On the morning of January 17th, 2021, the Future Battery Forum of China’s Electric Vehicle Hundred-People Conference was held in Beijing. Chen Binbin, Vice President of Electric Car Battery at Xinwangda and Director of the Battery System Research Institute, shared Xinwangda’s current technology status and solutions for battery safety at the forum.
Through nearly 10 years of system construction and product research and development, Xinwangda can now provide the industry with a full range of solutions from cell to BMS, module, and PACK systems. In 2021, Xinwangda can provide a range of 1 million kilometers for continuous driving and a 20-minute fast-charge cell. The power density of HEV single cell reaches 14,500 W/L, and the product line covers 48V, HEV, PHEV, and all BEV variants. The BMS can currently achieve ASILD level, with a basic software platform that meets AutoSar4.3. The precision of SOX during the whole life cycle is currently less than 3, and there are customized products for both HEV 48V and BEV. At the PACK level, we launched a solution for a fireproof battery system last year.
In the next 10 years, Xinwangda plans to push the sealing level of EOL to IP68 and achieve the ASILD level of functional safety for the entire system. Previously, we emphasized the functional safety of the BMS. Now, the entire battery system, not only the electronic control system safety but also the high-voltage safety, needs to reach level D.
In terms of lifespan, the operating vehicles last year traveled up to 800,000 kilometers, and the plan for 2021 is to increase that to 1 million kilometers. The fast-charging time will be shortened to 20 minutes. The system power density will reach 8,276 W/L in 2021, and the volume grouping efficiency will reach 55%.
Xinwangda’s technology roadmap is “one horizontal and one vertical.” On the horizontal axis, the focus is on the evolution from the perspective of system integration, developing towards the PACK direction – from standard modules to CTP, CTC, and intelligent chassis. Currently, our electronic control system and mechanical system integration are both BMS + FPC; the next step is BMS + FFC to further reduce costs and move towards wireless technology, ultimately leading to intelligent chassis. In terms of cell integration, our direction is intelligent cells, integrating chips further into the cell, even inside the cell, and creating wireless smart cells. On the vertical axis, we will further develop deep cell research and BMS research. Regarding BMS, we will upgrade bus rate, move towards wireless technology, improve network security and add OTA.
This is the BMS plan, mainly comprised of three parts: the integration path of BMS and PACK, the technological evolution of BMS itself, and the technological evolution of algorithms. We have planned three generations of products. The BMS itself is an upgraded hardware platform, improving safety features, network security and adding OTA implementation.In terms of algorithms, we have two approaches. The first one is online recognition and a SOX algorithm to achieve higher precision, and the other is to provide local warnings, while we currently provide cloud-based ones.
We have planned on the technological roadmap for battery cells, from 48 V and HEV to BEV and energy storage, as well as fast charging. In 2021, we will introduce BEV products with 630 Wh/L and HEV products with 14,500 W h/L to the industry, and the quick charging time can be reduced to 20 minutes.
Safety has been repeatedly raised in the industry in 2020. There were 141 recalls of new energy vehicles and a total of 860,500 vehicles were recalled, with fire being the most prominent issue. During the 2020 New Energy Vehicle Conference, Cao Qi, the deputy director of the Emergency Management Fire Protection and Rescue Bureau, mentioned that in recent years, the number of new energy vehicle fires has been on the rise, and fires have occurred in almost all new energy vehicle brands. XWD has shipped a total of 55,000 units over the past two years and has not experienced any incidents of fires.
We have also reviewed the statistical data from the National New Energy Vehicle Monitoring Platform, which showed that there were 79 safety incidents between May and August 2019. What were the causes of these safety incidents? About 61% of them were caused by defects in the battery itself, 21% were mechanical problems such as collisions, and there were other factors as well. In fact, each of these problems can be matched to our entire battery system. The table on the left shows that the intrinsic safety of the battery cells corresponds to the harms caused by the spontaneous internal short circuit of the cells themselves, while the active safety of the BMS and cloud monitoring system manages battery abuse such as overcharging, over-discharging, and thermal abuse. The passive safety system managed by the PACK system deals with mechanical abuse and environmental abuse.
So how did XWD address these issues? First, our quality criteria for XWD batteries are as follows: firstly, we believe that regardless of whether the electric vehicle is high-end or low-end, high-quality batteries must be used. Secondly, selling batteries with quality defects brings liability rather than profit to the company. Thirdly, implementing full lifecycle quality management can ensure the absolute safety of the battery.
To ensure battery safety, we need to work on six key processes: from the design, manufacture, and inspection processes at the factory, to cloud-based data monitoring, regular maintenance, and dynamic management through OTA when in the hands of users, to achieve full lifecycle management.How is the technical level of XWD? Firstly, all the data of the battery system is transmitted to the cloud big data, which can currently provide a safety warning with a recognition rate of 70% and an accuracy of 100%. The warning time varies according to different failure modes. Now, these ten hours show some of the monitored battery data. Once a single cell thermal runaway occurs, our BMS system can detect the hazardous accident within 6 seconds and report it to the whole vehicle system. We have designed a multi-layer protection system, and we can achieve a 30-minute isolation at the cell level and 20-minute isolation in the module level for 8-series. At the whole PACK level, whether it is a 5-series or an 8-series, we can achieve no fire or explosion.
How did we achieve this? We made a five-layer safety design. The first layer is the safety design and manufacturing at the cell level. Firstly, the material we developed is very safe, with low heat generation and high oxygen release temperature. Secondly, it has high thermal stability and mechanical safety, reaching HL2 level in the vertical extrusion of Z direction by 15%. There are 169 patented technologies in this area. The second layer is the monitoring system, including local and cloud-based big data monitoring of BMS. There are 58 patents here. Why can monitoring ensure battery safety? First, we can control the working of the battery in a safe range and boundary through the whole lifecycle battery status monitoring, and this boundary should be dynamically adjusted because the safe boundary will change with the working status of the battery. Secondly, BMS itself achieves the highest safety level of ASILD. Finally, the cloud’s proactive warning algorithm could predict possible risks of the battery in advance. The next three passive safety measures include efficient isolation and diversion at the cell level, control of thermal runaway through module enclosure and diversion technology, and system-harm reduction.
Safety needs to be 100% guaranteed, and there are approximately 5000 safety design elements that we need to check to ensure the system’s safety. Later, I will introduce how these five levels are implemented, one by one.
In terms of intrinsic safety, how does the cell design ensure safety? The material we are currently using has higher thermal stability and oxygen release temperature. In terms of mechanical safety, we performed a 35% limit deformation test in the Z-direction, simulating the safety of the cell being squeezed when the car has a bottom or passes a slope.# BMS Active Safety
The BMS itself reaches functional safety level D, and the system process developed by us has passed level L2. The precision of BMS algorithm is less than 3% throughout the entire lifecycle. Another aspect of active safety is cloud data monitoring, which consists of three parts. First is data, such as data for 30 seconds or one minute, which is sent to the cloud to perform an initial screening of battery safety status. Vehicles with problems will be sent to ground detection stations, where we have developed our own detection equipment to further diagnose battery safety. Actually, there is also a set of warning algorithms in the local BMS, which can predict the possibility of battery route failure in advance. This is a data analysis platform, and we have already connected to 450,000 vehicles. We have also independently developed ground detection equipment to work with automobile enterprises in performing periodic vehicle maintenance and maintenance.
Passive safety refers to the isolation at the cell level. This is directional diversion, which is different from traditional isolation. We can divert heat to the outside of the system. If the discharged gas temperature is less than 300 degrees, there will be no fire or explosion. It has passed the level 5 safety experiment at the system level.
In terms of safety manufacturing, the design of battery cells is more important than its manufacturing. From the aspects of material, electrode, winding, and consistency, we ensure the safety of the manufacturing of batteries.
Xinwangda is a group company, which was founded in 1997 with headquarters in Bao’an, Shenzhen. Currently, we have 32,000 employees and six bases. Xinwangda has been growing at a rate of over 25% each year. We reached 25.3 billion yuan last year, and this year, it is expected to exceed 30 billion yuan. Today, we are introducing the electric vehicle battery industry group, from cells, modules to systems.
Xinwangda’s development of power batteries insists on deep involvement in the entire industry chain to cultivate our comprehensive competitiveness, a layout covering the entire region, and establishing strategic customer resources. We will adhere to the full life cycle quality management to solidify the foundation for sustainable development.
Our production capacity: For the BEV product line, the effective production capacity in 2020 was 15 GWh, and our planned production capacity for 2021 is 25 GWh. According to the current growth expectations, we will have a 100% annual growth rate going forward. For the HEV product line, our effective production capacity in 2021 is 700,000 vehicles, and we have planned 1.5 million vehicles for 2022, with a 100% annual growth rate going forward.
This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.