Application of custom inductors in New Energy Electric Motor Drive Systems

2026-08-10

In the motor drive system of new energy vehicles, there is a seemingly insignificant but crucial component - customized coils. If the power battery is the heart of an electric vehicle, the drive motor is the muscle, then the coil is the tendon in the muscle, responsible for precisely converting electrical energy into mechanical energy that drives the vehicle forward. In today's evolution of the motor drive system towards higher power density, higher efficiency, and higher reliability, standardized and universal coils have been unable to meet the strict requirements of complete‑vehicle manufacturers. Customized coils are becoming the core technical lever in the hands of engineers.

Stator coils: The "last mile" of electromagnetic energy conversion

New energy vehicles widely adopt permanent magnet synchronous motors or induction asynchronous motors as power sources. Regardless of the type, the stator coil is the direct carrier of electromagnetic energy conversion. When three-phase alternating current is introduced into the stator coil, a rotating magnetic field is generated, driving the rotor to rotate, thereby outputting torque.
The winding method of the coil directly determines the final performance of the motor. The copper filling rate of the coil directly affects the power density - the traditional circular copper wire winding has a filling coefficient of only about 45%, and copper loss can account for more than 30% of the total loss of the motor. This means that if the coil design is not appropriate, a considerable amount of electrical energy will be converted into useless heat rather than power.
To break through this bottleneck, customized coil technology emerged.

The triple value of customized coils: Performance, efficiency, and reliability

1. Enhance power density, evolve towards "small volume, large power"
The most obvious value of customized coils lies in the leap in power density. By replacing the traditional circular copper wire winding with flat copper wire hairpin winding, the filling coefficient can be increased from 45% to over 60%, achieving higher power output within the same volume.
Furthermore, some cutting-edge technologies are breaking through the physical limits. German Additive Drives Company uses 3D printing additive manufacturing technology to manufacture stator windings, achieving a perfect geometric match between the copper conductor shape and the trapezoidal groove. The copper filling rate of each groove is significantly higher than that of traditional winding processes, and each wire is in thermal contact with the iron core, effectively eliminating hot spots. This "geometric perfect match" coil allows designers to no longer compromise between performance and efficiency.
Flexible substrate printed winding is another technical path. By printing winding patterns on flexible substrates, a volume reduction of up to 50% compared to traditional winding methods can be achieved.

2. Reduce losses, improve system efficiency from the source
The skin effect and proximity effect under high-frequency conditions are the main sources of AC losses. Customized coils can significantly reduce these losses through flat wire design and precise winding arrangement. With the flat copper wire hairpin winding design and automated precision winding equipment, the efficiency of an industrial servo motor can be increased by approximately 5%.
In addition, customized coils can further improve the overall efficiency of the motor through distributed winding topology optimization, reducing harmonic interference. In the application of electric vehicles, every bit of efficiency improvement means an extension of the range and a reduction in battery costs.

3. Meet automotive-grade reliability, cope with extreme conditions
Cars are "mobile extreme environment laboratories". The coil of the drive motor needs to work stably and long-term within a wide temperature range of -40°C to +150°C, withstanding vibration, salt fog, and erosion from coolant/lubricating oil.
Customized coils address these challenges through targeted optimization of material systems and processes. In terms of high-temperature tolerance, a "organic-inorganic" double-layer protective structure with a polyimide film (Kapton) base insulation layer and a nano-aluminum oxide ceramic coating can achieve a heat resistance level of H class (above 180°C), reducing dielectric loss by 30%, and extending the insulation life to over 10 years. At the technical level, the self-adhesive wire hot air shaping process can achieve a compact coil structure and ensure dimensional consistency; the vacuum impregnation process can enhance the moisture-proof and insulation performance. High-quality custom coil products can control the DC resistance (DCR) consistency within ±2%, and the CPK (Process Capability Index) of inductance quantity reaches above 1.67, and are delivered through the complete PPAP (Production Part Approval Process) Level 3 documents.

From "usable" to "user-friendly": Engineering practice of custom coils

The value of custom coils has been verified in actual engineering. In the electric power steering (EPS) motor, the low tooth-slot torque and high response speed characteristics of custom coils directly affect the driving feel and safety. In the electronic water pumps and oil pumps of the thermal management system, the corrosion resistance and insulation performance of custom coils ensure the long-term reliable operation of core components.
The other side of customization is the ultimate requirement for manufacturing capabilities. The production of high-precision custom coils relies on brands like Jidai's fully automatic winding machines, with equipment repeatability accuracy reaching 0.001mm. Combined with the lean production "one-piece flow" mode, it ensures that the quality of each product can be traced.

Future trends: Evolving towards higher integration and more extreme efficiency

The development direction of custom coils is highly consistent with the core demands of the new energy vehicle industry. The rise of axial flux motor technology has raised higher requirements for the geometric customization ability of coils - their stators need to have customized slot layout designs for flat wires or braided windings.
At the same time, new manufacturing processes such as 3D printed copper coils and flexible printed coils are gradually maturing, opening up unimaginable freedom for motor design: arbitrary geometric shapes, precise copper filling, conformal heat dissipation channels...

Custom coils are no longer "optional", but have become the "standard" for the high-performance motor drive system of new energy vehicles. It is the most critical link in converting electromagnetic principles into actual driving force - hidden in the stator slots, but determining the power performance and energy efficiency level of the entire vehicle. For new energy vehicles that pursue ultimate performance and reliability, the customization design capability of coils is becoming the core technical moat for the entire vehicle manufacturers and Tier 1 suppliers.

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