(A) new resonant converter controlled by integral cycle mode

Abstract

In this thesis, a new control method named as an integral cycle mode control for resonant converters is proposed. Output voltage of the resonant converter is controlled by proper selections of switch modes and the switch modes are analyzed for the resonant converters. Dc transfer functions are derived under the given load and control pattern and they are quantized due to resonant operation. Therefore, the resonant converter controlled by integral cycle mode is named as a quantum resonant converter (QRC) in this paper. The practical control scheme is suggested, simulated and verified through the experiment. In the proposed control scheme, zero current or zero voltage switching conditions are always guaranteed because switching instants are always synchronized with zero crossing points of the resonant current (in series resonant converter (SRC) or voltage in parallel resonant converter (PRC). Because of the zero current or zero voltage switching Characteristic of the quantum resonant converter, the switching stress and switching loss of the device are considerably low and the resonant converter can be operated at high frequency. Thus magnetic components and capacitors can be reduced in the size and weight. The models of the quantum resonant converters are simple and exact practically. The quantum SRC is modeled as a conventional buck/boost dc/dc converter. The quantum PRC is modeled as a conventional cuk, buck or boost converter. The validity of the proposed models is verified through analyses, simulations and experimental results. From these results, it is shown that series and parallel resonant circuits of the resonant converter are modeled as an equivalent indictor and capacitor, respectively. Dc and ac transfer functions of the quantum resonant converters are derived from analytical results, which are analogous to those of the conventional PWM converter except the quantized characteristics. Hence, systematic control algorithms for the PWM dc/dc converter can ...