This Small Business Innovation Research (SBIR) Phase I project will research and develop an efficient, integrated single-chip solar powered charge control circuit charging lithium ion (Li-Ion) and nickel metal hydride (NiMH) batteries from micro-solar panels for remote sensor and portable electronic applications. To achieve this goal, our investigation will focus on the following areas: 1) Research and development of an efficient power control algorithm and boost circuit optimized for applications using micro-solar cells, 2) Research and development of programmable embedded control circuits required to automatically control proper charging of Li-Ion and NiMH batteries. The intellectual merit of the proposed activity is to provide efficient, low cost solar energy harvesting solutions for autonomous sensor and mobile consumer electronic products. At the end of this project, an integrated, single chip maximum power point tracking (MPPT) circuit with integrated voltage boost and programmable battery charger circuitry will be demonstrated. The novel automatic MPPT algorithm enables a single solution for 1 to 8 cell panels without a change in circuit board parameters and eliminates the need for external microcontrollers. The integrated boost/MPPT features do not exist on the market today.
The broader impact/commercial potential of this project is very large because of the scalable nature of this technology. Scalable energy harvesting system blocks have application to solar charging for portable products, autonomous wireless sensors for real time system control, and larger rooftop solar harvesting for residential and industrial applications. This wide application space represents a significant opportunity to enable harvested renewable energy and reduce dependency on non-renewable energy sources. From a commercial perspective, all of these applications are anticipated growth markets over the next decade. Growth in cell phone use in developing regions like Africa, India, and China offers a large opportunity for solar charging. In addition, the recent earthquake in Japan has highlighted the need for solar charging for cell phones and flashlights when the power grid is vulnerable to natural disasters. Efficiency improvements in new wireless sensors systems and residential/industrial solar power systems will drive new demand and provide reduced costs of adoption for consumers. The results of this research project will increase solar energy harvesting effectiveness for small and large systems thereby providing consumers with new choices for energy savings and new freedoms for grid-independent power.
Triune Systems successfully completed demonstrated a fully functional solar switch-mode DC converter and an efficient, low-cost maximum point power tracking (MPPT-lite™) algorithm for a single- and multi-cell switch-mode converter, along with ultra-low quiescent current analog circuits using the companies nanoSmart® technology . The results of this research are extremely encouraging and provide a path to commercially viable integrated circuit products for energy harvesting applications. The intellectual merit of the proposed activity is to provide efficient, low cost solar energy harvesting solutions for autonomous sensor and mobile consumer electronic products. An integrated, single chip maximum power point tracking (MPPT) circuit with integrated voltage regulation and programmable battery charger circuitry was demonstrated. The broader impact of this research and development is to provide system blocks for energy harvesting systems, thus enabling several of the harvesting and storage technologies currently under development in the US; to gain greater market acceptance of solar powered products, and thereby reducing energy demand from non-renewable sources; as well as creating technical leadership in the US for this market space. With the availability of these solar powered battery charger solutions, system designers will be able to more effectively leverage solar power for small form factor applications. While initially targeted at micro-solar applications, the MPPT/converter integration described in this proposal is easily scalable to off-grid infrastructure applications, such as powering pico-cell and femto-cell cellular basestations. By providing extremely compact and efficient solar panel operating power control, the technology could also be used to increase the system efficiency of higher wattage residential and industrial solar power generation applications by ensuring each individual solar cell operates at its peak power condition. In Phase IB, two solar energy harvesting prototype systems, a supplemental power solar charger and a solar powered wireless shelf tag, were developed using to successfully demonstrate market viability for commercialization of the nanoSmart® devices and MPPT-lite™ technologies.