Acceleration determination method for electric vehicle, acceleration determination notification method for electric vehicle, and acceleration determination device for electric vehicle

Abstract

An acceleration determination method for an electric vehicle determines whether the electric vehicle can achieve predetermined accelerating travel on an uphill road while configured so that the torque of the motor that drives the electric vehicle is restricted when the temperature of the motor exceeds a predetermined temperature and decreases as the temperature of the motor rises above the predetermined temperature. According to the method, a gradient torque that generates a driving force of the electric vehicle balanced with the travel resistance the electric vehicle receives when traveling on an uphill road is estimated on the basis of the torque and the angular velocity of the motor, a determination torque is calculated by adding a predetermined acceleration torque for performing accelerating travel to the gradient torque, a determination temperature threshold which is the maximum temperature of the motor at which the motor can output the determination torque is calculated, and whether accelerating travel can be achieved is determined by comparing the present temperature of the motor and the determination temperature threshold.

Description

Method for determining acceleration of electric vehicle, method for notifying acceleration determination of electric vehicle, and device for determining acceleration of electric vehicle

[0001] The present invention relates to an acceleration determination method for an electric vehicle, an acceleration determination and notification method for an electric vehicle, and an acceleration determination device for an electric vehicle.

[0002] JP2010-142029A discloses a technology that detects the temperature of a motor, sets a limit torque that limits the motor output when the detected temperature exceeds a predetermined value, and sets the limit torque to become smaller as the detected temperature rises above the predetermined value, thereby protecting the motor and issuing an alarm when the torque required by the driver exceeds the limit torque.

[0003] However, for example, when the torque applied to the motor changes from a balancing torque that generates a driving force that balances the running resistance of the electric vehicle on an uphill road to a required torque for the electric vehicle to accelerate on an uphill road, it is difficult to determine in advance whether the required torque will exceed the limit torque.

[0004] Therefore, an object of the present invention is to provide an acceleration determination method for an electric vehicle, an acceleration determination notification method for an electric vehicle, and an acceleration determination device for an electric vehicle that determine whether or not acceleration is feasible before accelerating when the torque required by the driver is limited by the temperature of the motor and the electric vehicle accelerates uphill using that required torque.

[0005] According to one aspect of the present invention, there is provided an acceleration determination method for an electric vehicle that determines whether an electric vehicle can achieve a predetermined acceleration on an uphill road in a state in which the torque of the motor that drives the electric vehicle exceeds a predetermined temperature and the torque is set to decrease as the motor temperature increases above the predetermined temperature. This acceleration determination method estimates a gradient torque that causes the motor to generate a driving force of the electric vehicle that balances the running resistance encountered when the electric vehicle travels uphill, based on the torque and the angular velocity of the motor. The method calculates a threshold value for acceleration by adding the predetermined acceleration torque to the gradient torque, and calculates a threshold value for the motor temperature at which the motor can output the threshold value. The method then compares the current motor temperature with the threshold value to determine whether acceleration is possible.

[0006] FIG. 1 is a diagram showing the basic configuration of an electric vehicle to which an acceleration determination device for an electric vehicle of the first embodiment is applied. FIG. 2 is a block diagram of a motor control device including the acceleration determination device for an electric vehicle of the first embodiment. FIG. 3 is a map used by a torque limiter to calculate a first torque based on a higher-order torque command value, a motor rotation speed, and a DC voltage. FIG. 4 is a block diagram showing the configuration of a limit torque calculation unit. FIG. 5 is a block diagram showing the configuration of an acceleration determination device for an electric vehicle of the first embodiment. FIG. 6 is a block diagram showing the configuration of a gradient torque estimator. FIG. 7 is a diagram showing a model of a driving force transmission system of an electric vehicle. FIG. 8 is a truth table of a determination signal output unit of the first embodiment. FIG. 9 is a control flow for the electric vehicle of the first embodiment, including acceleration determination processing by the acceleration determination device for an electric vehicle of the first embodiment. FIG. 10 is a diagram showing the relationship between gradient torque, the maximum temperature of the motor capable of outputting gradient torque, the determination torque, and the determination temperature threshold of the motor capable of outputting the determination torque when the motor temperature is equal to or higher than a set temperature at which torque is limited. FIG. 11 is a block diagram of an acceleration determination device (determination temperature calculation unit) for an electric vehicle according to a second embodiment. FIG. 12 is a map for calculating a predicted value for calculating a predicted motor temperature after a predetermined time has elapsed since the actual motor temperature was detected. FIG. 13 is a diagram illustrating the relationship between the determination temperature, the predicted temperature, and the determination temperature threshold. FIG. 14 is a block diagram of an acceleration determination device (additional torque setting unit) for an electric vehicle according to a third embodiment. FIG. 15 is a block diagram of a vehicle mass estimator constituting the addition torque setting unit. FIG. 16 is a diagram illustrating the relationship between vehicle weight, determination torque, and the determination temperature threshold. FIG. 17 is a block diagram of an acceleration determination device (determination temperature calculation unit) for an electric vehicle according to a fourth embodiment. FIG. 18 is a time chart of a comparative example, illustrating changes in the notification when the driver repeatedly releases and operates the accelerator after receiving the acceleration impossibility notification. FIG. 19 is a time chart of the fourth embodiment, illustrating changes in the notification when the driver repeatedly releases and operates the accelerator after receiving the acceleration impossibility notification. Fig. 20 is a block diagram of an acceleration determination device for an electric vehicle according to the fifth embodiment, and Fig. 21 is a truth table of a determination signal output unit according to the fifth embodiment.Fig. 22 is a time chart of the fifth embodiment, illustrating changes in the notification when the driver repeatedly releases and operates the accelerator after receiving a notification that acceleration is not possible. Fig. 23 is a block diagram of an acceleration determination device for an electric vehicle of a sixth embodiment. Fig. 24 is a truth table of the determination signal output unit of the sixth embodiment.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] [First embodiment] Fig. 1 is a diagram showing the basic configuration of an electric vehicle to which an acceleration determination device 100 (Fig. 2) for an electric vehicle according to the first embodiment is applied. The electric vehicle according to this embodiment is configured with a vehicle control device 1, a motor control device 2, a PWM inverter 3, a motor 4, a speed reducer 5, a drive shaft 6, drive wheels 7, a battery 8, a voltage sensor 9, a current sensor 10, a resolver 11, a thermistor 12, etc.

[0009] The battery 8 discharges the driving power of the motor 4 and charges the regenerated power.

[0010] The vehicle control device 1 calculates a higher-order torque command value (T ＊ ) and outputs it to the motor control device 2.

[0011] The motor control device 2 determines the upper torque command value (T ＊ ), the current (iu, iv, iw) flowing to the motor 4 detected by a current sensor 10 or the like, the rotor position (θ) of the motor 4 detected by a resolver 11 or the like, the winding temperature (Temp) of the motor 4 (stator) detected by a thermistor 12 or the like, and the DC voltage (Vdc) that is the input to the PWM inverter 3 detected by a voltage sensor 9 or the like. ＊ ) in the motor 4, and outputs three-phase PWM duty command values ​​(Du, Dv, Dw) for implementing triangular wave comparison PWM in the PWM inverter 3.

[0012] The PWM inverter 3 compares a carrier triangular wave of a predetermined frequency with the Duty command value to generate a drive signal for a power element (IGBT), and by turning the power element ON / OFF according to the drive signal, converts the DC voltage supplied from the battery 8 into a PWM pseudo AC voltage, applies it to the motor 4, and causes current to flow.

[0013] The motor 4 generates driving force using the current supplied from the PWM inverter 3, and transmits the driving force to the drive wheels 7 via the speed reducer 5 and the drive shaft 6. When the motor 4 is rotated by the drive wheels 7 while the vehicle is running, the motor 4 generates regenerative driving force, thereby recovering the kinetic energy of the vehicle as electrical energy.

[0014] [Motor Control Device 2] Fig. 2 is a block diagram of the motor control device 2 including the acceleration determination device 100 for an electric vehicle according to the first embodiment. ＊ 4 is a block diagram showing the configuration of the limit torque calculation unit 23. The limit torque calculation unit 23 calculates the first torque (T1) based on the motor rotation speed (RPM), the motor rotation speed (RPM), and the DC voltage (Vdc).

[0015] The motor control device 2 includes a rotational speed calculation unit 21 , a torque limiter 22 , a limit torque calculation unit 23 , a torque selection unit 24 , a vibration suppression control unit 25 , a torque control unit 26 , and an acceleration determination device 100 .

[0016] The rotor position (θ) is input to the rotational speed calculation unit 21 from the resolver 11 (FIG. 1). The rotational speed calculation unit 21 generates signals relating to the rotational speed of the electric motor (mechanical angular velocity (ωm) [rad / s], electrical angular velocity (ωe) [rad / s], motor rotation speed (RPM) [rpm]) from the amount of change in the rotor position (θ) per unit time.

[0017] The torque limiter 22 receives a higher-order torque command value (T ＊ ) is input, the motor rotation speed (RPM) is input from the rotation speed calculation unit 21, and the DC voltage (Vdc) is input from the voltage sensor 9 (FIG. 1).

[0018] The torque limiter 22 is configured to limit the forward power running state of the motor 4 (first quadrant: upper torque command value (T ＊ )>0, motor rotation speed (RPM)>0), and the maximum torque line represented by the motor rotation speed (RPM) and DC voltage (Vdc) when the motor 4 is in a reverse regenerative state (second quadrant: upper torque command value (T ＊ )>0, motor rotation speed (RPM)≦0), and the maximum torque line indicated by the motor rotation speed (RPM) when the motor 4 is in a reverse powering state (third quadrant: upper torque command value (T ＊ )≦0, motor rotation speed (RPM)≦0), and the minimum torque line indicated by the motor rotation speed (RPM) when the motor 4 is in a forward regenerative state (fourth quadrant: upper torque command value (T ＊ )≦0, motor rotation speed (RPM)>0), and a map showing a minimum torque line represented by the DC voltage (Vdc).

[0019] Here, the maximum torque line in the forward powering state (first quadrant) moves in parallel away from the origin as the DC voltage (Vdc) increases, and moves in parallel away from the origin as the DC voltage (Vdc) decreases.

[0020] Similarly, the minimum torque line in the forward regenerative state (fourth quadrant) moves in parallel away from the origin as the DC voltage (Vdc) increases, and moves in parallel away from the origin as the DC voltage (Vdc) decreases.

[0021] The torque limiter 22 is a torque limiter that limits the upper torque command value (T ＊ ) (>0), DC voltage (Vdc), and motor rotation speed (RPM) (>0) are input, the upper torque command value (T ＊ ) and the rotation speed (RPM) of motor 4 is located outside the area surrounded by the rotation speed axis (>0), torque axis (>0), and the maximum torque line of the first quadrant, a torque that is the same rotation speed (RPM) as the input rotation speed (RPM) and is at an operating point that overlaps with the maximum torque line is output as the first torque (T1).

[0022] The torque limiter 22 is a torque limiter that limits the upper torque command value (T ＊) (>0), DC voltage (Vdc), and motor rotation speed (RPM) (≦0) are input, the upper torque command value (T ＊ ) and the rotation speed (RPM) of motor 4 is located outside the area surrounded by the rotation speed axis (≦0), torque axis (>0), and the maximum torque line of the second quadrant, a torque that is the same rotation speed (RPM) as the input rotation speed (RPM) and is at an operating point that overlaps with the maximum torque line is output as the first torque (T1).

[0023] The torque limiter 22 is a torque limiter that limits the upper torque command value (T ＊ ) (≦0), DC voltage (Vdc), and motor rotation speed (RPM) (≦0) are input, ＊ ) and the rotation speed (RPM) of motor 4 is located outside the area surrounded by the rotation speed axis (≦0), torque axis (≦0), and the minimum torque line in the third quadrant, a torque that is the same rotation speed (RPM) as the input rotation speed (RPM) and whose operating point overlaps with the minimum torque line is output as the first torque (T1).

[0024] The torque limiter 22 is a torque limiter that limits the upper torque command value (T ＊ ) (>0), DC voltage (Vdc), and motor rotation speed (RPM) (≦0) are input, the upper torque command value (T ＊ ) and the rotation speed (RPM) of motor 4 is located outside the area surrounded by the rotation speed axis (>0), torque axis (≦0), and the minimum torque line of the fourth quadrant, a torque that is the same rotation speed (RPM) as the input rotation speed (RPM) and whose operating point overlaps with the minimum torque line is output as the first torque (T1).

[0025] The torque limiter 22 is a torque limiter that limits the upper torque command value (T ＊ ) and the rotation speed (RPM) of the motor 4 is located within the area surrounded by the maximum torque line of the first quadrant, the maximum torque line of the second quadrant, the minimum torque line of the third quadrant, and the minimum torque line of the fourth quadrant, the upper torque command value (T ＊ ) is generated as a first torque (T1) as it is.

[0026] As shown in FIG. 2, the limit torque calculation unit 23 receives the motor winding temperatures (Temp_u, Temp_v, Temp_w) of the respective phases from the thermistor 12 .

[0027] As shown in FIG. 4 , the limit torque calculation unit 23 includes a temperature selection unit 231 and a limit torque map 232 .

[0028] The temperature selection unit 231 outputs the highest temperature among the motor winding temperatures of the respective phases (Temp_u, Temp_v, Temp_w) to the limit torque map 232 as the reference temperature (Temp).

[0029] The limit torque map 232 has a map showing the relationship between the limit torque (TL), which is the maximum torque that can be output by the motor 4, and the reference temperature (Temp) when the reference temperature (Temp) is higher than a predetermined set temperature (FIG. 10). When the reference temperature (Temp) (>set temperature) is input, the limit torque map 232 inputs this into the map to calculate the limit torque (TL).

[0030] As shown in FIG. 2, the torque selection unit 24 receives the first torque (T1) and the limit torque (TL), and outputs the lower torque as the second torque (T2).

[0031] The vibration suppression control unit 25 receives the second torque (T2) from the torque selection unit 24 and the mechanical angular velocity (ωm) from the rotational speed calculation unit 21 .

[0032] The vibration damping control unit 25 inputs the second torque (T2) and the mechanical angular velocity (ωm) into a vehicle model of the drive transmission system of the electric vehicle (see the gradient torque estimation unit 104 described later) to calculate the final torque (T3) that suppresses the torsional vibration of the drive shaft 6 (Figure 1).

[0033] Torque control unit 26 receives the final torque (T3) from vibration suppression control unit 25, the rotor position (θ) from resolver 11 (FIG. 1), and the electrical angular velocity (ωm) from rotational speed calculation unit 21.

[0034] The torque control unit 26 converts the current (iu, iv, iw) detected by the current sensor 10 into a rotating coordinate system to obtain a current command value (id, iq) in the rotating coordinate system obtained from the final torque (T3) by current vector control and voltage phase control. ＊ , iq ＊ ) to follow the voltage command value (vd ＊ , vq ＊ ) is generated by feedback control, and the voltage command value (vd ＊ , vq ＊ ), PWM signals (Du, Dv, Dw) are generated and output to the PWM inverter 3.

[0035] The acceleration determination device 100 receives the second torque (T2) from the torque selection unit 24, the motor winding temperatures of each phase (Temp_u, Temp_v, Temp_w) from the thermistor 12, and the mechanical angular velocity (ωm) and motor rotation speed (RPM) from the rotational speed calculation unit 21, details of which will be described later.

[0036] [Acceleration Determination Device 100] Fig. 5 is a block diagram of the acceleration determination device 100 for an electric vehicle according to the first embodiment. Fig. 6 is a block diagram showing the configuration of the gradient torque estimation unit 104. Fig. 7 is a diagram showing a model of the driving force transmission system of the electric vehicle. Fig. 8 is a truth table of the determination signal output unit 107 according to the first embodiment.

[0037] As shown in FIG. 5 , the acceleration determination device 100 includes a stop determination unit 101, a determination temperature calculation unit 102, an acceleration torque calculation unit 103, a gradient torque estimation unit 104, a determination torque calculation unit 105, a determination temperature threshold calculation unit 106, and a determination signal output unit 107.

[0038] The motor rotation speed (RPM) is input to the stop determination unit 101. When the motor rotation speed (RPM) is zero or the absolute value of the motor rotation speed (RPM) is equal to or less than a predetermined value, the stop determination unit 101 determines that the electric vehicle has stopped and outputs a stop flag (SF=YES). Furthermore, when the motor rotation speed is not zero or the absolute value of the motor rotation speed (RPM) is higher than a predetermined value, the stop determination unit 101 determines that the electric vehicle has not stopped and outputs a stop flag (SF=NO).

[0039] The motor winding temperatures of each phase (Temp_u, Temp_v, Temp_w) are input to the temperature-for-determination calculation unit 102. The temperature-for-determination calculation unit 102 outputs the highest temperature among the motor winding temperatures of each phase (Temp_u, Temp_v, Temp_w) as the temperature-for-determination (Temp_j1).

[0040] The acceleration torque calculation unit 103 outputs a torque (fixed value) corresponding to the acceleration (G) required for the electric vehicle as the acceleration torque (Ta). The acceleration torque (Ta) is preset to a torque value corresponding to the minimum acceleration (e.g., 0.05 G) required for the electric vehicle so as not to interfere with traffic.

[0041] The gradient torque estimator 104 receives the second torque (T2) from the torque selector 24 (FIG. 2) and the mechanical angular velocity (ωm) from the rotational speed calculator 21 (FIG. 2). The gradient torque estimator 104 calculates a gradient torque (Ts) that causes the motor 4 to generate a driving force (F) of the electric vehicle that is balanced with the running resistance (R) received from the uphill road while the electric vehicle is traveling on the uphill road (see the third embodiment).

[0042] As shown in FIG. 6 , the gradient torque estimating unit 104 includes a filter element 1041 , a filter element 1042 , a subtractor 1043 , a filter element 1044 , and a filter element 1045 .

[0043] The mechanical angular velocity (ωm) is input to the filter element 1041. The filter element 1041 has a function (H1(s) / Gp(s)) that uses a vehicle model (Gp(s)) of the transfer characteristics of the motor torque (Tm) and the mechanical angular velocity (ωm) and a low-pass filter (H1(s)) that is equal to or greater than the difference between the denominator time and the numerator time of the vehicle model (Gp(s)). The filter element 1041 filters the input mechanical angular velocity (ωm) using the function (H1(s) / Gp(s)) to calculate the estimated torque (Test).

[0044] The second torque (T2) is input to the filter element 1042. The filter element 1042 calculates the reference torque (Tref) by filtering the second torque (T2) using the low-pass filter (H1(s)).

[0045] A subtractor 1043 calculates the difference by subtracting the estimated torque (Test) from the reference torque (Tref).

[0046] The filter element 1044 calculates the disturbance torque (Td) by filtering the difference input from the subtractor 1043 using a filter (Hz(s)) described later.

[0047] The filter element 1045 calculates the gradient torque (Ts) by filtering the disturbance torque (Td) input from the filter element 1044 using a filter (Hs(s)) described later.

[0048] When the driving force transmission system of an electric vehicle is modeled as shown in FIG. 7, the symbols are as follows: Jm: inertia of the electric motor Jw: inertia of the driving wheels M: mass of the vehicle K Ｄ : Torsional rigidity of drivetrain K ｔ : coefficient of friction between tire and road surface N: overall gear ratio r: tire load radius ωm: mechanical angular velocity of motor Tm: motor torque T Ｄ : Torque of the driving wheels F : Force applied to the vehicle V : Vehicle speed ω ｗ : Angular velocity of the drive wheels

[0049] From FIG. 7, the following equations of motion (equations (1) to (5)) can be derived.

[0050] When the transfer characteristic (Gp(s)) from the motor torque (Tm) to the mechanical angular velocity (ωm) is calculated based on equations (1) to (5), equation (6) is obtained.

[0051] Here, each parameter in equation (6) is expressed by the following equation (7).

[0052] When examining the poles and zeros of the transfer function shown in equation (7), it can be approximated to the transfer function of equation (8), with one pole and one zero showing very close values. This is because α and β in the following equation (8) show very close values.

[0053] Therefore, by performing pole-zero cancellation (approximating α=β) in equation (8), a (second-order) / (third-order) transfer characteristic Gp(s) is formed as shown in the following equation (9).

[0054] For H1(s), it is necessary to configure a low-pass filter of an order equal to or greater than the difference between the numerator and denominator orders of Gp(s) because H1(s) / Gp(s) is a proper function (the order of the numerator is equal to or less than the order of the denominator). From equation (9), a first-order low-pass filter (time constant τ1 is approximately several tens of milliseconds depending on the torque response of the motor 4) is configured as shown in equation (10).

[0055] Here, the Hz(s) filter will be explained. Equation (9) can be rewritten as equation (11). However, each parameter in equation (11) is as shown in equation (12).

[0056] From the above, Hz(s) is given by equation (13). However, ζc>ζz.

[0057] H2(s) is a low-pass filter that removes high-frequency components (the effects of minute undulations, cracks, and steps on the road surface) other than the effect of the gradient contained in the disturbance torque (Td), and is configured as a first-order filter (time constant τ2 is approximately several hundred [ms] depending on the expected road surface) as shown in equation (14).

[0058] As shown in FIG. 5, the judgment torque calculation unit 105 calculates the judgment torque (Tj) by adding the acceleration torque (Ta) input from the acceleration torque calculation unit 103 and the gradient torque (Ts) input from the gradient torque estimation unit 104.

[0059] The judgment temperature threshold calculation unit 106 has a map similar to the limit torque map 232 of the limit torque calculation unit 23. When the judgment torque (Tj) is input, the judgment temperature threshold calculation unit 106 calculates a judgment temperature threshold (Temp_th) that is the maximum temperature of the motor 4 that can output the judgment torque (Tj).

[0060] The judgment signal output unit 107 receives the stop flag (SF) output from the stop judgment unit 101, the judgment temperature (Temp_j1) output from the judgment temperature calculation unit 102, and the judgment temperature threshold (Temp_th) output from the judgment temperature threshold calculation unit 106.

[0061] According to the truth table shown in Figure 8, when the stop flag (SF) is "NO", the judgment signal output unit 107 outputs a judgment flag (J = 0) (acceleration possible) regardless of the magnitude relationship between the judgment temperature (Temp_j1) and the judgment temperature threshold value (Temp_th).

[0062] When the stop flag (SF) is "YES" and the judgment temperature (Temp_j1) is equal to or greater than the judgment temperature threshold (Temp_th) (or higher than the judgment temperature threshold (Temp_th)), the judgment signal output unit 107 outputs a judgment flag (J=1) (acceleration is not possible) (requesting a notification to the driver that acceleration is not possible). Note that this notification is displayed, for example, on a navigation display arranged on the dashboard of the vehicle, or output as sound from a speaker.

[0063] The determination signal output unit 107 outputs a determination flag (J=0) (acceleration possible) (cancels the notification to the driver that acceleration is not possible) when the stop flag (SF) is "YES" and the determination temperature (Temp_j1) is not equal to or greater than the determination temperature threshold (Temp_th), that is, when the determination temperature (Temp_j1) is less than the determination temperature threshold (Temp_th) (or equal to or less than the determination temperature threshold (Temp_th)). These correspond to cases where, when the driver has operated the accelerator to apply a torque equivalent to the gradient torque (Ts) to the motor 4 and the electric vehicle has been stopped on an uphill road (accelerator hill hold state), it is determined in advance whether or not the electric vehicle can be accelerated by further depressing the accelerator.

[0064] Note that the determination signal output unit 107 can output a determination flag (J=1) (acceleration impossible) (requesting a notification to the driver that acceleration is impossible) when the determination temperature (Temp_j1) is equal to or greater than the determination temperature threshold (Temp_th) regardless of the stop flag (SF), and can output a determination flag (J=0) (acceleration possible) (cancelling the notification to the driver that acceleration is impossible) when the determination temperature (Temp_j1) is less than the determination temperature threshold (Temp_th). This corresponds to a case where, when the driver operates the accelerator to apply a torque equivalent to the gradient torque (Ts) to the motor 4, causing the electric vehicle to travel at a substantially constant speed uphill, it is determined in advance whether a predetermined acceleration is possible by further depressing the accelerator.

[0065] 9 is a control flow for an electric vehicle according to the first embodiment, which includes acceleration determination processing by the acceleration determination device 100 for an electric vehicle according to the first embodiment. The control flow sequentially executes input processing (steps S901-S907), torque upper limit limit processing (steps S908-S909), driver notification request processing (step S910), and motor drive control processing (steps S911-S912), which are repeated at a predetermined interval.

[0066] In step S901, the motor control device 2 (rotational speed calculation unit 21, torque control unit 26) (FIG. 2) acquires the rotor position (θ) from the resolver 11 (FIG. 1).

[0067] In step S902, the motor control device 2 (torque control unit 26) (FIG. 2) acquires the detected current values ​​(iu, iv, iw) from the current sensor 10 (FIG. 1).

[0068] In step S903, the motor control device 2 (torque limiter 22, torque control unit 26) (FIG. 2) acquires the DC voltage (Vdc) from the voltage sensor 9 (FIG. 1).

[0069] In step S904, the motor control device 2 (limit torque calculation unit 23, acceleration determination device 100) (FIG. 2) acquires the motor winding temperatures (Temp_u, Temp_v, Temp_w) of each phase from the thermistor 12 (FIG. 1).

[0070] In step S905, the motor control device 2 (torque limiter 22) (FIG. 2) receives the upper torque command value (T ＊ ) to obtain the

[0071] In step S906, the motor control device 2 (rotational speed calculation unit 21) (FIG. 2) calculates the motor rotation speed (RPM), mechanical angular velocity (ωm), and electrical angular velocity (ωe) from the rotor position (θ).

[0072] In step S907, the motor control device 2 (torque limiter 22) (FIG. 2) calculates the upper torque command value (T ＊ ), the motor rotation speed (RPM), and the DC voltage (Vdc), a first torque (T1) that the motor 4 can effectively output is calculated.

[0073] In step S908, the motor control device 2 (limit torque calculation unit 23) (FIG. 2) calculates the limit torque (TL) based on the highest motor winding temperature among the motor winding temperatures of the respective phases (Temp_u, Temp_v, Temp_w).

[0074] In step S909, the motor control device 2 (torque selection unit 24) (FIG. 2) selects the lower of the first torque (T1) and the limit torque (TL) as the second torque (T2).

[0075] In step S910, when the driving force of the electric vehicle due to accelerator operation is balanced with the force acting to move the electric vehicle downward on the uphill road, causing the electric vehicle to stop on the uphill road, the motor control device 2 (acceleration determination device 100) (FIG. 2) generates a determination signal (SF: YES or No) to notify the driver that the specified acceleration driving is not possible.

[0076] In step S911, the motor control device 2 (vibration control unit 25) (Figure 2) calculates the final torque (T3) that suppresses the torsional vibration of the drive shaft 6 (Figure 1) based on the second torque (T2) and the mechanical angular velocity (ωm).

[0077] In step S912, the motor control device 2 (torque control unit 26) (FIG. 2) generates PWM signals (Du, Dv, Dw) based on the final torque (T3), the detected current values ​​(iu, iv, iw), the rotor position (θ), and the electrical angular velocity (ωe), and outputs the PWM signals to the PWM inverter 3.

[0078] [Torque Limitation and Acceleration Running] Figure 10 is a diagram showing the relationship between the gradient torque (Ts), the maximum temperature of the motor 4 at which the gradient torque (Ts) can be output, the judgment torque (Tj), and the judgment temperature threshold (Temp_th) of the motor 4 at which the judgment torque (Tj) can be output, when the temperature of the motor 4 is equal to or higher than the set temperature at which torque is limited. As shown in Figure 10, in order to protect the motor 4 from temperature, the torque is limited when the temperature of the motor 4 exceeds a predetermined set temperature, and the torque is set to monotonically decrease as the temperature of the motor 4 increases above the set temperature.

[0079] When an electric vehicle travels uphill, a gradient running resistance is applied to the motor 4 in a direction in which the electric vehicle moves backward uphill. However, when the accelerator is operated to apply a gradient torque (Ts) to the motor 4, which generates a driving force in the motor 4 that balances the running resistance, the electric vehicle comes to a halt on the uphill road.

[0080] At this time, when the temperature of the motor 4 (temperature for determination (Temp_j1)) reaches the maximum temperature shown in FIG. 10 , the upper limit of the torque of the motor 4 is limited to the same value as the gradient torque (Ts). Therefore, even if the driver subsequently depresses the accelerator pedal further, it is difficult for the electric vehicle to accelerate. Furthermore, even if the driver is notified that acceleration is not possible when the temperature of the motor 4 reaches the maximum temperature shown in FIG. 10 , it is still difficult to accelerate thereafter, as described above.

[0081] On the other hand, in this embodiment, a judgment torque (Tj) is calculated by adding the acceleration torque (Ta) to the gradient torque (Ts) when a torque of the same magnitude as the gradient torque (Ts) is applied to the motor 4. Then, a judgment temperature threshold (Temp_th) that is the maximum temperature of the motor 4 at which the judgment torque (Tj) can be output is calculated, and based on the magnitude relationship between the temperature of the motor 4 (judgment temperature (Temp_j1)) and the judgment temperature threshold (Temp_th), it is determined whether or not acceleration driving that achieves a predetermined acceleration is possible when the driver subsequently depresses the accelerator pedal further.

[0082] For example, if the temperature of the motor 4 (temperature for judgment (Temp_j1)) is less than the judgment temperature threshold (Temp_th), it is determined that accelerated driving is possible, and if the temperature of the motor 4 (temperature for judgment (Temp_j1)) is greater than or equal to the judgment temperature threshold (Temp_th), it is determined that accelerated driving is not possible.

[0083] In the past, for example, when holding the accelerator on an uphill road, a determination was made as to whether acceleration was possible at a timing when a balancing torque could not be output to prevent the vehicle from rolling back, and a notification was given to that effect if acceleration was not possible. However, in this embodiment, the determination and notification are made at a timing before an excess torque (acceleration torque (Ta)) that allows the vehicle to run at a predetermined acceleration when resuming running from a stopped state is output, thereby reducing the inconvenience to the driver caused by not being able to produce the predetermined acceleration when starting.

[0084] [Second embodiment] Fig. 11 is a block diagram of an acceleration determination device 100 (determination temperature calculation unit 102) for an electric vehicle according to a second embodiment. Fig. 12 is a map for calculating a predicted value (ΔTemp_x) for calculating a predicted temperature (Temp_j2) of the motor 4 after a predetermined time has elapsed since the actual temperature (e.g., Temp_u) of the motor 4 was detected.

[0085] In the second embodiment, the motor 4 (and the PWM inverter 3 and battery 8) are incorporated in a circulation path (not shown) through which a refrigerant (coolant) circulates. A radiator (not shown) is disposed in the circulation path, and the coolant exchanges heat through the radiator. The motor control device 2 (determination temperature calculation unit 102) receives the coolant temperature (Temp_r).

[0086] As shown in FIG. 11, the judgment temperature calculation unit 102 includes a subtractor 1021 , a temperature selection unit 1022 , a predicted value calculation unit 1023 , and an adder 1024 .

[0087] A subtractor 1021 calculates first differences (ΔTemp_u, ΔTemp_v, ΔTemp_w) by subtracting the coolant temperature (Temp_r) from the motor winding temperatures (Temp_u, Temp_v, Temp_w) of the respective phases obtained from the thermistor 12 (FIG. 1).

[0088] The temperature selection unit 1022 outputs the component with the highest value among the first differences as a second difference (ΔTemp) between the temperature of the motor 4 and the coolant temperature (Temp_r).

[0089] The predicted value calculation unit 1023 receives the second torque (T2), the second difference (ΔTemp), and the cooling water temperature (Temp_r), and calculates a predicted value (ΔTemp_x) for calculating the predicted temperature (Temp_j2) after a predetermined time (e.g., 10 seconds) has elapsed since the actual temperature (e.g., Temp_u) of the motor 4 was detected.

[0090] When the second torque (T2) is constant, the motor 4 generates heat as the second torque (T2) continues to be output, and eventually saturates and converges. The temperature at this time is defined as the convergence temperature (Temp_c). The predicted value calculation unit 1023 has a map that shows the relationship between the convergence temperature (Temp_c) based on the second torque (T2), the coolant temperature (Temp_r), and the second difference (ΔTemp). When no torque is applied, the temperature of the motor 4 is equal to the coolant temperature (Temp_r). Therefore, the reference is set to the coolant temperature (Temp_r). By continuing to apply the second torque from that state, the temperature will eventually reach the convergence temperature (Temp_c). The second difference (ΔTemp) indicates the temperature halfway from the coolant temperature (Temp_r) to the convergence temperature (Temp_c). In other words, the convergence temperature (Temp_c) is determined by the second torque, and the second difference (ΔTemp) indicates the remaining time until the convergence temperature (Temp_c) is reached.

[0091] When the actual temperature of the motor 4 is different from the convergence temperature, the actual temperature has a first-order response of converging to the convergence temperature with a predetermined time constant. In this case, the larger the difference between the actual temperature and the convergence temperature, the larger the difference between the actual temperature and the predicted temperature. Conversely, the smaller the difference between the actual temperature and the convergence temperature, the smaller the difference between the actual temperature and the predicted temperature. When the actual temperature matches the convergence temperature, the actual temperature and the predicted temperature match.

[0092] For example, if the electric vehicle is accelerating on an uphill road before entering the accelerator hill hold state, the torque of the motor 4 during this acceleration is greater than the gradient torque (Ts), so the actual temperature (e.g., Temp_u) at the start of the accelerator hill hold state will be higher than the convergence temperature (Temp_c) for the accelerator hill hold state. Also, if the accelerator is released and the brakes are applied before the electric vehicle enters the accelerator hill hold state on an uphill road, the torque of the motor 4 during this braking operation will be smaller (zero) than the gradient torque (Ts), so the actual temperature (e.g., Temp_u) at the start of the accelerator hill hold state will be lower than the convergence temperature (Temp_c) for the accelerator hill hold state.

[0093] Therefore, as shown in Figure 12, when the second difference (ΔTemp) matches the third difference (Temp_c-Temp_r) obtained by subtracting the coolant temperature (Temp_r) from the predicted temperature (Temp_c), the predicted value (ΔTemp_x) becomes zero (ΔTemp_x = 0).

[0094] Furthermore, if the second difference (ΔTemp) is smaller than the third difference (Temp_c-Temp_r), the predicted value (ΔTemp_x) will be a positive value (Temp_x>0), and the smaller the second difference (ΔTemp) is than the third difference (Temp_c-Temp_r), the larger the predicted value (ΔTemp_x) will be.

[0095] Furthermore, if the second difference (ΔTemp) is greater than the third difference (Temp_c-Temp_r), the predicted value (ΔTemp_x) will be a negative value (Temp_x<0), and the larger the second difference (ΔTemp) is than the third difference (Temp_c-Temp_r), the larger the absolute value of the predicted value (ΔTemp_x) will be.

[0096] The map shown in Figure 12 calculates, for example, how many degrees [°C] the temperature of the motor 4 will rise (fall) to after a predetermined time has elapsed from the current temperature (cooling water temperature + 100 [°C]) when the accelerator hill hold state is maintained on an uphill road with the second torque (T2) at 200 [Nm].

[0097] As shown in Figure 11, the adder 1024 calculates the second judgment temperature (Temp_j2) by adding the predicted value (ΔTemp_x) output from the predicted value calculation unit 1023 and the coolant temperature (Temp_r), and outputs it to the judgment signal output unit 107 (Figure 5).

[0098] In addition, instead of the predicted value calculation unit 1023 and the adder 1024, a motor temperature estimation model expressed by the following equation (15) of a first-order lag time response may be used to estimate the predicted temperature after a predetermined time has elapsed since the actual temperature was detected. T: Motor temperature T ０ : Motor temperature initial value T Ｗ : Cooling water temperature τ : Time constant Rh : Thermal resistance P : Heat loss due to current flowing through motor 4

[0099] When the stop flag (SF) is "NO", the judgment signal output unit 107 (see Figure 8) outputs a judgment flag (J = 0) (acceleration possible) regardless of the magnitude relationship between the predicted temperature (Temp_j2) and the judgment temperature threshold (Temp_th).

[0100] The judgment signal output unit 107 outputs a judgment flag (J=0) (acceleration possible) when the stop flag (SF) is "YES" and the predicted temperature (Temp_j2) is not equal to or greater than the judgment temperature threshold (Temp_th), i.e., when the predicted temperature (Temp_j2) is less than the judgment temperature threshold (Temp_th) (or equal to or less than the judgment temperature threshold (Temp_th)).

[0101] When the stop flag (SF) is "YES" and the predicted temperature (Temp_j2) is equal to or greater than the judgment temperature threshold (Temp_th) (or is higher than the judgment temperature threshold (Temp_th)), the judgment signal output unit 107 outputs a judgment flag (J=1) (acceleration impossible) (requesting notification to the driver that acceleration is impossible).

[0102] The judgment signal output unit 107 outputs a judgment flag (J=0) (acceleration possible) (cancels the notification to the driver that acceleration is not possible) when the stop flag (SF) is "YES" and the predicted temperature (Temp_j2) is not equal to or greater than the judgment temperature threshold (Temp_th), i.e., when the predicted temperature (Temp_j2) is less than the judgment temperature threshold (Temp_th).

[0103] [Time chart of the second embodiment] Fig. 13 is a diagram showing the relationship between the temperature for determination (Temp_j1), the predicted temperature (Temp_j2), and the temperature threshold for determination (Temp_th). Fig. 12 shows the temperature transition when the actual temperature of the motor 4 at the start of the accelerator hill hold state is lower than the convergence temperature of the motor 4 while the accelerator hill hold state is maintained.

[0104] As shown in Figure 13, in the past, the driver was notified that acceleration was not possible at time t1 when the actual temperature of motor 4 reached the maximum temperature at which the accelerator hill hold state could be maintained (at which gradient torque (Ts) could be output), making it difficult to fully accelerate after the accelerator hill hold.

[0105] In the second embodiment, the predicted temperature (Temp_j2) is estimated based on the actual temperature at time t0, which is before time t1. That is, the predicted temperature (Temp_j2) at time t0 is the same as the actual temperature at time t0+x (<time t1), a predetermined time (x [s]) after time t0. Then, when the predicted temperature (Temp_j2) reaches the judgment temperature threshold (Temp_th) at time t0+x, the driver is notified that acceleration is not possible. This makes it possible to notify the driver that acceleration is not possible a predetermined time (x [s]) earlier than in the first embodiment, thereby ensuring time to encourage re-acceleration by operating the accelerator and reducing the inconvenience to the driver.

[0106] In the first embodiment, the temperature for determination (Temp_j1) is substantially the same as the actual temperature. Therefore, when the temperature for determination (Temp_j1) reaches the temperature threshold value for determination (Temp_th) at time t0+2x (<time t1), which is later than time t0+x in the first embodiment, the driver is notified that acceleration is not possible.

[0107] [Third embodiment] Fig. 14 is a block diagram of an acceleration determination device 100 (acceleration torque calculation unit 103) for an electric vehicle according to a third embodiment. Fig. 15 is a block diagram of a vehicle mass estimation unit 1031 constituting the acceleration torque calculation unit 103. Fig. 16 is a diagram showing the relationship between vehicle weight, determination torque, and determination temperature threshold value.

[0108] As shown in FIG. 14 , the acceleration determination device 100 (acceleration torque calculation unit 103) of the third embodiment does not output the additional torque (Ta) as a fixed value as in the first embodiment, but estimates the vehicle mass and calculates the additional torque (Ta) based on the estimated vehicle mass.

[0109] The acceleration torque calculation unit 103 includes a vehicle mass estimation unit 1031 and an acceleration torque estimation unit 1032 .

[0110] The second torque (T2), longitudinal acceleration (a), and shift position are input to the vehicle mass estimation unit 1031. Here, the longitudinal acceleration (a) is a detection value of a longitudinal acceleration sensor attached to the electric vehicle. The longitudinal acceleration sensor detects acceleration or deceleration of the electric vehicle as longitudinal acceleration, and if the road on which the electric vehicle is traveling is inclined in the longitudinal direction, the amount of inclination is detected as longitudinal acceleration. The longitudinal acceleration (a) may be obtained by communication from another controller other than the longitudinal acceleration sensor.

[0111] The shift position is input from the vehicle control device 1 via communication.

[0112] As shown in FIG. 15, in step S1501, the vehicle mass estimating unit 1031 calculates the absolute value (|a|) of the longitudinal acceleration (a).

[0113] In step S1502, the vehicle mass estimation unit 1031 calculates the absolute value (|a^|) of the previous value of the estimated longitudinal acceleration value (a^) to be calculated in step S1507 described later.

[0114] In step S1503, the vehicle mass estimation unit 1031 calculates the acceleration difference (Δa) by subtracting the absolute value (|a|) calculated in step S1501 from the absolute value (|a^|) calculated in step S1502.

[0115] In step S1504, the vehicle mass estimation unit 1031 calculates the correction mass (ΔM) by multiplying the acceleration difference (Δa) calculated in step S1503 by the mass setting gain (Km).

[0116] In step S1505, the vehicle mass estimator 1031 calculates the vehicle mass estimate (M^) by adding the correction mass (ΔM) calculated in step S1504 for each control calculation. When the driver shifts the gearshift to a predetermined position (e.g., P range), the vehicle mass estimate (M^) is initialized (returned to a preset initial value).

[0117] In step S1506, the vehicle mass estimation unit 1031 receives the second torque (T2) as an input and calculates the driving force (F) based on the transfer characteristic (GpF(s)) of the vehicle model of equation (14). Here, the transfer characteristic (GpF(s)) from the second torque (T2) to the driving force (F) is calculated as follows based on the above equations (1) to (5):

[0118] In step S1507, the vehicle mass estimating unit 1031 calculates the estimated longitudinal acceleration value (a^) by dividing the driving force (F) calculated in step S1506 by the estimated vehicle mass value (M^).

[0119] As shown in Fig. 14, the acceleration torque estimating unit 1032 receives an estimated vehicle mass value (M^). The acceleration torque estimating unit 1032 has a map that represents the relationship between the vehicle mass and the acceleration torque required for an electric vehicle of that vehicle mass to achieve a predetermined acceleration, and for example, the acceleration torque changes as a linear function with changes in vehicle mass. The acceleration torque estimating unit 1032 inputs the received estimated vehicle mass value (M^) into the map to calculate the acceleration torque (Ta).

[0120] The driving force of the vehicle can be expressed by the following equation of motion (17). M: Vehicle mass g: Gravitational acceleration V: Vehicle speed F: Driving force R: Running resistance

[0121] Since the driving force (F) depends on the vehicle mass (M), the required acceleration torque (Ta) changes depending on the vehicle mass (M). When traveling uphill, the running resistance (R) becomes gradient resistance.

[0122] Therefore, in the third embodiment, as shown in Fig. 16 , the acceleration torque (Ta) is set to increase as the vehicle mass (M) increases. As a result, the determination torque (Tj) increases and the determination temperature threshold (Temp_th) decreases as the vehicle mass (M) increases. Conversely, the acceleration torque (Ta) is set to decrease as the vehicle mass (M) decreases. As a result, the determination torque (Tj) decreases and the determination temperature threshold (Temp_th) increases as the vehicle mass (M) decreases.

[0123] In this way, in order to ensure a specified acceleration, the judgment temperature threshold (Temp_th) can be set according to the acceleration torque (Ta), which needs to be changed in accordance with changes in the vehicle mass (M), so that the driver can be notified that acceleration is not possible at a more appropriate time.

[0124] Fourth Embodiment FIG. 17 is a block diagram of an acceleration determination device 100 (determination temperature calculation unit 102) for an electric vehicle according to a fourth embodiment.

[0125] The acceleration determination device 100 (determination temperature calculation unit 102) of the fourth embodiment is obtained by adding a first latch processing unit 1025 to the determination temperature calculation unit 102 of the second embodiment.

[0126] The first latch processing unit 1025 receives the stop flag (SF) and the second torque (T2).

[0127] The first latch processing unit 1025 outputs the second torque (T2) input from the torque selection unit 24 (FIG. 2) as is to the predicted value calculation unit 1023, but latches (holds) the second torque (T2) when the stop flag (SF) switches from “NO” to “YES” and outputs the latched second torque (T2) to the predicted value calculation unit 1023.

[0128] When the stop flag (SF) switches from "YES" to "NO", the first latch processing unit 1025 releases the latch and outputs the second torque (T2) input from the torque selection unit 24 (Figure 2) as is to the predicted value calculation unit 1023.

[0129] [Time charts of a comparative example and the fourth embodiment] Fig. 18 is a time chart of a comparative example, which is a diagram for explaining changes in the notification when the driver repeatedly releases and operates the accelerator after receiving the acceleration impossible notification. Fig. 19 is a time chart of the fourth embodiment, which is a diagram for explaining changes in the notification when the driver repeatedly releases and operates the accelerator after receiving the acceleration impossible notification.

[0130] The time charts of the comparative example and the fourth embodiment show a state in which an electric vehicle is maintained at a stop on an uphill road by accelerator hill hold, and at time t0 the predicted temperature (Temp_j2) reaches the judgment temperature threshold (Temp_th), after which the accelerator operation is released and the brake operation is performed (times t1, t3, and t5), and a state in which the brake operation is released at time t2 and the accelerator operation (accelerator hill hold) is resumed (times t2 and t4), which are repeated alternately.

[0131] The comparative example does not have the first latch processing unit 1025 of the fourth embodiment, and is configured so that the second torque (T2) output from the torque selection unit 24 (Figure 2) is input directly to the predicted value calculation unit 1023.

[0132] In the comparative example and the fourth embodiment, the convergence temperature (Temp_c) of the motor 4 when the accelerator hill hold is being performed is higher than the judgment temperature threshold (Temp_th), and the convergence temperature (Temp_th) when the accelerator operation (accelerator hill hold) is released becomes the coolant temperature (Temp_r).

[0133] At time t0 in the comparative example and the fourth embodiment, the predicted temperature (Temp_j2) reaches the judgment temperature threshold (Temp_th), causing the judgment signal (J) to change from "0" to "1," and the notification that acceleration driving is not possible switches from "OFF" to "ON."

[0134] Before time t1 in the comparative example and the fourth embodiment, accelerator hill-hold is performed, so the second torque (T2) becomes the gradient torque (Ts) (torque that causes the motor 4 to generate a driving force (F) of the electric vehicle that is balanced with the running resistance (R)). Therefore, the gradient torque (Ts) output by the gradient torque estimator 104 (FIG. 5) becomes equivalent to the running resistance (R), and the judgment torque (Tj) becomes a value obtained by adding the acceleration torque (Ta) to the equivalent of the running resistance (R).

[0135] In the comparative example and the fourth embodiment, when the accelerator operation is released (the brake operation is performed) at times t1, t3, and t5, the second torque (T2) becomes zero, so the gradient torque (Ts) output by the gradient torque estimator 104 (FIG. 5) becomes zero, and the determination torque (Tj) consists of only the acceleration torque (Ta). Furthermore, because the second torque (T2) becomes zero, the determination temperature threshold (Temp_th) becomes higher than the value before time t1.

[0136] At times t2 and t4 in the comparative example and the fourth embodiment, when accelerator operation (accelerator hill hold) is resumed, the second torque (T2), the gradient torque (Ts), and the judgment torque (Tj) return to the same state as before time t1.

[0137] The actual temperature of the motor 4 (temperature for determination (Temp_j1)) rises while the accelerator is being operated (accelerator hill hold) and falls when the accelerator is released, but the temperature transition is the same in the comparative example and the fourth embodiment. Note that the actual temperature of the motor 4 transitions in a region closer to the convergence temperature when the second torque (Ts) is set to the torque (gradient torque) when the accelerator hill hold is being performed than to the convergence temperature (coolant temperature (Temp_r)) when the second torque (T2) is zero, and therefore the rate at which the actual temperature falls is faster than the rate at which it rises.

[0138] At time t1 in the comparative example, when the accelerator operation is released, the predicted value (ΔTemp_x) calculated by the predicted value calculation unit 1023 ( FIG. 17 ) decreases in a step function manner. Therefore, immediately after time t1, the predicted temperature (Temp_j2) has the actual temperature at time t1 (determination temperature (Temp_j1)) as its initial value, and becomes the temperature of the motor 4 after a predetermined time has elapsed from time t1 when the second torque (T2) is zero. Therefore, the predicted temperature (Temp_j2) decreases in a step function manner at time t1 and becomes lower than the determination temperature threshold (Temp_th). Therefore, the determination signal (J) changes from "1" to "0," and the notification that acceleration driving is not possible switches from "ON" to "OFF."

[0139] When the driver perceives the notification and resumes accelerator operation (accelerator hill hold) at time t2 after time t1, the predicted value (ΔTemp_x) calculated by the predicted value calculation unit 1023 ( FIG. 17 ) rises in a step function manner. Therefore, the predicted temperature (Temp_j2) is the temperature of the motor 4 after a predetermined time has elapsed since time t2, with the actual temperature at time t2 (determination temperature (Temp_j1)) set as its initial value and the second torque (T2) set to a value for executing accelerator hill hold (equivalent to gradient torque (Ts) = running resistance (R)). Therefore, the predicted temperature (Temp_j2) rises in a step function manner at time t2 and becomes higher than the determination temperature threshold (Temp_th). Therefore, the determination signal (J) changes from "0" to "1," and the notification that acceleration driving is not possible switches from "OFF" to "ON."

[0140] In this way, in the comparative example, until the predicted temperature (Temp_j2) when accelerator hill hold is performed becomes lower than the judgment temperature threshold (Temp_th), the notification alternates between switching from "OFF" to "ON" when the driver operates the accelerator and switching from "ON" to "OFF" when the accelerator operation is released, which causes discomfort to the driver.

[0141] On the other hand, at time t1 in the fourth embodiment, when the accelerator operation is released, the stop flag (SF) switches from "OFF" to "ON", and the first latch processing unit 1025 latches the second torque (T2) (corresponding to the gradient torque (Ts)) when the stop flag (SF) switches from "OFF" to "ON". Therefore, a step function-like change does not occur in the predicted value (ΔTemp_x) calculated by the predicted value calculation unit 1023 ( FIG. 17 ).

[0142] Furthermore, the second difference (ΔTemp) input to the predicted value calculation unit 1023 is substantially the actual temperature (current temperature) of the motor 4, but decreases monotonically as the second torque (T2) becomes zero. Therefore, the predicted value (ΔTemp_x) output by the predicted value calculation unit 1023 also decreases monotonically.

[0143] As described above, immediately after time t1 (similarly immediately after time t3 and immediately after time t5), the predicted temperature (Temp_j2) in the fourth embodiment does not decrease stepwise at time t1, but instead uses the predicted temperature (Temp_j2) immediately before time t1 as its initial value and monotonically decreases in accordance with the actual temperature (determination temperature (Temp_j1)), which monotonically decreases. Therefore, as long as the stop flag (SF) remains "ON" (even if the driver repeatedly outputs and stops the second torque (T2) (= gradient torque (Ts) = running resistance (R)) for executing accelerator hill hold), the notification remains "ON" and does not become "OFF" until the predicted temperature (Temp_j2) becomes lower than the determination temperature threshold (Temp_th).

[0144] If accelerator operation (accelerator hill hold) is resumed at time t2 (time t4), the stop flag (SF) remains "YES" so that no step function change occurs in the predicted temperature (Temp_j2). Furthermore, when the accelerator is operated, the second torque (T2) becomes the gradient torque (Ts) (torque that causes the motor 4 to generate a driving force (R) that balances the running resistance (R)), so the actual temperature (temperature for determination (Temp_j1)) increases monotonically, but the predicted temperature (Temp_j2) also increases monotonically in accordance with the change in the actual temperature (temperature for determination (Temp_j1)).

[0145] 19 , for example, at time t6 after time t5, the predicted temperature (Temp_j2) becomes lower than the judgment temperature threshold (Temp_th), and the notification is turned "OFF." Although not shown in the figure, when the accelerator is subsequently operated to accelerate uphill and the electric vehicle starts traveling, the stop flag (SF) becomes "NO," and the latch of the first latch processing unit 1025 is released.

[0146] [Fifth embodiment] Fig. 20 is a block diagram of an acceleration determination device 100 for an electric vehicle according to a fifth embodiment. Fig. 21 is a truth table of a determination signal output unit 107 according to the fifth embodiment.

[0147] The acceleration determination device 100 of the fifth embodiment is obtained by adding a second latch processing unit 108 and a subtractor 109 to the acceleration determination device 100 (determination temperature calculation unit 102) of the second embodiment.

[0148] The second latch processing unit 108 receives the stop flag (SF) output from the stop determination unit 101 and the determination temperature threshold value (Temp_th) output from the determination temperature threshold value calculation unit 106 .

[0149] The second latch processing unit 108 normally outputs the input judgment temperature threshold (Temp_th) as is to the judgment signal output unit 107 as the first judgment temperature threshold (Temp_th1), but latches (holds) the judgment temperature threshold (Temp_th) when the stop flag (SF) changes from "NO" to "YES" and outputs the latched judgment temperature threshold (Temp_th) to the judgment signal output unit 107 as the first judgment threshold (Temp_th1).

[0150] When the stop flag (SF) switches from "YES" to "NO", the second latch processing unit 108 unlatches the judgment temperature threshold (Temp_th) and outputs the input judgment temperature threshold (Temp_th) as is to the judgment signal output unit 107 as the first judgment temperature threshold (Temp_th1).

[0151] Subtractor 109 calculates a second determination temperature threshold (Temp_th2) by subtracting a predetermined temperature difference set value (ΔT_h) from the first determination temperature threshold (Temp_th1), and outputs this to determination signal output unit 107. Here, temperature difference set value (ΔT_h) is set to a value required to maintain the notification "ON" regardless of the step function change (FIGS. 18 and 22) in the predicted temperature (Temp_j2) associated with the driver's accelerator operation / release.

[0152] The judgment signal output unit 107 receives the prediction signal (Temp_j2), the first judgment temperature threshold (Temp_th1), and the second judgment temperature threshold (Temp_th2).

[0153] As shown in Figure 21, when the stop flag (SF) is "NO", the judgment signal output unit 107 outputs a judgment signal (J = 0) regardless of the magnitude relationship between the prediction signal (Temp_j2) and the first judgment temperature threshold (Temp_th1) and the second judgment temperature threshold (Temp_th2).

[0154] The determination signal output unit 107 outputs a determination signal (J=1) when the stop flag (SF) is "YES" and the predicted temperature (Temp_j2) is equal to or higher than the first determination temperature threshold (Temp_th1).

[0155] When the stop flag (SF) is "YES" and the predicted temperature (Temp_th) is equal to or greater than the second judgment temperature threshold (Temp_th2) and lower than the first judgment temperature threshold (Temp_th1), the judgment signal output unit 107 maintains the judgment signal (J) at the previous value (J = TPV).

[0156] The determination signal output unit 107 outputs a determination signal (J=0) when the stop flag (SF) is "YES" and the predicted temperature (Temp_j2) is lower than the second determination temperature threshold (Temp_th2).

[0157] [Time Chart of Fifth Embodiment] FIG. 22 is a time chart of the fifth embodiment, which is a diagram for explaining changes in the notification when the driver repeatedly releases and operates the accelerator after receiving a notification that acceleration driving is impossible.

[0158] In the fifth embodiment, the time charts of the second torque (T2), the judgment torque (Tj), the gradient torque (Ts), the first judgment temperature threshold (Temp_th1) (= the judgment temperature threshold (Temp_th)), the actual temperature (the judgment temperature (Temp_j1)), and the predicted temperature (Temp_J2) are the same as those in the comparative example of Figure 18.

[0159] In the fifth embodiment, when the predicted temperature (Temp_j2) reaches the first judgment temperature threshold (Temp_th1) at time t0, the judgment signal output unit 107 switches the notification that acceleration driving is not possible from "OFF" (J=0) to "ON" (J=1).

[0160] In addition, the second latch processing unit 108 (Figure 20) latches (holds) the first judgment temperature threshold (Temp_th1) at time t0, and the subtractor 109 calculates the second judgment temperature threshold (Temp_th2) based on the latched first judgment temperature threshold (Temp_th1).

[0161] The judgment signal output unit 107 outputs a judgment signal (J) in accordance with the truth table of FIG. 21, but since the second judgment temperature threshold (Temp_th2) remains lower than the predicted temperature (Temp_j2) until time t7, which is later than time t5, the judgment signal (J=1) is maintained regardless of whether the driver operates / releases the accelerator.

[0162] Then, after time t7, the determination signal output unit 107 switches the notification that acceleration is not possible from "ON" (J=1) to "OFF" (J=0). Furthermore, when the electric vehicle starts to travel after time t7, the stop flag (SF) switches from "YES" to "NO", and the second latch processing unit 108 releases the latch on the first determination temperature threshold (Temp_th1).

[0163] Sixth Embodiment Fig. 23 is a block diagram of an acceleration determination device 100 for an electric vehicle according to a sixth embodiment. Fig. 24 is a truth table of a determination signal output unit 107 according to the sixth embodiment.

[0164] The acceleration judgment device 100 of the sixth embodiment is configured by applying the judgment temperature calculation unit 102 (output of which is the first predicted temperature (Temp_j21)) of the second embodiment (FIG. 11) to the configuration of the first embodiment, and further adding the judgment temperature calculation unit 102 (output of which is the second predicted temperature (Temp_j22)) of the fourth embodiment (FIG. 17) and the second latch processing unit 108 and subtractor 109 of the fifth embodiment (FIG. 20).

[0165] The judgment signal output unit 107 receives as input the first predicted temperature (Temp_j1) from the judgment temperature calculation unit 102 of the second embodiment (FIG. 11), the second predicted temperature (Temp_j2) from the judgment temperature calculation unit 102 of the fourth embodiment (FIG. 17), the judgment temperature threshold (Temp_th) from the judgment temperature threshold calculation unit 106, the first judgment temperature threshold (Temp_th1) from the second latch processing unit 108, and the second judgment temperature threshold (Temp_th2) from the subtractor 109.

[0166] The determination signal output unit 107 outputs "ON" (J=1) or "OFF" (J=0) as a notification that acceleration is not possible according to the truth table shown in Fig. 24. The determination signal output unit 107 performs, in parallel, a step of calculating a flag (J1) according to the truth table of Fig. 24(A) and a step of calculating a flag (J2) according to the truth table of Fig. 24(B).

[0167] (A) in Fig. 24 is substantially the same as the truth table in Fig. 8, except that "J" in Fig. 8 is replaced with "J1." Also, the first predicted temperature (Temp_th1) is the same as the predicted temperature (Temp_th) shown in Fig. 19. Therefore, (A) in Fig. 24 is substantially the same as the output procedure of the determination signal (J) in the fourth embodiment.

[0168] (B) of Figure 24 is substantially the same as the truth table of Figure 21, except that "J" in Figure 21 is replaced with "J2." Also, the second predicted temperature (Temp_th2) is the same as the predicted temperature (Temp_th) shown in Figure 22. Therefore, (B) of Figure 24 is substantially the same as the output procedure of the determination signal (J) in the fifth embodiment.

[0169] As shown in the truth table of (C) of Figure 24, the judgment signal output unit 107 outputs a notification that acceleration driving is not possible as "ON" (J = 1) when "J1 = 1" and / or "J2 = 1", and outputs the notification as "OFF" (J = 0) in all other cases.

[0170] In the sixth embodiment, the flag (J1) and the flag (J2) are calculated in parallel, and when at least one of them becomes "1", a judgment signal (J=1) is output, thereby improving the judgment accuracy (notification accuracy).

[0171] [Effects of this embodiment] The acceleration determination method of this embodiment is a method for determining whether or not the electric vehicle can achieve a predetermined acceleration running on an uphill road in a state in which the torque of the motor 4 that drives the electric vehicle is limited when the temperature of the motor 4 exceeds a predetermined temperature (set temperature) and the torque decreases as the temperature of the motor 4 becomes higher than the predetermined temperature (set temperature), and the method determines the running resistance that the electric vehicle experiences when running on an uphill road based on the torque (second torque (T2)) and the angular velocity (mechanical angular velocity (ωm)) of the motor 4. The gradient torque (Ts) that causes the motor 4 to generate a driving force (F) of the electric vehicle that balances the resistance (R) is estimated, a predetermined acceleration torque (Ta) for accelerating is added to the gradient torque (Ts) to calculate a judgment torque (Tj), a judgment temperature threshold (Temp_th) that is the maximum temperature of the motor 4 at which the motor 4 can output the judgment torque (Tj), and the current temperature of the motor 4 (judgment temperature (Temp_j1)) is compared with the judgment temperature threshold (Temp_th) to judge whether or not accelerated driving is possible.

[0172] In the past, for example, when holding the accelerator on an uphill road, the determination of whether acceleration was possible was made at a timing when the vehicle could not output a balanced torque to prevent the vehicle from rolling back. However, with the above method, the determination is made at a timing before the output of the surplus torque (acceleration torque (Ta)) that allows the vehicle to run at a predetermined acceleration when resuming driving from a stopped state, thereby reducing the inconvenience to the driver caused by not being able to produce the predetermined acceleration when starting.

[0173] In this embodiment, a predicted temperature (Temp_j2) which will be the temperature of the motor 4 after a predetermined time (e.g., 10 c) has elapsed since the current temperature (ΔTemp, FIG. 11) was detected is calculated based on the current temperature (ΔTemp, FIG. 11) and the gradient torque (second torque (T2) during accelerator hill hold), and the predicted temperature (Temp_j2) is compared with a judgment temperature threshold (Temp_th) to determine whether accelerated driving is possible.

[0174] By using the above method, the driver can be notified that acceleration is not possible a predetermined time in advance compared to when the current temperature (temperature for judgment (Temp_j1)) is compared with the judgment temperature threshold (Temp_th), which ensures time to encourage re-acceleration by operating the accelerator, thereby reducing the inconvenience to the driver.

[0175] In this embodiment, the mass of the electric vehicle (vehicle mass (M)) is estimated, and the acceleration torque (Ta) is set to increase as the mass (vehicle mass (M)) increases.

[0176] By using the above method, the judgment temperature threshold (Temp_th) can be set according to the acceleration torque (Ta), which needs to be changed in accordance with changes in the vehicle mass (M) in order to ensure the specified acceleration driving, so that the driver can be notified that acceleration driving is not possible at a more appropriate time.

[0177] The acceleration determination and notification method for an electric vehicle of this embodiment is an acceleration determination and notification method for an electric vehicle that uses an acceleration determination method for an electric vehicle, and when it is determined that accelerated driving is not feasible, a determination signal (J = 1) indicating this impossibility is notified to the outside.

[0178] In the past, for example, when holding the accelerator on an uphill road, a determination was made as to whether acceleration was possible at a timing when it was not possible to output a balanced torque to prevent the vehicle from rolling back, and if acceleration was not possible, a notification was given to that effect. However, with the above method, the determination and notification are made at a timing before the output of a surplus torque (acceleration torque (Ta)) that allows the vehicle to run at a predetermined acceleration when resuming driving from a stopped state, so the inconvenience to the driver caused by not being able to produce the predetermined acceleration when starting can be reduced.

[0179] The acceleration determination and notification method for an electric vehicle of this embodiment is an acceleration determination and notification method for an electric vehicle that uses an acceleration determination method for an electric vehicle, and when it is determined that acceleration driving is not feasible, a determination signal (J=1) indicating this impossibility is notified to the outside, and when the determination signal (J=1) is notified, a torque related to the gradient torque (Ts) is applied to the motor 4, so that the electric vehicle is in a stopped state on an uphill road (accelerator hill hold state), and the driver who perceives the notified determination signal (J=1) applies a torque (second torque When the accelerator operation for applying a torque (second torque (T2)) to the motor 4 is released and a brake operation is performed, the torque (second torque (T2)) immediately before the accelerator operation is released is stored, and a predicted temperature (Temp_j2) after the accelerator operation is released is calculated based on the current temperature (ΔTemp, FIG. 11) and the stored torque (second torque (T2)), and when the predicted temperature (Temp_j2) becomes lower than the judgment temperature threshold value (Temp_th), notification of the judgment signal is stopped (a judgment signal (J=0) is output).

[0180] With the above method, regardless of the driver's repeated accelerator operation / release, the notification that acceleration is not possible is maintained "ON" (determination signal (J = 1)) until the predicted temperature (Temp_j2) becomes lower than the judgment temperature threshold (Temp_th), thereby reducing discomfort to the driver.

[0181] The acceleration determination and notification method for an electric vehicle of this embodiment is an acceleration determination and notification method for an electric vehicle that uses the acceleration determination method for an electric vehicle, and when it is determined that acceleration driving is not feasible, a determination signal (J=1) indicating this impossibility is notified to the outside, and when the determination signal (J=1) is notified, a torque (second torque (T2)) related to the gradient torque (Ts) is applied to the motor 4, causing the electric vehicle to be stopped on an uphill road, and when the driver who has perceived the notified determination signal (J=1) releases the accelerator operation for applying the torque (second torque (T2)) to the motor 4 and performs a brake operation, the determination signal (J=1) immediately before releasing the accelerator operation This is an acceleration determination and notification method for an electric vehicle, which stores a constant temperature threshold (Temp_th) (as a first determination threshold temperature (Temp_th1)), calculates a second determination temperature threshold (Temp_th2) that is lower than the determination temperature threshold (first determination threshold temperature (Temp_th1)) by a predetermined temperature (ΔT_h), calculates a predicted temperature (Temp_j2) after accelerator operation is released based on the current temperature (ΔTemp, FIG. 11) and the torque after accelerator operation is released (for example, second torque (T2) = 0), and stops notification of a determination signal (outputs a determination signal (J = 0)) when the predicted temperature (Temp_j2) becomes lower than the second determination temperature threshold (Temp_th2).

[0182] With the above method, regardless of the driver's repeated accelerator operation / release, the notification that acceleration is not possible is maintained "ON" (determination signal (J = 1)) until the predicted temperature (Temp_j2) becomes lower than the second determination temperature threshold (Temp_th2), thereby reducing discomfort to the driver.

[0183] The acceleration determination and notification method for an electric vehicle of this embodiment is an acceleration determination and notification method for an electric vehicle, which, when it is determined that acceleration traveling is not feasible, notifies an external device of a determination signal (J=1) indicating the impossibility of accelerating traveling, and when the determination signal (J=1) is notified, if a torque (second torque (T2)) related to a gradient torque (Ts) is applied to the motor 4, causing the electric vehicle to be stopped on an uphill road, and if a driver who has perceived the notified determination signal (J=1) releases an accelerator operation for applying the torque (second torque (T2)) to the motor 4 and performs a brake operation, the torque (second torque (T2)) and a determination temperature threshold (Temp_th) immediately before the accelerator operation are released are stored (as a first determination threshold temperature (Temp_th1)), and the determination temperature threshold (Temp_th) is stored (as a second determination threshold temperature (Temp_th2)). a second judgment temperature threshold (Temp_th2) that is lower by a predetermined temperature (ΔT_h) than the current temperature (ΔTemp, FIG. 11)), and a predicted temperature (Temp_j2) after the accelerator operation is released is calculated based on a first predicted temperature (Temp_j21) that is calculated based on the current temperature (ΔTemp, FIG. 11) and the stored torque (second torque (T2)), and the current temperature (ΔTemp, FIG. 11) and the torque (for example, For example, the second torque (T2) = 0) is set as the second predicted temperature (Temp_j22), and when the first predicted temperature (Temp_j21) becomes lower than the judgment temperature threshold (first judgment temperature threshold (Temp_th1)) and / or when the second predicted temperature (Temp_j22) becomes lower than the second judgment temperature threshold (Temp_th2), notification of the judgment signal is stopped (a judgment signal (J = 0) is output).

[0184] With the above method, regardless of the driver's repeated accelerator operation / release, the notification that accelerated driving is not possible is maintained "ON" (determination signal (J=1)) until the first predicted temperature (Temp_j21) becomes lower than the first judgment temperature threshold (Temp_th1) and / or until the second predicted temperature (Temp_j22) becomes lower than the second judgment temperature threshold (Temp_th2), thereby reducing discomfort to the driver and improving the accuracy of the determination signal (J=1).

[0185] The acceleration determination device 100 for an electric vehicle of this embodiment determines whether or not the electric vehicle can achieve a predetermined acceleration running on an uphill road in a state in which the torque of the motor 4 that drives the electric vehicle is limited when the temperature of the motor 4 exceeds a predetermined temperature (set temperature), and the torque decreases as the temperature of the motor 4 becomes higher than the predetermined temperature (set temperature).The acceleration determination device 100 for an electric vehicle determines whether or not the electric vehicle can achieve a predetermined acceleration running on an uphill road in a state in which the torque of the motor 4 is limited when the temperature of the motor 4 exceeds a predetermined temperature (set temperature), and the torque of the motor 4 decreases as the temperature of the motor 4 becomes higher than the predetermined temperature (set temperature).The acceleration determination device 100 for an electric vehicle determines a driving force (F) of the electric vehicle that balances with the running resistance (R) that the electric vehicle experiences when running on an uphill road based on the torque (second torque (T2)) and the angular velocity (mechanical angular velocity (ωm)) of the motor 4. a judgment torque calculation unit 105 that calculates a judgment torque (Tj) by adding a predetermined acceleration torque (Ta) for accelerating to the gradient torque (Ts); a judgment temperature threshold calculation unit 106 that calculates a judgment temperature threshold (Temp_th) that is the maximum temperature of the motor 4 at which the motor 4 can output the judgment torque (Tj); and a judgment unit (judgment signal output unit 107) that judges whether or not accelerated running is possible by comparing the current temperature of the motor 4 (judgment temperature (Temp_j1)) with the judgment temperature threshold (Temp_th).

[0186] In the past, for example, when holding the accelerator on an uphill road, the determination of whether acceleration is possible was made at a timing when the vehicle could not output a balanced torque to prevent the vehicle from rolling back. However, with the above configuration, the determination is made at a timing before the output of the surplus torque (acceleration torque (Ta)) that allows the vehicle to run at a predetermined acceleration when resuming driving from a stopped state, thereby reducing the inconvenience to the driver caused by not being able to produce the predetermined acceleration when starting.

[0187] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. An acceleration determination method for an electric vehicle that determines whether or not the electric vehicle can achieve a predetermined acceleration on an uphill road in a state in which the torque of the motor that drives the electric vehicle is limited when the temperature of the motor exceeds a predetermined temperature and the torque decreases as the temperature of the motor increases above the predetermined temperature, the method comprising: estimating a gradient torque that causes the motor to generate a driving force for the electric vehicle that balances the running resistance experienced when the electric vehicle runs on the uphill road based on the torque and the angular velocity of the motor; calculating a determination torque by adding the predetermined acceleration torque for performing the acceleration to the gradient torque; calculating a determination temperature threshold that is the maximum temperature of the motor at which the motor can output the determination torque; and determining whether or not the acceleration can be achieved by comparing the current temperature of the motor with the determination temperature threshold.

2. The acceleration determination method for an electric vehicle according to claim 1, further comprising: calculating a predicted temperature of the motor after a predetermined time has elapsed since the current temperature was detected based on the current temperature and the gradient torque; and determining whether or not the accelerated driving is feasible by comparing the predicted temperature with the determination temperature threshold.

3. The method for determining acceleration of an electric vehicle according to claim 1, wherein the mass of the electric vehicle is estimated, and the acceleration torque is set to be higher as the mass increases.

4. An acceleration determination and notification method for an electric vehicle that uses the acceleration determination method for an electric vehicle described in any one of claims 1 to 3, wherein when it is determined that the accelerated driving is not feasible, a determination signal indicating the impossibility of the accelerated driving is sent to an external device.

5. An acceleration judgment and notification method for an electric vehicle using the acceleration judgment method for an electric vehicle as defined in claim 2, wherein when it is determined that accelerated driving is not feasible, a judgment signal indicating this impossibility is notified to the outside, and when the judgment signal is notified, the torque related to the gradient torque is applied to the motor, causing the electric vehicle to be stopped on the uphill road, and the driver, perceiving the notified judgment signal, releases the accelerator operation for applying the torque to the motor and performs a brake operation, the torque immediately before the accelerator operation is released is stored, the predicted temperature after the accelerator operation is released is calculated based on the current temperature and the stored torque, and when the predicted temperature becomes lower than the judgment temperature threshold, the notification of the judgment signal is stopped.

6. An acceleration judgment and notification method for an electric vehicle using the acceleration judgment method for an electric vehicle as defined in claim 2, wherein, when it is determined that accelerated driving is not feasible, a judgment signal indicating this impossibility is notified to the outside, and when the judgment signal is notified, the torque related to the gradient torque is applied to the motor, causing the electric vehicle to be stopped on the uphill road, and the driver, perceiving the notified judgment signal, releases the accelerator operation for applying the torque to the motor and performs a brake operation, the method stores the judgment temperature threshold immediately before the accelerator operation is released and calculates a second judgment temperature threshold that is a predetermined temperature lower than the judgment temperature threshold, calculates the predicted temperature after the accelerator operation is released based on the current temperature and the torque after the accelerator operation is released, and stops notifying the judgment signal when the predicted temperature becomes lower than the second judgment temperature threshold.

7. An acceleration judgment and notification method for an electric vehicle using the acceleration judgment method for an electric vehicle as defined in claim 2, wherein when it is determined that accelerated driving is not feasible, a judgment signal indicating this impossibility is notified to the outside, and when the judgment signal is notified, the torque related to the gradient torque is applied to the motor, causing the electric vehicle to be stopped on the uphill road, and the driver, perceiving the notified judgment signal, releases the accelerator operation for applying the torque to the motor and performs a brake operation, the torque and judgment temperature threshold value immediately before the accelerator operation is released are stored, and a second judgment temperature threshold value that is lower by a predetermined temperature than the judgment temperature threshold is calculated, the predicted temperature after the accelerator operation is released is set as a first predicted temperature calculated based on the current temperature and the stored torque, and a second predicted temperature calculated based on the current temperature and the torque after the accelerator operation is released, and the notification of the judgment signal is stopped when the first predicted temperature becomes lower than the judgment temperature threshold and / or the second predicted temperature becomes lower than the second judgment temperature threshold.

8. An acceleration determination device for an electric vehicle that determines whether or not the electric vehicle can achieve a predetermined acceleration running on an uphill road in a state in which the torque of the motor that drives the electric vehicle is limited when the temperature of the motor exceeds a predetermined temperature and the torque decreases as the temperature of the motor increases above the predetermined temperature, the acceleration determination device for an electric vehicle comprising: a gradient torque estimation unit that estimates a gradient torque that causes the motor to generate a driving force of the electric vehicle that balances the running resistance experienced when the electric vehicle runs on the uphill road based on the torque and the angular velocity of the motor; a determination torque calculation unit that calculates a determination torque by adding a predetermined acceleration torque for performing the acceleration running to the gradient torque; a determination temperature threshold calculation unit that calculates a determination temperature threshold that is the maximum temperature of the motor at which the motor can output the determination torque; and a determination unit that determines whether or not the acceleration running is possible by comparing the current temperature of the motor with the determination temperature threshold.

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