Stepping Motor Control Device for Vibration Suppression
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Solution Overview
Problem
Existing stepping motor control methods fail to adequately suppress vibration and impact sounds during the driving period, despite efforts to manage these noises during activation and stop periods.
Innovation Solution
A control device and method that gradually adjusts the excitation current in stepping motors using pulse width modulation, ensuring the current variation per unit time is within a predetermined threshold, allowing for smooth rotor movement to predetermined positions during both activation and stop periods, thereby reducing noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hold current is applied to attract the rotor to the initial position during activation period, then the stepping motor can be surely activated and hunting is prevented, but vibration sound and impact sound are generated
Solution Approach 1:
The control device performs preliminary action by gradually increasing the hold current during a hold period before normal driving. This preliminary current increase prepares the rotor for smooth movement to the initial position, preventing sudden jumps that cause vibration and impact sounds while ensuring reliable activation
Solution Approach 2:
The invention applies dynamics by making the hold current variable rather than constant. The hold current is gradually increased from zero to the target value during the hold period, creating a dynamic transition that suppresses mechanical shocks and vibrations during rotor positioning
2Speed
If the excitation current is suddenly changed during stop period, then the rotor can quickly reach the stop position, but vibration sound and impact sound are generated
Solution Approach 1:
The control device performs preliminary action by gradually decreasing the hold current during a hold period before the rotor reaches the stop position. This gradual current reduction prepares the system for smooth stopping, preventing sudden mechanical impacts while maintaining adequate positioning speed
Solution Approach 2:
The invention applies dynamics by making the hold current variable during the stop period. The current is gradually decreased from the holding value to zero during the hold period, creating a dynamic transition that suppresses vibration and impact sounds during rotor stopping
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively suppresses vibration and impact sounds by ensuring the rotor moves to positions at controlled speeds, maintaining noise levels below predetermined limits during both driving and stopping phases.
Implementation Method 1
A stepping motor is excited by applying an excitation current to multiple coils, whereby a rotor is driven to rotate in steps
Implementation Method 2
a drive voltage subjected to pulse width modulation such that a duty ratio thereof decreases as time proceeds
Data Source
AI summary
There is provided a control device for a stepping motor, configured to apply an excitation current to multiple coils to rotate a rotor. The control device includes a drive unit configured to apply a drive voltage to the coils, and a control unit configured to control the drive voltage applied by the drive unit, wherein the control unit includes a stop control unit configured to perform, during a hold period of a stop period of the stepping motor, a stop control which gradually decreases a magnitude of the excitation current flowing in the coils such that the rotor moves to a predetermined stop position, and wherein the stop control unit is configured to perform the stop control such that a variation amount of the excitation current per unit time becomes a predetermined threshold value for the stop period or less.