Over-voltages suppression methods in multiple drives using single half DC-link inverter for long cable applications

This paper presents multiple drives of induction motors using single voltage source inverter through long feeding cables. As known, when the cable length is long, over-voltages at motor terminal could be doubled from the pulsed output voltage at inverter terminal. In this paper, a half DC-link inverter is implemented to drive three motors simultaneously for different configurations of cable lengths. The implemented inverter drastically reduces the over-voltage at three motor terminals with a proper duration time of Vdc/2 level (β). Simulation and experimental results are provided to show the effectiveness of over-voltage reduction by using this inverter. According to these results, for three motors with series multiple drives configuration, this β should be calculated based on the cable length closed to the longest.