high performance voltage doubler - brusa.biz

© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 23.06.2021 11© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 2021/06/21

High Performance

Voltage Doubler

The Fast Charging Booster

for the Porsche Taycan

Dr. Holger Fink

Dr Holger Fink

Dr Vladan Lazarevic

Dr Tobias Wellerdieck

© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 23.06.2021 22

Content and scope

© BRUSA

1 A brief introduction of BRUSA

2 The authors

3 The problem to be solved

4 The basic idea

5 The technical solution

6 Conclusions and outlook

© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 22021/06/21


1 A brief introduction

of BRUSA



A brief introduction

of BRUSA

1985

BRUSA started operations in 1985 BRUSA is a pioneer in eMobility

History

1987



2021


of BRUSA

BRUSA is well known for its

innovative products and

solutions: highest efficiency

and power density

Tour de Sol

2011



2021


of BRUSA

2012

On-Board-Charger

(OBC)

• First 22kW On-Board Charger

Hybrid Synchronous

Motor (HSM)

• Electric motor with 97% efficiency

• Technology used today in almost

all automotive electric drive units

2013




of BRUSA

2018 2019

Wireless Charging (ICS)

• First automotive Wireless

Charging System

Fast Charging Booster

• 400V to 800V Fast Charging Booster

• DC/DCs for 400V/48V/12V

2021



Japan

Distributor

Munich, Germany

BRUSA Elektronik GmbH

USA

Distributor

Heimsheim, Germany

BRUSA Elektronik AG

Shenzhen, China

BRUSA Electronic

Technology Co., Ltd

Sennwald, Switzerland

BRUSA Elektronik AG


of BRUSA


© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 23.06.2021 99© BRUSA


of BRUSA

→ Only examples, in total more than 700 customers



BRUSA provides all products for BEV

and FCEV but the Battery and the Fuel Cell Stack


of BRUSA



The

authors2



Dr. Tobias WellerdieckDr. Vladan Lazarevic Dr. Holger Fink

The authors



3 The problem to be

solved

13© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 132021/06/21


Market trend for high performance and long

distance EVs: Powertrain voltage will increase

from 400V to 800V

Advantage:

• Enables fast charging with higher power

Example:

• Fast charging current limited to 350A

→ Charging @ low SoC* 2 times faster

→ Charging up to 70% SoC almost 2 times faster

The problem to be solved

350A

& :

© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 1414

*SoC = State of Charge

2021/06/21



The Porsche Taycan

• First mass produced EV in the market with 800V

Powertrain

• Fast charging with up to 270kW at the new 1000V/350A

Fast Chargers

• Charging from 5% SoC to 80% SoC in 22.5min

But:

• Fast Charging Systems for 800V Powertrains are

currently not worldwide available

• Even in countries which have the new 1000V Fast

Chargers, the coverage is by far not sufficient

Therefore:

• A solution to charge the 800V Powertrain at 400V

Fast Chargers with high power is required



The driver wants to charge at a Fast

Charging station and plugs in the

charging cable in the charging socket

Use case: Task:

400V

800V

150kW

270kW


@

@

DC Fast Charger

400V

or 800V


At the Fast Charging station the Taycan

should be charged automatically with

up to:



DC Fast Charger

400V

or 800V



The basic

idea4



The basic idea

800V Fast Charging

@ CCS2* Fast Charging station (<350kW, 200V-1000V, <500A)

*CCS2 Combined Charging System 2.x

DC Fast Charger

800V



The basic idea

560V

840V

HV Powertrain, Battery, OBC and DC/DCs

Charging Station

560V

840V

1000V

200V

Used voltage range

to charge the battery

800V Fast Charging

@ CCS2* Fast Charging station (<350kW, 200V-1000V, <500A)


DC Fast Charger



The basic idea

400V Fast Charging

@ CCS1* Fast Charging station (<500V)


DC fast chargerDC Fast Charger

400V



The basic idea

500V

0V

Charging Station


560V

840V


400V Fast Charging




1. Standard Solution: Boost Converter

• 2 control systems (Charging Station and DC/DC) →

output voltage of the Charging Station not determined

• Whole power processed by the Converter Cell

• Efficiency: 96% efficiency of Converter Cell would lead to

96% efficiency of the Booster

The basic idea

Different approaches for the DC/DC Converter



2. BRUSA solution: Voltage Doubler • 2 DC/DC converters in parallel / seriell configuration

• Converter Cell with voltage transfer of almost 1:1

• Booster with fixed input-to-output voltage gain

(Vout /Vin = 2)

• Output voltage of the Charging Station determined: Ubat/2

• Only 1 control system (Charging Station)

• Only half of the power processed by the Converter Cell

→ high power density

• High efficiency: 96% efficiency of Converter Cell leads to

98% efficiency of the Booster

→ Voltage Doubler has significant advantages

The basic idea

Different approaches for the DC/DC Converter



The basic idea

500V

0V

Charging Station


560V

840V


400V Fast Charging



420V

280V

Used voltage range

to charge the battery


The technical

solution5



Basics

• Resonant switched-capacitor Converter (RSCC)

• Resonant tank with LR and CR

• Constant output-to-input voltage ratio: VBAT /Vin ≅ 2

• Unidirectional version

• Bidirectional version feasible (CHAdeMO):

diodes (D1 & D2) need to be replaced with IGBTs

• Semiconductor devices + DC-link capacitors are

rated 650V

The technical solution


connector to Fast Charging Station

vehicle battery

© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 27272021/06/21 27




Ideal signal curves

0 < t < TS/2: ----- «charging the resonance capacitor»





connector to Fast Charging Station

vehicle battery

Ideal signal curves

TS/2< t < TS: ----- «discharging the resonance capacitor»





Resonant current

• Constant switching frequency operation

(fs ≈ fR), no load dependency

• Amplitude (Im) of resonant current does not depend

on the charging power PBAT of the battery

𝐼𝑚 =𝑉𝐼𝑁𝑍𝑅

= 𝑉𝐼𝑁𝐶𝑅𝐿𝑅

≅𝑉𝐵𝐴𝑇2

⋅𝐶𝑅𝐿𝑅





Charging power of the battery

• Average charging power PBAT of the battery during

one pulse period

• For partial load operation, full-cycle pulse skipping is

applied to obtain the desired charging power



Zero Current Switching (ZCS) to reduce losses

• Operation in capacitive region (fS < fR) allows for

current leading, ZCS naturally obtained

32



TS switching period

TR resonance period

T1 ZCS detection

T2 deadtime



Zero Voltage Switching (ZVS) to further reduce

losses

• Turn off S1 / turn on S2 (iZVS > 0)

• Turn off S2 / turn on S1 (iZVS < 0):

works similar

33



• Additional current source iZVS integrated to achieve ZVS

• Effects during switching of power semiconductors modeled with capacitors


𝑖ZVS

𝑖LR


Problems of the arrangement described so far

• iIN and iOUT with significant ripple

→ high filter effort to fulfill EMC requirements

• Very high current in resonant tank required:

Im > 600A to reach 150kW @ 800V

→ difficult to design LR and CR

34


© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 342021.06.21 34© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 34342021/06/21 34

𝑖ZVS

𝑖LR


Realisation of the 150kW Fast Charging Booster in the Porsche Taycan

• Multiphase converter with interleaved operation: 25kW / phase → 6 phases

• Advantages

→ lower ripple currents

→ less filter effort

→ design of LR and CR feasible

→ easy implementation of ZVS: 2 phases with 180° phase shift connected via LZVS

35


© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 352021.06.21 35© BRUSA High Performance Voltage Doubler – The Fast Charging Booster for the Porsche Taycan 35352021/06/21 35




Basics

• 2 phases with 180° phase shift

• 1 ZVS inductor is used for 2 phases

• iZVS has triangular waveform

• iZVS can provide sufficient energy to change potential

of the 4 bridge points (S1/S2, D1/D2, S3/S4, D3/D4) to

achieve ZVS

Advantages

• Less complexity

• Lower losses

• Higher power density

iZVS is small

commutation due to

ZVS inductor

all switches are turned off

to allow for ZCS and ZVS

ga

te s

ign

als

ZV

S in

du

cto

r

vo

lta

ge

, cu

rre

nt

bri

dg

e p

oin

t

vo

lta

ge

s


vPB1 vPB2

𝐃𝟏




Comparison with single phase operation

• 2 pulses instead of 1 pulse

• For same charging power: output current with

reduced ripple

• Less filter effort

Output current w/2 interleaved phases


𝐃𝟏



38



Output current

• Ripple in output current due to dead time in switching

• Average 𝑖𝑂𝑈𝑇 = 187.5𝐴, ripple Δ 𝑖𝑂𝑢𝑡 = 15.09A

• Peak current per phase 𝐼𝑚 = 110A

• Switching frequency 𝑓𝑆 = 64kHz

• Dead-time 𝑡𝑑 = 1𝜇𝑠




39



Efficiency

▪ Max. : 98.5%, @ full load: 98.3%

▪ Losses:

▪ 63% IGBTs

▪ 33% Diodes

▪ 4% others




40



• 150kW Booster • 800V/400V DC/DC

• 800V/48V DC/DC

• 800V/12V DC/DC

HV-Booster DC/DC-Converter


Electrical Boost mode Bypass mode

Vin max 435V 870V

Iin max 350A 350A

Ubat max 870V 870V

Ibat max 175A 350A

Pbat max 152kW 305kW

Power density 12kW/l 23kW/l

Mechanical Booster

Weight 14kg

Volume 13l


Conclusions and

outlook6



Conclusion and outlook


800V versus 400V Powertrain Systems

▪ The trend towards 800V systems will increase due

to the improved fast charging capabilities

▪ It will take quite some time until a sufficient coverage

with 1000V Fast Charging Systems will be available

worldwide

▪ During transitional period solutions to charge 800V

systems @ 400V fast chargers required

▪ The concept of the BRUSA Fast Charging Booster

enables a product solution with

▪ Higher efficiency

▪ Higher power density

▪ Lower cost than conventional solutions


Conclusion and outlook


Charging concepts & technology are key success

factors for eMobility

▪ Fast charging:

▪ Determined by public infrastructure

▪ Home and destination charging:

▪ Today: On-Board Chargers with 7kW…22kW,

1~ and 3~ operation

▪ Future: Demand for convenient charging like

wireless charging or automated conductive

charging

▪ BRUSA Inductive Charging System

▪ 2018 first system released to series, certified for

US/EU/CN/JP

▪ Our 2nd generation will be launched to the market

in 2022/2023



LET’S STAY IN TOUCHThank you very much for your attention


high performance voltage doubler - brusa.biz

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