Microinverter Using Li-Ion Battery

Department of E&EE, NMAM Institution of Technology, Nitte, Nitte (Deemed to be University), Karkala, India

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Abstract

The micro-inverter is small, compact source of energy and can provide a single-phase output voltage of 230v and support a load power of 150W. This microinverter can be used to power up devices such as Wi-Fi routers, mobile chargers, Closed-Circuit Television (CCTV) cameras, emergency medical equipment, emergency lights, etc. The DC power required for the inverter is obtained from the stack of Li-ion batteries connected in a series-parallel combination. The charge controller ensures the charging of the individual battery of the stack has a balance of charging and provides the protection required for the battery. Existing microinverters use lead acid battery. The proposed converter uses Lithium-ion batteries as they are more efficient compared to lead acid batteries and require less space, have low self-discharge, and have higher energy density. The charge controller has been designed and simulated. The final circuit is fabricated on a Printed Circuit Board (PCB) which ensures uniform charge distribution optimizing the size and heat dissipation. The inverter uses a modified sinusoidal pulse width modulation signal generated by a PIC microcontroller. The H-bridge configuration uses MOSFET as a switch and is driven by opto-isolators. The 12V AC output of the H-bridge is converted into 230V ac using the step-up transformer. Testing of the project is carried out at individual stages, and the results are verified with theoretical values.