Development Of Electronic Control Unit In Automobile Engine

With the rapid development of microelectronics, computer and control technique, it has been a new tendency in the automobile engine techniques to raise engine performance by using electronic control techniques, reduce energy consumption and meet the more and more strict emission regulations. As the domestic automobile electronics industry is at beginning stage at present, large-scaled production has not been formed. In addition, most of domestic auto works are joint ventures, the foreign partners control the technique decision rights and the electronic products are supplied by the suppliers that are chosen by the foreign partners. This seriously affects the development of our automobile electronics industry. As the kernel and key of automobile electronic technique, we must study its hardware and software. This paper aims at electronic control unit (ECU) development. We widely absorbed domestic and abroad advanced technical achievements and applied advanced electronic technology; we discussed the automobile engine control theories; introduced the structure and working principles of the EMS; analyzed the principles and characteristics of various sensors and execution machines in the EMS. On this base, we designed the ECU hardware and software. 1 ECU hardware design Aiming at the requirements of the engine management System (EMS), we determined the EMS sensors and execution machines. Through evaluating various controlling CPUs, we take XC167CI-16F40F, a high performance 16-bit microcontroller, as the main control processor that is specially designed for automobile electronics and industrial applications by Infineon. The treatment ability reaches 40MIPS (million instructions per second). There is a MAC inside the CPU and it possesses DSP treatment ability, high-speed programmable priority-level interrupts system, sample rate down to 50 ns. This is efficient to meet the demand of the engine control system. Single-cycle data transfer facilities via peripheral transfer controller (PEC), high performance Capture/compare units. This is particularly suitable for the injection and ignition control and the collection and treatment of rotation signal. There is a CAN interface inside and it could form CAN net with other controllers by this. We separately designed and tested the sensor signal adjustment circuits, execution machine driver circuits and data communication interface. We also expanded the CPU program and data memory and integrated various interfaces to finish the ECU hardware design. To debug system hardware, we design the JTAG-OCDS debugging interface as well. The ECU input side adopts the strong anti-noise and high precision signal treatment circuits to provide a accurate logical foundation for the EMS. The ECU output side adopts the smart power output control system. The microcontroller has the characteristic of high integration and strong reliability and it has self-diagnosis and self-protect function. We choose the SMD elements and multi-layer board design technique in the PCB design to ensure ECU has excellent electromagnetism compatibility. When designing the ECU hardware, we have taken the system expansion into full consideration and keep some circuits and pins for modifying the design. 2 ECU software design According to the view of software engineering, we designed the modularization-layered framework programming model. Modularization programming is an effective method to organize software project. Through organizing the software project as modules, it could divide the complex tasks into easier ones and it is helpful for the clarity. Different modules could be developed at the same time and debugged separately to increase the development efficiency. It will not affect other modules if a single module is modified. Aiming at the different controlled engines, it could produce new procedure rapidly by trimming the modules. By introducing the hardware abstraction layer, it is only needed to rewrite some bottom modules when modifying ECU hardware and it is no need to modify the higher control modules, this is helpful to increase the portability.Modularization layered framework programming model Layer 5—Application Layer (Control Strategy Layer) Various working conditions (start, warm-up, idle, full load, speedup and slowdown) Failure diagnosis MAP calibration and so on Layer 4—Application Support Layer (Function subprogram layer) Signals collection and transformation, such as coolant temperature, oil temperature, air intake temperature, air intake pressure, throttle position, pedal position, rotation speed and O2 sensor Execution machine drivers, such as fuel pump driver, ignition driver, and injection driver Universal subprogram, such as table operation and signal treatment, bus communication (RS232, CAN, LIN), air intake mass calculation, fuel injection calculation, ignition angle and dwell time calculation, EGR, turbo and so on. Layer 3—Operation System Layer (Real-time System) Task operation Synchronization operation Memory operation Layer 2—Hardware Abstraction Layer (HAL) Hardware drivers and diagnosis ECU internal circuit, such as memory, communication, A/D, PWM. Sensors and Execution machines, such as coolant temperature, oil temperature, air intake temperature, air intake pressure, throttle position, pedal position, rotation speed and O2 sensor Layer 1—Physical ECU hardware On the basis of respectively successful debugging of the independent units,...