A digital control circuits for a six-pulse bridge cyclocon-verter is designed and implemented. The logic of the firing circuit has been discussed in detail.
The frequency and amplitude of a three-phase output voltages are independently controlled. The open-loop speed control of a squirred-cage induction motor has been achieved under the constant flux operation.
Provision has been made for changing the phase sequence at the output in order to change the direction of rotation of the motor. Experimental results include the output waveforms of the various load conditions and frequencies.
