Dynamic Duty Cycle Control for Battery Toothbrush Motor Performance
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Solution Overview
Problem
Electric toothbrushes powered by replaceable or rechargeable batteries experience performance degradation due to declining battery voltage, leading to suboptimal operation before the batteries are completely depleted, resulting in undesirable performance fluctuations.
Innovation Solution
A system that measures battery voltage and motor current to adjust the drive signal's duty cycle, pulse width, or frequency, maintaining performance by compensating for voltage drops and ensuring the toothbrush operates effectively until battery replacement is necessary, with adjustments made during the appliance's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the toothbrush operates continuously with a fixed duty cycle, then the initial brushing performance is optimal, but the performance degrades as battery voltage declines
Solution Approach 1:
The duty cycle is made dynamic rather than fixed, allowing it to be adjusted in multiple steps during battery discharge. The control system monitors battery voltage and progressively increases the duty cycle from an initial low value to a final high value, enabling the motor to maintain consistent brushing performance throughout the entire battery lifespan despite voltage degradation.
Solution Approach 2:
The system changes the duty cycle parameter in response to battery voltage changes. By monitoring voltage levels and adjusting the duty cycle accordingly, the system compensates for battery degradation and maintains optimal motor performance throughout the battery's operational life, extending the effective usage duration.
2Power
If the duty cycle is increased to maintain performance, then power output is maintained, but energy consumption increases
Solution Approach 1:
The duty cycle is dynamically adjusted based on real-time battery voltage monitoring. The system starts with a low duty cycle when battery voltage is high and progressively increases it as voltage declines, maintaining consistent motor power output while minimizing overall energy consumption by using the lower duty cycle for longer periods during the battery's life.
3Power
If the toothbrush operates at full power from the beginning, then initial performance is optimal, but the effective operational duration is reduced
Solution Approach 1:
The system is pre-programmed with a multi-step duty cycle schedule that is automatically executed based on battery voltage levels. This preliminary configuration allows the toothbrush to start at lower power consumption settings and progressively increase power output, effectively extending the total operational duration while ensuring full power is available when needed.
Solution Approach 2:
The duty cycle is adjusted in periodic steps as the battery discharges. Instead of operating at constant full power, the system uses periodic adjustments to the duty cycle, increasing power output in controlled increments as battery voltage declines, thereby extending the effective operational lifespan while maintaining adequate performance throughout.
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 extends the number of brushings with consistent performance, reducing battery costs and maintaining effective operation until battery replacement is needed, with adjustments potentially increasing efficiency by 10-20 additional brushings.
Implementation Method 1
the current value in a stator portion of the motor for the electric toothbrush from which current value the corresponding amplitude of movement of the workpiece of the toothbrush is then obtained
Implementation Method 2
the electric toothbrush is driven by a resonant system
Data Source
Figure 1~2B
Figure 2C~3
AI summary
The system periodically measures the battery voltage of the toothbrush and the current in a stator portion of the motor for the appliance. The amplitude of movement of the toothbrush workpiece is determined from the measured stator current. A circuit/control program changes the duty cycle or pulse width of the drive signal from the motor if the battery voltage drops below a first threshold value and a circuit or control program changes the drive frequency of the appliance if the amplitude of the workpiece movement falls below a first threshold value. A circuit/control program terminates the operation of the toothbrush if the voltage drops below a second threshold value or if the amplitude drops below a second threshold value, both of which are less than the respective first thresholds.