NTT Energy and Environment Systems Laboratories

Project

• First Promotion Project

Up to now

• It would be wonderful if mobile phones could be powered by solar cells or fuel cells, but the iroutput voltage is unstable when they are connected in series.
• Isn't there a solar cell that is simpler to use and provides good performance?

At the NTT

We have developed an ultra-low-voltage booster circuit that enables digital handheld devices to work even if fuel cells or solar cells are not used without series connection. Adopting this technology, even weak energy generated around the user can effectively be harnessed to power handheld devices.

The feature set of mobile phones continues to expand, so people can now carry a digital camera, a music player, video games, and even a miniature TV around in their purse or pocket. The problem is that the battery capacity hasn't changed much, so for example if you try to watch TV for any length of time, the battery is drained very quickly. Much attention has focused on solar cells and fuel cells asasolution, but the conventional approach of connecting these elements in a series is technically laborious and costly. Moreover, in the case of solar cell, even partial shading diminishes the power extremely to the terminal, so a new method of extracting energy without connecting the cells in a series is required. This led us to invent a technology for boosting extremely low voltages of about 0.3 volts so the power-generating cells do not have to be connected in series, and to develop a robust power-generating system that continues to perform well even in partial shade and when scuffed and dirty.

Point!

Our new ultra-low-voltage circuit enables even single solar cells or fuel cells to be used, thus sloving the previous problem of having to connect power-generating cells in series.