Washing Machine Imbalance Detection Using Motor Current Phase
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Solution Overview
Problem
Conventional washing machines face challenges in detecting out of balance conditions during high-speed spin cycles, leading to unnecessary wear and tear on mechanical and electrical components, and reduced reliability due to the need for additional cycle time and power loss during imbalance detection.
Innovation Solution
A method and system that involves determining the angular positions of a washing machine's motor, sampling single-phase motor current data at these positions, and using spectral analysis to identify an out of balance condition based on the motor current spectrum, allowing for real-time detection and potential adjustment of rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imbalance detection techniques are used that require operating at a predetermined rotational speed, then out of balance conditions can be detected, but additional cycle time is required and power loss occurs due to ramping down to the predetermined speed
Solution Approach 1:
The patent changes the parameter being measured from motor current magnitude to motor current phase angle. By analyzing the phase angle of the motor current relative to the motor voltage across different rotor positions, the system can detect imbalance conditions without changing the rotational speed. This allows imbalance detection to occur during normal high-speed spin operations, eliminating the need to ramp down to a predetermined speed and thus reducing cycle time loss.
2Measurement precision
If conventional imbalance detection techniques are used that require operating at a predetermined rotational speed, then out of balance conditions can be detected, but power loss occurs due to ramping down to the predetermined rotational speed
Solution Approach 1:
The patent changes the parameter being measured from motor current magnitude to motor current phase angle. By analyzing the phase angle of the motor current relative to the motor voltage across different rotor positions, the system can detect imbalance conditions without changing the rotational speed. This allows imbalance detection to occur during normal high-speed spin operations, eliminating the need to ramp down to a predetermined speed and thus reducing power loss.
3Productivity
If high-speed spin operation continues with an out of balance load, then productivity is maintained, but wear and tear on mechanical and electrical components increases and reliability decreases
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the phase angle of the motor current during high-speed spin operation. When an imbalance condition is detected through phase angle analysis, the controller provides feedback to either alert the user or automatically adjust the spin operation. This allows the system to maintain productivity during normal operation while protecting against excessive wear and reliability issues by detecting and responding to imbalance conditions in real-time.
Data Source
AI summary
Systems and methods for determining an out of balance condition of a washing machine are provided. In particular, a plurality of angular positions of a motor associated with a washing machine can be determined. The washing machine can include a wash tub, and a wash basket rotatably mounted within the wash tub. The motor is configured to rotate the wash basket within said wash tub. Data indicative of at least a single phase of motor current being applied to the motor can be obtained while the wash basket rotates. The data can be spatially sampled over at least a subset of the plurality of angular positions of the motor. An out of balance condition associated with the washing machine can be determined based at least in part on the sampled data.