Sensorless Reactance Control for Revolving Field Machines
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Solution Overview
Problem
Existing methods for sensorless control of three-phase machines face challenges such as the need for mechanical encoders or high-quality machine models, which reduce robustness and are limited in torque overload or speed, especially in the saturation range.
Innovation Solution
A method that uses discrete angular positions for target current space vector advancement, compensates for EMF effects, and determines phase inductance to control torque and flux linkage directly, eliminating the need for rotor position sensors by utilizing EMF-compensated phase current increases and characteristic phase inductance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical encoder is used for flux determination, then high-quality flux determination is achieved, but robustness is reduced and volume increases
Solution Approach 1:
The patent replaces the mechanical encoder system with an electromagnetic field-based measurement system. By using reactance measurements and EMF-compensated current measurements, the system determines rotor position and flux linkage without mechanical sensors, thereby maintaining measurement precision while improving robustness and reducing volume.
Solution Approach 2:
The patent introduces EMF compensation as an intermediary process. By compensating for the back-EMF signal in the measurement circuit, the system can accurately extract reactance information from current measurements even during rotation, enabling sensorless control to work reliably across the entire operating range including high-speed conditions.
2Measurement precision
If a high-quality machine model based on induced voltage is used, then flux determination quality is improved, but speed range is limited
Solution Approach 1:
The patent changes the measurement parameter from voltage-based to current-based measurements with EMF compensation. By measuring current increases and compensating for EMF effects, the system maintains accurate reactance determination across the entire speed range including zero speed and high speed, overcoming the speed limitations of traditional voltage-based models.
3Measurement precision
If a high-quality machine model based on reactance measurements is used, then flux determination quality is improved, but torque overload capability is limited
Solution Approach 1:
The patent performs off-line determination of the relationship between current increases and reactance changes at discrete angular positions. This preliminary characterization enables the on-line system to accurately determine rotor position and flux linkage even in the saturation range and at high torque overloads, as the measurement method itself is not limited by operating conditions.
4Measurement precision
If measurement patterns are used for reactance control, then reactance measurement is achieved, but measurement time increases and measurement quality deteriorates due to EMF disturbance
Solution Approach 1:
The patent enables continuous reactance measurement during normal machine operation rather than requiring separate measurement cycles. By using EMF-compensated current measurements during regular operation, the system obtains accurate reactance information without stopping the machine or dedicating separate measurement time, thereby maintaining measurement quality while eliminating measurement time loss.
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 high-quality, sensorless control in the saturation range, achieving precise torque and flux control without mechanical encoders, with high selectivity and resolution, suitable for synchronous, asynchronous, and reluctance machines.
Implementation Method 1
the measurement pattern is heavily disturbed by the EMF
Data Source
AI summary
The method involves guiding a reference-flow range indicator limited to discrete angular position in a three-phase machine based on an electromotive force-compensating phase current rise measurement for determining characteristic line inductance. The measured inductance depends on the actual reference-flow range indicator for known parameter and on field flux linkage for system condition that is unknown in its angular position.