| Turbocharging technology of internal combustion engine is widely used in Marine diesel engine because it can greatly improve the power performance,economy and emission performance of internal combustion engine,becoming an indispensable important technology of advanced internal combustion engine.However,the traditional exhaust turbocharged diesel engine was prone to turbine hysteresis,emission deterioration,insufficient intake pressure and torque under low load conditions,while the diesel engine was prone to accelerate wear and combustion deterioration caused by excessive supercharging under high load conditions.Electric auxiliary turbocharging technology is an effective technical means to solve the above problems.Focus of this paper is to find out the electrical auxiliary turbocharger to high-speed Marine diesel engine under various conditions optimum thermal efficiency is the highest motor power,and the simulation calculated under this best motor power electric auxiliary turbocharger for the improvement of the diesel engine are compared with the traditional turbocharger effect,further designed can satisfy the power of motor control technology.Firstly,the influence law of electric auxiliary turbocharger motor power on high speed diesel engine performance is revealed.Based on GT-SUITE model,the steady-state performance prediction model of electrically assisted turbocharged diesel engine was established and checked,and the influence of motor power on the comprehensive thermal efficiency of diesel engine and turbocharger efficiency was simulated.The results show that the optimal motor power can achieve the highest comprehensive thermal efficiency of diesel engine under various load conditions,and the operation strategy of electrically assisted turbocharger is determined.Moreover,the influence of electric auxiliary turbocharger and traditional turbocharger on diesel engine performance under optimal motor power is compared and analyzed.The results show that under low load conditions,the diesel engine turbo hysteresis effect is improved obviously,the turbocharger ratio is increased obviously,and the fuel consumption is decreased obviously.Secondly,the paper demonstrates the control theory of the high power BLDC motor for the electric auxiliary turbocharger matching the aforementioned Marine high speed diesel engine.Passing zero test instead of sensor is used to realize the rotor position,and by measuring the counter electromotive force calculation to achieve speed and power control,at the same time to solve the non-inductive brushless motor start-up speed counter electromotive force can’t detect problems caused by the low design the three-step startup programs,meet the Marine high-speed diesel electric auxiliary turbocharger to high temperature and high pressure working environment.Thirdly,for the om H-5825-520 model 6.66 KW /44.4V BLDC motor,using MATLAB/Simulink simulation of the motor control technology,and the simulation results are analyzed.The results show that the control system designed in this paper can meet the control requirements of the actual electrically assisted turbocharger.Then the hardware circuit board and software program of brushless DC motor control system are designed according to the model and control theory.Hardware design part finished STM32F103C8T6 minimum system circuit design,step-down regulated power supply circuit design,power drive circuit design,the back emf zero detection circuit,current detection and protection circuit and other related hardware circuit design,software program design according to the state of motor to realize the control system,perform different functions for different status,Several software function modules are designed,including main program module,start module,reverse electromotive force detection and commutation module,speed detection and speed control module,current sampling and overcurrent protection module and so on.Finally,the control circuit board of BLDC motor designed and manufactured by ourselves was tested and verified.The results shown that the motor start time was controlled within 200 ms,and the rotor speed could be stabilized by using inverse electromotive force zero-crossing detection.No-load acceleration effect has fast response and good stability,which can meet the actual control requirements of electrically assisted turbocharger and achieve the due effect. |
PDF Full Text Request