JPS6019201B2 - Electric vehicle brake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control braking device for an electric vehicle, and is particularly applicable to a DC electric vehicle that uses a chopper to control a motor.

Conventionally, restraint braking in DC electric vehicles has been employed in resistance-controlled vehicles with dynamic braking, such as cam type, as shown in Fig. 1.

In other words, when the load resistance of the dynamic braking circuit is kept constant, the relationship between the electric car speed and the motor fin flow is expressed by the notch curve K,...
It can be expressed by a characteristic curve such as K2, & in which the speed increases as the motor current increases. However, when the speed of an electric car becomes higher than the equilibrium speed V, , V2, V3 at the intersection of each notch curve K, , K2, K3 and the gradient characteristic curve Do, the motor current increases and the braking torque increases. As V increases, the speed of the electric car automatically decreases, and conversely, when the speed of the electric car becomes lower than the restraining equilibrium speed V,, V2, V3, the motor current decreases and the braking torque decreases. As a result, the speed of the electric car automatically increases, and the electric car ends up running at the restrained equilibrium speed V, , V2, V3. On the other hand, recently, even in chopper-controlled vehicles that have many features such as energy saving, regenerative braking is used to perform restraint braking.

However, in the case of this chopper-controlled vehicle, a constant resistance curve as shown in FIG. 1 does not exist. Therefore, by actually detecting the speed of the vehicle using a speed detector and generating a motor current corresponding to this detected speed using a function generating circuit, control equivalent to the /ch curve K, , &, K3 in Fig. 1 can be performed. It is made possible. However, in the case of this chopper control vehicle, the speed detection signal of the vehicle is usually obtained as a detection signal corresponding to the rotational speed of the wheels by measuring the rotational speed of the wheels.

Therefore, for example, if the wheel width of an electric car increases, the number of rotations will actually decrease even at the same speed, and the arriving speed detection signal will become smaller accordingly. Therefore, before changing the wheel diameter, for example, The restraint braking control that has been performed as a reference is now performed using K and a shifted from the reference notch curves K and after a slight wheel change. On the other hand, the influence of this wheel diameter change also appears on the gradient characteristic curve Do, and after the change, the gradient characteristic curve D is shifted.

This is because as the wheel diameter increases, even if the same motor current is passed and the motor torque is the same, the braking force of the vehicle generated on the tread between the wheel and the rail becomes smaller, so when the speed is balanced even under the same slope condition. This is because the motor current increases. From the above, in the case of a chopper-controlled vehicle, when the wheel diameter of the electric vehicle increases, the speed equilibrium point changes from the intersection point V of the reference curve K before the change and Do to the curve K after the change. a
and D, to the intersection point V,2.

On the other hand, in the case of a resistance-controlled vehicle, the notch curve K does not change as described above even if the wheel diameter is changed, so the speed equilibrium point is the intersection point V and R of the curves K and D.

Therefore, in the past, in order to make the chopper control vehicle match the resistance control vehicle, a notch curve K suitable for the actual speed was used by giving a correction signal for the wheel diameter to the speed detection unit. was. However, even with such measures, the influence of the movement of the gradient characteristic curve still remains, and the velocity equilibrium point V, has shifted to V, R.

Ru. Therefore, in the past, when driving with restraint, care was taken to subtract this change from the safe speed limit on the slope. Therefore, especially when the wheel diameter is made small, the equilibrium speed becomes considerably low, which causes a reduction in operating efficiency. The present invention takes the above points into consideration and attempts to eliminate the drawbacks of the conventional chopper control vehicle.The present invention provides a correction signal corresponding to the wheel diameter to a function generating circuit that generates a motor current command value based on a detected speed signal. The notch curves K, , K2, K3 are set so that the damping equilibrium speed becomes the same as before changing the wheel diameter.
It is designed to shift the .

An example of the present invention will be described below in detail based on FIG. given to vessel 3.

The variation coefficient signal A of the wheel diameter variation coefficient circuit 4 is inputted to the multiplier 3 as a multiplication number, and the resultant calculation output AV obtained in the multiplier 3 is given to the function generation circuit 5. Here, the coefficient of variation signal A has a value of the ratio of the measured wheel diameter to the reference wheel diameter, so that the multiplication output AV input to the function generating circuit 5 always means a speed signal corresponding to the actual speed.

In this way, the motor current command value 1 corresponding to the actual speed can be obtained at the output terminal of the function generating circuit 5.

In addition to this, a positive constant is applied to the coefficient output A of the wheel rotation variation circuit 4 in the multiplication circuit 6 to control the suppression equilibrium speed after changing the wheel diameter to the same suppression change speed as in the case of the reference wheel diameter. By adding up B, the chicken calculation output AB is obtained as a positive coefficient signal.

This correction coefficient signal AB is multiplied by the current command value signal 1 of the function generation circuit 5 in the multiplication circuit 7, and the multiplication result A
BI is sent as a motor current command value.

In order to obtain the fin flow command value corresponding to the speed of the electric vehicle based on the output of the function generating circuit 5 in the configuration shown in FIG. 2, the correction of FIG. As shown in the notch curve K,b, the intersection point V. with the slope characteristic curve D after the wheel diameter is changed. The speed value indicated by No. 3 can be made the same value as the speed value at the intersection point V between the slope characteristic curve Do before the change and the reference notch curve K.

In this way, even after a slight change in the wheel, the control can be performed to the same equilibrium speed as in the case of the standard wheel diameter. Incidentally, the reason why the damping equilibrium speed can be corrected simply by multiplying the coefficients A and B as described above is because, firstly, if the electric vehicle has the same speed, the rotation speed is inversely proportional to the wheel diameter. 2, when the motor current is the same, the braking force of the vehicle is inversely proportional to the wheel diameter;
This is because the braking force of the electric motor and the crab flow can be considered to have a linear function relationship in a limited range such as damping control.
Therefore, the speed signal can be multiplied by the wheel ridge variation coefficient A to correct the /ch curve after changing the wheel diameter.In addition, the restraint equilibrium speed after changing the wheel diameter can be calculated using the correction constant B to correct the /ch curve after changing the wheel diameter. The speed change speed can be controlled to the same speed as in the case of , and the speed change speed can always be kept at a constant value even if the wheel diameter varies.

As described above, according to the present invention, by using a function generating circuit with a simple configuration, it is possible to always maintain the deformation equilibrium speed at a constant value even if the wheel diameter varies.

[Brief explanation of the drawing]

Figure 1 is a characteristic curve diagram for explaining the principle of the present invention, Figure 2 is a characteristic curve diagram used to explain the principle of the present invention.
The figure is a block diagram showing an example of a speed control braking device for a fin-driven car according to the present invention. 1: Number of circuits - voltage conversion circuit, 2: Speed generator, 3, 6,
7: Liker, 4: Wheel diameter variation coefficient, 5: Generation circuit. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a speed control braking device for an electric vehicle, which obtains a speed detection signal corresponding to the rotation speed of a wheel and generates a motor current command value for a chopper control device in a function generating circuit based on this speed detection signal, the above-mentioned The notch curve after changing the wheel diameter is corrected by multiplying the speed detection signal by the wheel diameter variation coefficient A and inputting the result to the relation generation circuit, and the output of the function generation circuit is multiplied by the correction coefficient B. A restraint braking device for an electric vehicle, characterized in that the restraint equilibrium speed is made to be the same value as before the change.