Low-cost compact PM machine for adjustable-speed pump application

A variable-speed driven pump can result in significant energy conservation where reduced flow rates are required for long periods of time. Concerning adjustable-speed pump drives, one major contribution of this paper is to show that a permanent magnet motor based on the slotless axial-flux PM machine (AFPM) topology can be a suitable candidate to advantageously compete with the induction motor for such a low-cost drive application. To the purpose of a cost comparison, the paper discusses the design and construction of a prototype machine which has been conceived to replace a 1.2 hp induction motor being used in a standard adjustable-speed pump drive. Results taken from laboratory tests of the prototype machine are reported together with an assessment of the machine manufacturing cost.