Study On Loss Performance Of Passive Three-Phase Soft-Switching Inverter

Increasing the switching frequency can reduces the volume and weight of power electronic circuits, improves the dynamic characteristics of the circuits. The switch of conventional three-phase PWM (Pulse width modulation) inverters works in hard-switching conditions. As switching frequency becomes higher, the fleetly increasing switching loss will lower efficiency of inverters, at the same time serious EMI (Electro magnetic interference) will be produced. In order to improve the switching process of switch, soft-switching technology came into being. And energy loss of three-phase inverters issues becomes a focus of people’s attention.The energy loss of three-phase inverter needs to focus on the device loss in the inverter, because we can carry out rational distribution according to the dimension of device energy loss. There are two ways to get the device energy loss, including by measuring the rise in temperature of the device and by calculating the integration of the device voltage and current product. How to obtain the device energy loss accurately based on work principle of the device receives widely focus and study during recent years. The calculated result of the device energy loss of soft-switching three-phase inverter is not accurate because of soft-switching technology has changed the switching waveforms of the switch. Therefore, in order to calculate the energy loss of soft-switching three-phase inverter, we need to analyze the specific commutation process of the switch, then we can calculate the loss according to the process of switching voltage and current waveforms of the switch.The energy loss study of three-phase inverters has in this thesis based on reading a lot of literature. On the basic of theoretical analysis results of the soft-switching three-phase inverter topology proposed in this thesis, presents a loss calculation method, and the performance of the circuit was verified by simulation study and physical experiment. The main jobs and conclusions as follows:Firstly, a novel soft-switching three-phase inverter topology was proposed, and its operation principle was analyzed. The result of theoretical analysis shows that the switch in the circuit can realizes soft-switching.Secondly, a loss calculation method of the soft-switching three-phase inverter was given. Thirdly, simulation study and physical experiment of this novel soft-switching three-phase inverter are made, and the results show that zero-current turn-on and zero-voltage turn-off of the switch can be achieved effectively. The actual waveforms in physical experiment show that the switching loss of switch under soft-switching condition can be ignored.