Title :
Common-Mode Voltage Reduction Methods for Current-Source Converters in Medium-Voltage Drives
Author :
Zhu, Ning ; Xu, David ; Wu, Bin ; Zargari, Navid R. ; Kazerani, Mehrdad ; Liu, Fangrui
Author_Institution :
Dept. of Electr. & Comput. Eng., Ryerson Univ., Toronto, ON, Canada
Abstract :
Common-mode voltages (CMVs) can lead to premature failure of the motor insulation system in medium-voltage current-source-fed drives. By analyzing the CMV values at all switching states under different operating conditions of a current-source-inverter (CSI)-based motor drive, this paper first indicates that the CMV peaks are produced by the zero states in most of the cases. The nonzero-state (NZS) modulation techniques employed in voltage-source converters are adapted for use in a space-vector-modulated current-source converter (CSC) to reduce the CMV magnitude. For NZS modulation in CSCs, the nearest three-state (NTS) modulation sequences are designed with good low-order harmonic performances in their linear modulation region of ma ≥ 0.67 and with no increase in the device switching frequency. A combined active-zero-state (AZS) modulation technique is also proposed as compensation, for a lower modulation index in the range of 0.4-0.67, when a compromise is made between the dc-link current minimization and high input power factor control. The simulation and experimental results are provided to validate the CMV reduction effects and harmonic performances of the NTS and combined AZS modulation methods in CSI-fed drives.
Keywords :
invertors; machine control; machine insulation; motor drives; active-zero-state modulation technique; common-mode voltage reduction methods; common-mode voltages; current-source converters; current-source-inverter; dc-link current minimization; linear modulation; low-order harmonic performances; medium-voltage current-source-fed drives; medium-voltage drives; motor drive; motor insulation system; nonzero-state modulation techniques; power factor control; space-vector-modulated current-source converter; three-state modulation; voltage-source converters; Harmonic analysis; Modulation; Motor drives; Reactive power; Support vector machines; Switches; Vectors; Active-zero-state (AZS) modulation; common-mode voltage (CMV); current-source converter (CSC); nearest three-state (NTS) modulation; nonzero-state (NZS) modulation;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2012.2201174