PCB Magnetic Current Sensing for WBG Short-Circuit Detection
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Solution Overview
Problem
High frequency high power density wide-band gap (WBG) power electronics converters face reliability issues due to the need for multiple short circuit protection circuits across multiple semiconductor switching legs, which increases system costs and maintenance, and existing methods are invasive, requiring hardware modifications.
Innovation Solution
A non-invasive ultra-fast short circuit protection system using a single point of monitoring (SPM) and MHz bandwidth magnetic current sensors to detect ultra-high frequency AC currents flowing through decoupling capacitors, allowing for efficient detection of short circuit conditions without modifying the hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple short circuit protection circuits are used for multiple switching legs, then detection coverage is improved, but device complexity and system cost increase
Solution Approach 1:
The patent combines multiple short circuit protection functions into a single protection circuit that monitors the common DC-link capacitor. By measuring the current through the capacitor, the system can detect short circuit conditions in multiple switching legs simultaneously, eliminating the need for separate protection circuits for each leg and reducing overall system complexity.
Solution Approach 2:
The single protection circuit serves multiple switching legs universally by monitoring the shared DC-link capacitor current. This multi-functional approach allows one circuit to provide short circuit protection coverage for the entire converter system, making the protection mechanism adaptable to different switching leg configurations without requiring additional dedicated circuits.
2Measurement precision
If invasive protection methods are used, then detection precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent uses the DC-link capacitor as an intermediary element to indirectly measure short circuit currents in switching legs. Instead of directly inserting sensors into each switching leg (invasive method), the system monitors the capacitor current which reflects the short circuit conditions, thereby achieving accurate detection without hardware modification to the switching legs themselves.
Solution Approach 2:
The patent replaces invasive electrical connections with non-invasive magnetic field-based current sensing. By using a magnetic current sensor to detect the magnetic field generated by the capacitor current, the system achieves precise short circuit detection without requiring physical modification or direct electrical contact with the switching leg circuits.
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
Enables rapid and efficient detection of short circuit currents in WBG power electronics converters, reducing system costs and maintenance by using a single monitoring point and non-invasive sensors, effectively addressing the reliability issues associated with multiple switching legs.
Implementation Method 1
MHz bandwidth magnetic current sensors to detect ultra-high frequency AC currents flowing through decoupling capacitors
Data Source
AI summary
In preferred embodiments, a short circuit protection system for a wide-band gap power electronics converter composed of multiple half-bridge legs is presented. The main approaches of the system are a single point of monitoring (SPM) for multiple switching legs, and non-invasive implementation and fast speed of the short circuit current detection. Ultra-high frequency (UHF) AC current, tens or hundreds of MHz, flowing through the DC-link capacitors represents the short circuit current occurred at the multiple switching legs. To capture the UHF AC current, a non-invasive MHz bandwidth magnetic current sensor is applied to the PCB conduction path of the converter. In this digest, simulation results of the short circuit current representation through the DC-link network and the magnetic field distribution in PCB layout for the selection of the proper location of the detection, and experimental results showing the UHF AC current sensing performance are presented.