Oscillating Motor Frequency Control for Resonant Blade Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing oscillating motor systems, such as those used in electric hair cutting devices, face inefficiencies when the mechanical resonant frequency of the motor and load changes over time, often requiring manual adjustment or service center intervention.
Innovation Solution
A control system that measures the mechanical resonant frequency of the motor and load when power is off, stores this frequency for future use, and automatically adjusts the power supply frequency to match the mechanical resonant frequency, ensuring efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power supply frequency is fixed at factory settings, then the initial operation efficiency is adequate, but the efficiency decreases when mechanical resonant frequency changes over time
Solution Approach 1:
The control system continuously monitors the mechanical resonant frequency of the motor-load system and automatically adjusts the power supply frequency to match the detected resonant frequency, creating a closed-loop feedback mechanism that maintains optimal operation efficiency despite changes in blades or mechanical conditions
Solution Approach 2:
The system transitions from a static fixed frequency approach to a dynamic frequency adjustment approach, where the power supply frequency automatically adapts in real-time to match the changing mechanical resonant frequency of the system
2Productivity
If manual adjustment of driving frequency is implemented, then frequency matching can be improved, but service center intervention is required
Solution Approach 1:
The control system performs self-adjustment by automatically detecting the mechanical resonant frequency and adjusting the power supply frequency without requiring any manual intervention or service center involvement, enabling the device to maintain optimal performance independently
3Adaptability or versatility
If automatic frequency adjustment is added, then adaptability to resonant frequency changes is improved, but device complexity increases
Solution Approach 1:
The controller performs multiple functions including operating the H-bridge power supply, detecting mechanical resonant frequency through signal analysis, and automatically adjusting the driving frequency, consolidating these functions into a single multi-functional control unit rather than requiring separate dedicated components for each function
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
This solution maintains efficient operation of oscillating motors by automatically adjusting the power supply frequency to match the mechanical resonant frequency, reducing the need for manual intervention and enhancing motor performance.
Implementation Method 1
The motor drives a load. In a vibratory hair clipper, for example, the armature in a pivot motor moves a cutting blade (the load) in a reciprocal fashion by oscillating the armature back and forth. The armature reciprocates with a slight arc. The combination of the motor, spring system and cutting blade have a mechanical resonant frequency.
Implementation Method 2
The power supply can be an H-bridge supplied with pulse width modulated (PWM) signals from a controller. The H-bridge converts direct current from a battery to an alternating current having a predetermined frequency when power is provided to the motor.
Implementation Method 3
The pivot motor has a stator with a plurality of laminations, and a bobbin located in operational relation to the stator. The bobbin has a coil of wire wound around the bobbin. A power supply provides alternating current to the coil, which causes the armature to oscillate at or near the frequency of the alternating current.
Data Source
AI summary
Some electric hair cutting devices have a stationary blade, a reciprocating blade, and an oscillating motor. Oscillating motors include pivot motors and linear motors. Both motors have a stator, an armature and at least one spring. The armature drives a load such as the reciprocating blade. The armature, the spring and the load have a mechanical resonant frequency. An H-bridge is supplied with pulse width modulated (PWM) signals from a controller and converts direct current from a battery to alternating current having the frequency of the PWM signals. The controller measures the mechanical resonant frequency when power to the motor is turned off and the armature continues to oscillate due to stored energy. The controller adjusts the frequency of the PWM signals to the measured mechanical resonant frequency and stores it in a memory for use the next time the motor is turned on.