Question

A single-phase voltage source inverter shown in figure is feeding power to a load. The triggering pulses of the devices are also shown in the figure.
If the load current is sinusoidal and is zero at $0,\pi ,2\pi ,...,$ the node voltage $V_{AO}$ has the waveform

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

The load current waveform is



When $S_1$ and $S_4$ switches are on


Voltage $V_{AC}=\frac{V_{DC}}{2}$

When $S_2$ and $S_3$ switches are on



Voltage $V_{AC}=-\frac{V_{OC}}{2}$


When the switches are off.
The current direction from $0$ to $\pi$ is positive so it is in the direction given in the circuit. $0\le \omega t\le \pi$

Voltage $V_{AO}=-\frac{V_{DC}}{2}$
$\pi \le \omega t\le 2\pi$

The load current is negative so the current direction will be opposite to given direction.



Voltage $V_{AO}=-\frac{V_{DC}}{2}$
so, the complete voltage $V_{AO}$ is