Motor Rotor Magnet Axial Length Adjustment for Torque Consistency
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Solution Overview
Problem
The use of magnets with different magnetic flux densities in motors leads to variations in torque and reduced motor efficiency due to the need for reactive current adjustments, as different manufacturers produce magnets with varying magnetic flux densities.
Innovation Solution
The axial length of magnets is adjusted based on their residual magnetic flux density by multiplying the reference axial length by the magnet's magnetic flux density and dividing by a reference residual magnetic flux density, ensuring consistent torque and motor efficiency by standardizing the magnetic flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnets with different magnetic flux densities are used from different manufacturers, then the motor can be assembled with available magnets, but the torque varies and motor efficiency decreases
Solution Approach 1:
The patent changes the physical parameter of magnet length (axial direction dimension) to compensate for variations in magnetic flux density. By adjusting the length parameter based on the specific magnetic flux density of each magnet, the total magnetic flux contribution is standardized, allowing magnets from different manufacturers to be used while maintaining consistent torque output.
2Force
If higher magnetic flux density magnets are used, then the torque increases, but the back electromotive force increases requiring lower applied voltage
Solution Approach 1:
The patent adjusts the axial length parameter of magnets to control the total magnetic flux. By varying this dimensional parameter, the system can optimize the balance between torque generation and back electromotive force, allowing flexible voltage operation while maintaining high torque output.
3Device complexity
If d-axis current is controlled by open loop, then the control is simple, but when back electromotive force fluctuates, extra reactive current is required reducing efficiency
Solution Approach 1:
The patent performs preliminary standardization of magnets during manufacturing by controlling their axial length according to their magnetic flux density. This pre-adjustment eliminates the need for complex real-time reactive current compensation, allowing simple open-loop control while maintaining high 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
This approach allows for consistent torque generation and adjustable back electromotive force across motors using magnets from different manufacturers, maintaining motor efficiency by standardizing the magnetic flux and adjusting resin amounts for precise magnet placement.
Implementation Method 1
the higher the magnetic flux densities of the magnets, the greater the gap magnetic flux of the motor and the greater the torque which the motor generates
Implementation Method 2
the higher the magnetic flux densities of the magnets, the higher the back electromotive force becomes
Data Source
AI summary
A rotor (10) of a motor includes a rotor core (11) and a plurality of magnets (14a, 14b) which are arranged at a circumferential surface of the rotor core or at the inside of the rotor core, the length of a magnet of the plurality of magnets in the axial direction of the rotor core determined in accordance with the residual magnetic flux density of the magnet. The axial direction length of the magnet is preferably determined by multiplying a reference axial direction length of the magnet with the residual magnetic flux density of the magnet and dividing this by a reference residual magnetic flux density of the magnet.