Voltage Sensing Circuit Fault Identification via Current Injection
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Solution Overview
Problem
Existing voltage sensing systems in LED drivers face safety issues due to the inability to accurately identify and differentiate between faults in voltage sensing resistors and external circuit components, leading to potential overvoltage or undervoltage conditions, and require additional circuit complexity and power losses for backup solutions.
Innovation Solution
A voltage sensing circuit that performs two feedback measurements: a primary measurement using a voltage divider and a secondary measurement with current injection to determine if the fault is caused by the voltage divider or the external circuit component, utilizing a voltage clamping component to differentiate between short circuits and open circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second voltage sensing resistor and associated control circuit are used as backup, then safety is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by implementing fault detection and identification before the backup circuit is activated. The controller performs two feedback measurements (primary and secondary) to detect and identify faults in advance, determining whether the fault is in the voltage divider or external circuit component. This allows the system to take appropriate control actions (shutdown, protection mode, or alarm) before safety issues arise, eliminating the need for a complete backup circuit while maintaining safety.
Solution Approach 2:
The patent introduces an intermediary measurement approach by adding a secondary feedback measurement path that acts as a mediator between the primary voltage sensing and the controller. This secondary measurement, combined with the primary measurement, provides sufficient information to identify fault conditions without requiring a full backup circuit. The intermediary measurement helps the controller distinguish between different fault types (voltage divider fault vs. external component fault) and respond appropriately.
2Reliability
If a second voltage sensing resistor and associated control circuit are used as backup, then safety is improved, but power losses increase
Solution Approach 1:
The patent applies preliminary action by detecting and identifying faults before they cause safety issues. The dual feedback measurement system continuously monitors voltage divider and external component conditions, allowing the controller to take preventive actions (shutdown, protection mode, or alarm) before unsafe conditions develop. This eliminates the need for a backup circuit that would continuously consume power, thereby reducing power losses while maintaining safety through proactive fault detection.
Solution Approach 2:
The patent implements self-service by enabling the voltage sensing circuit to self-diagnose and self-identify fault conditions using the dual feedback measurement approach. The controller uses the primary and secondary measurements to automatically determine the fault location and type, then autonomously responds with appropriate control actions. This self-service capability eliminates the need for a separate backup circuit, reducing power consumption while maintaining safety through intelligent fault detection and response.
3Device complexity
If only a single voltage feedback measurement is used, then device complexity is reduced, but the ability to identify fault causes is worsened
Solution Approach 1:
The patent applies another dimension by adding a second feedback measurement dimension to the single voltage measurement approach. Instead of relying on one measurement point, the system uses two distinct feedback measurements (primary voltage feedback and secondary measurement) to gather sufficient information for fault identification. This dimensional expansion allows the controller to distinguish between different fault types (voltage divider fault vs. external component fault) without significantly increasing circuit complexity, as the second measurement is integrated into the existing feedback path.
Solution Approach 2:
The patent introduces an intermediary measurement as a mediator that provides additional information about the fault condition. The secondary feedback measurement acts as an intermediary that, when combined with the primary measurement, enables the controller to identify the root cause of the fault. This intermediary measurement does not require a complete backup circuit but provides the necessary information to make informed control decisions, thereby reducing information loss while maintaining reasonable circuit complexity.
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
Enables accurate identification of fault causes, preventing unsafe conditions and reducing circuit complexity and power losses by distinguishing between different fault modes, allowing for appropriate control actions such as short circuit protection or shutdown.
Implementation Method 1
a voltage divider including first and second resistors in series, connected in parallel with the circuit component and between the first terminal (12) and the second terminal (14), wherein a sensing terminal between the first and second resistors is for providing a sense signal that is able to indicate the voltage across the circuit component
Implementation Method 2
a voltage clamping component (D1) coupled from the sensing terminal to the external circuit component
Implementation Method 3
a current injector for injecting current to the sensing terminal
Data Source
AI summary
A voltage sensing circuit uses a voltage divider for providing a sense signal indicating the voltage across a circuit component. A current injector is used for injecting current to the sensing terminal. A sense signal is obtained with no current injection, to determine if a fault is present. The sensing terminal is coupled to the external circuit component via a voltage clamping component. A further sense signal is obtained in response to the injection of current. By comparing the sense signal in response to the injected current and a clamping voltage of the voltage clamping component, it can then be determined if the fault is caused by the circuit component or by the voltage divider.