## 4 Calculation of Losses  
The total losses of power semiconductor systems are obtained by calculating and adding the switching and conduction losses separately. Switching losses are the losses that turn into heat at the moments of conduction and cut-off of IGBT modules. According to the datasheet details obtained from the IGBT company, the conduction switching loss of the IGBT at a 150 \({}^{\circ}\)C junction temperature, 600 V nominal voltage, and 600 A nominal current is 35 mJ. Under the same criteria, the cut-off switching loss is 110.4 mJ. In this study, since the nominal current value of the system is 200 A and the voltage value is 375 V, the approximate switching power loss of the system can be calculated by proportioning as follows. For IGBT;  
\[P_{d(IGBT)}=\text{(System Switching Frequency (Hz))}\cdot\text{Eon + Eoff (joule)}=\text{PowerLoss-1 (Watt)} \tag{2}\]  
In Equation (2), the system switching frequency is 8 kHz, the E\({}_{\text{on}}\) conduction switching loss is 35 mJ, and the cut-off switching loss is 110.4 mJ;  
\[P_{d(IGBT)}=8000\cdot(35+110.4)\cdot(10^{-3})=1163.2\text{ W} \tag{3}\]  
IGBT switching power dissipation is calculated in Equation (3). For the diode;  
\[P_{d(Diode)}=\text{(System Switching Frequency (Hz))}\cdot\text{(E${}_{\text{on }}$ (joule))}=\text{PowerLoss-2 (Watt)} \tag{4}\]  
In Equation (4), the system switching frequency is 8 kHz, E\({}_{\text{on}}\) conduction switching loss is 44 mJ;  
\[P_{d(Diode)}=8000\cdot(44)\cdot(10^{-3})=352\text{ W} \tag{5}\] \begin{table}
\begin{tabular}{c c c} \hline \hline
**Module Code** & **Voltage (V)** & **Current (A)** \\ \hline SEMIX604 GB12E4S & 1200 & 600 \\ \hline SEMIX904 GD126 HDs & 1200 & 600 \\ \hline SKM200 GB12E4 & 1200 & 200 \\ \hline SKM300 GB126D & 1200 & 300 \\ \hline SKiM459 GD12E4V2 & 1200 & 450 \\ \hline SKiM306 GD12E4 & 1200 & 300 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Selected switching modules. Figure 6: IGBT modules selected for BLDC motor driver. The diode switching power dissipation is calculated in Equation (5). The total switching power dissipation is calculated in Equation (6). \[P_{d(TOTAL)}=P_{d(IGBT)}+P_{d(Diode)}=1163.2+352=1515.2\;\mathrm{W} \tag{6}\]  
The value calculated in Equation (7) was performed at nominal voltage and current values of 600 V, 600 A. Since the nominal current value of the system is 200 A and the nominal voltage value is 375 V, the approximate switching power loss is expressed as shown in Equation (7) and obtained as shown in Equation (8). \[P_{d(TOTALnom)}=P_{d(TOTAL)}\cdot(I_{nom}\cdot V_{nom})/(I_{max}\cdot V_{max}) \tag{7}\]  
\[P_{d(TOTALnom)}=1515.2\cdot(200\cdot 375)/(600\cdot 600)\]  
\[P_{d(TOTALnom)}=315.66\;\mathrm{W} \tag{8}\]  
The switching power dissipation for a single IGBT diode pair is 315.66 W. Considering that there are 6 IGBT diode groups in the system, the total switching power dissipation is expressed as shown in Equation (9) and obtained as shown in Equation (10). \[P_{d(6\cdot TOTALnom)}=P_{d(TOTALnom)}\cdot 6 \tag{9}\]  
\[P_{d(6\cdot TOTALnom)}=315.66\cdot 6\]  
\[P_{d(6\cdot TOTALnom)}=1894\;\mathrm{W} \tag{10}\]  
This calculated value shows the maximum power loss. This amount of loss does not occur continuously while the system is operating. Transmission losses are directly proportional to the square of the nominal current value passing through the IGBT modules and the IGBT module internal resistance values. According to the data obtained from the IGBT data file, conduction loss calculations were performed by selecting the values of the switch internal resistance values of the IGBT module to be used at the maximum temperature. Equation (11) was used for IGBT in these calculations. It is calculated as shown in Equation (12). \[P_{i_{IGBT}}=V_{CEO}\cdot I_{nom}+r_{CE}\cdot(\;I_{nom})^{2} \tag{11}\]  
Figure 6:0  
Figure 6:1  
Equation (13) was used for the diode in these calculations. It is calculated as shown in Equation (14).