Control device for an electric vehicle drive motor and vehicle with the same

Abstract

An electric drive motor control device (12) for a vehicle for performing vector control of an electric drive motor (10) for the vehicle, the control device (12) comprising: a controller that generates a motor drive signal of a vector control for the motor (10) in accordance with a required drive torque; and a rectifier (11) that controls an electric power supplied to the motor (10) from a battery (20) as an electric power source in accordance with the motor drive signal; wherein the controller is configured to judge whether the battery (20) needs to be warmed up according to an output of a battery temperature sensor (22) that measures a temperature of the battery (20), and when it is judged that the battery (20) needs to be warmed up, in a situation (i) in which the vehicle is stopped, set a q-axis current value for vector control of the motor (10) to zero, or when a brake is released from such a situation (i), set a q-axis current to a value corresponding to a drive torque required to perform a vehicle creep operation, and additionally set a d-axis current to a value required to perform a battery warm-up operation; the controller is further configured to, when the battery (20) needs to be warmed up in a situation (ii) in which the vehicle is traveling, set a q-axis current to a value corresponding to a drive torque required to perform a vehicle traveling operation and additionally set a d-axis current to a value for promoting the battery warming up operation with respect to the q-axis current value; wherein the controller in situations (i) and (ii) is configured to perform an adjustment such that the d-axis current value increases with a decrease in the battery temperature; and wherein the controller, when judging that the battery (20) needs to be warmed up, is configured to calculate a required heat amount required for battery warming up according to the output of the battery temperature sensor (22), calculate an estimated self-heating amount of the battery (20) according to an engine power input amount based on the required drive torque of the engine (10), and increase according to a difference between the required heat amount and the estimated self-heating amount when the required heat amount is greater than the estimated self-heating amount.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a control device for an electric vehicle drive motor and a vehicle having the same (e.g., an electric vehicle or a hybrid vehicle). More particularly, the present invention relates to a motor control device for controlling the electric power supplied from a battery to a vector-controlled drive motor. BACKGROUND OF THE INVENTION

[0002] It is conventionally known that a chargeable and dischargeable secondary battery (hereinafter referred to as the battery) is used as a motor power supply for an electric vehicle and a hybrid vehicle that uses an electric drive motor as a vehicle power source. A decrease in the temperature inside the battery deteriorates its charge / discharge characteristics. Therefore, it is preferable to warm up the battery when a vehicle is in a cold-start state, namely, when the vehicle is restarted after long hours of inactivity in a place where the outside temperature is low, such as in winter or cold climates.

[0003] As a prior art for battery heating, for example, in a hybrid vehicle having an internal combustion engine and an electric drive motor as vehicle drive sources, JP2001-197607A (Patent Document 1) discloses that, when the battery is required to be warmed up, battery warming is performed by supplying a motor drive current (a so-called d-axis current or magnetic flux component current) to the electric drive motor only in the d-axis by applying vector control of an electric drive motor control device. The d-axis current is a current flowing in a direction for strengthening a magnetic flux of a permanent magnet of a motor rotor. In other words, according to such a technique, the electric power of the battery is consumed without rotating the electric drive motor, and can thereby warm up the battery by allowing the battery to be discharged for heat generation.The prior art is applicable only to a hybrid vehicle that has both an electric drive motor and an internal combustion engine as the vehicle's power sources, and is capable of running on at least one of these two power sources. That is, in the prior art, the battery is warmed up by supplying the d-axis current for vector control through the electric drive motor, while the internal combustion engine is warmed up by its own power, thus simultaneously driving the vehicle with the internal combustion engine and warming up the battery.

[0004] Furthermore, US 7,629,755 B2 is further known as prior art, which discloses a secondary battery device and method. In particular, when it is determined that the battery temperature is below a predetermined threshold, said device and method utilize an inverter control circuit that alternately switches the operating point of an AC motor between an optimal operating point and a point with increased motor loss. At the point with increased motor loss, the amplitude of the motor current increases, thereby increasing the copper loss in the three-phase coil of the AC motor. At the optimal operating point, however, this loss decreases, thus generating cyclic charging and discharging of the battery.

[0005] Further relevant information can also be found in Dirk Schröder's "Electric Drives - Control of Drive Systems," 4th edition (2015), pp. 1100-1113, which addresses specific aspects of the control of electric drive systems.

[0006] Meanwhile, the battery warm-up operation (cold start operation) described in Patent Document 1 is not applicable to so-called electric vehicles that use only an electric drive motor as the vehicle drive source. This is because Patent Document 1 relies on using both the engine operation alone and the battery warm-up operation by supplying the d-axis current to the electric drive motor during a cold start of the vehicle. Specifically, when the technology of Patent Document 1 is adopted for the electric vehicle, since only the d-axis current for vector control is supplied by the electric drive motor during a cold start (in a situation where battery warm-up is required), it becomes difficult to perform both the vehicle drive mode and the battery warm-up mode using the electric motor at the same time.Indeed, when the technology of Patent Document 1 is adopted for the electric vehicle, the battery warm-up technology is applicable in a situation where the vehicle is stopped, but in a drive mode (a mode where the required drive torque for the motor is generated by an accelerator pedal), it is difficult to achieve a situation where only the d-axis current is used for the battery warm-up process during a vehicle cold start because a q-axis current (torque component current) is required. On the other hand, in the hybrid vehicle, the vehicle is driven exclusively by the internal combustion engine during the battery warm-up process, while only the d-axis current is supplied to the electric drive motor (the q-axis current is zero, so the drive motor does not rotate).As a result, the hybrid vehicle does not fully utilize its capabilities from the standpoint of environmental considerations, such as reducing emissions.

[0007] The present invention was conceived in view of the above circumstances, and its object is to provide a control device for an electric vehicle drive motor capable of addressing the above-described issues, thereby realizing acceleration of battery heating and taking environmental protection considerations into account, regardless of whether it is an electric vehicle or a hybrid vehicle. The present invention also aims to provide a vehicle having such a control device for an electric motor as a vehicle drive motor. SUMMARY OF THE INVENTION

[0008] To realize the above object, the present invention basically provides the following control device for an electric vehicle drive motor and a vehicle (e.g., electric vehicle or hybrid vehicle) having the control device. (1) The vehicle electric drive motor control device is used for vector control of a vehicle electric drive motor. The control device includes a controller that generates a vector control motor drive signal for the motor in accordance with a required drive torque, and a rectifier that controls electric power supplied to the motor from a battery as an electric power source in accordance with the motor drive signal.The controller is configured to judge whether the battery needs warming up according to an output of a battery temperature sensor that measures the temperature of the battery, and, when judging that the battery needs warming up, set a q-axis current value for vector control of the motor to zero in a situation (i) where the vehicle is stopped, or when a brake is released from such a situation (i), set a q-axis current to a value corresponding to a drive torque required to perform a vehicle creep operation, and additionally set a d-axis current to a value required to perform a battery warming up operation.On the other hand, when the battery needs to be warmed up in a situation (ii) where the vehicle is traveling, the controller is further configured to set a q-axis current to a value corresponding to a drive torque required to perform a vehicle traveling operation, and additionally set a d-axis current to a value for promoting the battery warm-up operation relative to the q-axis current value. In situations (i) and (ii), the controller performs an adjustment such that the d-axis current value increases with a decrease in the battery temperature. (2) If necessary, when the controller judges that the battery needs to be warmed up, it is preferable that the controller is configured to set such that the d-axis current value increases with a decrease in the battery temperature and decreases with an increase in the q-axis current value due to an increase in the required drive torque. (3) The q-axis current value and the d-axis current value are set to increase in accordance with a difference between a required heat amount and an estimated self-heating amount when the required heat amount is greater than the estimated self-heating amount. Here, the required heat amount required for battery warm-up is calculated by the controller according to the output of the battery temperature sensor, and the estimated self-heating amount of the battery is calculated by the controller according to an engine power input amount based on the required drive torque of the engine. (4) According to another aspect of the present invention, there is provided a vehicle including the control device described in (1) and (3) above.

[0009] According to yet another aspect of the present invention, the following vehicle is also provided. That is, a vehicle includes a vector-controlled electric drive motor for the vehicle, a battery as an electric power source for the drive motor, a controller that generates a motor drive signal required for vector control of the motor in accordance with a required drive torque for the vehicle, a rectifier that controls electric power supplied from the battery to the motor in accordance with the motor drive signal, a battery temperature sensor that measures the temperature of the battery, and a heat supply device that supplies heat generated at one or both of the drive motor and the rectifier to the battery.Furthermore, the controller is configured to set a q-axis current value and a d-axis current value for vector control according to the required drive torque of the motor. Still further, when judging from an output of the battery temperature sensor that the battery needs heating, the controller is configured to calculate a heat amount required for battery heating according to the output of the battery temperature sensor, calculate an estimated self-heating amount of the battery according to a motor power input amount based on the required drive torque of the motor, and calculate a heat supply amount indicating the amount of heat supplied to the battery by the heat supply device.Still further, when the required heat amount for warming up the battery is greater than a sum of the estimated self-heating amount and the heat supply amount, the controller is configured to correct to increase the d-axis current value for vector control according to a magnitude of a difference between the required heat amount and the sum of the estimated self-heating amount and the heat supply amount. Furthermore, when judging that the battery needs warming up, the controller is configured to increase the estimated self-heating amount of the battery according to a difference between the required heat amount and the estimated self-heating amount when the required heat amount is greater than the estimated self-heating amount.

[0010] According to the present invention, for example, in a case where the vehicle to be controlled is an electric vehicle and in a situation where battery warm-up is necessary for a cold start of the vehicle, the q-axis current value is set for vector control required for vehicle running (based on the required drive torque of the motor), while the d-axis current value is set to increase with a decrease in battery temperature. Therefore, battery warm-up can be accelerated regardless of whether the electric vehicle is stopped or running. On the other hand, when the present invention is applied to a hybrid vehicle, the vehicle can run by utilizing the electric drive motor instead of the internal combustion engine regardless of whether a battery warm-up mode is selected, allowing the battery warm-up described above.Thus, the present invention makes it possible to provide an engine control device and a vehicle that correctly take environmental protection considerations into account, regardless of whether an electric vehicle or a hybrid vehicle is to be controlled. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram illustrating an overall configuration of a vehicle according to a first embodiment of the present invention; Fig. 2 is an overall flowchart illustrating a battery warm-up process according to the first embodiment; Fig. 3 is a flowchart illustrating a current correction process for the battery warm-up process according to the first embodiment; Fig. 4 is a graph illustrating a d-axis current and a q-axis current for vector control set in a current correction process according to an embodiment of the present invention; Fig. 5 is a diagram illustrating a table derived from the one in Fig. 4 shown graphic; Fig. Fig. 6 is a diagram illustrating an overall configuration of a second embodiment of the present invention; and Fig. 7 is a flowchart illustrating a current correction process for the battery warm-up process according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] Embodiments of the present invention will now be described with reference to the accompanying drawings. First embodiment

[0012] Fig. 1 is a schematic diagram illustrating a vehicle having a motor control device according to a first embodiment of the present invention. As an example, an electric vehicle having an electric vehicle drive motor 10 as a drive source is shown in this schematic diagram.

[0013] The Fig. The vehicle according to the first embodiment shown in FIG. 1 includes three ECUs (electronic control units): a battery ECU 21, a motor ECU (engine control device) 12 for controlling the drive motor 10, and a vehicle ECU 30 for providing overall control of the vehicle. The battery ECU 21 calculates a state of charge (SOC) based on a voltage across a battery 20, which is to be a vehicle power source, a charge / discharge current, and an integrated charge / discharge current, and detects a battery temperature measured by a battery temperature sensor 22. Thereby, the battery ECU 21 manages the charge / discharge current and other characteristics of the battery 20. Furthermore, the battery ECU 21 outputs the SOC and other information about the battery 20 to another electronic control unit, such as the vehicle ECU 30, through a vehicle network 3.Furthermore, the battery ECU 21 outputs an actuation signal to a battery fan 23 in accordance with the temperature of the battery.

[0014] The vehicle ECU 30 generates an engine control signal (a drive torque command, i.e., a required drive torque) related to vehicle braking or vehicle propulsion based on information acquired by the vehicle network 3 and signals supplied from an outside air temperature sensor 40, an accelerator pedal sensor 13, a brake pedal sensor 14, and a wheel speed sensor 15 connected to the vehicle ECU 30. The engine control signal generated by the vehicle ECU 30 is output to the engine ECU 12 through the vehicle network 3.

[0015] According to a drive torque command from the vehicle ECU 30, the engine ECU 12 determines a voltage to be applied to the drive motor 10. For example, when a motor control signal generated as the drive torque command (the required drive torque) is input to the engine ECU 12, the engine ECU 12 calculates a q-axis current value for vector control of the motor according to the required drive torque and a d-axis current value based on necessity (the d-axis current value requested during a battery warm-up operation described later), and calculates a voltage to be applied to the drive motor 10 from the d-axis and q-axis currents. The engine ECU 12 outputs a pulse signal (PWM: Pulse Width Modulation signal, i.e., a motor drive signal) corresponding to the voltage to be applied to the drive motor 10 to a rectifier 11.Generally, a current controller (rotating frame), a rotating frame-to-rest frame converter, or the like is used to convert the d-axis and q-axis current values ​​into the pulse signals (PWM signals) to be applied to the rectifier. Explanation regarding such conversion will be omitted here, as it is a well-known technology.

[0016] According to the pulse width modulation signal (motor drive signal) input from the engine ECU 12, the rectifier 11 converts a direct current output from the battery 20 into a three-phase current output and supplies the three-phase current output to the drive motor 10. Specifically, the rectifier 11 controls the electric power supplied to the drive motor 10 from the battery 20 as a power source according to the motor drive signal. Thus, the drive motor 10 can generate a driving force (torque) required for vehicle propulsion. The driving force of the drive motor 10 is transmitted to the drive wheels 2 (2a, 2b) of the vehicle through a reduction gear 1, allowing the vehicle to travel.

[0017] Incidentally, regarding the temperature characteristics of a battery, it is well known that the electric power dissipated from the battery is extremely reduced when the battery temperature is not higher than 0°C, for example. Therefore, when the vehicle is restarted after a long period of rest in a place where the outside temperature is low, the driving performance may deteriorate due to a reduction in the electric power dissipated from the battery. To address such a problem, the engine ECU 12 includes a calculation unit that determines (corrects) the d-axis current value for vector control according to the output (battery temperature value) of the battery temperature sensor 22.

[0018] Fig. 2 and Fig. 3 are flowcharts illustrating a calculation processing procedure of the current control for the drive motor 10, wherein Fig. 2 is a flowchart illustrating an overview of the computation processing procedure, and Fig. 3 is a flowchart illustrating a part of the arithmetic processing operation, ie, a motor current adjustment (current correction) operation, which is performed when battery warm-up is required.

[0019] It will be Fig. 2. First, the vehicle ECU 30 performs analog-to-digital conversion of an output signal from each sensor and acquires information through the vehicle network at step S101. Next, at step S102, the vehicle ECU 30 calculates a torque command (required torque) to be output from the drive motor 10 according to a value measured by the accelerator pedal sensor 13 and the information acquired through the vehicle network. At step S103, the engine ECU 12 receives the required drive torque (drive torque command) from the vehicle ECU 30 and calculates the q-axis current value and the d-axis current value for vector control of the drive motor 10. Since a torque current component is formed by the q-axis current, the d-axis current value (magnetic flux component) to be calculated may be zero depending on the operating conditions.Next, at step S104, the vehicle ECU 30 or the engine ECU 12 judges whether the battery needs to be warmed up. For example, if the battery temperature detected at step S101 is not higher than a predetermined value, at step S104 it is judged that battery warming up is necessary, so the processing proceeds to step S200. On the other hand, if the judgment result obtained at step S104 indicates that battery warming up is not necessary, the processing proceeds to step S105. At step S105, the drive motor 10 is subjected to current control according to the d-axis and q-axis current values ​​previously calculated when battery warming up is not necessary. Upon completion of step S105, the processing ends.

[0020] When the processing proceeds to step S200 after it is judged at step S104 that battery warm-up is necessary, the steps shown in the flowchart of the Fig. 3 are performed sequentially to correct the d-axis and q-axis current values ​​or at least the d-axis current value set by the engine ECU 12 in step S103.

[0021] It will be Fig. 3. At step S201, the engine ECU 12 calculates a heat quantity (a required heat generation amount) Wr necessary for battery warm-up according to a current battery temperature. The required heat generation amount Wr is determined by equation (1) or equation (2). Wr=K1(Tt−Tb) Wr=K1(Tt−Tb)+K2(Tt−T0) where T b stands for the battery temperature, Tt stands for a battery target temperature, T0 stands for an outside air temperature and K1 and K2 are factors.

[0022] Next, at step S202, the motor ETC 12 calculates an estimated self-heating amount We of the battery under the condition that the drive motor is driven using the d-axis and q-axis currents set at step S103. In other words, the estimated self-heating amount of the battery is calculated according to a motor power input amount based on the required drive torque of the drive motor. Since a battery has an internal resistance Ri, when a current Ia is output from the battery, a loss due to the internal resistance generally turns out to be heat, and the temperature of the battery rises due to its self-heating. Therefore, the self-heating amount is determined by equation (3) based on Joule's law. In equation (3), t represents time. We=Ia2Rit

[0023] Next, at step S203, the engine ECU 12 compares the estimated self-heating amount W and the required heat generation amount Wr calculated in steps S201 and S202. If the self-heating amount We is equal to or greater than the required heat generation amount Wr (Wr≤We), at step S203, it is judged that battery warm-up is not necessary, so such operations end and restart. In this example, the current control at step S105 is executed using the d-axis and q-axis currents determined at step S103 and is not subjected to battery warm-up correction.

[0024] In contrast, at step S203, when it is judged that battery warm-up is necessary (Wr>We), the processing proceeds to step S204.

[0025] At step S204, the engine ECU 12 calculates a difference W (= Wr - We) between the required heat generation amount and the estimated self-heating amount, and then, at step S205, a target total current Ia to be output from the battery is calculated according to the difference W. The target total current Ia is a value determined by equation (4) taking into account the required drive torque of the drive motor and battery warm-up. Ia=K3(Wr−We) where K3 is a factor.

[0026] According to the relationship between the d-axis current id and the q-axis current iq used for vector control, the target total current la is given by Ia 2 = id 2 + IQ 2 Details are given later with reference to Fig. 4. In step S206, the d-axis current value (i d) is set from the target total current la using, for example, equation (5). Upon completion of step S206, the process ends. id=Ia2−iq2

[0027] The above d-axis current value is one which is determined when subjected to battery warm-up correction.

[0028] Fig. Figure 4 schematically shows the d-axis and q-axis current values ​​for the required drive with respect to the target total current la, which is set according to the battery temperature.

[0029] It will be Fig. 4. The vertical axis represents the target total current la, which is set depending on the battery temperature T, and the horizontal axis represents the required drive torque D of the drive motor. The battery temperature T can be determined by taking the outside temperature into consideration. A symbol id represents d-axis current characteristics, which are performed when motor current control (vector control) according to the present embodiment is performed, whereas the symbol iq represents q-axis current characteristics. The relationship expression indicating the relationship between the battery temperatures T1, T2, and T2 indicated along the vertical axis is T1 > T2 > T3. The relationship expression indicating the relationship between the total currents la1, la2, and la3 determined at the battery temperatures T1, T2, and T2, respectively, is la1 < la2 < la3 during a battery warm-up operation.The battery temperature T at which battery warm-up is required is set so that the target total current la increases with a decrease in the battery temperature. The q-axis current value iq has linear characteristics (iq = KqD, where Kq is a factor) and changes according to the required drive torque D. On the other hand, the d-axis current value id decreases with an increase in the required drive torque D (q-axis current value iq), as shown by a curve (id = √(Ia). 2 - (KqD) 2 )) due to the relationship between the target total current la and the required drive torque D (q-axis current value iq) gradually decreases (Ia 2 = iq 2 + id 2). The required driving torques D1, D2, and D3 (D1 < D2 < D3) indicated along the horizontal axis are required driving torques that implement the battery warm-up process by using only the q-axis current value itself at the battery temperatures T1, T2, and T3.

[0030] For example, when the battery temperature is T1, the target total current is set to la1. In this example, the q-axis current iq is set according to the required driving torque D. Then, the d-axis current id1 is set with respect to the q-axis current iq. In this example, when the required driving torque is zero (the vehicle is stopped), the q-axis current value iq is zero, and the d-axis current id1 is set to a target total current la1 (id1 = la1). When the required driving torque D is greater than zero and less than the required driving torque D1, equation (5) is used to determine the d-axis current id1 from the target total current la1 and the q-axis current iq. When the battery temperature is lower than T1, for example, equal to T2 or T3, the target total current is set to la2 or la3 (la1 < la2 < la3).In this example, a correction is made so that the d-axis current increases with a decrease in battery temperature, even if the required drive torque D (q-axis current value) remains unchanged. Furthermore, as the battery temperature T gradually increases during the battery warm-up process, a used d-axis current value characteristic curve id changes to a corresponding curve. For example, when the battery temperature increases from T3 to T2, the d-axis current value characteristic curve changes from id3 to id2.

[0031] That is, in the present embodiment, the engine ECU 12 as a controller judges whether battery warm-up is required. If the battery needs warming up in the situation (i) where the vehicle is stopped, the engine ECU 12 sets the q-axis current value iq to zero and sets a d-axis current value that permits the battery warm-up operation. On the other hand, if the battery needs warming up in the situation (ii) where the vehicle is running, the engine ECU 12 sets the q-axis current value iq according to the drive torque D required for vehicle running and sets a d-axis current value id that promotes the battery warm-up operation with respect to the q-axis current value iq. In situations (i) and (ii), the engine ECU 12 performs adjustment so that the d-axis current value included in the target total current la increases with a decrease in the battery temperature.Furthermore, the engine ECU 12 performs adjustment so that the d-axis current value decreases with an increase in the q-axis current value due to an increase in the required drive torque.

[0032] Since, as described above, the d-axis current and q-axis current are adjusted according to the required drive torque D of the drive motor and the temperature of the battery 20, the d-axis current value for the vector control of the drive motor for battery warm-up can be corrected regardless of whether the vehicle is stopped or running.

[0033] As a result, battery warm-up can be accelerated regardless of whether an electric vehicle is stopped or moving.

[0034] Furthermore, in the present embodiment, the engine ECU 12 increases or decreases the d-axis current for vector control for correction purposes according to the amount of heat required for battery warm-up, which is determined from the battery temperature, and the amount of self-heating of the battery, which is determined from the power input amount for motor drive (mainly the q-axis current for vector control). This makes it possible to provide a motor control device that allows the vehicle to drive while performing battery warm-up with high correction accuracy of the d-axis current and shortens the length of the battery warm-up time while taking energy efficiency into account.

[0035] Furthermore, the d-axis current does not flow when a required amount of heat generation can be covered by the q-axis current alone, which is primarily related to the driving force. This makes it possible to reduce unnecessary energy consumption.

[0036] In the present embodiment, although equations (4) and (5) are used to set the target total current and d-axis current for vector control, alternatively, the target total current and d-axis current for vector control can also be obtained by tabulating the graph of Fig. 4, ie, by preparing a table showing q-axis and d-axis current value settings in relation to the required drive torque and battery temperature, as shown in Fig. 5. In this case, an interpolation method based on an iq linear function and an id curve function can be additionally used if necessary.

[0037] The present embodiment has been described assuming that the present invention is applied to an electric vehicle. However, the motor current control (d-axis current / q-axis current control) during battery warm-up can also be applied to a motor control device for a hybrid vehicle. In a hybrid vehicle described in Patent Document 1, the current control for battery warm-up was previously performed using the d-axis current alone while the engine was operating. On the other hand, since according to the present embodiment, a hybrid vehicle motor is controlled during a battery warm-up operation by adopting the configuration, flowcharts, and table shown in the Fig. 1 to 5 are used as needed without the internal combustion engine operation, it is possible to provide a vehicle capable of performing the battery warm-up operation regardless of whether it is stopped or running, while emitting no exhaust gas during a battery warm-up operation.

[0038] It should be noted that the following embodiments can also be applied to both electric vehicles and hybrid vehicles. Second embodiment

[0039] Fig. Figure 6 is a schematic diagram illustrating a vehicle with the motor control device according to a second embodiment of the present invention. The second embodiment achieves battery warm-up by utilizing not only the heat dissipated from the battery's self-heating based on the d-axis and q-axis currents, but also the heat generated by the drive motor and rectifier.

[0040] In the Fig. 6, the elements designated by the same reference numerals as those in Fig. 1 have the same functions as those in Fig. 1 and will not be described redundantly. In the second embodiment, the Fig. 1 includes the battery ECU 21, the engine ECU 12, and the vehicle ECU 30, which are the same as the corresponding elements used in the first embodiment.

[0041] The present embodiment heats the battery 20 not only by using the heat derived from the self-heating of the battery based on the d-axis and q-axis currents as in the first embodiment, but also by transferring the heat generated by the drive motor 10 and rectifier 11 to the battery 20 through cooling water and air.

[0042] Therefore, the vehicle according to the present embodiment includes a cooling water circuit (cooling system) for cooling the drive motor 10 and rectifier 11 in addition to the cooling water circuits shown in Fig. 1 shown elements. In Fig. 6 the cooling water circuit is indicated by a dashed line.

[0043] The cooling water circuit is a closed circuit in which cooling water is circulated by a water pump 60. Specifically, the water pump 60 feeds circulating cooling water into water jackets in the rectifier 11 and the drive motor 10. The cooling water supplied to the drive motor 10 passes through cooling water paths 101, 102 and flows into a radiator 61. The radiator 61 is a heat exchanger that cools high-temperature cooling water. The cooling water flowing into the radiator 61 is cooled by exchanging heat with the outside air. The cooling water flowing out of the radiator 61 flows into a cooling water path 103.

[0044] A thermostat 62 is capable of switching from one flow path to another depending on the cooling water temperature. When the cooling water temperature is low, the thermostat 62 closes a radiator-side cooling water path to connect the cooling water path 101 with the cooling water path 103. This ensures that no heat exchange occurs in the radiator 61. Therefore, when battery warm-up is required, the cooling water temperature can be increased immediately.

[0045] The cooling water flowing in the cooling water path 103 passes through a cooling water path 104 and then returns to the water pump 60 through a heater core 64.

[0046] The heater core 64 is a heat exchanger similar to the one included in the radiator 61. A fan blower 67 supplies air so that the heat of the cooling water is transferred through the air into the vehicle interior and used as a heat source to warm the vehicle interior.

[0047] A flow path switching valve 66 switches between the cooling water path 104 and a cooling water path 105 in accordance with a signal from a temperature control unit 50. Therefore, when the vehicle interior needs to be warmed up while the cooling water temperature is low, the flow path switching valve 66 closes the cooling water path to the heater core 64 to increase the cooling water temperature and prevent cold air from being unnecessarily supplied to the vehicle interior.

[0048] The heater core 64 is placed in a vehicle air conditioner, which is placed in the vehicle interior and is not shown in the figure, and is arranged downstream of an evaporator 65 with respect to the flow of air supplied from the fan blower 67.

[0049] The temperature control unit 50 is an electronic control unit that provides temperature control of the cooling water and the vehicle interior. The temperature control unit 50 receives a signal from a cooling water temperature sensor 42, which measures the temperature of the cooling water, and a signal from a vehicle interior temperature sensor 41, which measures the temperature of the vehicle interior. Furthermore, the temperature control unit 50 outputs actuation signals to the water pump 60, the flow path switching valve 66, and the fan blower 67 for the purpose of controlling the cooling water temperature in accordance with temperature signals, such as the cooling water temperature, vehicle interior temperature, and outside temperature signals, and a signal supplied from the vehicle ECU 30.

[0050] The battery fan blower 23 can transfer the heat of the cooling water through the air to the battery 20.

[0051] In the present embodiment, vector control of the drive motor 10 is also basically carried out as shown in the flowcharts of Fig. 3 and Fig. 4. However, the vector control provided by the present embodiment is somewhat different from the vector control provided by the first embodiment. In step S202 for current correction processing shown in the flowchart of Fig. 3, the first embodiment determines the estimated heat generation amount We from the self-heating amount of the battery. On the other hand, the present embodiment considers the heat generated by the drive motor 10 and rectifier 11 in addition to the estimated heat generation amount We based on the self-heating amount of the battery, and corrects the d-axis current value by performing processing as shown in the flowchart of FIG. Fig. 3, although the configuration used is specific to the present embodiment.

[0052] Specifically, when it is judged that battery warm-up is necessary as in the first embodiment, the present embodiment calculates the heat amount Wr required for battery warm-up according to the output of the battery temperature sensor 22, calculates the estimated self-heating amount We of the battery according to the motor power input amount based on the required drive torque of the drive motor, and calculates the amount Wh of heat to be supplied to the battery 20 by a heat supply device (drive motor and rectifier cooling water system).

[0053] When the required heat amount Wr is larger than the sum of the estimated self-heating amount We and the heat supply amount Wh, the present embodiment increases the d-axis current value for the vector control for correction purposes in accordance with a difference between the required heat amount Wr and the sum of the estimated self-heating amount We and the heat supply amount Wh.

[0054] The second embodiment is configured so that the heat generated by the battery's self-heating and the heat generated by the drive motor 10 and rectifier 11 can both be used as heat sources for battery warming. This makes it possible to provide improved battery warming capability. Furthermore, the amount of power consumption can be reduced by using the d-axis current by utilizing the heat of the cooling water. Furthermore, when the heat generated by the drive motor and rectifier is recovered and used for battery warming, the battery warming operation can be performed with increased efficiency because the d-axis current is controlled according to the amount of heat generated by the drive motor and rectifier.

[0055] Specifically, the drive motor determines whether or not to perform the battery warm-up process using the d-axis current based on the amount of heat remaining in an exhaust heat recovery unit (cooling water system) of the rectifier. This makes it possible to reduce unnecessary energy consumption, for example, during restarting. Third embodiment

[0056] Fig. 7 is a flowchart illustrating motor current control performed during a battery warm-up operation for a vehicle applied to a third embodiment of the present invention.

[0057] The vehicle according to the third embodiment has the same configuration as the vehicle according to the first embodiment. Like the first embodiment, the third embodiment performs d-axis current control and q-axis current control during a battery warm-up operation according to the battery temperature and the required drive torque signal. However, the third embodiment differs from the first embodiment in that, while the vehicle is stopped, the engine ECU 12 performs a battery warm-up operation using the d-axis current without decreasing the q-axis current to zero to adjust the q-axis current value according to a drive torque, allowing the vehicle to creep under the assumption that the brake is released.

[0058] The above-mentioned engine control will now be described with reference to the flow chart of the Fig. 7. In the flowchart of the Fig. 7 are steps that have the same number of steps as in the flow chart of the Fig. 3 are not described redundantly, as they refer to a process in which the same function is performed as in the flowchart of the Fig. 3.

[0059] As for a conventional hybrid vehicle or electric vehicle, when the vehicle is stopped and the brake pedal is depressed, its engine and drive motor are set to stop to reduce energy consumption. In contrast, when both the accelerator pedal and brake pedal are released, a predetermined driving force (required driving torque) is generated to make the vehicle creep. In other words, when the brake pedal is depressed while the vehicle is stopped, the electric power consumption of the drive motor 10 and rectifier 11 is reduced, and as a result, the amount of heat generated by the self-heating of the battery 20 decreases.

[0060] Meanwhile, according to the present embodiment, as shown in the flowchart of Fig. 7, when the battery warm-up is required and the calculation process of the target total current has been carried out in a not-yet-warm-up state at steps S201 to S205, a step S207 is then carried out to determine, in accordance with a signal of the brake pedal sensor 14 (see Fig. 1) to judge whether the brake pedal is depressed while the vehicle is stopped. The vehicle ECU 30 takes information about a vehicle stop state from both the information indicating that the depression amount of the Fig. 1 is zero, as well as the information indicating that the speed is zero, which is generated by the wheel speed sensor 15. If the judgment result obtained in step S207 does not indicate that the brake pedal is depressed while the vehicle is stopped, only the d-axis current is corrected, as in the case of the Fig.3 is the case, and then the process ends. On the other hand, the judgment result obtained in step S207 indicates that the brake pedal is depressed while the vehicle is stopped, and the relevant information is transmitted to the engine ECU 12. The engine ECU 12 then sets a q-axis current corresponding to the drive torque for creeping, corrects the d-axis current value in step S206 according to equation (5), and ends the process.

[0061] As described above, when the brake is depressed by the vehicle driver while the vehicle is stopped, the engine ECU 12 sets a q-axis current that outputs drive torque to make the vehicle creep when the brake is released, and allows the d-axis current to flow to promote the battery warm-up process. This makes it possible to warm up the battery 20 immediately. The present embodiment also provides the following advantages.

[0062] At low temperatures where battery warm-up is required, the battery's discharge power is not fully delivered, and the battery's instantaneous power (the amount of current that can be drawn instantly) is weaker than that at a suitable temperature. Therefore, for example, when the brake is depressed to stop the vehicle and then the brakes are released to depress the accelerator pedal to accelerate, it takes a certain amount of time to draw the necessary amount of current, which may result in a sluggish acceleration feeling.Therefore, in order to address such a problem, the present embodiment previously generates a predetermined driving force (the driving torque required to allow the vehicle to creep) while the vehicle is stopped while the brake is depressed in a situation where battery warm-up is required, and when the brake is released to depress the accelerator pedal, it is possible to avoid a sluggish acceleration feeling and to promptly complete battery warm-up.

[0063] In the embodiments described above, the d-axis and q-axis current values ​​to be adjusted by a current correction unit are calculated according to the self-heating amount of the battery 20 and the amount of heat required for battery warm-up. However, from the standpoint of vehicle protection and device protection, corrections may be made according to, for example, the state of charge (SOC) and state of health (SOH) of the battery. Furthermore, if an excessive amount of current is drawn for self-heating of the battery, the battery may deteriorate. Therefore, the amount of current to be drawn may be limited to avoid such a problem.

Claims

[1] An electric drive motor control device (12) for a vehicle for performing vector control of an electric drive motor (10) for the vehicle, the control device (12) comprising: a controller that generates a motor drive signal of a vector control for the motor (10) in accordance with a required drive torque; and a rectifier (11) that controls an electric power supplied to the motor (10) from a battery (20) as an electric power source in accordance with the motor drive signal; wherein the controller is configured to judge whether the battery (20) needs to be warmed up according to an output of a battery temperature sensor (22) that measures a temperature of the battery (20), and when it is judged that the battery (20) needs to be warmed up, in a situation (i) in which the vehicle is stopped, set a q-axis current value for vector control of the motor (10) to zero, or when a brake is released from such a situation (i), set a q-axis current to a value corresponding to a drive torque required to perform a vehicle creep operation, and additionally set a d-axis current to a value required to perform a battery warm-up operation; the controller is further configured to, when the battery (20) needs to be warmed up in a situation (ii) in which the vehicle is traveling, set a q-axis current to a value corresponding to a drive torque required to perform a vehicle traveling operation, and additionally set a d-axis current to a value for promoting the battery warming up operation with respect to the q-axis current value; wherein the controller in situations (i) and (ii) is configured to perform an adjustment such that the d-axis current value increases with a decrease in the battery temperature; and wherein the controller, when judging that the battery (20) needs to be warmed up, is configured to calculate a required heat amount required for battery warming up according to the output of the battery temperature sensor (22), calculate an estimated self-heating amount of the battery (20) according to an engine power input amount based on the required drive torque of the engine (10), and increase according to a difference between the required heat amount and the estimated self-heating amount when the required heat amount is greater than the estimated self-heating amount. [2] The control device (12) according to claim 1, wherein the controller, when judging that the battery (20) needs to be warmed up, is configured to make an adjustment such that the d-axis current value increases with a decrease in the battery temperature and decreases with an increase in the q-axis current value due to an increase in the required drive torque. [3] The control device (12) according to claim 1, wherein the q-axis current value and the d-axis current value are preset in a table in accordance with the required drive torque and the battery temperature. [4] Vehicle with a vector-controlled electric drive motor (10); a battery (20) serving as an electrical power source for the drive motor (10); a battery temperature sensor (22) that measures the temperature of the battery (20); and the electric drive motor control device (12) for the vehicle according to claim 1. [5] Vehicle with a vector-controlled electric drive motor (10) for the vehicle; a battery (20) as an electrical power source for the drive motor (10); a controller that generates a motor drive signal required for vector control of the motor (10) in accordance with a required drive torque for the vehicle; a rectifier (11) that controls electrical power supplied to the motor (10) from the battery (20) in accordance with the motor drive signal; a battery temperature sensor (22) that measures the temperature of the battery (20); and a heat supply device that supplies heat generated at one or both of the drive motor (10) and rectifier (11) to the battery (20); wherein the controller is configured to set a q-axis current value and a d-axis current value for the vector control in accordance with the required drive torque of the motor (10), and when it judges from an output of the battery temperature sensor (22) that the battery (20) needs to be warmed up, calculate a heat amount required for battery warming in accordance with the output of the battery temperature sensor (22), calculate an estimated self-heating amount of the battery (20) in accordance with a motor power input amount based on the required drive torque of the motor (10), and calculate a heat supply amount indicating the amount of heat supplied to the battery (20) by the heat supply device, the controller is further configured, when the required heat amount for warming up the battery (20) is greater than a sum of the estimated self-heating amount and the heat supply amount, to correct to increase the d-axis current value for vector control in accordance with a magnitude of a difference between the required heat amount and the sum of the estimated self-heating amount and the heat supply amount; and the controller, when judging that the battery (20) needs to be warmed up, is configured to increase the estimated self-heating amount of the battery (20) in accordance with a difference between the required heat amount and the estimated self-heating amount when the required heat amount is greater than the estimated self-heating amount. [6] The vehicle according to claim 5, wherein the vehicle is an electric vehicle, and the controller is configured to receive braking information and stopping information related to the electric vehicle to be controlled, judge whether the vehicle is in a brake-on stop state, and when it is judged that the vehicle is stopped with the brake on, not only set a q-axis current value corresponding to a drive torque to allow the vehicle to creep under the assumption that the brake is released while the battery (20) requires warming up, but also correct the d-axis current value. [7] The vehicle according to claim 6, wherein the controller is further configured, when the temperature of the heat supply device is equal to or greater than a predetermined value, not to correct the d-axis current value.

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