AHU Temperature Controller — PID + VFD Simulation

Reverse-acting PID · Derivative on PV · Anti-windup

Temperature (PV)
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Setpoint (SP)
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VFD Output
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Error
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Sim Time
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Temperature & VFD Output

PID Terms (P / I / D)

Setpoint

18 °C24.0 °C30 °C

PID Gains (positive values)

Disturbance

25 °C35 °C45 °C

Mode

Auto-Tuner (Relay Feedback)

PID Tuning Guide

  1. Set Ki = 0, Kd = 0.
  2. Increase Kp until temp oscillates steadily. Note this value as Ku and the oscillation period Tu.
  3. Apply Ziegler–Nichols:
    Kp = 0.6 × Ku
    Ki = 1.2 × Ku / Tu
    Kd = 0.075 × Ku × Tu
  4. Fine-tune: increase Ki to reduce steady-state error; increase Kd to reduce overshoot.