Power Electronics C Mark Johnson University of Nottingham University of Nottingham
Overview l Introduction to Power Electronics l Current Challenges for Power Electronics l IeMRC Power Electronics Themes
IeMRC Power Electronics Themes l Research Examples l Conclusions What Does Power Electronics Do? Efficient, flexible control and conversion of electrical energy • Typically involves controlled change of voltage/current level and/or frequency • Conversion efficiencies typically in excess of 90% Rectification AC sources: single phase or three phase AC AC DC DC­DC conversion conversion
AC loads: machines, industrial processes, power transmission and distribution systems AC­AC conversion AC DC Inversion DC sources: batteries, solar panel, power supply output DC loads: electrical/electronic circuits, machines, industrial processes Benefits of Power Electronics Environmental Energy Availability Sustainability footprint Efficiency Flexibility l l l l l Energy saving Cost and space saving Reduced maintenance Longer life Low environmental impact l l l l Quality of life Better performance Better control Flexibility Improved reliability
Power Electronics Applications 1 cm 1 W 200 m 2 GW
Power Electronics is Growing Enabling technology throughout the energy supply chain Primary energy extraction & transport Energy conversion & concentration Work Energy transmission and distribution Energy delivery Heat IT 14% Electricity 39% Other 40% Motion 51% Transport 21% ~16,000 TWh/annum global electricity 40% today growing to 60% by 2040 80% of this will be managed by power electronics 80% of this will be managed by power electronics
Lighting 19% HVAC 16% The Market l l l l l Power electronics is an essential technology in all future sustainable energy scenarios It is the only technology that can deliver efficient and flexible control of electrical energy share of electrical energy which will be controlled by power electronics is expected to increase from 40% in 2000 to 80% in 2015 Global market for power electronics devices in 2007 was $9.8bn and is expected to reach $17.7bn by 2013 with a compound annual growth rate of 11.6% 1 In 2007 power electronics contributed to another $1 trillion of sales in related hardware electronics [1] “Power Electronics: Technologies and Global Markets” http://www.electronics.ca/reports/power_energy/utility_power_ele http://www.electronics.ca/reports/power_energy/utility_power_ele
ctronics.html Growth areas for power electronics l l l l l l l l Power supplies: new concepts can improve overall efficiency by 2 new concepts can improve overall efficiency by 2­ 4% Motor drives: use 50­60% of all electrical energy consumed in the 60% of all electrical energy consumed in the developed world: a potential reduction in energy consumption of 20 developed world: a potential reduction in energy consumption of 20­ 30% is achievable. Home appliances: electronic thermostats for refrigerators and electronic thermostats for refrigerators and freezers can yield 23% energy saving: an additional 20% can be saved by using power electronics to control compressor motors (with 3­phase PMDC motors). Lighting: power electronics can improve the efficiency of power electronics can improve the efficiency of fluorescent and HID ballasts by a minimum of 20%. Connection of renewable energy sources renewable energy sources to power grids is not possible without power electronics. Future electricity networks will incorporate power electronics. will incorporate power electronics. Automotive: electric and hybrid drive trains are only possible with electric and hybrid drive trains are only possible with efficient and intelligent power electronics. Aerospace: weight savings through power electronics will reduce weight savings through power electronics will reduce fuel demand over the flight cycle. fuel demand over the flight cycle.
Why Manufacture in the UK? l l l l UK based technology and manufacturing capability is currently relatively strong UK is internationally competitive across the whole supply chain Many systems are application specific, highly customised and tend to have a relatively high added value Suited to a technologically advanced manufacturing base and can absorb the relatively manufacturing base and can absorb the relatively
high UK labour costs Early History of Power Electronics I d1 i as1 3 phase input v L i L i as2 I d 2 Bridge rectifier (1896) Cycloconverter Thyratron (1922) (1927) 1880 Selenium Mercury arc rectifier Phase angle rectifier (1876) control (1903) (1902) Ignitron (1933) HVDC (1935) Silicon power diode (1954)
Thyristor (1957) Thyratron motor (1934) 1960 Development of Power Semiconductor Devices Semiconductor Devices
100 6kV, 6kA Switched Power (MVA) 2.5kV, 0.5kA 4kV, 3kA 10 8kV, 4kA 6kV, 6kA 4.5kV, 4kA 12kV, 1.5kA 4.5kV, 2.1kA 4.5kV, 3kA 6.5kV 0.9kA 2.5kV, 1.5kA 3.3kV, 1.2kA 1kV, 0.15kA 2.5kV, 0.6kA 1 1.7kV, 1.2kA 1.2kV, 0.6kA 1kV, 0.3kA 0.1 0.4kV, 0.08kA 0.6kV, 0.2kA ETT LTT GTO IGBT 0.5kV, 0.2kA IEGT GCT 1kV, 25A 0.01 1960 1970 1980 Year 1990 2000 What’s in Today’s Power Electronic What’s in Today’s Power Electronic Systems? Half­bridge sandwich (one per phase) DC+ C DC 20mF, 1000V S A+ D A+ P C S A­ 600 V D A­ P B DC­ GDU A GDU B GDU C Passive components Gate drives and control Power semiconductor module P A Thermal management
Overview l Introduction to Power Electronics l Current Challenges for Power Electronics l IeMRC Power Electronics Themes
IeMRC Power Electronics Themes l Research Examples l Conclusions Challenges in Power Electronics l l l l l l Increased power densities High reliability in extreme operating environments Lower electromagnetic emissions Modular turn­key systems Higher levels of integration Higher levels of integration
Lower through­life costs Challenges in Power Electronics: Road Mapping Exercise Road Mapping Exercise
Initial workshop review of results Structured collection of expert input at workshop Online review of roadmap Roadmapping Process Knowledge database built from results Analysis H
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Product Area Automotive power train 26 26 Renewable energy sources (grid interface and control) 22 21 Aircraft actuation 25 24 Aircraft power distribution 23 25 Aircraft generation 22 21 Marine propulsion 21 19 Automotive controls 21 21 Rail traction 21 20 High performance drives 21 18 Large industrial drives 21 18 Small drives for home appliances 17 15 Components: active 17 18 Aircraft engine controls 18 17 Power transmission and distribution infrastructure 14 15 Components: thermal management 13 14 Components: passive 11 13 Pulsed power 11 11 Other 1 1 Total Records 325 317 3 1 2 3 3 3 3 3 2 3 2 1 2 3 1 1 1 1 38 216 212 211 205 189 184 179 178 174 160 155 150 149 131 123 105 103 14 2838 1 l l l Priority product areas Priority technology areas TRL analysis 0.9 0.8 0.7 TRL 1­2 0.6 TRL 3­4 0.5 TRL 5­6 0.4 TRL 7­8 0.3 TRL 9
0.2 0.1 0 y2008 y2009 y2010 y2011 y2012 y2013 y2014 y2015 y2016 y2017 Priority Product Areas Product area Proportion of challenges Automotive power train 58% Renewable energy sources (grid interface and control) 53% Aircraft actuation 56% Aircraft power distribution 58% Aircraft generation 52% Automotive controls 50% Marine propulsion 47% High performance drives 50% Rail traction 47% Large industrial drives 44%
l Many challenges apply to a large number of priority product areas l Substantial potential for cross Substantial potential for cross­sector activities Priority Technology Areas Technology area Proportion of challenges Reliability and qualification 61% Packaging and integration 65% Thermal management 56% Materials technologies 55% Efficiency 56% Simulation and design methods 44% Active devices 47%
l Many challenges identify same priority technology areas l Technology areas are strongly interdependent l Priorities are mainly underpinning technologies that can be applied across many product sectors The Power Density Challenge l l How far can we go? Limiting factors:
Cooling
· Losses (efficiency)
· Cooling capability (heat transfer from surface)
· Energy storage requirements (filters etc.)
· Upper limit for “core” temperature Converter volume Heat æ
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Core temperature (Tcore) 3 2 The Reliability Challenge l l l l l Automotive drive train, rail traction, aerospace, renewable generation interfaces etc. are subject to significant load and environmental cycling Desire for higher power density means Desire for higher power density means increased temperatures and increased thermal cycling range increased thermal cycling range – both tend to reduce reliability reduce reliability However… Customers demand very high levels of Customers demand very high levels of availability, unexpected failures are not acceptable Unscheduled maintenance Unscheduled maintenance is time consuming and
expensive Meeting the Challenge Power Quality Energy Efficiency Mission Profile Weight Component Technologies Packaging & Integration Reliability/ Availability Reliability Design Tools & Methodology DC+ S A+ D A+ P A S A­ D A­ Prognostics & Health Management DC­ GDU A Volume Through­life Cost
Thermal Management Power Electronics Integration l l l Performance specifications for power electronics include electrical, reliability, cost and end include electrical, reliability, cost and end­of­life targets Strong interactions between packaging, thermal performance and reliability themes means ALL aspects of power electronics technology must be addressed concurrently An integrated approach is essential in the design and manufacture of future power electronic and manufacture of future power electronic
systems Overview l Introduction to Power Electronics l Current Challenges for Power Electronics l IeMRC Power Electronics Themes
IeMRC Power Electronics Themes l Research Examples l Conclusions IeMRC Projects in Power Electronics Aim: Enhance competitiveness of the UK power electronics industry through world electronics industry through world­leading research into design and manufacturing manufacturing Road mapping Market/customer Aspirations Technology Limiters Technology Drivers Research & Development Requirements
Technology Opportunities ag
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Product Area Automotive power train 26 26 Renewable energy sources (grid interface and control) 22 21 Aircraft actuation 25 24 Aircraft power distribution 23 25 Aircraft generation 22 21 Marine propulsion 21 19 Automotive controls 21 21 Rail traction 21 20 High performance drives 21 18 Large industrial drives 21 18 Small drives for home appliances 17 15 Components: active 17 18 Aircraft engine controls 18 17 Power transmission and distribution infrastructure 14 15 Components: thermal management 13 14 Components: passive 11 13 Pulsed power 11 11 Other 1 1 Total Records 325 317 1 0.9 3 1 2 3 3 3 3 3 2 3 2 1 2 3 1 1 1 1 38 216 212 211 205 189 184 179 178 174 160 155 150 149 131 123 105 103 14 2838 0.7 TRL 1­2 0.6 TRL 3­4 0.5 TRL 5­6 0.4 TRL 7­8 0.3 TRL 9 0.2 0.1 0 y2008 y2009 y2010 y2011 y2012 y2013 y2014 y2015 y2016 y2017 A Joined­Up Approach Up Approach Research & Technology Core Packaging & Integration Reliability Experimental: testing, methodology, qualification Physics of failure models Model validation Design Tools & Methodology New technologies: materials, assembly methods System optimisation Integration of passives SiC & other WBG Thermal Management New technologies: air and liquid cooling System optimisation Real­time models Prognostics & Health Management Technology Road­ mapping TRL 1­4
Technology Demonstration Projects TRL 3­6 IeMRC Power Electronics Cluster EU­funded aerospace research within MOET and Clean Sky JTI TSB­funded programmes in power electronics (TULIP & PEATE) Other IeMRC projects on Advanced Capacitors, Prognostics & Diagnostics IeMRC SiP Design Flagship Project EPSRC­funded research in SiC: Platform grant & responsive mode Power electronics roadmap Reliability and Physics of Failure Advanced packaging Design for qualification EPSRC Grand Challenge: 3­D Mintegration D Mintegration TSB­funded research into improved bonding technology (IMPECT & NEWTON) TSB­funded research into modelling of power modules (MPM) Cluster approach maximises gearing and mutual coupling between projects
Academic Partners power electronics, module design and failure analysis, packaging, EMC, thermal management physics­of­failure reliability predictions, multi­physics modelling and numerical optimisation, design tools partial discharge effects Materials support, interconnect, capacitors component technologies,
component technologies, power electronics high­permittivity dielectrics and Silicon Carbide device fabrication metallography and microscopy Industrial Partners l l l l l l l l l l l l l l Areva T&D Corac Group Dynex Semiconductor Flomerics (Mentor Graphics) Hispano Suiza (Safran) Goodrich GE Aviation International Rectifier Morgan Technical Ceramics Morgan Technical Ceramics
Rolls­Royce Semelab (TT Electronics) SR­Drives TRW Automotive Zodiac Overview l Introduction to Power Electronics l Current Challenges for Power Electronics l IeMRC Power Electronics Themes l Research Examples
Research Examples l Conclusions IeMRC Flagship Project l l l l l Aim: Enhance competitiveness of the UK power electronics industry through improvements to the design and manufacturing manufacturing capability Key target is technologies and techniques to improve power module performance Total IeMRC funding £811 k, 5 directly Total IeMRC funding £811 k, 5 directly­funded academic partners, 11 industrial partners Fundamental research that underpins many activities Total of “geared” funding exceeds £8 M Total of “geared” funding exceeds £8 M
Flagship Themes l l l Road mapping: A UK centred power electronics road map A UK centred power electronics road map highlighting the research priorities for IeMRC/EPSRC and TSB support was published in 2007 Technology watch: The project maintains a “technology watch” The project maintains a “technology watch” on emerging technologies for power electronic modules and associated thermal management systems Reliability and physics of failure
Reliability and physics of failure ·
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Combined Modelling and Accelerated Life Testing carried out by academic and industrial partners
academic and industrial partners Identify Root Cause (Physics) of Failures
Identify Root Cause (Physics) of Failures Develop Physics of Failure models
Develop Physics of Failure models Apply validated models: » » l to assess design options (MPM project) prognostics and health management (IeMRC prognostics and diagnostics project) Advanced packaging: investigate the feasibility of a range of investigate the feasibility of a range of advanced power electronic module manufacturing technologies:
advanced power electronic module manufacturing technologies: ·
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Capacitor technology
Thermal management technology
Thermal management technology Novel Interconnect and die attach
Enhanced wire bonding Power Electronic Modules l l l l l l l Principal functional element of power electronics Physical containment for one or more basic component building blocks e.g. semiconductor dies, resistors, etc. Can include control and protection functions Protection from environment e.g. ingress of liquids, dust etc. Circuit interconnections (internal and external) Electromagnetic management Electromagnetic management – EMC issues
Thermal Management Anatomy of Typical Module and Heatsink Lead­out interconnect Bond wire Encapsulation Housing Thermal stack has 9 layers, 8 interfaces! Thermal stack has 9 layers, 8 interfaces!
Die Solder Direct bonded copper Ceramic Direct bonded copper Solder Copper baseplate Thermal Grease Heatsink Reliability Limitations Repeated heating and cooling of assembly leads to repetitive mechanical stress and eventual failure repetitive mechanical stress and eventual failure
CTE mismatch causes fatigue failure (de­bonding) at heel CTE mismatch causes fatigue failure at interfaces Bond wire Die Solder Direct bonded copper Ceramic Direct bonded copper Solder Copper baseplate Investigating Reliability Limitations l l ­60 to 150 C air­to­air No failure 4000 number of cycles to failure l Combined Modelling and Accelerated Life Testing Identify Root Cause (Physics) of Failures Develop Physics of Failure models Apply in design process and health management 3500 3000 2500 2000 ­60 to 150 C 1500 1000 500 0 1 2 3 4 5 6 7 8 9 10 11 substrate tile number 10000.0 Thousands of Cycles l 1000.0 100.0 10.0 1.0 0.1 10 100 1000 delta T (K) æ T ö
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- K Thermal Management Options Target overall reductions in weight and volume for liquid­cooled systems cooled systems l Comparison of cooler options: Comparison of cooler options:
l · Conventional base­plate and separate cooler
plate and separate cooler · Integrated base­plate cooler
plate cooler · Direct cooler (no base­plate) plate) Base­plate (1­3mm) Cold plate 9 layers 8 interfaces Integrated base­ ­plate cooler 7 layers 6 interfaces Direct substrate cooler 5 layers 4 interfaces
Impingement Cooling Impingement Cooling
1. 2. 3. Jet impingement Heat transfer Mixing of working fluid l
l Jet impingement reduces thermal gradient and thermal resistance Heat transfer coefficient increases (>30 kW/(m 2 K) achieved) 2 Heat from Electronics 1 3 Impingement Cooling l l Prototype coolers manufactured in Stainless Steel (17­4 PH SS) using the Direct Metal Laser ) using the Direct Metal Laser Sintering (DMLS) rapid prototyping process ) rapid prototyping process Grooves machined into the baseplate to improve sealing between adjacent cooling cells Direct cooling of baseplate Direct cooling of DBC substrates
Thermal Impedance l Measure of the ability of the cooler to cope with step inputs and thermal transients Cooling curves at a coolant flow rate of 4 litres/minute Thermal Step Response ­ IGBT Die Temperature 50 45 Die to Coolant Temperature Difference l 40 35 30 25 20 15 10 5 0 0.001 0.01 0.1 1 Time (se conds) COLDPLATE BASEPLATE SUBSTRATE
10 100 Pumping Power Pumping Power
l Power required to pass coolant fluid through the cooler Data shown is for flow rates up to 4 litres/min Die To Coolant Temperature Difference vs Pumping Power 100 90 Die to Coolant Temperature Difference (K) l 80 70 60 50 40 0.00 0.01 0.10 30 1.00 Pumping Power Required (Watts) SUBSTRATE BASEPLATE COLDPLATE 10.00 100.00 Conclusions l Power Electronics:
· Underpins future transport and electricity supply networks Underpins future transport and electricity supply networks
· Is a current and future growth area Is a current and future growth area
· Is an area of UK strength l Key challenges for power electronics include:
Key challenges for power electronics include: ·
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l Increased power densities Increased power densities
Lower electromagnetic emissions
Lower electromagnetic emissions High reliability in extreme operating environments
High reliability in extreme operating environments Modular turn­key systems
key systems Higher levels of integration
Higher levels of integration Lower capital and maintenance costs IeMRC supports research as part of a coordinated programme addressing the key challenges programme addressing the key challenges