new energy vehicle motors iron core materials

Five Technological Routes: Iron Core Materials For New Energy Vehicle Motors

As the automotive industry continues its transition towards sustainable energy solutions, the development of electric vehicles (EVs) has become a focal point. Within the realm of EVs, the efficiency and performance of electric motors play a crucial role. At the heart of these motors lie core components known as iron cores, which significantly impact their overall performance and cost. In this blog post, we delve into the advancements in high-performance iron core materials for new energy vehicle motors, exploring five key technological routes driving innovation in the era of high power density.

Iron Core: The Core Component of Motors

The iron core is a vital component influencing the performance of electric motors, constituting approximately 30% of the motor’s cost. Electric motors, serving as crucial devices for electro-mechanical energy conversion, stand as the primary power source for most industrial equipment.

motor components

The electric vehicle motor lamination core plays a crucial role in converting electrical energy into mechanical energy by maintaining a stable magnetic circuit. When the current passes through the coils of the motor, the resulting magnetic field creates a magnetic flux in the iron core. 

By minimizing magnetic flux loss through efficient design and material selection, such as adopting a laminated or stacked structure, the core enhances motor efficiency. This design reduces eddy current loss, increases magnetic resistance, and facilitates efficient transmission of the magnetic field between the rotor and stator.

From an electronic cost perspective, while electric motors come in numerous specifications and types, their structures are generally similar, mainly consisting of stators, rotors, windings, and other components such as end caps and bearing caps. The stators and rotors, as core components, collectively account for 30% of the total cost.

Benefiting from the thriving development of downstream new energy vehicles, the automotive industry’s demand for drive motor iron cores is rapidly increasing.

According to QY Research, the market size of automotive motor iron cores in China was estimated to reach $550 million in 2022, expected to rise to $600 million by 2023 and potentially reach $1.3 billion by 2029, with a CAGR of 13.74% from 2023 to 2029.

Overall, the Chinese automotive motor lamiantions industry is on an upward trajectory, driven by the rapid expansion of the downstream new energy vehicle market, indicating vast potential in demand for automotive motor iron cores in the future.

Arrival of the High Power Density Era: Opening Doors to New Opportunities for Motor Iron Core Materials

With the advent of the high power density era, a new opportunity arises for innovative electric motor core materials as various emerging end markets such as new energy vehicles and photovoltaic energy storage demand higher power output and space efficiency.

Taking the new energy vehicle sector as an example, power converters, as one of the core components of automotive traction motors, play a crucial role in converting the direct current from batteries into corresponding voltage levels of direct current, alternating current, or pulse power required by selected electric motor drive currents.

High power density motors offer advantages such as lightweight, high efficiency, and effective reduction of vehicle energy consumption to meet various dynamic requirements of automobiles.

Materials Analysis

The material of the stator and rotor iron core is crucial in determining the performance of the drive motor and hub motors. Compared with traditional silicon steel sheet motors, amorphous motors exhibit significant advantages in power density and high-efficiency energy conservation.

Traditional motor iron core materials primarily consist of silicon steel sheets. In comparison, amorphous alloys have lower density, thinner thickness, smaller volume, and lighter weight than silicon steel sheets, while also possessing characteristics such as high magnetic permeability, high resistivity, low loss, and low coercivity.

Properties Analysis

However, the physical properties of amorphous alloy materials, such as thinness, brittleness, and hardness, make them sensitive to processing technology, leading to difficulties in processing amorphous stator iron cores into complex shapes, posing certain challenges for industrialization.

In principle, under the same power and speed, the smaller the volume and weight of the motor, the higher the power density can be achieved through high-frequency operation.

At medium and high frequencies, the iron loss of amorphous alloys is only equivalent to 1/8 to 1/10 of that of ordinary silicon steel sheets, and the trend becomes more pronounced as the frequency increases. The low iron loss enables energy-efficient operation of the motor.

Application Analysis

In specific applications, in March 2023, AIan released a new generation of high-performance integrated electric drive technology group—Quark Electric Drive. The motor iron core adopts nanocrystalline-amorphous materials, achieving a motor power density of 12 kW/kg, doubling the industry average of 6 kW/kg.

Simultaneously, reducing the iron core loss of the motor by 50% effectively cuts down motor energy loss, while increasing motor operating efficiency to 97.2%, with a maximum efficiency reaching 98.5%.

In October, Alan’s luxury brand HaoBo SSR supercar was launched and began delivery, equipped with amorphous motors. Its zero-to-hundred acceleration of just 1.9 seconds has elevated electric supercar performance to new heights.

CharacteristicSilicon SteelAmorphous Alloy
Grade35W470Metglas2605SAI
Thickness(mm)0.350.03
Iron Loss(W/kg | 400Hz)7.60.45
Saturation Magnetisation Value(T)1.71.54
HardnessHV 100-200HV900
Motor StructureRadial magnetic fieldTransverse magnetic field
Metal StructureAtomic orderingAtomic disorder

Iron Core Materials Type In New Energy Vehicle Motors

Apart from amorphous alloys, other commonly used high-performance iron core materials in the market include 6.5% Si high silicon steel, cobalt-iron, nickel-iron, and metal soft magnetic powder cores, each with its own advantages and disadvantages.

6.5% Si High Silicon Steel

Besides reducing thickness, as silicon content increases, the hysteresis stretching coefficient of silicon steel decreases, reducing iron loss and increasing magnetic permeability. When the silicon content reaches 6.5%, the magnetic permeability of silicon steel reaches its maximum value, demonstrating excellent magnetic properties.

However, 6.5% Si high silicon steel is brittle in texture with extremely poor processing performance, making it difficult to prepare using conventional rolling methods. In terms of application, 6.5% Si high silicon steel is considered an ideal iron core material for high-frequency motors.

Cobalt-Iron

By alloying with iron, cobalt achieves extremely high saturation magnetization at room temperature. However, due to the high cobalt content, cobalt-iron is usually expensive.

Its typical applications include onboard motors, oil field motors, and specialized motors for racing and hybrid power systems.

Nickel-Iron

Composed mainly of nickel and iron, with additional impurities such as chromium, silicon, sulfur, phosphorus, and carbon, nickel-iron boasts high magnetic permeability and low coercive force but has limitations in saturation and maximum flux density.

In applications, nickel-iron finds primary utilization in motors with low loss requirements, such as dental and surgical instruments, as well as in low-loss aerospace applications.

Metal Soft Magnetic Powder Cores

By uniformly dispersing magnetic particles in non-magnetic materials, these cores can reduce high-frequency eddy current losses, increase application frequency, and offer advantages such as small density, light weight, high production efficiency, low cost, and good product repeatability and consistency.

However, due to the separation of magnetic particles by non-magnetic substances, magnetic circuits are partially interrupted. In application, metal soft magnetic powder cores can serve as stator iron core materials for axial flux motors.

Materials Compared Table

MaterialsAdvantagesLimitationsMotor Application
6.5% Si High Silicon Steel(Super Steel)The silicon content is as high as 6.5%, the iron loss is reduced, and the magnetic permeability reaches the maximum valueThe texture is brittle, the processing performance is extremely poor, and it is difficult to mass productionHigh frequency motor
Cobalt-IronHigh saturation magnetizationHigh costOnboard motor
Nickel-IronHigh magnetic permeability, low coercivityLow saturation strength and low maximum magnetic flux densityLow energy consumption motor
Metal Soft Magnetic Powder CoresSmall density, light weight, high production efficiency, low cost, good product repeatability and good consistencyThe magnetic particles are separated by non-magnetic bodies, and the magnetic circuit is partially cut offAxial flux motor

Lamnow Electric Vehicle Motor Laminations Capabilities

Lamnow has over a decade of experience in lamination core for motor design and manufacturing. Our factory has multiple high-speed punching machines, welding machines, automation glue bonding machines, injection moulding machines, coating machines, and automation winding machines.

We offer customized high performance the motor rotor and stator laminations for electric vehicles, elevator traction, rail transportation, power tools, home appliances, robotics, drones, renewable energy, and industry. The materials of electric motor laminations include silicon steel, amorphous alloys, soft magnetic composite materials, nickel alloy, and cobalt alloys.

Whether you need a large motor lamination, small motor lamination stack, segmented motor lamination, adhesive motor core, or axial flux motor lamination, our comprehensive solutions can meet your needs.

Conclusion

With the increasing demand for higher efficiency and power density, new electric motor core materials may replace some shares of silicon steel sheets.

By optimizing alloy formulations, improving preparation processes, and controlling grain structures and magnetic domain behaviors, it is possible to enhance core material magnetization, reduce hysteresis losses and eddy current losses, thereby improving motor efficiency and power density.

As electric motor technology continues to evolve, with stricter efficiency requirements, we anticipate an increasing proportion of high-strength, high-frequency, low-iron-loss iron core materials for new energy vehicle motors, potentially replacing some shares of silicon steel sheets.

This trend underscores the demand for higher performance and more reliable motor systems.

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