Electric vehicle hairpin motor technology

With the continuous changes in the transportation industry and the advancement of vehicle electrification worldwide, stators using card-issuing technology are widely used in the manufacturing of electric drive motors (traction motors) for electric vehicles (including passenger cars and commercial vehicles). Card-issuing technology become increasingly important.

Hairpin technology is a winding process, but it is different from the traditional copper wire coil manufacturing method. It uses copper strips inserted into the stator laminations and is made of enamelled copper wire with a layer of varnish. These U-shaped pins that plug into the coil resemble classic hairpins. Because the cross-section of the copper wire is relatively flat, the slot fill rate of the hairpin can be higher, thereby increasing the power density. In addition, high slot fullness also brings better thermal performance and NVH performance.

Hair-pin twists are shaped like hairpins. It is first formed, then inserted, then welded on one side. It is the most widely used form of flat wire winding. 

Hairpin motor stator manufacturing includes the following processes:

1. Line forming

2. Insert paper

3. Plug in the wire

4. Expansion

5. Turn your head

6. Soldering and interconnection

Hair-pin uses hot melt welding, and a solder ball is formed at the end. The heat-affected area is large, generally around 8-10mm², the welding area is 110% of the cross-sectional area, and the pull-out force is generally around 800-1000N.

7.Insulation treatment

Hair-pin uses impregnation paint + coating process to ensure insulation performance and strength.

Ningbo Nide Mechanical Equipment Co., Ltd. focuses on motor manufacturing solutions, providing hairpin motor manufacturing equipment to customers in many countries around the world, and providing customers with large-scale hairpin motor production lines. By using open coil segments prefabricated with rectangular cross-section wires and a high degree of automation, motor hairpin technology produces high-quality stators with higher filling rates.