Great Wall tore Huawei apart like an assassin who wanted to kill the extended range

It is human nature to eat melons, especially to watch the big guys fighting each other.

The background of the story is very straightforward: Yu Chengdong took advantage of the launch of the new car of Wenjie to claim that "extended-range vehicles" are the most suitable new energy model at present, and called for "eliminating fuel vehicles as soon as possible." At the same time, he posted a Weibo praising Ideal, the domestic pioneer of extended-range hybrid vehicles, and Li Xiang reposted it and responded with a business heart.

The one who couldn't stand it anymore was Li Ruifeng, CEO of WEY, a subsidiary of Great Wall Motors. He bluntly stated that "it is an industry consensus that extended-range hybrid technology is backward", and that the DHT series-parallel hybrid technology that the company promotes is the "world's best" hybrid technology.

As soon as the big guys opened their mouths, the big Vs ran around, and all the KOLs seemed to have made an appointment and entered their respective roles...

Yu Chengdong is well-known in the industry for his "big mouth", and the sudden outburst of Great Wall, a traditional independent car company, is somewhat unexpected. It turns out that these days, not only cubicle workers, but also CEOs need to be able to argue and fight to be the primary productivity. The joys and sorrows of the contemporary workplace are actually connected at this moment...

Whether it is Yu Chengdong's "appeal" that is so full of advertising flavor, or Li Ruifeng's undisguised "tearing" that is well prepared, it is not difficult for friends with a good sense of the Internet to see that the proactive marketing attributes of this matter far outweigh the technical debate.

The big guys are fighting each other, but that doesn't stop us from picking what we want to see. So, ignoring the verbal attacks from both sides, and only considering the two hybrid technology routes of extended-range and DHT, is it really the "industry consensus" as Weipai CEO Li Ruifeng said: extended-range hybrid is backward, while DHT hybrid is more advanced?

YES and NO. Yes, but no.

Extended range and DHT, only one dollar difference

Extended-range hybrid is easy to understand: the fuel engine is used as a range extender only to generate electricity, and the electricity can be used directly to drive the wheels, or it can be stored in the battery first and then supplied to the motor when needed. Because the fuel engine is always upstream of the motor in this path, the oil and electricity are relayed in a "one-line" manner, so it is also called series hybrid.

This hybrid mode, which was once regarded as "taking off pants to fart", was originally intended to decouple the wheel speed from the internal combustion engine speed. The internal combustion engine speed no longer has to jump up and down with the vehicle's stopping and starting. The internal combustion engine can operate in the high-efficiency range as much as possible, thereby improving efficiency and reducing energy consumption.

Nissan explains e-POWER extended-range technology, with operating points more concentrated in the high-efficiency zone, source watermark

Series-parallel DHT is a type of DHT hybrid and is also the most popular DHT hybrid route at present. Its source is Honda i-MMD. Series-parallel DHT can switch the engine and motor between series and parallel by opening and closing a clutch.

As shown in the figure below, in the center hybrid mode state, the clutch is disconnected, the engine is used to generate electricity and supply power to the motor to drive the wheels, which is no different from a series-range extended-range hybrid; in the right engine drive state, the clutch is closed, the engine power and the motor power are combined to drive the wheels, and the two are in parallel.

This is the i-MMD series-parallel connection. Cut off the rightmost part to get the extended range.

In fact, the reason why i-MMD was so groundbreaking was that Honda was the first to introduce the series working mode with the help of a clutch in a world full of parallel hybrids. That is, the originality of i-MMD at that time was to add "range extension" as a working mode to the hybrid system.

So when Ideal ONE was first launched, many Honda fans who were familiar with i-MMD exclaimed that it looked familiar. The final products of the two are very different: one is a super-large battery PHEV, and the other is a HEV (the main push at the time); one is a series-connected extended-range type, and the other is a series-parallel DHT, but some of the internal principles are indeed the same.

If we make a change to a series-parallel hybrid like the i-MMD, cut off the mechanical connection structure between the engine and the wheels (or even just keep the clutch open forever), abandon the ability of the engine and motor to drive the wheels together in parallel mode, and use the engine only for power generation, that is, as a range extender - abandoning the possibility of direct fuel drive, what we get is a series, extended-range hybrid.

i-MMD introduces PHEV version with large battery

As for the battery size, it can actually be ignored. Extended-range hybrid can also develop into HEV with a small battery, but there are very few cases, such as Nissan e-POWER; and series-parallel DHT hybrid has always been applicable to both HEV and PHEV. For example, Honda focused on HEV in the early years, and in recent years it has also launched a large-battery PHEV based on i-MMD, not to mention today's domestic brands of DHT-HEV and DHT-PHEV.

Honda pioneered the series-parallel DHT, and almost all domestic automakers have adopted it in the past two years. In addition to Great Wall Group's Lemon Hybrid DHT, there are BYD DM-i, Geely Thor Hi·X, Chery Kunpeng DHT, Dongfeng Mach DHT, GAC GMC2.0, etc.

Therefore, we don’t need to judge heroes by success or failure, and we can’t underestimate the series-parallel DHT technology itself just because of the high or low sales of some products. Even if we only look at the results, BYD DM-i, which has really good sales in the same camp, is also a good choice.

The structure of DHT can be varied

Due to the need to choose technology and avoid patents, the DHT technologies of the above-mentioned independent brands are different, and some even "infiltrate" part of Toyota's power diversion ideas (Geely). But in general, the core principle is based on the series-parallel DHT similar to i-MMD, and the main difference is the number and implementation method of direct drive gears.

For example, the Great Wall Lemon DHT has added a two-speed direct drive structure, the Geely Thor Hi·X DHT Pro uses two sets of planetary gear sets to achieve three gears, the Chery Kunpeng DHT has achieved the so-called "9 modes and 11 speeds" with a similar 3-speed DCT structure, and the BYD DM-i is a fundamentalist single-speed series-parallel. If you are interested, you may jump to "Just to get better, the DHT universe is going crazy".

Compared with extended-range hybrids, these DHT hybrids can firstly use the internal combustion engine to directly drive the wheels, and some even use mechanical gears to allow multiple gears when driving purely electric. Even compared with the simplest single-gear direct-drive members, Honda i-MMD and BYD DM-i, extended-range hybrids lack a clutch and corresponding direct-drive capability.

If we only judge by the "more or less" of the system, the extended-range hybrid is obviously "lagging behind" the series-parallel DHT hybrid. This is probably the source of Li Ruifeng's determination of "industry consensus".

Whether there is direct drive or not is determined by the buttocks

The debate is naturally not so easy to end.

Rather than saying that the extended-range hybrid is "backward" than the DHT, it is better to say that the extended-range hybrid is more "simplified" than the DHT - and simplicity does not necessarily mean backwardness. Compared with the simplest single-gear system in the series-parallel DHT, the key thing that the extended-range hybrid lacks is direct drive capability.

i-MMD's "extended range" mode, with gray representing the direct drive portion

The reason for supporting the retention of direct drive capability is related to the operating characteristics of the internal combustion engine. As we all know, the most economical operating condition for fuel vehicles is to drive at a constant speed at medium or high speed. At this time, the internal combustion engine operates in the highest efficiency range, and the efficiency advantage of the electric motor over the internal combustion engine is the smallest.

At the same time, for extended-range hybrid (and DHT series mode), the mechanical energy of the internal combustion engine needs to be converted into electrical energy first, and then converted back into mechanical energy of the wheels by the electric motor. Compared with the internal combustion engine driving the wheels directly, this will bring an additional energy conversion loss of single digit percent (Ideal ONE once gave no more than 10%).

Based on factors such as cost, volume and weight, large-scale extended-range models such as Ideal often choose small-displacement range extenders. Since the optimal energy consumption area of ​​the internal combustion engine is directly related to the exhaust volume, the power required for high-speed cruising of these large vehicles may exceed the power provided by the high-efficiency range of the small-displacement range extender. In other words, the higher the speed of the vehicle, the more likely it is to deviate from the high-efficiency zone by relying solely on the range extender for power generation.

When these multiple factors are combined, when the vehicle tends to be stable at high-speed cruising, the efficiency advantage of electric motors over internal combustion engines is not so significant. When Ideal ONE was released in 2019, Ideal admitted that compared with the same level of fuel vehicles, its fuel consumption at high speeds is no longer as advantageous as at low speeds. Later, the reputation of real car owners also proved this.