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Suggestions for isolated AC/DC ,DC/DC power supplies for String inverter

archit khandelwal
Prodigy 190 points
Other Parts Discussed in Thread: UCC28742, UCC28710, UCC28600

Hi, 

I am developing a 3kW String Inverter.

For our circuit to be functional, we require certain basic voltage levels-

1. +5v for microcontroller, sensors

2.+12v for sensors and relays

3.+21-24V for IGBT gate supply  

Our Solar PV input will be generally in the range of 100-600V and as it is a GRID-TIED inverter we have AC input as well.

So we can consider two types of voltage inputs when designing for power supply     1.  DC from Solar PV

                                                              2. AC from Grid (230V, 50hz)

 I need suggestion/advice regarding-

1.  What points to consider or how to identify which input option is suitable for the generation of a particular voltage level required to operate a string inverter circuit. For eg. For the  IGBT gate driver supply should I go for Isolated AC/DC option or isolated DC/DC option or from where should I take input for the isolated power supply generating +5V for the Microcontroller?.

2. What solutions should I look into in order to design for the above requirements?

Best regards and thanks in advance.

  • 0
    TI__Expert 8210 points
    Archit

    For your first question, this depends on what the system requirements for the inverter are. For example if there any anti-islanding requirements that require the AC output to be disabled, but the microcontroller still needs to be powered, than the bias power needs to come from the PV.

    For the second question, we have devices that will meet your requirements for both PV and grid input. The specific device we would recommend is dependent on the power level of these devices that will be powered off this auxiliary power supply. Typically we've seen UCC28600, UCC28742 or UCC28710 meet customer requirements for both grid tie and PV input.

    We also have references like PMP5067 that are designed for typical auxiliary power supply for inverters.

    Best Regards,
    Eric