Single Current Sensor for Inverter AC Ripple Measurement
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Solution Overview
Problem
The existing methods for measuring AC current in inverters require two current sensors, which are expensive and inefficient, despite providing accurate sampling of high-frequency ripples in AC currents.
Innovation Solution
A method and circuit that utilize a single current sensor to generate a signal based on the sum of AC currents flowing in both lines, allowing for accurate sampling of high-frequency ripples during both half-periods of the AC current, thereby reducing costs and maintaining sampling accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two current sensors are used to accurately sample high-frequency ripples in both lines, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the measurement functions of both lines into a single current sensor placed in the second line. By measuring the combined current (i2 = iL2 - iL1) that contains ripple information from both lines, the system achieves accurate sampling of high-frequency ripples without requiring two separate sensors, thus reducing device complexity while maintaining measurement precision
Solution Approach 2:
The single current sensor in the second line serves multiple functions: it measures the current in line 2 directly and simultaneously captures the ripple information from both line 1 and line 2 through the combined current path. This multi-functional approach eliminates the need for separate sensors while maintaining comprehensive measurement capability
2Measurement precision
If two current sensors are deployed to measure AC current in both lines, then measurement completeness is improved, but cost increases
Solution Approach 1:
The patent merges the measurement capability into a single sensor by utilizing the fact that the combined current in line 2 (i2 = iL2 - iL1) contains ripple components from both lines. This combining approach allows one sensor to capture information that would otherwise require two sensors, reducing the quantity of components while maintaining measurement completeness
Solution Approach 2:
The second line acts as an intermediary that carries combined current information from both lines. By placing the current sensor in this intermediary path, the system can indirectly measure ripple information from both line 1 and line 2 through a single measurement point, reducing the number of sensors 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
The proposed solution allows for accurate measurement and control of AC current generation using a single current sensor, reducing costs while maintaining high accuracy and efficiency in acquiring values indicative of the AC current.
Implementation Method 1
a first current sensor (60) operatively associated to the first and second lines (51, 52) and adapted to generate an output signal (S) as a function of the sum between the AC current (I1, I2) flowing in the first and second lines (51, 52)
Data Source
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AI summary
A method for acquiring values indicative of an AC current generable by an inverting stage of an inverter comprising: - an output stage adapted to be operatively connected to one or more AC grids or loads; - at least a first line and a second line for providing a path for said AC current between the inverting stage and the output stage; - a current sensor operatively associated to the first and second lines and configured in such a way to generate a signal as a function of the sum between the AC current flowing in the first line and the AC current flowing in the second line. The method comprising: - driving the inverting stage for generating the AC current in such a way that the AC current, while flowing in said first line, comprises a first high-frequency upple during a first-half of the current period, and in such a way that said AC current, while flowing in the second line, comprises a second high-frequency upple during a second-half of the current period; - generating through the sensor a signal as a function of the sum between the AC current flowing in said first line and the AC current flowing in the second line; and - sampling values of the generated signal during the first and second half periods.