Two-Phase Synchronous Motor Current Waveform for Torque Ripple Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Two-phase synchronous motors, particularly small-scale hybrid type stepping motors, experience rotational vibrations and stop angle errors due to fluctuations in reluctance torque and magnet torque, which conventional methods have not adequately addressed.
Innovation Solution
A motor control device that generates a control current waveform by superposing a fundamental sinusoidal wave with reluctance torque and magnet torque correction waveforms to stabilize the torque fluctuations, allowing for open-loop constant current control without position or speed feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sinusoidal current is used for driving the two-phase synchronous motor, then the motor operates smoothly under normal conditions, but rotational vibrations occur when the rotation speed corresponds to eigenfrequency conditions (one half or one fourth the eigenfrequency)
Solution Approach 1:
The invention applies preliminary anti-action by generating a corrective current waveform that produces a torque component opposing the fluctuating reluctance torque before the vibration occurs. The corrective waveform is designed to cancel the harmful torque fluctuation at its source, preventing the vibration from developing rather than reacting to it after occurrence.
Solution Approach 2:
The invention changes the parameter of the drive current waveform from a simple sinusoidal wave to a composite waveform that includes additional harmonic components. By modifying the current waveform parameters (adding the corrective component with specific frequency and phase), the motor operates smoothly across a broader speed range without experiencing vibrations at eigenfrequency conditions.
2Reliability
If constant current excitation is used to stop the motor, then the motor can be held in position, but the stop position deviates from the theoretical stop position (stop angle error)
Solution Approach 1:
The invention applies preliminary action by adjusting the current waveform before the motor reaches the stop position. The corrective current waveform is applied during the deceleration phase to compensate for the anticipated stop angle error, ensuring the motor stops at the theoretically correct position rather than allowing the error to accumulate.
3Device complexity
If conventional control methods are used, then the control system remains simple, but the methods fail to adequately suppress vibrations and reduce stop angle errors in small-scale hybrid type stepping motors
Solution Approach 1:
The invention applies self-service by generating the corrective current waveform through calculation based on motor parameters (inductance, resistance, pole pairs) that are inherently known or can be easily measured. The system uses its own existing data to create the compensation waveform without requiring external sensors or complex feedback systems, maintaining simplicity while achieving vibration suppression.
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3A~3B
AI summary
A motor control device is provided, which drives a two-phase synchronous motor. The motor control device includes: control current waveform generating means which generates a control current waveform by superposing a fundamental sinusoidal wave and a reluctance torque correction waveform that suppresses the fluctuation of the reluctance torque of the two-phase synchronous motor; and current control signal generating means which generates a current control signal for supplying a current to the windings of the two-phase synchronous motor according to the control current waveform generated by the control current waveform generating means. The reluctance torque correction waveform may have a waveform profile such that an original waveform having a frequency twice that of the fundamental sinusoidal wave and having a phase matched with that of the fundamental sinusoidal wave is full-wave-rectified to the same sign as or a different sign from that of the fundamental sinusoidal wave.