Abstract: A resonant converter and a variable cutoff frequency control method of the resonant converter are provided. The variable cutoff frequency control method includes obtaining a first relationship between a lower limit frequency of the resonant converter and a preset voltage outputted by the resonant converter; updating the preset voltage in the first relationship to a correlative voltage between the preset voltage and an actual voltage outputted by the resonant converter, to obtain a second relationship between the lower limit frequency and the correlative voltage; and limiting the lower limit frequency of the resonant converter according to the second relationship.

Abstract: A bidirectional DC/DC converter and an energy storage system are provided. The bidirectional DC/DC converter includes: a first half-bridge circuit, a second half-bridge circuit, an inductor circuit, an inductor current detection circuit, and a control circuit. The control circuit is configured to: according to an operating mode, determine one of the first and second half-bridge circuits as a target half-bridge circuit; determine a target switch circuit and a freewheeling switch circuit; control the target switch circuit to be turned on and off periodically; control the freewheeling switch circuit to be turned off when the target switch circuit is turned on; control the freewheeling switch circuit to be turned on when the target switch circuit is turned off; and when an amplitude of a current flowing through the inductor circuit is less than or equal to a preset threshold value, control the freewheeling switch circuit to be turned off.

Abstract: An inverter system, including a pre-conversion circuit, a post-conversion circuit, and a control circuit; the pre-conversion circuit is configured to convert a voltage of a power supply into a DC voltage and output the DC voltage to the post-conversion circuit; a voltage between the pre-conversion circuit and the post-conversion circuit is a DC bus voltage; the post-conversion circuit is configured to output an alternating current; the control circuit is configured to detect a DC component of an output terminal of the post-conversion circuit, calculate a difference value of a zero value and the DC component to obtain a DC component deviation value, and perform PI adjustment on the DC component deviation value to obtain a voltage compensation value; the voltage compensation value is used to adjust the DC bus voltage.