Abstract: Disclosed is a method for controlling battery charging/discharging current in an off-grid mode of a hybrid energy storage inverter that is based on photovoltaic and a lithium battery. If photovoltaic energy is sufficient and a battery is not fully charged, the photovoltaic energy is supplied to a load and excess energy is supplied to the battery, to achieve maximum power point tracking of an output power of a photovoltaic component achieves maximum power point tracking; if photovoltaic energy is sufficient and a battery has been fully charged, the photovoltaic energy is supplied to a load, the excess photovoltaic energy is prohibited from charging the battery to prevent overcharging of the lithium battery; if photovoltaic energy is insufficient, the photovoltaic energy and battery energy are jointly supplied to a load, to achieve maximum power point tracking of an output power of a photovoltaic component.

Abstract: An inverter circuit for realizing high-efficiency control of single-phase power of a single-phase three-wire power supply includes a bridge inverter circuit connected to an output end of a DC power supply, a freewheeling circuit connected to an output end of the bridge inverter circuit for providing freewheeling during switching of the bridge inverter circuit, and a control unit connected with the bridge inverter circuit and the freewheeling circuit. When the switching units in the high-frequency operating state are switched to an off state, the freewheeling circuit is controlled to operate continuously to output power to the U-phase line or the W-phase line, so that the switching units only participate in high-frequency operations in nearly half of the whole mains cycle, thereby switching loss and conduction loss of the switching units Q1 to Q6 can be reduced by nearly half, and the efficiency of the whole inverter circuit is greatly improved.