As the cost of motor control DSP has come down by a factor of ten over the last 15 years, software in these devices have replaced the rotor position sensors generally used in variable speed motors such as PMSMs and IPMs. Advanced mathematics can be used to estimate the rotor position of PMSM motor, using closed loop observer techniques. Thus, the trend is to go sensor-less by replacing the rotor position sensors, such as hall sensors.
With advanced software, the future will be to use the motor as a sensor in the applications. As a key component of HVAC or appliance end systems, software will become critical in faults & diagnostic information generation which can be used to prolong the life of the system.