Current Supervisory Circuit With Modulated Overcurrent Reporting
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Solution Overview
Problem
Existing current sensors fail to reliably detect and report overcurrent events due to electromagnetic interference and lack of failure diagnosis in electronic control units.
Innovation Solution
A current supervisory device that uses a modulated signal to report the detection of overcurrent events by modulating the reporting signal based on event detection, with parameters such as pulse width and frequency, allowing for reliable communication even in the presence of interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a digital output signal is used to report overcurrent events, then the communication is simple and clear, but the system becomes sensitive to electromagnetic interference and cannot diagnose reporting unit failures
Solution Approach 1:
The patent applies periodic action by using a modulated carrier signal with a specific frequency (e.g., 1 kHz square wave) to transmit the overcurrent status. Instead of sending a static digital level, the system periodically switches the output between high and low states according to the carrier frequency, making the signal inherently more robust against electromagnetic interference while maintaining clear binary information transmission.
Solution Approach 2:
The patent changes the parameter of the output signal from a simple digital voltage level to a modulated signal characterized by frequency and duty cycle. The modulated output stage varies the duty cycle of the carrier signal based on the overcurrent status (e.g., 50% duty cycle for normal, 0% or 100% for fault), transforming a vulnerable digital signal into a resilient modulated waveform that resists electromagnetic interference.
2Device complexity
If a digital output signal is used to report overcurrent events, then the communication protocol is simple, but the electronic control unit cannot diagnose failures in the reporting unit
Solution Approach 1:
The patent implements feedback by using the same modulated carrier signal approach for both normal operation reporting and fault indication. The electronic control unit can detect whether the supervisory device is functioning properly by analyzing the presence and characteristics of the modulated signal. If the carrier signal is absent or abnormal, the ECU can diagnose a failure in the reporting unit, enabling self-diagnosis without complicating the communication protocol.
3Object-affected harmful factors
If modulation is applied to the reporting signal, then electromagnetic interference resistance improves, but the device complexity increases
Solution Approach 1:
The patent merges the modulation function with the existing output stage of the supervisory device. The modulated output stage combines the carrier signal generation and the status encoding into a single integrated circuit block, eliminating the need for separate modulation components. This integration achieves electromagnetic interference resistance while minimizing the increase in device complexity through functional consolidation.
Data Source
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AI summary
The present invention relates to a current supervisory device (1) comprising : - current sensing means (3) for sensing a current, - a circuit (5) arranged to convert a signal (4) received from the current sensing means into a signal (6) indicative of the sensed current, - a processing circuit (9) arranged to receive the signal (6) indicative of the sensed current, to detect an event based on the received signal (6), said detecting yielding an outcome corresponding to one of at least two different states, and to generate an event signal in accordance with the outcome, said processing circuit comprising modulation means for performing modulation based on the event signal, - an output terminal (10) arranged to output a reporting signal (12) received from said processing circuit, whereby at least one of at least two different states gives rise to said reporting signal being a modulated signal.