The development trend of new energy vehicle motors: the replacement of flat wire (hairpin wire) motors for round wires is accelerating
According to the current development trend of new energy vehicles, the placement of flat wires for round wires is accelerating. Compared with the traditional round wire motor, the flat wire (hairpin wire) motor owns a great advantage above it. At present, new energy vehicles are in a period of rapid development, product quality is rapidly improving, and consumers have higher and higher requirements for performance. Flat wire motor is a winding technology with complicated manufacturing process and currently has a high technical premium. The so-called flat wire motor refers to the change in the shape and structure of the wires used in the stator winding design, from multiple thin round wires to thick rectangular wires, commonly known as flat wires.
The advantage of flat wire motor
1. High-efficiency conversion of flat-wire motors saves battery costs. Flat wire motors can greatly improve conversion efficiency and reduce battery costs. The cost savings of 1,000 yuan per vehicle is of great significance to car companies. Under the circumstance that the cost of new energy vehicles and power batteries is still too high, how to reduce costs is the eternal pursuit of car companies, and how to improve the efficiency of motors is one of the effective ways to reduce costs.
2. The flat wire motor is small in size and uses less material under the same power, or with the same volume, the slot full rate is improved, and the power density is continuously improved. The full rate of round wire grooves is about 40%, and the full rate of flat wire grooves can be increased to about 70%. Since the cross section of the round wire is circular, there are some irregular structural gaps between the wires, while the gap of the flat wire is small and the slot full rate is high.
3. High Power Density Makes Vehicles More Powerful. The power of the motor is proportional to the copper content, the flat wire motor slot full rate is increased, the copper wire filling amount increases by 20-30% under the same product volume, and the output power technology is expected to be improved by 20-30%, making the vehicle more dynamic.
4. The electromagnetic noise of the flat wire motor is low. The stress and rigidity of the motor conductors are large, which can make the armature have good rigidity, thereby suppressing the armature noise. Using a smaller slot size can effectively reduce the cogging torque and further reduce the electromagnetic noise of the motor.
5. The end of the flat wire motor is short, which saves copper and improves the efficiency of the motor. Due to technical problems, the ends of conventional round wire motors are usually long, otherwise the copper wires are easily damaged during processing. For flat wire motors, because the wires are all hard wires, the ends can be made smaller during processing, saving copper, and improving motor efficiency. In addition, the flat wire motor adopts a more advanced winding method, which brings the end of the flat wire motor easier to cut. Compared with the round wire motor, the size of the end of the flat wire motor is reduced by 15-20%, and the space is further reduced. Miniaturization and weight reduction of the motor.
6. The flat wire motor has good heat dissipation and improves high temperature power. The internal clearance of the flat wire motor becomes smaller, the heat dissipation performance is good, and the temperature rise is 10% lower than that of the round wire motor. Because the flat wire is in closer contact with the round wire and the heat dissipation is improved, the study found that the thermal conductivity between the windings under the high slot full rate is 150% of the low slot full rate. The contact between the winding and the core slot is better, the heat conduction is better, and the thermal conduction capacity in the axial direction is 100 times that in the radial direction. The lower the temperature rise, the better the acceleration performance of the car.
The reason why flat wire motor companies will become the future trend is determined by the development level of electric drive systems for new energy vehicles. The characteristics of miniaturization, integration, and high power density are the evolution directions of electric drive systems for new energy vehicles. After all, bulky, heavy and weak drive systems are not welcome in the new energy vehicle market, and flat wire motors conform to the development trend of new energy vehicles.
From November 22 to 24, 2023, a motor industry event will be held at the Shanghai New International Expo Center, which is the much-anticipated "2023 China International 27th Small Motor Technology, Magnetic Materials Technical Seminar and Exhibition".
As one of the core parts of new energy vehicles, the electric drive system has an important impact on the performance of new energy vehicles, and has important significance for the power, economy, comfort, safety, reliability, and durability of new energy vehicles. In addition, in terms of industry needs, low cost, miniaturization, and intelligence are the main trends. The electric drive system of an electric vehicle is mainly composed of four parts: drive motor, transmission, power converter and controller. The drive motor is the core of the electric drive system, and its performance and efficiency directly affect the performance of electric vehicles. The size and weight of the drive motor and transmission will also affect the overall efficiency of the vehicle. Power converters and controllers can help electric vehicles operate safely and reliably.
In the long term, the trend of flat wire motors is highly certain. In the first half of 2021, the penetration rate of flat wire motors among the top 15 vehicle models in terms of sales reached 28%, compared to just 14% in 2020. It is anticipated that by 2025, the proportion of flat wire motors in the drive systems of new energy vehicles will exceed 80%.
X-Pin motor technology allows for a reduction in the height of the linear segment at the end of the motor while maintaining a high slot fill factor. This results in a shorter overall motor length, saving copper wire usage and improving motor efficiency, thus achieving miniaturization.
In recent years, the market penetration of new energy passenger vehicles has continued to rise. Due to the high demand, existing cylindrical-wire motors have become insufficient in meeting the performance requirements of electric vehicle propulsion. Therefore, the substitution of flat-wire motors for cylindrical-wire motors is a highly certain trend for the future. Motor manufacturers are actively seeking high-capacity, high-quality production processes to meet market demands, with ongoing optimization and innovation in the manufacturing processes of flat-wire motor stators.
As is well known, the energy conversion efficiency of electric motors is around 90%, meaning that losses account for approximately 10%. Within the energy losses of a motor, copper loss, which is the heat generated by the current passing through the stator winding, constitutes about two-thirds of these losses.By adopting flat wire motors, the round wire windings are replaced with flat wire windings, increasing the amount of copper per unit area on the stator. This increases the copper fill factor to 20% to 30%, meaning more copper is packed into the stator slots. This effectively reduces winding resistance, and the lower the resistance of the winding, the higher the electrical efficiency. Consequently, it reduces copper losses.