Variable-Magnet Motor Position Sensing for Accurate Flux Control
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Solution Overview
Problem
Conventional motors face challenges in accurately detecting the position of variable magnets, leading to potential misidentification and inefficient control of magnetic flux, especially when the magnetic force of the variable magnet is decreased.
Innovation Solution
A motor design incorporating a stator with a coil, a rotor with variable magnets, and multiple position sensors spaced 120 degrees apart, with a processor controlling the energizing operation to accurately magnetize or demagnetize the variable magnets, ensuring precise magnetic flux control and uniform magnetic forces across the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a digital hall sensor is used to detect the position of the variable magnet, then the position detection is simple and cost-effective, but the position detection accuracy deteriorates when the magnetic force of the variable magnet is decreased
Solution Approach 1:
The patent introduces an intermediary signal processing mechanism that converts the analog voltage output from position sensors into digital position information. This intermediary conversion process allows the system to use simple analog sensors while achieving accurate digital position detection, resolving the contradiction between sensor simplicity and detection accuracy.
Solution Approach 2:
The patent changes the detection parameter from binary on/off switching output (digital hall sensor) to continuous voltage output (analog position sensor). This parameter change enables the system to detect position accurately even when magnetic force varies, as the continuous voltage signal provides more granular position information than binary switching.
2Speed
If the magnetic force of the variable magnet is decreased to reduce magnetic flux, then the motor can operate at high speed with low torque, but the position detection accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary signal processing mechanism that converts the analog voltage output from position sensors into digital position information. This intermediary conversion process allows the system to use simple analog sensors while achieving accurate digital position detection, resolving the contradiction between sensor simplicity and detection accuracy.
Solution Approach 2:
The patent changes the detection parameter from binary on/off switching output (digital hall sensor) to continuous voltage output (analog position sensor). This parameter change enables the system to detect position accurately even when magnetic force varies, as the continuous voltage signal provides more granular position information than binary switching.
3Reliability
If multiple position sensors are used to improve position detection accuracy, then the position detection reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by strategically positioning sensors at specific locations (e.g., 120 degrees apart) rather than uniformly distributing them. This selective placement optimizes detection reliability for the specific application while minimizing the total number of sensors required, thus balancing reliability improvement with complexity control.
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 design enhances the accuracy of variable magnet position detection and magnetic flux control, reducing misidentification and noise levels, thereby improving motor performance and efficiency.
Implementation Method 1
an exciting current for changing the amount of magnetization of the variable magnet to flow in a winding of a stator through an inverter circuit
Implementation Method 2
a plurality of position sensors each having an output voltage changed according to a magnetic flux of the variable magnet
Data Source
AI summary
Provided is a washing machine including: a stator including a coil; a rotor including a plurality of variable magnets each having a magnetic force variable, and rotatable with respect to the stator; a controller configured to control an energizing of the coil to increase or decrease a magnetic force of the variable magnet; and a plurality of position sensors each having a output voltage changed according to a magnetic flux of the variable magnet.