Switched-Inductor Boost Converter

12V - 48V @ 1A A switched-inductor type boost converter has multiple inductors that are charged in parallel but discharged in series, thereby putting multiple boost inductors in series to the input power supply. The two diodes above and below the inductors enable parallel charging of the inductors when the MOSFET is on and the two diodes in series with the inductors put them in series to the input when the MOSFET is off. This results in an increased "boost" for the same duty cycle compared to a single inductor type boost converter. The output voltage of a boost converter is given by the formula Vo = Vin*n/(1 - D) This circuit runs at a duty cycle of 65% and outputs 48V. A normal boost converter with an efficiency of 90% would output Vo = 12*0.9/(1-0.65) = 30.85V The output voltage of a two-inductor switched boost converter for the same duty cycle is Vo = Vin*n*(1+D)/(1-D) Substituting the appropriate values, Vo = 12 *0.9*(1+0.65)/(1-0.65) = 50V This circuit, in reality, outputs 48V. An LTspice simulation of the same circuit achieved 92% efficiency.

published 5 years ago