Two-degree-of-freedom PI digital control of bi-directional voltage mode high frequency link inverter with active clamp

This paper presents a novel modulation and a two-degree-of-freedom (2-DOF) PI digital controller based on a bi-directional voltage mode high frequency link inverter with active clamp. A novel modulation strategy is applied by modulating the triangle carrier wave and two inverse sinusoidal modulation waves. It is no need of checking the pole of the output voltage to switch the drive signals, and it is able to weaken the distortion of the output on zero passage. This 2-DOF PI controller has two parameters to be designed separately and can obtain good dynamic responses both in the command tracking and load disturbance regulation characteristic. In this paper, the 2-DOF PI digital controller for the inverter system is designed and implemented to obtain high dynamic and static performance. The parameters of the controller are found by model building, theoretical deduction according to the desired specifications. The simulation and experimental results are provided to verify the proposed modulation and digital control strategy