The present disclosure provides a bidirectional power supply (100) includes an AC port (110), a line-frequency rectifier/inverter (120) and a set of switches (215). A bidirectional resonant supply (100) is coupled to a DC port (140) with primary-side switches (240) and secondary-side switches (250) respectively arranged on a primary and secondary side of a transformer (225). A controller (150) controls the primary-side switches (240) and the secondary-side switches (250) by controlling switching frequency based on a determined value while setting time delay between control of the primary-side (240) and the secondary-side switches (250) to be a predefined time delay or by controlling the time delay between control of the primary-side (240) and the secondary-side switches (250) based on a determined value while setting the switching frequency to be a predefined switching frequency.