A low cost DC uninterruptible power supply with capacitor isolation

We are in an era witnessing the rise of low power real time embedded systems. Automated embedded systems like security and monitoring systems are no longer considered luxury but as an essential part of our lives. One of the most important features of such a system is its ability to function in the absence of AC main supply. This paper presents a simple, robust, easy to build, low cost uninterruptible power supply that prioritizes main supply while simultaneously monitoring back up battery. The paper highlights the modularity of the design, and the ease of its re configurability that is application specific, all while maintaining a low cost approach. In the event of a power failure, the circuit switches instantaneously with filter capacitor isolation from the circuit. This enables quick response and retention of capacitor charge saving energy and the need for a bleeder. The design is also inspired by an all relay switching, which significantly reduces static power dissipation.