Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 1] Inroducion o Sof Swiching Why sof swiching Types of sof swiching Examples Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 2] Why Sof Swiching? conrol V GS V S I S J p Hard swiching lossed 1
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 3] Why Sof Swiching? V in L V x V o Ir C R Diode reverse recovery problem in all opologies Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 4] Magneics size Ideal Pracical Hager swiching frequency reduce size of oher componens 2
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 5] Swiching Losses Concepual Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 6] Sof Swiching Terminology 3
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 7] Sof Swiching Mehods Passive Lossless Snubbers Quasi resonan swiching Auxiliary swich, lossless snubber Self sof swiching opologies (muli ransisor) Operaion a DCM or DCM-CCM bordeline Resonan converers Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 8] Passive Lossless Snubber No addiional swiches 4
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 9] Conrolling di/d Turn on snubber Series inducor Need o recover energy Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 10] Conrolling dv/d Turn off snubber Parallel capacior Need o recover energy 5
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 11] Recovery by Resonan Circui Resonan process is Lossless Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 12] Example 1 urn off snubber 6
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 13] Example 1 dv/d is conrolled Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 14] Example 1 Energy is reurned o supply 7
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 15] Snubber Seminar on WEB hp://www.ee.bgu.ac.il/~pel/public.hm#4 S. Ben-Yaakov and G. Ivensky, Passive lossless snubbers for high frequency PWM converers. IEEE Applied Power Elecronics conference, APEC-99, Dallas, 1999. Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 16] Old Snubber 8
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 17] Quasi-Resonan (Resoan Transiion) Applies resonan phenomena during ransiions Normally no special energy-reurn pahs May use exra passive componens or jus original circui Variable swiching frequency operaion Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 18] Quasi-Resonan 9
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 19] Quasi-Resonan L r, C r, form a resonan circui Resonan ime is fixed ; variable swiching frequency High conducion losses Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 20] Flyback in DCM Turn on may be under high volage CV 2 / 2 losses Lower losses if urn on a valley 10
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 21] Quasi-Resonan Flyback in DCM Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 22] Quasi-Resonan Flyback in DCM Resonan a primary side Resonan a primary side Variable swiching frequency Lower EMI (?) 11
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 23] Auxiliary Swich Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 24] Auxiliary Swich 12
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 25] Auxiliary Swich Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 26] Self Sof-Swiching (Muli Swich) Q 1 C 1 V C L 2 Q2 delay C 2 V C 2 I L Curren polariy reversal is a mus C 1, C 2 of ransisor plus exernal (if any) V DS1 V DS2 13
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 27] Asymmerical Half Bridge DC-DC Converer Curren polariy reversal is a mus Wha is he purpose of Cc? Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 28] Dead ime requiremen Q 1 Q 2 I L delay V DS1 V DS2 14
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 29] Phase Shifed PWM Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 30] Phase Shifed PWM 15
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 31] Phase Shifed PWM Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 32] Phase Shifed PWM Two diodes are conducing during Toff 16
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 33] CCM-BCM operaion Sof swiching requires curren polaroy reversal Synchronous Buck in CCM: Upper ransidor hard swiched Operaion jus below CCM-DCM border will faciliae ZVS Higher conducion losses Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 34] Resonan Converers Sinusoidal Curren due o resonance Sof swiching achievable 17
Prof. S. Ben-Yaakov, Fundamenals of PWM Converer [NL_11 35] Resonan Converers Sinusoidal Curren due o resonance Sof swiching achievable 18