| If there is a number of harmonic current in the AC power supply systems on the air, it will lead tothe distortion of the load voltage and influence on the performance of electronic equipment whichrequires the high-quality input-voltage. In order to ensure that the power system on the air operationssafely, reliably and economically, the research on mid-frequency rectifier for aviation applications isof great significance. Compared with the technique of passive filter and multi-pulse rectifier on the air,PWM rectifier achieves the closed-loop control of the input current and output voltage, and receivesconsiderable attention.Firstly, the researching background and the main topology structure, control strategy andmodulation method in the three-phase PWM rectifier are introduced. Then this paper delves into theworking principle and control strategy of the three-phase three-leg PWM rectifier and does asimulation of the working state on the balanced input-voltage and imbalanced input-voltage.According to the analysis of the advantages and disadvantages of three-phase three-leg rectifier, thescheme of the three-phase four-leg PWM rectifier which adopts the third harmonic injectionmodulation is proposed. It improves the DC voltage utilization and the operation performance underthe imbalanced input. The simulation results verify the feasibility of the control scheme.Then，the small signal model for three-phase four-leg PWM rectifier as well as its control schemeis developed, and a regulation of voltage and current feedback loop is researched and designed.Finally, the main circuit, multiplication circuit and drive circuit are designed based on theperformance requirements. Experimental results of a10kW three-phase four-leg PWM rectifier verifythe analysis is correct. System shows good performance under both balanced and unbalancedconditions. |
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