Single phase three-level SVPWM algorithm and its relationship with carrier-based PWM with zero-sequence voltage injection

A significant problem of three-level neutral-point clamped (NPC) converters is the fluctuation of the neutral-point voltage. A SVPWM strategy with neutral point voltage balancing for single phase three-level converters adopted widely in railway traction drive system is proposed in this paper. The relationship between the adopted SVPWM and carrier-based pulse width modulation (CBPWM) with a zero-sequence voltage injection (ZSVI) is analyzed in details. Theoretical analysis shows that SVPWM is a special type of CBPWM-ZSVI methods. Performance of the proposed SVPWM scheme is verified by simulation and experimental test.