考虑电感软饱和特性的图腾柱PFC变换器预测控制方法

Predictive Control Algorithm Considering the Soft Saturation Nature of the Inductors for Totem-pole PFC Converter

磁粉芯电感由于其具有饱和磁密高、气隙分布均匀、高频损耗较低等优点,近年来在功率因数校正场合得到了广泛应用。但由于磁粉芯具有软饱和特性,采用磁粉芯绕制的电感器在高直流偏置下电感偏移量极大,使得在数字实现的PI电流控制器参数设计时难以兼顾控制器性能与系统稳定性。为了解决这个问题,可以采用更加适用于数字实现的PFC平均电流预测控制方法,但是预测控制依赖于模型参数,而磁粉芯电感的使用降低了系统响应速度与控制精度。为此,首先分析电感软饱和特性对传统预测控制的影响,通过分析磁粉芯的软饱和特性及其变化规律,提出一种模型在线修正的平均电流预测控制方法。并将其应用于数字控制3.6kW图腾柱PFC变换器评估其性能,通过实验证明了分析结果及所提出控制方法的有效性。

The powder core inductors have been widely used in power factor correction applications in recent years due to their advantages of high saturation magnetization, uniform air gap distribution, and low high-frequency loss. However, because of the soft saturation nature of the powder cores, it is difficult to take into account both the quality of the current and the stability of the system when using the proportional-integral(PI) current controller. To improve the quality of the current, an average current predictive control method that is more suitable for digital control PFC converters can be adopted. Besides the predictive control relies on the model parameters, the powder core inductors limit the speed and accuracy of the control system. Firstly, the influence of soft saturation nature on the traditional predictive control was introduced in this paper. According to the soft saturation nature of the powder core and its variation law, an on-line modified method was proposed for the average current predictive control algorithm to eliminate the influence of the inductance nonlinear variation. Finally, the performing experiments verify the analysis and proposed method using a 3.6 kW PFC converter.