Before The Battery Technology Breakthrough, The Extended-range Electric Car May Be The Best Transition

- Nov 08, 2019-

Before the rise of Tesla, I once thought that there would be no leap or subversive revolution in battery energy storage technology for electric vehicles in a short period of time. At present, although Tesla can achieve a huge breakthrough in the field of battery safety management, I still think that "pure electric vehicle" is not the best product for consumers, and can overcome the fuel car and the hybrid car in the foreseeable future. It is not a "pure electric vehicle", but an "extended electric vehicle" such as VOLT produced by General Motors and the ideal ONE of a car and home.


What is an extended-range electric car?


The extended-range electric vehicle adopts a series hybrid structure, which is a type of plug-in hybrid vehicle, which directly drives the vehicle by the motor, and the engine does not participate in driving. It can be seen as a small-capacity pure electric vehicle, and an additional generator is added to allow the vehicle to charge while driving. When the battery is low, the vehicle generates electricity through the extended range engine operation, and part of the generated electric energy is used to directly drive the motor, and the other part is to charge the battery.


When the battery's electric energy reaches a certain upper limit, the extended range engine stops working, and the battery directly drives the motor; as the driving time and mileage increase, the battery consumption becomes larger and larger, and the battery's electric energy is lower than a lower limit, increasing The engine started to start working again. In this way, the extended range engine will always be in a cyclic working state, and the start and stop of the engine depends entirely on the power supply of the battery.


Unlike the "hybrid vehicle has both a fuel system and an electric system", the extended-range electric vehicle needs to cooperate with fuels such as gasoline and hydrogen in long-distance driving, but gasoline is only used to generate electricity and drive electric vehicles with electricity. Instead of driving the car directly with gasoline in the case of power exhaustion, even the gearbox is not needed, so the structure is much simpler than the hybrid car and the plug-in hybrid car; and in the extended mode, The engine has been working in the optimal speed range, and there is no frequent start and stop, which is more energy efficient than ordinary hybrid cars.


In addition, the "Extended Electric Vehicle" itself can use its external power supply to charge the battery it is equipped with. Like the plug-in chaotic car, it can also supply power to the battery through energy recovery when the brake is decelerating. Therefore, the extended-range electric vehicle not only has the driving quality of the pure electric vehicle, but also effectively solves the problem that the current electric vehicle has insufficient cruising range. Based on this, I believe that under the premise that the battery energy storage technology will not have a rapid development or a revolutionary revolution, the “extended electric vehicle” will be popular and popular in the market.


What are the advantages of the extended-range electric vehicle?


Compared with hybrid vehicles, the hybrid vehicle usually has a fixed operating point of high speed and high power when the engine is turned on, which will reduce the fuel economy of the engine. When the engine has excess energy, it will first use energy. A portion of the energy is stored in a manner that is transmitted to the battery pack and then to the drive motor. While increasing the transmission process, it also increases the energy loss. However, after the range extender is turned on, the extended program car will adjust the output power of the engine according to the required power of the drive motor, and try to make it work in the best working curve to achieve better economic performance.


Compared with the traditional fuel engine, the range extender is equipped with a smaller engine displacement, which is smaller than the conventional engine, has less noise, and is more efficient. Moreover, in the design of the whole vehicle structure, the range extender consists only of the generator and the engine, the structure is simple, the energy transmission efficiency is high, and the fuel consumption and emissions are ideal. In addition, the motor of the extended-range vehicle can also recover the energy of the vehicle braking and downhill, reducing energy loss.


Compared with general pure electric vehicles, the extended range of the extended-range electric vehicle can charge the power battery with the vehicle, which greatly increases the cruising range of the vehicle. At the same time, its vehicle-mounted power battery is far smaller than the pure electric vehicle power battery of the same type, so the manufacturing and production costs of the vehicle are greatly reduced. In addition, when the range extender is turned on, the risk of over-discharging of the power battery pack can also be shared, which is beneficial to improving the service life of the battery pack.


While driving, the vehicle is completely driven by the motor, so the engine can maintain "optimal speed" to generate electricity throughout the journey. Under such circumstances, even if it is "first use oil to generate electricity, then use electricity to drive", it is more energy efficient than many vehicles that are directly driven by oil. Moreover, the engine displacements used in most of the extended-range electric vehicles are relatively small, and there are many even only 0.5L. Although it is difficult to drive the vehicle, it can accomplish the task of generating electricity well, and the fuel consumption naturally needs to be It is much lower than the 1.5L and 2.0L models. The power can still be like a pure electric car. It has a strong low-speed torque and a relatively fast starting speed.


Moreover, almost all of the extended-range electric vehicles themselves support the use of charging piles for charging. Within the capacity range of the power battery, the vehicle can still maintain a zero discharge for a certain distance, further reducing the overall fuel consumption and emissions. Coupled with factors such as low engine displacement and lower operating noise than larger displacement engines, the vehicle's mute effect is superior to most conventional fuel vehicles.


What is the working principle of the extended-range electric vehicle?


For the technical solution of the extended program, there should be two trends:


1. Based on the structure of a pure electric vehicle, a small range extender is arranged in the air. Pluggable pure electric life under the condition of soC30% trigger extended range, should also ensure the actual driving conditions of pure electricity (instead of NEDC) city commute life, the suggestion is equivalent to more than 200km NEDC life. Then, the small range extender should be as simple and light as possible to simplify the working conditions. This extended architecture can be developed based on purely electric architecture.


2. Engine-based direct drive based on micro-hybrid/hybrid architecture. The gearbox and drive shaft are eliminated, and the electric drive front and four wheels are available. Among them, the important point is to control the battery power and reduce costs. The power of the engine should be greater than or equal to the rated power of the motor (or more than half of the peak power). Through optimization of the strategy, it is necessary to ensure that the engine is as narrow as possible under the conditions of direct driving under various operating conditions of the engine. In this way, the engine can be avoided to make a full-duty engine, at least to lock the speed, simplifying the complexity of the timing system.


Can the range extender participate directly in the drive?


Usually we say plug-in hybrid and non-plug-in hybrids, motors and engines can drive the vehicle, so the design of the chassis and the vehicle's power structure is very complicated. The engine of the extended-range electric vehicle is not directly involved in driving the vehicle, so the difficulty in design and production is reduced.


Then, is it possible to use the engine on the extended-range electric vehicle to generate electricity only in the urban area where the congestion is unbearable, and in the unimpeded high-speed road condition, the engine on the extended-range electric vehicle can directly participate in the driving of the vehicle, thereby achieving At the same time, the city's congested road sections and high-speed smooth passage sections can greatly save fuel?


The answer is: For the new extended-range electric car, it really works!


In fact, the VOLTEC technology used on the Chevrolet VOLT already has this capability, consisting of a dual motor, a planetary gear set and a power split module. This combination of dual motor + planetary gears is easily reminiscent of Toyota's THSII. In fact, they do have considerable intercommunication in the basic principle. The two motors work in tandem with the planetary gear set to achieve the purpose of changing the transmission ratio and power mixing. The difference is that Toyota's THSII is more focused on the direct output of the engine under normal driving conditions, while VOLTEC pays more attention to the coordinated work of the two motors.


With this system, VOLT's extended program power is essentially different from the current popular plug-in hybrid. It is more like a set of deep mixing technology, adding a similar plug-in approach, not only at the time, but also very few.


The technology used on the Buick VELITE5 is basically the same as the second-generation Chevrolet VOLT, even further. In fact, based on the development of the first generation VOLT, GM began to have a deep understanding of deep mixing, and then applied it to the development of a new generation of extended-range electric vehicles Buick VELITE5.


The versatile new hybrid system is equivalent to adding a planetary gear set to the previous VOLT hybrid, thus forming the effect of the dual planetary gear + dual motor working together. Among the two motors, one is the “main drive motor”, and the other is the task of “generator” under the condition of urban congestion, etc., and when needed in the open channel, it can directly participate in the vehicle drive to avoid “oil-to-electricity”. The process, thus making up for the shortcomings of the previously increased efficiency of the electric vehicle under high-speed conditions.


It is worth mentioning that in the extended-range electric vehicle products, the ideal ONE of the car and the home will be more competitive from the product point of view, for the following reasons:


First, as the founder of the former car home, Li Xiang founded the first SUV product after the car and the home. I think Li Xiang is a person who will build and want to build a good product. Second, the "ideal ONE" can be said to be The pure electric vehicle that has been mass-produced and has the highest cruising range now solves the problem of more endurance (although it is an extended program). Thirdly, the ideal is the production car of pure electric vehicles so far, I think the degree of completion. The highest (for the consumer is the gospel); Fourth, as the luxury seven-seat SUV, the ideal price is indeed the price of the same level is not too bad.


Xiaobian has something to say


The positive significance of the extended program to the development of the new energy industry has three aspects: First, market recognition. In the short to medium term, it can satisfy different travel scenarios of consumers, and the market acceptance is high, which can promote the popularization of pure electric power; second, the technology is close to pure electric. Due to the long range of pure range electric power, it is necessary to invest heavily in battery management, lightweight, thermal management, electric drive and many other technical propositions. These technologies are common to pure electric vehicles and are conducive to technology accumulation. Third, charging foundation Facilities expansion. Plug-in hybrids, such as the extended program, also need to be recharged. With the promotion of plug-in hybrids, the construction of charging infrastructure will continue to be driven, thus laying the foundation for pure electric power.


In terms of market availability and products, I believe that "extended electric vehicles are the best combination of traditional fuel vehicles and future pure electric vehicles. They will inherit the advantages of the traditional automobile industry to a large extent, but not destroy traditional cars. Under the premise of the industrial chain, along with the mature battery energy storage technology, the whole society will be slowly promoted to the stage of pure electric vehicles.