Text/Civil
In the current three hybrid structures, the tandem mode and the parallel mode have their own advantages and disadvantages, the tandem mode is more efficient in pure electric drive at low speed, but the energy efficiency is not good in the direct drive and hybrid drive of the engine; the direct drive of the engine in parallel mode and the power of the hybrid drive are more surging when driving at high speed, but the engine cannot continue to run in the efficient range, and the fuel economy is greatly reduced.
Then the hybrid hybrid structure that has the advantage of the series parallel structure at the same time came into being, working in series when the car is driving at low speed, using the pure electric drive of the motor; when the high-speed stable driving, it works in parallel, and the engine is directly driven or mixed with the two.
Let's take the hybrid structure of this BYD F3DM as an example, which is old but easy to understand. If you want to achieve the switching of series parallel, you only need to achieve it through the clutch in the figure, if the clutch is disconnected, then the entire power line will become a series mode; if the clutch is engaged, the M1 position is disconnected, then it is a parallel mode.
At the same time, there are also similar to the STRUCTURE of the SAIC EDU hybrid system, which is connected in series and parallel by two clutches, but the basic principles are the same.
Still in terms of BYD F3DM, the working mode of the hybrid hybrid system has the following types:
1. If the power demand of the current driving vehicle can be provided through the efficient range of the engine, then the clutch is engaged to carry out the engine direct drive mode.
2. When the current driving speed of the vehicle is exactly in the efficient speed range of the engine, but the power required by the vehicle is not large (such as downhill and other situations), the clutch is engaged to ensure that the engine runs in the efficient range, and the surplus power is given to the motor of M1 to charge the battery. The M2 motor is not working.
3, when the engine remains in the most efficient range, but the vehicle's power demand is still insufficient (such as acceleration and uphill, etc.), the clutch is engaged, the engine is still running in the most efficient range, if the power demand is larger, it is provided by M1, and the demand is smaller, it is provided by M2.
4. If the engine operating range corresponding to the current speed of the vehicle is not in the most efficient range, then the clutch will be disconnected and converted to series mode, and then the engine will be maintained in the efficient range, and then the M1 power generation will be driven by M2. If the power required to drive the vehicle is less than the power provided by the engine, the battery will be charged at the same time; if the engine provides insufficient power, the battery will join to power the motor.
5. If the current driving speed of the vehicle is high, and the required power cannot be satisfied by the motor alone (such as high speed, overtaking, etc.), the clutch is engaged into parallel mode, and the engine and the two motors provide power for the vehicle at the same time.
6. When driving at low speed, the battery provides electricity to allow the M2 motor to drive the vehicle alone; when the vehicle is stationary, the engine generates electricity to charge the battery.
The advantage of the hybrid hybrid structure is that it combines the advantages of string paralleling, and it is needless to say, so the main disadvantages are also obvious:
Compared with series and parallel connection, the obvious drive mode of hybrid connection is more complex, and the increase of components also puts forward higher requirements for the optimal control of car companies. At the same time, the requirements for the motor, the clutch, and the working area of the engine will be higher, so the cost is a big problem.
Representative models of hybrid hybrid structure are: Toyota Prius, Hybrid Camry, Lexus CT200, Honda i-MMD, in addition to the typical hybrid hybrid structure, such as the hybrid system of the dual motor is basically a hybrid system, and most of the current hybrid systems are in this range.
summary:
The hybrid hybrid structure does learn from each other's strengths and complement each other's weaknesses, combining the advantages of series and parallel, but at the same time, because of the more complex system, the requirements for the optimization and control technology and cost control of car companies are also greater, but the advantages are obvious, so it is also the main direction of hybrid technology development for many car companies.