Development of a Low Cost Sensored Control for High-Speed Axial Flux Permanent Magnet Machines

Abstract

A Low Cost Control for a compact High-Power High-Speed Axial Flux Permanent Magnet (AFPM) Machine has been developed in this research. The machine under consideration has been designed to run in the generation as well as in the motoring mode for utilization in vast industrial and automotive applications. When used as a motor for automotive applications, the machine is directly coupled to a radial inward flow compressor to operate as an electric driven supercharger running in the range of 40,000 – 50,00 rpm. To run the machine as a motor at its rated speed and power, a suitable electric drive and controller has to be utilized while considering the machine performance characteristics. Most of the available Commercial Off-The-Shelf (COTS) systems are either designed for low-speed high-power machines or high-speed, low-power machines. In addition, the self inductance of such machines are relatively high (in the range of hundreds of millihenry) compared to the AFPM machine under consideration which has a very low self inductance (in the range of tens of microhenry). The low inductance of PM machines often makes current control difficult. If high switching frequencies are not used, the current ripple in the machine windings will be very high, causing degradation of the overall machine efficiency and increasing the rotor torque ripple and pulsation.  In this research a high frequency inverter-based controllers using Insulated Gate Bipolar Transistors (IGBTs) is utilized to overcome the problem of the low inductance of the machine. For simple and low cost control scheme, Hall effect sensors are used to energize the machine coils in the appropriate sequence thus providing accurate and precise control. The sensored control is analyzed using computer simulation and a prototype of the controller is also developed. Simulation results are validated by the experimental tests which showed good match and demonstrated the machine behavior under such controller and provided promising results for further research and investigations.

Keywords: sensored control, low cost control, permanent magnet machines, axial flux machines;

This research is funded by the Deanship of Research and Graduate Studies in Zarqa University /Jordan