ac line cycle dropout is a power failure that significantly impacts the operation of power factor correction (PFC). If an ac dropout duration is less than the targeting power supply hold-up time, it is highly desired to resume PFC operation without resetting the system. ac dropout performance is extremely important in server power supply units (PSUs) where reducing system downtime is critical. In this paper, ac dropout algorithm is proposed for a digitally controlled totem-pole bridgeless PFC. The proposed algorithm shows the fast detection of ac dropout and demonstrates the ability to immediately resume PFC operation when ac gets back. The proposed method does not require any additional components and can be easily integrated with a digitally controlled PFC design. The test results are validated with a totem-pole bridgeless PFC prototype.
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