Innovative Design of the Fast Switching Power Supplies for the SOLEIL EMPHU Insertion and its Fast Correctors

Transcription

1 Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F. BOUVET On Behalf of the SOLEIL Power Supply Team Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

2 Content Context of the project Power supply requrements Man power supply desgn Topology Power conerter sng Dgtal control loops Dynamc performances Influence of the real load behaor Corrector power supples Desgn Power supply drng ID Feedforward compensaton Questons Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

3 Context A new electromagnetc/permanent helcal undulator, wth a 65 mm magnetc perod, s under deelopment at SOLEIL Ths nserton dece should prode a fast swtchng < ms of the photon polaraton to perform dchroïsm experments Desgn of the undulator * : Copper sheets : Cols B Slcon-steel poles NdFeB permanent magnets Bx Bx = B =,24 T * F. Marteau, Deelopment of an Electromagnetc/Permanent Helcal Undulator for Fast Polarsaton Swtchng, PAC 9 Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

4 Desgned undulator Prototype SEF The prototype s fxed on 2 grders attached to a motored carrage Vertcal moement to change peak feld alues Col coolng: Use of thermal dran sheets cooled by tubng braed to ther outsde edges thermal dran sheet for eery 2 current carrer sheets Eery conductor has one surface n contact wth a coolng plate through nsulaton Current carrer sheets Thermal dran sheet Vew of elementary serpentne col Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

5 Power supply requrements Man power supply: Feedng the cols producng the ertcal feld: R = 3 mω ; L = 4 mh to 8 mh dependng on the delered current 4-quadrant operaton Maxmum current +/-35 A Polarty swtchng tme < 5 ms Current precson: ppm of the nomnal current Current reference: Trapeoïdal shape wth rounded corners. Repetton rate wll extend between DC and 5 H 8 Corrector power supples: Feedng the correcton cols used to compensate any beam closed orbt dstorton consecute to man feld transtons Rated between A / W and 2 A / 2 W Should prode at least as fast response as the man PS and should be synchronsed wth t < ms Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

6 Man power supply desgn Structure of the conerter: Inerter assembly 2-pulse rectfyng unt + flter and energy storage + 2 nterleaed PWM nerters + flter AC mans AC-DC stage Intermedate DC stage 4Q DC-DC stage Load 5 H stepdown transformer 2-pulse dode rectfer Flter and energy storage HF flterng + decouplng 2 nterleaed PWM nerters + flter Rather smple structure: Faours relablty and eases up mantenance Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

7 Man power supply desgn Ths topology choce s lnked to the followng consderatons: AC-DC stage: Requrements: Galanc solaton between mans and output load + adjustment of the DC lnk otage leel Chosen soluton: 5 H transformer + 2-pulse rectfer Well-known and relable soluton DC lnk oltage predomnatng harmonc theortcally at 6 H easy to flter No addtonnal power swtches hae to be controlled other than the ones used n the 4Q DC-DC stage: The whole conerter can be controlled usng a sngle SLS dgtal control unt Increased relablty + reduced costs Intermedate DC stage: Formed by a slghtly damped LC flter Used to attenuate the harmoncs produced by the 2-pulse rectfcaton and to mtgate the mpact of AC mans perturbatons When the load acts as a generator, the energy s transferred to the capactor bank energy storage Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

8 Man power supply desgn 4Q DC-DC stage: The nerter secton conssts of 2 nterleaed PWM H-brdges Chosen nterleaed PWM control strategy: 8 phase shft between leg and leg 2 and between leg 3 and leg phase shft between legs, 2 and legs 3, 4. Vdc+ Leg Leg 2 Leg 3 Leg 4 CHF Out 2 Out Out 3 Out 4 Vdc- α =,9 α =,5 Vge IGBT top legs, 2, 3, 4 Effecte frequency at the output and also n the DClnk HF flterng capactors = 4 tmes the IGBT swtchng frequency Enables to conclate the need of hgh bandwdth and good flterng of the output current I Out Yellow ; I Out 35 A Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

9 Power conerter sng Determnaton of the transformer rato Lnked to: Power aalablty needed durng transents Generaton of the requred current waeform wth 2 ka/s d/dt Uout max / Uout statc 3 AC mans oltage aratons < +/-% Maxmum duty cycle of PWM sgnals:,95 Wth PWM perod = 6 µs and IGBT leg dead tme = µs, the mnmum duraton of the PWM pulses s µs aods pulse suppresson by IGBT drer Nonlneartes Voltage drops accross the components Ex: Transformer wndngs Ipeak ~ 92%. no load Hgher DC lnk oltage yelds: Increase of IGBT swtchng losses Increase of output current dstorton IGBT dead tme effect Transformer rato = 6 Vch 2 α- Vdc Load current Output oltage DC lnk oltage Transformer secondary currents 5 H Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

10 Power conerter sng LC flter at the rectfer output: Resonant frequency: 25 H Attenuaton of the 6 H harmonc: 3 db Magntude db Bode Dagram System: LC_flter Frequency H: 6 Magntude db: -3.5 IGBT swtchng frequency: Trade-off between effcency, dynamc response and relablty 7 kh Phase deg Frequency H IGBT modules: FF4R6KE3 from EUPEC Measured effcency of the whole conerter at nomnal power: 85% η nerter: 9% Power cyclng capablty of the IGBT modules Estmaton usng the power cyclng cures proded by INFINEON for the 6V IGBT3 standard modules: 7. cycles at 5 H operaton 9 cyles at less than H operaton Tj C Tme s H 5H Ant-// H Ant-// 5H Power swtch juncton temperature Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

11 Power conerter sng Output flter: - 3 db cut-off frequency: 5 H Peak gan: 2 db Attenuaton of 65 db at 68 kh 4 tmes the PWM frequency Influence on load current rpple of pulse repetton modulaton PRM harmoncs * : To oercome the resoluton lmts of classc dgtal PWM, a specal pulse repetton modulaton has been mplemented by the Paul Scherrer Insttute for the SLS controllers Generaton of low frequency harmoncs In our applcaton, the PRM spectrum can contan subharmoncs of the PWM carrer-frequency down to 45 H /37 of the PWM frequency Output current dstorton due to PRM harmoncs < ppm of nomnal Magntude db Phase deg x x -3 2 Bode Dagram Frequency H System: Output_Flter Frequency H: 6.8e+4 Magntude db: Load current rpple A x -3 Duty cycle araton due to PRM Tme s x -3 Output current dstorton due to 45 H harmonc * F. Jenn, M. Emmenegger, A Fully Dgtal PWM for Hghest Precson Power Supples, EPE 2 Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

12 Power conerter sng Current transducer: DCCT Ultrastab DANFYSIK: Lnearty error < ppm Rato error: Intal < 2 ppm / s. Temperature <,3 ppm/ C Offset error: Intal < 2 ppm / s. Temperature <,2 ppm/ C Output nose DC kh <,5ppm Current A Control electroncs: Use of SLS dgtal control cards * Tme h Current stablty Already n use at SOLEIL on the 3 H Booster power supples Well-proen and hgh performng electroncs Tranng on the DSP and FPGA software dspensed by DIAMOND The whole conerter can be controlled wth a sngle control unt * L. Tanner, F. Jenn, Dgtal Control for Hghest Precson Accelerator Power Supples, PAC Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

13 Dgtal control loops Tmng of PSI dgtal control cards: PWM Frequency = 7 kh 6 µs PWM Sync Start of Con. Precse ADCs A/D conerson precse ADCs Data Samplng Start of Con. Unprecse ADCs A/D conerson unprecse ADCs Data Samplng Precse Data transfer 2,5 µs Samplng perod: Te = 3 µs Unprecse Data transfer Begn data block Data arred IT regulaton Regulaton task Load Current = Mean of Precse Data measurement delay = 22,5 µs Output oltage Unprecse Data measurement delay = 2 µs Computaton tme delay ~ Te = 3 µs Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

14 Dgtal control loops Control scheme Based on 2 nested loops: Fast nner oltage loop: PID controller + Feedforward Hgh precson outer current loop: PI controller mplemented under a R.S.T form FEEDFORWARD I_ref MAX/MIN_ I_REF d/dt Lmtaton + rounded corners -K- K_FILT DI / DT LIMITATION MAX/MIN_ DI_REF_DT +/- 2 ka/s Te - - Integrator t_ T Outer Current Loop OUTER CURRENT LOOP Add MAX/MIN_VOUT 4 Vdc meas 2 Vout_ref Zero-Order Hold2 r_.+r_. -+r2_-2 +s_ - R / S ADC_Delay2 + - a_f.+a_f - Dscrete Flter INNER VOLTAGE LOOP Add Dde MAX/MIN_MOD MAX/MIN_MOD - DSP_Delay Modulaton Index Modulaton Index 2 I LOAD meas Zero-Order Hold ADC_Delay r_.+r_ - R 3 Vout meas / S Zero-Order Hold ADC_Delay / S2 Inner Voltage Loop Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

15 Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC Voltage loop desgn * : The power conerter can be modelled by a second order system: Control delay: Closed-loop transfer functon: Dgtal control loops Magntude db Phase deg Bode Dagram Frequency H System Model = = a a b b A B m out + + = D + = R B D S A R B D CL S R where s the controller transfer functon Duty cycle computaton delay ADC delay Zero order hold delay PID controller * E. Godoy, E. Orstertag, A Complete Methodology for the Desgn of a Dgtal Control Law for PWM Inerters, EPE 23

16 Dgtal control loops To lmt the order of the controller, only the duty cycle computaton tme delay wll be compensated. The parameters of the controller are dered from a pole placement such that the oltage closedloop behaes lke a second order system whth a cut-off frequency Fcl = 2,5 kh greater than the output flter resonant frequency and a dampng rato ξ =,7: A 2 S + B R = + d + d 2 Order of the controller: 2 S R An ntegrator s needed n the controller ero steadystate error = S = + s = r + r + r2 Computaton tme Magntude db ξ 2 π Fcl Te d = 2 cos e 2 π Fcl Te ξ ξ 4 π Fcl Te d2 = e OL CL 2 Bode Dagram System: OL Gan Margn db: 5.22 At frequency H: 5.4e+3 Closed Loop Stable? Yes Phase Margn: 5 Gan Margn: 5 db Frequency H Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors Phase deg 9-9 System: OL Phase Margn deg: 53.4 Delay Margn sec: 6.e-5 At frequency H: 2.43e+3 Closed Loop Stable? Yes Open and closed-loop Bode plots wth power conerter real transfer functon F Bouet IPAC

17 Dgtal control loops Feedforward control: Improement of dynamc and statc behaor + VdcFIL = Vdc MEAS a + a Vout m k = Vdc REF FIL k k 6 H rpple 4 < 5 ppm of nomnal Current loop desgn: F F Hgh frequency flter Cut-off frequency: 6 kh Computed consderng that the oltage loop s untary because of rato between bandwdths of nner and outer loops Current A 35 Wthout FFWD Wth FFWD Tme s System model wth oltage loop: I Vout Load REF = B A Ζ Z Load b + b = + a B Closed-loop: T CL R, S, T polynomals IP controller A S + B R Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

18 Dgtal control loops Closed-loop pole placement method: Sole A S + B R = + d + d2 2 Chosen cut-off frequency Fcl = 7 H Fcl / Fcl = 3,5 Dampng rato ξ = ξ 2 π Fcl Te d = 2 cos e 2 π Fcl Te ξ ξ 4 π Fcl Te d 2 = e Order of the controller: S R = r Polynomal T : = + r Chosen to assure unty gan to the closed-loop Desgned so as to not ntroduce an undesrable ero n the closed-loop transfer functon smple gan, drectly gen by the coeffcents of R - : 2 T = r + r Bode Dagram Frequency H Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors Magntude db Phase deg System: OL Gan Margn db: 3.3 At frequency H: 2.34e+3 Closed Loop Stable? Yes System: OL Phase Margn deg: 38 Delay Margn sec:.46 At frequency H: 724 Closed Loop Stable? Yes Open and closed-loop Bode plot wth oltage closed-loop transfer functon and control delays Trackng error n the F B =.35 / Tr 9% rse tme, Phase shft ~ 2,5,5 L = L mn = 4 mh: Phase Margn: 4 Gan Margn: 3 db OL CL_PI CL_RST F Bouet IPAC

19 Dynamc performances Smulaton and expermental results: Current A Current reference Load current Tme s Control error x Error A Smulaton of a current transton from -35 A to +35 A Current settlng tme ~ 5 ms Oershoot almost equal to ero Trackng error n the ramps ~ 3% Ok n our applcaton ms synchronsaton requrement between man and corrector power supples, but could be mproed by desgnng approprate eros n the closed-loop transfer functon. Ex: Predcte algorthm estmatng I REF k+h by usng lnear extrapolaton: T = r + r + h h 5 H on a mω - 3 mh test load Blue cure: Load current 5A/d Green cure: Output oltage 5V/d Red sgnal: Hgh f control error below ppm of nomnal Tme scale Zoom wndow: 2ms/d Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

20 Influence of the real load behaor Power tests wth the undulator The control loop parameters had to be optmed to achee stable operaton Oershoot 35 A araton Yellow cure: Load current Blue cure: Output oltage Green sgnal: Hgh f control error below ppm of nomnal Equalent crcut of the real load: Vstep load R L Rs Voltage step Yellow cure: Load current Blue cure: Output oltage Rs = Vstep / load - R = 4 mω Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

21 Influence of the real load behaor Explanaton: Results from the structure of the cols. Each of them = 25 layers of copper stacked together around the poles, among 9 are coolng plates Current carrer sheets In between: Thermal dran sheet and kapton to guarantee the nsulaton Vew of elementary col Equalent model of the undulator = Transformer whch secondares are short-crcuted. Seen from the prmary, the model classcaly becomes: R L Rs ρ l 6 Rs = 9 = 4mΩ S 9 2 Rs: secondary wndng resstance reflected to the prmary sde Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

22 Influence of the real load behaor The power supply dynamc performances can be mproed by addng a feedforward term to the current controller output : Current A Tme s Current reference Control error wthout Feedforward Control error wth Feedforward enabled Howeer, a serous ssue les n the magnetc feld settlng tme About 3 ms ,2 Error A Z REF EST k k = Z k EST REF R + Rs + R Rs Te L = + Rs Te L REF REF REF where Z EST s the estmaton of the load mpedance R + Rs Current A, Voltage V output current Lp wth reel load oltage wth RL load oltage wth reel load Tme s Current flowng through the load prmary nductance ~ mage of the magnetc feld Output waeforms n AC mode of operaton To oercome ths problem, the thermal dran sheets TDS are currently under modfcaton to ncrease the resstance alue of the load secondary crcut: Inserton of gaps n the TDS Wth the gaps, the total magnetc feld whch crosses each TDS wndow then surroundng 2 adjacent poles nstead of only s ero. Wth a resstance ncrease by a factor of at least, the ms target for the magnetc feld settlng tme can be reached. Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

23 Corrector power supply desgn A set of 8 bpolar power supples s needed to feed the correcton cols splt between the entrance and the ext of the undulator. These correctors are necessary to keep the feld ntegral as low as possble durng the man feld transtons and to mantan the beam trajectory on the reference orbt. Power supples rated between A / W and 2 A / 2 W Structure: Based on the use of ether sngle ou paralleled power operatonal amplfers PA2A from APEX Correctors Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

24 Corrector power supply desgn Current settlng tme: ~ 5 ms load tme constant ~ 3 ms A 5. Current A Voltage V I out I out Vs V supply maître V V out maître Master V V out esclae Slae Tme mn. ± A / ± V power supply ±2 A / ± V power supply In order to dre the corrector PS synchronously wth the man PS, a specal dece has been deelopped. It conssts of: - a 8 MH µc on whch the correcton tables are shpped - fast ADCs whch a kh rate the analog setpont sgnals drng each of the 9 power supples Temperature C A Tme mn T PA2 Maître MasterC T PA2 Esclae Slae C T ambante ambent C The ms synchronsaton requrement between the power supples s met Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

25 ID Feedforward compensaton Ideal waeforms durng changes of the man magnetc feld: 2 A Man PS setpont Man PS current M rst Corrector setpont rst Corrector current C M M 2 C M 2 C2 M 2 M 3 2 nd Corrector setpont 2 nd Corrector current C2 M 3 Tme Step by step feedforward tables: To each man PS current alue corresponds a set of corrector current alues Ideal compensaton: The 9 power supples begn rampng to the new setponts synchronously and reach these setponts at the same nstants Real waeforms: Man PS setpont Man PS current.5 ms ms rst Corrector setpont rst Corrector current <.5 ms M M 2 2 nd Corrector setpont 2 nd Corrector current C M C2 M ms C M 2 C2 M 2 Tme M 3 Tme C M 3 C2 M 3 Tme The current slope of the power supples s constant unlke the corrector current steps the 9 power supples do not reach ther present setponts at the same tme Suppresson of most of the transtory effects on the beam poston caused by ths mperfect FFWD compensaton SOLEIL Fast Orbt Feedback correcton system * * L-S. Nadolsk et al., Beam Poston Orbt Stablty Improement at SOLEIL, PAC 9 Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC

26 Questons Thank you for your attenton. Questons? Innoate Desgn of the Fast Swtchng Power Supples for the SOLEIL EMPHU Inserton and ts Fast Correctors F Bouet IPAC