DE2640259C3 - Speed control arrangement for an electromotive vehicle drive - Google Patents

Description

15th

20th

The invention relates to a speed control arrangement fo ^r an electric motor vehicle drive, using a proportional controller as a speed regulator, the output of the current or tension and / or braking force setpoint provides a lower-level control loop. Such a speed control arrangement is known from the journal "Deutsche Eisenbahntechnik", 19 (1971), pp. 433-437

Modern speed controls for locomotives should not have any major deviations from Allow predetermined target speeds, than about ± 1 to 2 km / h. On the one hand, that requires a large one Control gain, on the other hand, this is contrary to the stability of the control loop. Integral controller ("/ controller) or proportional-integral controller (P'A controller) are due to Due to their large overshoot behavior in the event of disturbances, it is difficult to use from the outset. Proportional controller (P controller), on the other hand, easily lead to instabilities, in particular, with the large gains required if the controlled system, as in the present case, has elements with greater time behavior (time constants) having. The main disturbance variable in vehicle speed control is the tractive force or the motor current required for this. These quantities can be used to maintain a required speed be different depending on the weight of the train and the terrain. The pulling force can be for the same speed of Vary zero to positive values (slope) or negative values (slope).

The object of the invention is to use a P controller relatively simple way to achieve high control accuracy without instabilities or overshoots.

This object is achieved for a speed control of the type mentioned in that when using a proportional controller with a relatively small gain, a higher one The accuracy of the regulation is achieved by adding a correction variable to the speed setpoint is superimposed on the difference between a size proportional to the pulling or braking force and one of the measured acceleration or deceleration proportional size is so proportional that the remaining Control deviation of the speed controller

is at least approximately balanced

In connection with a P-controller it is known per se (»Introduction to the technology of automatic control«, Göschen, Vol. 714 / 714a, 195o, pp. 79/80), controlled systems to be improved in terms of control technology through feedforward control. This happens with the acquaintance in that the setpoint is influenced as a function of the disturbance variable and the actual value with the sum the disturbance variable and the setpoint is compared. The P-deviation is reduced by the contribution that the would otherwise cause the added disturbance variable. The invention is used to avoid instabilities Accepted lower P gain through correction or falsification of the setpoint by means of the Disturbance itself balanced again. The introduction of acceleration or deceleration is It is important to avoid during an acceleration phase (or deceleration phase) up to the approach (Run-in) at a target speed to reduce the influence of the tensile force correction variable. Only after the correction variable intervenes increasingly. This prevents overshooting. In the case of steady travel, the acceleration is = 0 and therefore has no influence on the correction variable traction or braking force

A circuit example of the invention will be explained hereinafter in more detail The figure shows in a circuit segment a speed control arrangement for the formation of a current setpoint _so l \ i a subordinate motor current control loop. Of the 3 operational amplifiers shown, the operational amplifier 1 is the actual proportional controller for the speed control and the two amplifiers 2 and 3 are used to generate and apply the correction variables to the input of the speed controller. A gain of V = IO is assumed for the proportional controller. Via a connection 4 and a series resistor 5 the input of the speed setpoint value v _S oih takes place via the connection 6 the input of the _{actual speed value Vj 51} . The difference between the signed v ₅₀ n and v, _s , values occurring at the node 7 is fed to the input (-) of the proportional controller 1. The v / sr value is differentiated by means of a PC element 8, 9 and the amplifier 2 and fed to the amplifier 3 as an acceleration variable a via line 10 and resistor 11. The current actual value signal (motor current) / _{; si} is applied to connection 12 via resistor 13 as a proportional substitute for the tensile force. At node 14, the addition of values with different signs is used to subtract the acceleration a as an electrical variable from the current actual value signal /, «. The difference value controls the amplifier 3, the output of which has an additive effect on the control input (-) of the proportional controller 1 via line 15 and a resistor 16. The required ratio of the resistance values of the resistors 5 and 16 depends on the degree of amplification of the proportional amplifier 1 in order to arrive at the required speed values according to the invention. According to the chosen example of a gain v = 10, a resistance ratio of 1:10 must be selected here in order to get to 100% Vü _{with v IO; / corrected to 110%.} The resistor 16 thus has ten times the value of the resistor 5. The / «, // value at the output of proportional amplifier 1 is increased accordingly. A connection for actual braking force values Mb _{is also} designated by 17. Instead of connection 12, it receives signals when braking (downhill) if there is

it is important to keep a speed. A feed resistor for the _var values is also designated by 18

In function, the setpoint value of the speed vw / would be present at connection 4 and drive the amplifier I fully up to saturation. The v «, value grows slowly and is initially without any influence, since AV, ie K ₅₀ ;; - V«, continues to drive the amplifier fully. The additive correction variable via line 15 has little or no effect at the highest acceleration. The additive correction value increases until it reaches the full value at acceleration a = 0. Then the vehicle is also open the target speed has run in. The steady-state run is reached with a = 0, and the I correction value has its full size. It corresponds to the tractive force required for the steady drive. When driving uphill, is the subtracting? Acceleration value a become smaller, so that the correction value becomes larger. When traveling downhill, Z ₅₀ Zi becomes negative, which means a braking setpoint Mb _x Ii / &, (connection 12) is in this case 0. The correction is now derived from the braking torque Mb ^, (connection 17).

With the invention, the remaining control deviation of a proportional controller is in a simple manner balanced, and a higher accuracy speed control can be established.

1 sheet of drawings

Claims (1)

Claim: Speed control arrangement for an electromotive vehicle drive using a proportional controller as a speed controller, the output of which supplies the current or tension and / or braking force setpoint specification of its subordinate control circuit, characterized in that using a proportional controller (1) with a relatively small gain a higher accuracy of the Control is achieved in that the speed setpoint (vsoii) is superimposed with a correction variable which is proportional to the difference between a variable proportional to the pulling or braking force and a variable proportional to the measured acceleration or deceleration (a) so that the remaining control deviation is proportional of the cruise control is at least approximately balanced 10