Induction Motor Rotor Resistance Estimation via State Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for controlling induction motors are vulnerable to changes in motor parameters, particularly rotor resistance, due to temperature fluctuations caused by load changes, which degrade vector control performance as they do not estimate parameters in real time.
Innovation Solution
An apparatus that includes a state estimator and an integral controller to calculate the error in rotor resistance and stator resistance, using d and q-axis currents and voltages in a synchronous reference frame, and updates the control operation in real time to enhance vector control performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time parameter estimation is implemented, then vector control performance is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the estimated rotor resistance is fed back to the current controller to adjust control parameters in real-time. The state estimator continuously monitors motor parameters and provides feedback signals to compensate for resistance variations, thereby maintaining optimal vector control performance despite parameter changes.
Solution Approach 2:
The patent introduces a state estimator as an intermediary component between the motor and the controller. This intermediary estimates rotor resistance by processing signals from the motor and provides compensated parameter information to the current controller, enabling accurate control without directly measuring resistance changes.
2Measurement precision
If parameter estimation is performed, then control accuracy is improved, but measurement and detection difficulty increases
Solution Approach 1:
The patent replaces direct physical measurement of rotor resistance with an estimation approach using electrical signal processing. Instead of inserting measurement devices into the motor windings, the system uses voltage and current signals already present in the control circuit to calculate resistance parameters through mathematical models and state estimation algorithms.
Solution Approach 2:
The state estimator acts as an intermediary that indirectly determines rotor resistance by processing easily measurable voltage and current signals. Rather than directly measuring resistance (which would require complex instrumentation), the system uses the intermediary estimation process to derive resistance values from standard electrical measurements.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5
AI summary
An apparatus for estimating a parameter of an induction motor is provided. The estimating apparatus receives an output from a current controller and d and q-axis currents in a synchronous reference frame applied to an induction motor, calculates an error of rotor resistance, and obtains a difference between the rotor resistance and nominal rotor resistance.