The chart demonstrates that the reverse recovery loss of SiC-MOSFET is only 1/6 th of Si-MOSFET.įigure 4: a) Traditional PFC current sensor, b) Current Transformer (CT), c) Shunt resistor with Opamp and isolator, d) Magnetic current sensor module or IC based on Hall Effect or AMR sensor, e) MCA1101 application circuit with OCP function, f) MCA1101 application circuit without OCP functionĪ current transformer (CT) can be used to sample the inductor current. It is clear that SiC device dramatically reduces the body-Diode loss. Table 2 compares the amounts of reverse recovery loss between Si-MOSFET and SiC-MOSFET. Si-MOSFET to SiC-MOSFET provide different amounts of body-Diode loss. Using a SiC-MOSFET can dramatically reduce the reverse recovery loss enabling the Totem Pole PFC to work in CCM mode to support higher power. The choice of SiC-MOSFET over GaN-MOSFET is based on SiC-MOSFET providing higher breakdown voltage needed for this application. We chose a SiC-MOSFET C3M0065090K from Wolfspeed as the high frequency switches and a IXFH80N65X2 from IXYS as the low frequency switches.
In the paper, we will discuss a Totem pole architecture and design based on SiC MOSFETs, magnetic current sensing and CCM control. With the availability of fast switching wideband gap transistor SiC and GaN based power switches, which have minimal reverse recovery charge along with other advantages, Totem Pole PFC designs can now operate in CCM mode to provide higher efficiency and higher power. In addition, the peak current will be 2 times of a CCM PFC, which increases the difficulty of EMI filter design and efficiency optimization. When using a BCM PFC, the operation frequency varies widely. But both have challenges.Ī DCM PFC can only support low power applications.
This means that the Totem Pole PFC can only work in DCM (Discontinuous Conduction Mode) or BCM (Boundary Conduction Mode) mode with traditional Si-MOSFET. (A DCDC boost converter provides output voltage higher than the input voltage.) For a synchronous-rectified boost, a big problem is reverse recovery charge of the MOSFET body-Diode if the converter works in CCM (Continuous Conduction Mode) condition. Why SiC-MOSFET is needed in Totem Pole PFC designĪs Figure 2 shows, Totem Pole PFC can be considered a synchronous-rectified boost DCDC converter. Figure 1: a) Bridgeless PFC, b) Totem Pole PF Design consideration of Totem Pole PFC
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