flat wire motors in ev

Why Flat Wire Motors Are The Future Of New Energy Vehicles?

The rapid evolution of the automotive industry towards sustainability and efficiency has led to a burgeoning interest in new energy vehicles (NEVs). Among the myriad technological advancements driving this transition, the adoption of Hairpin flat wire motors stands out as a pivotal development. In this blog, we delve into the intrinsic superiority of flat wire motors over their traditional round wire counterparts, exploring their mechanisms, advantages, and burgeoning potential in shaping the landscape of NEVs.

What is Flat Wire Motor?

Flat wire motors, also known as pancake motors or axial flux motors, are a type of electric motor characterized by their flat, disc-like shape. They consist of a stator and a rotor, with the windings typically arranged in a pancake configuration, sandwiched between the stator and rotor.

A flat wire motor refers to a motor in which the traditional cylindrical enamel-coated copper wires in the stator winding are replaced with enamel-coated copper flat wires processed into hairpin shapes.

what is flat wire motor

Advantages of Flat Wire Motor

High Slot Fill Factor

One of the defining features of flat wire motor is their remarkable slot filling rate. Unlike round wire motors, which typically exhibit a slot fullness of about 40%, flat wire motors soar beyond 60%. This enhancement translates into a denser arrangement of copper conductors within the motor’s stator slots, thereby amplifying magnetic field strength and bolstering motor power density.

High Power Density and Efficiency

Central to the allure of flat wire motor is their exceptional power density and efficiency. By capitalizing on their augmented slot fill rate, these motors can deliver greater power output within the same or even smaller volume and weight parameters compared to round wire counterparts. Such advancements hold profound implications for NEVs, promising heightened performance and extended mileage while minimizing spatial and cost constraints.

Improved Heat Dissipation

Flat wire motors exhibit superior heat dissipation due to the tighter contact between the coil windings. Research shows a remarkable 10% reduction in temperature rise compared to round wire motors.

Moreover, at high slot fill factors, the thermal conductivity between windings increases by 150% compared to low slot fill factors, further enhancing heat dissipation performance. This improved thermal management makes flat wire motors ideal for applications demanding efficient cooling and reliable operation.

Noise Reduction and Comfort

The elevated slot fullness of the flat wire motor engenders smoother operation, mitigating vibrations and reducing noise levels. This attribute is particularly pronounced under varying operational conditions, where the motor’s ability to sustain high torque at low speeds or low torque at high speeds ensures a serene driving experience, resonating with the ethos of NEVs.

flat wire motor and round wire motor in ev

Mechanics of Flat Wire Motors

Enhanced Slot Fill Rate

At the heart of the superior performance of flat wire motors lies their distinctive utilization of flat rectangular wires. Unlike their circular counterparts, flat wires enable a seamless packing of conductors within the stator slots, eliminating gaps and maximizing slot fullness.

Consequently, the resultant increase in magnetic flux density augments the motor’s torque generation capabilities, epitomizing the essence of power density.

Mitigation of Pierce Loss

Another key advantage conferred by flat wires is the attenuation of Pierce loss within the winding. Owing to their reduced cross-sectional area and amplified circumferential exposure to the winding axis, flat conductors curtail the incidence of eddy currents induced by alternating magnetic fields.

This mitigation translates into diminished energy dissipation, further bolstering the efficiency and longevity of the flat wire motor.

Application of Flat Wire Motors In New Energy Vehicles

Initially confined to high-power motors and generator sets in industrial settings, flat wire motor has witnessed a notable expansion into the automotive realm. The burgeoning new energy automobile industry has spurred the integration of the flat wire motor into various vehicular applications.

From automotive generators and starters to EPS (electric power steering) motors, main drive motors, and P2 (parallel hybrid) system motors, the versatility of flat wire motors is showcased across a spectrum of automotive functionalities. 

Among several mainstream directions of EV motor development, flat wire motor is more and more predominating the development advancement. Currently, there are increasing numbers of vehicle models using flat wire winding motor, including Tesla Model 3/Model Y, BYD Qin PLUS DMI, Toyota Prius, Volkswagen ID4, and others.

Development Potential of Flat Wire Motors

The ascendancy of flat wire motors from industrial applications to the realm of NEVs underscores their burgeoning prominence as a cornerstone of automotive propulsion systems.

With leading automotive brands embracing flat wire technology, the empirical validation of its efficacy heralds a paradigm shift in the trajectory of NEV development.

Beyond mere theoretical conjecture, flat wire motors have emerged as a tangible solution capable of enhancing automotive performance, curtailing costs, and ameliorating environmental footprints.

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In conclusion, through their intrinsic advantages of heightened slot fill rates, enhanced power density, and reduced operational noise, flat wire motors epitomize the quintessence of progress in NEV propulsion technology.

As automotive landscapes evolve, embracing the transformative potential of flat wire motors is not merely an option but an imperative, heralding a greener, more efficient future for vehicular transportation.


How Do Flat Wire Motor Differ from Round Wire Motor?

The primary difference lies in the shape of the wire used. Flat wire motor utilizes flat rectangular wires, enabling higher slot filling rates and, consequently, enhanced performance compared to the cylindrical wires used in round wire motor.

Are Flat Wire Motor More Expensive Than Round Wire Motor?

While flat wire motor may have a slightly higher initial cost due to their specialized construction, their long-term benefits in terms of energy efficiency and performance often outweigh the initial investment.

What Makes Flat Wire Motor Suitable for New Energy Vehicles?

The inherent advantages of flat wire motor, such as their superior power density and efficiency, align closely with the requirements of new energy vehicles. Their ability to deliver high performance in a compact and energy-efficient package makes them an ideal choice for NEV propulsion systems.

Are There Any Limitations to Flat Wire Motors?

While flat wire motors offer numerous advantages such as increased power density and efficiency, they may face limitations in applications requiring extreme operating conditions or specialized requirements. Factors such as temperature sensitivity and limited availability of flat wire materials could pose challenges in certain scenarios.

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