JPS5939962B2 - electric vehicle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a separately excited motor as a drive motor, sets the armature current of the drive motor according to the amount of depression of the accelerator pedal, and matches the armature feedback value with this set value. The results relate to improvements in electric vehicle control devices that perform speed control using closed-loop field system control.

Figure 1 shows a typical main circuit of an electric vehicle using a conventional field chopper type separately excited motor of this type, in which 1 is a DC power supply, 2 is a field current detection resistor, and 3 is a drive motor and other circuits. Excitation field winding, 4 is a flywheel diode, 5 is a transistor chopper, 6 is a resistor for armature current detection, 7, 10
, 11 is a magnetic contactor, 8 and 9 are armature current limiting resistors (
(hereinafter simply a limiting resistor), 12 is a regeneration diode, 13
is the armature of the drive motor.

In this circuit, speed is controlled by varying the armature circuit resistance by sequentially shorting or inserting limiting resistors 8 and 9 connected by electromagnetic contactors T, 1O, and 11.

That is, the armature circuit is changed to 1-6-7-8-9-13-1, 1-6-7-1 by shorting or inserting the limiting resistors 8 and 9.
0-9-13-1, 1-6-7-10-11-13-1
Three modes are formed. In these three modes, the field current is controlled by the field chopper 5,
To control the speed of an electric motor in a straight line and run the vehicle without shock. Note that whether the electromagnetic contactors 7, 10, and 11 are turned on or off is determined by the amount of accelerator depression and the motor rotation speed.
Further, braking is performed by the circuit 13-12-6-1-13 by strengthening the field of the electric motor and regenerating it as a generator. In the above-mentioned field control, in order to widen the field control range and add a torque control effect, the maximum and minimum field variable ranges of the field current are predetermined by a limiter circuit, and within these variable ranges, during power running. Compare the amount of depression with the armature current as the set value of the armature current, and if the armature current is smaller than the set value, the field current will be decreased, and conversely, if the armature current is large, the field current will be increased. Closed-loop control is used to ensure that

In addition, when braking, compare the braking current setting value and armature current,
The field current is controlled in a closed loop so that when the armature current is large compared to the set value, the field current is decreased, and when the armature current is small, the field current is increased. In this control, the maximum limiter value that determines the field current variable range is determined from the maximum current rating of the field chopper 5 and the allowable temperature of the field winding 3, and the minimum limiter value is determined from the maximum current rating of the field chopper 5 and the allowable temperature of the field winding 3. It is determined from the point of Electric vehicles using such field chopper type separately excited motors have problems when starting and when running at low speeds.

That is, in this case, only the armature current determined by the limiting resistors 8 and 9 flows through the motor, so if the accelerator is fully depressed and the armature current setting increases, the above-mentioned field control operation will change. The field current weakens to the minimum value applied to the lower limiter, the torque decreases, and the acceleration becomes smaller. This is a phenomenon in which the comparative torque decreases and the acceleration decreases when the accelerator pedal is depressed more than when the accelerator pedal is depressed less, which is contradictory to the driving sensation of current ordinary gasoline-powered cars. In view of this point, the present invention solves the above contradiction by varying the variable range of the field current depending on the rotation speed of the electric motor, and provides an electric vehicle control device that provides a driving sensation equivalent to that of a gasoline vehicle. The purpose is to provide.

An embodiment of the present invention will be described below with reference to the closed loop field control system shown in FIG. 2 and the field variable range characteristics shown in FIG.

In FIG. 2, reference numeral 14 denotes an accelerator pedal depression amount detector that outputs a signal corresponding to the amount of depression of the accelerator pedal, and is used to set the armature current. 6 is a resistor for detecting the armature current of the motor shown in FIG. 1, 15 is a subtracter for subtracting this armature current from the set value, and the result of the subtraction is set by a Schmitt circuit 16 having a hysteresis width. If the armature current is larger than the value, it turns off, and if it is smaller, it turns into an on/off wave.

The hysteresis width of this Schmitt circuit 16 becomes the ripple value of the armature current. The output of the Schmitt circuit 16 is logically summed with the output of the field current lower limit value limiter circuit 18 which uses a NOR circuit 17 to set the lower limit of the field control range, and the output of this NOR circuit 17 is used to set the upper limit of the field control range using the NOR circuit 19. A logical OR is performed with the magnetic current upper limit value limiter circuit 20. The output of the NOR circuit 19 causes the field chopper 5 shown in FIG. The current flowing through the field winding 3 is detected by the resistor 2 shown in FIG. 1 and is input to the field current lower limit value limiter circuit 18. The limiter circuit 18 is a Schmitt circuit with a hismolysis width, which converts the field current into an on-off wave that is on (L level) when it is larger than the Schmitt level and off (H level) when it is smaller than the Schmitt level, and sets the lower limit value of the field current. Performs limiter control.

The purpose of the hysteresis width is to limit the maximum frequency of the field chopper 5 during limiter operation. Further, the field current detected by the resistor 2 is input to the field upper limit value limiter circuit 20.

This limiter circuit 20 is a Schmitt circuit with a hysteresis width, and when the field current is larger than the Schmitt level, it is turned off (H level), and when it is smaller than the Schmitt level, it is turned on (L level). Performs limiter control. The purpose of the hysteresis width is to limit the maximum frequency of the field chopper 5 during limiter operation. In this circuit, the lower limit value of the limiter circuit 18 is advanced by the NOR circuit 17 and the upper limit value of the limiter circuit 20 is advanced by the NOR circuit 19 than in the steady state control. A soft start circuit 21 generates a first-order delayed waveform of about 4 to 5 seconds when the accelerator pedal is depressed and the accelerator pedal switch 22 is turned on, thereby controlling the limit level of the earth limit value limiter circuit 20 in a pattern. This soft start circuit 21 is operated only in a region where the rotational speed of the electric motor is low. This is the soft start circuit 2 when the rotation speed is high.
This is to eliminate the phenomenon in which the torque increases due to 1 and causes a torque shock. Here, in the present invention, a rotation speed detector 23 is provided to detect the rotation speed of the electric motor, and the output of this rotation speed detector 23 is inputted to the field current lower limit value limiter circuit 18 through the F-converter 24. As shown in Figure 3 (curve a is the upper limit set value), in the low speed region where the limiting resistors 8 and 9 are inserted, the field current lower limit is set so that the lower the speed is, the higher the lower limit value b is. Value limiter circuit 1
Next, the operation of the above-mentioned component device will be explained.

Adder 15 calculates armature current setting value 14 and snoring current feedback value 6.
The deviation is used to operate the field chopper 5 through the Schmitt circuit 16 and the NOR circuits 17 and 19 to excite the field winding 3. In this case, if the armature current is smaller than the set value, the output of the adder 15 passes through the Schmitt circuit 16 and the NOR circuits 17 and 19, turns on the field chopper 5, and excites the field winding 3; If it is large, Schmitt circuit 1
6 is no longer output, the field chopper 5 is turned off, and the field winding 3 is not excited. That is, the field stopper 5 is turned on and off according to the difference between the armature current and the set value to control the field current. In this operation, the current in the field winding 3 is detected by the resistor 2, and the detected value is applied to the field current lower limit value limiter circuit 18. When the field current becomes less than the lower limit value, this lower limit value limiter circuit 18 is applied. An output is generated from the NOR circuit 1.
7, 19 to the field chopper 5 and the field winding 3
Excite. Therefore, the field current of the field winding 3 is continuously supplied regardless of whether the armature current is larger or smaller than the set value, and becomes larger than the lower limit value. The field current detection value is also given to a field current upper limit value limiter circuit 20, and when the field current exceeds the upper limit value, an output is generated from this upper limit value limiter circuit 20, and this output is added to the NOR circuit 19. As a result, the NOR circuit 19 is turned off and the input to the field chopper 5 is interrupted. Therefore, no current flows through the field winding 3, and the field current becomes smaller than the upper limit value. In this way, the field current is controlled within the upper and lower limits. In addition to this operation, the rotation speed of the electric motor is detected by the rotation speed detector 23,
The F-converter 24 converts the voltage into a voltage according to the output frequency of the rotation speed detector 23 and inputs it to the lower limit value limiter circuit 18, and the lower limit value is set in the low speed region as shown in curve b in FIG. The control is such that the lower the speed, the higher the speed.
In this way, if the lower limit value of the field current is set to be high in the low speed region, a large acceleration force can be obtained even if the amount of accelerator depression is large because the lower limit value of the field current to be controlled is high. Therefore, it is possible to eliminate the paradox that the accelerating force decreases when the accelerator depression amount is large compared to when the accelerator depression amount is small. Therefore, the driving sensation at low vehicle speeds when the accelerator is depressed can be improved to the same level as that of a gasoline-powered vehicle, and since the acceleration control can proceed smoothly, the time required to insert the limiting resistors 8 and 9 can be shortened, and the electric power This has the advantage of reducing losses.

The present invention can also be applied to a circuit using an armature tipper, and can be applied during braking in the same way as during power running.According to the above-described invention, the driving sensation at low speeds can be compared to that of a gasoline vehicle. An electric vehicle control device that can be equally improved can be provided.

[Brief explanation of the drawing]

Fig. 1 is a main circuit diagram of an electric vehicle using a field chopper type separately excited motor, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 3 is a field variable range characteristic curve diagram in the same embodiment. . 1; DC power supply, 3 and 13; field winding and armature of the motor,
5; Field chopper, 7, 10, 11; Magnetic contactor, 8,
9: Limiting resistor, 14: Detection amount of accelerator pedal depression,
18; Field current lower limit value limiter circuit; 20; Field current upper limit value limiter circuit; 23; Rotation speed detector; 24; F-converter.

Claims (1)

[Claims] 1. Several stages of starting resistors connected in series with the armature circuit, switching elements that short-circuit or interrogate these starting resistors, and closed-loop field current control in which upper and lower control ranges are predetermined. A DC motor with a system is used as the drive motor, and during power running, the field current is controlled by a field current control system so that the accelerator pedal depression amount becomes the set value of the armature current, and during control, the armature current is constant. An electric vehicle control device which controls a field current by a field current control system so that the field current reaches a certain value, wherein the lower limit setting value of the field control range is set high in a low vehicle speed region. 2. The electric vehicle control device according to claim 1, wherein the lower limit setting value of the field control region is varied so as to be higher as the vehicle speed is lower.