At nonlinear field-weakening control of interior permanent magnet synchronous motor (IPMSM), the working point is difficult to calculate and the saturation of current regulators may lead to losing control. Linear field-weakening control (LFC) of IPMSM is proposed to control both torque and current in wide speed range applications and LFC can prevent loosing current control in IPMSM. IPMSM operation range is divided into three areas, namely constant torque linear area, constant power transition linear area, and constant direct axis current area. Current, speed, and torque of the three areas are obtained while maintaining the current and voltage constraints. Currents are controllable and the system can operate in deep field-weakening. Results are used to calculate the IPMSM working points. The validity of this study is verified by experiments.