Active-Diode MOSFET Checking in Parallel Power Supplies
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Solution Overview
Problem
Existing methods for testing field-effect transistors used as active diodes in parallel power supplies fail to provide reliable results when the voltage drops of functioning transistors are similar to defective ones, leading to incorrect identification of defective components.
Innovation Solution
A method involving two voltage drop measurements at different set voltages is employed to distinguish between a properly functioning field-effect transistor and a defective one, using threshold values to detect defects by measuring voltage drops across the transistor's switching path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single voltage drop measurement is performed at a fixed output voltage to test the field-effect transistor, then the test method is simple, but the test result is unreliable when parallel power supplies have similar voltage magnitudes
Solution Approach 1:
The test method dynamically adjusts the output voltage of the power supply unit to at least two different values during the testing process. By varying the operating point and measuring voltage drops at multiple voltage levels, the method can reliably distinguish between healthy and defective transistors even in parallel power supply configurations where voltages are similar at a single operating point.
2Adaptability or versatility
If the field-effect transistor is tested in parallel power supply configuration, then redundant power supply functionality is maintained, but voltage drop measurements become ambiguous and may lead to incorrect defect identification
Solution Approach 1:
The test method performs preliminary actions by temporarily adjusting the output voltage to test values that create measurable voltage differences between parallel power supplies. This preliminary voltage adjustment allows accurate measurement of the field-effect transistor's voltage drop without permanently altering the power supply configuration, enabling precise defect detection while maintaining parallel operation capability.
3Reliability
If the output voltage is changed during testing, then reliable defect detection is achieved, but the testing process becomes more complex and time-consuming
Solution Approach 1:
The test method employs periodic action by systematically varying the output voltage to at least two different test values in a structured sequence. This periodic voltage adjustment allows the system to gather sufficient measurement data for reliable defect detection while maintaining an efficient testing rhythm that minimizes overall testing time compared to continuous or random voltage variations.
Data Source
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AI summary
The invention relates to a method for checking at least one field-effect transistor (11) which is connected as an active diode downstream of an output of a power supply unit (1) within a power supply device. The method comprises the following steps: - generating an incompletely conductive, in particular blocking state of the at least one field-effect transistor (11); - recording a first value of a voltage drop (ΔU) over 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); - recording a second value of the voltage drop (ΔU) over 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 signalling a defect of the at least one field-effect transistor (11) if both the first value of the voltage drop (ΔU) and the second value of the voltage drop (ΔU) are each quantitatively less 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) is greater than a predetermined second positive threshold value (Un), the second threshold value being greater 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) is connected as an active diode.