A rotary fluid power converter for improving energy efficiency of hydraulic system with variable load

Due to throttling losses, the variable load hydraulic servo system based on traditional valve control is less efficient. In this paper, a rotary fluid power converter (RFPC) is designed for improving the efficiency of hydraulic energy in mobile hydraulic robots and other hydraulic systems with variable load. The mechanism of RFPC is validated via simulation, based on MATLAB/Simulink. The RFPC can change the output pressure or flow to meet the hydraulic system load without throttling control, it regulates the output hydraulic energy by controlling energy conversion processes. The working principle of RFPC is similar to the transformation principle of boost electronic transformer. The transformer is based on the principle of electromagnetic induction for voltage regulation, while the RFPC is based on hydraulic-mechanical energy conversion. The rotary fluid power converter is controlled by pulse-width modulation (PWM) wave, and the output pressure or output flow rate of the RFPC can be adjusted by changing the duty cycle of the control signal. The MATLAB/Simulink model of the rotary fluid power converter is built to analyze its performance and energy efficiency. The simulation shows that the novel RFPC has a higher working efficiency than the traditional throttling control in most cases. •A rotary fluid power converter (RFPC) is an energy-saving hydraulic energy converter.•High pressure oil and low pressure oil are mixed in rotary inertia module to match the load.•The RFPC uses pulse width modulation (PWM) method to achieve throttle-less control.•RFPC exhibits better energy efficiency performance than traditional servo valves in variable load systems.