Four-switch Drive With APFC For BLDCM Control System

This paper proposes a new brushless DC motor (BLDCM) driving controlsystem used in fan industry which is based on four fan developing directions:green drive, low cost, high efficiency and high level of integration.According to Boost state-space averaging method, this paper designs a kindof digital controlled power factor correction system. Using the active powerfactor correction (APFC) technology to reduce line current harmonic pollution ofthe proposed brushless DC motor driving control system, what is called greendrive. In order to get the unit power factor, reducing current total harmonicdistortion, current sampling problem in digital power factor correction isanalyzed in the paper, and a new current sampling method is proposed; Throughtheoretical analysis and derivation, this paper presents a duty ratio feed-forwardcompensation algorithm to improve current zero-crossing distortion, using ainput impedance analysis method to analyze the input impedance of the powerfactor correction system before and after the duty ratio feed-forwardcompensation, which is to analyze the current distortion problem and to validatethe proposed duty ratio feed-forward compensation algorithm.This paper researches on the three-phase four switch inverter instead oftraditional three-phase six switch inverter, which is in order to reduce inverterswitch numbers. The four switch inverter square wave operating mode in eachsector and voltage balance in capacitance bridge are studied to analyze fourswitch inverter driving control characteristics. This paper gives two kinds of thecurrent control technology of four switch driving control system, in view of thehysteresis current control technology is not suitable for low switch frequency, adouble PI current regulator current control technology is proposed to inhibit thecurrent distortion in low switch frequency of the four switch brushless DC motorcontrol system.This paper proposes a new brushless DC motor drive control system, whichis consist of a Boost active power factor correction rectifier and a square wavefour switch inverter. In which, the power switch and diode of the Boost rectifierare from a bridge leg of the traditional six switch inverter, the remaining two bridge legs and two capacitances are formed four switch inverter, and using asingle power integrated module (PIM) to achieve the above rectifier and inverter,which is in consideration of volume control problem to improve the systemintegration. The new control system hardware design and software design arepresented. Finally, the related experimental results of the proposed system aregiven.