Motor Control Circuit Rapid Braking via Reversed Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In power tools like angle grinders, the motor continues to rotate due to inertia after the operating switch is released, leading to a delay in stopping the sanding or cutting process, which can be unsafe and inefficient.
Innovation Solution
A control circuit for the motor with a driving state and a braking state, including a main control switch, driving branch, braking branch, and control unit, which detects braking parameters and applies a braking current to rapidly stop the motor by disconnecting the stator winding from the rotor when predetermined conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the operating switch is opened to stop the motor, then the power supply is cut off, but the motor continues to rotate due to inertia causing delayed stopping
Solution Approach 1:
The control circuit applies a braking current in the opposite direction to the motor's rotation before the motor naturally stops, creating a counter-torque that actively opposes the inertial motion. This preliminary anti-action prevents the motor from continuing to rotate due to inertia, achieving rapid deceleration and stopping.
Solution Approach 2:
The control circuit utilizes the motor's own electromagnetic properties to generate a braking effect. By reversing the current direction through the stator winding, the system converts the motor's driving capability into a braking force, transforming the potential harm of continued rotation into a beneficial stopping mechanism.
2Loss of time
If a braking current is applied to stop the motor quickly, then the stopping time is reduced, but the control circuit complexity increases
Solution Approach 1:
The control circuit uses the same stator winding for both driving the motor during operation and generating braking torque during stopping. The switching mechanism repurposes the existing motor components for dual functions, avoiding the need for separate braking components and reducing overall system complexity despite the added control logic.
Solution Approach 2:
The motor's own electromagnetic field and stator winding are utilized to generate the braking force, rather than requiring an external braking mechanism. The system serves itself by using its inherent properties to achieve rapid stopping, minimizing the need for additional hardware.
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 control circuit effectively stops the motor rotation quickly, enhancing safety and efficiency by rapidly reducing the rotational speed of the rotor, thus preventing continued operation after the switch is released.
Implementation Method 1
the braking branch includes a branch formed by the stator winding, a braking switch, and an electrical energy storage component. The electrical energy storage component is configured to provide an electrical energy to the braking branch
Data Source
AI summary
A control circuit for a motor has a driving state and a braking state and includes a driving branch and a braking branch. The driving branch includes a branch formed by a stator winding and a rotor. The braking branch includes a branch formed by the stator winding, a braking switch, and an electrical energy storage component. The electrical energy storage component is configured to provide an electrical energy to the braking branch. When the motor is in the braking state, if the braking branch is detected as short-circuited, the connection between the stator winding and the rotor of the driving branch is turned on. Further provided is a power tool including the above control circuit.