GATE Electrical Engineering (EE) 2016 Shift 2 Solved Paper

A single-phase bi-directional voltage source converter (VSC) is shown in the figure below. All devices are ideal. It is used to charge a battery at $400\mathit{V}$ with power of $5\mathit{k}\mathit{W}$ from a source ${\mathit{V}}_{\mathit{s}}=220\mathit{V}$ (rms), $50\mathit{H}\mathit{z}$ sinusoidal AC mains at unity p.f. If its AC side interfacing inductor is $5\mathit{m}\mathit{H}$ and the switches are operated at 20 kHz, then the phase shift $\left(\mathit{\delta }\right)$ between AC mains voltage $\left({\mathit{V}}_{\mathit{s}}\right)$ and fundamental AC rms VSC voltage $\left({\mathit{V}}_{\mathit{C}1}\right)$, in degree, is _________.