Inverter Current Detection via Supplementary Bridge Circuit
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Solution Overview
Problem
Conventional current detection devices in semiconductor systems, such as IPMs, face challenges in reducing device size due to the use of current transformers for detecting main currents, which increases the scale and complexity of the device, and requires additional components for insulation, leading to increased costs and complexity.
Innovation Solution
The implementation of a current detection device with a supplementary bridge circuit connected in parallel to the main bridge circuit, using current transformers to detect a fraction of the AC current, allowing for a reduction in the size of the current detection unit and eliminating the need for additional insulation components by using current transformers directly in the detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current transformer is used to detect the main current flowing in the main line, then the load current can be detected, but the size of the current detection unit and the overall device scale will increase
Solution Approach 1:
The invention divides the bridge circuit into a main bridge circuit for power conversion and a supplementary bridge circuit for current detection. The supplementary bridge circuit is connected in parallel to the main bridge circuit and generates a detection-use AC current that is a prescribed fraction of the main bridge circuit's output current. This segmentation allows the current transformer to detect only the smaller detection-use current rather than the full main current, significantly reducing the required current transformer size and overall device scale while maintaining detection accuracy.
2Reliability
If additional insulation components are added to protect the current detection unit, then reliability improves, but device complexity and cost increase
Solution Approach 1:
The invention merges the current detection function directly into the supplementary bridge circuit output line, which is already electrically isolated from the main power path through the parallel connection architecture. The current transformer is disposed on the supplementary bridge circuit output line to detect the detection-use AC current, eliminating the need for additional insulation components between the detection circuit and main power circuit, thereby reducing device complexity and cost while maintaining reliability.
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 configuration reduces the overall size of the device, decreases costs by minimizing the number of components, and allows for more compact integration of current transformers, enhancing the miniaturization and efficiency of current detection in semiconductor systems.
Implementation Method 1
If a current transformer, for example, is accordingly used as the current detection unit
Data Source
AI summary
An inverter circuit with a current detection circuitry includes a main bridge circuit connected between the pair of DC input nodes, the main bridge circuit converting the received DC voltage to a primary AC current so as to output the primary AC current through an output terminal to be connected to a load; a supplementary bridge circuit connected in parallel to the main bridge circuit between the pair of DC input nodes, the supplementary bridge circuit having a circuit configuration identical to that of the main bridge circuit with smaller circuit parameters in at least some of constituent circuit elements so as to generate a detection-use AC current that is a prescribed fraction of said AC current outputted by the main bridge circuit. The detection-use AC current is detected by a current detector so as to calculate the amount of the primary AC current.