Low Cost, Power Dense, Axial Gap, Rare-Earth-Free PM Motor for Electric Drive Vehicles
- Magnetic Power-Motion, LLC
Cost and size reductions are needed in the electric traction drive system currently used for electric drive vehicles (EDVs) to make them cost and performance competitive with fossil fuel vehicles. Such cost parity is critical to achieving public acceptance and expanded market share of EDV products. To achieve cost and size parity, the DOE has established 2025 technical targets of $3.3/kW and 50kW/L for the electric traction motor. Interior permanent magnet (IPM) synchronous motors are a popular choice for the traction motor due to their high torque and power density, high efficiency, simple control, and field weakening ability for constant power operation. However, the rare-earth magnets used in these motors are costly, accounting for 20% to 30% of the total motor cost. Furthermore, as China is the primary supplier of the rare-earth materials used in these magnets, they are susceptible to supply and cost volatility. Therefore, the DoE is seeking a motor solution that can meet stringent 2025 cost and power density targets without the use of rare-earth materials. Proposed for this application is a novel, axial gap, IPM motor design that uses low cost Alnico magnets. This design is based on a single stator, dual-rotor topology that makes very efficient use of active materials for low cost, and a unique wave winding that provides low losses, excellent cooling, and a large magnetic air gap for high power-density. It also employs an advanced rotor design that is able to field-weaken the motor (for constant power operation) without demagnetizing the Alnico magnets. In the Phase I effort, a preliminary design was developed, and a number of mechanical and electromagnetic design options were investigated. Design models were developed and used to generate optimal designs that met power and efficiency requirements at minimum volume. Design studies were conducted to examine how motor volume and cost varied with certain key parameters, such as the magnetic pole number and base speed. Although predicted performance and cost fell short of DOE targets, the results suggested a viable design could possibly be achieved with several identified improvements.
- Research Organization:
- Magnetic Power-Motion, LLC
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018695
- OSTI ID:
- 1546090
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE18695
- Country of Publication:
- United States
- Language:
- English
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