DIRECT TORQUE CONTROL OF BRUSHLESS DC MOTORS

OBJECTIVE

To control the speed of three phase brushless dc motor by using Direct torque control principle.

To find some satisfactory solution for the problems that arise in applying Direct torque control principle.

To introduce new optimization techniques for improving the performance of Direct torque controlled Brushless DC motor drive.

CLASSIFICATION OF MOTORS

BRUSHLESS DC MOTORSBrushless Direct Current (BLDC) motor

one of the type of synchronous motor. BLDC motors do not use brushes for

commutation; instead, they are electronically commutated.

BLDC motors are used in industries such as Appliances, Automotive, Aerospace, Consumer, Medical, Industrial Automation Equipment and Instrumentation.

ADVANTAGES OF BLDC MOTOR

BLDC motors have many advantages over brushed DC motors and induction motors.

A few of these are: Better speed versus torque characteristics High dynamic response High efficiency Long operating life Noiseless operation Higher speed ranges

DISADVANTAGES OF BLDC MOTOR

Cost of Permanent Magnets

Need for Position Sensors

Limited Extended Speed Range

Field Weakening Operation is Difficult

MODELING OF BLDC MOTOR

SPEED CONTROL TECHNIQUES

DIRECT TORQUE CONTROL

FEATURES OF DTC SCHEME

Direct torque control and and direct stator flux control

Indirect control of stator currents and voltage

Approximately sinusoidal stator flux and stator currents.

High dynamic performance

ADVANTAGES OF DTC SCHEME

Absence of co-ordinate transformation

Minimal torque response time.

DISADVANTAGES OF DTC SCHEME

• possible problems during starting

•Inherent torque and flux ripples

optimizationOptimization is one of the acute

problem in science and technology.

Several optimization techniques are there like

1. Genetic algorithm2. Simulated analysis3. Swam optimization4. Ant colony algorithm

Contd.. Reason for choosing bacteria

foraging optimization ?

Bacteria foraging optimization- the most primitive organisms to be dealt for global optimization.

Swam foraging in adaptive control

Software for implementation

The total direct torque control of BLDC motor is simulated using MATLAB / SIMULINK software