Hybrid MEMS and Solid-State Switching for Surge Current Handling
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Solution Overview
Problem
Conventional circuit breakers are large, slow, complex, and expensive, with solid-state switches experiencing leakage current and voltage drop issues that hinder their use in circuit breaker applications, while micro-electromechanical system (MEMS) switches face challenges in handling surge currents effectively.
Innovation Solution
A switching system combining micro-electromechanical system (MEMS) switching circuitry with solid-state switching circuitry and dual over-current protection circuitry, featuring a balanced diode bridge and pulse circuit to suppress arc formation and manage surge currents, allowing selective switching between MEMS and solid-state circuits based on load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromechanical switches are used in circuit breakers, then the switching mechanism is simple and reliable, but the device becomes large in size, slow in operation, and complex to build
Solution Approach 1:
The circuit breaker is divided into two independent switching paths: one with MEMS switches for normal operation and another with solid-state switches for surge current handling. This segmentation allows each path to be optimized for its specific function, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
Solid-state switching circuitry acts as an intermediary to handle surge currents before they reach the MEMS switches. This mediator protects the MEMS switches from damage during surge events, enabling the use of simpler, more reliable MEMS technology for normal operation.
2Speed
If solid-state switches are used to replace electromechanical switches, then switching speed increases, but leakage current and voltage drop cause excess heat generation
Solution Approach 1:
The switching system is segmented into solid-state switches for rapid surge current interruption and MEMS switches for steady-state operation. This division allows solid-state switches to operate only during brief surge events, minimizing their energy losses, while MEMS switches handle continuous operation with lower inherent losses.
Solution Approach 2:
Solid-state switches are activated periodically only during surge current events rather than continuously. This periodic operation reduces the cumulative energy loss from leakage current and voltage drop, as the solid-state switches remain inactive during normal steady-state operation.
3Power
If multiple MEMS switches are used in parallel to handle surge current, then surge current capability increases, but the cost increases significantly
Solution Approach 1:
Different switching technologies are applied to different operational conditions: solid-state switches are used locally for surge current handling while MEMS switches handle steady-state operation. This localized application of appropriate technology optimizes performance for each condition without requiring excessive numbers of expensive MEMS switches.
Solution Approach 2:
Solid-state switching circuitry serves as an intermediary that absorbs surge currents, protecting the MEMS switches from having to handle them. This mediator role allows the use of fewer MEMS switches than would otherwise be required, significantly reducing manufacturing cost while maintaining surge current capability.
4Device complexity
If MEMS switches are used for circuit breaker applications, then device size is reduced and cost is lowered, but arc formation between contacts occurs during switching
Solution Approach 1:
Solid-state switches are activated in advance to interrupt surge currents before the MEMS switches attempt to open under surge conditions. This preliminary action prevents the formation of harmful arcs by ensuring surge currents are already interrupted when MEMS switches operate, allowing them to function in their optimal arc-free manner.
Solution Approach 2:
Solid-state switching circuitry acts as an intermediary that handles the harmful surge currents, protecting the MEMS switches from arc formation. This mediator absorbs the harmful effects during surge events, enabling the MEMS switches to operate reliably without arc damage.
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
Enables reliable and cost-effective handling of surge currents while maintaining MEMS switches for steady-state operations and fault conditions, reducing heat generation and preventing arc formation between contacts.
Implementation Method 1
a first over-current protection circuitry connected in a parallel circuit with the micro-electromechanical system switching circuitry and the solid state switching circuitry, wherein the first over-current protection circuitry is configured to suppress arc formation between contacts of the micro-electromechanical system switching circuitry
Implementation Method 2
due to internal resistances, when solid-state switches operate in a conducting state, they experience a voltage drop
Implementation Method 3
since solid-state switches do not create a physical gap between contacts when they are switched into a non-conducting state, they experience leakage current. Furthermore, due to internal resistances, when solid-state switches operate in a conducting state, they experience a voltage drop. Both the voltage drop and leakage current contribute to the generation of excess heat
Data Source
Figure 1~2
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Figure 4
AI summary
A switching system is provided. The switching system includes electromechanical switching circuitry, such as a micro-electromechanical system switching circuitry (202). The system may further include solid state switching circuitry (204) coupled in a parallel circuit with the electromechanical switching circuitry, and a controller (208) coupled to the electromechanical switching circuitry and the solid state switching circuitry. The controller may be configured to perform selective switching of a load current between the electromechanical switching circuitry and the solid state switching circuitry in response to a load current condition appropriate to an operational capability of a respective one of the switching circuitries.