Minimization of Filter Capacitor for Medium-Voltage Current-Source Converters Based on Natural Sampling SVM

Current-source converters (CSCs) used in high-power (megawatt level) medium-voltage (MV) (2.3–6.6 kV) drives require three-phase capacitors to assist the commutation of switching devices and to filter out harmonics of the converter output PWM current. Different types of modulation schemes with different harmonic performance lead to different capacitor selections. Conventional space vector modulation (SVM) featuring high dynamic performance cannot be used in practice even with the help of active damping, which can effectively damp the possible LC resonance introduced by conventional SVM. Recently, a natural-sampling SVM (NS-SVM) is proposed for MV CSC drives. It features superior low-order harmonics and has been highly considered for MV CSCs in practice. This study, therefore, focuses on two issues. One is why conventional SVM cannot be used in practice even with the help of active damping. On this basis, the second is capacitor minimization based on NS-SVM. Finally, experimental verification is provided.