AN857
AN857 is Brushless DC Motor Control Made Easy manufactured by Microchip Technology.
Brushless DC Motor Control Made Easy
Author: Ward Brown Microchip Technology Inc. get d evice an d e xercise the co de directly from th e MPLAB® env ironment. The fin al co de ca n the n be ported to one of the smaller, less expensive, PICmicro m icrocontrollers. T he porting t akes m inimal effort because the instruction set is identical for all PICmicro 14-bit core devices. It should also be noted that the code was bench tested and optimized for a Pittman N2311A011 brushless DC motor. Other motors were also tested to assure that the code was generally useful.
INTRODUCTION
This application note discusses the steps of developing several controllers for brushless motors. We cover sensored, sensorless, open loop, and closed loop design. There is even a controller with independent voltage and speed controls so you can discover your motor’s characteristics empirically. The code in this application note was developed with the Microchip PIC16F877 PICmicro® Microcontroller, in conjuction with the In-C ircuit D ebugger (ICD). Thi s bination was chosen because the ICD is inexpensive, and code can be debugged in the prototype hardware w ithout ne ed fo r an ex tra pro grammer or emulator. As the design develops, we program the tar-
Anatomy of a BLDC
Figure 1 is a simplified illustration of BLDC motor construction. A brushless motor is constructed with a permanent magnet ro tor and w ire w ound stator po les. Electrical energy is converted to mechanical energy by the magnetic attractive forces between the permanent magnet rotor and a rotating magnetic field induced in the wound stator poles.
FIGURE 1:
SIMPLIFIED BLDC MOTOR DIAGRAMS
A a
101 c
N a b
6 3
C b
4 1
N c
B a
010 c
2 5 b B
© 2002 Microchip Technology Inc.
DS00857A-page 1 http://..
In this example there are three electromagnetic circuits connected at a c ommon po int. Eac h el ectromagnetic circuit is...
