Filter Capacitance Estimation Using Resonance Frequency Tracking
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Solution Overview
Problem
Existing electrical converter systems require manual and disruptive maintenance to check the degradation of capacitors in electrical filters, which are crucial for preventing complete failure.
Innovation Solution
A method to estimate the capacitance of electrical filters using resonance frequency determination, allowing for automatic and non-disruptive monitoring during normal operation, utilizing frequency components injected into the converter's voltage reference to determine filter admittance and impedance, and calculate capacitance without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurements are used to check capacitor degradation, then measurement accuracy is improved, but system operation must be stopped and maintenance time increases
Solution Approach 1:
The patent replaces manual mechanical measurement methods with an automated electronic measurement system. The controller automatically determines filter admittance/impedance by injecting frequency components and processing electrical signals, eliminating the need for manual intervention and system shutdown while maintaining measurement accuracy through computational analysis of resonance and anti-resonance frequencies.
Solution Approach 2:
The system performs preliminary capacitance estimation by continuously monitoring filter admittance/impedance characteristics during normal operation. By detecting changes in resonance and anti-resonance frequencies in advance, the system can predict capacitor degradation trends and schedule maintenance proactively, preventing complete capacitor failure without requiring emergency shutdowns.
2Loss of information
If manual measurements are performed, then detailed capacitance data is obtained, but the process becomes complex and requires service technician intervention
Solution Approach 1:
The system performs self-diagnosis by automatically measuring filter admittance/impedance and calculating capacitance values without external intervention. The controller independently determines resonance and anti-resonance frequencies, processes the electrical signals, and generates capacitance estimates, enabling the system to monitor its own health status and eliminate the need for service technician involvement in routine capacitance checking.
Solution Approach 2:
The system implements continuous feedback monitoring by regularly measuring filter admittance/impedance characteristics and comparing capacitance values over time. The controller tracks degradation trends and can trigger maintenance alerts when capacitance falls below threshold values, providing automated information about capacitor health status without requiring manual data collection or analysis.
3Productivity
If the converter system operates continuously, then productivity is improved, but capacitor degradation cannot be monitored without stopping operation
Solution Approach 1:
The system enables continuous operation by performing capacitance measurements during normal converter operation. The controller injects frequency components into the operating system and processes the resulting electrical signals to determine filter admittance/impedance and calculate capacitance values, allowing uninterrupted monitoring of capacitor degradation while maintaining full productivity without requiring system shutdowns.
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 continuous, non-intrusive estimation of filter capacitance and degradation, reducing maintenance downtime and operational costs by allowing real-time monitoring and predicting capacitor replacement needs.
Implementation Method 1
at least one of a resonance frequency and an anti-resonance frequency of the electrical filter is expected
Data Source
AI summary
Described herein is a method of estimating a quantity dependent on a capacitance (Cf) of an electrical filter connected to an AC side of an electrical converter. The method includes injecting a plurality of frequency components into a voltage reference of the electrical converter; operating the electrical converter with the voltage reference by determining switching commands from the voltage reference and applying the switching commands to the electrical converter; determining an AC side voltage (uc) and an AC side current (ic) in the AC side of the electrical converter and determining a filter admittance and/or filter impedance from the AC side voltage (uc) and the AC side current (ic); determining at least one of a resonance frequency and an anti-resonance frequency of the electrical filter; and determining the quantity dependent on the capacitance (Cf) of the electrical filter from the resonance frequency and/or the anti-resonance frequency.