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Principle and Design Application of Half-Bridge LLC Resonant Converter

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OUTLINE

I. Introduction

II. Review of Switching Characteristics

III. Traditional Resonant Topologies

IV. Half-Bridge LLC Resonant Converter

V. Half Bridge LLC Resonant Converter

Operation Principle

VI. Design Guidelines and Example

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I. Introduction

� Typical applications of power electronics include AC-DC,

DC-AC, AC-AC and DC-DC.

� The requirements of power converter include small size,

light weight, high efficiency and high power density.

� Hard-switching PWM converters suffer from high switching

losses, high switching stresses and high EMI noise.

� Soft-switching PWM converters can alleviate these problems

in which a high switching frequency operation can be

achieved.

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II. Review of Switching Characteristics

� Limitations of hard-switching PWM converters� Operating frequency (50~200kHz)� Power density� EMI

� Review of soft-switching techniques� Zero-voltage switching (ZVS)� Zero-current switching (ZCS)

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� Load-line trajectories of power switches

ON

OFF

I

SOA

hard-switching

soft-switching

V

B

A 1

A2

Load-line trajectories illustrating switching transitions

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� Switching losses

� Turn-on loss due to reverse-recovery current of the freewheeling diode

� Turn-on loss by drain-to-source capacitance

� Turn-off loss

dt)t(i)t(vW DSDSont

D ∫= 0

DS)DSv(DS

DSV

DSdsC dCvW ν∫=0

dt)t(i)t(W DS

offt

DSoff ∫=0

ν

STMicroelectronics

Ш. Traditional Resonant Topologies

� Three Traditional Resonant Topologies

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� Series Resonant Converter (SRC)

� Parallel Resonant Converter (PRC)

� Series Parallel Resonant Converter(SPRC)

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� Series Resonant Converter

Half Bridge Series Resonant Converter

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DC Characteristics and Operating Region of SRC

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� Parallel Resonant Converter

Half Bridge Parallel Resonant Converter

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DC Characteristics and Operating Region of PRC

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� Series Parallel Resonant Converter

Half Bridge Series Parallel Resonant Converter

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DC Characteristics and Operating Region of SPRC

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IV. Half Bridge LLC Resonant Converter

VoutNs1

Ns2

Vin

Lm Np

Lr

C1Q1 CQ1

DQ1

Q2 CQ2

DQ2

D1

D2C2

C0

T1

� Type 1 Half Bridge LLC Resonant Topologies

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VoutN

Ns2

Vin

Np

Lr

Q1

DQ1

Q2

D1

D2

Cr

Lm

DQ2

C0

T1

s1

� Type 2 Half Bridge LLC Resonant Topologies

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�LLC Resonant Tank

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�LLC DC Characteristics

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� LLC DC Characteristics for ZVS/ZCS Region

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� LLC DC Characteristics for Three Operating Region

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� LLC DC Characteristics for Two Resonant Frequency

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VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

T1

V. Half Bridge LLC Resonant Converter operation Principle

� Mode 1 (t0~t1)

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� Mode 1 (t0~t1)

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VoutNs1

N

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

s2

T1

� Mode 2 (t1~t2)

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� Mode 2 (t1~t2)

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Vout

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

Ns2

Ns1

T1

� Mode 3 (t2~t3)

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� Mode 3 (t2~t3)

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VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 CQ2

Q1 CQ1

C2

T1

� Mode 4 (t3~t4)

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� Mode 4 (t3~t4)

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VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

T1

� Mode 5 (t4~t5)

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� Mode 5 (t4~t5)

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� Mode 6 (t5~t6)

VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

T1

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� Mode 6 (t5~t6)

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� Mode 7 (t6~t7)

VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2 DQ2

Q1 DQ1

C2

T1

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� Mode 7 (t6~t7)

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� Mode 8 (t7~t8)

VoutNs1

Ns2

Vin

Lm Np

Lr

C1

D1

D2

Co

Q2

Q1

C2

T1

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� Mode 8 (t7~t8)

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�Control Circuitry Design

• ST L6599 Resonant Controller Featured

Description

• Pin function description

• L6599 operate frequency

� Design Example and Test Result

VI. Design guidelines and example

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� Control Circuitry Design

� ST L6599 Resonant Controller Featured Description

MAIN FEATURES• 50% DUTY CYCLE, VARIABLE FREQUENCY CONTROL OF RESONANT HALF-BRIDGE• UP TO 500 kHz OPERATING FREQUENCY• INTERFACE WITH PFC CONTROLLER• LATCHED DISABLE INPUT• BURST-MODE OPERATION AT LIGHT LOAD• INPUT FOR POWER-ON/OFF SEQUENCING• OR BROWNOUT PROTECTION• NON-LINEAR SOFT-START FOR MONOTONIC• OUTPUT VOLTAGE RISE

600V-RAIL COMPATIBLE HIGH-SIDE GATE• DRIVER WITH INTEGRATED BOOTSTRAP• DIODE AND HIGH dV/dt IMMUNITY

-300/800 mA HIGH-SIDE AND LOW-SIDE

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Internal Block Diagram of the L6599

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Pins Function of the L6599

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L6599 operate Frequency

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Fmin & Fmax

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� Design Example and Test Result

� Specification:Input Voltage: 90VAc~264VAcOutput Voltage: 24V/6A 12V/3A 18V/3AResonant Frequency: 75kHz

� Resonant Component Rating:L101: 200uHC101/C102: 0.022uF/630VLm: 1mHNp: 54T; Ns1:6T; Ns2:3T

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Load setting

30.236Load5

00.236Load4

20.51.53Load3

10.20.26Load2

10.0530.2Load1

+18V+5Vs+12V+24V

Unit: A

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Efficiency

Vac-efficiency

84.00%

86.00%

88.00%

90.00%

92.00%

0 50 100 150 200 250 300 Vac

Eff

icie

ncy

Load4(η)

Load5(η)

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Regulation1

84.76%235.80278.2018.244.9611.9124.06Load5

86.16%181.20210.3018.254.9611.9124.08Load4

84.79%128.96152.1018.224.9511.9324.05Load3

85.22%164.04192.5018.224.9512.2523.73Load2

80.57%58.1772.2018.244.9511.6024.43Load1

EfficiencyPoutPin+18V+5Vs+12V+24V

Unit:VVin=90Vac

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Regulation2

85.76%235.83275.0018.254.9611.9124.06Load5

87.03%181.20208.2018.244.9511.9124.08Load4

85.29%128.96151.2018.224.9511.9324.05Load3

85.84%164.04191.1018.224.9512.2523.73Load2

80.80%58.1772.0018.244.9511.6024.43Load1

EfficiencyPoutPin+18V+5Vs+12V+24V

Unit:VVin=100Vac

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Regulation3

89.43%235.74263.6018.224.9511.9124.06Load5

90.11%181.20201.1018.234.9611.9124.08Load4

87.97%128.96146.6018.224.9511.9324.05Load3

88.96%164.04184.4018.224.9512.2523.73Load2

83.69%58.1669.5018.234.9511.6024.43Load1

EfficiencyPoutPin+18V+5Vs+12V+24V

Vin=220VAC

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Regulation4

90.05%235.74261.8018.224.9511.9124.06Load5

90.98%181.23199.2018.244.9511.9224.08Load4

88.23%128.47145.6018.224.9511.6024.05Load3

89.39%164.04183.5018.224.9512.2423.73Load2

83.82%58.1769.4018.244.9511.6024.43Load1

EfficiencyPoutPin+18V+5Vs+12V+24V

Vin=260VAC

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