AC Power Measurement via Thermal Equilibrium
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Solution Overview
Problem
Existing methods for determining power values in AC circuits face challenges in achieving accurate measurements due to factors like self-heating of components, phase differences, and the presence of higher harmonics, leading to reduced accuracy and increased uncertainties.
Innovation Solution
The approach involves transforming AC power into heat and measuring power dissipation using a thermally coupled DC circuit, where a balancing unit controls the DC power source based on thermal parameters to achieve thermal equilibrium, allowing for real-time determination of AC power values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If AC voltage and current are measured and multiplied to acquire instantaneous power, then power measurement can be performed in real-time, but measurement accuracy is reduced due to phase differences, higher harmonics, and ADC sampling limitations
Solution Approach 1:
The patent introduces a thermal intermediary system (heat sink, temperature sensor) as a mediator between the AC circuit and measurement system. Instead of directly measuring electrical parameters, the system converts AC power dissipation into thermal energy and measures the resulting temperature change. This thermal mediation eliminates the problems of phase differences and harmonics, providing accurate real-time power measurement without ADC sampling limitations.
Solution Approach 2:
The patent replaces the electrical measurement system (ADC, voltage/current sensors) with a thermal measurement system. By substituting electrical measurement with thermal measurement, the system avoids the limitations of high-speed ADC sampling and phase difference compensation, achieving accurate power measurement through temperature-based detection.
2Measurement precision
If additional circuits are added for filtering and error compensation, then measurement accuracy can be improved, but circuit uncertainty and complexity increase
Solution Approach 1:
The patent replaces complex electrical filtering and compensation circuits with a simple thermal measurement system. The thermal system naturally averages power dissipation over time, eliminating the need for separate filtering circuits. This substitution dramatically reduces device complexity while maintaining or improving measurement accuracy.
3Measurement precision
If DC and AC measurements are compared sequentially using temperature increase, then power characterization can be achieved, but real-time accuracy is limited due to changing thermal models and self-heating
Solution Approach 1:
The patent implements continuous real-time temperature monitoring and power calculation, rather than sequential DC then AC measurements. The system continuously measures temperature increase and calculates instantaneous AC power dissipation, maintaining uninterrupted measurement capability. This continuous action ensures reliability even as thermal conditions change, as each measurement is based on current temperature data.
Solution Approach 2:
The patent uses real-time temperature feedback to continuously update power calculations. The temperature sensor provides continuous feedback about the thermal state, which is immediately used to calculate current power dissipation. This feedback mechanism ensures that measurements remain accurate despite changing thermal conditions or self-heating effects.
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 method provides accurate and fast power measurements, even in time-varying or periodic systems, by isolating DC and AC power dissipation measurements, thereby improving measurement accuracy and reliability.
Implementation Method 1
measuring a power dissipation, in particular by measuring a temperature increase of a power sink
Implementation Method 2
at least one heat sink which is thermally coupled between the DC circuit and the target AC circuit
Data Source
AI summary
An apparatus and a method for determining a power value of a target in the form of an AC circuit (130; 230; 330) having an AC power source (132; 232; 332). The method involves operating (72) a controllable DC power source (12) to provide DC power to a DC circuit (10; 110; 210; 310) and measuring (73) at least one thermal parameter related to power dissipation of the DC circuit (10; 110; 210; 310) and of the target AC circuit (30; 130; 230; 330), wherein at least one heat sink (160a, 160b; 260; 360) is thermally coupled between the DC circuit (10; 110; 210; 310) and the target AC circuit (30; 130; 230; 330). The method further involves controlling (74) the DC power source (12) based on the measured at least one thermal parameter to reduce a difference in power dissipation between the DC circuit (10; 110; 210; 310) and the target AC circuit (30; 130; 230; 330). The method then involves, when thermal equilibrium is reached (75), determining the power value (49) of the target AC circuit (30; 130; 230; 330) by retrieving (76) at least one real-time measurement of at least one electric parameter of the DC circuit (10; 110; 210; 310), calculating (77) a DC power value of the DC circuit (10; 110; 210; 310) based on the retrieved at least one real-time measurement of the at least one electric parameter, and calculating (78) the power value (49) of the target AC circuit (30; 130; 230; 330) using the calculated DC power value.