Precision Voltage Drop Measurement for Semiconductor Switching Elements
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Solution Overview
Problem
Existing methods for measuring voltage drop across semiconductor switching elements, such as IGBTs in subsea applications, lack precision due to uncertainty in diode voltage drop measurement, which affects the accuracy of determining IGBT aging and predicting its lifetime.
Innovation Solution
An apparatus with two identical circuit paths and a regulating circuit that ensures equal current flow through both paths, allowing for precise measurement of the voltage drop across the semiconductor switching element by including the voltage drop across the protective element in the measurement, using identical protective and impedance elements to maintain consistent electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode is inserted to protect the measurement circuit from high voltage, then the measurement circuit is protected, but the voltage drop across the diode introduces measurement uncertainty and reduces precision
Solution Approach 1:
The patent introduces a compensating circuit as an intermediary system that includes identical protective elements (diodes) and impedance elements (resistors) to measure and compensate for the voltage drop introduced by the protective diode in the main measurement path. This mediator circuit allows the system to account for and eliminate the measurement error caused by the protective diode's voltage drop.
Solution Approach 2:
The patent changes the measurement parameter from directly measuring the voltage across the IGBT to measuring the voltage across identical components in a compensating circuit that operates under the same conditions. By measuring the voltage drop across identical resistors and diodes in the compensating path, the system transforms the measurement into a differential measurement that eliminates the uncertainty of the protective diode's voltage drop.
2Ease of manufacture
If a voltage source with series resistor is used instead of a current source, then the measurement circuit is more available and easier to implement, but the voltage drop across the protective diode cannot be measured directly, reducing measurement precision
Solution Approach 1:
The patent creates a compensating circuit that is an exact copy of the measurement path, including identical protective diodes and impedance elements. By copying the entire measurement path and measuring the voltage drop in this identical circuit under the same current conditions, the system can accurately determine and compensate for the voltage drop introduced by the protective elements without needing to measure it directly in the main path.
Solution Approach 2:
The compensating circuit acts as an intermediary that provides indirect measurement of the voltage drop across protective elements. Instead of trying to measure the voltage drop directly in the main path (which would require breaking the circuit or adding measurement points), the intermediary compensating circuit provides a safe and accurate way to determine this voltage drop through voltage division and differential measurement.
3Device complexity
If the voltage drop across the protective diode is not included in the measurement, then the measurement circuit is simpler, but the precision is insufficient to determine IGBT aging
Solution Approach 1:
The compensating circuit with identical protective and impedance elements serves as an intermediary measurement system that captures the voltage drop across protective elements without complicating the main measurement path. This intermediary approach allows precise determination of the protective element voltage drop, which can then be subtracted from the total voltage measurement to obtain the accurate IGBT voltage drop for aging determination.
Solution Approach 2:
The patent segments the voltage measurement into two separate components: the voltage drop across protective elements and the voltage drop across the IGBT. By using the compensating circuit to measure the protective element voltage drop separately and then subtracting it from the total voltage measurement, the system achieves precise segmentation of the measurement, enabling accurate IGBT aging determination.
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 approach provides a precise measurement of the voltage drop across the semiconductor switching element, enabling accurate determination of IGBT aging and predicting its remaining lifetime, thus allowing for timely maintenance in subsea applications.
Implementation Method 1
a first protective element, a first impedance element and a voltage source, wherein the first circuit path is adapted to be connected between the first terminal and the second terminal of the semiconductor switching element
Implementation Method 2
a first impedance element and a voltage source, wherein the first circuit path is adapted to be connected between the first terminal and the second terminal of the semiconductor switching element
Data Source
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AI summary
There is described an apparatus for precision measurement of voltage drop across a semiconductor switching element. The apparatus comprises (a) a first circuit path comprising a first protective element, a first impedance element and a voltage source (Vs), wherein the first circuit path is adapted to be connected between the first terminal and the second terminal of the semiconductor switching element, (b) a second circuit path formed between a first output terminal (211) and a second output terminal (212), the second circuit path comprising a second protective element and a second impedance element, wherein the second protective element is identical to the first protective element, and wherein the second impedance element is identical to the first impedance element, and (c) a regulating circuit for regulating the current in the second circuit path such that said current in the second circuit path is equal to the current in the first circuit path, wherein the voltage drop (Vce) between the first terminal and the second terminal of the semiconductor switching element equals the difference between the voltage provided by the voltage source (Vs) and the voltage drop (Vm) between the first output terminal (211) and the second output terminal (212). Furthermore, there is described a subsea device, a monitoring system and a method.