Control method of electric vehicle, and control system of electric vehicle

Abstract

To provide a control method of an electric vehicle, and a control system of the electric vehicle which reduce occurrence of an overheated state in a motor etc., in performing warming-up control while the electric vehicle is stopped.SOLUTION: A control method of an electric vehicle generates a first warming-up current command value to set the value as a current command value when warming-up request is received, and further substantially sets a q-axis component of the first warming-up current command value to zero when the electric vehicle is stopped. When it is that the electric vehicle is stopped and brake force is applied to a driving wheel 104a driven by a motor 206 and the occurrence of an overheated state is predicted in the motor 206 or an electric power system for supplying electric power to the motor 206, the control method generates a second warming-up current command value to set the value as the current command value by correcting a current phase of the first warming-up current command value by a predetermined correction value (Δβ).SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to a control method for an electric vehicle and a control system for an electric vehicle. [Background technology]

[0002] Patent Document 1 discloses a method for determining whether or not a battery mounted on an electric vehicle needs to be warmed up, and when it is determined that warming is necessary, correcting the power (d-axis current command value, q-axis current command value) supplied to the motor to control the power supplied to the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-165526 ​​A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, when the electric vehicle is stopped and braking force is applied to the drive wheels, the q-axis current value is controlled to zero so that no torque is generated in the motor. Depending on the rotational position of the motor, current may be concentrated in a specific phase, which may cause that phase to overheat.

[0005] An object of the present invention is to provide a control method for an electric vehicle and a control system for an electric vehicle that reduce the occurrence of an overheating state in a motor or the like when warm-up control is performed while the electric vehicle is stopped. [Means for solving the problem]

[0006] A control method for an electric vehicle according to the present invention is a method for controlling an electric vehicle, which calculates a current command value based on a torque command value, drives a motor of the electric vehicle based on the current command value, generates a first warm-up current command value for increasing the amount of heat generated by the motor when a warm-up request is received from an outside, and sets the first warm-up current command value as a current command value, and when the electric vehicle stops, sets a d-axis component of the first warm-up current command value so that the motor generates heat based on the warm-up request, and sets a q-axis component of the first warm-up current command value to substantially zero. In this control method, when it is detected that the electric vehicle stops and a braking force is applied to a drive wheel driven by the motor, and an overheating state is predicted to occur in the motor or an electric power system that supplies power to the motor, a current phase of the first warm-up current command value is corrected by a predetermined correction value to generate a second warm-up current command value and set the second warm-up current command value as a current command value. Effect of the Invention

[0007] According to the present invention, when the vehicle is stopped, the motor angle is fixed, so a relatively large current flows through a specific phase, which may cause overheating. However, by changing the current phase, the load can be distributed to a phase with more thermal margin, and warm-up can be continued. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the overall configuration of an electric vehicle to which the control system for an electric vehicle according to the first embodiment is applied. [Diagram 2] FIG. 2 is a schematic diagram of a control system for the electric vehicle according to the first embodiment. [Diagram 3] FIG. 3 is a block diagram of a current command generating unit constituting the control system for the electric vehicle of the first embodiment. [Figure 4] FIG. 4 is a diagram showing a determination condition of the current phase change permission determination unit constituting the control system for the electric vehicle of the first embodiment. [Diagram 5] FIG. 5 is a diagram showing a determination condition (relationship between a current phase change permission signal and a switching element temperature) of the current phase change request determination unit constituting the control system for the electric vehicle of the first embodiment. [Figure 6] FIG. 6 is a diagram showing a determination condition (relationship between a current phase change permission signal and a stator temperature) of the current phase change request determination unit constituting the control system for the electric vehicle of the first embodiment. [Figure 7] FIG. 7 is a diagram showing a determination condition for a current phase change request of the current phase change request determination unit constituting the control system for the electric vehicle of the first embodiment. [Figure 8] FIG. 8 is a block diagram of a current control unit constituting the control system for the electric vehicle of the first embodiment. [Figure 9] FIG. 9 is a block diagram of a PWM modulation control unit constituting the control system for the electric vehicle of the first embodiment. [Figure 10] FIG. 10 is a flowchart of the control system for the electric vehicle according to the first embodiment. [Figure 11] FIG. 11 is a diagram showing changes over time in phase current and temperature of the motor (switching element) by the control system for the electric vehicle of the first embodiment. [Figure 12] Figure 12 is a diagram for explaining the relationship between the current phase change amount and the electrical angle change amount when the d-axis current flows in the negative direction, where Figure 12(A) shows the current vector in a rotating coordinate system when the q-axis current is zero and the d-axis current is negative, Figure 12(B) shows the current vector after the current vector shown in Figure 12(A) is rotated by the current phase change amount in the rotating coordinate system, and Figure 12(C) shows the current vector after the rotating coordinate system shown in Figure 12(B) is rotated by the electrical angle change amount relative to a fixed coordinate system. [Figure 13] Figure 13 is a diagram for explaining the relationship between the amount of current phase change and the amount of electrical angle change when the d-axis current flows in the positive direction, where Figure 13(A) shows the current vector in a rotating coordinate system when the q-axis current is zero and the d-axis current is positive, Figure 13(B) shows the current vector after the current vector shown in Figure 13(A) is rotated by the amount of current phase change in the rotating coordinate system, and Figure 13(C) shows the current vector after the rotating coordinate system shown in Figure 13(B) is rotated by the amount of electrical angle change relative to a fixed coordinate system. [Figure 14] FIG. 14 is a diagram showing the relationship between the current phase and the torque. [Figure 15]FIG. 15 is a block diagram of a current command generating unit constituting the control system for the electric vehicle of the second embodiment. [Figure 16] FIG. 16 is a diagram showing a determination condition for a current phase change request of the current phase change request determination unit constituting the control system for the electric vehicle of the second embodiment. [Figure 17] FIG. 17 is a block diagram of a current command generating unit constituting the control system for an electrically powered vehicle according to the third embodiment. [Figure 18] FIG. 18 is a block diagram of a temperature estimation calculation unit constituting the control system for the electric vehicle of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] [Overall configuration of electric vehicle]

[0011] 1 is a schematic diagram showing the overall configuration of an electric vehicle to which the control system for an electric vehicle of the first embodiment is applied. The electric vehicle to which the control system for an electric vehicle of the present embodiment is applied is configured with an electric unit 101 (control system), a reduction gear 102, a differential gear 103, a drive shaft 104, drive wheels 104a, a battery management unit 105 (BMS), a battery 106, and a vehicle controller 108 (VCM). The electric power unit 101 includes a motor 206 (FIG. 2), an inverter 204 (FIG. 2), and components for controlling the inverter 204 (FIG. 2).

[0012] Torque generated by the electric unit 101 (motor 206) is transmitted via the reduction gear 102, the differential gear 103, and the drive shaft 104 to the driving wheels 104a.

[0013] The battery management unit 105 calculates the remaining battery capacity (SOC) based on the terminal voltage and the integration of the charge and discharge current of the battery 106 that serves as the vehicle power source, and acquires the battery temperature using a battery temperature sensor 107, and manages the charge and discharge current according to the acquired temperature. The battery management unit 105 also outputs information such as the remaining battery capacity (SOC), the battery temperature, a warm-up request, and a command for the amount of current required during warm-up to the electric unit 101 via a CAN (Controller Area Network) communication line.

[0014] The vehicle controller 108 receives information from an accelerator pedal sensor 109, a brake pedal sensor 110, an electric parking brake switch 111 (e-PKB), a shift position signal 112, etc., and outputs to the electric unit 101 the required torque related to the accelerator pedal sensor 109, shift position information related to the shift position signal 112, brake depression amount information related to the brake pedal sensor 110, and an e-PKB switch signal related to the electric parking brake switch 111.

[0015] [First embodiment] 2 is a schematic diagram of the control system (electric unit 101) of the electric vehicle of the first embodiment. The electric unit 101 includes a current command generation unit 201, a current control unit 202, a PWM modulation control unit 203, an inverter 204, a pulse generator 208 (RDIC), an electrical angle calculation unit 209, a speed calculation unit 210, and a dq coordinate conversion unit 211. Of these, the current command generation unit 201, the current control unit 202, the PWM modulation control unit 203, the speed calculation unit 210, and the dq coordinate conversion unit 211 are control blocks written in software in a microcomputer unit (MCU) mounted on the electric unit 101.

[0016] A three-phase voltage is applied to the motor 206 by converting the DC voltage of the battery 106 into an AC voltage via an inverter 204 .

[0017] A current sensor 205 for detecting at least two-phase currents is provided at the output terminal of the inverter 204, and outputs a U-phase current (iu) and a V-phase current (iv).

[0018] A DC voltage sensor 212 is provided at the input end of the inverter 204 to detect the DC voltage (Vdc).

[0019] The motor 206 is provided with a resolver 207 as a rotor position detector, and transmits and receives excitation / modulation signals to and from a pulse generator 208 .

[0020] The pulse generator 208 outputs up / down counter pulses A and B and an origin signal pulse Z based on the excitation / modulation signal.

[0021] The electrical angle calculation unit 209 calculates and outputs an electrical angle (θ) based on the ABZ signal.

[0022] The speed calculation unit 210 calculates and outputs an electrical angular speed (ωe) and a mechanical angular speed (ωm) from the amount of change per unit time of the electrical angle (θ).

[0023] The dq coordinate conversion unit 211 converts the U-phase current (iu) and the V-phase current (iv) into a d-axis current (id) and a q-axis current (iq) based on the electrical angle (θ) as follows:

number

[0024] The current command generator 201 receives a torque command value (T * ), electrical angular velocity (ωe), d-axis current (id), q-axis current (iq), electrical angle (θ), temperature sensor values ​​of each phase of the switching elements (IGBTs) constituting the inverter 204, temperature sensor values ​​of the stator windings of the motor 206, a warm-up request, the amount of current required when a warm-up request is met, the amount of brake depression, and the e-PKB signal are input. Based on the above inputs, the current command generating unit 201 generates a d-axis current command value (id * ) and q-axis current command value (iq * The current command generating unit 201 will be described in detail later.

[0025] The current control unit 202 receives a DC voltage (Vdc), a d-axis current command value (id * ), q-axis current command value (iq * ), the electrical angular velocity (ωe), the d-axis current (id), and the q-axis current (iq), the torque of the motor 206 is set to a torque command value (T * d-axis voltage command value (vd * ), q-axis voltage command value (vq * ) and outputs it. The details of the current control unit 202 will be described later.

[0026] The PWM modulation control unit 203 calculates the d-axis voltage command value (vd * ), q-axis voltage command value (vq * ) and the electrical angle (θ), a drive signal (Duu) for the switching element (IGBT) of the inverter 204 is generated. * ~Dwl * The PWM modulation control section 203 will be described in detail later.

[0027] [Current command generation unit 201] 3 is a block diagram of a current command generating unit 201 constituting the control system for the electric vehicle of the first embodiment. The current command generating unit 201 includes a normal current command calculating unit 401, a warm-up current calculating unit 402, a current phase change permission determining unit 403, a current phase change request determining unit 404, a final warm-up current calculating unit 405, and a final current command generating unit 406.

[0028] The normal current command calculation unit 401 calculates the torque command value (T * ), the DC voltage (Vdc) of the battery 106, and the electrical angular velocity (ωe) are input to a map prepared in advance, whereby the d-axis normal current command value (id _T * ) and q-axis normal current command value (iq _T * The current command value used during normal driving is the output value of this normal current command calculation unit 401.

[0029] The warm-up current calculation unit 402 calculates the d-axis normal current command value (id _T *) and q-axis normal current command value (iq _T * ), the required current command, the d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is calculated.

[0030] As in the conventional example, the warm-up current calculation unit 402 calculates a warm-up current command value that is the required current amount required by the required current amount command on the equal torque line so that the torque does not change while the vehicle is running. Regarding the warm-up current command value, when the electric vehicle is stopped, the torque becomes substantially zero (the torque of the motor 206 is 0 or a torque equal to or less than the creep torque), and a current command that becomes the required current amount command is calculated. Note that the required current amount occurs, for example, when the outside air temperature falls below a predetermined temperature, and is set to increase as the outside air temperature falls below the predetermined temperature.

[0031] There are two solutions for the warm-up current command value that provide the required current amount and satisfy the target torque: when the d-axis current is in the positive direction and when it is in the negative direction. The direction of the d-axis current to be passed is determined so that when the current phase changes from the normal current command value to the warm-up current command value, the direction in which the drive shaft 104 is twisted by the generated torque is the same as the direction in which the current phase changes (see FIG. 13).

[0032] Specifically, when the motor 206 is an interior permanent magnet (IPM) type having normal reverse saliency, the d-axis current flows in the positive direction, and when the motor has forward saliency, the d-axis current flows in the negative direction.

[0033] 4 is a diagram showing the judgment conditions of the current phase change permission judgment unit 403 constituting the control system for the electric vehicle of the first embodiment. The current phase change permission judgment unit 403 judges from the shift position, the side brake signal, and the amount of brake depression that the electric vehicle is stopped and that the electric vehicle will not move even if motor torque is applied, and outputs a current phase permission signal. brake ” and the brake depression threshold at which the vehicle does not move is set to “Pbrake_th " and the current phase change permission signal is determined by the process shown in FIG.

[0034] As shown in FIG. 4, when the shift position is “P” (parking) and the e-PKB signal is “ON”, the current phase change permission determination unit 403 determines that the current phase change permission signal is “permitted” regardless of the amount of brake depression.

[0035] The current phase change permission determination unit 403 determines whether the shift position is "P" (parking) and the brake depression amount is "P brake >P brake_th In this case, the current phase change permission signal is determined to be "permitted."

[0036] The current phase change permission determination unit 403 determines whether the shift position is "P" (parking), the e-PKB signal is "OFF," and the brake depression amount is "P brake ≦P brake_th If the current phase change permission signal is "prohibited", the current phase change permission signal is determined to be "prohibited". For example, if the electric vehicle is a four-wheel drive vehicle with some drive wheels receiving braking force and others not receiving braking force, the current phase change is generated to prevent the drive wheels not receiving braking force from spinning freely.

[0037] When the shift position is other than "P" (parking), the current phase change permission determination unit 403 determines that the current phase change permission signal is "prohibited" regardless of the e-PKB signal and the brake depression amount.

[0038] As shown in FIG. 3, the current phase change request determination unit 404 performs an IGBT phase change request determination process and a stator phase change request determination process based on the maximum value processed IGBT temperature (the temperature of the switching elements constituting the inverter 204) and the stator winding temperature of the motor 206, and the current phase change permission signal, by processes as shown in FIG. 5 and FIG. 6 described later, and performs a current phase change request determination as shown in FIG. 7 described later based on the output IGBT phase change request (a request to change the current phase based on a temperature rise of the switching elements) and stator phase change request (a request to change the current phase based on a temperature rise of the stator). Note that the switching element temperature is the maximum value (T SW The stator winding temperature is the maximum value (T MTR ) to extract the

[0039] Fig. 5 is a diagram showing the determination conditions (relationship between the current phase change permission signal and the temperature of the switching element) of the current phase change request determination unit 404 constituting the control system for the electric vehicle of the first embodiment. Fig. 6 is a diagram showing the determination conditions (relationship between the current phase change permission signal and the temperature of the stator) of the current phase change request determination unit 404 constituting the control system for the electric vehicle of the first embodiment. Fig. 7 is a diagram showing the determination conditions of the current phase change request of the current phase change request determination unit 404 constituting the control system for the electric vehicle of the first embodiment.

[0040] As shown in FIG. 5, the current phase change request determination unit 404 determines whether the IGBT temperature (the temperature of the switching element) exceeds a predetermined temperature threshold (T SWth1 ) and the current phase change permission determination unit 403 determines that the IGBT phase change request is "ON."

[0041] The current phase change request determination unit 404 determines whether the IGBT temperature is a predetermined temperature threshold (T SWth2 ) and the current phase change permission determination unit 403 determines that the IGBT phase change request is "OFF." SWth1) is the temperature threshold (T SWth2 ) is set to a value higher than the threshold voltage Vcc, providing hysteresis in the determination of the IGBT phase change request, thereby preventing chattering in the determination.

[0042] The current phase change request determination unit 404 determines whether the IGBT temperature is a predetermined temperature threshold (T SWth1 ) and a predetermined temperature threshold (T SWth2 ) and the current phase change permission determination unit 403 determines that the current phase change is permitted, the previous determination content is maintained as an IGBT phase change request.

[0043] When the current phase change permission determination unit 403 determines that the change is "prohibited," the current phase change request determination unit 404 determines that the IGBT phase change request is "OFF" regardless of the IGBT temperature.

[0044] As shown in FIG. 6, the current phase change request determination unit 404 determines whether the stator temperature of the motor 206 exceeds a predetermined temperature threshold (T MTRth1 ) and the current phase change permission determination unit 403 determines that the stator phase change request is "ON."

[0045] The current phase change request determination unit 404 determines whether the stator temperature is greater than a predetermined temperature threshold (T MTRth2 ) and the current phase change permission determination unit 403 determines that the stator phase change request is "permitted." MTRth1 ) is the temperature threshold (T MTRth2 ) to provide hysteresis in determining whether or not a stator phase change is required, thereby preventing chattering in the determination.

[0046] The current phase change request determination unit 404 determines whether the stator temperature is greater than a predetermined temperature threshold (T MTRth1 ) and a predetermined temperature threshold (T MTRth2 ) and further, if the current phase change permission determining unit 403 determines that the current phase change is permitted, the previous determination content is maintained as a stator phase change request.

[0047] When the current phase change permission determination unit 403 determines that the change is "prohibited," the current phase change request determination unit 404 determines that the stator phase change request is "OFF" regardless of the stator temperature.

[0048] As shown in FIG. 7, when the IGBT phase change request is "ON" and the stator phase change request is "ON", the current phase change request determination unit 404 sets the current phase change request to "ON".

[0049] When the IGBT phase change request is "ON" and the stator phase change request is "OFF", the current phase change request determination unit 404 sets the current phase change request to "ON".

[0050] When the IGBT phase change request is "OFF" and the stator phase change request is "ON", the current phase change request determination unit 404 sets the current phase change request to "ON".

[0051] When the IGBT phase change request is "OFF" and the stator phase change request is "OFF", the current phase change request determination unit 404 sets the current phase change request to "OFF".

[0052] Here, the time constant of the temperature rise of the switching element tends to be shorter than the time constant of the temperature rise of the stator, and the IGBT phase change request can be turned "ON" at an earlier stage than the stator phase change request.

[0053] In addition, the current phase change request determination unit 404 can set the current phase change request to “ON” when any of the three-phase currents (iu, iv, iw) detected via the current sensor 205 exceeds a predetermined current value (a current value at which overheating may occur).

[0054] As shown in FIG. 3, the final warm-up current calculation unit 405 calculates the d-axis final warm-up current command value (id _heat_fin * ), q-axis final warm-up current command value (iq _heat_fin * ) to output.

[0055] Here, if the current phase change request is "OFF", the d-axis warm air current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is used as the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * )

[0056] In addition, when the current phase change request is "ON", the d-axis warm air current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is rotated, and the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * )

[0057] The current phase change amount (Δβ) is set in the direction in which the current amount of the phase where the phase current has an extreme value (positive maximum value, negative maximum value) decreases, and its magnitude is determined, for example, so that the current value of the phase where the current amount is an extreme value becomes 0. If the stiffness (Kd) of the drive shaft 104 and the gear ratio (Nal) of the reducer 102 are known in advance, the target sum of the current phase change amount (Δβ) and the motor angle displacement (Δθ) due to the torsion of the drive shaft 104 can be set as "Δθ sta " can be calculated so as to satisfy the following equations (2) and (3).

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[0058] Since the calculations using the formulas (2) and (3) are complicated, the final warm-up current calculation unit 405 calculates the target "Δθ staA map may be implemented in which "ia" (required current amount) is input and "Δβ" is output. In addition, if the maximum value of the torque is limited due to requirements of peripheral devices, the current amount (d-axis warm-up current command value (id _heat * ) and the q-axis warm-up current command value (iq _heat * )) to place a limit on “Δβ”.

[0059] After calculating "Δβ" as described above, the final warm-up current calculation unit 405 calculates the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * ) and outputs it to the current control unit 202.

number

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[0060] When there is no warm-up request, the final current command generator 406 generates the d-axis normal current command value (id _T * ) and q-axis normal current command value (iq _T * ) and the d-axis current command value (id * ) and q-axis current command value (iq * ) to the current control unit 202.

[0061] When there is a warm-up request, the final current command generator 406 generates the d-axis final warm-up current command value (id _heat_fin * ) and the q-axis final current command value (iq _heat_fin * ) and the d-axis current command value (id * ) and q-axis current command value (iq * ) to the current control unit 202.

[0062] [Current control unit 202] 8 is a block diagram of the current control unit 202 constituting the control system for the electric vehicle of the first embodiment. Note that, although some of the configuration on the q-axis side is omitted here, it is the same as the configuration on the d-axis side. The current control unit 202 includes an interference voltage table 301, a low-pass filter 302, a subtractor 304, a PI controller 303, and an adder 305.

[0063] The interference voltage table 301 stores the d-axis current command value (id * ) and q-axis current command value (iq * ), electrical angular velocity (ωe), and DC voltage (Vdc) are used as inputs to refer to a lookup table to determine the d-axis interference voltage command value (vd _dcpl * ), and the q-axis interference voltage command value (vq _dcpl * ) is required.

[0064] The subtractor 304 calculates the d-axis current command value (id * ) and the d-axis current detection value (id) output from the dq coordinate conversion unit 211 (FIG. 2), and output the result to the PI controller 303.

[0065] The PI controller 303 calculates the d-axis control voltage (vd _pi ) and outputs it to the adder 305.

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[0066] Generally, the proportional gain (k pd ) and integral gain (k id ) is set according to equation (7) using the d-axis inductance (Ld) and winding resistance (R) of the motor 206, and the reference response time constant (τ) of the d-axis current (id) and q-axis current (iq).

number

[0067] The low-pass filter 302 uses a first-order filter (with the same time constant as the above-mentioned "τ") shown in the following equation (8) to generate a d-axis interference voltage command value (vd _dcpl * ) to the d-axis decoupling voltage (vd _dcpl_flt ) and output it to the adder 305.

number

[0068] The adder 305 calculates the d-axis control voltage (vd _pi ) and d-axis decoupling voltage (vd _dcpl_flt ) to obtain the d-axis final voltage command value (vd _fin * ) to the d-axis voltage command value (vd * ) to the PWM modulation control unit 203. Note that the q-axis final voltage command value (vq _fin * ) is calculated in the same manner as above, and this is used as the q-axis voltage command value (vq * ) to the PWM modulation control section 203.

[0069] [PWM modulation control unit 203] 9 is a block diagram of the PWM modulation control unit 203 constituting the control system for the electric vehicle of Embodiment 1. As shown in FIG. 9, the PWM modulation control unit 203 includes a coordinate conversion unit 501, an asynchronous PWM control unit 502, and an asynchronous PWM signal generator 503.

[0070] The coordinate conversion unit 501 receives the d-axis voltage command value (vd * ), q-axis voltage command value (vq * ), and electrical angle (θ). The coordinate conversion unit 501 then calculates the d-axis voltage command value (vd * ) and q-axis voltage command value (vq * ) to the three-phase voltage command value (v u * , v v * , v w * ) to

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[0071] The asynchronous PWM control unit 502 calculates a three-phase voltage command value (v u * , v v * , v w * ) and DC voltage (Vdc) based on the three-phase duty command value (Duty _u , Duty _v , Duty _w ) [%].

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[0072] The asynchronous PWM signal generator 503 generates a carrier triangular wave with a constant frequency and a duty command value (Duty _u , Duty _v , Duty _w ) is compared with the six asynchronous PWM signals (D uu * , D ul * , D vu * , D vl * , D wu * , D wl * )

[0073] [Flowchart of the first embodiment] FIG. 10 is a flowchart of the control system for the electric vehicle according to the first embodiment.

[0074] In step S01, the current command generating unit 201 (the normal current command calculating unit 401) calculates a torque command value (T * ), DC voltage (Vdc), and electrical angular velocity (ωe) are used to determine the d-axis normal current command value (id _T* ) and q-axis normal current command value (iq _T * ) is calculated.

[0075] In step S02, the current command generating unit 201 (final current command generating unit 406) determines whether or not there is a warm-up request. If YES, the process proceeds to step S03, and if NO, the process proceeds to step S09 described below.

[0076] In step S03, the current command generating unit 201 (current phase change permission determining unit 403) receives information on the e-PKB signal, the brake depression amount, and the shift position, and executes a current phase change permission determination according to the table shown in FIG.

[0077] In step S04, the current command generating unit 201 (current phase change request determination unit 404) determines whether the content of the current phase change permission determination is "permitted" or not, and if the result is YES ("permitted"), the process proceeds to step S05, and if the result is NO ("prohibited") (i.e., "no current phase change"), the process proceeds to step S08B described below.

[0078] In step S05, the current command generating unit 201 (current phase change request determination unit 404) receives IGBT temperature information and stator temperature information and performs a current phase request determination (prediction of the occurrence of an overheating state in the motor 206 or inverter 204) according to the table shown in Figure 5-7.

[0079] In step S06, the current command generating unit 201 (final warm-up current calculation unit 405) determines whether the content of the current phase request judgment is “ON” or not, and if the result is YES (“ON”) (an overheating state is predicted to occur in the motor 206 or the inverter 204), it proceeds to step S07, and if the result is NO (“OFF”) (an overheating state is predicted not to occur in the motor 206 or the inverter 204), it proceeds to step S08B described below.

[0080] In step S07, the current command generating unit 201 (final warm-up current calculating unit 405) calculates the current phase change amount (Δβ) using the above equations (2) and (3) or a map that serves as a substitute for these.

[0081] In step S08A, the current command generating unit 201 (warm air current calculating unit 402) calculates the d-axis normal current command value (id _T * ) and q-axis normal current command value (iq _T * ), and the d-axis warm-up current command value (id _heat * ) and the q-axis warm-up current command value (iq _heat * Further, the current command generating unit 201 (final warm-up current calculating unit 405) generates the d-axis warm-up current command value (id _heat * ) and the q-axis warm-up current command value (iq _heat * ), and the d-axis final warm-up current command value (id _heat_fin * ) and the q-axis final current command value (iq _heat_fin * ) is calculated.

[0082] In step S08B, the current command generating unit 201 (the warm-up current calculating unit 402) calculates the d-axis normal current command value (id _T * ) and q-axis normal current command value (iq _T * ), and the d-axis warm-up current command value (id _heat * ) and the q-axis warm-up current command value (iq _heat * Further, the current command generating unit 201 (final warm-up current calculating unit 405) generates the d-axis warm-up current command value (id _heat * ) and the q-axis warm-up current command value (iq _heat * ) is the d-axis final warm-up current command value (id _heat_fin *) and the q-axis final current command value (iq _heat_fin * )

[0083] In step S09 (derived from step S02 (NO)), the current command generator 201 (final current command generator 406) calculates the d-axis normal current command value (id _T * ) and q-axis normal current command value (iq _T * ), respectively, the d-axis current command value (id * ) and q-axis current command value (iq * ) and output to the current control unit 202.

[0084] In step S09 (derived from step S08A), the current command generating unit 201 (final current command generating unit 406) generates the d-axis final warm-up current command value (id _heat_fin * ) and the q-axis final current command value (iq _heat_fin * ) are the d-axis current command values ​​(id * ) and q-axis current command value (iq * ) and output to the current control unit 202.

[0085] In step S09 (derived from step S08B), the current command generator 201 (final current command generator 406) generates the d-axis final warm-up current command value (id _heat_fin * ) and the q-axis final current command value (iq _heat_fin * ) are the d-axis current command values ​​(id * ) and q-axis current command value (iq * ) and output to the current control unit 202.

[0086] In step S10, the current control unit 202 calculates the d-axis current command value (id * ), q-axis current command value (iq * ), d-axis current detection value (id), q-axis current detection value (iq), and electrical angular velocity (ωe) are used to calculate the d-axis voltage command value (vd * ) and q-axis voltage command value (vq* ) and outputs it to the PWM modulation control unit 203.

[0087] In step S11, the PWM modulation control unit 203 calculates the d-axis voltage command value (vd * ), q-axis voltage command value (vq * ), and the three-phase voltage command value (v u * , v v * , v w * ) and then generates the three-phase voltage command value (v u * , v v * , v w * ) and DC voltage (Vdc) based on the three-phase duty command value (Duty _u , Duty _v , Duty _w ) [%], and the drive signal (D uu * , D ul * , D vu * , D vl * , D wu * , D wl * )

[0088] [Relationship between phase current and temperature of motor 206 (switching element)] FIG. 11 is a diagram showing changes over time in phase current and temperature of the motor 206 (switching element) by the control system for the electric vehicle of the first embodiment.

[0089] For example, when the electric unit 101 is warmed up while the motor 206 is stopped, the current values ​​of the UVW phases become unbalanced. Therefore, the switching elements and the winding temperatures of the stator also become unbalanced accordingly, and one phase may become hotter than the other two phases. This narrows the thermal constraints, and reduces the amount of heat generated by the electric unit 101 (FIG. 1).

[0090] Therefore, by changing the current phase and further twisting the shaft to change the motor angle, the phase of the flowing phase current can be shifted. For example, when the U-phase current is in a state where it is peaking, changing the current phase can move it to a phase away from the peak. As shown in Fig. 11, in a state where the U-phase is at its peak from time t0 to just before time t1 and is overheating, by changing the current phase at time t1, the load can be distributed to, for example, the W-phase, and the peak temperature can be reduced without changing the amount of current. This relaxes the thermal constraints and increases the amount of heat generated by the electric unit 101.

[0091] [Relationship between current phase change (Δβ) and electrical angle change (Δθ)] Figure 12 is a diagram for explaining the relationship between the current phase change (Δβ) and the electrical angle change (Δθ) when the d-axis current flows in the negative direction, where Figure 12(A) shows the current vector in a rotating coordinate system when the q-axis current is zero and the d-axis current is negative, Figure 12(B) shows the current vector after the current vector shown in Figure 12(A) is rotated by the current phase change (Δβ), and Figure 12(C) shows the current vector after the rotating coordinate system shown in Figure 12(B) is rotated by the electrical angle change (Δθ) relative to a fixed coordinate system. Figure 13 is a diagram for explaining the relationship between the current phase change (Δβ) and the electrical angle change (Δθ) when the d-axis current flows in the positive direction, where Figure 13(A) shows the current vector in a rotating coordinate system when the q-axis current is zero and the d-axis current is positive, Figure 13(B) shows the current vector after the current vector shown in Figure 13(A) is rotated by the current phase change (Δβ), and Figure 13(C) shows the current vector after the rotating coordinate system shown in Figure 13(B) is rotated by the electrical angle change (Δθ) relative to a fixed coordinate system.

[0092] The phase change amount of the phase current is synonymous with the change amount of the angle of the current vector in a fixed coordinate system (XY coordinate system). In other words, it is determined by two factors: the current phase change amount (Δβ) in a rotating coordinate system (dq coordinate system) whose coordinate axes are the d-axis current and the q-axis current, and the electrical angle change amount (Δθ) of the motor 206 (FIG. 2) in a fixed coordinate system that shares a common origin with the rotating coordinate system.

[0093] Naturally, torque is generated in motor 206 as the current phase changes, so the amount of change in the current phase must be determined taking into consideration the stress on peripheral devices such as reducer 102 (Fig. 1) and drive shaft 104 (Fig. 1). Therefore, consider the case where the current phase is changed from a state in which the d-axis current flows in the positive direction, and the case where the current phase is changed from a state in which the d-axis current flows in the negative direction. Also, consider here the case where the current phase is changed in a direction that generates positive torque, and in which direction the motor angle (electrical angle) moves in a fixed coordinate system due to that torque.

[0094] First, as shown in Fig. 12(A), consider the case where the d-axis current is negative. In this case, the current vector is parallel to the d-axis and points in the negative direction. In this case, the fixed coordinate system and the rotating coordinate system have a common origin and are arranged so that they overlap each other.

[0095] Normally, a positive torque is output by passing a positive q-axis current. Therefore, when the current phase of the current vector shown in Fig. 12(A) is changed so as to give a positive torque to the current vector, the current vector changes its direction toward the positive direction of the q-axis and rotates clockwise by the current phase change amount (Δβ) as shown in Fig. 12(B).

[0096] As described above, when a braking force is applied to the drive wheel 104a (FIG. 1) and a positive torque is applied to the motor 206 (FIG. 2), the drive shaft 104 (FIG. 1) that supports the drive wheel 104a is twisted, causing the motor 206 (rotor) to rotate. At this time, as shown in FIG. 12(C), the rotating coordinate system rotates around the origin by an electrical angle change (Δθ) with respect to the fixed coordinate system.

[0097] When the d-axis current is in the negative direction, the direction of rotation of the current vector in the rotating coordinate system differs from the direction of rotation of the rotating coordinate system relative to the fixed coordinate system. Therefore, in the fixed coordinate system, the current vector rotates by "Δβ-Δθ".

[0098] Next, consider the case where the d-axis current is in the positive direction, as shown in Fig. 13(A). In this case, the current vector is parallel to the d-axis and faces in the positive direction. Then, as described above, if the current phase of the current vector shown in Fig. 13(A) is changed so as to give a positive torque to the current vector, the current vector changes in the direction toward the positive direction of the q-axis and rotates counterclockwise by the current phase change amount (Δβ) as shown in Fig. 13(B).

[0099] When the d-axis current is in the positive direction, the direction of rotation of the current vector in the rotating coordinate system is the same as the direction of rotation of the rotating coordinate system relative to the fixed coordinate system. Therefore, in the fixed coordinate system, the current vector rotates by "Δβ + Δθ".

[0100] Therefore, when the current phase is changed based on the positive flow of the d-axis current, the amount of change in the direction of the current vector in the final fixed coordinate system can be made larger for the same amount of change in the current phase.

[0101] In addition, a secondary advantage of changing the current phase based on the positive flow of the d-axis current is that the amount of change in torque relative to the amount of change in current phase is smaller than when the negative flow of the d-axis current is used as the base, as shown below.

[0102] FIG. 14 is a diagram showing the relationship between the current phase and torque. In FIG. 14, when the current phase is 90 [deg], the d-axis current is negative, and when the current phase is 270 [deg], the d-axis current is positive. As shown in FIG. 14, the rate of change (slope of the curve) of the current phase-torque characteristics is smaller when the current phase is around 270 [deg] than when the current phase is around 90 [deg]. A typical interior permanent magnet motor (IPMSM) has reverse salience, and when the d-axis current is negative, a reluctance torque is generated in the same direction as the magnet torque, and when the d-axis current is positive, a reluctance torque is generated in a direction that cancels out the magnet torque. Therefore, when the current phase is changed based on the d-axis positive direction, the output torque can be kept small even with the same amount of current phase change, and stress on peripheral devices can be reduced.

[0103] [Second embodiment] Fig. 15 is a block diagram of a current command generating unit 201 constituting the control system (electric unit 101) of the electric vehicle of the second embodiment. Fig. 16 is a diagram showing a judgment condition of a current phase change request of a current phase change request judgment unit 404 constituting the control system (electric unit 101) of the electric vehicle of the second embodiment.

[0104] In the current command generating unit 201 of the second embodiment, the current phase change permission determining unit 403 is omitted.

[0105] Further, the current phase change request determination unit 404 determines the current phase change request (predicts the occurrence of an overheating state in the motor 206 or the inverter 204) according to the table shown in FIG.

[0106] The current phase change request determination unit 404 determines whether the current phase change permission determination is "ON" and whether the required current amount command (ia * ) is greater than a predetermined threshold (ia_th), the current phase change request is set to "ON" (an overheating condition is predicted to occur in the motor 206 or the inverter 204).

[0107] The current phase change request determination unit 404 determines whether the current phase change permission determination is "ON" and whether the required current amount command (ia* ) is equal to or less than a predetermined threshold (ia_th), the current phase change request is set to "OFF" (it is predicted that an overheating state will not occur in the motor 206 or the inverter 204).

[0108] When the current phase change permission determination is "OFF", the current phase change request determination unit 404 outputs a required current amount command (ia * ) sets the current phase change request to "OFF".

[0109] When the current phase change permission determination is "ON", the current phase change request determination unit 404 outputs a required current amount command (ia * It is also possible to set the current phase change request to "ON" regardless of the magnitude of the current phase change (predicting that an overheating state will occur in the motor 206 or inverter 204).

[0110] The final warm-up current calculation unit 405 calculates the d-axis final warm-up current command value (id _heat_fin * ), q-axis final warm-up current command value (iq _heat_fin * ) to output.

[0111] When the current phase change request is "ON" and the electrical angle (θ) is within a predetermined range (for example, 5 [deg]) centered on a specific electrical angle, the final warm-up current calculation unit 405 calculates the d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is rotated, and the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * )

[0112] Here, the specific electrical angle is an electrical angle (θ) at which any one of the U-phase current, V-phase current, and W-phase current of the stator of the motor 206 has a positive maximum value or a negative maximum value. The U-phase current, V-phase current, and W-phase current change periodically in a sinusoidal manner with respect to the electrical angle (θ). For example, if the U-phase current has a positive maximum value at an electrical angle (θ) of 0[deg] and a negative maximum value at 180[deg], the V-phase current has a positive maximum value at 120[deg] and a negative maximum value at 300[deg], and the W-phase current has a positive maximum value at 60[deg] and a positive maximum value at 240[deg]. As a result, the specific electrical angles are 0[deg], 60[deg], 120[deg], 180[deg], 240[deg], and 300[deg].

[0113] Therefore, when the electrical angle (θ) of the motor 206 is within a predetermined range centered on a specific electrical angle, the current of one of the phases becomes excessive, and an overheating state occurs in the switching element and in one of the phases of the stator. Therefore, by the above-mentioned rotation coordinate transformation, the d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is rotated, and the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * ) to reduce the overheating condition.

[0114] When changing the current phase as described above, the final warm-up current calculation unit 405 does not keep the current phase change amount (Δβ) constant, but changes the current phase change amount (Δβ) by max " is the maximum current phase value, "β min " may be set as a minimum value and "Δβ" may be varied at a constant period (T) as shown in the following equations (11) and (12).

number

number

[0115] Here, it is preferable to set the period (T) shorter than the time constant of the temperature rise of the switching element or the time constant of the temperature rise of the motor 206 (stator). This makes it possible to suppress the temperature rise of the switching element or the motor 206 (stator) and ensure the amount of current required for warming up. In addition, while equations (11) and (12) change the amount of current phase change (Δβ) with a triangular wave, a similar effect can be obtained with a periodic function such as a sine wave.

[0116] On the other hand, when the current phase change request is “OFF”, or when the current phase change request is “ON” and the electrical angle (θ) is outside a predetermined range (for example, 5[deg]) centered on the specific electrical angle, the final warm-up current calculation unit 405 calculates the d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * ) is used as the d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * )

[0117] [Third embodiment] Fig. 17 is a block diagram of a current command generating unit 201 constituting the control system (electric unit 101) of an electric vehicle of the third embodiment. Fig. 18 is a block diagram of a temperature estimation calculation unit 407 constituting the control system (electric unit 101) of an electric vehicle of the third embodiment.

[0118] A temperature estimation calculation unit 407 is added to the current command generation unit 201 of the third embodiment.

[0119] The temperature estimation calculation unit 407 includes a current norm calculation unit 601 , an IGBT loss calculation unit 602 , an IGBT temperature estimation unit 603 , a stator loss calculation unit 604 , and a stator temperature estimation unit 605 .

[0120] The current norm calculation unit 601 calculates the current norm (ia) by inputting the d-axis current detection value (id) and the q-axis current detection value (iq) into the following equation (13).

number

[0121] The IGBT loss calculation unit 602 inputs the current norm (ia) and the electrical angular velocity (ωe) into a prepared map to calculate the IGBT loss (P SW [W]) (switching element loss).

[0122] The IGBT temperature estimation unit 603 estimates the IGBT loss (P SW The calculation is made according to the following formula (14) using the temperature "Tw" of the cooling water that cools the switching elements (and the stator) and the power consumption "W".

number

[0123] Here, "R SW ” is the thermal resistance of the switching element, “C SW " is the thermal capacity of the switching element.

[0124] The stator loss calculation unit 604 inputs the current norm (ia) and the electrical angular velocity (ωe) into a prepared map to calculate the stator loss (P MTR Calculate the value of [W].

[0125] The stator temperature estimation unit 605 estimates the stator loss (P MTR [W]) and the cooling water temperature “Tw” are used in accordance with the following formula (15).

number

[0126] Here, "R MTR ” is the thermal resistance of the stator, “C MTR " is the thermal capacity of the stator.

[0127] [Effects of this embodiment] The control method for an electric vehicle according to the present embodiment is * ) based on the current command value (d-axis current command value (id * ), q-axis current command value (iq * )) and drives the motor 206 of the electric vehicle based on the current command value. When a warm-up request is received from the outside, a first warm-up current command value (d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * )) is generated and set as a current command value, and when the electric vehicle is stopped, the d-axis component of the first warm-up current command value (d-axis warm-up current command value (id _heat * )) and the q-axis component of the first warm-up current command value (q-axis warm-up current command value (iq _heat * )) to substantially zero, the method for controlling an electric vehicle includes: detecting that a braking force is being applied to the drive wheels 104a driven by the motor 206 when the electric vehicle is stopped; and predicting that an overheating state will occur in the motor 206 or an electric power system (e.g., the inverter 204) that supplies electric power to the motor 206; and correcting the current phase of the first warm-up current command value by a predetermined correction value (amount of change in current phase (Δβ)) to set a second warm-up current command value (d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * ) is generated and set as the current command value.

[0128] With the above method, when the vehicle is stopped, the motor angle (electrical angle (θ)) is fixed, so a relatively large current flows through a specific phase, which may cause overheating. However, by changing the current phase, the load can be distributed to phases with more thermal margins, and warm-up can be continued.

[0129] In this embodiment, the occurrence of an overheating state is predicted when the electrical angle (θ) of the motor 206 is within a predetermined range centered on a specific electrical angle at which the current of any of the three-phase currents (iu, iv, iw) flowing through the motor 206 reaches an extreme value (positive maximum value, negative maximum value).

[0130] By using the above method, the heating state of the motor 206 and the power system (inverter 204) that supplies power to the motor 206 can be predicted in advance.

[0131] In this embodiment, the d-axis component of the first warm-up current command value (d-axis current command value (id * )) and the q-axis component of the first warm-up current command value (q-axis current command value (iq * )) is set to substantially zero, the method for controlling an electric vehicle detects that the electric vehicle is stopped and a braking force is applied to the drive wheels 104a driven by the motor 206, and the electrical angle (θ) of the motor 206 is within a predetermined range centered on a specific electrical angle at which the current of any phase of the three-phase current (iu, iv, iw) flowing through the motor 206 becomes an extreme value (positive maximum value, negative maximum value), and the required current amount (ia) is within a predetermined threshold value (ia _th ) to predict the occurrence of an overheating condition.

[0132] By the above method, the required current (ia) is set to the threshold (ia _th ) In the following cases, an overheating state does not occur in the motor 206 and the switching elements, so in this case, the current phase of the first warm-up current command value is changed to avoid generating torque in the motor 206, thereby reducing the load on peripheral devices.

[0133] In this embodiment, the current command value (d-axis current command value (id * ), q-axis current command value (iq *In the case where a PWM signal is generated based on the PWM signal and output to an inverter 204, and the inverter 204 generates three-phase currents (iu, iv, iw) from the PWM signal and drives a motor 206 with the three-phase currents (iu, iv, iw), when the temperature of a switching element of the inverter 204 that generates a current of any phase of the three-phase currents (iu, iv, iw) reaches a first predetermined temperature (T SWth1 ) or the temperature of the motor 206 exceeds a second predetermined temperature (T MTRth1 ), three-phase current (i u , i v , i w When the current detection value of any of the phases exceeds a predetermined current value, the occurrence of the overheating state is predicted.

[0134] By using the above method, the current phase is changed only when overheating occurs in the motor 206 or the inverter 204 (switching element), thereby reducing stress on peripheral devices.

[0135] In this embodiment, the occurrence of an overheating state is predicted when the current detection value of any of the three-phase currents supplied to the motor 206 exceeds a predetermined current value (for example, when the current detection value of any of the U-phase current, V-phase current, or W-phase current of the stator of the motor 206 exceeds a positive maximum value or a value close to it, or a negative maximum value or a value close to it).

[0136] The above method provides a simple method for predicting the occurrence of an overheating condition.

[0137] In this embodiment, the second warm-up current command value (d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * )) is taken as the norm of the first warm-up current command value (d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * )) to the same value.

[0138] By using the above method, the warm-up can be continued without changing the total amount of current when the electric vehicle is stopped.

[0139] In this embodiment, the d-axis component of the first warm-up current command value (d-axis warm-up current command value (id _heat * )) and the q-axis component of the first warm-up current command value (q-axis warm-up current command value (iq _heat * )) is the coordinate axis (q axis), and the first warm air current command value (d axis warm air current command value (id _heat * ), q-axis warm-up current command value (iq _heat * )) and the second warm-up current command value (d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * With respect to a rotating coordinate system (dq coordinate system) expressing the first warm-up current command value and the second warm-up current command value as current vectors, respectively, and a fixed coordinate system (XY coordinate system) having a common origin with the rotating coordinate system, the d-axis component (d-axis warm-up current command value (id _heat * Sets the sign of the ).

[0140] With the above method, the direction in which the current vector rotates in the rotating coordinate system is the same as the direction in which the rotating coordinate system rotates relative to the fixed coordinate system, so that the required current phase change can be achieved with less output torque (q-axis component of the second warm-up current command value), thereby improving the durability and reducing costs of peripheral equipment.

[0141] In this embodiment, the correction value (current phase change amount (Δβ)) is varied in a period (T) shorter than the time constant of the temperature change when the switching element heats up or the time constant of the temperature change when the motor 206 (stator) heats up.

[0142] By using the above method, it is possible to suppress the temperature rise of the switching elements or the motor 206 (stator) and ensure the amount of current required for warming up.

[0143] In this embodiment, the temperature of the inverter 204 (switching element) and the temperature of the motor 206 (stator) are estimated based on the temperature of the refrigerant that cools the inverter 204 (switching element) and the motor 206 (stator) and the detected current value of the motor 206.

[0144] By using the above method, the temperatures of the inverter 204 (switching element) and the motor 206 (stator) can be estimated without providing temperature sensors in the inverter 204 (switching element) and the motor 206 (stator).

[0145] The control system for an electric vehicle of this embodiment includes a motor 206 that drives the electric vehicle, Torque command value (T * ) to drive the motor 206 based on the current command value (d-axis current command value (id * ), q-axis current command value (iq * The controller (current command generating unit 201) calculates a first warm-up current command value (d-axis warm-up current command value (id _heat * ), q-axis warm-up current command value (iq _heat * )) is generated and set as a current command value, and when the electric vehicle is stopped, the d-axis component of the first warm-up current command value (d-axis warm-up current command value (id _heat * )) and the q-axis component of the first warm-up current command value (q-axis warm-up current command value (iq _heat *)) to substantially zero, the controller (current command generating unit 201) detects that the electric vehicle is stopped and a braking force is applied to the drive wheels 104a driven by the motor 206, and when an overheating state is predicted to occur in the motor 206 or an electric power system (e.g., an inverter 204) that supplies electric power to the motor 206, corrects the current phase of the first warm-up current command value by a predetermined correction value (amount of current phase change (Δβ)) to set a second warm-up current command value (d-axis final current command value (id _heat_fin * ), q-axis final current command value (iq _heat_fin * ) is generated and set as the current command value.

[0146] With the above configuration, when the vehicle is stopped, the motor angle (electrical angle (θ)) is fixed, so a relatively large current flows through a specific phase, which may cause overheating. However, by changing the current phase, the load can be distributed to phases with more thermal margins, and warm-up can be continued.

[0147] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above-mentioned embodiments. In addition, the above-mentioned embodiments can be appropriately combined. [Explanation of symbols]

[0148] 101 Electric unit, driving wheel 104a, 204 Inverter, 206 Motor

Claims

1. Calculating a current command value based on the torque command value and driving a motor of the electric vehicle based on the current command value; A method for controlling an electric vehicle, comprising: when receiving a warm-up request from an outside, generating a first warm-up current command value for increasing a heat generation amount of the motor, and setting the first warm-up current command value as the current command value; and when the electric vehicle stops, setting a d-axis component of the first warm-up current command value so that the motor generates heat based on the warm-up request, and setting a q-axis component of the first warm-up current command value to substantially zero, A control method for an electric vehicle, comprising: detecting that the electric vehicle is stopped and that a braking force is being applied to a drive wheel driven by the motor; and when an overheating condition is predicted to occur in the motor or a power system that supplies power to the motor, correcting the current phase of the first warm-up current command value with a predetermined correction value to generate a second warm-up current command value and setting the second warm-up current command value as the current command value.

2. 2. The method for controlling an electric vehicle according to claim 1, wherein the occurrence of the overheating state is predicted when the electrical angle of the motor is within a predetermined range centered on a specific electrical angle at which a current of any one of three-phase currents flowing through the motor has an extreme value.

3. A d-axis component of the first warm-up current command value is set so that the motor generates heat based on a required current amount related to the warm-up request, and a q-axis component of the first warm-up current command value is set to substantially zero, 2. The method for controlling an electric vehicle according to claim 1, wherein the occurrence of the overheating state is predicted when the electrical angle of the motor is within a predetermined range centered on a specific electrical angle at which a current of any phase of a three-phase current flowing through the motor has an extreme value, and when the required current amount exceeds a predetermined threshold value.

4. A PWM signal is generated based on the current command value, the PWM signal is output to an inverter constituting the power system, the inverter generates a three-phase current from the PWM signal, and the motor is driven by the three-phase current, 2. The method for controlling an electric vehicle according to claim 1, further comprising the step of predicting the occurrence of the overheating state when a temperature of a switching element of the inverter that generates a current of any one of the three-phase currents exceeds a first predetermined temperature, or when a temperature of the motor exceeds a second predetermined temperature.

5. The method for controlling an electric vehicle according to claim 1, further comprising the step of predicting the occurrence of the overheating state when a current detection value of any one of the three-phase currents supplied to the motor exceeds a predetermined current value.

6. 6. The method for controlling an electric vehicle according to claim 1, wherein a norm of the second warm-up current command value is set to be equal to a norm of the first warm-up current command value.

7. 6. The method for controlling an electric vehicle according to claim 1, wherein, with respect to a rotating coordinate system having coordinate axes parallel to a d-axis component of the first warm-up current command value and a q-axis component of the first warm-up current command value, and expressing the first warm-up current command value and the second warm-up current command value as current vectors, and a fixed coordinate system having a common origin with the rotating coordinate system, a sign of a d-axis component of the first warm-up current command value is set so that a direction in which the current vector rotates from a direction related to the first warm-up current command value to a direction related to the second warm-up current command value is the same as a direction in which the rotating coordinate system rotates about the origin relative to the fixed coordinate system as a result of a torque of the motor generated by the second warm-up current command value twisting a shaft that supports the drive wheels and rotating the motor.

8. The method for controlling an electric vehicle according to claim 4, wherein the correction value is varied in a period shorter than a time constant of a temperature change when the switching element generates heat or a time constant of a temperature change when the motor generates heat.

9. 5. The method for controlling an electric vehicle according to claim 4, further comprising the step of estimating the temperature of the inverter and the temperature of the motor based on temperatures of a coolant that cools the inverter and the motor and a detected current value of the motor.

10. A motor that drives an electric vehicle; a controller that calculates a current command value for driving the motor based on a torque command value; a controller for controlling an electric vehicle, the controller generating a first warm-up current command value for increasing a heat generation amount of the motor when a warm-up request is received from an outside, and setting the first warm-up current command value as the current command value, and further setting a d-axis component of the first warm-up current command value so that the motor generates heat based on the warm-up request when the electric vehicle stops, and setting a q-axis component of the first warm-up current command value to substantially zero, The controller: a control system for an electric vehicle that detects that the electric vehicle is stopped and that a braking force is being applied to a drive wheel driven by the motor, and when an overheating condition is predicted to occur in the motor or an electric power system that supplies power to the motor, generates a second warm-up current command value by correcting the current phase of the first warm-up current command value with a predetermined correction value, and sets the second warm-up current command value as the current command value.

Images