Current ripple calculation for dead time compensation in three phase PWM inverters

As switching power converters are becoming widespread, the power quality of inverters and active rectifiers is becoming increasingly important. Effective dead time is a major cause of harmonics in the output current of voltage sourced PWM converters. The traditional dead-time compensation methods can only handle high current operating conditions well. Several methods capable of accurately compensating at low current conditions and zero crossing or discontinuous currents require the actual value of the current ripple which is measured between the two switch-over points within a switching period. In this article, a new definition is given for the current ripple used in dead time compensation, and a method is described for its calculation. The calculation method was simulated in Matlab Simulink together with a linear interpolation based dead time compensator on a three phase grid connected inverter model. The resulting THD values are compared to other dead time compensation methods.