Modified SEPIC converter.

           In modified SEPIC converter, a voltage multiplier circuit is applied to the classical boost converter, for higher output voltage, improved efficiency and low switch voltage. This is done by adding diode D_M and Capacitor C_M to the classical SEPIC as shown in fig..

            Capacitor C_M of the modified SEPIC is charged with the output voltage, hence when the switch is conducting the voltage applied to inductor  is higher than that in traditional SEPIC. In case of modified SEPIC converter, the losses due to diode reverse recovery current are reduced and soft commutation is obtained with regenerative snubber circuit. The static gain of modified SEPIC is higher than classical boost converter for high values of duty cycle, and low input voltage.A gain up to 5 is considered as standard static gain, gain larger than 10 is high static gain and that larger than gain equal to 20 is considered as very high static gain. If compared with other converters for high gain, modified SEPIC utilizes lesser number of switches and less passive components than those converters.

           The main purpose of magnetic coupling in modified SEPIC is to increase the voltage gain leading to boost in the output voltage. In past various other techniques like voltage multiplier, interleaved boost converter, zero voltage switching boost integration technique, etc each of them have certain advantages and disadvantages and can be implemented as per application. If compared with these techniques for high gain, proposed modified SEPIC with magnetic coupling utilizes lesser number of switches and less passive components.

The theoretical explanation, working and simulation results of modified SEPIC without magnetic coupling and modified SEPIC with magnetic coupling are explained in following sections. For magnetic coupling an inductor operating as a flyback transformer is used.