Reverse Polarity Protection Methods

[asrikrishnagovi]

Hello, I am using an IGBT Module,  for a three-phase inverter operation, and the input to the module is a DC Supply from a battery/bench supply. I would like to know any protection features that can be implemented, to prevent any damage by accidentally swapping the DC Supply terminals. Emphasis on avoiding the method involving a Schottky diode in the main DC Line, due to the usage of an IGBT Module and other constraints such as track width of PCB due to high currents being involved. Any alternate methods would be helpful.  Thanks and Regards

[asrikrishnagovi]

Hello, I am using an IGBT Module,  for a three-phase inverter operation, and the input to the module is a DC Supply from a battery/bench supply. I would like to know any protection features that can be implemented, to prevent any damage by accidentally swapping the DC Supply terminals. Emphasis on avoiding the method involving a Schottky diode in the main DC Line, due to the usage of an IGBT Module and other constraints such as track width of PCB due to high currents being involved. Any alternate methods would be helpful.  Thanks and Regards

[Malleswararao]

Hi @asrikrishnagovi,

thanks for posting your query in the Infineon community.

here is the circuit below that works for you.

Operation: 

when DC connections are correct as per the below circuit, Diode will be reverse biased, and current will flow through the fuse to the inverter.

If DC connections are reversed, then Diode will get forward biased (bypass the Inverter section) and current flows through the fuse and it keeps on increasing until your fuse gets blown.

in this way, you will protect your inverter section.

thanks 

Malleswararao

[asrikrishnagovi]

Thank you for the quick response. Could you elaborate on the selection criteria for this Diode, such that all the short circuit current flows through it? Thanks and Regards

[Malleswararao · Accepted solution]

Hi @asrikrishnagovi,

The selection criteria will depend on, how fast your fuse will blow.

firstly, you need to identify what is your short circuit current sourcing capacity of your Input DC Source.

then how fast (means within what time) your selected fuse will get blown.

based on that arcing current you can choose the diode which is conducting throughout that arcing time of the fuse. 

selection of that diode is in such a way that, the diode surge current should be at least 2.5 times the arcing current of the fuse within that time.

thanks

malleswararao