Field Oriented Control System Diagram - Xilinx Spartan 6 FPGA Quick Start Manual

Motor control development kit

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Qdesys Sensorless Field Oriented Control Quick Start Guide

Field Oriented Control System Diagram

The diagram below shows a high level depiction of the main blocks and architecture for this Field

Oriented Control (FOC) demonstration. Two motor phase currents are sampled and the missing third

phase current is calculated using Kirchoff's Current Law. The 3 phase currents are converted into a 2-

axis, stationary coordinate system using the Clarke Transform. The 2-axis system is then translated into

a rotating frame of reference (the rotor's frame of reference) via the Park Transform. The PID loops

calculate and correct the error. The inverse transforms are applied and then a final modulation stage

creates the proper PWM sequence for the h-bridge circuitry to deliver power to the motor.

This closed loop control system enables precise control of motor torque, which leads to better efficiency,

smoother operation, lower cost motors, and longer lasting equipment. Note that in this demonstration, the

motor position (theta) is obtained by using a sensorless algorithm known as a Sliding Mode Observer.

This eliminates the need for costly encoders and bulky wiring harnesses. However, the Qdesys design

also allows an encoder connection, which is desirable in some applications.

Before you set up the board, please install the host PC software, including the Qdesys MC

Manager GUI and other software and settings needed to demonstrate the QDESYS IP.

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