USB Power Interface Mains-Loss Detection via Transformer Monitoring
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Solution Overview
Problem
USB interfaces adapted to USB-PD technology struggle to detect mains loss, leading to potential data corruption or loss when the AC voltage from the mains decreases significantly, which can cause the interface to fail in providing the negotiated power supply.
Innovation Solution
A USB interface design incorporating a transformer, switches, capacitors, and a control circuit that compares voltage thresholds to detect mains loss by monitoring the root mean square value of the AC voltage, sending alerts or requests to swap power roles between devices if necessary, ensuring data integrity and power supply continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If USB interface monitors AC voltage to detect mains loss, then data integrity is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary detection circuit that monitors the AC voltage through the transformer without directly interfering with the power conversion process. This intermediary mechanism detects mains loss by monitoring voltage thresholds while maintaining isolation between the detection system and the main power pathway, thus improving reliability without significantly increasing overall interface complexity.
Solution Approach 2:
The USB interface uses its existing transformer and voltage regulation components to perform dual functions: both power conversion and mains loss detection. The control circuit leverages the already-present voltage nodes and transformer windings to detect AC voltage levels, allowing the system to self-monitor without requiring entirely separate detection hardware, thereby minimizing additional complexity.
2Reliability
If USB interface detects mains loss and sends alerts, then power supply continuity is improved, but loss of time increases
Solution Approach 1:
The control circuit continuously monitors the AC voltage and compares it against predefined thresholds in real-time, maintaining a ready state for rapid detection of mains loss. By continuously comparing voltage levels rather than periodically checking, the system eliminates detection delay and can immediately trigger power role swapping or alerts when voltage drops below the threshold, ensuring minimal response time while maintaining power supply continuity.
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
The solution effectively detects mains loss and prevents data corruption by sending alerts or requests to swap power roles, maintaining data integrity and ensuring power supply continuity during voltage fluctuations or mains disconnection.
Implementation Method 1
a transformer, a first switch, and a primary winding of the transformer series connected between a first node and a second node
Implementation Method 2
a rectifying bridge configured to receive a second AC voltage and to provide a third voltage on the first node and a second reference voltage on the second node
Data Source
AI summary
In an embodiment, a USB interface includes a transformer, a primary winding of the transformer, and a first switch in series between a first and a second node, a secondary winding of the transformer and a component in series between a third and a fourth node, the fourth node configured to be set a first reference potential, a second switch connected between the third node and a first terminal, the first terminal configured to provide an output voltage of the USB interface; wherein the component is configured to avoid a current circulation in the secondary winding when the first switch is closed and a control circuit configured to compare a first voltage of an interconnection node between the secondary winding and the component to a first threshold and compare the first voltage to a second threshold when the first voltage is, in absolute values, above the first threshold.