A DC-link voltage ripple compensation method for multilevel active-neutral-point-clamped converters operating with SHE-PWM
This paper presents a DC-link voltage ripple compensation method for the five-level flying capacitor (FC) based active-neutral-point-clamped (ANPC) converter operating with selective harmonic elimination pulse width modulation (SHE-PWM). The compensation method modifies the modulation index according to the DC-link voltage ripple, which in turns alters the switching functions. The modification of the switching functions alleviates the effect of the DC-link voltage ripple on the output voltage. A control strategy is implemented to regulate the voltages across the FCs and the DC-link capacitors to their reference voltage levels. The performance of the compensation method is evaluated with experimental results taken from a low power laboratory prototype.