an overview and comparison of on board chargers topologies ... · 5/11/2017 · pfc stage: totem...
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Infineon Italy s.r.l. ATV group
An Overview and Comparison of On Board Chargers Topologies, semiconductors choices and synchronous rectification advantages in Automotive Applications
Davide GIACOMINI Principal, Automotive HVICs
Level 1: OnBoard Charger
Level 3:
Charger Station
1.5kW < Power < 3.5kW
16h < Charge Time < 7h
Level 2:
External Charger
3.5kW < Power < 10kW
7h < Charge Time < 2.5h
10kW < Power < 25kW
2.5h < Charge Time < 1h
Electrical Vehicle Charger Classification
http://avt.inl.gov/pdf/phev/phevInfrastructureReport08.pdf
Charge Time for 25kWh battery
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Level 1 AC/DC Onboard Charger
Each Electrical Vehicle has an Onboard charger :
• The output power is between 1.5kW and 3.5kW
• AC input : 16A @ 110V/240V → 2.2kW/3.8kW
• DC Output: 200 - 450V
AC SOURCE
AC/DC PFC DC/DC
High Voltage
Battery
ONBOARD CHARGER
110V - 240V
200V - 450V +
-
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http://avt.inl.gov/pdf/phev/phevInfrastructureReport08.pdf
On Board Charger (AC/DC)
Application
HV Semiconductor chipset
• PFC + DC-DC • Output voltage
250-450V • Output power from
1,5 kWh to 4 kWh
• HV MOSFET or ultra Fast IGBT
• EASY modules • Fast gate driver IC • HV Diodes • SiC Mosfets 2ph
110V/220V
AC input
PFC
µP
HVD
HVD
Double
Isolation
400V
+
In Filter Input
diodes
Output
diodes Out Filter
HV batt.
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On board chargers: simplified schematic
CoolMos
CFDA
CoolMos
CFDA
SiC or FRED diodes
SiC or FRED diode
CV/CC charge
Isolated from GND
Isolated from GND
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LIN/CAN
Double
Isolation
Low Side Driver
Half Bridge Driver
uP controller
Isolation
I/V Battery
Monitoring
BMS
PFC stage: Conventional Boost PFC
› SB: typically superjunction
› DB: Ultrafast Diode or SiC Schottky for lowest loss
› Can achieve >96% efficiency
Typical operating frequency <70 kHz
• Keep fundamental and 2nd harmonic
below 150 kHz EMI;
Typically Continuous Conduction Mode
• Lower EMI and good balance
between ripple current and switching
losses;
Discontinuous or Critical mode only for
low power applications (not in OBC);
• Higher ripple current but allows ZVS
and switching loss reduction
Dominant loss is input bridge
rectifier
• 1-2% total efficiency loss due to input
bridge
REF: “Circuit topologies for PWM boost rectifiers operated from 1ph ad 3ph AC supplies and using either single or split
dc rail voltage outputs”, J. C: Salmon; IEEE TRANSACTIONS ON POWER ELECTRONICS, 1995
«Performance Evaluation of Bridgeless PFC Boost Rectifiers», Laszlo Huber, Yungtaek Jang and Milan M. Jovanovic;
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 3, MAY 2008
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PFC stage: Interleaved Boost PFC
REF: “An Automotive On-Board 3.3 kW Battery Charger for PHEV Application”, Deepak Gautam, Fariborz Musavi,
Murray Edington, Wilson Eberle, William G. Dunford; VEHICLE POWER AND PROPULSION CONFERENCE (VPPC),
2011 IEEE
› QBx: typically superjunction
› DBx: Ultrafast Diode or SiC Schottky for lowest loss
› Operation 180° out of phase
› Reduces input/output ripple and achieves >96% efficiency
Doubles the effective switching
frequency
• Reduces EMI and input filter
size
• Reduces output ripple
Can work in Discontinuous or
Critical mode on each section
since current ripple add on input
bridge
Dominant loss is input bridge
rectifier
• 1-2% total efficiency loss due
to input bridge
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PFC stage: Dual Boost Bridgeless PFC
Cb
VPFC
RL
D1 D2
Da Db
S1 S2
› Dual boost configuration, no ripple cancellation
› Saves 2 diodes vs. interleaved boost PFC
› S1, S2: typically superjunction
› D1, D2: Ultrafast Diode or SiC Schottky for lowest loss
S1, D1 and S2, D2 work on semi
sinusoids
Only one input diode in conduction
at all times
• 50% losses on input diodes vs.
bridge configuration
• Achieves 98% efficiency
Switch losses are dominated by:
• Conduction (especially severe
for high ripple CrCM and DCM)
• Turn-on speed
• Eoss (energy in Coss) only for
CCM)
• Turn-off speed
Compared to Conventional boost PFC, eliminates 1 diode drop and adds an entire boost stage
REF: «Performance Evaluation of Bridgeless PFC Boost Rectifiers», Laszlo Huber, Yungtaek Jang and Milan M. Jovanovic;
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 3, MAY 2008
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PFC stage: Totem Pole PFC
› Requires HV switches with good body diode
› Uses only 2 diodes and 2 switches
› S1, S2: cannot be Superjunction, use SiC or GaN
› D1, D2: slow speed low Fwd diodes => eliminates SiC need
Can achieve > 98% efficiency
D1 and D2 work on semi
sinusoids, can be replaced by SJ
Mosfets
Only one input diode in conduction
at all times
• 50% losses on input diodes vs.
bridge configuration
CCM mode of operation
Switch losses are dominated by:
• Conduction
• Turn-on speed
• Eoss (energy in Coss)
• Turn-off speed
Cb
VPFC
RL
D1
D2
S1
S2
REF: «Design of GaN-Based MHz Totem-Pole PFC Rectifier», Zhengyang Liu, Fred C. Lee, Qiang Li;
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, VOL. 4, NO. 3, SEPTEMBER 2016
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PFC stage: Full Bridge Totem Pole PFC
› Requires HV switches with good body diode => topology is GaN or SiC enabled
› Uses only 4 switches, all work in PWM mode
› No diodes involved, reduces crossover distortion
› Switches cannot be Superjunction, need fast body diode
Can achieve > 98% efficiency
Most complex solution.
No diodes in conduction, except
during dead times
• Reduced cross over distortion
CCM mode of operation
Switch losses are dominated by:
• Turn-on speed
• Eoss (energy in Coss)
• Turn-off speed
Cb
VPFC
RL
S1
S2
REF: «Evaluation of a non-isolated charger», Robert Nystrom, Yuxuan He; Department of Energy and Environment
Division of Electric Power Engineering, CHALMERS UNIVERSITY OF TECHNOLOGY, GOTHENBURG, SWEDEN 2012
S4
S3
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Integrated motor drive and battery charger
REF: «Grid-Connected Integrated Battery Chargers in Vehicle Applications: Review and New Solution», Saeid Haghbin, Sonja
Lundmark, Mats Alaküla, and Ola Carlson; IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 60, NO. 2, FEB. 2013
«Review of Battery Charger Topologies, Charging Power Levels, and Infrastructure for Plug-In Electric and Hybrid Vehicles»,
Murat Yilmaz and Philip T. Krein; IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 5, MAY 2013
› Uses existing inverter for double function: traction and charger
› Inverter uses IGBTs, not optimal switches for a charger, efficiency not at top.
› Not isolated from mains => need large EMI filter, more complex monitoring
› Saves BOM and costs but adds complexity Needs a split-winding motor
configuration to avoid torque
during charging
IGBT antiparallel diodes have to
be chosen accordingly
Efficiency not at the top
Switch losses are dominated
by:
• IGBT fwd dropout
Boost Inductor Boost Inductor
Power
Power
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Conventional PFC losses in OBC
› In a standard boost PFC the input stage is still today using diodes since:
› No need for control signal;
› HV mosfets so far didn’t have a low enough Rds-on vs price to become competitive versus diodes. Now the use of new generation technologies or new material allows this.
Power dissipated in the input bridge is high compared to the global balance;
Source: Design of High Efficiency High Power Density 10,5kW 3ph PBC for (H)Evs, G. Yang and all, PCIM Europe 2016
Output
› Total losses: 96,5W
PFC stage power loss breakdown
32,5%
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DC/DC stage: ZVS phase shift (ZVS-PS) › Usually Full Bridge configuration for higher energy density
› S1-S4: HV mosfets or SiC with fast body diode
› D1-D4: Ultrafast Diode or SiC Schottky
› Frequency around 100kHz typically
PWM control needs dead time
adjustment with load and Vbus
changes
Voltage Mode control uses 50%
duty cycle and needs large value
DC decoupling capacitor at primary
Leading edge switches are more
difficult to achieve ZVS at light load
Synchronous rectification at
secondary would require
recontruction signal from primary
diagonals controls.
Relevant losses on output
bridge rectifier
Vbatt
D4
D2 D1
D3
S3
S1
Lr
Lo
Co
S2
S4
HV
batt.
Vbus
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DC/DC stage: LLC resonant › Usually Full Bridge configuration for higher energy density
› Most popular working above resonance (ZVS mode)
› S1-S4: Typically Superjunction or SiC
› D1-D4: Ultrafast Diode or SiC Schottky
› Frequency range < 200kHz typically
Input and Output sinusoidal current =>
easier filtering and lower EMI
50% duty cycle control
Small or no output inductor => lower
overvoltage on secondary diodes May
allow 600V mosfet synchronous
rectification
Needs low value high voltage capacitor
for resonance, also providing DC
decoupling
Simpler control strategy than ZVS-PS
(frequency variation)
Synchronous rectification at secondary
would require extra current or voltage
sensing, since phase shift with input
changes with load and Vbus
Relevant losses on output bridge
rectifier
Vbatt
D4
D2 D1
D3
S3
S1
Lr
Lo
Co
S2
S4
HV
batt.
Vbus
Cr
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DC/DC stage: LLC resonant below resonance
› Full Bridge configuration for higher energy density
› S1-S4: HV mosfets or SiC, need ultrafast body diode
› Not popular since cannot use Superjunction (ZCS mode)
› D1-D4: Ultrafast Diode or SiC Schottky
› Frequency range < 200kHz typically
Input and Output sinusoidal current
=> easier filtering and lower EMI
Small or no output inductor => lower
overvoltage on secondary diodes
May allow 600V mosfet synchronous
rectification
Frequency reduces at light load
where converter operates most of
the time => lower switching losses
Simpler control strategy than ZVS-
PS (frequency variation)
Synchronous rectification at
secondary would require extra
current or voltage sensing, since
phase shift with input changes with
load and Vbus
Relevant losses on output bridge
rectifier
Vbatt
D4
D2 D1
D3
S3
S1
Lr Co
S2
S4
HV
batt.
Vbus
Cr
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HV DC/DC –LLC converter in OBC
› In a OBC the output stage is still today using diodes since:
› No need for control signal, however not easily available in a LLC topology, mostly used in OBCs for its sinusoidal current waveform;
› HV mosfets so far didn’t have a low enough Rds-on vs price, to become competitive versus diodes. Now the use of new generation technologies or new material allows this.
Power dissipated in the output bridge is very high compared to the global balance;
many designers are looking for a viable solution
Source: Design of High Efficiency High Power Density 10,5kW 3ph PBC for (H)Evs, G. Yang and all, PCIM Europe 2016
Output
› LLC stage power loss breakdown
Total losses: 105.1W
50,1%
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Synchonous Rectification easily implemented
Primary Side
uP controller
SR PWM generation
SR G
ate
Sig
nal
Pri
mary
gate
dri
vers
Optoisolation
Signal Conditioning
Secondary Side
Gate Driver
Gate Driver
AUIRS1170S replaces:
› 1 current sensing IC
› Some SW development in uP
› 1 opto
› 1 Gate driver
REF: «3 kW dual-phase LLC demo board Using 600 V CoolMOS™ P7 and digital control by XMC4400» AN_201703, INFINEON, MARCH 2017
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Self controlled, 600V active bridge scheme
› 1x AUIRS1170S + 4 SMD components replace each large diode of the bridge
› As shown this will save around 50% of the losses in the HV-DC/DC converter output stage and 33% in the input bridge
› This will also greatly reduce the size of heat sinks and save money on mechanics, to compensate higher cost of Mosfet + SR_IC
Output
Iout =>
Iin =>
Vout
Vd2 Vd1
Vinp
Vinm
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600V active bridge simulation, sinusoidal current input
Vd1 Vd2
Vout
Vinp-Vinm
Vg2 & Vg4-Vs4
Vg1 & Vg3-Vs3
Iin
Iout
Iin= sin. current gen. 4Apeak @ 85kHz, Vout = 500V, Rload = 200W, Cout=100ouF, Pout= 1250W
Gate voltages accurately track the input current, a slight delay (600ns) is visible at turn-on
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600V active bridge hardware and test
• No heatsink needed!
• At 8A – 380V output (3kW), Tcase = 45C (only 20C above Ta)
• Saves about 16W power => diodes would need at least a <5C/W heat sink to run at Ta=100C
• Efficiency gain at 3kW is only 0,5%, (limited by slow body diodes recovery), still saves money on cooling solution!!!
• Picture of the HV DC/DC LLC converter prototype, obtained by reworking a 400V-12V demoboard, replacing the transformer and the output stage, to deliver 380V output
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600V active bridge in a 4kW DC/DC stage Waveforms comparison
400V
Body Diodes
Active bridge
Low Iout Vd2
Vprim
Vprim
Vg2
Ultrafast Diodes
Vg2 Vg1
Vout
Vprim
Vprim
Iout
Iout
Iout
Iout
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Conclusions
› Several solutions are existing in the market for On Board Chargers, PFC and DC/DC stages use many different topologies;
› New topologies are enabled and give a significant benefit by using Wide Bandgap switches, SiC and GaN;
› Input and output diodes represent a large portion of total losses, due to their high forward dropout, in both PFC and DC/DC stages: – In a standard boost PFC, around 33% of total power losses are in the input
bridge diodes; – In a HV-DC/DC converter, around 45-50% power losses are in the output
Ultrafast Diodes rectification;
› Synchronous rectification may allow good reduction of diodes’ losses in both stages and boost efficiency of standard topologies: – This will also greatly reduce the size of heat sinks and save money on
hardware, to compensate higher cost of Mosfet+SR_IC;
› Slow body diodes of most very low RDS-on MOSFETs may reduce the Synch-Rect advantage, use of SiC or GaN switches can avoid this drawback.
› For input bridges the advantage of using synchronous rectification is much more evident since the lower operating frequency.
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