Journal of Electrical Engineering and Technology

The Korean Institute of Electrical Engineers (대한전기학회)
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Research on the Mechanism of Neutral-point Voltage Fluctuation and Capacitor Voltage Balancing Control Strategy of Three-phase Three-level T-type Inverter

  • Yan, Gangui (School of Electrical Engineering, Northeast Electric Power University) ;
  • Duan, Shuangming (School of Electrical Engineering, Northeast Electric Power University) ;
  • Zhao, Shujian (School of Electrical Engineering, Northeast Electric Power University) ;
  • Li, Gen (Cardiff University) ;
  • Wu, Wei (School of Electrical Engineering, Northeast Electric Power University) ;
  • Li, Hongbo (School of Electrical Engineering, Northeast Electric Power University)
  • Received : 2017.01.14
  • Accepted : 2017.08.23
  • Published : 2017.11.01
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Abstract

In order to solve the neutral-point voltage fluctuation problem of three-phase three-level T-type inverters (TPTLTIs), the unbalance characteristics of capacitor voltages under different switching states and the mechanism of neutral-point voltage fluctuation are revealed. Based on the mathematical model of a TPTLTI, a feed-forward voltage balancing control strategy of DC-link capacitor voltages error is proposed. The strategy generates a DC bias voltage using a capacitor voltage loop with a proportional integral (PI) controller. The proposed strategy can suppress the neutral-point voltage fluctuation effectively and improve the quality of output currents. The correctness of the theoretical analysis is verified through simulations. An experimental prototype of a TPTLTI based on Digital Signal Processor (DSP) is built. The feasibility and effectiveness of the proposed strategy is verified through experiment. The results from simulations and experiment match very well.

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References

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