WOODWARD 5464-658 Digital Servo Drive Module

Description

1. Core Overview & Positioning

2. Key Features & Functions

• Precision Closed-Loop Control:​ Implements a high-speed digital control algorithm (typically PID with advanced filters) to maintain actuator position precisely aligned with the commanded setpoint.
• Dual-Channel Input Processing:
  • Command Input:​ Accepts an analog position command (e.g., ±10V DC, 4-20mA) from the master controller.
  • Feedback Input:​ Continuously reads the position signal from an LVDT (Linear Variable Differential Transformer)​ or RVDT​ attached to the actuator, forming the feedback for the control loop.
• High-Power Output Stage:​ Generates a modulated current output (typically in the range of ±150mA to ±300mA) capable of driving the inductive coil of a high-performance servo valve.
• Advanced Integrated Diagnostics:
  • Continuous monitoring of LVDT health (signal level, frequency, phase).
  • Real-time monitoring of coil current, driver temperature, and output stage health.
  • Detection of excessive position error, command-feedback mismatch, and communication faults.
• Configurable Control & Protection:​ All operational parameters—including servo loop gains (P, I, D, feedforward), current limits, fault response strategies (e.g., drive to pre-set fail-safe position), and I/O scaling—are configured via software (Woodward Toolkit).
• Integrated Communication:​ Features onboard communication interfaces (typically a Woodward proprietary bus like Gov. Bus​ or a serial link) for seamless integration with the primary controller, real-time data monitoring, and remote configuration.

3. Common Technical Specifications

• Part Number Context:​ The -658suffix specifies the exact hardware revision, firmware version, and possibly default calibration for a particular application (e.g., specific actuator model or turbine type).
• Command Signal:​ Configurable for standard analog inputs: ±10V DC or 4-20mA.
• Feedback Signal:​ Designed for industry-standard AC LVDT/RVDTs, providing excitation (e.g., 3 Vrms @ 2.5 kHz) and measuring the return signal.
• Output Drive:​ Current output suitable for driving proportional or servo-proportional valve coils.
• Power Supply:​ Requires external, well-regulated DC power rails, commonly ±15V DC for control logic and a higher voltage (e.g., +24V to +80V DC) for the power output stage.
• Physical Form:​ A robust printed circuit board assembly designed for mounting in a control cabinet or dedicated drive chassis, featuring high-reliability connectors.

4. System Integration & Configuration

• Role in Control Hierarchy:​ Acts as a slave drive unit​ to a primary Woodward Digital Controller. It executes position commands with high fidelity but relies on the master for the overall control strategy (speed, load, sequencing).
• Configuration Software:​ Entirely configured and tuned using Woodward Toolkit​ PC software. The process involves:
  1. Hardware Configuration:​ Setting I/O types and scaling.
  2. LVDT Calibration:​ A precise procedure to map the LVDT’s electrical output to the actuator’s physical stroke (min/max travel).
  3. Servo Tuning:​ Adjusting the PID and dynamic compensation parameters to achieve optimal step response—fast without overshoot or oscillation—specific to the connected actuator’s mechanical and hydraulic characteristics.
• Calibration Criticality:​ Accurate mechanical installation and electrical calibration of the LVDT are absolute prerequisites for safe and stable operation.

5. Typical Applications

• Heavy-Duty & Aeroderivative Gas Turbines:​ Controlling fuel gas control valves (GCVs), liquid fuel metering valves, and inlet guide vanes (IGVs).
• Steam Turbine Governing:​ Positioning main stop valves, governor valves, and extraction valves.
• Large Diesel & Dual-Fuel Engines:​ Governing actuator control for fuel injection systems.
• Compressor Anti-Surge Systems:​ Providing fast, precise control of anti-surge valves.