Practical PID using op amps

Discussion in 'Power Electronics' started by Ande, Aug 9, 2018.

  1. Ande

    Thread Starter Member

    Feb 3, 2017
    I am attempting to design a DC-AC inverter for my third year project. I have successfully simulated the inverter on PSIM with an inner loop current controller and an outer voltage control loop (see attached images). However, when I attempt to use op amps for the PID circuit, the simulation just doesn't run as desired. I get a constant dc 5V output. Kindly help in this regard.

    Input voltage = 400V output = 230 rms, 50Hz. Switching freq = 50khz.
    1st image: conceptual design
    2nd image output of conceptual design
    3rd image pid using op amps (does not run as desired).

    Integral time constant = R9C3
    Proportional gain = R9.R10/(R8.R11)
    All unspecified resistances are 10k.
  2. crutschow


    Mar 14, 2008
    You need to look at all the signals in the loop to determine at what point the voltages do not seem correct.

    Troubleshooting a malfunctioning design is one of the more important tasks of a design engineer. and this is a good opportunity to hone your skills. :D
    Last edited: Aug 9, 2018