Control of Single Source Multilevel Inverter driving High Inductance Actuators with AC and DC Currents

High inductance actuators are found in many mechatronics systems and inverter requires higher voltage DC bus to drive these actuators with variable frequency and current magnitudes. Since the load is dominantly reactive, only a small current is required from the DC source to feed the active power of the load. In some applications, these actuators require AC and/or DC currents for the operation. In this paper, a control algorithm is proposed for a cascaded multilevel inverter with only one DC source to drive high inductance loads with AC and/or DC currents. It also offers the advantages of the multilevel inverter like multilevel voltage and low voltage rating switches. Multiple inverters can be added in series without DC source to get the desired voltage rating, but continuous active power rating is defined by the one inverter with DC source. The control system is developed to achieve the commanded AC and/or DC load current, to regulate the DC bus voltage of the inverter without DC source and manage the power sharing between the inverters during steady and transient operations. The experimental results are obtained to verify the inverter performance under various operational scenarios.