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Servo drive for thruster control on underwater vehicles

Ingenia Motion Control (Spain) introduced the CANopen i127 brushless AC motor servo drive for operation at up to 1600 m deepness. It was developed for control of propulsion systems on manned submarines, AUVs (autonomous underwater vehicles), ROVs (remotely operated vehicles) or other underwater vehicles.

THE DEVICE IMPLEMENTS THE CANopen profiles CiA 301 and CiA 402 (CANopen device profile for drives and motion control) for drive operation and monitoring. The CiA 402 is also internationally standardized in IEC 61800-7-201 and IEC 61800-7-301, both of which are available from the IEC. The drive includes control schemes for velocity and current/torque loops and provides the field-oriented control sensor-less algorithm with back-emf estimator based on an observer. External analog operation for safety control is available. Motion controller capabilities are provided for task monitoring and data logging. The drive uses sensor-less flux-vector control algorithms that allow for motor control without external feedback device. It has been designed for AC brushless motor thrusters and may operate at hydrostatic pressures of up to 160 bar (equivalent to 1600 meter deep immersion) without the need of pressure relief vessels. Maximum storage pressure is 250 bar. The device uses power Mosfet semiconductors to drive the 2,5-kW propellers from the 170-V battery bus.

Historically, electronic systems for deep water applications have been installed inside low pressure vessels. Working with pressure-tolerant electronics reduces the weight and volume of containers as well as the number of connections through pressure barriers. The power and electronic systems are not placed in the submarine cabin. Less complex and reliable cooling systems are required. Use of such electronics also reduces system cost and complexity and increases the reliability.

When working with pressure-tolerant electronics, several design issues should be taken into consideration to achieve reliable drivers for the thrusters control. Full isolation between power and logic connections should be given. Dynamic braking should be done through on-board high power shunt braking resistor. For operation, full disconnection from batteries should be achieved. Furthermore, on-board self monitoring systems for voltage, current and temperature supervision are required. Protection systems should not provide non-resettable devices i.e. all protections should be electronic. Presented drive incorporates the power electronics and control building blocks required to control AC brushless motor thrusters for subsea applications.

The company specializes in the design, development and manufacturing of motion control products and custom motion systems for medical, robotics, semiconductor, automotive, laser processing, military, aerospace, electronic manufacturing and test, research and development, and other industries.

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