New 1200A IGBT Module Breaks Power Density Barrier for 800V EVs
A groundbreaking advancement in power electronics for electric vehicles (EVs) has emerged from a collaborative research effort, unveiling a high-power-density IGBT module specifically engineered for the next generation of 800-volt electric drivetrains. This newly developed module, based on the widely adopted EconoDUAL package, achieves a remarkable current rating of 1,200 amperes, a significant leap that promises to enhance the performance, efficiency, and charging speed of future EVs. The research, which successfully addressed the critical bottleneck of parasitic inductance in traditional designs, was published in the Journal of Power Supply, a leading peer-reviewed publication in the field of power engineering.
The development of high-voltage 800V architectures has become a key strategic focus for the automotive industry, primarily driven by the need for ultra-fast charging capabilities. While 400V systems have been the standard, 800V platforms can effectively double the charging power, drastically reducing charging times and alleviating a major consumer concern. However, this shift to higher voltage systems places immense stress on the vehicle’s power electronics, particularly the power modules that act as the heart of the inverter, converting DC battery power into the AC power needed to drive the electric motor. Conventional power modules, often built with a two-dimensional (2D) layout on a Direct Bonded Copper (DBC) substrate, suffer from high levels of parasitic inductance. This inherent electrical resistance to changes in current creates voltage spikes during the rapid switching of IGBTs (Insulated-Gate Bipolar Transistors), which can damage the semiconductor chips and limit the maximum safe operating voltage and switching speed. This limitation has been a significant barrier to increasing power density—the amount of power a module can handle relative to its size and weight. As the industry pushes for smaller, lighter, and more powerful components to extend vehicle range and reduce costs, overcoming this inductance hurdle is paramount.
The research team, led by Hui Xiaoshuang, a doctoral candidate at the University of Chinese Academy of Sciences and the Institute of Electrical Engineering, Chinese Academy of Sciences, has tackled this challenge with an innovative three-dimensional (3D) design approach. Their solution moves away from the conventional flat layout and instead employs a “stacked DBC” method. In this novel architecture, two DBC substrates are used in a vertical configuration. The bottom DBC carries the primary power current, while the top DBC is used for specific connections, creating two overlapping current paths. This strategic overlap is the key to the module’s success, as it leverages the principle of mutual inductance cancellation. When two conductors carry current in opposite directions, their magnetic fields interact in a way that reduces the overall inductance of the circuit. By carefully designing the current flow through the stacked layers, the researchers were able to create a magnetic field interaction that significantly cancels out the parasitic inductance that plagues traditional 2D designs.
The impact of this 3D stacked design is quantifiable and substantial. According to the team’s analysis, the internal parasitic inductance of the new module was reduced by a remarkable 58% compared to a conventional 2D layout. This dramatic reduction is not just a theoretical achievement; it is a critical enabler for real-world performance. With lower inductance, the module can switch on and off much faster without generating destructive voltage overshoots. This faster switching speed translates directly into higher efficiency, as the time spent in the high-loss transition state between on and off is minimized. Furthermore, the reduced voltage spikes allow the module to operate safely at the higher 800V bus voltage, which is essential for fast-charging applications. This combination of high voltage and high current capability is what defines the module’s exceptional power density.
To achieve the 1,200A current rating within the confines of the standard EconoDUAL footprint, the team implemented a sophisticated parallelization strategy. Instead of using a few large, high-current chips, which are difficult to manage thermally and electrically, they opted for a distributed design using six smaller IGBT chips and six corresponding diode chips, each rated for 200A. This modular approach offers several advantages. First, it provides redundancy; if one chip were to fail, the others can continue to operate, albeit at a reduced capacity, enhancing system reliability. Second, the smaller chip size allows for a more uniform distribution of heat across the DBC substrate, preventing the formation of dangerous hot spots. Third, the parallel configuration inherently helps to further reduce the overall resistance and inductance of the power path. The precise placement of these twelve chips—six IGBTs and six diodes—was meticulously optimized on the stacked DBC structure. The layout ensures that the current paths for the upper and lower switches of the half-bridge circuit are as short and symmetrical as possible, which is crucial for balanced current sharing and minimizing electromagnetic interference (EMI).
A critical aspect of any high-power-density design is thermal management. Packing more power into a smaller space generates more heat, and if not effectively dissipated, this heat can quickly degrade the semiconductor materials and lead to premature failure. Recognizing this, the research team integrated a high-performance cooling solution directly into their design. They attached a water-cooled PinFin heat sink to the bottom of the power module. Unlike traditional flat cold plates, a PinFin heat sink features an array of small, fin-like protrusions that dramatically increase the surface area in contact with the cooling fluid. This enhanced surface area allows for far more efficient heat transfer from the DBC substrate into the coolant. Computational Fluid Dynamics (CFD) simulations, a sophisticated multi-physics modeling technique, were used to predict the module’s thermal performance under operating conditions. These simulations modeled the complex interaction between the electrical power losses generating heat, the conduction of that heat through the module’s layers, and the convection of heat away by the flowing coolant. The results of the simulation were highly promising, predicting a maximum junction temperature of approximately 150 degrees Celsius under full load, which is within the safe operating limits for modern IGBTs.
However, simulation results, while valuable, must be validated by real-world testing. To confirm the module’s thermal performance, the team conducted rigorous experimental thermal resistance testing. Thermal resistance, measured in Kelvin per Watt (K/W), is a key metric that quantifies how effectively heat flows from the semiconductor junction (the hottest point) to the cooling medium (in this case, the water). A lower thermal resistance value indicates better cooling performance. The test involved a specialized circuit where a high “heating” current was pulsed through the IGBT or diode to raise its temperature, followed by a low “measurement” current to monitor the voltage drop, which is highly sensitive to temperature. By analyzing the temperature rise and fall curve, the transient thermal resistance can be calculated. The experimental results were exceptionally favorable. The measured thermal resistance from the IGBT junction to the cooling water was 0.084 K/W, and for the diode, it was 0.124 K/W. These values are critically important because they are virtually identical to those of a commercially available 1,200V/900A module in the same EconoDUAL package. This direct comparison demonstrates that the team’s high-power-density design did not come at the expense of thermal performance. They achieved a 33% increase in current capability (from 900A to 1,200A) without increasing the thermal resistance, a testament to the effectiveness of their 3D stacked layout and PinFin cooling solution.
The ultimate validation of any power module’s electrical performance comes from dynamic testing under realistic conditions. To this end, the researchers performed a double-pulse test, the industry-standard method for evaluating a module’s switching behavior. This test subjects the device to rapid, high-current switching events that mimic the actual stresses it will face in an inverter. The test was conducted at a bus voltage of 800 volts and a pulse current of 1,200 amperes, pushing the module to its designed limits. The results were unequivocal: the module successfully passed the test at both room temperature and at a high junction temperature of 150 degrees Celsius. The switching waveforms showed clean, stable turn-on and turn-off characteristics with no signs of destructive voltage overshoot or oscillation, confirming that the low-inductance design effectively manages the electrical stresses. This successful test is the final proof that the module is not just a laboratory curiosity but a viable, high-performance component ready for integration into next-generation EV powertrains.
The implications of this research extend far beyond a single component. It represents a significant step forward in the art of power module design. The stacked DBC approach provides a clear pathway for increasing the power density of existing, widely used packages like the EconoDUAL, which could accelerate the adoption of 800V systems without requiring a complete redesign of vehicle inverter architectures. This is a crucial advantage for automakers looking to leverage existing manufacturing knowledge and supply chains. Furthermore, the success of this project highlights the importance of a holistic design philosophy that simultaneously optimizes electrical, thermal, and mechanical performance. The team did not focus solely on reducing inductance; they equally prioritized thermal management and structural integrity, resulting in a balanced and robust solution.
This work was supported by the National Key Research and Development Program of China and the CAS Youth Multi-discipline Project, underscoring its strategic importance to national technological advancement. The collaboration between academic institutions—the University of Chinese Academy of Sciences and Huaqiao University—and a leading industry partner, Zhejiang Xinfeng Technology Co., Ltd., exemplifies the kind of public-private partnership that is essential for driving innovation in complex engineering fields. The involvement of industry ensures that the research is grounded in practical manufacturing constraints and market needs, while the academic partners provide deep expertise in fundamental physics and advanced simulation techniques.
In conclusion, the development of this 1,200A IGBT module marks a pivotal moment in the evolution of EV power electronics. By ingeniously applying a 3D stacked DBC layout to a standard package, Hui Xiaoshuang, Ning Puqi, Fan Tao, Guo Xinhua, Fu Jinyuan, and Huang Ke have created a component that breaks the traditional trade-off between power density and reliability. Their design achieves unprecedented current capability at 800V with parasitic inductance reduced by 58% and thermal performance on par with lower-current commercial modules. This breakthrough paves the way for smaller, lighter, and more efficient inverters, which will directly contribute to longer driving ranges, faster charging, and ultimately, a more compelling and sustainable electric vehicle for consumers worldwide. As the automotive industry races toward a fully electrified future, innovations like this are the essential building blocks that will power the journey.
Hui Xiaoshuang, Ning Puqi, Fan Tao, Guo Xinhua, Fu Jinyuan, Huang Ke. New 1200A IGBT Module Breaks Power Density Barrier for 800V EVs. Journal of Power Supply. DOI 10.13234/j.issn.2095-2805.2024.3.72