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Posted on : Monday 10th August 2020 05:10 PM

IGBT OVERCURRENT AND SHORT-CIRCUIT PROTECTION IN INDUSTRIAL DRIVES


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Posted by  Murali Palani
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IGBT OVERCURRENT AND SHORT-CIRCUIT PROTECTION IN INDUSTRIAL DRIVES

 

Short-circuits at Manufacturing Atmospheres

Industrial motor drives function at the comparatively harsh situation in which high temperature, ac line transients, mechanical overload, and other incidents can occur. Some of these events result in substantial overcurrent levels flowing in the motor drive power circuits. 

These described below:

  • Inverter shoot-through. 
    • It causes the false turn-on of both IGBTs in one of the inverter legs, which in turn result from electromagnetic interference malfunction in the switch. It could also cause the failure of the IGBT.
  • Phase to phase short-circuit.
    • It causes insulation breakdown at motor windings due to degradation, over-temperature and overvoltage.
  • Short-circuit to earth.
    • It causes insulation breakdown between a motor winding and covering; due to degradation, over-temperature and overvoltage.

 

Generally, motors capable of absorbing high current for extended periods; however, the IGBTs majority of industrial motor drive inverter stages have short-circuited tolerate times in microseconds.

 

IGBT Short-Circuit Ability

 

The short-circuit endure a time of an IGBT is related to its transconductance, and thermal the capacity of the IGBT die. More significant gain leads to greater

short-circuit current levels within the IGBT, so lower-gain IGBTs will

have lower short-circuit levels.

  • Advances in IGBT technology resulting in the trend of increased short-circuit current levels and subsequently reduced short-circuit withstand times. 
  • Reducing the size and lowering thermal capacity, which furthers the resist time. There is also a robust dependency on the collector-emitter voltage. Hence, the parallel trend toward higher dc bus voltage levels in industrial drives results in a further reduction in short-circuit resist times. 
  • Moreover, the short-circuit withstand time widely from to device, so it usually recommended building an additional margin beyond the specified short-circuit face time, in IGBT protection circuits.

 

 

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igbt overcurrent short circuit protection industrial drives

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