Development Of ECU Hardware And Underlying Driver Software For High Pressure Common Rail Diesel Engine

With the increasing possession of internal combustion engine vehicles and more serious emissions of pollutants,our country has enacted more stringent emission laws and regulations.The application of electronic control high pressure common rail technology in diesel engine is of great significance in response to the national call for energy saving and emission reduction.According to the requirements of the ECU of the high pressure common rail diesel engine,the circuit schematic is designed in this paper.Besides,the processing requirement of the sensor input signal,the working principle and the control requirement of the actuator are analyzed and the high-performance control chip MPC5644A is selected as well.The MPC5644A is a 32-bit microprocessor from Freescale's PowerPC family.It has a clock operating rate of up to 150MHz and has a rich on-chip resource to meet the control requirements of high-pressure common rail diesel engines.According to the requirements of the ECU of the high pressure common rail diesel engine,the circuit schematic of the ECU is designed.The ECU hardware circuit includes the minimum control system circuit,the signal processing circuit,the power drive circuit,the power management circuit and the communication circuit briefly.To be exactly,the minimum control system circuit comprises a reset circuit and a crystal oscillator circuit;the signal processing circuit comprises a switch quantity,an analog quantity and a frequency quantity signal processing circuit;the power-driven circuit comprises a fuel injector drive circuit,a fuel metering unit drive circuit,a DC motor drive circuit,and a preheating Plug drive circuit and electromagnetic relay drive circuit,specific fuel injector and fuel metering unit drive circuit,selecting the new programmable chip MC33PT2000 for circuit design,realizing the flexible control of boost voltage and current through programming control;the power management circuit provides 1.2V,3.3V,5V and 12V voltages;communication circuit includes SPI and CAN communication circuit.In addition,the underlying driver software is designed with the MPC5644A on-chip resources.The underlying driver software includes a control system program,an input signal processing program,an actuator control program and a communication program.To be more specific,the control system program includes a phase-locked loop program,a real-time interrupt program and a watchdog program;the input signal processing program includes switching input program,analog input program and frequency signal input program.Meanwhile,the eTPU module is selected to collect the frequency signal,and a timing synchronization program is designed;the actuator control program designs a switch control signal,a PWM control signal and QOM control signal output program.According to the designed fuel injector and fuel metering unit drive circuit,MC33PT2000 DevStudio is applied to design the boost drive,injector drive and fuel metering unit drive program.Besides,the fuel injector and fuel metering unit are designed to enable the running program on the eTPU module;the communication program includes an SPI communication program and a CAN communication program.Thus,to realize the automatic generation of code,Simulink was used for encapsulation,the descriptive file C MEX Function of the encapsulation module was written and the system target file and module target file were written on the basis of the design of the underlying driver software.At the same time,the analog gantry is built,and the functional test of the ECU hardware circuit and the underlying driver software is performed.The ECU hardware circuit test includes:crankshaft and camshaft signal processing circuit,booster circuit,fuel injector drive circuit,fuel metering unit drive circuit and CAN communication circuit test.The ECU underlying driver software verification includes eTPU program verification,eMIOS program verification,AD conversion verification,and CAN communication verification.The test results of each module show that the functions of each module of the ECU hardware circuit are stable,and the function of the underlying driver software meets the design requirements.