This article describes a newly developed IGBT module for the application of pure electric vehicle (EV) and hybrid automotive (HEV) high power motor inverters. The new IGBT module adopts a 6-in-1 package structure, optimized internal lead arrangement, direct main terminal bonding structure (DLB structure) and direct cooling structure of bottom plate integrated aluminum column. As a result, the new IGBT module achieves high performance and low self-inductance at the same time. Compact package and light weight. Compared with conventional products with similar power levels, the adoption of these innovative technologies has resulted in a 20% increase in heat-dissipating capability of the IGBT module, a 30% reduction in self-inductance, a 50% reduction in packaging, and a 70% reduction in weight.
1, high power J1 series power module
1.1 Introduction
The market for pure electric vehicles and hybrid cars has grown along with the increasing awareness of global environmental protection. Power semiconductor modules have become an important part of determining the performance of electric vehicles. Especially in recent years, with the growth of the market, the diversification of power systems requires high power, high power density, and large-capacity power modules.
In response to the automotive market's basic requirements for power modules, such as high power, high reliability, compactness, and high efficiency, the new high-power J1 series high-power IGBT modules have been developed. High Power J1 Series IGBT Modules with 6-in-1 Internal Circuit Structure, Direct Main Terminal Bundle (DLB), Direct Cooling Structure, 7th Generation Carrier Channel Type Bipolar Transistor Silicon Technology (CSTBTTM) and RFC Diodes Wafer technology. The combination of optimization of these technologies has succeeded in improving the performance of high-power J1 series IGBT modules dedicated to EV applications. The appearance and internal circuit structure of the high-power J1 series module are shown in Fig. 1 and Fig. 2. The dimensions and the corresponding rated current and voltage specifications are shown in Table 1.
1.2 Packaging Technology
Compared to the J series and J1 series automotive IGBT modules previously introduced by Mitsubishi Electric, the internal structure of the high-power J1 series IGBT modules with heat-dissipation aluminum pillars for further improvement in voltage and current capabilities for electric vehicles is shown in Figure 3. Several typical package features of this new 6-in-1 module include a highly reliable direct main terminal bonding structure, compact size, light weight and high power handling capability. Large-size leads and power terminals included in high-power capability modules (such as 650V/1000A and 1200V/600A) increase their package size. Larger packages generally have greater self-inductance than small packages, and this is highly dizzying. High-power applications under /dt conditions are very dangerous problems. However, the flux between the PN terminals can be eliminated by using an optimized internal power lead and wafer layout, and the newly developed high-power J1 series modules successfully achieve low self-inductance. Figure 4 shows the inductive simulation results of the newly developed high-power J1 series compared to the traditional design.
Compared with more traditional packaged products (J-series T-PM), the package size of the new high-power module is reduced by 50% (as shown in Figure 5). The reduction in size of the high-power J1 series module is the result of an optimized cooled aluminum column structure combined with efficient 7th-generation CSTBTTM/RFC diode silicon technology. In addition to cooling aluminum columns with lower thermal conductivity than cooling copper columns, the choice of aluminum cooling columns has several advantages for EV/HEV applications. Among them, the most significant advantage is the direct exposure to aluminum in the coolant. Corrosion capacity and weight reduction compared to inverter solutions using J Series 6-in-1 IGBT modules can be reduced by 70% (as shown in Figure 6). Aluminum is not as susceptible to electrochemical corrosion as copper. If copper pillars are used, thick nickel plating is required to prevent corrosion. In addition, the lightweight aluminum helps to reduce the electricity cost and fuel consumption of EV/HEV.
In addition, the high-power J1 series eliminates two layers in the thermal path, one is the solder layer between the heat-dissipating substrate and the bottom plate, and the other is the grease layer between the bottom plate and the water-cooled heat sink. Compared with the traditional J series T-PM inverters, the thermal conductivity is increased by 20% (as shown in Figure 7). At the same time, the reduction in the number of layers also contributes to the improvement of the temperature cycle capability.
The scheme comparison shown in FIG. 5, FIG. 6, and FIG. 7 is based on the same voltage/current level IGBT module applied to the three-phase EV/HEV motor drive.
1.3 Test results using the latest silicon technology
With water-cooled heat sinks, the power handling capabilities of the high-power J1 series 650V/1000A IGBT modules were verified experimentally under the following conditions: battery voltage = 450V, PWM switching frequency = 5kHz/10kHz, cooling water temperature (Tw) = 65°C, Cooling water flow rate = 10L/min, thermal resistance IGBT-Rth(jw) takes the maximum, IGBT characteristic parameters take typical values. Similarly, the experimental conditions for the high-power J1 series 1200V/600A IGBT module are as follows: battery voltage=600V, PWM switching frequency=5kHz/10kHz, cooling water temperature (Tw)=65°C; cooling water flow rate=10L/min, thermal resistance The IGBT-Rth(jw) takes the maximum value and the IGBT characteristic parameter takes the typical value.
Under these conditions of application, the maximum inverter output current of a 650V/1000A module at a maximum operating junction temperature of less than 150°C can exceed 600 Arms (the corresponding inverter output power can exceed 120 kW). The maximum inverter output current of the 1200V/600A module at a maximum operating junction temperature of less than 150°C can exceed 400 Arms (the corresponding inverter output power can exceed 120 kW). The results of these experiments are shown in Figure 8 and Figure 9.
Such attractive and good results were obtained using the latest 7th generation CSTBTTM and RFC diode silicon technology. Advances in IGBT technology have been driven by the continuing demand for higher power density and higher efficiency, which is reflected in the optimization of the well-known saturation voltage drop VCE(sat) vs. turn-off loss Eoff compromised performance through the use of an improved internal structure. The purpose of the progressive generation of IGBT silicon performance. By adding additional carrier layers to the IGBT silicon structure, CSTBTTM wafers can achieve higher efficiency by reducing both saturation voltage drop and turn-off loss. The 7th-generation IGBT silicon further optimizes the CSTBTTM saturation voltage drop VCE(sat) vs. the turn-off loss Eoff compromise performance, as shown in Figure 10, which summarizes the continuous improvement of the performance of the new generation IGBT silicon. Considering the ultra-compactness of the J1 series of innovative package designs (power module volume less than 0.68 liters), it is evident that ultra-high power density can be achieved by using 7th generation IGBT silicon chips.
2. Conclusion
The new high power density IGBT module "High Power J1 Series" has been developed to meet the evolving requirements of the market for electric vehicles and hybrid vehicles. High-power J1 series IGBT modules achieve high performance, low self-inductance, compact package and light weight. These attractive features are achieved through the combination of optimized package structure technology and state-of-the-art silicon technology (7th generation CSTBTTM and RFC diodes ) to achieve. All in all, the high-power J1 series IGBT module can realize the operation of the helium-range inverter to meet the application requirements of different types of electric vehicles and hybrid cars.
3, reference
1. S. Inokuchi et al., "A new versatile high power Intelligent Power Module (IPM)", PCIM-ASIA2015 pp. 205-209
2. K. Hussein, et al., "IPMs Solving Major Reliability Issues in Automotive Applications", IEEE-ISPSD2004, Proceedings, pp. 89-92.
3, S. Honda, et al, "Next generation 600V CSTBTTM with an advanced finepattern and a thin wafer process technologies", ISPSD 2012, pp. 149-152.
4. M. Ishihara et al., "New compact-package Power Modules for Electric and Hybrid Vehicles (J1-Series)", PCIM-Europe 2014, pp. 1093-1097
5, K. Hussein, et al., "New compact, high performance 7th Generation IGBT module with direct liquid cooling for EV/HEV inverters", IEEE-APEC 2015, Proceedings, pp. 1343-1346.
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