Title :
A new thyristor inverter without external commutation for AC motor control
Author :
Venkata Ratnam, K. ; Prasad, Dinkar
Author_Institution :
IIT, Kharagpur, India
Abstract :
The paper presents a new thyristorised inverter without the necessity of external commutation circuits for 3 phase induction motor control. The DC input is fed to the inverter through a fast acting load-commutated DC to DC thyristor chopper without any filter in between. The chopper output consists of a series of high frequency (1 to 3 kHz) saw-tooth shaped voltage pulses which are appropriately transferred to the three phase load by the inverter. Barring the high frequency capacitor used in the chopper, there are no other force-commutation elements. Only one snubber circuit at the input end of the inverter is sufficient. The turn-on and turn-off losses are small since the switchings are mostly soft. The paper explains the operation of the inverter with its control circuits and presents experimental results regarding voltage and current waveforms when used to drive a laboratory size induction motor
Keywords :
DC-AC power convertors; DC-DC power convertors; choppers (circuits); commutation; electric current control; induction motor drives; invertors; losses; machine control; snubbers; switching circuits; thyristor convertors; voltage control; 1 to 3 kHz; 3 phase induction motor control; AC motor control; DC input; current waveforms; force-commutation; high frequency capacitor; high frequency saw-tooth shaped voltage pulses; load-commutated DC to DC thyristor chopper; snubber circuit; soft switching; thyristor inverter; turn-off losses; turn-on losses; voltage waveforms; AC motors; Choppers; Circuits; Commutation; Filters; Frequency; Induction motors; Inverters; Thyristors; Voltage;
Conference_Titel :
Power Electronics and Drive Systems, 1995., Proceedings of 1995 International Conference on
Print_ISBN :
0-7803-2423-4
DOI :
10.1109/PEDS.1995.404937
