基于复合PWM的高速开关阀先导控制电液换向阀特性试验研究OA北大核心CSTPCD

In order to address the problems of imprecise flow control&large pressure impact in traditional hydraulic support directional valves,a high-speed on/off valve-based electro-hydraulic directional valve control hydraulic cylinder scheme was proposed.A test platform was built to study the pilot valve characteristics,and compare the response speed of the electro-hydraulic directional valve when using high-speed&conventional electromagnetic on/off valves as pilot stages.Due to the short lag time of the high-speed on/off valve,the main valve control chamber pressure rises quickly,enabling faster response.Methods of pulse width modulation(PWM)&pulse frequency modulation(PFM)were proposed to control the displacement of the main valve core.Results show that the core's steady-state displacement undergoes four stages,exhibiting a proportional opening effect within a specific duty cycle range.The adjustment of the displacement of the main valve core can be achieved by the high-speed on/off valve throughout the stroke under 10 MPa liquid supply pressure,the control interval of composite PWM signals is 30%～65%duty cycle,whereas the control interval of conventional PWM signal is 35%～50%duty cycle.The composite PWM signals have wider adjustment interval compared with conventional PWM signals,which are more suitable for proportional control of directional valve core displacement.The results can provide reference for the design&development of hydraulic support control valves.