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A novel single-phase pulse width modulation (PWM) direct ac-ac converter based on two-level non-differential dual-buck ac chopper legs with inverting and non-inverting operations is first proposed in this paper. It has the ability to resolve both voltage sag and swell problems at the same time when used as distributed flexible voltage conditioner (DFVC). Compared to the traditional ac-ac converter, it has much enhanced system reliability thanks to no shoot-through problems even when all switches of each ac chopper legs are turned on, and therefore, the PWM dead-time is not needed leading to improving the utilization of the duty cycles. Only half of the switches in the proposed converter are switched at high frequency during a switching period at most, which significantly reduces the total switching loss. In particularly, the converter has two greatest advantages that it retains the common sharing ground of the input and output and has the same buck/boost operation process for non-inverting and inverting modes. In order to fully testify the performance of the proposed converter, a 500W experimental prototype is built and tested at different conditions.

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