Enhancing Lifespan and Control Precision in High-Speed Switching Valve Pneumatic Pressure Servo Systems With Variable Frequency PWM and Duty Cycle Compensation

The single-chamber dual-valve pneumatic pressure servo system, characterized by its swift response and low cost, has significant applications in areas such as automotive braking and pneumatic clamping. To enhance pressure control accuracy and reduce the switching times of high-speed switching valves (HSVs) to prolong their lifespan, a novel mixed control strategy is proposed. This strategy combines a frequency regulation compensation method for duty cycle compensation to improve control precision and a variable frequency pulsewidth modulation (PWM) strategy to reduce HSV switching times. The mixed control strategy determines the base frequency of the PWM through a frequency regulation function and then optimizes the PWM frequency based on the duty cycle and valve dead zone range, achieving low-frequency response when system tracking errors are large and high-frequency precise operation when tracking errors are small. Experimental results indicate that the mixed control strategy demonstrates excellent performance in both static and dynamic responses. The total number of switches for the random step response decreased by 78.9%, while the root mean square error for the multifrequency sinusoidal response was reduced by 15.0%, and the total number of switches decreased by 20.3%. Additionally, it was confirmed that this mixed control strategy has a minimal impact on the system's air consumption.