Closed loop speed control of a 24V brushless DC motor (BLDC) with Hall sensors

BLDC Motors are fast replacing the traditional DC motors with a physical commutator made of copper segments and carbon brushes because of the following advantages

Ø Higher efficiencies

Ø High torque to inertia ratios

Ø Greater speed versus torque characteristics

Ø Lower maintenance costs

Ø Better thermal efficiencies and

Ø Lower audible noise.

The motivation behind this project is the need to produce a simple closed loop speed control system which is cost effective and efficient. Other products on the market are quite expensive because they incorporate some functionality that the customers do not even need.So this design will satisfy the customers who just need a low cost drive with closed loop speed controller for their BLDC motors.

 PROJECT DESCRIPTION

The aim of the project is to design and build a  variable speed drive for a three phase 24V BLDC motor with Hall sensors.A digital (PI) closed loop speed controller is to be implemented. This involves the derivation of the motor transfer function and its application in the controller design using MATLAB. A dsPIC30F2010 micro-controller is to be used.

 PROJECT GOALS

To design a robust drive that will be reasonably priced compared to what is already on the market.

To design a drive which can give very good control of

 steady state conditions particularly the steady state error and

 transient conditions particularly the overshoot, rise time and the settling time.

 An LCD will be used to display the desired speed and the actual speed to showcase the efficiency of the closed loop (PI) controller.

THE BLDC MOTOR STRUCTURE

The motor has a permanent magnet rotor and a wound stator. The stator is wound in such a way so as to produce an even number of pole pairs.There are two types of stator windings

trapezoidal and

sinusoidal.