Example $3$:

Consider a full$-$bridge single$-$phase inverter with input voltage equal to $400$ V $.$ The load is a pour resistor with magnitude equal to $20$ ohms. This inverter is controlled by single PWM technique with amplitude modulation index equal to $0\mathrm{.}5.$

If the single PWM technique is replaced by the unified PWM technique with $4$ pulses in each half cycle, to have same power at the output side, calculate the new amplitude modulation index. Also, calculate the output power.