Sliding Mode Control of Llc Resonant Dc-Dc Converter For Wide Output Voltage Range in Battery Charging Applications

In this paper, a sliding mode control of the llc resonant dc-dc converter low voltage and high current to the battery charger for electric vehicles is presented. the proposed controller operates at two fixed switching frequencies with sliding mode control implementation. in resonant converter, because of the soft-switching process, switching loss is negligible and converters can be designed at high frequencies to decline their size, weight and price. to analyze this convertor the harmonic approximation method with state space equation is used. taking advantage of the approximations used in order to avoid uncertainty, sliding mode control method is used. the mentioned convertor with the proposed controlled is exploited within three switching frequency bands that are lower than resonant frequency, resonant frequency and above resonant frequency. due to the robustness of the sliding mode control, the output voltage regulation occurs with minimum distortion under a wide variation of input voltage, output voltage and output current. as a result, the battery life increases. in order to verify the results and effectiveness of the proposed converters, the prototype of llc resonant converters simulation and experimental results for the input voltage (300-420vdc), output voltage (36-72vdc) and current output (0-11a) is presented. the prototype achieves a peak efficiency value of 96%.