## 7 Design and Assembly of Other Power Stage Circuits  
Whether the cooling system is air, fan assisted air, or a liquid cooled system, IGBT modules are mounted on these coolers after manufacturing. A busbar or sandwich busbar is mounted on these IGBT modules. After this, DA-Bus capacitors and the snubber are assembled. Depending on the sheath structure of the IGBT, the IGBT driver (Skyper 32) is connected to the system either directly or through an intermediate mounting tube. In Figure 16, due to the sheath of the IGBT module, an intermediate auxiliary circuit (board) manufactured for easy connections is used. The placement of the auxiliary board circuit on the IGBT modules together with the Skyper 32 Pro is shown in Figure 17[16]. Figure 16: DC-Bus IGBT heatsink and capacitance. Figure 17: IGBT module design on a fluid cooling system. In this study, the original design of both air and liquid-cooled three-phase power plants with a nominal power of 75 kW and a maximum power of 100 kW is presented. The DC-AC converter (inverter) was designed, manufactured, and operated. In the air-cooled system, the DA-Bus capacitors are installed by connecting eight 4500 uF 450 V capacitors in parallel. Figure 18 shows the original 75 kW fan-assisted natural-air cooled three-phase inverter circuit. With the emergence of film capacitors with the development of technology instead of electrolytic capacitors, film capacitors were used in the second design, the liquid-cooled system. In the liquid cooled inverter circuit in Figure 19, two film capacitors are used. The physical structure of the system is much smaller. As shown in the above figures, the space occupied by both designs is large. A new sandwich busbar design with a film capacitor was required to reduce the physical footprint. After such a design is completed; It turned out that it was appropriate to design the system  
Figure 19: Original 75 kW liquid cooled three phase inverter circuit. Figure 18: Original 75 kW fan assisted natural-air cooled three-phase inverter circuit. using a \"module containing six IGBTs in a single case\". The SKiM459 GD12E4 model, produced by Semikron for three-phase systems, with six IGBTs in a single housing and with a suitable thermal structure, was selected. The design of two 220 \(\upmu\)F 1200 V film concentrators and the'sandwich-bara' design that will allow us to connect them to the IGBT module is shown in Figure 20. In addition, the placement of the SKiM459 GD12E4 IGBT module on the liquid cooling unit, the adapter circuit (Adaptor Board 93 GD) required for the connection of the IGBT module and the IGBT driver circuit, the placement of the IGBT driver circuit SKYPER(r) 42 LJ R, the connection of current sensors, and the input and output connectors are shown in three dimensions in the design in Figure 20. It can be seen that the new design is a very compact and space-saving one. In Figure 21, three-dimensional drawings of the cooler module were made and the mounting locations of the IGBT module were determined so as not to coincide with the liquid channels of this cooler. The SKiM459 GD12E4 six-IGBT module in Figure 22 was selected based on technical requirements such as system current voltage values, etc. First of all, this IGBT module was mounted on this heatsink block. The \"Adaptor Board 93 GD\", which is an adapter circuit suitable for the IGBT module, was selected from Semikron. The adapter circuit is mounted on the IGBT module as in the design structure in Figure 22[18]. As shown in Figure 23, a different sandwich busbar was designed and connected for the assembly of the SKiM459 GD12E4 IGBT module and film capacitors. The sandwich bar  
Figure 21: Three-dimensional design visuals of the cooling module from the front, top and side. Figure 20: Original three-phase 75 kW liquid cooled inverter circuit with six IGBT modules. was manufactured. In Figure 23, the original three-phase 75 kW fully controlled liquid-cooled DC-AC converter circuit was designed and manufactured.