PALESTINE POLYTECHNIC UNIVERSITY(PPU)

POWER ELECTRONICS

Dr. Sameer Khader

Spring 2003 / 20042005/2006

Chapter 3-B Three-Phase Rectifiers

Chapter 3-A : Single Phase Rectifiers

Rectifier Classification

Power Electronics

Chapter 3

Uncontrolled Rectifiers

Un controlled Rectifiers

Single-PhaseRectifiers

Three-Phase rectifiers

Half-Wave Full-Wave

A: s1_1

Power Electronics

Chapter 3 : A

Single –Phase Uncontrolled Rectifiers

Single-Phase Rectifiers

Half-Wave “HW”

Full Wave“FW”

Bridge circuit Center tape

A: s1_1

Power Electronics

Chapter 3 : B

Three –Phase Uncontrolled Rectifiers

Three-Phase Rectifiers

Half-Wave “HW”

Full Wave“FW”

Three-Phase Half Wave Uncontrolled I- With Resistive Load Principle of operation :

1-Each diode must conduct for 120 dg while the anode voltage is maximum positive comparing with the other anode voltages .

2- Each phase voltage is connect to the load for the time of 120 dg.

3-The source ( phase) current is unsymmetrical

because it’s flow only during the positive half cycles .

Conclusion : 1- Low ripples , comparing with single-phase rectifier 2- Relatively acceptable efficiency and TUF 74 %3-There is a dc component in the source current (heavy saturated transformer)4- The output ripples are three-times the supply frequency .5- The diode inverse voltage is 1.731 Vm .

PIV

Vout

Ic

Vdiode

II- Three Phase Rectifier with R-L Load

The existing of inductance in the rectification circuit (

supply transformer & load inductance),leads to: 1- Voltage reduction in the average output voltage; 2- Current deformation of the output & phase current 3- Increasing the harmonic specter, therefore , increasing the harmonic losses .

Vdc L 0( ) Vdc L0( ) VL 0

V 3 Idc Lc fLc fThe output voltage :

In every commutation interval, two diodes operate together for angle Which called overlapping angle .

III- Three Phase Rectifier with failed diode

Vdc d1( ) failed Vdc0 11

3 VxVdc0

V4

T0

6

tVmcos tdThe output

voltage

The load current

The loadcurrents

The loadvoltage

The diode

voltage

.

The mathematical equations of HW – Three Phase Rectifier

IdcVdc

R

Vdc

2- The RMS voltage & current:

IrmsVrms

R

Vrms

3 - The output average & AC power:

Pdc Vdc IdcVdc

4 - The rectification efficiency: Pdc

Pac

Pdc

Pac

5- The transformer utility factor:

Pac Vrms IrmsVrms Irms

TUFPdc

VA( ) rating

Pdc

VA rating

where

8- The Ripple Factor :

1- The average voltage & current :

VA( ) rating 3 Vs IsVA( ) rating Vs Is

6 - The source current:

Vrms3

0

3

tVmcos t( )2d 0.840Vm

3

7 - The diode average current :

Idav1

0

3

tIm cos t( ) d 0.33Idc

8 - The diode rms current :

Idr1

0

3

tImcos t( )2d

Irms

3

1

Is3

0

3

tIm. cos t( )2d 0.48Im Irms

0

3

tIm. cos t( )2d

Vdc3

0

3

tVm cos t( ) d 3 3Vm

2

7 - The Form factor :FF Vrms

Vdc1.015

RF FF2 1 18 %

9- Diode PIV : PIV Va Vb 3 VmVa Vb Vm

Three-Phase Full Wave Uncontrolled I- With Resistive Load Principle of operation :

1-Each diode from anode group will conduct for 120 dg while the anode voltage is maximum positive comparing with the other anode voltages . And one diode from cathode group also conduct for 120 dg, while the cathode voltage is maximum negative .

2- Each diodes group is connect to the load for a time of 60 dg.

3-The source ( phase) current is symmetrical,

therefore no saturation effect

4- the supply voltage connected to the load is line voltage .

Conclusion :

1- Low ripples , comparing with another circuits (4% ripples), therefore no need of filter 2- Extremely high efficiency efficiency and TUF > 96%3-There is no dc component in the source current , therefore minimized losses4- The output ripples are with six-times the supply frequency .5- The diode inverse voltage is 1.731 Vm .6- the phase rms current is 81% of the load rms value .7- This circuit find widespread applications in wide range of the power specter .

II- FW Rectifier with R-L load

Vdc L 0( ) Vdc L0( ) VL 0

V 6 Idc Lc fLc f

The output average voltage:

Load current

Phasecurrent

Output voltage

Phase current

.

Mathematical Modeling of FW – Three Phase Rectifier

IdcVdc

R

Vdc

2- The RMS voltage & current:

IrmsVrms

R

Vrms

3 - The output average & AC power:

Pdc Vdc IdcVdc

4 - The rectification efficiency: Pdc

Pac

Pdc

Pac

5- The transformer utility factor:

Pac Vrms IrmsVrms Irms

TUFPdc

VA( ) rating

Pdc

VA rating

where

9- The Ripple Factor :

1- The average voltage & current :

VA( ) rating 3 Vs IsVA( ) rating Vs Is

6 - The source current:

7 - The diode average current :

8 - The diode rms current :

7 - The Form factor :

10- Diode PIV : PIV Va Vb 3 VmVa Vb Vm

Vdc6

0

6

tVab t( ) d 3 3Vm

Vrms6

0

6

tVab t( )( )2d 1.655Vm

6

Is8

2 0

6

tVab t( )

R

2

d 0.7804ImL

0

6

tVab t( )

R

2

d

ImL 3Vm

R

Vm

Idav4

2 0

6

tImL cos t( ) d 0.318ImL

Idr4

2 0

6

tImLcos t( )2d

Irms

3

4

2

Is Irms4

6Irms

RF FF2 1 4 %2 1FFFF Vrms

Vdc1.0006

Single Phase Half-Wave Circuit

0.000ms 30.00ms 60.00ms 90.00ms

30.00 V

10.00 V

-10.00 V

-30.00 V

A: v1_1

0.000ms 30.00ms 60.00ms 90.00ms

30.00 V

20.00 V

10.00 V

0.000 V

-10.00 V

A: s1_1

0.000ms 30.00ms 60.00ms 90.00ms

25.00mA

-25.00mA

-75.00mA

-125.0mA

A: r1[i]

0.000ms 30.00ms 60.00ms 90.00ms

30.00 V

20.00 V

10.00 V

0.000 V

-10.00 V

A: s1_2

D1DIODE

S1

C130uF

50 Hz

V1-30/30V

R1200

D1DIODE

S1

C130uF

50 Hz

V1-30/30V

R1200

T12TO1

50 Hz

V2-30/30V

C230uF

S2

D2DIODE

R2200

T12TO1

50 Hz

V2-30/30V

C230uF

S2

D2DIODE

R2200

Supply voltage

Output voltageWithout C

Output voltageWith C

Load current with C

Conclusion :

1- High ripples , therefore large value of capacitor is required 2- Poor efficiency and TUF ~28%--31%3- Dc component in the source current ( heavy saturated transformer ) 4- The output ripples have the same frequency equals the source frequency .

S1

C1

30uF

D1BRIDGE

50 Hz

V1-30/30V

R1200

0.000ms 30.00ms 60.00ms 90.00ms

30.00 V

20.00 V

10.00 V

0.000 V

-10.00 V

A: s1_1

S1

C1

30uF

D1BRIDGE

50 Hz

V1-30/30V

R1200

0.000ms 30.00ms 60.00ms 90.00ms

30.00 V

20.00 V

10.00 V

0.000 V

-10.00 V

A: s1_2

Single phase Uncontrolled Bridge rectifiers

1-Electrical circuit without filtering capacitor

1-Electrical circuit with filtering

capacitor

Conclusion :

1- Low ripples , therefore small value of capacitor is required 2- Relatively high efficiency and TUF 81 %3- No dc component in the source current ( no-saturation Effect in the transformer4- The output ripples have twice frequency with respect to the source .

The mathematical equationsof FW Bridge Rectifier

IdcVdc

R

Vdc

- The RMS voltage:

IrmsVrms

R

Vrms

- The output average & AC power:

Pdc Vdc IdcVdc

- The rectification efficiency: Pdc

Pac

Pdc

Pac

- The transformer utility factor:

Pac Vrms IrmsVrms Irms

TUFPdc

VA( ) rating

Pdc

VA rating

- for FW- bridge…..

- for FW- center tape IsIrms

2

Irms

Is IrmsIrms

whereVA( ) rating Vs IsVA( ) rating Vs Is

VA( ) rating 2 Vs IsVA( ) rating Vs Is

- The ripple factor: RF FF2 12 1FF

1- The main parameters : * rectification output parameters : - Average output voltage & current:

Vdc2

T0

T

2 tVm sin t( ) d

- The harmonic factor

HFIs

Is1

2

12

1Is

Is1; HF= 1.11

Vrms

0

T

2

tVmsin t2d

2

TVmsin t

The mathematical equationsof HW Rectifier

IdcVdc

R

Vdc

- The RMS voltage:

IrmsVrms

R

Vrms

- The output average & AC power:

Pdc Vdc IdcVdc

- The rectification efficiency: Pdc

Pac

Pdc

Pac

- The transformer utility factor:

Pac Vrms IrmsVrms Irms

TUFPdc

VA( ) rating

Pdc

VA rating

Is IrmsIrms

where

VA( ) rating Vs IsVA( ) rating Vs Is

- The form factor :

- The ripple factor: RF FF2 12 1FF

1- The main parameters : * rectification output parameters : - Average output voltage & current:

Vdc1

T0

T

2 tVm sin t( ) d

- The harmonic factor

HFIs

Is1

2

12

1Is

Is1

; FF= 1.57

Vrms

0

T

2 tVmsin t

2d1

TVmsin t

apparent power

source current

Single-Phase Rectifier – Center Tap

D512F120

D412F120

60 Hz

V2 5TO1CT

R5500

0.000ms 15.00ms 30.00ms 45.00ms

20.00 V

10.00 V

0.000 V

-10.00 V

-20.00 V

A: r5_2

Conclusion :

1- Low ripples , therefore small value of capacitor is required 2- Relatively high efficiency and low TUF ~ 57%3- No dc component in the source current ( no-saturation Effect in the transformer4- The output ripples have twice frequency with respect to the source .5- The diode PIV voltage is twice the supply voltage

IdcVdc

R

Vdc

- The RMS voltage:

IrmsVrms

R

Vrms

- The output average & AC power:

Pdc Vdc IdcVdc

- The rectification efficiency: Pdc

Pac

Pdc

Pac

- The transformer utility factor:

Pac Vrms IrmsVrms Irms

TUFPdc

VA( ) rating

Pdc

VA rating

- for FW- center tape IsIrms

2

Irms

where

VA( ) rating 2 Vs IsVA( ) rating Vs Is

- The form factor :

- The ripple factor: RF FF2 12 1FF

1- The main parameters : * rectification output parameters : - Average output voltage & current:

Vdc2

T0

T

2 tVm sin t( ) d

- The harmonic factor

HFIs

Is1

2

12

1Is

Is1

; FF= 1.11

Vrms

0

T

2

tVmsin t2d

2

TVmsin t

Mathematical Equations of FW Rectifier – Center Tap

+51 Volt Power Supply D412F120

D3DIODES1A

+

C1100uF

2TO1

60 Hz

V1-170/170V

D118DB10

D21N4757

Q12N2222A

+

C2100uF

R1680 R2

50

Additional Circuits

0.000ms 10.00ms 20.00ms 30.00ms

125.0 V

75.00 V

25.00 V

-25.00 V

A: r2_2

0.000ms 10.00ms 20.00ms 30.00ms

125.0 V

75.00 V

25.00 V

-25.00 V

A: r2_2

Without stabilizer

With stabilizer

Thyristor and Triac Circuits

D1DIODE

+

C10.9uF

R15k 30%

SCR12N506450 Hz

V1-220/220V

B A

R2100

B A

D1DIODE

+

C10.9uF

R15k 30%

SCR12N506450 Hz

V1-220/220V

B A

R2100

20.00ms 35.00ms 50.00ms 65.00ms

2.250 A

1.750 A

1.250 A

0.750 A

0.250 A

-0.250 A

A: r2[i]

20.00ms 35.00ms 50.00ms 65.00ms

150.0 V

50.00 V

-50.00 V

-150.0 V

-250.0 V

A: scr1_1

40.00ms 55.00ms 70.00ms 85.00ms

2.500 V

-2.500 V

-7.500 V

-12.50 V

A: r1_2

Thyristor voltage

Loadcurent

Capacitor voltage

Load

MAC210-6

D1DIODE

+C1

0.9uF

R110k 20%

50 Hz

V1-220/220V

B A

R2100

B A

MAC210-6

D1DIODE

+C1

0.9uF

R110k 20%

50 Hz

V1-220/220V

B A

R2100

35.00ms 50.00ms 65.00ms 80.00ms

200.0 V

100.0 V

0.000 V

-100.0 V

-200.0 V

A: r2_2

Triacvoltage

35.00ms 50.00ms 65.00ms 80.00ms

2.500 A

1.500 A

0.500 A

-0.500 A

-1.500 A

-2.500 A

A: r2[i]

Triaccurrent

35.00ms 50.00ms 65.00ms 80.00ms

1.500 V

0.500 V

-0.500 V

-1.500 V

A: d1_k

Capacitorvoltage

.

S1

0.5uF

2N2646

20V

D

MAC210-6

C

3.00ms

0/0V

B

120 Hz

0/5V

A

50 Hz

15/-15V

AB

QV(A+B)

5k 150

47

20

100

D

C

B

A

6.000ms 8.000ms 10.00ms 12.00ms

5.000 V

3.000 V

1.000 V

-1.000 V

-3.000 V

-5.000 V

A: q1_3

5.000ms 15.00ms 25.00ms 35.00ms

12.50 V

7.500 V

2.500 V

-2.500 V

-7.500 V

-12.50 V

A: q1_2

0.000ms 10.00ms 20.00ms 30.00ms

12.50 V

7.500 V

2.500 V

-2.500 V

-7.500 V

-12.50 V

A: q1_2

0.000ms 10.00ms 20.00ms 30.00ms

12.50 V

7.500 V

2.500 V

-2.500 V

-7.500 V

-12.50 V

A: q1_3

0.000ms 10.00ms 20.00ms 30.00ms

12.50 V

7.500 V

2.500 V

-2.500 V

-7.500 V

-12.50 V

A: q1_3

0.000ms 5.000ms 10.00ms 15.00ms

25.00 V

15.00 V

5.000 V

-5.000 V

-15.00 V

-25.00 V

A: c1_2

UJTneedle

s

Loadvoltag

e

Pulsegenerator

Loadvoltag

e

Capacitorvoltage

Triac firing circuits