Deadbeat controller with phase corrector for 400-Hz inverter used in ground power units of aircrafts

The digital controller faces a severe phase delay problem in medium frequency inverters while updating the pulse width modulation (PWM) of the inverter. In this paper, a digital controller for maintaining the phase balance and ac voltage regulation of a 400-Hz inverter for the ground power unit (GPU) using Deadbeat control is presented. The disturbance decoupling networks are provided along with the Deadbeat controller to give good disturbance rejection capability and improve the robustness towards the load variations. However, the performance of the digital controller is affected by the sampling, A/D conversion and the execution of the programs in digital processors. To improve the performance, the time delay compensation is done by providing a phase corrector scheme. The difference in phase is measured by Fourier analysis, and the compensation is provided at the reference sinusoidal waveform of the SPWM control strategy. Simulation is done on MATLAB/Simulink platform and the waveforms for single phase as well as three phase bridge circuits are obtained for linear as well as non-linear loads.