JAJU802A January 2022 – October 2022
Boost converter is the most popular topology for PFC application. This is because boost converters have continuous input current that can be controlled with average current mode control to force input current to track changes in line voltage. Also higher inherent efficiency and wide duty cycle range makes it more attractive than buck-boost converter.
While basic single phase boost converter is adequate for low power non-isolated application, interleaving techniques provide additional advantages in high power motor drive application. The two phase interleaved boost converter is simply two boost converters in parallel operating 180° out of phase. The input current is the sum of the two inductor currents IL1 and IL2. Because the inductor’s ripple currents are out of phase, they tend to cancel each other and reduce the input ripple current caused by the boost inductors. The best input inductor ripple current cancellation occurs at 50 percent duty cycle. The output capacitor current is the sum of the two diode currents (ID1 + ID2) less the dc output current. Interleaving reduces the output capacitor ripple current ( IOUT) as a function of duty cycle. As the duty cycle approaches 0 percent, 50 percent and 100 percent duty cycle, the sum of the two diode currents approaches dc. At these points, the output capacitor only has to filter the inductor ripple current.