High gain step up DC-DC converter for DC micro-grid application

Abstract

In this paper a very high gain step up DC-DC converter is proposed. Maximum voltage gain in conventional boost converter like, switched inductor converter, switched capacitor converter, cascaded boost converter etc. are limited due to extreme duty cycle (i.e. duty cycle near to unity). Operation at extreme duty cycle leads to, serious reverse recovery problem at the switches, high conduction losses, high electromagnetic interference etc. Isolated converter such as fly-back converter, push-pull converter, forward converter, bridge converters etc. overcomes the above issues, where basically a transformer or coupled inductor is used to boost the voltage. But, inclusion of transformer or coupled inductor introduces voltage spike at the main switch and power loss due to leakage inductance. Recently, DC micro-grid gets major importance because of the significant increase in DC loads and demand of high quality power. These DC loads require different voltage levels based on their power ratings. Photo voltaic source (PV) is one of the prime source of energy in DC micro-grid. A very high voltage gain converter is necessary for DC micro-grid because of low PV source voltage. In this regard, here a step up DC-DC converter is proposed, which possess a very high voltage gain characteristic. Along with this, it provides the additional advantage of supplying power to two different loads (i.e. one for high voltage level and another for low voltage level), which makes it more suitable for DC micro-grid application. Steady state analysis and PWM control of the proposed converter are described in this paper. Theoretical verification of the proposed converter has been done by simulating it in MATLAB Simulink.