JPH0937408A - Controller for inverter of electric car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propel an electric car by an arbitrary creeping speed. SOLUTION: The rotational speed Vm of a wheel 2 is detected by a rotational speed detector 4, and the car speed Vt is detected by a car speed detector 5. A creeping speed Vs is obtained by a first adder/subtracter 6 from the motor speed Vm and the car speed Vt. This creeping speed Vs and a creeping speed command Vs* which a creeping speed command generator 7 outputs are compared by a second adder/subtracter 8, and it outputs a creeping speed deviation Vse. A torque command calculating part 9 calculates a torque command T* so as to make this creeping speed deviation Vse small. Receiving this torque command T*, a motor drive part 10 supplies a drive signal to the motor 3. The motor 3 receives the drive signal and is driven, and rotates wheels 2. Accordingly, it becomes possible to drive the electric car stably without slipping and sliding as the creeping speed is controlled at high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control device for an electric vehicle, and more particularly, to a drive control device for an electric vehicle that can improve adhesion performance in an electric vehicle driven by an induction motor (hereinafter referred to as a motor). It is a thing.

[0002]

2. Description of the Related Art FIG. 13 shows an example of the configuration of an electric vehicle driven by a conventional variable speed motor disclosed in, for example, Japanese Patent Laid-Open No. 4-54802. In FIG. It serves as an input power source for the inverter 22 via 19, the filter reactor 20, and the filter capacitor 21. The inverter 22 converts the input current into an alternating current and outputs it to drive the electric motors 23A to 23D. The pulse generators 24A to 24D are the motor 2
The rotation frequencies of 3A to 23D are detected and output to the frequency calculator 25. The frequency calculation unit 25 selects the minimum value during power running and the maximum value during regeneration and outputs it to the reference rotation frequency calculation unit 32 as the rotation frequency signal frm.

The pattern generator 31 generates a slip frequency pattern signal fsp and a current pattern signal I based on the operation command.
p and the acceleration pattern signal αp (βp) are generated. The slip frequency pattern signal fsp is the reference frequency signal fr output from the reference rotation frequency calculator 32, and the slip frequency deviation value Δ output from the current control means described later.
fs is added by the adder / subtractor 30 to obtain the inverter frequency fi.
It is output to the inverter 22 as nv.

The reference rotation frequency calculation unit 32 includes a storage element 3
3, 34, an arithmetic unit 35, a frequency deviation value arithmetic unit 36, an adder / subtractor 37, and a discriminating circuit 38. The first storage element 33 stores the reference rotation frequency signal fro one arithmetic cycle before.
The first and second storage elements 34 store the reference rotation frequency signal pro2 one cycle before. F in the calculator 35
ro1 and fr2 are input and the time change amount Δfr is output. Further, the frequency deviation value calculator 36 outputs the acceleration pattern signal αp (βp) which is the output of the pattern generator 31.
To output the frequency deviation value Δfp. The adder / subtractor 37 synthesizes the frequency deviation value Δfp, the time change amount Δfr, and the reference rotation frequency signal fro of one cycle before and outputs the rotation frequency equivalent signal fr at the time of adhesion. The determination circuit 38 selects a lower value during power running and a higher value during regeneration from the rotational frequency equivalent signal fr of the adhesive shaft and the rotational frequency signal frm output from the frequency calculator 25, and selects the reference rotational frequency signal. It is output to the adder / subtractor 30 as "fro".

The current control means is an ammeter 26 and an inverter 2
The output current of No. 2 is detected, and the current detection unit 27 converts it into an effective value. The comparator 28 compares the effective value Im with the current pattern signal Ip output from the pattern generator 31 and outputs the deviation ΔIm to the slip frequency calculator 29. The slip frequency calculation unit 29 converts the deviation ΔIm into a slip frequency deviation amount Δfs and outputs it to the adder / subtractor 30.

With this configuration, when there is a shaft that is sticking even in the case of idling / sliding or even in the case of one shaft, the frequency calculating unit 25 selects the rotation speed of the sticking shaft, so that the inverter frequency signal finv is idling. It is given as before. Further, when all the axes slip and slide, the frequency deviation value Δ output from the frequency deviation calculator 36 based on the acceleration pattern signal αp (βp) output from the pattern generator 31.
The rotation frequency equivalent signal fr that is incremented by the output Δfr of the arithmetic unit 35, which is the speed change immediately before, is selected, and the inverter frequency finv is given regardless of the rotation speed of the motor, and is constant until idling / sliding stops. Given in increments.

[0007]

Since this prior art is only trying to control the rotation of the motor only by the rotation speed of the motor and the command value, the adhesive state between the rail and the wheel is not considered at all. Has become. Since the torque command is given regardless of the adhesive state, slipping is likely to occur in a poor adhesive state.

[0008] Further, since the control is performed only by the rotation speed of the motor until the slipping, the actual slipping speed / creep speed cannot be controlled.

Further, since the reduction in acceleration / deceleration due to slipping / sliding is not taken into consideration, it is possible to suppress the slipping amount / sliding amount to be low when slipping / sliding occurs, but it becomes impossible to re-adhesive. Can be considered.

[0010]

According to a first aspect of the present invention, an inverter control device for an electric vehicle includes a wheel rotation speed detecting means for detecting a wheel rotation speed, a vehicle body speed detecting means for detecting a vehicle body speed, and a creep. Speed command generating means, torque command calculating means for calculating a torque command by inputting the creep speed command, vehicle body speed, and rotation speed, and a motor drive section for driving a motor based on the torque command output by the torque command calculating means. It is equipped with and.

An inverter control device for an electric vehicle according to a second aspect of the present invention is the inverter control device for an electric vehicle according to the first aspect, wherein an optimum creep speed value is obtained by inputting a torque command output from a torque command calculation means. It is provided with an optimum creep speed search unit for outputting.

An inverter control device for an electric vehicle according to a third aspect of the present invention is the inverter control device for an electric vehicle according to the second aspect, in which a creep speed command is generated based on an optimum creep speed value supplied from an optimum creep speed search section. Is provided with a creep speed command adjusting unit, and the creep speed command generating unit changes the creep speed command by this creep speed command adjusting unit.

An inverter control device for an electric vehicle according to a fourth aspect of the present invention is the inverter control device for an electric vehicle according to any one of the first to third aspects, in which the wheel rotation speed and the vehicle body speed are input. The wheel diameter calculating means for outputting the calculated value is provided, and the rotation speed detecting means changes the wheel diameter value according to the wheel calculated value.

An inverter control device for an electric vehicle according to a fifth aspect of the present invention is the inverter control device for an electric vehicle according to any one of the first to fourth aspects, wherein the torque command value output by the torque command calculation means is output. And an optimum creep speed value output from the optimum creep speed search unit are input, and a creep speed-adhesion force display device for displaying a two-dimensional map of adhesive strength on the driver's cab is provided.

According to a sixth aspect of the present invention, there is provided an inverter control device for an electric vehicle according to the fifth aspect, wherein the creep speed-adhesive force display device displays a command adhesive force corresponding to the creep speed command. When the driver determines that the peak value of the actual adhesive force is less than the command adhesive force, the creep speed command change means that changes the setting of the creep speed command generator by a predetermined operation of the driver is provided. Be prepared.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of the present invention. 1 is the body of the train to be driven, 2 is the wheels, 3
Is a motor for driving the wheels, 4 is a rotation speed detector (means) for detecting the rotation speed (motor speed) Vm of the wheels, and 5 is a vehicle speed detector (means) for detecting the vehicle speed Vt which is the ground speed of the vehicle body 1. ) And 6 are first adder / subtractors that obtain the creep speed Vs by comparing the motor speed Vm and the vehicle body speed Vt. The second adder / subtractor 8 outputs the creep speed deviation Vse using the creep speed Vs and the creep speed command Vs * output from the creep speed command generator (means) 7 as inputs. Reference numeral 9 denotes a torque command calculation unit (means) which inputs the creep speed deviation Vse and outputs a torque command T * to the motor drive unit 10. The motor drive unit 10 receives the torque command T * and supplies a drive signal to the motor 3.

The operation of this embodiment will be described with reference to the drawings. The rotation speed Vm of the wheel 2 is detected by the rotation speed detector 4 from the motor rotation speed and the wheel rotation speed obtained by detecting the rotation speed of a pulse generator or the like. On the other hand, the vehicle body speed Vt is detected by the vehicle body speed detector 5 attached to the vehicle body by, for example, detection of the rotation speed of the driven wheel without a motor, non-contact ground speed detection, and position information detection obtained from ATO information.

The creep speed Vs is obtained from the motor speed Vm and the vehicle body speed Vt by the first adder / subtractor 6 according to the following equation. Vs = Vm-Vt This creep speed Vs is compared with the creep speed command Vs * output from the creep speed command generator 7 by the second adder / subtractor 8 to output the creep speed deviation Vse. The torque command calculator 9 calculates the torque command T * so as to reduce the creep speed deviation Vse. Motor drive unit 10
Receives the torque command T * and supplies a drive signal to the motor 3. The motor 3 receives the drive signal and is driven to rotate the wheels 2.

The present invention utilizes the fact that the transmission force from the wheel 2 to the rail, that is, the propulsion force of the train can be adjusted by adjusting the torque generated by the motor 3 when the creep speed is stable. Now, it will be described that the transmission force can be adjusted by adjusting the torque generated by the motor 3. When the transmission torque of the motor 3 to the vehicle body 1 is Tt and the generated torque is Tm, the equation of motion is created on the motor side and the vehicle body side as follows. Tt = GTm-Jm · dVmr / dt (1) Tt = Mt · r ² · dVtr / dt (2) Here, Jm is an axle conversion value of the motor inertia, and Mt is the motor 3 of the vehicle body weight. Is the load, G is the gear ratio, and r is the wheel diameter. Further, Vmr and Vtr are angular velocity conversion values of the motor speed and the vehicle body speed. When the creep speed is constant, such as during coasting, the transmission force can be regarded as constant, so that the acceleration of the vehicle is also constant along with the acceleration of the motor.
In the above equations (1) and (2), dVmr / dt = dVt
If r / dt, then Tm = {(Mt · r ² + Jm) / Mt · r ² · 1 / G} · Tt (3), and the torque Tm generated by the motor 3 becomes the torque transmitted to the vehicle body 1 Tt. Simply proportional. Therefore, if the creep speed is reliably and stably controlled, the torque transmitted to the vehicle body 1 can be adjusted by adjusting the torque generated by the motor 3.

Next, the setting of the creep speed command will be described. The creep speed command Vs * output from the creep speed command generator 7 selects and outputs the creep speed that seems to be optimum, and the optimum value is set in advance by experience or given an approximate value by estimation. It is something that can be done. FIG. 2 shows an example in which the transmission force between the wheel and the rail is expressed with respect to the creep speed, and Vso in the figure is the maximum transmission creep speed that gives the maximum transmission force Fmax. The left side of this Vso, that is, the creep speed is Vso
The smaller side is an area where the wheel 2 is stably adhered, and the right side, that is, the side where the creep speed is higher than Vso is an unstable area, and the wheel 2 runs idly when the creep speed increases. According to the pattern of FIG. 2, a large transmission force can be obtained by keeping the creep speed Vs close to Vso. Therefore, if the command value is set to this Vso, the creep speed Vs
It becomes possible to obtain a higher transmission force by controlling. A stable thrust can be obtained by setting a command value so as to control the creep speed at Vso or less.

In the present invention, not only Vso but also Vso
Even if the creep speed command exceeds, the creep speed can be controlled stably without taking over the slip. That is, the creep speed command value is set to any value, and the torque command value T * corresponding thereto can be used to drive any motor. With this configuration, the creep speed does not change even if the adhesive pattern changes and the adhesive force decreases, so that the vehicle can run without causing idling.

The torque command calculator 9 determines the creep speed deviation V
se is quickly adjusted. For example, a PID controller, a learned neural network (hereinafter referred to as NN), or the like can be used to configure a control system with high responsiveness.

Embodiment 2 FIG. Next, a second embodiment will be described. FIG. 3 shows the configuration of this embodiment, and a description of the parts having the same functions as in FIG. 1 will be omitted. The optimum creep speed searching unit 11 inputs the torque command value T * which is the output of the torque command calculating unit 9 and outputs the optimum creep speed value Vso.

Since the transmission force has a mountain as shown in FIG. 2, the optimum creep velocity searching unit 11 can use, for example, a hill climbing exploration method. When the hill-climbing search method is used, the top of the mountain is always searched for the optimum creep speed value Vso that can obtain the maximum transmission force. As a result, the maximum adhesive force can always be applied even if the adhesive state changes. Also,
The fuzzy reasoning, the AI method, the NN method and the like can have the same function, and the optimum speed can be set without being limited to the creep speed that gives the maximum transmission force.

Embodiment 3. Next, a third embodiment will be described. FIG. 4 shows the configuration of this embodiment, and the description of the parts having the same functions as those in FIGS. 1 and 3 is omitted. The optimum creep speed searching unit 11 inputs the torque command value T *, which is the output of the torque command calculating unit 10, and outputs the optimum creep speed value Vso at which the maximum adhesive force can be obtained. This optimum creep speed search value Vso is output to the creep speed command adjustment unit 12, and the creep speed command adjustment unit 12 adjusts the creep speed command Vs * of the creep speed command value generator 7 based on the optimum creep speed value Vso. .

With this creep speed command adjusting function, the creep speed command value can be corrected when the adhesive force desired to be obtained at the commanded creep speed cannot be obtained in the actual adhesive state.

Embodiment 4 Next, a fourth embodiment will be described. FIG. 5 is a block diagram showing the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 1 will be omitted. The rotation speed detector 4 inputs the rotation frequency of the motor and outputs the rotation speed Vm. The wheel diameter calculator 13 inputs the rotation speed Vm output from the rotation speed detector 4 and the vehicle body speed Vt output from the vehicle body speed detector 5, and supplies the wheel diameter calculation value rc to the rotation speed detector 4. FIG. 6 shows the rotation speed detector 4
3 is a block diagram showing the internal configuration of FIG. The wheel rotation speed detector 4 has a rotation frequency detector 4a for detecting the rotation frequency of the motor and a rotation frequency speed converter 4b therein, and converts the wheel diameter calculation value rc supplied from the wheel diameter calculator 13 into the rotation frequency speed converter. It is used as the input of the container 4b.

The rotation frequency fm of the motor 3 detected by the rotation frequency detector 4a is the rotation frequency speed converter 4b.
Is converted into a rotation speed Vm by. The conversion formula is represented by the following formula. Vm = 2πr / pG · fm (4) where π is the circular constant and p is the number of pole pairs of the motor. As the vehicle continues to run, the wheels wear and the wheel diameter decreases. If this value does not match the actual value when converting from the rotation frequency fm to the rotation speed Vm, the creep speed cannot be obtained correctly from the equation (4). In order to solve this problem, the wheel diameter calculator 13 changes the value of the wheel diameter r used by the rotation frequency speed converter 4b, such as during coasting of the train. Since the creep speed Vs = 0 during coasting, the vehicle speed and the motor speed become equal. That is, from the equation (1), Vt = 2πrc / pG · fm (5) is obtained and rc = pG / 2π · Vt / fm (6) By resetting the wheel diameter calculation value rc thus obtained as the wheel diameter value r in the rotation frequency speed converter 4b, it is possible to always accurately calculate the creep speed. Here, the rotation frequency of the motor is detected to obtain the rotation speed Vm, but the same operation is performed even if the rotation frequency of the wheels is detected.

Embodiment 5. Next, a fifth embodiment will be described. FIG. 7 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 3 are omitted. The optimum creep speed search unit 11 inputs the creep speed Vs output from the first adder / subtractor 6 and the torque command T * output from the torque command calculation unit 9 to obtain the optimum creep speed value V.
Output so. In this way, by inputting the actual creep speed as well, a more reliable optimum creep speed search can be performed.

Embodiment 6 FIG. Next, a sixth embodiment will be described. FIG. 8 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 4 are omitted. The optimum creep speed search unit 11 searches for an optimum creep speed at which an arbitrary transmission force can be obtained. A limiter 14 receives the optimum creep speed value Vso as an input, and outputs a limit to the optimum creep speed value Vso to the creep speed command adjusting unit 12 with a certain limit. As a result, even when the optimum creep speed search unit 11 obtains a search result that is greater than or equal to the command adhesion force, the creep speed command adjustment is also restricted by limiting, and no command is given above the arbitrary transmission force.

Embodiment 7 Next, a seventh embodiment will be described. FIG. 9 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 4 are omitted. Reference numeral 15 is a low-pass filter that receives the torque command T * as an input and outputs a filtering result to the optimum creep speed searching unit 11. By adding the low-pass filter 15, it is possible to cut fine fluctuations in the torque command T * that is being controlled at high speed, and search for the optimum creep speed value with a stable torque command T *. When the stable optimum creep speed search is performed, the output of the creep speed command adjusting unit 12 becomes smooth, so that the creep speed command output from the creep speed command generator 7 can be smoothly supplied.

Embodiment 8 FIG. Next, an eighth embodiment of the present invention will be described. FIG. 10 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 3 are omitted. Reference numeral 16 denotes the optimum creep speed value Vso output by the optimum creep speed search unit 11 and the torque command T * output by the torque command calculation unit 9 and displays the adhesive force two-dimensional map on the driver's cab It is a display device. As a result, the adhesive force obtained by the torque command T * can be grasped on the cab.

Embodiment 9 Next, a ninth embodiment of the invention will be described. FIG. 11 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 4 are omitted. Reference numeral 16 denotes the optimum creep speed value Vso output by the optimum creep speed search unit 11 and the torque command calculation unit 9
Output torque command T *, creep speed command generator 7
Is a creep speed-adhesive force display device for inputting a creep speed command Vs * output from the device and displaying a two-dimensional map of the command adhesive force and the estimated adhesive force on the driver's cab. This allows the driver's cab to simultaneously grasp the command adhesive force and the estimated adhesive force, and confirm that the search result is reflected in the command.

Embodiment 10 FIG. Next, a tenth embodiment of the present invention will be described. FIG. 12 shows the configuration of this embodiment. Descriptions of parts having the same functions as those in FIG. 3 are omitted. 16 is the optimum creep speed search unit 11
2D of the command adhesive force and the estimated adhesive force by inputting the optimum creep speed value Vso output by the torque command T * output by the torque command calculator 9 and the creep speed command Vs * output by the creep speed command generator 7 A creep speed / adhesive force display device for displaying a map on the driver's cab, and reference numeral 17 is a creep speed command change button for outputting a creep speed command adjustment command to the creep speed command generator 7 by a driver's operation.

For example, when the maximum value of the adhesive pattern is lowered, for example, when the weather is light, the estimated adhesive force tries to obtain the maximum adhesive force in the two-dimensional map displayed on the driver's cab. Is displayed as a single point. On the other hand, the command adhesive force changes along a straight line because the creep speed command is a fixed value. When there is no change in the display, the driver judges that the adhesive strength has decreased and the creep speed command change button 1
When 7 is pressed, the creep speed command generator 7 sets and changes the creep speed command value to a low value. As a result, the command value is adjusted according to the driver's request while observing the driving state and becomes close to the actual creep speed, so that the creep speed control is stably performed.

[0036]

According to the first aspect of the present invention, there is provided an inverter control device for an electric vehicle, which comprises a wheel rotation speed detecting means for detecting a wheel rotation speed, a vehicle body speed detecting means for detecting a ground speed of a vehicle body, and a creep speed. A creep speed command generating means for outputting a command, a torque command calculating means for calculating a creep speed from the wheel rotation speed and the vehicle body speed, and a torque command by performing command value tracking control for the creep speed command, and the torque command. Since the motor drive unit that drives the motor from the torque command output from the computing means is provided, the torque command that follows the given creep speed command is given to the motor, and the creep speed does not change (that is, slipping / sliding). The effect is that it is possible to drive the train (without running).

According to a second aspect of the present invention, there is provided an inverter control device for an electric vehicle according to the first aspect of the present invention, which is the inverter control device for an electric vehicle. Since the creep speed search unit for outputting is provided, the optimum creep speed for giving the torque command T * can be obtained. As a result, it is found that the optimum creep speed has changed, and it is possible to estimate the actual adhesive force and correct the command value by using this creep speed search value.

According to a third aspect of the present invention, there is provided an inverter control device for an electric vehicle according to the second aspect, wherein the creep speed command value is set based on the optimum creep speed value output from the creep speed search section. Since the creep speed command adjusting unit for adjusting is provided, the creep speed command value can be adjusted more optimally.

According to a fourth aspect of the present invention, there is provided an inverter control device for an electric vehicle, wherein the inverter control device for an electric vehicle according to any one of the first to third aspects is based on the wheel rotation speed and the train body speed. Since the wheel diameter calculator for calculating the diameter and outputting it as the wheel diameter used for the rotation speed calculation is provided, the wheel rotation speed can always be obtained with a correct value. As a result, even if the wheel diameter changes due to wheel wear or the like, a minute creep speed can be accurately obtained.

An inverter control device for an electric vehicle according to a fifth aspect of the present invention is a creep speed for displaying a two-dimensional adhesive force map in the inverter control device for an electric vehicle according to any one of the first to fourth aspects. Since the adhesive force display device is provided, there is an effect that the adhesive force can be constantly viewed on the cab.

According to a sixth aspect of the present invention, there is provided an electric vehicle inverter control device for displaying an adhesive force two-dimensional map of command adhesive force and estimated adhesive force on a driver's cab in the electric vehicle inverter control device according to the fifth aspect. Since the creep speed-adhesive force display device and the creep speed command changing means operated by the driver are provided, there is a clear difference between the command adhesive force for the creep speed command and the estimated adhesive force for the optimum creep speed search result. When the driver determines that it is continuing, there is an effect that the creep speed command value is changed and the driving can be performed by the creep speed command corresponding to the actual adhesive force.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a creep velocity-transmission force diagram used for explaining the basic concept of the present invention.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 6 is a block diagram showing an internal configuration of a rotation speed detector according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a fifth exemplary embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of an eighth exemplary embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a ninth exemplary embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a tenth exemplary embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a conventional electric vehicle control device that attempts to solve the problems in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 vehicle body 2 wheels 3 motor 4 rotation speed detector (means) 5 vehicle body speed detector (means) 6 first adder-subtractor 7 creep speed command generator (means) 8 second adder-subtractor 9 torque command calculator (means) ) 10 motor drive part 11 optimal creep speed search part 12 creep speed command adjustment part 13 wheel diameter calculator (means) 14 limiter 15 low pass filter 16 creep speed-adhesive force display monitor 17 creep speed command change button.

Claims (6)

[Claims] 1. An electric vehicle driven by a motor capable of variable speed driving, wheel rotation speed detecting means for detecting wheel rotation speed, vehicle body speed detecting means for detecting ground speed of a vehicle body, and creep speed command. A creep speed command generating means for outputting, a creep speed command calculating means for calculating the creep speed from the wheel rotation speed and the vehicle body speed, and a command value tracking control for the creep speed command to calculate a torque command, and the torque command calculating means And a motor drive unit that drives a motor from a torque command output by the inverter control device for an electric vehicle. 2. The inverter control device for an electric vehicle according to claim 1, further comprising an optimum creep speed search unit for inputting a torque command output from the torque command calculation means and outputting an optimum creep speed value. 3. The creep speed command adjusting unit for adjusting the creep speed command value output by the creep speed command generating means according to the optimum creep speed value output by the optimum creep speed searching unit. Inverter control device for electric car 4. A wheel diameter calculation means for outputting a wheel diameter calculation value by inputting a rotation speed output by the wheel rotation speed detection means and a vehicle body speed output by the vehicle body speed detection means, the wheel rotation speed detection means comprising: The inverter control device for an electric vehicle according to any one of claims 1 to 3, wherein the wheel diameter value is changed using the calculated wheel diameter value. 5. A creep speed-adhesion force display for displaying a two-dimensional adhesive force map on a driver's cab by inputting a torque command value output from a torque command calculation means and an optimum creep speed value output from an optimum creep speed search unit. An inverter control device for an electric vehicle according to any one of claims 1 to 4, further comprising a device. 6. A creep speed-adhesion force display device has a function of inputting a creep speed command output from a creep speed command generator and displaying a command adhesion force obtained from the creep speed command on an adhesion two-dimensional map. However, when the driver determines that the maximum value of the adhesive force map is lower than the command adhesive force, it has a creep speed command changing means having a function of changing the setting of the creep speed command generator by a predetermined operation. The inverter control device for an electric vehicle according to claim 5.