Power Converter Health Monitoring via Slew Rate Ratios
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Solution Overview
Problem
Existing power converter monitoring methods involve continuous high sampling rates and complex algorithms, leading to increased costs and potential interference, and are not easily transportable, limiting their effectiveness during routine checks and maintenance.
Innovation Solution
A method involving the injection of a control pulse to selected power devices, measuring voltage and current slew rates, and determining slew rate ratios to assess power converter health, using less complex processing and non-intrusive sensors like Rogowski coils, allowing for portable and efficient monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous monitoring with high sampling rates and complex algorithms is used, then measurement precision and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation (PWM) signals to periodically switch power devices on and off at specific duty cycles, enabling health monitoring through transient responses rather than continuous monitoring. This reduces the need for high sampling rates and complex processing while maintaining effective detection capability
Solution Approach 2:
The patent extracts only the essential health indicators from the power converter system by measuring specific electrical parameters (voltage and current transients) during PWM switching events. This extraction approach focuses monitoring efforts on critical degradation signs without requiring comprehensive continuous analysis of all system parameters
2Reliability
If continuous high sampling rate monitoring is implemented, then reliability is improved, but loss of energy and operational interference increase
Solution Approach 1:
The monitoring system uses periodic PWM switching events rather than continuous high-frequency sampling. The health assessment is performed by analyzing transient responses during these periodic switching events, significantly reducing the energy consumption associated with data acquisition while maintaining reliable detection of power device degradation
Solution Approach 2:
The power converter's own PWM switching operations are utilized to generate the test signals needed for health monitoring. The normal switching events serve dual purposes: power conversion and health diagnostics, eliminating the need for separate dedicated test signal generation and reducing overall system energy consumption
3Measurement precision
If complex processing algorithms are used, then measurement precision is improved, but ease of operation and portability deteriorate
Solution Approach 1:
The patent extracts and measures only the essential transient electrical parameters (voltage and current slew rates) during PWM switching events. This focused parameter extraction approach enables effective health monitoring with simpler processing requirements, facilitating the use of portable monitoring equipment during field maintenance and service operations
Solution Approach 2:
The monitoring method relies on detecting changes in specific electrical parameters (voltage and current transient characteristics) rather than requiring complex multi-parameter analysis. This parameter-focused approach reduces computational complexity while maintaining sensitivity to power device degradation, enabling deployment with portable equipment
Data Source
AI summary
A method for monitoring a health of a power converter having a plurality of power devices includes selecting a first power device and a second power device from the plurality of power devices. The method includes injecting simultaneously a control pulse to only the first power device and the second power device, determining first voltage and current slew rates of the first power device and second voltage and current slew rates of the second power device, and determining a voltage slew rate ratio of the first voltage slew rate to the second voltage slew rate. The method includes determining a current slew rate ratio of the first current slew rate to the second current slew rate, and determining that the power converter is degraded when the voltage and current slew rate ratios lie outside respective predetermined voltage and current slew rate ratio ranges.