Stator End Insulation Structure for Motor Shaft Voltage Shielding
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Solution Overview
Problem
Existing IPM-type motors experience bearing corrosion due to axis voltage and current, leading to noise, vibration, and motor failure, which is exacerbated by increased voltage and carrier frequency, and conventional anti-corrosion solutions like ceramic bearings are costly.
Innovation Solution
An insulation structure comprising a conducting part and insulating part applied to the stator ends to redirect and insulate the electric field, reducing axis voltage without using expensive ceramic bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic bearings or SGR/RGC bearings are used to prevent bearing corrosion, then bearing reliability is improved, but material cost increases
Solution Approach 1:
The patent introduces a shielding structure as an intermediary component between the motor components and the bearing. This shielding structure redirects the axis voltage to the motor housing, preventing it from reaching the bearing. By adding this intermediate protective layer, the patent maintains bearing reliability while allowing the use of cost-effective standard bearings instead of expensive ceramic or specialized bearings.
Solution Approach 2:
The patent employs a cost-effective shielding structure made from readily available materials that can be easily manufactured and replaced if needed. This approach substitutes expensive long-lasting ceramic bearings with a cheaper shielding solution plus standard bearings, reducing overall material cost while maintaining adequate reliability through the shielding protection.
2Temperature
If oil cooling method is used to cool the motor, then cooling efficiency is improved, but anti-corrosion effect is significantly reduced due to oil film formation
Solution Approach 1:
The patent segments the motor structure by introducing a shielding structure that creates a separate electrical path. The shielding structure is positioned to intercept axis voltage before it reaches the bearing, while the oil cooling system operates independently. This segmentation allows the oil cooling function to remain effective while the shielding function protects against corrosion, resolving the conflict between cooling efficiency and anti-corrosion effect.
Solution Approach 2:
The shielding structure acts as an intermediary that blocks the path of axis voltage to the bearing. Even when oil film is present on bearing surfaces due to oil cooling, the shielding structure prevents axis voltage from reaching the bearing, maintaining anti-corrosion protection while allowing oil cooling to function at full efficiency.
3Power
If increased voltage and carrier frequency are applied to meet higher motor specifications, then motor power is improved, but axis voltage and axis current increase causing more bearing corrosion
Solution Approach 1:
The patent converts the harmful axis voltage generated by high-power operation into a beneficial situation by providing it with a safe discharge path through the shielding structure. The shielding structure guides the axis voltage to the motor housing, preventing it from damaging the bearing. This allows the motor to operate at high power levels while the previously harmful axis voltage is redirected to serve as a controlled electrical path that protects rather than damages components.
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 insulation structure effectively decreases axis voltage by up to 69% and 28%, minimizing motor failures while maintaining manufacturing convenience and reducing material costs.
Implementation Method 1
a conducting part extending in an induction direction parallel to a direction in which the end coil assembly is pulled out from the stator and inducing the electric field of the end coil assembly to be directed in the induction direction
Implementation Method 2
an insulating part positioned between the conducting part and the end coil assembly to insulate the conducting part
Data Source
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AI summary
An insulation structure applied to each of two ends of a stator in an axial direction to block an electric field of an end coil assembly from being applied to a motor shaft. The structure includes: a conducting part extending in a predetermined induction direction parallel to a direction in which the end coil assembly is pulled out from the stator; and an insulating part positioned between the conducting part and the end coil assembly to insulate the conducting part.