BAS Controller USB Port Power Management
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Solution Overview
Problem
Building automation system (BAS) controllers face challenges in managing power distribution to USB peripherals, leading to unpredictable operating states and potential overloading, as they cannot anticipate the types of devices connected during product design.
Innovation Solution
A BAS controller with a USB hub and primary controller that independently powers USB ports, using a known device table to determine current draw and remove power from unused ports when the total current exceeds a threshold, ensuring the system operates within a predefined power budget.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the BAS controller imposes a current limit on an attached peripheral, then power consumption is controlled within budget, but the peripheral may operate in an unintended manner
Solution Approach 1:
The system performs preliminary identification of USB devices and calculates their power requirements before actually connecting them to the power bus. The controller reads device descriptors, determines current draw requirements, and pre-calculates whether the total power budget would be exceeded before enabling power to any port. This prevents peripherals from operating in unintended states by ensuring power is only provided when safe.
Solution Approach 2:
The patent introduces an intermediary power control mechanism between the power supply and USB ports. A controllable switch (power control circuit) acts as a mediator that can independently enable or disable power to each USB port based on device identification and power budget calculations. This intermediary layer prevents direct power imposition that could cause unreliable peripheral operation.
2Use of energy by moving object
If the BAS controller power supply enters protected mode, then power consumption is controlled within budget, but the device enters a reduced function state
Solution Approach 1:
The system performs preliminary power budget calculations before entering any protected mode. By identifying all connected USB devices and summing their current draw requirements in advance, the controller can determine whether power budget constraints exist before activation. This prevents the power supply from entering protected mode that would reduce device functionality, as power allocation is optimized beforehand.
Solution Approach 2:
The patent implements dynamic power allocation where the controller can independently control power delivery to each USB port based on real-time device identification and power budget status. Rather than a static protected mode that uniformly reduces all functions, the system dynamically adjusts power distribution, enabling full functionality for devices within budget while restricting only those that would cause overload.
3Reliability
If the BAS controller proactively manages power by removing power from unused ports when current exceeds threshold, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the power management function into independent, modular components: a USB hub with independently controllable ports, a power control circuit for each port, and a central controller that manages device identification and power allocation. This segmentation allows the system to achieve reliable power management by treating each USB port as an independent controllable unit rather than a monolithic system.
Solution Approach 2:
The controller automatically performs device identification, current draw calculation, and power allocation decisions without external intervention. The system services itself by monitoring its own power budget status and autonomously enabling or disabling ports as needed. This self-service approach manages the inherent complexity through automation rather than manual control mechanisms.
Data Source
AI summary
A building automation system (BAS) controller includes a power supply, a primary controller, and plurality of USB ports for connection to a set of supported peripherals. The primary controller identifies the inserted USB device type and, based on device type, estimates a current draw of the USB device. The total estimated current draw of all inserted USB devices is added to the current draw of the primary controller and compared to the available capacity of the power supply. If the combined current draw is above a threshold, any remaining USB ports in which no USB devices are inserted are deactivated, thereby preventing the use of further USB devices. In embodiments, the BAS controller includes an auxiliary peripheral device power interface, and the total current of connected auxiliary peripheral devices is included in the combined current determination. A user interface coupled to the BAS controller displays power allocation status.