/PRCWT/October 17, 2023 Beijing -- 01 giant entered the high-performance tram group and started
Recently, Mercedes-Benz released the first concept model of its MMA platform CLA, its new electric drive unit MB.EDU, the motor, transmission and power electronics module integration,175 kW permanent magnet synchronous motor and 2-speed transmission by a controller unified control, function integration after the electric drive unit weight of less than 110 kg, energy conversion efficiency of up to 93%. At the same time, according to network news, Tesla is preparing to develop a two-speed transmission electric drive assembly. In addition, there are a number of pure electric models equipped with two-speed transmission, such as Porsche Tycan, Lotus Eletre pure electric SUV, and GAC Aeon Hyper, etc., electric vehicles have gradually gathered many strength players on the track of multi-gear.
02 speed ratio is difficult to change the burden of the motor
At present, the penetration rate of new energy vehicles has stabilized more than 30%, when people think that pure electricity has formed a "lift" advantage for traditional fuel vehicles, carefully disassemble the car sales data, it is not difficult to find that pure electricity wants to achieve the flat replacement of traditional fuel but also make a lot of efforts.
The middle and high-end market has become a fortress that is difficult to overcome
According to the passenger car sales data from January to July this year, "Tong Jiren Automobile Review" analysis, from the level point of view, the smaller the size, the faster the decline of fuel vehicles; The larger the size, the harder it is to replace a fuel car.
The fastest decline in fuel vehicles this year is a decline of 25.8% of small SUVs, a decline of 21% of small cars and a decline of 10.7% of compact cars, while medium and large cars, medium and large SUVs, large SUV market fuel vehicles, this year is even growing.
From the price point of view, the lower the price, the faster the decline of fuel vehicles. The high-priced market is still dominated by fuel vehicles.
With the rise in prices, the decline of fuel vehicles is getting smaller and smaller, the sales of fuel vehicles below 100,000 yuan fell by 20% year-on-year, but to more than 300,000 yuan, fuel vehicles began to grow, more than 500,000 yuan fuel vehicles, this year's sales growth even more than 15%.
The vote made by consumers with their feet exposed the distress and weakness of pure trams in occupying the middle and high-end market. At present, there is no new energy vehicle that can prove that it can challenge the fuel luxury benchmark, nor is there any new energy vehicle that can prove that it can become the first choice of the only full-scene transportation vehicle in the family.
Domestic trams have not been able to conquer the traditional automobile power with product force
"Tiger Sniff" recently issued a document that in the first half of this year, China's new energy vehicles exported to Europe about 350,000, accounting for 25% of the total sales of 1.419 million new energy vehicles in Europe during the same period. While the market share looks high, Wu Songquan, senior chief expert of the China Automotive Center and chief engineer of the China Automotive Strategy and Policy Research Center, points out that while China's total auto exports are large, their share in most single markets is relatively small. In addition, the number of Chinese auto brands is large, and compared with Europe, America, South Korea and other multinational brands, has not achieved the same status.
This can be seen from the sales list of China's pure electric vehicles in 14 European countries released by "First Electric" in August this year, even if the domestic electric vehicles have achieved "big sales" in some narrative logic, their brand is still European.
The reason for this is partly due to the "narrow" product positioning of pure electric vehicles made by domestic new energy vehicle enterprises based on the main use scenarios of trams in China at this stage, and China's pure electric vehicle products have failed to meet the performance requirements of Europeans facing more inter-city and even interstate commuting use scenarios. The vast majority of Chinese people commute to and from work within the same city, while Germans face more intercity and even interstate commuting. Taking the microblog content released by the German Embassy in China as an example, 48 percent of the country's office workers live in the suburbs and drive or take trains to the city center to work every day. In large cities such as Dusseldorf, Frankfurt, Munich and Stuttgart, up to 60% of the population lives outside the city.
In such a commuting environment, Germany has many "cut-and-dry" motorways with no speed limit to ensure commuting efficiency. This section of road has great requirements for the reacceleration performance of the vehicle at high speed, and the top speed of the vehicle should be improved accordingly, which is the shortage of electric vehicles today. Therefore, the use of high-performance new energy vehicles with single-stage retarders is only a helpless move after weighing various technical levels under various conditions such as low energy efficiency and highway speed limits. However, the huge defects brought by this trade-off make it difficult for high-end new energy vehicles to break away from the label of "big toys" in public opinion, making it difficult to launch an impact on higher-end application scenarios.
In such a driving scenario, whether the power output of the range above 150 km/h is continuous, whether the body shape is conducive to reducing wind noise, whether the energy reserve of the vehicle in the long distance at high speed can not cause anxiety and other product force indicators are more likely to be perceived and concerned by the driver and passenger, and the product positioning of domestic new energy vehicles is not focused on this.
In Germany, the author of "Tiger Smell" test-drove the NiO EL7(the domestic ES7), which was launched in many European countries last year. In the high speed without speed limit, the maximum speed of this car is limited to 200 km/h, and the acceleration of more than 150 km/h is no longer obvious. You know, the power and speed level of this car on the domestic electric car has belonged to the "ceiling" level.
After driving for a period of time, the power consumption of the vehicle has reached nearly 30kWh. Obviously, if you drive on the A8 and A9, which run through the country and have long distance speed limit sections, the standard 75kWh electric vehicle brings mileage anxiety to users. Based on the domestic definition of domestic electric vehicles under the maximum 120 km/h working condition, German cars have also exposed certain disadvantages in chassis, power and high-speed performance.
03 "Acceleration, maximum speed, endurance"
Tram full scene penetration answers
In the current cultivation and growth stage of the development of new energy vehicles in China, the market focus is biased toward small compact cars and electric models with prices below 300,000 yuan, which are more oriented to the urban commuting market. Oems focus more on improving charging efficiency and on driving unrelated comfort configurations, while strategically ignoring the construction and improvement of powertrain product capabilities that support the fundamental attributes of the vehicle.
Small orders can't support big scenes
Objectively speaking, the single-stage gearbox powertrain scheme which is widely used at this stage is not a perfect scheme.
With the use of a single-stage reducer, the vehicle always maintains the same gear to complete the driving from the start to the maximum speed, the torque output is reduced after the motor reaches a high speed, it is difficult to achieve the best performance, and the re-acceleration ability is greatly weakened. In order to improve vehicle acceleration performance and maximum speed, motor development needs to continuously increase power, and in the motor design and manufacturing process, limited by the application scenario can not increase the volume, so can only continue to increase the motor speed, improve the rotor material and process, resulting in a surge in costs. At the same time, pure electric vehicles in the cruise state, because there is only a fixed transmission ratio, the motor also needs to run at high speed for a long time. According to the typical motor efficiency characteristics, when the motor is running at high speed, it is in the inefficient working range, which will significantly increase the internal power consumption and affect the endurance, and the wide application of flat wire motor makes the skin effect and proximity effect of the motor at high speed more prominent, the motor efficiency decreases significantly, and the space for the high-speed development of the motor is getting smaller and smaller. At the same time, high speed will also bring NVH deterioration, which brings great challenges to motor design.
The electric vehicle with a single-stage reducer is adjusted by the motor speed only under different speed conditions, just like a bicycle without a transmission, and the speed, load and climbing ability of the car are completely dependent on the physical fitness of the rider. At this stage, China has solved the problem of electric vehicles, paying attention to small scenes of urban commuting, like the short-distance commuting scene of shared bicycles in the subway to the door, and in order to accelerate penetration in the deep development stage, and become an option for family full-scene travel tools, it is also necessary to work on power, speed, and endurance, just like long-distance riding and road racing use scenarios, shared bicycles show However, it is difficult to be competent, or to carry the mountain bike with variable speed function.
The two-speed electric drive system is the lever used in the whole scene
For pure electric vehicles pursuing high performance, equipped with a two-speed transmission will bring considerable performance improvement. Taking the simulation model established by AVL-Cruise software by a university team as an example, a pure electric commercial vehicle model was established by analyzing and considering realistic factors and matching parameters, and the simulation was carried out through the simulation software. The results show that, 0-30 km/h acceleration time increased by 14.4%,0-100 km/h acceleration time increased by 2.33%, the maximum speed increased by 16%; Maximum climb increased by 22.2%; In C-WTVC conditions, driving range increased by 9.5%.
Similar simulation experiments have also been applied to passenger vehicles. Through simulation results, it is found that when using a two-speed transmission, the acceleration performance of 100km is increased by 3%, the acceleration performance of 0-60km/h is increased by 15%, the maximum climb is increased by more than 17%, and the maximum speed is increased by nearly 18%. As for power consumption, the simulation power consumption decreased significantly under different working conditions, the power consumption decreased by 8.39% under FTP working condition, and the energy saving level under high-speed working condition was significantly improved compared with that under comprehensive working condition.
It is obvious that the blessing of the two-speed electric drive makes the tram gain significantly in power, speed and endurance, and gives the driver more confidence to calmly cope with the use of the whole scene.
The dilemma of autonomous car companies
There are a lot of benefits of two-speed electric drive, but the application is mostly foreign brands, there may be two reasons.
In such an internal environment, cost reduction has become the only goal of car companies, and the addition of two gears will inevitably increase the cost of parts and increase the difficulty of calculation for car companies' decision-making. There is never only income without investment in the world, but not in order to reduce the cost, the key to make a balance, to see whether the investment of new technology can bring considerable benefits for the product, for the user, for the enterprise, and the two to join, in the vehicle performance, the use of scenarios to broaden, battery costs have significantly improved, only the battery cost of one that has thousands of dollars to save, this account is not difficult to calculate.
More importantly, it may be because the current motor + single reduction technology has created a comfort circle for autonomous car companies that has never been in the era of oil vehicles, for a long time, of course, the lack of courage to actively break the circle, the two-speed transmission is not our strong point, the shadow of the transmission technology in the era of oil vehicles is suppressed by foreign investment, so that we still lack confidence in the era of technology breakthrough, why not in the low technical threshold The field eats the dividends of scale advantage.
Trams are cars too.
There are a lot of concepts in today's automotive industry, such as networking, intelligent cockpit, software-defined cars, etc., but they should not be separated from the fundamental attributes of the car, carrying refrigerators, color TVS, and big sofas should be the power system of the car.
Since the invention of the automobile, it has profoundly changed the travel logic of human beings and greatly expanded the travel scope of human beings. At the same time, people's continuous pursuit of automobile technology shows that human beings have broken through the limitations of nature step by step and explored in a faster and farther direction. In the era of electric vehicles, human beings will not give up this exploration and pursuit, and creating a two-speed electric drive system with stronger product force may be one of the great directions, and then, it depends on who is more charismatic.
