of Three Phase Systems Mahdi Izadkhast Learning Objectives I a 1 - - PowerPoint PPT Presentation

Sequences & Reference Transformations

• f Three Phase Systems

Mahdi Izadkhast

Learning Objectives

• What are the positive negative zero

sequences for the unbalanced three phase systems?

• What is the alpha-beta transformation and

when it is used?

• What is a phase locked loop?

1 a

I

1 b

I

1 c

I

Unbalances

Sequences

1 a

I

1 b

I

1 c

I

2 a

I

2 c

I

2 b

I

b I

a I

c I

Sequence Representation

Three-Phase Conversion to Sequence

Alpha-Beta Transformation

v

a ,b(t) = 2

3 1

• 1

2

• 1

2 3 2

• 3

2 é ë ê ê ê ê ê ù û ú ú ú ú ú va vb vc é ë ê ê ê ê ù û ú ú ú ú

Phase Locked Loop (PLL)

Control system that generates an output signal whose phase is related to the phase of an input signal

Summary

1 a

I

1 b

I

1 c

I

2 a

I

2 c

I

2 b

I

b I a I c I