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Special stator windings boost efficiency in motor/generator for hybrid vehicles

Special stator windings boost efficiency in motor/generator for hybrid vehicles

To meet the demand for drive motors / generators needed for hybrid vehicles, engineers at Remy International Inc. designed a line of off-the-shelf devices that are said to have the highest efficiencies and power densities of any motor/generator on the market.

The key to these HVH motors are their High-voltage Hairpin stator windings. Unlike convention round-wire windings, these motors use precision-formed rectangular or hairpin wires. Several layers of these interlocking hairpins have better slot fill than conventional windings (up to 70% for HVH compared to 40% for round windings). This creates a shorter end-turn space, thereby reducing heat and improving torque and power density, as well as reducing motor size. The winding scheme also makes it easier to strengthen the construction at critical connections between conductors. The HVH windings are well-suited to liquid cooling which enhances performance and reliability.

In tests, an HVH internal-permanent-magnet (IPM) motor generated 27% more torque and 37% more power compared to the same sized round-wire- winding IPM motor. And HVH motors offer a 22% reduction space requirements and 13% less mass than conventional motors with the same performance characteristics.

The motors are modular. To simplify the engineering involved in adding an HVH motor to a vehicle, the motors meet SAE standards and use SAE bellhousing and transmission bolt patters. Though motors noramlly use internal permanent magnets for torque, power, and efficiency, they can instead use an ac induction coil for simpler controls and lower cost.

The HVH250 (standard) motor generates 60 kW off continuous power, 82 kW of peak power and operates at 93% efficiency between 2,500 and 10,000 rpm. The 33.5-kg motor turns out 200 Nm of continuous torque and 325 Nm of peak torque. It measures 147-mm long and 242-mm in diameter. The standard HVH410, a 36-kg motor, produces 110 kW of continuous power, 130 kW of peak power, ,and operates at 94.5% efficiency. Continuous torque is 580 Nm and peak torque is 830 Nm. There are also high-torque versions of the motors as well as ones with high-flow cooling.


Remy International Inc., Pendelton, Ind., (

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