Motor Drive Overcurrent Protection With Single Anomaly Signal Line
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Solution Overview
Problem
Conventional motor drive systems require multiple output lines for anomaly signals from overcurrent detection means, which can be impractical due to limited ports on controllers and potential connectivity issues, especially in cases of short circuits and demagnetization currents.
Innovation Solution
A motor drive system that includes a current detector, a low-pass filter, a demagnetization current determiner, and a short circuit determiner, allowing for the transmission of anomaly signals from multiple overcurrent detection means through a single output line by combining signals and comparing them against thresholds to control the inverter's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple overcurrent detection means are provided to protect the inverter, motor, and power supply, then the protection capability is improved, but the number of output lines required increases
Solution Approach 1:
The patent combines multiple anomaly signals from different overcurrent detection means (short circuit detection and demagnetization detection) into a single anomaly signal output line. The control circuit merges these signals and transmits them through one shared line to the gate drive signal generation circuit, thereby reducing the number of output lines while maintaining comprehensive protection capability.
Solution Approach 2:
The single anomaly signal output line serves multiple functions by carrying both short circuit anomaly signals and demagnetization anomaly signals. This multi-functional approach allows the system to protect against different types of overcurrent conditions through a unified signal transmission path, eliminating the need for separate dedicated lines for each detection function.
2Reliability
If multiple anomaly signal lines are used to transmit signals from multiple overcurrent detection means, then the signal transmission reliability is improved, but the port usage of the microcomputer increases
Solution Approach 1:
The patent merges multiple anomaly signals into a single output line that connects to the microcomputer through one port. The control circuit consolidates the short circuit anomaly signal and demagnetization anomaly signal onto this single line, thereby reducing microcomputer port consumption while ensuring that all critical anomaly information is transmitted reliably to the controller.
3Device complexity
If a single anomaly signal line is used to combine multiple detection signals, then the device complexity is reduced, but the signal processing complexity increases
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the multiple detection means and the output line. This control circuit performs the signal merging and processing functions, managing the complexity of combining multiple anomaly signals while presenting a simplified single-line interface to the rest of the system. The intermediary handles the signal processing complexity internally, keeping the overall system architecture simple.
Data Source
AI summary
A motor drive system includes: an inverter that drives a motor; a current detector that detects and outputs the first signal that is a current value of a current flowing through the inverter; a first low-pass filter that removes a noise frequency component from the first signal and outputs a second signal that is a current value after the noise frequency component has been removed; a demagnetization current determiner that compares a demagnetization current threshold with the second signal, and outputs a demagnetization protection signal when the second signal takes a value larger than the demagnetization current threshold; and a short circuit determiner that compares a third signal with a short circuit and outputs an anomaly signal for stopping the inverter when the third signal takes a value larger than or equal to the short circuit threshold.