SR drive for hydraulic pump using a novel passive boost converter

This paper presents a practical pressure control of hydraulic oil-pump system using SR(Switched Reluctance) drive. For a 6 Mpa grade hydraulic oil-pump, 2.6 kW SR drive is developed. In order to minimize the power consumption during the maintaining of preset oil-pressure, the pressure control system changes the maximum oil-pressure band and flow rate according to the motor speed. For the efficiency and output power, a novel passive boost converter is proposed. The proposed converter has a simple passive circuit in the front-end of conventional asymmetric converter, which consists of three diodes and one capacitor. With the additional passive circuit, it is possible to have high demagnetization voltage. And the boost capacitor can keep the DC-link voltage automatically. With the high negative bias during commutation, positive torque region can be extended and the passive boost converter can save energy and improve the efficiency, output power. Some computer simulation and experimental results are done to verify the performance of proposed system.