STMicroelectronics: three-phase motor control solutions

Three-phase AC induction motor

Three-phase induction motor is a brushless motor. Is copper wire windings of the stator, rotor is usually an aluminum squirrel cage. Typical drive configuration is 1 three-phase bridge (3 half-bridge), you can provide 3 sine wave voltage for the stator. The drive is usually used for high power applications, generally by 1 discrete IGBT with high voltage gate driver, or integration of the 3 and a half bridge and gate driver stage power module. Inverter control microcontrollers realizes the field-oriented control, or scalar (Volt/Hz) control algorithm.

Three-phase induction motors vector drive (FOC)

Vector control (that is, field-oriented control, FOC) is a method of variable frequency drives to control three-phase AC motor torque and speed. In particular, this means to measure motor current, and then convert it to the coordinate system that rotates the rotor of the machine. In order to complete this reference frame transformation must be measured directly (through the actual speed/position sensor) or indirect estimates (without sensor) the rotor position.

Vector control need HW peripherals to complete this task and more intensive than the scalar control calculation, on the other hand it enables better dynamic response (for example changes in load control), more accurate mechanical torque adjustment and quieter operation.