What had to be solved
The task was to make a specialized power interface between an automation system and a proportional hydraulic valve, where the controlled variable is coil current rather than a simple applied voltage.
Projects / Industrial automation and embedded control
Proportional hydraulic valve current controller
Compact industrial current controller for proportional hydraulic valves: 12...30 V DC supply, 0...3 A coil-current regulation, 0...10 V / 4...20 mA / PWM / UART setpoints, ramp modes, dither and diagnostics.
What the project reached
The module solves a practical industrial-control task: it regulates valve-coil current repeatably, protects the output and provides clear setup for a specific valve or distributor.
Project materials
Photos and working materials
Documentation
Device manual
Public materials
Engineering context
Important constraints
The target devices are proportional valves and distributors without spool-position feedback.
The solenoid force is related to current, while current depends on coil resistance, inductance, temperature and supply voltage.
Smooth transitions are needed to reduce hydraulic jerks and sharp transients.
The device has to be configurable for 0...10 V, 4...20 mA, PWM and UART control inputs.
Work done
What was included
Current-controller circuitry for a proportional valve coil.
Firmware with PI current regulation, ramp functions and dither.
Support for 0...10 V, 4...20 mA, PWM and UART setpoint inputs.
Local setup with an OLED display and buttons.
Parameter storage and fault diagnostics.
Manual and interface-accessible settings for current limits, ramp timing, dither and regulator mode.
Details
Engineering project description
Operating principle
The controller measures current through the solenoid coil and closes an internal regulation loop around this measured current. The user sets output-current limits and input-signal scaling, so an allowed input signal can be mapped to the required output current.
Separate rise and fall times allow the setpoint to change with a configured speed instead of a hard step. In hydraulics this helps reduce jerks and overshoot.
Main capabilities
- closed-loop coil-current regulation in the 0...3.0 A range
- 12...30 V DC supply for 24 V systems
- 0...10 V, 4...20 mA, PWM and UART setpoint inputs
- independent minimum and maximum input-signal settings
- independent minimum and maximum output-current settings
- separate current rise-time and fall-time settings
- FAST, NORM and SLOW PI-regulator modes
- dither frequency and amplitude settings
- local setup with OLED display and two buttons
- parameter storage in non-volatile memory
Technical parameters
- nominal system: 24 V
- absolute supply maximum: 35 V
- output topology: low-side N-MOSFET switch
- maximum continuous current: 3 A at +25 C
- current-regulation accuracy: +/-1% of range
- power PWM frequency options: 2 / 4 / 8 / 16 kHz, with 16 kHz as default
- rise and fall time: 0...10000 ms
- dither frequency: 10...300 Hz
- dither amplitude: 0...0.4 A pk-pk
- UART service interface: 115200, 8N1
- DIN-rail mounting
Diagnostics and protection
- overvoltage and undervoltage supply monitoring
- input-voltage and current-setpoint limit checks
- short-circuit protection with output shutdown
- open-coil indication
Contact
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