A converter circuit includes an inverter and a controller. The inverter is configured to receive an input voltage and to convert the input voltage into a primary-side alternating-current (AC) voltage in a first inversion mode or a second inversion mode. Each of a first switch unit and a second switch unit in the inverter includes switches. When the converter circuit works in the first inversion mode, the controller controls switches of the first switch unit and the second switch unit to cooperatively switch on and switch off periodically according to an output voltage corresponding to the primary-side AC voltage. When the converter circuit works in the second inversion mode, the controller controls the first switch unit to operate independently, in which the switches of the first switch unit switch on and switch off periodically.