USB Load Detection Apparatus for Power Converter Frequency Control
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Solution Overview
Problem
USB power systems face slow response times due to reduced switching frequency during power saving modes, which can lead to output voltage deviations when sudden load changes occur, such as when a USB device is plugged in.
Innovation Solution
A load detection apparatus that monitors voltage changes across USB data terminals, generates a wake-up signal, and adjusts the switching frequency of the power converter by connecting a primary and secondary controller with a transformer, allowing the power converter to increase its switching frequency from a low power saving mode to a higher operational mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency is reduced during power saving mode, then energy consumption is reduced, but the response time to load changes deteriorates
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by monitoring voltage changes on USB data terminals. When a plug-in event is detected (voltage change), the system transitions from low frequency (power saving mode) to high frequency (operational mode), and vice versa when no load is detected. This dynamic adaptation resolves the contradiction by making the switching frequency flexible rather than fixed, allowing the system to optimize between energy consumption and response time based on actual load conditions.
2Loss of energy
If the switching frequency is reduced to save power, then energy efficiency is improved, but output voltage stability deteriorates during sudden load changes
Solution Approach 1:
The patent employs a feedback mechanism where the voltage change on USB data terminals is continuously monitored. When a plug-in event occurs, the detected voltage change triggers an increase in switching frequency to maintain output voltage stability. This feedback loop ensures that the system responds to load changes by adjusting operating parameters, thereby maintaining voltage stability while minimizing energy consumption during no-load periods.
3Use of energy by stationary object
If the system operates in power saving mode with low switching frequency, then power consumption is reduced, but the ability to respond to plug-in events deteriorates
Solution Approach 1:
The patent implements preliminary detection capability by continuously monitoring voltage changes on USB data terminals even in power saving mode. This preliminary detection of plug-in events allows the system to prepare for load changes by detecting the event first, then rapidly transitioning to high switching frequency operation. The monitoring circuit remains active at minimal power consumption to detect events before full power operation is required.
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
Improves the response time of the USB power system by quickly adjusting the switching frequency upon detecting a plug-in event, ensuring stable output voltage and faster load transient response.
Implementation Method 1
The transformer provides a voltage ratio from input to output. In addition, the transformer provides isolation.
Implementation Method 2
The diode rectifier is able to convert the input ac waveform to a pulsating dc waveform at the output terminals of the diode rectifier.
Implementation Method 3
A plurality of capacitors may be coupled between the two output terminals of the diode rectifier. The capacitors are used to attenuate the ripple of the pulsating dc waveform.
Implementation Method 4
When the switch is turned on, energy is stored in the winding of the transformer. The polarity dots of the transformer and the diode are arranged such that there is no energy transferred to the secondary side when the switch is on.
Data Source
AI summary
An apparatus comprises a positive data input/output terminal configured to be connected with a positive data line of a USB device, wherein the positive data input/output port is weakly pulled up to a first voltage potential through a pull-up resistor, a negative data input/output terminal configured to be connected with a negative data line of the USB device, wherein the negative data input/output terminal is connected to a second voltage potential, a window comparator having an input detecting a voltage across the two data input/output terminals and a wake-up signal generator connected to an output of the window comparator, wherein the wake-up signal generator is configured to generate a signal for adjusting a switching frequency of a power converter after the USB device is connected to the power converter.