Keyless Resolver Rotor Assembly for Precise Angular Sensing
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Solution Overview
Problem
Existing electric machines face challenges in achieving high sensing accuracy of the angular position of the resolver due to the use of key coupling structures, which increase manufacturing costs and tolerance chain links, affecting the precision of the relative angular position between the resolver rotor and the machine shaft.
Innovation Solution
A tool and method using a DC voltage applying device to generate a static magnetic field aligning the machine rotor with the resolver rotor, followed by a pressing device to press-fit the resolver rotor onto the machine shaft without a key coupling structure, ensuring precise angular orientation through interference fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a key coupling structure is used to set the relative angular position between the resolver rotor and the machine shaft, then the angular position can be controlled, but the manufacturing cost increases and the sensing accuracy of the angular position deteriorates due to increased tolerance chain links
Solution Approach 1:
The patent removes the key coupling structure from the assembly, eliminating the key groove features that were previously required on both the machine shaft and resolver rotor. This extraction of the unnecessary component directly reduces the number of tolerance chain links and simplifies the device structure while maintaining angular position control through alternative means.
Solution Approach 2:
The patent replaces the mechanical key coupling system with a magnetic field-based alignment system. By applying DC voltage to the three-phase windings to generate a static magnetic field, the machine rotor aligns automatically with the resolver rotor, eliminating the need for mechanical key grooves and their associated tolerance accumulation.
2Reliability
If a key coupling structure is used between the resolver rotor and the machine shaft, then the angular position can be set, but the manufacturing cost increases due to additional key grooves and tolerance control measures
Solution Approach 1:
The patent eliminates the key coupling structure and key grooves, removing the need for expensive precision machining and tolerance control measures associated with mechanical key fittings. The angular position setting function is maintained through magnetic field alignment, which reduces manufacturing complexity and cost.
Solution Approach 2:
The patent substitutes the mechanical key coupling system with an electromagnetic field-based system. By using DC voltage applied to the three-phase windings to create a static magnetic field for automatic alignment, the system achieves reliable angular position setting without the costly mechanical key groove fabrication and precision tolerance control required by traditional methods.
3Manufacturing precision
If key grooves are formed on both the resolver rotor and the machine shaft to create a key coupling structure, then the angular position can be controlled, but the number of tolerance chain links increases, negatively affecting sensing accuracy
Solution Approach 1:
The patent removes the key coupling structure that requires key grooves on both components, thereby eliminating the additional tolerance chain links introduced by this mechanical connection. This extraction simplifies the tolerance chain and improves the relative angular position precision between the resolver rotor and machine shaft.
Solution Approach 2:
The patent replaces the mechanical key coupling system with an electromagnetic alignment system. By applying DC voltage to generate a static magnetic field that automatically aligns the machine rotor with the resolver rotor, the system eliminates the need for multiple mechanical interface tolerances, reducing the number of tolerance chain links and improving angular position precision.
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 enhances sensing accuracy and reduces operational noise and instability by eliminating key coupling structures, ensuring high precision and stability of the angular position, thus improving the operational performance of the electric machine.
Implementation Method 1
applying a DC voltage across at least one phase of windings of the three-phase windings to create a static magnetic field by a DC electric current flowing through the at least one phase of windings
Implementation Method 2
the static magnetic field being able to force the machine rotor to rotate to an angular orientation where an N-S direction of magnets of the machine rotor is aligned with an N-S direction of the static magnetic field and to keep the machine rotor stably in the angular orientation
Implementation Method 3
a pressing device configured to push the resolver rotor onto the machine shaft in an axial direction
Data Source
AI summary
A resolver which includes a resolver rotor and a resolver stator, the resolver rotor being assembled by: applying a DC voltage across at least one phase of windings the electric machine to create a static magnetic field by a DC electric current flowing through the at least one phase of windings of the three-phase windings, the static magnetic field forcing a machine rotor to rotate to an angular orientation where an N-S direction of magnets of the machine rotor is aligned with an N-S direction of the static magnetic field and keeping the machine rotor stably in this angular orientation; and pushing the resolver rotor onto a machine shaft in an axial direction in a state that the machine rotor is kept in the angular orientation by the static magnetic field.