Power Tool Motor Braking Using Phase Voltage Thresholds
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Solution Overview
Problem
Existing power tools lack efficient methods for smoothly transitioning from operation to a controlled stop, often resulting in abrupt braking that can be harmful to the tool and user.
Innovation Solution
A power tool system that utilizes a phase voltage-based braking mechanism, where an electronic controller monitors the motor's phase voltage and applies a braking force after the voltage drops below a threshold, allowing the motor to coast initially and then engage braking elements to ensure a controlled stop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional braking methods are used, then the motor stops quickly, but the braking is abrupt causing harm to the tool and user
Solution Approach 1:
The system performs preliminary action by allowing the motor to coast before applying braking force. The controller monitors phase voltage and only engages the braking element after the voltage drops below a threshold, ensuring the motor has already slowed to a safe speed. This preliminary coasting phase prevents abrupt braking harm while maintaining efficient stopping time.
Solution Approach 2:
The braking system transitions from a static on/off control to a dynamic voltage-threshold-based control. The controller continuously monitors phase voltage and adjusts braking engagement based on real-time voltage levels, creating a dynamic response that adapts to the motor's deceleration state. This dynamic approach enables smooth transition from coasting to controlled braking.
2Ease of operation
If voltage threshold control is used, then braking is smoothly controlled, but the control system complexity increases
Solution Approach 1:
The controller implements feedback by continuously monitoring the phase voltage of the motor and comparing it against a predetermined threshold. This feedback mechanism automatically determines when to engage or disengage the braking element based on real-time voltage conditions, providing smooth controlled braking without requiring complex external control systems.
Solution Approach 2:
The braking system uses the motor's own phase voltage as the control signal source. The existing voltage monitoring capability of the controller is leveraged to automatically trigger braking engagement when voltage drops below the threshold, eliminating the need for additional sensors or complex control circuitry. The system essentially services itself using its inherent electrical characteristics.
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 method enables a smooth and controlled braking process, reducing wear on the tool and enhancing user safety by minimizing abrupt stops.
Implementation Method 1
monitor a phase voltage of the motor, determine whether the phase voltage of the motor is equal to or less than a phase voltage threshold
Data Source
AI summary
Braking a power tool motor based on a phase voltage of the motor. The power tool includes a motor and a power source providing operating power to the motor. A power switching network is between the power source and the motor to drive the motor. An actuator is operable to provide an input. An electronic controller is connected to the actuator and the power switching network. The electronic controller is configured to receive an indication related to initiating braking of the motor, control the power switching network to allow the motor to coast, monitor a phase voltage of the motor, determine whether the phase voltage of the motor is equal to or less than a phase voltage threshold, and control, in response to the phase voltage of the motor being equal to or less than the phase voltage threshold, the power switching network to brake the motor.