This paper develops an internal permanent magnet synchronous motor (IPMSM) controller to maximize the drive performance under the same energy usage. Maximum torque per ampere (MTPA) control is used to maximize the torque output below rated speed. Flux-weakening (FW) control is implemented to maximize the power output beyond rated speed. From the perspective of MTPA, a fixed m-t axis current control is proposed during the constant torque region at low speed. Conventional MTPA control requires the differentiation of nonlinear torque equation to obtain corresponding d- and q-axis current, leading to complicated nonlinear mathematical calculation. Under this effect, conventional MTPA results in considerable controller memory and calculation time. From the perspective of FW, both feedforward and feedback control methods are compared to identify a suited FW controller. It is shown that the feedforward FW control results in fast dynamic responses; however, the parameter sensitivity is the primary control issue.