Control Strategy Of Variable Cam Phaser Device System Modeling And Simulation Research

Continuously variable cam phaser (CVCP) technology is one of the key technologies of the engine. By changing the relative angle between the camshaft and the crankshaft, it can adjust the timing of the valve, and effectively improve the low-speed torque of the engine, reduce fuel consumption, optimize emissions and improve the stability of the idle speed. Due to the energy efficiency of Continuously variable cam phaser (CVCP) system depends greatly on the electronic control unit (ECU) of the relevant control software, therefore, the CVCP control strategy and algorithm need to be verified before being used in the actual engine control. In the process of software development based on V model, software in loop simulation is an important step in the development and debugging of CVCP control software. Therefore, the model based on control design and based on software testing have become the key content of the development of CVCP control software in the engine management system (EMS).In this paper, focusing on the two aspects involving the establishment of the cam phaser device model and the control strategy of CVCP system control signal generation, based on the model, the control logic and control algorithm of the application layer software of CVCP control system are designed. With the aid of the Matlab/Simulink software platform, the actuator dynamic model and control strategy model are established, and results of simulation are verified by the test data in engine bench. The main research work is as follows:1) Dynamic modeling of CVCP actuator for control. Based on the physical process and working mechanism, the mathematical model of the phaser and OCV are established. Then the corresponding Simulink simulation model is constructed, and the model of the phaser device is verified by off-line simulation using the engine bench test data.2) Design of CVCP control strategy based on Model. To establish the Simulink model of enabled module, position prediction module and position control module. According to the relevant control parameters in the working process of the engine and the control strategy, combined with the calibration of the engine bench test, the pulse spectrum, the enable state of the phase device is determined by judging the state of the flag position; According to the engine speed and load information, combined with the engine temperature, the demand torque and the amount of compensation, to calculate the target phase; For the phase position control part, the traditional PID control strategy is used to check the proportion, differential and integral calibration coefficient of the target phase and the actual phase, and then work out the control duty cycle of the CVCP system.3) Closed loop simulation verification based on engine bench test data. A closed loop system with the control strategy and the cam phase device model is presented, and CVCP system GUI interface is established. According to measured engine operating condition data and actual phase value, the control effect is evaluated by simulating the two party from the steady state characteristic and response characteristic.