1 High Efficiency SiC Power Semiconductor May 20, 2014 Toyota Motor Corporation
Outline 2 1.Overview of power semiconductors 2.Aim of SiC power semiconductor development 3.Steps toward SiC power semiconductor development
(1) Development of hybrid technology 3 EV Motor PCU Battery HV Engine Fuel tank Motor Engine PCU Battery Generator Fuel tank PHV Motor Engine PCU Battery Generator Fuel tank FCV Motor PCU Battery Fuel Hydrogen cell tank Hybrid technology is central to Toyota s development of PHVs, EVs and FCVs. Toyota has positioned it as a core technology.
(2) Hybrid system overview 4 Generator Engine Battery Power control unit (PCU) Power split device Motor The power control unit (PCU) controls the hybrid system s electrical power, playing an important role.
(3) Role of power semiconductors 5 Power module Power semiconductors Power control unit (PCU) Diode Transistor Switch that controls current flow (on/off) Passes electric current in a single direction Conducts up to 200A of electricity Does not conduct electricity even if 1,200V is applied PCUs contain multiple power semiconductors, which are usually made of silicon.
(4) HV electrical power loss 6 Other HV-system components Power semiconductor 20% PCU power loss Other PCU components Approx. 20% of HV total electrical power loss occurs in the power semiconductors One key to improving fuel efficiency is to improve power semiconductor efficiency
(5) Amount of semiconductor usage 7 2008 LS 600h 2009 third-gen Prius 2.60 wafers* 1.11 wafers* PCU power semiconductors Other power semiconductors Microcomputers Memory Power semiconductors account for more than 25% of semiconductors used in hybrids IC Others *Six-inch wafers
(6) Improving silicon power semiconductor efficiency 8 1 st generation Prius 2 nd generation Prius Current Prius Silicon power semiconductor Power loss 1/4 Due to the importance of power semiconductors, Toyota has been developing them in-house since the first generation Prius and has focused on increasing their efficiency.
Outline 9 1.Overview of power semiconductors 2.Aim of SiC power semiconductor development 3.Steps toward SiC power semiconductor development
(1) SiC characteristics (theoretical) 10 SiC* is a compound made of silicon and carbon. (*Silicon Carbide) Power loss 1/10 1 100kHz 10kHz 150 o C Silicon 200 o C 250 o C Drive frequency SiC Drive temperature SiC is the next generation of power semiconductors Compared to silicon, SiC power semiconductors lose1/10 the power and drive frequency can be increased by a factor of ten. Increased fuel efficiency and smaller PCUs
(2) Silicon power semiconductor (transistor) 11 Conduction loss Switching loss Current Tail current During conduction, a portion of current is lost as heat Loss also occurs when the current switches on and off The main cause of loss in silicon power semiconductors is due to tail current when switching between power states
(3) SiC power semiconductor (transistor) 12 Small conduction loss Small switching loss Current Conduction loss in SiC power semiconductor is small Current doesn t tail during switching, meaning loss is small Higher efficiency can be achieved
(4) High frequency drive 13 Current Silicon power semiconductor <10kHz Switching loss Tail current time Current SiC power semiconductor As switching loss is small in SiC power semiconductors, high frequency drive is possible time
(5) Downsizing coil and capacitor 14 Battery DC 200 V Boost Converter PCU DC 650 V Power semiconductor Inverter AC 650 V Coil Tr, M Capacitor Motor Current Higher frequency Time Current Time Coils and condensers temporarily hold electricity and take up 40% of the PCU Coils and condensers can be downsized due to high frequency control within the PCU
(6) Improving fuel efficiency 15 Silicon SiC Goal: 10% fuel improvement * * Japanese JC08 test cycle Due to the increased efficiency, Toyota is aiming for a 10% improvement in fuel efficiency
(7) PCU downsizing 16 Power module Coil Capacitor Goal: 80% less volume Aim to leverage the benefits of high frequency and high efficiency to enable PCU downsizing of 80%
Outline 17 1.Overview of power semiconductors 2.Aim of SiC power semiconductor development 3.Steps toward SiC power semiconductor development
5 mm 6 mm (1) High efficiency SiC power semiconductor 18 5 mm 6 mm SiC transistor SiC diode Jointly developed by DENSO and Toyota Central R&D Labs., Inc. and Toyota. Development of high efficiency SiC power semiconductor
(2) High efficiency SiC power semiconductor (transistor) 19 Transistor cross-section SiC Silicon Planar structure Gate electrode Trench structure (developed) Trench Gate electrode Trench structure (current) Trench Gate electrode Architecture n n + p - n n + p - n + p - n + n + n - n + p + Achieved high efficiency through adoption of trench structure
(3) Evaluation of Test Vehicle 20 SiC transistor SiC diode Test vehicle Evaluation has begun in special test vehicles Over 5% fuel efficiency improvement * confirmed * Under JC08 test cycle
(4) Semiconductor development and production 21 Development and production of PCUs, etc. Development and production of silicon semiconductors Development of SiC power semiconductors A clean room for development of SiC power semiconductors was set up at Toyota s Hirose Plant in December 2013
(5) Hirose Plant SiC trial wafers 22 SiC transistor SiC diode Jointly developed by DENSO and Toyota Central R&D Labs., Inc. and Toyota.
(6)Going forward 23 - Plan to begin vehicle tests on public roads within a year - Toyota has positioned high efficiency power semiconductors as a key technology for improving fuel efficiency for HVs and other vehicles with electrified powertrains and will continue to boost development activities aimed at early implementation of SiC power semiconductors.
Ref.: Automotive Engineering Exposition 2014 24 SiC power semiconductor technology display at Automotive Engineering Exposition 2014, May 21-23. Pacifico Yokohama Exhibition Hall, Yokohama, Japan