Verification and simulation of a discrete energy function based nonlinear controller for an AC/DC boost PFC converter

The conventional two loops PI control system of a Power Factor Correction (PFC) boost converter has a slow dynamic response against load variations due to the fact that the voltage loop must have a very low bandwidth in order to avoid distortions in the input current waveform. To allow the ac/dc boost PFC converter to operate with faster dynamic response and simultaneously maintain near unity input power factor, a new control approach that is based on a novel discrete energy function minimization control law has been proposed. To evaluate the performance of the new control approach, a simulation of a 6.4 kW PFC boost converter was conducted with Simulink and PLECS. Difficulties and potential flaws in control system implementation were discussed. Finally, a new method to synthesize load resistance and reference input current was proposed based on the result of simulation. Results show that the duration of transients can be limited to 2~3 line cycles and the overshoot/undershoot of the output voltage can be limited to several volts when there is a load change.