Voltage and current control of self-excited Switched Reluctance Generator for variable speed drive

This paper deals with the Switched Reluctance Generator (SRG), working in self excitation mode, for controlled generated voltage operation in variable speed environment. The inherent behavior observed is the existence of high amounts of reactive power circulating between the machine windings and the excitation capacitors that lead to high peaks of phase currents. These high currents, due to wide excursions in magnetic flux, can impose restrictions in the applications of the machine. It is observed that this high amount of reactive power is not necessary to reach given specifications in generated voltages. Therefore, the paper investigates a way to overcome this problem, through the control of the machine's phase currents. It is shown that with controlled phase currents the generator still delivers desired voltages and power, within a range of speed variation. The work explores the current control strategy based on controlling the phase switching angles, through hysteresis control. Block diagram of the control system is presented, along with the state space model of the SRG, which includes the saturation of the magnetic circuit. The complete set is simulated and the results are presented and discussed. Bench experiments are carried out to validate the simulation findings, where all control circuitry is developed in digital environment using the TMS320F28335 DSP platform. These experimental results are also included.