Encoder Alignment Plate for Motor Back-EMF Correlation
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Solution Overview
Problem
Existing electric motors require precise alignment of rotary encoders with back electromotive force (BEMF) waveforms, which is challenging when encoders need replacement or repair, as this alignment is typically done during assembly and not easily replicable by end users.
Innovation Solution
A method and assembly for mounting a calibrated encoder assembly to an electric motor using a sensor alignment plate that can be adjusted to align the sensor output signal waveform with the BEMF waveform, involving a servo driven functional tester and data acquisition unit to measure and secure the alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the rotary encoder is replaced during field service, then the encoder can be renewed, but the alignment between sensor output signal waveform and BEMF waveform is lost
Solution Approach 1:
The alignment plate is pre-calibrated during manufacturing to establish the correct angular relationship between the sensor and BEMF waveform. This preliminary alignment action ensures that when the encoder is replaced, the pre-calibrated plate maintains the proper alignment without requiring field recalibration
Solution Approach 2:
The alignment plate serves as an intermediary component between the encoder and the motor. It decouples the encoder replacement from alignment loss by providing a stable, pre-calibrated reference frame that maintains the sensor-BEMF relationship independent of encoder changes
2Manufacturing precision
If the encoder is initially aligned during assembly, then the alignment is established, but the alignment cannot be replicated when the encoder is replaced
Solution Approach 1:
The alignment plate is pre-calibrated during manufacturing to establish the correct angular relationship between the sensor and BEMF waveform. This preliminary alignment action ensures that when the encoder is replaced, the pre-calibrated plate maintains the proper alignment without requiring field recalibration
Solution Approach 2:
The alignment plate provides universal alignment capability across multiple encoder replacements. Once calibrated, the same plate can be used with different encoders, making the alignment process universal and repeatable without requiring re-calibration for each encoder instance
3Manufacturing precision
If a fixed alignment method is used, then the initial alignment is achieved, but field service requires complex realignment procedures
Solution Approach 1:
The alignment plate serves as an intermediary component between the encoder and the motor. It decouples the encoder replacement from alignment loss by providing a stable, pre-calibrated reference frame that maintains the sensor-BEMF relationship independent of encoder changes
Solution Approach 2:
The alignment function is segmented into a separate, independent component (the alignment plate) that can be pre-calibrated and reused. This segmentation allows the alignment task to be performed once during manufacturing rather than repeatedly during field service, simplifying maintenance procedures
Data Source
AI summary
A method and apparatus serve to mount a calibrated encoder assembly to an electric motor so that a sensor output signal waveform produced by the calibrated encoder assembly is aligned with a back electromotive force (BEMF) waveform of the electric motor. The calibrated encoder assembly is fixed to an alignment plate, which is attached to the electric motor. The electric motor is rotated using a servo driven functional tester and the BEMF waveform of the electric motor is measured. The sensor output signal waveform is measured, and the alignment plate is adjusted relative to the electric motor to align the sensor output signal waveform to the BEMF waveform. The alignment plate is secured to the electric motor in the adjusted orientation.