SMM9 March 18: Cao Hongfei, chief engineer of Zhejiang Godson Electric Drive Technology Co., Ltd., gave a speech on the theme of "commonly used materials and technology development trend of automobile power motor" at the 2020 (2nd) China Industry Expo New Materials Forum-China Automotive New Materials Application Summit and China (8th) Aluminum processing Industry chain supply and demand Trading Summit. It mainly focuses on the following four aspects: the cost and pressure analysis of automobile powertrain and motor, the cost reduction way of power motor, the common materials and technical requirements of power motor, the core materials of motor and the development trend of technology.
Analysis on the total cost of automobile power and the cost pressure of motor
1. The situation of New Energy vehicle Industry and the National subsidy Policy
The price of the battery is decreasing year by year, but the battery life of the whole vehicle is increasing year by year, the weight of the whole vehicle is getting heavier and the acceleration performance is getting better and better (Tesla). With the increasingly fierce price competition of the whole vehicle, the total success rate of power is getting larger and larger, and the total cost proportion and cost pressure are also increasing.
two。 Cost composition and analysis
The motor accounts for a large proportion of the total cost of electric power.
With the development of power electronics technology and the material cost of motor will account for more than half of the system cost.
As the foreign supply chain is better than the domestic supply chain, domestic enterprises need to give full play to the low-cost advantage of motors in order to ensure that the domestic electric system has sufficient market competitiveness.
The main materials of the motor are metal, except that the structural parts are greatly affected by the processing cost, the rest of the cost directly depends on the amount of raw materials. The raw material cost of driving motor basically does not change with the increase of output.
3. Changing trend of main material cost of Motor
Although aluminum materials are cheaper, aluminum products are greatly affected by processing fees, so the price of aluminum parts fluctuates less.
As the material cost of copper accounts for a high proportion of the total motor cost, and the proportion of processing cost is small, the rise of copper price will directly push up the motor cost.
The price of rare earth for motor fluctuates greatly, and the overall price of light rare earth falls slightly, but the price of heavy rare earth rises, which leads to the price of motor magnet basically unchanged.
4. Analysis of Logistics Channel of main Materials of Motor in China
Choosing a reasonable geographical location can save considerable cost of motor logistics expenses;
The motor materials in the Yangtze River Delta are the most complete, but the labor cost in the Yangtze River Delta does not necessarily have an advantage.
Choosing to build a factory with customers on the spot can not only reduce logistics costs, but also reduce packaging costs.
Supplier and logistics channel of silicon steel sheet
The consumption of silicon steel sheet is the largest, and the utilization rate is less than 45%. The weight of the iron core made of silicon steel sheet accounts for more than 50% of the whole machine weight, so the logistics cost of silicon steel is the highest.
Supplier and logistics channel of enamelled wire
The weight of enamelled wire is about 1015% of the total weight of the motor, and the logistics cost is also relatively high.
Logistics channel for structural parts
Aluminum consumption is relatively large, accounting for more than 30% of the total motor weight, and most of the aluminum structures are closely machined, so the logistics cost of aluminum is also very high.
The way to reduce the cost of power motor
1. System integration-saving structure and harness costs
The motor and the gearbox share the end cover, which saves the structure cost.
The motor and the controller are electrically directly connected to save the electrical connection.
The system cost is optimized by unifying and determining the performance requirements and thermal management of each sub-component from the system level.
After-sales maintenance cannot be carried out alone
It is only suitable for suppliers with overall deep integration capabilities.
The technical challenges that integration brings to motors:
Design and simulation of oil cooling;
Oil resistance of insulating materials;
Limited motor space-high power density requirements.
2. Significance and methods of increasing power density
Affected by the saturation of the magnetic conducting material, it is difficult for the motor to increase the magnetic load B when the magnetic density of the silicon steel sheet is more than 1.95T, and most of the driving motors are saturated when the peak torque is running, so, to a large extent, the improvement of power density depends on whether a higher current density can be obtained.
The loss of the motor mainly includes copper loss and iron loss, the main heating loss of most motors is copper loss, and the relationship between the copper loss and the current density of the motor is square. Therefore, increasing the current density of the motor can easily lead to motor overheating, the overheating capacity of the motor is limited by insulation materials, and the higher the winding working temperature is, the lower the efficiency is.
Improving the cooling effect can not only improve the electrical conductivity of the armature, but also reduce the armature temperature and further reduce the copper loss of the motor. Cooling design is the most effective way to reduce the cost.
3. Optimize cooling design to increase electrical load and reduce comprehensive cost
Reduce the path L in the heat transfer direction; increase the heat transfer area S; increase the thermal conductivity λ; in addition, increase the heat conduction path (which may be the most effective measure in the thermal design of the motor).
4. HAIR-PIN motor technology and products
High magnetoresistive torque
The flat wire winding matches the equal slot width iron core, which increases the armature tooth width, avoids the excessive saturation of the armature core, not only reduces the iron loss, but also improves the magnetoresistive torque effect of the motor.
High torque / power density
The effective cross-sectional area of the winding is large, the air filling in the armature slot and the end of the winding is less, and the ability of heat conduction and heat dissipation is good. More power and torque can be obtained.
Make the armature have better stiffness and restrain the armature noise; the relatively small notch size can effectively reduce the cogging torque and further reduce the electromagnetic noise of the motor.
There is no need for binding.
The size of the end of the winding is stable, it does not rebound after shaping, and the end of the winding does not need to be tied, so the cost of auxiliary materials is saved. The off-line speed of the equipment is faster and simpler than that of the round winding. Compared with the round wire armature, the flat wire armature has good parameter consistency, which can reduce the labor cost.
5. Increase the ratio of magnetoresistive torque and reduce the amount of rare earth
Through the accurate design of motor parameters, control of key parameters (including heating parameters, back EMF, short-circuit current, magnetic steel demagnetization current, etc.) design margin, and reasonable distribution, to achieve the purpose of controlling the amount of magnetic steel.
By increasing the magnetoresistive torque ratio of the motor, replacing the NdFeB magnetic steel with other magnetic steel materials, adopting the new armature process and punching process, improving the efficiency, reducing the temperature rise of the motor, and reducing the use of expensive rare earths.
A new type of non-permanent magnet motor and its control theory are studied. (such as switched reluctance motor, Synchronize motor, new technology induction motor), to find and design a scheme that can replace rare earth motor.
Common materials and technical requirements for power motors
At present, the main materials commonly used in power motors are conductors and insulation materials, silicon steel, magnetic steel, junction plate seat (bus-bar).
Main technical specifications of enamelled wire
Main technical indexes of tertiary insulation
Main technical index of silicon steel sheet
Main technical indexes of iron core
Main Technical Indexes of bus-bar
Development trend of Motor Core Materials and Technology
1. Key points of industry demand
The five factors that the whole vehicle pays close attention to the motor performance are: high power density, low noise, high efficiency, low cost and less involvement.
A good brand must rely on good products to ensure reliability. The manufacturing technology and production management of motor products are the most key factors to ensure the competitiveness of products.
No ideal motor can meet all customer needs.
No full-car customers will give in on cost control.
two。 Demand trend of New Energy vehicle Industry
The powertrain of the whole vehicle is developed on the platform, and the space size of the chassis is getting more and more compact, and the space of the whole vehicle is getting bigger and bigger.
Better and better acceleration performance and farther and farther driving mileage;
A single vehicle has multiple power units, and multiple power sources work together efficiently.
The more widely used the range enhancer will be in the passenger car;
3. Analysis on the Technical situation of Motor
4. Product technology innovation and management
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