Woodward VariStroke-I Electronic Driver Module (PCB)

Electronic Driver Module (PCB)

The printed circuit board (PCB) is mounted on top of the housing. The PCB

performs the following tasks:

 Power Supply

 Isolated Input and Outputs

 Dual Redundant Demand inputs

 Dual Redundant inputs for Final Cylinder Feedback

  Microprocessor based control

 Actuator H-Bridge Drive

 Current Limiting for Thermal Protection

 Advanced Diagnostics

 Discrete Outputs for Fault, Alarm and Shutdown Enunciation

The shield connections for the Analog Output (terminal #20), CAN1 (terminal

#23) and CAN2 (terminal #29) are through capacitors only as indicated in the

wiring section of this manual.

The power supply section performs the EMI filtering on the (18 to 32) V (dc) input

voltage and generates controlled voltages for several electronics sub-systems.

The power supply system is monitored for proper operation. If input voltage or

internal power systems are detected outside of allowable operating ranges, a

diagnostic alarm will be enunciated.

Calibration and configuration of alarms and shut down and redundancy operation

are configurable via the PC Service Tool.

The primary demand and redundant demand / feedback input signals are

designed for a (4 to 20) mA control signal. Each input signal is EMC protected.

Discrete outputs are provided for alarm and shut down enunciation. An internal

LED also is illuminated when a fault condition is detected. Cover needs to be

removed to see this LED. The configurable discrete output can be customized to

output a variety of enunciations using the PC Service Tool. All of the discrete

outputs are configurable for normally-open or normally-closed action using the

PC Service Tool.

Cylinder Position Control

The cylinder position controller adjusts the hydraulic power cylinder position to

match the feedback signal to the demand.

Both the servo position controller and cylinder position controller are monitored to

ensure accurate tracking.

The position controller regulates a pulse width modulated (PWM) drive signal to

the actuator. The drive current to the actuator is regulated, transiently allowing up

to 10 Amps to be provided to move the actuator at its maximum speed and

torque. A steady state current limit becomes active after a period of a few

seconds to protect the actuator and electronics.