Motor Load State Detection via Voltage-Corrected Current
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Solution Overview
Problem
Existing electric working machines cannot accurately determine the no-load operation state of a motor due to voltage drops in the power supply path, which are influenced by internal resistances in power cords and batteries, leading to incorrect current readings.
Innovation Solution
Incorporating a load state determination unit that uses both current and voltage detectors to calculate a corrected current value, accounting for internal resistances in the power supply path, allowing precise determination of the motor's operation state by comparing input and output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only current detection is used to determine motor operation state, then the detection method is simple, but the determination accuracy deteriorates when power supply path length changes
Solution Approach 1:
The patent introduces voltage detection as an intermediary measurement to correct the current detection results. By detecting both voltage and current, the system calculates corrected current values that compensate for voltage drops in the power supply path, thereby maintaining accurate operation state determination regardless of power supply path length changes.
2Length of moving object
If cord reel for extension is used to extend power supply path, then the reach distance is improved, but the input voltage and input current are reduced
Solution Approach 1:
The patent implements feedback by continuously monitoring both voltage and current at the motor terminals and using this information to calculate corrected current values. This feedback mechanism allows the system to accurately determine operation state even when the power supply is extended through cord reels, compensating for the reduced voltage and current caused by the extended path.
3Length of moving object
If multiple cord reels are used to further extend power supply path, then the reach distance is increased, but the voltage drop and current reduction become more severe
Solution Approach 1:
The patent changes the measurement parameters by detecting both voltage and current simultaneously and calculating a corrected current value that accounts for voltage drop. This parameter transformation allows accurate operation state determination even when multiple cord reels are used, as the corrected current compensates for the cumulative voltage drops across multiple extension segments.
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
Enables accurate identification of no-load operation states regardless of changes in the power supply path length or battery condition, ensuring proper motor control and power management.
Implementation Method 1
a voltage detector that detects an input voltage supplied to the motor during drive of the motor
Implementation Method 2
a current detector that detects a current flowing through the motor during drive of the motor
Implementation Method 3
This voltage drop is dependent on an internal resistance R of the power cord 4 and an input current Iin to the electric working machine 6
Data Source
AI summary
An electric working machine according to one aspect of the present disclosure includes a motor, a current detector, a voltage detector, and a load state determination unit. The current detector is configured to detect a current flowing through the motor during drive of the motor. The voltage detector is configured to detect an input voltage supplied to the motor during drive of the motor. The load state determination unit is configured to determine whether the motor is in a no-load operation state based on the detected current, the detected input voltage and an output voltage from an electric power source.