Micro-power Active Clamped Resonant DC-link Inverter DC-link Control And Parameter Optimization Design

The active clamp resonant DC-link inverter (ACRDCLI) achieves soft-switching for the switching devices in inverter. ACRDCLI has the advantages of simple structure and high efficiency. With the Two-Amplitude control technique, the resonant loss is reduced and the converter's output performance is improved. The micro-power ACRDCLI should have the characteristics of high efficiency and long life. But the traditional ACRDCLI clamping voltage balance control strategy has a disadvantage of great loss in high-power. Therefore it is necessary to solve the problem brought by traditional DC-link control strategy. The parameters are optimized in order to achieve high efficiency.Firstly, the working process of the DC-link is analyzed in this paper. In order to make the DC-link work normally, the clamp capacitor voltage must be balance. The reason for the change of clamping voltage is analyzed. A no short-circuit control strategy is introduced. According to the loss estimation method, the loss of the circuit with no short-circuit control and short-circuit control strategy are calculated with MathCAD. The clamp capacitor value is calculated while its ripple was restricted to 20%. Secondly, the default parameters are given. The MathCAD software draws circuit operation waveform with different clamp coefficient, characteristic impedance, resonant frequency and switching frequency. The influence of various parameters on the loss of the DC-link is analyzed. According to the equivalent resistance loss and clamp switching loss calculation, the parameters of the micro-power inverter were designed. At last the inverter was simulated with matlab/simulink. The main parameters of the waveform were obtained.The results indicate that:compared to short-circuit control, the micro power ACRDCLI with no short control can reduce the loss of inverter and choose film capacitor as the clamp capacitor. The losses do not have much decrease but a big value clamp capacitor should be selected. The right shutdown current of clamp balance is difficult to be selected in the micro-power. Therefore, the micro-power ACRDCLI is more suitable to use short -circuit control strategy. When the parameters are selected, a high resonant frequency and a low switching frequency should be selected. The ratio of the resonant frequency and the switching frequency is selected as large as possible. If the maximum critical value is taken as the shutdown current, the losses of the DC-link could be minimized by taking 1.2 as the clamping coefficient and 10 as the characteristic impedance.The research of this paper is supported by natural science foundation of china (No.51107117).