Research for the characteristics of electro-mechanical converter for 2D digital servo valve

As electro-mechanical energy conversion interface of electro-hydraulic control valve, the electro-mechanical converter has a crucial influence on the performance of valve itself and thus the whole electro-hydraulic control system. In this paper the mathematical model of electro-mechanical converter using stepping motor was established and its frequency characteristic with voltage control and current control were analyzed, respectively. The simulation results show that the frequency width of electro-mechanical converter is 320Hz at 3dB (-90°) approximately and its rise time for step response is about 3ms. Besides, to ensure the electro-mechanical converter has both fast dynamic response and high position accuracy, a novel tracking control algorithm was presented and an embedded controller based on this algorithm is designed and developed. Finally to validate the accuracy of theoretical results and the effectiveness of tracking control algorithm, an exclusive test rig for electro-mechanical converter characteristics was built. Experimental results show that the measured frequency width of electro-mechanical converter is about 310 HZ at -3dB (-90°) and its rise time is about 5ms; And the frequency width of 2D digital valve that uses electro-mechanical converter above-mentioned is about 210Hz at -3dB (-90°) and its rise time for step response is approximately 8ms. Therefore both theoretical analysis and experimental results illustrate the electro-mechanical converter and corresponding have high frequency width and fast dynamic response.