Vector Control System of Induction Machine Supplied by Three-Level Inverter Based on a Fast SVPWM Algorithm

Diode clamped multi-level inverter (DCMLI) has wide application prospect in high-performance medium or high voltage adjustable speed drive systems. In this paper, a vector control system of an induction machine using neutral-point-clamped (NPC) inverter is proposed. In the system, the indirect rotor-flux-oriented control of an induction machine supplied by a voltage-source inverter with fast current control is employed, the magnitude and space angle of the rotor flux-linkage is obtained by flux model. A fast space vector pulse width modulation (SVPWM) algorithm based on 60°coordinate is used for the control of a three-level inverter, which can easily get the desired vectors and calculate their dwelling time. Aimed to the capacitor voltage unbalance resulted by active power output in the motor operation, the control of neutral-point potential is implemented by adjusting the dwelling time of the redundant vector by detecting the capacitor voltage and the neutral line current. Experimental results verify the good performance of the three-level inverter-fed drive with vector control.