JP2018074655A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle which can exhibit a maximum driving force even when a difference is caused in cooling performance between motors.SOLUTION: An electric vehicle comprises: an output shaft which can transmit driving force of a first motor and a second motor to drive wheels; a control part which controls outputs of those motors; a first temperature detection part which detects a temperature of the first motor; and a second temperature detection part which detects a temperature of the second motor. In the electric vehicle, the control part is configured so as to control outputs of the first motor and second motor so that output torque of the first motor is limited to upper limit torque in the case that the temperature of the first motor is an output limit temperature or higher, and output torque of the second motor is limited to upper limit torque in the case that the temperature of the second motor is an output limit temperature or higher, and in the case that both of the temperatures of the first motor and the second motor are lower than the output limit temperature, output torque of one motor of which the detected temperature is relatively higher, out of the first motor and the second motor, becomes smaller than output torque of the other motor.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electric vehicle that travels by a driving force of a motor.

  Electric vehicles that travel by the driving force of a motor are in widespread use. In recent years, electric vehicles have been developed even for large vehicles such as large buses. To drive a large electric vehicle, a large driving force is required. For this reason, for example, the electric vehicle disclosed in Patent Document 1 includes two motors, and the two motors are connected to the same output shaft. By simultaneously driving, a double driving force obtained by synthesizing the outputs of the two motors is obtained from the output shaft.

JP-A-2006-54598

  By the way, in such an electric vehicle, the outputs of the two motors are normally controlled so that the torques output from the two motors are equal to each other with respect to the required torque. When the temperature of one motor rises above a certain temperature, it is necessary to limit the output of the one motor to protect the motor. However, since the driving force of the one motor is reduced while the output is limited, the opportunity to exhibit the maximum driving force is reduced. For this reason, it is preferable to reduce as much as possible the opportunity to apply power restrictions.

  Accordingly, an object of the present invention is to provide an electric vehicle capable of increasing the chances of exhibiting the maximum driving force even when a difference occurs in the cooling performance between the motors.

  In the electric vehicle according to the present invention, a first motor, a second motor, the first motor and the second motor are connected, and driving force of the first motor and the second motor is obtained. An output shaft capable of being transmitted to the drive wheel; and a controller that controls the outputs of the first motor and the second motor while simultaneously driving the first motor and the second motor. The electric vehicle further includes a first temperature detection unit that detects the temperature of the first motor, and a second temperature detection unit that detects the temperature of the second motor. The control unit limits the output torque of the first motor to a predetermined upper limit torque when the temperature of the first motor detected by the first temperature detection unit is equal to or higher than a predetermined output limit temperature. When the temperature of the second motor detected by the second temperature detector is equal to or higher than the output limit temperature, the output torque of the second motor is limited to the upper limit torque, and the temperature of the first motor And when the temperature of the second motor is lower than the output limit temperature, the output torque of one of the first motor and the second motor that has a relatively high detected temperature. Is configured to control the outputs of the first motor and the second motor so as to be smaller than the output torque of the other motor.

  In the electric vehicle of the present invention, when the temperatures of the two motors are both lower than the output limit temperature, the output torque of one motor having a relatively high temperature is smaller than the output torque of the other motor having a relatively low temperature. Thus, the outputs of the two motors are controlled.

  Accordingly, an increase in the temperature of the one motor can be suppressed, and the driving force can be increased by the other motor, so that the opportunity to exhibit the maximum driving force can be increased. In addition, since the occurrence of the opportunity for each motor to reach the output limit temperature is suppressed, the durability of the vehicle can be improved.

It is a block diagram which shows the structure of the electric vehicle which concerns on embodiment of this invention. It is a schematic diagram which shows the structure of a gear mechanism. It is a block diagram which shows the structure of the control system in an electric vehicle. It is a flowchart for demonstrating the motor output control performed with an electric vehicle. It is an image figure of the map data which defined the response | compatibility with the temperature difference and torque difference correction coefficient of the motor used by motor output control.

  Hereinafter, embodiments of the present invention will be described. This embodiment shows an example when the electric vehicle of the present invention is applied to, for example, a large bus.

  FIG. 1 is a block diagram illustrating a configuration of the electric vehicle according to the present embodiment. As shown in the figure, the electric vehicle 10 includes a first drive device 100, a second drive device 200, and a power transmission device 300. The first drive device 100 and the second drive device 200 each generate a driving force necessary for traveling the electric vehicle 10. The power transmission device 300 synthesizes the driving forces individually generated in the first driving device 100 and the second driving device 200 and transmits the combined driving force to the left and right driving wheels 11 and 12 of the electric vehicle 10. To do. That is, the electric vehicle 10 travels with the driving force generated by the first driving device 100 and the second driving device 200.

  Here, as shown in FIG. 1, the structure of the 1st drive device 100 and the 2nd drive device 200 is mutually the same. Therefore, in FIG. 1, constituent elements of the first driving device 100 are denoted by reference numerals in the 100s, and corresponding constituent elements of the second driving device 200 are denoted by reference numerals in the 200s. Furthermore, the code | symbol of the component which mutually respond | corresponds makes the last 2 digits the same. In the following description, the configuration of the first drive device 100 will be mainly described, and the description of the configuration of the second drive device 200 will be omitted as appropriate.

  The first drive device 100 includes a fuel cell device 110, a power storage device 120, an inverter 130, and a motor generator (MG) 140 (corresponding to a first motor of the present invention. Hereinafter, it may be referred to as a first motor). And.

  The fuel cell device 110 includes a fuel tank 111, a fuel cell stack 112, and a boost converter 113. The fuel tank 111 stores gas fuel such as hydrogen in a high pressure state. The fuel tank 111 depressurizes the stored gas fuel and supplies it to the fuel cell stack 112. The fuel cell stack 112 is a fuel cell having a stacked structure in which a plurality of solid oxide fuel cells are connected and overlapped. The fuel cell stack 112 generates power by a chemical reaction between gas fuel supplied from the fuel tank 111 and air (outside air) supplied from a blower (not shown). Boost converter 113 converts (boosts) the DC power generated by fuel cell stack 112 into a voltage suitable for supply to inverter 130, and inputs the boosted DC power to inverter 130.

  Power storage device 120 includes a rechargeable battery 121 and a boost converter 122. The step-up converter 122 is a DC / DC converter that supports both step-up and step-down. Boost converter 122 has a switching circuit (not shown) configured by a relay or the like. By driving the circuit, the boost converter 122 switches between energization paths when the battery 121 is charged and discharged. Boost converter 122 converts (boosts) the DC power supplied (discharged) from battery 121 to a voltage suitable for supply to inverter 130 when switched to the energization path during discharging, and the DC after boosting Electric power is input to the inverter 130. Boost converter 122 converts DC power supplied from fuel cell device 110 via boost converter 113 to a voltage suitable for supply to battery 121 (step-down) when switched to the energization path during charging. Then, the DC power after the step-down is supplied to the battery 121. As a result, the battery 121 is charged, and surplus power that has not been consumed by the motor generator 140 out of the power generated by the fuel cell device 110 is stored in the battery 121. The battery 121 is composed of, for example, a nickel / hydrogen storage battery.

  Inverter 130 converts the DC power supplied from fuel cell device 110 via its boost converter 113 or from power storage device 120 via its boost converter 122 to AC power (for example, three-phase AC power) to convert the motor into a motor. This is supplied to the generator 140. This supply causes the motor generator 140 to generate a driving force. Inverter 130 also converts regenerative power (AC power) from motor generator 140 into DC power and supplies it to power storage device 120. At this time, boost converter 122 of power storage device 120 converts (steps down) the DC power supplied from inverter 130 to a voltage suitable for supply to battery 121, and supplies the DC power after the step-down to battery 121. As a result, the battery 121 is charged and the regenerative power is stored in the battery 121.

  The motor generator 140 is a rotating electrical machine that receives a supply of AC power and generates a driving force. Such driving force is converted into propulsive force for traveling of the electric vehicle 10 by the power transmission device 300. In motor generator 140, regenerative power is generated when electric vehicle 10 is decelerated. The regenerative power is stored in the battery 121 of the power storage device 120 as described above, and is used later for traveling the electric vehicle 10 and the like.

  Further, the motor generator 140 is provided with a cooling circuit for cooling a stator, a rotor and the like housed in the motor housing (none is shown). The cooling circuit includes an oil pump that supplies and circulates oil for cooling the motor in the cooling path including the motor housing, an oil cooler that cools the cooled oil discharged from the motor housing to a cooling temperature, and a cooling temperature. It is composed of a reservoir tank for storing cooled oil and piping for connecting them. In this cooling circuit, oil for motor cooling is circulated in the cooling path by an oil pump, so that the stator and rotor of the motor generator 140 are cooled. The oil pump is a mechanical gear pump or an electric oil pump.

  The power transmission device 300 includes a gear mechanism 310, a propeller shaft 320, and a final reduction gear 330 including a differential mechanism.

  The gear mechanism 310 receives the driving force output from the rotating shaft 141 of the motor generator 140 and the rotating shaft 241 of the motor generator 240 (corresponding to the second motor of the present invention, hereinafter also referred to as a second motor). This is transmitted to the propeller shaft 320 via the output shaft of the gear mechanism 310. Specifically, as shown in FIG. 2, the gear mechanism 310 includes an idler shaft 311 and an output shaft 312. An input gear 311a and an output gear 311b are connected and fixed to the idler shaft 311 so as to rotate together. An output gear 141 a fixed to the rotating shaft 141 of the motor generator 140 and an output gear 241 a fixed to the rotating shaft 241 of the motor generator 240 are connected to the input gear 311 a. The output gear 311 b is connected to a driven gear 312 a that is fixed to the output shaft 312. With such a configuration, in the gear mechanism 310, when the rotation shaft 141 of the first motor and the rotation shaft 241 of the second motor rotate, the idler gear 311 rotates by the rotation thereof. At this time, the rotation of the rotation shaft 141 and the rotation shaft 241 is combined as the rotation of the idler shaft 311. Then, the rotation of the combined idler shaft 311 is output as the rotation of the output shaft 312. In other words, the electric vehicle 10 includes the motor generator 140 and the motor generator 240, and by connecting these two motor generators to the same output shaft 312, a double driving force obtained by combining the outputs of the two motor generators is output. It can be obtained from the shaft 312. In addition, since the rotating shaft 141 and the rotating shaft 241 are gear-coupled to the idler shaft 311, only one of them cannot rotate. Therefore, for example, even when the motor generator 140 is driven and only the rotation shaft 141 rotates, the rotation shaft 241 rotates along with the rotation of the idler shaft 311. In addition, one end of a propeller shaft 320 is connected to the output shaft 312 (not shown). Therefore, the propeller shaft 320 rotates integrally with the output shaft 312.

  The final reduction gear 330 is connected to the other end of the propeller shaft 320 as shown in FIG. Further, one end of each of the drive shafts 331 and 332 is connected to the final reduction gear 330. When the propeller shaft 320 rotates, the driving force is distributed by the differential mechanism of the final reduction gear 330, and the drive shafts 331 and 332 rotate. Left and right drive wheels 11 and 12 are connected to the other ends of the drive shafts 331 and 332, respectively. The electric vehicle 10 further includes two non-driving wheels in addition to the left and right driving wheels 11 and 12, but the non-driving wheels are not shown.

  With such a configuration, when the electric vehicle 10 travels, the driving force output from the motor generator 140 and the motor generator 240 is transmitted to the drive wheels 11 and 12 via the power transmission device 300, thereby traveling. The driving force for In the electric vehicle 10, during braking, the rotation of the drive wheels 11 and 12 is transmitted to the rotation shaft 141 and the rotation shaft 241 via the power transmission device 300, so that the motor generator 140 and the motor generator 240 respectively regenerate. Electric power is generated.

  In addition, the electric vehicle 10 includes a control device 400 for controlling the vehicle.

  FIG. 3 is a block diagram illustrating a configuration of the control device 400 in the electric vehicle 10 according to the present embodiment. As shown in FIG. 3, the control device 400 (corresponding to the control unit of the present invention) includes a main control unit 401, a first control unit 410, and a second control unit 420. Each of these control units 401, 410, 420 is configured as an electronic control unit (ECU) having a computer. The control device 400 is substantially configured as one computer system by the main control unit 401, the first control unit 410, and the second control unit 420. The main control unit 401 has a function of integrally controlling the entire electric vehicle 10. The first control unit 410 and the second control unit 420 are electrically connected to the main control unit 401 via signal lines, respectively. With this connection, the main control unit 401, the first control unit 410, and the second control unit 420 can communicate with each other. As shown in FIG. 1, the first control unit 410 is incorporated as a part of the first drive device 100 and is a subsystem for controlling the operation of the first drive device 100. The first control unit 410 controls driving of the motor generator 140, power generation of the fuel cell device 110, charge / discharge of the power storage device 120, and the like. On the other hand, the second control unit 420 is incorporated as a part of the second drive device 200 and is a subsystem for controlling the operation of the second drive device 200. The second control unit 420 performs the same control as the first control unit 410 regarding each component of the second drive device 200.

  Each of these control units 401, 410, and 420 is a microprocessor (CPU) that executes a control program to perform various calculations, a ROM that stores a control program and various map data, and data such as calculation results by the CPU temporarily. And an input / output port (both not shown).

  The control of the operation of the first drive device 100 by the first control unit 410 is performed by the CPU outputting a control signal to the component to be controlled by the first drive device 100 via the input / output port. For example, the CPU outputs a control signal to the boost converter 122 to control driving of the boost converter 122, so that the first control unit 410 controls power supplied from the power storage device 120 to the inverter 130. . In addition, the CPU outputs control signals to the fuel cell stack 112 and the boost converter 113 to control the driving of the fuel cell stack 112 and the boost converter 113, so that the first control unit 410 changes from the fuel cell device 110 to the power storage device 120 and inverter 130. Control the power supplied. Further, the CPU outputs a control signal to the inverter 130, whereby the first control unit 410 controls driving of the motor generator 140 via the inverter 130. The control of the operation of the second drive device 200 by the second control unit 420 is also performed by the same method as the control by the first control unit 410.

  Further, detection signals indicating the state of the vehicle are input to the CPUs of the control units 401, 410, and 420 from various sensors provided in the electric vehicle 10 via the input / output ports. As shown in FIG. 3, the main control unit 401 includes a vehicle speed sensor 13 that detects the vehicle speed of the electric vehicle 10, and an accelerator opening that detects a depression amount (accelerator opening) of an unillustrated accelerator pedal operated by the driver. A sensor 14 and a brake pedal sensor 15 for detecting a depression amount (brake operation amount) of a brake pedal (not shown) operated by the driver are connected. The first controller 410 also includes an MG rotation speed sensor 142 that detects the rotation speed (rotation speed) of the rotation shaft 141 of the motor generator 140, and a coil temperature that detects the temperature of a stator coil (not shown) of the motor generator 140. A sensor 143 (corresponding to the first temperature detection unit of the present invention), an SOC sensor 123 that detects the SOC value of the battery 121, and the like are connected. The SOC (State Of Charge) value is a value representing the state of charge of the battery in the range of 0% to 100% after defining the fully discharged state as 0% and the fully charged state as 100%. . The second control unit 420 also includes an MG rotation speed sensor 242 that detects the rotation speed (rotation speed) of the rotation shaft 241 of the motor generator 240, and a coil temperature that detects the temperature of a stator coil (not shown) of the motor generator 240. A sensor 243 (corresponding to the second temperature detection unit of the present invention), an SOC sensor 223 for detecting the SOC value of the battery 221, and the like are connected. By connecting these sensors, each control unit 401, 410, 420 acquires information necessary for judging the state of the vehicle from its own sensor or from the sensors of other control units by communication. be able to. The MG rotation speed sensors 142 and 242 are resolvers (rotation angle sensors) built in the motor generators 140 and 240, magnetic rotation angle sensors provided in the vicinity of the rotation shafts 141 and 241 of the motor generator, and the like. . Coil temperature sensors 143 and 243 are provided in stator coils (not shown) of motor generators 140 and 240. For the coil temperature sensors 143 and 243, for example, a thermistor is used.

  When electric vehicle 10 travels, control device 400 drives the two motors (motor generators 140 and 240) as follows in order to output the driving force necessary for traveling.

  First, the main control unit 401 of the control device 400 acquires information on the accelerator opening and the vehicle speed of the electric vehicle 10 with the sensors 14 and 13, and based on the information and map data acquired from the ROM, the vehicle The required driving force for is calculated. Next, the main control unit 401 calculates a total required torque tgr based on the calculated required driving force, and based on this required torque tgr, the torque (MG1 output torque) tg1 to be output by the motor generator 140 and the motor Torque (MG2 output torque) tg2 to be output by generator 240 is calculated. The main control unit 401 transmits an MG torque command (value) based on the calculated MG1 output torque tg1 to the first control unit 410, and an MG torque command (value) based on the calculated MG2 output torque tg2. Is transmitted to the second control unit 420.

  When receiving the MG torque command, the first control unit 410 of the control device 400 sets the output torque required by the MG torque command (MG1 output torque tg1) as the target output torque, and based on the setting, the inverter 130 The driving of the motor generator 140 is controlled via this. Specifically, the first control unit 410 outputs a control signal to the inverter 130 and performs PWM (pulse width modulation) control on the voltage supplied from the inverter 130 to the motor generator 140, thereby setting the target output that has been set. The drive of the motor generator 140 is controlled so that the torque is actually output from the motor generator 140. The drive control of the motor generator 240 performed when the second control unit 420 receives the MG torque command is performed in the same manner as the control by the first control unit 410. When the target output torque is set to a positive value, the motor generator functions as an electric motor and outputs torque for rotating the drive wheels. On the other hand, when the target output torque is set to a negative value, the motor generator functions as a generator and performs regenerative power generation by the rotation transmitted from the drive wheels.

  By the way, in the electric vehicle 10, from the viewpoint of equalizing the service life of the motor generators (hereinafter simply referred to as motors) 140, 240, in principle, the output of the motors 140, 240 should be as small as possible so as not to cause a torque difference. The driving of the two motors 140 and 240 is controlled. However, there are differences in the cooling performance between motors due to factors such as differences in the piping position of the motor cooling circuit due to mounting restrictions and individual differences in the parts that make up the motor cooling circuit. When it rises exceeding this, it will be necessary to carry out output restriction | limiting with respect to the said one motor for motor protection. When the motor output is limited, the output torque of the one motor is reduced, and the total maximum driving force is reduced.

  Therefore, in order to improve this point, in the electric vehicle 10 according to the present embodiment, the two motors are considered in consideration of the temperature difference between the motors 140 and 240 so that the motors 140 and 240 do not reach the temperature requiring the output restriction as much as possible. The outputs 140 and 240 are controlled.

  Hereinafter, this motor output control performed in the electric vehicle 10 of this embodiment is demonstrated.

  FIG. 4 is a flowchart for explaining motor output control performed in the electric vehicle 10 of the present embodiment. Note that the process shown in FIG. 4 is repeatedly executed at predetermined time intervals by the main control unit 401 of the control device 400 when the electric vehicle 10 is set to the travel mode, for example.

  When the processing of the flowchart is started, the main control unit 401 acquires information on the accelerator opening and the vehicle speed by the accelerator opening sensor 14 and the vehicle speed sensor 13 as the vehicle state in step S1.

  Next, in step S2, the main control unit 401 calculates the required driving force for the vehicle based on the information on the accelerator opening and the vehicle speed, the map data acquired from the ROM, and the like. Specifically, for example, the required driving force is calculated by selecting a driving force characteristic line corresponding to the accelerator opening from the map data and searching the driving force characteristic line by the vehicle speed.

  Next, the main control part 401 acquires the temperature information of the motor 140 which is a 1st motor, and the motor 240 which is a 2nd motor in step S3. Specifically, the main control unit 401 communicates with the first control unit 410 and the second control unit 420 and acquires temperature information of the motor 140 and the motor 240 from the coil temperature sensors 143 and 243.

  Next, in step S4, the main control unit 401 determines that the temperature th1 of the motor 140 (hereinafter also referred to as the first motor temperature th1) is less than a predetermined output limit temperature based on the temperature information acquired in step S3. It is determined whether or not there is. If the main control unit 401 determines in step S4 that the first motor temperature th1 is lower than the predetermined output limit temperature, the main control unit 401 proceeds to step S5 (YES side). On the other hand, when the main control unit 401 determines that the first motor temperature th1 is equal to or higher than the predetermined output limit temperature, the main control unit 401 proceeds to step S10 (NO side).

  In step S5, the main control unit 401 determines whether or not the temperature th2 of the motor 240 (hereinafter sometimes referred to as the second motor temperature th2) is lower than a predetermined output limit temperature based on the temperature information acquired in step S3. Determine whether. When the main control unit 401 determines in step S5 that the second motor temperature th2 is lower than the predetermined output limit temperature, the main control unit 401 proceeds to step S6 (YES side). On the other hand, when the main control unit 401 determines that the second motor temperature th2 is equal to or higher than the predetermined output limit temperature, the main control unit 401 proceeds to step S9 (NO side).

  In step S6, the main control unit 401 calculates a required torque tgr with respect to the required driving force.

  Next, in step S7, the main control unit 401 calculates the temperature difference thd of the two motors from the first motor temperature th1 and the second motor temperature th2, and the torque for the motors 140 and 240 based on the temperature difference thd. Determine the allocation.

  When a temperature difference occurs between the two motors 140 and 240 during operation, the output torque of the motor having a relatively high temperature is made smaller than the output torque of the motor having a relatively low temperature. In other words, if the outputs of the two motors are controlled so that the motor outputs have a torque difference opposite to the temperature difference, an increase in the temperature of the one motor having a higher temperature can be suppressed. At the same time, the driving force can be increased by the other motor having a lower temperature.

  If the outputs of the two motors are controlled in this way, the temperature of the motor having the higher temperature gradually decreases, and the temperature of the motor having the lower temperature increases. Then, when it is considered that there is no temperature difference between the two motors, the temperature of the two motors is equalized by controlling the outputs of the two motors so that the torques output from the motors are equal. It becomes like this. In this case, the temperatures of the two motors are equalized within a range in which the motor does not reach a temperature that requires output limitation. Therefore, the occurrence of the opportunity for each motor to reach the output limit temperature can be suppressed, and the durability of the vehicle can be improved.

  Therefore, in the electric vehicle 10 according to the present embodiment, the output torque difference between the two motors 140 and 240 is determined in advance so as to have a torque difference opposite to the temperature difference between the motors. Data or the like is stored in advance in the ROM of the main control unit 401. As an example, FIG. 5 shows an image of map data that defines the correspondence between the motor temperature difference and the torque difference. In this example of map data, a torque difference correction coefficient α (vertical axis) for causing a torque difference between the outputs of the two motors at a portion where the absolute value of the motor temperature difference thd (horizontal axis) exceeds a predetermined value tha. However, it is determined so as to increase in absolute value in proportion to the temperature difference thd. The torque difference correction coefficient α defines correction values for addition and subtraction of the torque difference for correcting the distribution ratio of the required torque tgr to the two motors 140 and 240. The predetermined value tha is an upper limit value of a temperature difference that does not give a difference in the lifetime between the two motors with respect to the motor lifetime against heat, and is also a threshold value for preventing control hunting.

  In the motor output control, the output of the two motors 140 and 240 is controlled using such map data. That is, when acquiring the map data from the ROM, the main control unit 401 obtains the torque difference correction coefficient α corresponding to the calculated motor temperature difference thd = th1−th2 from the map data. The main control unit 401 determines torque distribution for the two motors 140 and 240 based on the torque difference correction coefficient α. Specifically, for example, the temperature th1 of the motor 140 that is the first motor is higher than the temperature th2 of the motor 240 that is the second motor, and the torque difference correction coefficient α obtained from the map data is “−0.1. ”. In this case, the distribution ratio “−0.05” obtained by dividing “−0.1” of the torque difference correction coefficient α by “2” of the number of motors is the distribution ratio of the required torque tgr to the two motors, Here, since there are two motors, addition / subtraction is performed on “0.5 (motor 140): 0.5 (motor 240)”. That is, the division value “−0.05” is added to the distribution ratio “0.5” of the motor 140, while the division value “0.5” of the motor 240 is added to the division value “0.5”. Subtract “−0.05”. The value obtained by this calculation is the torque distribution for the two motors. In this case, the formula “0.5 + (− 0.05): 0.5 − (− 0.05)” is calculated, and the torque distribution is “0.45 (motor 140): 0.55 ( Motor 240) ".

  Next, in step S7, the main control unit 401 multiplies the determined torque distribution by the required torque tgr calculated in step S6, respectively, so that the torque (MG1 output torque) tg1 to be output by the motor 140 and Torque (MG2 output torque) tg2 to be output by the motor 240 is calculated.

  Next, in step S8, the main control unit 401 sends an MG torque command (value) based on the MG1 output torque tg1 to the first control unit 410 and an MG torque command (value) based on the MG2 output torque tg2. It transmits to the 2nd control part 420. The motor drive control performed when the first control unit 410 and the second control unit 420 receive the MG torque command is as described above.

  After performing the motor output control as described above, the main control unit 401 ends this routine.

  In the motor output control performed in the electric vehicle 10 of the present embodiment, the output torque of the motor having the higher temperature is higher than the output torque of the motor having the lower temperature in consideration of the temperature difference between the motors as described above. The outputs of the two motors are controlled so as to be smaller.

  On the other hand, when it is determined in step S5 that the second motor temperature (the temperature of the motor 240) th2 is equal to or higher than the predetermined output limit temperature, the main control unit 401 outputs the output limit corresponding to the output limit temperature in step S9. A value (corresponding to the upper limit torque of the present invention) is acquired from the ROM, and the output limit value (torque) is directly calculated as the MG2 output torque tg2. Further, main controller 401 calculates required torque tgr based on the required driving force, and calculates the result obtained by subtracting the output limit value from required torque tgr as MG1 output torque tg1. Then, the main control unit 401 proceeds to step S8.

  If it is determined in step S4 that the first motor temperature (the temperature of the motor 140) th1 is equal to or higher than the predetermined output limit temperature, the main control unit 401 obtains the temperature information acquired in step S3 in step S10. Based on this, it is determined whether or not the temperature of the motor 240 (second motor temperature) th2 is less than a predetermined output limit temperature. If the main control unit 401 determines in step S10 that the second motor temperature th2 is lower than the predetermined output limit temperature, the main control unit 401 proceeds to step S11 (YES side). On the other hand, when the main control unit 401 determines that the second motor temperature th2 is equal to or higher than the predetermined output limit temperature, the main control unit 401 proceeds to step S12 (NO side).

  In step S11, the main control unit 401 acquires an output limit value corresponding to the output limit temperature from the ROM, and calculates the output limit value (torque) as it is as the MG1 output torque tg1. Further, main controller 401 calculates required torque tgr based on the required driving force in the same manner as step S6, and calculates the result obtained by subtracting the output limit value from required torque tgr as MG2 output torque tg2. Then, the main control unit 401 proceeds to step S8.

  In the motor output control performed in the electric vehicle 10 of the present embodiment, when the temperature of one motor has reached the output limit temperature, the output torque of the motor is reduced by the output limit. Therefore, the outputs of the two motors are controlled so as to increase the output torque of the other motor.

  When it is determined in step S10 that the temperature (second motor temperature) th2 of the motor 240 is equal to or higher than the predetermined output limit temperature, the main control unit 401 outputs an output limit value corresponding to the output limit temperature in step S12. Is obtained from the ROM. In this case, output limitation is required for both the motor 140 and the motor 240. Therefore, the main control unit 401 calculates the output limit value (torque) acquired from the ROM as it is as the MG1 output torque tg1 and the MG2 output torque tg2. Then, the main control unit 401 proceeds to step S8.

  In the motor output control performed in the electric vehicle 10 according to the present embodiment, when the temperatures of both motors have reached the output limit temperature, the output torque is set to be equal within the range of the output limit. The outputs of the two motors are controlled.

  As described above, in the motor output control performed in the electric vehicle 10 of the present embodiment, the required driving force (step S2) and the required torque tgr (step S6) for the vehicle based on the accelerator opening and the vehicle speed detected by the sensor. Is calculated. When the temperatures of the two motors detected by the sensor, that is, the first motor temperature th1 and the second motor temperature th2 are both lower than the output limit temperature, the temperature difference between the two motors thd = th1-th2 And MG1 output torque tg1 and MG2 output torque tg2 are calculated based on the required torque tgr and the temperature difference thd (step S7). At this time, the torque distribution is such that the output torque of one motor having a relatively high temperature is smaller than the output torque of the other motor having a relatively low temperature (that is, lower than the temperature of the one motor). In addition, the larger the temperature difference thd, the larger the output torque difference is determined in absolute value.

  In the motor output control performed in the electric vehicle 10 of the present embodiment, the outputs of the two motors 140 and 240 are controlled based on the MG1 output torque tg1 and the MG2 output torque tg2 calculated as described above. Therefore, in this case, an increase in the temperature of one of the motors having a relatively high temperature can be suppressed, and the driving force can be increased by the other motor, so that a decrease in the maximum driving force can be suppressed. In this case, since the occurrence of the opportunity for each motor to reach the output limit temperature is suppressed, it is possible to increase the situation where the maximum driving force can be exhibited. In addition, since the reduction of the motor life with respect to heat can be suppressed by suppressing the expression, the reduction of the heat life of the vehicle can be suppressed and the durability of the vehicle can be improved.

  In the electric vehicle 10 of the present embodiment, the output gear fixed to the rotation shaft of the first motor (motor 140) and the output gear fixed to the rotation shaft of the second motor (motor 240) are the same idler shaft 311. In the above description, the input gear 311a is connected in parallel. However, as long as the double driving force obtained by synthesizing the outputs of the two motors can be obtained from the output shaft 312, a configuration other than the above may be used.

  In addition, the configuration of the control device 400 (the main control unit 401, the first control unit 410, and the second control unit 420) of the present embodiment is merely an example, and is not limited to the above configuration. For example, the main control unit 401 may be omitted, and the control device 400 may be configured by the first control unit 410 and the second control unit 420. In such a case, the first control unit 410 and the second control unit 420 are electrically connected by a signal line to enable mutual communication. In addition, sensors connected to the main control unit 401 (vehicle speed sensor 13, accelerator opening sensor 14, brake pedal sensor 15, etc.) are connected to one or both of the first control unit 410 and the second control unit 420. . The motor output control (the process shown in FIG. 4) executed by the main control unit 401 may be executed by the first control unit 410 or the second control unit 420. That is, the first control unit 410 or the second control unit 420 may be substituted for the main control unit 401.

  In the above description, the number of motors is two (motors 140 and 240). However, the number of motors may be three or more. In this case, for example, the distribution ratio of the required torque tgr to the motor is set so that the torque difference opposite to the temperature difference is given based on the temperature difference of each motor with the motor temperature as an input value. A function for outputting a correction value for correction is created in advance. Here, for example, the number of motors is three, and the distribution ratio of the required torque tgr to the three motors MG1, MG2, MG3 is, for example, “MG1 = 0.33: MG2 = 0.34: MG3 = 0.33 ". In this case, the temperature of each motor is “MG1 = T1, MG2 = T2, MG3 = T3”, and if the values of the temperatures of these three motors are given as inputs to the functions created in advance, , It is assumed that a correction value for the distribution ratio such as “MG1 = −0.1: MG2 = + 0.05: MG3 = + 0.05” is obtained. In this case, the correction value is added to the above distribution ratio, and the value obtained by the calculation becomes the torque distribution for the three motors with respect to the required torque tgr. That is, in this case, the torque distribution is determined as “MG1 = 0.23: MG2 = 0.39: MG3 = 0.38”, and therefore, according to the procedure described above based on this torque distribution and the required torque tgr. The MG1 output torque, the MG2 output torque, and the MG3 output torque may be calculated, and the outputs of the three motors may be controlled based on these torques.

  In the above description, the motor output is controlled on the basis of “torque (N · m)”, but the motor output is based on “power (W)” instead of “torque (N · m)”. You may make it perform control of.

  DESCRIPTION OF SYMBOLS 10 Electric vehicle, 11, 12 Drive wheel, 13 Vehicle speed sensor, 14 Accelerator opening sensor, 130, 230 Inverter, 140, 240 Motor generator (MG), 141, 241 Rotating shaft, 143, 243 Coil temperature sensor, 300 Power transmission Device, 310 gear mechanism, 311 idler shaft, 312 output shaft, 400 control device, 401 main control unit, 410 first control unit, 420 second control unit.

Claims (1)

A first motor;
A second motor;
An output shaft to which the first motor and the second motor are connected and capable of transmitting the driving force of the first motor and the second motor to driving wheels;
A controller that controls outputs of the first motor and the second motor while simultaneously driving the first motor and the second motor;
In an electric vehicle equipped with
A first temperature detector for detecting the temperature of the first motor;
A second temperature detector for detecting the temperature of the second motor,
The controller limits the output torque of the first motor to a predetermined upper limit torque when the temperature of the first motor detected by the first temperature detector is equal to or higher than a predetermined output limit temperature, When the temperature of the second motor detected by the second temperature detector is equal to or higher than the output limit temperature, the output torque of the second motor is limited to the upper limit torque, and the temperature of the first motor and the temperature of the first motor When both of the temperatures of the second motor are lower than the output limit temperature, the output torque of one of the first motor and the second motor having the relatively high detected temperature is the other. An electric vehicle configured to control outputs of the first motor and the second motor to be smaller than an output torque of the motor.

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