A single-phase full-bridge voltage source inverter feeds a purely inductive load, as shown in the given figure, where T₁, T₂, T₃, T₄ are power transistors and D₁, D₂, D₃, D₄ are feedback diodes. The inverter is operated in square-wave mode with a frequency of 50 Hz. If average load current is zero, what is the time duration of conduction of each feedback diode in a cycle?