Battery heating device

Abstract

The present invention provides a battery heating device that enables motor heating while parked, even when the drive system that transmits the driving force of the electric motor to the wheels does not have a parking brake or the like, without the need to add a parking brake or the like. [Solution] When predetermined heat generation start conditions are met, the EV-CU60 drives the electric brake booster 51 and supplies power to the front motor generator 21. After a predetermined time has elapsed, it stops driving the electric brake booster 51 and performs a heat generation feasibility determination process to determine whether the front motor generator 21 rotated while the electric brake booster 51 was driving and after it stopped. If the front motor generator 21 does not rotate, the power supplied to the front motor generator 21 is increased and the heat generation feasibility determination process is repeated. When the power supplied to the front motor generator 21 reaches the target power, that state is maintained.

Description

Technical Field

[0001] The present invention relates to a battery warming device.

Background Art

[0002] In recent years, battery electric vehicles (BEVs) that use an electric motor as a drive power source and do not emit exhaust gas have been put into practical use. In such electric vehicles, a high-voltage battery (hereinafter also simply referred to as "battery") for supplying power to the electric motor (or receiving and storing regenerated power) is mounted.

[0003] By the way, the battery has a tendency that the internal resistance increases and the charge-discharge characteristics deteriorate as the temperature becomes lower. Therefore, for example, when the outside air temperature is low and the battery is cold, the charging time becomes longer. Also, high output cannot be achieved. Therefore, electric vehicles are known to have a so-called motor heat generation function that supplies power (energizes) to the electric motor when the vehicle is stopped (parked) and warms (raises the temperature) the battery by using the heat generated by the electric motor.

[0004] Here, for example, Patent Document 1 describes a technique for preventing the vehicle from moving by suppressing the occurrence of an unintended large torque due to a sudden large current flowing through the rotating electric machine when performing warming control (motor heat generation) when the vehicle is stopped, so that the torque of the rotating electric machine exceeds the parking brake holding torque.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, according to the technology described in Patent Document 1, it is possible to suppress the movement of the vehicle due to the torque of the rotating electric motor exceeding the parking brake holding torque during temperature rise control (motor heat generation) while the vehicle is stopped. However, in vehicles where the drive system that transmits the driving force of the electric motor to the wheels is not equipped with a parking gear or parking brake, attempting to perform motor heat generation while the vehicle is stopped (parked) using that electric motor may cause the wheels to rotate (or spin freely). On the other hand, adding a dedicated parking gear or parking brake would increase costs and weight. Furthermore, since the electric brake booster cannot be driven continuously for a long period of time due to thermal stress, it is not possible to continuously drive the electric brake booster while the motor is being heated.

[0007] The present invention was made to solve the above problems, and aims to provide a battery heating device that can generate motor heat when the vehicle is stopped (parked), without adding a dedicated parking gear or parking brake, even when the drive system that transmits the driving force of the electric motor to the wheels does not have a parking gear or parking brake. [Means for solving the problem]

[0008] A battery heating device according to one aspect of the present invention includes an electric motor that drives the wheels via a drive system without a parking gear and a parking brake, an electric brake booster that generates brake hydraulic pressure using the drive motor, a hydraulic brake that brakes the wheels using the brake hydraulic pressure, a battery that supplies power to the electric motor, a heat exchanger that performs heat exchange between the electric motor and the battery, a rotation detection means for detecting the rotation of the electric motor, a temperature detection means for detecting the temperature of the battery, and a control unit that controls the electric motor and the electric brake booster, wherein the control unit is in operation when the vehicle is parked and the battery temperature reaches a predetermined temperature. When predetermined heat generation initiation conditions, including the condition that the temperature is below a certain degree Celsius, are met, the electric brake booster is driven while power is supplied to the electric motor, the drive of the electric brake booster is stopped after a predetermined time has elapsed, a heat generation feasibility determination process is performed to determine whether the electric motor rotated while the electric brake booster was being driven and after it was stopped, if the electric motor does not rotate, the power supplied to the electric motor is increased and the heat generation feasibility determination process is repeated, and when the power supplied to the electric motor reaches the target power, the drive of the electric brake booster is stopped and a heat generation process is performed that maintains the state of supplying the target power to the electric motor.

[0009] According to one aspect of the present invention, when the electric motor does not rotate (i.e., the wheels do not rotate) during operation of the electric brake booster and after operation stops, the power supplied to the electric motor is increased, and when the power supplied to the electric motor without the electric motor rotating (i.e., the wheels do not rotate) reaches a predetermined target power, that state is maintained (heat generation treatment is performed). Therefore, motor heat generation can be performed after confirming that the electric motor (wheels) do not rotate. [Effects of the Invention]

[0010] According to the present invention, even if the drive system that transmits the driving force of the electric motor to the wheels is not equipped with a parking gear or parking brake, it is possible to perform motor heating when the vehicle is stopped (parked) without adding a dedicated parking gear or parking brake. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing a battery heating device according to an embodiment, and the configuration of an electric all-wheel drive vehicle to which the battery heating device is applied. [Figure 2] This figure shows the configuration of the heat exchange system that constitutes the battery heating device according to the embodiment. [Figure 3] This flowchart shows the processing procedure for motor heat generation treatment (heat generation feasibility determination process and heat generation treatment) using a battery heating device according to the embodiment. [Figure 4] This is a timing chart showing the changes in the heat generation command flag, electric oil pump flow rate, motor command current, brake command, and battery temperature during the execution of the motor heat generation process (heat generation feasibility determination process and heat generation process) by the battery heating device according to the embodiment. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts will be given the same reference numerals. Also, in each drawing, the same elements will be given the same reference numerals, and redundant explanations will be omitted. In this embodiment, the case in which the invention is applied to an electric all-wheel drive vehicle (AWD BEV) will be described as an example.

[0013] First, the configuration of the battery heating device (motor heat generation system) 3 according to the embodiment will be described using Figures 1 and 2 together. Figure 1 is a block diagram showing the configuration of the battery heating device 3 and the electric all-wheel drive vehicle 1 (hereinafter also simply referred to as "vehicle 1") to which the battery heating device 3 is applied. Figure 2 is a diagram showing the configuration of the heat exchange system 80 that constitutes the battery heating device 3.

[0014] The front motor generator (FMG) 21 (corresponding to the first electric motor described in the claims) is connected to the left and right front wheels 10FL and 10FR via a drive system 13F having, for example, a reduction gear (or transmission), a front differential (not shown), and left and right drive shafts 45L and 45R, so as to be able to transmit torque. Therefore, the torque output from the front motor generator 21 is converted by the reduction gear and then transmitted to the left and right front wheels 10FL and 10FR via the front differential and left and right drive shafts 45L and 45R. In other words, the front motor generator 21 is connected to the front wheels 10FL and 10FR and drives the front wheels 10FL and 10FR.

[0015] Similarly, the rear motor generator (RMG) 22 (corresponding to the second electric motor described in the claims) is connected to the left and right rear wheels 10RL and 10RR via a drive system 13R having, for example, a reduction gear (or transmission), a rear differential (not shown), and left and right drive shafts 48L and 48R, so as to be able to transmit torque. Therefore, the torque output from the rear motor generator 22 is converted by the reduction gear and then transmitted to the left and right rear wheels 10RL and 10RR via the rear differential and left and right drive shafts 48L and 48R. In other words, the rear motor generator 22 is connected to the rear wheels 10RL and 10RR and drives the rear wheels 10RL and 10RR.

[0016] The drivetrain 13R, which transmits the driving force of the rear motor generator 22 to the rear wheels 10RL and 10RR, is equipped with a parking gear 14 and an electric parking brake 17. More specifically, for example, the parking gear 14 is fitted to the output shaft of the reduction gear. Then, for example, when the parking (P) range is selected, the parking pawl engages with the parking gear 14, locking the parking gear 14 so that the rear wheels 10RL and 10RR do not rotate.

[0017] The electric parking brake (EPB) 17, for example, has an electric actuator, and when predetermined operating conditions, including driver operation (such as turning on the electric parking brake switch), are met, the electric actuator is driven to brake the rear wheels 10RL and 10RR of the vehicle 1, and the vehicle 1 is held in a stopped state. In this embodiment, an inner drum type (drum-in-disc) with a small drum brake for parking brake built into the hub is used as the electric parking brake 17, but other types may be used. It is preferable that the EV-CU60, described later, automatically turns on the electric parking brake 17 and locks the parking gear 14 (parking mechanism) when the motor heat generation is performed.

[0018] On the other hand, the drivetrain 13F, which transmits the driving force of the front motor generator 21 to the front wheels 10FL and 10FR, is not equipped with a parking gear (parking mechanism) or an electric parking brake.

[0019] The front motor generator 21 and the rear motor generator 22 are configured as synchronous generator motors (three-phase AC type synchronous motors) that have functions as synchronous motors that convert supplied electric power (three-phase alternating current) into mechanical power and as generators that convert input mechanical power into electric power. That is, each of the front motor generator 21 and the rear motor generator 22 operates as a synchronous motor that generates driving torque during vehicle driving and operates as a generator during regeneration. Each of the front motor generator 21 and the rear motor generator 22 is controlled by an EV-CU 60 described later.

[0020] The front motor generator 21 is connected to the battery 72 via the front inverter 71F, and the rear motor generator 22 is connected to the battery 72 via the rear inverter 71R. Note that the front inverter 71F may be integrated with, for example, the front motor generator 21, a speed reducer, a front differential, etc. Similarly, the rear inverter 71R may be integrated with the rear motor generator 22, a speed reducer, a front differential, etc.

[0021] When the front motor generator 21 and the rear motor generator 22 function as motors, the front inverter 71F and the rear inverter 71R (hereinafter sometimes referred to as the inverter 71 together) convert the DC power (current) supplied from the battery 72 into AC power (current) and drive the front motor generator 21 and the rear motor generator 22. Also, when the front motor generator 21 and the rear motor generator 22 function as generators, the front inverter 71F and the rear inverter 71R convert the AC power generated by the front motor generator 21 and the rear motor generator 22 into DC power and charge the battery 72.

[0022] That is, the battery 72 supplies power to the front motor generator 21 and the rear motor generator 22 which are the driving power sources of the vehicle 1, or receives and stores the regenerated electric power. As the battery 72, for example, a lithium-ion battery or the like is preferably used.

[0023] A temperature sensor 64 (corresponding to the temperature detection means described in the claims) for detecting the temperature of the battery 72 is attached to the battery 72. The temperature sensor 64 is connected to an EV-CU 60 described later, and an electric signal (voltage value) corresponding to the battery temperature is read by the EV-CU 60. As the temperature sensor 64, for example, a thermistor or the like whose resistance value changes with temperature is preferably used.

[0024] Hydraulic brakes 11FL to 11RR (hereinafter sometimes collectively referred to as the brake 11) for braking the wheels 10FL to 10RR are attached to each of the wheels 10FL to 10RR (hereinafter sometimes collectively referred to as the wheels 10). Further, wheel speed sensors 12FL to 12RR (hereinafter sometimes collectively referred to as the wheel speed sensor 12) for detecting the wheel rotation speed are attached to each of the wheels 10FL to 10RR.

[0025] The wheel speed sensor 12 is a non-contact sensor that detects a change in the magnetic field by a rotor (gear rotor or magnetic rotor) that rotates together with the wheel 10. For example, a method of detecting rotor rotation with a magnetic pickup, a Hall element, an MR element, or the like is preferably used. The wheel speed sensor 12 is connected to an EV-CU 60 described later. The wheel speed sensor 12 may be connected to a VDCU 50 described later.

[0026] With this configuration, in vehicle 1, the front wheels 10FL and 10FR are directly driven by the front motor generator 21, and the rear wheels 10RL and 10RR are directly driven by the rear motor generator 22. The balance between the driving force of the front motor generator 21 and the driving force of the rear motor generator 22 is controlled, and the driving force of the front and rear wheels 10 is arbitrarily and variably distributed. Furthermore, regeneration can be performed by the front motor generator 21 and the rear motor generator 22 during braking, etc.

[0027] The front motor generator 21 and the rear motor generator 22 are oil-cooled electric motors that are cooled by oil. The temperature of the front motor generator 21, rear motor generator 22, battery 72, front inverter 71F, rear inverter 71R, etc., is adjusted to an appropriate range by the heat exchange system (temperature control system) 80. As shown in Figure 2, the heat exchange system (temperature control system) 80 mainly consists of an oil circulation system 81, a cooling water circulation system 82, and a heat exchanger 85.

[0028] The oil circulation system (motor cooling system) 81 mainly consists of an electric oil pump 83, a front motor generator 21, a rear motor generator 22, etc. The electric oil pump 83 pressurizes and discharges oil, forcibly circulating it. The electric oil pump 83 sends oil cooled by the heat exchanger 85 to the front motor generator 21 and the rear motor generator 22. The oil that has cooled the front motor generator 21 and the rear motor generator 22 (i.e., the oil that has been heated by the front motor generator 21 and the rear motor generator 22) is sent to the heat exchanger 85, where heat exchange takes place between the oil and the cooling water.

[0029] The coolant circulation system (battery temperature control system) 82 mainly consists of an electric water pump 88, a radiator 86, a battery 72, a front inverter 71F, a rear inverter 71R, a switching valve 87, etc. The electric water pump 88 forcibly circulates the coolant by pressurizing and discharging it. The radiator 86 performs heat exchange between the coolant and the atmosphere (i.e., dissipates the heat of the coolant to the outside). The switching valve 87 operates, for example, according to the coolant temperature to switch the piping (path) through which the coolant flows. More specifically, during warm-up, the switching valve 87 switches the path of the coolant piping to bypass the radiator 86 to promote warm-up. Therefore, when the coolant temperature is low, the coolant is circulated by bypassing the radiator 86. Also, during the motor heat generation treatment described later, the coolant is circulated by bypassing the radiator 86.

[0030] The heat exchanger 85 performs heat exchange between the oil that cools the front motor generator 21 and the rear motor generator 22 and the cooling water that regulates the temperature of the battery 72.

[0031] Returning to Figure 1, the drives of the front motor generator 21, rear motor generator 22, electric brake booster 51 (drive motor), electric oil pump 83, and electric water pump 88 are comprehensively controlled by the EV-CU 60. The EV-CU 60 is connected via CAN (Controller Area Network) 100 to communicate with the Vehicle Dynamics Control Unit (hereinafter referred to as "VDCU") 50, etc., which suppresses skidding of the vehicle 1 and improves driving stability.

[0032] The EV-CU60 and VDCU50 are configured to include a microprocessor for performing calculations, an EEPROM for storing programs and the like for causing the microprocessor to execute various processes, a RAM for storing various data such as calculation results, a backup RAM for which the stored contents are retained, and input / output interfaces, etc.

[0033] The VDCU 50 is connected to, for example, a steering angle sensor 16, a longitudinal acceleration (longitudinal G) sensor 55, a lateral acceleration (lateral G) sensor 56, a yaw rate sensor 57, and a brake switch 58. The longitudinal acceleration sensor 55 detects the longitudinal acceleration acting on the vehicle 1, and the lateral acceleration sensor 56 detects the lateral acceleration acting on the vehicle 1. The steering angle sensor 16 detects the steering angle of the front wheels 10FL and 10FR (i.e., the steering angle of the steering wheel 15) by detecting the rotation angle of the pinion shaft. The yaw rate sensor 57 detects the yaw rate of the vehicle 1.

[0034] The VDCU 50 drives the hydraulic brake 11 in accordance with the amount of brake pedal operation (pressure), thereby braking the vehicle 1. It also detects vehicle behavior using various sensors (e.g., wheel speed sensor 12, steering angle sensor 16, longitudinal acceleration sensor 55, lateral acceleration sensor 56, yaw rate sensor 57, etc.) and suppresses skidding through automatic pressurization brake control using an electric brake booster 51 and motor torque control, thereby ensuring vehicle stability during cornering. In other words, the VDCU 50 prevents skidding and ensures excellent driving stability when the vehicle's attitude (behavior) is disturbed, for example, when entering a corner at excessive speed or when the vehicle's attitude (behavior) is disturbed by sudden steering maneuvers.

[0035] Furthermore, the VDCU 50 brakes the vehicle 1 (wheels 10) by driving the electric brake booster 51 (i.e., driving the hydraulic brake 11) in response to a braking request from the EV-CU 60 during motor heat generation treatment (details will be described later). The electric brake booster 51 drives the hydraulic brake 11 by generating brake hydraulic pressure, for example, by pressing the primary piston with the power of the drive motor. However, since the electric brake booster 51 cannot be driven continuously for a long period of time due to thermal limitations, it cannot be driven continuously during the motor heat generation treatment described later.

[0036] The VDCU50 transmits detected steering angle, longitudinal acceleration, lateral acceleration, yaw rate, and braking information to the EV-CU60 via the CAN100. Conversely, the VDCU50 receives braking request information from the EV-CU60 via the CAN100.

[0037] The EV-CU60 is connected to various sensors, including, for example, an accelerator sensor 61 that detects the amount the accelerator pedal is pressed (accelerator operation amount), a resolver 62 that detects the rotational position (rotational speed) of the front motor generator 21 (corresponding to the rotational detection means described in the claims), a resolver 63 that detects the rotational position (rotational speed) of the rear motor generator 22 (corresponding to the rotational detection means described in the claims), and a wheel speed sensor 12 that detects the speed of the wheels 10 as described above. The EV-CU60 is also connected to a temperature sensor 64 that detects the temperature of the battery 72 as described above. Furthermore, the EV-CU60 is connected to an oil temperature sensor 65 that detects the oil temperature, and an electrical signal (voltage value) corresponding to the oil temperature is read by the EV-CU60. As the oil temperature sensor 65, for example, a thermistor whose resistance value changes with temperature is preferably used.

[0038] Furthermore, the EV-CU60 receives the current values ​​supplied to the front motor generator 21 and the rear motor generator 22, respectively, which are detected by the current sensor, either directly or via CAN100 from the PDU70, which will be described later.

[0039] Furthermore, the EV-CU60 receives various types of information from the VDCU50 via CAN100, such as steering angle, longitudinal acceleration, lateral acceleration, yaw rate, and braking information.

[0040] Based on the various information acquired, the EV-CU60 comprehensively controls the drive of the front motor generator 21 and the rear motor generator 22. The EV-CU60 calculates and outputs the target torque (torque command value) for the front motor generator 21 and the rear motor generator 22 based on, for example, the accelerator input (driver's requested driving force), the driving state of the vehicle 1 (vehicle speed, etc.), and the charge state (SOC) of the battery 72. Furthermore, as described above, the EV-CU60 controls the electric brake booster 51, the electric oil pump 83, and the electric water pump 88, etc. In other words, the EV-CU60 functions as the control unit described in the claims.

[0041] In this process, the EV-CU60 adjusts (controls) the output torque of the front motor generator 21 and the rear motor generator 22 so that the front-to-rear drive force distribution corresponds to the frictional force between the front wheels 10FL, 10FR and the rear wheels 10RL, 10RR and the road surface. The EV-CU60 also determines the ground contact load of the front wheels 10FL, 10FR and the rear wheels 10RL, 10RR from the longitudinal and lateral acceleration of the vehicle 1, and estimates the frictional force with the road surface based on this ground contact load.

[0042] The power control unit (hereinafter referred to as "PCU") 70 drives the front motor generator 21 and the rear motor generator 22, respectively, via the front inverter 71F and the rear inverter 71R, based on the target torque (torque command value). Here, the front inverter 71F and the rear inverter 71R each convert the DC power (current) of the battery 72 into three-phase AC power (current) and supply it to the front motor generator 21 and the rear motor generator 22, respectively. On the other hand, during regeneration, the front inverter 71F and / or the rear inverter 71R convert the AC power generated by the front motor generator 21 and / or the rear motor generator 22 into DC power to charge the battery 72.

[0043] Incidentally, the battery 72 tends to have a characteristic where its internal resistance increases as the temperature drops, and its charge and discharge characteristics deteriorate. Therefore, for example, when the ambient temperature is low and the battery 72 is cold, the charging time will be longer, and it will not be able to output high power.

[0044] Therefore, the EV-CU60 has a function to generate motor heat when the vehicle is stopped (parked), even if the drive system 13F that transmits the driving force of the electric motor (front motor generator 21 in this embodiment) to the wheels 10 (front wheels 10FL, 10FR in this embodiment) does not have a parking gear or parking brake, etc., without adding a dedicated parking gear or parking brake, etc. In other words, the EV-CU60 generates motor heat using the front motor generator 21 in addition to the rear motor generator 22. In the EV-CU60, this function is realized by the execution of a program stored in EEPROM, etc., by a microprocessor. The following explanation will mainly focus on the front motor generator 21.

[0045] When the EV-CU60 is parked (vehicle stopped) and a predetermined heat generation start condition is met, including the condition that the battery 72 temperature is below a predetermined temperature (e.g., 0°C), it drives the electric brake booster 51 (hydraulic brake 11) and supplies power (current) to the front motor generator 21. After a predetermined time (e.g., several seconds to several tens of seconds) has elapsed, it stops driving the electric brake booster 51 and performs a heat generation feasibility determination process to determine whether the front motor generator 21 (or wheels 10) rotated while the electric brake booster 51 was driving and after it stopped.

[0046] Furthermore, at that time, the EV-CU60 drives the electric oil pump 83 to a discharge flow rate that is sufficient to wet the entire stator of the front motor generator 21. It is preferable that the above predetermined time be set considering the thermal continuous operating time of the electric brake booster 51.

[0047] If the front motor generator 21 (or wheel 10) is not rotating, after a predetermined time has elapsed (i.e., after the temperature of the electric brake booster 51 has dropped below a predetermined temperature), the EV-CU60 drives the electric brake booster 51 (hydraulic brake 11) again while increasing (adding) the power (current) supplied to the front motor generator 21 by a predetermined amount, stops driving the electric brake booster 51 after a predetermined time has elapsed, and determines whether the front motor generator 21 (or wheel 10) rotated while the electric brake booster 51 was driving and after it stopped (executes a heat generation feasibility determination process). In other words, it determines that the front motor generator 21 is operating as commanded when the supplied power (current) is increased, and that the front motor generator 21 is not rotating (for example, that the rotor phase angle fluctuation [deg] or [deg / sec] is below a predetermined angle (threshold)).

[0048] If the front motor generator 21 (wheel 10) does not rotate, the EV-CU60 increases the power (current) supplied to the front motor generator 21 (by adding a predetermined value) and repeatedly performs the above heat generation feasibility determination process.

[0049] When the EV-CU60 receives power (current) supplied to the front motor generator 21 and reaches a predetermined target power (current), it continues to perform a heat generation process that maintains that state, i.e., stops the operation of the electric brake booster 51 and supplies the predetermined target power (current) to the front motor generator 21, until the battery 72 reaches a predetermined target temperature. Here, the heat generation feasibility determination process and the heat generation process are collectively referred to as the motor heat generation process. Furthermore, it is preferable to set the predetermined target power (current) taking into consideration, for example, temperature requirements.

[0050] Subsequently, when the temperature of the battery 72 reaches a predetermined target temperature, the EV-CU60 stops supplying power to the front motor generator 21 and terminates the motor heat generation process, which consists of a heat generation feasibility determination process and a heat generation process.

[0051] On the other hand, if the EV-CU60 is performing (or is performing) the motor heat generation process (heat generation feasibility determination process or heat generation process) and the front motor generator 21 (or wheel 10) rotates by more than a predetermined angle, it immediately stops the power supply to the front motor generator 21, stops the rotation of the front motor generator 21 (i.e., the rotation of the front wheels 10FL and 10FR), and cancels the motor heat generation process (heat generation feasibility determination process or heat generation process). It is preferable that the above predetermined angle is set considering, for example, the angle at which the backlash of the gears and other components constituting the drive system 13F of the front motor generator 21 becomes compressed.

[0052] Furthermore, it is preferable that the EV-CU60 increases the discharge rate of the electric oil pump 83 as the power (current) supplied to the front motor generator 21 increases (as the temperature of the front motor generator 21 rises). For example, it is preferable to reduce the discharge rate of the electric oil pump 83 when the heat generation feasibility determination process is executed, and to increase the discharge rate of the electric oil pump 83 when the heat generation process is executed.

[0053] Next, the operation of the battery heating device (motor heating system) 3 will be explained with reference to Figures 3 and 4. Figure 3 is a flowchart showing the processing procedure for motor heating (heat heating feasibility determination process and heating process) by the battery heating device 3. This process is mainly performed repeatedly at predetermined timings in the EV-CU60. Figure 4 is a timing chart showing the changes in the heating command flag, electric oil pump flow rate, motor command current, brake command, and battery temperature when the motor heating process (heat heating feasibility determination process and heating process) is performed by the battery heating device 3. The horizontal axis of Figure 4 represents time, and the vertical axis, from top to bottom, represents the heating command flag, electric oil pump (EOP) flow rate, motor command current, brake command, and battery temperature.

[0054] In step S100, a determination is made as to whether the predetermined heat generation initiation conditions have been met, including the conditions that the vehicle is parked (stopped) and that the temperature of the battery 72 is below a predetermined temperature. If the heat generation initiation conditions are not met, the process is temporarily exited. On the other hand, if the heat generation initiation conditions are met, the process proceeds to step S102 (see time t1 in Figure 4).

[0055] In step S102, the electric oil pump 83 and other components are driven, and the heat exchange system (temperature control system) 80 is activated (see time t1 in Figure 4).

[0056] Next, in step S104, the electric brake booster 51 (hydraulic brake 11) is driven, and power (current) is supplied to the front motor generator 21 (see time t2 in Figure 4).

[0057] Next, in step S106, a determination is made as to whether the front motor generator 21 (or wheel 10) has rotated by a predetermined angle or more. If the front motor generator 21 (or wheel 10) has rotated by a predetermined angle or more, the process proceeds to step S108. On the other hand, if the front motor generator 21 (or wheel 10) has not rotated by a predetermined angle or more, the process proceeds to step S110.

[0058] In step S108, the power supply to the front motor generator 21 is stopped, the rotation of the front motor generator 21 (i.e., the rotation of the front wheels 10FL and 10FR) is stopped, and the motor heat generation process (heat generation feasibility determination process) is canceled. Various system checks (fail checks) are also performed. After that, the system exits this process.

[0059] Meanwhile, in step S110, a determination is made as to whether a predetermined time has elapsed since the start of operation of the electric brake booster 51. If the predetermined time has not elapsed, this process is repeated until the predetermined time has elapsed. If the predetermined time has elapsed, the process moves on to step S112 (see time t3 in Figure 4).

[0060] In step S112, the drive of the electric brake booster 51 (hydraulic brake 11) is stopped (see time t3 in Figure 4). Then, in the following step S114, a determination is made as to whether the front motor generator 21 (or wheel 10) has rotated by a predetermined angle or more. If the front motor generator 21 (or wheel 10) has rotated by a predetermined angle or more, the process proceeds to step S108 described above. Power supply to the front motor generator 21 is stopped, the rotation of the front motor generator 21 (i.e., the rotation of the front wheels 10FL and 10FR) is stopped, and the motor heat generation process (heat generation feasibility determination process) is canceled. Various system checks (fail checks) are also performed. After that, the process is temporarily exited.

[0061] On the other hand, if the front motor generator 21 (or wheel 10) does not rotate by a predetermined angle or more, the process proceeds to step S116. In step S116, a determination is made as to whether the power (current) supplied to the front motor generator 21 has reached a predetermined target power (current). If the power (current) supplied to the front motor generator 21 has not reached the predetermined target power (current), the process proceeds to step S118. On the other hand, if the power (current) supplied to the front motor generator 21 has reached the predetermined target power (current), the process proceeds to step S120 (see time t8 in Figure 4).

[0062] In step S118, after a predetermined time has elapsed (for example, after the temperature of the electric brake booster 51 has dropped below a predetermined temperature), the electric brake booster 51 (hydraulic brake 11) is driven again, and the power (current) supplied to the front motor generator 21 is increased (added) by a predetermined amount (see time t4 in Figure 4). After that, the process moves to step S106, and the processes of steps S106 to S116 described above are executed again (repeatedly) (see times t4 to t8 in Figure 4).

[0063] On the other hand, in step S120, the discharge volume (oil circulation volume) of the electric oil pump 83 is increased, and the amount of heat supplied to the battery 72 (motor heat generation) is maximized (see time t8 in Figure 4).

[0064] Next, in step S122, a determination is made as to whether the temperature of the battery 72 has reached a predetermined target temperature. If the temperature of the battery 72 has not reached the predetermined target temperature, in step S124, that state is maintained, namely, the driving of the electric brake booster 51 is stopped and a predetermined target power (current) is supplied to the front motor generator 21, until the temperature of the battery 72 reaches the predetermined target temperature (heat generation treatment is continued).

[0065] On the other hand, when the temperature of the battery 72 reaches a predetermined target temperature, in step S126, the power supply to the front motor generator 21 is stopped, and the motor heat generation process is terminated. After that, the process is exited (see time t9 in Figure 4).

[0066] As described in detail above, according to this embodiment, when the front motor generator 21 does not rotate (i.e., the wheel 10 does not rotate) during and after the electric brake booster 51 is driven, the power supplied to the front motor generator 21 is increased, and when the power supplied to the front motor generator 21 reaches a predetermined target power without the front motor generator 21 rotating (i.e., without the wheel 10 rotating), that state is maintained (heat generation treatment is performed). Therefore, motor heat generation can be performed after confirming that the front motor generator 21 (wheel 10) is not rotating.

[0067] As a result, even if the drive system 13F that transmits the driving force of the front motor generator 21 to the wheels 10 does not have a parking gear or parking brake, it becomes possible to generate motor heat using the front motor generator 21 when the vehicle is stopped (parked) without adding a dedicated parking gear or parking brake. In other words, it becomes possible to generate motor heat using the front motor generator 21 in addition to the rear motor generator 22. Furthermore, this makes it possible to increase the amount of heat generated by the motor (the amount of heat supplied to the battery 72).

[0068] On the other hand, according to this embodiment, if the front motor generator 21 (or wheel 10) rotates by more than a predetermined angle while the motor heat generation process (heat generation feasibility determination process, heat generation process) is being performed, the power supply to the front motor generator 21 is immediately stopped, and the motor heat generation process (heat generation feasibility determination process, heat generation process) is canceled. Therefore, the rotation of the front motor generator 21 (i.e., the rotation of the wheel 10) can be stopped quickly and reliably.

[0069] Furthermore, according to this embodiment, when the temperature of the battery 72 reaches a predetermined target temperature, the power supply to the front motor generator 21 is stopped, and the motor heat generation process (heat generation feasibility determination process, heat generation process) is terminated. Therefore, unnecessary power consumption can be suppressed.

[0070] According to this embodiment, when the power (current) supplied to the front motor generator 21 is increased, the discharge volume of the electric oil pump 83 is increased. Therefore, when the power supplied to the front motor generator 21 is low, the discharge volume (oil circulation volume) of the electric oil pump 83 is reduced to promote the heating of the front motor generator 21, while when the power (current) supplied to the front motor generator 21 is high, the discharge volume (oil circulation volume) of the electric oil pump 83 is increased to maximize the amount of heat supplied to the battery 72 (motor heat generation).

[0071] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiments, the present invention was described using the case where it is applied to a two-motor electric vehicle (BEV) as an example, but the present invention can also be applied to electric vehicles (BEV) with, for example, one motor (for example, only the front motor generator 21). That is, in the above embodiments, the present invention was described using the case where it is applied to an AWD vehicle (all-wheel drive vehicle) as an example, but the present invention can also be applied to, for example, a 2WD vehicle. Furthermore, it can also be applied to fuel cell vehicles (FCVs) and the like.

[0072] Furthermore, in the above embodiment, the parking gear 14 and parking brake 17 are provided only on the rear wheel drive system 13R, but it is also possible to configure the system so that the parking gear 14 and parking brake 17 are provided only on the front wheel drive system 13F.

[0073] Furthermore, the system configuration of controllers such as EV-CU60 and VDCU50, and the division of functions among the controllers, are not limited to the above embodiment. For example, in the above embodiment, the wheel speed sensor 12 is connected to EV-CU60, but it may also be connected to VDCU50 and transmitted to EV-CU60 via CAN100. Furthermore, in the above embodiment, EV-CU60, PCU70, and VDCU50 are connected to communicate with each other via CAN100, but the system configuration is not limited to this form and can be arbitrarily changed (integrated, etc.) considering, for example, functional requirements and costs. [Explanation of Symbols]

[0074] 1. Electric all-wheel drive vehicle 3. Battery heating device 10FL,10FR,10RL,10RR wheels 11FL, 11FR, 11RL, 11RR Brakes 12FL, 12FR, 12RL, 12RR Wheel Speed ​​Sensor 13F, 13R drivetrain 14 Parking gear 16 Steering angle sensor 17. Electric parking brake 21. Front Motor Generator (Front Electric Motor) 22 Rear Motor Generator (Rear Electric Motor) 45L Left front drive shaft 45R Right front drive shaft 48L Left rear drive shaft 48R Right rear drive shaft 50 VDCU 51 Electric brake booster 55 Front and rear accelerometer 56. Lateral acceleration sensor 57 Yaw Rate Sensor 58 Brake switch 60 EV-CU (Control Unit) 61 Accelerator sensor 62, 63 Resolver (rotation detection means) 64 Temperature sensor (temperature detection means) 65 Oil temperature sensor 70 PCU 71F Front Inverter 71R Rear Inverter 72 High-voltage battery (battery) 80 Heat exchange system (temperature control system) 81 Oil circulation system 82 Cooling water circulation system 83 Electric oil pump 85 Heat exchanger 86 Radiator 87 Switching valve 88 Electric Water Pump 100 CAN

Claims

1. An electric motor drives the wheels via a drive system that does not have a parking gear or parking brake, A hydraulic brake having an electric brake booster that generates brake hydraulic pressure using a drive motor, and using the brake hydraulic pressure to brake the wheels, A battery that supplies power to the electric motor, A heat exchanger that performs heat exchange between the electric motor and the battery, Rotation detection means for detecting the rotation of the electric motor, A temperature detection means for detecting the temperature of the battery, The electric motor and the electric brake booster are controlled by a control unit, The aforementioned control unit is When predetermined heat generation initiation conditions are met, including the condition that the vehicle is parked and the battery temperature is below a predetermined temperature, the electric brake booster is driven while power is supplied to the electric motor, the drive of the electric brake booster is stopped after a predetermined time has elapsed, and a heat generation feasibility determination process is performed to determine whether the electric motor rotated while the electric brake booster was being driven and after it was stopped. If the electric motor does not rotate, the power supplied to the electric motor is increased and the process of determining whether or not heat generation is possible is repeated. When the power supplied to the electric motor reaches a predetermined target power, the drive of the electric brake booster is stopped, and a heat generation process is performed to maintain the state in which the electric motor is supplied with the predetermined target power. A battery heating device characterized by the following features.

2. The battery heating device according to claim 1, characterized in that, when the control unit is performing the heat generation feasibility determination process or the heat generation process, if the electric motor rotates by an angle greater than a predetermined angle, it stops supplying power to the electric motor and cancels the motor heat generation process consisting of the heat generation feasibility determination process and the heat generation process.

3. The battery heating device according to claim 2, characterized in that when the temperature of the battery reaches a predetermined target temperature, the control unit stops supplying power to the electric motor and terminates the motor heating process, which consists of the heating feasibility determination process and the heating process.

4. It has an electric oil pump that pressurizes and discharges oil, supplying oil to cool the electric motor, The heat exchanger performs heat exchange between the oil that cools the electric motor and the battery. The battery heating device according to claim 3, characterized in that the control unit increases the discharge amount of the electric oil pump as the power supplied to the electric motor increases.

5. The electric motor includes a first electric motor that drives the front wheels and a second electric motor that drives the rear wheels. A parking gear and / or parking brake is provided in only one of the drive systems: the drive system that transmits the driving force of the first electric motor to the front wheels, and the drive system that transmits the driving force of the second electric motor to the rear wheels. The battery heating device according to claim 4, characterized in that the control unit performs the motor heat generation treatment using both the first electric motor and the second electric motor.

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