Rotary Motor Controller Angle Correction Under High-Speed Noise
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Solution Overview
Problem
Existing rotary electric machine controllers face challenges in accurately detecting rotational angles at high speeds due to sensor angle errors, which result in torque ripple and unwanted noise, as the feedback control response frequency needs to increase with rotational speed, leading to a trade-off between noise and error reduction.
Innovation Solution
A controller for rotary electric machines with a stator and rotor, incorporating a rotation detection unit, angle calculation, current detection, voltage command, and switching control units, which calculates rotational angles by feedback control to minimize sensor detection errors through internal deviation ratio adjustments based on rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the response frequency of feedback control is increased to reduce AC component error at high rotational speed, then the accuracy of rotational angle detection is improved, but high frequency noise component from current detection value is superimposed on correction amount
Solution Approach 1:
The patent segments the error correction process into two distinct components: DC component error correction using axial error calculator, and AC component error correction using torque ripple error calculator. This segmentation allows each component to be handled with appropriate filtering strategies, preventing noise superposition while maintaining accuracy.
Solution Approach 2:
The patent introduces an intermediary low-pass filter between the torque ripple error calculation and the correction amount generation. This filter acts as a mediator that allows the AC component error to be corrected while blocking the high frequency noise from the current detection value, thus resolving the contradiction between accuracy and noise.
2Reliability
If the response frequency of feedback control is increased to compensate for AC component error, then torque ripple error is reduced, but the complexity of control system increases
Solution Approach 1:
The control system is segmented into multiple independent error correction paths: one for DC component error and another for AC component error. Each path operates at its own optimal response frequency with appropriate filtering, avoiding the need to increase overall feedback control frequency and thus maintaining system simplicity while improving reliability.
Solution Approach 2:
The patent changes the parameter of response frequency to be different for different error components: a lower response frequency is used for DC component correction while a higher but filtered response frequency is used for AC component correction. This parameter differentiation allows each correction to be optimized independently without increasing overall system complexity.
Data Source
AI summary
To provide a controller for a rotary electric machine and an electric power steering apparatus which can suppress the error increase of the rotational angle due to the high frequency noise component included in the current detection value, while reducing the AC component error included in the sensor detection value of rotational angle, at high rotational speed. A controller for a rotary electric machine estimates an estimation actual angle deviation; calculates a detection angle deviation; calculates a control angle deviation by dividing internally between the estimation actual angle deviation and the detection angle deviation; calculates a rotational angle for control by performing feedback control so that the control angle deviation approaches 0; and makes the ratio of the estimation actual angle deviation higher than the ratio of the detection angle deviation, when the rotational speed is higher than a speed threshold value.