JPH0216081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant speed control method for an electric vehicle, and particularly to a constant speed control method for constant speed operation in a field controlled electric vehicle.

Currently, in the constant speed control method for field-controlled electric vehicles, in order to quickly bring the actual speed (V) of the electric vehicle to a preset target speed (Vp), the actual field current is weakened, and then A field weakening pattern that can increase the actual speed to a higher speed range is output, and when the actual speed is increased by this field weakening pattern and the actual speed exceeds the target speed, the state shown in Figure 1 is generated. A constant speed control limiter with special characteristics intensifies the field current by an amount proportional to V-Vp to lower acceleration performance and suppress speed increase above the target speed.

In addition, the timing at which the above field weakening pattern is output is determined, for example, by (1) a constant speed operation command being issued from the driver's cab (set as P ₁ ), (2) an appropriate speed range for the target speed. ( ₃ ) The main circuit is at the end of the series or parallel stage and the power running resistance is completely shorted (P ₃ ), etc. This is when all the logic of the input conditions promised in advance are established.

In this method, the difference between the actual speed and the target speed eventually becomes zero, and constant speed performance that follows load torque fluctuations can be obtained, but it has the following drawbacks during transients.

In other words, when the camshaft reaches the final stage in parallel or series and the field weakening pattern is output at the timing when all the necessary conditions ((1), (2), (3)...) etc. are satisfied, the shunt field is Since the magnetic flux suddenly weakens, a large current flows from the overhead wire compared to the constant current that had been advancing to the current limit value, which may cause temporary torque fluctuations. This armature current overshoot is caused by the field current being controlled at a large value when the load is large and the current limit value is high. The variation range of the magnetic current is also large, which has an even worse effect.

The present invention has been made in view of this point.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 is a block diagram showing an example of a device for implementing the constant speed control method according to the present invention, and FIG. 3 shows the actual armature current controlled by the device shown in FIG. FIG. 3 is a diagram showing magnetic current and actual speed.

In FIG. 2, 11 is an AND circuit,
As described above, an output is generated when all the logics of predetermined input conditions such as P ₁ , P ₂ , and P ₃ are satisfied. 12 is a field weakening pattern generator,
Connected to the output side of the AND circuit 11, and the real field current
A field weakening pattern is generated that can weaken I _f and increase the actual speed V to a speed range higher than the target speed V _p . 4A is a constant current limiter,
It is connected to the output side of the AND circuit 11, and when the actual armature current I _a exceeds the armature current pattern I _p , the difference (I _a −
I _p ), thereby making the actual armature current I _a equal to the armature current pattern I _p . Similarly, 13 is a constant speed control limiter composed of, for example, one operational amplifier, and is connected to the output side of the AND circuit 11, and when the actual speed V exceeds the target speed V _p , the difference (V −V _p ), thereby making the actual speed V equal to the target speed V _p . 14
is a comparison calculator, which is connected to the output sides of the field weakening pattern generator 12, constant current limiter 4A, constant speed control limiter, and actual field current detector (not shown), and compares and calculates each output. Performs control described later. 15 is a phase shifter that converts the output of the comparator 14 into a pulse width, and FC is a field current control device that controls the actual field current _If based on the output of the phase shifter 14.

In the constant speed control method of the present invention, the AND circuit 11 generates an output when all the logics of the above-mentioned input conditions are satisfied. In response to this output, at time _t1 , the field weakening pattern generator 12, the constant current limiter 4A
and constant speed control limiter 13 are operated simultaneously. As a result, first the field weakening pattern generator 1
2 supplies an output with a polarity representing a field weakening pattern to a comparator 14, which compares the output with the above-mentioned polarity and the real field current _{I f} from a real field current detector (not shown). The field current control device (FC) weakens the actual field current I _f by comparing and calculating the polarity output representing the field current I f . When the actual field current I _f is weakened in this way, the internal induced voltage of the compound motor decreases, and the actual armature current I _a increases. When the actual armature current I _a exceeds the armature current pattern I _p , the constant current limiter 4A supplies the polarity output to the comparator 14, where it is added to the field weakening pattern described above and the actual field The current I _f is strengthened, the internal induced voltage of the compound motor increases, and the actual armature current I _a
increase is suppressed. That is, the constant current limiter 4A controls the actual armature current I _a to be equal to the armature current pattern I _p . The field-controlled electric vehicle is accelerated toward the target speed V _p while performing such constant armature current control.
This state is shown in FIG. 3 from time t ₁ to time t ₂ .

When the actual speed V increases and exceeds the target speed V _p at time t ₂ , the constant speed control limiter 13 supplies a polar output to the comparator 14 , and as in the case of the constant current limiter 4A, this polar The output is the comparator 14
is added to the field weakening pattern in the field, resulting in a decrease in the actual armature current _Ia . That is, when the actual speed V exceeds the target speed V _p , the actual armature current I _a is reduced to reduce the drive torque. In other words, control is performed to generate the amount of drive torque necessary to travel at a constant target speed _Vp . This state is the third
In the figure, it is shown after time _t2 .

As described in detail above, the present invention allows the actual speed to rise smoothly to the target speed after the power running resistance is short-circuited, without causing unnecessary torque fluctuations, by switching the control before and after the target speed is achieved. The effect is that stable constant speed control can be performed even in the range.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the output characteristics of a constant speed control limiter, Fig. 2 is a block diagram showing an example of a device for carrying out the present invention, and Fig. 3 explains the operation of the device shown in Fig. 2. This is a diagram for In the figure, 12 is a field weakening pattern generator, 4A is a constant current limiter, 13 is a constant speed control limiter, 6 is a phase shifter, and F-CH is a field chopper.

Claims (1)

[Claims] 1 The resistors connected in series to the armature of a compound motor are short-circuited one after another as the speed increases, and the shunt field current is controlled by a field current control device to obtain a predetermined power running performance. When a command is issued to the field-controlled electric vehicle to operate the field-controlled electric vehicle at a constant speed at a predetermined target speed, the field-controlled electric vehicle is operated in a speed range higher than the target speed until the actual speed of the field-controlled electric vehicle reaches the target speed. A field weakening pattern generator outputs a field weakening pattern that can increase the actual speed, and by strengthening the actual field current, the induced voltage of the compound motor increases, suppressing the increase in the actual armature current, and increasing the actual armature current. The field control electric vehicle is controlled by a constant current limiter that prevents the actual armature current from exceeding a certain value, and when the actual speed reaches the target speed and attempts to exceed it, the actual speed and the target A constant speed control method for an electric vehicle, characterized in that the field control electric vehicle is controlled by a constant speed control limiter that increases the actual field current according to a difference in speed.