Annular Parallel Half-Bridge Assembly for Low-Inductance IGBT Switching
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Solution Overview
Problem
Existing crimp-type IGBT modules suffer from large parasitic inductance in the commutation loop, leading to overvoltage issues and limitations in power electronic device capacity due to the size and placement of capacitors relative to IGBTs, which complicates the formation of a half-bridge circuit.
Innovation Solution
A modular parallel half-bridge integrated assembly with an annular layout is designed, featuring capacitors C4, C5, and C6, and sub-modules with IGBTs, where inductors and IGBTs are strategically connected to balance parasitic inductance and current distribution, ensuring a compact and symmetrical structure that minimizes parasitic inductance and enhances switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitor and IGBT are placed far apart to form a half-bridge circuit, then the circuit functionality is achieved, but parasitic inductance increases
Solution Approach 1:
The patent divides the half-bridge circuit into multiple parallel sub-modules, each containing its own capacitor and IGBT. This segmentation allows each module to be compact while maintaining overall circuit functionality, reducing the distance between capacitors and IGBTs in each sub-module and thereby reducing parasitic inductance.
Solution Approach 2:
The patent employs a three-dimensional layout where capacitors are positioned directly above or below IGBTs in the vertical dimension, rather than placing them far apart in the horizontal plane. This dimensional reorganization minimizes the commutation loop area and reduces parasitic inductance while maintaining circuit functionality.
2Ease of manufacture
If capacitor terminals are placed far from IGBT terminals, then circuit assembly is simplified, but overvoltage occurs during IGBT turn-off
Solution Approach 1:
By dividing the circuit into parallel sub-modules with compact internal layouts, each module can be assembled independently with minimized capacitor-IGBT distances. This segmentation maintains manufacturing simplicity while ensuring reliable overvoltage suppression through reduced parasitic inductance in each module.
Solution Approach 2:
The patent merges the capacitor and IGBT into closely integrated sub-modules, combining elements that were traditionally separated. This merging reduces the commutation loop area and parasitic inductance, preventing overvoltage during switching while maintaining assembly simplicity through modular design.
3Power
If compact structure is achieved, then power density increases, but parasitic inductance becomes difficult to control
Solution Approach 1:
The patent segments the high-power circuit into multiple parallel sub-modules, each with compact structure. This segmentation maintains high power density while providing independent control of parasitic inductance in each module, making it easier to manage and optimize the harmful inductive effects.
Solution Approach 2:
The patent applies different layout optimizations to different parts of the circuit. Within each sub-module, the capacitor and IGBT are positioned to minimize local parasitic inductance, while the overall parallel structure provides global power density. This local quality optimization allows compact structure while controlling parasitic inductance.
4Power
If parallel sub-modules are used, then current capacity increases, but current imbalance occurs among sub-modules
Solution Approach 1:
The patent introduces asymmetric damping resistors in each parallel sub-module to compensate for inherent asymmetries in parasitic inductance and other parameters. This deliberate asymmetric element balancing ensures uniform current distribution among sub-modules, maintaining stability while achieving high current capacity.
Solution Approach 2:
The patent adjusts parameters such as damping resistor values and capacitor configurations in each sub-module to optimize current balance. By changing these parameters, the system achieves uniform current distribution among parallel sub-modules, enabling high current capacity without current imbalance issues.
Data Source
AI summary
A modular parallel half-bridge integrated assembly with an annular layout is provided. The assembly includes a plurality of parallel sub-modules to improve a current capacity of the assembly. The sub-modules adopt an annular layout and are connected in parallel to balance currents of the sub-modules. The half-bridge integrated assembly includes a plurality of sub-modules, a plurality of heat sinks, a drive board, a direct current (DC) positive collecting busbar, a DC negative collecting busbar, and an alternating current (AC) collecting busbar. According to the assembly, since each insulated gate bipolar transistor (IGBT) is tightly bound to a capacitor, parasitic inductance of a commutation loop is small, realizing a small voltage overshoot and a fast switching speed for the IGBT module, so as to balance the currents of the sub-modules.