## 3 Results and Discussion
### Effect of Electromagnetic Parameters  
Figure 10 shows the effect of magnetic field intensity and voltage on velocity in the cooling channel. The Lorentz force using the MHD pump is generated in a perpendicular direction to the applied magnetic field and voltage directions which drives the coolant in the cooling channel. The ferrofluid depicts the quality of self-circulation under the influence of magnetic field intensity and voltage, hence, velocity in the cooling channel due to the MHD pump is generated for ferrofluid coolant. The self-circulation performance of ferrofluid using the MHD pump improves with a rise in voltage and magnetic field intensity, which results in a linear increase in velocity of ferrofluid coolant with an increase in voltage and magnetic field intensity. Therefore, the intensity of coolant mixing is high at a higher voltage and magnetic field intensity, which results in higher velocity. The higher velocity indicates improvement in forced convection, which results in enhanced heat transfer performance of ferrofluid cooling. In the case of water, the velocity generated by the MHD pump is zero, owing to the absence of self-circulating characteristics under the influence of a magnetic field and voltage. The increase rate in velocity with increase in voltage is superior at a higher magnetic intensity and increasing rate becomes narrow as the magnetic field intensity decreases. With an increase in voltage from 0.1 V to 0.5 V, the velocity increases from 0.92 mm/s to 4.03 mm/s in the case of 0.1 T, 1.77 mm/s to 7.12 mm/s in the case of 0.2 T, 2.56 mm/s to 9.69 mm/s in the case of 0.3 T and 3.32 mm/s to 12.08 mm/s in the case of 0.4 T, respectively. Figure 10: Velocity in cooling channel under various conditions of magnetic field intensity and voltage. The variation in the inverter maximum temperature for various conditions of magnetic field intensity and voltage in the case of water and ferrofluid cooling is shown in Figure 11. In the case of water cooling, the traction inverter temperature is 354 \({}^{\circ}\)C, which is significantly higher than the maximum allowable temperature for the failure of a traction inverter. Furthermore, the change in magnetic field intensity and voltage has no influence on the inverter maximum temperature in the case of water cooling because of the absence of magnetic properties which help to create the self-circulation effect using the MHD pump in the case of water cooling. Despite of the presence of the MHD pump, the water cannot be circulated and remained stagnant, which creates the natural convection cooling in the case of water, thus, the inverter maximum temperature is high for water cooling. The ferrofluid enables the excellent magnetic and electrical properties which create the self-circulation of ferrofluid using the MHD pump under various conditions of magnetic field intensity and voltage. With the rise in magnetic field intensity and voltage, the MHD pump power increases, which creates a higher intensity of force circulation effect in ferrofluid cooling. Therefore, in the case of ferrofluid cooling, the inverter maximum temperature decreases with an increase in magnetic field intensity and voltage. Furthermore, the heat transfer properties of ferrofluid are superior compared to water. The improvement in the forced circulation effect and heat transfer properties result in higher dissipation of heat from the traction inverter to ferrofluid and thus the lower inverter maximum temperature compared to water cooling. The decrease in the steepness curve of the inverter maximum temperature with an increase in voltage is higher in the case of lower magnetic field intensity. However, the lowest inverter maximum temperature is evaluated at a higher magnetic field intensity and higher voltage owing to the superior MHD pump effect.