Efficient PM motors are half the size of induction machines

Hitachi is considering launching a range of permanent magnet, brushless DC synchronous motors and drives in the UK as a smaller, lighter and more efficient alternative to induction motors. The Ecoheart motors, which have been available in Japan for several years, have recently been released in North America.

Compared to standard induction motors, the Ecoheart motors are said to be 10% more efficient, because their internal power losses are cut by half. The PM motors are also half the size, and weigh 35% less than comparable induction machines. A 3.7kW machine operating at 7,200 rpm, has an efficiency of 92% (or 87.4% including the inverter), and a rated torque of 0.5Nm.

The motors use a new stator winding method, and the current waveform is sinusoidal instead of the trapezoidal shape that most other PM motors use. Other attractions are said to include low torque ripple, vibration, harmonics and vibration levels.

In North America, Hitachi is aiming the motors at OEMs. The drives have no standard form factor and can be tailored to the OEM`s needs. At present, the Ecoheart range of optimised for pump applications, but other versions for fan, compressor, conveyor and other energy- and space-saving applications are planned.

Stuart Harvey, managing director of Hitachi`s UK operation, Silverteam, says it is "very likely" that the PM drives will be sold in the UK but no final decision has been made yet. Silverteam is also looking at bringing other Hitachi ranges into the UK, including two- to eight-pole AC motors and elevator drives.