Motor Control Apparatus Reducing Torque Ripple via In-Phase Noise Cancellation
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Solution Overview
Problem
Conventional motor control apparatuses face challenges in reducing torque ripple, vibration, and noise, especially at high motor speeds, due to in-phase noise and the need for multiple coordinate transformations, which affect current control accuracy and responsiveness.
Innovation Solution
A motor control apparatus for permanent-magnet synchronous motors with three-phase windings, utilizing two inverters, a current detector, and a controller that calculates voltage commands by multiplying the difference between target and actual currents by proportionality constants, adjusting these constants based on the number of systems, and setting self- and mutual inductance parameters to optimize control, thereby reducing noise and maintaining accurate current tracking at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a three-phase-current feedback method is used to reduce calculation load, then the calculation amount is reduced, but in-phase noise is not cancelled causing increased torque ripple, vibration, and noise
Solution Approach 1:
The patent converts the harmful in-phase noise into a beneficial control action by detecting it through the common reference electric potential and actively canceling it through the voltage command calculation, thereby eliminating torque ripple, vibration, and noise while maintaining the efficient three-phase-current feedback method
Solution Approach 2:
The patent introduces feedback by detecting the common reference electric potential (which contains in-phase noise) and using it to adjust the voltage commands, creating a closed-loop control system that actively compensates for noise without increasing calculation load significantly
2Device complexity
If three-phase-current feedback control is used at high motor speeds, then the control system is simple, but the current cannot keep track of the command value due to high frequency
Solution Approach 1:
The patent introduces an intermediary integration operation between the current detection and voltage command calculation, which effectively lowers the frequency of the control signals and enables accurate current tracking at high motor speeds while maintaining a relatively simple control system structure
3Reliability
If multiple coordinate transformations are used for each system, then complete control of two-system motor is achieved, but the calculation load increases
Solution Approach 1:
The patent merges the control of two motor systems by using a common reference electric potential detection and unified voltage command calculation, reducing the number of coordinate transformations needed while maintaining complete control through the shared control infrastructure
Data Source
AI summary
When a voltage application command is outputted to a three-phase winding of one system, a d-axis proportionality constant and a q-axis proportionality constant are set with Ld and Lq, respectively, as parameters; when voltage application commands are outputted to three-phase windings of two systems, a d-axis proportionality constant and a q-axis proportionality constant are set with [Ld+Md] and [Lq+Mq], respectively, as parameters.