Surgical Handpiece BLDC Startup Control for Smooth Autoclave Use
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Solution Overview
Problem
Conventional motorized surgical tools face challenges with weight, sterilization compatibility, pin count reduction, smooth motor starting, and battery voltage monitoring, which affect maneuverability, reliability, and user notification during surgical procedures.
Innovation Solution
A lightweight, autoclave-tolerant power unit with a single high-temperature battery, reduced pin count, and advanced motor control methods, including a boost converter and sensorless starting algorithms, to ensure reliable operation and user notification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple lithium ion cell battery packs are used to provide needed motor power, then the power output is sufficient, but the weight increases greatly making it difficult to hold and maneuver
Solution Approach 1:
The battery pack is divided into multiple individual lithium ion cells (e.g., five 18650 cells) that can be arranged in series/parallel configurations to achieve the required power output. This segmentation allows for optimized power distribution while maintaining a manageable weight and form factor compared to a single large battery pack.
2Reliability
If conventional battery packs are placed in autoclave for sterilization, then sterilization is achieved, but the battery pack is damaged due to high temperature and pressure cycles
Solution Approach 1:
A hermetically sealed enclosure acts as an intermediary protective barrier between the autoclave environment and the battery cells. This enclosure withstands the high temperature and pressure cycles of autoclave sterilization while protecting the sensitive battery chemistry inside, allowing the battery pack to meet medical sterilization protocols without damage.
3Reliability
If multiple pins are used to provide electrical connection in handheld surgical devices, then electrical connectivity is achieved, but the number of potential leak paths for high pressure steam increases
Solution Approach 1:
Multiple electrical connection functions are merged into a single hermetically sealed connector assembly. This integration reduces the number of discrete pin interfaces that could potentially leak steam, while maintaining all necessary electrical connections through the sealed barrier.
4Speed
If conventional starting sequence is applied to motor, then the motor starts operation, but rough starting causes jerking motion of the tool and tool bit
Solution Approach 1:
The motor starting sequence is made dynamic and adaptive rather than fixed. The controller monitors motor current, back-EMF, and load conditions in real-time, adjusting the commutation timing and voltage application dynamically during startup. This dynamic control smooths the acceleration profile and eliminates jerking motions, making the tool easier to maneuver during initiation.
5Loss of information
If visual warning indicator such as fuel gauge or flashing LED is used to notify low battery, then user is alerted, but the indicator may be obscured due to holding position or surgeon concentration
Solution Approach 1:
A pneumatic or acoustic alert mechanism is implemented that uses sound waves or pressure signals to notify the user of low battery status. This auditory/tactile notification method bypasses the limitation of visual indicators that can be obscured, ensuring the surgeon is alerted regardless of hand position or visual attention.
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
The solution enhances the reliability and maneuverability of surgical tools by reducing weight and improving sterilization resistance, ensuring smooth motor starting, and providing effective battery voltage monitoring, thus improving surgical precision and safety.
Implementation Method 1
One of the advantages of lithium technology batteries is that they maintain their voltage much better, until the last few percent of remaining charge.
Implementation Method 2
The maximum speed of a motor is determined by the voltage applied across its terminals.
Data Source
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AI summary
The invention relates to a method for starting a brushless direct current motor.