电液比例阀独立颤振的叠加方法研究

Method Study of Superimposing Independent Dither to Electro-hydraulic Proportional Valve

脉宽调制信号以其高效、灵活、抗干扰能力强的特点被广泛应用在电液比例控制系统中。由于磁铁材料的磁滞和运动的摩擦力会导致液压阀稳态特性存在明显的滞环现象,滞环严重影响了阀的动态响应性能,减小滞环比较有效的方法是在驱动信号中叠加一定频率的颤振信号,目前普遍采用改变PWM波占空比的方法来实现颤振信号的叠加。通过理论推导和实验研究证明:改变PWM波的频率参数能实现频率和振幅均独立可调的颤振,这种颤振叠加方式使电磁铁平均电流和颤振电流分别受PWM占空比和PWM频率的独立控制。

Plus Width Modulation （PWM）is widely used in proportional control systems for its characteristics of efficient,flexi-ble and strong ability of anti-interference. Due to the friction and hysteresis of electromagnet,hysteresis phenomenon was caused to ex-ist in characteristics of hydraulic valve in steady-state,and the dynamic response performance of the valve was seriously influenced by the hysteresis. The relatively effective method of reducing the hysteresis was by superimposing dithers with certain frequency and ampli-tude to the diving signal,currently,changing the duty ratio of PWM was widely used to implement the superimpose dither to the signal. Through both the theoretical deducing and experimental study,it proves that dither with independent adjustable frequency and ampli-tude can be generated by changing the frequency of the PWM,in this way of superimposing dithers,the average current of electromag-net and dither current can be controlled independently by the duty ratio and frequency of PWM separately.