UPS Phase Synchronization During Voltage Detector Failure
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Solution Overview
Problem
Conventional uninterruptible power supply devices experience instantaneous interruptions in two-phase AC voltage supply to loads when a failure occurs in the voltage detector, leading to disruptions in power delivery.
Innovation Solution
An uninterruptible power supply device with a converter, inverter, bypass switch pair, semiconductor switch pair, multiple voltage detectors, and an abnormality detector, which controls the system to maintain continuous power supply by switching to DC voltage from a power storage device and synchronizing phases with commercial AC power when a voltage detector failure is detected, ensuring no instantaneous interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single voltage detector is used to control the converter and inverter, then the device structure is simple, but power supply interruption occurs when the voltage detector fails
Solution Approach 1:
The single voltage detector is segmented into multiple voltage detectors (first voltage detector and second voltage detector), each detecting voltage from different phases. This segmentation allows the system to continue operating using remaining functional detectors even when one fails, thereby improving reliability without excessive complexity increase.
Solution Approach 2:
The system performs preliminary detection of voltage detector abnormalities and proactively switches to bypass switches before actual power interruption occurs. The abnormality detector identifies detector failures in advance, allowing the control circuit to prepare and execute the bypass switching operation, preventing power supply interruption.
2Reliability
If the converter operation is stopped when voltage detector abnormality occurs, then the abnormal detector can safely control the system, but the inverter cannot maintain synchronized phase with commercial AC power
Solution Approach 1:
The system stores phase information of the commercial AC power supply before the voltage detector abnormality occurs. This preliminary storage of phase data allows the inverter to quickly restore phase synchronization after switching to battery power, eliminating the need to wait for converter restart and maintaining continuous synchronized operation.
Solution Approach 2:
The control circuit acts as an intermediary that manages the transition between converter-based operation and battery-based operation. It maintains phase synchronization information and coordinates the switching between different power sources, ensuring continuous synchronized power delivery to the load even during detector abnormalities.
3Reliability
If bypass switches are turned on immediately when power storage voltage reaches cut-off voltage, then power continuity is maintained, but instantaneous interruption occurs during switching transition
Solution Approach 1:
The bypass switches are turned on in advance before the voltage across the power storage device actually reaches the cut-off voltage. This preliminary activation ensures that the bypass path is already established and ready, eliminating any interruption when the main power path needs to be discontinued due to voltage depletion.
Solution Approach 2:
The system prepares the bypass path as a cushioning measure before the main power path fails. By having the bypass switches ready and the abnormality detection system monitoring conditions, the system creates a safety buffer that prevents power interruption when the power storage device voltage drops to critical levels.
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 solution ensures uninterrupted two-phase AC voltage supply to loads even when an abnormality occurs in the voltage detector, maintaining power continuity by seamlessly switching to stored DC power and synchronizing phases with commercial AC power.
Implementation Method 1
a converter configured to convert a two-phase AC voltage supplied from a commercial AC power supply into a DC voltage
Implementation Method 2
an inverter configured to convert the DC voltage generated by the converter or a DC voltage supplied from a power storage device into a two-phase AC voltage
Data Source
AI summary
When an abnormality occurs in a first voltage detector (4a), a control circuit (7) in an uninterruptible power supply device controls an inverter (3) in synchronization with an output signal (VI2D) from a second voltage detector (4b) to match a phase of a two-phase AC voltage (VO1, VO2) output from the inverter (3) with a phase of a two-phase AC voltage (VI1, VI2) supplied from a commercial AC power supply (51), and then turns on a semiconductor switch pair (S9, S10) and a bypass switch pair (S7, S8). Accordingly, even when an abnormality occurs in the first voltage detector (4a), the two-phase AC voltage can be supplied to a load (53) without instantaneous interruption.