Brushless Motor Phase Winding Control for Heavy Load Torque
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Solution Overview
Problem
Brushless motors in power tools experience reduced performance and user experience due to high armature current and low torque during heavy load states, leading to inefficient operation and delayed commutation.
Innovation Solution
A power tool system with a controller that dynamically connects and disconnects phase windings to the power supply based on the rotor's position, using a drive circuit and position detection module to optimize voltage and current distribution, allowing for advanced commutation strategies and field weakening to enhance motor efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the brushless motor operates in heavy load state, then the current of the armature winding increases, but the torque decreases and performance deteriorates
Solution Approach 1:
The patent implements dynamic phase winding connection control based on rotor position detection. The controller dynamically switches between different phase winding connections (star connection and triangle connection) according to the motor's operating state, enabling the motor to adapt to heavy load conditions and maintain stable performance by optimizing the electrical connection configuration in real-time
Solution Approach 2:
The patent changes the connection parameter of phase windings dynamically. By switching the connection mode (star/triangle) of phase windings based on rotor position and load conditions, the motor impedance and current distribution are adjusted, allowing the motor to maintain optimal performance across different load states including heavy load conditions
2Power
If the brushless motor operates in heavy load state, then the armature current increases, but the commutation timing is delayed
Solution Approach 1:
The patent uses position detection modules to detect rotor position in advance and predicts the optimal commutation timing. By performing preliminary detection and calculation of commutation points based on rotor position, the system compensates for potential delays and ensures accurate commutation timing even under heavy load conditions where current increases
Solution Approach 2:
The patent implements a feedback control mechanism where the controller continuously monitors rotor position through position detection modules and adjusts commutation timing based on actual motor state. This closed-loop feedback ensures that commutation occurs at the optimal moment regardless of load variations, preventing timing delays
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 improves motor efficiency and stability by reducing armature reaction and enabling effective field weakening, resulting in higher rotational speed and stable output performance even under heavy loads.
Implementation Method 1
a power supply module configured to power the motor; a drive circuit configured to cause the power supply module to be electrically connected to at least two of the first phase winding, the second winding, and the third phase winding
Implementation Method 2
a controller configured to control the drive circuit according to a rotational position of the rotor to connect the first phase winding, the second phase winding, and the third phase winding to the power supply module
Data Source
AI summary
A power tool and a control method of the power tool are provided. The power tool includes a rotor and a stator having a first phase winding, a second phase winding and a third phase winding; a power supply module configured to power the motor; a drive circuit configured to electrically connecting the power module to at least two of the first phase winding, the second winding, and the third phase winding; a controller configured to control the drive circuit to connect the first phase winding, the second phase winding, and the third phase winding to the power supply module according to a rotational position of the rotor.