In the previous part, we talked about the current choice of first-line Chinese brands in the insertion and mixing technology route (review please poke "The world of insertion and mixing is not so complicated (Part 1): Mainstream PHEV technical route analysis"), a simple summary is that most brands have chosen the DHT scheme of dual motor control, while Changan iDD has chosen a dead single motor, ANDD DM-i directly abandons the variable speed structure to use single-speed drive, which is also the most mainstream plug-and-mix solution used in the hybrid models we can buy at present.
These different technical routes point to the same component - hybrid engines. Every time a manufacturer publicizes how good its hybrid engine is, someone will always ask what is the "hybrid special"? How is it different from a conventional fuel vehicle engine? Does specialization have a big impact on the hybrid system?
The answer, of course, is that there is a difference between the two, and it is not small. In order to let everyone understand PHEV technology more intuitively, this issue will analyze where the hybrid special engine is "specialized"?
After a brief analysis of the previous issue, I believe that this content will be easier to understand. At the same time, in order to bring into the actual car selection environment, I will also talk about issues such as "for people with different driving styles, how to choose the insertion and mixing system", "under different working conditions, the logic of choosing PHEV" and so on.
How about a special method?
Before understanding the hybrid engine, it should be clear that the engine is only an integral part of the PHEV system, and it cannot be viewed separately from the entire hybrid system.
The so-called hybrid special engine refers to nothing more than an engine dedicated to the service of this plug-in and hybrid system, which is detached from the important attributes of being the only power source.
As mentioned in the technical route of the previous part, when the system is in series mode, the engine can be used as a range extender, only generating electricity and not participating in driving the wheels. In this case, the power we feel when driving has nothing to do with the engine speed and output torque, so the engine will be kept in the highest thermal efficiency speed range as much as possible, which is also the first purpose of the hybrid special engine designed: high thermal efficiency.
Thermal efficiency has always been the bottleneck in the development of internal combustion engine technology, and the thermal efficiency of engines on the market today is mostly between 36% and 40%. On this basis, it is quite difficult to increase by another 1% unless the way the engine is circulated is changed.
At present, most of the traditional fuel vehicles adopt the Otto cycle, that is, the compression ratio is equal to the expansion ratio of the cycle. To further improve thermal efficiency, the most significant way is to adopt a compression ratio less than the expansion ratio, that is, the work stroke is greater than the compression stroke. This is also the most basic principle of the Miller cycle and the Atkinson cycle, the difference between the two is that the implementation method is different, and it will not be introduced in detail here.
At present, the highest thermal efficiency of the "Energy Star" certified mass production hybrid special engine is 43.32%, code-named DHE15, using Miller cycle, installed in the Geely Star-more L Hi · X on. It was followed by a BYD Snap Cloud Hybrid 1.5L engine with an Atkinson cycle, with a thermal efficiency of 43.04%.
Speaking of this, some people may wonder, since the Miller cycle and the Atkinson cycle can achieve higher thermal efficiency, why is the traditional engine still dominated by the Otto cycle? This is because in order to achieve a compression ratio that is less than the expansion ratio, the design of the gas distribution mechanism will be much more complicated, and the maximum speed limit of the engine will be relatively large. What's more, the Miller cycle and the Atkinson cycle have a much weaker low twist. Therefore, the motor + Miller/Atkinson cycle has become an excellent combination of efficiency and is widely used in hybrid special engines.
The second feature of the hybrid special engine, that is, the elimination of conventional mechanical accessories, is replaced by an electronic structure.
Riders who know something about the engine should know that conventional engines will drive their attached generators, pumps, compressors and other accessories through the belt, and these accessories have a large impact on the power of the engine when working, especially for small displacement engines. At present, the mainstream hybrid special engines have changed these auxiliary functions to electronic structures, so that all the power of the engine no longer has other uses other than output power and power generation, and the efficiency is naturally higher than that of traditional engines.
In a nutshell, due to the addition of other power output sources to a plug-in system, the plug-and-mix special engine has unloaded a lot of baggage. While lightly loading, it also creates the "most comfortable office environment", because the control logic of most hybrid systems will allow the engine to run directly in a relatively efficient range, avoiding idle speed, low rotation and other working conditions.
On the other hand, if a plug-in special engine is not modified, it cannot be installed separately on a traditional fuel vehicle to work normally.
PHEV Car Buying Manual
After talking about the plug-in mixing technology and the hybrid special engine, basically the content of the "power system" of plug-and-mix is shared. The remaining power battery pack and some details are placed in the following selection and recommendation section, combined with the characteristics of different PHEV, to talk about what conditions they are most suitable for.
Every friend who has paid attention to PHEV is believed to have been moved by its "oilable and electric" characteristics. Urban electricity and long-distance oil use perfectly solve the problem of high oil prices and difficult charging. At present, most of the listed PHEV models have basically reached the threshold of 100km of pure electric endurance, chery Kunpeng DHT and Geely Thor Hi · X will also have a plug-in hybrid model with a 200km pure electric endurance at the end of the year. Considering the sharp increase in raw material prices, it is estimated that the pricing of models will be much more expensive than that of the listed models.
If your car environment is mainly based on the city, buying PHEV is to avoid battery life anxiety at the same time, maximize the feeling of the "electric drive" characteristics, then the big battery is forever dripping God!
It should be noted that although BYD's blade battery is extremely safe and the performance in the puncture experiment is very stable, it is not perfect. The characteristics of lithium iron phosphate batteries are destined to attenuate more than ternary lithium batteries at low temperatures, so the discount on winter battery life will be more obvious than that of other players who use ternary lithium batteries. Coupled with BYD's general SOC setting at 25%, the pure electric mileage available in the northern winter is only about 50km.
The use of "large capacity + ternary lithium battery" combination of Changan UNI-K iDD is obviously more suitable for this type of car environment, and Changan has made a series of measures for the low temperature environment, making full use of the advantages of large-capacity batteries, after reaching the critical point through power consumption insulation and other ways to make its working environment reach -35 ° C, it is still very practical in the north.
If you buy a PHEV just for a green card, there is no charging conditions and no pure electric preference, and the most cost-effective model is the 50+km pure electric endurance version of the BYD DM-i series.
For example, Song PLUS DM-i, Qin PLUS DM-i and other models have 50+km pure electric endurance version, because the current price increases of upstream manufacturers have led to different degrees of increase in new energy vehicles, and the price increase of low-capacity battery versions is the least obvious. For example, the Qin PLUS DM-i 55km endurance version starts at only 111,800 yuan, and the fuel consumption is only 3.8L/100km, and the cost performance is outstanding.
Upcoming Geely Emgrand L Hi · X is actually not weaker than Qin PLUS DM-i in terms of fuel consumption, endurance and performance, but considering its pure electric endurance of 100km, it is estimated that the cost will not be lower than that of Qin PLUS DM-i. As for the PK result between the two cars, it also depends on the final Emgrand L Hi · X price.
If your car environment occupies more than half of the proportion of high-speed, the choice of PHEV is to reduce the cost of use, then the use of hybrid special engines with T and multi-gear DHT will be more appropriate, among them, Chery Kunpeng DHT and Geely Raytheon Hi · X is a good choice.
Named after Emgrand L Hi · X, for example, the structure of the 3-speed DHT allows the engine to revve at lower speeds at high speeds, and the NVH and fuel consumption performance are better. Secondly, Geely's 1.5T engine, code-named BHE15, is inherently more powerful than many 1.5L engines at the same price, and the re-acceleration capability during cruising will be better.
If you buy PHEV to experience high performance, then there is currently only BYD Han DM-p to choose from, go and see the upcoming Han DM-p!
Master observation
Perhaps, the internal combustion engine will eventually disappear in the future, but there will be a decades-long overlap between the beginning of the pure electric era and the end of the fuel era. Not to mention the car, even Nokia, the hegemon of the feature phone era replaced by Apple Samsung, did not disappear overnight, and the reason is not something that can be summarized in one or two sentences.
So how will this be replaced, and how will this time affect everyone's travel? Exploring this process is actually quite interesting. From the perspective of these independent car companies that have invested aggressively, made all-out efforts to transform, and do not hesitate to create new brands to do plug-in, PHEV is the direction they think is relatively suitable. And today, in 2022, everyone has also given a fairly good solution.
However, the right choice to consider in the right environment, phEV is suitable for whom? Which car environment maximizes the characteristics of PHEV? Do people who buy PHEV have anything in common? On these topics, I hope that in the future, I can find some OWNERS of PHEV models who have purchased and have a certain experience of use, and after I have real communication with them, I will share them with you one by one.