Analysis of dither in PWM control on electro-hydraulic proportional valve
Liu Guoping;Xia Wuxing;Qi Dawei;Hu Ronghua;School of Mechanical Engineering,Nanchang University;
Plus With Modulation( PWM) is widely used in proporational control systems for it is efficient,flexible and anti-interference. Due to the friction and hysteresis of electromagnet,hysteresis exists when hydraulic valve in steady-state,and hysteresis influences the dynamic characteristics of the valve seriously,the hysteresis can be improved by superimposing dithers with certain frequency and amplitude to the valve coil. Aiming at the character of anti-unloading power driver circuit,analyzed the parasitic dither which exists in ± 24 V PWM control,besides,the experiment shows that in a high frequency PWM,dither with independent frequency and amplitude can be generated by changing the frequency of the PWM,in this way,the average current of electromagnet and dither can be adjusted separately by changing duty ratio and frequency of PWM.
【CateGory Index】： TH137.52