Engine Generator Abnormality Detection via Duty Ratio
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Solution Overview
Problem
Conventional engine generators are unable to detect abnormalities when the AC current output from the inverter is small, limiting their ability to identify issues such as shorted windings or rectifiers.
Innovation Solution
The engine generator incorporates an abnormality detection system that utilizes an input voltage detector to monitor duty ratios and change rates, allowing for the identification of abnormalities even when the AC current is below a threshold value, by comparing pre- and post-short duty ratios and change rates, and incorporating DC voltage and engine revolution detectors to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AC current output from the inverter is small, then the generator operates under light load conditions, but the ability to detect abnormalities such as shorted windings or rectifiers deteriorates
Solution Approach 1:
The patent changes the detection parameter from AC current magnitude to duty ratio of input voltage. By monitoring how the duty ratio changes under varying load conditions, the system can detect abnormalities even when AC current is small. The duty ratio reflects the operational state of rectifiers and windings, providing a reliable detection metric independent of load magnitude.
Solution Approach 2:
The patent introduces the duty ratio as an intermediary parameter that mediates between the input voltage and the abnormality detection. Instead of directly detecting abnormalities through AC current, the system uses duty ratio changes as an intermediate indicator that reliably signals faults in rectifiers and windings regardless of current level.
2Loss of energy
If the engine generator operates at low AC current levels, then energy consumption is reduced, but the detection of generator abnormalities becomes unreliable
Solution Approach 1:
The system changes from current-based detection to duty ratio-based detection. The duty ratio of the input voltage to the converter provides reliable abnormality detection signals even at low current levels, eliminating the need to increase current for detection purposes and thus maintaining low energy consumption.
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 approach enables precise detection of engine generator abnormalities, preventing damage and ensuring reliable operation by accurately identifying issues even at low AC current levels, thereby improving fault detection accuracy.
Implementation Method 1
a generator body (14) connected to the engine (12)
Implementation Method 2
a converter (28) including a plurality of rectifiers that convert an output from the generator body to DC current
Data Source
AI summary
An engine generator includes a generator body connected to an engine, a converter including rectifiers that convert an output from the generator body to DC current, an inverter that converts an output from the converter to AC current, an input voltage detector that detects an input voltage from the generator body to the converter, and an AC current detector that detects an AC current output from the inverter. An abnormality in the engine generator is determined if a state that a current detected by the AC current detector is not higher than a first threshold value and a duty ratio of a voltage detected by the input voltage detector is not higher than the second threshold value continues for a first predetermined time; or if the current detected by the AC current detector is not higher than a third threshold value and the duty ratio change rate is not higher than a fourth threshold value.