Nurnburg, Germany

The widespread use of active Power Factor Correction (PFC) circuit is becoming even more popular as government agencies demand more effective use of grid supply capacities. A typical PFC circuit includes a diode bridge for rectifying the ac source and a boost stage to force the input current proportional to the input voltage. The rectifier bridge consumes a significant part of the circuit loss; therefore, many topology innovations for bridge-less PFCs have emerged. But most suffer from either common mode (CM) electromagnetic interference (EMI) or other issues and, therefore, are not practical.

One unique topology called the totem pole PFC has both simple power loops and low

EMI [1]. However, this topology demands very-low reverse recovery charges (Qrr) for

the MOSFET body diodes – not possible with high-voltage Si MOSFETs. With the advent

of Gallium Nitride (GaN) power devices [2] [3], new 600V-class low Qrr transistors make this highly promising circuit a practical reality.


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