DC-link Capacitors Voltage Control using a Multi-phase Induction Motor Load Driven by a Multilevel Inverter

In this paper, DC-link capacitors voltage deviation control is achieved using a symmetrical six-phase induction machine (IM) load driven by a nine-level inverter. The motor phase currents are utilised intelligently to control the common coupling points (CCPs: terminal connections series-connected capacitors across a DC-link). Each phase of this inverter consists of a five-level stacked inverter and two cascaded H-bridge (CHB) inverters, which can be built using low voltage switching devices. Simultaneous control of DC-link capacitors and CHB capacitors balancing is achieved by using the pole voltage redundancies. This concept is validated using a standard simulation tool with a six-phase load under the ‘V/f’ control operation. The simulation results for steady-state and transient conditions are provided at low speed and high speed of operation with low and high power factors conditions.