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Thread: multivariable pid

  1. #1

    multivariable pid

    I'm using a teensy3 as a glorified power supply monitor/controller/logger. One of my outputs is a 0-450V linear supply, limited to 20mA or 8W, and I'd like software control of the limits. I'm using PWM -> opto -> rc as an analog output to drive the gate of the pass FET, output voltage is read off a divider and current from a high side current monitor.

    Ignoring the dissipation issue (or rolling foldback into software, adding another variable still) do I do PID for voltage (x), OR whatever duty cycle results in the programmed current limit (y) OR whatever duty cycle results in the max allowed power output/pass transistor dissipation?

    (It doesn't have to go all the way to 0V, but thats more of a question of dissipation, and how close to ideal can I get, and is outside the scope of the control loop question).

  2. #2
    Is this a multi input single output system, and is that three nested loops, orthree parallel loops, selecting the most restrictive output? Describing the problem sounds like the latter case, but it also seems like you could mess up a control loop yanking its value around to some arbitrary value decided by a different loop.

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