The support behind the safety and reliability of new energy vehicles

Despite the decline in subsidies, the investment in new energy vehicles, especially electric vehicles, is still high in my country, judging from the new projects that have been reported in the media recently. At the "2017 China Electric Vehicle Hundred People Forum" held at the beginning of this year, Miao Wei, Minister of Industry and Information Technology, said that the Ministry of Industry and Information Technology has taken the lead in compiling the "Medium- and Long-Term Development Plan for the Automobile Industry", which clearly defines the development goals of my country's annual production of new energy vehicles to reach 2 million by 2020 and the proportion of new energy vehicle sales in my country's total sales to reach more than 20% by 2025.

In foreign countries, increasingly stringent energy conservation and emission reduction regulations are also driving the future development of new energy vehicles. McKinsey pointed out in an earlier report that electric vehicles will account for 50% of global new car sales by 2030.

The future development of new energy vehicles can be described as a "field of hope". However, for enterprises, opportunities and challenges have always been complementary.

At present, new energy vehicles, especially electric vehicles, are still facing safety risks, short driving range, insufficient system architecture reliability, uneven product quality, high cost, and difficulty in charging. Among them, the most important challenge is the safety and reliability of the system. After all, for market development and consumers, no matter how forward-looking the technology is or how attractive the preferential policies are, "safety and reliability" is the most critical and basic guarantee.

This requires that in addition to breakthroughs in key technologies such as batteries, motors, and electronic controls, all relevant manufacturing companies must also make achievements in core basic components such as connectors, sensors, contactors, and relays. Even these "supporting roles" that were originally used in the traditional automotive field are increasing in number as the electronic and electrical architecture is comprehensively improved, playing a key supporting role in the reliability and perfection of the entire system architecture.

Connect, sense and protect in the new electrical architecture

Taking the electric vehicle system architecture as an example, it is composed of several major components: battery, drive motor and electronic control, high-voltage distribution box, charging system, and high-voltage auxiliary electrical appliances. Whether it is from the components themselves or the entire system architecture, it involves connection, sensing and protection, and connection and sensing are the basis, and protection is achieved through connection and sensing. However, compared with traditional vehicles, these core components face more stringent requirements and challenges under the high-voltage and high-current system architecture.

First of all, as a core basic component necessary for electrical connection of circuit systems, connectors have higher current carrying capacity, voltage resistance and reliability requirements under high voltage and high current. In addition, electromagnetic interference is another important problem faced by connectors under such high power. At the same time, live plugging and unplugging operations under high-voltage circuits will generate arcs, which will seriously endanger electrical connections and electronic equipment, and may cause car fires. These problems require special design and development of connectors.

As for the main contactors that connect and disconnect the power battery from the inverter, the new electrical system architecture requires them to not only handle very high continuous currents, but also safely disconnect overload currents. Once a battery short circuit occurs, these contactors must be able to carry thousands of amperes of current until the main fuse cuts off the circuit. According to the Economic Commission for Europe Regulation "ECE R-100, Battery-Powered Electric Vehicles", battery-powered vehicles must generally be equipped with protection devices such as fuses, circuit breakers or main contactors to prevent the power battery from overheating due to overcurrent.

Now let's look at another core component - the sensor. According to relevant experts, the future development trend of pure electric vehicle sensors is to achieve miniaturization, multi-function, integration and intelligence. This requires that the sensor not only has the characteristics of small size, low price and high reliability, but also needs to be further improved in terms of accuracy, functionality and intelligence.

In addition to the above three types of components, there are also basic components such as circuit protectors, manual maintenance switches, relays, wiring harnesses, etc., which need to be upgraded under the new electrical architecture. However, for OEMs, the innovation of individual components is important, but what they value more is the stability and reliability of the system, and what they need is a more "reliable" systematic solution.

In response to this, TE Connectivity (TE), a global leader in connectivity and sensor solutions, has used its extensive experience in high-voltage generation, transmission and distribution to continuously improve and innovate its products in the field of new energy vehicles several years ago, and is committed to providing safe and reliable system solutions. Currently, there are matching solutions for multiple links in the new electrical architecture to meet the challenges in the development of new energy vehicles.

System solutions "escort" every aspect of the electrical architecture

●The connection and protection of the battery pack is a crucial part of vehicle safety

As the core component and power source of new energy vehicles, the battery pack is not only heavy, but also has a complex structure. It is composed of multiple battery modules, each of which consists of several to more than a dozen batteries. Among them, the current transmission and signal transmission between modules, between batteries, and within the battery management system (BMS) that manages the batteries require various connections and current and temperature monitoring, and the battery needs a high-voltage connector for external power transmission. Therefore, the reliability of battery cell connection and module connection, high and low voltage interface, current and temperature monitoring is crucial.

In addition, in recent years, there have been incidents of explosions and spontaneous combustion of new energy vehicles, most of which are also related to batteries. According to Li Wanxiang, General Manager of Sales and Marketing for Greater China at TE Automotive Division, "Under high voltage conditions, the contact and disconnection of the current circuit is very dangerous and it is easy to generate arcs. If not managed properly, the product may explode and burn." This poses a great challenge to the design of the pre-charge circuit, the matching of fuses and contactors, etc.

It can be said that the connection and protection of the battery pack is a crucial part of vehicle safety. In this regard, in addition to providing cell connection boards (ICBs), module connection solutions (M2M), low-voltage signal connectors and current sensors, TE's challenging high-voltage and high-current connectors and high-voltage contactor product series have been fully recognized by automakers.

High-performance connectors for high current and optimized size. TE's AMP+ HVP 800 high-voltage connector system can safely transmit high current and high voltage from the battery to the inverter and motor by using up to 250A of current in a 50mm² wire. This connector product series adopts a wide temperature and wire diameter range, as well as multiple fool-proof design options, suitable for many hybrid and pure electric vehicle applications. The assembly difficulty is simplified by the auxiliary pull rod that can achieve low insertion force. It is understood that in addition to the HVP800 high-voltage connector, TE has currently developed high-voltage and high-current connector products such as HVP1100 and PCON21.

TE's AMP+ HVP 800 High Voltage Connector System

A combination of high-voltage fuses and high-voltage contactors that effectively suppress switching arcs. Like the fuel tanks of conventional vehicles, the energy storage systems of hybrid and pure electric vehicles must be protected against thermal overloads. In order to promptly block the current after the vehicle is turned off or a fault occurs, a combination of high-voltage fuses and high-voltage contactors is usually used in the connection between the power battery and the electrical circuit. TE's EVC 250 high-voltage contactor is a safety device developed specifically for this application requirement. The product has a larger contact gap and optimized switching power. It has a high-performance arc-extinguishing magnet, which, combined with other measures, can effectively suppress the switching arc. It can also achieve a continuous 250A rated current and can carry up to 6,000A overcurrent for 20ms without affecting any critical performance. It is worth mentioning that the switch room of the EVC 250 high-voltage contactor has been optimized to completely cut off the current even under low pressure conditions at an altitude of up to 5,000 meters.

TE's EVC 250 high voltage main contactor

In addition to the EVC 250 high-voltage contactor, TE has also developed a series of high-voltage contactors and pre-charge relays such as EVC500, EVC135, EVC175, and HV Mini-k. Among safety devices, TE has also developed a manual maintenance switch (MSD) to address safety hazards caused by misoperation during battery pack maintenance.

“TE’s sense of responsibility for safety is a key factor in developing new products. We ensure that we provide safe and reliable solutions for all applications. In addition, the country now has very strict requirements on the energy density of battery packs. All battery pack manufacturers hope to store as much electricity as possible in the smallest possible space. Therefore, they will have very strict requirements on the space of connectors or other auxiliary components. We now use 0.5 mm connectors to meet this demand.” Li Wanxiang added.

● Improvement of charging technology is crucial to the development of new energy

In the past two years, many electric vehicle fires caused by charging have brought the safety issue of new energy vehicles to the forefront. TE has always put safety first in its charging cable products and built all the resources needed for charging solutions: from cables to contactors, from meters to card readers, from screens to sockets. In terms of safety and reliability, TE charging systems have monitoring, detection and protection functions, including: grounding monitoring, wiring error detection, avoiding overvoltage and undervoltage affecting charging, short-circuit protection in overcurrent conditions, relay diagnosis, and overheating protection, etc., to ensure the safety of the entire charging process.

In addition to batteries and charging systems, the motor and electronic control and high-voltage auxiliary electrical appliances in the electrical architecture also have many connection sensing and protection related contents, such as high-voltage shield connection, resolver, temperature sensor, terminal block, low-voltage signal connection, etc. TE currently has systematic solutions to match these components.

"As a parts supplier, TE hopes to give full play to our expertise to promote the rapid development of China's new energy vehicle industry. Regarding the safety issues of new energy vehicles, on the one hand, we will strictly follow the requirements of car companies or system suppliers to ensure the reliability and consistency of our products; on the other hand, we will make corresponding suggestions from a professional perspective to improve customers' considerations of the entire architecture. This is our responsibility and our mission." Li Wanxiang said in an interview.

This reminded the reporter of a comment made by Tsinghua University professor Ouyang Minggao at a previous industry forum, "The development momentum of new energy vehicles is very rapid, but too much momentum is not necessarily a good thing. Once a serious safety accident occurs, it will cause a devastating blow to the entire new energy vehicle industry. This requires special attention, and companies must have a sense of awe." The "enterprises" here include not only the OEMs, but also various parts suppliers in the industry chain. Let us encourage each other!

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.