Views: 136 Author: Site Editor Publish Time: 2021-12-15 Origin: Site
Hybrid vehicles use two independent energy sources, usually engines (such as diesel engines or steam turbines, or small-displacement internal combustion engines) and auxiliary power batteries. Classified according to the capabilities and functions of battery motors, the structure of HEV is as below:
2.1 Micro-hybrid hybrid vehicles
The micro-hybrid hybrid vehicle consists of a starting/generating system that works in conjunction with a traditional engine. This starting/generating system can not only provide limited power to help the engine run better during the starting process, but also can be used as an alternator to switch the engine Start and stop are combined with regenerative braking energy recovery. A typical micro-hybrid system consists of a motor with a power of up to SkW and a traditional 12V battery to reduce the fuel consumption of the vehicle. At present, light vehicles equipped with this system can generally achieve a fuel saving rate of 2%-10% in an urban driving cycle (the specific value depends on the vehicle, power transmission system and driving conditions). In addition, when the vehicle enters the driving state, the motor does not provide additional torque to the engine.
2.2 Light Hybrid Hybrid Electric Vehicle
The light-hybrid hybrid vehicle provides motor assistance when starting, and the energy is recovered to supplement the battery power during braking. The system has a motor with a slightly larger power than the micro-hybrid hybrid system to assist the engine. The power is about 6~12kW, and the working voltage is 140V. However, the system still cannot be driven purely by electricity. It only provides torque compensation during acceleration and braking, mainly because the system's motor is coaxial with the engine. The fuel efficiency of the structural system is increased by up to 30% (generally 10% to 20%), and the displacement of the engine can be reduced at the same time. Typical mild hybrid hybrid vehicles equipped with this system in the market include GMC Sierra pickup, Honda Civic, Accord and Saturn Vue.
2.3 Strong-hybrid or power-assisted hybrid electric vehicles
In a strong hybrid hybrid vehicle, the electric motor can be the only driving power source. Because it has a complete electric drive system, the system provides engine starting, idling operation, pure electric starting, torque assist, regenerative braking energy recovery and limited pure electric driving range. Unlike a light-hybrid hybrid vehicle, it can realize the operation of the motor or the engine, or both at the same time, through power splitting. When used in pure electric mode, the vehicle achieves almost zero emissions during operation.
Strong-hybrid hybrid vehicles usually have a high-capacity energy storage system with a power of 60kW and an operating voltage of 200V or more. This system has a wide range of architectures (series, parallel, and hybrid). Therefore, this system can increase the fuel efficiency of vehicles by as much as 40% (usually between 20% and 50%), and does not have much impact on driving performance. However, a strong hybrid hybrid power system usually requires larger batteries and motors, as well as improved accessory systems.
2.4 Plug-in hybrid electric vehicles (or extended-range electric vehicles)
The plug-in hybrid vehicle is similar to the strong hybrid hybrid vehicle in that it can be driven by both fuel and pure electricity. One characteristic of plug-in hybrid vehicles is that electric energy can be obtained not only from fossil fuel power generation, but also from the power grid. A plug-in hybrid electric vehicle is regarded as a pure electric vehicle equipped with a limited-power engine, or an extended-range electric vehicle that uses the engine to charge the battery to increase the driving range.
In plug-in hybrid electric vehicles, because the vehicle has alternative energy units and batteries that can be charged from the grid, the quality of the battery is significantly smaller than that of pure electric vehicles (larger battery capacity than strong hybrid electric vehicles), so plug-in hybrid vehicles Compared with similar electric vehicles running in pure electric mode, the efficiency is higher (due to the reduction in driving power required to drive the vehicle). PHEV chargers must be lightweight, compact, and efficient in order to maximize the utilization of electrical energy obtained from the grid. By separately or simultaneously using the electrical energy obtained from the grid and the chemical energy stored in the fuel tank, plug-in hybrid vehicles can achieve better driving performance, higher energy efficiency, less environmental impact and more energy than traditional vehicles. Low cost, these also depend on driving habits and power generation structure.
The electric energy demand of plug-in hybrid electric vehicles depends on various factors (especially the weight of the vehicle), and the required power is above 70kW. Since electric energy is obtained from the power grid (rather than a traditional engine), the vehicle is driven in a motor drive mode during short-distance driving and urban conditions, and both efficiency and power performance can be significantly improved. Therefore, plug-in hybrid vehicles are very ideal vehicle types for driving in cities and highways.