DSP-based digital control of a PWM inverter for sine wave tracking by optimal state feedback technique

摘要

This paper proposes a fully digital control scheme for the closed-loop regulation of a single-phase PWM inverter used to synthesize a sinusoidal waveform even under large load variation. An accurate sampled-data model of the PWM inverter considering the sensor dynamics has been derived. The optimal state feedback gains of the proposed digital controller are determined by fitting a specified step response through the steepest descent method. The gating signals of the switching devices are computed at every sampling instant by instantaneous feedback of the inductor current and output voltage. The design procedure of the proposed digital controller and its software realization have been described in detail. Moreover, a DSP-based (TMS320C14) fully digitally controlled PWM inverter has been constructed to verify the proposed control scheme. The simulation and experimental results show that satisfactory results can still be obtained even at low sampling frequency.