Permanent Magnet Motor Parallel Coils EMI Suppression
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Solution Overview
Problem
There is a need for a compact electric motor with high power density to meet the demands of portable power tools, as existing motors are limited in size reduction while maintaining maximum force output.
Innovation Solution
A permanent magnet motor design featuring a stator with multiple magnets, a brush card, brushes, lead wires, and a rotor with a commutator and winding, where the coils are wound around teeth and connected in parallel, and an EMI suppression component is used to enhance power density and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the motor size is reduced to make portable power tools compact, then the portability and compactness are improved, but the output power and force decrease
Solution Approach 1:
The motor is divided into distinct functional segments: permanent magnet stator, laminated rotor core with teeth, commutator with segments, and brush assembly. This segmentation allows optimization of each component for high power density while maintaining compact overall dimensions suitable for portable power tools
Solution Approach 2:
The invention changes key parameters including using permanent magnets for the stator instead of field windings, employing laminated rotor core construction, and implementing a commutator-based brush motor design. These parameter changes enable high power density in a compact form factor, resolving the contradiction between small size and high output power
2Volume of moving object
If the motor size is reduced to increase power density, then the compactness is improved, but the cooling capability and heat dissipation worsen
Solution Approach 1:
The rotor core employs laminated construction with insulated layers that provide both mechanical strength and thermal management. The dynamic rotation of the rotor creates continuous air flow through the motor, enhancing convective cooling despite the compact size, thus managing heat dissipation effectively in a small form factor
3Volume of moving object
If thinner wire coils are used to increase power density, then the motor size is reduced, but the current carrying capacity and electrical resistance worsen
Solution Approach 1:
The winding system is segmented into multiple coils distributed around the rotor teeth, with each coil connected to specific commutator segments. This segmentation allows the use of thinner wires in multiple parallel paths, maintaining current carrying capacity while reducing overall motor size and improving power density
Solution Approach 2:
The invention changes the electrical configuration by using multiple coils with parallel connections through the commutator system. This parameter change enables the use of thinner wires while maintaining adequate current capacity, resolving the contradiction between compact size and electrical performance reliability
4Power
If the number of magnets is increased to increase output power, then the power density is improved, but the device complexity and manufacturing cost worsen
Solution Approach 1:
The stator uses an asymmetric arrangement of permanent magnets optimized for the specific application, with magnets positioned to create effective magnetic fields for high power density. This asymmetric design achieves high output power without requiring excessive numbers of magnets, balancing performance with manufacturing complexity
Solution Approach 2:
The invention changes from traditional wound field stators to permanent magnet stators, and from solid rotor cores to laminated constructions. These parameter changes enable high output power with optimized magnet placement, reducing the number of magnets needed while maintaining high power density and simplifying manufacturing
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
The motor achieves increased power density by using thinner wire coils connected in parallel, allowing for a more compact design while maintaining high output power, and the EMI suppression component minimizes electromagnetic interference.
Implementation Method 1
a permanent magnet motor comprising: a stator having a housing, a plurality of magnets installed at an inner surface of the housing... a rotor installed in the stator, the rotor comprising a shaft, a commutator fixed on the shaft, a rotor core fixed on the shaft and a winding wound on the rotor core... in operation electrified coils are connected in parallel
Data Source
AI summary
An electric motor has a stator and a rotor rotatably installed in the stator. The stator includes a housing, a plurality of magnets installed at an inner surface of the housing, a brush card installed inside of the housing, brushes mounted on the brush card, lead wires for connecting to a power source and feeding power to the brushes, and an end cap attached to an end of the housing and covering the brushes. The rotor includes a shaft, a commutator fixed on the shaft, a rotor core fixed on the shaft and a winding wound on the rotor core and connected to the commutator. An EMI suppression component is mounted on the brush card and covered by the end cap, and the lead wires extends through the EMI suppression component.