Single phase fully controlled halfwave rectifier with resistive Load -Circuit Diagram & Waveforms
Single phase fully controlled half wave rectifier with resistive load:
This type of configuration is hardly used in practice.
At ωt = 0 when the input supply voltage becomes positive the thyristor T becomes forward biased. it does not turn ON till a gate pulse is applied at ωt = α. During the period 0 < ωt ≤ α, the thyristor blocks the supply voltage and the load voltage remains zero. no load current flows during this interval.
As soon as a gate pulse is applied to the thyristor at ωt = α it turns ON. The voltage across the thyristor collapses to almost zero and the full supply voltage appears across the load. From this point onwards the load voltage follows the supply voltage. The load being purely resistive the load current io is proportional to the load voltage.
At ωt = π as the supply voltage passes through the negative going zero crossing the load voltage and hence the load current becomes zero and tries to reverse direction. In the process the thyristor undergoes reverse recovery and starts blocking the negative supply voltage. Therefore, the load voltage and the load current remains clamped at zero till the thyristor is fired again at ωt = 2π α. The same process repeats thereafter.