Jienlu VFD Dedicated for Constant Pressure Water Supply
What control methods
are typically used by variable frequency drives (VFDs) in constant pressure
water supply applications?
Here is the
professional English translation of the control methods for variable frequency
drives (VFDs) in constant pressure water supply systems, structured according
to your original format:
Ⅰ. PID Closed-Loop Control (PrimarySolution)
- Control
Logic
Continuously compares pressure sensor feedback (e.g., signals from remote pressure gauges or transmitters) with user-defined setpoints. Adjusts pump speed via Proportional (P), Integral (I), and Derivative (D) algorithms:
o
Low pressure → PID increases output frequency → Pump
accelerates → Pressure rises
o
High pressure → PID decreases output frequency → Pump
decelerates → Pressure falls
- Wiring
& Parameter Configuration
o
Sensor connection:
§
Remote
pressure gauge (3-wire): Red → +10V, Yellow → AVI analog input, Green → GND
o
Pressure
transmitter (2-wire): +24V → A1, - → GND
o
Key parameters:
§
Target
pressure (e.g., 0.4 MPa)
§
PID
proportional/integral gains (e.g., parameter codes P117/P118)
§
Pressure
gauge range calibration (e.g., set P119=16 for a 1.6 MPa gauge)
🔄 Ⅱ. Sleep-Wake Strategy
Energy-saving logic:
- Sleep
condition: Stop pump when pressure stabilizes and frequency ≤ threshold (e.g., ≤20 Hz for 5 seconds)
- Wake
condition: Automatically restart pump if pressure drops below threshold
(e.g., pressure equivalent to 25 Hz)
⚡️ Ⅲ. Auxiliary Control Extensions
- Multi-Pump
Coordination
o
Master
VFD + fixed-frequency backup pumps: Activate auxiliary pumps during peak
demand, coordinated by controller
- Pressure
Switch Control (Simplified solution)
o
Switch-based
control: Low-pressure contact starts VFD; high-pressure contact stops it (for
low-precision scenarios)
🛠️ Ⅳ. Commissioning Notes
|
Key Item |
Operation
Guidelines |
|
Pressure
gauge selection |
Calibrate range parameter (e.g., set to 16 for 1.6
MPa gauge to avoid reading distortion) |
|
Anti-interference |
Shield long signal cables; install reactors to
suppress VFD harmonics if necessary |
|
Macro
function |
Enable "Constant Pressure Macro" in modern
VFDs (e.g., F00.01=1) to auto-configure PID parameters |
Industry trend: External PID controllers are being replaced by built-in VFD PID, simplifying wiring and improving response speed