control of boost crm pfc converters

8/14/2019 Control of Boost CRM PFC Converters

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Prof. Ying-Yu Tzou

808DSP/FPGA

http://pemclab.cn.nctu.edu.tw/

Lab-808: Power Electronic Systems & Chips Lab., NCTU, Taiwan

Digital Voltage Control of Boost CRM PFC AC/DC

Converters with TRIAC Phase Control Dimmer

LAB808

NCTU

Lab808:

Power Electronic Systems & Chips, NCTU, TAIWAN

Depart. of Electrical Engineering,

National Chiao Tung Univ., Hsinchu, Taiwan


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Contents

Introduction

TRIAC Phase Control Dimming Method Digital Voltage Control Loop Design

Simulation and Experimental Results

Conclusion


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TRIAC Dimming Control Circuit

)(tvin

)(tvtriac

)(tG

Delay

Line Voltage and Dimming Waveforms

AC

DIM

BRIGHT k250R1

k3.3R2

nF100C1

DIAC

TRIAC

GK

A

Basic TRIAC Dimmer

ci

cv

The role of R1 to adjust the size of the capacitive current

Delay time of the decision by the C1 and (R1+R2)

121 C)R(RT

)(tvin


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4/23

TRIAC Dimmer Fired with Ideal Line Voltage in Different

Load Conditions

(a) resistive load

(b) inductive load (c) capacitive load


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LM3445 Triac Dimmable Offline LED Driver (NS)

Features:

Triac dim decoder c ircuit for LED dimming

Application voltage range 80VAC 270VAC Capable of contro ll ing LED currents greater

than 1A

Adjustable switching frequency

Low quiescent current

Adaptive programmable off -time allows forconstant r ipple current

Thermal shutdown

No 120Hz flicker

Low profile 10 pin MSOP Package

Patent pending drive architecture

Applications:

Retro Fit Triac Dimming

Solid State Lighting

Industrial and Commercial Lighting Residential Light ing


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LT3799 Offline Isolated Flyback LED Controller with

Active PFC


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Digital vs. Analog PFC Control ler

Digi tal control provides flexibility for contro l algori thm realization

Synchronous current sampling and feedback signal reconstruct ion

Interleaved control for load current sharing

Robust performance for line and load variations

Efficient optimization across the entire load curves

(a) Analog PFC Controller (b) Digital PFC Controller

Iin

IL

D

CSLV

in

Kv

Vref

Vv-sam

RviRvfC

vfVp

Viref

Vc-sam

Ki

PWM

EA1

EA2

Rcz C

cz

Rci

Vc Vpwm

PWM

Vout Vout

Vref

Vv-samViref

Vc-sam

Vpwm

Vp

A/D

A/D

ILI

in

Vin

L

D

CSinVinV

inV

inV

Vc

)1()(

)()1()(

4

43

4

43

kVK

KKT

kVK

KKkVkV

c

opwmpwm

MULTMULT

A/D

samvsamv

samvpp

VTKkVKTK

kVKkVkV

212

1

)1()(

)()1()(


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Digital PFC Controller for LED Lighting Applications

85~265V

50~60 Hz

Digi tal PFC

controller

Digital

PWM

Controller

Digital

PWM

Controller

Digital

Lighting

Controller


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Proposed Digital Control Scheme for CRM Boost PFC

Converters

oC

DL

Q

)(tvin

)(tiL )(tiD

Q

i

)(tVi

oV

)(tiin

LR

3R

4R

1R

2R

refvVoltage Loop Controller

S Q

R Q

][* nibL

ZCD(t)

][nVcomp

)(tVo

sR

A/DA/D

D/A

inC

TRIAC

DIMMING

LC Low-Pass Filter

][nVo

][nVerr

)(tVi

][nVi

)(* ti bL

)(tisw

)(tio

ConductionAngle

)(t

ZCDR

zD

refZV ,


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Current Control Strategies for Boost PFC Converters

LRfC

fL D

S

PFCController

iL

oV

rV

iave

iL

Peak Current Control

iave

Boundary Control Mode (CRM)

iavehigh reflow ref

Variable Hysteresis Control

TON

iave

Average Current Control

iref


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Comparison of PFC Technologies


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Small-Signal Modeling of Boost PFC Converters

Boost single-phase PFC converter with an inner current loop and an outer voltage loop.

Small-signal model of the PFC converter

)(sZin

)(sZin

InputImpedance ofPFC Converter


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Input Impedance In Consideration of Input Filter

Q

DL

PFC

Controller

Li

ov

*

ov

TRIAC

Dimmer

gvInput Impedance'

inZ

)()(1

)()('

ssZCC

sZsZ

inacdc

inin

)1

(1

)(

)(

)()(

2

nl

s

z

l

s

in

inin

LgR

Rs

sp

gR

R

sI

sVsZ

)(sHc

sL1

sR

)(sIin)(sV

in

m

o

V

V

)(sIR refl

)(sL

(a) The ringing input current greater than holding current ofTRIAC (b) The ringing input current less than holding current of TRIAC.


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LC Filter with Damping Resistor Circuits

LPFL

LPFC

damperR

)(tvin

+

-

)(tIin

FB+

PFC

PowerSource

+TRAICDimmer

L

C

damperR

)(tvtriac

+

-

)(tIin

FB+

PFC

PowerSource

+

TRAICDimmer

Small-signal equivalent circuit of the boost PFC converter.


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Output Power as a Function of Conduction Angle

)degree(

2

T

Full power

Dimming state

(a) Full load and half load input voltage waveform.

The linear area of output power is from the conduction angle 30 degreeto 150 degree.

When the conduction angle becomes smaller (


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Dimming with Variable DC Link Voltage

DC-link voltage as a function of conduction angle.

is the conduction angle, b is a parameter to adjust the drop slop. The dc link voltage decrease from conduction angle 90 degree to 0

degree.

The minimum dc link voltage must greater than maximum input voltage,since the PFC is a boost circuit.


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Modeling amd Control of the PFC Preregulator

(a) Detail of the resistor emulator control scheme.(b) Ideal waveforms with no ripple on the error amplifier.

(c) Real waveforms.

Low-pass filter corner frequency

Maximum power that complies with IEC 61000-3-2 regulations for different corner frequencies

of the voltage regulator.

VREF

vo

C2

R2vea

B

Current Loop

Voltage Loop

Sinusoidalwaveform

Multiplier

vea

Current reference

Control SignalVoltage Loop

1

2

RRAR

222

1

CRfC

Vea vea(t)

CurrentReference

CurrentReference

)sin( tVin

)sin( tk

VV inea )sin( t

k

VV inea

)sin( tVin Sinusoid Sinusoid

R1

voi1

i1

0 10 20 30 40 50 60 70 80 90 100500

1000

1500

2000

2500

3000

3500

4000

P(W)

AR

fC=1kHz

fC=500Hz

fC=100Hz

(c)

(a)

(b)

X

F f th di it l lt l i


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Frequency responses of the digital voltage loop gain


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Simulation Results of Steady-State Responses

Simulation results of steady-state response of the input line current and the inputvoltage through the TRIAC dimmer with a rated load of 25 W.

(a) no damping resistor. (b) with a 1 k damping resistor.


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Simulation Results of Transient Responses

Simulation results of transient response of the output voltage for dimming time is0.1s. Load changing from 25 W to 4 W

(a) Constant dc-link voltage. (b) Variable dc-l ink voltage.


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System Parameters and Experiment Setup

Monitor PC

Emulator

TMS320F2812

TRIAC

AC InInterfaceCircuitFLYBACK

Converter

LEDsLoad

DC power supply


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Experimental results for the dimmable LED system with

digital PFC control at different phase control angles.

150

90

30

(a)

(b)

(c)

0 20 40 60 80 100 120 140 160 1800

5

10

15

20

25

30

35

40

45

50

Conductin Angle (degree)

OutputPower(W

)

Dimming Curve

Output pow er as a function of phase conduction angle.


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Conclusion

Wide Dimming Control Range 5~100% Rated Power

No Flickering

Digital PFC Control Scheme for TRIAC Dimming Control

Passive Damping Technique to Reduce TRIAC Ringing

Variable DC-link Voltage Modulation Method

Experimental verification has been carried out on a DSP(TMS320F2812) controlled PFC CRM Converter.

control of boost crm pfc converters

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