METHOD AND SYSTEM FOR DEAD TIME COMPENSATION IN A PWM CONTROLLED INVERTER

A method is suggested for compensating the dead time effects in a pulse wide modulated voltage sourced inverter, PWM VSI, comprising in each phase a pair of semiconductor switching elements (SW1, SW2) connected in series between DC voltage rails of a DC power source and a pair of diodes (D1, D2) connected in series between the DC voltage rails of the DC power source wherein each of the diodes (D1, D2) is connected antiparallel with a respective semiconductor switching element (SW1, SW2), wherein each phase output node (A, B, C) is connected to an LC filter circuit. The method comprises the steps of - providing a PWM control signal for controlling the switching state of the semiconductor switching elements (SW1, SW2) in each phase leg, - taking measurement samples of different parameters influencing the voltage (Ub) of a phase leg cyclically. The method is characterized in the further steps of - selecting the frequency of taking the samples so that at least one sample of the parameters is taken during each half period of the PWM carrier signal, - using the time of taking the measurement sample as a time stamp, - determining the number of already switched over phases in each half period of the PWM carrier signal for the actual time stamp, and - carrying out an in-cycle correction of the duty cycle (D) for the phases not yet switched over. Also suggested is a system for implementing the method.