Control strategy of a three-phase five-level double converter with adjustable DC voltage for induction motor drives

This paper describes a control strategy for a five-level double converter that consists of the five-level rectifier, the DC link, and the five-level inverter. The purposes of the proposed control strategy are to correct voltage imbalance of the DC link capacitors, to keep the input power factor at near unity, and to achieve adjustable-speed drive. The five-level rectifier is controlled by the instantaneous-value-compared current control method using multi-band hysteresis comparators. On the other hand, the five-level inverter is controlled by the space vector pulse-width modulation method. The validity of the control strategy is verified by experiments using a 3.7 kW induction motor.