Motor Control Harmonic Compensation for Torque Ripple Reduction
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Solution Overview
Problem
Existing AC motor control systems struggle with undesirable torque ripple due to inherent characteristics, particularly in interior permanent magnet machines, necessitating improved methods to reduce torque variations.
Innovation Solution
A motor control system that identifies harmonics in drive feedback signals, generates torque ripple compensation signals, and applies phase shift angles to carrier signals for multiple windings to minimize torque ripple, using d-q reference frame control and harmonic cancellation commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If AC motor control systems use discrete magnet placement in interior permanent magnet machines, then the motor structure is simplified and manufacturing is easier, but torque ripple increases due to inherent harmonic characteristics
Solution Approach 1:
The patent identifies harmonic components in the drive feedback signals and generates compensation signals that convert these harmful harmonics into beneficial corrections. By injecting compensation currents that are specifically designed to counteract the identified harmonics, the system transforms the problematic torque ripple caused by discrete magnet placement into a controlled parameter that can be actively compensated, thereby maintaining the simplified motor structure while reducing torque ripple.
Solution Approach 2:
The patent implements a feedback mechanism where drive feedback signals are continuously monitored to identify harmonic components. The identified harmonics are used to generate compensation signals that are fed back into the motor control system. This closed-loop feedback approach enables real-time detection and correction of torque ripple, allowing the system to maintain optimal performance despite the inherent limitations of discrete magnet placement.
2Ease of operation
If AC motor control systems attempt to provide balanced sinusoidal drive currents, then the control system operation is simplified, but torque ripple cannot be effectively reduced due to inherent motor characteristics
Solution Approach 1:
The patent performs preliminary action by identifying harmonic components in the drive feedback signals before they cause significant torque ripple. Compensation signals are generated in advance based on the identified harmonics and are injected into the control system proactively. This preliminary compensation approach allows the system to maintain simplified sinusoidal current control while preemptively counteracting torque ripple effects, rather than reacting after the problem occurs.
3Object-generated harmful factors
If harmonic cancellation commands are generated and applied to compensate for torque ripple, then torque ripple is reduced, but the control system complexity increases
Solution Approach 1:
The patent introduces an intermediary processing stage that analyzes drive feedback signals to identify harmonic components and generates compensation signals. This intermediary layer acts as a mediator between the simple sinusoidal current control and the motor's inherent harmonic characteristics. By placing the complexity in a dedicated harmonic compensation module rather than throughout the entire control system, the patent reduces torque ripple while keeping the overall system architecture manageable and modular.
Data Source
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AI summary
A method for operating a motor control system to dynamically compensate for low-frequency and/or high-frequency torque ripple. Embodiments include receiving an input command, receiving drive feedback signals representative of drive currents in a motor, identifying harmonics in the drive feedback signals representative of motor torque ripple, producing torque ripple compensation signals based on the identified harmonics; and producing motor drive control signals based on the input command, the current feedback signals,the torque ripple compensation signals, and carrier signals with a certain phase shift.