This paper presents novel sliding mode control (SMC) approaches for Maximum Torque Per Ampere (MTPA) and Maximum Power Per Ampere (MPPA) of interior permanent magnet synchronous motors (IPMs). We first derive the first-order sliding mode control methods to improve the field oriented control’s resiliency against the external perturbations, extraneous noise and modeling uncertainties. And after that, we propose the higher-order sliding mode control to significantly reduce the chattering phenomenon which is inherent in the first order sliding mode control method. Based on the comparison studies, the conventional proportional-integral derivative based field oriented control shows sluggish response and is more sensitive to parameter perturbations and external torque disturbances. By introducing the novel sliding mode control methods, both of the speed and torque regulation performance of interior-mounted permanent magnet synchronous motor can be greatly improved. Computer simulation studies have shown the superior performance of the first-order and higher-order sliding mode controllers for interior permanent magnet synchronous motor speed and torque regulation applications.