Analysis of Commutation Interval of Modifbed-Switch-Parallel-Commutation Chopper

Abstract

The commutation of chopper circuit can be obtained in many ways. Some of them are, (i) Switch-parallel (ii) Load-parallel and (iii) source parallel commutation. This paper gives detailed study of commutation interval of modified-switch parallel-commutation-chopper. It gives detailed study of load voltage, load current-, thyristor-1 current-, thyristor-2 current-, diode current-, diode-1 current-, capacitor voltage- and capacitor current-waveforms. It presents time interval analysis of the modified-switch-parallel-commutation-chopper circuit during only the commutation interval and disadvantages involved. The paper proposes to replace diode D₁ by Thyristor TH³ and injects concept of extended ‘on-time’ of the thyristor TH¹. Hence the desired variable pulse-width can be obtained even after TH³ has turned off.