Fig.1.1. Single-phase fully controlled converter
When the thyristor converter has a resistive load, both the DC current and voltage will be in phase. As soon as the positive half-cycle ends, the current through thyristors T1 and T11 will be reaching zero after which they would be reverse biased due to the supply voltage embarking into negative half-cycle. This causes the voltage pulses to be spreading from firing angle α to π as shown in the Fig.1.2. Both the current in the DC link (Idc) and the current in the source (Is) will be discontinuous.