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What is Hairpin Motor? The Advantages and Disadvantages of Hairpin Motor

Definition of hairpin motor:


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. 


The circulation market has a very clear understanding of traditional new energy drive motors. For example, the composition of motors includes stator, rotor, end cap, bearing, junction boxes, and terminal, while the market has limited knowledge of hairpin motor. The definition of hairpin motor refers to the change in the shape of the wire used in the stator winding, from multiple thin round wires to several thick rectangular wires, also known as flat wires.


Advantages and disadvantages of hairpin motor:


The advantages of hairpin motor include small size, material saving, high efficiency, strong heat conduction, low temperature rise, and low noise. Details as follow:


1. Advantage 1: The same power, smaller volume, fewer materials, and lower cost. The volume is the same, the slot full rate is increased, and the power density is increased. The round wire becomes flat wire, and under the premise of the same space, the filled copper can increase by 20-30%. This means that the power is increased by 20-30% with the same motor space. In the case of the same power, the outer diameter and volume of the motor can be reduced, thereby reducing the amount of other materials used in the motor.


2. Advantage 2: The temperature performance is better. The internal voids are reduced, the contact area between the flat wire and the flat wire is large, and the heat dissipation and heat conduction are better. Through temperature field simulation, it is concluded that the temperature rise of the flat copper wire motor winding of the same design is 10% lower than that of the round copper wire motor. In addition to better heat dissipation performance, other performances including temperature can be improved.


3. Advantage 3: Lower electromagnetic noise. A relatively small slot size can be used to effectively reduce the cogging torque and further reduce the electromagnetic noise of the motor.


4. Advantage 4: Save copper, improve efficiency. For traditional round wire motors, due to process problems, it's ends are generally longer, otherwise, it's easy to damage the copper wire during the process. For hairpin motor, because the wires are hard-wired, the ends can be made smaller during processing, saving copper and improving efficiency.


Compared with the round wire motor, the hairpin motor also has its shortcomings, including difficult design, difficult technology, difficult equipment, difficult flat wire and lossy.


1. Disadvantage 1: Increase in loss. The round wire motor can use thin wires, there are more wires, and the flat wire is thicker, which will increase the loss of the hairpin motor, but the impact is limited. The specific effect is that the higher the frequency, the higher the AC copper loss of the rectangular copper wire winding. At the same time, the effect is also related to the electromagnetic design, such as the magnetic density amplitude in the slot, the height of the slot and the size of the flat copper wire.


2. Disadvantage 2: High requirements for copper wire. Thick copper wire has a certain degree of elasticity, and the bent material has a certain degree of rebound. This requires the designer to design in advance, which is a certain degree of difficulty. Due to factors such as bending and rebound, the insulating layer is easily damaged and gaps are generated. Hairpin motors have higher requirements for copper wires. Traditional motor windings can be wrapped and insulated after forming. Hairpin motors cannot be like this.


3. Disadvantage 3: The equipment requirements are high. Due to the complex process and high precision requirements of flat wire, it is basically impossible to achieve large-scale mass production through manual manufacturing. It must rely on professional high-end equipment, which is an important reason why it is not widely used.


4. Disadvantage 4: It's difficult to design hairpin motor, and it places high demands on the designer. The main disadvantage of hairpin motor is that they are not flexible enough. From the perspective of designing motors, different designs are usually extended. If you only need a 100KW motor, but in the design, you need to design a series of motors in the range of 80-120 KW. The reasons include two points: one is to meet potential needs, and the other is to make product design more distinctive, which is clearly different from other companies. For round wire motors, the iron core and the number of slots are the same, but the length and the number of turns of the coil are different, so it is easier to design a series. The number of turns of the hairpin motor is relatively small, and reducing one or two wires will have a greater impact on the performance of the entire motor.


Regarding the shortcomings mentioned above, the difficulties in raw materials, processes, and equipment are the barriers of the hairpin motor.

Shenzhen HONEST Intelligent Equipment Co., Ltd. was established in 2007. It is a national high-tech enterprise and a national little giant enterprise. It is mainly engaged in the research and development, production and sales of intelligent equipment, and provide digital and intelligent overall solutions for leading companies in the field of new energy vehicles. The company has a factory building area of 40,000+ square meters and more than 500 employees. R&D personnel account for 35%+ of the company's total. The company has branches in Dongguan, Chengdu, Suzhou, and Wuhan, and sales offices in Malaysia and South Korea.


Honest Automation independently developed new energy-driven hairpin motor stator assembly line, which is suitable for the production of card hairpin stator, such as BSG motor, automobile generator, new energy drive motor, etc. The entire production line has a high output. The servo motor adopts bus control, the key parts are processed by precision equipment, and the standard parts adopt the international top brands. Intelligent functions include lifespan management of key components, face recognition, real-time traceability of production data, upload, and distribution, and docking with the MES system.


Equipment advantages include high reliability, high stability and intelligence.


The hairpin motor stator assembly line includes paper inserting machine, paper shaping machine, wire making machine, wire twisting shaping machine, wire inserting machine, and welding machine.


Paper inserting machine: The equipment adopts a unique patented technology, and the control method adopts a high-speed, high-reliability bus servo, which can reliably shape and insert the insulating paper into the stator core. The insertion and cutting length of the insulating paper is guaranteed to be greater than or less than 0.03, It can well guarantee the withstand voltage and insulation of the motor.


Paper shaping machine: using precision shaping molds, strictly control the shaping stroke, temperature and time to ensure the shaping effect. When this equipment produces different models of products, only the upper and lower molds need to be replaced, and the program formula can be switched. The overall model conversion time is about 15 minutes.


Wire-making machine: The whole machine has only one power source and adopts a precision 

cam mechanism. The wire-making part is designed and processed at the mold level, which fully guarantees the consistency of the product. High stability can be achieved at the same time, the wire-making speed can reach up to 150 PCS per hour. There are a variety of wire-making equipment.


Twisted wire shaping machine: the contact with the wire is mirror-polished, which can have a good protective effect on the wire. It adopts up to 20 bus servo control, which can adjust the parameters accurately and flexibly so that the plug-in shaping can reach the ideal effect.


Line into the mold machine: the contact with the line is mirror-polished, which can protect the line very well. The equipment adopts bus-type servo and electronic cam control, which has good stability and high efficiency.


Welding machine: adopts double-station imported welding machine, high-precision welding and isolation tooling, so that the welding effect is stable and reliable. Using continuous welding, the welding speed can reach 400 points per minute.


Shenzhen HONEST can provide hairpin motor A/B samples, fully automatic production lines, semi-automatic production lines and stand-alone equipment according to customer needs. We have cooperated with many well-known automobile brands and have mature hairpin motor stator and rotor assembly technology. Welcome to get free customized solutions now!


Click here to get information about the hairpin motor production line

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