基于GaN的图腾柱PFC电流过零点问题的研究

在连续导通模式下,图腾柱无桥拓扑结构功率因数校正器(PFC)的损耗非常大,导致拓扑结构的效率降低,在输入电压过零点处电流容易发生畸变。针对此问题,提出了一种改进的过零点控制方法。将输入电压过零时段划分为两个控制阶段,即高频桥臂主开关管完成软启动,采用双极控制方法有效校正输入电流,使其跟随输入电压。搭建一台1 kW实验样机,并利用DSP开发板进行实验验证。测试结果表明,当开关频率为100 kHz时,功率因数为0.99,PFC模块效率最大可达98.5%,总谐波失真在输出功率大于200 W时小于3%。

Research on the Zero-Crossing Problem of Totem Pole PFC Current Based on GaN

Power factor correction (PFC) totem-pole bridgeless structures usually work in continuous conduction mode with an excessive loss, which lead to the reduction of efficiency of topological structure and the distortion of current at zero point of input voltage. An improved zero-crossing control method was proposed to solve this problem. The input voltage zero-crossing period had been divided into two stages. One stage was that the high frequency leg main switch device completed soft start, and the other stage was that the bipolar control scheme was used to correct effectively the input current to follow the input voltage. Finally, a 1 kW prototype of the continuous conduction mode totem-pole bridgeless PFC converter with a DSP digital modulator had made to verify the experiment. The test results showed that the power factor was 0.99 at 100 kHz switching frequency, the maximum efficiency of PFC module was 98.5%, and the total harmonic distortion was less than 3% while the output power was more than 200 W.