Design, Modelling, and Analysis of a Capacitive Reservoir Based PWM Digital Circuit of Electro-Hydraulic Proportional Valve

The high-speed and high-accuracy current control circuit is a key component for the high-performance electro-hydraulic proportional valve. In this paper, a new capacitive reservoir-based PWM digital circuit (CRPDC) is designed, modeled, and analyzed. The proposed CRPDC employs a capacitive reservoir circuit to acquire electricity from the DC power supply while the PWM control signal is at a high level and the supply current for the proportional valve coil while the PWM control signal is at a low level, which will result in a small ripple and fast response of the coil current. For the proposed CRPDC, the charging and discharging mathematical models are specially established to reveal the response characteristics of the proportional-valve coil current. The coil current control performance of the proposed CRPDC is simulated by the mathematical models and the Multisim models. Simulation results demonstrate that the designed CRPDC can energize the coil current in a high-accuracy and fast-speed manner. In summary, the designed CRPDC has wide application in the current control of the proportional valve coil.