PWM Signals for Proportional Valves

✅ General Requirements for the PWM Signal for HAWE PSV Valves:

1. Signal Form:

• Square wave signal with defined pulse width (PWM – Pulse-width modulation)
• DC power source required, no AC voltage

2. Voltage (independent of duty cycle):

• Nominal: 12 V DC or 24 V DC, depending on valve type
• Power supply must be stable and filtered

3. Frequency Range:

• Typical: 100 – 300 Hz
  (depending on valve series also 80 – 400 Hz possible – refer to data sheet!)
• Too high a frequency (>500 Hz) may prevent the valve from following mechanically
• Too low a frequency (<80 Hz) can cause chattering or audible noise

4. Duty Cycle:

• Typical: 10 – 90 % (controllable range)
• Zero position: often at 0 % or 10 % (depending on valve and application)
• The effective valve opening is controlled via the duty cycle

5. Current Control Instead of Voltage Control (Recommended!):

• HAWE recommends a current-controlled PWM output stage since the magnetic force is proportional to current, not voltage
• This ensures better repeatability and temperature independence

⚠️ Special Requirements / Notes:

• Ramp function (soft start/soft stop) is recommended to avoid pressure spikes and hammering
• Freewheeling diode required at PWM output if no integrated flyback diode is present
• Watch for temperature drift in the coils (current control helps compensate)
• Ensure EMC protection (shielded cables, proper grounding)

📘 Example (typical for PSV valves):

• Supply voltage: 24 V DC
• PWM frequency: 100 Hz
• Current control: 0 – 1.6 A
• Control range: Duty cycle approx. 10–90 %
• Input signal: 0–10 V or 4–20 mA (converted to PWM in the controller)

We are happy to provide additional information on how to implement the signal in your controller, e.g., in CODESYS.

With the compact HAWE CAN IO mobile controller, parameters can easily be configured via the graphical user interface.