Isolated Bus Transfer Using High-Frequency Transformer Switching
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Solution Overview
Problem
Conventional uninterruptable power supplies (UPS) are large, heavy, costly, and pose safety and environmental hazards due to large storage batteries, and existing bus transfer switches are slow in switching between power sources, which can lead to system failures during voltage disruptions.
Innovation Solution
The use of high-frequency switch-mode transformers with isolated primary windings and a controller for high-speed switching between power sources, allowing for efficient and rapid switching between power sources, reducing the size and weight of the transformer and eliminating the need for large isolation transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UPS systems use large storage batteries to maintain constant charge, then power supply reliability is improved, but device size, weight, and safety hazards increase
Solution Approach 1:
The patent extracts and eliminates the large storage battery component from the UPS system by implementing a high-speed transfer switch that directly switches between utility power and backup power sources, removing the need for heavy battery banks while maintaining power supply reliability
Solution Approach 2:
The patent replaces the mechanical/electrochemical battery-based power storage system with an electronic high-speed transfer switching system that uses solid-state switches and control circuits to achieve power source switching without moving parts or chemical energy storage
2Adaptability or versatility
If automatic bus transfer switches are used to disconnect and reconnect critical equipment between power busses, then power source switching capability is improved, but switching time increases to hundreds of milliseconds
Solution Approach 1:
The patent implements dynamic high-speed switching using solid-state switches that can change state in microseconds, replacing the slow mechanical or electromechanical bus transfer switches with a dynamic electronic switching system controlled by real-time voltage monitoring and control logic
Solution Approach 2:
The patent uses voltage detection circuitry that continuously monitors power source conditions in advance, allowing the control system to initiate switching actions before voltage disruptions affect the load, thereby reducing the effective switching time to microseconds
3Reliability
If isolation transformers operating at utility frequency are used to provide isolation, then electrical isolation is achieved, but device size and cost increase prohibitively
Solution Approach 1:
The patent changes the operating frequency parameter from utility frequency (50/60 Hz) to high switching frequency (kHz to MHz range), enabling the use of much smaller high-frequency transformers that provide the same electrical isolation function with dramatically reduced size and cost
Solution Approach 2:
The patent uses high-frequency switching waveforms that replicate the isolation function of traditional low-frequency transformers but achieve the same electromagnetic coupling and isolation effects at higher frequencies, allowing smaller core sizes and fewer turns
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 enables efficient power conversion with reduced size and weight, faster switching times, and eliminates the safety and environmental hazards associated with traditional UPS systems, while maintaining reliable power supply to critical equipment.
Implementation Method 1
A switch-mode transformer with a switching frequency much higher than the utility frequency (e.g., the frequency of the alternating voltage of the electrical utility) can provide the same function as a utility frequency isolation transformer
Implementation Method 2
The controller can control the H-bridge circuitry to provide inverted power output from one power source relative to another power source of the plurality of power sources
Data Source
AI summary
An apparatus for high-speed switching between a plurality of power sources includes a switch-mode isolation transformer. The switch-mode isolation transformer includes a plurality of isolated primary windings. Each of the plurality of isolated primary windings can be electrically isolated from others of the isolated primary windings and selectively couplable to a power source of the plurality of power sources. The switch-mode isolation transformer further includes a secondary winding coupled to a load. The apparatus further includes a controller to selectively couple one of the plurality of power sources through a corresponding isolated primary winding, responsive to detecting an adverse condition in another power source of the plurality of power sources. Other methods and systems are also described.