Research On Sensorless Control System Of BLDC For Electric Fuel Pump

As an important part of automotive electronic control fuel injection system, thefunction of electric fuel pump is to suck out fuel from the fuel tank and then transport itto the fuel injection system. Fuel pump commonly uses brush DC motor as its powerplant. Because brush DC motor is commutated through the brush and commutator, it hasa short life span and bad EMC performance, and is difficult to be maintained when aproblem occurs. Especially for methanol fuel vehicles, due to the corrosive effect of themethanol, the fuel pump life will be greatly shortened, which limits the furtherpromotion of methanol fuel vehicles.Because BLDC is commutated though electronic control, it has no sparks, noelectromagnetic interference, and high reliability. In this paper, BLDC is used to replacebrush DC motor as the fuel pump drive equipment, which could greatly extend the fuelpump life, reduce the use cost of the methanol cars, and has great economic benefits.This paper does research on the sensorless control system of brushless fuel pump.Firstly, this paper briefly introduces the working way of BLDC and the principle ofterminal voltage detecting method, and proposes an algorithm for compensating thephase-shift error caused by filter circuit. Based on a brief discussion of different PWMstrategies, a detailed analysis about the errors caused by PWM modes in rotor positiondetection and current detection is given in this paper. Finally, the paper analyses theeffect of freewheeling diodes on rotor position detecting in the commutation process.The research on the common problems in the sensorless control has importantsignificance for improving the detection accuracy of rotor position and achievingcommutation control of brushless fuel pump.This paper establishes a simulation model of the sensorless control system ofbrushless fuel pump in MATLAB/Simulink. The simulation results of the control systemverify its reliability. Possible failures are studied by the simulation model, which couldprovide important reference for fault diagnosis of the sensorless control system.Based on the simulation results, the overall scheme of the sensorless controlsystem of brushless fuel pump is designed. Then the hardware circuits and softwareprograms are designed, and the basic composition and working principle of eachmodule of the control system are described in detail. Experimental results show that thefuel pump controller designed in this paper could work properly and achieve theprotection function, and its performance could meet actual needs.