Projects / Industrial automation and embedded control
Compact 24 V proportional hydraulic valve driver with 0-10 V and 4-20 mA inputs, closed-loop coil-current regulation, UART setup and load diagnostics.
The task was to make an industrial controller for a throttling hydraulic valve. In this application it is not enough to apply PWM directly to the coil: solenoid force is related to current, while current depends on winding resistance, temperature, inductance and supply voltage.
A practical proportional hydraulic valve driver was developed. The device accepts an analog setpoint, measures coil current, regulates it in a closed loop, saves settings to flash memory and diagnoses the main load faults.
Project materials
Engineering context
The control input had to be compatible with industrial 0-10 V and 4-20 mA signals.
The main regulated variable is coil current, not voltage across the coil.
The current range has to be adjustable for a specific valve.
The device had to work from a 24 V industrial supply and fit within limited dimensions.
Work done
Compact coil-control board schematic.
0-10 V and 4-20 mA inputs with signal-type selection.
Current measurement through a shunt and amplifier.
PWM power output for the solenoid.
STM32F103 firmware with a PI current regulator.
UART setup for current limits and PWM frequency.
Parameter storage in flash memory.
Open-coil and short-circuit load diagnostics.
Details
The driver measures real coil current and changes PWM so the actual current follows the setpoint. This is more stable than open-loop voltage control.
Through UART it is possible to set PWM frequency, lower and upper current limits, save parameters or restore factory defaults. This allows one board to be adapted to different valve instances and operating conditions.
The project shows applied embedded development for industrial hydraulics: standard input signal, power output, current feedback and load diagnostics in one compact node. This device was produced in a small series and works on industrial equipment.
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