NPC three-level BLDC torque ripple minimization control method based on duty ratio modulation

Abstract

The invention provides an NPC three-level BLDC torque ripple minimization control method based on duty ratio modulation, and the method comprises the steps: firstly obtaining a three-phase stator current through a current sensor, and obtaining a rotor position angle and an electric angle speed through an encoder, so as to calculate three-phase counter electromotive force at different rotor positions; obtaining a dq-axis current prediction value at a k + 1 moment through coordinate change and a current prediction model; obtaining the action time of the optimal vector through a duty ratio calculation module; and finally, outputting a switching state which is beneficial to inhibiting midpoint potential fluctuation through midpoint potential balance control so as to drive the motor. Through duty ratio modulation, the torque ripple of the brushless direct current motor is effectively reduced, and the fluctuation of the neutral point potential of the NPC three-level inverter is inhibited through neutral point potential balance control.

Description

technical field [0001] The invention relates to a duty ratio modulated NPC three-level BLDC torque ripple minimization control method, which belongs to the field of motor drive and control. Background technique [0002] Brushless DC motor (brushless DC electric motor, BLDC) has the advantages of simple structure, large starting torque, no commutation spark, and long service life, and has received extensive attention in the fields of electric vehicles, aerospace, industrial control, and automation. Traditional brushless DC motor control methods mainly include square wave control, vector control and so on. The square wave control uses the Hall position sensor or the non-position control algorithm to commutate once every 60 degrees of electrical angle according to the rotor position, and can obtain a current waveform similar to a square wave, which has the advantages of simple control and low hardware requirements. It has the defects of large torque fluctuation and low efficie...

AI Technical Summary

Problems solved by technology

However, the traditional model predicts the current control, only one voltage vector is applied in one sampling period, and it is difficult to ensure that the actual value of the current accurately tracks the change of the reference value of the current, resulting in large torque fluctuations and affecting the steady state of the system performance

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