Solving the "safety anxiety" of new energy vehicles needs to start from the details

With the strong support of the country, China's new energy vehicle market has made great progress in just a few years. Independent automakers including BYD, SAIC, BAIC and Chery responded to the call to launch their own new energy products. According to the latest data disclosed by the China Association of Automobile Manufacturers, from January to September this year, new energy vehicles produced 302,000 vehicles and sold 289,000 vehicles, an increase of 93.0% and 100.6% over the same period of the previous year. Among them, the production and sales of pure electric vehicles were 229,000 and 216,000 respectively, up 118.1% and 128.4% respectively over the same period of the previous year; the production and sales of plug-in hybrid vehicles were 73,000, an increase of 41.7% and 47.2 respectively over the same period of the previous year. %. With such growth, the huge market holdings are just around the corner.

Solving the "safety anxiety" of new energy vehicles needs to start from the details. However, with the rapid increase of new energy vehicles, some quality hidden dangers have begun to emerge. Since last year, accidents involving the spontaneous combustion of pure electric buses and hybrid buses have been reported in newspapers. The reporter obtained statistics from the current public information and related reports. In the first half of 2016, the self-ignition accidents of new energy vehicles exposed in the first half of 2016 were as high as a dozen. For a time, the safety of new energy vehicles has become the focus of attention in the industry. Compared with “mileage anxiety”, “safety anxiety” is more worrying and has become an important level in the development of the industry.

There is a lack of trust behind this kind of “security anxiety” due to vague industry standards. For example, consumers will have questions such as “Does the new energy vehicle battery radiation hurt?” However, the most direct ones should be those that have already occurred. Especially the shocking spontaneous combustion accident. So, what is the source of the spontaneous combustion accident of new energy vehicles? There are many different opinions in the industry, but it is related to the reliability of power batteries, power distribution systems, wiring harnesses or electrical devices, or improper charging.

How to eliminate the hidden dangers of new energy vehicles, especially the spontaneous combustion hazards? The answer involves all aspects. Today, we start with a part of it, that is, the distribution and transmission system closely related to vehicle safety.

Industry efforts: building a safe and reliable distribution and transmission system

As we all know, with the upgrade of voltage and current in new energy vehicles, the performance requirements of various components are more demanding in high voltage and high current environments. Therefore, it will become critical to establish a safe, reliable and efficient power distribution and transmission system.

In this regard, Li Wanxiang, general manager of sales and marketing of TE Connectivity (TE) China Automotive Division, said: "To establish a safe and reliable power distribution and transmission system, the first priority is that the main engine factory must clearly understand the system load characteristics, so that it is reasonable. Build the entire system architecture; secondly, consider the performance and quality of the components. The so-called 'best' parts and components in the system application should be the 'most suitable' products."

Power battery with high voltage electrical connector system as an example (as shown below), a hybrid electric vehicle and an energy storage system must be thermal overload protection. High-voltage fuses and high-voltage contactors are often used in the connection between the power battery and the electrical circuit to block current in the event of a vehicle stall or malfunction. It should be emphasized here that the cutting capacity and overload tolerance of the main contactor must be coordinated with the characteristics of the fuse, that is, the main contactor and the fuse can be used together to function as a loop protection.

Battery and electrical system connection diagram

It should be said that every component is responsible for the safety of the entire vehicle, as well as the safe operation of the distribution and transmission system.

Therefore, in order for the performance of contactors and connectors to fully meet the increasingly stringent use environment of new energy vehicles, technical breakthroughs are needed.

The reporter learned from many parties that many inflatable contactors used in new energy vehicles are not specifically developed for automotive applications, and are often borrowed from other industrial applications. The reason is that the new energy vehicles have developed too rapidly in just a few years, and the matching parts industry has just started. Many standards and technical parameters are still vague, still in the exploration stage. In addition, in order to improve the relevant standards and technical parameters of new energy vehicle products, it is far from enough to rely solely on the requirements of the main engine manufacturer and the products manufactured by the component manufacturers. In this process, it is necessary to have excellent research and development capabilities, rich industry experience and real commitment. Companies that promote innovation in the industry come together to complete.

It is reported that TE has launched the EVC 250 to the Chinese market, which is the world's first high-voltage main contactor for new energy vehicle applications. The product features a non-inflatable, innovative design that offers significant performance, safety and cost advantages.

Forward development: Optimize the breaking current capability of the EVC 250 main contactor

According to the LV123 standard issued by the German Automobile Manufacturers Organization (AK), in the case of overcurrent, the energy storage and / or high voltage battery must be able to be disconnected from the DC high voltage circuit through the corresponding contactor. Therefore, before the fuse is blown, the main contactor in the main circuit must maintain complete functionality to carry or break the overcurrent; even after the fault is cut off, the disconnected contactor must ensure that there is sufficient between the high voltage battery and the vehicle. High insulation resistance.

TE's new generation of EVC 250 main contactors have greater contact clearance and optimized breaking capacity. It features a high-performance arc-extinguishing magnet that, in combination with other measures, effectively suppresses switching arcs. The contactor achieves a continuous current rating of 250A and can carry an overcurrent of up to 6000A for 20ms without affecting any critical performance.

In addition, the EVC 250's switchgear is optimized to cut off current completely even at low altitudes up to 5,000 meters. Because the EVC 250 is non-inflated, there is no need for repair or replacement due to pressure loss or air leaks; and when the current greatly exceeds the current limit, excess pressure can be released without damaging the casing, greatly reducing The possibility of explosive damage to the component improves the safety of the product.

EVC 250 main contactor

The EVC 250's innovative design achieves a compact size of 93 x 55.3 x 49.8mm for fully automated production. TE offers both single and dual coils, as well as different voltage versions of EVC 250 of 450VDC and 800VDC to meet the needs of passenger and commercial vehicles.

Li Wanxiang said: "For new energy vehicles, TE has had an in-depth understanding and reserve in the early stage. The solutions introduced are based on solid basic research and years of application experience, not only to achieve breakthroughs in innovation, but also to have a forward-looking perspective on market development. Sex. It is understood that in addition to EVC 250 contactors, TE high-voltage contactors and relays currently used in hybrid vehicles, pure electric vehicles and fuel cell vehicles, and automotive charging systems include: EVC135 contactors, EVC175 contactors, EVC 500 contactor, Mini K HV pre-charge relay, etc. In addition, with its technical advantages in the field of connection and sensing, TE also has mature solutions for cell connection and high voltage shielded connectors to consolidate system security and stability.

Nowadays, it is the critical period for the development of new energy vehicles. The frequently exposed safety issues will not only increase consumer doubts and concerns, but also affect the overall development of the country's strategic emerging industries. Eliminating the "safety anxiety" of new energy vehicles is an industry issue. From policy specifications to technical details, all parties need to work together.

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