Torque Ripple Compensation in PMSM Motor Control
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Solution Overview
Problem
Permanent magnet synchronous machines (PMSM) experience torque ripple due to non-sinusoidal back-EMF distribution and phase imbalances, leading to noise, vibration, and harshness (NVH) issues that degrade beyond desirable thresholds, making them uncomfortable and potentially inoperable, and causing structural damage.
Innovation Solution
A motor control system with a current regulator that generates voltage commands using transformation matrices to compensate for torque ripple by decoupling base current regulation from voltage generation, providing zero steady-state tracking of pulsating currents and d/q axis current control loop decoupling for optimal torque ripple compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If complex electric drive components are introduced to optimize cost, then cost is reduced, but NVH characteristics degrade and exceed desirable thresholds
Solution Approach 1:
The patent converts the harmful torque ripple into a beneficial control signal by measuring it and injecting an equal and opposite compensating torque through the current regulator, thereby eliminating the harmful NVH effects while maintaining the cost-optimized complex electric drive configuration
2Device complexity
If standard current regulation is used in PMSM, then control is simplified, but torque ripple is produced due to non-sinusoidal back-EMF and phase imbalances
Solution Approach 1:
The patent segments the current regulation into two independent parts: a base current regulator for average current control and a compensator for torque ripple compensation. This segmentation allows each component to be optimized for its specific function, reducing overall torque ripple while maintaining manageable control complexity
Solution Approach 2:
The patent introduces a compensator as an intermediary component between the base current regulator and the power converter. This compensator processes the torque ripple measurement and generates compensating current commands, acting as a mediator that eliminates torque ripple without requiring complete redesign of the entire control system
3Object-affected harmful factors
If torque ripple compensation is added to the control system, then NVH performance is improved, but control system complexity increases
Solution Approach 1:
The patent merges the torque ripple compensator with the existing base current regulator into a unified control structure. The compensator uses the same transformation matrices and current regulator framework, combining multiple functions into an integrated system that improves NVH performance without proportionally increasing complexity
Data Source
AI summary
According to one or more embodiments, a motor control system that provides torque ripple compensation includes a current regulator that receives a first current command corresponding to an input torque command. The current regulator further generates a first voltage command based on the first current command using a first transformation matrix. The current regulator further receives a second current command corresponding to a torque ripple to be compensated. The current regulator further generates a second voltage command based on the second current command using a second transformation matrix. The current regulator further computes a final voltage command using the first voltage command and the second current command, the final voltage command being applied to a motor.