Volume flow characterization of PWM-controlled fast-switching pneumatic valves

Abstract

In this paper we present results of an experimental analysis of the dependence of volume flow on pulse width modulation (PWM) control signal through a fast-switching pneumatic valve. The main goal of this study is to determine how the PWM frequency and duty cycle (pulse width) influence the volume flow and if there is a correlation between them. The highest PWM signal frequencies that can control the tested fast-switching valve were used. This way we minimised the influence of pressure pulsation that can make a pneumatic system, pressure regulator and flow sensor unstable at lower frequencies. The aim was also to determine if pressure difference and PWM frequency have any influence on the shortest pulse needed to open the valve. The volume flow was measured with a state-of-the-art mass flow sensor that can calculate average volume flow and isn't influenced by high-frequency pressure pulsation. We also made temperature measurement in a valve solenoid and pressure chamber during an 8-hour excitation with a PWM signal.