Synchronous Machine Self-Sensing Fault Detection via DC Power Validation
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Solution Overview
Problem
Challenges in precise rotor position and speed sensing in synchronous machines due to sensor noise, signal interference, and mechanical misalignments lead to deviations in rotor position and speed estimation, potentially causing suboptimal performance and catastrophic failure.
Innovation Solution
A control system that continuously calculates inverter DC power based on phase currents, DC link voltage, and gate signals, comparing it against commanded mechanical power, with a threshold to detect and correct rotor position and speed deviations, and shut down the inverter if errors exceed acceptable margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotor position and speed sensing is performed using sensors in synchronous machines, then operational parameters and performance characteristics can be determined, but sensor noise, signal interference, and mechanical misalignments cause deviations in estimation that may lead to suboptimal performance or catastrophic failure
Solution Approach 1:
The patent introduces an intermediary validation mechanism that compares estimated rotor position and speed (from sensorless control) with actual measurements from physical sensors. This intermediary comparison system identifies and corrects deviations caused by sensor noise or interference before they propagate to the inverter control, thereby maintaining reliability while preserving measurement precision.
Solution Approach 2:
The patent implements a feedback loop where the controller continuously monitors the difference between estimated and actual rotor position and speed. When deviations exceed predetermined thresholds, the system generates correction signals or shutdown commands to prevent catastrophic failure. This feedback mechanism ensures reliability by actively compensating for measurement errors in real-time.
2Device complexity
If sensorless control is used to estimate rotor position and speed, then system complexity is reduced, but estimation errors may propagate and cause inverter failure
Solution Approach 1:
The patent applies beforehand cushioning by implementing predetermined threshold values for rotor position and speed estimation errors before actual failure occurs. The controller continuously monitors estimation accuracy and prepares correction mechanisms or shutdown procedures in advance, cushioning against potential catastrophic failures from estimation errors while maintaining the simplicity of sensorless control.
Solution Approach 2:
The patent enables the control system to self-validate its own estimates by comparing them against physical sensor measurements when available. The system performs self-diagnosis of estimation accuracy and automatically corrects or isolates errors without external intervention, maintaining reliability while preserving the reduced complexity of sensorless operation.
3Productivity
If the inverter continues operating with exceeded error margins, then productivity is maintained, but error propagation may lead to catastrophic failure
Solution Approach 1:
The patent applies dynamics by making the inverter operation status adaptive rather than static. The controller dynamically adjusts operation continuity based on real-time estimation error magnitudes. When errors remain within thresholds, the inverter continues operating to maintain productivity; when errors exceed thresholds, the system dynamically switches to correction or shutdown modes to prevent catastrophic failure, thus balancing productivity and reliability.
Data Source
AI summary
Techniques are described to continuously calculate an inverter DC power of a synchronous machine, e.g., motor or generator, based on the individual phase currents, DC link voltage, and gate signals, which can be compared against the commanded mechanical power based of the estimated rotor speed and commanded torque. A controller can determine whether to shut down the inverter, such as the pulse width modulation (PWM), if the DC power is greater than a threshold value. Such a threshold can be defined to allow an acceptable position and speed estimation error margin.