Brushless Motor Pole Count Optimization for Compact Design
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Solution Overview
Problem
Existing electric work machines with brushless motors face challenges in making the motor more lightweight and compact while maintaining output power, and avoiding decreased detection accuracy of magnetic sensors and coil burnout.
Innovation Solution
The configuration includes a brushless motor with a rotor and stator, magnetic sensors, and a controller, where the rotor has permanent magnets fixed to the rotor core, and the stator has coils mounted on insulators, with specific conditions for pole count and stator diameter to ensure a lightweight and compact design, and a three-phase motor with optimized wire-to-wire resistance to prevent coil burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the pole count and stator diameter are optimized to make the motor more lightweight and compact, then the motor weight and size are reduced, but the detection accuracy of magnetic sensors may decrease
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships between pole count N and stator diameter x (0.16x+2.5≤N≤0.23x+3.6). This quantitative parameter optimization allows the motor to achieve reduced weight and compact size while maintaining adequate detection accuracy through proper magnetic flux distribution.
Solution Approach 2:
The patent employs local quality by using neodymium sintered plate magnets with specific magnetic properties positioned at precise locations on the rotor. This localized optimization of magnetic material properties ensures sufficient magnetic flux density for sensor detection even in a compact design, preventing detection accuracy degradation.
2Weight of moving object
If the pole count and stator diameter are optimized to make the motor more lightweight and compact, then the motor weight and size are reduced, but the output power may decrease
Solution Approach 1:
The patent resolves this contradiction through parameter changes by defining optimal ranges for pole count N relative to stator diameter x (0.16x+2.5≤N≤0.23x+3.6). This mathematical relationship ensures that the motor maintains sufficient output power while achieving weight reduction and compactness through optimized magnetic circuit design.
Solution Approach 2:
The patent uses neodymium sintered magnets, which are high-performance composite magnetic materials, to maximize magnetic flux density and efficiency. This allows the compact motor design to maintain high output power by utilizing the superior magnetic properties of these composite materials.
3Reliability
If the wire-to-wire resistance is reduced to prevent coil burnout, then the reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent addresses this contradiction through parameter changes by optimizing the wire-to-wire resistance to specific thresholds based on motor power rating. This quantitative approach allows prevention of coil burnout through controlled resistance values while maintaining manufacturability through standardized design criteria.
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 configuration allows for a more lightweight and compact brushless motor that maintains output power, avoids decreased detection accuracy, and reduces the likelihood of coil burnout, ensuring durable performance.
Implementation Method 1
The magnetic sensors may detect the position of the rotor in a rotational direction by detecting the magnetic flux of the permanent magnets
Implementation Method 2
The controller may control the coils that are energized in accordance with detection signals of the magnetic sensors
Data Source
AI summary
An electric work machine includes: a brushless motor including: a rotor having permanent magnets fixed to a rotor core; a stator core; one or more insulators fixed to the stator core; and a stator including coils mounted on the insulator(s); magnetic sensors, which detect the position of the rotor in a rotational direction by detecting the magnetic flux of the permanent magnets; a controller, which controls energization of the coils based in part on detection signals of the magnetic sensors; and an output part driven by the rotor. The permanent magnets are each a neodymium, sintered, plate magnet. The pole count (N) is the number of permanent magnets. The stator diameter (x) is the diameter of a surface of the stator core that faces the rotor in millimeters. The following condition is satisfied: 0.16x+2.5<N<0.23x+3.6.