Control system for current supplied to actuator for e.g. valve in vehicle, by comparing actual and desired current passing through switch between current source and inductor

摘要

A switch (4) is connected between the current source (5) and inductor (1) and can be turned on and off at a high frequency. A control device (3) is used to regulate the switch on and off times on the basis of an inputted ideal current value (Iset) so that the pulse width for the switch (i.e. the time spent by the switch in the on position) indicates the actual current (I1) being supplied to the inductor. A device (6) measures the current passing through the switch when it is on, A processor is used to calculate the size of the pulse width needed for the actual current to correspond to the desired current whilst the switch is off. The control device regulates the pulse width on the basis of this pulse width calculation once the switch is turned back on again. The switch is turned on and off at a frequency of 1 (ca. 20) kHz or more. The switch comprises a semiconductor component, e.g. an IGBT.