Real-time State Monitoring During Switching Mode Transitions in High Power Three-level Inverters

Nowadays,high power multiple-level inverters get more and more wide application in industry.However,multiple-level inverters have complex topologies and many devices,which makes it difficult to simultaneously monitor and analyze the operation states in different modes.Aimed at high power 3-level inverters,this paper first accomplished the on-line test of switching dynamic performances.Based on the test data,the paper researched further on the topology variation rule during switching mode transitions,in both theoretical and practical load circumstances.Through real time monitoring on the all circuit electrical parameters and device states,the authors find the additional electrical stresses during the 3-level inverter switching commutations under abnormal working conditions.At the same time,after profound researches,the paper gave the reasons for such additional electrical stresses under the abnormal conditions,which provides references for 3-level inverter malfunction diagnosis,and also plays a role in designing high efficiency multiple-level inverter system,both theoretically and practically.