Dishwasher Motor Current Detection for Sensorless Position Tracking
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Solution Overview
Problem
Conventional water-bearing household appliances require additional wiring and complexity due to the need for position sensors to determine the position of movable components, increasing costs and complexity.
Innovation Solution
A water-bearing household appliance with a brushless direct current (BLDC) motor and a control device that detects the drive current consumed by the motor to determine the position of movable components, eliminating the need for additional cabling and position sensors by using a load device to provide position-dependent resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor with additional wiring is used to determine the position of movable components, then the position detection accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the position sensing function from a separate physical sensor and wiring system, and integrates it into the existing motor control system by analyzing the motor's drive current characteristics. This eliminates the need for additional position sensors and their associated wiring, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The motor control system is given a dual function: it not only controls the motor's operation but also detects the position of movable components through current analysis. This multi-functionality approach allows the same system to perform both motor control and position sensing without requiring separate dedicated components, thereby reducing overall system complexity while maintaining detection accuracy.
2Measurement precision
If a switching cam with signal cable is used to determine component position, then the position detection is achieved, but the wiring effort and device complexity increase
Solution Approach 1:
The patent removes the mechanical switching cam and its signal cable from the system, replacing them with an electronic sensing method that utilizes the motor's existing electrical connections. This extraction eliminates the need for additional mechanical components and wiring, simplifying both manufacturing and assembly processes while maintaining position detection capability.
Solution Approach 2:
The patent replaces the mechanical position detection system (switching cam with physical contact and signal cable) with an electrical/electronic sensing system that analyzes motor current characteristics. This substitution eliminates mechanical wear, reduces wiring requirements, and simplifies the overall system while achieving the same position detection function.
3Loss of information
If additional position sensors and cabling are installed to detect movable component position, then the position information is obtained, but the cost and complexity of the appliance increase
Solution Approach 1:
The motor itself serves as the sensing element by providing position information through its own operational characteristics (drive current). Instead of requiring the motor to simply drive the component while a separate sensor monitors position, the system uses the motor's electrical characteristics to self-report its position, eliminating the need for additional sensing components and reducing overall system complexity.
Solution Approach 2:
The patent extracts position information from the motor's operational parameters rather than requiring separate sensing hardware. By analyzing the drive current characteristics during motor operation, the system obtains position information without adding sensors or cabling, thereby reducing appliance complexity while preventing loss of position information.
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
This solution reduces the complexity and cost of the appliance while accurately determining the position of movable components without additional cabling, enhancing operational efficiency and reliability.
Implementation Method 1
The control device is set up to detect the drive current consumed by the electric motor during the movement of the component at the specified speed
Implementation Method 2
the load device provides a position-dependent resistance opposing the movement of the movable component
Implementation Method 3
The electric motor is designed in particular as a brushless direct current motor (BLDC motor)
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
The invention relates to a water-bearing domestic appliance, in particular a dishwasher, comprising a moving component, an electric motor for moving the component, a control apparatus for actuating the electric motor and a load apparatus for providing a resistance which is dependent on a position of the moving component and opposes the movement, wherein the control apparatus is designed to detect the drive current which is drawn by the electric motor and is dependent on the provided resistance and to ascertain the position of the moving component as a function of the detected drive current.