HVDC Motor Power Density via Rotor Core Ratio
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Solution Overview
Problem
Conventional high voltage direct current (HVDC) motors used in kitchen appliances such as soybean milk makers and food mixers are limited by their power output, typically less than 40 watts, and cannot be easily scaled up without increasing size.
Innovation Solution
A permanent magnet motor design with a stator and rotor, utilizing higher-grade ferrite magnets with specific magnetic properties and a larger rotor core diameter relative to the housing diameter, allowing for increased power output without size increase, achieved by using a magnetically conductive round housing with permanent magnets and optimized rotor windings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor core outer diameter is increased to improve power output, then the power output increases, but the motor size increases
Solution Approach 1:
The patent optimizes the ratio of rotor core outer diameter to housing outer diameter within a specific range (0.7-0.85), and selects ferrite magnets with specific magnetic properties (Br≥3800Gs, Hcj≥4000Oe, BHmax≥4.0MGOe). These parameter optimizations enable higher power density, achieving 50-100W output without increasing motor size beyond conventional dimensions.
Solution Approach 2:
The patent uses ferrite permanent magnets with specific compositional characteristics (residual magnetic flux density Br of 3800-4400Gs, intrinsic coercive force Hcj of 4000-5000Oe, maximum energy product BHmax greater than 4.0MGOe). These composite magnetic materials provide higher magnetic strength and energy density, enabling increased power output within the same volume constraints.
2Device complexity
If conventional HVDC motors are used, then the motor structure is simple, but the power output is limited to less than 40 watts
Solution Approach 1:
The patent modifies key parameters of the conventional HVDC motor structure, including optimizing the rotor core to housing diameter ratio to 0.7-0.85 and selecting ferrite magnets with enhanced magnetic properties (BHmax>4.0MGOe). These parameter changes enable the motor to achieve 50-100W power output while maintaining the simple HVDC motor structure with commutator and brushes.
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 design achieves a power output range of 50 to 100 watts, providing a more powerful motor in a similar size, with improved thermal management and reduced copper losses, suitable for kitchen appliances.
Implementation Method 1
The stator comprises a magnetically conductive round housing, at least one permanent magnet fixed to an inner surface of the housing... The rotor windings are wound about poles of the rotor core and electrically connected to the commutator
Implementation Method 2
The rotor windings are supplied with HVDC power via a commutator and brushes... brushes for making sliding contact with the commutator
Data Source
AI summary
A permanent magnet motor has a rotor and a stator. The rotor has a shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft adjacent to the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator. The stator includes a magnetically conductive round housing, permanent magnets fixed to an inner surface of the housing, and brushes for making sliding contact with the commutator. The ratio of an outer diameter of the rotor core to an outer diameter of the housing is between 66% to 84%.