Sensorless Rotary Machine Flux Control for Torque Ripple Compensation
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Solution Overview
Problem
Existing rotary machine control devices face limitations in effectively reducing torque ripple in synchronous rotary machines, particularly in position sensorless magnetic flux control, as current methods do not adequately account for harmonic components and magnetization characteristics.
Innovation Solution
A rotary machine control device that includes a magnetic flux estimator, command amplitude generator, magnetization characteristics determiner, ripple compensation determiner, and command phase determiner, using a dm-qm coordinate system to determine the magnet phase, qm-axis magnetic flux, and harmonic components, and generating a command magnetic flux vector phase based on ripple compensation and torque commands to reduce torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If position sensorless magnetic flux control is used to drive synchronous rotary machine, then control simplicity is improved, but torque ripple is increased
Solution Approach 1:
The control device calculates a ripple compensation torque in advance based on the qm-axis current and harmonic component of magnet phase, then applies this compensation torque to the command torque to counteract the torque ripple before it occurs. This preliminary compensation action effectively reduces torque ripple while maintaining the simplicity of position sensorless control.
2Object-generated harmful factors
If conventional torque ripple reduction methods are applied, then torque ripple is reduced, but control complexity is increased
Solution Approach 1:
The invention introduces a dm-qm coordinate system transformation that rotates based on the magnet phase angle, allowing the extraction of qm-axis current and harmonic components. By changing the coordinate system parameters and using the relationship between qm-axis current and ripple torque, the system achieves torque ripple reduction through parameter analysis rather than complex structural modifications.
Solution Approach 2:
The control device continuously monitors the qm-axis current and harmonic component of magnet phase, calculates the ripple compensation torque in real-time, and feeds this compensation back to the torque command. This feedback mechanism dynamically adjusts for torque ripple without requiring complex additional hardware or sensors.
3Object-generated harmful factors
If harmonic components are considered in control, then torque ripple reduction is improved, but calculation complexity is increased
Solution Approach 1:
By transforming to the dm-qm coordinate system that rotates with the magnet phase, the invention simplifies the extraction of harmonic components. The qm-axis current in this rotating coordinate system directly correlates with the ripple torque, allowing harmonic analysis through standard coordinate transformation rather than complex spectral analysis.
Data Source
AI summary
A rotary machine control device includes: a magnetization characteristics determiner that determines a magnet phase of a magnet flux based on an estimated magnetic flux and a detection current, and determines a qm-axis magnetic flux of the estimated magnetic flux, a qm-axis current of the detection current, and a harmonic component of a magnet phase using a dm-qm coordinate system with a dm axis representing the magnet phase and a qm axis representing a phase shifted by 90 degrees from the magnet phase; a ripple compensation determiner that determines a ripple compensation phase using a ripple compensation torque obtained based on the qm-axis current and the harmonic component; a command phase determiner that determines a command phase based on the ripple compensation phase and a torque command; and a command magnetic flux generator that generates a command magnetic flux based on a command amplitude and the command phase.