Need to design a PCB driver with a FPGA to manage the control signals

Hello folks!

I need to design a PCB driver with a FPGA to manage the control signals of several high power IGBT. These IGBTs are going to drive a lot of current (around 7000 Amp) and I need to do a robust PCB design.

I have been doing some EMC PCB designs for low power applications (maximum 3 Amp) and they are working very well. However I have never done a EMC PCB design for very high power application and I have been searching some guidelines:

https://www.st.com/st-web-ui/static...ical/document/application_note/DM00182773.pdf
https://www.onsemi.com/pub_link/Collateral/AND9071-D.PDF

Therefore I would like to know your opinion about the previous links and if there is anything else that should I have into account to do the PCB design of this IGBT driver…

Ahh and finally we are planning to use a Spartan 3A from Xilinx to handle the IGBT control lines. Xilinx is a good manufacturer for this applications or do you think that for this special application there are other manufacturers which can me provide me special EMC/EMI FPGAs?

Thanks for the help!

7KA is a RIDICULOUSLY HIGH current!!!! Are you trying to build a time machine???!!

What voltage generates it?
Even with low inductance such current can cause huge magnetic fields - if it doesn't melt the PCB first.

Hehehehe,

Alsmost…it is a huge Power converter for solar/wind power generators. I have to develop a IGBT PCB driver to generate the control signals of the big IGBTs. I am not sure about the exact value of Amp, but I can tell you that the power which is able to provide is 1.5 MWatt!!!!!

I'm no time machine expert but I think it's a good idea to gear up the voltage and decrease the current to more earthly numbers.

Even with low inductance such current can cause huge magnetic fields - if it doesn't melt the PCB first.

Click to expand...

Consider that the IGBT power circuit is not implemented on the PCB.

High power IGBTs are relative slow switching, in so far EMC issues are manageable. The essential requirement is to have clear separation of power and control circuits with safe isolation of gate driver and measurement signals. In high power applications, it's usually achieved by industrial gate driver and measurement modules. Power supply and all external interfaces of your control board should have state-of-the-art protection against surge and fast transients.

I made a mistake the IGBT are out of the board and they are handling 7.5Kv and 150A - 300 A

fvM is right, The IGBTs are places in other board, the PCB driver board that i have to design only generates the control signals for switching the IGBTs. So I would like to know where can I leanr the state of the art to isolate the control signals of the IGBT to avoid EMI problems. Can I follow the rules of the links that I attached or I have to take into account another rules?

Regarding to the ground. When I have been working with low power designs (5v / 3A) I have been using one GND power plane for the Analog/Digital components. The only thing that i took into account was to separate very well analog from dogital devices. I.e. I place all the analog devices on the left side of the aborad and digital in the right side.

However in this kind of design is recommendable to have to different GND planes? AGND and DGND?

Thanks!

If you don't have extra small analog signals or need to achieve a very high dynamic range (both would be unusual for a power electronic application), I would try a single common GND plane for analog and digital interfaces.

flote21 said:

So I would like to know where can I leanr the state of the art to isolate the control signals of the IGBT to avoid EMI problems

Click to expand...

I guess that you're probably using a bank of IGBTs encapsulated with the standard power module pack that allows connection with cabling terminals by screws. If that's the case, I strongly recommend consider the assembly based on parallel plates instead of wires, as shown bellow:

https://www.edaboard.com/blog/1919/

@FvM

I am also thinking to use one single GND plane for Analog + Power + Digital Devices. When I say Power devices I mean the Power devices to supply FPGAS and O-Amp of the driver board. However reading some design reference documents for high power Motor controlling with IGBTs from manufacturers like ON Semiconductor or ST (See links above). All of them recommend to separate the GND planes into three different planes: Analog GND, Digital GND and Power GND. I agree with you FvM. I would like to use just ONE GND plane and place the different group of devices separately on the PCB: Power devices in bottom, Analog Devices on the left side and Digital devices on the right side. However I don’t know if using GND planes can be more susceptible to EMI.

@andre_teprom

That idea is already used in the IGBTs board. The system is described like you say. We have two different PCBs: One PCB board is the board where is placed all the IGBTs with the power supply for them and the other PCB board that I have to design is going to be driver for the gates of the IGBTs. The IGBT board is built in the same way like you say, however we need cables/connectors to connect it with the PCB driver that I have to design. There my question is basically which PCB rules should I take into account for the high poser design to have a good EMI protection in the driver PCB board. I did high speed EMI/EMC designs for small signal and low power systems and they were working perfectly. However I never did a high speed EMI/EMC design for high power systems and I don’t know if I need to follow additional PCB rules for designing. On the other hand. The amplitude of the signals that I have to handle in the driver PCB board are maximum 5V with maximum currents of 300 mA (The gate of the IGBTs does not need too much voltage an current to switch). However I need a good isolation in the driver PCB board to avoid the high currents and voltages running in the IGBT board affect to my driver. Maybe there are special EMI/EMC cables or connectors to use in the driver board. Or maybe I need to some optocoupler to isolate both boards. (See the picture attached to have an idea about the system)


Thanks!

Search
Henry Ott...
Ralph Morrison...
Keith Armstrong.... EMC club