Application Overview
Electric vehicle traction motors are the single largest automotive consumer of NdFeB magnets. A typical passenger-EV PMSM drivetrain uses approximately 1.2 kg of sintered NdFeB per 100 kW of peak motor power, with rotor magnets operating at internal temperatures above 150°C under continuous duty. The grade choice directly determines torque density, thermal derating, and the motor's ability to survive fault conditions without demagnetization. European and North American OEMs overwhelmingly specify SH and UH grades with GBD processing to balance performance, cost, and heavy-rare-earth exposure.
Why NdFeB for EV Motors
NdFeB delivers the highest energy product of any commercial permanent magnet material. This directly translates to smaller, lighter motors with higher torque density — critical for vehicle range, packaging, and handling. Alternative materials (ferrite, SmCo) either cannot reach the required flux density or cannot deliver it economically at automotive volumes.
Key Design Requirements
Max operating temperature
Typical rotor-magnet hotspots reach 150–180°C in sustained high-load duty cycles; 200°C+ in performance variants. Minimum grade: N42SH for entry-level, N45UH or N42UH for premium programs.
Intrinsic coercivity (HcJ)
Must survive stalled-rotor and short-circuit fault currents without permanent demagnetization. HcJ ≥20 kOe at working temperature is a practical minimum.
Flux consistency
Motor-to-motor torque variance directly correlates with magnet-to-magnet flux variance. Target <1% variance across a production lot.
Dimensional tolerance
Air-gap sensitivity means ID/OD tolerance of ±0.02mm and concentricity ≤0.05mm is standard for automotive-qualified suppliers.
Traceability & compliance
IATF 16949 certification, batch-level BH-curve data, and REACH/RoHS compliance are non-negotiable. MOFCOM export licensing must be handled by the supplier.
Recommended NdFeB Grades for EV Motors
Grade selection depends on the specific duty cycle, operating temperature, and torque requirements of your design. Below are the most common specifications used for ev motors.
N42SH
150°C · Super High Temperature (SH)Workhorse SH-grade NdFeB for 150°C traction motors, robotics actuators, and high-duty servo drives.
N45SH
150°C · Super High Temperature (SH)High-flux SH-grade NdFeB for compact, high-torque motors operating continuously up to 150°C.
N48SH
150°C · Super High Temperature (SH)Premium SH-grade NdFeB — the gold-standard magnet for high-performance EV and robotics motor rotors.
N42UH
180°C · Ultra High Temperature (UH)High-performance UH-grade NdFeB for the most demanding traction, aerospace, and industrial motor applications.
N45UH
180°C · Ultra High Temperature (UH)Top-tier UH-grade NdFeB — rare production, reserved for the highest-performance traction and aerospace motors.
N42EH
200°C · Extreme High Temperature (EH)Highest commercial EH-grade NdFeB — the upper limit of 200°C NdFeB in production today.
Typical Magnet Configurations
- •Surface-mounted arc segments bonded to back iron (IPM alternatives for performance variants)
- •Radial multi-pole sintered rings for compact auxiliary motors (EPS, water pumps, cooling fans)
- •Halbach and skewed arrays for torque ripple reduction in premium drivetrains
- •Laminated V-shape or spoke-type configurations for interior permanent magnet (IPM) rotors
Typical dimensions: Arc segments typically 20–60mm chord length, 3–10mm radial thickness, 15–80mm axial length. Radial multi-pole rings 40–250mm OD, 8–12 poles.
Design & Procurement Considerations
- 01GBD-processed grades are the default for European Tier 1 automotive programs — they meet spec with 50–70% less heavy rare earth content, reducing both cost and supply-chain risk.
- 02Coating choice matters: epoxy-over-NiCuNi is standard for adhesive-bonded rotor assemblies; plain NiCuNi is acceptable for mechanically retained designs.
- 03Thermal FEA must include realistic duty cycles — specifying a grade based on continuous rated temperature alone under-accounts for transient peaks.
- 04Dual-sourcing is no longer optional for traction programs given recent rare earth export control volatility.
Frequently Asked Questions
What grade of NdFeB magnet is used in EV traction motors?
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Most EV traction motors use N42SH to N48SH grades with GBD processing for standard programs, and N42UH to N45UH for premium/performance variants. The specific grade depends on peak continuous operating temperature (150°C for SH, 180°C for UH) and the required torque density. Always specify minimum HcJ at working temperature, not room temperature.
How much NdFeB is used in a typical electric vehicle?
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A passenger EV traction motor typically uses 1.0–1.8 kg of sintered NdFeB, scaling with motor peak power. A rough rule is 1.2 kg per 100 kW of peak power. Premium dual-motor variants can use 2.5–3.5 kg across both motors. This excludes the smaller NdFeB magnets in auxiliary motors (EPS, water pump, cooling fan) which add another 0.3–0.6 kg.
Do EV traction motor magnets require heavy rare earths?
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Yes — dysprosium (Dy) and/or terbium (Tb) are required to achieve the coercivity needed at traction-motor operating temperatures. Grain Boundary Diffusion (GBD) processing reduces the heavy rare earth content by 50–70% versus conventional production while maintaining the same grade performance, and is standard for European OEM programs.
Can I source EV motor magnets directly from a Chinese manufacturer?
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Yes, direct manufacturer sourcing is fully permitted. The required MOFCOM export license is held by the supplier and managed on their side. Qualification typically requires IATF 16949 certification, batch-level BH-curve data, and documented process control — requirements a capable factory will meet without friction.
Request a Quote for EV Motors
Share your application, target dimensions, operating temperature, and annual volume. Our UK-based engineering team responds within 1 business day with grade recommendation, followed by pricing and lead time typically within 2 business days.