Power Cable Fault Detection via Communication-Line Voltage Sensing
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Solution Overview
Problem
Existing power conversion and transmission systems fail to correctly detect a short circuit in the current sensing resistor, leading to inadequate overcurrent protection.
Innovation Solution
The system includes a power provider unit with a path switch controlled by a gate voltage, and a method to detect electrical characteristics at the terminals connected to the cable, allowing for the determination of overcurrent or short-circuit conditions in the current sensing resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current sensing resistor RCS is used to detect bus current, then the overcurrent protection mechanism can be activated when bus current exceeds threshold, but if the current sensing resistor RCS is short-circuited, the system cannot correctly detect the short circuit condition even when overcurrent occurs
Solution Approach 1:
The patent introduces a communication sub-cable as an intermediary to detect overcurrent conditions. Instead of relying solely on the current sensing resistor, the system uses the communication sub-cable to sense voltage changes caused by voltage drops across the power sub-cable during overcurrent events. This intermediary detection path allows the system to identify overcurrent conditions even when the current sensing resistor is short-circuited.
Solution Approach 2:
The patent replaces the direct electrical measurement method (using current sensing resistor voltage) with an indirect detection method based on voltage level sensing through the communication sub-cable. This substitution allows the system to detect overcurrent conditions through voltage changes in the communication line rather than directly measuring current through the sensing resistor.
2Ease of operation
If the provider control circuit relies on current sensing signal voltage to detect overcurrent, then the protection mechanism can function normally under normal conditions, but it fails to detect short circuit of the current sensing resistor
Solution Approach 1:
The communication sub-cable is given a dual function: it serves both as a communication channel and as a sensing path for detecting overcurrent conditions. By making the communication sub-cable multi-functional, the system gains an additional detection path that can identify overcurrent events even when the primary current sensing method fails due to resistor short-circuit.
Solution Approach 2:
The system implements feedback by continuously monitoring the voltage level at the provider-end communication node. This feedback mechanism allows the provider control circuit to detect changes in voltage that indicate overcurrent conditions, creating a closed-loop detection system that can respond to faults even when the primary sensing path is compromised.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables reliable detection of overcurrent and short-circuit conditions, ensuring appropriate protection mechanisms are initiated, thereby enhancing system safety and reliability.
Implementation Method 1
a charge pump circuit for generating a gate voltage; a provider control circuit for controlling the power conversion circuit and generating an output control signal to control the charge pump circuit
Implementation Method 2
the path switch comprises an N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor); controlled by the gate voltage, for turning on or off the electrical connection
Implementation Method 3
at determination time point, the provider control circuit senses a present voltage level of the provider-end communication node
Data Source
AI summary
A power conversion and transmission system includes a power provider unit, a load unit and a cable. The power provider unit includes a power conversion circuit for converting an input power into an intermediate power, and a path switch coupled between the intermediate power and a bus power. The cable includes a power sub-cable, a communication sub-cable, and a ground sub-cable, for coupling the provider-end power, communication, and ground nodes of the power provider unit respectively to the corresponding nodes of the load unit. At an initial time point, voltage the of the provider-end communication node is sensed and recorded as the initial voltage level. At a determination time point, if the difference between the present voltage level of the provider-end communication node and the initial voltage level exceeds a threshold value, a power source limiting operation is initiated.