Solar micro-inverters' work is based on Digital Signal Controller (DSCs) that boast powerful algorithms to provide the features of both off-grid and on-grid inverters, so that functions such as MPPT (Maximum Power Point Tracking), charge management, inversion, and connection with grid can be enabled on a single device. A micro-inverter is built with battery charge management, an inversion circuit and a relay.
Battery charge management includes a DC-DC module, and circuits for detection of input/output voltage and current. It provides MPPT and charge management functions under the control of a DSC. Inversion circuit is made up of four circuits:
- An input filter circuit implemented with filter capacitors which are used to reduce input voltage ripples;
- A boost circuit which includes a Schottky diode, an inductor and a DSC-driven MOSFET to boost a low DC voltage (usually 12-36V) provided by batteries to a high DC voltage;
- A single-phase full-bridge inverter which consists of 4 MOSFETs driven by a DSC to convert high-voltage DC power into 50-60Hz AC power;
- An output filter circuit that uses two inductors and a capacitor to eliminate harmonics of output voltage.