Washing Machine Load Detection Using Motor Current Analysis
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Solution Overview
Problem
Conventional washing machines face challenges in accurately determining the amount of laundry, especially with sensorless motors, leading to inefficiencies in spin-drying operations due to unbalanced loads and increased energy consumption.
Innovation Solution
A washing machine with a controller that analyzes current values during motor operation, using gravity and inertia to calculate the laundry amount by controlling the motor's speed within specific ranges and periods, eliminating initial position and movement errors without relying on sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current is measured at the time of starting the motor to determine the amount of laundry, then the measurement process is simple, but the measurement precision is poor due to initial position and movement variations
Solution Approach 1:
The motor is driven at a predetermined speed before measuring current to ensure the laundry is in a stable state. This preliminary action eliminates the effects of initial position and movement variations, allowing for more precise measurement of laundry amount based on current consumption at a known operational state.
Solution Approach 2:
The measurement process transitions from a static measurement (at motor start) to a dynamic measurement (at predetermined motor speed). By controlling the motor to operate at a specific speed before measurement, the system captures laundry amount information under controlled dynamic conditions, improving precision while maintaining reasonable complexity.
2Productivity
If the motor is rotated at high speed for spin-drying without precise laundry amount determination, then the spin-drying operation can proceed quickly, but the reliability decreases due to unbalanced loads and potential damage
Solution Approach 1:
The system measures current consumption at a predetermined motor speed to determine laundry amount, then uses this information as feedback to adjust the spin-drying rotational speed. By setting the maximum rotational speed based on the measured laundry amount, the system ensures balanced operation and prevents damage while maintaining efficient spin-drying performance.
Solution Approach 2:
The spin-drying rotational speed parameter is dynamically adjusted based on the measured laundry amount. Instead of using a fixed high speed, the system changes the speed parameter according to the actual load conditions, optimizing both safety and productivity by matching motor speed to laundry mass.
3Productivity
If the motor rotational speed is increased for faster spin-drying, then the productivity increases, but the use of energy increases due to extended washing time from imprecise laundry determination
Solution Approach 1:
The system replaces complex sensor-based laundry detection mechanisms with an electrical measurement approach. By measuring current consumption at a predetermined motor speed, the system determines laundry amount through electrical parameters rather than mechanical sensing, enabling rapid assessment that reduces overall washing time and energy consumption while maintaining spin-drying efficiency.
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 precise and rapid determination of laundry quantity, reducing washing time and energy consumption by optimizing spin-drying operations based on accurate load measurements.
Implementation Method 1
a motor (270) connected to the drum (134)
Implementation Method 2
a current-sensing unit (280) for measuring a current value of the motor (270)
Implementation Method 3
a motor is rotated at a high speed. As a result, centrifugal force is applied to the laundry in the drum, whereby water is removed from the laundry
Implementation Method 4
determining the amount of laundry based on a current value received from the current-sensing unit (280), wherein the motor-driving unit (260) controls the motor (270) such that a rotational speed of the motor is repeatedly maintained, accelerated, and decelerated within a predetermined range of speed
Data Source
AI summary
An amount of laundry that is introduced into a washing machine is determined by identifying gravitational and inertia forces applied during the operation of a motor, whereby it is possible to precisely calculate the amount of laundry and to minimize the effects of the initial position of the laundry and the movement of the laundry. In addition, the current value of the motor that is operated is used to measure the amount of laundry without a sensor. Furthermore, the amount of laundry is measured at the rotational speed of the motor at which the laundry clings to the drum, whereby it is possible to minimize error due to the movement of the laundry to thus improve accuracy. Moreover, it is possible to determine the amount of laundry within a short time. Consequently, it is easy to commence the spin-drying operation, thereby reducing washing time and saving energy.