Driven by the dual forces of global energy transformation and industrial intelligence, the motor industry is experiencing unprecedented development opportunities. Surges in demand for new energy vehicle motors, high-speed industrial motors, and precision servo motors are driving rapid advancements in motor technology toward higher frequencies, higher efficiency, and smaller sizes.
However, traditional magnetic materials such as silicon steel and ferrite are increasingly showing limitations in meeting the performance requirements of high-frequency, high-efficiency motors. Silicon steel exhibits significant increases in core loss under high-frequency conditions, resulting in reduced motor efficiency. While ferrite exhibits lower high-frequency losses, its magnetic permeability is insufficient, making it difficult to meet the demands of precision control scenarios.
Against this backdrop, nanocrystalline cores, with their unique magnetic properties, have become a key solution to overcome the bottlenecks of traditional materials and drive the advancement of motor technology. A deeper understanding of the application value of nanocrystalline cores in motors is crucial for improving motor system performance and supporting the development of new energy and high-end manufacturing industries.
Magnetic materials are the core carriers of energy conversion and signal transmission in motors. Their performance directly determines the motor's efficiency, reliability, and control accuracy. They play three main roles:
Magnetic conductivity: They create a stable magnetic circuit, ensuring efficient conversion of electrical energy into mechanical energy and providing the foundation for the motor's power output.
Interference suppression: They filter electromagnetic noise generated during motor operation, reducing interference with surrounding electronic components and the power grid.
Loss reduction: By optimizing hysteresis and eddy current losses, they reduce energy waste during motor operation and improve energy efficiency.
As motors evolve toward higher frequencies and greater intelligence, traditional magnetic materials are increasingly unable to meet these demands:
High-frequency losses: Eddy current losses in silicon steel sheets increase dramatically at frequencies exceeding 1kHz, leading to excessive motor temperature rise and shortened lifespan.
Insufficient magnetic permeability: The magnetic permeability of ferrite is typically less than 1000, making it difficult to achieve precise current and magnetic field regulation in applications requiring high-precision magnetic circuit control, such as precision servo motors.
Limited adaptability: Traditional materials struggle to simultaneously achieve high frequency, low loss, and high permeability, failing to meet the dual requirements of "high efficiency and compactness" for new energy vehicle motors.
Nanocrystalline cores are made of an iron-based nanocrystalline alloy. Their microstructure consists of nanoscale grains (typically 5-20 nm in size). This unique structure imparts exceptional magnetic properties, primarily in the following three areas:
The initial permeability of nanocrystalline cores can reach 50,000-100,000, significantly higher than that of silicon steel sheets (initial permeability approximately 3,000-8,000) and ferrite (initial permeability approximately 1,000-5,000). This high permeability means that under the same magnetic field strength, nanocrystalline cores can generate stronger magnetic induction intensity, significantly reducing the size of the motor's magnetic circuit and facilitating miniaturization.
At high frequencies (1 kHz-1 MHz), nanocrystalline cores exhibit significantly lower iron losses than traditional materials. Taking a frequency of 10kHz as an example, the specific loss (loss per unit mass) of nanocrystalline cores is typically less than 0.5W/kg, compared to 5-10W/kg for silicon steel sheets of the same grade, and approximately 1-3W/kg for ferrite. This wide-band, low-loss characteristic makes it suitable for high-frequency motor operation, significantly improving motor energy efficiency.
Nanocrystalline cores offer excellent magnetic shielding and noise absorption capabilities, effectively suppressing common-mode and differential-mode interference generated by pulse-width modulation (PWM) signals in motor drive systems. In new energy vehicle motors, the use of nanocrystalline cores can reduce EMI emissions by 20-30dB, meeting stringent electromagnetic compatibility standards such as ISO 11452.
|
Property |
Silicon Steel |
Ferrite |
Nanocrystalline Cores |
|
Initial Permeability |
3,000 - 8,000 |
1,000 - 5,000 |
50,000 - 100,000 |
|
Core Loss @ 10kHz |
5 - 10 W/kg |
1 - 3 W/kg |
< 0.5 W/kg |
|
EMI Suppression |
Fair |
Moderate |
Excellent |
|
Operating Temperature |
-40°C to 150°C |
-20°C to 120°C |
-50°C to 180°C |
|
Density |
7.6 g/cm³ |
4.5 g/cm³ |
7.2 g/cm³ |
nanocrystalline cores do not directly replace traditional magnetic materials in motor stators/rotors. Instead, they play a key supporting role in motor systems. Their primary applications include the following four categories:
Nanocrystalline common-mode chokes (NCCCHs) are core components at the input and output of motor controllers. They filter common-mode interference signals between the motor and the power grid, preventing interference from propagating through the power lines to other electronic devices. They also protect the motor controller from grid voltage fluctuations. For example, in new energy vehicle motor controllers, NCCs effectively suppress high-frequency interference generated by IGBT switching.
In motor drive circuits, NCCs are used to reduce the harmonic components of PWM drive signals, making the motor input current more sinusoidal and reducing losses in the motor windings caused by current harmonics. Furthermore, NCCs can be used for isolated power supply to motor controllers. Their high-frequency, low-loss characteristics improve power conversion efficiency and reduce controller temperature rise.
In precision servo motors and new energy vehicle motors, current transformers (CTs) are used to measure motor winding current in real time, providing accurate current feedback to the control system. Nanocrystalline CT cores, with their high magnetic permeability and low coercivity, enable high-precision detection (typically with an error of less than 0.5%) over a wide current range, helping motors achieve refined torque control.
For high-speed motors exceeding 10,000 rpm (such as aviation cooling motors and data center fan motors), researchers are exploring the use of nanocrystalline cores in auxiliary magnetic circuits. This aims to reduce eddy current losses generated by stator slots during high-speed rotation. Currently, laboratory studies have achieved a 3-5% increase in motor efficiency, with potential for industrial application in the future.
New energy vehicle motors have extremely high requirements for efficiency, EMC performance, and reliability. Nanocrystalline cores are already used in the motor drive systems of vehicles such as the Tesla Model 3 and BYD Han to create common-mode inductors and filter inductors. Application Effect: Compared to traditional silicon steel inductors, nanocrystalline inductors reduce EMI emissions from motor drive systems by 25dB while reducing inductor volume by 30%, helping to increase vehicle range by 5-8km.
Added Value: The wide operating temperature range (-50-180°C) of the nanocrystalline core allows it to withstand both high and low-temperature operating conditions in vehicles, improving the environmental adaptability of the motor system.
In aerospace, data centers, and other fields, high-speed motors (20,000-100,000 rpm) are widely used for cooling and boosting. For example, the use of nanocrystalline filter inductors in an aircraft engine cooling motor resulted in:
Reduced High-Frequency Losses: At a drive frequency of 50kHz, the motor's core losses were reduced by 40%, and the temperature rise was reduced by 15°C.
Improved Stability: The impact of high-frequency harmonics on motor bearings was reduced, extending the motor's lifespan by more than two times.
Precision servo motors are used in high-end equipment such as CNC machine tools and robots, and they place stringent requirements on current sensing accuracy and control response speed. After a domestic servo motor manufacturer adopted nanocrystalline CT cores in its 220V series products, the results were:
Improved detection accuracy: Current detection error was reduced from 1.2% to 0.3%, increasing motor positioning accuracy to ±0.001mm;
Fast response speed: Core hysteresis was reduced, shortening the motor's dynamic response time by 20%, meeting high-speed machining requirements.
In addition to the aforementioned property comparison, from the perspective of motor system applications, nanocrystalline cores differ from silicon steel and ferrite in the following dimensions:
Silicon steel sheets: Primarily used in the main magnetic circuit of the motor stator and rotor, suitable for medium- and low-frequency (<1kHz) high-power motors (such as industrial traction motors), but performance degrades significantly under high-frequency conditions.
Ferrites: Suitable for the auxiliary magnetic circuit of high-frequency, low-power motors (such as household fan motors), but have low magnetic permeability and are brittle, making them difficult to adapt to high-vibration conditions.
Nanocrystalline cores: Focus on the high-frequency auxiliary links (filtering, detection, and anti-interference) of motor systems, suitable for high-frequency, high-precision, and high-reliability applications, providing a complementary solution to traditional materials.
Cost: The unit price of a nanocrystalline core is approximately 5-8 times that of silicon steel and 3-5 times that of ferrite. However, due to its compact size and high efficiency, the overall cost of the motor system only increases by 5-10%, and it can also achieve long-term benefits through energy savings.
Process: Nanocrystalline cores are made using amorphous alloy rapid solidification and annealing process. While the production process is relatively complex, it is highly automated, and there is room for cost reduction after mass production.
With the advancement of motor technology and downstream industry demand, the application of nanocrystalline cores in motors will show three major trends:
In the future, motors will be deeply integrated with controllers and sensors to form an integrated "motor-electronic control-magnetic component" module. Nanocrystalline cores can be integrated into the motor controller's PCB, achieving multifunctional integration of the "inductor-transformer-CT" component, further reducing the size of the motor system and improving its integration density. For example, flat-wire motors for new energy vehicles have begun experimenting with this integrated design, and it is expected to become increasingly common after 2025.
According to industry forecasts, the global high-frequency motor (>10kHz) market will exceed 50 billion yuan by 2030, primarily driven by new energy vehicles, aerospace, data centers, and other sectors. The demand for low-loss magnetic materials in high-frequency motors will directly drive the nanocrystalline core market to maintain growth rates exceeding 20%, making it a hot growth area in the magnetic materials sector.
To address the performance requirements of both the main and auxiliary magnetic circuits, researchers are exploring "nanocrystalline + silicon steel" and "nanocrystalline + ferrite" composite magnetic materials. For example, laminating nanocrystalline ribbons with silicon steel sheets to form motor stators can reduce high-frequency losses in the main magnetic circuit by 30%. Applying a nanocrystalline coating to the surface of ferrite can improve its magnetic permeability and impact resistance. These composite materials are expected to enter industrialization between 2026 and 2030.
Although nanocrystalline cores are not a mainstream material for the main magnetic circuit of motors, they play a crucial role in improving motor system performance. Their high-frequency, low-loss, high-permeability, and strong EMI suppression precisely address the pain points of traditional materials in high-frequency, high-efficiency, and high-precision motors, providing core support for technological upgrades in new energy vehicle motors, high-speed industrial motors, and precision servo motors.
From a practical perspective, nanocrystalline cores not only reduce motor energy consumption and improve control precision, but also reduce system size and enhance environmental adaptability. They are a crucial material foundation for driving the development of motors towards higher efficiency, miniaturization, and intelligence.
In the future, with the deepening trend of motor and electronic control integration and the widespread adoption of high-frequency motors, the application scenarios of nanocrystalline cores will further expand. Industry companies are advised to increase R&D investment, break through low-cost production processes, and explore innovative approaches such as composite magnetic materials. This will allow nanocrystalline cores to play a valuable role in more high-end motor applications, contributing to global energy efficiency improvements and industrial manufacturing upgrades.