The asymmetrical half-bridge PWM drive leverages the motor’s best features. An independent current loop is implemented for each motor phase so that some phase current overlap is possible to attain higher speeds. For the drive, 2 x n power switches are required (n being the number of motor phases).
The simplified asymmetrical half-bridge PWM drive topology only requires n + 1 power switches and is well adapted to medium-speed operation.
ST has developed specific products to better address both configurations.
AN885: ST62 microcontrollers drive home appliance motor technology
Publications and Collaterals
Motor Control Reference Guide