Power electronics solutions for DC networks

Transcription

1 Power electronics solutions for DC networks Prof. Dr.-Ing. Marco Liserre Chair of Power Electronics Christian-Albrechts-Universität zu Kiel Kaiserstraße Kiel

2 slide 1

3 Smart Grids Integration of Renewable/ Electric vehicles Energy Systems EEMESWEA und Add-On ENSURE New Grid Structures HEART DFG SPP DACH Project Synchronization of the power electronics interfaces Smart Transformer Electric vehicles and Bus charging stations, Cold ironing for Ships MMC, DC-fault handling slide 2

4 Laboratory slide 3

5 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 4

6 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 5

7 DC-grid for Data Center Data Center traffic triples from 2015 to 2020 Consuming around 2 percent of the worlds electrical energy AC-Architecture Source: Cisco DC back up power of the UPS needs to be converted to AC power Bypassing of UPS improves efficiency but introduces reduced system reliability DC-Architecture Source: Emerson Network Power Source: Emerson Network Power Direct integration of DC back up power Less conversion stages Higher efficiency Reduced installation and maintenance costs Smaller footprint slide 6

8 DC-grid for Charging stations AC-Charging DC-Charging Source: ABB Source: SAE J1772, SAE Hybrid, IEC 62196, IEC DC -Grid EV charging can be divided into AC and DC charging DC Charging is mostly related to fast charging Power electronic is located outside the car for DC charging Reduction of conversion stages Higher efficiency Simpler integration of energy storage to compensate peak load demand slide 7

9 DC-grid for Aereospace Looking for power converter solutions: Fault-tolerant Offering connectivity but also isolation Microgrid on board Very high safety requirements -> bus isolation and separation The power density is a priority Load prioritization: during each flight stage, the loads have changing priority (landing gear, de-icing system) Intrinsically hybrid (AC and DC) with multiple voltage levels slide 8

10 DC-grid for Distribution Several Concepts exist (from nano-grid to classical MVDC distribution) HEART, Kiel Efficiency and Safety Near to come applications: industry dc network, public illumination, Smart house FREEDM Virginiatech slide 9

11 The LV-Engine Network Concept Bringing valuable functionalities to the 11kV/LV network Voltage regulation Power flow control Harmonic filtering Reactive power injection LVDC supply slide 10

12 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 11

13 DC-DC Stage: Implementation concept Non-Modular vs. Modular Fewer number of components High Voltage WBG devices Simple control/communication system Low voltage/current rating semiconductors Scalability in voltage/power Fault tolerance capability Reduced dv/dt and di/dt slide 12

14 DC-DC Stage: Implementation concept Modularization Level Cell level Converter level System level Different modular levels can be freely combined slide 13

15 Review on dc-dc converters Relevant converters: Dual-Active-Bridge Converter Power converter: DAB Cell topology: FB, 3L Semiconductor: Mosfet, SiC slide 14

16 Review on dc-dc converters Relevant converters: Three-Phase Dual-Active-Bridge Converter Power converter: 3P-DAB Cell topology: FB-3Legs/-6Legs Semiconductor: Mosfet, IGBT slide 15

17 Review on dc-dc converters Relevant converters: Multiple-Active-Bridge Converter Power converter: TAB Cell topology: FB Semiconductor: Mosfet, IGBT slide 16

18 Review on dc-dc converters Relevant converters: Series-Resonant Converter Power converter: SRC Cell topology: FB, HB, 3L, NPC Semiconductor: Mosfet, IGBT, SiC, GaN slide 17

19 Review on dc-dc converters Relevant converters: Phase-Shift Full-Bridge ZVS Converter (PSFB-ZVS) Power converter: PSFB Cell topology: FB Semiconductor: SiC, GaN slide 18

20 Review on dc-dc converters Relevant converters: Existing dc-dc converters: (published in literature) slide 19

21 Series-Resonant Converter Target: Efficiency Reliability Accurate losses modeling Automatic design - (optimum parameter selection) Wideband gap devices Fault tolerant topology Lifetime devices considerations slide 20

22 Series-Resonant Converter Overview of basic dc-dc topologies suitable to be used as a building block of the ST dc-dc stage Influence on efficiency: Wideband-gap devices plays an important role Design: correct parameters selection CAU Kiel dc-dc converter Max Eff = 98.61% Eff (@P max ) = 98.1% L. F. Costa, G. Buticchi, M. Liserre, Highly Efficient and Reliable SiC-based DC-DC Converter for Smart Transformer, in IEEE Transactions on Industrial Electronics slide 21

23 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 22

24 Multiwinding-based topologies Connect more dc devices or dc-buses It is fault-tolerant It is a compromise between not-modular and modular topologies (only one transformer) M. Liserre, G. Buticchi, L. Costa, M. Andresen Spannungswandler, Verfahren zu dessen Betrieb und Computerprogramm, German Patent DE slide 23

25 Multiwinding-based topologies Unbrekable HEART Proof-of- Concept ERC Grant slide 24

26 Multiport Series-Resonant Converter Extension of Series-Resonant Converter Characterisitcs: 50 % duty cycle Open-loop stability Soft switching High efficiency (ZVS/ZCS) One magnetic core Integration of storage in floating port Redundancy Fault Tolerance Main Challenges Accurate determination of multi-winding transformer parasitics Accurate tuning of the resonant tanks to ensure good power balance in open-loop slide 25

27 Multiport Active Bridge Converter Extension of Dual Active Bridge Converter Characteristics: Higher controllability Higher control complexity Soft switching High efficiency (ZVS) One magnetic core Integration of storage in floating port Redundancy Fault Tolerance Main Challenges Accurate determination of multi-winding transformer parasitic Reactive power circulation slide 26

28 Fault tolerant operation of Multiwinding topologies Modular Contactor Ka-Kf to isolate faulty bridge Modular with Multiwinding For single-winding topology: 1 Fault = 2 FB s lost For multi-winding Topology: 1 Fault = 1 FB lost Doubles (x2) possible faults slide 27

29 QAB for charging stations Interphase Topology -> power balanced among the phases In comparison with not-interphase QAB: Higher efficiency (after 10 chargers) Lower cost (after 8 chargers) slide 28

30 QAB for Aerospace Performance Features High efficiency (above 98%) Control Unit for safety applications SiC Power Electronics with planar transformer In cooperation with Prof. Buticchi slide 29

31 QAB for distribution QAB Converter Multi-objective design: Target: Efficiency & cost L. Costa, G. Buticchi, M. Liserre, Optimum Design of a Multiple-Active-Bridge DC-DC Converter for Smart Transformer, IEEE Transactions on Power Electronics. slide 30

32 QAB for distribution QAB Converter slide 31

33 QAB for distribution Overview of basic dc-dc topologies suitable to be used as a building block of the ST dc-dc stage Influence on efficiency: Wideband-gap devices plays an important role Design: correct parameters selection CAU Kiel dc-dc converter Max Eff = 97.5% (SiC) Highest efficiency of a MAB converter slide 32

34 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 33

35 Comparison between DAB (modular) and QAB (semi-modular) Comparative analysis: considering different semiconductor technologies 1. Design consideration Semiconductors / Capacitors / Heatsink Magnetics (wire losses and cost) Auxillaries (gate driver, power supply, communication) 2. Specifications 3. Design algorithm slide 34

36 Comparison between DAB and QAB Comparative analysis results of performance (losses/kw) and cost 1. DAB-Based 2. Assymetrical QAB 3. Symetrical QAB (V) 4. Symetrical QAB (P) Standard / Benchmark 9 MV cells 9 Units 9 MV cells 3 Units Same voltage MV side 10 MV cells 5 Units Same voltage MV side 6 MV cells 6 Units Same power rating per unit slide 35

37 Comparison between DAB and QAB But why QAB and NOT DAB? Around 20% of cost reduction when AQAB is adopted slide 36

38 Comparison between DAB and QAB But why QAB and NOT DAB? Around 20% of cost reduction when AQAB is adopted DAB and QAB have similar efficiencies (only 5% of difference in favor of the QAB) SiC offers 10% of losses reduction, but increase the cost in around 40% Reduced number of: Auxilar components (GDU, APS and control) Semiconductors on LV side Less semiconductor on the LV side, but with higher current rating. Few impact on the cost slide 37

39 Comparison between DAB (notmodular) and QAB (semi-modular) Rated Power 2.5 MW Rated Power 2.5 MW Input voltage range 900 V ~ 1.5 kv Input voltage range 1.1 kv ~ 1.5 kv Output voltage 1.1 kv Output voltage 1.1 kv Switching frequency 1 khz Switching frequency 1 khz Dual Active Bridge Quadruple Active Bridge slide 38

40 Specification and Requirements Rated Power Input voltage range Output voltage Switching frequency 2.5 MW 900 V ~ 1.5 kv 1.1 kv 1 khz Rated Power Input voltage range Output voltage Switching frequency 2.5 MW 1.1 kv ~ 1.5 kv 1.1 kv 1 khz Different design possibilities DAB QAB 1 QAB 2 Chosen design slide 39

41 Comparison of DAB and QAB solutions Efficiency calculated for DAB in case of Transformer resistance equal to 1 mω, in case it is 10 mω the efficiency is expected to drop to 95 % at full load The efficiency of the QAB solutions is expected to be better The cost of multiwinding Transformer in comparison with one not-multiwinding Transformer is 20 % more. The cost of the devices for QAB is expected to be lower slide 40

42 Outline DC-grids in Data Center, Charging Station, Aerospace, Distribution DC/DC Converters overview Potential of Multi-winding-based topologies (semi-modular) Comparison: Modular/Semi-modular, Semi-modular/not-modular Conclusions slide 41

43 Conclusions DC-grids brings energy saving and more reliability in several applications Isolated DC/DC Converters is not yet a mature technology, no standards product to buy exist! Multi-winding-based topologies have potential to connect several buses at different voltages and offer modularity with reduced costs (only one trafo!) slide 42