JPH0591602A - Electric vehicle control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To eliminate the imbalance between vehicles due to the difference in wheel diameter between multiple drive shafts, and to increase the level of the adhesion coefficient of each drive shaft to increase the traction force of the entire vehicle. Let [Structure] The drive motors of the respective drive shafts are individually controlled by inverters provided corresponding to the respective drive motors. For example, the inverter INV1 controls only the first axis drive motor IM1. The slip frequency calculating means 14 in the inverter INV1 is the first speed sensor PG mounted on the driving wheel.
Signal from 1 and second speed sensor PG mounted on the driven wheel
The signal from _A is input and the optimum slip frequency fs1 according to the wheel diameter of the first shaft is calculated. As a result, the value of the inverter output frequency f _INV becomes a value at which a desired tread torque can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle controller for operating a plurality of drive motors by controlling the slip frequency of an inverter.

[0002]

2. Description of the Related Art As a drive system for an electric vehicle, a VVVF inverter control system, which supplies electric power of variable voltage and variable frequency to a drive motor such as a three-phase AC squirrel-cage induction traction motor to control the speed, is currently the mainstream. Is becoming

In this inverter control system, a system (1C4M control) in which four drive motors are collectively controlled by one inverter is usually adopted. However, recently, with the development of semiconductor manufacturing technology, it is possible to increase the capacity of GTO thyristors and power transistors used in inverter control devices, and the number of drive motors that can be controlled by one inverter increases. is doing. And
At present, a method (1C8M control) of collectively controlling as many as eight drive motors by one inverter has been put into practical use.

In controlling the speeds of a plurality of drive motors by such an inverter control system,
It is general to perform so-called slip frequency control.
The slip frequency control is to detect the rotation speed n of the drive motor as a feedback element, and determine the optimum slip frequency f from the detected value and a preset slip frequency pattern.
_The inverter output frequency f is obtained by obtaining _s and adding this slip frequency f _s to the rotor frequency f _r (during power running).
It is a closed loop control that tries to determine _INV .

FIG. 7 shows the case where such a slip frequency is used.
It is a schematic block diagram of the electric vehicle control apparatus which performs 1C4M control. In this figure, the DC power collected by the pantograph 1 is the unit switch 2, the filter reactor 3,
Inverter 6 via GTO 4 and filter capacitor 5
Entered in. A charging resistor 7 for charging the filter capacitor 5 and a brake diode 8 for flowing a regenerative current during regeneration are connected in parallel to the GTO 4. In addition, 9 is a ground switch.

The inverter 6 converts the DC power input in this way into AC power, controls the variable voltage and variable frequency, and controls the four driving motors (induction motors) IM _{1 to} IM.
It is output to M ₄ . Each of the wheels rotatably driven by each of these drive motors has a speed sensor PG ₁ -PG.
₄ is attached, it has an average value of detection values f _r1 ~f _r4 so as to perform frequency control slip by using the rotor frequency f _r.

[0007]

By the way, while the electric vehicle is being operated for a long period of time, the wheel diameters of the wheels attached to the drive motors gradually decrease due to wear. The degree of this reduction is usually different for each wheel.

Accordingly, as shown in FIG. 7, in the system in which the _four drive motors IM _{1 to} IM ₄ are collectively controlled by the single inverter 6, the electric vehicle is controlled with the shaft torques of the respective wheels being different. Will be performed. Conventionally, it has been considered that such a difference in wheel diameter between the wheels is unavoidable to some extent, and no control has been particularly performed in consideration of the difference in wheel diameter.

However, in recent years, control technology has been developed in various fields, and even in electric vehicle control, more advanced control technology is required in order to improve accuracy, reliability, safety and comfort. Is becoming popular.

Therefore, the inventors of the present invention examine the control problem caused by the difference in the wheel diameters and solve the problem to improve the controllability of the electric vehicle. Was successful.

This problem is due to the fact that the tread torques of the wheels are different, the traction forces between the connected vehicles are different, and the adhesion coefficient is different for each wheel. It is not possible to increase the traction force of one vehicle as a whole.

In the following, a detailed study will be added to each of these two problems. (1) Regarding tread torque: FIG. 8 is a characteristic diagram obtained when the electric vehicle control device having the configuration of FIG. 7 is powered. In this figure, T _p is the tread torque (traction force) of the wheel, and the solid line, the broken line, and the alternate long and short dash line respectively show the case of the reference wheel diameter, the case of the small wheel diameter, and the case of the large wheel diameter.

I _M is the motor current (effective value), V
_M is the motor voltage (effective value), f _INV is the inverter output frequency, and f _s is the slip frequency. It should be noted that mode 1 is a starting characteristic of an electric vehicle controlled by an inverter, and is a region where the motor voltage V _M is forcibly raised. That is, since it is an area outside the scope of the present invention, it is left blank. Mode 3 in which the slip frequency f _s changes is also outside the scope of the present invention. Therefore, the target of the present invention is the region of mode 2 in which the slip frequency is constant.

By the way, the inverter frequency f _INV during power running [H _Z] is f _INV = f _r + f _s, and the inverter frequency f _INV during regeneration becomes f _INV = fr -f _s.

Meanwhile, the relationship between the speed of the electric vehicle V [Km / h] and the wheel diameter WD [mm], if the constants K _1, is represented by _{V = K I · WD · f} r. Therefore, the rotor frequency f _r becomes _{f r = V / (K 1} · WD).

Further, the reference wheel diameter is WD ₀ , the smaller and larger diameters are WD ₁ and WD _2, and the inverter frequencies to be made to correspond to the respective wheel diameters at the speed V ₀ are f _{INV0 (V 0)} , F _{INV1 (V0)} , f _{INV2 (V0)} ,
For example, each inverter frequency during power running is f _{INV0 (V0)} = V ₀ / (K ₁ · WD ₀ ) + fs _s f _{INV1 (V 0)} = V ₀ / (K ₁ WD ₁ ) + fs _s f _{INV 2 (V 0). = V 0 / (K 1 ·} WD 2) a + f _s. Here, since the value of f _s is fixed, from WD ₂ > WD ₀ > WD ₁ , f _{INV2 (V 0)} <f _{INV 0 (V 0)} <f _{INV 1 (V 0)} . In this way, if the wheel diameter is different, the inverter frequency to be output corresponding to the different wheel diameter should originally have a different value.

Nevertheless, in the method of controlling a plurality of drive motors by one inverter as shown in FIG. 7, such a difference in wheel diameter is ignored and the average frequency f
It is the result of being operated collectively by _INV . Therefore, the values of the tread torque T _p and the axial torque T _o are different for each wheel.

Here, the relationship between the tread torque T _p and the axial torque T _o will be briefly described. Normally, both can be considered as T _p · r = T _o, with the wheel radius r (= WD / 2). However, in order to perform more advanced control, it is necessary to consider T _p · r = T _o · g _r · η _r in consideration of the gear ratio g _r and the gear efficiency η. Therefore, if the function of the axial torque T _o when the wheel radius r is a variable is T _{o (r)} and the constant is k, then the above equation can be expressed as T _p = k · T _{o (r)} / r You can

In this expression, since the variable r is included in both the numerator and the denominator, even if the magnitude relation of the wheel radius r or the wheel diameter WD is determined, the magnitude of the tread torque T _p is accordingly changed. Relationships are not decided immediately. Therefore, in FIG. 7, the tread torque T _p is the smallest when the wheel diameter is large (dashed line), but this is merely an example, and the reverse case is also possible.

However, regarding the axial torque T _o , if the magnitude relationship between the wheel diameters is known, the magnitude relationship can be immediately known. That is, FIG. 9 is a diagram showing a slip torque characteristics of the motor, according to this, the value of it is the shaft torque T _o of the wheel large diameter if e.g. the normal powering control range becomes large ..

When a plurality of drive motors are controlled by one inverter as described above, the tread torques take different values due to the different wheel diameters. This is when considering one whole vehicle,
This means that the accuracy of control of the traction force of this vehicle cannot be increased above a certain level.

Therefore, in the case of a train composed of a plurality of vehicles, a force for pushing and pulling against the coupler between the vehicles is generated, and particularly in the case of a passenger train, the comfort is deteriorated. It was (2) Adhesion coefficient: In FIG. 7, the average wheel diameter of the four drive shafts is D _A , the average shaft torque is T _OA, and the average wheel diameter D _A and the wheel diameter difference of a certain shaft are ΔD,
Torque unbalance, which is the difference from the average shaft torque T _OA , is
Letting T be the relationship between them (ΔT / T _OA ) = [(1 / S) −1] · (ΔD / 2D _A ). In addition, S is a slip.

As is clear from this equation, the larger the wheel diameter difference ΔD between the shafts, the larger the torque imbalance amount ΔT, and accordingly, the shaft that is liable to idle is generated in proportion to this.

On the other hand, there is an adhesion coefficient μ as a coefficient representing the degree of tendency of slipping. Now, assuming that the adhesion coefficient of the i-th axis (i = 1, 2, 3, 4 in FIG. 7) is μ _i and the tread torque and the axial load are T _pi and W _i , respectively, the adhesion coefficient μ
_i is defined as μ _i = T _pi / W _i . The expected adhesion coefficient μ _e is the adhesion coefficient that can be maximized without causing slipping. In order to reduce the MT ratio of the vehicle and meet the demand for cost reduction, it is preferable to design this value as high as possible.

As described above, the magnitude relation of the wheels between the drive shafts does not always reflect the magnitude relation of the tread torque between the drive shafts. However, in this case, in order to simplify the explanation, it is assumed that the magnitude relationship between the wheels directly reflects the magnitude relationship between the axial torque and the tread torque.

That is, the wheel diameters D _{1 to} D of the first to fourth shafts
_If the magnitude relationship of ₄ is D ₁ <D ₂ <D ₃ <D ₄ , the tread torque T of each axis at a certain time point
The magnitude relation of _{p1 to} T _p4 is T _p1 <T _p2 <T _p3 <T _p4 . Therefore, if the axial weights W _{1 to} W _{4 of} the respective axes are W ₁ = W ₂ = W ₃ = W ₄ , then the adhesion coefficients μ _{1 to} μ ₄ of the respective axes at this time.
The magnitude relation of is μ ₁ <μ ₂ <μ ₃ <μ ₄ .

This means that when the value of the adhesion coefficient of each axis gradually increases, the fourth axis first reaches the expected adhesion coefficient μ _e4 . However, at this point, the adhesion coefficients of the first axis to the third axis have not yet reached the level of the respective expected adhesion coefficients, and especially for the first axis, there is a considerable margin before reaching the expected adhesion coefficient. It has been left.

However, in the method of controlling four drive motors with one inverter as shown in FIG. 7, when the fourth shaft reaches the expected adhesion coefficient μ _e4 , the tread torque or shaft torque further increases. It will be something that must be controlled not to do so. That is, since the configuration of the conventional device of FIG. 7 has a limitation of preventing occurrence of idling of the fourth shaft, the upper limit value of the tread torque of the other shaft must be suppressed to a level equal to or lower than the expected adhesion coefficient. Therefore, when trying to increase the traction force of the vehicle as a whole, the result is that it acts as a negative factor.

The present invention has been made in view of the above circumstances, and it is possible to improve the accuracy of the control of the traction force of the entire vehicle, and to set the upper limit of the tread torque of each drive shaft to the respective expected adhesion. It is an object of the present invention to provide an electric vehicle control device capable of increasing the traction force of the entire vehicle by raising it to a level corresponding to the coefficient.

[0030]

As a means for solving the above-mentioned problems, the present invention provides an electric vehicle controller for operating a plurality of drive motors by controlling the slip frequency of an inverter, wherein the inverter is provided for each drive motor. One by one, with a first speed sensor for each drive wheel,
A second speed sensor is provided on one of the driven wheels, and each inverter calculates the wheel diameter of its driving wheel based on the detection signals from both speed sensors, and the calculated wheel diameter is preset. The configuration is provided with a slip frequency calculating means for calculating a ratio with a reference diameter and correcting a value obtained based on a preset slip frequency pattern according to this ratio.

The slip frequency calculating means of each inverter may be configured to correct the calculated value according to the detected current value of the drive motor. Further, the slip frequency can be calculated according to the axial load detection value of the drive shaft so that a desired adhesion coefficient can be obtained.

[0032]

According to the above construction, each drive motor is individually controlled by the corresponding inverter. Therefore, even if the wheel diameters of the drive shafts are different, the drive motors are controlled according to the wheel diameters.

In this case, the slip frequency calculating means of each inverter first receives the detection signals from both the first speed sensor and the second speed sensor. Since the difference in wheel diameter appears as the difference in rotation speed, the size of the wheel diameter of the driving wheel can be obtained based on the detection signals from these two sensors. The ratio between the diameter and the reference diameter can be calculated.

Next, the slip frequency calculating means calculates a slip frequency which is a predetermined value from the value obtained by the preset slip frequency pattern and this ratio, and the calculated slip frequency is used to calculate the frequency of the inverter. Take control.

In this way, the difference in wheel diameter is taken into consideration, and the optimum frequency control corresponding to the wheel diameter is performed for each drive wheel, whereby the accuracy of controlling the tread torque can be improved, and The upper limit value of the tread torque of each drive wheel can be raised to the level of each expected adhesion coefficient.

The slip frequency calculating means of each of the above-mentioned inverters can be configured to perform the correction with the calculated slip frequency value according to the detected current value of each drive motor. According to this, it is possible to further improve the reliability of the control for setting the tread torque to a predetermined value.

Further, the slip frequency calculating means of each inverter may be configured to calculate the slip frequency value according to the axial load detection value of each drive shaft. According to this, it is possible to optimally control the above-mentioned tread torque regardless of the loading condition of the vehicle, and to raise the value of the adhesion coefficient to a desired value, for example, the level of the expected adhesion coefficient. You can

[0038]

Embodiments of the present invention will be described below with reference to FIGS. However, the same components as those in FIG. 7 are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 3 is a schematic configuration diagram showing a main circuit connecting portion of the electric vehicle controller according to the first embodiment. The configuration of FIG. 3 differs from that of FIG. 7 in that the drive motors IM _{1 to} IM
₄ corresponding to respective inverters INV ₁ INV ₄
Are provided, and these drive motors can be individually controlled. As in the case of FIG. 7, speed sensors PG _{1 to} PG ₄ (first speed sensors) are attached to the respective drive wheels, and the detection signals of these are provided in the inverter I.
It is designed to be sent to NV _{1 to} INV ₄ . In the configuration of this figure, the speed sensor P is attached to one of the driven wheels.
G _A is provided, and this detection signal also applies to each inverter I.
It is designed to be sent to NV _{1 to} INV ₄ .

FIG. 1 shows the inverter INV ₁ in FIG.
~ INV ₄ shows the configuration of the inverter INV ₁ . The configurations of the inverters INV _{1 to} INV ₄ are the same as those of the inverters INV _{1 to} INV ₄ . As shown in this figure, the inverter INV ₁ includes the inverter unit 10,
It has a PWM control circuit 11, a modulation factor calculation circuit 12, a pulse mode determination circuit 13, and a slip frequency calculation means 14. Then, and is input to the detection signal f _r1, f _rA is the slip frequency calculation means 14 from the speed sensor PG _1, PG _A attached to the wheels of the first shaft. Further, a voltage detector 15 is connected in parallel with the filter capacitor 5,
The detection signal is input to the modulation rate calculation circuit 12 and the pulse mode determination circuit 13. Here, the modulation factor calculation circuit 12 determines the voltage V _{c of the} filter capacitor 5.
_Is a circuit for outputting a modulation rate according to the value of the frequency signal f _INV1 to the PWM control circuit 11 while monitoring Further, the pulse mode determination circuit 13 determines that the capacitor voltage V _c
Is a circuit for determining the pulse mode in accordance with the value of f _INV by using for adjusting the switching timing. And P
The WM control circuit 11 receives the signals from the modulation rate calculation circuit 12 and the pulse mode determination circuit 13 and the frequency signal f.
PW for the inverter unit 10 based on the input with _INV1
Outputs M control command signal.

FIG. 2 is a block diagram showing the structure of the slip frequency calculating means in FIG. In this Figure, the detection signal from the speed sensor PG _1, PG _A rotational speed amplifier 1
6 and 17, the rotational speed ω ₁ of the drive wheel of the first shaft and the rotational speed ω _A of the driven wheel are output. Speed ratio calculation circuit 18
Calculates the rotation speed ratio K ₁ = (ω ₁ / ω _A ) of these wheels and outputs the signal to the wheel diameter calculation circuit 19.

The wheel diameter calculation circuit 19 calculates the rotation speed ratio K ₁ and
From the wheel diameter WD _A of the driven wheel to the wheel diameter WD of the drive wheel of the first shaft
Calculate ₁ The shaft torque pattern circuit 20 has a wheel diameter W.
The signals of the axial torque T _{0 (r1)} corresponding to D ₁ and the axial torque T _{0 (r0)} corresponding to the virtual reference wheel diameter WD ₀ are output.
It should be noted that such a characteristic curve between the wheel diameter and the shaft torque corresponding thereto has been clarified in advance by experiments or the like.

The correction coefficient calculation circuit 21 determines the axial torque T
_{0 (r0),} T ₀ and the correction coefficient K ₀ from the wheel diameter WD _0, WD ₁ Tokyo _{(r1) K 0 = (WD} 1 / WD 0) · (T 0 (r1) / T 0 (r0)) of Calculate using an expression.

On the other hand, the f _s pattern circuit 22 inputs the notch command and the reference frequency command, and outputs the reference slip frequency f _s0 for the reference wheel diameter WD ₀ for each notch to the pattern value correction circuit 23. Pattern value correction circuit 23
Outputs a slip frequency f _s1 for the drive wheel of the first shaft by multiplying the reference frequency f _s0 by the correction coefficient K ₀ .
The PWM control circuit 11 in FIG. 1 adds a frequency f _INV1 obtained by adding the slip frequency f _s1 calculated in this way and the rotor frequency f _r1 from the speed sensor PG ₁ to the drive wheel of the first shaft. P as the inverter output frequency
Perform WM control. As a result, the tread torque T _p1 of the drive shaft of the first shaft can be controlled to a predetermined value. The above is the operation of the inverter INV ₁ that controls the drive wheels of the first shaft, but the inverters INV _{2 to} INV ₄ that control the drive wheels of the second to fourth shafts also operate in the same manner. Do.

In this way, the drive wheels of the first to fourth axes are individually driven by the drive motors IM _{1 to} IM ₄ , and the inverter IN is driven according to the difference in the wheel diameter of each drive wheel.
Since the slip frequencies f _{s1 to} f _s4 of V _{1 to} INV ₄ are adjusted, the tread torques T _{p1 to} T _{p4 on} each axis are adjusted.
Can be controlled to be a predetermined value (for example, the same value as each other). That is, in a train in which a plurality of vehicles are connected, it is possible to prevent a difference in the tread torque, that is, the traction force between the vehicles, and to prevent the force of pushing and pulling against the coupler. Therefore, it is possible to improve comfort, which has an important meaning in passenger trains and the like, without managing the wheel diameter, and it is possible to solve the first problem described in the related art.

Regarding the second problem, by changing the respective patterns of the axial torque pattern circuit 20 and the f _s pattern circuit 22 of the slip frequency calculating means 14 in FIG. 2 to a pattern considering the expected adhesion coefficient. It can be resolved in the same way. In fact, in the conventional device shown in FIG. 7, the value of the average adhesion coefficient μ _A of the first axis to the fourth axis is about 18
However, according to the apparatus of the present embodiment, the adhesion coefficient of each axis can be increased to the level of the expected adhesion coefficient, and as a result, the value of the average adhesion coefficient μ _A is increased to about 23%. I was able to do it.

FIG. 4 is a characteristic diagram obtained when power running is performed on the electric vehicle controller having the configuration of FIGS. 1 to 3. As shown in this figure, the value of the tread torque T _p is set to a flat state, that is, a constant value during the period of the mode 2. Further, the values of the respective parameters take different values depending on the size of the wheel diameter. However,
As described in the prior art, since the tread torque T _p is determined by the two functions r and T _{0 (r)} , the magnitude relation of the parameters corresponding to the magnitude relation of the wheel diameters is not always as shown in the figure. It doesn't mean

FIG. 5 is a block diagram showing a part of the second embodiment and corresponds to FIG. 2 showing a part of the first embodiment. That is, the inverter IN in this figure
V _1A is the same as I _{M in} the configuration of the inverter INV ₁ in FIG.
The configuration is such that a pattern circuit 24 is added. And
The drive motor IM ₁ is provided with a current detector 25 for detecting the motor current I _M , and the deviation between the detected value and the I _M pattern circuit 24 is input to the slip frequency calculating means 14. ing. Slip frequency calculation means 1
4 further corrects the slip frequency calculated by the configuration shown in FIG. 2 based on this deviation.

According to the configuration of FIG. 5, the reliability of the slip frequency f _s1 output from the slip frequency calculating means 14 can be further improved. That is, according to the characteristic diagram of FIG. 4, the difference in the wheel diameters of the respective drive shafts means that the motor current I
It appears as a difference in the level of _M. Therefore,
Since the wheel diameter can be estimated from the detected value of the motor current I _M , the reliability of the calculated slip frequency f _s1 can be improved by performing the correction in consideration of the detected value.

The first and second embodiments described above can solve the problem of the imbalance of the tread torque or the adhesion coefficient, which has occurred in the conventional device due to the difference in the wheel diameters of the drive shafts.

By the way, in the first and second embodiments, it is assumed that the axial loads of the respective drive shafts are the same, and there is no difference in the magnitude or distribution of the axial loads. Not a problem. However, in reality, there may be a large difference in the axial load between the drive shafts due to the distribution of personnel or load in the vehicle, the axial load fluctuation during acceleration / deceleration traveling, the movement of the axial load position during slope traveling, etc. There is.

As described above, when there is a large difference in the axial load between the drive shafts, a desired value of the adhesion coefficient cannot be obtained by correcting the slip frequency by considering only the difference in the wheel diameters. It is impossible.

Therefore, in the third embodiment shown in FIG. 6, the slip frequency can be calculated in consideration of not only the difference in the wheel diameters of the drive shafts but also the difference in the axial loads of the drive shafts. Is configured.

The inverter INV _1B in FIG.
Inverter INV _1A configuration in μ pattern circuit 2
6 and a tread torque calculation circuit 27 are added. An axial load detector 28 is attached to the drive shaft, and the tread torque calculation circuit 27 determines the axial load detection value W ₁ and the adhesion coefficient value μ from the μ pattern circuit 26.
_{From 1} (preferably, μ ₁ is a value close to the expected adhesion coefficient level), the corresponding tread torque value T _p1 is calculated and output to the slip frequency calculating means 14.

The slip frequency calculating means 14 calculates the slip frequency value f _s10 corresponding to this T _p1 , and based on this f _s10 , the optimum frequency value f _s1 corresponding to the wheel diameter of the first shaft. Is calculated.

According to the third embodiment as described above, the value of the adhesion coefficient can always be controlled to a desired value even when the wheel diameters between the drive shafts are different and the shaft loads are different. .. The configuration of the third embodiment of FIG. 6 is merely the second problem in the problems of the prior art (the level of the adhesion coefficient for all drive shafts is not always sufficiently high). And is directly related to the elimination of the first problem (improving the precision of control of the tread torque in order to eliminate the pushing and inquiring of the coupler between vehicles). Not a thing.

Although the embodiments of the present invention and the effects thereof are generally as described above, the following secondary effects are derived from the present invention.

Conventional IC4M control or IC8M
In the control, it was necessary to carefully manage the wheel diameter in order to suppress the difference in the wheel diameter between the drive shafts to a certain value or less, but by using the device according to the present invention, such a wheel diameter Eliminates the need for management.

Conventional IC4M control or IC8M
In the control, it is necessary to increase the rated slip of the induction motor used for the drive motor (about 3%) in order to reduce the amount of unbalance of the shaft torque caused by the difference in the wheel diameter between the drive shafts. However, since each drive shaft is controlled individually, the rated slip is small (about 1.5
%)can do. Therefore, the induction motor can be made highly efficient, compact, and lightweight.

Since each drive shaft is individually controlled, even if any drive shaft is idly rotated for some reason, the inverter is adjusted only for the drive shaft according to the degree of idling. Since the frequency can be controlled, fluctuations in the traction force of the entire vehicle can be minimized and sudden changes can be prevented.

[0061]

As described above, according to the present invention, the drive motors of the respective drive shafts are individually inverter-controlled,
Since the configuration is such that the value of the slip frequency for each drive shaft is adjusted according to the size of each wheel diameter, it is possible to improve the accuracy of the control of the traction force of the entire vehicle, and
The upper limit of the tread torque of each drive shaft can be raised to a level corresponding to each expected adhesion coefficient to increase the traction force of the entire vehicle.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a slip frequency calculating means in FIG.

FIG. 3 is a schematic configuration diagram showing a main circuit configuration unit of the device according to the first embodiment.

FIG. 4 is a characteristic diagram showing a characteristic example of the first embodiment.

FIG. 5 is a block diagram showing a main part of a second embodiment of the present invention.

FIG. 6 is a block diagram showing a main part of a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an apparatus according to a conventional example.

FIG. 8 is a characteristic diagram showing a characteristic example of the conventional example.

FIG. 9 is a characteristic diagram showing a characteristic example of the conventional example.

[Explanation of symbols]

INV ₁ INV ₄ inverter IM ₁ to IM ₄ driving motor PG ₁ ~PG ₄ first speed sensor PG _A second speed sensor f _s slip frequency f _INV inverter output frequency 14 slip frequency control means 25 current detector 28 axis Load detector

Claims (3)

[Claims] 1. An electric vehicle controller for operating a plurality of drive motors by controlling the slip frequency of an inverter, wherein one inverter is provided for each drive motor, and a first speed sensor is provided for each drive wheel. And a second speed sensor is provided on one of the driven wheels, and each inverter calculates the wheel diameter of its driving wheel based on the detection signals from both speed sensors. An electrical device characterized by comprising a slip frequency calculating means for calculating a ratio with a set reference diameter and correcting a value obtained based on a preset slip frequency pattern in accordance with this ratio. Vehicle control device. 2. The electric vehicle controller according to claim 1, wherein each slip frequency calculating means corrects the calculated value in accordance with the detected current value of the drive motor. 3. The electric vehicle according to claim 1, wherein each of the slip frequency calculating means calculates the slip frequency in accordance with the detected axial load value of the drive shaft so that a desired adhesion coefficient can be obtained. Control device.