High voltage common rail piezoelectric actuator driving current control circuit

Abstract

The invention discloses a high-voltage common rail system piezoelectric actuator charging and discharging drive current control circuit. The circuit comprises a charging current modulation circuit, a discharging current reversal processing circuit and a discharging current modulation circuit. In the charging current modulation circuit and the discharging current modulation circuit, along with the change of charging currents and discharging currents, the connection relation of resistors in a current threshold value voltage division circuit is directly affected through switching device transistors, the change of current threshold values is controlled, the two threshold values are converted with each other, and PWM signals determined by the two current threshold values are output through the charging current modulation circuit and the discharging current modulation circuit. The circuit has the advantages that the magnitude of the charging and discharging drive currents of a piezoelectric actuator is controlled, the drive circuit is simple and feasible, the modulation process of the drive currents is completely achieved by hardware, consistency of the currents is basically guaranteed, and meanwhile occupied MCU resources are fewer.

Description

technical field [0001] The invention relates to piezoelectric actuator drive technology, in particular to a piezoelectric actuator drive current control device for a high-voltage common rail system of a diesel engine. Background technique [0002] Before the piezoelectric actuator is injected, the energy stored on the piezoelectric actuator is very small, and the voltage of the piezoelectric actuator is very low. When the piezoelectric actuator starts to inject fuel, it is directly charged with 150V voltage. At the initial moment of charging, The current flowing through the piezoelectric actuator will be very large, which may lead to a large acceleration of the piezoelectric actuator’s elongation and deformation. Although this problem can be alleviated by adding a preload, if a piezoelectric actuator is designed to charge Putting the loop drive current control circuit will fundamentally solve this problem. Similarly, if the discharge current is too large, the deformation ac...

AI Technical Summary

Problems solved by technology

The deficiency and reason of this patent: 1. The duty ratio and frequency of the PWM signal generated by CPLD frequency division is an empirical value set by the individual, and this scheme has certain requirements for the logic timing of the PWM signal and the charging enable signal. Software programming is complex and takes up resources. If this logic sequence is not followed, the charging current waveform will be inconsistent, and the charging time will be different each time. In addition, the patent does not perform closed-loop control on the discharge current of the piezoelectric crystal.

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