Effect of rotor counter bore in LSPMM

Single-phase induction motors are widely used in several household applications and in the last years became the goal of some governmental agencies that introduced regulations focused in reduction of energy consumption. The use of line start permanent magnet motor (LSPMM) as a substitute of induction motor has been largely discussed in the academy and industry last decades because it combines the advantage of the brushless permanent magnet motor with the high starting capability of the induction motor. However, in some application reciprocating compressor, a counter-bore is sometimes used in the induction rotor to reduce final compressor height. This work analyses the effect of counter bore in LSPMM used in reciprocating compressors and presents results of simulations obtained with analytical and numerical analysis and finally experimental results.