Synchronous Motor Speed Command Correction for Torque Ripple
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Solution Overview
Problem
Existing synchronous motor control technologies fail to effectively suppress ripple in vibration torque and output torque, which leads to inefficiencies and increased current peaks, particularly when dealing with periodic loads.
Innovation Solution
A speed command correction device that adjusts the rotational speed command by matching primary magnetic flux components with a command value, using a combination of subtraction, addition, and Fourier series proportional integral control to extract and correct n-th order components of rotational and torque angles, thereby reducing vibration and output torque ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional synchronous motor control is used, then the motor can operate, but vibration torque and output torque ripples occur leading to inefficiency and increased current peaks
Solution Approach 1:
The patent extracts the n-th order periodic components from the torque ripple using Fourier series analysis. By identifying and separating these specific frequency components from the total torque signal, the system can针对性地 suppress them through speed command correction, thereby reducing vibration and improving efficiency without affecting other operational characteristics
Solution Approach 2:
The patent changes the rotational speed parameter by introducing a correction amount that compensates for the extracted torque ripple components. By dynamically adjusting the speed command based on the identified periodic components, the system eliminates torque ripples while maintaining overall motor performance and efficiency
2Object-generated harmful factors
If torque control is applied to suppress vibration, then vibration torque can be reduced, but peak current values increase
Solution Approach 1:
The patent applies periodic correction to the speed command based on the identified n-th order components of torque ripple. By using Fourier series to represent the periodic nature of the vibration and applying corresponding periodic corrections, the system suppresses vibration torque through natural cancellation rather than forceful opposition, avoiding current peaks
Solution Approach 2:
The patent implements a feedback mechanism where the torque ripple components are continuously identified through Fourier analysis and used to generate corrective speed commands. This closed-loop approach ensures that vibration suppression is achieved through precise, adaptive adjustments rather than aggressive current control, thereby avoiding increased peak currents
Data Source
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AI summary
Ripple of vibration torque and/or output torque is reduced by correcting a rotational speed command while reflecting the periodicity of load torque. A subtractor 109 subtracts an angular speed correction amount Δωe* from a rotational speed command ωeo* to obtain a corrected rotational speed command ωe*. An adder 107 adds a second-axis current correction value Δiγc1 to a γc-axis current iγc to obtain a corrected second-axis current iγc1. An angular ripple extraction unit 105a obtains, from a rotational angle θm on a mechanical angle of a synchronous motor 3, a rotational angle difference Δθm being a ripple component of the rotational angle θm. An nth-order component extraction unit 105b extracts nth-order components Δθms(n) and Δθmc(n) of a fundamental frequency of the rotational angle θm from the rotational angle difference Δθm. A torque conversion unit 105i obtains nth-order components τvs(n) and τvc(n) of an estimated value of vibration torque τv. A correction amount calculation unit 105h obtains the second-axis current correction value Δiγc1 using the nth-order components τvs(n) and τvc(n).