LLC Resonan Converer Reference Design using he dspic DSC 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 1 Hello, and welcome o his web seminar on Microchip s LLC Resonan Converer Reference Design. My name is Alex Dumais, and I am a Senior Applicaions Engineer in he High performance Microconroller Division of Microchip. 1
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 2 In his webinar, we will sar wih some background informaion on resonan converers and why resonan converers are gaining ineres. Then we will discuss differen resonan converer opologies wih an emphasis on LLC resonan converers. Aferwards we will go hrough he design of Microchip s 200W LLC Resonan Converer Reference Design. So le s ge sared wih some background informaion on resonan converers. 2
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 3 In his webinar, we will sar wih some background informaion on resonan converers and why resonan converers are gaining ineres. Then we will discuss differen resonan converer opologies wih an emphasis on LLC resonan converers. Aferwards we will go hrough he design of Microchip s 200W LLC Resonan Converer Reference Design. So le s ge sared wih some background informaion on resonan converers. 3
Why Resonan Converers 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 4 Wih he push for higher efficiency converers, power supply designers are looking for differen opologies o improve heir power supply efficiency. One such opology ha has been gaining ineres is he resonan converer. Unil recenly, resonan converers have been overlooked due o he complexiy of conrol. The dspic digial signal conroller wih is advanced peripherals and highspeed DSP engine provides he capabiliy o easily conrol complex sysems such as Resonan Converers. 4
High Efficiency Why Resonan Converers 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 5 Resonan converers are becoming more and more popular hese days due o heir abiliy o achieve high efficiency hrough sofly commuaing he swiching devices. 5
High Efficiency Why Resonan Converers Sof-Swiching Converers 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 6 Sof-swiching echniques, such as Zero-Volage Swiching and Zero-Curren Swiching can be implemened which provides beer EMI performance along wih higher efficiency 6
High Efficiency Why Resonan Converers Sof-Swiching Converers Higher Power Densiy 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 7 Resonan Converers are capable of achieving higher power densiy meaning he overall converer size can be reduced as he converer can operae a higher swiching frequencies due o sof-swiching described above 7
High Efficiency Why Resonan Converers Sof-Swiching Converers Higher Power Densiy High Power Applicaions 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 8 Resonan Converers are well suied for high power applicaions 8
High Efficiency Why Resonan Converers Sof-Swiching Converers Higher Power Densiy High Power Applicaions Wide Inpu Volage Range 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 9 They work well over a wide inpu volage range 9
High Efficiency Why Resonan Converers Sof-Swiching Converers Higher Power Densiy High Power Applicaions Wide Inpu Volage Range Lower Cos 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 10 Lower cos Due o heir Higher swiching frequencies he size of passive componens can be reduced 10
Concep of Resonan Converers V dc - Full / Half Bridge Converer Resonan Tank Recifier Filer V ou - 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 11 This slide demonsraes a high-level, he archiecure of any resonan converer. A resonan converer can be divided ino four main block ses: he full/half Bridge Converer, a Resonan Tank, a Recifier, and a low-pass filer. Saring on he inpu side he full/half bridge converer is ypically configured in complemenary mode wih a fixed duy cycle (~50%) and wih some dead-ime. The bridge converer is ypically operaed by adjusing he duy cycle bu in he case of he resonan converer he bridge converer is frequency conrolled. This means ha by changing he frequency of he converer we change he impedance of he resonan ank. We will discuss more on his a a laer ime. 11
Concep of Resonan Converers V dc - Full / Half Bridge Converer Resonan Tank Recifier Filer V ou - Resonan Inverer 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 12 The oupu of he bridge converer is a square wave wih fixed duy cycle, wih an ampliude equal o Vdc and a DC offse of Vdc/2. 12
Concep of Resonan Converers V dc - Full / Half Bridge Converer Resonan Tank Recifier Filer V ou - Resonan Inverer 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 13 The resonan ank is made up of reacive componens (capaciors and inducors) and can have several differen configuraions. Depending on he ank configuraion, he oupu will have eiher a sinusoidal curren or volage. The resonan ank will inroduce a phase shif beween he volage and curren and because of his we are able o achieve sof-swiching. 13
Concep of Resonan Converers V dc - Full / Half Bridge Converer Resonan Tank Recifier Filer V ou - Resonan Inverer 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 14 Combining he bridge converer and he resonan ank we creae a resonan inverer and by adding a recifier and low pass filer we creae a resonan converer. 14
Wha is Resonance Resonance occurs in a circui a a paricular frequency where he impedance beween he inpu and oupu of he circui is a is minimum. 1 X C := jωc A a paricular frequency wo Reacance s will be equal in magniude bu opposie in sign X L = - X C V Z := I X L := jωl 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 15 Before we dive any deeper ino resonan converers we should firs undersand a couple erms ha are commonly used in describing resonan converers. So firs le us look a he meaning of resonance. In a simple series LC circui (shown in boom righ) here exis a poin where he reacance of he capacior and he reacance of he inducor are equal in magniude bu opposie in sign. A his paricular frequency he reacance is zero and he impedance beween he inpu and he oupu of he circui is a i s minimum. If we look a he impedance vs. frequency plo we will see ha he summaion of he capacior and inducor reacance is a i s minimum a he resonan poin. 15
Qualiy Facor Qualiy Facor (Q), of a resonan circui is a dimensionless parameer ha describes how damped a resonan circui is. The higher he Qualiy Facor he more narrow he bandwidh. Q is he raio beween he power sored and he power dissipaed in he circui. General Definiion: Q = P sored / P dissipaed = I 2 X / I 2 R 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 16 Anoher erm used o describe resonan converers is Qualiy Facor. Qualiy Facor (Q) is a dimensionless parameer ha describes how damped a resonan circui is. The higher he Qualiy Facor he narrower he bandwidh of he sysem. As a general definiion Qualiy Facor can be defined as he raio beween he power sored and he power dissipaed in he circui. I is imporan o noe ha he Qualiy Facor changes wih load, (i.e. i is no a fixed parameer). 16
Sof Swiching 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 17 As discussed earlier, resonan converers are able o achieve high efficiency from employing sof-swiching echniques. The following slides discuss wha hese sofswiching echniques are and heir advanages. 17
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds G D I d S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 18 The following animaion demonsraes Zero Volage Swiching. 18
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds V ds () G D I d S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 19 Firs he drain-o-source capaciance of he MOSFET is discharged. 19
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds V ds () G D I d S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 20 Nex he PWM enables he MOSFET allowing he curren hrough he MOSFET o begin o rise 20
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds V ds () I d () G D I d S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 21 When he PWM is disabled he drain-o-source volage begins o rise bu he curren sill flows hrough he MOSFET. 21
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds V ds () I d () G D I d S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 22 When he PWM is disabled he drain-o-source volage begins o rise bu he curren sill flows hrough he MOSFET. 22
Zero Volage Swiching A ransiion period from one sae o anoher sae of he MOSFET, he volage is zero, hence no losses ZVS demonsraed only a Swich urn-on V ds I d V ds () ZVS I d () G D S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 23 From his animaion we can see ha a swich urn-on we are eliminaing he MOSFET swiching losses as he volage across he drain-o-source is zero (ZVS). A swich urn-off we see ha here will be a significan amoun of curren and volage a he ransiion sae which ranslaes ino swiching losses. Zero Volage swiching is preferred in high-volage, high-power applicaions. 23
Zero Curren Swiching A ransiion period from one sae o anoher sae of he MOSFET, curren is zero, hence no losses ZCS demonsraed only a Swich Turn-OFF V ds G D S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 24 The following animaion demonsraes Zero Curren Swiching. 24
Zero Curren Swiching A ransiion period from one sae o anoher sae of he MOSFET, curren is zero, hence no losses ZCS demonsraed only a Swich Turn-OFF V ds I r () V ds () G D S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 25 Firs he PWM is enabled and he curren hrough he MOSFET begins o rise as he MOSFETs drain-o-source volage drops. 25
Zero Curren Swiching A ransiion period from one sae o anoher sae of he MOSFET, curren is zero, hence no losses ZCS demonsraed only a Swich Turn-OFF V ds I r () V ds () G D S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 26 Once he curren hrough he MOSFET becomes zero, we disable he MOSFET. Now he drain-o-source volage begins o rise. 26
Zero Curren Swiching A ransiion period from one sae o anoher sae of he MOSFET, curren is zero, hence no losses ZCS demonsraed only a Swich Turn-OFF V ds I r () V ds () ZCS G D S PWM 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 27 This is he poin a which zero curren swiching occurs From he animaion we can see ha a swich urn-off we are eliminaing he MOSFET swiching losses as he curren is zero and he drain-o-source volage is also zero. A swich urn-on we see ha here will be a significan amoun of curren and volage a he ransiion sae which ranslaes ino swiching losses. Zero Curren swiching can be implemened a swich urn-on as well as urn-off. Wih sof-swiching we can reduce he noise in he sysem, herefore improving EMI performance. 27
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 28 Nex we will ake a closer look a hree differen resonan converer opologies. 28
Series Resonan Converer Resonan ank (L R & C R ) is in series wih he oupu load Resonan ank and he load ac as a volage divider (M <= 1) SRC can work a no load bu oupu volage can no be regulaed For ZVS, need o operae above resonance (negaive slope) A low line SRC operaes closer o resonan frequency 1 f r := 2 π L r C r 1 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) M f n, 10 M f n, 9 M f n, 8 M f n, 7 M f n, 6 M f n, 5 M f n, 4 M f n, 3 M f n, 2 M f n, 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Q - Curves 0.01 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.1 f n 2 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 29 For a series resonan converer he resonan ank is composed of inducor Lr and capacior Cr in a series configuraion (shown in schemaic). I is called a series resonan converer because he resonan ank is in series wih he oupu load. Here he resonan ank and he oupu load ac as a volage divider and herefore limiing he gain of he ank o be less hen or equal o one. Looking a he Volage gain curves (boom righ diagram) we see ha all Q-curves inersec a he resonan frequency poin (Fn = 1, and Gain = 1). From he volage gain plo we can also see ha he converer operaes closer o resonance when he inpu volage is a low line. For Zero Volage Swiching he converer mus work a or above resonance. 29
Parallel Resonan Converer Load is in parallel wih resonan capacior PRC can operae a no load For ZVS, need o operae above resonance (negaive slope) A low line PRC operaes closer o resonan frequency High circulaing currens Inherenly shor circui proeced 8 8 1 f r := 2 π L r C r ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) M f n, 10 M f n, 9 M f n, 8 M f n, 7 M f n, 6 M f n, 5 M f n, 4 M f n, 3 M f n, 2 M f n, 1 7 6 5 4 3 2 1 Q - Curves 0 0 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5.4 f n 1.6 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 30 For a parallel resonan converer, he resonan ank is similar o ha of he series resonan converer bu now he oupu load is conneced in parallel wih he resonan capacior Cr. Similar o he series resonan converer, he parallel resonan converer will operae closer o resonan frequency a low-line, and for Zero-Volage swiching he converer should work a or above resonance. Unlike he series resonan converer, he parallel resonan converer can operae a no load. One disadvanage of he parallel resonan converer is ha is will operae wih high circulaing currens, even a no load condiions. 30
Series-Parallel Resonan Converer - LLC Can operae a resonance a nominal inpu volage The LLC converer is able o operae a no load Can be designed o operae over a wide inpu volage Zero volage swiching is achievable over he enire operaing range Zero curren swiching is achievable over he enire operaing range 0.5 1 f r := 1 f 2 π L r C r2 := r 2 π L r L pr 0.039 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 ( ) C r 3 3 2.5 M( f n, 1) M( f n, 0.9) M( f 2 n, 0.8) M( f n, 0.7) M( f n, 0.6) 1.5 M( f n, 0.5) M( f n, 0.4) M( f n, 0.3) 1 M( f n, 0.2) M( f n, 0) 0.1 f n Q - Curves 2 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 31 Series-parallel converers are a combinaion of he series resonan converer and he parallel resonan converer. Here we are showing an LLC resonan converer which is composed of wo inducors and a single resonan capacior. Anoher common Series-Parallel resonan converer is he LCC converer which replaces he inducor Lpr wih anoher capacior as in he parallel resonan configuraion. LLC resonan converers have many advanages: They can operae a resonance a nominal inpu volage They can operae a no load condiions Have lower circulaing currens hen he parallel resonan converer The advanages of resonan converers are heir abiliy o operae over a wide inpu volage range and he fac ha ZVS/ZCS is achievable over he enire operaing condiion. 31
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 32 Nex we will examine he differen operaing modes of an LLC Resonan Converer. 32
Operaion @ Resonance 0 1 2 3 4 5 6 Q1 D1 C1 V DS1 D3 C r L r V dc C o R o I Q2 D2 C2 L m V p V s2 D4 Vo V dc < 0 : Q1 off; Q2 on D3 off; D4 on V dc The volage drop on upper cap C1 is V dc. A 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 33 Firs we will sar ou by examining, in deail, he operaional waveforms when he sysem operaes a resonan frequency. For simpliciy we are showing a half-bridge converer on he primary side and a full-wave recifier on he secondary. Diodes D1,D2 and Capaciors C1, C2 have been explicily drawn here bu are essenially par of he MOSFETs parasiics. A ime <0, he boom MOSFET (Q2) is conducing and diode (D4) is forward biased. The volage drop across capacior C1 is equal o he inpu volage (Vdc). 33
Operaion @ Resonance 0 1 2 3 4 5 6 Q1 D1 C1 V DS1 D3 V dc C r L r V s1 C o R o I Q2 D2 C2 L m V p V s2 D4 Vo V dc 0 < < 1 : Q1 off; Q2 off (dead ime); D3 off; D4 off V dc 1. Primary curren is magneizing curren 2. Curren splis beween he wo MOSFET caps, discharging C1 and charging C2 3. Magneizing curren mus complee caps charge /discharge before dead ime end 4. Pars/dead ime mus be seleced accordingly A 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 34 A ime 0<<1, boh MOSFETs are disabled (known as dead-ime region) and boh secondary diodes D3, D4 are reversed biased. A his ime he oupu capacior is supplying he required load curren. On he primary side we see ha he magneizing curren is flowing and will begin o discharge capacior C1 and charge capacior C2. The magneizing curren mus be large enough o charge/discharge he capaciors before he dead-ime inerval ends. 34
Operaion @ Resonance 0 1 2 3 4 5 6 Q1 D1 C1 D3 V dc C r L r V s1 C o R o I Q2 D2 C2 L m V p V s2 D4 Vo V dc 1 < < 2: Q1 off -> on; Q2 off D3 off -> on; D4 off V dc 1. Diode D1 sars conducing 2. Swich Q1 can be closed a any ime during his inerval wih zero vols across i 3. Zero Volage Swiching (ZVS) is obained. A 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 35 A he ime inerval 1<<2, he high side MOSFET (Q1) begins o ransiion o he on-sae. Iniially he magneizing curren is negaive and he inernal body diode of he MOSFET will be forward biased. Diode D3 is also ransiioning o forward biased. When MOSFET (Q1) is enabled, he drain o source volage is zero, herefore Zero Volage Swiching is obained. 35
Operaion @ Resonance 0 1 2 3 4 5 6 Q1 D1 C1 D3 V dc C r L r V s1 C o R o I Q2 D2 C2 V DS2 L m V p V s2 D4 Vo V dc 2 < < 3: Q1 on; Q2 off D3 on; D4 off V dc 1. Power ransfer akes place during his inerval 2. Boh componens of he primary curren are significan 3. The magneizing curren is generaed by he secondary volage (Vo) refleced back o he primary. A 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 36 A ime 2<<3, boh MOSFET Q1 and Diode D3 are conducing. This is he firs inerval in which power ransfer akes place. The ank curren is supplied by he inpu volage source and he magneizing curren is generaed by he secondary volage refleced back o he primary by he ransformer urns raio. The magneizing inducor is clamped a his volage, hence he linear rise of magneizing curren. The sinusoidal ank curren flowing in he ransformer will generae a quasisinusoidal curren on he secondary side relaed by he ransformer urns raio. A he end of he swiching cycle he curren flowing hrough diode D3 will be equal o zero, hence zero curren swiching is achieved on he secondary. 36
Operaion @ Resonance 0 1 2 3 4 5 6 Q1 D1 C1 V DS1 D3 V dc C r L r V s1 C o R o I Q2 D2 C2 L m V p V s2 D4 Vo V dc 3 < < 4 : Q1 off; Q2 off (dead ime) D3 off; D4 off 1. Circui behavior is complemenary o he previous dead ime inerval 2. The primary curren is he magneizing curren 3. This curren splis o charge C1 and a he same ime discharge C2. V dc A 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 37 A he ime inerval 3<<4, he primary curren is he magneizing curren. The circui operaion is he same as he previous dead-ime inerval excep now, capacior C1 is being charged while capacior C2 is discharged. The circui operaion for he remaining ime inervals will be he reverse of he firs half cycle. 37
Operaion Below Resonance 0 1 2 x 3 4 5 6 Q1 D1 C1 V DS1 D3 V dc C r Q2 D2 C2 L r L m V p V s1 V s2 D4 C o Vo R o X < < 4 : primary curren equal magneizing curren V dc Secondary mosfes mus be swiched off a ime x. 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 38 Now ha we have reviewed in deail he circui operaion a resonance, we will review he differences in circui behavior when he converer operaes above and below resonance. When operaing below resonance he ank fundamenal sine wave will have a shorer period hen ha of he swiching frequency (decreasing he swiching frequency = an increase in he swiching period). From he figure we can see ha he ank curren will equal he magneizing curren before he half period ends (x 3). From his poin on he curren flowing in he primary is ha of he magneizing curren. 38
Operaion Above Resonance 0 1 2 3 4 5 6 Q1 D1 C1 V DS1 D3 V dc C r L r V s1 C o R o Q2 D2 C2 L m V p V s2 D4 Vo 3: The secondary MOSFETs are swiched off wih he primary. V dc 3 < < 4 : dead ime 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 39 The circui behavior is somehow reversed compared o he operaion below resonance. Since he resonan period is longer hen ha of he swiching period, a he end of he swiching half period, he ank curren is higher han he magneizing curren. During he dead ime inerval he ank curren falls rapidly o he value of he magneizing curren, so ha a new half cycle can sar. 39
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 40 Now ha we have some background informaion on resonan converers we can proceed wih looking a Microchip s 200W LLC Resonan Converer Reference Design. 40
Inpu Range: 350Vdc o 420Vdc 400Vdc nominal Oupu Volage: 12Vdc Oupu Power: 200W High Efficiency: 95% Resonan Frequency: 200KHz Modulaed Frequency: LLC Resonan Converer Reference Design Specificaions 150KHz 220KHz 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 41 The LLC Resonan Converer Reference Design is raed for 200W wih a nominal inpu volage of 400V DC. This LLC reference design is inended o be he second sage in a AC-DC applicaion so he nominal inpu volage is he ypical oupu volage of a PFC converer (385-400V). The abiliy of he LLC converer o operae over a wide inpu range allows he bulk capaciors on he PFC converer (which are required for hold-up ime) o be reduced. As his design is 200W he half-bridge converer was seleced for driving he resonan ank. As for he recifier, he radiional full-wave recifier was replaced wih a synchronous recifier circui, where MOSFETs replace diodes, o improve efficiency. High-volage isolaion (~4kV) separaing he primary and secondary is obained hrough proper componen selecion and magneic srucures. Use of he reference design is Royaly Free, and complee documenaion, sofware, and hardware design informaion is available on he Microchip web sie. Demonsraion unis are also available from worldwide Microchip sales offices. 41
LLC Resonan Converer Block Diagram DC Inpu 350 420Vdc Half-Bridge Converer / Resonan Tank Power Conversion Block Synchronous Recifier Oupu Filer 12V Oupu Load Flyback Auxiliary Power Supply dspic DSC Power Flow Signal Flow Legend I2C Power Managemen Inerface Block PICki Serial Analyzer Compuer 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 42 This slide shows a sysem-level block diagram of he LLC Resonan Converer. A single dspic33f GS series digial signal conroller, shown in he cener of he block diagram, drives he power sages (Half-bridge converer and Synchronous Recifier), performs conrol loop operaions, power managemen communicaion and faul managemen rouines. 42
LLC Resonan Converer Board Layou: 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 43 Now ha we have seen a funcional overview of he LLC Resonan Converer, we can physically locae all secions on a picure of he Reference Design iself. This is a op view of he LLC Resonan Converer Reference Design. Posiions of each block of he sysem are highlighed as follows: 43
LLC Resonan Converer Board Layou: Oupu Inpu 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 44 The inpu erminal can be seen on he boom lef and he oupu erminal on he op righ 44
LLC Resonan Converer Board Layou: Half-Bridge Converer & Resonan Tank Oupu Inpu 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 45 The Half-bridge Converer can be found owards he upper lef side. 45
LLC Resonan Converer Board Layou: Half-Bridge Converer & Resonan Tank Synchronous Recifier Oupu Inpu 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 46 The Synchronous Recifier is locaed on he op righ 46
LLC Resonan Converer Board Layou: Half-Bridge Converer & Resonan Tank Synchronous Recifier Oupu Filer Oupu Inpu 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 47 Oupu Filer on he middle righ hand side 47
LLC Resonan Converer Board Layou: Half-Bridge Converer & Resonan Tank Synchronous Recifier Oupu Filer Oupu Inpu Flyback Auxiliary Power 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 48 Flyback Auxiliary Power on he boom Lef 48
LLC Resonan Converer Board Layou: Half-Bridge Converer & Resonan Tank Synchronous Recifier Oupu Filer Oupu dspic Inpu Flyback Auxiliary Power 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 49 And lasly he dspic DSC is locaed on he boom righ of he board. 49
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 50 Nex we will look a he operaion of he half-bridge converer and he resonan ank. 50
Half-Bridge Converer / Resonan Tank Half-Bridge Converer generaes a square wave wih ampliude = V DC and dc offse of V DC /2 Resonan capacior C R blocks dc componen Resonan ank filers higher harmonics, essenially sinusoidal curren is allowed o flow 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 51 - A circui diagram of he half-bridge converer and he resonan ank is as shown. Two MOSFETs are conneced in a bridge configuraion and he resonan ank is conneced a he Half-Bridge poin. The half-bridge converer is configured in complemenary mode wih a fixed duy cycle (~50%) and wih some dead-ime The dead-ime serves wo purposes: firs, i prevens shoohrough (boh MOSFETs on a he same ime), secondly, i is he ime inerval used o charge/discharge he MOSFETs drain-o-source capaciance used for zero volage swiching (as seen earlier in he presenaion). Because of he high swiching frequencies MOSFETs are preferred over IGBT s. The resonan capacior blocks he DC componen of he square wave, producing a signal ha is cenered around 0v. The resonan ank will filer he higher harmonics essenially only allowing sinusoidal curren o flow. 51
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 52 Nex les look a he recifier block found on he secondary side. 52
Types of Recifiers Three opologies o consider: Half-wave recifier Full-wave recifier (cener-apped) Bridge recifier High oupu volage low oupu curren Half-wave Full-wave Bridge-Recifier 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 53 There are hree differen recifier opologies o consider: Half-wave, Full-wave, and Bridge Recifier. As his applicaion has a low oupu volage (12V) and high oupu curren he bridge recifier is no a suiable soluion. For his reference design we have used a Full-Wave recifier bu we have replaced he Diodes wih MOSFETs. This is more commonly known as synchronous recificaion. The MOSFETs swiching losses and conducion losses are less hen ha of he Diodes losses, which helps improve overall efficiency. The MOSFETs have been placed on he low-side (ground reference) o reduce componen coun and complexiy. One hing o noe is ha now ha we have added MOSFETs o he recifier special care mus be aken o mainain Zero-Curren Swiching. 53
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 54 Les now look a he auxiliary flyback circui. 54
Auxiliary Power Block Diagram DC Inpu 350V 420V Snubber Flyback Conroller Flyback TX Isolaion Barrier Oupu Filers 12V oupu from Aux Supply 12V oupu from Converer Buck Swicher dspic 3.3V oupu High Volage Low Volage Legend Feedback Opo-Coupler Solid Sae Relay Re-sar Auxiliary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 55 Here is a high-level block diagram of he auxiliary power secion. In his design we were argeing high efficiency and very low power a no/ligh load operaing condiions. To do his he auxiliary circui has been designed wih an auo shu-off feaure providing low sand-by power. The circui also provides he abiliy o resar he auxiliary circui in he even of a faul condiion. Upon sysem sar-up, he flyback converer provides power o he dspic. When he dspic is up and running he oupu from he LLC converer (12V) will provide he necessary power for he dspic, essenially powering iself. 55
Session Agenda Background Informaion Resonan Converer Topologies LLC Resonan Converer Operaing Modes 200W LLC Resonan Converer Reference Design Overview Half-Bridge Converer / Resonan ank Synchronous Recifier Flyback Auxiliary Power Summary 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 56 Nex, le us recap wha we discussed on resonan converers. 56
Summary Resonan Converer Background Informaion Differen Resonan Converer Topologies LLC Resonan Converer Operaion Modes Microchip s 200W LLC Resonan Converer 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 57 In his webinar, we discussed he differen resonan converer opologies, operaional waveforms of a LLC resonan converer, and Microchip s 200W LLC Resonan Converer Reference Design. From our discussions we saw ha he LLC resonan converer is a suiable DC-DC converer for high-power applicaions wih i s high efficiency, high power densiy, and is abiliy o operae over a wide inpu volage range. 57
Thank You Visi www.microchip.com/smps for more design resources Available for Free Download: Applicaion Noe Complee Source code PCB Design files MATLAB Simulaion files 2010 Microchip Technology Incorporaed. All Righs Reserved. LLC Resonan Converer Webinar Slide 58 Thank you for joining me in his webinar on he LLC Resonan Converer Reference Design using he dspic Digial Signal Conroller. Please visi he link on his page for more design deails on he LLC Resonan Converer as well as oher Swich-Mode Power Supply Reference Designs. 58