PR controller implementation using double update mode digital PWM for grid connected inverter

This paper proposes Proportional Resonant (PR) controller implementation with double update mode digital PWM for grid connected single phase inverter. Digital implementation of PR compensator to track the sinusoidal current reference is also presented. A distinctive advantage of PR controller over conventional Proportional Integral (PI) controller for disturbance rejection capability and lower steady state error is achieved. Model of double update digital PWM is analysed and implemented through DSP. The advantage of modulation delay reduction in proposed digital PWM in double update mode improves the closed loop performance. The PR controllers are tuned to suppress the lower order harmonics. Design of the controllers and their tuning methodology is elaborated and analysed through simulation in MATLAB. Phase Lock Loop (PLL) elimination in grid synchronization and removal of switching noise component in sampled signals is demonstrated. The experimental results of 100W grid connected inverter with the PR digital controller implementation through TMS320F28027 are validated for the proposed control scheme.