JP2006191736A - Re-adhesion control device of electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of acceleration or deceleration performance caused by idling or sliding by a simple and inexpensive constitution. <P>SOLUTION: A PID adjuster 16 is arranged with at least either of a rotation number deflection amount of a motor 2 obtained by a rotation number deflection amount operation part 12, and a time change rate deflection amount of the rotation number of the motor obtained by a deflection amount operation part 14 as an input, and a frequency command value with respect to the motor 2 or its torque command value is controlled by using the output value of the adjuster so as to be narrowed down to either or the command values, thus enabling the re-adhesion control of an electric vehicle by a re-adhesion control device that is simple in constitution and less in adjustment amount. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the control of an electric vehicle using a means for detecting or estimating the rotation frequency of a motor and a power conversion device such as an inverter, the present invention is in a normal state when a driven wheel is idled or slid. The present invention relates to a re-adhesion control device for making an adhesive state.

  FIG. 11 is a block diagram showing this type of control device disclosed in Patent Document 1, for example. In the figure, 1 is a power converter such as an inverter, 2 is an induction motor (motor), 3 is a pulse generator (PG), 4 is a rotation speed (frequency) calculator, 7 is a reference frequency selector, and 8 and 11 are A subtractor, 9 is a function generator, and 10 is a change rate calculator, which is an example of driving four motors as one unit. That is, all motors 2 are provided with PG 3, and the rotational frequency fr 1 to fr 4 of each motor 2 is obtained from the output signal of PG 3 by the rotational speed calculator 4. The rotation speed calculator 4 may be provided with a function (wheel diameter difference correction function) for correcting the difference in rotation frequency due to the variation in the diameter of the drive wheel by the rotation frequency during coasting.

  The rotation frequencies fr1 to fr4 obtained by the rotation number calculator 4 are input to the reference frequency selector 7, the subtractor 8, and the change rate calculator 10, respectively. In the reference frequency selector 7, a powering / braking signal is input in addition to the rotational frequency, and the minimum frequency among the rotational frequencies fr1 to fr4 is set during power running, and the maximum frequency among the rotational frequencies fr1 to fr4 is set during braking. Select as reference frequency fr (REF). The subtractor 8 calculates the difference between the frequencies fr1 to fr4 of each motor and the reference frequency fr (REF). Here, a power running / braking signal is also input to the subtractor 8, and the value is zero by subtracting the reference frequency from the rotational frequency of each motor during power running and subtracting the rotational frequency of each motor from the reference frequency during braking, or It is set to a positive value. Further, the change rate calculator 10 inputs the rotation frequencies fr1 to fr4 and calculates the time change rate of the rotation frequency.

  The difference between the rotation frequency calculated by the subtracter 8 and the reference frequency fr and the time change rate calculated by the change rate calculator 10 are input to the function generator 9. The function generator 9 outputs a value that is a reduction amount of the motor current command according to the input value. The output value of the function generator 9 is input to the subtractor 11, where it is subtracted from the original motor current command, and finally the motor current command input to the power converter 1 is output.

  By adopting the configuration as described above, until the idling or sliding state is detected, the motor current command is reduced in a certain pattern, and the motor rotating state in the idling or sliding state is changed. The reduction amount of the motor current command can be determined based on (the difference between the rotation frequency and the reference frequency, the time change rate of the rotation frequency). As a result, re-adhesion in accordance with the idling or sliding state can be achieved, and a decrease in the acceleration or deceleration performance of the electric vehicle can be minimized.

Japanese Patent No. 3246075 (5th page, FIG. 1)

In the apparatus of FIG. 11, acceleration or slipping due to idling or sliding is determined by determining the amount of narrowing of the motor current command in accordance with the behavior of the rotational frequency during idling or sliding that varies greatly depending on the adhesion state between the wheel and the rail. A reduction in deceleration performance can be minimized.
However, there are problems (1) and (2) below.
(1) The input / output characteristics of the required function generator must be created, which takes time and effort. This leads to an increase in development costs and, consequently, an increase in the price of the device.
(2) Attempting to improve performance leads to an increase in adjustment factors or an increase in the amount of information in the function generator, which increases the burden on the control device.

  Accordingly, an object of the present invention is to minimize a decrease in acceleration or deceleration performance due to idling or sliding with a simple and inexpensive configuration.

In order to solve such a problem, in the invention of claim 1, in the re-adhesion control device for an electric vehicle using the means for detecting or estimating the rotational frequency of the motor and the power converter,
A PID controller is provided that has a deviation value calculated from at least one of the detected value (estimated value) of the motor rotation frequency and the time change rate of the detected value (estimated value) of the motor rotation frequency as its input value. The value is used to narrow down at least one of a frequency command and a torque command for the motor.

  In the first aspect of the present invention, a threshold value is set for the input value of the PID adjuster, and when the input value of the PID adjuster is smaller than the threshold value, the input value of the PID adjuster is set. It can be zero (invention of claim 2). In the invention of claim 2, when the input value of the PID regulator is zero, the output value (integral term) of the PID regulator can be reduced to zero after a certain time (invention of claim 3). ). In the first to third aspects of the invention, a low-pass filter can be inserted into the output section of the PID adjuster (the fourth aspect of the invention).

  According to the present invention, the amount of narrowing down of the motor current command is determined in accordance with the behavior of the rotational frequency at the time of idling or sliding greatly changing depending on the adhesion state between the wheel and the rail with a simple configuration. It is possible to minimize a decrease in acceleration or deceleration performance due to idling or sliding. As a result, it is possible to provide a re-adhesion control device that is inexpensive and requires little adjustment (easily applied to other models).

FIG. 1 is a block diagram showing a first embodiment of the present invention.
In FIG. 1, 1 is a power conversion device such as an inverter, 2 is an induction motor (motor), 3 is a pulse generator (PG), 4 is a rotation speed (frequency) calculator, 11 is a subtractor, and 12 is a rotation speed calculation value. Rotational speed deviation amount calculation unit for calculating the deviation amount based on the above, 13 is a time change rate calculator for calculating the time change rate of the rotation speed from the rotation speed calculation value, and 14 is based on the time change rate calculation value of the rotation speed A deviation amount calculation unit for calculating a deviation amount, 15 is an adder, and 16 is a PID (P: proportional, I: integral, D: derivative) adjuster.

  As shown in FIG. 1, a feature of the present invention resides in that the PID controller 16 is used to perform re-adhesion control when the vehicle is idling or sliding. Therefore, first, the fact that re-adhesion control is possible with the PID controller will be described below. Note that idling is a phenomenon during power running and sliding is a phenomenon during braking, but the generation principle and re-adhesion method are basically the same, although there are differences in the sign and the change in the amount of change. In the following, the case of idling will be described as an example.

When idling occurs, the motor rotation speed of the shaft where idling occurs becomes higher than the motor rotation speed of the other axles. The reason why idling occurs is that the torque generated by the motor exceeds the adhesive force of the wheels. In order to avoid this idling state, the following two methods are basically conceivable.
(1) Increase the adhesion between the wheel and the rail.
(2) Reduce the torque generated by the motor.

As means for realizing the above (1), it is possible to scatter sand on the wheels and rails. Here, it is considered to re-adhere by the method (2).
That is, when idling occurs, the torque is quickly reduced. However, if the aperture is reduced more than necessary, the acceleration characteristics will deteriorate. In order not to deteriorate the acceleration characteristics, it is necessary to reduce the torque by the amount of restriction according to the idling state, or to return the reduced torque appropriately to the original state or the vicinity of the original state. In addition, it is conceivable that the engine slips again in the process of returning the torque to the original state. Therefore, it is also important to return the torque to the original state with a gradient as gentle as possible.

Considering the above, it is considered desirable to have the characteristics shown in FIG. 2 as to how to reduce the torque after idling. If the adjustment amount can be changed according to the idling state while maintaining the relationship of FIG. 2, optimal re-adhesion control according to the situation can be realized.
FIG. 2 shows the current command value characteristics during the re-adhesion control, which can be considered in three regions. The area (a) is an area for quickly returning to the adhesive state at the time when idling occurs. For that purpose, it is necessary to instantaneously narrow the current command value to a level that can ensure the adhesive state.

  In addition, the area (b) is an area for returning to the original state as soon as possible in the re-adhered state, and for this purpose, it is necessary to return the current command value to the original state according to the current state of the motor. . Further, the region (c) is a region in which the current command value is held in a state where the current command value is reduced by a certain amount from the current command value at the time when the slipping occurs so that the slipping does not occur again. In this region, it may be considered that the motor has already returned to the normal state before idling.

Here, FIG. 2 shows the relationship among the rotational frequency of the idling motor, the torque (current) throttle amount, and the torque (current) command value.
When a certain motor rotates, the rotational frequency of the idle motor increases rapidly (region (a) in FIG. 2). By narrowing down the current command value using this deviation amount, an increase in the rotational frequency is suppressed, and further, the normal rotational frequency in the adhesive state is restored (region (b) in FIG. 2). However, if the current command value is returned to the value at the time when idling occurs in this state, the possibility of idling again increases. Therefore, even if the rotational frequency of the idling motor returns to the normal state due to re-adhesion, only the current command value is held in a state where it is reduced by a certain amount without returning to the value at the time of idling. A period is provided (region (c) in FIG. 2).

As described above, the characteristics of the three regions are as follows: the rotational frequency of the idling motor is used as the deviation amount, the property of region (a) is the differential operation, the property of region (b) is the proportional operation, and the property of region (c) is the region It can be understood that a so-called PID controller may be used since each can be realized as an integration operation of the deviation amounts of (a) to (b). At this time, the deviation amount indicating the idling state is based on the rotation frequency of each motor described above, or the time change rate of the rotation frequency is obtained from the rotation frequency of each motor, and is based on the time change rate of the rotation frequency. At least one of those can be used. The area in FIG. 2D will be described later.
From the above, it is assumed here that the characteristics of the amount of restriction of the current command value at the time of re-adhesion control when idling occurs are approximately realized by the PID controller.

FIG. 3 shows a first modification of FIG.
In FIG. 1, the output value of the PID regulator 16 is used as it is as the reduction amount of the current command value, but the output value of the PID regulator 16 a is set as the current command value reduction rate as shown in FIG. The final current command value can also be obtained by subtracting 1 from 1 and multiplying the value by the original current command value by the multiplier 18. Others are the same as the case of FIG.
1 and 3, the current command value is narrowed down, but the frequency command value may be narrowed down instead of the current command value, or both of them may be narrowed down.

FIG. 4 shows a specific example of the rotational speed deviation amount calculation unit shown in FIGS.
The reference frequency calculation unit 121 receives the rotation frequencies fr1 to fr4 calculated by the rotation frequency calculator 4 and calculates the reference frequency. By subtracting the reference frequency and the rotation frequencies fr1 to fr4 by the subtractor 122, a deviation amount based on the rotation speed is calculated. At this time, the power running / braking signal is used, the reference frequency is subtracted from the rotation frequencies fr1 to fr4 at the time of power running, and the rotation frequencies fr1 to fr4 of each motor are subtracted from the reference frequency at the time of braking. The amount of increase / decrease is matched.

FIG. 5 shows a specific example of the time change rate deviation amount calculation unit shown in FIGS.
This is basically the same as FIG. 4 except that the inputs fr1 to fr4 in FIG. 4 are changed to the time change rates Δfr1 / Δt to Δfr4 / Δt of the rotation frequency. In addition, 141 is a calculating part which calculates the time change rate reference value of rotation speed, 142 is a subtractor.

FIG. 6 shows a second modification of FIG.
In FIG. 6, instead of the deviation amount calculation unit 14 of FIG. 1, a time change rate magnitude determination unit 19 of the rotation speed is provided, whereby the rotation speed change rate Δfr1 / Δt to Δfr4 / Δt of each motor and the set value The magnitude relationship with “αSET” is determined. That is, the output of the speed change rate magnitude determination unit 19 of the rotation speed is input to the rotation speed deviation adjustment unit 20, and the time change rates Δfr1 / Δt to Δfr4 / Δt of the rotation speeds of the respective motors are set from the set value “αSET”. Is smaller than the set value “αSET”, the deviation amount calculated by the rotation amount deviation calculation unit 12 is directly used for PID adjustment. The input of the device 16. By doing so, it becomes possible to perform re-adhesion control that restores the rotational speed deviation when the rate of change in the rotational speed with time exceeds a set value.

In FIG. 6, a set value is provided for the rate of change in the rotational speed with time, and the rotational speed deviation amount is used as an input value for the PID adjuster 16. It is also possible to use a numerical time change rate deviation amount as an input value of the PID controller 16.
FIG. 7 shows a third modification of FIG. This is characterized in that a deviation amount adjusting unit 21 is provided between the adder 15 and the PID adjuster 16 with respect to that shown in FIG.

  As shown in FIG. 8, the deviation amount adjusting unit 21 sets a threshold level for the deviation amount added by the adder 15. When the deviation amount is equal to or less than the threshold level, the deviation amount is adjusted. The amount is input to the PID controller 16 as zero, and the deviation amount is directly input to the PID controller 16 when the threshold level is exceeded. In this way, since the re-adhesion control is not performed until a certain deviation amount is reached, it is not necessary to perform the re-adhesion control in an unnecessary state. In addition, a decrease in acceleration / deceleration characteristics due to frequent repeated re-adhesion control can be suppressed as much as possible.

FIG. 9 is a characteristic diagram showing another example of the re-adhesion control characteristic.
That is, the characteristic of FIG. 2 is that after the region (c), the integral term of the PID regulator is returned to zero and returned to the state before idling.
The reason why the current command value is held at a certain reduction amount in the region (c) of FIG. 2 is that, for example, when the rain is raining and the adhesion state between the wheels and the rail is deteriorated, This is because if the current command value is returned to the current command value at the time when idling occurs, the state is not improved and there is a high possibility that idling will occur again.

However, when the adhesion state between the wheel and the rail is partially deteriorated, there is a high possibility that the adhesion state is improved during the re-adhesion control. In such a case, if a constant reduction amount is kept forever, the acceleration / deceleration characteristics will be reduced unnecessarily.
Therefore, as shown in the characteristic diagram of FIG. 9, the acceleration / deceleration is performed by returning the current command value to the state before the idling occurs (region of FIG. 2D) after the region (c) has passed for a certain time. Try to suppress deterioration of characteristics.

FIG. 10 shows a fourth modification of FIG.
The configuration of FIG. 1 is characterized in that a low-pass filter 22 is inserted between the PID adjuster 16 and the subtractor 11. With this low-pass filter 22, the steep change rate due to the differential operation of the PID adjuster 16 can be adjusted according to the apparatus. As a result, sudden fluctuations during re-adhesion control can be suppressed, and deterioration in ride comfort can be suppressed.

The block diagram which shows 1st Embodiment of this invention Principle explanatory diagram of the present invention The block diagram which shows the 1st modification of FIG. The block diagram which shows the specific example of the rotation speed deviation amount calculating part shown in FIG. The block diagram which shows the specific example of the time change rate deviation amount calculating part of the rotation speed shown in FIG. The block diagram which shows the 2nd modification of FIG. The block diagram which shows the 3rd modification of FIG. FIG. 7 is a characteristic diagram showing a characteristic example of the deviation amount adjusting unit used in FIG. Characteristic chart showing another example of re-adhesion control characteristics The block diagram which shows the 4th modification of FIG. Configuration diagram showing a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power converter device, 2 ... Induction motor (motor), 3 ... Pulse generator (PG), 4 ... Revolution (frequency) calculator, 7 ... Reference frequency selector, 8, 11, 17, 122, 142 ... Subtraction 9 ... function generator, 10 ... change rate calculator, 12 ... rotational speed deviation calculation unit, 13 ... time change rate calculator, 14 ... rotational speed change rate deviation amount calculation unit, 15 ... adder, DESCRIPTION OF SYMBOLS 16, 16a ... PID adjuster, 18 ... Multiplier, 19 ... Size discriminating part, 20 ... Rotational speed deviation amount adjustment part, 21 ... Deviation amount adjustment part, 22 ... Low pass filter, 121 ... Reference frequency calculating part, 141 ... Rotation Number time change rate reference value calculator.

Claims (4)

In a re-adhesion control device for an electric vehicle using a means for detecting or estimating the rotational frequency of a motor and a power converter,
A PID controller is provided that has a deviation value calculated from at least one of the detected value (estimated value) of the motor rotation frequency and the time change rate of the detected value (estimated value) of the motor rotation frequency as its input value. A re-adhesion control device for an electric vehicle, wherein a value is used to narrow down at least one of a frequency command and a torque command for the motor.   A threshold value is set for an input value of the PID regulator, and when the input value of the PID regulator is smaller than the threshold value, the input value of the PID regulator is set to zero. Item 2. The re-adhesion control device for an electric vehicle according to Item 1.   3. The electric vehicle re-adhesion control device according to claim 2, wherein when the input value of the PID controller is zero, the output value (integral term) of the PID controller is reduced to zero after a predetermined time. . The re-adhesion control device for an electric vehicle according to any one of claims 1 to 3, wherein a low-pass filter is inserted into an output unit of the PID adjuster.

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