Encoderless Motor Parameter Identification via Standstill Signal Injection
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Solution Overview
Problem
Existing methods for determining electrical equivalent circuit diagram parameters of three-phase asynchronous motors require mechanical or electrical loading, which can lead to overloading and are invasive, making them inefficient and risky.
Innovation Solution
A method that feeds a test signal in both α and β directions at standstill, allowing for the measurement of equivalent circuit diagram parameters without mechanical or electrical loading, using signal-theoretical methods to transform time domain data into frequency domain data and extract parameters from the frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct current, no-load and short-circuit tests are carried out to determine equivalent circuit parameters, then the electrical behavior can be characterized, but the motor is subjected to mechanical or electrical overload risks
Solution Approach 1:
The patent changes the operating parameters by performing measurements at standstill (zero speed) instead of requiring the motor to run at various speeds and loads. This parameter change allows determination of all equivalent circuit parameters (stator resistance, rotor resistance, leakage inductances, and main inductance) without subjecting the motor to mechanical or electrical overload conditions.
Solution Approach 2:
The patent replaces mechanical testing methods (no-load tests, short-circuit tests requiring motor rotation and mechanical loading) with an electrical measurement method using voltage and current signals at standstill. This substitution eliminates the need for mechanical sensors and mechanical overload conditions while achieving accurate parameter identification.
2Loss of information
If mechanical sensors are used to measure operating behavior at different speeds, then speed-correlated parameters can be derived, but the measurement system becomes more complex and invasive
Solution Approach 1:
The patent replaces mechanical sensors (speed sensors, position sensors) with an electrical measurement system that uses voltage and current signals. By performing measurements at standstill and using signal-theoretical methods, the system derives electrical behavior characteristics without requiring mechanical sensors or measuring rotating components, thus reducing system complexity and invasiveness.
Solution Approach 2:
The patent extracts the essential electrical behavior information directly from voltage and current measurements at standstill, separating the electrical parameter identification from mechanical measurement requirements. This extraction eliminates the need for mechanical sensor systems while obtaining the necessary electrical characteristics.
3Measurement precision
If the motor is driven in a test environment to perform time domain measurements, then operating behavior can be measured, but the process is time-consuming and requires complex test setups
Solution Approach 1:
The patent performs all necessary measurements at standstill before any rotation or operation. By preparing the measurement system and acquiring all required voltage and current data while the motor is stationary, the method eliminates the need for time-consuming dynamic testing and motor rotation during measurement processes.
Solution Approach 2:
The patent replaces time-domain dynamic measurements (requiring motor rotation and operation) with frequency-domain measurements at standstill. This substitution allows complete electrical characterization without the motor needing to run, significantly reducing measurement time and eliminating the need for complex dynamic test setups.
Data Source
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AI summary
The invention relates to a method for the encoderless identification of electrical equivalent circuit parameters (15) of a three-phase asynchronous motor (09). The method comprises at least the following steps: - bringing the rotor (11) to a standstill position; - applying test signal voltages U1α, U1β in the α- and β-axis directions of the asynchronous motor (09) in the same direction; - measuring the signal current I1α, I1β in the α- and β-axis directions of the asynchronous motor (09); - identifying equivalent circuit parameters of the asynchronous motor (09) based on the test signal voltages U1a, U1β and the measurement signal currents I1α, I1β; wherein the test signal is applied to the asynchronous motor (09) in such a way that the rotor (09) remains torque-free.In related aspects, the invention relates to an identification device (39) for determining equivalent circuit parameters (15) of an asynchronous motor (09) and a motor control device (35) comprising this device, wherein the identified equivalent circuit parameters (15) can be used to determine, optimize, and monitor motor control. Finally, the invention proposes using the identification method for controlling electric drives.