High-performance ripple feedback for the buck unity-power-factor rectifier

The buck unity power factor rectifier has harmonic-free input current with complete load regulation down to zero output voltage. A new "nonlinear ripple feedback" is proposed which exactly cancels the spoiling effect of DC-side current ripple on the low-distortion AC line current waveforms, even for large amounts of ripple. This cancellation is independent of operating point and readily implemented with analog hardware, thereby permitting economies in the design of the DC filter while maintaining harmonic-free operation. Both large-signal and incremental analyses of the rectifier are given. Confirming experimental results from a 1 kW 48 V isolated battery charger operating with current-ripple levels ranging from 50 percent to discontinuous-conduction-mode operation are given.<
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