Micronucleus high frequency pulse heating technology
In the process of research and development and the use of batteries, we already know that the battery has a normal working temperature range, and the actual use of the battery in a low temperature environment will be greatly reduced, so in this environment, the battery needs a good thermal management to keep it warm.
Just by listening to the name, you know that this technology is definitely aimed at battery thermal management systems, especially with the word pulse heating. Looking back at the technology announced by Chang'an this time, in fact, its idea is not complicated, in the case of heating this big premise unchanged, so that the heating of the battery pack is more rapid and balanced, so that the battery pack can reach a suitable working environment as soon as possible under low temperature conditions.
The principle is actually based on a patented technology published in the Ningde era before the expansion, this patent is the use of low temperature to lead to increased internal resistance characteristics, by adding a device at both ends of the battery can generate oscillating current, so that the current through the cell with a large internal resistance, so that the battery internally generates a lot of heat, and finally the battery temperature rises rapidly.
Therefore, in order to avoid the occurrence of lithium dendrites in the negative electrode of the battery due to frequent overcharging, Chang'an slightly improved this technology on the basis of this technology in the Ningde era, and chose to use alternating current to generate current heating for the battery pack.
Why do we have to mention that it is alternating current? In the previous battery self-heating technology, the current generated was direct current. According to the physical definition, the size and direction of the current does not change in a unit time is called direct current, and then look back at the "lithium dendrite" generation conditions, in the discharge process the negative electrode is too late to deal with lithium ions, resulting in the emergence of metallic lithium elements.
The negative electrode of the battery that needs a breathing time, in the face of the constant output of direct current, it is easy to reach the limit, and then it is easy to appear "lithium dendrite", so in order to weaken this "immutable", it is necessary to give the negative electrode some breathing space, and the alternating current that constantly changes in the size and direction of the current in a unit time is more suitable for this work.
Alternating current does not maintain a constant value like direct current, it will always maintain a positive -0-negative -0-positive periodic change, and it is precisely because of the non-constant characteristics of alternating current that the negative electrode of the battery can reduce the burden, thereby reducing the probability of generating lithium dendrites.
At the same time, Changan also mentioned the power semiconductor IGBT (insulated gate bipolar transistor) at the meeting, IGBT is a non-on and off switch, it does not have the function of amplifying voltage, can be seen as a wire when conducted, and as an open circuit when disconnected. Coupled with the motor and the BMS system working together, it is possible to achieve random high-frequency current charge and discharge switching, further reducing the occurrence of lithium dendrite.
The navy blue C385 power battery pack officially announced by Changan can maintain a heating rate of 4 °C/mini in the ambient temperature of minus 30 °C, and can increase the power performance by 50% and shorten the charging time by 15% in the ambient temperature of minus 30 °C. From the data, the improved "battery self-heating" technology is not only more efficient, but also has a longer battery life, which is quite good news for users in low temperature areas.
Battery: I also need to "warm the baby"
At present, the more mainstream battery types on the market can be divided into two types according to the type of elements, namely ternary lithium batteries and lithium iron phosphate batteries, the biggest difference between the two is the use of different battery cathode materials.
Lithium iron phosphate batteries use lithium iron phosphate (LiFePO4) as the cathode material. Its advantage is that the safety is very high at high temperature conditions or overcharge, the disadvantage is that under low temperature conditions (the temperature is below -10 ° C), lithium phosphate batteries decay very quickly, after less than 100 charge and discharge cycles, the battery capacity will drop to 20% of the initial capacity, basically insulated from the use of cold areas.
Ternary lithium battery is the use of nickel cobalt manganese oxide (Li (NiCoMn) O2, NCM) or nickel cobalt aluminum oxide (NCA) ternary cathode material lithium battery, the nickel salt, cobalt salt, manganese salt as three different composition ratios for different adjustments, so called "ternary", like the Ningde era NCM811 is to refer to nickel, cobalt, manganese three ratio of 8: 1: 1 ternary lithium battery.
The advantage of ternary lithium battery is high energy density, which is also produced by the Ningde era, and its lithium iron phosphate battery energy density is 178Wh/kg, while NCM523 is 200Wh/kg, and NCM811 is 240Wh/kg. In terms of low temperature- -30 °C conditions, ternary lithium batteries can also maintain normal battery capacity, more suitable for the use of low temperature areas in the north. The disadvantage is that under high temperature conditions, the ternary material of the ternary lithium battery will decompose at 200 ° C, and it is very easy to burn or explode under the action of high temperature.
The above two kinds of batteries, although the materials and advantages and disadvantages are different, but from a microscopic point of view, the working principle of the two is also the process of lithium ion migration back and forth between the positive and negative electrodes.
In the low temperature environment, the positive and negative electrode material activity of the battery is reduced, and the conductivity of the electrolyte that acts as a bridge is also reduced, so when the battery is charged and discharged, the internal resistance will be generated, which is called internal resistance. The internal resistance of the battery increases, in the normal use of the battery, it will produce a large amount of Joule heat caused by the increase in battery temperature, experiments show that when the environment below 0 ° C, the temperature drops by 10 ° C, the internal resistance increases by about 15%.
Hindered by internal resistance, want to force but can only lead to excessive discharge of the battery, electrical energy is constantly converted into thermal energy, not only the power drops, can not normally output power, but also easy to affect the safety of the battery, all of which are caused by the low temperature environment.
In order to solve this problem, in addition to the latest "pulse self-heating" technology we mentioned above, in fact, suppliers and manufacturers have done a lot of "warm" measures.
PTC components
Heating membrane
At present, there are several common schemes, the first is the PTC and heating film that most pure electric models choose, and the idea of this scheme is to increase the battery temperature by heating the external electric heating element. PTC has two kinds of water heating and wind heating, water heating through PTC heating coolant, and then heat exchange with the radiator, wind heating is to open the warm air, cold air directly and PTC heat exchange, and finally blow out the warm air. The heating film is like a layer of conductive heating quilt to the battery cover, but the shortcomings of both are more obvious, PTC is easy to cause uneven heating, and occupy the space of the battery compartment, and the heating film due to the relationship between safety, the overall cost is not low, and the actual heating efficiency is not high.
Another solution is a liquid-cooled circulation system, which is like adding an additional set of heating to the battery pack to obtain a longer-lasting heat source by heating the coolant. There is also a scheme is heat pump air conditioning, the whole principle is like forcing the extraction of atmospheric heat into the car, but when the ambient temperature is too low when the heat pump is easy to fail, so Tesla also made a "magic change", in addition to extracting the heat of the outside air, but also collects the power battery system, drive system and PCS power electronics generated by the waste heat, the whole system relies on the eight-way reversing valve for complex heat absorption, in order to improve the overall efficiency of the heat pump air conditioning.
Changan Deep Blue C385 itself is a very sporty and high-tech model, and obvious stylistic characteristics can also be seen from its appearance. The closed front face outlines the X-shaped front through the lines on both sides, coupled with the sneaky body shape, as well as the hidden door handles and low wind resistance wheels designed to further reduce the wind resistance, etc., also appear on it, and the overall style is more dynamic.
The interior adopts a different design style from all the current Changan models, the instrument and central control screen adopt a stand-alone layout, the steering wheel adopts a double-frame design, and it is a sporty flat-bottom design. The central control screen adopts the 14.6-inch sunflower screen with intelligent steering with driving, which can be tilted left and right, and the sense of technology is full. Although there is no direct information to indicate that the car will use the Hongmeng system, from the layout of the interface, it is basically the same as the layout of the Avita 011 central control screen released earlier.
In terms of configuration, the new car will be equipped with AR-HUD head-up display system, Sony speakers, APA7.0 remote unmanned valet parking system, and electric drive high-frequency pulse heating technology. Among them, the APA7.0 remote unmanned valet parking system can create a "private driving" in the exclusive parking lot of "calling and going" for users.
In terms of power, thanks to the expansion of the EPA1 full-power platform, C385 provides a variety of power systems, including a pure electric version of the comprehensive cruising range of more than 700km, the maximum power of more than 190kW, the power consumption under comprehensive working conditions of 12.3kWh/100km, the fastest acceleration time of 100 km 5.9s; the extended range version of the comprehensive endurance of more than 1200km, pure electric endurance of more than 200km, feed fuel consumption of 4.5L/100km or less The hydrogen fuel cell version has a comprehensive endurance of more than 700 km, the hydrogen consumption of feed is as low as 0.65kg/100 km, and the rapid replenishment of energy in 3 minutes.
From the panel data alone, Changan Deep Blue C385 almost integrates the respective advantages of the current traditional and new power manufacturers, which also benefits from the new platform of EPA1.
In terms of the three-electric system, the EPA1 platform will adopt Chang'an's new generation of super collector electric drive, which has eight-layer flat wire winding, rotor double-V topology configuration, ultra-low resistance wire, adaptive control algorithm, low resistance topology optimization and other technologies, so that the maximum efficiency of the entire electric drive system reaches 95%.
It can also achieve a global OTA, support all node controller upgrades in the whole vehicle / car control domain software upgrade speed≤ 3min / cockpit software dual partition, to avoid the failure of the car upgrade, resulting in vehicle suspension, to achieve a common and new experience. The use of 8155 chips, the realization of 105K DMIPS high computing power of the cockpit domain controller, equipped with "Changan smart core", intelligent driving domain controller up to L4 intelligent driving and other functions can be basically realized on each model under the platform.
brief summary:
In the era of traditional and new power brands, the arms race has not only been at the level of mechanical adjustment, but also a key part of high-precision technology, so it is not difficult to understand why Chang'an has worked tirelessly to launch a new platform related to electric power. From the perspective of this pulse self-heating technology announced this time alone, the improvement of technology is worth our expectations, but the technology ultimately depends on the experience, coupled with the fact that the last car company using pulse self-heating technology has suffered a heavy blow in low temperature areas, this time Changan has pushed the model with this technology, and also hopes that Changan can give our consumers a satisfactory answer in terms of adjustment and actual measurement experience. (Text: Pacific Auto Network Gao Zijian)