Active Diode MOSFET Testing Across Dual Set Voltages
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Solution Overview
Problem
Existing methods for testing field effect transistors (FETs) used as active diodes in power supply devices fail to provide reliable results when multiple devices are connected in parallel, leading to incorrect detection of functioning FETs as defective due to matched voltage levels.
Innovation Solution
A method involving two voltage drop measurements at different set voltages is employed to detect defects in FETs, using threshold values to distinguish between normal operation and potential failures, including a random component to prevent synchronized measurements in redundant systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single voltage drop measurement is performed at a fixed set voltage to test FET functionality, then the test method is simple and quick, but reliable detection of FET defects cannot be ensured in parallel power supply configurations due to matched voltage levels
Solution Approach 1:
The test method dynamically changes the set voltage of the power supply unit to at least two different values during the testing process. This dynamic voltage variation allows the system to differentiate between FET defects and normal parallel operation conditions, where voltage matching between redundant power supply devices would otherwise cause false defect detections.
Solution Approach 2:
The method changes the operating parameter (set voltage) of the power supply unit during testing. By measuring voltage drops at multiple different voltage levels, the system can identify FET defects through characteristic patterns that differ from normal operation, thereby improving detection reliability without requiring complex additional hardware.
2Reliability
If multiple power supply devices are connected in parallel for redundant operation, then system reliability and current capacity are improved, but FET defect detection becomes unreliable due to matched voltage levels causing false positives
Solution Approach 1:
The power supply unit dynamically adjusts its set voltage during the testing phase, allowing the system to create measurable voltage differentials even in parallel redundant configurations. This dynamic adjustment enables accurate FET defect detection while maintaining the beneficial parallel operation for redundancy and current capacity.
Solution Approach 2:
The testing procedure is performed as a preliminary action before the power supply device is put into normal redundant operation. By conducting voltage drop measurements at multiple voltage levels during this preliminary test phase, the system can identify and flag potential FET defects before they affect the reliability of the redundant power supply configuration.
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
Ensures reliable detection of FET defects, reducing power losses and ensuring safe operation by preventing misidentification of functioning FETs as defective, even in parallel and redundant power supply configurations.
Implementation Method 1
If a suitable field effect transistor, in particular a MOSFET transistor (metal oxide FET) is used, contact resistances in the range of milliohms can be achieved in the conducting state, whereby the voltage drop can be reduced to a few millivolts (mV) or a few 10 mV and the power dissipation can be reduced accordingly
Implementation Method 2
a first value of a voltage drop across a switching path of the field effect transistor is measured at a first set voltage of the power supply unit
Data Source
AI summary
The invention relates to a method for checking at least one field effect transistor (11) connected as an active diode, which is connected downstream of an output of a power supply unit (1) within a power supply device. The method comprises the following steps:generating a not fully conducting, in particular blocking state of the at least one field effect transistor (11);detecting a first value of a voltage drop (ΔU) across a switching path of the at least one field effect transistor (11) at a first set voltage of the power supply unit (1);setting a second voltage of the power supply unit (1);detecting a second value of the voltage drop (ΔU) across the switching path of the at least one field effect transistor (11) at the second set voltage of the power supply unit (1);detecting and signaling a defect of the at least one field effect transistor (11) if the first value of the voltage drop (ΔU) and the second value of the voltage drop (ΔU) are both smaller in magnitude than a predetermined first positive threshold value (U1), or if the first value of the voltage drop (ΔU) and/or the second value of the voltage drop (ΔU) are larger than a predetermined second positive threshold value (Uη), wherein the second threshold value is larger than the first threshold value.The invention further relates to a power supply device having a power supply unit (1) downstream of which at least one field effect transistor (11) connected as an active diode is connected.