Self-Powered Power Sensor Thermal Management via Dynamic Duty Cycle
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Solution Overview
Problem
Existing non-intrusive power measurement systems face challenges in accurately measuring low currents across multiple circuit breakers, particularly in noisy environments, and suffer from overheating issues due to inefficient energy transformation, which can lead to safety hazards.
Innovation Solution
A self-powered power sensor system that uses a current transformer to measure power consumption, integrates energy harvesting, and employs a microcontroller with a radio frequency transceiver for wireless communication, along with a temperature sensor to prevent overheating, allowing for precise power monitoring across a range of currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a self-powered sensor harvests energy from the magnetic field to operate, then the sensor can function autonomously without external power, but the heat dissipation increases and may cause overheating in confined spaces
Solution Approach 1:
The sensor operates in periodic cycles, alternating between energy harvesting mode and measurement mode. During energy harvesting, the sensor draws power from the magnetic field; during measurement, it uses stored energy. This periodic operation allows thermal management by distributing heat generation over time rather than continuous operation, preventing overheating while maintaining autonomous functionality.
2Adaptability or versatility
If the sensor operates over a large current range (0.5A to 250A), then the measurement capability is enhanced, but the heat dissipation and overheating risk increase significantly
Solution Approach 1:
The sensor dynamically adjusts its operating parameters based on the detected current level. For low currents (0.5A-25A), it uses one set of measurement parameters; for high currents (25A-250A), it switches to different parameters optimized for high-current detection. This dynamic adaptation allows the sensor to maintain measurement accuracy across the full current range while minimizing heat generation by using appropriate measurement strategies for each current level.
3Ease of operation
If wireless telemetry is implemented for power consumption measurement, then remote monitoring capability is provided, but the sensor performance degrades in noisy electromagnetic environments
Solution Approach 1:
The wireless communication system implements feedback mechanisms to detect and correct transmission errors caused by electromagnetic noise. The sensor monitors signal quality and adjusts transmission parameters accordingly, such as increasing transmission power or using error correction codes, thereby maintaining reliable communication in noisy environments while preserving remote monitoring functionality.
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 accurate, non-intrusive power measurement across a wide range of currents while preventing overheating, ensuring safety and efficient operation in noisy environments with improved communication and data transmission capabilities.
Implementation Method 1
A current transformer (CT) of sorts is created that comprises the primary winding as the power line conductor and the secondary providing an output current inversely proportionate to the number of windings
Implementation Method 2
The energy is harvested from the magnetic field and is used for the operation of the sensor
Implementation Method 3
a temperature sensor to prevent overheating
Data Source
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Figure 3~4
Figure 5
AI summary
Apparatus and methods are provided for handling the heating resulting from the operation of a self-powered power sensor (SPPS). The SPPS periodically switches between a sense mode and a harvest mode, each contributing to power dissipation that translates into heat, which may become a safety hazard. A duty cycle that is the ratio between the period in which sensing take place and the total time elapsed between sensing periods defines the duty cycle of the SPPS. In order to prevent overheating of the SPPS it is configured to provide a dynamic duty cycle that is higher for lower currents in the primary power wire and lower, for higher primary currents. This allows for better power dissipation of the SPPS and removing it from operation in unfavorable or dangerous conditions.