Power factor correction of a single-phase on-line UPS with the half-bridge inverter

The power factor correction (PFC) scheme of the conventional on-line UPS with the half-bridge inverter is proposed and described. A correction method for the positive voltage boost stage is like the well-established boost corrector, but the PFC circuit of the negative voltage boost stage is different. The power factor of unbalanced loads can be still close to unity by the proposed scheme. Design considerations for the half-power positive or negative boost corrector are also presented and discussed. The experiment has been conducted to verify the proposed circuit.