Electric Motor Control Device Non-Linearity Suppression
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Solution Overview
Problem
Existing speed control techniques for electric motors face challenges in managing non-linear relationships between amplitude setting values and drive waveforms, leading to oscillations and prolonged convergence times, especially when the controller design is based on linear assumptions.
Innovation Solution
An electric motor control device that generates a drive waveform, detects rotational phase and speed, and adjusts the phase relationship and amplitude of the waveform to match target speeds, using data correction to minimize non-linearity and maintain control stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If controller parameter design is performed in a linear relationship region, then control is simple and fast convergence is achieved, but control oscillates in non-linear relationship regions
Solution Approach 1:
The patent applies parameter changes by switching between two sets of controller parameters (first parameters for linear relationship region, second parameters for non-linear relationship region) based on the detected relationship type. This allows the controller to adapt its parameters to match the operating conditions, ensuring stable control in non-linear regions while maintaining fast convergence in linear regions.
2Reliability
If controller parameter design is performed in a non-linear relationship region, then control stability is improved in non-linear regions, but convergence time is lengthened in linear relationship regions
Solution Approach 1:
The patent uses parameter changes by selecting different controller parameters based on the relationship region. When operating in linear relationship regions, the controller uses the second parameters designed for non-linear regions, which may result in longer convergence time but ensures stability. When in non-linear regions, the first parameters provide fast convergence and stability.
Solution Approach 2:
The patent implements dynamics by making the controller parameters changeable and adaptable based on real-time detection of the relationship region. The controller dynamically switches between parameter sets according to whether the system is in a linear or non-linear relationship region, optimizing performance for each operating condition.
3Speed
If speed control is achieved by increasing and decreasing amplitude of sine wave voltage waveform, then high speed driving is realized, but non-linearity causes control oscillation and extended convergence time
Solution Approach 1:
The patent applies parameter changes by adjusting both the amplitude and frequency of the drive waveform based on the detected relationship region. When in non-linear regions, the controller modifies parameters to compensate for non-linearity, preventing oscillation and maintaining stability during high-speed driving operations.
Data Source
AI summary
An electric motor control device includes a drive waveform generating unit configured to generate a drive waveform (a sine wave or a pseudo-trapezoidal wave) to an electric motor. A plurality of photo interrupters detect a rotational phase of an electric motor, and a information of rotational speed is detected by an encoder circuit based on a detected signal of the rotational phase of the electric motor. The control unit controls the drive waveform generating unit on the basis of detection information of the rotational phase of the electric motor and performs control so that a phase relationship between the rotational phase of the electric motor and the phase of the drive waveform is kept constant. Furthermore, the control unit sets an amplitude value of the drive waveform generated by the drive waveform generating unit in accordance with a difference between a target speed and the detected information of rotational speed and performs speed control so that a speed of the electric motor is kept constant. The control unit calculates an amplitude setting value with which correction for suppressing non-linearity is performed in a region in which an amplitude setting value of the drive waveform and actual work given to the electric motor is non-linear and controls the speed.