© 2016-2017 NXP B.V. Sensorless ACIM Field-Oriented Control 1. Introduction This document describes the software design of the direct vector control of 3-phase AC Induction Motors (ACIM). ACIMs are popular in the industry for a number of reasons, such as: • Their construction is extremely optimized, because they have been produced for years. • They are very simple and the manufacturing costs are low, because they do not include any expensive components (such as permanent magnets). • They are robust and require minimum maintenance due to the absence of brushes, permanent magnets, or other complicated mechanical elements. • Unlike Permanent Magnet Synchronous Motors (PMSM), they can run without any control method using the mains 3-phase voltage. You can find induction motors in applications like water pumps, compressors, fans, and air-conditioning systems. To achieve variable speed operations with a 3-phase AC induction motor, variable voltage and frequency must be supplied to the motor. The modern 3-phase variable speed drives achieve this using digitally-controlled switching inverters. NXP offers the High-Voltage Motor-Control Platform (HVP) power stage, which supports many kinds of MCUs, easily interchangeable using expansion cards. For more information, see the Freescale High-Voltage Motor- Control Platform User's Guide (document HVPMC3PHUG). NXP Semiconductors Document Number: DRM150 Design Reference Manual Rev. 1 , 01/2017 Contents 1. Introduction ....................................................................... 1 2. AC induction motor ........................................................... 2 2.1. Equivalent circuit of induction motor ........................ 4 2.2. Space vector model of AC induction motor............... 5 3. ACIM field-oriented control .............................................. 9 3.1. Rotor flux observer .................................................. 12 3.2. Rotor speed estimation ............................................ 15 3.3. Max Torque Per Ampere ......................................... 16 3.4. Flux weakening ....................................................... 17 3.5. Space vector modulation ......................................... 18 4. Software design ............................................................... 20 4.1. Data types ................................................................ 22 4.2. Scaling of analog quantities ..................................... 23 4.3. Motor-control algorithms synchronization .............. 24 4.4. State machines ......................................................... 25 4.5. ACIM control software implementation .................. 34 5. References ....................................................................... 39 6. Revision history ............................................................... 39