Electric Machine Torque Control via Magnetic Flux Polynomial Approximation
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Solution Overview
Problem
Existing methods for controlling electric machines, such as permanently excited synchronous motors, face inefficiencies due to the separate consideration and compensation of magnetic saturation effects and winding inductance reduction, leading to complex parameterization and algorithmic challenges.
Innovation Solution
The method involves using the magnetic flux generated by the stator current as a controlled variable to efficiently manage torque, employing a polynomial approximation to calculate magnetic flux, thereby simplifying calculations and control, and reducing the need for multiple tables and complex algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic saturation effects and winding inductance reduction are considered separately with multiple tables and complex algorithms, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the separate considerations of magnetic saturation effects and winding inductance reduction into a unified control approach. By using a single table storing torque values as a function of stator current and saturation factor, and calculating magnetic flux through a unified polynomial approximation, the method integrates multiple compensation functions into one coherent system, thereby reducing device complexity while maintaining control precision.
Solution Approach 2:
The control method achieves multi-functionality by using the magnetic flux calculation as a universal basis for both torque control and saturation compensation. The same polynomial approximation and flux values serve multiple purposes: determining torque, compensating for saturation effects, and accounting for inductance reduction, eliminating the need for separate specialized algorithms for each function.
2Measurement precision
If separate compensation methods for magnetic saturation and inductance reduction are used, then control accuracy is improved, but processor load increases
Solution Approach 1:
The patent merges separate compensation calculations into a unified process where magnetic flux is calculated once using polynomial approximation based on stator current and saturation factor. This single flux calculation serves multiple control purposes simultaneously, eliminating redundant computations and reducing processor load while maintaining control accuracy.
Solution Approach 2:
The method introduces a saturation factor as an additional parameter that modifies the relationship between stator current and magnetic flux. By changing the parameter set to include saturation factor alongside current, the system achieves more accurate control through polynomial approximation without requiring multiple separate compensation calculations, thereby reducing computational burden.
3Measurement precision
If multiple tables are stored for saturation compensation and inductance compensation, then control precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent consolidates multiple compensation tables into a single table that stores torque values as a function of stator current and saturation factor. This unified table structure simplifies the control operation by eliminating the need to query and coordinate multiple separate tables, making the control system easier to operate while maintaining precision through the comprehensive data it contains.
Solution Approach 2:
The single stored table serves multiple functions simultaneously: it provides torque information, saturation compensation data, and inductance compensation references. This multi-functional table eliminates the need for operators to manage multiple specialized tables, significantly improving ease of operation while preserving control precision through its comprehensive information content.
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 allows for more efficient operation of electric machines by directly addressing magnetic saturation effects, reducing processor load, and simplifying parameterization, resulting in improved control loop stability and efficiency.
Implementation Method 1
The effects of the magnetic saturation due the stator current are efficiently taken into consideration
Implementation Method 2
the Lorentz force, or rather the law of induction
Data Source
AI summary
A method for operating an electric machine comprises ascertaining an electric stator current of the electric machine, calculating a magnetic flux which is generated based on the ascertained electric stator current, and controlling a torque generated by means of the electric machine, as a function of the calculated magnetic flux.