Power Tool Motor Commutation Control Under Heavy Load
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Solution Overview
Problem
The durations of phases in a three-phase electric motor within power tools fluctuate under heavy loads, leading to uneven commutation phenomena, which can cause premature activation of locked rotor protection, affecting performance, efficiency, and user experience.
Innovation Solution
A power tool with a detection device to monitor phase durations and a controller that dynamically adjusts rising and falling commutation points based on the duration ratio of rising to falling phases, thereby maintaining balanced phase durations and preventing uneven commutation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power tool operates under heavy load, then the power output is improved, but the phase duration fluctuation increases causing uneven commutation
Solution Approach 1:
The patent implements dynamic commutation point adjustment by detecting phase duration in real-time and modifying commutation timing based on detected fluctuations. The controller dynamically adapts the commutation points to compensate for load-induced variations, transforming the static commutation system into a dynamic one that maintains stability under varying power conditions
Solution Approach 2:
The patent employs feedback control by detecting the actual phase duration of the motor and using this information to adjust the commutation points. The detection device monitors phase duration, and the controller uses this feedback to correct commutation timing, creating a closed-loop control system that eliminates uneven commutation caused by heavy load operation
2Device complexity
If the phase duration fluctuation is not corrected, then the device complexity remains low, but the locked rotor protection activates prematurely
Solution Approach 1:
The patent implements self-service control where the system detects its own operational state (phase duration) and automatically adjusts its own parameters (commutation points). The motor control system monitors itself and performs self-correction, eliminating the need for external intervention or complex additional control mechanisms while improving protection accuracy
3Stability of the object's composition
If the commutation points are dynamically adjusted, then the uneven commutation phenomenon is eliminated, but the control system complexity increases
Solution Approach 1:
The patent changes the timing parameters of commutation based on detected phase duration. By adjusting the commutation point timing parameters in response to measured fluctuations, the system maintains uniform commutation without requiring fundamental changes to the motor structure or control architecture, achieving improved stability through parameter optimization
Data Source
AI summary
A power tool includes a functional piece; an electric motor; a power supply device; a controller connected to the electric motor and used for controlling the operation of the electric motor; and a detection device connected to the electric motor and the controller and configured to detect the duration of each phase of the electric motor. The controller is configured to obtain the duration of a rising phase and the duration of a falling phase according to the duration of each phase of the electric motor and determine whether the electric motor has an uneven commutation phenomenon; and when the electric motor has the uneven commutation phenomenon, dynamically adjust a rising commutation point and/or a falling commutation point of the electric motor based.