PWM Power-and-Data Transmission Over Twisted Pair Lines
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Solution Overview
Problem
Existing power and data transmission methods over twisted pair wiring face challenges in efficiently delivering power while simultaneously transmitting data without interfering with the power delivery, particularly in scenarios where constant power levels are required.
Innovation Solution
The use of pulse-width modulation (PWM) signals with varying frequencies to transmit data while maintaining a constant duty cycle for power delivery, allowing devices to receive power and data on the same line without disrupting the power level, and the implementation of impedance alteration to detect changes in operating frequencies for data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power and data are transmitted over the same twisted pair line, then the complexity of wiring is reduced, but interference between power delivery and data transmission occurs
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation (PWM) to deliver power in periodic pulses rather than continuous DC. The PWM signal alternates between high and low states at a specific frequency, creating periodic power delivery that allows data to be transmitted during the low-power intervals. This periodic structure resolves the interference problem while maintaining power delivery over the same twisted pair line used for data communication.
Solution Approach 2:
The patent segments the power and data transmission functions by assigning different time slots or frequency bands. During high-power PWM intervals, power is delivered; during low-power intervals, data transmission occurs. This temporal segmentation allows both functions to coexist on the same physical medium without significant interference, reducing wiring complexity while avoiding electromagnetic conflict.
2Power
If pulse-width modulation is used to regulate power, then power delivery is controlled, but data transmission becomes difficult due to varying average power
Solution Approach 1:
The patent introduces an intermediary mechanism where a coupling capacitor is used to block the PWM frequency components while allowing data signals to pass. The capacitor couples the data signal from the load to the controller while blocking the high-frequency PWM switching signals. This intermediary element enables simultaneous power regulation via PWM and accurate data transmission without the varying average power of PWM interfering with data integrity.
3Loss of information
If frequency variation is used to transmit data, then data communication is enabled, but power level stability is compromised
Solution Approach 1:
The patent uses periodic PWM action with a fixed duty cycle to maintain stable average power delivery while allowing frequency variations for data encoding. The PWM frequency is chosen to be significantly higher than the data transmission frequency, ensuring that power stability is maintained at the fundamental frequency while higher-frequency variations carry data information. This resolves the contradiction by separating the timescales of power regulation and data communication.
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 efficient and reliable transmission of both power and data over a single twisted pair line, maintaining constant power levels while allowing for bidirectional communication without additional power loss, making it suitable for applications like LED lighting control.
Implementation Method 1
The circuit may also be configured to set a duty cycle of the pulse-width modulated signal in order to transmit a determined power level to the device
Implementation Method 2
The control device may, in order to receive the information, detect a change in an operating frequency of the power converter created in response to the impedance added to the line
Data Source
AI summary
In one embodiment, an apparatus includes a circuit coupled to a line, where the circuit may power a device, and where the power is transmitted to the device over the line as a pulse-width modulated signal. The circuit may set a duty cycle of the pulse-width modulated signal in order to transmit a determined power level to the device. The apparatus may vary a frequency of the pulse-width modulated signal to transmit data to the device while the duty cycle of the pulse-width modulated signal is fixed in order to continue to transmit the determined power level to the device. A variation in the frequency of the pulse-width modulated signal may be detectable by the device and represents at least a portion of the data.