3. A single phase semiconverter is supplying RLE load and has a freewheeling diode across the load. The firing angle is a. The freewheeling diode conducts for
7. Two single phase semi-converters are connected in series to form a series converter. The input is v = Vm sin ?t and a1, a2 are the firing angles. If a1 = 0, the dc output voltage is