An article to understand the current situation and trend of electric drive

The core technology that distinguishes new energy vehicles from traditional vehicles lies in the "three electrics", namely batteries, motors, and electronic controls. At present, due to issues such as driving range and safety, the industry focuses most of its attention on the battery industry. However, relatively less attention is paid to the electric drive system composed of motors and electronic controls, which directly determine the main performance indicators of electric vehicles such as climbing, acceleration, and maximum speed.

So, what stage is the development of China's electric drive system at now? What are the development trends and challenges?

On June 26, 2019, Gong Jun, the motor responsible expert of the overall group of the National 863 Plan Energy Saving and New Energy Vehicle Major Project, introduced the development of China's electric drive industry at the "2019 Nanjing Innovation Week New Energy Vehicle Industry Landmark Summit".

Gong Jun, the motor responsible expert of the overall group of the National 863 Plan Energy Saving and New Energy Vehicle Major Project

At the same time, the "China New Energy Vehicle Electric Drive Industry Development Report (2019)" (hereinafter referred to as the "Electric Drive Development Report"), edited by the China Automotive Research Center Co., Ltd. and the Electric Vehicle Electric Drive System Full Industry Chain Technology Innovation Strategic Alliance, was officially released, comprehensively evaluating the technical status and problems of China's electric drive.

Thanks to its abundant rare earth resources, China has become a major producer of drive motors, and many technical indicators of the drive motors it produces have reached international advanced levels. However, in some areas, such as electric drive system integration capabilities, and SiC device research and development, manufacturing, etc., there is still a large gap with the advanced level of foreign countries.

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Gong Jun believes that China has certain advantages in the drive motor industry. With the development of the domestic new energy vehicle industry, China's motor industry has also made great progress. The domestic drive motor industry chain is complete, and independent motors always occupy an absolute share. At present, only a few passenger cars use electric drive systems from foreign-funded enterprises. China has formed a complete industrial chain including drive motors, motor controllers, transmissions, electric drive assemblies, major key materials and key components, and has achieved localization.

According to the statistics of China Association of Automobile Manufacturers in 2018, the proportion of self-supporting drive motors, motor controllers and electric drive assemblies in China reached more than 95%. In the announcement of China's new energy vehicles, there are more than 200 motor and motor controller manufacturers, of which the top 20 manufacturers account for more than 70% of the total product volume, and the market concentration is relatively high. Especially in the field of commercial vehicles, basically all domestically produced supporting equipment has been achieved.

The development of China's drive motor industry is showing a diversified trend . At present , independent motor suppliers such as Shanghai Electric Drive, Jingjin Electric, Shanghai Dajun, CRRC Zhuzhou Institute, and United Electronics are represented , and some products have been exported; companies represented by commercial vehicle powertrains such as Suzhou Green Control and Nanjing Yuebo independently develop and produce motors and electronic controls, mainly for commercial vehicles; and other vehicle development companies such as BYD, BAIC New Energy, Changan, Chery, and Weilai develop and produce electric drive systems through independent construction, joint ventures, and other means.

Jingjin Electric 3-in-1 Electric Drive Assembly

China's drive motor production accounts for more than half of the world's total production. Statistics show that the motor production capacity of China's major drive motor companies has exceeded 3 million units. In Gong Jun's view, China has become a veritable drive motor production powerhouse.

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China's overall electric drive level

Not far behind international advanced standards

Is China a strong country in drive motors? Judging from the performance indicators, Chinese motors are not bad. At present, many indicators of motor technology produced in China have reached the international advanced level.

The Electric Drive Development Report shows that the power range of China's independently developed drive motor series products meets the needs of various new energy vehicles below 250kW. In terms of key technical indicators, the power density and efficiency of China's drive motors are basically comparable to international levels.

Passenger car electric drive system

Specifically, China's drive motors have continued to improve in power density, system integration, motor efficiency and speed, winding manufacturing process, cooling and heat dissipation technology, etc., and are on par with foreign advanced levels. According to Gong Jun, China has developed prototypes and products with a power density of 4.5-4.6kW/kg, a maximum speed of 13000-16000rpm, and has achieved electric drive integration. The motor cooling methods include water cooling and oil cooling. In terms of specific companies, Jingjin Electric has developed a commercial vehicle direct drive motor with a torque density of 20.3Nm/kg, and Beijing Petlai has developed a 3500Nm outer rotor direct drive motor using flat wire technology. This shows that China's high-density drive motors and commercial vehicle motors have reached international advanced levels.

In terms of motor controllers, Shanghai Electric Drive, Shanghai Dajun, CRRC Times and others have launched their own automotive IGBT chips, double-sided cooling IGBT module packages and high-power density motor controllers, which also shows that China's high-density motor controllers are rapidly catching up with the international advanced level. For example, Shanghai Dajun and Shanghai Daozhi have developed a dual-motor controller with a double-sided water cooling structure, an input power of 260kW, and a motor controller power density of 23.5W/L. Compared with Bosch's dual-motor controller, the power density index of this product is comparable.

Gong Jun believes that in China's new energy vehicle industry chain, the advantages of drive motors are more obvious, which is mainly due to China's large reserves of rare earths.

However, many companies are also trying to get rid of the dependence of motors on rare earths. Foreign companies represented by Toyota and General Motors have begun to study the possibility of using hybrid magnets (including ferrite, etc.) to partially replace NdFeB materials, and have developed prototypes for verification; low-content heavy rare earth permanent magnet materials have been mass-produced in new energy vehicles such as Honda Accord ( parameters | pictures ).

Magna electric drive axle system

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Hub motors and 48V are also hot topics

Some hot areas in the development of the electric drive industry are also worthy of attention, such as hub motors and 48V systems.

In Gong Jun's view, wheel hub motors are an important development direction for new energy permanent magnet synchronous drive motors, but there is still a long way to go before large-scale mass production and application. Some Chinese universities, research institutes, and automakers have increased their investment in the research and development of wheel hub motors. BYD is a typical domestic company that uses wheel hub motors, which has successfully developed wheel hub motors (wheel-side motors) for buses.

However, hub motors currently have problems such as difficulty in integrated optimization design and high power density performance requirements. Their application in commercial vehicles and special vehicles has begun, but it will still take a long time to be applied in high-speed passenger vehicles.

In addition, the 48V BSG integrated assembly has attracted the attention of many foreign powertrain integrators due to its high cost-effectiveness. Continental, Bosch, Valeo, Magneti Marelli, and South Korea's LG have already launched 48V BSG prototypes. The "Electric Drive Development Report" shows that Continental, Bosch, and Valeo already have the ability to integrate 48V systems (BSG+battery+DC/DC), have achieved vehicle testing and small-batch trial production, and have increased fuel efficiency by as much as 12%-15%.

According to Gong Jun, China's 48V BSG assembly level is basically the same as that of foreign countries, and industrialization capabilities have been formed in key parts such as 48V BSG, DC/DC converters and 48V power batteries. However, in terms of integration capabilities, China still needs to combine domestic superior resources for development.

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High-power semiconductors have a high degree of external dependence

Of course, there are certain shortcomings in the development of China's electric drive industry.

First, the industry lacks recognition of domestic power electronic devices. Gong Jun believes that the global high-power semiconductors are still occupied by foreign companies. Since high-power power electronic devices such as IGBT in new energy vehicles generally have an expected life of more than 20 years, power cycles of tens of thousands or even millions of times, and need to work in different environments and climates, they have very strict requirements for performance and reliability, and most domestic companies use imported products. Data shows that about 90% of the new energy vehicle IGBT electronic products demanded by the Chinese market need to be imported, with the main sources being Europe, the United States and Japan.

Secondly, China started late in the technical research of SiC (silicon carbide) materials and devices, and there is a big gap with the advanced level abroad. However, many domestic research institutes have begun research and have made some progress. The "Electric Drive Development Report" shows that the 55th Institute of China Electronics Technology Group Corporation, CRRC Zhuzhou Institute, BYD, Beijing Tyco Tianrun, etc. have carried out research on SiC power devices. Tyco Tianrun has provided 1200V products to the market, and CRRC Times Electric has developed a hybrid module sample of 1700 Si IGBT+SiC Diode.