It's time to talk about domestic hybrid systems. With BYD's DM-i super hybrid, the Great Wall's lemon DHT hybrid, Geely's Thor hybrid, Chery's Kunpeng hybrid, etc., various names are flying all over the world, and domestic first-line car companies have their own hybrid systems, so what differences do they have before, who has more advantages in the technical route, and who can roll out from the perspective of mass production? This article will give you a concise summary.
Hybrid technology route:
From a hundred flowers to DHT unification
The determination of Chinese independent car companies to break through hybrid technology has a long history, and the earliest can be traced back to 2006, WHEND set up a pre-research project for BYD's S6 hybrid project.
As early as sixteen years ago, Wang Chuanfu believed that the charging infrastructure required for pure electric vehicles was still too far away, so the intermediate transition period could be replaced by "electric vehicles with generators", and the earliest product was the BYD F3DM launched in 2008.
However, due to the fine tuning ability of BYD's backward engine and hybrid system at that time, this system did not have amazing results in power and fuel consumption, so the low-level but high-cost "bucket car" did not get the recognition of the market, but the failure of the market did not mean that the attempt was meaningless.
After a long time, the research and development of domestic hybrid technology has almost stagnated. It was not until Toyota's domestic THS launched the offensive and ferocious "double engine" marketing that the hybrid was able to return to the vision of domestic consumers. However, in addition to Toyota, GM, Ford, and Honda all launched hybrid models around 2014, but due to the low localization rate, sales have basically not improved. However, at this time, independent brands hope to achieve cornering overtaking at the level of hybrid technology.
Geely began to cooperate with Corun in 2014 to establish CHS to develop "China Hybrid", which is similar to Toyota's THS hybrid system. However, due to cost and patent reasons, the CHS hybrid system has progressed slowly, and it will not be loaded until 2018, but at that time, Geely and Volvo P2.5 plug-in hybrid technology has already made breakthroughs.
Around 2013, there was also an independent car company that had a breakthrough in hybrid technology, that is, the first generation of EDU system developed by SAIC. However, this two-motor, two-speed AMT hybrid system did not start to be loaded until 2018, but it encountered the same problem as Geely, and everyone felt that the P2 architecture was the trend.
In fact, the plug-in hybrid model of the P2 architecture is probably considered to be a new energy trend in the European and American markets around 2015. Compared with the THS system, the biggest advantage of the P2 architecture is that it is compatible with the traditional internal combustion engine powertrain, especially the DCT gearbox can continue to be used with slight improvements, and the scale effect is very good. Another advantage is that for the German market with unlimited speed highways, the power performance of the P2 architecture is far more advantageous than that of toyota THS.
In addition, there is another reason that European and American car companies want to find ways to bypass Toyota's THS technology patents, and the P2 architecture is the most convenient.
In the same period, BYD's DM dual-mode hybrid came to the second generation, and also chose a plug-and-mix system similar to the European and American route. In 2015, the second generation of DM based on the P3 architecture was launched, which was applied to qin, Tang and other models, and later iterated out the third generation DM system. It is said that the reason why BYD chose the P3 architecture instead of the P2 architecture is mainly because the P2 architecture needs to put the small motor inside the gearbox, but BYD's motor power is large and the structure is also large, so it is placed externally.
The new powertrain of 1.5TD+7DCT jointly developed by Geely and Volvo has derived P2 architecture plug-in and hybrid technology, and is also preparing to make a small battery version of the HEV model. SAIC is also approaching the time – probably in 2019 – to launch a second-generation EDU, using a 6AMT transmission structure plus a 4-speed motor for a more efficient power combination.
There is also a Great Wall Motor in the WEY special launch of the P8 model, which is a P0 + P4 architecture PHEV, is a very simple structure, Schaeffler for the rear-drive motor to provide two-speed reducer. Similar structures are also bmw X1 PHEV, which are electrically powered and dragged by an engine tow a two-ton body when there is no electricity.
In contrast, the P2 architecture is indeed more efficient than these.
Just when everyone thought that P2/P3 was going to dominate the world, the turn of events happened after Honda launched the i-MMD. The i-MMD, a simple and efficient hybrid system, was first successful in the North American market in 2015, and Honda quickly iterated the i-MMD to the second generation.
Compared with the single motor of the P2/P3 architecture, the biggest feature of the Honda i-MMD system is that it has a generator and a drive motor, and the engine can also drive the vehicle directly at high speed. In this way, i-MMD solves the problem of low power generation efficiency of P2/P3 architecture, and does not require a gearbox, the cost is greatly reduced, the only drawback is that the high-speed performance is not so good, but it is still more powerful than THS.
After that, Chinese car companies recognized that DHT dual-motor hybrid system should be the general trend of the future. Therefore, in the period from 2015 to 2018, most of the independent brands have begun to develop DHT powertrain, and the first to bear the brunt of it is naturally BYD.
Thanks to F3DM's R&D experience – the original DM was essentially a two-motor hybrid – BYD quickly chose the DHT route and then set several core breakthroughs: high-thermally efficient engines, high-power motors, blade batteries, etc. These core technologies make up the DM-i super hybrid and are brought to market faster than several other autonomous car companies.
Great Wall Motors soon came up with its own DHT hybrid system, Lemon Hybrid DHT. Similarly, the Lemon DHT also has a high thermal efficiency engine, dual motors, battery packs, etc., but there is an additional set of two-stop fixed-shaft transmissions.
Next is the Chery Kunpeng hybrid system, which is also a dual-motor structure, also a high-thermal efficiency engine, the difference is that its gearbox is more complex.
Finally, Geely's Thor Power. Completely different from the previous P2.5 route, this time Geely also returned to the DHT technology route. However, the previous 1.5TD engine was chosen, and the dual motors were also integrated on a three-stop planetary gear, further increasing the complexity.
In addition, including Dongfeng, FAW, etc. have their own DHT systems, but they have not yet been fully mass-produced, and the technical route and performance are estimated to be close to the above car companies, just to see how high the depth of self-research is.
Of course, there are also some car companies that have not fully shown their cards. For example, GAC, the current hybrid technology route is to get toyota THS, and also reserve DHT technology, including DHE hybrid engine and DHT hybrid special gearbox under the Julang power platform.
There is also Changan, an independent brand that has invested heavily in pure electric vehicle models, but has not made much achievements in hybridization, and currently only has the Blue Whale iDD hybrid system based on the P2 architecture.
In addition, there are now car companies including Ideal and Lantu that have re-launched the range extender hybrid - this technology was first F3DM, and then put on the VELITE 5 by SAIC GM - but compared to DHT, no engine direct drive is always the short board of the extended range. In simple terms, dhT itself also covers the technical scope of range extenders, but the range extension cannot achieve DHT's lower fuel consumption at high speeds.
Range extender hybrid is now mainly defined as a "pure electric drive without anxiety" product, and the biggest difference between it and the DHT model is that it has a larger battery pack and longer cruising range, and the product setting is closer to pure tram.
However, it is believed that as DHT begins to increase the size of large battery packs and improve pure electric endurance, the extender hybrid technology is still relatively inefficient compared to DHT. This should also be an important reason why independent car companies are more willing to bet on DHT rather than extend the range.
Hybrid technology, who leads the way?
Although independent car companies have invariably chosen DHT technology, each car company has different specific technologies. Coupled with the existence of Changan and GAC, which choose P2 and THS alternatives, which hybrid technology has more advantages?
First, let's look at Changan's P2 and GAC's THS, two alternative routes.
As mentioned earlier, the P2's main advantage is that it has excellent performance, can support high-speed cruising, and both the engine and 6DCT can be used in fuel models. But what is more interesting about Changan UNI-K iDD is that Changan chooses to use a large-capacity battery pack of about 30kWh, and the pure electric mileage is only 130 kilometers, while the 30kWh battery pack of others can do more than 200 kilometers.
So what is the excess power used for? In fact, it is because the P2 architecture consumes energy in the feed state, especially when driving on urban roads, it is equivalent to a small engine dragging a large battery, so that the fuel consumption cannot go down. Therefore, Changan has thought of a way to keep the battery pack at a relatively high level of power, such as 40%-50%, which is far stronger than the general P2 retention of 20% - just tell you on the table that the battery life may only be about 130 kilometers and has been used up.
In this way, driving on urban roads can always be driven by electric motors, reducing fuel consumption while maintaining high-performance output in the feed state.
It can be said that the Changan iDD hybrid system is to use the battery capacity to solve the shortcomings of the low efficiency of the P2 architecture feed, but it needs to increase the battery capacity by almost double, and the cost is still very high.
Look at GAC's THS hybrid. GAC chose to cooperate with Toyota on the Trumpchi GS8 this time to introduce the Toyota THS system, but changed the high thermal efficiency self-priming engine to 2.0T. The advantage of this is that the 2.0T's power performance is obviously better, especially when it comes to plateau or long-distance cruises, and the turbocharged engine will be more efficient than the self-priming engine.
But the problem with THS is also obvious, this is a blue model, there is no purchase tax subsidy, and then the system patent is Toyota's, the overall cost is very high. This route may be more pleasing to the Guangdong market, but it may not be advantageous in China as a whole – which is why the position of Toyota THS is gradually being surpassed by the Honda i-MMD, which is more competitive in terms of performance, efficiency and cost. Of course, GAC also has a backup means - DHT technology is also advancing, and even GAC is the first car company in China to hold the extended range technology.
Next, look at the DHT genre, which is basically BYD's single-speed DHT, Great Wall's two-speed DHT, Chery and Geely's three-speed DHT.
If we start from the "Occam Razor" principle - do not add entities if it is not necessary - BYD's DM-i with a single-speed reducer is obviously more reasonable.
But why do Great Wall, Chery, and Geely engage in multi-gear DHT? Perhaps an important reason is that these car companies need to make some differences to show their differences in technical strength and BYD. It's not just a matter of efficiency, it's about being able to distill marketing words at the technical level. Of course, technical engineers also want to challenge some of the higher difficulties.
Is multi-gear DHT really better? The answer is yes, at least in terms of efficiency. It is only said that the little efficiency of the two-speed or three-speed DHT may not be economical when converted into costs, and the engineering difficulty and manufacturing difficulty brought by it are higher.
For example, the Great Wall's two-speed DHT is through two sets of variable speed gears to achieve direct engine drive at different speeds, in order to improve the fuel economy at low and medium speeds. Chery and Geely's DHT is more complex, Chery's three gears are equivalent to using a 3DCT, forming a P2+P2.5 architecture to achieve high efficiency under various working conditions, and Geely is equivalent to using a 3AT to achieve higher efficiency. These multi-gear mechanisms must make the whole system more complex, make the adjustment work more, and even in terms of smoothness, it is far less than the single gear shift.
More critically, the complex multi-gear shifting mechanism is of little significance to Chinese consumers. A 150kW motor itself can cover most working conditions, low-speed can not drive directly or the problem of slight lack of high-speed performance for consumers may be minimal, fuel economy is only 0.5L / 100 km change. But in exchange for higher costs, more complex engineering issues, lower reliability, and a less smooth driving experience.
Therefore, the essence of DHT technology is to pursue a concise system, and the starting point of the multi-gear position itself is good, but the user's point of interest perception is not obvious, and the single-speed DHT system is more likely to be the future.
But another core of DHT technology lies in the development of the internal combustion engine.
Previously, both Toyota and Honda insisted on using naturally aspirated engines as the core of the hybrid, and in essence, self-priming engines are easier to balance in terms of high thermal efficiency and cost.
But then, and perhaps the problem that Japanese car companies do not realize, is that in the vast continent of China, the working conditions in high altitude areas are a very special scene, and the driving efficiency of these self-priming engines in the highland areas can be said to be stretched. Therefore, a more reasonable choice for DHT engines in the Chinese market is a small displacement turbocharged engine.
Whether it is 1.2T or 1.5T, another benefit is that the engine output power can be more controllable than self-priming, which can better meet the needs of large motors.
Taking honda i-MMD to choose a 2.0L engine to match the 135kW motor system as an example, the core reason is that the power generation power of the engine needs to match the motor output power basically, otherwise there may be insufficient power generation, the battery is quickly powered down, and the final power is limited.
If it is a pure 1.5L self-priming engine, then the entire DHT system will obviously encounter more problems. However, at the slightest expense of thermal efficiency and cost, switching to a 1.5T engine, the coupling of the entire system will be better, which is why autonomous car companies have begun to choose small-displacement turbocharging as the engine of DHT.
The third difference is that independent car companies have begun to realize the advantages of large battery packs when developing DHT technology.
The core of the previous Japanese blue hybrid model was the internal combustion engine, and then the use of a small capacity power battery of about 2kWh to achieve high fuel economy in the low-speed stage. This is based on cost considerations, because the cost of batteries was too high ten years ago or even five years ago, and there was no need to increase battery capacity.
However, with the beginning of the Chinese government's subsidies for new energy, PHEV models can initially enjoy subsidies of about 10,000 yuan to cover the cost of more than ten degrees of batteries, and cities like Shanghai, Guangzhou, and Shenzhen also have license policy support. This has greatly enhanced the enthusiasm of car companies to increase battery packs. However, the fact is that although the subsidy threshold for PHEV in the Chinese market is not high, such as pure electric mileage of more than 50 kilometers, consumers have not shown particularly positive purchase interest until the emergence of DHT technology.
The first advantage of DHT use, even in the feed state, can achieve fuel consumption performance of about 5L/100 km, while the previous P2 or other PHEV technology without charging conditions, driving performance and fuel consumption performance in the feed state are difficult to satisfy. This change has allowed BYD Qin PLUS DM-i models to usher in the breakthrough of the first sales bottleneck.
The reason for further making DHT models accepted by consumers is that with the use of large battery packs, the pure electric mileage of DHT models has been greatly improved, coupled with the use of fast charging piles, which further reduces the cost of use and improves the driving experience.
The use of large battery packs first appeared in BYD's DM-i long-endurance models, those about 18kWh battery packs can achieve a pure electric range of 100 kilometers, and allow DC fast charging for power replenishment - BYD designed a special "direct flow AC" conversion head to solve this problem.
Then, more independent brands began to carry 20kWh, or even close to 40kWh battery packs, fast charge is also directly designed on the vehicle, such as mocha DHT-PHEV, Han DM-i and so on. In addition, geely, Lynk & Co and other models also have similar models under development, pure electric mileage aimed at the 200 km level.
And, with the combination of DHT technology and large-capacity battery packs, range extender hybrid technology may soon be replaced.
Previously, the range extender hybrid used a 40kWh battery pack to achieve a pure electric endurance of nearly 200 kilometers, and the experience of using urban roads was close to that of pure electric vehicles, and the fuel consumption on high-speed roads was about 10L - equivalent to the average energy consumption of ordinary fuel vehicles. However, the large battery version of DHT can also easily achieve the former goal, and on high-speed roads, it can use the engine direct drive, making it fuel efficiency about 50% higher than the range increase, which is more efficient.
Driver's Summary
At present, in addition to the rapid development of pure electric vehicles in China's new energy vehicle market, PHEV models will be rapidly increased due to the popularity of DHT technology.
The leading role in the PHEV model will definitely be the SETTING OF DHT+ large-capacity battery pack, and the pure electric mileage will be increased to 100 km to 200 km. In terms of technical details, the engine selection should be based on a small displacement turbocharged engine, and support fast charging, which will greatly enhance the application scenarios of DHT-PHEV models.
Of course, in the various technical routes of DHT, perhaps the single-gear DHT should be the main force covering A-class to B-class models, which is a good balance based on manufacturing costs and efficiency. The multi-speed DHT technology, coupled with the P4 rear-drive motor, may be more suitable for use in C-class high-end cars, as well as B-level SUVs and MPV models, focusing on the balance of better athletic performance and high efficiency, in order to cover the high manufacturing costs of multi-gear DHT.
Therefore, BYD further develops its existing DM-i technology, and Great Wall, Geely, and Chery should subtract from existing technologies and quickly develop single-stop DHT systems is the key to catching up with BYD. In addition, autonomous car companies need to further develop high-thermal efficiency 1.2T and 1.5T engines, preferably four-cylinder.
Text| JackieLXX
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