1 Optimized ePWM Configurations

A basic totem-pole PFC structure is shown in Figure 1-1. Different from the boost converter, the control of a totem-pole PFC is much more complex. Based on the input voltage VAC polarity, high frequency FETs Q1 and Q2 alternately work as a PFC active switch or sync switch, while slow frequency FETs Q3 and Q3 switch at grid frequency. The basic control logic could refer to Control challenges in a totem-pole PFC. In the actual applications, it is required to consider how to better handle the transient conditions, when the power stage enters overload conditions, light load or fault conditions, which is discussed in the proposed PWM configurations.

Figure 1-1 Totem-Pole PFC Structure