Controller with PI behaviour and with a device for improving the starting-up behaviour

摘要

In order to improve the starting-up behaviour of a controller with PI behaviour, in addition a D portion is connected to the I portion of the controller as long as the size of the control deviation multiplied by the amplification factor of the P portion is greater than a predetermined value. The control deviation or the control variable serves as input signal for the D portion. The counteracting control of the D portion which is connected to the I portion during starting up is dependent on the speed of change of the control variable. In this way, in the case of relatively large values, the control variable reaches the set value without unnecessary delay and without overshooting. In addition, a limiting device for the control variable of the controller is provided which, when predeterminable limit values are exceeded, feeds a correction signal to the I portion which returns the control variable to the range limited by the limit values.