Application of range extender in pure electric vehicles
First, introduction to Range Extender
The main advantage of Range Extender: it increases the driving range of pure electric vehicles, which is also the origin of the name of "range extender". Some people may ask that gasoline and diesel also cannot meet unlimited supply and demand, but it is true, but gasoline or diesel will have common gas stations to allow cars to replenish "food" at any time, but pure electric vehicles do not have such a large number and reliable. " "Post", because from the current research situation, the technology of "power station" is still in the development stage and is not very mature. The current situation makes us unable to waste food because of choking. The technology of "power plant" is still researched and developed. Pure electric vehicles must also continue to be used in suitable occasions to try to reduce pollution and save energy. Since we cannot supply electric vehicles with "food" at the "post" on the road, we can only try to bring our own "food" first, so that we can increase the driving range of electric vehicles to a certain extent. And the "food" that comes with it is the well-known range extender generator, and the range extender can also replenish fuel at the gas station at any time. More generally speaking, just like we went to a place where there is no socket to charge the mobile phone, we can only bring a mobile power supply to increase the power of the mobile phone. Range extender to electric car is equivalent to mobile power to mobile phone.
Range extender is one of the most important components of an extended-range electric vehicle, which improves the power, emissions and economy of the vehicle. It includes a power generation device and an auxiliary energy storage device. The main power source is electrical energy (provided by a power battery), and the auxiliary power source is an engine.
Second, range extender classification
According to the layout position, it is divided into trailer type, plug-in type, and vehicle-mounted type; according to the structural composition, it is divided into: large-capacity battery range extender, fuel cell range extender (also need to overcome technical problems), engine generator set range extender.
Third, the working mode of the range extender
1. The most extensive research of engine generator set range extender, now take this as an example to illustrate the direction of energy flow in the range extender: the chemical energy of the fuel is converted into mechanical energy in the engine, and the mechanical energy is transferred to the generator and converted into electrical energy . After converting the voltage, the electrical energy is finally used by the power distributor to drive the wheels or charge the power battery (as shown below).
2. The specific transmission of the electrical energy generated by the range extender is determined according to the control strategy of the car design. Under the research of various parties in the society, there are now a variety of control strategies, the most common of which are the thermostat mode, power follow mode, and constant temperature. Combined power-follower mode, there are other more complex strategies. The ultimate goal of these control strategies is:
(1) Ensuring power-premise. The power P required by the vehicle to drive is provided by the power of the power battery or the generator. To ensure that it can meet the power required by the vehicle in various working conditions, this requires the control strategy to determine whether the car is starting, cruising, high-speed or accelerating, climbing, The working conditions and energy transmission direction of the range extender and power battery under the conditions of deceleration braking and parking charging. For example, when it starts at low speed and the power battery has sufficient power, it runs in pure electric mode to minimize emissions, the range extender does not work, and prevents the engine from operating at low speeds and low efficiency; the power required at high speeds exceeds the power supply capacity of the power battery. , At this time, the range extender will automatically start to generate power to supplement the insufficient power in time.
(2) Ensure fuel economy-advantages. Let the engine work under the best working conditions. At this time, the engine can fully burn the fuel, save energy, and exert its best performance to ensure the life of the engine. For example, when the power battery has insufficient power, the range extender starts to work. While the engine supplies the kinetic energy of the driving wheels, it charges the battery due to the excess power working in the optimal working condition.
Fourth, application of range extender
The plug-in electric vehicle with the range extender installed has become a brand new electric vehicle model between the pure electric vehicle (Electric Vehicle, EV) and the hybrid electric vehicle (Hybrid Eectric Vehicle, HEV)-extension program Electric vehicles (Extended-Range Electric Vehicle, E-REV). "Extended range electric vehicles are a type of vehicle: When the on-board rechargeable energy storage system can provide electrical energy, the car runs in a pure electric mode with an additional energy device. This additional device only has energy in the on-board rechargeable energy storage system. Start work only when it's not enough, "General Motors' EDTate et al. Gave such a definition.
E-REV plays an indispensable role in the electric vehicle industrialization strategy that has been reached by the international automobile industry. The application research of range extenders in automobiles at home and abroad is also constantly developing and improving.
The combination of range extender and pure electric vehicles not only exerts the advantages of pure electric vehicles: reduced pollution emissions, energy saving, and reduced noise, but also makes up for the deficiencies of pure electric vehicles, which increases the driving range of vehicles. Significant progress, and under the premise of ensuring power, the best working state of the engine can be achieved, and the fuel economy of the car can be improved, which provides an opportunity for the development of electric vehicles in China.