Contactor Control for Short-Circuit Contact Welding Prevention
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Solution Overview
Problem
Contactors face challenges in maintaining a long service life due to the difference between mechanical and electrical life, particularly under short-circuit conditions where electric repulsion forces can cause contact welding and failure.
Innovation Solution
The contactor design includes an electromagnetic component, a movable component with a connected movable contact and a driving part, a sensor to detect displacement based on electric repulsion force, and a controller to adjust the magnetic field generated by the electromagnetic component, reducing the electromagnetic driving force opposite to the electric repulsion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromagnetic driving force is increased to ensure reliable contact closing, then the contactor can maintain stable operation under normal conditions, but the contacts are more likely to weld together under short-circuit conditions due to the strong attraction force pulling the movable contact back onto the static contact
Solution Approach 1:
The patent applies the dynamics principle by making the electromagnetic driving force adjustable rather than fixed. The controller dynamically modifies the driving force magnitude based on real-time feedback from the sensor about contact separation status. During normal operation, sufficient driving force ensures reliable contact closing. During short-circuit conditions, when the sensor detects contact separation, the controller reduces the driving force to prevent the movable contact from being pulled back onto the welded static contact, thereby resolving the contradiction between reliable closing and welding prevention.
Solution Approach 2:
The patent implements parameter changes by varying the electromagnetic driving force parameter according to operating conditions. The controller changes the magnitude of the driving force based on feedback signals: maintaining a higher value for reliable contact closure under normal conditions, and reducing it when short-circuit conditions are detected to prevent contact welding. This dynamic parameter adjustment resolves the technical contradiction by adapting the driving force to different operational states.
2Object-affected harmful factors
If a sensor and control system are added to detect and respond to contact separation, then contact welding can be prevented under short-circuit conditions, but the device complexity increases due to the additional components and control logic
Solution Approach 1:
The patent applies the feedback principle by introducing a sensor that detects the separation distance between contacts and feeds this information back to the controller. The controller uses this feedback to determine whether to maintain or reduce the electromagnetic driving force. This feedback mechanism enables automatic prevention of contact welding during short-circuit conditions while keeping the control logic relatively simple: if separation is detected, reduce driving force; if contacts are closed, maintain normal operation.
3Object-affected harmful factors
If the electromagnetic driving force is reduced to prevent contact welding, then contactor reliability under short-circuit conditions improves, but the contactor may fail to reliably close contacts under normal operating conditions
Solution Approach 1:
The patent resolves this contradiction through dynamic adjustment of the electromagnetic driving force. Rather than using a fixed reduced driving force that would compromise normal operation, the system dynamically sets the driving force magnitude based on real-time feedback. During normal operation, the driving force is maintained at a level sufficient for reliable contact closing. When short-circuit conditions occur and contact separation is detected, the driving force is then reduced to prevent welding, thus achieving both objectives at different times.
Solution Approach 2:
The patent implements parameter changes by adjusting the electromagnetic driving force parameter based on operational conditions. The controller changes the driving force magnitude: maintaining a higher value during normal operation to ensure reliable contact closing, and reducing it when short-circuit conditions are detected through sensor feedback. This conditional parameter adjustment resolves the contradiction by adapting the driving force to the specific operational state.
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 solution effectively prevents contact welding during short-circuit conditions by ensuring the movable contact does not fall back onto the static contact, thereby extending the contactor's service life and improving equipment reliability.
Implementation Method 1
the driving part is configured to produce an electromagnetic driving force through the magnetic field generated by the electromagnetic component
Implementation Method 2
the first elastic part is configured to generate an elastic force supporting the movable component
Implementation Method 3
the sensor is configured to detect the displacement of the driving part based on the electric repulsion force generated by the current flowing through the movable contact and the static contact
Data Source
AI summary
A contactor and a control method thereof are disclosed, the contactor including: an electromagnetic component; a static contact; a movable component including a connected movable contact, a first elastic part configured to generate an elastic force supporting the movable component and a driving part configured to produce an electromagnetic driving force through a magnetic field generated by the electromagnetic component; a sensor; and a controller configured to: in response to the sensor detecting that the driving part is displaced based on the electric repulsion force generated by the current flowing through the movable contact and the static contact, control the electromagnetic component to adjust the generated magnetic field to reduce the electromagnetic driving force produced by the driving part based on the generated magnetic field in the opposite direction to the electric repulsion force, so that the movable contact is not closed with the static contact again.