Modeling And Simulation Of The 42V Power Net System Based On Automobile Exhaust Waste Heat Thermoelectric Generation

As the demand for electricity of electric device and electronic control technology in the automobile gradually increases, today's 12V car power supply system has become increasingly difficult to meet the demand for electricity of modern cars, the 42V car power supply is the next generation of vehicle electrical system program to solve the contradiction of automotive electricity supply and demand generally acknowledged by the international community.Based on the 42V power supply system, the development of mild hybrid vehicles characterized by integrated starter/generator(ISG) has become a hot spot. The advantages of mild hybrid vehicles based on ISG are below, it costs little to be modified based on the existing internal combustion engine vehicles, the ISG can make quick starts and stops of the engine to avoid engine idling in regular conditions, even if the engine shuts down,air conditioners and other electrical accessories can also be driven by the motor alone, the motor can provide auxiliary power when accelerating or hill climbing and other heavy load conditions,retrieve braking energy when deceleration or braking by the function of regenerative braking. These unique features have a significant effect to improve vehicle fuel economy and reduce emissions in the context of maintaining the same dynamic performance.The automobile exhaust waste heat thermoelectric power generation technology utilizes the principle of direct conversion for thermoelectric materials,converts the exhaust heat account for 40% of the chemical energy of fuel combustion to electricity used by vehicles. At the present stage, the actual conversion efficiency of power generation projects of the passenger vehicles is less than 5%, the actual output power available is less than 1KW. The methods of improving the output power and conversion efficiency for the thermoelectric power generation system.replacing the traditional generator by the thermoelectric generators for the electricity supply of the automotive or building a mild hybrid system to work together with a internal combustion engine by a certain degree of hybridization become a research hot spot.In this paper, it proposes a program of the ISG-type 42V HEV system based on the thermoelectric generation to combine the characteristics of the ISG-type 42V HEV system and the thermoelectric power generation system. After a brief analysis of the basic principles,system architecture and system features of thermoelectric generation and the basic theory, structure type and function realization mode of the 42V mild hybrid system, based on the system framework,it carries out the system construction and optimization of the subsystems for the thermoelectric generation,type selection and parameters design of the internal combustion engine, ISG, batteries and transmission in the 42V powertrain to ensure the same dynamic performance and aim at reducing fuel consumption and exhaust emissions.In order to find out the performance of this new power system, based on the MATLAB/Slmulink modeling environment and electric vehicle simulation software Advisor, depending on the system's structure, work patterns and control strategies, it builds a simulink model of the thermoelectric power generation system,embeds it in the vehicle simulation model as a subsystem and carries a proper control of energy flow. On the basis of the existing models in the advisor, it improves the original models based on the characteristics of the new system,establishes the simulation models of the engine, ISG, batteries in the ISG-type 42V HEV powertrain, control strategy and the vehicle.Using the established simulation model, after setting the simulation parameters of parts, acceleration, climbing and other performance requirements in the Advisor, selectting some different driving cycles for simulation analysis, it carries a comparative analysis of the traditional car, ISG-type 42V HEV and the ISG-type 42V HEV based on thermoelectric generation. The fuel consumption and exhaust emissions have improved when vehicle dynamic performance remains the same, we can see, the development of this new power system for enhancing the vehicle's overall performance is effective.