Rotor Position Detection Using Local Inductance Matrix
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Solution Overview
Problem
Conventional methods for determining the rotor position of three-phase machines are unstable and noise-immune, especially at low rotational speeds, due to the incomplete use of the rotor position-dependent local inductance matrix and simplified assumptions about anisotropy, leading to instability in closed-loop control systems.
Innovation Solution
A method that utilizes the complete differential inductance matrix to determine the rotor position by weighting and summing measured local inductance values, accounting for the orientation and magnitude of the fundamental current, and adjusting the model rotor angle using a control loop to maintain stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional injection methods use simplified assumptions about anisotropy and only the anisotropic component of the local inductance matrix, then the device complexity is reduced, but the stability of the control system deteriorates
Solution Approach 1:
The patent changes the parameters used for rotor position determination from simplified anisotropic components to the complete local inductance matrix, including all three components (Laa, Lbb, Lab). This parameter expansion resolves the stability issue while maintaining computational feasibility through systematic evaluation of all matrix elements.
Solution Approach 2:
The patent makes the control method universally applicable to all three-phase machines regardless of their specific anisotropic properties by using the complete local inductance matrix. This eliminates the need for simplified assumptions about machine characteristics, allowing the method to handle diverse machine types and operating conditions stably.
2Ease of operation
If conventional methods use only the anisotropic component of the local inductance matrix, then the measurement precision is reduced, but the ease of operation is improved
Solution Approach 1:
The patent segments the local inductance matrix into three distinct components (Laa, Lbb, Lab) and evaluates each separately. This segmentation allows systematic processing of the complete matrix information while maintaining computational organization and feasibility.
Solution Approach 2:
The patent merges all three components of the local inductance matrix (Laa, Lbb, Lab) into a unified evaluation framework for rotor position determination. This combination充分利用s the complete information content of the matrix, improving measurement precision while maintaining operational simplicity through integrated processing.
3Measurement precision
If rotary position encoders are used to determine rotor position, then the measurement precision is improved, but the reliability of the system deteriorates due to increased failure risk
Solution Approach 1:
The patent replaces the mechanical rotary position encoder with an electrical measurement method based on the local inductance matrix. This substitution eliminates mechanical wear and failure modes while achieving comparable or superior measurement precision through electrical signal evaluation.
Solution Approach 2:
The patent creates a virtual model of the rotor position by evaluating the local inductance matrix characteristics, which are inherently coupled to the rotor position. This virtual copying approach provides accurate position information without physical contact or additional sensors.
4Stability of the object's composition
If the complete local inductance matrix is used for rotor position determination, then the stability is improved, but the device complexity increases
Solution Approach 1:
The patent systematically evaluates all three parameters of the local inductance matrix (Laa, Lbb, Lab) rather than using simplified assumptions. This comprehensive parameter evaluation improves stability while maintaining computational feasibility through organized processing of each matrix element.
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
This approach provides stable and noise-immune rotor position identification across all operating points, improving the reliability and efficiency of three-phase machine control systems without the need for rotary position encoders.
Implementation Method 1
the rotor position or the rotor angle being derived from the rotor position dependency of the differential, respectively local inductances
Data Source
AI summary
In a method for determining the rotor position of a three-phase machine without using a rotary encoder, and to a device for controlling a three-phase motor without using a rotary encoder, the three-phase machine is fed by a converter that can be operated by pulse-width modulation, and the converter has model variables for the rotor angle and the current indicator of the three-phase machine, and the converter has device(s) by using which, in control operation, at least two values are measured which represent a measure of the local inductances of the machine which represent a measure of the local inductances of the machine, the error of the model rotor angle is determined in that, depending on the model rotor angle and the model current indicator, at least two weighting factors are determined, and in that a weighted sum is formed from the at least two measured values and the at least two weighting factors, and in that a further offset value is substracted from the sum, which is likewise determined on the basis of the model rotor angle and the model current indicator.