Photovoltaic inverter auxiliary source

Usually installed under the PV panel, micro inverter is required to have high power conversion efficiency, good thermal performance, small size and long lifetime. The conventional auxiliary power supply is usually a Flyback, either secondary side regulated (SSR) or primary side regulated (PSR).

Photovoltaic systems are continually evolving to improve their efficiency and financial viability. One trend is to move to larger strings of cells giving higher dc voltages to be converted to ac voltage for the grid. Cost savings result but auxiliary power supplies for monitoring and control need to accept these higher voltages as inputs.

The recommended maximum load current capability is 2 A, which is also enough for the auxiliary power of micro inverter which usually does not exceed 10 W power need. The Fly-BuckTM is also known as the isolated buck converter, where the isolated output is generated by adding a coupled winding to the filter inductor of a buck converter.

Simultaneously, the auxiliary power supply should be capable of delivering stable low-voltage rails for the control and sensing devices. The auxiliary power supply can be directly responsible for maintaining these voltages throughout system operation.

This requires the auxiliary bias supply, which takes power from the PV panel, to be able to produce both the non-isolated low voltage bias voltages for the DSP and signal acquisition circuit, and the isolate bias voltages for the inverter gate drivers' use. Figure 1-4 shows a typical power tree of micro inverter. Figure 1-4.

Cost savings result but auxiliary power supplies for monitoring and control need to accept these higher voltages as inputs. Photovoltaic (PV) power generation systems have always fought to justify themselves in terms of $/watt of generated power and are hampered by the initial low efficiency of the panels themselves.