MEMS Soft Switching for Arc-Less Power Control
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Solution Overview
Problem
Electromechanical contactors in power systems face challenges with fault currents exceeding their interrupting capacity, and existing solutions like vacuum contactors are difficult to inspect and cause transient overvoltages, while mechanical switches operate slowly and are prone to error in zero crossing prediction.
Innovation Solution
A micro-electromechanical system (MEMS) based soft switching system that uses detection and control circuitry to facilitate arc-less switching by closing and opening MEMS switches at zero voltage and current crossings, respectively, thereby avoiding pre-strike arcing and ensuring the switches operate within their design capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electromechanical contactors are used to handle switching currents, then the contactor can switch large currents, but fault currents exceeding the interrupting capacity will damage the contactor
Solution Approach 1:
The system segments the switching function into two parts: a fast-acting protective device (MEMS switch) that handles fault currents, and a slower electromechanical contactor that handles normal switching operations. This segmentation allows each component to be optimized for its specific function, with the MEMS switch providing rapid protection against overcurrent conditions.
Solution Approach 2:
The MEMS switch acts as an intermediary protective device positioned in series with the electromechanical contactor. It intercepts and interrupts fault currents before they can damage the contactor, serving as a mediator that protects the main switching device from harmful conditions.
2Power
If vacuum contactors are used to handle large motors and transformers, then the switching capability is improved, but the contactor tips are encapsulated making visual inspection difficult
Solution Approach 1:
The patent replaces traditional mechanical vacuum contactors with MEMS-based switching technology. The MEMS switches use electrostatic actuation instead of mechanical vacuum sealing, eliminating the need for encapsulated contact tips while maintaining high switching capability for large motors and transformers.
3Power
If vacuum contactors are used for switching, then the handling of large motors and transformers is improved, but damaging transient overvoltages are generated particularly when the load is switched off
Solution Approach 1:
The patent replaces mechanical vacuum contactors with MEMS switches that use electrostatic actuation. This substitution eliminates the mechanical contact bounce and arc quenching issues that generate transient overvoltages, providing clean switching without damaging voltage spikes.
Solution Approach 2:
The patent changes the switching mechanism from mechanical to electrostatic, fundamentally altering the switching parameters. The electrostatic actuation provides controlled, arc-free switching that eliminates the transient overvoltages generated by mechanical contact interruption, while maintaining the ability to handle large motors and transformers.
4Device complexity
If mechanical switches are used for switching, then the construction is simple, but the switching speed is relatively slow requiring predictive zero crossing techniques
Solution Approach 1:
The patent replaces mechanical switches with MEMS switches that use electrostatic actuation. This substitution increases switching speed by several orders of magnitude while maintaining relatively simple construction. The electrostatic mechanism responds almost instantaneously to control signals, eliminating the need for predictive zero crossing techniques.
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 MEMS based soft switching system effectively handles high currents and reduces transient overvoltages by synchronizing switch operations with zero crossings, enhancing the reliability and safety of power system switching operations.
Implementation Method 1
a first mechanism for selectively applying an electrostatic force between a first flexible surface and a second flexible surface
Data Source
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AI summary
A system (10) is presented. The system (10) includes detection circuitry (14) configured to detect occurrence of a zero crossing of an alternating source voltage (36) or an alternating load current (42). The system also includes switching circuitry (12) coupled to the detection circuitry (14) and comprising a micro-electromechanical system switch (20). Additionally, the system (10) includes control circuitry (16) coupled to the detection circuitry (14) and the switching circuitry (12) and configured to perform arc-less switching of the micro-electromechanical system switch (20) responsive to a detected zero crossing of an alternating source voltage (36) or alternating load current (42).