A 50kW integrated fault tolerant permanent magnet machine and motor drive

The integration of an electrical machine and power electronics promises many benefits, the largest being an increase in power density. The use of system integration may lead to an increase in loss density and local or component temperatures. For this reason much attention needs to be paid to the thermal design aspects of the system. In the aerospace industry weight and reliability are of significant importance. In this paper the integration of a permanent magnet machine and power electronics into a single structure with joint thermal management is investigated. An overall goal of 2 kW/kg is set for system power density. Additionally in this paper fault tolerance is introduced into the design. This will allow the system to continue functioning should a single electrical fault occur. Principle faults are identified and discussed. A 50 kW, 6 phase, 8 pole permanent magnet machine is presented with a rotor speed of 50 krpm. A symmetrical phase shifted full bridge is used to drive the permanent magnet machine, aiding the functionality of fault tolerance and enabling the use of soft switching. A mathematical model for both machine and power electronics is created and used to calculate phase currents and losses in the machine and power electronics. Finally, spatial integration and thermal management concepts are presented and analysed.