Research On A Novel ZCS-PWM Switch Cell

This paper focuses on a novel Zero-Current-Switching (ZCS) pulsewidth-modulated (PWM) switch cell firstly. The main switch and auxiliary switch operate at ZCS turn-on and turn-off, and all the passive semiconductor devices operate at zero-voltage-switching (ZVS) turn-on and turn-off at specified voltage range and at all load range. In addition, the switch cell has the less current stress in comparison to the ZCS-PWM switch cell counterpart. The principle of operation, theoretical analysis, design and control circuitry of the Buck converter based on the novel ZCS-PWM switch cell are also presented in this paper.The performance of this converter is verified by simulation and experimental results obtained from a 300W, 30 kHz prototype.Based on the analysis above, an improved ZCS-PWM witch cell is obtained and presented in the paper nextly, which overcomes some shortages in original switch cell by getting rid of a resonant inductor and the diode in series with the auxiliary switch and by adding one clamp diode. Moreover, it reserves all the merits in original switch cell. The principle of operation, theoretical analysis, design and control circuitry, and simulation and experimental results of the Buck converter based on the novel ZCS-PWM switch cell, rated 300W and operating at 30 kHz, are also provided in this paper as an example to verify the performance of this improved ZCS-PWM switch cell.At the end, a novel Boost Power-Factor-Correction (PFC) converter employing the improved ZCS-PWM switch cell is presented. The PFC converter is characterized by simple structure, ZCS, low switch voltage stress and low current stress, high efficiency and high powe-factor. The operational principle, the output characteristics and the condition for ZCS of the switches are analyzed. Simulation and experimental results obertained from a prototype rated 1000W and operating at 50 kHz are given.