October 7, 2008 Solutions for Electrical Traction Motor Drive · • Driving hybrid – driving...

TM

Freescale Semiconductor Proprietary Information. Freescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2008.

Solutions for Electrical Traction Motor Drive

October 7, 2008

Roman FilkaSystems and Applications Engineer

FA101

TMFreescale Semiconductor Proprietary Information. Freescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2008. 2

Session Content

►Hybrid EV powertrain• Typical hybrid system• Driving hybrid – driving modes

►Freescale MCU solutions• Centralized (multi-axis) control• Distributed (single-axis) control

►Electric motor control• 3-phase motor control• Achieving Deterministic and Precise Control

►Freescale application solutions• Sensorless PM AC motor control

►Motor control on Freescale Web site


Please Ask Questions

► Do you have something in mind?

► Do I need to be more clear?

► Do not hesitate to interrupt.

► Do not hesitate to ask.

► This session is long!

► Ask when you have a question in mind.

?


Typical Hybrid System

• High efficiency gas engine• Planetary gear power split device

AC synchronous generator• High voltage AC-DC inverter• Nickel-metal hydride battery• Permanent magnet AC motor

Battery

Inverter

Motor

Drive wheels

Generator

Engine

Power split device

Power circuit


Typical Hybrid System

• High efficiency gas engine• Planetary gear power split

device AC synchronous generator

• High voltage AC-DC inverter• Nickel-metal hydride battery• Permanent magnet AC motor

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Electric power

Drive power

Power circuit


Hybrid Powertrain Roadmap

Engine Start/Stop

Regenerative Braking

Engine Assist

Full Electric Drive

MicroHybrid

MildHybrid

FullHybrid

SeriesHybrid

Hyb

rid F

unct

ions

2-10k12-42V

10-20k42-100V

20-80k100-300V

80-110k300-600V

Parallel Hybrids


Driving Hybrid

► Regenerative Braking. The electric motor applies resistance to the drivetrain causing the wheels to slow down. In return, the energy from the wheels turns the motor, which functions as a generator, converting energy normally wasted during coasting and braking into electricity, which is stored in a battery until needed by the electric motor.► Electric Motor Drive/Assist. The electric motor provides additional power to assist the engine in accelerating, passing, or hill climbing. This allows a smaller, more efficient engine to be used. In some vehicles, the motor alone provides power for low-speed driving conditions where internal combustion engines are least efficient.

Source: TOYOTA, Hybrid Synergy Drive, Information Portal

Hybrid strength


Hybrid Driving Modes

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Power circuit

Low Speed Normal Driving

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Power circuit

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Power circuit

Sudden Acceleration


Hybrid Driving Modes

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Power circuit

Battery

Inverter

Motor

Drive Wheels

Generator

Engine

Reduction gear

Power split

device

Power circuit

Battery Charging Regeneration


Hybrid Vehicle

Generator / StarterField Oriented Control

Battery ManagementCharging mgmnt

(DC/DC conversion control)Lifetime monitoring

Traction MotorField Oriented Control

AC Induction MotorSensorless control

Engine ControlKnock Detect (FFT)Control of Engine

SupervisorEnergy Flow management

Source: www.ford.com


Problem Statements

► Complex distributed system• There is one MCU dedicated to synchronization of multiple controllers including the

transmission controller• High bandwidth communication availability (5 ms response window)

► Motor control• Precise, fast and deterministic control timing• CPU bandwidth limitation which pushes the solution to one micro per motor

controlled; high bandwidth is emphasized more than memory. This may cause the need for a horsepower part with low memory requirements.

• Need optimized and flexible PWM output control for 3-phase motor control linked with fast and effective analogue acquisition

► System costs• Multiple controllers and sensors• Microprocessor needed for DC/DC converter also needed for control of voltage

conversion

TM


Freescale MCU Solution


Freescale 32-bit MCU Solutions — Agenda

►Centralized (Multi-axis) Control• System concept based on devices with eTPU• What is an eTPU?• eTPU operation in motor control application• eTPU performance in motor control application

►Distributed (Single axis) Control• Introduction of 32-bit MCU dedicated to motor control• Motor control peripherals

– PWM — unique all edge control– Timer– ADC– Cross triggering unit (CTU) – unique way to offload CPU


Centralized Control

► Centralized control can be based on the powerful CPU supported by the motor control “co-processors”, called eTPU.

Battery

Generator

Engine

Power circuit

Motor

Inverter

ECU

MCU

MCU

eTPU

eTPU

CPU


The enhanced time processor unit is a programmable I/O controller with its own core and memory system, allowing it to perform complex timing and I/O management independently of the CPU. The eTPU is essentially a microcontroller all by itself! – motor control coprocessor

4

Timer ChannelsScheduler

Micro-engine

Execution Unit

Fetch and Decode

MDU

Host Interface

IPI

Code Memory (up to 64k)IPI

Debug Interface

Service request

Channel

Channel 0Channel 1Channel 2

Channel 31

Control

Control

Code

Data

System Configuration

Channel Control

Development and Test

Data Memory (up to 8k)

Debug

Control and data

TCR2 / Angle clock

What is an eTPU?

TCR1


Centralized Control—System Concept

► eTPU drives a motor independently of the CPU► eQADC (triggered by eTPU) samples analog quantities► eDMA transfers data between eQADC and eTPU► CPU only sets required quantity value (speed or torque)► CPU can handle higher level tasks

MotorDrive

enable/disablePWM signals

CPU HardwareDC-Bus

Us e

r In t

erfa

c e PWM Signals

DC-Bus Voltage

MotorPowerStage

eTPU

Sensor Signals

eQADCPhase Currents

eDMA

two parallel

conversions12-bit

Application State

Machine


eTPU Operation

► PWM signals generation► Shaft encoder signals processing► eQADC trigger signal generation

► PMSM/ACIMVC vector control loop► Speed-closed loop control► DC-bus break signal generation

QD

ASAC

SCrequiredspeed

requiredtorque

position difference& time difference

ADC Trigger

Shaft Encoder

DC-bus voltage

CPU eTPU Hardware

PMSMVC/ACIMVC PWMMAC

alphaduty-cycles

MotorInverter

PWMFbeta

phase_a_currentphase_b_currentphase_c_current

requiredtorque

actualspeed

QD_Index

position counter

BC DC-BusBreak

DC-bus voltagealpha

beta

DC

-Bus

Rip

ple

Elim

inat

ionu_alpha

u_beta

Inve

rse

Par

kTr

ansf

orm

u_q_lin

u_d_lin

Dec

oupl

ing

i_alpha

i_betaFlux

M

odel

sin

cos

i_q

u_q

u_d

i_d_required

i_d

Cla

rke

Tran

sfor

m

i_a

i_c

i_q_requiredPI

i_d

i_q

u_dc_busACIMVC

PI

i_b

omega_actual

DQ

Es

tabl

ishm

ent

i_alpha

i_beta

u_alpha

u_betapsi_r_alpha

psi_r_betacos

sin

omega_field

omega_field

Circ

leLi

mita

tion


Applications based on Motor Control eTPU Library

AC MotorsDC Motors

Stepper MotorsBLDC with QD Speed & Current Loop

PMSM Speed Vector ControlBLDC with QD Speed Loop

PMSM Torque Vector ControlBLDC with QD Open Loop

ACIM Speed Vector ControlBLDC with HD Speed & Current Loop

ACIM Torque Vector ControlBLDC with HD Speed Loop

ACIM V/Hz Speed Loop with SVM DriveBLCD with HD Open Loop

ACIM V/Hz Speed Loop with Sine Wave DriveDC Speed & Current Loop

ACIM V/Hz Open Loop with SVM DriveDC Speed Loop with HD

ACIM V/Hz Open Loop with Sine Wave DriveDC Open Loop

Motor Control Functions work together to drive the following motors:


eTPU Performance

PMSM Vector Control ACIM Vector ControlMCF5235 (simplified) MPC5553/4 MPC5553/4

CPU/eTPU Clock 150 MHz/75 MHz 128 MHz 128 MHz

eTPU Engine Time Load

68.7% @ 10 RPM 45.6% @ 10 RPM 53.1% @ 10 RPMaverage

76.8% @ 1000 RPM 49.9% @ 1000 RPM 61.8% @ 1000 RPM

78.6% @ 10 RPM 50.3% @ 10 RPM 58.8% @ 10 RPMpeak

84.8% @ 10000 RPM 54.6% @ 1000 RPM 67.5% @ 1000 RPM

eTPU Memory Usage

Code RAM 6088 bytes 7508 bytes 8212 bytes

Data RAM 1024 bytes 1000 bytes 1072 bytes

Application ParametersPWM frequency: 20 kHz

Vector control update frequency: 20 kHz

Speed controller update frequency: 1 kHz

Shaft Encoder - increments per revolution: 4096


► eTPU Function Library and API

► eTPU Applications and Demonstrations

► eTPU Libraries Installation and Integration Guide

► eTPU Graphical Configuration Tool

► Links eTPU Compiler and Simulator Tools

► Link to eTPU VirtuaLab — Web interface to live demo

► Information on Trainings and Courses

► eTPU Documentation

eTPU Product Summary Web Pagehttp://www.freescale.com/etpu

Where Can I Learn More?

http://www.freescale.com/etpu


Distributed Control

► Distributed control is based on micro-controllers with dedicated motor control peripherals such as 6-ch. PWM, position sensor decoders, etc.

Battery

Generator

Engine

Power circuit

Motor

Inverter

ECU

MCU1

MCU2

FlexRayCAN

MCU

PWMCPUTimer

ADC

MCU1


MPC5604P(Execution)

Power Architecture® Core• Up to 64 MHz e200 zen0h core

Memory•512 KB Program Flash with ECC•4 x 16 KB DataFlash® with ECC•40 KB SRAM with ECC

I/O•1 x High speed FlexCAN with 32 Message Buffers (MB)•1 x Safety port (can be used as additional FlexCAN – 32 MB)•1 x FlexRay Dual Channel with 32 MB•2 x LinFlex•4 x DSPI (4 independent chip selects each)•1 x FlexPWM (4 channels with 4 fault inputs)•1 x eTimer (6 channels incl. quad decode)•1 x eTimer (6 channels for general purpose)•2 x ADC

•2 x 12 ch.(4 shared channels), 10-bit, conversion time 700 nsec ( 2x 6 ch., 4shared on 100-pin package)

•1 x CTU triggering unit: 8 events

System•2 x PLL (one FM-PLL, one for FlexRay™) •16-ch. eDMA•Fault collection unit•16 MHz internal RC OSC•Junction temperature sensor•JTAG (2 pin or 5 pin) / Nexus Class 2+•3.3V single supply (5V mask option) with external ballast transistor•100- and 144-pin thin quad flat pack (TQFP)

I/OBridge SRAM

e200CoreVReg

Com

mun

icat

ions

I/O S

yste

m

Crossbar Slaves

Crossbar Masters

2A

DC

Nexus

JTAG

Debug

PROGRAMFlash

1 eFlexC

AN

eDMA VLE

Boot AssistModule (BAM)

Osc/PLL

CROSSBAR SWITCH

System Integration

FlexRay™Controller

FlexPW

M

DATAFlash

2LIN

Flex

2eTim

er

4 x DSPI

Safety

CTU

Interrupt Controller


Key Highlights► Feature set specifically addressing electric motor control applications

• Timer resolution and functions• PWM channel number and function • ADC

► Safety focus• Peripheral protection through access control• Core test capability• Flash and SRAM memories have error code correction ( ECC )• FlexRay™ networking

► Software ecosystem• Model based tools development• AUTOSAR• Optimized libraries for motor control and signal processing

► Zen 32-bit Power Architecture covers a complete range of performance and cost

• easy migration as requirements grow• Signal processing engine (on Z3 and above) for fast signal processing

► Proven eSys architecture used in most of the world’s powertrain control products


Boot Assist Module

NexusIEEE -ISTO

5001-2003Interrupt Controller

Crossbar Switch

I/OBridge SIU 512K

FLASH40K

SRAM

JTAGC -JTAGPowerPC™

e200z0

VLE

Vreg3.3 to 1.2VExt NPN

FMPL

4-40 MHz X -OSC

16 MHz RC-OSC

16 Ch.eDMA

FlexRay

4+1 Ch.PIT

Junctiontemp.Sensor

dSP

IdS

PI

eSC

I

FlexCA

N

Safety P.

dSP

I

PWM

Timer

Timer S&H S&H

Mux Mux

EEE

10bitI/F

10bitI/F eS

CI

MPC560xP Functional Safety HighlightsPower Architecture® Core:• Core self test planned

Vreg• Spreads power losses over PCB• Allows high temp operation

RC OSC• Provides seperate clock to system watchdog

FlexRay Option• 2-channel w/32 MSG buffers,

10 Mbps

Safety Port• Allows CRC signed

communication to slave MCU (if needed)

• May be used as second CAN

RAM• Provides ECC support in HW• Offers higher safety than SW

signature at no speed constraint

Flash + Data Block• Provides ECC for both

program Flash and Data Flash

Fault Collection Unit• Detects when errors have occurred and the source and sets a flag•Independant of software operation

There are many different features in MPC560xP that introduce redundancy and enhance functional safety


MC Peripherals System Diagram

MCU

CTU

eTimer(Pos Counter)

PWM Reload

Timer/ Pos. decoder compare

External Signal

External Trigger

Trig

ger G

ener

ator

eTimer

flexPWM

Sch

edul

er

ADC Cmd

ADC Trig & Ackw

RealPWMs

PWMs

PWM Triggers

Real PWMs ADC Inputs

AD

C1

SHA

RED

AD

C2


Timer Module:• DSC based• Six Ch IC/OC• Double buffered registers for

detecting two edges in a row• eDMA supported• Integrated quad decoder support• 2 x BUS frequency high resolution

MCU

CTU

eTimer(Pos Counter)

PWM Reload

Timer/ Pos. decoder compare

External Signal

External Trigger

Trig

ger G

ener

ator

eTimer

flexPWM

Sch

edul

er

ADC Cmd

ADC Trig & Ackw

RealPWM’s

PWM’s

PWM Triggers

Real PWM’sADC Inputs

AD

C 1

SHAR

ED

AD

C 2

2x ADC• Up to 24channels, with 4 shared. • 10-bit• 700 nsec conversion time• Limit checking & zero crossing detect

Electric Motor Control Peripherals

FlexPWM• Based on DSC PWM• Optimized for 3ph motor control• One „extra“ pair of PWM integrated• Includes dead time insertion, fault channels,

center/edge alignment, Distortion correction, …

• Register protections• Double buffered registers• eDMA supported• 2 x BUS frequency high resolution

Cross Triggering Unit• Allows mcTIM, PWM, ATD

to be synchronized• Automatic ADC & eTimer acquisitions • No CPU intervention during the control

cycle

PWM0 Ch0PWM0 Ch1

PWM1 Ch0PWM1 Ch1

PWM2 Ch0PWM2 Ch1

PWM3 Ch0PWM3 Ch1

Con

trol

M

M

DC/DC

8

2

6

11 4 11

10bit

S&HMUX

I/F10bit

S&HMUX

I/F

11


Motor Control PWM Peripheral Module

► Main Features► 4 Submodules, each with complementary PWM generation, Isense

IC/OC and fault input

► 16 bits of resolution for center, edge aligned, and asymmetricalPWMs

► PWM outputs can operate as complimentary pairs or independent channels

► Independent control of both edges of each PWM output

► Independently programmable PWM output polarity

► Separate dead time for rising and falling edges

► Each complementary pair can operate with its own PWM frequency and deadtime values

► All outputs can be programmed to change simultaneously via a "Force Out" event

► Double buffered PWM registers• Integral reload rates from 1 to 16• Half cycle reload capability

► Safety► Write protection for critical registers

► Fault inputs can be assigned to control multiple PWM outputs

► Programmable filters for fault inputs

PWM0 Ch0

Con

trol

PWM0 Ch1

PWM1 Ch0

PWM1 Ch1

PWM2 Ch0

PWM2 Ch1

PWM3 Ch0

PWM3 Ch1

Faults

Internal triggers

Complementary Pairs PWM Modes

Independent ChannelPWM Modes

auX

auX

auX

auX

• Permanent magnet synchronous motor (PMSM, PMAC) • Brushless DC motor (BLDC)• Brush DC motor (BDC)• AC induction motor (ACIM) • Switched reluctance motor (SRM) • Variable reluctance motor (VRM) • Stepper motors• DC/DC converters

CMP1CMP2Independent

Edge Control


Quasi-Centre Aligned PWM (Full Resolution) – Normal Polarity

PWM output

0

-4

34

-3

Case A0%

Case B100%

Case A0%

Case B100%

Case C62.5%

ValONValOFF

INIT

Val0

• Case A• Duty cycle – 0%

General– x% = 0%– ValON = 0– ValOFF = 0

Example– MOD = 8– x% = 0– INIT = -4– Val0 = INIT + MOD – 1 = -(INIT) -1 = 3– TMP = MOD/2 * x% = 0– ValON = -round(TMP) = 0– ValOFF = truncate(TMP) = 0

• Case B• Duty cycle – 100%

General– x% =100%– ValON <= INIT– ValOFF >= -(ValON) = -(INIT) > Val0

Example– MOD = 8– x% = 100% – INIT = -4– Val0 = INIT + MOD – 1 = -(INIT) -1 = 3– TMP = MOD/2 * x% = 4– ValON = -round(TMP) = -4– ValOFF = truncate(TMP) = 4

• Case C• Duty cycle – <0%,100%>

General– x% = <0%,100%>– TMP = MOD/2 * x% – ValON = -round(TMP– ValOFF = truncate(TMP)

Example– MOD = 8– x% = 62.5% – INIT = -4– Val0 = INIT + MOD – 1 = -(INIT) -1 = 3– TMP = MOD/2 * x% = 2.5– ValON = -round(TMP) = -3– ValOFF = truncate(TMP) = 2


Other PWM Paterns — Example

►3-ph PWMs can be divided into:

• Standard – center aligned

• Two active vectors – left aligned

• Three active vectors – sequential

• Two active vectors – centered

• Three active vectors – center aligned (double switching)

60° - 120° 240° - 300°

120° - 180°60° - 120°

0° - 60° 60° - 120°


Motor Control eTimer Peripheral Module

► Main Features► Six 16-bit general purpose up/down timer/counter per module

► Powerful multiplexer between external pins and internal signals for external triggers

► Individual channel capability:• Input capture trigger• Output compare• Many counting modes (gating; triggered; one-shot)• Separate prescaler for each counter• Selectable clock source• Rotation direction flag (Quad decoder mode)

Sec.Input

PRIMARY

SECONDARY

PRESCALER

MUX

STATUS & CONTROL

DMA IF

COUNTER

TMRLOAD TMRHOLD

Edge Detect.

CAPTURE CAPTURE

CAP Buf.1 CAP Buf.1

TMRCMP1 TMRCMP2

CMPLD1 CMPLD2

COMP. COMP.

MUX OFLAG

OutputPrim.Input

CONTROL

OUTPUT

DATA BUS

Peripheral Clock

WD Count

UP/DNOutput Disable

OTHER CTNTRS

eTimer Channel

► Dual action capability per channel• PWM measurement 0% to 100%

► Quadrature decoder• rotor position• rotor zero speed detection (position watchdog)

► ADC trigger can also trigger input capture for rotor position measurement (ex: sin/cos sensor)

► Cascade able for higher precision (32 bits)


IC 1

IC1IC2

Counter

forward forwardjitter jitterbackward

PRESCALER 16-BIT

Trigger/ClockController

Input Capture

ARR16 bit counter

Encoder Interface

IC 2

output trigger

Output Compare

Encoder Index

eTimer — Encoder Interface Mode

► The counter is clocked by each valid transition on IC 1 or IC 2 by incremental encoder

► Depending on the sequence the counter counts, automatically, up or down

► The Output of Encoder Interface can be connected to Encoder Index to reset the counter on zero position detection

► The timer can provide information on encoded position

► To obtain dynamic information (speed, acceleration, deceleration) by measuring the periods between two encoder events using a second timer


Encoder Interface Mode — Safety

► Position WATCHDOG Timer/Counter

► Two successive counts indicate proper operation and will reset the timer.

► The timeout value is programmable. When a timeout occurs, an interrupt to the processor can be generated.

► This timer is separate from the watchdog timer in the COP module.

PHASE A

PHASE B

+/-1

PositionCounter

Incr. Encoder

What happens when PHASE A is cut off ?

Normal Operation

Operation at phase cut off

Pos. WatchdogInt. Request

Watchdog timeout

ISR

+/-1 counts of the Position Counter do not reset the Watchdog timer!

The Watchdog can detect the encoder signal line cut off!


► Main Features

► 2 Independent units• <=12channels on ADC1, <=12 channels on ADC2, • 4 channels shared on ADC1 and ADC2

► 4 shared signals for motor control acquisitions• 3 for phase currents• 1 for other acquisitions

► 760 ns conversion time, including 125 ns sampling time

► 10-bit resolution (+/- 2LSB; target +/-1,5LSB)

► Single sample and hold per ADC• Dual sample through ADC cross triggering

► Separate sampling and conversionclock pre-scalers

Motor Control ADC Peripheral ModuleADC Unit

►ADC_INTERRUPTS

ADC data registers

►D15►D14►.►.►.

►D1►D0

SUCCESSIVE APPROXIMATION A/D CONVERTER

SAMPLESAMPLE

& &

HOLDHOLD

10 bit10 bit

ConvertorConvertor

AIN0

AIN1

AIN15

..

..

..

ANALOG MUX

►ADC_CONTROLTrigger Event for

conversion

Trigger event for injected conversion

END OF CONVERSION

END OF INJECTION

THRESHOLD VIOLATION

INTERRUPTS

Results FIFOs

►Analogwatchdog

SUCCESSIVE APPROXIMATION A/D CONVERTER

SAMPLESAMPLE

& &

HOLDHOLD

10 bit10 bit

ConvertorConvertor

AIN0

AIN1

AIN15

..

..

..

ANALOG MUX

10 4 10

12bit

S&HMUX

I/F12bit

S&HMUX

I/F


Motor Control Cross Triggering Unit

► Main Features

► Two modes of operation:• Sequential mode• Triggered mode

► Schedule acquisition of the state variables (ADC, position counter, PWM duty cycle decoder) with respect to PWM cycle

► ADC commands stored in ADC lists

► Support for over-sampling

► Triggers activate an ADC list• ADC commands can be static• Triggers are changed according to space

vector location

► Trigger generation, ADC commands and ADC lists are double-buffered

► Manages both ADCs

► No real time involvement of CPU

► Compliant with ISO26262 for reduction of CPU interrupts

► DMA support

CTU

Trigger GeneratorSubunit

eTimer1

External signal

SchedulerSubunit

PWM triggersodd

Real PWM’s/IsenseX

Trigger0..7

eTimer2/ Pos. decoder

compare

PWM reload

2 x CLK

ADC Command Bus

External trigger

Presc.

Master Reload

eTimer1

eTimer2/ Pos. decoder compare

PWM triggerseven

Trigger


ADC Commands► ADCs must be in CTU control mode

► 16 channels for each ADC (12 + 4 shared channels)

► Commands List of 24 commands

► Commands List registers are double-buffered

► Single conversion mode or dual conversion mode

► The result of each conversion, in both modes, can be stored in one of the 4 FIFOs

► The interrupt request bit is used as an interrupt request to the CPU when ADC will complete the command

► The commands in the list will allow to have control on:• channel A number: number of ADC channel to sample from ADC unit A (4

bits)• channel B number: number of ADC channel to sample from ADC unit B (4

bits)• FIFO selection bits for the ADC unit A/B (2 bits)• Conversion Mode selection bit• first command bit (only for CTU internal use)• interrupt request bit

► 1 trigger from CTU initiate an ADC command list; this command list can require several ADC acquisitions

Conversions only triggered by CTU

ADCch0...chN...ch23

CTUChannel ConversionCommand

Result FIFOs

CPU/eDMA

Memory

eTimer,FlexPWM


Use Case for Cross Triggering Unit No.1

t1 t2

t1’ t2’

pwm a

pwm b

pwm c

DC-bus current

PositionDC bus voltage

Calibration

Position

DC bus voltage

Calibration


Internal counter

Desired PWM

Use Case for Cross Triggering Unit No.2

Overall delay: ~0.4 ÷ 6 us

ADC trigger output event

ADC clock sync. ADC MUX selection S&H

ADC Sample

Trigger advancement to compensate ADC delays

ADC delays

Low pass filter delay + Topto: ~1usReal feedback signal

at ADC pin


Motor Control Peripheral

► Freescale motor control peripherals are well suited to handle various PWM patterns and ADC sampling schemes including very complex ones.

► Effective and versatile cycle-by-cycle control is possible while keeping SW driver load at minimum.

► Cross triggering unit (CTU) allows for two modes of operation (relative trigger timing to PWM cycle or to PWM edges); thus, you can select the most static mode with minimum CPU or SW load.

► In case of static pattern (e.g., PWM type, CTU trigger timing, ADC sampling scheme) whole operation is fully automatic with zero CPU or SW involvement.


In Summary►Power Architecture upward compatible roadmap

• Scalable performance Z0 to Z7►Reliable supply

• Dual source — Single architecture, separate manufacturing and distribution • Competitive sales and support

►Strong electric motor control• Timer resolution and functions• PWM channel number and function • ADC

►Next Geneneration safety approach• Core fault detection Lockstep and core self test• Peripheral protection through access control• Flash and SRAM memories have error code correction ( ECC )• FlexRay™ communications networking

►Software ecosystem• Model based tools development• AUTOSAR• Optimized libraries for motor control and signal processing

►Proven eSys Aachitecture used in most of the world’s powertraincontrol products

TM


AC Motor Control


►Typical representation with six switch configuration

Inverter Topology

Typical circuit configuration used to control a 3-ph motor are the inverter is shown. Six power-MOSFET or insulated-gate bipolar transistor (IGBT) switches are used in the inverter.

Motor

A

B

C

Current Feedback

Position Feedback Resolver or Encoder Type

GateDriver

with Isolation

ECU


Fast and Precise Control — FOC

Outer Loop (slower) ~ 1Outer Loop (slower) ~ 1--5ms5ms

Inner Loop (faster) ~100Inner Loop (faster) ~100μμss


Torque Production Principle

► Electromagnetic torque production by the stator magnetic flux and magnet flux space vectors

γ

γsin⋅Ψ×Ψ⋅=Ψ×Ψ⋅= SRSRe ccT

°=→ 90)max( γeT

γγ


DC Motor Principle

► The stator of a permanent magnet DC motor is composed of two or more permanent magnet pole pieces.

► The rotor is composed of windings connected to a mechanical commutator, which mechanically ensures the angle between wire current and magnetic field ~ 90°.

SN

current

rotation

current

commutator

“Mechanical” FOC

mot

ion


Creation of Rotating Magnetic Field

► The space-vectors can be defined for all motor quantities.

0

π 2π

is

A

B

C

3-ph currents/MMF

A B C

oo 2401200 jC

jB

jAs eieieii ++=

1

-1


Transformation to 2-ph Stationary Frame

3-ph quantities

0

π 2π

β

α

0

π 2π

Stationary2-ph quantities

1

-1

1.5

-1.5

is

3-ph currents/MMF

A B C

α β

o900 jβ

jαs eieii +=


Transformation to 2-ph Synchronous Frame

► Position and amplitude of the stator flux/current vector is fully controlled by two DC values

is

α

β

0

π 2π

Stationary2-ph quantities

1

-1

0

π 2π

Rotating2-ph quantities

1

-1

id

iq

α β

d q

TMFreescale Semiconductor Proprietary Information. Freescale™ and the Freescale logo are trademarksof Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2008.

Transformation to 2-ph Synchronous Frame

► Position and amplitude of the stator flux/current vector is fully controlled by two DC values

is

α

β

0

π 2π

Stationary2ph quantities

1

-1

0

π 2π

Rotating2ph quantities

1

-1

iq

α β

d q


FOC Transformation Sequencing

Phase APhase BPhase C

α

β

Phase APhase BPhase C

d

q

d

q

α

β3-Phase

to2-Phase

Stationaryto

RotatingSVM

3-PhaseSystem

2-PhaseSystem

3-PhaseSystem

AC

Rotatingto

Stationary

ACDCC

ontr

olPr

oces

s

Stationary Reference Frame Stationary Reference FrameRotating Reference Frame

From measurementFrom measurement ??


► Sample the A/D on at least 2 of the phase currents simultaneously and read motor position.

► The A/D sample is performed on the same point during the PWM cycle (ex. midpoint of off time).

Deterministic Control

MotorControl(50 us)

PWMPeriod(50 us)

Current Ripple Profile

Max 0.5 us delay b/t successive A/D

sample 50us

Mid-Point of PWM Off Time

A/D Conversion of Motor Currents (~1us)

Motor Control (FOC) Time (~10us)

A/D Conversion always done at same point of

profile

Read Motor Position


A/D Converter-PWM Synchronization Benefits► ADC sampling helps to filtering the measured current – anti-aliasing► Noise free ADC sampling when the power switch is not acting► ADC sample is taken when shunt resistor signal (information) is available

PWM Period

PWM topPWM Bottom

Phase Current

Sampled and Average Currents

Shunt ResistorSignals

A/D

calc.

New PWM Parameters Calculation with Half-cycle Reload

TM


Freescale Application SolutionsSensorless PM AC Motor Control


Sensorless Control Basics

► What does it mean?• Controlling of electric motors without position/speed sensors• Utilizes motor phase voltage and current sensors• Uses models and algorithms to estimate the state variables (e.g.,

speed, mag. flux, resistance …)

M

Motorola

Dave’sControlCenter

Supply

Position/speedsensor

Ib

Ic


Electric Motor Type Classification

ELECTRIC MOTORS

AC DC

SYNCHRONOUSASYNCHRONOUS

BrushlessInduction Reluctance StepperSinusoidal

Permanent Magnet

Wound Field

Surface PM

Interior PM

• Stator same• Difference in rotor construction

If properly controlled• Provides constant torque• Low torque ripple

SR

VARIABLE RELUCTANCE

TMFreescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2007.

Sensorless Control of PM Motors

►Classifications of Used Sensorless Algorithms• Utilization of Magnetic Saliency

rotor position detected by tracking magnetic saliencycarrier signal superimposed to main voltage excitation

• Calculating an Appropriate Motor Modelproper motor parameters, voltage & current requiredissue at zero and low speed estimation

– measured current low, distortion by inverter non-idealities– parameter deviation becomes significant with lowering speed

• Combination of two sensorless algorithmscovering the entire speed range


IPMSM Saliency Identification

►HF Impedance Measurement• Verification of motor magnetic saliency at higher

frequencies under varying load conditions

• D-Q axis impedance difference gets smaller with increased load and might eventually be zero causing failure of sensorless algorithm

– This is caused by saturation of q-axis inductance with increased load.

►Armature Reaction Effect• Increasing load generates stronger armature

reaction

• The motor armature reaction shifts the resulting magnetic saliency towards the direction of q-axisSaliency shift due to

armature reactionSaliency shift due to armature reactionDecreased SaliencyDecreased Saliency

Salient Pole MotorSalient Pole Motor

50V @500Hz


Saliency Tracking Observer for Low Speeds

►Adding additional signal into rotating coordinates excites the motor at low and zero speed and makes the magnetic saliency signature visible.►Signal frequency chosen sufficiently high so no to interfere with base motor operating frequency. ► Signal amplitude chosen such that the hf currents generated by this signal are measurable with sufficient accuracy. ►If the two frames are misaligned, a high frequency signal injected in estimated d-axis will also be coupled into estimated q-axis and hf current response will be generated in estimated q-axis.

θactual

θerrd axis

q axis

d axis (est)

q axis (est)

( )errqdhf

mq ZZ

ZVi θω

2sin2

Δ−=

∧

PI regulator results in steady state error

value servoing to zero!


Initial Axis Alignment

►PM polarity detection starts after initial axis alignment►STO settling time varies depending on whether the STO stabilizing trajectory starts in an unstable region or not


PM Polarity Detection Principle

►Utilizing the effect of stator slot saturation in direction of the rotor flux►hf carrier voltage signal injected into d-axis►Amplitude of the exciting hf signal must be sufficiently large to cause visible►Depending on PM flux direction, one half of the hf signal period creates flux that adds up with PM flux whereas the other half acts against PM flux.►Signal visible at second harmonic of hf carrierMeasured Ld = f(id)


PM Polarity Detection Experiments

with PM polarity detectionwithout PM polarity detection


Sinusoidal PM Motor Model in DQ Rotating Frame

►Salient vs. Non-Salient Machine Model in DQ rotating frameStator Voltage Equations

Stator Flux Linkages of Non-Salient Machine

Stator Flux Linkages of Salient Machine

L the average inductance & ΔL the zero-to-peak differential inductance

dsdt

00

sd sdss re

sq sqss re

u iR su iR s

α

β

ψωψω

⎡ ⎤ ⎡ ⎤⎡ ⎤⎡ ⎤ ⎡ ⎤= ⋅ + ⋅⎢ ⎥ ⎢ ⎥⎢ ⎥⎢ ⎥ ⎢ ⎥−⎣ ⎦ ⎣ ⎦⎣ ⎦⎣ ⎦ ⎣ ⎦

0 10 0

sd sdsPM

sq sqs

iLiL

ψψ

ψ⎡ ⎤ ⎡ ⎤⎡ ⎤ ⎡ ⎤

= ⋅ + ⋅⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎣ ⎦⎣ ⎦⎣ ⎦ ⎣ ⎦

0 10 0

sd d sdPM

sq q sq

L iL i

ψψ

ψ⎡ ⎤ ⎡ ⎤ ⎡ ⎤ ⎡ ⎤

= ⋅ + ⋅⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦⎣ ⎦ ⎣ ⎦ ⎣ ⎦

2qd LL

L+

=2

d qL LL

−Δ =

d qL L≠

Direct & Quadrature InductanceNot Equal


Saliency Based Back-EMF Observer

► Saliency based back-EMF voltage is generated due to Ld≠Lq

► Because back-EMF term is not modeled, observer actually acts as a back-EMF state filter

► Observer is designed in synchronous reference frame, i.e. all observer quantities are DC in steady state making the observer accuracy independent of rotor speed.

voltagedtdcauses

dtdwithcombinedwhenwhich

ddcauses

ddL

=λθ

θλ

θ,,


Position Estimation Using Saliency Based Back-EMF

Position estimation steady state error at constant speed

Position estimation steady state error during speed ramp change


Full Speed Sensorless Control Operation

Accurate at low speeds

Accurate at high speeds

► Full Operation Speed Range covered by two dedicated algorithms

► Crossover Merging Algorithm - based on FUZZY logic merges the two algorithm outputs into a single position/speed estimation.

► Sensorless Algorithms► Initial Position Detection

• avoids conventional alignment

► Low Speed Algorithm• Saliency Tracking Observer

► High Speed Algorithm• State Filter Observer


IPMSM Speed Sensorless FOC

Speed control loop

Speed estimation

PWMgeneration

Position estimation

Current control loop

Hardware PortionSoftware Portion


Low Speed Operation

30 [rpm] reversal

15 [ ° ] el. degree error = 1.5 [ ° ] mech. degree error


Entire Speed Operation — Speed Profile

High-Speed Operation Low-Speed Operation


Full Speed Sensorless Experimental Results


Entire Speed Operation — Reversal Detail

Transition to full EEMF observer control

HF injection OFF

HF signal injection based sensorless control

TM

Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2008.

Motor Control on Freescale Web siteReference designs, application notes, …


Freescale Motor Control Web Pageswww.freescale.com/motorcontrol


Session MaterialSession Location – Online Literature Libraryhttp://www.freescale.com/webapp/sps/site/homepage.jsp?nodeId=052577903644CB

DemosPedestal ID Demo Title

October 7, 2008 Solutions for Electrical Traction Motor Drive · • Driving hybrid – driving...

Documents

Transcript of October 7, 2008 Solutions for Electrical Traction Motor Drive · • Driving hybrid – driving...