Power Electronics and Motor Drive Systems

5.4. Asymmetric or Half-Controlled Rectifiers

Fig. 5.21 shows the power circuits of two half-controlled rectifiers. As shown in this figure, for the implementation of these rectifiers, thyristors and diodes are used. The half-controlled rectifier is composed of two connected in series rectifier stages: the upper stage which is implemented by thyristors and the lower stage which is implemented by diodes. The upper stage generates positive controlled voltage and the lower stage generates negative uncontrolled voltage. Fig. 5.22 shows the waveforms of the single-phase half-controlled rectifier of Fig. 5.21(a). As shown in Fig. 5.22(a) and (c) the output voltage v_o1 is controllable but not v_o2. Half-controlled rectifier topologies cannot control their ...