Fluid Actuator Positioner Dual Power Supply Segmentation
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Solution Overview
Problem
The existing positioner for fluid actuators lacks adequate separation of electric circuits between the analog power supply and the emergency voltage system, leading to residual currents and potential malfunction due to material fatigue in the spring-biased emergency switch, which compromises fail-safe operation and energy efficiency.
Innovation Solution
A positioner design with two separate power supplies, where the current/pressure transducer is powered independently by a binary emergency voltage input, eliminating the need for a spring-biased switch and allowing higher power electronic components, and incorporating an operational amplifier to amplify control signals and a current limiter to ensure safe deactivation during failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the current/pressure transducer is powered via the analog power supply through the electronics assembly, then the transducer can be operated with available power, but residual currents flow in the electrical conductor even when the system is down, inducing stray currents in the emergency switch coil that may maintain the switch closed and prevent instant fail-safe operation
Solution Approach 1:
The patent divides the power supply system into two completely separate and independent power supplies: one for normal operation (analog power supply for electronics assembly) and one for emergency fail-safe operation (binary emergency voltage for current/pressure transducer). This segmentation eliminates residual current interference between the two systems, ensuring that when the emergency voltage is absent, no stray currents can induce the emergency switch to remain closed, guaranteeing instant fail-safe operation.
2Reliability
If a spring-biased emergency switch is used to open-circuit the electrical conductor when voltage is missing, then the actuator can be dumped to fail-safe position, but the mechanical spring component may malfunction due to material fatigue, risking the current/pressure transducer not being signalled OFF with mandatory high assurance
Solution Approach 1:
The patent replaces the mechanical spring-biased emergency switch with an electronically controlled emergency switch that is directly actuated by the binary emergency voltage. This eliminates the mechanical spring component that is subject to material fatigue, replacing it with an electronic switching mechanism that has no moving parts and therefore no fatigue-related degradation, ensuring long-term reliability for fail-safe operation.
3Ease of operation
If the emergency switch has a coil connected to binary emergency voltage to provide electromagnetic forces in closing the switch, then the switch can be closed when voltage is present, but the structure is risky because there is no total separation of electric circuits from the analog power supply and the dump system from the binary emergency voltage
Solution Approach 1:
The patent implements complete circuit segmentation by providing the current/pressure transducer with a dedicated binary emergency voltage power supply that is entirely separate from the analog power supply used by the electronics assembly. This eliminates any shared conductors or residual current paths between the normal operation circuit and the emergency dump circuit, achieving total electrical separation and eliminating the risk of residual currents interfering with emergency switch operation.
4Device complexity
If only the analog power supply is used to power both the electronics assembly and the current/pressure transducer, then the system structure is simplified, but only a restricted amount of energy of the analog power supply is available for consumption by the electronics components, limiting the performance of the positioner
Solution Approach 1:
The patent segments the power supply architecture into two independent channels: the analog power supply exclusively powers the electronics assembly, while the binary emergency voltage independently powers the current/pressure transducer. This segmentation resolves the power conflict by providing dedicated power resources to each subsystem, enabling the electronics components to consume sufficient energy for high-performance operation without being constrained by the limited capacity of a shared analog power supply.
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
This configuration enhances fail-safe reliability, reduces mechanical components, and allows for higher performance by ensuring the actuator is safely dumped to a fail-safe position even in the presence of residual currents, with improved energy utilization and reduced risk of malfunction.
Implementation Method 1
incorporating an operational amplifier to amplify control signals
Implementation Method 2
incorporating an operational amplifier to amplify control signals and a current limiter to ensure safe deactivation during failures
Data Source
AI summary
A positioner for a fluid actuator comprising an electronics assembly designed for setpoint/actual value comparison and for outputting a feedback control signal includes a current/pressure transducer receiving the feedback control signal for controlling the actuator, an analog power supply, particularly in a range 4 to 20 mA, for powering the electronics assembly, and an additional voltage input, particularly in a range of up to 24 V, wherein said voltage input is configured as a further power supply for powering the current/pressure transducer separate from the analog power supply.