This design uses an incremental system build to demonstrate a complete fixed-point sensorless Field-oriented control (FOC) design across a wide range of speeds and takes into consideration torque changes with transient phases by processing a dynamic model of the motor. Each incremental build uses modular software blocks to create a full sensorless-FOC design using two current sensors, macros for angle and speed estimation, speed and torque regulation, Park, Clarke, inverse Park, and space vector PWM generation (SVGEN). A block daigram for Sensorless FOC using two current sensors is shown in Figure 6-1.

For more information on the theoretical background of Sensorless FOC implementation with this design, see Sensorless FOC of PMSM.

Angle estimation is implemented using an Enhanced Sliding Mode Observer (eSMO) with phased lock-loop (PLL) to accurately estimate the real-time speed of a BLDC/PMSM motor. The motor state of the algorithm is controlled by using a state variable to automatically transition the motor from startup to open loop, and from open loop to closed loop. The closed-loop state allows for real-time motor control with minimal reference current, and additionally provides tunable speed regulation across torque changes or load conditions.