基于可变电感的高品质DCM/CRM Boost PFC 变换器研究

DCM和CRM Boost PFC变换器广泛应用于中低功率交-直变换领域，但存在电感电流峰值高或开关频率变化范围宽等缺点，造成器件应力大、效率提升受限、EMI滤波器设计和交错并联控制困难等问题。本项目首先建立可变电感与偏置绕组及主绕组电流等参数间的数学模型，并给出其设计方法。其次，对于DCM和CRM，在保持单位功率因数的同时，分析能实现半个工频周期内的（准）满开关周期利用和（准）定开关频率的电感值连续或分段变化规则，推导其与输入电压、输出电压、输出功率、开关频率和输入电角度的关联函数。然后，在负载或输入电压跳变时，探究可使跳变前后开关管导通时间不变的新电感值，实现输出电压的稳定平滑过渡。最后，系统提出可变电感及主功率电路的控制方法，以达成高功率因数、高变换效率、优动态响应、易扩展设计目标。本思路也可推广至其他拓扑及DC/AC、DC/DC、AC/AC领域，研究成果具有重要理论意义和应用价值。

DCM and CRM boost PFC converters are widely used in the field of medium and low power AC-DC converter, but they have some disadvantages such as high peak value of inductor current or wide range of switching frequency variation, which lead to the problems of large device stress, limited efficiency improvement, difficulty in EMI filter design and interleaving parallel control. In this project, firstly, the mathematical model of variable inductance, bias winding and main winding current is established, and its design method is given. Secondly, for DCM and CRM, while maintaining the unit power factor, the rule of continuous or segmented change of inductance which can realize (quasi) full switch cycle utilization and (quasi) constant switching frequency in a half line cycle is analyzed, and its correlation function with input voltage, output voltage, output power, switching frequency and input electrical angle is deduced. Then, in case of load’s or input voltage’s step change, the new inductance which can make the conduction time of the switch unchanged before and after the step change is explored to realize the stable and smooth transition of the output voltage. Finally, the control method of variable inductor and main power circuit is proposed to achieve the goals of high power factor, high conversion efficiency, excellent dynamic response and easiness of expanding design. This idea can also be extended to other topologies and DC/AC, DC/DC, AC/AC fields. The research results have important theoretical significance and application value.