Adaptive Drive System Using Stator Current for Resonance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mass-produced personal care appliances, such as power toothbrushes, face challenges in efficiently maintaining the desired amplitude of motion due to the high cost and complexity of frequency matching and amplitude measurement, often resulting in resonance being designed away to simplify manufacturing and reduce costs.
Innovation Solution
A system within the appliance uses a circuit to measure average electrical current through the stator, correlating it with amplitude and frequency responses to adjust the operating frequency, allowing for efficient operation without sensors or separate equipment, both during manufacturing and throughout the appliance's life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resonant drive systems are used to produce reciprocating motion, then efficiency is improved, but frequency matching complexity increases
Solution Approach 1:
The system uses the stator's own current consumption as a feedback signal to automatically tune the drive frequency. The microprocessor monitors the stator current and adjusts the frequency to maximize current draw, which corresponds to resonant operation, eliminating the need for external sensors or complex tuning mechanisms.
Solution Approach 2:
The system implements feedback by continuously monitoring the stator current and using it to adjust the drive frequency. The microprocessor modifies the frequency based on current measurements to maintain resonant conditions, creating a closed-loop control system that automatically adapts to changing conditions.
2Use of energy by moving object
If sensors are used to adapt operation to actual use conditions, then operating efficiency is maintained, but cost and packaging difficulty increase
Solution Approach 1:
The stator serves a dual function: as the electromagnetic actuator and as the sensing element. By monitoring the current drawn by the stator, the system obtains feedback about resonant conditions without requiring separate sensors, thereby eliminating packaging difficulties associated with sensor integration.
Solution Approach 2:
The stator is designed to perform multiple functions: generating the magnetic field for drive operation and simultaneously serving as the sensing element for frequency tuning. This multi-functionality eliminates the need for separate sensors and reduces overall system complexity.
3Use of energy by moving object
If frequency tuning is performed after manufacture, then resonant operation is achieved, but production time and cost increase
Solution Approach 1:
The system performs frequency tuning automatically during the first operational cycle or initialization phase, before normal production proceeds. The microprocessor executes a tuning routine that adjusts the frequency to match the resonant conditions, accomplishing what would otherwise require manual intervention during assembly.
4Ease of manufacture
If resonance is designed away from the system, then manufacturing simplicity is improved, but operating efficiency decreases
Solution Approach 1:
The system transitions from a static, fixed-frequency design to a dynamic, adaptive design where the drive frequency automatically adjusts to maintain resonant conditions. The microprocessor continuously monitors stator current and modifies the frequency in real-time to optimize performance, enabling the system to operate at resonance without requiring precision-manufactured fixed-frequency components.
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 approach enables efficient operation by maintaining the desired amplitude of motion while reducing costs and complexity, allowing for continuous adjustment to compensate for wear and varying loads, ensuring optimal performance without the need for expensive sensors or control systems.
Implementation Method 1
a circuit for measuring an average electrical current through the stator member
Implementation Method 2
resonant drive systems, such as those used for driving a workpiece portion of an appliance, for example, a power toothbrush, are highly efficient in producing a reciprocating motion
Data Source
AI summary
An adaptive system for a personal care appliance, such as a power toothbrush, having a workpiece which is driven through an amplitude of motion by a drive mechanism which includes a stator member includes a circuit (13) for measuring average electrical current through the stator member and stored information (19) in the personal care appliance which relates the average current values through the stator during operation of the device to corresponding amplitude of motion of the workpiece. A processor (17) utilizing a stored program adjusts the operating frequency to produce a stator current value which correlates to the desired amplitude of motion of the workpiece.