Motor control Design using thyristor

Discussion in 'The Projects Forum' started by grandure, Apr 18, 2011.

  1. grandure

    Thread Starter New Member

    Sep 28, 2010
    2
    0
    The following text is the prompt of the project
    "
    A thyristor is used to turn on and off a 50-A DC motor every 60 seconds. We wish to design a circuit to control the motor using a GE. C150 slow switching device.

    The manufacturer suggests that if the current in the thyristor rises too quickly, that is a high di/dt, the device can be destroyed. Therefore, some inductance must be placed with this device, so that di/dt is below the maximum limit. Also, this device may turn on (without any gate pulses), if the forward voltage is too high. That is known as dv/dt turn-on and it may lead to an improper operation of the circuit and the DC motor. A simple RC snubber may limit the dv/dt of the applied forward voltage.

    Your design should also include the thyristor protection units, a switching device/mechanism using an auxiliary electronic switches (such SCR’s, power MOSFET’s, BJT’s, etc), and a commutation circuit.

    Reporting Requirements: All components used in this project must have values with their spec. sheets attached (if any). Your references must be listed in a separate sheet. (i.e. Reference Sheet). Your plots/graphs are completely labeled and all calculations are clearly explained with the proper units. Note: Group works are encouraged but your individual works and their originalities are observed.

    Specification of GE. C150 (E, N, and P) Series:

    Repetitive Peak Forward and Reverse Voltages 500 V (C150E)
    800 V (C150N)
    1000 V (C150P)
    Reverse and Forward Leakage Current 10 - 20 mA
    Holding Current 20 mA
    RMS Current 100 A
    Forward Voltage Drop 1.2 - 2.0 V
    Peak One-Cycle Surge (60 Hz) 1500 A
    I2t for Fusing 7000 amp2.sec
    dv/dt 200 – 500 V/µsec
    di/dt 500 A/µsec
    Gate Trigger Voltage 1.5 – 3 V
    Gate Trigger Current 50 – 200 mA
    Turn On-Time 3 µsec
    Turn Off-Time 100 µsec
    "
    Unfortunately, i feel the information that i have is missing based on my knowledge but the professor ensure me that i have all the data.

    How can I figure out the information of the load (Motor) like (Ra, La and Ea) so i can get the firing angel ??
     
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