Remote Rotor Position Sensing via Differential Harness Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In applications where there is limited axial packaging space, the reliable transfer of angular position data from a rotating electric machine to a control board is compromised due to the need to locate the inverter away from the motor end, leading to signal degradation over long electrical harnesses.
Innovation Solution
The implementation of an electronically controlled electric machine with a sensor board positioned at the opposite end of the rotor shaft, transmitting a differential pair of electrical signals via an electrical harness to a machine control board located outside the casing, which converts these signals back to a single-ended signal indicative of the angular position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the inverter is located away from the motor end to accommodate limited axial packaging space, then the packaging space constraint is resolved, but the angular position data transmission reliability deteriorates due to long electrical harnesses causing signal degradation
Solution Approach 1:
A sensor board is introduced as an intermediary component positioned at the non-drive end of the motor shaft, close to the sensor target. This sensor board includes a shaft angle sensor that generates electrical signals and converts them to differential pairs for transmission through the electrical harness to the control board, thereby maintaining signal integrity over long distances while enabling remote inverter placement
Solution Approach 2:
The electrical signal parameters are transformed from single-ended signals generated by the shaft angle sensor to differential pair signals for transmission. This parameter change enhances noise immunity and signal integrity over long electrical harnesses, resolving the reliability issue while allowing flexible inverter placement
2Reliability
If the inverter is positioned close to the motor end to ensure reliable signal transmission, then the angular position data transmission reliability is improved, but the axial packaging space is insufficient
Solution Approach 1:
The control system is segmented into three separate components: the shaft angle sensor on the sensor board at the motor end, the electrical harness for signal transmission, and the control board in the inverter away from the motor. This segmentation allows each component to be optimally positioned, enabling reliable signal transmission while accommodating limited axial packaging space
3Device complexity
If a single-ended electrical signal is transmitted over a long electrical harness, then the system complexity is low, but the signal integrity deteriorates due to noise and interference
Solution Approach 1:
The signal transmission parameter is changed from single-ended to differential pair format. This transformation provides inherent noise rejection and immunity to ground potential differences, maintaining signal integrity over long electrical harnesses while adding manageable complexity through the sensor board's signal conversion capability
Data Source
AI summary
A rotating electric machine includes a shaft angle sensor communicating with an external controller via differential signaling. This construction permits the controller to be located away from the axial end of the motor while reliably transmitting rotor angle or speed information to the controller over a relatively long electrical harness. The shaft angle sensor is mounted on a sensor board carried by the machine casing at the non-drive end of the rotor shaft. The sensor board can optionally act as a hub at which signals from multiple machine sensors are gathered to be placed in communication with the controller via the same electrical harness used to transmit the sensor information.