ECEN5817 Lecture 44. On-campus students: Pick up final exam Due by 2pm on Wednesday, May 9 in the instructor s office

Transcription

1 ECEN5817 Lecture 44 On-campus students: Pick up final exam Due by 2pm on Wednesday, May 9 in the instructor s office Off-campus students: Pick up and submit the exam via D2L Exam is due in 5 days from the start time but no work will be accepted after 5pm MT on Wednesday, May 16 1

2 ECEN5817 Lecture 44 Dual-active-bridge converter* Q 1 Q 3 Q 5 Q 7 + v 2 v 4 1:n v 6 v 8 V g + V Q 2 Q 4 Q 6 Q 8 _ * R.W.A.A. De Doncker, D.M. Divan, M.H. Kheraluwala, "A Three-phase Soft-Switched High-Power-Density DC-DC Converter for High-Power Applications," IEEE Tran. on Industry Applications, Jan/Feb 1991, Vol. 27, No. 1, pp

3 DCX (V/nV g = 1) waveforms neglecting resonant transitions Q 1 v 2 i l Q 3 v 4 L l 1:n Q 5 v 6 Q 7 v 8 i o + Phase shift 0 < d < 1 dt s /2 V g v p v s Q 2 Q 4 Q 6 Q 8 V _ v p ni ( 1 d) I o 2V pk T g s 2 I pk d Ll 2 v s /n V g dt s I pk Ll 2 i l VgTs Io d( (1 d ) 2nL ni o I pk ni Note how phase o shift d controls the DCX power flow l T s /2 3 T s

4 Dual Active Bridge (DAB) DC-DC Converter Q 1 Q 3 Q 5 Q 7 i o C p C p C s C s L l 1:n t V i + + g l vp v s C out R out Q 2 Q 4 Q 6 Q 8 C p C p C s C s + V out 150-to-12 V, 100 W 1 MHz Efficiency: 97.5% i l Zero-voltage switching of all transistors v ds6 Relatively low peak and RMS v ds2 v ds4 current stresses Circuit design trade-offs driven by primary-side device C p, and secondary-side device R on [1] D. Costinett, H. Nguyen, R. Zane, D. Maksimovic, GaN-FET based dual active bridge DC-DC converter, IEEE APEC [2] D. Costinett, R. Zane, D. Maksimovic, "Automatic voltage and dead time control for efficiency optimization in a dual active bridge converter," IEEE APEC

5 Effects of primary-side device capacitance 1:n 0 t V + + g P v v out i l v p L l v s I l [A] i l time [ sec] RMS currents [A] to-12 V, 100 W I g,rms n t i out,rms L L l C p [pf] L l [μh] V p [V] v p C p = 70 pf C p = 40 pf C p = 20 pf time [ sec] Primary ZVS minimizes primary-side switching losses A larger device C p requires larger L l, and longer transition times, which results in larger peak and RMS currents, i.e. larger conduction loss on both primary and secondary sides

6 Device comparison for DAB application Si vs. GaN Transistors, 200V Si vs. GaN Transistors, 20-40V C oss R R on [pf Ω] C oss R R on [pf Ω] Q g R on [nc Ω] Q g R on [pc Ω] Data-sheet based comparison of Si and GaN (EPC 2011) devices Dt Datasheet tcc oss at 100V or 20V, and Q g at rated voltage V GS DAB circuit design trade-offs decided by primary-side C oss R on, and secondary-side device Q g R on 6

7 Device Loss Comparison: V DAB Secondary Gate Drive Loss Primary Gate Drive Loss Secondary Conduction Loss Primary Conduction Loss Power Loss [W W] 7

8 Efficiency optimization via control to-(10-12) V conversion 100 W i l v gs v gs2 v gs4 Effic ciency Manual Optimization Constant V out Automatic V Regulation out Output Power [W] 80W 20W V out /V g conversion ratio controlled to maximize efficiency over wider power range 8

9 Dual active bridge DC-DC converter summary At V/nV g = 1 (DCX), waveforms are close to ideal if F << 1 ZVS of all semiconductors for loads greater than a minimum ZVS can be extended to lighter loads by adjusting conversion ratio Phase shift can be used to control the conversion ratio (non-dcx operation) High step-down, or high step-up conversion ratios feasible at high efficiencies (well above 90%). Bidirectional power flow is possible For standard unidirectional applications, the secondary-side bridge can be just diodes (operation is similar, but not the same) Half-bridge and push-pull variations are available Some DAB issues: Transformer saturation (may require a series blocking capacitor) Switching frequency trade-offs (F << 1; transformer and inductor core and proximity losses) Significant new developments in Power Electronics based on emerging compound semiconductor (elements from 2 or more groups of the periodic table) devices (e.g. GaN, GaAs, SiC) 9

10 Application example: Automotive battery power management in a fuel-cell vehicle* *F. Krismer, J.W.Kolar, Accurate Power Loss Model Derivation of a High-Current Dual Active Bridge Converter for an Automotive Application, IEEE Trans. On Industrial Electronics, March

11 Efficiency results 11

12 Power flow control in 3-phase AC power distribution* Purpose: control active and reactive power flow; increasingly important function in AC power distribution systems with distributed resources Solution above requires bulky 50/60 Hz transformers, e.g. for a 6.6 kv, 1 MVA unit, each transformer weights around 4,000 kg * A. Inoue, H. Akagi, A Bidirectional Isolated DC DC Converter as a Core Circuit of the Next- Generation Medium-Voltage Power Conversion System, IEEE Trans. on Power Elect., March

13 Solution based on modular DCX Each cell can be switched as +E, -E, or 0 With N = 9 cells, a total 19 levels are available to synthesize high-quality sine-wave 13

14 Converter realization 14

15 Spring 2013: ECEN 5807 Modeling and Control of Power Electronics Averaged switch modeling and simulation (Section 7.4 and Appendix B) Techniques of Design-Oriented Analysis, with Application to Switching Converters Middlebrook's Extra Element Theorem (Appendix C) Input Filter Design (Chapter 10) The n-extra Element Theorem Middlebrook's Feedback Theorem Dynamic modeling and simulation of converters operating in discontinuous conduction mode (Chapter 11 and Appendix B) Introduction to sampled-data modeling Current Programmed Control (Chapter 12 and Appendix B) Introduction to Digital Control of Switching Converters Power-Factor Correction Rectifiers (Chapters 16-18) 15

16 Professional Certificate in Power Electronics Awarded upon completion of ECEN5797, ECEN5807 and ECEN5817 Send a request to Adam Sadoff, ECEE graduate program administrator sadoff@schof.colorado.ed 16

17 New courses offered in Fall 2012 and Spring 2013 ECEN5017 Power Electronics for Electric Drive Vehicles Fall

18 New courses offered in Fall 2012 and Spring 2013 ECEN5737 Adjustable Speed AC Drives Spring

19 New DOE GATE Center: Innovative Drivetrains in Electric Automotive Technology Education (IDEATE) Joint center between CU-Boulder and UC Colorado Springs campuses Graduate certificate in battery controls and electric drivetrains 19 19

20 Thank you for your hard work, good luck with the finals 20