Research On Single-phase Inverter And The Reliability Of Its Parallel System

With the development of technology, the reliability of electrical equipment is becoming more andmore important. In many occasions related to people’s life and property, such as hospitals, banks,aerospace and national military units, the quality and the reliability of power supply is especiallyimportant. If the power supply unit breaks down suddenly, it must recover as soon as possible. Thepower supply system must have strong sustainability and maintainability. To ensure the continuingwork of the power supply system, we need predict the time at which a failure in power supplyequipment will happen and take remedial measures to avoid power failure.The reliability of inverter and parallel system has been studied in this paper. The state-spaceaveraging method is used to establish the mathematical model of full-bridge inverter. This is thefoundation of study. After modeling, a set of reasonable parameters of closed-loop control is designed,which achieves the requirement of both the dynamic-state and steady-state performances of inverter.For the inverter parallel system, analog control and digital control are respectively used torealize current sharing control. The error value of electronic elements used in analog controllerpresents regular distribution, and it will influence the circulating current in this system eventually. Asa comparison, digital control strategy has been adopted for deep research in this paper.For further improvement of reliability in inverter, a new protection method, which takes intoaccount of various factors affecting the reliability of inverter, is put forward in this paper. And the safeoperating area (SOA) of inverter system has been derived considering those factors. At last, a practicaloperational area for convenient control is selected in SOA.And the hardware circuit has been designed to prove the consistency of the theoretical analysis.Finally, reliable prediction of single-phase inverter and parallel system are conducted in thispaper. According to these calculations, it’s easy to find that the most important factor which affects thereliability of inverter is the power switch tube. As the supplement of this paper, the reliability ofinverter parallel system has been studied, and it proves that the reliability of inverter parallel system ismuch greater than that of single inverter quantitatively.