Proportional current operated activator for valves - has pulse width modulated mode with dither frequency voltage and control signals mapped into memory

摘要

The controller for a proportional mode valve has an electromagnetic drive stage with a coil (1) that is supplied with current in the form of a pulse width modulated square wave signal. The pulses are generated by a switching transistor (2) that responds to inputs (3) generated by a microprocessor. The coil has inductance and resistance and the square wave input is converted into a different form current drive signal, such that the actual current differs from the ideal. The characteristic data for different voltages and dither frequencies are stored in memory and are accessed for control. ADVANTAGE - Obtains linear current for proportional control.