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EMI noise issue on PWM input side from motor controller

Shiranga Ariyasinghe
Expert 1145 points
Other Parts Discussed in Thread: MOTORWARE

Hi,


I am making an igbt based motor controller to drive a PMSM. Power inverter was made with 1200V/200A rated IGBTs. I am using motorware firmware to control the motor and my inverter is based on TMDSHVMTRPFCKIT solution. 


In my assembly, igbt gate drivers were placed near to the power inverter and micro-controller and the other circuits were placed quite away from the drivers (1 to 1.5 feet). 12Vdc, 5Vdc and all pwm signals were connected to gate drivers using twisted wire pairs. 
When I turned on pwm signals without giving bus voltage (330Vdc) I could see clean pwm signals, 12V supply voltage and 5V supply voltage. But when I operated inverter with the bus voltage(330Vdc) I saw a huge EMI noise in the system. 
I suppressed noises on 12V and 5V supplies using ferrite beads. But ferrite beads did not work for pwm signals. I have attached the oscilloscope images of pwm with induced noise.


Is there any possibility to turn-on and turn-off igbts due to this induced noise notches? How can I filter these EMI noise from PWM signals ?



Thank you

  • 0
    Expert 2550 points
    Dear Lakshan,

    The problem that you are facing is related to designing poor in DC-Bus decoupling, the result is EMI from DC-Bus are impacting to your control signals or control stage.

    You can improve this as following:
    1) Using a FILM CAPACITOR (about 0.22uF) and placing it across the DC-Bus and connecting to the +DC terminal and -DC terminal of IGBT module as near as possible.
    2) Adding a Snubber circuit for each leg of Inverter. You should refer to how to design snubber network in somewhere.
    3) Adjusting the value of gate resistor in IGBT driver circuit in order to reduce the turn on speed and/or increase the turn-off speed of each IGBT in the converter.

    I hove this helps you a bit.

    Mr. Tran
  • 0 in reply to Tran Binh Duong
    Expert 1145 points

    Hi Binh,

    Thank you for your quick response.

    But I could not see any voltage ripple in my inverter .So I did not add snubber circuits or did not adjust gate resister. Images which I have attached were pwm signals from micro-controller to gate driver. They were induced. I have used isolated power supplies to gate drivers to isolate inverter side and control side.

    I have noticed that the voltage 5V supply to the C2000 micro-controller also induced with noises. Still  I couldn't fix this issue.  

     

  • 0 in reply to Shiranga Ariyasinghe
    Expert 2550 points
    Dear Lakshan,

    You should look at the ripple voltage on DC-bus or Vce of one of IGBT semiconductor device. If the ripple is large, you should add a FILM CAP as I suggested.

    By the way what the gate driver IC in your board is? Is it type of isolated IC or boost trap IC?

    If you can take a photo of your power module and your hardware setup, it maybe I can have some more ideas.

    Mr. Tran
  • 0 in reply to Tran Binh Duong
    Expert 1145 points

    Binh,

    I have checked Vce and Vbus with oscilloscope. I could not find any large voltage ripple on that. That is why I suspect this is an EMI issue.

    I have used an isolated gate driver IC with an isolated power supply.