Gradationally Controlled Voltage Inverter for More Electric Aircrafts 2019-01-1913

The more electric aircraft (MEA) concept has been attracting attention over recent decades to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems, and hence the weight of inverters has significant importance. The weight of inverters is largely attributed to passive filters that reduce the derivative of output voltages dv/dt and electromagnetic interference noises caused by common-mode voltages. To reduce the size of passive filters, multilevel inverters with 5 or more voltage steps are preferred. However, classic multilevel inverters have some challenges to achieve these step numbers without using plural dc power supplies that require massive transformers. In this work, a gradationally controlled voltage (GCV) inverter is proposed for MEAs. The GCV inverter can supply gradational quasi-sinusoidal voltages with 7 voltage steps, combining two different voltages from a three-level (main) inverter and H-bridge (sub) inverters. In addition, only one dc power supply is required for the main inverter. Furthermore, when sub inverters have faults, the GCV inverter can continue operation using the main inverter. Simulation results confirm that the GCV inverter suppresses common-mode voltages and dv/dt as low levels as the classic multilevel inverter and continues operation during a fault.