Extended Back-EMF Based Industrial Sensorless Drive System for PMSMs

Field Oriented Control (FOC) of Permanent Magnet Synchronous Motors (PMSM) is utilized in many industrial applications due to its high performance. Semiconductor manufacturers provide specialized solutions and tools for this technique. However, such solutions are protected with closed source codes. This reduces the flexibility and the performance of such systems. This paper presents the conducted studies of controller and embedded software design for FOC of a PMSM using extended back-Electromotive Force (EMF) observer. Observer is derived from motor analytical model. Accurate position and speed estimations are observed using the simulations. An inverter board is obtained from market and a controller board with microcontroller is designed. Extended back-EMF observer model is implemented in embedded software. The developed drive system is fully capable to replace the existing closed source solutions with the benefits of having a robust and flexible structure that can be fine-tuned according to the application. Performance in nominal speed range with no-load and full-load along with transient loading is tested with a 3000 rpm industrial fan motor. The developed drive system is capable to operate down to 200 rpm and maintain stability under load disturbances, compensating the 10% speed error during nominal load transitions in one second.