Proportional solenoid valve control system

A proportional solenoid valve control system for controlling a current in a proportional solenoid valve, comprising:

• a current command detection circuit for detecting a differential voltage between an input voltage and a reference voltage and generating a current command output signal;
• an offset circuit which receives said current command output signal from said current command detection circuit, and generates an offset signal according to an offset value which can be varied by user;
• a current command limiting circuit which receives said current command output signal and said offset signal, and generates a limited output current which is set to a fixed value when said offset signal is larger than said current command output signal and is set to be equal to said current command output signal when said offset signal is not larger than said current command output signal;
• a current detection circuit for detecting the current flowing in the proportional solenoid valve and generates a solenoid current signal responsive to the detected current;
• a proportional integrator controller which receives a first triangular pulse signal alternating between a positive value and a negative value, said limited output current and said solenoid current signal and forms an error signal;
• a pulse width modulation comparator which receives and compares a second triangular pulse signal and said error signal to form a pulse width output signal;
• and
• an output circuit which generates a switching signal having a duty ratio corresponding to said pulse width output signal.