The Difference Between I-pin, Hair-pin, X-pin and S-winding

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2023-06-16 13:50

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Flat wire motors are currently the mainstream form of motor windings. Compared with round wires, flat wires are conducive to the improvement of motor slot fill rate. Generally, the slot fill rate of round wire motors is about 50%, while the slot fill rate of flat wire motors Can reach more than 70%. The improvement of slot fullness means that under the condition of constant stator slot space, more copper wires can be filled, and a larger current can be passed to generate a stronger magnetic field, thereby increasing the power density.

The winding forms of flat wire motors mainly include I-pin, Hair-pin, X-pin, and S-winding. The following is an introduction to the four types of flat wire windings:

I-pin

The I-Pin winding is shaped like an I, directly plugged in, and then welded on both sides. No need for performing single-slot assembly, which can further reduce the reserved space for winding assembly. The disadvantage is that the welding process is cumbersome and the end size is large.

Hair-pin

The Hair-pin winding is shaped like a hairpin. It is formed first, then plugged in, and then welded on one side. It is the most widely used flat wire winding form.

X-pin

The X-pin winding is mainly optimized at the soldering end.

Compared with I-pin: the welding ends at both ends are shortened, and the copper loss is reduced, but the number of solder joints has not changed, and double-sided welding is still required. The welding process has higher requirements, and there is a risk of welding quality.

Compared with the Hairpin process: the size of the plug-in end does not change, and the size of the welding end can be reduced by 5-10mm, which further reduces the copper loss of the motor and improves the efficiency of the motor.

S-Winding

The shape of S-winding winding is S-shaped, after forming, the ends of both ends do not need to be welded, and the size of the end space is smaller, more excellent NVH performance, reducing torque ripple to achieve smoother operation and better performance cooling effect.

The above is the learning summary of the four flat wire windings of I-pin, Hair-pin, X-pin, and S-winding. The comparison of the end size, copper loss, and production process difficulty is as follows:

Process Comparison	I-pin	Hair-pin	X-pin	S-winding
End Size	High	Middle	Low	Low
Copper Loss	High	Middle	Low	Low
Difficulty of Production Process	Low	Middle	High	High

Different technical routes have a great impact on production equipment and processes. The winding production steps are roughly divided into: plug, wire forming, twisting, cutting, welding, etc. Hair-pin is moderately difficult in each step of the production process, while S-winding is extremely difficult in the online forming process, but it has advantages in terms of welding and end height.

The current technical route is still dominated by the hair-pin process technology route, I-pin is represented by Bosch, and S-winding is represented by BorgWarner.

HONEST has successful cases in I-pin, Hairpin and X-pin motor winding and assembly equipment, and has achieved mass production for leading automotive companies. We can provide customers with customized automation equipment solutions, including semi-automatic and fully automatic. Welcome to consult!

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