Research On Voltage Balancing Of Series Connection Of IGBTs In A 10kV High Voltage Frequency Converter

The technique for AC adjusting speed is a main means of saving power, improving industrial flow to improve quality of products and environment, advancing the development of technique. The variable frequency and speed adjusting technique is commonly considered a promising method for its advantages of high adjusting speed and starting-stopping performance, high efficiency and power factor, and the effect of power saving in various methods for adjusting speed. However, the development of variable frequency and adjusting speed technique has a close relationship with the development of power devices.As the core of main circuit in frequency converter, power switch devices play an important role in the circuit IGBT is applied widely for its advantages of high input resistance, high operating speed, low forward voltage, high carrying capacity and easier driving. However, the voltage and current ratings of IGBT device are low and cannot satisfy the requirements for development of application and technique of power electronics. To realize the high voltage application of IGBT, researching the technique for series connection of IGBTs has a very important meaning.The entire subject is to research voltage balancing of series connection of IGBTs against the background of a 10kV high voltage frequency converter, In the subject, a voltage balancing circuit is designed and a problem on IGBT not applied in high voltage frequency converter for its limited voltage ratings is solved.First, this paper narrates some main knowledge about IGBT, such as its structure, operation principle, basic characteristics and protection methods. Secondly, this paper analyzes the factors in influencing operation of series connection of IGBTs and compares load-side voltage balancing technique with gate-side voltage balancing technique, and presents a control method of gate-side dynamic voltage balancing. Furthermore, a chopper circuit mat consists oftwo series-connected IGBT is designed and the satisfactory simulation results are obtained by simulating voltage imbalance, and the feasibility of voltage balancing circuit is testifiedFinally, a chopper circuit that consists of six series-connected IGBTs is set up. The experimental results show that the voltage balancing circuit can restrain voltage imbalance during switching transient in the circuit of series connection of IGBT and the problem on IGBT not applied in a 10 kV high voltage frequency converter is solved.