Single Phase Semi-Converter And Full Converter

ASingle Phase Semi-Converter And Full Converter

In this topic, we will look at the circuit configuration of the semi-converter and full converter and the output of Semi-converter and Full-Converter and finally,we will discuss the difference between this two converter.

Single Phase Semi-Converter

For the positive cycle,T1 and D1 are in forward biased. At delay angle = alpha, a gate signal is given to the gate terminal of T1 and T1 will start conduction. And the path of conduction is (L - T1-A-R-B-D1-N) for the positive cycle.

For the negative cycle, T2 and D2 will be in forward biased while other two will be in reversed biased. At delay angle (wt = pi + alpha), the gate signal is provided to T2 and it will start conduction.And the path of the conduction is (N-T2-A-R-B-D2-L) for the negative cycle. So, the direction of Id through the load is same. Therefore, the output voltage is again positive.

The waveform of it is shown in fig_3 below.

Single Phase Full-Converter

The circuit diagram of the Full converter is shown in figure(3). The basic difference of it with Single Phase Semi-Converter in terms of power components is that the use of four thyristors instead of the use of two thyristors and two diodes as in Semi-Converter.

For the operation, in the positive cycle,T1 and T2 are in forward biased while T3 and T4 are in reversed biased. When the gate signal is provided at delay angle wt = alpha, T1 and T2 starts conducting. At wt = pi, the input voltage is zero, so load current will be zero and it stops conducting due to line commutation.

In the negative cycle, T3 and T4 are in forward biased while T1 and T2 are in a reverse biased when the gate signal is provided to T3 and T4, they start conduction and the path of flow of current is same as that in a positive cycle. Hence, the voltage across the load is positive as in the positive cycle.

The output waveform is shown in fig_3 below.

Differences

With a resistive load, the operation of both semi_converter and full_converter is same which can be verified from the output waveform given in fig_c.When the inductive load is used, the full converter is able to pump back the inductive load energy to the supply. Along with this, the rare few differences in load voltage vs. trigger delay angle.