UPS Bypass Power Path for Inverter Failure Backup
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Solution Overview
Problem
Conventional uninterruptible power supplies fail to drive a load when the inverter and AC power source are both failed, resulting in a power supply failure.
Innovation Solution
An uninterruptible power supply system with a controller that selects from multiple power supply modes, including a third mode where the first switch is turned off and the second switch is turned on, allowing the first power converter to convert DC power from the storage device into AC power and supply it to the load via the second switch, ensuring continuous operation even if the second power converter and AC power source are failed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional uninterruptible power supply with a single inverter is used, then the structure is simple, but the load cannot be driven when both the inverter and AC power source fail
Solution Approach 1:
The power conversion function is segmented into two independent power converters: a first power converter connected between the AC power source and power storage device, and a second power converter connected between the power storage device and the load. This segmentation allows the system to operate in multiple modes depending on component availability, thereby improving reliability without requiring a completely redundant system architecture.
Solution Approach 2:
The first power converter is designed to perform multiple functions: it can convert AC power to DC for charging the power storage device during normal operation, and it can also convert DC power to AC for supplying the load when the second power converter fails. This multi-functionality allows a single component to compensate for failures in other parts of the system.
2Reliability
If the second power converter is removed to simplify the system, then the device complexity is reduced, but the load cannot be powered when the AC power source fails
Solution Approach 1:
The power storage device serves as an intermediary between the AC power source and the load. It accumulates energy from the AC source through the first power converter and can subsequently supply energy to the load through the first power converter when the AC source fails, ensuring continuous power supply without requiring the second power converter.
3Adaptability or versatility
If multiple power supply modes are implemented to handle various failure scenarios, then the adaptability is improved, but the control complexity increases
Solution Approach 1:
The control system dynamically switches between different operational modes based on the status of the AC power source and power converters. The controller monitors system conditions and automatically transitions between normal operation mode, AC failure mode, and converter failure mode, providing adaptability without requiring complex manual intervention or overly sophisticated control algorithms.
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 the uninterrupted operation of the load by converting DC power to AC power and supplying it through the second switch, even if the second power converter and AC power source are unavailable, thus ensuring continuous power delivery.
Implementation Method 1
controls the first power converter so as to convert the AC power supplied from the AC power source via the first switch into DC power and store the DC power in the power storage device
Implementation Method 2
controls the first power converter so as to convert the DC power of the power storage device into AC power and supply the AC power to the load via the second switch
Data Source
AI summary
In the uninterruptible power supply, when the input switch is connected between the input terminal and the AC node of the converter and the fourth operation mode is selected, the input switch is turned off and the bypass switch is turned on, and the converter is controlled to convert the DC power of the battery into AC power and supply the AC power to the load via the bypass switch. Thus, even if the inverter is failed when the commercial AC power source is failed, it is possible to drive the load.