No relation to the Terminator 3 saga, this “rise” refers to the expanding applications and growing physical sizes for today’s permanent magnet (PM) machines—motors, generators, and other devices. Times have changed the notion that PM machines comprise mainly small ac (and dc) motors.
        PM brushless synchronous motors have moved well beyond machine tool, CNC, and related traditional applications. Even here sizes have grown, for example, up to 220 kW rated power from Fanuc Ltd. Newer PM machine applications include general-purpose industrial processeswww.cechina.cn, electric hybrid vehicleswww.cechina.cn, magnetic (variable-speed) drivesCONTROL ENGINEERING China版权所有, and generators for giant wind turbines. The objective is high efficiency by cutting rotor losses compared to induction machines.
        One notable general-purpose product development is Baldor Electric’s RPM AC line of PM synchronous motors. The design combines a laminated steel frame stator and a salient-pole, interior PM (IPM) rotor for power density and efficiency (see Online Ref. 1). Rich SchaeferCONTROL ENGINEERING China版权所有, marketing manager for variable speed and specialty motors, explains that RPM AC series ratings are now available up to 700 hp (522 kW) in standard air-cooled version. Still higher ratings apply to water-cooled units, such as a gearmotor developed for the drilling industry, rated at 1,020 hp and able to produce 35,000 lb-ft (47,460 N-m) torque in a very compact space控制工程网版权所有, Schaefer notes.
        Indicative of further power growth ahead is a development for electrically driven gas compressors from GE Global Research. GEGR described a 6 MW, high-speed drive motor prototype at a March 2009 workshop staged by the U.S. Dept. of Energy and others (see Online Ref. 2). Efficiency and other benefits make PM machine topology the preferred choice above 15,000 rpm speeds, says GEGR.