Ironless machine design and novel digital control for automotive applications

Permanent magnet brushless DC machines are commonly used for automotive applications because of their inherently high efficiency, power density, reliability and low maintenance. However, in order to obtain high performance for mentioned applications, the overall hardware system can be very complex and costly. This paper presents an ironless machine design that can be used for in-wheel traction machines as well as for Integrated Starter/Alternators (ISA), controlled by a novel digital control strategy for 4-quadrant machine operation. Machine design is suitable for different radius of the wheel and is scalable in terms of power density. It does not require iron, so composite materials can be used, which was one of the limitations with conventional machine. In addition, a low-cost digital control strategy has been presented that can be used by itself, or as a subsystem of a more complex control scheme. For applications that do not require a high degree of speed accuracy, the proposed control strategy shows faster response when variable speed command is applied to the shaft of the machine. The implementation of this scheme is also much simpler than most existing methods used in automotive applications.