The inverter converts DC power into AC power. If the DC voltage is low, the standard AC voltage and frequency are obtained by boosting through an AC transformer. For large capacity inverters, due to the high DC bus voltage, the AC output generally does not require transformer boost to reach 220V. In medium and small capacity inverters, due to the low DC voltage, such as 12V and 24V, a boost circuit must be designed.

Medium and small capacity inverters generally have three types: push-pull inverter circuit, full bridge inverter circuit, and high-frequency boost inverter circuit. The push-pull circuit connects the neutral plug of the boost transformer to the positive power source, and the two power transistors work alternately to output AC power. Due to the common ground connection of the power transistors, the driving and control circuits are simple. In addition, the transformer has a certain leakage inductance, which can limit the short-circuit current, thus improving the reliability of the circuit. Its disadvantages are low transformer utilization and poor ability to carry inductive loads.

The full bridge inverter circuit overcomes the shortcomings of push-pull circuits. The power transistor adjusts the output pulse width, and the effective value of the output AC voltage changes accordingly. Due to its freewheeling circuit, even for inductive loads, the output voltage waveform will not be distorted. The disadvantage of this circuit is that the power transistors of the upper and lower bridge arms are not grounded, so a dedicated driving circuit or isolated power supply must be used. In addition, to prevent joint conduction between the upper and lower bridge arms, it is necessary to design a circuit that turns off first and then conducts, that is, a dead time must be set, and its circuit structure is relatively complex.