Research On Intelligent Regulator Of Automobile Generator Based On CAN Bus

With the development of intelligent,integrated and networked automotive control technology,the functions of automotive electrical appliances are gradually becoming intelligent and networked.The automobile generator regulator is an integral part of the automotive electrical system.It can stabilize the output voltage of the generator and plays a key role in the safety of the entire automotive electrical system.When the engine starts running,the generator will always be in the state of power generation,which may cause the battery to be overcharged all the time,causing damage to the service life of the battery.However,the smart generator regulator can control the generator to stop charging the battery.When the battery is fully charged and the load is small,the power generation can be stopped completely to save a certain amount of energy,reduce the engine load,protect the battery and improve the fuel economy of the vehicle.This paper studies the intelligent regulator of automobile generator with Freescale MC9S12XS128 as the control core.In this paper,the working principle of vehicle generator,vehicle battery and related sensors is deeply studied,and the intelligent controller control strategy based on battery SOC and vehicle operating conditions is established.Among them,battery SOC and other signals are from CAN bus,according to engine load and the battery power and other conditions,control the generator excitation coil current,adjust the generator output voltage.Design the generator output status monitoring function,send monitoring information to the display instrument CPU through the CAN bus,and monitor and alarm the generator output status.The modular design concept is used to design the intelligent circuit of the generator intelligent regulator.The main control chip adopts the high-performance 16-bit Freescale single-chip MC9S12XS128.The whole control system includes the power supply circuit,voltage detection circuit,current detection circuit,excitation control circuit and CAN communication.Circuits,etc.In the excitation control circuit,the MOSFET switching device is directly driven by the single-chip microcomputer to realize the function of controlling the on/off of the excitation coil of the generator.In terms of software design,the generator intelligent regulator software program and CAN communication program are designed.The application layer communication protocol based on CAN2.0B protocol standard is formulated,and the CAN communication message sending and receiving program of the generator intelligent regulator node is designed.Developed a test program for the intelligent controller of the generator,completed the test of each hardware circuit,and performed the accuracy test on the A/D conversion.The verification test and CAN communication test of the intelligent controller control strategy of the generator were completed.The test results were in line with expectations.The effect can meet the design requirements.