Non-Isolated DC-DC Converter Switch Short-Circuit Detection
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Solution Overview
Problem
Non-isolated full-bridge DC/DC converters face a risk of faulty electrical connections between the input and output, which can lead to unsafe operating conditions due to the lack of electrical isolation, necessitating a reliable method for detecting short circuits in switching devices before startup.
Innovation Solution
A non-isolated DC-DC converter with integrated short-circuit detection circuitry using resistive dividers and sensing circuitry to compare node voltages against normal values, distinguishing between short-circuit and non-short-circuit conditions for upper, middle, and lower switches during pre-operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If non-isolated DC-DC converter topology is used to achieve high efficiency and high power density, then converter efficiency and power density are improved, but the risk of faulty electrical connections between input and output increases
Solution Approach 1:
The patent applies preliminary action by performing short-circuit detection during a pre-operation testing phase before the converter is activated. The control circuitry tests each switching device (Q1-Q4) individually by activating them in sequence and monitoring voltage at test nodes (VA, VB, VC) to detect potential short circuits before they can cause harmful effects during normal operation.
Solution Approach 2:
The patent implements preliminary anti-action by proactively detecting and preventing short circuit conditions before they can lead to unsafe operating conditions. The control circuitry is designed to identify faulty electrical connections in advance and prevent the converter from entering a dangerous state by blocking startup when short circuits are detected.
2Reliability
If short-circuit detection circuitry is added to detect switching device failures, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the control circuitry to perform multiple functions: it controls the switching devices during normal operation and simultaneously performs short-circuit detection during pre-operation testing. The same control circuitry and test nodes (VA, VB, VC) are used for both operational control and fault detection, eliminating the need for separate dedicated detection hardware.
Solution Approach 2:
The patent merges the short-circuit detection function with the existing control circuitry and operational structure. The detection process utilizes the same switching devices, test nodes, and control signals that are already present in the converter design, combining fault detection capabilities with the operational control system rather than adding entirely separate detection equipment.
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
Effectively detects and prevents short circuits in switching devices, ensuring safe and reliable converter operation by identifying abnormal voltage conditions before startup, thereby protecting against unsafe input-to-output voltage transfer.
Implementation Method 1
a resistive divider to establish normal values of a primary-side test node and a secondary-side test node in a non-short-circuit condition
Implementation Method 2
sensing circuitry operative during the pre-operation of the converter to detect abnormal values of the primary-side and secondary-side test nodes indicative of an abnormal short circuit
Data Source
AI summary
A non-isolated DC-DC converter detects short circuits of its switching devices to avoid faulty and unsafe operating conditions. The converter includes a transformer and switching circuitry that includes upper switches and middle switches of a primary-side inverter and lower switches of a secondary-side rectifier. Short-circuit detection circuitry has (1) a resistive divider to establish normal values of a primary-side test node and a secondary-side test node in a non-short-circuit condition during pre-operation with all the switches in an OFF condition, and (2) sensing circuitry operative during the pre-operation of the converter to detect abnormal values of the primary-side and secondary-side test nodes indicative of an abnormal short circuit of the upper, middle or lower switches.