Solar Battery Charger

Project Description:

The CMOS Solar-Powered Battery Charger is a unique approach to solve the rapidly growing need for more renewable energy sources and sustainable practices in our ever-evolving world. This design would enable both the usage of clean solar energy for charging and increase the usage of rechargeable batteries, eliminating the single-use batteries that currently plague many of our landfills and devices. Furthermore, the rapid development in technology over the past few decades has enabled many of our devices to shrink in size; however, the charging systems for these devices have remained mostly stagnant, only slightly decreasing in recent years. The CMOS solar-powered battery charger would allow for a smaller charging system that could be housed in smaller packaging. Thus, making the charging pack smaller and more portable, allowing access to critical energy infrastructure in remote locations without readily available connections to the power grid.

To implement the CMOS Solar-Powered Battery Charger, a 130nm CMOS fabrication process has been selected using the SkyWater130 Foundry’s process design kit(PDK). The overall design of the CMOS Solar-Powered Battery Charger has been implemented in three parts: the Boost Converter, the Boost Converter Control Circuitry, and the Battery Charger. The Boost Converter takes the output of the solar cell array and steps it up to a larger voltage, 5V, which will then power the Battery Charger Circuitry. To regulate this 5V output, the Boost Converter Controller will be used. This circuit works by sensing the output voltage and comparing it with a 5V reference. The differential signal between the output and reference signal becomes the input of a PI controller, which then modulates the duty cycle of the boost converter switching to track and ensures the output voltage is very close to 5V. Lastly, the Battery Charger is used to take the output from the Boost Converter and use it to charge the battery. To do this, the battery charger will monitor the charge stored in the battery by monitoring its voltage, and then select between various operating modes, Trickle Charge, Constant Current, Constant Voltage, and Maintenance modes, controlling the amount of current that flows into the battery. Ensuring efficient battery charging and protecting the health and longevity of the battery. 

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