Configuration 1: Solar Home Charge Controller Configuration 2: Sunblazer Solar PV Solar PV Charge 24-V Controller Batteries dc/dc Converter 12-V Batteries dc Loads Batteries Configuration 3: ac Microgrid Solar PV Configuration 4: dc Microgrid Solar PV Synchronizing Inverter dc/dc Converter ac/dc Adapter Charge Controller Batteries dc Microgrid Generator ac Microgrid Batteries Figure 11. Common microgrid configurations that can be operated by the IEEE Smart Village universal charge controller. [Figure courtesy of Arizona State University (Shammya Saha and Nathan Johnson).] The UCC (Figure 12) is a modular solution capable of addressing all the mentioned use cases. The system was separated into four modules, one for each input source. xx Module 1: Charging from a 24-Vdc battery system (similar to the IEEE Sunblazer setup). xx Module 2: Charging from a solar panel with an open circuit voltage between 18 and 24 V. xx Module 3: Charging from a dc source with open circuit voltages between 50 and 70 V. This is useful for larger solar PV arrays and dc microgrids. xx Module 4: Charging from was created specifically for ac inputs, which includes an externally connected ac/dc adapter providing a source voltage between 19 and 21 V. The minimum battery capacity for the UCC was set at 20 Ah based on the battery size used for the Sunblazer portable battery kit. The maximum battery capacity was 200 Ah, which was chosen based on common battery sizes in a solar home system. The UCC was also designed to permit the use of lead acid or lithium ferrophosphate (LiFePO4) battery chemistries. Testing and validation of the design parameters are currently underway using a development board (DC2069A), based on integrated circuit LT8490, to create a prototype design that can handle the wide range requirement for input-output voltage and current. The DC2069A board was used to charge batteries of different ampere-hour capacity from two different types of sources, 24-V battery bank as the input-voltage source and solar panel as the input-current source. Module 1 Module 2 Module 3 Solar PV Home Sunblazer 24 Vdc dc Microgrid 18-24 Vdc 50-70 Vdc Port C1 Port C2 Universal Charge Controller Buck Buck Module 4 12 Vdc Battery Port Port C3 19-21 Vdc 110/220 Vac ac Rectifier Microgrid Load Port 12-24 Vdc 12-V/24-V Battery Loads Key: Controller dc ac Converter Figure 12. A block diagram of a system topology and connections for the Universal Charge Controller designed by Arizona State University. [Figure courtesy of Arizona State University (Shammya Saha and Nathan Johnson).] Figure 13 shows the test results from a 290-W solar panel charging a 12-V, 20-Ah battery. The current flowing to the battery varied per variation of irradiance. The battery IEEE Electrific ation Magazine / j une 2 0 1 7 15