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

Abstract

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.

Nonlinear PI-Control Approach for Improving the DC-Link Voltage Control Performance of a Power-Factor-Corrected System

“…In [16], the voltage loop was studied under a control based on a discrete energy function. The idea of the energy function method is to measure the peak power of the load and then use this information to determine a feed forward term to improve the response of the voltage control loop to load changes.…”

“…This paper presents a nonlinear PI control method for voltage control in a PFC system, which can provide a fast step response and low current loop distortion. Compared with foregoing papers [9], [12], [13], [16], [17], the proposed approach has several advantages; the approach is simple to tune as the tuning procedure is similar as in a standard linear PI-controller, while the overall controller complexity is kept to a minimum. With the proposed control, the obtained load transient dynamics are at least as good as can be obtained by 'best' linear control [12] or nonlinear control with more complex structure, such as used in [17].…”