Brushless AC motors, also known as Permanent Magnet Synchronous Motors (PMSM) or Permanent Magnet AC motors (PMAC), have the permanent magnets on the rotor and the externally commutated coils on the stator. They differ from a BLDC motor primarily in that the B-emf waveform induced by rotor spinning has a sinusoidal shape. The primary benefits of a brushless AC motor is it's inherent efficiency smooth operation and reliability. Typical configurations are a three phase motor driven by 3 half bridges. In low voltage applications the drivers can be integrated into a smart power IC. For higher voltages discrete MOSFET or IGBT and high voltage gate driver ICs are used for the half bridges. Power modules integrating three half bridges and the related gate driving stage can also be used. For many applications, sensorless drivers have eliminated the need for the speed/position sensors used in the past.