Multiport USB Adapter Current Measurement via Segmented Sense Resistors
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Solution Overview
Problem
Multiport power adapters face challenges in accurately measuring load current across multiple ports due to shared common ground among connected devices, leading to inaccurate current measurement and increased system complexity, cost, and reduced efficiency.
Innovation Solution
A system and method that utilize a combination of low side and high side current sense methods, implemented through a system controller interacting with AC-DC and buck-boost mode power conversion units via digital interfaces, to measure and adjust load currents on each USB port, eliminating the need for additional current sense resistors and simplifying calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current sense methods are used in multiport power adapters, then current measurement can be achieved, but system complexity increases and measurement accuracy deteriorates due to shared common ground
Solution Approach 1:
The patent segments the current measurement function into separate measurement paths for each USB port. Each port has its own current sense resistor and measurement circuitry, allowing independent current measurement without interference from other ports. This segmentation resolves the common ground issue by creating isolated measurement loops for each port.
Solution Approach 2:
The patent introduces separate current sense resistors as intermediary elements between each USB port and the common ground. These resistors act as mediators that enable accurate current measurement by creating distinct voltage drops that can be measured independently, despite the shared ground connection. The intermediary resistors isolate the measurement function from the common ground interference.
2Measurement precision
If multiple current sense resistors are used for each port, then current measurement accuracy improves, but manufacturing cost increases
Solution Approach 1:
The patent uses exactly one current sense resistor per USB port, segmenting the measurement function minimally but effectively. This approach achieves accurate current measurement for each port without the need for multiple resistors per port, thereby controlling manufacturing costs while maintaining measurement precision.
3Measurement precision
If complex current measurement methods are implemented, then measurement capability is achieved, but power conversion efficiency decreases
Solution Approach 1:
The current sense resistors are integrated into the existing power path of each USB port, allowing the measurement function to be provided by the same components that carry the load current. This self-service approach eliminates the need for separate measurement circuits that would add complexity and potential energy losses, maintaining power conversion efficiency while achieving accurate current measurement.
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 approach provides accurate, reliable, and efficient load current measurement across multiple ports, reducing system costs and improving power conversion efficiency while ensuring safe operation by eliminating issues associated with common ground connections.
Implementation Method 1
The system controller is configured to measure the first load current by means of a low side current sense method, and the one or more second load currents by means of a high side current sense method
Data Source
AI summary
The present disclosure provides a system and method including: a first USB port and one or more second USB ports provided on the multi-port adapter; an AC-DC conversion configured to measure a first load current at the first USB port; a plurality of buck-boost mode power conversion units, each configured to measure a second load current at a corresponding one or more second USB ports; and a system controller configured to measure the first load current and the one or more second load currents, wherein the system controller is configured to compare and adjust the measured first load current and the measured one or more second load currents to, respectively, a first rated current and a corresponding second rated current for each of the one or more second USB ports.