The Voltage Source Inverter (VSI) shown in the figure below is switched to provide a 50 Hz, square-wave ac output voltage (vo) across an R-L load. Reference polarity of vo and reference direction of the output current io are indicated in the figure. It is given that R = 3?, L = 9.55 mH.In the interval whenΒ vo < 0 and io > 0 the pair of devices which conducts the load current is