WOODWARD 5437-524 Digital Servo Drive Module

Description

1. Core Overview & Positioning

2. Key Features & Functions

• Precision Closed-Loop Control:​ Forms the inner loop of a cascade control system, ensuring actuator position accurately tracks the setpoint from the speed/load governor.
• Dual Input Processing:
  • Command Input:​ Accepts a low-level analog position command signal (typically ±10V DC or 4-20mA) from the primary controller.
  • Feedback Input:​ Accepts AC signals from a Linear Variable Differential Transformer (LVDT)​ or Rotary Variable Differential Transformer (RVDT) attached to the actuator to measure actual position.
• High-Power Output Drive:​ Supplies the modulated current (typically in the range of ±80mA to ±300mA) required to drive the inductive coil of a servo valve or the amplifier for an electric actuator.
• Advanced Diagnostics & Protection:
  • Continuous monitoring of LVDT/RVDT signal health (detects opens, shorts, loss of excitation).
  • Monitors servo coil current and driver stage health.
  • Detects excessive position error and can trigger a fault shutdown to a safe state.
• Field-Configurable Tuning:​ Allows adjustment of critical servo loop parameters (Proportional, Integral, and Derivative gains, deadband compensation, current limits) via configuration software to optimize performance for the specific actuator dynamics.
• Status Communication:​ Reports operational status, faults, and diagnostic data to the primary controller via a communication link (e.g., Woodward’s Gov. Bus/NetBus).

3. Common Technical Specifications

• Part Number Context:​ The -524suffix indicates a specific variant within the 5437 family, defining its exact input/output ranges, connector types, and firmware features.
• Command Signal:​ Analog, typically ±10V DC or 4-20mA.
• Feedback Signal:​ AC LVDT/RVDT, commonly with a 2.5 – 5.0 Vrms, 2.5 – 10 kHz excitation signal.
• Output Drive:​ Current output suitable for standard industrial servo valve coils.
• Power Supply:​ Requires clean, regulated DC power, typically ±15V DC for control circuitry and +24V DC or similar for the power output stage.
• Communication Interface:​ Typically includes a proprietary Woodward serial interface (e.g., for connection to a 723PLUS controller) for configuration and diagnostics.
• Physical Form:​ A printed circuit board (PCB) module designed for installation within a Woodward control cabinet or a dedicated drive enclosure.

4. System Integration & Configuration

• Role in the Control Chain:​ It is the final control element driver​ in a hierarchical system:
  1. Primary Controller:​ Computes the required fuel/air setpoint based on speed, load, or process demands.
  2. Servo Driver (5437-524):​ Translates this setpoint into precise physical actuator movement.
  3. Actuator & LVDT:​ The mechanical assembly that moves the valve/rack and provides position feedback.
• Configuration Tool:​ Set up, calibrated, and tuned using Woodward Toolkit​ software. The configuration process involves:
  • Setting input/output signal types and scaling.
  • Performing LVDT calibration (span and zero adjustment).
  • Tuning the PID gains of the position loop for optimal response (fast without oscillation).
• Critical Calibration:​ A precise mechanical calibration (linking the LVDT stroke to the actual valve stroke) is essential for accurate control.

5. Typical Applications

• Gas Turbine Control:​ Driving fuel metering valves, gas control valves (GCVs), inlet guide vanes (IGVs), and compressor bleed valves.
• Steam Turbine Control:​ Positioning governor valves for speed/load control.
• Diesel & Heavy Fuel Oil Engine Control:​ Controlling fuel rack actuators or electronic unit pump/injector actuators.
• Compressor Control:​ Anti-surge valve actuation in centrifugal compressor systems.