Dead time and nonlinearities compensation for VSI feeding AC drives

This paper presents a recursive nonideality compensation method for Voltage Source Inverter (VSI) controlled by Predictive Current Control (PCC) in the field of electrical drives. An accurate mathematical model of the effects of VSI nonlinearities, such as dead time and control delay, is here reported including the magnitude loss and the ripple distortion. For every sampling interval, the exact voltage error and ripple time-shift is calculated using only reference and real phase currents. As soon as a steady-state operation is detected, the voltage error of the entire fundamental period is stored in an array and then used to accurately compensate the VSI output voltage in the next fundamental period. The error array is renewed after every transient and a look-up-table is step-by-step built including the motor operating conditions and related voltage error. Experimental and numerical results validate the effectiveness of the proposed algorithm in reducing the VSI voltage and current distortions and their influence on the motor torque and efficiency.