China’s new‑energy vehicle market is gradually shifting from policy‑driven to market‑driven. In the coming years, market demands for new‑energy motors will move toward high power density, high efficiency and platform‑based development. Hair‑pin drive motors represent a solution that perfectly matches such development trends. Founder Motor has made substantial investment in hair‑pin motor technology, achieving rapid development and establishing a leading position in the industry.

Founder’s platform‑based hair‑pin motor adopts an 8‑layer hair‑pin conductor structure. Each production procedure can be fully automated by dedicated equipment, delivering good product consistency and high production efficiency with an annual production capacity of 150 000 sets.

Figure 1: Founder Hair‑pin Motor Production Equipment

The windings of hair‑pin motors are neatly arranged inside stator slots with a high slot fill factor; the pure‑copper slot fill factor reaches 70 %, improving motor torque output and heat dissipation performance. The rotor adopts a dual‑V magnet configuration for higher magnet utilization, boosting motor torque and power capability. Laser welding is applied to the PIN terminals of the hair‑pin stator, forming full, smooth solder joints with high welding strength, high efficiency and excellent joint consistency.

Figure 2: Winding Arrangement

Figure 3: Laser‑welded PIN Terminals

Hair‑pin motors feature compact size, light weight and high power density. The stator core outer diameter of Founder’s hair‑pin motor is 220 mm, with eight conductors per slot and C‑type insulating paper. The windings adopt planetary connection with four parallel branches, and the neutral point is connected via a bus ring, delivering compact structure and high reliability.

Figure 4: Overall Dimensions of Hair‑pin Motor

Figure 5: Exploded View of Hair‑pin Motor

The hair‑pin motor delivers outstanding output performance. This Founder hair‑pin motor achieves peak performance of 350 Nm / 170 kW and continuous performance of 150 Nm / 65 kW.

Its maximum motor efficiency reaches 97.5 %, and average NEDC efficiency exceeds 94 %.

Figure 6: Efficiency Comparison between Hair‑pin Motor and Round‑wire Motor

To sum up, Founder’s hair‑pin motor features obvious technical advantages, which are summarized as follows:

1. High slot fill factor: typically above 70 %. A higher slot fill factor effectively increases motor power density and improves heat dissipation inside stator slots.

2. Superior heat‑dissipation capability: besides lower heat generation at medium‑low speeds caused by reduced AC resistance of hair‑pin conductors, hair‑pin stators reduce thermal resistance within stator teeth compared with round‑wire stators for better thermal conduction.

3. Enhanced power and torque capacity: benefiting from lower heat generation and better heat dissipation, the thermal load of stator windings can be appropriately raised in electromagnetic design, leaving more space for the rotor. With stator temperature kept comparable to that of round‑‑wire stators, the rotor outer diameter can be enlarged to improve peak output capability.

4. Compared with round‑‑wire winding motors, hair‑pin winding motors show greater efficiency advantages at low‑speed conditions, making them better suited to vehicle requirements under Chinese urban driving cycles.