Motor Drive Data Transmission via Shielded Cable
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Solution Overview
Problem
Existing drive systems for electric motors powered by converters via supply cables face challenges in efficient data transmission due to interference from switching events and energy signal changes, which can disrupt communication and require complex cabling setups.
Innovation Solution
A system where signal electronics on both the motor and converter sides use a shielded supply cable to transmit data during interference-free periods, determined by predicting switching events, allowing for bit-serial digital protocols with time stamps for error-free communication, and using the same cable for both power and data signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is transmitted via the supply cable during switching events, then data transmission can be continuous, but interference from switching events disrupts communication reliability
Solution Approach 1:
The converter-side signal electronics predict future switching events and proactively identify interference-free time windows before they occur. Query signals are generated and transmitted in advance during these predicted safe periods, ensuring data transmission occurs before interference arises rather than attempting to transmit during or after switching events.
Solution Approach 2:
The system converts the deterministic nature of switching events from a harmful interference source into a useful timing reference. By predicting switching events, the system identifies regular interference-free periods that can be systematically utilized for data transmission, turning the predictable interference pattern into a structured communication schedule.
2Reliability
If separate communication cables are used for data transmission, then communication reliability is improved, but system complexity and cabling cost increase
Solution Approach 1:
The system merges power transmission and data communication functions into a single supply cable. By using the existing power cable for both energy delivery and digital signal transmission, the invention eliminates the need for separate communication cables, reducing system complexity and installation cost while maintaining reliable communication through interference-aware timing.
Solution Approach 2:
The supply cable is designed to perform multiple functions simultaneously: it serves as both the power transmission medium for the motor and the communication channel for digital data exchange. This multi-functionality is achieved through careful signal modulation and timing selection, allowing the same physical infrastructure to support both high-power energy delivery and precise digital communication.
3Productivity
If data transmission occurs during switching events, then transmission rate can be high, but interference signals cause errors in data transmission
Solution Approach 1:
The system performs preliminary prediction of switching events to identify future interference-free time windows. By scheduling data transmission in advance during these predicted safe periods, the system ensures high-rate communication occurs before interference arises, rather than attempting to filter or recover data transmitted during high-interference periods.
Solution Approach 2:
The system skips over the high-interference periods caused by switching events and rushes data transmission through the identified interference-free time windows. By rapidly transmitting complete data packets during these brief safe periods and immediately pausing before the next switching event, the system maintains high effective transmission rates while avoiding error-prone communication during interference.
Data Source
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AI summary
The invention relates to a system and a method for operating a system, comprising an electric motor fed by a frequency converter via a connecting cable. Arranged on said motor are a signal electronics system, located on the motor side, and at least one sensor, the signals of said sensor being transmitted via the connecting cable to a signal electronics system on the frequency converter side. Said signal electronics system on the frequency converter side has a means for determining the times of switching occurrences, in particular of the controllable switches of the frequency converter and/or the controllable switches of the brake control. Said signal electronics system on the frequency converter side also has a means for generating an interrogation signal which is only sent when a sufficiently long noise-free period of time for the transmission of a protocol can be expected between said times. The signal electronics system on the motor side has a means for transmitting a protocol, said protocol containing information comprising a respective measured value detected by the sensor.