Control method for electric vehicle and control device for electric vehicle

Abstract

To provide an electric vehicle control method and an electric vehicle control device in which, when a first electric motor and a winding-field type second electric motor are applied to an electric four-wheel drive vehicle, and the drive torque is output from the first electric motor and the second electric motor is coasted, shock and rattling noise that may occur during reacceleration using the second electric motor are prevented from occurring.SOLUTION: When a first torque command value to a first electric motor is not zero and a second torque command value to a second electric motor is zero, the electric vehicle control method determines whether or not backlash reduction made between the second electric motor and a driving force transmission mechanism is canceled; then, upon determining that the backlash reduction is canceled, outputs a correction torque command value to the second electric motor to maintain the backlash reduction; and outputs a first PWM signal to be outputted to a stator on the basis of the correction torque command value, and simultaneously stop outputting of a second PWM signal to be outputted to a rotor.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] When coasting, the inverter is generally stopped when a wound-field motor is used to control the motor mounted on an electric vehicle. On the other hand, when a permanent magnet motor is used, an induced voltage is generated when the inverter is stopped, which acts as a regenerative brake, so it is known that zero torque control is performed to suppress the induced voltage (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-336647 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a first electric motor and a wound-field type second electric motor are used in an electric four-wheel drive vehicle, and drive torque is output from the first electric motor to coast the second electric motor in order to reduce power consumption, stopping the inverter for the second electric motor generates friction torque in the second electric motor and releases the backlash-eliminated state between the second electric motor and the reducer, etc., resulting in the problem of shocks and gear rattles when accelerating again.

[0005] The present invention aims to provide an electric vehicle control method and an electric vehicle control device that apply a first electric motor and a wound-field type second electric motor to an electric four-wheel drive vehicle, output drive torque from the first electric motor, and suppress the occurrence of shocks and gear rattle noises that occur when re-accelerating using the second electric motor when coasting. [Means for solving the problem]

[0006] A control method for an electric vehicle according to the present invention includes: using a first electric motor and a second electric motor arranged side by side in the longitudinal direction of the vehicle as a drive source of the vehicle; outputting a first torque command value to the first electric motor and a second torque command value to the second electric motor based on vehicle information; the second electric motor being a wound field type and connected to drive wheels via a driving force transmission mechanism; driving the second electric motor by outputting a PWM signal corresponding to the second torque command value to an inverter connected to the second electric motor; and outputting a first PWM signal, which is output to a stator of the second electric motor, and a second PWM signal, which is output to a rotor of the second electric motor. This control method determines whether or not the backlash elimination formed between the second electric motor and the driving force transmission mechanism will be released when the second electric motor applies driving force to the driving force transmission mechanism when the first torque command value is not zero and the second torque command value becomes zero, and if it determines that the backlash elimination will be released, outputs a correction torque command value to the second electric motor to maintain the backlash elimination, outputs a first PWM signal based on the correction torque command value, and stops outputting the second PWM signal. [Effects of the Invention]

[0007] According to the present invention, the second electric motor rotates following the rotation of the driving force transmission mechanism based on the correction torque command value without being rotated by the driving force transmission mechanism, thereby avoiding friction torque and maintaining the eliminated backlash, thereby reducing shock and gear rattle noise during re-acceleration. Furthermore, the correction torque generated by the second electric motor is generated based on the first PWM signal output to the stator, and the second PWM signal output to the rotor is set to zero. Therefore, the field current flowing through the rotor is zero, thereby reducing power consumption. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a system configuration diagram of a control device for an electric vehicle according to this embodiment. [Figure 2]FIG. 2 is a control configuration diagram on the second motor side in the control device for the electric vehicle of this embodiment. [Figure 3] FIG. 3 is a table showing the determination contents of the second motor torque necessity determining section. [Figure 4] FIG. 4 is a table showing the criteria for determining the actual current convergence flag in the current control section. [Figure 5] FIG. 5 is a flowchart of the current control of the second motor in the control device for the electric vehicle of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] [System configuration of electric vehicle control device] 1 is a diagram showing an example of the basic configuration of a control device for an electric vehicle according to the first embodiment. An electric vehicle to which this embodiment is applied has a first motor 7A disposed on one side in the longitudinal direction of the vehicle and a second motor 7B disposed on the other side, with the second motor 7B being a wound field synchronous motor. Meanwhile, the first motor 7A is, for example, a permanent magnet type (or may be a field winding type) synchronous motor.

[0011] The first motor 7A is mechanically coupled to one drive shaft 9A in the longitudinal direction of the electric vehicle via a reduction gear 8A. The second motor 7B is mechanically coupled to the other drive shaft 9B (driving force transmission mechanism) in the longitudinal direction of the electric vehicle via a reduction gear 8A (driving force transmission mechanism). Therefore, drive wheels 10A attached to both ends of the drive shaft 9A are driven by the driving force of the first motor 7A, and drive wheels 10B attached to both ends of the drive shaft 9B are driven by the driving force of the second motor 7B. Note that electric vehicles include not only electric vehicles driven by the first motor 7A and the second motor 7B, but also hybrid vehicles and fuel cell vehicles.

[0012] The battery 1 discharges the driving power of the first motor 7A and the second motor 7B and charges the regenerated power.

[0013] The driving force distribution controller 2 receives vehicle information such as vehicle speed and accelerator opening as digital signals, and calculates a first motor torque command value T1 based on the vehicle information. * and second motor torque command value T2 * In this embodiment, when the required driving torque is small, the first motor torque command value T1 * is set based on the driving torque, and the second motor torque command value T2 * Set to zero.

[0014] The first motor controller 3A outputs a first motor torque command value T1 * Signals of various vehicle variables such as the rotor phase of the first motor 7A and the current (iu, iv, iw) of the first motor 7A are input as digital signals, and a PWM signal that controls the first motor 7A is generated in accordance with the various vehicle variables, and a drive signal for the first inverter 4A is generated through a drive circuit in accordance with this PWM signal.

[0015] The second motor controller 3B outputs a second motor torque command value T2 * The second motor controller 3B receives various vehicle variable signals such as the rotor phase of the second motor 7B, the current (iu, iv, iw, if) of the second motor 7B, etc. as digital signals, generates a PWM signal to control the second motor 7B in accordance with the various vehicle variables, and generates a drive signal for the second inverter 4B through a drive circuit in accordance with the PWM signal. * The second motor correction torque command value T comp * Used as a criterion for outputting.

[0016] The first inverter 4A and the second inverter 4B are configured, for example, with two switching elements (for example, power semiconductor elements such as IGBTs and MOS-FETs) for each phase, and by turning the switching elements ON / OFF in response to a PWM (Pulse Width Modulation)_Duty drive signal (PWM signal), the DC current supplied from the battery 1 is converted to AC for the stator and inversely converted, and the desired current is passed through the first motor 7A and the second motor 7B.

[0017] The first motor 7A generates driving force from the AC current supplied to the stator by the first inverter 4A, and transmits the driving force to the drive wheels 10A via the speed reducer 8A and the drive shaft 9A. When the first motor 7A rotates along with the drive wheels 10A while the vehicle is running, it generates regenerative driving force, thereby recovering the kinetic energy of the vehicle as electrical energy.

[0018] The second motor 7B generates driving force using AC current supplied to the stator by the second inverter 4B and DC current supplied to the rotor, and transmits the driving force to the drive wheels 10B via the speed reducer 8B and the drive shaft 9B (driving force transmission mechanism). When the second motor 7B rotates along with the drive wheels 10B while the vehicle is running, it generates regenerative driving force, thereby recovering the kinetic energy of the vehicle as electrical energy.

[0019] In addition, there are provided a current sensor 5A that detects each phase current of the first motor 7A, a rotation sensor 6A (resolver or encoder) that detects the rotor phase of the first motor 7A, a current sensor 5B (and current sensor 106 shown in Figure 2) that detects each phase current of the second motor 7B, and a rotation sensor 6B (resolver or encoder) that detects the rotor phase of the second motor 7B.

[0020] [Control configuration of electric vehicle control device] FIG. 2 is a control configuration diagram on the side of the second motor 7B in the control device for the electric vehicle of this embodiment.

[0021] The second motor 7B is a wound-field synchronous motor. When the control device is applied to an electric vehicle, the second motor 7B serves as a drive source for the vehicle.

[0022] The PWM converter 102 generates a three-phase voltage command value v u * ,v v * ,v w * Based on this, the PWM_Duty drive signal D of the switching element (IGBT, etc.) of the second inverter 4B of the three-phase voltage type is uu * ,D ul * ,D vu * ,D vl * ,D wu * ,D wl * (first PWM signal) is generated. Then, the field voltage command value v f * Based on this, the PWM_Duty drive signal D of the switching element (IGBT, etc.) of the field current output unit 105 is fu * ,D fl * (second PWM signal).

[0023] Furthermore, the PWM converter 102 sets each PWM_Duty drive signal (duty ratio of the first PWM signal and the second PWM signal) to 0% (gate off) according to the rotor gate off flag ("1") and the stator gate off flag ("1") described below.

[0024] Furthermore, the PWM converter 102 changes the stator carrier frequency for generating a PWM_Duty drive signal (first PWM signal) for the stator, using a stator carrier frequency signal described later.

[0025] The second inverter 4B converts the DC voltage V output from the battery 1 into a dcを AC voltage v u ,v v,v w and supplied to the stator windings of the second motor 7B.

[0026] The battery 1 is, for example, a stacked lithium ion battery.

[0027] The field current output unit 105 (which may be integrated with the second inverter 4B) outputs the DC voltage V output from the battery 1 based on the PWM_Duty drive signal generated by the PWM converter 102. dc The field voltage V f and supplies it to the rotor winding of the second motor 7B. In this way, the stator winding and the rotor winding are supplied with power from the common battery 1.

[0028] The current sensor 5B detects at least two phases of current (for example, u-phase current i) of the three-phase AC current supplied from the second inverter 4B to the stator of the second motor 7B. u , v phase current i v ) is detected. The detected two-phase current (u-phase current i u ,v phase current i v ) is converted into a digital signal (i us ,i ws ) and input to the three-phase / dq AC coordinate converter 112. When the current sensor 5B is attached to only two phases, the w-phase current iws of the remaining phase can be found by the following equation (1).

number

[0029] The current sensor 106 detects the field current i supplied from the field current output unit 105 to the rotor winding of the second motor 7B. f The detected field current value i f is converted into a digital signal (i fs )

[0030] The rotation sensor 6B (magnetic pole position detector) outputs A-phase, B-phase, and Z-phase pulses according to the rotor position (angle) of the second motor 7B.

[0031] The pulse counter 109 calculates the electrical angle θ, which indicates the rotor position (angle), based on the pulses output from the rotation sensor 6B. re Calculate.

[0032] The angular velocity calculator 110 calculates the electrical angle θ re and calculate the electrical angular velocity ω from the time rate of change. re , and electrical angular velocity ω re Divide by the number of motor pole pairs p to get the rotation speed N (mechanical angular velocity ω m ) is found.

number

number

[0033] The look-ahead compensation unit 111 calculates the electrical angle θ re and electrical angular velocity ω re Enter the electrical angle θ re With respect to the electrical angular velocity ω re and the dead time t of the control system comp The calculated value is multiplied by the calculated value to obtain the electrical angle θ after look-ahead compensation. re ' is required.

number

[0034] The three-phase / dq AC coordinate converter 112 converts a three-phase AC coordinate system (a fixed coordinate system having uv and w axes) into an orthogonal two-axis DC coordinate system (a rotating coordinate system having d and q axes that rotate in synchronization with the rotation of the rotor). Specifically, the u-phase current i us , v phase current i vs and electrical angle θ re and calculate the d-axis current detection value i d , q-axis current detection value i q Calculate.

number

[0035] The current control unit 113 uses general PI control and non-interference control to calculate the d-axis current command value i d * , q-axis current command value i q * , field current command value i f * Then, the measured (actual) d-axis current detection value i d , q-axis current detection value i q , field current detection value i f The current control unit 113 outputs the d-axis voltage command value v d * , q-axis voltage command value v q * , field voltage command value v f * Output.

[0036] In addition, the current control unit 113 determines whether the actual current (current detection value) converges to within a certain value with respect to the current command value according to the condition table shown in FIG. 4 (details of which will be described later), and sets an actual current convergence flag, which will be described later.

[0037] The dq / three-phase AC coordinate converter 114 converts the electrical angular velocity ω re The orthogonal two-axis DC coordinate system (dq axes) rotating at θ is transformed into a three-phase AC coordinate system (uvw axes). Specifically, the d-axis voltage command value v d * , q-axis voltage command value v q * and the electrical angle θ after look-ahead compensation re ' is input, and the coordinate transformation process is performed using the following equation (6) to obtain the three-phase voltage command value v u * ,v v * ,v w * is calculated and output.

number

[0038] The current command value calculation unit 115 calculates the second motor torque command value T2* , rotation speed N, DC voltage V dc is input, and the d-axis current command value i is calculated by referring to the current map obtained in advance through experiments, taking into account the magnet torque and reluctance torque. d_mngt * , q-axis current command value i q_mngt * , field current command value i f_mngt * These current command values ​​are used to request drive torque (positive torque and negative torque) from the second motor 7B.

[0039] The second motor torque necessity determination unit 116 determines the first motor torque command value T1 * , second motor torque command value T2 * , and the rotation speed N are input, and as shown in FIG. 3 (details will be described later), the stator gate off flag, rotor gate off flag, second motor torque correction necessity flag, second motor correction torque coefficient K t_comp , and the stator carrier frequency signal is set. This determination is made only when the actual current convergence flag, which will be described later, is set.

[0040] The second motor correction torque calculation unit 117 calculates the second motor correction torque coefficient K t_comp , the rotation speed N is input, and the second motor correction torque command value T is calculated based on the following equation (7): comp * where T frct (N) is the friction torque of the second motor 7B according to the rotation speed N, and T bcklsh is a torque for keeping the backlash of the reducer 8B eliminated, which was previously set through experiments.

number

[0041] The second motor correction current command value calculation unit 118 calculates the second motor correction torque command value T comp * and rotation speed N, DC voltage V dcis input, and the current map for outputting the reluctance torque obtained in advance through experiments is referenced, and the d-axis correction current command value i d_rlct * , q-axis correction current command value i q_rlct * , field correction current command value i f_rlct * Here, the field correction current command value i f_rlct * is 0.

[0042] Furthermore, the current command value for a synchronous motor is generally Id<0, Iq>0 during powering in the field-weakening region, which cancels out the induced voltage from the rotor, and Id<0, Iq<0 during regeneration. However, the characteristics of a wound-field synchronous motor are such that the magnet torque cancels out the reluctance torque in the field-weakening region, so in the region where you want to use only the reluctance torque, if you use the current command value as described above, the sign of the torque will be reversed. Therefore, in the region where you want to use only the reluctance torque, the second motor correction torque command value T comp * is positive (second motor correction torque coefficient K t_comp If is "1" (Figure 3), then i d_rlct * , i q_rlct * The current command values ​​are set so that the signs of the second motor correction torque command value T comp * is negative (second motor correction torque coefficient K t_comp is "-1" (Fig. 3), the current command values ​​are set so that their signs are different from each other.

[0043] The torque T generated by the second motor 7B is calculated as shown in the following equation (8).

number

[0044] Here, the first term of equation (8) (p×i q×φ) is the magnet torque, and the second term (p×(L q -L d )×i d ×i q ) is the reluctance torque. Also, p is the number of pole pairs of the stator, Lq is the q-axis reluctance, and Ld is the d-axis reluctance. Furthermore, φ is the rotor magnetic flux, and the field current (field current detection value i f ) is zero. Therefore, for example, in equations (7) and (8), T comp * =T, φ=0, and the d-axis current detection value i d = d-axis current command value i d * and the q-axis current detection value i q = q-axis current command value i q * Furthermore, T and the d-axis current command value i d * , q-axis current command value i q * By using a table showing the relationship between the magnitude of the d-axis current command value i d * , q-axis current command value i q * The size can be calculated.

[0045] When the second motor torque correction necessity flag is "necessary" (for example, a 1-bit signal "1"), the current command value switching unit 119 switches the output (i d_rlct * , i q_rlct * , i f_rict * ) are the d-axis current command values ​​i d * , q-axis current command value i q * , field current command value i f * to the current control unit 113.

[0046] Further, when the second motor torque correction necessity flag is "No" (for example, a 1-bit signal "0"), the current command value switching unit 119 switches the output (id_mngt * , i q_mngt * , i f_mngt * ) are the d-axis current command values ​​i d * , q-axis current command value i q * , field current command value i f * to the current control unit 113.

[0047] [Second motor torque necessity determination unit 116] FIG. 3 is a table showing the determination contents of the second motor torque necessity determining section 116. In FIG.

[0048] As shown in FIG. 3, the second motor torque command value T2 * is a value other than 0, the second motor torque necessity determination unit 116 determines the rotation speed N of the second motor 7B and the first motor torque command value T1 * Regardless of the value of T2, the stator gate-off flag and rotor gate-off flag are set to "Do not gate-off" (1-bit signal "0", the same notation will be used below), the second motor torque correction necessity flag is set to "No" ("0"), and the stator carrier frequency is set to 10 [kHz]. As a result, the second motor 7B is driven according to the second motor torque command value T2 * The drive torque is output based on the

[0049] Second motor torque command value T2 * is zero, the rotation speed N is positive (the rotation direction (positive rotation) of the second motor 7B when the electric vehicle moves forward), and the first motor torque command value T1 * Let us consider the case where is positive (positive torque that generates forward acceleration of the electric vehicle).

[0050] In this case, the reducer 8B rotates in the positive direction relative to the second motor 7B (which is rotating in the positive direction due to inertial force) as a reference, and therefore the backlash elimination in the positive direction is released.

[0051] Here, "eliminating backlash in the positive direction" refers to a state in which, when the electric vehicle is moving forward and positive torque is being applied to the reducer 8B by the first motor 7A, a positive torque, which is a torque in the same direction as the vehicle acceleration, is applied to the second motor 7B, thereby eliminating backlash in the positive direction between the second motor 7B and the reducer 8B. Also, at this time, the second motor 7B and the reducer 8B are rigidly engaged as long as the second motor 7B transmits positive torque to the reducer 8B.

[0052] The reducer 8B then rotates relative to the second motor 7B in the forward direction by an amount equal to the backlash, thereby again engaging with the second motor 7B. In this case, the second motor 7B is rotated by the reducer 8B and generates a friction torque on the reducer 8B side in a direction that prevents the electric vehicle from accelerating forward.

[0053] Therefore, the second motor torque necessity determination unit 116 sets the stator gate-off flag to "not gate-off", the rotor gate-off flag to "gate-off" ("1"), the second motor torque correction necessity flag to "necessary" ("1"), and the second motor torque correction torque coefficient K t_comp Set to "1" and set the stator carrier frequency to 5 [kHz].

[0054] As a result, the second motor 7B rotates in the forward direction following the forward rotation of the reducer 8B without being rotated by the reducer 8B due to the correction torque (positive torque), thereby avoiding friction torque and further maintaining the elimination of backlash in the forward direction, thereby reducing shock and rattle noise when the electric vehicle is re-accelerated in the forward direction.

[0055] The correction torque is the d-axis current command value i d * , q-axis current command value i q * The field current command value i f * is set to substantially zero (the second PWM signal is gated off in the PWM converter 102). Therefore, power consumption can be reduced by the amount that the field current is not used.

[0056] Furthermore, the stator carrier frequency (5 kHz) of the PWM signal when generating the correction torque is set lower than the stator carrier frequency (10 kHz) of the PWM signal when generating the drive torque (positive torque, negative torque). This reduces the switching loss of the switching elements of the second inverter 4B when generating the correction torque, thereby reducing power consumption.

[0057] Second motor torque command value T2 * is zero, the rotation speed N is positive (forward rotation) and the first motor torque command value T1 * is a negative torque (a negative torque that applies acceleration to the electric vehicle in a direction that causes the electric vehicle to move backward, a negative torque that allows regenerative power to be extracted from the first motor 7A while the rotation speed N is positive), the second motor 7B applies an inertial force (a force that tries to rotate in the positive direction) to the reducer 8B, so that the positive direction backlash is maintained. Therefore, since there is no need for the second motor torque necessity determination unit 116 to generate correction torque, the second motor torque necessity determination unit 116 sets the stator gate off flag and the rotor gate off flag to "do not gate off" ("0"), sets the second motor torque correction necessity flag to "no" ("0"), and sets the stator carrier frequency to 5 [kHz] (the carrier wave may be stopped).

[0058] Second motor torque command value T2 * is zero, the rotation speed N is positive (forward rotation) and the first motor torque command value T1 * If is zero, the second motor torque necessity determining unit 116 maintains the previous values ​​of each flag and the stator carrier frequency.

[0059] Second motor torque command value T2 * is zero, the rotation speed N is negative (the rotation direction (reverse rotation) of the second motor 7B when the electric vehicle moves backward), and the first motor torque command value T1 * Let us consider a case where the torque is positive (a positive torque that allows regenerative power to be extracted from the first motor 7A while the rotation speed N is negative).

[0060] In this case, initially, the reducer 8B and the second motor 7B are rotating in the reverse direction, and the second motor 7B rotates in the forward direction relative to the reducer 8B, so the release of the backlash elimination in the forward direction does not occur. Therefore, since there is no need for the second motor torque necessity determination unit 116 to generate correction torque, the second motor torque necessity determination unit 116 sets the stator gate-off flag and the rotor gate-off flag to "do not gate-off" ("0"), sets the second motor torque correction necessity flag to "no" ("0"), and sets the stator carrier frequency to 5 kHz (the carrier wave may be stopped).

[0061] However, when the reducer 8B subsequently begins to rotate in the forward direction, the second motor 7B rotates relative to the reducer 8B in the negative direction (the reducer 8B rotates relative to the second motor 7B in the positive direction), causing the positive direction backlash removal to be released. The second motor 7B then rotates relative to the reducer 8B in the negative direction by an amount equal to the backlash, thereby again engaging with the reducer 8B. In this case, the second motor 7B is rotated by the reducer 8B and generates a friction torque toward the reducer 8B in a direction that hinders acceleration in the forward direction of the electric vehicle.

[0062] Therefore, the second motor torque necessity determination unit 116 sets the stator gate-off flag to "not gate-off", the rotor gate-off flag to "gate-off" ("1"), the second motor torque correction necessity flag to "necessary" ("1"), and the second motor torque correction torque coefficient K t_comp Set to "1" and set the stator carrier frequency to 5 [kHz].

[0063] Second motor torque command value T2 * is zero, the rotation speed N is negative, and the first motor torque command value T1 * When the value is negative, the reducer 8B rotates in the negative direction relative to the second motor 7B (which is rotating in the reverse direction due to inertia), so that the elimination of backlash in the positive direction is maintained, but the elimination of backlash in the negative direction is released.

[0064] Here, eliminating backlash in the negative direction refers to a state in which, when the electric vehicle is moving backward and negative torque is being applied to the reducer 8B by the first motor 7A, negative torque is applied to the second motor 7B, thereby eliminating backlash in the negative direction between the second motor 7B and the reducer 8B.

[0065] The reducer 8B then rotates relative to the second motor 7B in the negative direction by an amount equal to the backlash, thereby again engaging with the second motor 7B. In this case, the second motor 7B is rotated by the reducer 8B and generates a friction torque toward the reducer 8B in a direction that prevents the electric vehicle from accelerating backward.

[0066] Therefore, the second motor torque necessity determination unit 116 sets the stator gate-off flag to "not gate-off", the rotor gate-off flag to "gate-off" ("1"), the second motor torque correction necessity flag to "necessary" ("1"), and the second motor torque correction torque coefficient K t_comp Set to "-1" and set the stator carrier frequency to 5 [kHz].

[0067] As a result, the second motor 7B rotates in the reverse direction following the reverse rotation of the reducer 8B without being rotated by the reducer 8B due to the correction torque (negative torque), thereby avoiding friction torque and further maintaining clearance in the negative direction, thereby reducing shock and rattle noise when the electric vehicle accelerates again in the backward direction.

[0068] Second motor torque command value T2 * is zero, the rotation speed N is in the negative direction, and the first motor torque command value T1 * If is zero, the second motor torque necessity determining unit 116 maintains the previous values ​​of each flag and the stator carrier frequency.

[0069] Second motor torque command value T2 *is zero and the rotation speed N is zero, the second motor 7B and the reducer 8B do not rotate, so there is no need to eliminate backlash. Therefore, the second motor torque necessity determination unit 116 does not need to generate correction torque, so it sets the stator gate-off flag and the rotor gate-off flag to "do not gate-off" ("0"), sets the second motor torque correction necessity flag to "no" ("0"), and sets the stator carrier frequency to 5 [kHz] (the carrier wave may be stopped).

[0070] [Actual current convergence flag] 4 is a table showing the criteria for determining the actual current convergence flag in the current control unit 113. The current control unit 113 outputs the actual current convergence flag by determining whether the actual current flowing through the second motor 7B has converged to the command value. Specifically, the current control unit 113 outputs the actual current convergence flag by determining whether the d-axis current command value i d * and the d-axis current detection value i d The difference between the q-axis current command value i q * and the q-axis current detection value i q The difference between the field current command value i f * and the field current detection value i f When the actual current is lower than the command value, the actual current convergence flag is generated, and the difference between the actual current and the command value is calculated. This reduces the sudden torque change when the vehicle transitions from a normal driving state to a state where the second motor 7B outputs a correction torque, thereby reducing the shock to the vehicle.

[0071] As shown in FIG. 4, the current control unit 113 controls the d-axis current command value i d * and the d-axis current detection value i d The difference between the q-axis current command value i and the q-axis current command value i is less than 10 [A] (D1). q * and the q-axis current detection value i q The difference between the field current command value i and the field current command value i is less than 10 [A] (Q1). f * and the field current detection value i fConsidering the condition (F1) that the difference between and is less than 1 [A], if all conditions are met simultaneously, that is, when "D1∩Q1∩F1" is met, the actual current convergence flag is set to "1".

[0072] On the other hand, if any one of the above conditions is not satisfied, the actual current convergence flag is set to "0." For example, when the d-axis current command value i d * and the d-axis current detection value i d The difference between the q-axis current command value i and the q-axis current command value i is 10 [A] or more (D2). q * and the q-axis current detection value i q The difference between the field current command value i and the field current command value i is 10 [A] or more (Q2). f * and the field current detection value i f Considering the condition (F2) that the difference between and is 1 [A] or more, if either condition is met, that is, when "D2 ∪ Q2 ∪ F2" is met, the actual current convergence flag is set to "0".

[0073] The second motor torque necessity determination unit 116 sets the second motor torque correction necessity flag to "No" ("0") when the actual current convergence flag is "0", and sets the second motor torque correction necessity flag to "Needed" ("1") when the actual current convergence flag is "1".

[0074] [flowchart] FIG. 5 is a flowchart of the current control of the second motor 7B in the control device for an electric vehicle of this embodiment.

[0075] In step S501, the second motor torque necessity determination unit 116 sets the second motor torque command value T2 * Detects that has become zero.

[0076] In step S502, the current control unit 113 waits until the actual current converges to the vicinity of the command value, and outputs the actual current convergence flag "1" when the actual current converges.

[0077] In step S503, the second motor torque necessity determination unit 116 determines whether or not correction torque is necessary. If the second motor torque necessity determination unit 116 determines that correction torque is necessary (YES), the process proceeds to step S504, and if the second motor torque necessity determination unit 116 determines that correction torque is not necessary (NO), the process proceeds to step S505.

[0078] Here, a correction torque is required when the first motor 7A outputs positive torque and the second motor 7B and the reducer 8B are rotating in the forward direction, or when the first motor 7A outputs negative torque and the second motor 7B and the reducer 8B are rotating in the reverse direction (Figure 3).

[0079] In step S504, the second motor torque necessity determination unit 116 outputs a rotor gate-off flag ("1") to the PWM converter 102. As a result, the PWM converter 102 gates off (stops transmission of) the component (second PWM signal) of the PWM_Duty drive signal that is output to the rotor.

[0080] In step S505, the second motor torque necessity determination unit 116 outputs the rotor gate-off flag ("1") and the stator gate-off flag ("1") to the PWM converter 102 and proceeds to "End." This causes the PWM converter 102 to gate-off (stop transmission) all of the PWM_Duty drive signals (first PWM signal, second PWM signal).

[0081] In step S506, the second motor torque necessity determining unit 116 outputs the stator carrier frequency signal (5 [kHz]) to the PWM converter 102. The PWM_Duty drive signal (first PWM signal) to be output to the stator is generated using a carrier wave with a stator carrier frequency of 5 [kHz].

[0082] In step S507, the second motor correction torque calculation unit 117 calculates the second motor correction torque command value T comp *At this time, the second motor torque necessity determination unit 116 calculates the second motor correction torque coefficient K based on the rotation direction of the rotation speed N of the second motor 7B (equation (7)). t_comp is set and output to the second motor correction torque calculation unit 117. Here, the second motor correction torque coefficient K t_comp is "1" when the rotation speed N is in the forward direction, and is "-1" when the rotation speed N is in the reverse direction. t_comp ) may be set by the second motor correction torque calculation unit 117.

[0083] In step S508, the second motor correction current command value calculation unit 118 calculates the second motor correction torque command value T comp * The positive or negative sign of the second motor correction torque coefficient K t_comp ) to determine whether or not it is necessary to output positive torque from the second motor 7B, and if it is determined that it is necessary (YES), the process proceeds to step S509, and if it is determined that it is not necessary (NO), the process proceeds to step S510.

[0084] In step S509, the second motor correction current command value calculation unit 118 calculates the d-axis correction current command value i d_rlct * , q-axis correction current command value i q_rlct * , field correction current command value i f_rlct * At this time, the d-axis correction current command value i d_rlct * and the q-axis correction current command value i q_rlct * The product of these is positive, i.e., the d-axis correction current command value i d_rlct * and the q-axis correction current command value i q_rlct * are calculated so that they have the same sign.

[0085] In step S510, the second motor correction current command value calculation unit 118 calculates the d-axis correction current command value i d_rlct * , q-axis correction current command value i q_rlct * , field correction current command value if_rlct * At this time, the d-axis correction current command value i d_rlct * and the q-axis correction current command value i q_rlct * The product of these is negative, i.e., the d-axis correction current command value i d_rlct * and the q-axis correction current command value i q_rlct * are calculated so that they have different signs.

[0086] In steps S509 and S510, second motor torque necessity determination unit 116 outputs the second correction torque necessity flag ("1") to current command value switching unit 119 and proceeds to "End." As a result, current command value switching unit 119 switches the input destination of the current command value from current command value calculation unit 115 to second motor correction current command value calculation unit 118.

[0087] [Effects of this embodiment] According to the control method for an electric vehicle of this embodiment, a first electric motor (first motor 7A) and a second electric motor (second motor 7B) arranged side by side in the longitudinal direction of the vehicle are used as drive sources for the vehicle, and a first torque command value (first motor torque command value T1) is sent to the first electric motor (first motor 7A) based on vehicle information (vehicle speed, accelerator opening, etc.). * ) and outputs a second torque command value (second motor torque command value T2 * a second electric motor (second motor 7B) being a wound field type and connected to drive wheels 10B via a driving force transmission mechanism (a reduction gear 8B, a drive shaft 9B), a PWM signal corresponding to the second torque command value being output to an inverter (second inverter 4B) connected to the second electric motor to drive the second electric motor, and a PWM signal (PWM_Duty drive signal) including a first PWM signal output to a stator of the second electric motor (second motor 7B) and a second PWM signal output to a rotor of the second electric motor (second motor 7B), * ) is not zero and the second torque command value (second motor torque command value T2* ) becomes zero, the second motor (second motor 7B) applies a driving force (positive torque, negative torque) to the driving force transmission mechanism (reduction gear 8B, drive shaft 9B), the second motor (second motor 7B) determines whether or not the backlash elimination formed between the second motor (second motor 7B) and the driving force transmission mechanism (reduction gear 8B, drive shaft 9B) is released, and if it is determined that the backlash elimination is released, the second motor (second motor 7B) is directed to the second motor (second motor 7B) to maintain the backlash elimination. comp * ) and outputs the correction torque command value (second motor correction torque command value T comp * ) the first PWM signal is output and the output of the second PWM signal is stopped.

[0088] By the above method, the second electric motor (second motor 7B) is controlled to generate a correction torque command value (second motor correction torque command value T comp * ), it rotates following the rotation of the drive force transmission mechanism (reduction gear 8B, drive shaft 9B) without being pulled around by the drive force transmission mechanism (reduction gear 8B, drive shaft 9B), thereby avoiding friction torque and maintaining clearance, thereby reducing shock and gear rattle noise when re-accelerating. In addition, the correction torque generated by the second electric motor (second motor 7B) is generated based on the first PWM signal output to the stator, and the second PWM signal output to the rotor is set to zero. As a result, the field current flowing through the rotor is zero, thereby reducing power consumption accordingly.

[0089] In this embodiment, the first torque command value (first motor torque command value T1 * ) is a positive torque command value (first motor torque command value T1 * ), and a negative torque command value (first motor torque command value T1 * ), and the correction torque command value (second motor correction torque command value T comp * ) is the first torque command value (first motor torque command value T1* ) is the positive torque command value (the first motor torque command value T1 * ) and the vehicle is moving forward, the first correction torque command value (the second motor correction torque command value T comp * ) and the first torque command value (first motor torque command value T1 * ) is the negative torque command value (the first motor torque command value T1 * ) and the second correction torque command value (the second motor correction torque command value T comp * ) and includes.

[0090] By the above method, the correction torque command value (second motor correction torque command value T comp * ) can be output.

[0091] In this embodiment, the PWM signal (PWM_Duty drive signal) is converted into a correction torque command value (second motor correction torque command value T comp * ) and the current command value is calculated based on a d-axis current command value i d * and q-axis current command value i q * The first correction torque command value (the second motor correction torque command value T comp * ) when generating the current command value based on the d-axis current command value i d * and q-axis current command value i q * The positive and negative signs of the second motor correction torque command value T comp * ) when generating the current command value based on the d-axis current command value i d * and q-axis current command value iq * are set so that their positive and negative signs are different from each other.

[0092] The above method allows for a simple calculation of the first correction torque command value (the second motor correction torque command value T comp * ) and the second correction torque command value (the second motor correction torque command value T comp * ) can be generated.

[0093] In this embodiment, the correction torque command value (second motor correction torque command value T comp * ) when calculating the current command value based on the d-axis current command value i d * and q-axis current command value i q * The magnitudes of the respective values ​​are calculated based on the rotation speed N of the second electric motor (second motor 7B).

[0094] This allows for a simple method to obtain the d-axis current command value i d * and q-axis current command value i q * The magnitude of can be calculated.

[0095] In this embodiment, a PWM signal is generated based on a predetermined carrier frequency, and a correction torque command value (second motor correction torque command value T comp * When the PWM signal is generated based on the torque command value, the carrier frequency is set to a frequency lower than the carrier frequency when the PWM signal is generated based on the second torque command value.

[0096] By using the above method, it is possible to reduce the switching loss occurring in the switching elements of the inverter (second inverter 4B), thereby reducing the power consumption.

[0097] In this embodiment, the first torque command value (first motor torque command value T1 *) is the negative torque command value (the first motor torque command value T1 * ) and the vehicle is moving forward, or when the first torque command value (first motor torque command value T1 * ) is the positive torque command value (the first motor torque command value T1 * ) and the vehicle is moving backward, it is determined that the release of the backlash elimination will not occur, and the output of the first PWM signal and the second PWM signal is stopped.

[0098] According to the above method, if backlash elimination is maintained even when the second torque command value becomes zero, power consumption can be reduced by stopping (gating off) the output of the first PWM signal and the second PWM signal.

[0099] In this embodiment, the current command value is a field current command value i f * and a first torque command value (first motor torque command value T1 * ) is not zero and the second torque command value (second motor torque command value T2 * ) becomes zero, the d-axis current command value i d * and the d-axis current detection value i obtained by converting the three-phase AC current flowing through the stator into dq-axis coordinates. d The difference between the q-axis current command value i q * and the q-axis current detection value i obtained by converting the three-phase AC current into dq-axis coordinates. q The difference between the field current command value i f * and the detected field current value i flowing through the rotor f When the difference between the first motor and the second motor becomes smaller than a predetermined value, the correction torque command value (second motor correction torque command value T comp * ) is outputted to the second electric motor (second motor 7B).

[0100] The above method reduces the sudden torque change that occurs when the vehicle transitions from a normal driving state to a state in which the second electric motor (second motor 7B) outputs correction torque, thereby reducing the shock that occurs to the vehicle.

[0101] According to the control device for an electric vehicle of this embodiment, a first torque command value (first motor torque command value T1) is calculated based on vehicle information (vehicle speed, accelerator opening, etc.) and is disposed on one side of the vehicle in the front-rear direction. * ) and a second electric motor (first motor 7A) that is arranged on the other side of the vehicle in the longitudinal direction and is driven based on a second torque command value (second motor torque command value T2 * ), a driving force transmission mechanism (reduction gear 8B, drive shaft 9B) that transmits the driving force of the second electric motor (second motor 7B) to the driving wheels 10B, an inverter (second inverter 4B) connected to the second electric motor (second motor 7B), and a second torque command value (second motor torque command value T2 * and a PWM converter 102 that generates a PWM signal (PWM_Duty drive signal) based on the first torque command value (first motor torque command value T1) and outputs the PWM signal (PWM_Duty drive signal) to an inverter (second inverter 4B), the PWM signal (PWM_Duty drive signal) including a first PWM signal that is output to a stator of a second electric motor (second motor 7B) and a second PWM signal that is output to a rotor of the second electric motor (second motor 7B), * ) is not zero and the second torque command value (second motor torque command value T2 * ) becomes zero, the second motor (second motor 7B) applies a driving force to the driving force transmission mechanism (reduction gear 8B, drive shaft 9B), the second motor (second motor 7B) determines whether or not the backlash elimination formed between the second motor (second motor 7B) and the driving force transmission mechanism (reduction gear 8B, drive shaft 9B) is released, and if it is determined that the backlash elimination is released, the second motor (second motor 7B) is directed to the second motor (second motor 7B) to maintain the backlash elimination. comp * ) and the correction torque necessity determination means (second motor torque necessity determination unit 116) commands the output of the correction torque command value (second motor correction torque command value T comp *) is commanded, the correction torque command value (second motor correction torque command value T comp * and a correction torque calculation unit (second motor correction torque calculation unit 117) that calculates the correction torque command value (second motor correction torque command value T comp * ) output, the correction torque command value (second motor correction torque command value T comp * ) the first PWM signal is output and the output of the second PWM signal is stopped.

[0102] With the above configuration, the second electric motor (second motor 7B) is driven by the correction torque command value (second motor correction torque command value T comp * ), it rotates following the rotation of the drive force transmission mechanism (reduction gear 8B, drive shaft 9B) without being pulled around by the drive force transmission mechanism (reduction gear 8B, drive shaft 9B), thereby avoiding friction torque and maintaining clearance, thereby reducing shock and gear rattle noise when re-accelerating. In addition, the correction torque generated by the second electric motor (second motor 7B) is generated based on the first PWM signal output to the stator, and the second PWM signal output to the rotor is set to zero. As a result, the field current flowing through the rotor is zero, thereby reducing power consumption accordingly.

[0103] 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 the technical scope of the present invention is not intended to be limited to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of symbols]

[0104] 4B second inverter, 7A first motor, 7B second motor, 8B reducer, 9B drive shaft, 10B drive wheel, 102 PWM converter, 116 second motor torque necessity determination unit, 117 second motor correction torque calculation unit

Claims

1. a first torque command value output to the first electric motor and a second torque command value output to the second electric motor based on vehicle information; the second electric motor being a wound field type and connected to drive wheels via a driving force transmission mechanism; a PWM signal corresponding to the second torque command value output to an inverter connected to the second electric motor to drive the second electric motor; and the PWM signal being a first PWM signal output to a stator of the second electric motor and a second PWM signal output to a rotor of the second electric motor, when the first torque command value is not zero and the second torque command value becomes zero, determining whether or not backlash elimination formed between the second electric motor and the driving force transmission mechanism will be released when the second electric motor applies driving force to the driving force transmission mechanism, and outputting a correction torque command value to the second electric motor for maintaining the backlash elimination when it is determined that the backlash elimination will be released; a control method for an electric vehicle, the control method including outputting the first PWM signal and stopping output of the second PWM signal based on the correction torque command value;

2. the first torque command value includes a positive torque command value that generates acceleration in a direction that moves the vehicle forward, and a negative torque command value that generates acceleration in a direction that moves the vehicle backward, 2. The control method for an electric vehicle according to claim 1, wherein the correction torque command value includes a first correction torque command value that is set when the first torque command value is set to the positive torque command value and the vehicle is moving forward, and a second correction torque command value that is set when the first torque command value is set to the negative torque command value and the vehicle is moving backward.

3. calculating the PWM signal based on a current command value calculated based on the corrected torque command value; the current command value includes a d-axis current command value and a q-axis current command value that are expressed in dq-axis coordinates that rotate in synchronization with rotation of the rotor and are used to generate the first PWM signal, When generating the current command value based on the first correction torque command value, the d-axis current command value and the q-axis current command value are set to have the same positive or negative sign, and 3. The method for controlling an electric vehicle according to claim 2, wherein when the current command value is generated based on the second correction torque command value, the d-axis current command value and the q-axis current command value are set to have different positive and negative signs.

4. 4. The control method for an electric vehicle according to claim 3, wherein when the current command value is calculated based on the corrected torque command value, the magnitudes of the d-axis current command value and the q-axis current command value are each calculated based on a rotation speed of the second electric motor.

5. generating the PWM signal based on a predetermined carrier frequency; 5. The control method for an electric vehicle according to claim 1, wherein the carrier frequency is set to a frequency lower than the carrier frequency when the PWM signal is generated based on the second torque command value, when the PWM signal is generated based on the correction torque command value.

6. 3. The method for controlling an electric vehicle according to claim 2, wherein it is determined that the release of the backlash elimination will not occur and output of the first PWM signal and the second PWM signal is stopped when the first torque command value is set to the negative torque command value and the vehicle is moving forward, or when the first torque command value is set to the positive torque command value and the vehicle is moving backward.

7. the current command value further includes a field current command value for generating the second PWM signal, When the first torque command value is not zero and the second torque command value is zero, 5. The method for controlling an electric vehicle according to claim 3, wherein the correction torque command value is output to the second electric motor when each of a difference between the d-axis current command value and a d-axis current detection value obtained by converting the three-phase AC current flowing through the stator into the dq-axis coordinates, a difference between the q-axis current command value and a q-axis current detection value obtained by converting the three-phase AC current into the dq-axis coordinates, and a difference between the field current command value and the field current detection value flowing through the rotor becomes smaller than a predetermined value.

8. a first electric motor disposed on one side of the vehicle in a front-rear direction and driven based on a first torque command value calculated based on vehicle information; a second electric motor arranged on the other side of the vehicle in the front-rear direction and driven based on a second torque command value calculated based on the vehicle information; a driving force transmission mechanism that transmits the driving force of the second electric motor to driving wheels; an inverter connected to the second motor; a PWM conversion means for generating a PWM signal based on the second torque command value and outputting the PWM signal to the inverter, a control device for an electric vehicle, wherein the PWM signal includes a first PWM signal outputted to a stator of the second electric motor and a second PWM signal outputted to a rotor of the second electric motor, a correction torque necessity determination means for determining whether or not backlash elimination formed between the second electric motor and the driving force transmission mechanism will be released when the second electric motor applies driving force to the driving force transmission mechanism when the first torque command value is not zero and the second torque command value becomes zero, and for instructing the second electric motor to output a correction torque command value for maintaining the backlash elimination when it is determined that the backlash elimination will be released; a correction torque calculation unit that, when the correction torque necessity determination unit issues a command to output the correction torque command value, calculates the correction torque command value based on the rotation speed of the second electric motor and outputs the correction torque command value to the PWM conversion unit, The PWM conversion means a control device for an electric vehicle that, when the correction torque necessity determination means commands output of the correction torque command value, outputs the first PWM signal based on the correction torque command value and stops output of the second PWM signal.

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