The vehicle power system consists of a battery, a starter, a generator, an electric load and an ECU. The vehicle power system can be divided into two parts from the system: one is the power system, which is composed of a generator, a battery, and an electric load for the whole vehicle; The starting system consists of an engine, a starter, and a battery. When developing a new model, it is first necessary to determine the vehicle system design goals, and then select the starter, battery and generator according to the design goals, and finally verify the rationality of the selection by experiment. Figure 1 Power system selection process Generator selection • Load average current statistics According to different vehicle configurations (high and low), the rated current of the load is multiplied by the weighting factor (usage frequency) to calculate the average operating current of the idle and driving conditions. In the formula, I average: average operating current of the vehicle's electrical load m: the number of electrical equipment used in the whole vehicle Ni: The number of i-th power equipment Ii: rated current of the i-th electrical equipment; Ki: weighting factor of the i-th electrical device • Generator output power confirmation The rated current of the generator should meet the demand of the electric load for the whole vehicle. At the same time, under the idle speed and standard driving conditions, the output current of the generator should also meet the power demand of the whole vehicle. ♦ Idle condition evaluation criteria ♦ Generator power evaluation standard ♦ Standard driving conditions evaluation criteria • Generator selection confirmation According to the performance parameters provided by the generator supplier, under the premise of meeting the power requirements under various working conditions, the most cost-effective generator is selected. Figure 2 Generator selection process Starter selection calculation • Starter performance requirements for the starter The starter output performance should be such that the engine is rotated to a defined minimum starting speed in a low temperature environment. The torque output from the starter at the starting speed point should be able to overcome the rotational resistance torque of the engine to ensure a smooth start of the engine. • Gear ratio matching The gear ratio of the engine and the starter is an important parameter to ensure that the starting of the engine start is matched. The gear ratio is changed by the gear ratio of the pinion (starter) and the flywheel (engine), and the torque and speed are changed while maintaining the power. • Starter selection confirmation According to the performance parameters provided by the starter supplier, under the premise of meeting the above requirements, the most cost-effective starter is selected. Figure 3 Starter selection calculation process Battery selection • Resting performance requirements The amount of power lost by the battery during the vehicle's rest period includes the continuous consumption of the vehicle's quiescent current, the self-discharge of the battery, and the electrical consumption during the next engine restart (excluding the consumption of the vehicle during sleep). The rest time refers to the duration during which the battery is discharged from the specified initial SOC to the minimum SOC after the vehicle is dormant, and the vehicle can be smoothly started at the specified minimum SOC. The rest time needs to meet the design requirements. • Cold start performance requirements ♦ Battery internal resistance When the vehicle is in a low temperature environment (Tstart °C), the battery power needs to ensure that the voltage and current required by the starter are continuously output for a period of time (tstart seconds). ♦ Minimum voltage during startup During the engine starting process, in order to ensure that the relevant electrical and electronic devices can work normally, the minimum voltage of the battery should meet the requirements of the voltage functional specifications of the relevant electronic components. Figure 4 battery selection process 100G Toothpaste,Toothpaste For Sensitive Teeth,Desensitizing Toothpaste,Stain Removal Toothpaste Shenglong Co.,Ltd , https://www.sl-oralcleaning.com
