Choosing non-oriented electrical steel for EV and high-efficiency motors
Thickness, core loss and magnetic induction pull in different directions in motor design. A practical guide to the Baosteel A and AH series.
Unlike transformer steel, non-oriented (NGO) electrical steel has similar magnetic properties in all directions in the sheet plane, which suits rotating machines where the flux direction changes continuously. Choosing a grade for a motor is a balance between core loss, magnetic induction, thickness and cost.
Reading the grade
In Baosteel names such as B35A270, “35” is the nominal thickness (0.35 mm), “A” the non-oriented series and “270” the guaranteed maximum core loss P1.5/50 multiplied by 100, i.e. 2.70 W/kg at 1.5 T and 50 Hz. The AH series (for example B50AH470) are high magnetic induction grades.
| Grade | Thickness (mm) | Maximum P1.5/50 (W/kg) |
|---|---|---|
| B35A210 | 0.35 | 2.10 |
| B35A250 | 0.35 | 2.50 |
| B35A270 | 0.35 | 2.70 |
| B35A300 | 0.35 | 3.00 |
| B50A290 | 0.50 | 2.90 |
| B50A350 | 0.50 | 3.50 |
| B50A470 | 0.50 | 4.70 |
| B50A800 | 0.50 | 8.00 |
Values are the guaranteed maxima from Baosteel product information. Actual values for each lot are on the mill certificate.
Thickness: 0.35 mm or 0.50 mm?
Eddy-current loss rises with thickness and with frequency. Motors that run at higher electrical frequency—EV traction motors, high-speed compressors and servo motors—usually benefit from 0.35 mm or thinner material. For industrial motors at mains frequency, 0.50 mm grades often give the best cost per kilowatt. Thinner gauges and grades for EV and high-frequency use are available on request; their values follow the Baosteel quotation and certificate.
Loss or induction?
- Low-loss grades (lower number) improve efficiency, especially at partial load and higher frequency.
- High-induction AH grades let the motor reach the required torque with less current or a smaller cross-section.
- Stamping and stress-relief annealing change the final properties; agree the processing route early.
Equivalent grades
When a drawing specifies a European or Japanese grade, the loss class is the usual reference: B35A270 corresponds to GB/T 35W270, EN M270-35A and JIS 35A270. We confirm the equivalent with the current Baosteel data before quoting.
Send us the motor type, operating frequency, lamination drawing and annual quantity, and we will suggest grades and a processing route from strip to finished core.
