automotive power shen s2

8/2/2019 Automotive Power Shen s2

1/131

5/20/02 2nd Annual Intelligent Vehicle Systems SymposiumDr. John Shen, University of Michigan-Dearborn

1

Emerging Issues in Automotive

Power Electronics

John ShenElectrical and Computer Engineering Department

University of Michigan-Dearborn

[email protected]


2/131


2

Outlines

Overview of Power Electronics Power Semiconductor Devices

Power Electronic Circuits

Automotive Case Studies

Emerging Issues


3/131


3

Overview of Power Electronics

What is power electronics? General applications

Automotive applications

Classification of power processors and converters

Interdisciplinary nature of power electronics


4/131


4

What Is Power Electronics?

Power electronics: to control and process electricalenergy efficiently.

Power electronics: an enabling technology for

computer, communication, industrial control, andautomotive technologies.


5/131


5

General Applications

Power suppliesBattery chargers

RefrigerationLighting & heating

ComputerCommunication

Consumer

Pumps/compressorMachines & toolsProcess control

Factory automation

IndustrialCommercial

HVDCStatic var comp.Renewable engr.Energy storage

Utility systems

AircarftSpace shuttle

SateliteMilitary

ArospaceMilitary

EV/HEVBattery chargers

Load controlTrains & Metro

TransportationAutomotive

Power ElectronicsApplications


6/131


6

(Source: Hitachi)


7/131


7

Voltage and Current Ranges

1 10 100 1000 10000

Voltage (Volts)

1

10

100

1000

0.1

0.01

Current(

Amperes)

Digital

Analog

Disk

Drives

Display Drives

Telecommunication

Automotive

Lighting

Motor

Control

Traction

HVDC

PowerSupplies


8/131


8

Automotive Applications

PowertrainFuel injection

IgnitionTransmission control

Cooling fan control

Electronic throttle controlAlternator rectifier

Voltage regulatorIntegrated starter generator

EV/HEV traction drive

Battery charger

Body ElectronicsHeadlamp control

HIDPower seatPower door

Power window

Windshield wiperDefrosting/defoggingClimate control

Instrumentation

Chassis & SafetyElectrical Power steering

ABSTraction controlActive suspension

Airbag ignitor

E/E ArchitectureMultiplex wiring

Active power managementTelematicsMobile media


9/131


9

Military Vehicle Applications

Hybrid electric drivetrains to improve fuel economy

Fuel cell: drivetrain and auxiliary power Next generation electrical architectures: 42V and beyond

X-by-wire applications

Mobile power generation

Central

Power

Processing

Unit

110V AC220V AC12/24/42V DC

..


10/131


10

Classification of Power Converters

AC/DC converters (rectifiers) DC/AC converters (inverters)

DC/DC converters

AC/AC converters

ConverterInput:

AC or DC

Output:

AC or DC

Control


11/131


11

Interdisciplinary Nature of PowerElectronics


12/131


12

Power Semiconductor Devices

Ideal power switches Diodes: rectifying, freewheeling, and clamping

Power MOSFET: the low voltage load driver

IGBT: the high voltage power switch

Power ICs and emerging device technologies

SiC technology

Power losses and thermal management


13/131


13

Examples of Using Power Switches

Loads: lamps, solenoids, motors, ignition coils, etc.

+ v -

i

- v +i

High-Side Switching Low-Side Switching

Load Load


14/131


14

Ideal Power Switches

Block large forward and reversevoltages when OFF (i=0).

Conduct large currents when ON (v=0).

Switch between ON and OFFinstantaneously.

Ease of control

Rugged and reliable

Low EMI during switching

i=0

+

v

-

i

+

v=0

-

ONOFF


15/131


15

Non-Ideal Characteristics:Breakdown Voltage Rating

A real switch can only block a certainamount of voltage (voltage rating) when

OFF. The switch will conduct currents if

the limit is exceeded (breakdown). Most switches can only block voltages in

one direction.

i

+

v

-

OFF


16/131


16

Non-Ideal Characteristics:Current Rating and Conduction Loss

A real switch always has some resistanceand can only conduct a certain amount of

current (current rating) when ON. The

switch will overheat if the limit isexceeded.

Conduction loss: p = i*v=i2*R

i

+

v

-

ON

R


17/131


17

Non-Ideal Characteristics:Switching Speed and Switching Loss

A real switch takes a certain amount of time toswitch between ON and OFF states (switching

time or switching speed).

Switching loss: p(t) = i(t)*v(t)

i

v

ON ONOFF

Ideal Switch

i

v

ON ONOFF

Real Switch

toff ton


18/131


18

Semiconductor Power Devices

Diode Bipolar Junction Transistor (BJT)

Power MOSFET

IGBT

GTO

Thyristor

Power ICs and SmartPower devices

SiC Devices


19/131


19

Diodes

Diode: a two-terminal uncontrollable device Automotive applications: rectifying (alternator),

clamping (transient voltage suppression), and

freewheeling (electric drivetrain inverters)

P N

+ V -

IV

I

Forward

(ON)

Reverse

(OFF)

Breakdown

ON voltage


20/131


20

Switching Characteristics

Reverse recovery (turn-off) Forward recovery (turn-on)

Fast and soft

i

Ideal diode current

Real diode current

Recovery time trr

IRM

ONOFF

Recovery charge Qrr


21/131


21

Zener Diodes

Operating in breakdown mode Used as transient voltage suppressors (TVS) to

reduce EMI or provide load dump protection.

Circuits

+

v

-


22/131


22

Power MOSFET

A three-terminal controllable device Driver (or switch) for low-voltage loads

Voltage ratings: 30-60V for 14V systems and 75-

100V for 42V systems


23/131


23

DC Characteristics

Threshold voltage Vth

Drain-source breakdown voltage V(BR)DSS

Drain-source resistance RRDSON


24/131


24


Charge and dischargecapacitors

No charge storage time


25/131


25

Safe Operating Area (SOA)


26/131


26

Avalanche (UIS) Energy Capability

The ability to survive the

harsh automotive EMIenvironment


27/131


27

MOSFET Device Structure


28/131


28

Rdson and Current Rating

Current rating is determined by the Rdson and

thermal design of the MOSFET. Larger die size=>lower Rdson @ higher cost

Trench MOSFET technology provides lower Rdson.


29/131


29

Insulated Gate Bipolar Transistor(IGBT)

Excellent power switch for HV circuits (>500V) lower conduction loss and high current capability

Medium switching speed (


30/131


30

IGBT vs. MOSFET

IGBT:

Bipolar (two carriers) Conductivity modulation

Medium speed

MOSFET:

Unipolar (single carrier) Ohmic resistance

High speed


31/131


31

DC Characteristics

Collector (C)

Emitter (E)

Gate (G)

iCE

+vCE

-+

vGE

-


32/131


32

DC Comparison: IGBT vs. MOSFET


33/131


33



34/131

5/20/02 2nd Annual Intelligent Vehicle Systems SymposiumDr. John Shen, University of Michigan-Dearborn 34

Switching Comparison:IGBT vs. MOSFET


35/131


Short Circuit Capability of IGBT

The ability to survive a short-circuit condition fora certain amount of time.

Extremely high voltage, current, and power.


36/131


Power ICs & SmartPower Devices

Power ICs or SmartPower devices integrate powerdevices with control, diagnostic, and protective

functions into a single chip or package.

Tradeoff between function integration & cost Usually limited to moderate power applications


37/131


Example: Smart High-Side Switch

(Infineon BSP752T)


38/131


Emerging Power Semiconductors

MOS-gated thyristors (MCT, MCCT, etc.) SiC technology


39/131


SiC: Electrical Properties

Wide bandgap semiconductor material

(SiC: 3-3.3eV vs. Si: 1.12 eV)

High electric breakdown field

(SiC: 1.5-4e6 V/cm vs. Si:2-8e5 V/cm)

High carrier mobility

High thermal conductivity

Specific on-resistance of a SiC device is 1/300th that of an

equivalently rated Si device Ideal for high power, high temperature, and high frequency

applications (e.g., electric drivetrains)


40/131


SiC: Materials

Many polytypes: 6H, 4H, 3C, etc. 4H-SiC for high power devices (higher electron

mobility)

50mm 4H- and 6H-SiC wafers available and75mm SiC wafer capability demonstrated.

Micropipe defect is the limiting factor

Both bulk and expitaxial SiC wafers needed


41/131

5/20/022nd Annual Intelligent Vehicle Systems Symposium

Dr. John Shen, University of Michigan-Dearborn 41

SiC: Power Device Demonstration

Diodes: 2.5-4.5V, Vf of 4V at 1000A/cm2

Power MOSFET: 550V, 25mO-cm2

Thyristor: 900V, Vf of 3.9V at 625A/cm2

SiC BJT, IGBT, low-voltage CMOS devices havealso been demonstrated


42/131

5/20/02 2nd Annual Intelligent Vehicle Systems Symposium

Dr. John Shen, University of Michigan-Dearborn

42

SiC: Technical Challenges

Materials: 75-100 mm bulk and epi wafers withlow defect density at a reasonable price

Oxide interface quality and reliability

Ion implantation processes: high temperatureimplantation and annealing

Sheet resistance and contact resistance for p-type

SiC doping Companion packaging technology


43/131



43

Analysis of Switch Power Losses:A Simplified Case

SOFFdOFFS

SONdONS

OFFSONSSWITCHING

S

ONONCONDUCTION

SWITCHINGCONDUCTIONTOTAL

ftIVP

ftIVP

PPP

T

tIVP

PPP

)(0)(

)(0)(

)()(

0

2

1

2

1

=

=

+=

=

+=


44/131



44

Interaction between the main switch andfreewheeling diode

Nonlinear waveforms

Time-varying PWM duty cycles Temperature-dependent device parameters

Analysis of Switch Power Losses:More Realistic Case


45/131



45

Thermal Management

Switch power losses heat up the devices.

Maximum junction temperature is the limiting

factor on the power handling capability of devices.

Selection of appropriate device ratings and proper

thermal design are critical steps in power

electronics design.


46/131



46

Electric Loads & Passive Components

Capacitors Inductors

Transformers

Lamps Solenoids, coils, and relays

Motors


47/131



47

Capacitors


48/131



48

Inductors


49/131



49

Transformers


50/131



50

Lamps

Conventional Halogen lamps are resistive loads. New automotive lighting technologies such as

High Intensity Discharge (HID) and LED need

special drive circuits. Challenge with 42V systems: A higher bus voltage

requires a higher filament resistance to maintain

the same power. This results in a thinner and/orlonger and less reliable filament. PWM can solve

the problem.


51/131



51

Solenoids, coils, and Relays

Solenoids, coils, and relays are inductive loads in

nature. Voltage spikes occur when the load currents are

interrupted.


52/131



52

Motors

AC DC

PMSynchronous Asynchronous

SRM

Stepper

Squirrel

Cage

3 -Induction

Hybrid

Field Winding

Wound

Rotor

DC field

winding

PM

Brushless DC

SeriesShunt

ISG

EV/HEV

regular

starters

ISG

EV/HEV

Lundell

alternator

small car

motors


53/131



53

An Electromechanical System


54/131



54

Power Electronic Converters

Overview

Steady state analysis

Pulse Width Modulation (PWM) concept

High-side, low-side, and H-bridge configurations AC/DC rectifiers

DC/DC converters

DC/AC inverters

Controls of power electronics


55/131



55

Overview of Power Converters

Power electronic circuits move through different

topologies as power semiconductor switches open

and close

Time-domain circuit analysis

Circuits

ContainingSwitches

Output

FilterNetwork

Input

FilterNetwork

LoadSource

Power Flow

Power Converter


56/131



56

Steady State Condition

In power electronic circuits, semiconductor

switches constantly change their ON or OFF

status.

A steady state condition is reached when the

circuit waveforms repeat with a time period T.

Time

T


57/131



57

Average Power and RMS Current

Instantaneous power

Average power

RMS current

Power factor cos

1

)(1

)()()(

0

2

0

==

=

=

=

RMSRMS

av

T

RMS

T

av

VI

PPF

dtiT

I

dttpT

P

titvtp


58/131



58

Steady State Analysis

Exploiting steady state conditions is extremely

useful in analyzing power electronic circuits

For capacitors:

average current = 0

For inductors:

average voltage = 0

0)(1

)()(

)(1

)()(

=>======= vtri:TA+ & TB- ON

vcontrol< vtri:TA- & TB+ ON

H-Bridge DC/DC


73/131



73

Converter:Unipolar Switching

Vcontrol> vtri:TA+ ON

-vcontrol> vtri:TB+ ON


74/131



74

DC/DC Converter Applications

Adjustable-speed DC motor drives:

electric engine fan, pinch-free power window,

smart windshield wiper, etc.

42/14V conversion

PWM lighting


75/131



75

DC/AC Inverter

AC motor drives: EPS or drivetrain

Single-phase square-wave inverter

Single-phase PWM inverter

Three-phase PWM inverter


76/131



76

Single-Phase (H-Bridge) Inverter


77/131



77

Switch Control

Valid switch combinations are those that do not

short or open the load

Only four valid switch states for H-bridge

inverters:

- TA+ & TB- ON, TA- & TB+OFF => Va=Vdc- TA- & TB+ ON, TA+ & TB- OFF => Va=-Vdc- TA+ & TB+ ON, TA- & TB- OFF => Va=0

- TA- & TB- ON, TA+ & TB+OFF => Va=0

Square-Wave


78/131



78

Square Wave

Switching


79/131



79

PWM Switching (Bipolar)

When vcontrol>vtri,TA+ & TB- ON

When vcontrol


80/131



80

When vcontrol>vtri,TA+ ON

When -vcontrol>vtri,TB+ ON

W Sw tc g

(Unipolar)


81/131



81

Three-Phase Inverter


82/131



82

PWM Switching ofThree-Phase

Inverter


83/131



83

Control of Power Electronics


84/131



84

Separation of Time Scales


85/131



85

PWM Control

PWM is the main technique in power converters

Automotive Power Electronics:


86/131



86

Case Studies

Fuel injector solenoid driver circuits

IGBT ignition coil driver circuits

Electric power steering systems

42V PowerNet Electric/Hybrid drivetrains

F l I j i S


87/131



87

Fuel Injection System

F l I j t S l id D i Ci it


88/131



88

Fuel Injector Solenoid Driver Circuit

F h li Di d f P t ti


89/131



89

Freewheeling Diodes for Protection

Common

V +

Inductive Load

MCU or

CMOS IC

PWM Generator

Free Wheeling

Diode FWD

V + SUPPLY

Common

D l L l C t C t l


90/131



90

Dual-Level Current Control

A large current passes

through the inductivesolenoid load which

quickly opens the valve

for fuel release.

A lower current is then

needed to maintain (or

hold) the fuel injectorvalve until completion.

Fast Recovery Solenoid Driver


91/131



91

Circuits

The electromagnetic energy of an inductive load

sometimes needs to be cleared quickly. A higher voltage is needed to bring the load current

to zero faster.

V = L di/dt

V + SUPPLY

Common

V + SUPPLY

Common

Fast Recovery Solenoid Driver

Ci i (C )


92/131



92

Circuits (Cont)

VDC 100-130

Current Sense

Direct In Combustion

Cylinder Fuel Injection

Solenoid

Switches:

Power Fet"s

IGBT's

1 per Cylinder

14 to 53 Volts

Boost

Converter

Hi-Side

Drive

Ignition Coil Driver Circuits

Di ib S


93/131



93

Distributor Systems


Di t ib t l S t


94/131



94

Distributorless Systems


C il Pl (COP) S t


95/131



95

Coil-on-Plug (COP) Systems

IGBT Ignition Driver Circuit


96/131



96

IGBT Ignition Driver Circuit

Primary voltage: 350-600V

Secondary voltage: 20-40KV

Inductive Switching


97/131



97

Inductive Switching

Detailed Waveforms


98/131



98

Detailed Waveforms

Electric Power Steering Systems


99/131



99

Electric Power Steering Systems

Motor

Pump

Motor Controller

Sense

I sense

hydraulic cylinderValve

Hydraulic tubes

electricmotor

Motor Controller

Angle sense

Steering wheel

Torque sense

EHPS

Electro Hydraulic Power Steering

Brushless or Induction Motordrives pump

ECU controls motor driving the

hydraulic pump.

EPS, Electric Power Steering

Or Direct-Assist Power Steering

Electric motor provides assistance

ECU controls motor driving thesteering column

EHPS and EPS


100/131



100

EHPS and EPS

GearBox

PowerStage

SteeringColumn

HydraulicPump

Current

Sense

SteeringWheel

Microcontroller

PressureSensor

WheelPosition

Angle / Torque

Motor

VehicleSpeed

PowerStage

SteeringColumn

CurrentSense

SteeringWheel

Microcontroller

WheelPosition

Angle / Torque

Motor

VehicleSpeed

GearBox

EHPS EPS

EHPS Power Electronic Circuit


101/131



101

EHPS Power Electronic CircuitPM MOTOR, SINGLE POWER TRANSISTOR

LOW-SIDE PWM DC/DC DRIVE

Supply Voltage

Sense Input

PWM

Output

+ 12V

PM

Motor

Power

Stage

PUMP

GateDrive

com.

MCU

N-FET Drain Voltage

Sense Input

+ D

G

S

POWER

RELAY

Pressure

Sensor

RESET 5V REG

LVI

COP

+12 Ignition

Osc

Vehicle

Speed

Sensor

Diagnostic

Port

8 bit Core

A/D

PWM

SCI

FWD

N-FET

EPS Power Electronic Circuits


102/131



102

EPS Power Electronic Circuits

Brushless DC or Induction

Motor Drive

Switched Reluctance

Motor Drive

42V PowerNet


103/131



103

42V PowerNet

100

1,000

10,000

100,000

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

2020

2030

Year

w/ Propulsion

wo/ Propulsion

1.8 kW

15 kW

40 kWGrowth Rates:

1920-40 6%/yr

1940-70 2%/yr

1970-90 6%/yr

Projected 1990-2030:

w/o Proplsn. 5%/yr

w/ Proplsn. 8%/yr

1900s

6V Systems

1950s

12V Systems

1970s

12V Systems

5V Electronics

1960s

12/24V

Heavy Duty

Power

Requirement(W

atts)

42V Voltage

Specification0 9 1 1 1 4 .3 2 0Ve h i c l e B u s Vo l t a g e ( 1 4 V S u p p l y )

1 6


104/131



104

Specification

0 5 1 4 1 8 2 2

M in . Op . V olt

N o m i n a l O p . V o l t

M a x . O p . V o l t

M in Ze n e r Cla m p V olt .

S e m i c o n d u c t o r Re q u i re m e n t s

0 5 4 2 5 2 5 8

M in . Op V olt

N o m i n a l O p . V o l t

M a x O p V o l t

M in Ze n e r Cla m p V olt

S e m i c o n d u c t o r Re q u i re m e n t s

Ve h i c l e B u s Vo l t a g e ( 4 2 V S u p p l y )

0 2 5 3 3 4 3 5 6

M in S t art V olt .

M in V olt . En g. OFF

M a x V o l t E n g . O N

M ax V olt C LD

5 2

0 9 2 0

M in S t art V olt .

M in . V olt En g. OFF

M a x V o l t E n g . O N

Ma x C l a m p Vo l t .

1 6

42V Electrical Architectures


105/131



105

42V Electrical Architectures

ElectronicModule

Alt

Str.

B1

Mot.

B2

C1

C2

42V

14V

Electronic

ModuleC2

Alt.C1

B1

B2

42V

14V

Str.Mot

42V Integrated Starter Generator

(ISG)


106/131



106

(ISG)

42V/14V DC/DC Converter


107/131



107

PWM

Controller42V 14V

S1

S2

Control Input

Bi-directional conversion (42V 14V)

1-2KW output power

42V Distribution Circuits


108/131



108

DC

DC

CS51022 14V

DC

DC

Low Power5V, 3.3V

DC

DC

CS5102214V

DC

DC

CS5102214V

Other 14V Loads

(including other lamps)

Right Lamps

Left Lamps

Type C Semiconductors

(ECU. Logic, Memory, etc.)

42V Loads42V

Battery

ISA

42V Multiplexing Network and

Smart Junction Box (SJB)


109/131



109

J ( J )

Electric and Hybrid Drivetrains


110/131



110

y

Bus voltages: 42-300V

Power ratings: 5-100KW

Motors: induction, BLDC, SRM

Power converters: IGBT or MOSFET PWM

inverters

Control design: P- or DSP-based vector control

Power Conversion


111/131



111

Three-Phase PWM Inverter


112/131



112

3 legs / 6 active switches

Fixed switching frequency

Variable switching duty cycle

Both frequency and amplitude of

phase voltages controllable

KEY: switching sequence of

active switches

Control of AC Motor Drives


113/131



113

Control stator voltage

amplitude and frequency

Simple implementation

Acceptable steady statecharacteristics

Poor transient response

Poor transient efficiency

Control stator voltages and

currents represented by

vectors

Accurate control for bothsteady state and transient

operations

High efficiency

Complex implementation

(DSP and sensors)

Scalar Control (V/f ) Vector Control (Field Oriented )

Advanced Vector Control for AC

Motor Drives


114/131



114

Emerging Issues in Automotive Power

Electronics


115/131



115

Power losses and efficiency

Inverter power module reliability

Novel thermal management technology

Cost reduction with better power bus regulation

EMC concerns

42V or higher voltage electrical architectures

Power Losses and Conversion Efficiency


116/131



116

Power losses of power switching devices, conversion

efficiency, and thermal management are the key designissues for electric drivetrains and other automotive

applications (e.g., EPS)

New circuit topologies: cascade or soft switching inverters

Selecting the right switching devices: a complex design

trade-off

Peak vs. normal power design dilemma (ratio as high as

10:1): load leveling approach

Reliability of Power Electronic ModulesA k l t t d ki l t i l i ti l i


117/131



117

A key element toward making electric propulsion more practical is

the development of cost-effective, high-efficiency integrated power

electronic modules.

The reliability of these power modules will be of paramount

importance for the success of various EV/HEV concepts due to the

critical safety concern for drivers/passengers, stringent quality

assurance requirements of vehicles, and extremely harsh

underhood automotive environments.

In addition, automotive electric drivetrains, due to their wide

dynamic range of operation and diverse usage profiles, will likely

impose a more stringent reliability requirement on the power

modules than any other industrial motor control applications.

Reliability and Failure Mechanisms Elevated junction temperatures (150oC max)


118/131



118

Elevated junction temperatures (150 C max)

Thermal-mechanical stress and fatigue: wire bond lift-off, solder

joint cracks, Si chip cracks, etc.

Vibration

Contamination

Defects

Si Chip Si Chip

Cu

Baseplate

Direct Bond Copper Substrate

Solder Joints

Wirebond Connector

Case

Research in Power Module Reliability


119/131



119

Improving Understanding on Module Reliability Requirements

Developing Realistic Reliability Testing Standards and LifetimeProjection Models

Enhancing System Diagnostic Capability with Early Warning

Fault Detection (embedded diagnostics/prognostics for power

electronics)

Drive Cycle &

Usage

Analysis

Inverter

Module

Power Loss

Analysis

Inverter

Module

Thermal

Analysis

Inverter

Module

Stress

Analysis

Drive Cycle and Power Loss


120/131



120

0 1000 2000 3000 4000 5000 6000 700040

60

80

100

120

140

160

180

200

220

240 ISG P owe r Los s Trace

Time (s)

PowerLoss(W)

0 1000 2000 3000 4000 5000 6000 70000

500

1000

1500

2000

2500

3000

Time (s )

RPM

CITYNEW Drive Cycle Speed Trace

Novel Thermal Management


121/131



121

Removal of heat from power electronics is the limiting

factor for cost, compactness, and reliability. The disparity between the peak load capability and average

load operation of automotive power electronics severely

lowers the hardware utilization efficiency and sets a limit

on cost reduction and reliability enhancement.

Peak power load is typically several times higher than

average power load, but only lasts for a short period of

time ranging from a few tens of milliseconds to a fewseconds.

Phase Change Thermal Management Transitions between solid,


122/131



122

liquid, and gaseous phases

typically involve large

amounts of energy comparedto the specific heat. For

example, one gram of water

absorbs merely 4.18 joules of

heat to increase its

temperature by 1o

C, butamazingly 2260 joules of heat

when vaporized even without

any change in temperature.

Phase change materials can be

used as passive heatmoderators in power

electronic packages.

Silicon

Case

Heat Sink

Conventional Power Electronics Module

Silicon Phase Change

Heat Moderator

Heat Sink

Proposed Power Electronics Module

Case

Time

J

unctionTemperature

Peak Load Average Load

Conventional

Power Module

Phase Change

Power Module

Improve Power Bus Voltage

Regulation to Reduce Cost ofAutomotive Power Electronics


123/131



123

0 20 40 60 80 100 1200

0.5

1

1.5

2

2.5

3

3.5

4

Breakdown Voltage (Volts)

SpecificOn-Res

istance(mohm-cm2)

Theoretical limit of Silicon

Dis crete

P ower IC

15 20 25 30 35 40 45 50 55 60 65

1

1.5

2

2.5

3

DC VOLTGAE RATING (V)

NORMA

LIZEDCOST

Power MOSFET Ron vs Voltage Rating Capacitor Cost vs Voltage Rating

Automotive Power Systems


124/131



124

Automotive

Po w er

Sy stems

Battery

Voltage

Nominal

Operating

Voltage

Maximum

Operating

Voltage

Maximum

Dynamic

Over-

voltage

Power

Electronics

Voltage

Rating

12V

Car/Light

Truck

12 V 14V 24V

(Jump

Start)

_ 60-40V

24V

Heavy

Truck

24 V 28V 34V _ 80-60V

42V

Po w e rNe t

36 V 42V 50V 58V

(Load

Dump)

100-75V

Transients in Automotive

Environments


125/131



125

Time

Duration

Caus e Vo ltag e

Amplitude

Energy

Level

Frequency

o fOccurrence

200ms to

400ms

Load dump

(disconnection of

battery while at

high charging)

10J Infre que nt

Steady

State

Fa ile d voltage

regulator

18V _ Infre que nt


126/131



126

NORMAL BUS VOLTAGE

TVS CLAMPING VOLTAGE

VOLTAGE

RATING

OF POWER

ELECTRONICS

6-24V 6-24V

4-40V

0-60V

24-27V

Existing Voltage

Rating

Proposed Voltage

Rating

NORMAL BUS VOLTAGE

TVS CLAMPING VOLTAGE

VOLTAGE

RATING

OF POWER

ELECTRONICS

10-34V 10-34V

4-60V

0-60V

34-37V

Existing Voltage

Rating

Proposed Voltage

Rating

Introduction of A New Class of

Transient Voltage Suppressors:MOSTVS


127/131



127

Much less variations in clamping voltage than conventional Zener

diodes or MOVs over a wide range of current and temperature.

Proven power MOSFET technology

Provide cost benefits in 12V, 24V, 42V or higher voltage systems

BTB Poly DiodesD

S

Rg

G

Module 1 Module N

Central Suppressor Distributed Suppressor

DC Power Bus

Electromagnetic Compatibility

Concerns


128/131



128

EMC compliance is a major challenge for automotivepower electronic systems

Large common-mode inverter currents due to couplingpaths to ground through the motor and housing

Large di/dtand dv/dt, while minimizing switching losses,

generate broadband radiated and conducted emissions. RF characteristics of power semiconductor

devices(especially bipolar types) are neither fullyinvestigated nor considered in the EMC consideration.

Conducted immunity concerns: load dump, negativetransients, etc.

Electrical/Electronic Architectures


129/131



129

Electrical Architectures: Power

Generation and Distribution


130/131



130

Active power management: multiple power sources, loads,

energy storage elements, multiplexing, etc. System stability may become a major concern.

Arc fault detection is critical for 42V or higher voltage

electrical distribution systems:

Distributed current sensor network and DSP to detect

arc fault signatures

Arc fault detection should be an integral part of

electrical architecture design rather than using add-onapproach

Summary


131/131



131

Power electronics will become more pervasive in

automotive systems. Device and circuit technology advances need to be

made to meet performance, reliability, and cost

targets. Many critical technical challenges and barriers

need to be overcome.

automotive power shen s2

Documents