JPH0382301A - Drive controller of electric car - Google Patents

Abstract

PURPOSE:To improve the reliability of an apparatus by having a car speed detector and a car speed estimator and by using a car speed for drive control at the time of normal running and an estimated speed in place of the car speed, when abnormality occurs in a car speed signal. CONSTITUTION:The signal of a trailing-wheel speed detector 12 and that of a car speed estimator 14 are inputted to a switching logic circuit 15, a trailing- wheel speed is usually selected and outputted to a current command rate-of- change compensator 13, and the output to the current command rate-of-change compensator 13 is switched to an estimated car speed, when abnormality occurs in a trailing-wheel speed signal. In a switching logic, the trailing-wheel speed is the speed of a car body having a large mass and suffers no sudden change of time, and the deviation of a detection speed is monitored always and abnor mality is judged, when the deviation exceeds a specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a drive control device for an electric vehicle driven by an electric motor.

(Conventional technology) Electric cars use electric motors to apply rotational force (torque) to the wheels.
The adhesive force (frictional force) between the wheels and the rails uses rotational force as propulsion force to propel the vehicle. The adhesive force FAD of one wheel is FAD=μW (1) where μ is the adhesive coefficient and W is the weight (axle load) on the wheel.

When the rotational force FTH exceeds the adhesive force, the excess rotational force ΔFT
Due to H (=FTHFAo), the wheels are accelerated beyond the vehicle body speed and idle on the rails, resulting in a significant decrease in the transmission of propulsive force. This phenomenon occurs during driving and is called "slip." During braking, if the braking force FBR exceeds the adhesion force, the excess braking force ΔFBR (= FBR - FAD) will decelerate the wheels below the vehicle body speed, causing the wheels to It will slide on the rail, and the transmission of braking force will be significantly reduced. This is called "gliding"6
Hereinafter, in the present invention, explanation will be given regarding slipping, but the same applies to sliding, so the explanation will be omitted.

Note that the wheels connected to the electric motor mentioned above are called driving wheels.
The one that is not connected is called the slave shaft.

As mentioned above, slipping occurs when the rotational force exceeds the adhesive force, but the same thing occurs when the adhesive force is lower than the rotational force.

When slipping occurs, the first thing that happens is that the driving force is not transmitted smoothly, but secondary problems also occur, such as separation of the treads of the passive wheels, burnout of the bearings, and fatigue and wear of the rails. Therefore, it is necessary to control the drive so that it does not spin as much as possible. One of the simplest measures for this purpose is to drive and control the electric motors connected to the driving wheels so that each driving wheel does not generate too large a torque. However, this method requires a large number of electric motors or driving wheels to obtain sufficient torque to index the vehicle, which increases costs.Therefore, drive control is performed by generating as much torque as possible without causing the vehicle to spin. It is desirable to do so.

Here, we will show an example of conventional control and point out its problems. FIG. 4 is a control block diagram showing the general configuration of a motor drive device in an electric vehicle that drives an induction motor using a PWM inverter. As shown in the figure, a current control loop is configured and a current command is given to control the torque of the electric motor to control the driving force of the electric vehicle.In the diagram, 1 generates a current pattern (actual current command) based on the current command. current pattern generator, 2
3 is a current controller that outputs a perfect frequency command based on an appropriate control logic using the current pattern and the detected actual motor current, and 3 is an adder that adds the perfect frequency command to the motor rotation frequency to create an inverter frequency command. 4 is a V/F constant controller that performs V/F constant control based on the Suberi frequency command; 5 is a PWM pulse generator that generates PWM pulses based on the voltage command that is the output of the V/F constant controller; The current detected by 6 is a PWM control voltage type inverter, 7 is an induction motor, and 8 is a current detector is fed back to the current control section 2. Reference numeral 9 denotes a speed detector, and the detected speed is sent to an adder 3 which generates an inverter frequency command in this example. 10
is a slipping/skidding detector, and its detection signal is sent to the current pattern generator 1.

When controlling the drive of an electric vehicle using this motor control system, there will be no problem as long as no slipping or skidding occurs.

(Problems to be Solved by the Invention) Here, a case will be described as an example in which control is performed to cause the driving wheels to readhere (readhesion control) after slipping or skidding occurs.

The slip/slip detector lO monitors the acceleration of the electric motor,
If this acceleration exceeds a predetermined value (hereinafter referred to as idling detection acceleration), it is determined that idling is occurring, and if it falls below a separately determined value (hereinafter referred to as readhesion detection acceleration). It is often determined to be re-adhesion.

The biggest drawback of this method is that it uses acceleration, which is a differential signal of velocity. As is well known, differential signals are generally susceptible to noise. For this reason, first of all, erroneous determinations of slippage and readhesion are likely to occur. If a misjudgment occurs, the re-adhesion control will not operate properly and the idling period will become longer.
Furthermore, there arises a problem that even readhesion does not occur.

As a countermeasure against misjudgment, it is often done to provide a certain amount of margin for the slip detection acceleration and readhesion detection acceleration.

For example, set the slip judgment acceleration to about twice the normal running acceleration, and when slipping is detected with this setting, reduce the actual current command at a constant slope, make the re-adhesion acceleration slightly thicker than the normal running acceleration, and use this setting. There is a method of fixing the actual current command for a certain period of time even after readhesion is determined. According to this method, the start of the readhesion control, that is, the start of the operation to throttle the current, is delayed by the margin provided, and even if the readhesion really occurs, re-acceleration cannot be started until the above-mentioned fixed period has passed. There are problems such as a delay in speed recovery.

In addition, there is also a method of preventing erroneous determinations in determining whether the vehicle is idling by determining that the vehicle is idling when the detected acceleration not only exceeds the idling detection acceleration but also exceeds the idling detection acceleration for a certain period of time (for example, 0.5 seconds). This method has the problem that even if true slipping occurs, the current throttling is delayed, so the slipping continues to grow, making readhesion difficult.

Furthermore, since speed is not monitored and the method relies on acceleration, there is a problem in that correct determination cannot always be expected, especially when determining readhesion. Therefore, as mentioned above, even after it is determined that re-adhesion has occurred, a method is used in which the actual current command is fixed at the value at the time when re-adhesion was determined for a certain period of time. There are no selection criteria as to whether or not to do so, and there is no guarantee that it will reattach within this period.

Furthermore, although this conventional example is an example in which an induction motor is driven by a PWM inverter, when determining the inverter frequency,
An adder 3 adds a frequency command to the motor rotation frequency. Using the motor rotation frequency in this way, in this example, one inverter drives one electric motor, so if, for example, idling occurs, the motor rotation frequency will rise rapidly, and the inverter frequency will also change accordingly. This has the disadvantage that it can rapidly rise and lead to out-of-control situations.

Even when one inverter drives a plurality of electric motors, if all the shafts idle, the motors will run out of control as in the above case.

One way to solve these problems is to use vehicle speed for control. During normal driving, the vehicle speed and driving wheel speed match. (Strictly speaking, they match after converting one of them into the other, but this will be omitted hereafter for the sake of brevity.

) When slipping or skidding occurs, a deviation occurs between the driving wheel speed and the vehicle body speed. If this deviation is monitored, slipping or skidding can be detected in terms of speed rather than acceleration, which eliminates the drawbacks of using acceleration signals as pointed out earlier. Further, if the vehicle speed is used to determine the inverter frequency, the above-mentioned runaway will not occur.

The vehicle speed can be obtained by attaching a speed detector to a wheel to which the electric motor is not connected, that is, a follower wheel, and detecting the rotational speed of the wheel. In this case, in locomotives and trains (vehicles that carry passengers), vehicles equipped with an electric motor usually do not have a slave shaft, so the vehicle body speed, that is, the slave shaft speed, is transmitted from other vehicles that are not equipped with an electric motor. It turns out. In this case, the transmission path becomes long and requires passing through a coupler.

Therefore, it is necessary to take into consideration the occurrence of abnormalities such as disconnection of the transmission line. When this abnormality occurs, it naturally has a serious effect on control and poses a problem in terms of reliability.

The present invention eliminates the above-mentioned problems in the prior art,
The purpose is to provide a highly reliable electric vehicle control device.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is a drive control device for an electric vehicle that controls the drive of an electric vehicle with the following configuration.

In the drive control of an electric vehicle, a vehicle speed detector that detects the vehicle speed and a vehicle speed estimator that estimates the vehicle speed are provided, and during normal running, the vehicle speed is used for drive control of the electric vehicle, and the vehicle speed is When an abnormality occurs in the signal, the estimated vehicle speed determined by the vehicle speed estimator is used instead of the vehicle speed.

(Function) In the above drive control device for an electric vehicle according to the present invention, the vehicle speed is normally used to control the drive of the electric vehicle, and when an abnormality occurs in the vehicle speed signal, the estimated value of the vehicle speed is used. With this configuration, it is possible to improve the reliability of control that prevents malfunctions and control delays due to detection of slipping and readhesion, or runaway of the inverter frequency and motor speed, which is the problem that the invention aims to solve. It is possible to eliminate the drawbacks of the conventional technology pointed out in section.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a drive control device for an electric vehicle according to a first embodiment of the present invention. In this figure, the same components as in FIG. 4 are given the same symbols and their explanations will be omitted.

In this embodiment, the slave shaft speed is used as the vehicle speed.

In FIG. 1, 11 is a slave shaft, and 12 is a slave shaft speed detector. The slave shaft speed detected by the slave shaft speed detector 12 and the motor speed detected by the speed detector 9 are converted into driving wheel speed by a coefficient unit 94, taking into account gear ratio, driving wheel radius, etc., and the current command change rate is corrected. Feed back to container 13. 14 is a block for estimating vehicle speed.

The method of constructing this block is not related to the present invention and will not be described in detail, but examples include an observer for estimating the vehicle speed, a simulator for simulating the motion of the vehicle, and a method for detecting and integrating the acceleration of the vehicle.

Reference numeral 15 denotes a switching logic circuit, which receives the slave shaft speed and the estimated vehicle body speed in this embodiment, monitors the slave shaft speed, normally selects the slave shaft speed, outputs it to the current command change rate corrector 13, and outputs the slave shaft speed to the current command change rate corrector 13. When it is detected that an abnormality has occurred in the speed signal, the output to the current command change rate corrector 13 is switched to the estimated vehicle speed.

The current command change rate corrector 13 calculates the deviation between the output signal of the switching logic circuit and the driving wheel speed, performs proportional processing and, if necessary, integral processing to generate a current command change rate correction signal. This current command change rate correction signal is fed back to the current pattern generator 1 to calculate the command value to the current controller 2. In this way, when slipping or skidding occurs, the deviation is no longer O, and the current command is reduced to measure readhesion.

In the switching logic, abnormalities in the speed of the slave shaft are monitored as follows, for example.Since the speed of the slave shaft is the speed of a vehicle body with a large mass, it is impossible for it to change suddenly over an hour. Therefore, the differential value of the slave axis speed, or the deviation between the detected speed before the current point and the current detected speed, which is equivalent when executed by a microcomputer, is constantly monitored, and the value is set at a certain specified value (threshold value). ) is determined to be abnormal.

Furthermore, the slave shaft speed itself cannot take a negative value when the traveling direction is positive, and it cannot exceed a maximum speed many times higher than the maximum speed determined by the design specifications of the electric vehicle. That is, for the slave shaft speed itself, similarly to the differential value, it is possible to set a prescribed value that can be determined to be abnormal if the value exceeds a predetermined range. Therefore, the speed is constantly monitored, and when the value exceeds the specified value (threshold value) mentioned above, it is determined that there is an abnormality.

The above two methods may be used together.

FIG. 2 is a block diagram of a drive control device for an electric vehicle according to a second embodiment of the present invention. In this figure, the same components as in FIG. 1 are given the same symbols and their explanations will be omitted.

In this embodiment, the output signal of the switching circuit is sent to the coefficient unit 111.
Convert to motor speed by considering gear ratio, driving wheel radius, etc.
It is used as a signal returned to the adder 3 which is the source of the inverter command frequency. With this configuration, even when the driving wheels idle, the inverter frequency does not increase with the driving wheel speed.

Furthermore, as in the first embodiment, the switching circuit 15 monitors signal abnormalities, so reliability can be improved.

FIG. 3 is a block diagram of a drive control device for an electric vehicle according to a third embodiment of the present invention. In this figure, the same components as in FIGS. 1 and 2 are given the same symbols, and their explanations will be omitted.

This embodiment is a combination of the first and second embodiments, and sends the output of the switching logic to the current command change rate corrector 13 and coefficient unit 111. In this case as well, there is an effect of improving reliability as in the previous two examples.

〔Effect of the invention〕

As explained above, according to the present invention, redundancy is provided to the drive control device by using the vehicle speed during normal driving and the estimated vehicle speed when an abnormality occurs in the signal, thereby improving reliability. It is possible to provide high-quality electric vehicle drive control equipment.

[Brief explanation of drawings]

The second construction drawing is a block diagram showing the configuration of the first embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the second embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of the second embodiment of the present invention. FIG. 4 is a block diagram showing the structure of a conventional example. 1... Current command pattern generator 2... Current controller 3... Adder 4... V/F constant controller 5... PWM pulse generator 6... PWM control control voltage fin bar

Claims (1)

[Claims] In the drive control of the electric vehicle, the electric vehicle has a vehicle speed detector that detects the vehicle speed and a vehicle speed estimator that estimates the vehicle speed, and during normal running, the vehicle speed is used to control the drive of the electric vehicle. used for
A drive control device for an electric vehicle, characterized in that when an abnormality occurs in the vehicle speed signal, an estimated vehicle speed determined by the vehicle speed estimator is used instead of the vehicle speed.