Sensorless control of permanent-magnet synchronous motors adopting indirect self-control

This study presents a detailed description of how sensorless control of permanent-magnet synchronous motors can be implemented when the torque and stator flux amplitude are controlled using the principle of indirect self-control (ISC). As a new contribution, it is demonstrated how carrier signal injection, used to obtain accurate speed and position estimates in the low-speed region, can be incorporated in the ISC scheme. Furthermore, the impact of saturation in the rotor structure during initial rotor position detection is also analysed. Results from finite element simulations together with experimental results (from a laboratory bench setup as well as from a test train) support the obtained results.