A new discrete-time voltage controller based on the internal model principle for three-phase voltage source PWM inverters with ΔY output transformer

In this paper a new digital voltage controller based on the internal model principle for three-phase inverters with Δ transformer at the output is proposed. A dynamic model of the inverter, transformer, filter and load is derived and a decoupling method is proposed. The proposed digital controller is not prone to produce DC components, which that can lead to the output transformer saturation. Additionally, this digital controller result in a simple form and it is well suited for a fixed-point implementation. Experimental results, implemented in 16 bits DSP TMS320F241, validate the theoretical developments and demonstrate the good performance of the proposed controller under both nonlinear balanced and unbalanced loads.