Research On High Current AC Generator

In the field of power system, high current AC generator provides current corresponding to the level for detecting the accuracy of large current transformer. Traditional 50 Hz AC current generator has a low efficiency, large volume weight, low power factor and is inconvenient to carry. In this paper, the technology of power electronics is used to achieve high current adjustable output.Firstly, the background of this research is introduced. By aiming at the drawback of traditional high current generator, this paper proposes to use a figure of three stages which includes AC/DC PFC+high step down DC/DC transformer+low voltage and high current DC/AC.Then it analyzes the status of DC-DC transformer and low voltage and high current output inverter. In the occasion of low-voltage input and high-voltage output, the second chapter studies the secondary side leakage inductor has effect on the actual gain curve of LLC resonant converter. The methods of improving the external characteristics and efficiency are proposed. Faced with the need of high step-down converters, the structure of PSSP sharing the switching network is proposed to reduce the resonant leakage inductance in order to improve the external characteristics. This paper presents the analysis of high step-down LLC transformer and the design using. Besides, this paper analyzes how the differences of transformer parameters affect the current unbalance of PSSP. In the third chapter, several control strategies of non-isolated interleaved full-bridge controllable current source inverter with a common DC and AC bus are analyzed and compared with each other. Analysis of the harmonic structure of the inductor current under the control of interleaved carrier-based unipolar is researched, and the maximum ripple of a single inductor current of the converter are analyzed in the interleaved condition according to the operating mode,which is compared with synchronized condition. This provides guidance for the design of inductor. An experimental prototype converter of LLC resonant DC-DC transformer is built in the fourth chapter.And two modules in parallel is also designed. The parameters of the main circuit and the control circuit are given respectively, and the experimental verification is carried out.