Space vector modulation extended to voltage source converters with multiple legs in parallel

Abstract

This paper extends the space vector (SV) modulation to Voltage Source Converters (VSC) with multiple legs in parallel. Multiple legs voltage source converters are strong candidates for low voltage high power applications, such as wind power systems where the converter has to handle high currents. The main advantages of the proposed modulation are: (i) minimization of the total harmonic distortion (THD) of the output current or reduction the filter size; (ii) decoupling the output current control loops from the current sharing control loops. In addition the well-known features of the SV modulation such as the full utilization of the DC bus voltage and the possibility of minimization of switching losses can also be achieved. Finally, experimental results from a three phase multiple legs converter are presented to support the analysis carried out as well as to demonstrate the performance of the proposed SV modulation. Furthermore, experimental results are also presented to compare the proposed SV modulation with a conventional PWM with triangular phase-shift.