Digital controller design based on active damping method of capacitor current feedback for auxiliary resonant snubber inverter with lc filter

Abstract

In some high-performance applications, an LC filter must be added to the auxiliary resonant snubber inverter (ARSI) to reduce the output current ripple. However, resonance occurs due to the additional LC filter, which makes the traditional closed-loop control not suitable to be used directly. Therefore, this paper presents a double-loop digital control based on the active damping method of capacitor current feedback to stabilize the system. Most of the studies on active damping methods are focused on the grid in consideration of zero resistance. However, the load resistance should not be neglected in the drive system. Therefore, the load resistance and digital control delays are considered in this paper. Moreover, an improved loading method is proposed to improve the duty ratio range. In order to verify the effectiveness of the controller, a prototype was developed. The simulation and experimental results demonstrate that soft-switching can be realized for the entire load range. The maximum duty ratio is improved by 0.01 by using the proposed loading method. The resonance can be eliminated by using the proposed control method.