An exact discrete-time model considering dead-time nonlinearity for an H-bridge grid-connected inverter

With the development of the renewable energy, grid-connected H-bridge inverter plays a more important role than ever. However, the dead-time and the zero crossing clamping (ZCC) effect caused by dead-time can cause THD problem. As a consequence, more and more researches have focused on this issue. Most of the researches use the harmonics to replace the effect of dead-time, which ignores ZCC effect. Some other researches use the average current to distinguish the ZCC effect, which is not accurate enough. This paper analyzes the whole changing process of inductor current ripples during power cycle and a complete discrete-time model of the H-bridge grid-connected inverter with dead-time is established. On the basis of the model, the analysis of dynamic behavior is carried out, the result of which shows that the length of dead-time can cause nonlinear phenomenon and reduces the stability region of the controller parameters. Besides, this model is also useful to the nonlinearity compensation of the system.