EE631 – Spring ECE631/EE631Q Lecture 9 – The Rectifier S.D.Sudhoff Purdue University

EE631 – Spring Restrictions on Firing And Commutation Let’s think about the a- phase current

EE631 – Spring Restrictions on Firing and Commutation Angle Thus, we must have –(1)  >0 –(2)  +u< 

EE631 – Spring Modification for Mode II Operation We can use our work for Mode 2 as well as Mode 1 if we make some additional modifications…

EE631 – Spring Modification for Mode II Operation Solution approach

EE631 – Spring Modification for Mode II Operation

EE631 – Spring Modification for Mode II Operation Thus, the effective firing angle must obey

EE631 – Spring Numerical Example Consider a system with a 560 V l-l rms voltage source, 20 mH commutating inductance, and operating at 60 Hz Let’s look at the output characteristics as dc link current varied from 0 to 100 A

EE631 – Spring Operating Mode

EE631 – Spring Output Voltage

EE631 – Spring Commutation Angle

EE631 – Spring Effective Firing Angle

EE631 – Spring Calculation of AC Currents Let’s consider the current in the generation source reference frame, i.e. the reference frame wherein

EE631 – Spring General Approach The average q- and d-axis current may be expressed

EE631 – Spring Commutation and Conduction Components Breaking the integrals up we have where

EE631 – Spring Calculation of Commutation Component We start with

EE631 – Spring Calculation of Commutation Component

EE631 – Spring Calculation of Commutation Component

EE631 – Spring Calculation of Commutation Component Finally, we arrive at ( ) ( )

EE631 – Spring Calculation of Conduction Component During the conduction interval

EE631 – Spring Calculation of Conduction Component

EE631 – Spring Calculation of Conduction Component

EE631 – Spring Calculation of Conduction Component Thus we arrive at ( ) ( )