Development Of 7KVA Three-phase/single-phase Inverter

7KVA AC-AC high power Aeronautical Static Inverter (ASI) is being researched in this thesis. Based on the comprehensive investigation of different strategies, and for the purpose of improving overall efficiency and high reliability, the DC/DC stage of ASI proposes two-transistor forward converter with parallel-serial/serial combination.The operation principles and characteristics of the parallel- serial combination two-transistor forward converter (TTFC) were first presented. Then a TTFC with a LCD clamp circuit is proposed. With this clamping circuit, the switching devices at primary are turned-off at zero voltage. And based on comparison among several secondary snubber circuits, CDD (one capacitor and two diodes) snubber circuit was choosed. Besides, The operation principles and characteristics of the two-transistor integrated-magnetics forward converter is studied in this paper. The phenomena about magnetic deviation due to asynchronism of duty cycle and other parameters is analyzed by simulation. And the parameters which effect magnetic bias in the electric circuit are discussed.. The paper also presents the design process of power circuits and control circuits, and the small-signal model of combined two-transistor forward converter is researched through the average linearization method. Moreover, the stability and dynamic characteristic of the system is analysed in this paper.This paper also presents the AC/DC and DC/AC design of AC-AC circuit. And for the purpose of improving larger input frequency range , the AC/DC stage of ASI proposes Multi-pulse rectifiers. It can not only reduce harmonics of input current, but also decrease the magnitude of output voltage harmonics. In the mean time the ripple frequency could be increased as well. The paper also presents the design of DP-type 18-pulse asymmetric autotransformer rectifier. Compared with conventional half-bridge inverter, dual buck inverter (DBI) overcomes the short-through problem, and can choose the power switches and the power doides separately, and realizes the optimum design of power devices, with the result of higher overall efficiency and high reliability. With the introduction of the working principle of DBI, a 7KVA prototype was developed. And a single current detection method of DBI was researched. Besides, the design principles and optimum design methods of the DBI output filter was pointed out. At last, the experimental results verify the feasibility.