Not long ago, with the electric vehicles of well-known domestic automobile companies such as Geely Automobile and Zhongtong Bus, the new energy vehicle high-performance permanent magnet motors led by SHJJ Power System Technology Company have been installed more than 70,000 units.
From the first-generation round strand winding motor with power density of 4.2-5.3kW / kg to the second-generation flat copper winding motor with power density of 6.3kW / kg, the product and sample specifications of permanent magnet motors are comparable or exceed The product level of first-line automobile motor manufacturers in Europe, America, Japan, and South Korea.
In the past two years, the company and 17 other units have driven the upstream industry chain to break through technical bottlenecks and filled a number of national technology and product gaps in the national “13th Five-Year” key R & D program for new energy vehicle drive motors. Among them, the usage of heavy rare earths of high-end rare earth permanent magnets is reduced by nearly 50%; the long-term temperature resistance of insulating materials exceeds 200 ° C, and the corona resistance life of round electromagnetic wires exceeds several times the national standard; the corona resistance life of enameled flat wires is greater than 90 hours …
Some of the raw materials, core components and devices that once relied on imports have been independently developed and produced. Some materials not only double their service life compared to foreign countries, but also cost only 60% of those abroad.
As of June 30, 2019, the project's first-generation round-strand winding motors had cumulatively loaded 68,000 passenger cars and nearly 4,000 commercial vehicles.
The drive motor is comparable to the world's leading automobile motor manufacturer
The development of new energy vehicles is inseparable from the core components of electric drives-motor systems. High-speed, high-efficiency and high-reliability motors can make new energy electric vehicles have lower energy consumption and longer life.
The current of the motor is conducted by the windings, and insulation is required between the windings and between the windings and the iron core. Low resistance and reliable insulation are the basic requirements for motor windings.
At the beginning of the 21st century, the well-known motor expert Cai Wei invented the "hairpin winding" motor, which was later applied to the GM Chevrolet Tahoe hybrid car. This is the world's first "hairpin winding" motor in the field of automotive electric drive. application.
Since launching the National Key R & D Program in 2017, Cai Wei, as the special person in charge, led Jingjin Electric and other units, and completed the technical innovation, mass production and loading applications of the first-generation round strand winding motor with a power density of 4.2kW / kg.
At the same time, the second-generation flat electromagnetic wire winding motor has also completed sample manufacturing and performance testing, and entered the test certification. Through ingenious design, they solved the topology problem of multi-parallel branch wave winding arrangement, adjusted cooling and welding parameters, overcome the manufacturing problems of multiple sets of thin flat wire motor windings, improved the number of motor pole pairs and speed, and made the motor smaller , Copper wire, silicon steel sheet and other materials are used less, the unit power consumption is less, and the cost performance is higher.
"The power density has increased from 4.3kW / kg to 6.3kW / kg, surpassing the 4.6kW / kg power density of the American general Bolt motor and the 3.8kW / kg power density of the BMW i3 motor, and also exceeding its planned 2025 in the United States. New energy vehicle motor index of 5.7kW / kg. "Cai Wei said.
On this basis, the third-generation transposed conductor winding motor has also started research and development.
High-end permanent magnet heavy rare earth usage dropped by 50%
In the global electric drive of new energy vehicles, permanent magnet motors account for nearly 90%. Adding heavy rare earth such as dysprosium and terbium to the permanent magnet can maintain the residual magnetism and improve the coercive force. "However, the reserves of heavy rare earths in rare earth mines are small, and with the popularization of new energy electric vehicles, large-scale production of rare earth permanent magnet motors at home and abroad, the use of heavy rare earths will face a bottleneck in resource shortage." Cai Wei said, Some developed countries have used low-weight rare earth permanent magnets in motor products.
The white paper "China's Rare Earth Status and Policies" once pointed out that China takes over 90% of the world's market supply with 23% of rare earth resources.
However, the preparation of rare earth permanent magnets and permanent magnet motors in China have long been controlled by Japan. "In the past, Japan bought rare earth permanent magnet raw materials from China, made permanent magnets and even motors, and then sold them to us at high prices or exported to Europe and America." Cai Wei said.
How to use heavy rare earth resources efficiently to avoid resource shortage and reduce costs? In the national special project, Cai Wei led, and cooperated with China's leading magnetic material technology company, to develop infiltration technology and lattice refinement technology to reduce the use of heavy rare earth by up to 50%.
"In the past, heavy rare earths such as dysprosium or terbium were often kneaded together with other permanent magnet raw materials like kneading. Now, by refining the crystal lattice, the heavy rare earths are infiltrated into the magnet. Precise. "
Cai Wei introduced that the R & D staff used the grain size refinement and microstructure consistency process to fill the gap in the domestic fine powder process, mass production of 35EH magnet dysprosium content, from 7wt% -8wt% to 5wt%, reducing weight The usage of rare earth is over 20%. At the same time, they combined the fine powder process and the diffusion process to reduce the terbium content of the 42EH magnet from 8wt% to the equivalent dysprosium 4.5%, reducing the use of heavy rare earth by 40% -50%.
Some insulation materials have a corona-resistant life of more than 10 times the national standard
As the heart of new energy vehicles, there are many electromagnetic wires in the drive motor. If the electromagnetic wire and the insulating material cannot withstand the high voltage, high temperature, and high voltage change rate during the operation of the motor, they will be easily broken down and reduce the service life of the motor.
The corona-resistant insulation materials produced in China are basically made from foreign manufacturers. "For example, nano-particle modified polyester imine and other raw materials and corona-resistant soft composite paper, etc., will be subject to international technical blockages at any time." Cai Wei said, The strength of the seller's market has left domestic users helpless.
In this project, Cai Wei and SZJF Insulation Materials Co., Ltd. used the composite technology of nanoparticles and enameled wire matrix resin to break through the technical bottleneck that nanoparticles are difficult to disperse in enameled wire matrix resin, and prepared a uniformly dispersed nanodispersion, Successfully prepared corona-resistant enameled wire paint.
At present, the corona-resistant polyesterimide impregnated resin developed by SZJF has long-term service temperature of over 200 ℃. The corona-resistant enameled flat wire developed by the company has a corona-resistant test life of more than 90 hours, which fills the domestic gap and exceeds the indicators of international competitors. The corona-resistant enameled round wire has a corona-resistant life of more than 100 hours and more than 10 times the national standard.