Comparison of five different approaches for real time digital feedback control of PWM inverters

The five schemes are resistive-load-based deadbeat (DB) control, disturbance-observer-based DB control I. disturbance-observer-based DB control II, internal-model-principle-based pole placement, and digital proportional-integral (PI) control. The control schemes are applicable to single-phase and three-phase balanced-load inverter systems because the balanced three-phase system can be converted to two decoupled single phase systems. The modification of the control law from a single-phase to a three-phase system is explained. Simulations were performed in both systems, and experiments were carried out in the three-phase PWM inverter system. The disturbance-observer-based I and the digital PI control schemes yielded the best overall performance. The former is better in terms of total harmonic distortion for a nonlinear load, but the latter is based on a much simpler algorithm.<>