Research on Main Circuit of Voltage Sag Generator Based on MATLAB Platform

With the development of science and technology, the demand for power quality is getting higher and higher. Voltage sag is one of the most common power quality events. It is of great practical significance to develop voltage sag generator to accurately evaluate the impact of voltage sag on industrial sensitive equipment and take effective technical measures to reduce economic losses. In order to use the voltage sag generator in different fields, its volume and weight should be as small as possible. At present, the voltage sag generator has a large volume and heavy weight, which can't meet the volume requirements of industrial and laboratory elevators and is not convenient for mobile use. This paper designs a main circuit structure of voltage sag generator, which consists of three-level PWM rectifier, DC-DC converter, and three-phase half-bridge inverter. Using dual active bridge bidirectional DC/DC converter(DAB) instead of power frequency transformer can greatly reduce the volume and weight of the circuit. And the three-level PWM rectifier, dual active bridge bidirectional DC-DC(DAB) converter and three-phase half-bridge inverter are all designed by modularization, which is convenient for disassembly and assembly. PWM rectifier and dual active bridge bidirectional DC/DC converter are used to make the power supply have the function of bidirectional energy flow. three-level half-bridge inverter is used to simulate the power supply characteristics under various fault conditions. The working principle of each part of the voltage sag generator is introduced in this paper. The simulation results prove the effectiveness of the design.