Bitauto Original In the past two years, domestic car companies have basically increased their presence in the hybrid market, and technical routes are also blooming. In the plug-in field alone, there have been products such as BYD DM-i, Geely Thor Hi·X, and Great Wall Lemon DHT. , GAC GMC, Chery C-DM and other solutions, from single motor to multiple motors, from single gear to multiple gears, each brand basically has its own set of signature technologies.
As one of the earliest domestic car companies to deploy hybrids, Roewe launched the plug-in hybrid Roewe e550 as early as 2013, which was equipped with SAIC's first-generation EDU hybrid system. Since then, it has successively iterated the second-generation 10-speed EDU, third generation EDU G2 Plus. But compared with later BYD, Geely and other brands, SAIC's hybrid products have always been smaller in volume and size. Now, SAIC seems to be awakening and making efforts in this field again, launching the latest iterated hybrid technology - DMH super hybrid system. The first model is the Roewe D7.
So how is this DMH system different from the previous three generations of systems? Is the Roewe D7 competitive compared to BYD Qin PLUS DM-i?
Evolutionary history of SAIC EDU: multi-speed→single-speed
In 2013, SAIC Group obtained patents related to the first-generation EDU electric drive system and mass-produced it on the Roewe e550. Its hybrid system uses P1+P2 dual motors and a 2-speed transmission mechanism. This car is also China's first Mass production of plug-in hybrid cars.
In 2019, SAIC began to apply the second-generation EDU hybrid system, which removed the P1 motor and adopted a single-motor lateral layout, a parallel shaft layout, and a dual-input shaft alternating shifting DHT structure, that is, a 6-speed transmission was added to the engine end box, and then give the motor 4 different speed ratios, finally achieving a total of 10 gears of "6+4", becoming the world's only 10-speed EDU intelligent electric drive transmission.
In 2020, SAIC will iterate to the upgraded hybrid system EDU G2 Plus, which will be installed on the third-generation Roewe eRX5 and other models. It is also 10 gears, but the gear structure has changed from "6+4" to "2×5", that is, the 5th gear of the engine end gearbox is multiplied by the 2nd gear of the motor end. This structure is theoretically shorter in overall length and more conducive to layout.
In 2023, this technology will continue to be upgraded, simplifying the complex, eliminating the unnecessary and retaining the essential, iterating into today's SAIC new DMH super hybrid system, P1+P3 dual motor single-speed direct drive, and first used in the Roewe D7 on DMH.
Single-speed DHT P1+P3 dual motor
Strictly speaking, DMH is SAIC’s fourth-generation hybrid system, but it has little connection with the previous three generations. From the structure, it can be seen that this hybrid system uses dual motors that are currently mainstream in the market. The hybrid topology is a single-speed direct drive mechanism with P1+P3 dual motors. Compared with those 2-speed DHT, 3-speed DHT or even 4-speed DHT, SAIC is doing subtraction. The advantage is that the structure is simpler and more compact. .
There are many "ingenious ideas" in the design of this DHT gearbox. First of all, the P1 motor is coaxial with the engine. Compared with the parallel axis arrangement, there is one less set of gears. The transmission efficiency is higher and the operation is smoother. The NVH performance is improved by more than 10% compared to products of the same category with parallel axis. At the same time, the size is smaller and the product is lighter.
In addition, its C1 clutch is nested inside the P1 motor, which is highly integrated. The overall structure will be more compact, the end windings are short, the axial length of the assembly is shortened by more than 10% compared to the hair-pin motor, and the continuous power can be It reaches 80% of the peak power, which is much higher than the 60% level of oil-cooled flat wire motors in the industry, and the cooling efficiency is increased by 30%.
As for the P3 motor, it adopts a high-efficiency direct-injection oil-cooled hair-pin flat wire winding design, with a maximum power of 150kW, a peak torque of 330N·m, and a motor mass power density of 6.1kW/kg. The official data is The maximum efficiency reaches 97.5%, and the WLTC comprehensive efficiency reaches over 90%.
In addition, the heat dissipation efficiency of the motor often directly affects the output power of the motor. SAIC DMH's P3 motor uses self-adjusting mechanical + electronic dual oil pump cooling, while BYD Qin PLUS DM-i only has one mechanical oil pump. The cooling capacity of their mechanical oil pump increases with vehicle speed, up to 15Lpm. However, the Roewe D7 has an additional electronic oil pump. The maximum starting cooling flow can reach 12Lpm, which can achieve precise control of the cooling oil output throughout the entire period. The independent adjustment is more fuel-efficient and has better continuous performance.
So in summary, although they are both single-speed DHTs, compared to BYD Qin PLUS DM-i's gearbox, SAIC's DHT is smaller in size and lighter in weight, but has higher output power and integration. The mechanical transmission efficiency has also reached 98.5%.
Five-in-one PICU controller
In terms of control, this DMH hybrid system uses the highly integrated powertrain brain PICU, which is a "five-in-one" of motor control, engine control, hybrid transmission control, air conditioning thermal management and battery thermal management. Here, SAIC has proposed a concept of "energy domain", which allows energy management to flow within the same domain to achieve "variable sharing" and improve response speed.
Thanks to the powertrain brain PICU, the network load and data delay in the car can be greatly reduced, and the computing speed is increased by 50%. The power response time of the Roewe D7 DMH is only 0.26 seconds, making overtaking faster when speeding up.
At the same time this designThe solution also saves 70% of redundant components. Judging from the components displayed on site, the volume is indeed much smaller than previous generations of products.
Roewe D7 DMH vs. Qin PLUS DM-i
Currently, there is no actual car test drive of the Roewe D7 DMH. Regardless of price, configuration, experience and other factors, we only make a simple comparison based on some parameter information.
In terms of size, the Roewe D7 is between the Qin PLUS DM-i and the Han DM-i, and is positioned as a mid-size car.
In terms of power, Roewe D7 DMH and BYD Qin PLUS DM-i are both equipped with 1.5L hybrid special engines, and Roewe D7 takes the lead in terms of performance parameters. It is worth mentioning that the D7 engine adopts a high tumble ratio port and compact combustion chamber design to improve combustion efficiency, and adopts piston/cylinder bore, crankshaft system, valve mechanism, chain system, lubrication system and accessory systems. It implemented 18 friction-reducing technologies and finally achieved a thermal efficiency of 43%.
In addition, in terms of the core battery, the Roewe D7 is equipped with a battery capacity of 21.4kWh. The official pure electric range is 125km, and the CLTC comprehensive cruising range on full fuel and full charge is as high as 1,400km.
In comparison, the BYD Qinqin PLUS DM-i long-range version is equipped with a battery capacity of 18.3kWh, a pure electric range of 120km, and a maximum range of 1,245km on a full charge.
Roewe D7 DAlthough the body size and curb weight of MH are higher than BYD Qin PLUS DM-i, MH still has a slight advantage in engine power, motor power, and pure electric cruising range, and the cruising range on full fuel and full electric power can open up a sufficient gap.
In addition, judging from some current signs, the Roewe D7 is mainly targeting BYD Qin PLUS DM-i, and it is not ruled out that it may overlap with the latter in terms of price. Of course, the most direct competitor may still be Geely Galaxy L6. In any case, it will definitely occupy the latecomer advantage, and its comprehensive product strength is still very strong.
Editor’s summary: From the first generation EDU in 2013 to DMH in 2023, SAIC’s ten-year technology upgrade path is also a microcosm of domestic car companies’ exploration of hybrid technology solutions. At present, the P1+P3 motor structure has become the first choice of most car companies, simply because the core components of this solution are more integrated, and the motor power can be made higher, which can better balance fuel economy. Balance between sex and performance. As for which set of DHT single gear or multi-speed, parallel axis and planetary gear should be used, it depends on the car company's technical patents, product planning, cost factors and user experience. We are not superstitious about multi-speed, nor do we deny multi-axis. The beholder has different opinions and the wise have different opinions. Smart, let product experience speak for itself, just wait and see the actual car experience of Roewe D7 DMH.
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