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1、OCP Global Summit October 18,2023|San Jose,CABosheng Sun&Sheng-Yang Yu Texas InstrumentsA M-CRPS compatible totem-pole bridgeless PFC with re-rush current control and extreme low iTHDKey M-CRPS RequirementsHigh efficiency,high power density,limited re-rush current,and low iTHDTopology selection to a
2、chieve high efficiencyBulk capacitor size reduction for high power densityRe-rush current managementSteps to achieve low iTHDReferenceAgendaM-CRPS:Modular Hardware System Common Redundant Power SupplyRequire high efficiency.Require high power density.Key M-CRPS Requirements3 form factor(LxWxH):185 x
3、 73.5 x 40mm185 x 60 x 40mm265 x 73.5 x 40mm 80W/in3 100W/in3Loading100%50%20%10%Titanium (2.5kW)94%96%94%90%Titanium (2.5kW)92%96%94%90%M-CRPS Efficiency requirementsM-CRPS:Modular Hardware System Common Redundant Power SupplySpecify re-rush current limit after AC-drop out event.Specify iTHD at dif
4、ferent loads especially 5%-10%load.Key M-CRPS Requirements cont.Efficiency Improvements PFCSiGaNGaNActive“bridge rectifier”in classic boost PFCImplementable with Si MOSCCM Totem pole“bridgeless”PFCCannot be realized with Si MOS,WBG devices needed for fast FETsefficiencyimprovementHigher efficiency i
5、mprovementHighest efficiency improvementClassic boost PFC with diode bridge rectifier AC-switch PFC(or H-PFC)Implementable with Si MOS98%98.3%98.5%99%Isolated DC/DC stageVoutAC input400VDCAux flyback power stage and controllerDC/DC controllerPFC controllerPFC power stageEMI filterIntroduce baby boos
6、t(BB)converterPower Density Improvements Bulk CapVACVBULKVBBSingle PhaseTotem Pole Bridgeless PFCBaby BoostRelay FETLoadVOUTQ2Q1Q3Q4BBFETCBULKCBBIsolated DC-DC ConverterBypass FETRT=2 ,2 ,2=2 3 kW 10(390)2 (320)2=1.207=2 ,2 ,2=2 3 kW 10(390)2 (240)2=635 50%reduction!Without BB:With BB:AC Dropout wit
7、h Baby BoostVBBIINBaby boost bypassing FET Driving signalInrush Current and Re-rush CurrentInrush current:when AC is applied(before PFC startup)Re-rush current:During PFC normal operation,AC drop then comes backRTOver 80A re-rush current!Re-rush Current Control with Relay FETt0t1t2 t3VacVBULKRectifi
8、ed VacRectified IacQ1,Q2 PWMQ3 ON/OFFONOFFON10ms000I_thresholdVACVBULKVBBSingle PhaseTotem Pole Bridgeless PFCBaby BoostRelay FETLoadVOUTQ2Q1Q3Q4BBFETCBULKCBBIsolated DC-DC ConverterBypass FETRTUse solid state relay for fast on/off controlMomentary turn off relay when re-rush current hit limitManipu
9、late PFC voltage and current loop such that the inductor current is well controlledRe-rush Current Test ResultsZoom int0t1t2 t3VacVBULKRectified VacRectified IacQ1,Q2 PWMQ3 ON/OFFONOFFON10ms000I_thresholdiTHD Improvement Step 1+GvVrefVoutGiVrms2PWM generatorPWMdABCVin+-+-IinIrefStep 1:Make sure the
10、sensed signals are clean:add a local capacitor close to the ADC pinif not enough,add a digital IIR filter to further reduce noiseiTHD Improvement Step 21 switch cycle8 samples/switching cycleOp-amp outputStep 2:over-sampling on current feedback signal:Single sample does not equal average currentOver
11、-sampling provides a more accurate feedback signal+GvVrefVoutGiVrms2PWM generatorPWMdABCVin+-+-IinIrefiTHD Improvement Step 3Output VoltageInput VoltageOutput Voltage(V)380390400410 1e-1Time(s)9.009.059.109.159.209.259.30Input Voltage(V)-2000200Vout_zc(t)Vout(t)Step 3:reduce double line frequency ri
12、pple:Use Vout at zero-crossing for feedbackUse instantaneous Vout and non-linear voltage loop to handle load transient+GvVrefVoutGiVrms2PWM generatorPWMdABCVin+-+-IinIrefiTHD Improvement Step 4Q3Q4ACQ1Q2Step 4:reduce current spikes at AC zero-crossing:Inherent issue to totem-pole PFCPWM soft start a
13、fter zero-crossingVACQ4 soft startQ3 soft startVGS_Q4VGS_Q3VGS_Q2All switches are off VGS_Q1All switches are off Q4 soft startQ3 soft startiTHD Improvement Step 5*Step 5:AC cycle skipping:THD is lower at heavy load than light loadReduce THDImprove efficiency1.https:/www.opencompute.org/documents/m-c
14、rps-r1-v1p0-rc4-pdf2.L.Huber,Y.Jang and M.Jovanovic,“Performance Evaluation of Bridgeless PFC Boost Rectifiers”,IEEE Transaction on Power Electronics,Vol.23,No.3,May 20083.B.Sun,“How to reduce current spikes at AC zero-crossing for totem-pole PFC,”Texas Instruments Analog Applications Journal,4Q 201
15、54.S.Yu,B.Genereaux,L.Yin,“Improve power density with a baby boost converter in a PFC circuit”,Texas Instruments Analog Design Journal,May 2022.5.B.Sun.“AC cycle skipping improve PFC light-load efficiency”,https:/ single-phase totem-pole bridgeless PFC reference design with 16-A max input,Texas Instruments,Oct.2022.Online.Available:https:/ Global Summit|October 18,2023|San Jose,CA