POWER SEMICONDUCTOR SYSTEMS I

Author: Ales Havel

E-mail: ales.havel@vsb.cz

Phone number: 4287

Headquarters: E227

Web page: http://homen.vsb.cz/~hav278/

Presentation contents

Main types of converters AC-DC converters

Single phase rectifiers Construction possibilities, wiring Load voltage and current waveforms Mathematics Neat examples

Three phase rectifiers Construction possibilities, wiring Load voltage and current waveforms Mathematics Neat examples

DC-DC converters DC-AC converters AC-AC converters

Power converters A power semiconductor converter is an

electrical device for converting electrical energy.

Division of AC/DC converters

Properties of rectifiers Number of input phases

Single phase rectifiers Three phase rectifiers n – phase rectifiers

Number of pulses P = 1, 2, 3, 6…

Possibilities of output voltage control Without control

Diode rectifiers Half-controlled rectifiers

Diodes + Thyristors Full-controlled rectifiers

Thyristors

Wiring Bridge rectifiers Node rectifiers

Half-wave single phase diode rectifiers

Voltage

Voltage

Current

Current

Resistive load

Inductive load

Half-wave single phase diode rectifiers

Voltage

Voltage

Current

Current

R+L+D0 load

R+L load

Half-wave single phase diode rectifiers

Voltage

Voltage

Current

Current

R+C load

R+V load

Two pulse diode rectifiers

Voltage

Current

Two pulse thyristor controlled rectifiers

Important mathematical relations

Output to Input phase RMS voltage ratio

p[-] UL / U1 [-]

1 0.45

2 0.90

3 1.17

6 2.34

Limit of load current continuity for resistive loadp[-] α[°]

3 306 60

0 sinL m

pU U

p

0 cosL LU U

The output AVG voltage of diode rectifier or thyristor rectifier with control angle α = 0°:

The output AVG voltage of thyristor rectifier with control angle α.

Condition 1: The load current must be continuousCondition 2: No parallel bypass diode on the load

Example 1- submission

Calculate the output AVG voltage of the 2-pulse bridge controlled rectifier, if you know the following values:

α = 60°, U1 = 230V

Example 1- solution

1

22sin( ) sin( ) cos( )

2

24 1 1 230 2cos cos 103.5

3 3 2 2

m mL m

m m m

U UU U t d t t d t t

T

U U U UV

1 12 2 2 230 2sin cos sin cos 103.5

2 3L m

U UpU U V

p

1

0.9 2300.9 cos 103.5

3 2LU U V

a) General calculation approach:

b) Calculation utilizing the basic relation:

c) Calculation utilizing the table values:

Example 1- question?

1

22sin( ) sin( ) cos( )

2

3 3 21 3 230 2cos cos 1 155

3 2 2 2 2

m mL BD m

m m m

U UU U t d t t d t t

T

U U U UV

How will change the output AVG voltage value if we use the bypass diode parallel to the load?

Solution:

Six pulse thyristor controlled rectifiers

Six pulse thyristor controlled rectifiers

Thank You for your attention