Motor Control Method for Electric Power Tools
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric power tools often enter a locked rotor condition during operation, leading to increased current and potential motor damage, requiring power cutoff and restart, which reduces efficiency and impacts motor life.
Innovation Solution
A motor control method that measures current and adjusts the duty cycle of the power supply circuit to eliminate locked rotor conditions without cutting off power, allowing continuous operation and preventing motor damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply is cut off when locked rotor condition occurs, then motor damage is prevented, but work efficiency is reduced and motor life is impacted
Solution Approach 1:
The patent implements continuous duty cycle adjustment to maintain motor operation during locked rotor conditions. Instead of cutting off power supply completely, the controller continuously adjusts the duty cycle to manage current while keeping the motor running, thereby eliminating the need for restart operations and maintaining work continuity.
Solution Approach 2:
The patent dynamically adjusts the duty cycle of the power supply circuit based on real-time current monitoring. When locked rotor condition is detected, the duty cycle is automatically modified to control current flow, and when the condition is eliminated, the duty cycle is restored. This dynamic adjustment allows the system to adapt to changing conditions without interruption.
2Reliability
If the power supply is cut off when locked rotor condition exists, then motor and circuit damage is avoided, but restart operation is required which reduces efficiency
Solution Approach 1:
The power supply is maintained continuously through duty cycle control rather than being cut off. The controller adjusts the duty cycle to prevent damage while keeping the power flow active, eliminating the stop-and-restart cycle that causes time loss and reduces overall system efficiency.
3Productivity
If the duty cycle is adjusted to eliminate locked rotor condition, then continuous operation is enabled, but current control precision must be maintained
Solution Approach 1:
The patent employs a feedback control mechanism where the controller continuously monitors the current flowing through the motor and adjusts the duty cycle accordingly. When locked rotor condition is detected through current threshold comparison, the duty cycle is modified to reduce current, and when the condition resolves, the duty cycle is increased back. This closed-loop feedback ensures precise current control while maintaining continuous operation.
Data Source
AI summary
An electric power tool includes a motor, a power supply circuit for supplying power to the motor, and a control device which is able to measure current of the motor and control duty cycle of the power supply circuit. When the measured current of the motor is greater than a predetermined current value, the duty cycle of the power supply circuit is increased to a first predetermined value. If the current of the motor is still greater than the predetermined current value, the duty cycle of the power supply circuit is decreased to a second predetermined value such that the current of the motor is equal to or less than the predetermined current value.