Power Tool Electronic Braking With Back-EMF Regeneration
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Solution Overview
Problem
Existing power tools with motors lack efficient electronic braking mechanisms, leading to slow motor stoppage and inefficient energy regeneration, which affects performance and battery life.
Innovation Solution
A power tool system incorporating a three-phase DC motor, a power switching network with high and low side electronic switches, and an electronic processor that controls the switching network to store back-electromagnetic force and regenerate current to the power source, enabling efficient braking and energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional motor control is used without electronic braking, then the motor stops slowly, but the system remains simple
Solution Approach 1:
The patent replaces traditional mechanical braking systems with an electronic braking mechanism that uses the motor's own back-electromagnetic force and regenerative current to achieve rapid stopping. The electronic processor controls power switching networks to redirect motor current back to the power source, eliminating the need for separate mechanical brakes while achieving faster stoppage.
Solution Approach 2:
The motor serves its own braking function by utilizing its inherent back-electromagnetic force and generated current to stop itself. The electronic braking system recovers energy from the motor's own operation during deceleration, converting the motor into a generator that feeds energy back to the power source while providing the braking force.
2Duration of action of moving object
If regenerative braking is implemented, then energy is recovered to extend battery life, but the system complexity increases
Solution Approach 1:
The power switching network performs multiple functions: it controls motor operation during normal operation and redirects current for regenerative braking during stopping. The same electronic switches and control circuitry serve both motor drive and energy recovery functions, minimizing additional complexity while achieving dual benefits of motor control and battery extension.
Solution Approach 2:
Instead of dissipating the motor's generated current as heat during braking, the system recovers this energy and feeds it back to the power source. The electronic processor detects braking conditions and activates the power switching network to capture and store the regenerative current in the battery, converting waste energy into useful charge.
3Loss of energy
If electronic braking with regenerative current is used, then energy efficiency improves, but the control system becomes more complex
Solution Approach 1:
The electronic processor continuously monitors motor operation and detects when braking conditions occur. Based on feedback from current sensors and motor performance data, the processor dynamically adjusts the power switching network to optimize energy recovery. This closed-loop control maximizes regenerative efficiency while adapting to varying operational conditions.
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 provides faster motor stoppage and extends battery life by effectively utilizing regenerative braking, improving the overall performance and efficiency of power tools.
Implementation Method 1
activating the first low side electronic switch and a second low side electronic switch for a first predetermined time in response to receiving the indication to stop the motor such that a back-electromagnetic force generated by the motor is stored in the first phase of the motor
Data Source
AI summary
A power tool includes a three-phase DC motor, a power switching network, a power source, and an electronic processor. A first phase of the motor is connected between a first low side electronic switch and a power source electronic switch, and connected to the power source via a first high side electronic switch in parallel with a diode. The electronic processor is configured to receive an indication to stop the motor during operation of the motor and activate the first low side electronic switch and a second low side electronic switch for a first predetermined time responsive to receiving the indication such that a back-electromagnetic force generated by the motor is stored in the first phase. The electronic processor is configured to deactivate the second low side electronic switch after the first predetermined time such that a first regenerative current is provided to the power source via the diode.