Hybrid Transfer Switch for Transient-Free AC Source Switching
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Solution Overview
Problem
Conventional Break-Before-Make transfer switches cause momentary power interruptions during transitions between AC power sources, which are undesirable in critical applications, while Make-Before-Break switches are complex and costly, limiting their use to high-power applications.
Innovation Solution
A hybrid solid-state transfer switch combining electromechanical relays and solid-state devices, synchronized by a controller, performs a Make-At-Break operation to ensure seamless power transfer by using relays and solid-state devices in coordination to maintain power delivery without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Break-Before-Make transfer switches are used, then device complexity is reduced, but power interruption occurs during transitions
Solution Approach 1:
The patent combines a mechanical relay with a solid-state device (such as a triac or transistor) in a hybrid configuration. The relay provides the make-before-break switching capability while the solid-state device ensures smooth transition and eliminates arcing. This merging of mechanical and solid-state components achieves continuous power transfer without requiring a fully complex Make-Before-Break mechanical switch.
Solution Approach 2:
The solid-state device acts as an intermediary element during the transition period. When the relay contacts are opening, the solid-state device temporarily carries the load current, bridging the gap and ensuring continuous power delivery. This intermediary role allows the system to achieve power continuity without the full complexity of synchronized Make-Before-Break mechanical switching.
2Reliability
If Make-Before-Break transfer switches are used, then power continuity is maintained, but cost and complexity increase
Solution Approach 1:
The patent replaces part of the mechanical Make-Before-Break switching mechanism with a solid-state device. Instead of requiring a complex mechanical arrangement where contacts are made before broken, the solid-state device (triac or transistor) is used to electronically bridge the transition period. This substitution maintains power continuity while significantly reducing mechanical complexity and manufacturing cost.
Solution Approach 2:
The patent changes the operational parameters of the switching system by introducing a solid-state device that can be precisely controlled through electrical signals. The controller adjusts the firing angle or gate signal timing of the solid-state device to ensure it conducts during the critical transition period, achieving continuous power transfer through parameter control rather than complex mechanical timing.
3Reliability
If hybrid solid-state and relay switching is used, then power transition smoothness is improved, but device complexity increases
Solution Approach 1:
The patent segments the switching function into two distinct components: the mechanical relay handles the primary circuit breaking and making, while the solid-state device handles the transition smoothing and current bridging. This segmentation allows each component to perform its specialized function efficiently, with the relay providing robust mechanical switching and the solid-state device providing smooth electronic transition, reducing the overall system complexity compared to a fully mechanical Make-Before-Break design.
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 switch provides a reliable, seamless power transition with minimal disruption, suitable for critical applications and renewable energy systems, enhancing power management and efficiency.
Implementation Method 1
at least one relay that is mechanically switchable between a closed state and an open state. With the at least one relay in the closed state, the first input is electrically connected to the output via the at least one relay
Implementation Method 2
at least one solid-state device that is electrically switchable between an enabled state and a disabled state. With the at least one solid-state device in the enabled state, the second input is electrically connected to the output via the at least one solid-state device
Data Source
AI summary
A transient free switch includes a first input connected to a first alternating current (AC) power source, a second input connected to a second AC power source, and an output connected to a load. A controller manages a transfer of power using at least one relay and at least one solid-state device. When the relay is in a closed state, the first source is connected to the load. Upon determining a request to switch, the controller switches the relay from the closed state to an open state and switches the solid-state device from a disabled state to an enabled state, which connects the second source to the load. This provides an uninterrupted power path during the relay's mechanical transition. After the relay finishes switching to the open state, the controller switches the solid-state device back to the disabled state.