Improved Voltage Regulation of Higher Order DC-DC Converter with Zero Voltage Switching using Digital Controller

摘要

In this paper a digital controller for improved voltage regulation of higher order DC-DC resonant converter with zero-voltage switching over an entire load range is proposed. The controller uses duty cycle and frequency both as control variables. The weakness of resonant converter is that the operation under conventional frequency control requires a wide range of frequency from rated load to very light loads. A control using duty cycle has a very limited control range and achieving zero-voltage switching (ZVS) is very difficult at light load. Therefore, a digital controller is proposed wherein duty cycles as well as frequency are varied for regulating the DC output voltage with respect to load. The proposed controller provides excellent converter efficiency and maintains soft switching over entire load range. The proposed control is a programmable approach and applicable to any converter tank with minimum modification in control algorithm. Also the proposed approach is flexible as frequency and duty cycle can be adjusted independently of each other. The experimental results on a 3000W, 220V/400V higher order LCLC resonant converter prototype are presented to validate the functionality of the proposed approach.