Electric Motor Flux Estimation for High-Frequency Torque Ripple
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Solution Overview
Problem
Existing motor control systems fail to effectively reduce high-frequency torque ripple due to response delays and amplification of noise and vibration, limiting the estimation and correction of interlinkage flux and output torque to sufficiently high frequencies.
Innovation Solution
A controller that estimates interlinkage flux based on current and applied voltage, calculates output torque using current and flux estimation, and extracts pulsation components from torque estimates to directly correct voltage commands, thereby reducing torque ripple without amplifying noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the correction value is fed back to the current command to suppress torque pulsation, then the torque ripple is reduced, but there is a response delay from the current command to the actual current, preventing correction up to sufficiently high frequency
Solution Approach 1:
The patent introduces an applied voltage as an intermediary signal to bypass the slow current feedback loop. By estimating interlinkage flux directly from the applied voltage (which is available without delay) and correcting the voltage command, the system achieves high-frequency torque ripple suppression without the response delay inherent in current-based feedback systems.
2Manufacturing precision
If the estimated torque ripple is fed back as current correction value, then torque pulsation is suppressed, but unnecessary noise and vibration are amplified
Solution Approach 1:
The patent extracts only the pulsation components from the torque estimation by performing Fourier transform and isolating specific frequency components. This extraction process separates the useful torque ripple information from the harmful noise and vibration, allowing selective correction of only the pulsation components while filtering out unnecessary noise.
3Measurement precision
If inverse operation of voltage equation is performed to estimate induced voltage, then torque can be estimated, but differentiation of current superimposes high frequency component that must be reduced by low pass filter, limiting estimation frequency
Solution Approach 1:
Instead of performing the inverse operation (differentiation) to estimate induced voltage from current, the patent inverts the approach by directly using the applied voltage to estimate interlinkage flux through integration. This alternative estimation path avoids the high-frequency noise problem entirely, as integration naturally filters high-frequency components while preserving the ability to estimate torque accurately up to high frequencies.
Data Source
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AI summary
To provide a controller for motor which can reduce a torque ripple up to high frequency, without amplifying unnecessary noise and vibration. A controller for motor estimates an interlinkage flux based on the applied voltage and the detection value of current; estimates an output torque based on the detection value of current and the estimation value of interlinkage flux; extracts a pulsation component from the estimation value of output torque; calculates a voltage command correction value based on the extraction value of pulsation component; calculates a voltage command after superimposing by superimposing the voltage command correction value on the voltage command basic value; and applies voltage to winding based on the voltage command after superimposing.