Topology and Control Strategy of Anti Direct Connection Single-Phase Three-Level Inverter With a Center-Tapped Inductor
Three-level inverters have the advantages of low voltage stress in power devices and low harmonic content in bridge leg output voltage.They are widely used in high-pressure applications.In order to avoid the problem of direct connection on the DC side,dead-time is necessary to add in the drive signals of the power switches.Dead-time not only introduces additional low-frequency harmonics,but also exacerbates the imbalance of DC side capacitors.The reliability of inverter operation will be affected.This paper proposes a three-level inverter with a center-tapped inductor.The inductor serves both anti direct connection and filtering purposes.Thus the inverter can avoid direct connection problem from the topology.Also the inverter constructs a freewheeling path to avoid sudden changes of the inductor current.The corresponding three-level modulation strategy of the proposed inverter is studied.The consistency between the proposed inverter and traditional three-level inverter is analyzed.On the basis,the filtering and anti direct connection effects are discussed through the equivalence of the center-tapped inductor.The topological advantages of achieving capacitor balance is analyzed.Finally,the correctness of the theoretical analysis was verified through simulation and experiments.
anti direct connection inverterdead-timecapacitor balancecenter-tapped inductorthree-level modulation
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维普
