Why flat wire
Why a 1% performance improvement of flat wire motor can cause huge changes in the industry?
Recently, the hottest topic in the field of new energy vehicles from lithium battery wind turned out to be the motor that accounts for only 10% of the cost of the vehicle. With the flat wire motor related to the Jingda shares, Founder Motor and other companies share price is nearly doubled, and the reason is a 1% efficiency improvement in the application of flat wire motor. Why this 1% performance improvement can cause a huge change in the industry?
Throughout history, whether it is sports or business war, the master of the duel, when approaching the limit
Every 1% improvement can often bring far more than 1% effect.
Looking back at the development of flat-wire motors, the Chevrolet Volt and Toyota’s fourth-generation Pruis have already started to apply flat-wire motors, while China’s research in this area started late. But recently, Tesla, SAIC New Energy, ZEEKR, BYD and other new energy vehicle companies have accelerated the pace of replacing round-wire motors with flat-wire motors.
Year | Automaker/Model |
2015 | Toyota/Pruis Gen4 |
2017 | SAIC/ERX5 |
2020/05 | GREAT WALL/ Svolt |
2020/06 | Porsche/Taycan |
2020/07 | Dongfeng Motor/Voyah |
2020/10 | BMW/ IX3 |
2020/11 | V.W./iD.4 |
2020/12 | BYD/Han GT |
And the reason for the replacement is:
Flat-wire motors are able to increase efficiency by 1% compared to ordinary motors.
Physics tells us that the nature of mechanical work is the process of converting energy from one form to another.
For the motor, the goal is to convert electrical energy into mechanical energy. And because of the law of conservation of energy, the limit of this conversion efficiency, is 99.99 ……%, infinitely close to but not 100%.
For electric motors, the losses come from these aspects.
Motor loss
The conversion efficiency of permanent magnet synchronous motors can reach 96%-97%, which is already much higher than that of internal combustion engines with only 30-40% thermal efficiency.
How to go further on this figure? It is the consensus of the industry to use more reasonable stator windings and to work on the copper consumption, which is the largest energy loss.
The flat wire winding technology is the solution to these needs.
Benefits of flat wire motors
1) High efficiency
More copper per unit area. Compared with traditional round wire motors, flat wire motors can increase the full rate of bare copper slots by 20% to 30%, effectively reducing winding resistance and thus copper losses.
Compared to round wire windings, flat wire motors can cram in more area of wire under the same conditions. The thicker the wire and the lower the resistance, the less energy will be lost in the wire due to heat generation.
Secondly, the end size is shorter. Hair-pin motors have shorter winding end size compared to round wire motors, and the total height of the end is 5~10mm shorter, which effectively reduces the copper consumption of the end winding and further improves the efficiency of the motor.
The copper at the end does not contribute to the motor power, but only serves as a connection, which generates additional electrical losses, so the shorter the better.
These structural optimizations can make the average motor efficiency, compared to motors that do not use flat wire technology, increase by more than 1%.
However, after all, the improvement is only 1%. How meaningful is the “1%” improvement for engineers in the lab? In terms of user experience, what can be brought to the user?
First, from the motor characteristics graph we can see that the four-slot flat-wire winding motor, the most efficient area is significantly enlarged.
The enlargement in the horizontal axis direction indicates that the speed range of the most efficient interval has become larger. From low speed working conditions in city congestion to high speed cruising conditions, the highest efficiency can be enjoyed.
Secondly, the so-called “1%” refers to the average efficiency difference between the two under WLTC conditions, which is 1.12% higher for flat-wire motors. However, in the full range of average conditions, the difference between the two efficiency values reaches 2%. At low speed and high torque operating points, the efficiency can even be improved by up to 10%.
(Note: WLTC is the new energy fuel consumption test standard to be implemented soon.)
Of course, flat wire technology brings more than just high efficiency.
2) Higher power density
Hair-pin motors increase the bare copper slot full rate of 20% to 30%, the current high level in China can reach 75% slot full rate, there is more room for growth in the future. Under the same volume, flat-wire motors can be packed into more stator windings, so that flat-wire motors can output higher power and torque under the same loss.
At present, the highest power density of motors with flat wire winding in China reaches 5kW/kg, while ordinary motors meet the bottleneck at 3kw/kg. China’s “Energy Saving and New Energy Industry Development Plan” requires motors to reach 4kw/kg or more, so the application of flat-wire motors has become inevitable.
(3) Stronger heat transfer capability
Compared to round wire, the flat wire in flat wire motors has a more regular shape, fits closely in the stator slot, makes better contact with the teeth and yoke of the stator core, reduces thermal resistance in the slot, and has higher heat transfer efficiency. All these will further improve the peak and sustained performance of the motor.
In reality usage, it means better sustained performance and can reduce the weakness of electric vehicles when running at high speed.
(4) Better NVH performance
The motor with flat wire structure will have better rigidity because the winding has better rigidity, and the whole machine will also have better rigidity. At the same time, the flat wire winding is inserted through the end of the core, so there is no need to embed the wire from the slot, and the electromagnetic design can choose a smaller slot design to effectively reduce the slot torque pulsation. Both mechanical and electromagnetic vibration noise can be effectively reduced.
(5) Smaller weight and size
With the same power, flat-wire motors can have smaller size and weight because of the decrease in copper usage due to the increase in slot fill rate and efficiency. For passenger car companies, the reduced size of the motor allows more space for the vehicle as a whole, such as increasing the capacity of the battery. And the smaller weight also allows the vehicle speed, range can be improved.
Raytron in the flat wire motor business
Raytron products in motor business
Enamelled Flat Copper Wire is widely used in the windings of telecommunication equipment, transformers, motors, and generators of various electrical equipment.
Raytron provides oxygen-free copper ( Min 100%IACS) and copper-clad aluminum ( Min 60%IACS) flat wire in a variety burr-free edges such as Square, Natural Round, and Full Round.
Raytron Flat Wire Features
♦ Burr Free Edges
♦ Continuous Coil with less Welds than Traditional Strip Coil
♦ The Width-to-Thickness Ratio of up to 100:1
♦ Yield Strength:<70Mpa
Applicable Products
Copper Ribbon / Flat Wire
*Ag, Ni, Sn Coating Available
Bimetal Ribbon / Flat Wire
*Ag, Ni, Sn Coating Available
Raytron Size Range
About us
Raytron was founded in 2012 and started its business with the development of copper-rolled flat wire.
After 10 years of persistent efforts, Raytron has become the most professional manufacturer of high precision copper & copper-clad aluminum flat wire in China and one of the very few manufacturers in China that can produce flat wire with a width to thickness ratio of higher than 100 times and copper flat wire with ultra-low yield strength below 70Mpa. High dimensional accuracy and straightness are also guaranteed.
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With 10 high-precision 4-link rolling mills and an annual production capacity of 10,000 tonnes, Raytron is the largest manufacturer of rolled copper flat wires for photovoltaic convergence strips in China.
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