Hybrid Contactor Series-Parallel Switching for Galvanic Isolation
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Solution Overview
Problem
Current circuit breakers for aerospace power distribution systems, particularly those using Solid State Power Controllers (SSPCs), are inefficient and costly for high power loads above 120 VAC or 25 Amps, and lack galvanic isolation, leading to issues like leakage current and mechanical contact degradation.
Innovation Solution
A hybrid contactor with a series-parallel arrangement of mechanical and solid-state switching elements, utilizing two mechanical contacts in series with an electromagnetic actuator and a semiconductor switch, ensuring galvanic isolation and reducing switching stress on mechanical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Solid State Power Controllers (SSPCs) are used for high power loads above 120 VAC or 25 Amps, then load control and protection functions are achieved, but the device becomes large, inefficient, and very costly to design and produce
Solution Approach 1:
The invention divides the switching function into two separate components: mechanical contacts handle the high power load switching, while semiconductor devices (SCRs or triacs) handle the control function. This segmentation allows each component to be optimized for its specific function, avoiding the need for a large, expensive SSPC to handle both control and high power switching.
Solution Approach 2:
The invention merges the advantages of mechanical switching (high power handling, galvanic isolation) with semiconductor switching (precise control, efficiency) into a single hybrid contactor device that performs both functions simultaneously.
2Ease of operation
If SSPCs are used for switching, then load control is achieved, but galvanic isolation is lost and leakage current occurs when in the off state
Solution Approach 1:
The invention separates the control circuit from the power circuit using mechanical contacts that provide galvanic isolation. The semiconductor control devices operate on one side of the mechanical contact gap, while the load operates on the other side, maintaining electrical isolation while enabling control.
Solution Approach 2:
The mechanical contacts serve as an intermediary that transfers control signals while maintaining galvanic isolation. When the mechanical contacts are open, they physically break the electrical connection, preventing leakage current and maintaining isolation between control and load circuits.
3Reliability
If mechanical contacts are used for switching, then galvanic isolation is maintained, but the contacts experience degradation and failure over time
Solution Approach 1:
The invention divides the switching function into two separate components: mechanical contacts handle the high power load switching, while semiconductor devices (SCRs or triacs) handle the control function. This segmentation allows each component to be optimized for its specific function, avoiding the need for a large, expensive SSPC to handle both control and high power switching.
Solution Approach 2:
The invention replaces semiconductor switching elements with mechanically isolated contacts for the high-power switching function, eliminating the need for complex semiconductor devices while maintaining galvanic isolation. The mechanical contacts are designed to handle the full load current without the degradation issues of traditional relay contacts.
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 hybrid contactor provides cost-effective, efficient, and reliable switching with galvanic isolation, reduced heat dissipation, and minimized relay contact failure, suitable for high power AC and DC applications.
Implementation Method 1
The contacts are used with one single activating electromagnetic actuator
Data Source
AI summary
A hybrid contactor device that provides the ability to use the device with both AC and DC circuits is provided. The hybrid contactor includes a series-parallel arrangement of mechanical contacts with solid state devices, increasing the switching capacity of the mechanical contacts, and maintains galvanic isolation when open. The hybrid contactor includes two mechanical contacts, and is arranged so that one contact closes shortly before the other. The second contact forms a parallel circuit with an electronic switch.