Development of Hydraulic Pump Drive System Using Switched Reluctance Motor with Servo Function

A switched reluctance motor (SRM) generates a reluctance torque without the power of a permanent magnet, rendering it a candidate for rare-earth free motors. Compared with a permanent magnet synchronous motor (PMSM), SRMs also offer operational advantage in high-temperature environments owing to their robust structure. However, SRMs are generally inferior to PMSMs in terms of torque ripple, noise, and speed control, in particular. Therefore, this study attempts to improve the controllability of SRMs by proposing an SRM driving method in the form of a bidirectional rotation torque and a speed-controllable servomotor. The advantage of this method is evaluated experimentally using a closed-loop hydraulic system (valveless control system), which includes a hydraulic pump driven by an SRM to supply hydraulic power to actuators. The results show that the pump flow rate and hydraulic motor speed are consistent with the sinusoidal commands corresponding to the forward and reverse rotations of the SRM.