Motor and Output Filter Parameter Estimation via Resonance Injection
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Solution Overview
Problem
Existing methods cannot estimate the parameters of an electric motor and a power filter when an output filter is connected, requiring laborious and time-consuming disconnection processes.
Innovation Solution
A method involving the injection of an AC signal of different frequencies to identify resonance frequencies and calculate the ratio of power filter inductance to motor leakage inductance, allowing for parameter estimation while the output filter remains connected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output filter is disconnected to estimate motor parameters, then the parameter estimation accuracy is improved, but the time consumption and operational complexity increase
Solution Approach 1:
The system performs preliminary identification of filter parameters before motor parameter estimation. By first detecting the presence of a power filter and determining its parameters (inductance Lf and capacitance Cf) using injection signals, the system prepares the necessary information in advance to enable accurate motor parameter estimation without requiring physical disconnection of the filter.
Solution Approach 2:
The patent uses an intermediary approach by introducing test signals (injection signals with varying frequencies) that interact with both the filter and motor to extract parameter information. The frequency response analysis acts as an intermediary method to separate and identify individual component parameters despite them being connected in the circuit.
2Measurement precision
If the output filter is disconnected to estimate motor parameters, then the parameter estimation accuracy is improved, but the operational complexity and cost increase
Solution Approach 1:
The system performs self-identification of both filter and motor parameters without requiring external intervention or manual disconnection operations. The controller automatically detects the presence of the power filter, determines its parameters through signal injection and frequency response analysis, and then proceeds to estimate motor parameters, making the entire process autonomous and eliminating the need for manual operational steps.
Solution Approach 2:
The identification system serves multiple functions: it detects the presence of the power filter, identifies filter parameters (Lf and Cf), and estimates motor parameters (Rr, Lr, σL, τr). This multi-functional capability allows the system to handle both filter and motor characterization through a single integrated process, reducing operational complexity while maintaining accuracy.
3Productivity
If the output filter remains connected during parameter estimation, then the operational efficiency is improved, but the ability to accurately estimate both filter and motor parameters deteriorates
Solution Approach 1:
The patent segments the parameter identification process into distinct stages: first identifying filter parameters using injection signals and frequency response analysis, then using those identified filter parameters to calculate motor parameters. This segmentation allows accurate estimation of both sets of parameters while they remain connected, by mathematically separating their contributions through the frequency response data.
Solution Approach 2:
The system changes parameters by injecting signals at different frequencies and analyzing the frequency response. By varying the injection signal frequency and measuring the resulting current and voltage responses, the system can distinguish between filter and motor parameters through their different frequency characteristics, enabling accurate parameter extraction while both components remain connected.
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 precise control and monitoring of both the power filter and motor by determining their electrical parameters without the need to disconnect the output filter, improving efficiency and reducing costs.
Implementation Method 1
The ASD provides a pulse width modulation voltage at its output for this controllable motion
Implementation Method 2
output power filters, such as Sine Wave Filters (SWF) are installed at the output of a frequency converter with the purpose of filtering out high frequency components from a current flowing through the motor
Implementation Method 3
determining a resonance frequency of the power filter based on the measured response signal
Data Source
AI summary
A method for estimating electrical parameters of an electric motor (205) and a power filter (203) connected to a power converter (201) including injecting an AC signal of different frequencies for a given time window in the power filter (203) and the motor (205), measuring a response signal of the power filter (203) and the motor (205) to the injected AC signal, determining a resonance frequency of the power filter (203) based on the measured response signal, calculating a ratio of leakage inductances of the power filter (203) and the motor (205).