An Overview and Comparison of on Board Chargers Topologies ... · 5/11/2017 · PFC stage: Totem Pole PFC › Requires HV switches with good body diode › Uses only 2 diodes and

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

2 2017-05-11 Copyright © Infineon Technologies AG 2017. All rights reserved.

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 +

-


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.


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


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


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


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


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


• 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


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


• 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


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


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%


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


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


› 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


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)


› 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


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%


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


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


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


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


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


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.


Documents

An Overview and Comparison of on Board Chargers Topologies ... · 5/11/2017 · PFC stage: Totem Pole PFC › Requires HV switches with good body diode › Uses only 2 diodes and