◆ Strategic layout from E0 to E2
At present, SAIC's new energy three-generation product system has formed three generations, of which E0 is the first generation, and its derivative products include Roewe Ei5, Roewe ERX5 and Marvel Comics? X and so on; And roewe r, which has just been listed? ER6 and roewe r? MARVEL-R adopts SAIC's new generation three-electricity technology, code E 1. According to the official statement, this generation has been optimized and improved on the basis of E0, thus bringing more excellent performance; On the other hand, E2 represents the next generation of "Three Electricity" technology of SAIC. The system will be developed based on a brand-new electric vehicle platform. According to Mr Zhu Jun, E2 is a "big expense".
With the above understanding of the intergenerational relationship of SAIC-EIC technology, it is convenient for us to introduce the performance improvement between different generations. However, what needs to be explained to you is that although we are talking about three major electrical technologies (motor, battery and electronic control) today, the concept of electronic control is broad and vague. The electronic control we usually say generally refers to the inverter of the motor and the power management system of the battery, which also determines the performance of the motor and the battery. Therefore, we will interpret the current technical status of Roewe Power System from two aspects of SAIC's motor and battery technology.
◆ Technical status and future development of SAIC.
When it comes to motor performance, we usually pay more attention to several parameters, including power level, volume and weight. Next, we will use these parameters to talk about the current achievements and future development direction of SAIC motor technology.
The above picture comes from SAIC official, and it can be seen that the peak power of the motor is low, heavy and bulky in E0 state, and the power density is only 1. 1kW/kg. In contrast, the motor power density of E 1 reaches 1.97kW/kg, which is obviously higher than that of E0 motor, which means that the motor weight of E 1 can be greatly reduced under the same power, and the smaller weight is beneficial to the maximization of vehicle cruising range.
The winding technology of 8-layer hairpin motor can be said to be the biggest contributor to the technical progress of E 1 motor. As we know, one of the main advantages of hairpin motor compared with traditional round copper winding is to improve the shape of copper winding to obtain higher slot full rate, improve the power density of motor, and improve the heat dissipation performance and running noise of winding.
In fact, E0 motor has adopted hairpin motor winding technology, with only four layers, but on E 1, the number of winding layers has doubled to eight. More winding layers are beneficial to reduce the influence of skin effect (the phenomenon that internal current gathers on the surface of conductor when alternating current is applied to the conductor) on the performance of the motor, thus improving the efficiency, power density and torque density of the motor.
However, the maximum efficiency of the motor can only be shown in a specific speed/torque range, so people should actually pay more attention to the size of the efficient working range of the motor. As can be seen from the figure, the rotation speed of the eight-layer hair-raising motor has been increased from 12000 to 15000, and the motor efficiency can still reach 94% when the motor reaches 14000, while the four-layer hair-raising motor cannot reach 94% when it exceeds 12000. This means that cars equipped with 4-layer hairpins will consume more power when driving at high speed, while 8-layer hairpins can bring longer cruising range with the same battery capacity.
The advantage of coaxial layout is that compared with the parallel axis design of E0 motor, it saves the transverse space of the motor. When the motor is arranged in the front engine room, the length of the front engine room can be reduced to make the vehicle more compact. However, because the coaxial layout can not reduce the longitudinal space of the motor, E 1 motor can only support the predecessor layout. Because if you put the motor on the rear axle, it will invade the trunk or the rear space.
As for the E2 motor, we will continue to use the 8-layer hairpin winding technology, but from the above parameter table, we can see that the peak power, maximum torque, maximum efficiency and power density of the motor have been obviously improved. As for how this promotion was achieved, Mr. Zhu Jun did not give a clear introduction, but pointed out the core direction of the breakthrough.
But the temperature data of the stator and rotor of the motor is very important, because once it exceeds a certain temperature, it will lead to demagnetization and affect the life of the motor. Therefore, establishing temperature model and implementing effective cooling measures are the keys to achieve greater power under the same motor size, which requires a lot of energy to establish the know-how.
Structurally, the E2 motor will return to the parallel axis layout, mainly because this layout can compress the longitudinal space of the motor to a certain extent, which is convenient to place on the rear axle and reduce the intrusion on the interior space of the car. I believe you should have gained something by this time. Yes, unlike the front drive layout restriction of E 1, the rear drive layout will be the first choice for vehicles equipped with E2 motor.
If the motor is arranged in front to drive the front wheel, it is easy for the front wheel to break through the limit of friction with the ground, causing slippage; Because the downforce of the rear wheel is greater, the motor with greater torque can obtain better performance, which is why the E2 motor should be arranged in the rear wheel drive type first.
However, this design has higher requirements for the platform of the vehicle. Therefore, starting from the third generation electric system of E2, SAIC will launch a new generation pure electric architecture that is completely independently developed. Only by adopting this architecture can we give full play to the advantages of small size and high performance of the new generation electric drive system. In addition, it is worth mentioning that at present, the electric drive system of E 1 already supports part of FOTA, and E2motor will be able to realize faster, more efficient and more comprehensive FOTA through 5G technology. At this point, editors began to look forward to it.
◆ Present situation and future development of SAIC battery technology
Unlike fuel vehicles, which pay more attention to the research and development of drive system, battery technology also plays a vital role in the development of electric vehicles. SAIC's R&D team also knows this, so it has been firmly in control of the independent research and development capabilities of batteries. At present, except for batteries, other battery-related technologies are basically the crystallization of independent research by SAIC engineering team.
At present, the development of battery technology is restricted by many factors, including cost, energy density, safety, charging speed and so on. These factors also have a certain degree of trade-off, how to choose is a more difficult multiple-choice question in front of the main engine factory.
With roewe r? With the launch of ER6, Roewe is officially equipped with the next generation of E 1 battery. The new generation battery completely surpasses E0 generation products in technical parameters, which are mainly reflected in lower cost, higher energy density, higher capacity and safer. So how did Roewe do it?
In order to achieve higher energy density, Roewe adopted large module battery technology. We know that the traditional power battery pack contains multiple battery modules, and each battery module contains multiple batteries. This layout makes the modules occupy a lot of space and cannot store electric energy, so the more modules, the lower the space utilization rate inside the battery pack.
According to Mr. Zhu Jun, at present, the energy density of E 1 battery pack can reach 180Wh/kg. You should know that this performance is achieved by using the ternary lithium battery system of 523 (the ratio of nickel, cobalt and manganese as cathode material is 5: 2: 3), which can make the vehicle reach the cruising range of more than 600km.
In the editor's view, on the one hand, it can improve the energy density and reduce the production cost, on the other hand, it is also helpful for the later maintenance of the product. After all, after using CTP technology, a battery pack is equivalent to a module, and all batteries are fixed with glue, which is not conducive to later maintenance.
SAIC is also expanding the capacity range of E 1 battery packs with the same volume. According to the current planning, the E 1 battery pack can achieve three capacities of 50kWh, 60kWh and 70kWh, corresponding to the cruising range of 400km, 500km and 600km respectively. The version with the lowest capacity adopts lithium iron phosphate battery, which reduces the battery cost by about 15% while ensuring safety and cruising range. The new Roewe Ei5 and MG EZS will use this battery pack in the future.
In E0 era, the battery capacity of SAIC was relatively low. In addition to the cost factor, there is actually a big reason, that is, paying great attention to the safety design of batteries. In the E 1 era, SAIC's requirements for safety have reached a new height, that is, the battery will not spread to other batteries within half an hour of thermal runaway. This standard comes from the American UL-2580 battery safety standard, which can be said to be very strict.
In order to achieve the safety goal of E 1 batteries, Mr. Zhu Jun said that at present, nearly 50 or 60 batteries have been burned by SAIC only through the thermal runaway management test, and according to the current technical state of E 1, the worst thermal runaway performance can last for about 40 minutes without diffusion.
In order to realize the design of integral cast aluminum tray, SAIC has spent a lot of energy, and has successively developed friction welding technology and high pressure die casting technology of extruded aluminum plus stirring rod. However, neither of these two technologies can realize the integral molding of the tray. In the end, the joint supplier of SAIC realized the integral molding of the cast aluminum pallet by studying the low-pressure casting technology, which not only reduced the cost, but also reduced the weight of 17kg for a single part, which made Mr. Zhu Jun very proud.
However, the next-generation E2 battery, which will be launched in two years, will bring us more surprises. Including the battery capacity will be increased to 100kWh, the energy density will exceed 200Wh/kg, the battery type will be added with new systems besides lithium ferrous phosphate and lithium ternary system, the battery thickness will be greatly reduced compared with the existing products, reaching 1 10mm, and the thermal runaway level will even be controlled at L0 level, that is, almost no diffusion will occur. In addition, the charging speed should be shortened by half. It can be said that the technical index of E2 battery is almost in every item, which greatly exceeds the current technical level.
It is worth mentioning that the cost of the new generation battery has not increased because of the introduction of more advanced technology, but has decreased exponentially. Mr. Zhu Jun told us: "The cost per watt-hour of E0 battery pack usually exceeds 1, which is close to 2; To E 1, it drops to about 9 hairs, and there are also 8 hairs; By E2, it should be about 60 cents. "
Full text summary:
When asked about the advantages of SAIC over other car companies in the three-power system, Mr. Zhu Jun clearly told us: We are pursuing an all-around champion, not a particular point, but the overall strength, just like golf and Camry models, which sell well and are characterized by reliability. In other ways, SAIC is also pursuing such products.
Looking back at the products released by SAIC in the past, we found that it did not follow the product logic that cruising range is king in the market, but exerted its strength in many dimensions such as safety, efficiency and performance, so we saw that Roewe Ei5 with only 35kWh battery capacity used heat pump air conditioning; Marvel Comics with only 53kWh battery capacity? X has three permanent magnet motors and is equipped with an overrunning clutch developed by SAIC to solve the problem of back electromotive force when the vehicle slides. These technical eyes may not have attracted everyone's attention at present, but they have built the technical foundation of SAIC in the field of new energy and greatly optimized E 1 products. When the E2 generation products appear, maybe SAIC's new energy vehicles will accumulate, so we might as well wait and see. (Figure/text? Car home? Hu Yongbin)