Views: 128 Author: Site Editor Publish Time: 2022-01-04 Origin: Site
In a strong hybrid electric vehicle, it can be divided into parallel type, series type, hybrid type (or even more complex architecture) according to the arrangement of primary and secondary driving power sources. These architectures present complex trade-offs between efficiency, driveability, cost, manufacturability, commercial viability, reliability, safety, and environmental impact. Therefore, the selection of the best architecture needs to be based on application requirements, especially driving conditions and driving cycles.
3.1 Series Hybrid Vehicles
In a series hybrid architecture, the engine generates electricity from a generator to charge the battery, which is used to drive the electric motor. Conceptually, it is an engine-assisted pure electric vehicle with extended driving range. In this architecture, the engine output power is converted into electrical energy, which is output from the battery to the powertrain. The main advantage of this architecture is that it allows the engine to operate at the average power point, rather than peak power demand, so it can operate in the most efficient area. In addition, the structure is relatively simple and there is no clutch, so the arrangement position of the engine generator set is relatively flexible. In addition, it can store a portion of the energy generated by braking energy recovery. On the other hand, this architecture requires relatively large batteries and motors to meet peak power requirements, and the energy is converted from mechanical energy to electrical energy and back to mechanical energy, causing large energy losses. This architecture is generally more suitable for urban frequent Park and run driving modes. In general, this architecture has suboptimal fuel economy (due to power conversion) and higher cost (due to additional generators), but offers flexible component selection and lower pollutants than parallel architectures Emissions (due to generators working more efficiently).
3.2 Parallel Hybrid Vehicles
In a parallel architecture (such as the Honda Civic and Accord Hybrid), both the engine and the electric motor provide torque to the wheels, so more power and torque can be delivered to the transmission. Conceptually, it is an electrically assisted conventional vehicle that reduces emissions and fuel consumption. In this architecture, the shaft end power of the engine is output directly to the driveline. An electric motor in parallel with the engine provides additional power when engine performance requirements are exceeded. Since the engine provides wheel torque, a smaller size battery and motor can be used (and therefore a lower capacity battery), but the engine does not always operate in its most efficient area. Therefore, this architecture can reduce fuel consumption by more than 40%. This architecture is generally suitable for urban and highway driving conditions.
3.3 Parallel/Series Hybrid Vehicles
Finally, there is a splittable parallel/series hybrid system (such as Toyota Prius, Toyota Auris, Lexus LS600h, Lexus CT200h and Nissan Tino), where the electric motor and generator are split through a power split device based on a planetary gear system (Fig. 1.9c) disengaged so that the engine provides torque to the wheels and charges the battery via the generator. This architecture has the advantages of both parallel and series at the expense of adding extra components. However, the advantages of each architecture depend on environmental conditions, driving style, driving range, electrical energy generation composition, and total cost.
3.4 Complex Hybrid Vehicles
This type of complex architecture HEV is very similar to a series/parallel architecture, with the main difference being a power converter, combined motor/generator and electric motor to improve the controllability and reliability of the vehicle. The main disadvantage of this architecture is the need for precise control strategies.