Study on the conversion of operating modes of floating valve under different switching frequencies

On-off attitude and orbit control valves achieve variable thrust output via pulse width modulation (PWM) technology. Their regulation process typically adopts a segmented control strategy combining wide-range thrust coarse adjustment with high-precision small-thrust fine adjustment, resulting in dynamically changing characteristics of the PWM period. Since the selection of switching frequency is directly determined by the PWM period, systematically investigating the dynamic operating characteristics of attitude and orbit control floating valves under different switching frequencies holds significant theoretical value and engineering significance for improving the control accuracy of attitude and orbit control systems. Firstly, this paper established a cold-gas experimental platform for floating valves and conducted a series of experimental studies at switching frequencies of 0.85 Hz、2.5Hz、 5 Hz、6.5Hz、10 Hz, and 16.5 Hz. The results show that the response process of the floating valve exhibits four typical modes, namely complete step response, rapid response, enhanced step response with delay, and zero-output response, and reveals the evolution law that the opening and closing time of the floating valve decreases with the increase of switching frequency. Secondly, to reduce the computational cost in engineering applications, a reduced-order model of the floating valve with fast prediction capability was adopted. Through simulation calculations, the frequency interval thresholds corresponding to the four operating modes were clarified. Finally, the influence mechanisms of key design parameters—such as the area ratio of the jet orifice to the pilot valve orifice, the structural dimensions of the pintle, and the initial volume of the lower chamber of the floating valve—on the modal frequency range were systematically explored, which provides theoretical basis and technical support for the structural optimization design of floating valves and the precise control of attitude and orbit control systems.