Application of GaN devices for 1 kW server power supply with integrated magnetics

In today's power electronics products, quality and reliability are given. Great emphases are placed on high efficiency, high power density and low cost. With recent advances made in gallium nitride power devices (GaNs), it is expected that GaNs will make significant impacts to all three areas mentioned above. Thanks to the absence of reverse recovery charge and smaller junction capacitances, the turn-on loss of GaN is significantly reduced and Turn-off loss and driving loss are negligible, for the first time. These desired properties coupled with ZVS techniques will drastically reduce all switching related losses, thus enabling GaN to operate at a switching frequency more than ten times higher than its silicon counterparts. To illustrate the impact of GaN on efficiency, density and even design practice, a 1 kW server power supply is demonstrated which employs an interleaved CRM totem-pole PFC followed with an LLC resonant converter. Both operate beyond 1 MHz. All magnetic components are integrated into PCB with much reduced EMI noises, thus, only a simple one-stage EMI filter is required. The system achieves a power density more than 150 W/in
³
, an efficiency above 96%, and much improved manufacturability with minimum labor content.