Core Logic and Practical Guide to Laminated BusBars for Reducing Parasitic Inductance
May 12, 2026
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In power circuit design, parasitic inductance is a hidden killer, often causing unexpected failures of IGBTs and SiC modules, severely impacting the stability and safety of power equipment. The Laminated Bus Bar for Inverter Powering Modern AC Locomotive, as a core component in high-current design, significantly reduces parasitic inductance thanks to its unique structural design, becoming an indispensable key component in power electronics design. The scientific nature of the Laminated Busbar Design directly determines the effectiveness of parasitic inductance reduction.
The difference in parasitic inductance between the Laminated Bus Bar for Electric Vehicle Power Distribution and traditional parallel busbars is extremely significant, as can be clearly demonstrated by data. According to test data, the parasitic inductance of a parallel busbar is 550 nH/m, while the parasitic inductance of the Laminated Bus Bar for High Horsepower Locomotive Traction Drive is only in the single digits (nH). Taking a 200mm long × 100mm wide × 0.5mm insulation layer Laminated Bus Bar for Electric Vehicle Power Electronics as an example, its parasitic inductance is only 3-5nH, while that of a traditional parallel busbar is 110nH under the same conditions. The difference between the two is more than 20 times. Laminated Inverter Busbars can better highlight this low inductance advantage in inverter design.
The key to the significantly reduced parasitic inductance of Laminated Busbars lies in their unique structural design and magnetic field cancellation principle. In traditional parallel busbars, current flows from the positive terminal, passes through the load, and returns from the negative terminal. The magnetic fields generated by the positive and negative busbars superimpose, making the entire circuit essentially a large inductor, resulting in persistently high parasitic inductance. Laminated Inverter Busbars, however, employ a sandwich-layer structure of "positive terminal-insulation layer-negative terminal." The precise connection of Laminated Busbar Connectors further optimizes the current path and enhances the magnetic field cancellation effect.
When current flows between the positive and negative terminals of Laminated Busbar Power Solutions, the magnetic fields generated by the two currents are opposite in direction and equal in magnitude, canceling each other out. This significantly reduces the overall parasitic inductance, which is the core reason for the low inductance characteristic of Laminated Busbar Connectors. This structural design not only reduces parasitic inductance but also optimizes current distribution, reduces the skin effect, and improves the busbar's current-carrying capacity, adapting to high-current operating conditions. Based on this principle, Laminated Busbar Power Solutions provides stable power supply for power devices.
From the perspective of loop inductance composition, the parasitic inductance of different components varies significantly: the typical parasitic inductance of a 62mm half-bridge IGBT module is approximately 20nH, the lead inductance of the bus capacitor itself is 15-40nH, while the parasitic inductance of a 0.2m long parallel busbar reaches 110nH, compared to only 3-5nH for a Laminated BusBar of the same length for Mersen, demonstrating a remarkably significant magnetic field cancellation effect. Therefore, for high-current IGBTs, especially SiC power circuits, Infineon explicitly recommends prioritizing the use of Laminated Bus Bars. Laminated BusBars for Mersen are perfectly suited for these demanding power circuits.
Mastering the measurement methods for parasitic inductance is crucial for optimizing the design of Laminated Copper BusBars and ensuring the stability of power circuits. The double-pulse test is the most standard measurement method in the industry. This method involves building a double-pulse test circuit, generating two pulses using a low-side switch, and measuring the Vce voltage waveform of the upper bridge arm IGBT to quantify the parasitic inductance value. This standard test method is commonly used for parasitic inductance detection of Laminated BusBars.
In summary, Laminated BusBars achieve magnetic field cancellation through a "sandwich" stacked structure, significantly reducing parasitic inductance and resolving the core hidden danger of IGBT/SiC failure in power circuits. They are an essential component for high-current designs. Understanding their inductance reduction principles and measurement methods, and appropriately selecting suitable Laminated BusBar types, can effectively improve the stability, safety, and lifespan of power equipment.
If you would like to learn more about the inductance reduction principles, design techniques, and selection methods of Laminated Copper BusBars, or have technical consultation or procurement needs, please contact us for professional and comprehensive industry support and customized solutions.
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