Research On The Drive And Control System Of The Piezo Injector For High-pressure Common-rail

Compared with the solenoid valve injector, piezoelectric injector has faster response speed, good repeatability, without delay.The response speed of piezoelectric injector is 3~4 times faster than of solenoid valve injector and reached 100 us. It can flexibly and precisely control the pre injection, main injection and after injection spray processes, such as the best effect of fuel atomization. And, in the same engine speed and 160 MPa of the injection pressure, fuel consumption reduced by 25% ~ 30%, 3 db noise reduction, emissions of harmful substances was reduced by 20%.First, this paper analyzes the characteristics of piezoelectric actuator and piezoelectric material, structure of sensor actuator. Then, analysis the piezoelectric actuator drive system, the voltage and current drive mode of their respective characteristics, select the current drive mode piezoelectric actuators. At the same time, this paper has established a way of implementation model of PWM switch mode according to the comparisons of several different driving means based on the characteristics, and designed the drive principle of PWM switch type of piezoelectric actuator.Based with the analysis of the discussion about the way to drive a piezoelectric actuator, we have confirmed the modularization of the piezoelectric actuator's control system, including the ECU major control module, DC/DC voltage rising module, power giving module, charge-discharge control module, sampling feedback module and so on. What's more, we have analyzed the requirement and the designing scheme of the concrete modules, so we have designed the concrete circuit according to this scheme.On the designed piezoelectric actuator driving control hardware platform, we have analyzed the three current driving ways: Single peak current, constant current and more peaks current, about their own difficulty of implementation model, the influence of the driving voltage and the driving current of piezoelectric actuator, finally we have confirmed the more peaks current driving way. At the same time, we have compared two PWM signal way, and analyzed their own characteristics, then we verified the advantages of variable duty cycle PWM. Then we have given three kinds of driving ways of piezoelectric actuator and their own advantages and disadvantages, also we have given the idea of the way of adjusting PWM signal's parameter based on the feedback of driving voltage and driving current. On this basis, we proposed a control algorithm which satisfies the system(the adaptive parameter control), and we realized the system real-time, the management of reliability, and we designed the software of the whole system.Finally, according to the designed software and hardware platform combined with the concrete driving strategy and controlling algorithm, this paper did some actual measurements of piezoelectric actuator's driving control process, also analyzed the real effect of concrete driving ways and strategies. We have verified the feasibility and the superiority of the final scheme.