In an electrified vehicle, magnet temperature plays a critical role in determining optimal current control trajectory of an interior permanent magnet machine. Monitoring magnet temperature is a challenging task. In lab and various specialized applications, infrared sensors or thermocouples are used to measure the temperature. But it adds cost, maintenance issues and their integration to electric machine drives could be complicated. To tackle the issues due to sensor based methods, various sensor-less model based approaches are proposed in the literature recently such as flux observer, high-frequency signal injection, and thermal models, etc. Although magnet temperature monitoring received a lot of attention of researchers, very few papers give a detailed overview of the effects of magnet temperature on motor control from a controls perspective. In this paper, we will show the effect of the change in magnet temperature on Maximum Torque per Ampere control and Flux Weakening Control. It will help control engineers to design better control algorithms to compensate the effect of magnet temperature to improve torque accuracy, system efficiency and to ensure stable operation in flux weakening region.