UPS Voltage Detection via Phase Estimation
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Solution Overview
Problem
Existing uninterruptible power supply devices experience instantaneous voltage drops during transitions from commercial power supply to inverter power supply due to delayed detection of AC power source failures, leading to poor reliability and efficiency.
Innovation Solution
An uninterruptible power supply device with a power source abnormality detecting unit that estimates the maximum value of AC input voltage and compares it to stored temporal transitions during simulated power failures, allowing for fast and accurate detection of power failures and seamless mode switching between commercial and inverter power supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the abnormality detection is based on comparing detected voltage and frequency values to reference value ranges, then the detection method is simple, but the detection time is delayed causing instantaneous voltage drops
Solution Approach 1:
The system performs preliminary actions by detecting voltage magnitude and phase angle in advance, and pre-calculates the maximum value continuously before power failure occurs. This allows the system to have the maximum value ready immediately when power failure happens, eliminating detection delay without requiring complex real-time comparison systems.
Solution Approach 2:
The invention replaces the mechanical/electrical maximum detection method with a computational approach. Instead of using complex circuitry to directly detect maximum voltage, the system uses a computation unit to calculate the maximum value from voltage magnitude and phase angle measurements, simplifying the hardware while improving response speed.
2Reliability
If the system uses on-line power supply mode to ensure high-quality AC power supply, then the power quality is improved, but power loss increases due to inverter operation
Solution Approach 1:
The control device continuously monitors the AC power source status and provides feedback to determine whether to operate in on-line or standby mode. By detecting power source abnormalities and responding with mode switching, the system maintains power quality when needed while minimizing inverter operation during normal conditions, thus reducing power loss.
3Loss of energy
If the system uses standby power supply mode to reduce power loss, then energy efficiency is improved, but power quality deteriorates with large voltage fluctuations
Solution Approach 1:
The system dynamically switches between standby and on-line modes based on real-time detection of AC power source status. During normal operation, it operates in standby mode for energy efficiency, but automatically transitions to on-line mode when power source abnormalities are detected, thus maintaining both energy efficiency and power quality according to conditions.
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
Prevents instantaneous voltage drops and improves reliability by enabling rapid detection of AC power source failures, ensuring a stable transition to inverter power supply and maintaining high efficiency during commercial power supply operations.
Implementation Method 1
a converter for converting alternating-current (AC) power from an AC power source into direct-current (DC) power
Implementation Method 2
an inverter for converting DC power generated by the converter or DC power of a power storage device into AC power and supplying the AC power to a load
Data Source
AI summary
A control device controls an uninterruptible power supply device such that a transition is made to an inverter power supply mode when a power source abnormality detecting unit detects a power failure of an AC power source in a case where a commercial power supply mode is selected. The power source abnormality detecting unit computes an estimated value of the maximum value of AC input voltage, based on detected values of the instantaneous value and the phase of AC input voltage supplied to an input terminal. The power source abnormality detecting unit is configured to store temporal transition of the maximum value when the AC power source undergoes a simulated power failure and determine a power failure of the AC power source, based on comparison between temporal transition of the estimated value of the maximum value and the stored temporal transition of the maximum value during power failure.