JP2007124832A - Drive force controller of electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance power efficiency of the entire electric vehicle, by controlling a motor such that the temperature of the motor approaches the ideal temperature, and that the power efficiency of the motor is improved. <P>SOLUTION: Target forward force Fxlt of left front and rear wheels and target forward force Fxrt of right front and rear wheels are calculated, based on an accelerator opening ψ, and the like, (S20-60). With regard to the motor generators 12FL and 12RL of the left front and rear wheels, target forward force Fxtfl of the left front wheel and target forward force Fxtrl of the left rear wheel are calculated, based on the larger one of target forward force Fxtl of the left front and rear wheels (S100), such that the actual temperature of the motor generator, having a larger difference between the actual temperature Tmfl, Tmrl and the ideal temperature Tmt of a motor generator, approaches the ideal temperature Tmt of that motor generator. Similarly, target forward force Fxtfr of the right front wheel and target forward force Fxtrr of the right rear wheel are calculated (S300), and the motor generators 12FL-12RR are controlled, based on the target forward force Fxti of each wheel (S500, 510). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving force control device for a vehicle such as an automobile, and more specifically, to a driving force control device for an electric vehicle in which an electric motor is provided for each wheel and the driving force of the electric motor is individually applied to a corresponding wheel. Related.

Electric motors corresponding to the respective wheels are provided, and various types of electric vehicles have been proposed in the past in which the driving force of the electric motor is individually applied to the corresponding wheels. As one of such electric vehicles, for example, as described in the following Patent Document 1 filed by the applicant of the present application, the distribution of driving force of each wheel so that vehicle stabilization control such as anti-skid control is performed well. 2. Description of the Related Art Conventionally, an electric vehicle including a driving force control device that performs control is known.
Japanese Patent Laid-Open No. 10-295004

  In general, there are various types of motor loss. Especially, loss that greatly affects the efficiency (power efficiency) of the motor depends on copper loss (heat loss due to winding resistance) and the viscosity of bearing lubricant and cooling oil. There is drag loss. As shown in FIG. 7, the copper loss increases as the motor temperature Tm increases, while the drag loss decreases as the motor temperature Tm increases. Therefore, if the temperature of the motor corresponding to the intersection of the copper loss line and the drag loss line in FIG. 7 is the ideal temperature Tmt, the power efficiency of the motor is highest when the temperature is the ideal temperature. In order to reduce power consumption and increase the power efficiency, it is preferable that the motor is controlled so that the temperature Tm of the motor having a large temperature difference from the ideal temperature is as close as possible to the ideal temperature Tmt.

  However, in the conventional driving force control apparatus for an electric vehicle as described above, the relationship between the motor loss, power efficiency, and ideal motor temperature is not considered at all in controlling the distribution of driving force. Therefore, there is a possibility that the power efficiency of the entire vehicle when the vehicle travels may be deteriorated, and improvement is required to improve the power efficiency of the entire electric vehicle by improving the power efficiency of the electric motor. Yes.

  The present invention has been made in view of the above-described problems in a conventional electric vehicle configured to be provided with a driving force of an electric motor corresponding to each wheel, and the main problem of the present invention is Focusing on the fact that the power efficiency of the motor decreases regardless of whether the motor temperature is higher or lower than the ideal temperature, and that the power efficiency of the motor increases as the motor temperature is closer to the ideal temperature. By controlling the electric motor so that the power efficiency of the vehicle is improved, the power efficiency of the entire electric vehicle is improved as compared with the conventional case.

  According to the present invention, the main problem described above is the driving force control device for an electric vehicle having the configuration of claim 1, that is, the electric vehicle having at least two electric motors for applying driving force to the wheels, and controls the output of the electric motor. An electric motor control means for detecting the actual temperature of the electric motor, and the electric motor control means uses the temperature at which the electric power efficiency of each electric motor is the highest as an ideal temperature to determine a deviation between the actual temperature and the ideal temperature. It is achieved by a driving force control device for an electric vehicle characterized by having means for determining an electric motor having a large size and controlling the output of the electric motor so that the actual temperature of the electric motor approaches the ideal temperature of the electric motor. The

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the electric vehicle has an electric motor that applies a driving force to a wheel corresponding to each wheel. However, the driving force required for the vehicle is distributed at least between the left and right wheels according to the running condition of the vehicle, and the deviation between the actual temperature and the ideal temperature is large for the two motors of the left front and rear wheels. The output of the other motor of the left front and rear wheels corresponds to the driving force distributed to the left front and rear wheels while controlling the output of the motor so that the actual temperature of the other motor approaches the ideal temperature of the motor The output of the motor of the other wheel is controlled so as to be a value obtained by subtracting the output of the motor with the larger deviation, and the deviation between the actual temperature and the ideal temperature for the two motors on the right front and rear wheels The larger one The output of the motor is controlled so that the actual temperature of the machine approaches the ideal temperature of the motor, and the output of the motor of the other wheel of the right front and rear wheels is more than the output corresponding to the driving force distributed to the right front and rear wheels. The output of the motor of the other wheel is controlled to be a value obtained by subtracting the output of the motor having the larger deviation (configuration of claim 2).

  In general, the temperature of the motor rises due to heat generated by the operation and decreases due to heat dissipation, and the amount of heat generated by the operation increases as the output of the motor increases.Therefore, when the temperature of the motor is lower than the ideal temperature, the output of the motor is increased. As a result, the temperature of the motor can be brought closer to the ideal temperature of the motor than when the output of the motor is not increased. Conversely, when the temperature of the motor is higher than the ideal temperature, the output of the motor is decreased by lowering the output of the motor. Compared with the case where the output is not lowered, the temperature of the electric motor can be made closer to the ideal temperature of the electric motor.

  According to the configuration of the first aspect, a motor having a large deviation between the actual temperature and the ideal temperature is determined from the motors, with the temperature having the highest power efficiency of each motor being an ideal temperature, and the actual motor Since the output of the motor is controlled so that the temperature of the motor approaches the ideal temperature of the motor, the temperature of the motor having a large temperature deviation can be reliably brought close to the ideal temperature, and thereby the power efficiency of the motor Can be reliably improved.

  Further, according to the configuration of the second aspect, the electric vehicle has an electric motor that applies a driving force to the corresponding wheel for each wheel, and the driving force required for the vehicle depends on the traveling state of the vehicle. The output of the motor is adjusted so that the actual temperature of the motor with the larger deviation between the actual temperature and the ideal temperature of the two left and right front motors approaches the ideal temperature of the motor. In addition to being controlled, the output of the motor of the other wheel of the left front and rear wheels is a value obtained by subtracting the output of the motor having the larger deviation from the output corresponding to the driving force allocated to the left front and rear wheels. The output of the motor on the other wheel is controlled so that the actual temperature of the motor with the larger deviation between the actual temperature and the ideal temperature for the two motors on the right front and rear wheels approaches the ideal temperature of the motor. Electric motor And the output of the motor of the other wheel of the right front and rear wheels is a value obtained by subtracting the output of the motor having the larger deviation from the output corresponding to the driving force allocated to the right front and rear wheels. Since the output of the motor of the other wheel is controlled, the output of the motor is controlled so that the temperature of the motor with the larger temperature deviation for both the left front wheel and the right front wheel approaches the ideal temperature. In addition, the power efficiency of the motor can be reliably improved, and the left / right distribution of the driving force due to the control of the output of the motor for improving the power efficiency is other than the predetermined distribution according to the traveling state of the vehicle. Can be reliably prevented.

[Preferred embodiment of problem solving means]
According to one preferable aspect of the present invention, in the configuration according to claim 1 or 2, the motor control means is such that the temperature of the motor having a large deviation between the actual temperature and the ideal temperature is lower than the ideal temperature. Sometimes, the output of the motor is increased, and when the temperature of the motor is higher than the ideal temperature, the output of the motor is decreased so that the actual temperature of the motor approaches the ideal temperature of the motor (preferred aspect 1). .

  According to another preferred aspect of the present invention, in the configuration of claim 1, the electric vehicle includes an electric motor that applies driving force to the wheels corresponding to the left and right front wheels and the left and right rear wheels. Preferred embodiment 2).

  According to another preferred aspect of the present invention, in the configuration of claim 1, the electric vehicle is a front wheel motor that applies driving force to the left and right front wheels and a rear wheel motor that applies driving force to the left and right rear wheels. It is comprised so that it may have an electric motor (the preferable aspect 3).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the motor control means is configured such that the temperature of the two front and rear wheels is lower than the ideal temperature for both the left front and rear wheels. When the temperature is high, the output of the motor having the higher temperature is decreased, so that the motors of the two front and rear wheels are controlled so that the temperature of the motor approaches the ideal temperature (preferred aspect 4).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 2 or the preferred embodiment 4, the motor control means is configured to control the temperature of the two front and rear wheels for both the left front and rear wheels. Is lower than the ideal temperature, by increasing the output of the motor with the lower temperature, the motors of the two front and rear wheels are controlled so that the temperature of the motor approaches the ideal temperature (preferred aspect 5). ).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 2 or the preferred embodiments 4 and 5, the motor control means is provided for either the left front wheel or the right front wheel. When the temperature of the two wheels is higher than the ideal temperature and the other temperature of the front and rear wheels is lower than the ideal temperature, the two wheels on the front and rear wheels are arranged so that the temperature of the motor with the larger deviation from the ideal temperature approaches the ideal temperature. It is comprised so that an electric motor may be controlled (preferred aspect 6).

  According to another preferred aspect of the present invention, in any of the left and right front wheels and the right front and rear wheels, the motor control means is the front wheel and the rear wheel. When the magnitude of the temperature deviation is less than or equal to the reference value, the motor is controlled based on the output required of the motor without bringing the temperature of the motor close to the ideal temperature (preferred aspect 7).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 2 or the preferred embodiments 4 to 7, the motor control means has an output of the motor for bringing the temperature of the motor close to an ideal temperature. When the maximum output of the motor is exceeded, the output of the motor is controlled to the maximum output, and the output of the other motor is controlled to a value obtained by subtracting the maximum output from the sum of the target outputs of the motors of the two wheels ( Preferred embodiment 8).

  According to another preferred aspect of the present invention, in the configuration of claim 1 or 2 or the preferred aspects 1 to 8, the motor control means is based on at least a deviation between the temperature of the motor and the ideal temperature. It is configured to control the increase / decrease amount of the output (preferred aspect 9).

  According to another preferred embodiment of the present invention, in the configuration of claim 1 or 2 or the preferred embodiments 1 to 9, all the motors are configured to have the same ideal temperature (preferred embodiment 10). ).

  According to another preferred aspect of the present invention, in the configuration of claim 1 or 2 or preferred modes 1 to 10, the electric motor is configured to perform regenerative braking during braking (preferred mode 11).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a first embodiment of a driving force control apparatus for an electric vehicle according to the present invention applied to an in-wheel motor type four-wheel drive vehicle.

  In FIG. 1, 10FL and 10FR respectively indicate left and right front wheels that are steering wheels, and 10RL and 10RR respectively indicate left and right rear wheels that are non-steering wheels. Motor generators 12FL and 12FR, which are in-wheel motors, are incorporated in the left and right front wheels 10FL and 10FR, respectively. The left and right front wheels 10FL and 10FR are driven by the motor generators 12FL and 12FR. The motor generators 12FL and 12FR also function as regenerative generators for the left and right front wheels during braking, respectively, and generate regenerative braking force.

  Similarly, motor generators 12RL and 12RR, which are in-wheel motors, are incorporated in the left and right rear wheels 10RL and 10RR, respectively. The left and right front wheels 10RL and 10RR are driven by the motor generators 12RL and 12RR. The motor generators 12RL and 12RR also function as left and right rear wheel generators during braking to generate regenerative braking force.

  The driving force of the motor generators 12FL to 12RR is controlled by the driving force control electronic control device 16 based on the accelerator opening φ as the accelerator pedal depression amount not shown in FIG. Is done. The regenerative braking force of the motor generators 12FL to 12RR is also controlled by the driving force control electronic control unit 16.

  Although not shown in detail in FIG. 1, the driving force control electronic control device 16 includes a microcomputer, a drive circuit, an inverter, and a battery. The microcomputer includes, for example, a CPU, a ROM, a RAM, and an input / output port. And a general configuration in which these are connected to each other by a bidirectional common bus. 1 is supplied to the motor generators 12FL to 12RR via a drive circuit and an inverter during normal driving, and regenerative by the motor generators 12FL to 12RR during deceleration braking of the vehicle. Electric power generated by braking is charged to the battery via the inverter and the drive circuit.

  The friction braking force of the left and right front wheels 10FL, 10FR and the left and right rear wheels 10RL, 10RR is controlled by controlling the braking pressure of the corresponding wheel cylinders 22FL, 22FR, 22RL, 22RR by the hydraulic circuit 20 of the friction braking device 18. The Although not shown in the drawing, the hydraulic circuit 20 includes a reservoir, an oil pump, various valve devices, etc., and the braking pressure of each wheel cylinder is normally determined by the amount of depression of the brake pedal 24 and depression of the brake pedal 24 by the driver. The brake pedal is controlled by the driver by controlling the oil pump and various valve devices by the electronic control device 28 for controlling the braking force as necessary. Control is performed regardless of the amount of depression of 24.

  Although not shown in detail in FIG. 1, the electronic control device 28 for controlling the braking force also includes a microcomputer and a drive circuit. The microcomputer includes, for example, a CPU, a ROM, a RAM, and an input / output port device. And may have a general configuration in which they are connected to each other by a bidirectional common bus.

  In addition to the signal indicating the accelerator opening φ from the accelerator opening sensor 14, the driving force control electronic control device 16 receives the temperature Tmi (i = fl, fr, fr) of the motor generators 12 FL to 12 RR from the temperature sensors 30 FL to 30 RR. rl, rr), a signal indicating the steering angle θ from the steering angle sensor 32, and a signal indicating the vehicle speed V from the vehicle speed sensor 34. Also, the braking force control electronic control unit 28 has a signal indicating the master cylinder pressure Pm from the pressure sensor 36, and a corresponding wheel braking pressure (wheel cylinder pressure) Pbi (i = fl, fr, rl,) from the pressure sensors 38FL to 38RR. rr) is input. The driving force control electronic control device 16 and the braking force control electronic control device 28 exchange signals with each other as necessary. The steering angle sensor 32 detects the steering angle θ with the left turning direction of the vehicle as positive.

  The driving force control electronic control device 16 calculates the target longitudinal force Fxt of the vehicle based on the accelerator opening φ and the master cylinder pressure Pm, which are the acceleration / deceleration operation amount of the driver, and the target longitudinal force Fxt is a negative value. When it is a braking force, the target longitudinal force Fxt is distributed to each wheel at a predetermined distribution ratio, and the target driving force Fxti (i = fl, fr, rl, rr) of each wheel is calculated. When the target driving force Fxti is equal to or less than the maximum regenerative braking force Fremax of the motor generators 12FL to 12RR, the target regenerative braking force Freti (i = fl, fr, rl, rr) of the motor generators 12FL to 12RR is used as the target driving force. The motor generators 12FL to 12RR are controlled so that the regenerative braking force of the motor generators 12FL to 12RR becomes the corresponding target regenerative braking force Freti, and the target friction braking force Fwbti (i = fl) of each wheel is set. , Fr, rl, rr) is output to the braking force control electronic control device 28 as 0.

  On the other hand, when the target driving force Fxti is higher than the maximum regenerative braking force Fremax of the motor generators 12FL to 12RR, the driving force control electronic control device 16 generates the maximum regenerative braking force Freti of the motor generators 12FL to 12RR. The motor generators 12FL-12RR are controlled so that the regenerative braking force of the motor generators 12FL-12RR becomes the maximum regenerative braking force Fremax by setting the braking force Fremax, and the target friction braking force Fwbti (= Fxti-Fremax of each wheel). ) And outputs a signal indicating the target friction braking force Fwbti to the braking force control electronic control unit 28.

  When the target longitudinal force Fxt is not a negative value but a driving force, the driving force control electronic control device 16 determines the left wheel distribution ratio Rl (0 <Rl <) of the target longitudinal force Fxt based on the steering angle θ, the vehicle speed V, and the like. 1) and the right wheel distribution ratio Rr (= 1-Rl) are calculated, and the left and right front wheel target longitudinal force Fxtl (= RlFxt) and the right front and rear wheel target longitudinal force Fxtr (= RrFxt) are calculated based on the left wheel distribution ratio Rl. Then, the target friction braking force Fwbti of each wheel is set to 0, and a signal indicating the target friction braking force Fwbti is output to the braking force control electronic control unit 28.

  The electronic controller 16 for controlling the driving force has a larger one of two deviations between the actual temperatures Tmfl and Tmrl and the ideal temperature Tmt of the motor generator for the two motor generators 12FL and 12RL of the left front and rear wheels. The output of the motor generator is controlled based on the target longitudinal force Fxlt of the left front and rear wheels and the larger temperature deviation so that the actual temperature of the motor generator approaches the ideal temperature Tmt of the motor generator. The output of the motor generator of the other wheel of the left front / rear wheel is controlled so as to be a value obtained by subtracting the wheel front / rear force corresponding to the output of the motor generator having a larger temperature deviation than the front / rear force Fxlt.

  Similarly, the electronic controller 16 for controlling the driving force has a magnitude of two deviations between the actual temperatures Tmfr and Tmrr and the ideal temperature Tmt of the motor generator for the two motor generators 12FR and 12RR of the right front and rear wheels. The output of the motor generator is controlled based on the target longitudinal force Fxrt of the right front and rear wheels and the larger temperature deviation so that the actual temperature of the larger motor generator approaches the ideal temperature Tmt of the motor generator. The output of the motor generator on the other wheel of the right front wheel is controlled so as to be a value obtained by subtracting the wheel front / rear force corresponding to the output of the motor generator having a larger temperature deviation than the target longitudinal force Fxrt. .

  Further, the braking force control electronic control unit 28 uses the target braking pressure Pbti (i = fl, fr, rl, rr) of each wheel based on the target friction braking force Fwbti of each wheel input from the electronic control unit 16 for driving force control. ) And the hydraulic circuit 20 is controlled so that the braking pressure Pbi of each wheel becomes the target braking pressure Pbti, so that the friction braking force Fwbi (i = fl, fr, rl, rr) of each wheel is The target friction braking force Fwbti is controlled.

  Next, the braking / driving force control in the illustrated embodiment 1 will be described with reference to the flowcharts shown in FIGS. The control according to the flowcharts shown in FIG. 2 to FIG. 4 is started when the driving force control electronic control device 16 is started, and every predetermined time until an ignition switch (not shown) is turned off. Will be executed repeatedly.

  First, in step 10, a signal indicating the accelerator opening φ detected by the accelerator opening sensor 14 is read, and in step 20, the technical field is based on the accelerator opening φ and the master cylinder pressure Pm. Then, the target longitudinal force Fxt of the vehicle is calculated in a known manner.

  In step 30, it is determined whether or not the target longitudinal force Fxt of the vehicle is a negative value, that is, whether or not the longitudinal force required for the vehicle is a braking force. In step 40, the braking force control electronic control unit 28 outputs a signal indicating the target longitudinal force Fxt and a braking force control command signal to the braking force control electronic control unit 28. If the braking force of each wheel is controlled based on the target longitudinal force Fxt in a manner known in the technical field, and a negative determination is made, the routine proceeds to step 50.

  In step 50, the left wheel distribution ratio Rl and the right wheel distribution ratio Rr of the target longitudinal force Fxt are calculated based on the steering angle θ, the vehicle speed V, and the like. In step 60, the left front and rear wheels are calculated based on the left wheel distribution ratio Rl. A target longitudinal force Fxtl (= RlFxt) and a right longitudinal wheel target longitudinal force Fxtr (= RrFxt) are calculated.

  In step 100, the magnitude of the two deviations between the actual temperatures Tmfl, Tmrl and the ideal temperature Tmt of the motor generator for the two left and right motor generators 12FL, 12RL in accordance with the routine shown in FIG. Based on the target front / rear force Fxtl of the left front / rear wheel and the larger temperature deviation, the front / rear target front / rear force Fxtfl and the left front wheel are adjusted so that the actual temperature of the motor generator with the larger The rear wheel target longitudinal force Fxtrl is calculated.

  Similarly, in step 300, according to the routine shown in FIG. 4, two deviations between the actual temperatures Tmfr and Tmrr and the ideal motor generator temperature Tmt for the two motor generators 12FR and 12RR of the right front and rear wheels. The target longitudinal force of the right front wheel is based on the target longitudinal force Fxtr of the left front and rear wheels and the larger temperature deviation so that the actual temperature of the larger motor generator approaches the ideal temperature Tmt of the motor generator. Fxtfr and the right front wheel target longitudinal force Fxtrr are calculated.

  In step 500, based on the target longitudinal force Fxti (i = fl, fr, rl, rr) calculated in steps 100 and 300, the target drive torque Txti (i = fl, fr, rl, rr) is calculated, and in step 510, the motor generators 12FL to 12RR are controlled so that the driving torque Txi of each wheel becomes the corresponding target driving torque Txti.

  Next, the routine for calculating the target front / rear force Fxtfl of the left front wheel and the target front / rear force Fxtrl of the left rear wheel executed in step 100 will be described with reference to the flowchart shown in FIG.

  First, at step 110, it is determined whether or not the temperature Tmfl of the motor generator 12FL for the left front wheel is lower than the ideal temperature Tmt and the temperature Tmrl of the motor generator 12RL for the left rear wheel is lower than the ideal temperature Tmt. If a negative determination is made, the process proceeds to step 160. If an affirmative determination is made, the process proceeds to step 120.

  In step 120, a deviation ΔTmlmin between the ideal temperature Tmt and the lower one of the temperatures Tmfl and Tmrl is calculated. In step 130, the temperature of the motor generator having the lower temperature rises and the ideal temperature increases. Based on the target longitudinal force Fxlt and temperature deviation ΔTmlmin of the left front and rear wheels, the target longitudinal force Fxltmin of the wheel with the lower motor generator temperature is based on the proportional, integral, and differential terms of the temperature deviation ΔTmlmin so as to approach the temperature Tmt. Is calculated by the PID compensation calculation.

  In step 140, the target longitudinal force Fxtlmax of the wheel having the higher temperature is calculated by subtracting the target longitudinal force Fxtlmin from the target longitudinal force Fxtl of the left front and rear wheels. In step 150, Tmfl <Tmrl. Sometimes the target longitudinal force Fxtfl of the left front wheel is set to the target longitudinal force Fxtlmin, and the target longitudinal force Fxtrl of the left rear wheel is set to the target longitudinal force Fxtlmax. Conversely, when Tmfl> Tmrl, the target longitudinal force of the left front wheel Fxtfl is set to the target longitudinal force Fxtlmax, and the target longitudinal force Fxtrl of the left rear wheel is set to the target longitudinal force Fxtlmin. When Tmfl = Tmrl, the target front / rear force Fxtfl of the left front wheel and the target front / rear force Fxtrl of the left rear wheel are both set to Fxtl / 2.

  In step 160, it is determined whether the temperature Tmfl of the left front wheel motor generator 12FL is higher than the ideal temperature Tmt and whether the temperature Tmrl of the left rear wheel motor generator 12RL is higher than the ideal temperature Tmt. If a negative determination is made, the process proceeds to step 210. If an affirmative determination is made, the process proceeds to step 170.

  In step 170, a deviation ΔTmlmax between the ideal temperature Tmt and the higher one of the temperatures Tmfl and Tmrl is calculated, and in step 180, the temperature of the motor generator having the higher temperature is decreased and the ideal temperature is decreased. Based on the target longitudinal force Fxtl and temperature deviation ΔTmlmax of the left front and rear wheels, the target longitudinal force Fxtlmax of the wheel with the higher motor generator temperature is determined from the proportional, integral, and differential terms of the temperature deviation ΔTmlmax so as to approach the temperature Tmt. Is calculated by the PID compensation calculation.

  In step 190, the target longitudinal force Fxtlmin of the lower temperature wheel is calculated by subtracting the target longitudinal force Fxtlmax from the target longitudinal force Fxtl of the left front and rear wheels. In step 200, Tmfl> Tmrl. Sometimes the target longitudinal force Fxtfl of the left front wheel is set to the target longitudinal force Fxtlmax, and the target longitudinal force Fxtrl of the left rear wheel is set to the target longitudinal force Fxtlmin. Conversely, when Tmfl <Tmrl, the target longitudinal force of the left front wheel Fxtfl is set to the target longitudinal force Fxtlmin, and the target longitudinal force Fxtrl of the left rear wheel is set to the target longitudinal force Fxtlmax. When Tmfl = Tmrl, the target front / rear force Fxtfl of the left front wheel and the target front / rear force Fxtrl of the left rear wheel are both set to Fxlt / 2.

  In step 210, the deviation ΔTmfl between the ideal temperature Tmt and the temperature Tmfl and the deviation ΔTmrl between the ideal temperature Tmt and the temperature Tmrl are calculated. In step 220, the larger one of the deviations ΔTmf1 and ΔTmrl (ΔTmlb ), The target longitudinal force Fxtllb of the wheel is proportional to the temperature deviation ΔTmlb based on the target longitudinal force Fxtl of the left front and rear wheels and the larger temperature deviation ΔTmlb so that the motor generator temperature approaches the ideal temperature Tmt. , An integral term, and a differential term.

  In step 230, the target longitudinal force Fxtlls of the smaller one of the temperature deviations ΔTmfl and ΔTmrl (ΔTmls) is calculated as a value obtained by subtracting the target longitudinal force Fxtllb from the target longitudinal force Fxtl of the left longitudinal wheel. In step 240, when ΔTmfl is larger than ΔTmrl, the target front / rear force Fxtfl of the left front wheel is set to the target front / rear force Fxtllb, and the target front / rear force Fxtrl of the left rear wheel is set to the target front / rear force Fxtlls. Conversely, when ΔTmfl is smaller than ΔTmrl, the target longitudinal force Fxtfl of the left front wheel is set to the target longitudinal force Fxtlls, and the target longitudinal force Fxtrl of the left rear wheel is set to the target longitudinal force Fxtllb. Is done.

  Next, the routine for calculating the target front / rear force Fxtfr for the right front wheel and the target front / rear force Fxtrr for the right rear wheel, which is executed in step 300, will be described with reference to the flowchart shown in FIG. Steps 310 to 440 are executed for the right front and rear wheels in the same manner as steps 110 to 240 described above.

  First, in step 310, it is determined whether or not the temperature Tmfr of the motor generator 12FR for the right front wheel is lower than the ideal temperature Tmt and the temperature Tmrr of the motor generator 12RR for the right rear wheel is lower than the ideal temperature Tmt. If a negative determination is made, the process proceeds to step 360. If an affirmative determination is made, the process proceeds to step 320.

  In step 320, a deviation ΔTmrmin between the ideal temperature Tmt and the lower one of the temperatures Tmfr and Tmrr is calculated, and in step 330, the temperature of the motor generator having the lower temperature rises and becomes ideal. Based on the target longitudinal force Fxtr and temperature deviation ΔTmrmin of the right front wheel, the target longitudinal force Fxtrmin of the wheel with the lower motor generator temperature is based on the proportional, integral, and differential terms of the temperature deviation ΔTmrmin so as to approach the temperature Tmt. Is calculated by the PID compensation calculation.

  In step 340, the target longitudinal force Fxtrmax of the wheel having the higher temperature is calculated by subtracting the target longitudinal force Fxtrmin from the target longitudinal force Fxtr of the right front / rear wheel, and in step 350, Tmfr <Tmrr. Sometimes the target longitudinal force Fxtfr of the right front wheel is set to the target longitudinal force Fxtrmin and the target longitudinal force Fxtrr of the right rear wheel is set to the target longitudinal force Fxtrmax. Conversely, when Tmfr> Tmrr, the target longitudinal force of the right front wheel Fxtfr is set to the target longitudinal force Fxtrmax, and the target longitudinal force Fxtrr of the right rear wheel is set to the target longitudinal force Fxtrmin. When Tmfr = Tmrr, the target longitudinal force Fxtfr for the right front wheel and the target longitudinal force Fxtrr for the right rear wheel are both set to Fxrt / 2.

  In step 360, it is determined whether or not the temperature Tmfr of the motor generator 12FR for the right front wheel is higher than the ideal temperature Tmt and the temperature Tmrr of the motor generator 12RR for the right rear wheel is higher than the ideal temperature Tmt. If a negative determination is made, the process proceeds to step 410. If an affirmative determination is made, the process proceeds to step 370.

  In step 370, the difference ΔTmrmax between the ideal temperature Tmt and the higher one of the temperatures Tmfr and Tmrr is calculated, and in step 380, the temperature of the motor generator with the higher temperature is decreased and the ideal temperature is decreased. Based on the target longitudinal force Fxtr and temperature deviation ΔTmrmax of the right front and rear wheels, the target longitudinal force Fxtrmax of the wheel with the higher motor generator temperature is determined from the proportional, integral, and differential terms of the temperature deviation ΔTmrmax so as to approach the temperature Tmt. Is calculated by the PID compensation calculation.

  In step 390, the target longitudinal force Fxtrmin of the lower temperature wheel is calculated by subtracting the target longitudinal force Fxtrmax from the target longitudinal force Fxtr of the right front wheel, and in step 400, Tmfr> Tmrr. Sometimes the target longitudinal force Fxtfr of the right front wheel is set to the target longitudinal force Fxtrmax and the target longitudinal force Fxtrr of the right rear wheel is set to the target longitudinal force Fxtrmin. Conversely, when Tmfr <Tmrr, the target longitudinal force of the right front wheel Fxtfr is set to the target longitudinal force Fxtrmin, and the target longitudinal force Fxtrr of the right rear wheel is set to the target longitudinal force Fxtrmax. When Tmfr = Tmrr, the target longitudinal force Fxtfr for the right front wheel and the target longitudinal force Fxtrr for the right rear wheel are both set to Fxrt / 2.

  In step 410, the deviation ΔTmfr between the ideal temperature Tmt and the temperature Tmfr and the deviation ΔTmrr between the ideal temperature Tmt and the temperature Tmrr are calculated. In step 420, the larger one of the deviations ΔTmfr and ΔTmrr (ΔTmrb ), The target longitudinal force Fxtrrb of the wheel is a proportional term of the temperature deviation ΔTmrb based on the target longitudinal force Fxtr of the right front wheel and the larger temperature deviation ΔTmrb so that the motor generator temperature approaches the ideal temperature Tmt. , An integral term, and a differential term.

  In step 430, the target longitudinal force Fxtrrs of the smaller one of the temperature deviations ΔTmfr and ΔTmrr (ΔTmrs) is calculated by subtracting the target longitudinal force Fxtrrb from the target longitudinal force Fxtr of the right front wheel. In step 440, when ΔTmfr is larger than ΔTmrr, the target front / rear force Fxtfr of the right front wheel is set to the target front / rear force Fxtrrb, and the target front / rear force Fxtrr of the right rear wheel is set to the target front / rear force Fxtrrs. Conversely, when ΔTmfr is smaller than ΔTmrr, the target front / rear force Fxtfr of the right front wheel is set as the target front / rear force Fxtrrs, and the target front / rear force Fxtrr of the right rear wheel is set as the target front / rear force Fxtrrb. Is done.

  Thus, according to the illustrated embodiment 1, the target longitudinal force Fxt of the vehicle is calculated based on the accelerator opening φ and the master cylinder pressure Pm in step 20, and the target longitudinal force Fxt of the vehicle is determined as the driving force in step 30. In Steps 50 and 60, the target front / rear force Fxtl of the left front / rear wheel and the target front / rear force Fxtr of the right front / rear wheel are calculated based on the steering angle θ, the vehicle speed V, and the like.

  In step 100, the actual motor generator of the larger one of the deviations between the actual temperatures Tmfl and Tmrl and the ideal temperature Tmt of the motor generator for the two motor generators 12FL and 12RL for the left front and rear wheels is larger. Based on the target longitudinal force Fxtl of the left front and rear wheels and the larger temperature deviation, the target longitudinal force Fxtfl of the left front wheel and the target longitudinal force Fxtrl of the left rear wheel are calculated so that the temperature approaches the ideal temperature Tmt of the motor generator. The

  In step 300, the actual motor of the motor generator having the larger one of the deviations between the actual temperatures Tmfr and Tmrr and the ideal temperature Tmt of the motor generator for the two motor generators 12FR and 12RR of the right front and rear wheels. Based on the target longitudinal force Fxtr of the left front and rear wheels and the larger temperature deviation, the target longitudinal force Fxtfr of the right front wheel and the target longitudinal force Fxtrr of the right rear wheel are calculated so that the temperature approaches the ideal temperature Tmt of the motor generator. The

  Further, in step 500, the target driving torque Txti of each wheel is calculated based on the target longitudinal force Fxti calculated in steps 100 and 300. In step 510, the driving torque Txi of each wheel corresponds. The motor generators 12FL to 12RR are controlled so as to achieve the target drive torque Txti.

  Therefore, according to Example 1 shown in the drawing, the motor generator having the larger one of the deviations between the actual temperatures Tmfl and Tmrl and the ideal temperature Tmt of the motor generator for the two motor generators 12FL and 12RL of the left front and rear wheels. The output of the motor generators 12FL and 12RL for the left front and rear wheels can be controlled so that the actual temperature of the motor approaches the ideal temperature Tmt of the motor generator, and the two motor generators 12FR and 12RR for the right front and rear wheels can be controlled. Of the right front and rear wheels so that the actual temperature of the motor generator having the larger of the deviations between the actual temperatures Tmfr and Tmrr and the ideal temperature Tmt of the motor generator approaches the ideal temperature Tmt of the motor generator. The output of the motor generators 12FR and 12RR can be controlled, thereby reliably improving the power efficiency of the entire vehicle without changing the magnitude of the braking / driving force of the entire vehicle and the left / right distribution of the braking / driving force. Can Kill.

  For example, FIG. 6 shows the implementation in the situation where the temperatures Tmfl and Tmrr of the motor generators of the left front wheel and the right rear wheel are higher than the ideal temperature Tmt in the situation where the same driving force should be applied to the four wheels. FIG. 6 is an explanatory diagram showing an operation of Example 1.

Fxtafl, Fxtafr, Fxtarl, Fxtarr are the target longitudinal forces of the left and right front wheels and the left and right rear wheels, respectively, based on the target longitudinal force Fxt of the vehicle. As shown in FIG. 6, the target longitudinal force of the left front wheel and the right rear wheel is reduced and the target longitudinal force of the right front wheel and the left rear wheel is increased as shown in FIG. The following formulas 1 to 3 are established between the target longitudinal force Fxti of the front wheels and the left and right rear wheels and other target longitudinal forces.
Fxtfl + Fxtrl = Fxtafl + Fxtarl = Fxtl (1)
Fxtfr + Fxtrr = Fxtafr + Fxtarr = Fxtr (2)
Fxtfl + Fxtrl + Fxtfr + Fxtrr
= Fxtafl + Fxtarl + Fxtafr + Fxtarr
= Fxt (3)

  FIG. 5 is a flowchart showing a braking / driving force control routine in Embodiment 2 of the driving force control apparatus for an electric vehicle according to the present invention. In FIG. 5, the same step number as that shown in FIG. 2 is assigned to the same step as that shown in FIG.

  In this second embodiment, steps 10, 100, 300, 500 and 510 are executed in the same manner as in the first embodiment described above. The target longitudinal force Fxt of the vehicle is calculated based on φ and the master cylinder pressure Pm in a manner known in the art, and based on the target longitudinal force Fxt, the steering angle θ, the vehicle speed V, and the like. Then, the target longitudinal force Fxtl of the left wheel and the target longitudinal force Fxtr of the right wheel are calculated in a known manner. The target longitudinal force Fxtl or Fxtr may be calculated as a braking force (negative value) depending on the steering angle θ, the vehicle speed V, etc., even if the target longitudinal force Fxt of the vehicle is a driving force (positive value).

  In step 80, it is determined whether or not the target longitudinal force Fxtl of the left wheel is a negative value and is a braking force. If a negative determination is made, the process proceeds to step 100. At 90, a signal indicating the target front / rear force Fxtl of the left wheel and a control command signal for the braking force are output to the braking force control electronic control device 28. The braking force of the left front and rear wheels is controlled based on the target front / rear force Fxtl in a known manner.

  When step 100 is completed, it is determined in step 250 whether the target front / rear force Fxtr of the right wheel is a negative value and is a braking force. If a negative determination is made, the process proceeds to step 300, where affirmative When the determination is made, in step 260, a signal indicating the target front / rear force Fxtr of the right wheel and a control command signal for the braking force are output to the braking force control electronic control unit 28, whereby the braking force control electronic control is performed. The device 28 controls the braking force of the right front and rear wheels based on the target longitudinal force Fxtr in a manner known in the art.

  Thus, according to the illustrated second embodiment, as in the first embodiment, the deviation between the actual temperature of the motor generator and the ideal temperature Tmt is determined for both the front left and right wheels and the front left and right wheels. The output of the motor generator with the larger temperature deviation can be controlled so that the actual temperature of the motor generator with the larger one approaches the ideal temperature Tmt of the motor generator. The power efficiency of the entire vehicle can be reliably improved without changing the magnitude of the braking / driving force of the entire vehicle and the left / right distribution of the braking / driving force.

  In particular, according to the illustrated embodiment 2, in step 70, the target longitudinal force Fxt of the vehicle is calculated based on the accelerator opening φ and the master cylinder pressure Pm, and the target longitudinal force Fxt, steering angle θ, vehicle speed V is calculated. Based on the above, the left and right target longitudinal force Fxtl and the right and right target longitudinal force Fxtr are calculated. In steps 80 and 250, the left and right wheel target longitudinal and forward force Fxtl and Fxtr are the driving forces, respectively. When the determination is made, since steps 100 and 300 are executed, even if the target longitudinal force Fxt of the entire vehicle is a driving force, the target longitudinal force Fxtl of the left wheel or the target longitudinal force Fxtr of the right wheel is calculated as a braking force. Also in the case of a vehicle, the above-described effects can be obtained when the target longitudinal force Fxtl for the left wheel or the target longitudinal force Fxtr for the right wheel is a driving force.

  According to the first and second embodiments described above, when a negative determination is made in steps 110 and 160 or steps 310 and 360, that is, the temperature of one of the front and rear motor generators is higher than the ideal temperature. When the temperature of the other motor generator of the front and rear wheels is lower than the ideal temperature, the output of the motor generator of the front and rear wheels is adjusted so that the temperature of the motor generator with the larger temperature deviation approaches the ideal temperature Tmt. Therefore, when the temperature of one motor generator of the front and rear wheels is higher than the ideal temperature and the temperature of the other motor generator of the front and rear wheels is lower than the ideal temperature, the correction control of the output of the motor generator is performed. Compared with the case where it is not performed, the power efficiency of the entire vehicle can be improved with certainty.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the first and second embodiments described above, the motor generators 12FL to 12RR are in-wheel motors. However, the motor generator may be provided on the vehicle body side, and the motor generator as a drive source of each wheel. May not perform regenerative braking.

  In the first and second embodiments described above, motor generators 12FL to 12RR are provided on each wheel, and the driving force of the corresponding motor generator is individually applied to each wheel. However, the present invention may be applied to a vehicle having a front-wheel motor generator that applies driving force to the left and right front wheels and a rear-wheel motor generator that applies driving force to the left and right rear wheels. Of the front-wheel motor generator and the rear-wheel motor generator so as not to change the longitudinal force required for the vehicle when the temperature of one of the motor-generator and the rear-wheel motor generator is controlled to approach the ideal temperature. The other output is controlled.

  In the first and second embodiments described above, the output of the motor is controlled so that the temperature of the motor having the larger deviation between the motor temperature and the ideal temperature approaches the ideal temperature. However, when the magnitude of the temperature deviation of any of the front and rear wheels is equal to or less than the reference value, the motor output may be corrected so as not to be controlled to bring the motor temperature close to the ideal temperature.

  Although not mentioned in the first and second embodiments, when the output of the motor for bringing the temperature of the motor closer to the ideal temperature exceeds the maximum output of the motor, the output of the motor is controlled to the maximum output. The output of the other motor may be modified to be controlled to a value obtained by subtracting the maximum output from the sum of the target outputs of the motors of the two wheels.

    Although not mentioned in the first and second embodiments, when traction control or anti-skid control is performed for any of the wheels, the motor temperature is set to the ideal temperature for at least the front and rear wheels including the wheel. It may be modified so that the control of the output of the electric motor for approaching to is not performed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows Example 1 of the driving force control apparatus by this invention applied to the wheel-in-motor type four-wheel drive vehicle. It is a flowchart which shows the main routine of the braking / driving force control in Example 1 of the driving force control apparatus by this invention. 6 is a flowchart illustrating a subroutine for calculating a target front / rear force Fxtfl for the left front wheel and a target front / rear force Fxtrl for the left rear wheel in the first embodiment. 7 is a flowchart illustrating a subroutine for calculating a target front / rear force Fxtfr for the right front wheel and a target front / rear force Fxtrr for the right rear wheel in the first embodiment. It is a flowchart which shows the main routine of the braking / driving force control in Example 2 of the driving force control apparatus by this invention. FIG. 4 is an explanatory diagram showing the operation of the first embodiment in a situation where the same driving force is to be applied to the four wheels and the temperature of the motor generators of the left front wheel and the right rear wheel is higher than the ideal temperature Tmt. is there. It is explanatory drawing which shows the relationship between the temperature Tm of an electric motor, copper loss, and dragging loss, and the ideal temperature Tmt of an electric motor.

Explanation of symbols

12FL to 12RR Motor generator 14 Accelerator opening sensor 16 Electronic control device for driving force control 18 Friction braking device 24 Brake pedal 28 Electronic control device for braking force control 30FL to 30RR Temperature sensor 32 Steering angle sensor 34 Vehicle speed sensor 36, 38FL 38RR Pressure sensor

Claims (2)

  A driving force control device for an electric vehicle having at least two electric motors for applying driving force to wheels, comprising: electric motor control means for controlling the output of the electric motor; and means for detecting an actual temperature of the electric motor. The motor control means has means for determining a motor having a large deviation between the actual temperature and the ideal temperature from among the motors, with the temperature having the highest power efficiency of each motor as an ideal temperature, and the actual temperature of the motor. Is a driving force control device for an electric vehicle, which controls the output of the electric motor so as to approach the ideal temperature of the electric motor. The electric vehicle has an electric motor for applying a driving force to the corresponding wheel for each wheel, and the driving force required for the vehicle is distributed at least between the left and right wheels according to the traveling state of the vehicle, The output of the motor is controlled so that the actual temperature of the motor with the larger deviation between the actual temperature and the ideal temperature approaches the ideal temperature of the motor, and the other wheel of the left front and rear wheels The output of the motor of the other wheel is controlled so that the output of the motor has a value obtained by subtracting the output of the motor having the larger deviation from the output corresponding to the driving force distributed to the left front and rear wheels. For the two motors, the output of the motor is controlled so that the actual temperature of the motor having the larger deviation between the actual temperature and the ideal temperature approaches the ideal temperature of the motor, and the electric power of the other wheel of the right front and rear wheels is controlled. The output of the motor of the other wheel is controlled such that the output of the other wheel is a value obtained by subtracting the output of the motor with the larger deviation from the output corresponding to the driving force distributed to the right front and rear wheels. Item 2. A driving force control apparatus for an electric vehicle according to Item 1.

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