What is the difference between electric car and traditional car chassis?

Basic Structure and Working Principle

The traditional car chassis consists of four parts: the transmission system, the driving system, the steering system, and the braking system. The chassis function is to support and install the car engine and its various components and assemblies, form the overall shape of the car, and accept the power of the engine to make the car produce motion., Keep running normally.

The basic structure of electric vehicles can be divided into three subsystems, namely the main energy system (electric source), the electric power drive system, and the energy management system. Among them, the power drive system is composed of electric control system, motor, mechanical transmission system and drive wheel. The main energy system is composed of the main power supply and the energy management system. The energy management system is a key part of the power use control, energy regeneration, and coordination control. The electric drive and control system is the core of electric vehicle and the biggest difference from the internal combustion engine car.

Working principle of electric vehicle: Battery-current-power regulator-motor-power transmission system-driving car.

Pure electric vehicles, compared to fuel cars, the main difference is(different) in the four components, drive motors, speed control controllers, power batteries, and car chargers.

Energy supply and systems

Compared with diesel vehicles, electric vehicles are characterized by flexible structure. The main energy sources of internal combustion vehicles are gasoline and diesel, while electric vehicles are powered by electric sources and motors. Electric driving and control systems are the core of electric vehicles and the biggest difference from internal combustion engine vehicles. Traditionally, the energy of an internalized car is transmitted through a steel coupling and a shaft, while the energy of an electric car is transmitted through flexible wires. Therefore, the placement of various components of electric vehicles has great flexibility.

Transmission.

The variable speed drive system is an important component of the electric vehicle drive subsystem. It refers to the mechanical connection between the drive motor shaft and the wheel. For conventional cars, the transmission is a necessary component and the type of transmission is primarily considered for design. However, for electric vehicles, since the torque and speed of the drive motor can be fully controlled by the electronic controller, the design of the shifting system can be variously selected. It can be shifted by conventional gearboxes or electronically controlled to directly shift the motor. Which solution to use depends mainly on the energy and economy of the electric vehicle, as well as the design of the motor and controller.

In order to improve the transmission efficiency of electric vehicles, a two- or three-speed automatic transmission bridge integrated with an electric motor and a variable speed transmission has been developed. The advanced two-speed motor/multi-speed transmission bridge fully integrates the variable speed gear set with the high-speed asynchronous motor and is directly mounted on the drive shaft of the electric vehicle drive wheel, resulting in light weight, small size, high efficiency, compact structure and cost. Low transmission system.

Power system

After the rapid development of electric vehicles in the past 20 years, three types of power system structure and technical characteristics have been formed in the energy power system.

Pure electric vehicles, hybrid electric vehicles and fuel cell vehicles are currently three types of electric vehicles. Hybrid electric vehicles are currently listed as industrialization plans by domestic and foreign major auto companies, parallel hybrid and hybrid hybrids. Power is the mainstream power system structure widely adopted by electric cars. In recent years, with the rapid development of energy storage battery technology, pure electric vehicles driven by electric vehicle battery have been rapidly developed. The pure electric power system of multiple motor-driven power dispersion structures has been widely used by domestic and foreign research institutions. attention. A fuel cell electric vehicle driven by hydrogen and oxygen through an electrode reaction and converted into electric energy adopts an electric-electric hybrid structure, and the energy conversion effect is 2 to 3 times higher than that of an internal combustion engine, and is one of the important development directions of a clean energy vehicle in the future.

Chest Electronic Modularization and Intelligence

Electric vehicles use electric energy, and electrification technology provides more possibilities for innovation of car structure performance. The chassis system will gradually adopt electric execution components, and the structure will also undergo innovations, and will promote the development of modular and intelligent automobiles.

General Motors developed the electric car "AUTOnomy"[ 6] It is a typical innovative example of the integration of chassis and power system integration. The car body is separated from the chassis. The chassis is integrated with the power system in a "skateboard." The drive system and the control system are designed on the chassis and use wire control technology. The vehicle control system, braking system, and other vehicle-mounted systems are all realized through electronic control rather than traditional mechanical methods. The body and chassis are only connected through software interfaces, and the chassis is fully "electrically operated".

Electric vehicles are driven directly by motors installed in the wheels to achieve decentralized power control. Compared with the traditional internal combustion engine car and the single-motor centrally driven electric vehicle, the four-wheel drive method realizes the independent decentralized drive of each wheel, and each wheel can achieve braking energy recovery. Can also save transmission, clutch, transmission shaft and other complex mechanical transmission, transmission efficiency.

Transmission.

Whether it is a series connection (the fuel cell can be regarded as a special series structure), a parallel, Mixed type hybrid car, or a pure electric vehicle powered by a battery, the arrangement of the power unit is often based on the original engine front compartment arrangement. And strive to arrange the corresponding electrical devices in the front compartment (such as DC / AC, DC / DC, etc.), so put forward higher requirements for component miniaturization. In addition, parallel or hybrid hybrids require more stringent layout due to the use of more than two power units. The hybrid structure of the Toyota Prius is a model for miniaturization and integration [4].

Compared with traditional automatic gearboxes, the automatic transmission bridges of electric vehicles also include disk-shaped and banded clutches, star-shaped gears, differential, hydraulic systems that perform clutch actions, lubricants, and cooling systems. The automatic transmission bridge can use the microprocessor to achieve the full electronic control of the shaft. A five-shift selector consisting of parking, reversing, neutral, driving, and driving from one gear provides drivers with different choices for driving in various situations. The controller will automatically determine which shift gear the driver hangs on, and will send the appropriate signal to the hydraulic control system and implement the shift control. Due to the low rotational inertia of AC asynchronous motor and the ideal torque characteristics, it is easier to control the transmission speed of the transmission bridge for smooth automatic transmission.

Intelligent Technology of Energy Power System

The electronic energy system and power system make electric vehicles show more and more powerful functions. However, the intelligent power system of electric vehicles has not attracted sufficient attention. In general, the focus is on the function, steady state performance indicators, reliability, and other aspects of the vehicle and the power system. The research shows that the intelligent technology of energy power system is of great significance to improve the economy, power and reliability of electric vehicle.

Vehicle motor systems such as asynchronous motors and permanent magnet motors have nonlinear time-varying parameters. Especially when the internal magnetic field and temperature change, the motor parameters will change, which is very important for online identification of such time-varying parameters. The self-learning battery management system accurately monitors the battery SOC status in real time and protects the battery from damage during operation, which is important for battery life and safety. The focus of vehicle energy management intelligent technology lies in the optimal allocation of energy and the economics of driving. That is, during normal driving (normal operation of each component), the remaining mileage is determined according to the SOC and SOH states of the battery, thereby optimizing the driving parameters. The vehicle intelligent energy management must also consider the abnormal working state of each subsystem and component, that is, when various faults occur in the power system work, timely determine the source of the fault and propose a reasonable coping strategy.

Brake system

The braking device of an electric car, like other cars, is designed to slow down or stop the car and is usually composed of a brake and its control device. The electric car transmits the inertial energy to the motor through the transmission system. The motor works in a power generation manner to charge the power cell and realize the recycling of braking energy. At the same time, the generated electric mechanism power moment can be applied to the drive wheel through the transmission system to generate braking power.

The traditional fuel car is to convert the inertial energy of the car into heat energy through the friction of the brake and emit it into the surrounding environment.

For electric cars. Because the motor is reversible, that is, the motor can be converted into a generator under certain conditions, so the feedback braking method can be used when braking to make the motor move in the power generation state. The feedback current generated by braking is fed into the human energy storage device through a designed power device, which can recover a considerable amount of inertial energy and increase the range of electric vehicles.

In general, the regenerative power generation system can only limit the speed of the rotor of the motor, that is, the speed of the rotor is not much higher than the synchronous speed, but it cannot be limited to less than the synchronous speed. That is to say, the regenerative braking can only play a stable operation. Therefore, when considering the design of several applications of regenerative braking, it is necessary to comprehensively consider the brakes, downhill taxiing, high-speed operation and Various occasions such as deceleration branch.

Future electric vehicle outlook

Unlike traditional cars, electric vehicles are obviously characterized by the adoption of new energy power systems. On the one hand, electric vehicles have undergone a technological revolution in energy conservation and environmental protection. On the other hand, the rapid torque response characteristics of the power drive system also make a big leap in active security technology and performance. The development and application of automotive electronics technology promote the development of chassis in the direction of electric, modular, intelligent and integrated, providing an inexhaustible source for the improvement of car safety and comfort, as well as providing new design ideas for the application of lightweight body and new materials. It can be predicted that electric vehicles will exceed the characteristics of the new energy power system itself, and a new revolution will appear in the design concept, method, and production method.

Changes in design concepts

The reform of the design concept of electric vehicle is mainly reflected in the design concept of safety. With the development of the electronic chassis and information technology, the rapid development of the active safety control of electric vehicles and the development of the intelligent technology of vehicles all have an impact on the safety design concept of traditional car bodies.

The application of intelligent technology makes the car have a "human-like" function. Before a potential collision accident (such as pedestrian-car collision, car-car collision, car-obstacle collision, etc.) occurs, the electric vehicle predicts various potential dangerous states through the cognitive function of the intelligent system, and advances or automatically adjusts. The movement track avoids the occurrence of dangerous accidents and greatly improves the safety of driving.

(2) The rapid response of the braking system can improve the impact resistance of the chassis when a collision occurs, such as when a collision occurs,

By applying the rapid response of the electric parts in time, the "soft collision" is realized, and the damage caused by the collision is effectively reduced.

(3) The body collision requirement is reduced. The new safety idea is adopted in the design concept and technology of collision safety.

The way the car body absorbs energy is replaced by rapid response and intelligent rapid prediction.

The Change and Simplification of Vehicle Production Mode

The biggest feature of electric cars in the future will be structural innovation. The integration of the chassis power plant will have a great impact on the core structure of the traditional car body. In the future, the structural advantages of the chassis integration system and the modularization of the body system will be fully utilized.

(1) The chassis integrates the power system through a simple component, integrating the battery system, the electric drive system, and the traditional chassis

A new type of chassis with components as one will greatly simplify the chassis production method.

(2) The body design is more concise. The body of the traditional car will probably not be so complicated. The original body function will be new

Instead of a type chassis, lightweight materials are applied to body (such as carbon fiber, automotive polypropylene, etc.). Modular body safety requirements are reduced in terms of collision safety. A chassis system with different shapes of body may become a new trend.

(3) The complex body manufacturing system of traditional cars may be more fashionable modular body and integrated chassis

Manufacturing system replaced. There are more and more electronic(electric) elements, and modular component production methods will be vigorously promoted and developed.

Summarize

In general, electric cars and fuel-powered cars are also motor vehicles. In terms of external performance, the mathematical and physical means of describing them are not very different. Therefore, most of the parameters of electric vehicles can be borrowed from the development of mature fuel car systems. However, due to the particularity of electric vehicles, its performance parameters such as battery weight, efficiency, and utilization efficiency of regenerative energy are not available in traditional diesel vehicles.

In addition to the new energy power system replacing the original internal combustion engine power system, the future development will increasingly reflect the characteristics of different from traditional cars. These characteristics include:(1) rapid response to power control; (2) A new type of power drive with decentralized power; (3) New body safety solutions and lightweight technology applications; (4) Electric, intelligent and integrated chassis. The development and innovation of the above technologies will greatly increase the safety and energy-saving effects of automobiles, further promote the transformation of the safety design concept of electric vehicles, and simplify the manufacturing and production methods of electric vehicles.

The page contains the contents of the machine translation.