Rail pressure control system and control method based on flow valve current

The invention provides a rail pressure control method and control system based on flow valve current. The method includes the steps: calculating basic target rail pressure as shown in the specification; correcting the target rail pressure; calculating and judging common rail pressure difference; calculating target driving current of a flow valve; calculating duty ratio; controlling flow valve opening; outputting PWM (pulse-width modulation) wave signals to flow valve driving hardware, controlling flow valve opening and adjusting the quantity of fuel entering a common rail pipe from a high-pressure oil pump metering unit when the common rail pressure difference devi controlled for the i time is smaller than Ps and a target PWM wave duty ratio Duty 2i controlled for the i time is equal to Duty 2i-1; i=i+1 and circularly executing the steps S1 to S6 when i is smaller than N; finishing when i is equal to N or an ECU (electronic control unit) receives stop commands. Power-on currentsampling precision can be improv