# Compact 3 \(\times\) 1 Matrix Converter Module Based on the SiC Devices with Easy Expandability
## 2 Structure of the Module  
The module was designed to be very compact, considering the mounting of almost all required components to drive the module, with only the need for external signals to control the module. Due to this consideration, the design was separated into three parts. The block diagram with the highlighted blocks is shown in Figure 3.  
For the power part, the SiC transistors were used due to their relatively high operation temperature, high blocking voltage, and relatively small form factor. Recently, the ON-Semiconductors manufacturer released a new family of the SiC MOSFETs, which were well suited for this application. The semiconductors are in the D2 PAK-7 package with a Kelvin source pin extended from the package to ensure proper driving of the device. It is important to select the right mounting of the semiconductors to ensure good electrical insulation and good heat dissipation. For this application, the best price to performance ratio is achieved by the IMS boards according to the research in the introduction. Additionally, this approach does not need an insulating pad between PCB and the heatsink, increasing thermal resistance significantly. Figure 2: PCB Heat dissipation solution: (a) thermal vias; (b) copper inlay; (c) IMS board. For the power part, the common-source configuration of the switches was selected. As described in many publications [19; 20; 21; 22; 23; 24], the commutation algorithm must be implemented to ensure no short or open circuit development, leading to overvoltage and overcurrent generation and circuit destruction. Many commutation techniques are available where most of them are based on the output current measurement. Thus, the authors decided to implement a current direction measurement to the power board for the commutation investigation in future work. The output current direction in the matrix converter can be measured in many ways, and these methods are summarized in Table 1, together with possible advantages and disadvantages. Since the current direction detection circuitry is designed at the power IMS board, the authors selected a method that measures at the output diodes, offering good precision and fast reaction. The power losses can be effectively dissipated through the metal board to the heatsink. If the diodes with low drop voltage are selected, the power losses can be reduced significantly. The circuit is supplemented with the fast comparator to detect the voltage drop direction at the diodes, as shown in Figure 4. The board was designed to one-layer IMS board with final dimensions of 129 \(\times\) 58 mm. The design of the power board is shown in Figure 4. The board consists of four mounting holes to be easily mounted to the heatsink. \begin{table}
\begin{tabular}{c l l} \hline \hline
**Method** & **Advantages** & **Disadvantages** \\ \hline \multirow{3}{*}{Direct measurement at the transistors} & -No additional losses & -Every transistor needs its circuitry \\  & -Accurate at low currents & -Lot of parts \\  & -No isolated power supply needed & -Lot of parts \\  & -Only one circuit per output phase & \\ \multirow{3}{*}{Measuring at the output diodes} & -Only one circuit per output phase & -Enters additional losses to the converter \\  & -Accurate at low currents & -Needs an isolated power supply \\ \multirow{3}{*}{Measuring at the output shunt} & -Only one circuit per output phase & -Low accuracy at the small output currents \\  & -Small additional losses & -Needs an isolated power supply \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of the basic current direction measurement methods. Figure 3: (**a**) Block diagram of the presented module, (**b**) schematic of the power part of the presented module. The design of this board allows the change of the power devices based on the output power specification of the matrix converter. The 3D model of the power board is shown in Figure 5.  
The second board was designed for driving SiC transistors.