To Next Page

To Previous Page

AC Induction Motor Example

One of the more complex motor control algorithms



Sensorless

, ACI induction machine direct rotor flux control



Goal: motor speed estimation & alpha

axis stator current estimation

The "IQmath" approach is ideally suited for applications where a large numerical dynamic range

is not required. Motor control is an example of such an application (audio and communication

algorithms are other applications). As an example, the IQmath approach has been applied to the

sensor-less direct field control of an AC induction motor. This is probably one of the most chal-

lenging motor control problems and as will be shown later, requires numerical accuracy greater

then 16-bits in the control calculations.

The above slide is a block diagram representation of the key control blocks and their interconnec-

tions. Essentially this system implements a "Forward Control" block for controlling the d-q axis

motor current using PID controllers and a "Feedback Control" block using back emf's integration

with compensated voltage from current model for estimating rotor flux based on current and volt-

age measurements. The motor speed is simply estimated from rotor flux differentiation and open-

loop slip computation. The system was initially implemented on a "Simulator Test Bench" which

uses a simulation of an "AC Induction Motor Model" in place of a real motor. Once working, the

system was then tested using a real motor on an appropriate hardware platform.

Each individual block shown in the slide exists as a stand-alone C/C++ module, which can be

interconnected to form the complete control system. This modular approach allows reusability

and portability of the code.

8 - 26 C28x - Numerical Concepts & IQmath

Texas Instruments C28 Series Student Guide

Other manuals for Texas Instruments C28 Series