JP2024100055A - Motor Control Device - Google Patents

Abstract

To provide a motor control device that can improve responsiveness to required torque based on operation of an accelerator pedal by a driver in an electric vehicle, while reducing gear rattle.SOLUTION: A motor control device comprises a torque command value control part that controls a torque command value, and a dead-band section determining part that determines whether a dead-band section in which torque of a motor of an electric vehicle is not transmitted to torque of a driving shaft of the electric vehicle ends or not. The torque command value control part sets the torque command value to a limit torque value that is smaller than a restriction torque value and is set in a certain range from the restriction torque value, on the basis of a required torque value of the electric vehicle. Until the dead-band section determining part determines that the dead-band section has ended, the torque command value control part sets the torque command value to be above the limit torque value and less than the restriction torque value. When the dead-band section determining part determines that the dead-band section has ended, the torque command value control part sets the torque command value to the required torque value.SELECTED DRAWING: Figure 2

Description

The present invention relates to a motor control device, and more specifically, to a motor control device that can reduce gear rattle noise while improving responsiveness to a torque request based on the operation of the accelerator pedal by the driver of an electric vehicle.

Patent Document 1 discloses a control device for an electric vehicle that suppresses noise and vibrations that occur due to abrupt torque changes even in situations where the vehicle is coasting or decelerating and then accelerating quickly. This control device for an electric vehicle sets a motor torque command value based on vehicle information and controls the torque of a motor connected to a drive wheel. This control device for an electric vehicle includes a torque command value calculation means and a motor torque control means. The torque command value calculation means applies filtering processing to the motor torque command value to reduce the natural vibration frequency of the driving force transmission system of the vehicle, which has a dead zone section in which the motor torque is not transmitted to the drive shaft torque of the vehicle. The motor torque control means controls the motor torque according to the torque command value obtained by applying filtering processing to the motor torque command value. Furthermore, in this control device for an electric vehicle, the torque command value calculation means performs rate limiting processing to limit the rate of change of the motor torque command value in the dead zone section to a predetermined upper limit value.

JP 2017-221056 A

However, in the control device for an electric vehicle as described in Patent Document 1, the upper limit of the time rate of change (slope) of the motor torque command value is limited within a range that does not deteriorate the torque responsiveness in the dead zone, so there is room for improvement in terms of improving the responsiveness to the torque requested by the driver.

The present invention was made in consideration of the problems associated with the conventional technology, and aims to provide a motor control device that can reduce gear rattle noise while improving responsiveness to the torque required based on the operation of the accelerator pedal by the driver of the electric vehicle.

After extensive research into achieving the above-mentioned objective, the inventors discovered that the above-mentioned objective can be achieved by having a torque command value control unit set the torque command value to a predetermined limit torque value based on the required torque value, maintain the torque command value at or above the limit torque value and below the limited torque value until the end of the dead band section, and set the torque command value to the required torque value when the dead band section ends, thereby completing the present invention.

That is, the motor control device of the present invention includes a torque command value control unit that controls the torque command value, and a dead band section judgment unit that judges whether the dead band section in which the torque of the motor of the electric vehicle is not transmitted to the torque of the drive shaft of the electric vehicle has ended.
A torque command value control unit sets the torque command value to a limit torque value that is smaller than the limit torque value and is set within a certain range from the limit torque value, based on a required torque value of the electric vehicle, which is equal to or greater than the limit torque value of the motor.
The torque command value control unit keeps the torque command value set to the limit torque value at or above the limit torque value and below the limit torque value until the dead-band interval determination unit determines that the dead-band interval has ended.
When the dead-band section determination unit determines that the dead-band section has ended, the torque command value control unit sets the torque command value, which is equal to or greater than the limit torque value and less than the restricted torque value, as the required torque value.

According to the present invention, the torque command value control unit sets the torque command value to the above-mentioned limit torque value based on the required torque value, maintains the torque command value between the limit torque value and the limited torque value until the end of the dead band, and sets the torque command value to the required torque value when the dead band ends. This makes it possible to provide a motor control device that can reduce gear rattle noise while improving responsiveness to the required torque based on the operation of the accelerator pedal by the driver of the electric vehicle.

1 is a block diagram showing an example of a main configuration of an electric vehicle equipped with an embodiment of a motor control device of the present invention; 4 is a graph showing an example of the relationship between time and each torque value in the motor control device of the present embodiment. FIG. FIG. 11 is a graph showing another example of the relationship between time and each torque value in the motor control device of the present embodiment. FIG. 11 is a graph showing yet another example of the relationship between time and each torque value in the motor control device of the present embodiment. FIG. 11 is a graph showing the relationship between time and weighting coefficient a. FIG. 11 is a graph showing yet another example of the relationship between time and each torque value in the motor control device of the present embodiment. FIG. 11 is a graph showing yet another example of the relationship between time and each torque value in the motor control device of the present embodiment. 4A and 4B are diagrams for explaining an outline of the relationship between a motor side gear and a drive shaft side gear.

Below, an embodiment of a motor control device of the present invention will be described in detail with reference to the drawings. Note that the dimensional ratios of the drawings cited below have been exaggerated for the convenience of explanation and may differ from the actual ratios.

Figure 1 is a block diagram showing an example of the main configuration of an electric vehicle equipped with the motor control device of this embodiment.

The electric vehicle in this embodiment is an electric vehicle, but the electric vehicle in the present invention may be any vehicle that has a motor as all or part of the vehicle's drive source and can run using the driving force of the motor, and includes not only electric vehicles, but also hybrid vehicles and fuel cell vehicles.

In this embodiment, for example, power is supplied to the motor 130 via the inverter 120 from the battery 100, which is a secondary battery such as a lithium-ion secondary battery or an all-solid-state battery, based on the control of the motor controller 110. The power of the motor 130 generated by the power is then transmitted to the drive wheels 170a, 170b via the reduction gear 150 and the drive shaft 160, accelerating the electric vehicle.

Signals indicating vehicle conditions such as vehicle speed V, accelerator opening θ, rotor phase α of motor 130, current i (iu, iv, iw) of motor 130, temperature T of motor 130, and rotational angular velocity ωw of drive wheels 170a, 170b are input as digital signals to motor controller 110. Motor controller 110 generates a pulse width modulation (PWM) signal for controlling motor 130 based on the input signals, and generates a drive signal for inverter 120 according to the generated PWM signal.

The motor controller 110 includes a motor control device 1 that controls the motor 130 in response to input from a sensor described below. The motor control device 1 also includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), all of which are not shown.

The CPU is a calculation device that realizes the overall control and functions of the motor control device 1 by reading programs and data from the ROM onto the RAM and executing the processing. The CPU, ROM, RAM, etc. may be integrated in the same package. The motor control device 1 may also be configured to use other logical calculation processors, such as a DSP (Digital Signal Processor), logic circuits, etc., instead of the CPU.

The ROM is a non-volatile semiconductor memory (storage device) that can retain programs (e.g., a program for determining dead zones, a program for determining motor temperature, a program for correcting limit torque values, a program for determining required torque values, a program for calculating motor rotation speed, a program for calculating drive shaft rotation speed, and a program for determining changes) and data (e.g., limit torque value data, limit torque value data, predetermined value data, weighting coefficient a data, accelerator opening-torque table data, rotor temperature-induced voltage data, motor temperature (rotor temperature, stator temperature)-motor rotation speed data, and gear ratio data) even when the power is turned off. Examples of the programs and data stored include an OS (Operating System), which is the basic software that controls the entire computer, and application software that provides various functions on the OS. The motor control device 1 may also be equipped with an SSD (Solid State Drive), etc.

RAM is a volatile semiconductor memory (storage device) that temporarily stores the above-mentioned programs and data.

The inverter 120 has, for example, two switching elements for each phase. The inverter 120 converts the direct current supplied from the battery 100 into alternating current by turning on and off the switching elements in response to a drive signal, and supplies the alternating current to the motor 130. Examples of switching elements include power semiconductor elements such as insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistors (MOSFETs).

The motor (three-phase AC motor) 130 generates driving force from the AC current supplied from the inverter 120, and transmits the driving force to the left and right driving wheels 170a, 170b via the reduction gear 150 and the drive shaft 160. The motor 130 also generates regenerative driving force when rotated by the rotational force of the driving wheels 170a, 170b while the electric vehicle is running. At this time, the inverter 120 converts the AC current generated during regenerative operation of the motor 130 into DC current and supplies the DC current to the battery 100. In this way, the kinetic energy of the electric vehicle is recovered as electrical energy.

The motor rotation sensor 131 is, for example, a resolver or an encoder, and detects the rotor phase α of the motor 130.

The motor temperature sensor 132 is, for example, a resistance temperature detector, a thermocouple, or a thermistor, and measures the temperature T (rotor temperature Tr, stator temperature Ts) of the motor 130. The motor temperature sensor 132 may also measure, for example, the temperature of a permanent magnet, such as a neodymium magnet, that may be incorporated into the rotor as the temperature T of the motor 130.

The current sensor 140 detects the three-phase AC currents iu, iv, and iw that flow through the motor 130. However, since the sum of the three-phase AC currents iu, iv, and iw is zero, the currents of any two phases may be detected and the current of the remaining phase may be calculated.

The reducer 150 has multiple gears, such as a motor side gear 151 and a drive shaft side gear 152, and transmits the reduced rotation speed of the motor 130 to the drive wheels 170a and 170b via the drive shaft 160.

The drive wheel rotation sensors 171a and 171b are, for example, electromagnetic induction type rotation sensors that detect the phase of the drive wheels 170a and 170b.

In electric vehicles such as those described above, the inverter 120 typically performs PWM control of the motor 130 to prevent unnecessary losses when the vehicle is stopped or running, when torque generation by the motor 130 is not required.

Motor 130 also typically has a relationship in which as the rotor temperature increases, the induced voltage of motor 130 decreases.Motor 130 also typically has a relationship in which, when the rotor temperature is constant, as the stator temperature decreases, the rotation speed increases.

When PWM control of the motor 130 is performed, the motor controller 110 acquires signals indicating the vehicle state. In this embodiment, the signals indicating the vehicle state include the vehicle speed V (km/h), the accelerator opening θ (%), the rotor phase α (rad) of the motor 130, the three-phase AC current i (iu, iv, iw) (A) flowing through the motor 130, the temperature T (K) of the motor 130, the rotational angular velocity ωw (rad/s) of the drive wheels 170a, 170b, and the DC voltage value Vdc (V) (not shown) of the battery 1.

The vehicle speed V (km/h) is acquired by communication from a vehicle speed sensor (not shown) or another controller such as a brake controller (not shown). Alternatively, the vehicle speed V (km/h) may be calculated by multiplying the motor rotation angular velocity ωm, which is the mechanical angular velocity of the motor 130, by the driving wheel (tire) dynamic radius R, dividing the result by the gear ratio of the final gear to obtain the vehicle speed v (m/s), and then multiplying the vehicle speed v (m/s) by 3600/1000 to perform unit conversion.

The accelerator opening θ (%) is obtained from an accelerator opening sensor (not shown). Alternatively, the accelerator opening θ (%) is obtained by communication from another controller (not shown), such as a vehicle controller. The torque command value Tm ^* f is set by referring to a predetermined accelerator opening-torque table.

The rotor phase α (rad) of the motor 130 is obtained from the motor rotation sensor 131. The rotation speed Nm (rpm) of the motor 130 is obtained by dividing the rotor angular velocity ω (electrical angle) by the number of pole pairs of the motor 130 to obtain the motor rotation angular velocity ωm (rad/s), and multiplying the motor rotation angular velocity ωm by 60/(2π). The rotor angular velocity ω (rad/s) is obtained by differentiating the rotor phase α.

The current i (iu, iv, iw) (A) of the motor 130 is obtained from the current sensor 140.

The drive wheel rotation angular velocity ωw (rad/s) is calculated by differentiating the average value of the values detected by the drive wheel rotation sensors 171a and 171b.

The DC voltage value Vdc (V) is detected by a voltage sensor (not shown) installed in the DC power supply line between the battery 1 and the inverter 3. Alternatively, the DC voltage value Vdc (V) is determined using the power supply voltage value transmitted from the battery controller (not shown).

The motor controller 110 determines the d-axis current target value id ^* and the q-axis current target value iq ^* based on the torque command value Tm ^* f, the motor rotational angular velocity ωm, and the DC voltage value Vdc, and performs current control to match the d-axis current id and the q-axis current iq to the d-axis current target value id ^* and the q-axis current target value iq ^* , respectively.

For example, the motor controller 110 first determines the d-axis current id and the q-axis current iq based on the input three-phase AC current values iu, iv, iw and the rotor phase α of the motor 130. Next, the motor controller 110 calculates the d-axis and q-axis voltage command values vd, vq from the deviation between the d-axis and q-axis current command values id ^* , iq ^* and the d-axis and q-axis currents id, iq.

The motor controller 110 further obtains three-phase AC voltage command values vu, vv, and vw from the d-axis and q-axis voltage command values vd, vq and the rotor phase α of the motor 130. The motor controller 110 then obtains PWM signals tu(%), tv(%), and tw(%) from the obtained three-phase AC voltage command values vu, vv, and vw and the DC voltage value Vdc.

The switching elements of the inverter 120 are opened and closed by the PWM signals tu, tv, and tw thus determined, so that the motor 130 is driven at the desired torque indicated by the torque command value Tm ^* f.

The motor control device 1 of this embodiment in the motor controller 110 includes a torque command value control unit 10 that controls the torque command value, and a dead zone interval determination unit 20 that determines whether or not the dead zone interval in which the torque of the electric vehicle motor is not transmitted to the torque of the drive shaft of the electric vehicle has ended.

Then, the torque command value control unit 10 sets the torque command value to a limit torque value that is smaller than the limit torque value and within a certain range from the limit torque value, based on the required torque value of the electric vehicle, which is equal to or greater than the limit torque value of the motor 130 (see Figure 2).

The limit torque value can be set, for example, based on the torque value at which the gear rattle noise occurs in the motor 130 (the gear rattle noise generating torque value) in a range that can improve the responsiveness to the required torque while preventing the occurrence of gear rattle noise due to backlash. The limit torque value may be the gear rattle noise generating torque value. This limit torque value can be set, for example, by a preliminary test using an actual vehicle. In addition, for example, in a motor having a rotor with a neodymium magnet, which is an example of a permanent magnet, when the temperature of the motor is in the medium temperature range of 20°C or higher and lower than 80°C, the limit torque value can be set within a range of 20% lower than the limit torque value and 10% lower than the limit torque value. This limit torque value can be set, for example, by a preliminary test using an actual vehicle and varying the magnet temperature.

Furthermore, until the dead zone determination unit 20 determines that the dead zone has ended, the torque command value control unit 10 keeps the torque command value set to the limit torque value at or above the limit torque value and below the limit torque value (see FIG. 2). Note that the end of the dead zone is, as will be described in detail later, when, for example, an actual torque value is obtained according to the torque command value, and the drive shaft rotates according to the actual torque value.

From the viewpoint of improving responsiveness to the required torque value, it is preferable that the time rate of change of the torque command value when the torque command value is set to the limit torque value is greater than the time rate of change of the torque command value when the torque command value set to the limit torque value is set to be equal to or greater than the limit torque value and less than the limit torque value. In addition, when the torque command value set to the limit torque value is set to be equal to or greater than the limit torque value and less than the limit torque value, the torque command value may be maintained at the limit torque value.

Furthermore, when the dead-band interval determination unit 20 determines that the dead-band interval has ended, the torque command value control unit 10 sets the torque command value, which is equal to or greater than the limit torque value and less than the restricted torque value, to the required torque value (see FIG. 2).

In addition, the motor control device 1 of this embodiment preferably further includes a motor temperature sensor 132 that measures the temperature of the motor 130, a motor temperature determination unit 30 that determines whether the temperature of the motor 130 is in the high or low temperature range, and a limit torque value correction unit 40 that corrects the limit torque value (see FIG. 1).

When the motor temperature determination unit 30 determines that the temperature of the motor 130 is in the high temperature range, it is preferable that the limit torque value correction unit 40 increases the limit torque value within a certain range (see Figure 3).

For example, in a motor equipped with a rotor having a neodymium magnet, which is an example of a permanent magnet, when the motor temperature is in the high temperature range of 80°C or higher and lower than 150°C, it is preferable to set the limit torque value within a range of 10% lower and 1% lower than the limit torque value.

In addition, when the motor temperature determination unit 30 determines that the temperature of the motor 130 is in the low temperature range, it is preferable that the limit torque value correction unit 40 reduces the limit torque value within a certain range (see Figure 3).

For example, in a motor equipped with a rotor having a neodymium magnet, which is an example of a permanent magnet, when the motor temperature is in the low temperature range of -40°C or higher and lower than 20°C, it is preferable to set the limit torque value within a range of 25% lower and 15% lower than the limit torque value.

Furthermore, the motor control device 1 of this embodiment preferably further includes a required torque value determination unit 50 that determines whether the time rate of change of the required torque value is greater than a predetermined value (see FIG. 1).

When the required torque value determination unit 50 determines that the time rate of change of the required torque value is greater than a predetermined value, it is preferable that the torque command value control unit 10 sets the torque command value to the required torque value without setting it to the limit torque value.

In an electric vehicle equipped with a motor 130 that controls the torque command value as shown in Figures 2 to 4, 6, and 7, the predetermined value is preferably set to, for example, 300 Nm/msec. This predetermined value is preferably set according to the specifications of the electric vehicle.

Furthermore, the motor control device 1 of this embodiment preferably further includes a motor rotation speed calculation unit 60 that calculates the rotation speed of the motor 130, and a drive shaft rotation speed calculation unit 70 that calculates the rotation speed of the drive shaft 160 (see FIG. 1).

Then, it is preferable that the dead-band interval determination unit 20 determines that the dead-band interval has ended by determining that the motor 130 and the drive shaft 160 are synchronized based on the difference between the rotation speed of the motor 130 and the rotation speed of the drive shaft 160.

Furthermore, in the motor control device 1 of this embodiment, when the torque command value control unit 10 sets the torque command value, which is equal to or greater than the limit torque value and less than the restricted torque value, to the required torque value, it is preferable to increase the torque command value over time (see FIG. 4).

Compared to the case of Fig. 6, when the required torque is relatively small as in the case of Fig. 4, the torque command value is increased based on the weighting coefficient a, which is a function with time as a variable as shown by the dotted line in Fig. 5. The relationship between the torque command value Tm ^* f, the required torque value Tm ^* d, the limit torque value Tm ^* end and the weighting coefficient a can be expressed by the following equation: Tm ^* f=a×Tm ^* d+(1−a)×Tm ^* end (0≦a≦1).

Furthermore, in the motor control device 1 of this embodiment, when the torque command value control unit 10 increases the torque command value over time, it is preferable to increase the amount of increase in the torque command value per unit time the greater the difference between the torque command value that is set to be equal to or greater than the limit torque value and less than the restricted torque value, and the required torque value (see Figures 6 and 4).

When the required torque is relatively large, as in the case of FIG. 6, as compared to the case of FIG. 4, the torque command value is increased based on the weighting coefficient a, which is a function with time as a variable, as shown by the solid line in FIG. 5.

Furthermore, it is preferable that the motor control device 1 of this embodiment further includes a change determination unit 80 that determines whether the requested torque value has been changed to a changed requested torque value that is less than the limit torque value.

When the change determination unit 80 determines that the required torque value has been changed to the changed request torque value before the dead-band interval determination unit 20 determines that the dead-band interval has ended, it is preferable that the torque command value control unit 10 sets the torque command value that has been set to be equal to or greater than the limit torque value but less than the limit torque value to the changed request torque value (see FIG. 7).

Next, the advantages of this embodiment will be described. In this embodiment, the torque command value control unit 10 sets the torque command value to the above-mentioned limit torque value based on the required torque value, maintains the torque command value between the limit torque value and the limited torque value until the dead zone section determination unit 20 determines that the dead zone section has ended, and sets the torque command value to the required torque value when the dead zone section determination unit 20 determines that the dead zone section has ended. As a result, compared to the conventional example (see FIG. 2) in which the upper limit value of the time rate of change (slope) of the actual torque value is limited within a range that does not deteriorate the torque responsiveness in the dead zone section, it is possible to reduce gear rattle noise while improving the responsiveness to the required torque based on the operation of the accelerator pedal by the driver of the electric vehicle.

Figure 8 is a diagram that uses solid lines to explain the general relationship between the motor side gear and the drive shaft side gear when PWM control is OFF. Figure 8 also uses dotted lines to explain the general relationship between the motor side gear and the drive shaft side gear when PWM control is ON.

The teeth rattle noise occurs, for example, when the PWM control is turned ON due to a change in the required torque value in response to the driver's operation of the accelerator pedal when the PWM control is OFF, and the two meshing gears (the motor side gear 151 and the drive shaft side gear 152) are shifted. More specifically, when the teeth of the drive shaft side gear 152 are in contact with the tooth surface A of the motor side gear 151 and there is a shift position (backlash) d on the tooth surface B, and when the motor side gear 151 rotates in the direction indicated by the arrow ωw, the teeth of the drive shaft side gear 152 move through the backlash d and are then pressed against the tooth surface B of the motor side gear 151. The predetermined time t for the teeth of the drive shaft side gear 152 to move through this backlash d is calculated as t = (2 x d x Jm/Tm) ^1/2 . Here, Jm is the motor end inertia (known quantity), and Tm is the motor torque (operation quantity). Further, the motor side gear relative speed (control amount) Vr is calculated by Vr=Tm/Jm×t.

Then, at a predetermined time t, the torque command value is set to be equal to or greater than the limit torque value and less than the limit torque value described above, and the motor side gear relative speed Vr when the gears are changed can be controlled within a predetermined range, in other words, below the limit speed at which rattle noise does not occur, thereby reducing rattle noise. Furthermore, because the limit torque value is constant regardless of time, responsiveness to the required torque is not impaired.

Furthermore, in this embodiment, in order to obtain the above-mentioned advantages, there is also the secondary advantage that the scale of changes to the control system is smaller compared to a control system that includes gear position control.

In addition, in this embodiment, when the motor temperature determination unit 30 determines that the temperature of the motor 130 is in the high temperature range as described above, the limit torque value correction unit 40 increases the limit torque value within a certain range, and when the motor temperature determination unit 30 determines that the temperature of the motor 130 is in the low temperature range as described above, the limit torque value correction unit 40 decreases the limit torque value within a certain range. As a result, in addition to the above-mentioned advantages, it is possible to reduce rattle noise and improve responsiveness to the required torque, regardless of the magnetic temperature characteristics of the permanent magnet in the motor. More specifically, compared to when the torque is controlled in a feedforward manner by current feedback control in the motor, the rattle noise limit speed is not exceeded and the actual torque is not insufficient when changing gears due to the magnetic temperature characteristics of the permanent magnet.

Furthermore, in this embodiment, when the required torque value determination unit 50 determines that the time rate of change of the required torque value is greater than a predetermined value, the torque command value control unit 10 sets the torque command value to the required torque value without setting it to the limit torque value. This not only achieves the above-mentioned advantages, but also improves acceleration when the driver requires acceleration rather than reduced gear rattle or vibration. Furthermore, when such a predetermined value is set, gear rattle is usually smaller than the noise in the environment surrounding the electric vehicle and is not a problem. Furthermore, the risk of the driver feeling a sense of stalling can be reduced.

Furthermore, in this embodiment, the dead zone determination unit 20 determines that the motor 130 and the drive shaft 160 are synchronized based on the difference between the rotation speed of the motor 130 and the rotation speed of the drive shaft 160, and thereby determines that the dead zone has ended. This provides the above-mentioned advantages, and in addition, it is possible to determine the end of the motor's dead zone in the minimum amount of time without having to consider the amount of gear play, variations in motor inertia, friction of the motor-side gear, and the magnetic temperature characteristics of the permanent magnet, thereby improving acceleration. It also reduces the risk that the driver will feel a sense of lag in acceleration.

Furthermore, in this embodiment, when the torque command value control unit 10 sets the torque command value, which is equal to or greater than the limit torque value but less than the restricted torque value, to the required torque value, the torque command value is increased over time. This makes it possible to reduce the occurrence of vibrations in addition to the above-mentioned advantages. In other words, by increasing the torque command value over time when the torque command value control unit 10 sets the above-mentioned torque command value to the required torque value, the time rate of change of the torque command value can be smoothed and torsion of the drive shaft can be reduced.

Furthermore, in this embodiment, when the torque command value control unit 10 increases the torque command value over time, the greater the difference between the torque command value, which is set to be equal to or greater than the limit torque value but less than the restricted torque value, and the required torque value, the greater the increase in the torque command value per unit time. This not only achieves the above-mentioned advantages, but also increases acceleration and improves responsiveness to the required torque, even when the required torque value is large. It also reduces the risk that the driver will feel a sense of delayed acceleration.

Furthermore, in this embodiment, when the change determination unit 80 determines that the required torque value has been changed to the changed request torque value before the dead zone section determination unit 20 determines that the dead zone section has ended, the torque command value control unit 10 sets the torque command value that is equal to or greater than the limit torque value and less than the limit torque value to the changed request torque value. This not only achieves the above-mentioned advantages, but also improves responsiveness to the requested torque without the above-mentioned unnecessary rattle noise reduction control. It also reduces the risk that the driver will feel a sense of delayed deceleration or a sense of being pushed out.

The present invention has been described above using one embodiment, but the present invention is not limited to this, and various modifications are possible within the scope of the gist of the present invention.

In the present invention, in order to reduce gear rattle noise while improving responsiveness to the required torque based on the operation of the accelerator pedal by the driver of the electric vehicle, the torque command value control unit sets the torque command value to the above-mentioned limit torque value based on the required torque value, maintains the torque command value at or above the limit torque value and below the limited torque value until the end of the dead band section, and sets the torque command value to the required torque value when the dead band section ends.

Thus, in the above embodiment, a motor in which a permanent magnet such as a neodymium magnet is incorporated in the rotor has been described as an example, but in the present invention, the permanent magnet of the rotor is not limited to a neodymium magnet, and other permanent magnets known in the art can also be applied. In that case, the limit torque value can also be changed appropriately depending on the magnetic temperature characteristics of the permanent magnet. Furthermore, in the present invention, a wound field type rotor can also be applied as the rotor of the motor.

In the above embodiment, a dead zone section determination unit that determines the end of the dead zone section based on the difference between the rotation speed of the motor and the rotation speed of the drive shaft is described as an example, but the present invention is not limited to this. For example, a dead zone section determination unit that determines the end of the dead zone section by calculating a predetermined time until the end of the dead zone section based on the amount of gear backlash, the variation in motor inertia, and the friction of the motor-side gear can also be applied.

In addition, the preferred components described above are not necessarily essential components and may be removed. Furthermore, it is also possible to change the details of the specifications of the motor control device, motor controller, battery, motor controller, inverter, motor, motor rotation sensor, motor temperature sensor, current sensor, reducer, drive wheel rotation sensor, etc.

REFERENCE SIGNS LIST 1 Motor control device 10 Torque command value control section 20 Dead band section determination section 30 Motor temperature determination section 40 Limit torque value correction section 50 Required torque value determination section 60 Motor rotation speed calculation section 70 Drive shaft rotation speed calculation section 80 Change determination section 100 Battery 110 Motor controller 120 Inverter 130 Motor 131 Motor rotation sensor 132 Motor temperature sensor 140 Current sensor 150 Speed reducer 151 Motor side gear 152 Drive shaft side gear 160 Drive shaft 170a, 170b Drive wheels 171a, 171b Drive wheel rotation sensor

Claims (7)

A motor control device including a torque command value control unit that controls a torque command value, and a dead zone section determination unit that determines whether or not a dead zone section in which torque of a motor of an electric vehicle is not transmitted to torque of a drive shaft of the electric vehicle has ended,
the torque command value control unit sets a torque command value to a limit torque value that is smaller than the limit torque value and is set within a certain range from the limit torque value, based on a required torque value of the electric vehicle, which is equal to or larger than the limit torque value of the motor;
the torque command value control unit keeps the torque command value set to the limit torque value equal to or greater than the limit torque value and less than the limit torque value until the dead band section determination unit determines that the dead band section has ended;
a torque command value control unit that sets a torque command value that is equal to or greater than the limit torque value and less than the restriction torque value to the required torque value when the dead band interval determination unit determines that the dead band interval has ended. The motor temperature sensor measures the temperature of the motor, a motor temperature determination unit determines whether the temperature of the motor is in a high temperature range or a low temperature range, and a limit torque value correction unit corrects the limit torque value,
when the motor temperature determination unit determines that the temperature of the motor is in a high temperature range, the limit torque value correction unit increases the limit torque value within the certain range,
2. The motor control device according to claim 1, wherein when the motor temperature determination unit determines that the temperature of the motor is in a low temperature range, the limit torque value correction unit reduces the limit torque value within the certain range. a required torque value determination unit that determines whether a time rate of change of the required torque value is greater than a predetermined value,
3. The motor control device according to claim 1, wherein when the required torque value determination unit determines that the time rate of change of the required torque value is greater than a predetermined value, the torque command value control unit sets the torque command value to the required torque value without setting it to the limit torque value. The system further includes a motor rotation speed calculation unit that calculates the rotation speed of the motor, and a drive shaft rotation speed calculation unit that calculates the rotation speed of the drive shaft,
3. The motor control device according to claim 1, wherein the dead zone determination unit determines that the dead zone has ended by determining that the motor and the drive shaft have been synchronized based on a difference between the rotation speed of the motor and the rotation speed of the drive shaft. The motor control device according to claim 1 or 2, characterized in that the torque command value control unit increases the torque command value over time when the torque command value, which is equal to or greater than the limit torque value and less than the limit torque value, is set to the required torque value. 6. The motor control device according to claim 5, wherein when the torque command value control unit increases the torque command value over time, the greater the difference between the torque command value that is equal to or greater than the limit torque value and less than the limit torque value, and the required torque value, the greater the increase in the torque command value per unit time. a change determination unit that determines whether the required torque value is changed to a changed required torque value that is less than the limit torque value,
3. The motor control device according to claim 1, wherein when the change determination unit determines that the required torque value has been changed to the changed requested torque value before the dead band section determination unit determines that the dead band section has ended, the torque command value control unit sets the torque command value that has been set to be equal to or greater than the limit torque value and less than the limit torque value to the changed requested torque value.

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