A simplified SVPWM algorithm research based on the neutral-point voltage balance for NPC three-level inverter

Abstract

Since the disadvantages of a lot of calculation for the traditional SVPWM algorithm in the three-level neutral-point -clamped (NPC) inverter, which is not easy to real-time control,a space vector PWM (SVPWM) algorithm based on 60° coordinate system is proposed. The coordinates of space vector are integeres by a simple coordinate transformation, and the basic vectors are achieved by the reference vector coordinate upward and rounded down respectively, whose effective time is calculated by the principle of Volt-seconds balance. The switching state equation is introduced to control the neutral-point voltage balance and the appropriate degrees of freedom are choosed. Because of the simplified SVPWM algorithm requires no judgment of sectors and avoids the complex trigonometric equations for real-time control of three-level inverter, the results of experiment show that this algorithm has less calculation amount than the traditional algorithm, and reduces the rotation of the motor pulse.