Motor Current Control Split by AC/DC Components for Torque Ripple
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Solution Overview
Problem
Existing rotating electrical machine control systems face challenges in reducing torque ripple without causing control interference, especially when the torque fluctuates suddenly or continuously, leading to overshoot or oscillation.
Innovation Solution
A rotating electrical machine control system that performs current feedback control using a d-q-axis orthogonal vector coordinate system, with a base current instruction and a correction current instruction, where the correction current instruction is alternating current with a frequency based on the torque ripple, and includes a first current control part for direct current components and a second current control part with a low gain for alternating current components to manage torque ripple reduction without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a correction current instruction is superimposed on the base current instruction to reduce torque ripple, then torque ripple is reduced, but control interference occurs causing overshoot or oscillation when torque fluctuates
Solution Approach 1:
The current control part is divided into a first current control part for direct current components and a second current control part for alternating current components. This segmentation allows independent control strategies for each component type, enabling torque ripple reduction while maintaining stability during torque fluctuations.
Solution Approach 2:
Different gain values are assigned to different control parts: the first current control part has a higher gain for responsive torque control, while the second current control part has a lower gain to prevent oscillation. This local differentiation of control parameters resolves the contradiction between torque ripple reduction and control stability.
2Speed
If the gain of the second current control part is increased to improve responsiveness to correction current, then responsiveness improves, but overshoot and oscillation occur during torque fluctuations
Solution Approach 1:
The gain parameter of the second current control part is specifically set to be lower than that of the first current control part. This parameter adjustment ensures that the alternating current component (correction current) is controlled with sufficient damping to prevent overshoot and oscillation, while still maintaining adequate responsiveness for torque ripple reduction.
Data Source
AI summary
A rotating electrical machine control system includes a base current instruction setting part that sets a base current instruction based on target torque of a rotating electrical machine; a correction current instruction setting part that sets a correction current instruction with a frequency determined based on torque ripple; and a current control part that performs current feedback control to compute a voltage instruction which is an instruction value of a voltage to be applied to the rotating electrical machine. The current control part includes a first current control part whose control target is a component of the base current instruction; and a second current control part whose control target is a component of the correction current instruction. A gain of the second current control part is set to be low compared to a gain of the first current control part.