Marine Propulsion Rotor Position Correction for Eddy Current Drift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional outboard motors experience a decrease in motor output due to deviations in the calculated magnet position of the rotor caused by eddy currents generated in the metal housing, leading to suboptimal torque application.
Innovation Solution
A marine propulsion device with a detector facing the rotor via a metal housing, where a controller calculates the rotation speed of the rotor based on magnetic flux density and corrects the deviation in the magnet position using stored correction information, ensuring optimal torque application by adjusting the current timing to the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detector faces the rotor via a metal housing, then the detector is protected and housed in a sealed member, but eddy currents are generated in the metal causing deviation in the calculated magnet position of the rotor
Solution Approach 1:
A non-magnetic material is introduced as an intermediary between the detector and the rotor, replacing the metal housing in the detection path. This non-magnetic material allows magnetic flux to pass through without generating eddy currents, thereby eliminating the deviation in magnet position detection while still providing protective housing for the detector
Solution Approach 2:
The metal housing is removed from the detection path between the detector and rotor. By extracting the metal component that causes eddy currents, the magnetic field can be detected accurately without interference, while the protective function is maintained through alternative non-magnetic housing materials
2Productivity
If the controller applies current to the stator based on calculated magnet position, then the motor operates, but the rotor does not obtain maximum torque due to position deviation
Solution Approach 1:
The system uses feedback from the detector to monitor the actual magnet position, compares it with the calculated position, and automatically corrects the current application timing to the stator. This feedback mechanism ensures that maximum torque is achieved by compensating for the deviation caused by eddy currents in the metal housing
Solution Approach 2:
The controller dynamically adjusts the timing parameter of current application to the stator based on the detected magnet position. By changing the timing parameter in real-time to compensate for position deviation, the system ensures optimal torque generation despite the presence of eddy currents
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 improves the motor output by accurately correcting the magnet position deviation, allowing the rotor to achieve maximum torque, thereby enhancing the propulsion efficiency of the marine vessel.
Implementation Method 1
a detector facing the rotor via a metal to detect a magnetic flux density generated by a magnet of the rotor
Implementation Method 2
correct a deviation in the calculated magnet position of the rotor due to an eddy current generated in the metal
Data Source
AI summary
A marine propulsion device includes a controller configured or programmed to calculate a rotation speed of a rotor based on a magnetic flux density detected by a detector, and correct a deviation in a calculated magnet position of the rotor due to an eddy current generated in a metal based on the calculated rotation speed of the rotor.