Modeling and Simulation

of

PFC Converter

1

PFC Converterby

Dr Sanjeev Singh

SLIET Longowal, Punjab, India

PFC Converter

• The PFC converter uses a DC-DC

converter topology amongst various

available topologies i.e. Buck, Boost

and Buck-boost;and Buck-boost;

• An average current control scheme

with current multiplier approach is

used in continuous conduction mode

(CCM) operation of the drive;2

PFC Converter PWM Control

3

Control Schemes of PFC Converters

• Continuous Conduction Mode (CCM) with Current

Multiplier Average Current Control.

• Discontinuous Conduction Mode (DCM) with Voltage

Follower Control.Follower Control.

These Control schemes are applied on various converter

configurations such as buck, boost and buck-boost DC-DC

Converters for control various drives.

4

Example 1

Switched Mode Power

5

Switched Mode Power

Supply (SMPS)

Power Supply

6

Linear Power Supply

7

Applications of SMPS

� Battery chargers

� Electronics ballast

� Measurement and testing equipments,

� Small rating motor drives in medical equipments,

� Small rating refrigeration units.

� Single stage with power-factor correction.

8

Battery Chargers

9

Electronic Ballast

10

Small Rating Motor Drives in Medical

Equipments

11

Operation of SMPS

The operation of SMPS involves,

� Rectification of available AC voltage from utility using

diode rectifiers and capacitive filter;

� The rectified DC voltage (unregulated) is converted to

high frequency AC by a suitable DC-DC converter

topology.topology.

� The high frequency transformers are used for isolation,

desired voltage ratio and multiple outputs, if required.

� The high frequency AC voltages are rectified using

diode rectifiers to achieve regulated DC output voltage.

� The regulated output voltage is applied to many

applications as discussed in the previous slides.12

Operation of SMPS

However, the rectification process results in many

problems at input AC mains in terms of

• poor power factor,

• High total harmonic distortion (THD) in AC mains

currentcurrent

• High crest factor (CF).

These problems are termed as power quality problems and

need to be addressed.

13

Power Quality� Power Quality (PQ) is the quality of the voltage, including

its frequency and the resulting current that are measured

in the input of any user System;

� Therefore, any power problem manifested in voltage,

current, or frequency deviation that results in failure or

mal-operation of utility or end-user equipment can be

14

mal-operation of utility or end-user equipment can be

treated as power quality problem;

� Non-linear loads (electronic devices, PE switch controlled

drives or switching converters for any electrical gadget)

are the major source of power quality problems.

Control of SPMS

• The control of SMPS is mainly a closed loop control in

which the output voltage is controlled using the DC-DC

Converter.

• The control of DC-DC Converter mainly modifies the duty• The control of DC-DC Converter mainly modifies the duty

cycle of the PWM signals applied to the converter switch.

• There are various control strategies for PWM control of

the DC-DC Converters.

• The schematic of SMPS Control and a general control

scheme are shown in next slides.15

Control Schemes

• Peak Current Control.

• Average Current Control.

• Hysteresis Current Control.

• Voltage Follower Control.

16

Peak current mode control

17

Average current mode control

18

Hysteresis current mode control

19

Voltage follower control

20

Complete Scheme of PFC ConverterCurrent Multiplier Control

21

Complete Scheme of PFC ConverterVoltage Follower Control

22

Modeling of PFC Controller

� The modeling of PFC Controller consists of

following:

� Modeling of Voltage Controller

� Modeling of Reference Current Generator

23

� Modeling of Reference Current Generator

� Modeling of PWM Current Controller

Modeling of Voltage Controller

� The voltage controller is a proportional and integral

(PI) controller which tracks the error voltage between

reference voltage and sensed voltage at DC link and

generates a control signal Ic based on the Kp and Ki

24

c p i

gains of the PI controller.

Ic (k) = Ic (k-1) + Kp{Ve(k) – Ve(k-1)} + KiVe(k)

where Ve(k) =V*dc(k)-Vdc(k)

� This controller is an essential part in Current multiplier

as well as voltage follower control schemes.

Modeling of

Reference Current Generator

� The reference current at input of the DC-DC converter

(idc*) is generated using the unit template of AC mains

voltage and output of the PI controller.

i* = I (k) u , u = v /V , v = |v |;

25

i*dc = Ic (k) uvs, uVs = vd/Vsm, vd = |vs|;

vs= Vsm sin ωt

� The reference current generator is not a part of voltage

follower control.

Modeling of PWM ControllerCurrent multiplier approach

� The PWM controller processes the current error (∆idc)

between the reference input current (idc*) of the DC-

DC converter and the DC current (idc) sensed after

DBR.

26

DBR.

� The PWM controller amplifies this current error (∆id)

by gain kd and compares with a fixed frequency (fs)

carrier waveforms md (t) to get the switching signal for

the MOSFET of PFC converter.

If kd ∆idc > md (t) then S = 1 (ON) else S = 0 (OFF),

where ∆idc=(idc* - idc)

Modeling of PWM ControllerVoltage follower approach

� The PWM controller processes the PI Controller output (Ic )after

amplification by gain kd and compares with a fixed frequency

(fs) carrier waveforms md (t) to get the switching signal for the

MOSFET of PFC converter.

If k I > m (t) then S = 1 (ON) else S = 0 (OFF),

27

If kd Ic > md (t) then S = 1 (ON) else S = 0 (OFF),

Design Equations of Isolated PFC

Topologies in CCM and DCM PFC Topology Design Equations

Forward buck Converter Vo = Vin D(N2/N1), with D(1+N3)/N1 < 1

Lo = (1-D) Vo/fs∆iLo

Lo min = {Vin(N2/N1)- Vo}DR/2fsVo (DCM)

Push pull buck Converter Vo = 2 Vin (N2/N1)D

28

Push pull buck Converter Vo = 2 Vin (N2/N1)D

Lo =Vo (0.5-D)/ fs ∆iLo

Lo min = (0.5-D) R/(2f) (DCM)

Half bridge buck Converter Vo = D (N21/N1) Vin, N21=N22

Lo =Vo (0.5-D)/ fs ∆iLo

Lo min = (0.5-D) R/(2f) (DCM)

Full bridge buck converter Vo = 2 (N21/N1) Vin D and N21=N22

Lo = Vo (0.5-D) / (fs ∆iLo)

Lo min = (0.5-D) R/(2f) (DCM)

Design Equations of Isolated PFC

Topologies in CCM and DCM

Forward boost Converter Vo = Vin (N2/N1) / (1-D)

Li= Vin D/ (∆ILi) fs

Lo = Vin D/(∆iLo fs)

Lo min = {Vin(N2/N1)- Vo}DR/2fsVo (DCM)

Push pull boost Converter Vo = Vin (N2/N1)/ {2 (1-D)}

L = V D/(f ∆i )

29

Li = Vin D/(fs ∆iLi)

Li min= (1-D)2 R/{2fs (N2/N1)2} (DCM)

Half bridge boost Converter Vo = Vin (N2/N1) / {2(1-D)}

Li = Vin D/(4fs ∆iLi)

Li min= (1-D)2 R/{2fs (N2/N1)2} (DCM)

Full bridge boost converter Vo = Vin (N2/N1)/{2(1-D)}

Li = (0.5- D) Vin/ (fs ∆iLi)

Li min= (1-D)2 R/{2fs (N2/N1)2} (DCM)

Design Equations of Isolated PFC

Topologies in CCM and DCM Flyback Converter Vo = Vin {D /(1-D)} (N2/N1)

Lm = Vin D/ (fs ∆iLm)

Lm min = {Vin(N2/N1)- Vo}DR/2fsVo (DCM)

Cuk Converter Vo = D (N2/N1) Vin / (1-D)

Li = Vin D/ (fs ∆iLi)

L = V (1-D) / (f ∆i )

30

Lo = Vo (1-D) / (fs∆iLo)

C1 =Vin (N2/N1)2 D2/{Rfs(1-D) ∆VC1}

C2 = VoD/(Rfs ∆VC2)

Li min = RL (1-D)2/ {2Dfs(N2/N1)2} (DCM)

SEPIC Converter Vo = Vin (N2/N1)D/(1-D)

Li = Vin D/(fs ∆iLi)

Lm = Vo (1-D) / (n fs ∆iLm)

C1 = (N2/N1)Vo D/(Rfs ∆VC1)

Li min = RL (1-D)2/ {2Dfs(N2/N1)2} (DCM)

Design Equations of Isolated PFC

Topologies in CCM and DCM Zeta Converter Vo = (N2/N1) Vin D/(1-D)

Lm = Vin D/(fs ∆iLm)

Lo = Vo (1-D)/ (fs ∆iLo)

C1 = Vo D/(R fs ∆VC1)

Li min = RL (1-D)2/ {2Dfs(N2/N1)2} (DCM)

DC Link Capacitor for C =I /2ω∆V

31

DC Link Capacitor for

all Converters

Co=Iav/2ω∆Vo

DC-DC Converters

There are mainly two types of DC-DC converter topologies

� Non-isolated converter

� Isolated converter

32

Non Isolated Converter

� Buck converter

� Boost converter

� Buck-Boost converter

� Cuk converter

� SEPIC converter� SEPIC converter

� Zeta converter

33

Buck Converter

34

Boost Converter

35

Buck-Boost Converter

36

Cuk Converter

37

SEPIC Converter

38

Zeta Converter

39

Simulation ResultsSimulation Results

40

Buck Converter

41

Boost Converter

42

Buck Boost Converter

43

SEPIC Converter

44

ZETA Converter

45

Isolated Converter

• Forward buck converter

• Forward boost converter

• Flyback converter

• Push-pull buck converter

• Push-pull boost converter

• Half bridge buck converter• Half bridge buck converter

• Half bridge boost converter

• Full bridge buck converter

• Full bridge boost converter

• Cuk converter

• SEPIC converter

• Zeta converter

46

Forward Buck Converter

47

Forward Boost Converter

48

Push-Pull Buck Converter

49

Push-Pull Boost Converter

50

Half-Bridge Buck Converter

51

Half-Bridge Boost Converter

52

Full-Bridge Buck Converter

53

Full-Bridge Boost Converter

54

Flyback Converter

55

Cuk Converter

56

SEPIC Converter

57

Zeta Converter

58

Simulation ResultsSimulation Results

59

Forward Buck Converter

Various Waveforms

60

Buck Push Pull Converter

61

Half Bridge Converter

62

Buck Full Bridge Converter

63

Boost Push-Pull Converter

64

Boost Half Bridge Converter

65

Flyback Converter

66

Cuk Converter

67

SEPIC Converter

68

ZETA Converter

69

MATLAB Model of Forward Buck

Converter CCM Operation

powergui

Discrete ,

Ts = 1e-006 s.

v+-A +

Sw pulse

Out1PF Measg1

2

Vdc 1

Is Vs

Gate

+

+VdcPulses

+

70

B -

Ism

Ia

Vdc

Vs

t

1

Idc

ILoad

Is

ILoad

Vdc1 Vdc

Idc

Vdc1

Is

ILoad

Vdc

Idr

Idr

Isw

Vs

Is

ILoad

Isw

Idc

Forward Buck

--Vdc

In RMS

In RMS

In Mean

In Mean

i+-

i+

-

AC Source

-

Simulation of Forward Buck Converter CCM Operation

Source current waveforms and its THD under CCM operation

71

MATLAB Model of Forward Buck

Converter DCM Operation

powergui

Discrete ,Ts = 1e-006 s.

v+-A +

Sw pulse

Out1

g1

2

Vdc 1

ILoad

Gate

+

+Vdc

i+

Pulses

+

72

B -

Ism

Ia

Vdc

Vs

t

PF Meas 2

ILoad

Is

ILoad

Vdc

Idc

Vdc1

Is

ILoad

Vdc

Vs

Is

Vs

Forward Buck

--Vdc

i+

-

AC Source

-

Simulation of Forward Buck Converter DCM Operation

Source current waveforms and its THD under DCM operation

73

PSIM Model of Flyback ConverterCCM Operation

Average current control of Flyback AC–DC converter under CCM operation

74

Simulation of Flyback ConverterCCM Operation

Source voltage and current waveforms and Current THD in Flyback converter

under CCM operation 75

PSIM Model of Flyback ConverterDCM Operation

Voltage Follower control of Flyback AC–DC converter for DCM operation

76

Simulation of Flyback ConverterDCM Operation

Source voltage and current waveforms and Current THD in Flyback

converter under DCM operation 77

PSIM Model of Cuk ConverterCCM Operation

Average current control of Cuk AC–DC converter under CCM operation

78

Simulation of Cuk ConverterCCM Operation

Source voltage and current waveforms and Current THD in Cuk converter under CCM

operation79

PSIM Model of Cuk ConverterDCM Operation

Voltage Follower control of Cuk AC–DC converter for DCM operation

80

Simulation of Cuk ConverterDCM Operation

Source voltage and current waveforms and Current THD in Cuk

converter under DCM operation81

PSIM Model of SEPIC ConverterCCM Operation

Average current control of SEPIC AC–DC converter under CCM

operation

82

PSIM Model of SEPIC ConverterDCM Operation

Voltage Follower control of SEPIC AC–DC converter under DCM operation

83

Simulation of SEPIC ConverterDCM Operation

Hardware Result of SEPIC AC–DC converter under DCM operation at 60

W Load

Simulation of SEPIC ConverterDCM Operation

Hardware Result of SEPIC AC–DC converter under DCM operation during

Load perturbation from 60 W to 200 W to 60 W

Implementation of SEPIC ConverterDCM Operation

The THD of source current for 200 W Load

Implementation of Zeta ConverterDCM Operation

Hardware Result under DCM operation at 60 W Load

Implementation of Zeta ConverterDCM Operation

Hardware Result under DCM operation during Load perturbation from 60

W to 200 W to 60 W

Implementation of Zeta ConverterDCM Operation

The THD of source current for 200 W Load

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References contd…

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References contd…

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