Electric Actuator Fail-Safe Control With Parallel Motor Modules
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Solution Overview
Problem
Existing fail-safe systems for electric actuators, particularly in subsea applications, face challenges such as complexity in software-based systems and space constraints with spring-based systems, which hinder efficient and reliable operation.
Innovation Solution
A control system for electric actuators that incorporates a second motor control module powered by an energy storage device, which takes over in fail-safe mode, independent of software updates, using a hardware motor control circuit to ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a software-based fail-safe system is used, then fail-safe functionality can be implemented, but the system becomes complicated and cumbersome to update and maintain
Solution Approach 1:
The control system is divided into two independent modules: a first motor control module for normal operation and a second motor control module for fail-safe mode. This segmentation allows each module to be optimized independently, with the second module dedicated solely to fail-safe functionality, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The patent replaces software-based fail-safe control with a hardware-based second motor control module. This hardware module operates independently of the software-controlled first module, eliminating the complexity of updating and maintaining software-based fail-safe systems while ensuring reliable fail-safe functionality.
2Reliability
If a spring-based fail-safe system is used, then fail-safe functionality is provided, but the system becomes space consuming and complicated to implement with rotating multi-turn actuators
Solution Approach 1:
The patent substitutes the mechanical spring-based fail-safe system with an electrical/hardware-based second motor control module. This replacement eliminates the need for large mechanical springs and associated mechanisms, significantly reducing space consumption while providing reliable fail-safe functionality for rotating multi-turn actuators.
Solution Approach 2:
The patent changes the fundamental parameter of fail-safe implementation from mechanical energy storage (springs) to electrical energy storage and control (battery-powered hardware module). This parameter change enables a compact design that does not require large mechanical components, thus reducing space consumption.
3Reliability
If a hardware motor control circuit is used for fail-safe mode, then independence from software updates is achieved, but the device complexity increases due to dual control modules
Solution Approach 1:
The control system is segmented into two distinct modules with clearly defined roles: the first motor control module handles normal operation under software control, while the second motor control module handles fail-safe operations independently. This segmentation, while creating two modules, actually reduces overall system complexity by eliminating the need for complex software-fail-safe integration and update procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a robust, independent fail-safe functionality that avoids the complexities of software updates and space constraints, ensuring reliable operation in subsea environments.
Implementation Method 1
a chargeable energy storage device... A second motor control module powered by the energy storage device
Data Source
Figure 1~2
Figure 3
AI summary
A control system (1) is disclosed for an electric actuator comprising an electric motor (4),an external supply (7) of electric energy, an energy storage device (2) and a first motor control module (12) which controls the supply of energy to the motor in normal operation. A second motor control module (15) controls the supply of energy to the motor in fail-safe mode. The first motor control module (12) and the second motor control module (15) are connected in parallel via a fail-safe switch (13) which is arranged to override the control executed by the first motor control module (12) to set the control system in fail-safe mode by activation of the second motor control module (15) in either case of: i) the energy level in the energy storage device (2) reaching, or falling below, a predetermined value, or ii) failure in the external energy supply (7), or iii) in response to an operator command (14). A method of controlling an electric actuator in a control system (1) is also disclosed.