JPS6227602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a vehicle induction motor,
In particular, the present invention relates to a frequency control device for an AC power supply device in an electric vehicle driven by an induction motor.

Control of an induction motor for driving a vehicle is generally performed as shown in FIG. That is, an induction motor (hereinafter referred to as a motor) 2 that drives a wheel 1 is energized by a variable frequency AC power source 3. As this AC power source 3, a cycloconverter or an inverter (hereinafter collectively referred to as an inverter) is used depending on the type of overhead line voltage, but in either case, the structure is such that the output voltage and frequency can be changed. .

Normally, the torque characteristics of the motor 2 are controlled to match those of a DC series motor, particularly when chopper control is performed, so that the slip frequency is kept constant and the voltage-to-frequency ratio is kept constant.

In order to keep the slip frequency constant, motor 2
It is necessary to detect the rotational speed of the AC power source 3 and operate the AC power supply 3 so that the frequency is always a certain number higher than the rotational speed of the AC power source 3. For this reason, a speed generator or a pulse generator (hereinafter collectively referred to simply as a pulse generator) is generally connected directly to the shaft of the motor 2.
4 is attached, and the slip frequency _S is added to its output frequency ₀ to determine the operating frequency of the inverter 3.

However, this method causes the following inconvenience when, for example, the wheel 1 spins idly. When the train is accelerating, the torque of the motor 2 acts as a traction force due to the adhesive force between the wheels 1 and the rail, but when the adhesive force decreases due to changes in the condition of the rail surface, the wheels 1 begin to spin and the traction force is lost. I won't be able to do it. In this case, the load on the motor 2 becomes smaller and the speed suddenly increases, but since the pulse generator 4 is attached to the motor shaft, the frequency of the inverter 3 also increases as the speed increases. That is, since the condition of constant slip frequency is always maintained, the motor 2 completely exhibits a series winding characteristic, and even if it begins to idle, the torque does not decrease and the idle becomes more and more accelerated, quickly leading to a large idle. As described above, the method shown in FIG. 1 is not suitable as a vehicle drive method.

In order to eliminate such drawbacks, a method as shown in FIG. 2 has also been proposed. The difference from FIG. 1 is that the pulse generator 4a is attached to the non-driving wheel 5. When the wheels 1 and 5 are not idling, the output frequency ₀ ' of the pulse generator 4a is
Since the gear ratio and wheel diameter are the same as those of the wheel 1, there is a one-to-one correspondence with the rotational speed of the motor 2, and there is no difference in principle from the system shown in FIG. In this system, the frequency of the inverter 3 is always determined according to the train speed. During acceleration, the inverter frequency is always higher than the rotational frequency of the motor 2 by the amount of the slip frequency _S , so the driving torque remains constant.
If idling occurs at this time, the speed of the motor 2 will suddenly increase. However, even if the condition of the rail surface changes, the non-driving wheels 5 do not produce tractive force, so they do not idle, and therefore the pulse generator 4a always accurately detects the train speed. Therefore, even when the wheel 1 is idling, the inverter frequency does not suddenly change and remains almost the same as the frequency immediately before the wheel idling. Therefore, when the speed of the motor 2 increases due to idling, the difference between the inverter frequency and the rotational frequency of the motor 2, that is, the slip frequency, becomes smaller, and the output torque of the motor 2 decreases. Therefore, in this system, the motor 2 exhibits a shunt characteristic when idling, and the wheel 1 can be immediately re-adhered without causing a large idling.
As described above, the method shown in FIG. 2 is an effective method for driving a vehicle, but it has the following problems when put into practical use.

The output frequency ₀ ' of the pulse generator 4a is
Although it was mentioned earlier that there is a one-to-one correspondence with the rotational speed of the motor 2, this state is not always maintained. That is, the wheel 1 idles when power is transmitted and is therefore subject to severe wear, but the wheel 5 simply rolls and therefore does not wear out as much. For this reason, a difference in wheel diameter gradually arises, and the wheel treads are sometimes machined, so the diameter ratio of wheels 1 and 5 may vary greatly.

Therefore, in this system, the wheel diameters must be strictly controlled so that the wheels 5 are re-sharpened from time to time so that the diameters of the wheels 1 and 5 are always equal within a certain error. This would increase maintenance effort and cannot be put into practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a vehicle induction motor that can automatically control the frequency of an AC power supply to always keep the slip frequency constant, while eliminating the drawbacks of the prior art described above.

To achieve this objective, the present invention provides an output that depends on the rotational speed of the motor when it is not idling and an output that depends on the actual vehicle speed that is not affected by idling, that is, the rotational speed of the non-driven wheels that are not driven by the motor. Find a correction coefficient according to the ratio of the output, store it, use the stored correction coefficient to correct the output according to the vehicle speed, and adjust the operating frequency of the AC power supply according to the corrected output. It is characterized in that it can be set.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 3 is a schematic configuration diagram showing an inverter-controlled induction motor drive system according to an embodiment of the present invention.

The pulse generator 4a is attached to the non-driving wheel 5 as in the case of FIG. This pulse generator output frequency does not necessarily correspond one-to-one to the rotational speed of the motor 2 due to the difference in diameter between the wheels 1 and 5. However, it is certain that they always correspond with a proportionality coefficient determined by the wheel diameter ratio at that time. If this proportionality coefficient is k, then the pulse generator output frequency is 1/k
If it is set, there will be a one-to-one correspondence with the motor rotation speed. Therefore, if a frequency correction circuit 6 is provided, its output frequency ₀ '' becomes ₀ , which is the same as in the case of FIG. 1.The correction coefficient of this correction circuit 6 is 1/
Accurate frequency control can be achieved at all times by readjusting k according to wheel wear or grinding, for example during periodic inspections, but relying on manual labor is undesirable because it increases the amount of maintenance.

For this reason, a correction coefficient setting circuit 7 is provided to automatically set the correction coefficient so that the frequency of the pulse generator 4 attached to the motor 2 and the output frequency of the correction circuit are equal to each other when the vehicle is coasting, that is, when the wheels are not idling. I'm trying to fix it.

In other words, the output frequency of the correction circuit 6 during coasting
₀ '' and the output frequency ₀ of the pulse generator 4 is provided, and the correction coefficient setting circuit 7 sets the correction coefficient 1/1 so that the output becomes zero.
Set k. The correction coefficient 1/k is maintained as is when the vehicle is regenerating power or stopped.

As the correction circuit 6, one as shown in FIG. 4 can be considered. Output frequency of pulse generator 4a
₀ ' is converted into a DC voltage by the FV converter 9, and amplified by the amplifier 10 to become the DC voltage V.
This DC voltage V is applied to the resistor 11 and the resistor groups 12 to 1.
9, the divided pressure output becomes v. The VF converter 28 returns the frequency to ₀ ''.Resistor groups 12-19 are grounded by transistor switch groups 20-27, respectively.Resistor groups 12-19 are grounded by transistor switch groups 20-27, respectively.
If the combined impedance of 19 is Z and the resistance value of resistor 11 is r, then the divided voltage output v is v=Z/r+ZV...(1) Therefore, the correction coefficient is 1/k=Z/r+Z...(2) ) ∴k=r+Z/Z=1+r/Z...(3) If the combined admittance of resistor groups 12 to 19 is Y, equation (3) is k=1+r・Y...(4) Here, resistor 12, The admittance ratio of 13, 14..., 19 is 1:2:4:8:16:32:64:
If the resistance value is determined to be 128, k
The value can be changed in 256 steps. As mentioned above, k is the proportional coefficient between the output frequencies ₀ and ₀ ' of the pulse generators 4 and 4a, which is determined by the wheel ratio of wheels 1 and 5, so if the circuit shown in FIG. 4 is used, the wear of the wheels will be reduced. It can be seen that this change in the proportional coefficient can be dealt with in 256 steps. The correction coefficient 1/k is set by applying an 8-bit signal to each base of the transistor switch group.

Next, the correction coefficient setting circuit 7 and the comparison calculation circuit 8
An example of this is shown in FIG. 5, but for convenience of explanation, the correction circuit 6
It will also be posted.

The output ₀ '' of the V-F converter 28 and the output ₀ of the pulse generator 4 are applied to a phase comparator 29 of the comparison calculation circuit 8.The output of this phase comparator 29 is passed through a low-pass filter 30 to a _DC voltage v
and is compared with the input voltage v of the VF converter 28 by the operational amplifier 31. This output is given to two comparators 33 and 34 of the correction coefficient setting circuit 7 through a switch element 32. These two comparators are provided with minute positive and negative voltages +ΔV and -ΔV as reference voltages, respectively, with the polarities shown in the figure, so when the input voltage is positive, the output of the comparator 33 is "1", and when the input voltage is negative, At times, the output of the comparator 34 is "1", and when the input voltage is less than ±ΔV, the outputs of both comparators are "0", and these two comparators eventually constitute an input voltage polarity discrimination circuit. This discrimination output is an AND gate 35,
When the output of the comparator 33 is "1", a clock signal is passed to make the up-down counter 37 count up, and when the output of the comparator 34 is "1", a clock signal is passed to make the up-down counter 37 count down. In this way, the correction coefficient setting circuit 7 increases the output 8-bit binary signal when v−v ₁ >0, and
When -v ₁ <0, it decreases, and when v-v ₁ =0, it works to maintain the same value.

When the output 8-bit binary signal of the correction coefficient setting circuit 7 is applied to the bases of the aforementioned transistor switch groups 20 to 27, the voltage division ratio changes according to the value of the binary signal, and the value of v can be adjusted.

When the control loop is constructed as shown in FIG. 5, it forms a kind of phase lock loop. In other words, if ₀ ''> ₀ now, the phase comparator 29 detects the frequency difference between the two (phase is the integral of frequency, so frequency detection is performed by phase detection) and lowers v ₁ . Ru.
Then, the output of the operational amplifier 31 becomes negative, decreasing the output binary signal of the up-down counter 37 and lowering v. After all, ₀ ″= ₀ , v=v ₁
However, since the output frequency of the pulse generator 4a at this time is ₀ ', the correction circuit 6 has adjusted the correction coefficient so that ₀ '→ ₀ ''= ₀ .

If you make the above adjustments during the coasting period and leave the switch 32 open, the up-down counter 37
remains as it is, so the correction circuit 6 performs accurate frequency correction for the time being. This correction coefficient adjustment work is performed automatically when the switch element 3
2 for a few seconds.

According to this embodiment, since the phase lock loop is used, the F-V converter 9 and the V-
An accurate correction coefficient can be set by correcting the error of the F converter 28 as well.

FIG. 6 is a block diagram showing the main parts of an inverter-controlled induction motor drive system according to another embodiment of the present invention.

During the coasting period, the output ₀ of the pulse generator ₄ and the output ₀ ' of the pulse generator 4a are applied to the divider 38 through the switch element 32, and the ratio _0/0 ' of these outputs ₀ and ₀ ' is determined. is memorized and this ratio _0/0 ' is multiplied by the output ₀ ' of the pulse generator 4a by the multiplier 39 and output _.
0 ″ is obtained. In this way, the output of the multiplier 39
Since ₀ '' is ₀ ''= ₀ '×( _{0/0 '} )= ₀ , the output ₀ ' of the pulse generator 4a has been corrected to a value equal to the output ₀ of the pulse generator 4.

7 shows an embodiment in which the correction circuit 6, correction coefficient setting circuit 7, and comparison calculation circuit 8 in FIG. 3 are replaced with a microcomputer 40.

Output ₀ of pulse generators 4, 4a,
₀ ' and the coasting signal S _d are input to the microcomputer 40, and only during coasting when the coasting signal S _d is input, the output ₀ of the pulse generator 4 and the output ₀ ' of the pulse generator 4a are currently set. Compare the value multiplied by the correction coefficient 1/k, that is, the output ₀ ″ of the microcomputer 40, and increase the correction coefficient 1/k until the outputs ₀ and ₀ ″ match.
When k is corrected and the two match, the correction coefficient 1/k at that time is memorized, and from now on, the output ₀ ' of the pulse generator 4a is corrected with this correction coefficient 1/k.
₀ ″ = ₀ correction output ₀ ″ is obtained.

That is, the microcomputer 40 is programmed according to a flowchart as shown in FIG.

According to this embodiment, the pulse generator 4a
All processing for correcting the output ₀ ' of the pulse generator 4 to a value equal to the output ₀ of the pulse generator 4 can be performed by the microcomputer 40, so it is possible to temporarily use the microcomputer provided for other purposes. It can be realized with a simple configuration.

As explained above, according to the present invention, the output according to the rotational speed of the non-driven wheels that are not driven by the motor is made equal to the output according to the rotational speed of the motor when it is not idling. This is automatically corrected and the operating frequency of the AC power supply is set according to the corrected output, thereby eliminating the drawback of promoting idling and leading to large idling, and increasing maintenance effort. Therefore, accurate frequency control can be performed at all times.

[Brief explanation of the drawing]

1 and 2 are schematic configuration diagrams showing each example of a conventional inverter-controlled induction motor drive system, and FIG. 3 is a schematic configuration diagram showing an inverter-controlled induction motor drive system according to an embodiment of the present invention. 4
The figure is an electric circuit diagram showing a specific example of the correction circuit shown in FIG. 3, and FIG. 5 is an electric circuit diagram showing a specific example of the correction circuit, correction coefficient setting circuit, and comparison calculation circuit shown in FIG. FIG. 6 is a block diagram showing the main parts of an inverter-controlled induction motor drive system according to another embodiment of the invention, and FIG. 7 is a main part of an inverter-controlled induction motor drive system according to still another embodiment of the invention. FIG. 8 is a flowchart showing a method of programming the microcomputer of FIG. 1... Drive wheel, 2... Motor, 3... Inverter,
4, 4a... Pulse generator, 5... Non-driven wheel, 6... Correction circuit, 7... Correction coefficient setting circuit, 8...
Comparison calculation circuit, 38...Divider, 39...Multiplier, 4
0...Microcomputer.

Claims (1)

[Claims] 1. An induction motor that drives a vehicle, an AC power supply that energizes the induction motor, and a first motor that outputs an output according to the rotational speed of a non-driven wheel that is not driven by the induction motor. In an induction motor drive electric vehicle control device comprising a speed detection device and a frequency control circuit that sets a driving frequency of the AC power supply according to the output of the first speed detection device, A second speed detection device that outputs a corresponding output, and a second speed detection device that outputs a corresponding output when the speed is not idling.
means for determining a correction coefficient according to the ratio of the output of the speed detection device and the output of the first speed detection device, means for storing this correction coefficient, and said frequency control using the correction coefficient stored in said storage means. A control device for an induction motor for a vehicle, comprising a correction means for correcting an output of the first speed detection device input to a circuit. 2. In claim 1, the means for determining the correction coefficient compares the output of the first speed detection device corrected by the correction means and the output of the second speed detection device, and determines the difference therebetween. 1. A control device for an induction motor for a vehicle, characterized in that the correction coefficient is set so that the value becomes zero. 3. The control device for an induction motor for a vehicle according to claim 1, wherein the means for determining the correction coefficient, the storage means, and the correction means are each comprised of a microcomputer.