LLC的原理与应用PPT课件

LLC的原理与应用,Index,LLC简介工作模式分析LLC的特点3KLLCDemoBoard介绍设计步骤与Push-pull的对比损耗分析效率优化,LLC简介-1,LLC：三元件谐振半桥/全桥线路图变频工作，电压反馈50Duty驱动副边不需电感,LLC简介-2,SRC电路与增益曲线SRC电路的直流增益总是小于1轻载调整率，高的谐振能量，以及高输入电压时的较大关断电流,LLC简介-3,AdvantagesofaddingLmCurrentLagZVSBoostWiderangeBestuseofresonantpointHighEfficiencyDrawbacksIncreasingresonanttankcirclecurrentAdditionalmagneticcomponent,buteasytorealize(integration),LLC简介-4,工作在谐振频率时等效电路分析副边电阻折算到原边Lm被输出电压箝位电流滞后于电压电容直流偏压Vin-nVo=Vin/2FHAapproach(firstharmonicapproximation),LLC简介-5,一些公式存在2个谐振频率Fr1和Fr2其余归一化参数,LLC简介-6,增益特性在谐振点Fr1，在所有负载条件下增益是固定的峰值增益在Fr2和Fr1之间存在ZCS区和ZVS区需要限制最低频率空载时，增益无法降得更低用跳周期解决,Buck区,Boost区,谐振区,LLC简介-7,MOSFETZVS的实现在死区时间内需要有足够的电流抽取MOSFET结电容上的能量；死区时间结束时，电流不能过零；即使在无负载的情况下也能零电压开关；的含义谐振电感与励磁电感的比值：Lr/Lm越大，调节能力越强，增益曲线越陡峭越大，增益范围越大,LLC简介-8,不同时增益曲线的变化（图中k1/）,LLC简介-9,DiodeZCS的实现能量传递过程SpikePhaseendswhenQ1isswitchedon,Cout,6/6,Vg,Vc,I(lp)I(ls),Imos,Id,Waveformsatresonance(fsw=fr1),Gate-drivesignals,Transformercurrents,Dead-time,Diodevoltages,Diodecurrents,Magnetizingcurrentistriangular,Outputcurrent,Tankcircuitcurrentissinusoidal,CCMoperation,HBmid-pointVoltageResonantcapvoltage,Vg,OperatingSequenceaboveresonance(Phase1/6),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,1/6,Vin,Vout,Q1,Q2,Ls,Lp,Cr,n:1:1,D1,D2,Coss1,Coss2,Q1isOFF,Q2isOND1isOFF,D2isONLpisdynamicallyshortedCrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenQ2isswitchedoff,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequenceaboveresonance(Phase2/6),Q1andQ2areOFF(dead-time)D1andD2areOFFtransformerssecondaryisopenV(D2)reversesasI(D2)goestozeroPhaseendswhenQ1isswitchedon,Cout,Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,2/6,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequenceaboveresonance(Phase3/6),Q1isON,Q2isOFFD1isON,D2isOFFLpisdynamicallyshortedCrresonateswithLs,fr1appearsPhaseendswhenI(Ls)=0,Cout,Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,3/6,Vg,Vc,I(lp)I(ls),Imos,Id,Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,OperatingSequenceaboveresonance(Phase4/6),4/6,Q1isON,Q2isOFFD1isON,D2isOFFLpisdynamicallyshortedCrresonateswithLs,fr1appearsEnergyistakenfromVinandgoestoVoutPhaseendswhenQ1isswitchedoff,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,OperatingSequenceaboveresonance(Phase5/6),5/6,Q1andQ2areOFF(dead-time)D1andD2areOFFtransformerssecondaryisopenPhaseendswhenQ2isswitchedon,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,OperatingSequenceaboveresonance(Phase6/6),6/6,Q1isOFF,Q2isOND1isOFF,D2isONLpisdynamicallyshorted.CrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenI(Ls)=0,Phase1starts,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,Waveformsaboveresonance(fswfr1),Gate-drivesignals,Transformercurrents,Dead-time,Diodevoltages,Diodecurrents,Magnetizingcurrentistriangular,Outputcurrent,Tankcircuitcurrent,CCMoperation,HBmid-pointVoltageResonantcapvoltage,Sinusoidf=fr1,Linearportion,Vg,OperatingSequencebelowresonance(Phase1/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,1/8,Vin,Vout,Q1,Q2,Ls,Lp,Cr,n:1:1,D1,D2,Coss1,Coss2,Q1isOFF,Q2isOND1isOFF,D2isON;LpisdynamicallyshortedCrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenI(D2)=0,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase2/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,2/8,Q2isON,Q1isOFFD1andD2areOFFtransformerssecondaryisopenCrresonateswithLs+Lp,fr2appearsOutputenergycomesfromCoutPhaseendswhenQ2isswitchedoff,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase3/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,3/8,Q1andQ2areOFFD1andD2areOFFtransformerssecondaryisopenPhaseendswhenQ1isswitchedon,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase4/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,4/8,Q1isON,Q2isOFFD1isON,D2isOFFLpisdynamicallyshortedCrresonateswithLs,fr1appearsEnergyisrecirculatingintoVinPhaseendswhenI(Ls)=0,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase5/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,5/8,Q1isON,Q2isOFFD1isON,D2isOFFLpisdynamicallyshortedCrresonateswithLs,fr1appearsEnergyistakenfromVinandgoestoVoutPhaseendswhenI(D1)=0,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase6/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,6/8,Q1isON,Q2isOFFD1andD2areOFFtransformerssecondaryisopenCrresonateswithLs+Lp,fr2appearsOutputenergycomesfromCoutPhaseendswhenQ1isswitchedoff,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase7/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,7/8,Q1andQ2areOFFD1andD2areOFFtransformerssecondaryisopenPhaseendswhenQ2isswitchedon,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,OperatingSequencebelowresonance(Phase8/8),Q1ONQ2OFF,Q1OFFQ2ON,Q1OFFQ2ON,8/8,Q1isOFF,Q2isOND1isOFF,D2isONLpisdynamicallyshortedCrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenI(Ls)=0,Phase1starts,Cout,Vg,Vc,I(lp)I(ls),Imos,Id,Gate-drivesignals,HBmid-pointVoltageResonantcapvoltage,Transformercurrents,Dead-time,Diodevoltages,Diodecurrents,Magnetizingcurrent,Outputcurrent,Tankcircuitcurrent,Waveformsbelowresonance(fswfr1),Sinusoidf=fr2,DCMoperation,Sinusoidf=fr2,LLC工作模式总结,三个工作区都能实现MOSFETZVS，DiodeZCSBOOST区需要限制最低频率部分时间没有向副边传递能量，利用率低，因而效率稍差谐振区效率最高，工作特性最好Buck区MOSFET关断损耗增加Diode反向恢复稍大空载需要跳周,FeaturesOfLLC,ZVSforprimaryswitchesinfullloadrange，ZCSforsecondaryrectifiersNoneedofoutputchokeinductorMagneticintegrationhelpsreductionofthevolumeLowvoltagestressofsecondarydiodeLessreverserecoveryHighefficiencyLowEMI,LLC的主要应用,最佳应用：输入高压400V左右，输出50V左右前级接PFC时，电压较为稳定，多数时间在谐振区附近工作MOSFET的Rds适当，驱动难度不大电感、变压器便于设计Diode可用Schottky谐振电容适当磁集成：600W以内磁芯和Bobbin难选，但绕制工艺简单漏感和励磁电感比例不能精确控制，但影响不大,LLC的主要应用,高端应用工频纹波大是一个很突出的问题由于电压环控制的原因，工频纹波很难抑制，工频补偿可以较为有效的解决这一问题副边同步整流也是一个难点准确确定同步MOSFET的开通、关断时间非常困难；目前较为传统的方法是采样SRMOSFETsDS电压控制开关(1168)；另可以采样副边电流控制(Hindenburg2)；原副边同驱(Houston)。工作频率高时增益反转现象由寄生参数引起,加强工艺,高频限制；,LLC在低压大电流时的应用,在低压大电流输入、高压输出时：不能磁集成最好采用原边全桥注意死区时间对ZVS的影响输出Diode的反向恢复是一个问题效率有优势EMI性能好,LLC应用问题,磁集成磁集成的方法LLC需要一个相对大的Lr，一般采用一种可组合线轴线圈数和绕线结构是决定Lr大小的主要因素变压器芯的气隙长度不会影响Lr太多通过调整气隙长度却可以轻松控制Lm分立磁性元件磁性元件体积大仍旧可以采用TX励磁电感作为Lm容易控制感量与工艺适合大功率应用,3KLLCDemoBoard,Circuitdiagram,3KLLCDemoBoard,Photoofthedemoboard（SecondEdition）Thelatesteditionisplannedcarefully,方案简介,采用L6599模拟控制原边全桥LLC，副边中心抽头全桥整流隔离驱动MOSFET：IPP075N15N3Diode：APT15DQ100KCr采用高压薄膜电容分离Lr与TX（Lm）,性能描述,按照输入电压80-110V设计，输出功率2700W；PeakEfficiency：97.4DCload；FullLoadEfficiency：97.0DCload；,全桥LLC与半桥LLC的区别,变压器匝比比半桥增大一倍；Lr、Lm是半桥的4倍，Cr是半桥的1/4保证Q值不变；需要隔离驱动；变压器匝数增多，线径变小；MOSFET数量由2个变为4个在低压大电流时，半桥LLC也需要用4个；都用4个MOSFET时，二者损耗相当；全桥LLC整体电流应力小；,设计步骤-1,注意：原边为全桥LLC，副边两路折算成一路1.列出设计参数与规格要求Vin（最小、最大、常压）、Vout、Pout、Fs（常压时的工作频率）根据常压与输出电压，结合所选拓扑求变压器匝比NNVin/Vout(全桥)（副边单路为Center-Tap形式）初选Lr与Lm的比值，在0.2-0.35之间较好求出Re：2.确定最低输入电压时需要的增益MmaxMmaxN*Vout/Vin-min（与半桥LLC不同）,3.确定Q值从增益曲线中找到与