechanism G, so the control device 10 can rotate the motor 20 without rotating the wheel T.

[0083] (6) When the control device 10 rotates the rotor in a direction that reduces the current value of the phase with the largest d-axis current among the multiple phases, it rotates the rotor by an angle greater than or equal to the minimum angle detectable by the resolution of the rotation sensor RS that detects the rotation of the rotor (step S24).

[0084] In this embodiment, the rotating rotor is rotated by an angle greater than or equal to the minimum angle detectable by the resolution of the rotation sensor RS. Therefore, the control device 10 can control the rotation angle of the rotor with greater precision compared to the case where the rotor is rotated by an angle less than the minimum angle detectable by the resolution of the rotation sensor RS.

[0085] (7) When the vehicle is stationary, the control device 10 rotates the rotor in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases. If the current value becomes greater than before the rotation, the control device 10 returns the rotor to its position before the rotation (step S24).

[0086] In this embodiment, if the current value after rotating the rotor becomes greater than before rotation, the control device 10 can return the rotor to its position before rotation, thereby maintaining improved warm-up performance of the battery 22.

[0087] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the embodiments described above. For example, the present invention is not limited to three phases but can also be applied to N phases (N = natural number). Furthermore, the elements shown in each embodiment can be combined arbitrarily, and the combinations described in the claims can be implemented as any combination of the configurations described in the specification.

[0088] 10 Control device 20 Motor 22 Battery 26 Vehicle 52 Battery warm-up state 70 U-phase current 72 V-phase current 74 W-phase current G Gear mechanism PL Park lock mechanism RS Rotation sensor

Claims

1. A control device for warming up a battery that converts DC power from a battery into AC power of multiple phases to vector control a motor for a vehicle and supplies power to the motor by flowing a d-axis current through the motor, wherein when the temperature of the battery is below a predetermined value, the control device rotates the rotor of the motor in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases when the vehicle is stationary, thereby flowing the d-axis current for warming up.

2. A control device according to claim 1, wherein the motor is a three-phase AC motor that operates on three-phase AC, the plurality of phases are three-phase, and the control device rotates the rotor in a direction that decreases the current value of the phase with the largest d-axis current among the three phases when the rotation angle of the rotor is within a predetermined range.

3. A control device according to claim 1 or claim 2, provided in a vehicle equipped with a park lock mechanism capable of forming a locked state that prevents the wheels from rotating while the vehicle is stationary, wherein, after the park lock mechanism has formed the locked state, the control device rotates the rotor in a direction that decreases the current value of the phase among the plurality of phases in which the d-axis current is largest.

4. A control device according to claim 3, wherein when the rotor is rotated in a direction that reduces the current value of the phase with the largest d-axis current among the plurality of phases, the rotor is rotated by a predetermined predetermined angle.

5. A control device according to claim 3, wherein when the rotor is rotated in a direction that reduces the current value of the phase with the largest d-axis current among the plurality of phases, the control device rotates the rotor by an angle less than or equal to the play of the gear mechanism that transmits power to the motor.

6. A control device according to claim 3, wherein when the rotor is rotated in a direction that decreases the current value of the phase with the largest d-axis current among the plurality of phases, the control device rotates the rotor by an angle greater than or equal to the minimum angle detectable by the resolution of the rotation sensor that detects the rotation of the rotor.

7. A control device according to claim 1, wherein, in the stationary state, the rotor is rotated in a direction that decreases the current value of the phase with the largest d-axis current among the plurality of phases, and if the current value becomes greater than before rotation, the rotor is returned to the position before rotation.

8. A control method for warming up a battery that converts DC power from a battery into AC power of multiple phases to vector control a motor for a vehicle and supplies power to the motor by flowing a d-axis current through the motor, wherein when the temperature of the battery is below a predetermined value, the rotor of the motor is rotated in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases while the vehicle is stationary, thereby flowing the d-axis current for warming up.

9. A computer-executable program for warming up a battery that converts DC power from a battery into AC power of multiple phases to vector control a motor for a vehicle and supplies power to the motor by flowing a d-axis current through the motor, wherein the program causes the computer to execute a procedure in which, when the temperature of the battery is below a predetermined value, the rotor of the motor is rotated in a direction that decreases the current value of the phase with the largest d-axis current among the multiple phases while the vehicle is stationary, thereby flowing the d-axis current for warming up.

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