Static Transfer Switch Detection Circuit for UPS Fault Monitoring

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Solution Overview

Problem

Traditional uninterruptible power systems using current sensors cannot detect short-circuit faults in silicon controlled rectifiers when the system is in energy-saving mode, leading to increased risk of damage due to undetected large short-circuit currents.

Innovation Solution

A detection circuit comprising a high-pass filter, low-pass filter, absolute value circuit, and determination unit connected to a static transfer switch, which filters terminal voltage components to generate signals indicating normal or abnormal conditions, allowing for immediate protection measures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a current sensor is used to detect short-circuit faults, then the detection is effective in online mode, but the detection capability is lost in energy-saving mode

Engineering Contradiction:

Improvefault detection capabilityVSAvoiddetection coverage across operating modes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the detection parameter from current (detected by CT sensor) to voltage (detected by voltage detection circuit). By monitoring the voltage across the static transfer switch terminals, the system can detect abnormal conditions in both online mode and energy-saving mode, resolving the limitation where current-based detection fails in energy-saving mode.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the system operates in energy-saving mode to reduce power consumption, then energy efficiency is improved, but the ability to detect short-circuit faults is lost

Engineering Contradiction:

Improvepower consumptionVSAvoidshort-circuit detection capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a voltage detection circuit as an intermediary monitoring mechanism that operates independently of the system's power mode. This circuit continuously monitors the voltage across the static transfer switch, providing fault detection capability without requiring the main system to be in online mode, thus maintaining reliability while allowing energy-saving operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If traditional current sensor detection is used, then the detection method is simple, but the protection response is delayed in energy-saving mode

Engineering Contradiction:

Improvedetection circuit complexityVSAvoidprotection response time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The voltage detection circuit performs preliminary monitoring of the static transfer switch condition continuously, regardless of operating mode. By maintaining constant voltage monitoring, the system is prepared to detect faults immediately when they occur, eliminating the delay that would otherwise occur when switching from energy-saving to online mode for detection.

Inventive Principle:

Principle #10Preliminary action

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 detection of abnormal conditions in silicon controlled rectifiers across both online and energy-saving modes, reducing the risk of system damage by providing timely protection.

Implementation Method 1

A low-frequency component of a terminal voltage between a first terminal and a second terminal of the static transfer switch is filtered off by a high-pass filter, so that a first signal is generated

Methodology Applied

Scientific EffectHigh-pass filtering: Filter (electronic)

Implementation Method 2

A high-frequency component of the first signal is filtered off by a low-pass filter, so that a second signal is generated

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Implementation Method 3

The second signal is converted into an absolute value signal by an absolute value circuit

Methodology Applied

Scientific EffectAbsolute value conversion:

Data Source

PatentUS11293984B2Detection circuit, detection method and uninterruptible power system using same

Publication Date: 2022.04.05 DELTA ELECTRONICS INC(CN)

AI summary

A detection circuit is electrically connected with a static transfer switch. The static transfer switch includes a silicon controlled rectifier. The detection circuit includes a high-pass filter, a low-pass filter, an absolute value circuit and a determination unit. After the high-pass filter filters off a low-frequency component of a terminal voltage between the first terminal and the second terminal of the static transfer switch, a first signal is generated. After a high-frequency component of the first signal is filtered off by the low-pass filter, a second signal is generated. The second signal is converted into an absolute value signal by the absolute value circuit. If no pulse signals are contained in the absolute value signal, the determination unit determines that the static transfer switch is in an abnormal on condition.