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Dr. Dorin ILES ([email protected]) PCIM Europe 2008
May 27 – 29 Nuremberg, Germany
Small Permanent Magnet Synchronous Motor TechnologyAn Overview
Dr. Dorin ILESHead R&D Laboratory for Electric Drives
Dr. Dorin ILES ([email protected]) 2 /
Target
• Comprehensive overview of small permanent magnet synchronous motor technology – one of the most competitive type of electric machines and drives
Dr. Dorin ILES ([email protected]) 3 /
Contents
I. IntroductionII. PMSM applicationsIII. PMSM drives technologiesIV. PMSM types and topologiesV. Materials used for PMSMVI. Construction and manufacturing technologies for PMSMVII. PMSM electromagnetic and thermal modeling and analysisVIII. Electromagnetic design - experience-based vs. optimization designIX. Experimental analysisX. Software-tools for PMSM design and analysisXI. Fundamental control issuesXII. Case study
Dr. Dorin ILES ([email protected]) 4 /
IntroductionCompeting electric motor/drives technologies for high performance applications
DC - permanent magnet brushed dc
IM - induction
BLDC - permanent magnet trapezoidal
BLAC - permanent magnet sinusoidal
SR - switched-reluctance
RS - reluctance synchronous
Dr. Dorin ILES ([email protected]) 5 /
IntroductionCompeting electric motor/drives technologies for high performance applications
DC - permanent magnet brushed dc
IM - induction
BLDC - permanent magnet trapezoidal
BLAC - permanent magnet sinusoidal
SR - switched-reluctance
RS - reluctance synchronous
DC
IM
BLDC
BLAC
SR RS
0
1
2
3
4
5
6
7
8
9
10
Dr. Dorin ILES ([email protected]) 6 /
IntroductionPMSM advantages and drawbacks
• In comparison with other conventional electric machines PMSM have two main advantages
• high efficiency (in the rotor: no copper losses and very low iron losses)
• high torque density due to the permanent magnet excitation
• PM excitation has also some drawbacks
• high cost of the permanent magnets
• risk of demagnetization at high temperature
• increased effort for permanent magnet fixture on/in rotor
• additional control effort for field weakening or advance angle control
Dr. Dorin ILES ([email protected]) 7 /
PMSM applications
• The field of actual high performance applications spans a wide range of applications• industrial• medical• electronic cooling• automotive• aerospace
Dr. Dorin ILES ([email protected]) 8 /
PMSM applicationsSchematic overview of automotive applications
SteeringHVAC
Fuel Cell Air Compressor
Variable Valve Timing
Throttle-by-wire
Clutch/Shift
Engine Cooling
Starter/ Generator
Traction
Variable Transmission
Turbocharger
BrakingSuspension
Damping Stabilizer
• Some significant automotive applications• steering systems
• active (front, rear) steering• power steering• steer-by-wire
• clutch- and shift-by wire actuators• electromechanical brakes• heating, ventilation, and air conditioning• suspension, damping and stabilization actuators• starter-generators (integrated and belt driven)• traction motors for
• electric vehicles (EV)• hybrid electric vehicles (HEV)• fuel cell vehicles (FCEV)
Dr. Dorin ILES ([email protected]) 9 /
PMSM applicationsTorque-speed demands for automotive applications
HVAC
FC-ACEPAS
EAFSEMB
SBW
EG
EHAS
EMAS
EAT
VVT
SGEV
HEV
0
1
10
100
1000
1 10 100 1000 10000 100000
Base speed [rpm]
T_pe
ak [N
m]
Dr. Dorin ILES ([email protected]) 10 /
PMSM drives technologiesClassification based on the shape of back-EMF and excitation currents
0 60 120 180 240 300 360-1.5
-1
-0.5
0
0.5
1
1.5
i
e
sinusoidal machine (BLAC) and control trapezoidal machine (BLDC) and control
3phPMSMVDC
Drive power end
stage
Drive control
position feedback
currents feedback
Dr. Dorin ILES ([email protected]) 11 /
PMSM drives technologiesBLAC motors and drives
• sinusoidal back-EMF shape and sinusoidal currents in order to get optimal torque quality• usually overlapped stator windings• mostly skewed surface permanent magnets in rotor• complex, cost-intensive high-resolution rotor position sensors like encoder or resolver (or sensorless methods) are mandatory for the sinusoidal current control• at least two current sensors are necessary to impose the shape of the phase currents
Due to the low torque ripple sinusoidal PMSM drive is the only proper technology for high performance applications
Dr. Dorin ILES ([email protected]) 12 /
PMSM drives technologiesBLDC motors and drives
• trapezoidal back-EMF shape and trapezoidal current in order to get optimal torque quality• usually concentrated stator windings• surface mounted permanent magnets (rings or segments)• BLDC motors are driven in two-phase-on mode• a simpler rotor position sensor, with a resolution of six instants per electrical period, may be used for the commutation• a single current sensor is needed for a possible control of the current in the two motor phases
The torque pulsations can be high due the current commutation and back-EMF shapes with remarkable distortionsThis simple control strategy is very often employed in low performance applications, where the required torque quality is not too high
Dr. Dorin ILES ([email protected]) 13 /
PMSM types and topologies PMSM classification
PMSMAC
machines
Axial flux Radial flux
Trapezoidal(BLDC)
Sinusoidal(PMSM)
Surface permanent magnets Interior
permanent magnets
Slotted stator Slotless stator
Distributed windings Concentrated windings
Back-EMFand stator currents shape
Permanent magnets location
Airgap flux orientation
Stator core construction
Stator windings configuration
Inner rotor Outer rotor Relative stator-rotor position
Dr. Dorin ILES ([email protected]) 14 /
PMSM types and topologies Airgap flux orientation
Radial vs. axial field PMSM (inner rotor radial, single sided axial, double sided axial configurations)
Dr. Dorin ILES ([email protected]) 15 /
PMSM types and topologies Relative stator-rotor position
Inner- vs. outer-rotor PMSM
Dr. Dorin ILES ([email protected]) 16 /
PMSM types and topologies BEMF-shape
0 60 120 180 240 300 360-1.5
-1
-0.5
0
0.5
1
1.5
i
e
Dr. Dorin ILES ([email protected]) 17 /
PMSM types and topologies Permanent magnets location
Dr. Dorin ILES ([email protected]) 18 /
Materials used for PMSMActive materials
• Permanent magnets – field excitation• Soft magnetic materials – flux paths• Copper – current conduction
Dr. Dorin ILES ([email protected]) 19 /
Materials used for PMSMPermanent magnets
• Permanent magnets (manufactured by injection or compression moulding or sintering)
• ferrites• Neodymium-Iron-Boron (NdFeB)
• For high torque density applications only sintered NdFeB-magnets can be considered
Dr. Dorin ILES ([email protected]) 20 /
Materials used for PMSMSoft magnetic (core)
Soft magnetic materials• cold rolled magnetic lamination (CRML) steel• soft magnetic composites (SMC) for “3-D design”and good construction and manufacturing capabilities
Conventional lamination steel is mandatory for high torque density applications
Comparison of typical B-H curves for lamination steel and SMC material
Dr. Dorin ILES ([email protected]) 21 /
Construction and manufacturing technologies for PMSM Major trends
• Transition from conventional overlapped to non-overlapped (concentrated, tooth-wound) winding systems• Modular stators• Rotors with interior (embedded) permanent magnets
Dr. Dorin ILES ([email protected]) 22 /
Construction and manufacturing technologies for PMSM Winding systems
• conventional overlapped winding
• non-overlapped (concentrated, tooth-wound) windings
• short end turns of the concentrated winding lead to a reduction of the copper losses• needle winding technology offers major advantages for coils with lower number of turns and higher wire diameter, like in PMSM for low voltage and/or high speed applications
Q=12, m=3, 2p=4 Y||
1 2 3 4 5 6 7 8 9 10 11 12
U V W
We Ue Ve Ua Va Wa
Q=6, m=3, 2p=4 Y||
Va Ue VeWe
1 2 3 4 5 6
Ua Ua UeUe VeVa Va VeWeWa WaWe
Ua Wa
Dr. Dorin ILES ([email protected]) 23 /
Construction and manufacturing technologies for PMSM Advanced winding techniques
• moulded hair-pin winding• single-turn wave litz winding• slotless-PMSM winding
Dr. Dorin ILES ([email protected]) 24 /
Construction and manufacturing technologies for PMSM Modular stators
New modular stator solutions (in order to increase the slot fill factor, especially for coils with higher wire diameter)
• teeth-and-yoke stator segments• two-part stators• rolled stator
Dr. Dorin ILES ([email protected]) 25 /
PMSM analysisElectromagnetic analysis aspects - Basics of PMSM modeling
Taking into account only the modeling approaches with concentrated parameters (FE-modeling and analysis will not be treated) for the PMSM the employed machine models can be classified considering following three criteria
- chosen reference coordinateso phase coordinates modeling (natural coordinates or abc-frame of reference)
o synchronous axes (dq) coordinates modeling
- nature of states variableso current state variables (CSV) modeling
o flux state variables (FSV) modeling
- nature of modeling domain o frequency domain (steady state modeling)
o time domain (transient modeling)
Dr. Dorin ILES ([email protected]) 26 /
PMSM analysisTransient FSV-model in phase coordinates for PMSM
PMSM abc-frame of reference with stationary phase axes
Voltage equations
Flux linkage vector - function of
• machine topology
• geometry
• materials
• excitation (PM, currents)
• relative windings-PM position
• PM-temperature
θea
c
b
a-axis
c-axis
b-axis
q-axis
d-axis
NS
dtdiRv
dtdiRv
dtdiRv
cccc
bbbb
aaaa
ψ
ψ
ψ
+=
+=
+=
Dr. Dorin ILES ([email protected]) 27 /
PMSM analysisTransient CSV-model in phase coordinates for PMSM
PMSM abc-frame of reference with stationary phase axes
Voltage equations
θea
c
b
a-axis
c-axis
b-axis
q-axis
d-axis
NS
PMce
ccce
e
cbbe
e
caae
ccc
bcb
acaccc
PMbe
bcce
e
bbbe
e
baae
cbc
bbb
ababbb
PMae
acce
e
abbe
e
aaae
cac
bab
aaaaaa
eddLi
ddLi
ddLi
dtdiL
dtdiL
dtdiLiRv
eddLi
ddLi
ddLi
dtdiL
dtdiL
dtdiLiRv
eddLi
ddLi
ddLi
dtdiL
dtdiL
dtdiLiRv
_
_
_
+++++++=
+++++++=
+++++++=
ϑω
ϑω
ϑω
ϑω
ϑω
ϑω
ϑω
ϑω
ϑω
Dr. Dorin ILES ([email protected]) 28 /
PMSM analysisdq0-coordinate transformation
• eliminates the rotor position dependence of inductances
• direct transformation
• inverse transformation
θea
c
b
a-axis
c-axis
b-axis
q-axis
d-axis
NS( )
( )
021
21
21
32
34sin
32sinsin
32
34cos
32coscos
32
0 =
++=
−−
−−−=
−+
−+=
cba
ecebeaq
ecebead
vvvv
vvvv
vvvv
πθ
πθθ
πθ
πθθ
( )0abc dq→
( ) ( )
0
0
0
34sin
34cos
32sin
32cos
sincos
vvvv
vvvv
vvvv
eqedc
eqedb
eqeda
+
−−
−=
+
−−
−=
+−=
πϑ
πϑ
πϑ
πϑ
ϑϑ
( )0dq abc→
Dr. Dorin ILES ([email protected]) 29 /
PMSM analysisTransient CSV-model in synchronous coordinates for PMSM
PMSM rotor-synchronous (dq)-frame of reference
dq-equivalent circuit
Voltage equations
dq-axis fluxes
θea
c
b
a-axis
c-axis
b-axis
q-axis
d-axis
NS
Rph ωeLqIqLdId
Vd
RphωeLdIdLq
Iq
Vq ωeΨPM
deq
qed
dd
dtd
Riv
dtdRiv
ψωψ
ψωψ
++=
−+=
qincqq
PMdincdd
iLiL
=
+=
ψ
ψψ
Dr. Dorin ILES ([email protected]) 30 /
PMSM analysisTransient CSV-model in synchronous coordinates for PMSM
CSV-model
electromagnetic torque
dynamic equation
- polar moment of inertia of the rotor, - coefficient of viscous friction, - load torque
−−−=
+−=
incq
PMedinc
q
deqinc
qincq
qincd
incqe
dincd
incd
dd
Li
LLi
LR
Lv
dtdi
iLL
iLR
Lv
dtdi
ψωω
ω
( )( ).23
qdincq
incdqPMem iiLLipt −−= ψ
( )Lmemr
m tBtJdt
d−−= ω
ω 1
BrJ Lt
Dr. Dorin ILES ([email protected]) 31 /
PMSM analysisSpecial physical phenomena in PMSM
The estimation of the mentioned machine parameters (resistances, inductances, fluxes) is influenced by several special physical phenomena within the PMSM
• iron core saturation
• iron core losses
• cross-saturation between the two orthogonal axes in the dq-model
• harmonics (spatial and time harmonics) for several physical quantities
• temperature effects (modification of machine parameters with temperature)
)()(
qqq
ddd
iLLiLL
==
),(
),(
qdqq
qddd
iiLLiiLL
=
=
RphωeLdI0d
RFe
Lq
V0q
I0q
IFeq
Iq
Vq ωeΨPM
Rph ωeLqI0q
RFe
Ld
V0d
I0d
IFed
Id
Vd
( ) ( ) ( )∑∑∞
=
∞
=
−==11
_ cosn
nenn
enPMePM nA ϕθθψθψ ( ) ( )∑∞
=
++=1
0 cosn
neneij nAAL ϕθθ
( ) ( ) ( )[ ]1212 1 θθαθθ ρ −+=Cu
RR ( ) ( ) ( )[ ]1212 1 θθαθθ −+=rBrr BB
Dr. Dorin ILES ([email protected]) 32 /
PMSM analysisThermal analysis aspects
Employing an one body (one source of losses) thermal model the temperatures for the different parts of the machine can be calculated• temperature rise of winding, permanent magnet and frame
- factor taking into account the duty cycle
- thermal resistance winding-ambient
- thermal resistance PM-ambient
- thermal resistance frame-ambient
_ _co duty loss th co ambT k P R∆ =
_ _PM duty loss th PM ambT k P R∆ =
_ _fr duty loss th fr ambT k P R∆ =
dutyk
_ _th co ambR
_ _th PM ambR
_ _th fr ambR
Dr. Dorin ILES ([email protected]) 33 /
PMSM analysisThermal analysis aspects
• thermal resistance frame-ambient
- frame area
- heat transfer coefficient through conduction, convection and radiation
• thermal resistances winding-ambient and PM-ambient
• absolute winding, PM and frame temperatures
_ __ _
1th fr amb
fr tr fr amb
RA h
=
frA_ _tr fr ambh
_ __ _
1th co amb
fr tr co amb
RA h
=_ _
_ _
1th PM amb
fr tr PM amb
RA h
=
co amb coT T T= +∆ PM amb PMT T T= +∆ fr amb frT T T= +∆
Dr. Dorin ILES ([email protected]) 34 /
PMSM design aspectsElectromagnetic design – demands and constraints
Manufacturing constraints :D_wire_max
Slot_width_minStator_yoke_heigth_min
Load machine (geometrical ) constraints :Volume (DxL)
Electric machine
Inverter constraints :U_rms_maxI_rms_max
Ambient constraints :Temperature (min, max)
HumidityPollution
Performance demands :T-n load points
T_max/JAcceleration/deceleration
T_cogg, T_pulsAcoustic behaviour
EMIControl (torque , speed, position)
Constructive /mechanical constraints :Stator_tooth_width_minWidth_bridge _rotor_minStator_yoke_heigth_min
Tolerances
Cost constraints :Material type (PM)
Material type (laminations)
Materials constraints :Temperature _winding _max
Demagnetization (PM)
Standards compliance constraints :
Dr. Dorin ILES ([email protected]) 35 /
PMSM design aspectsElectromagnetic design methods for electric machines
• Design (synthesis) vs. analysis
• Conventional (experience-based) design vs. optimization design
AnalysisSynthesis
Performance parameters(specification)
Design solution
Design solution Performance parameters
(Global) design methods
Conventional design :- experience -based
- heuristics
Advanced design :- optimization design
Dr. Dorin ILES ([email protected]) 36 /
PMSM design aspectsElectromagnetic design
Conventional (experience-based) design process includes
• analysis of specifications
• selection (experience-based) of topological structure
• selection (experience-based) of
• active materials (soft magnetic, hard magnetic, conducting)
• passive materials (insulating)
• dimensioning (experience-based) of geometry
• parameter and performance calculation
• choice of manufacturing technologies
• costs prediction
Dr. Dorin ILES ([email protected]) 37 /
PMSM design aspectsExperience-based design
• Motor design problem for a specific application is to find a set consisting of• topological structure• materials• geometry (shapes and dimensions)
• Traditional method is based on design engineers experience• This approach involves an immense effort, since it assumes the mastering of a wide area of technical knowledge• The conventional synthesis (design) process for electric machines, although based on a highly-developed theory and affording extended mathematical skills, has a fuzzy and heuristic nature, as it can not be carried out in a straightforward, closed way
Design solution
Topological structurestructuring
Materialsmaterialing
Excitation :currents / voltages
Geometry:- shapes; shaping
- dimensions ; dimensioning
Dr. Dorin ILES ([email protected]) 38 /
PMSM design aspectsElectromagnetic design/synthesis approaches
• sizing
• shaping
• structuring
Dr. Dorin ILES ([email protected]) 39 /
PMSM design aspectsExperience-based design
• Experience-based topology (configuration or structure) selection – crucial design issue• Selection of
• direction of the airgap field (radial, axial, or transversal field structure)r• relative rotor-stator position (interior or exterior rotor structure)• number of phases in stator (usually three or even more phases for high performance applications)• number of stator slots• number of rotor poles• structure of winding system
• one/two layers• overlapped/non-overlapped• electrically balanced/non-balanced• fully/partially wound stator
Dr. Dorin ILES ([email protected]) 40 /
PMSM design aspectsTopology selection based quality factors
Quality factors for small (up to 24 stator slots and 16 rotor poles) PMSM with symmetrically single-layerconcentrated windings
Dr. Dorin ILES ([email protected]) 41 /
PMSM design aspectsTopology selection based quality factors
Quality factors for small (up to 24 stator slots and 16 rotor poles) PMSM with symmetrically two-layer concentrated windings
Dr. Dorin ILES ([email protected]) 42 /
PMSM design aspectsExperienced-based sizing (dimensioning)
• Starting with a set of known key design parameters it is possible to determine the complete design
• Key design parameters can be• dimensional proportions• mechanical, electric, magnetic loadings
• The number of these key design parameters can vary
• It is possible to minimize this number by introducing proper additional design constraints and a few “given” geometrical dimensions (e.g. airgap length)
Dr. Dorin ILES ([email protected]) 43 /
PMSM design aspectsExperienced-based sizing (dimensioning)
• One possible way to choose the key design parameters
- average surface force density- ratio outer rotor diameter to stack length- amplitude of the first harmonic of the airgap flux density- maximal stator yoke flux density- maximal stator tooth flux density- maximal rotor yoke flux density- current density in the stator winding
• These key design parameters may also be chosen as design variables in an optimization design process
1, , , , ,sav g ys ts yrf B B B Bλ j
savf
λ1gB
ysB
tsB
yrB
j
Dr. Dorin ILES ([email protected]) 44 /
PMSM design aspectsExperienced-based sizing (dimensioning)
• Key geometrical dimensions of an electric machine
• The average surface force density is defined
- electromagnetic torque- outer rotor diameter- stack length
• The ratio outer rotor diameter to stack length
Loew
L
Shaft
Dso
Dro
Dri
(Dsh)
Stator
Rotor
2
2 esav
ro
TfD Lπ
=
eT
roD
L
roDL
λ =
Dr. Dorin ILES ([email protected]) 45 /
PMSM design aspectsExperienced-based sizing (dimensioning)
• Given the required electromagnetic torque in the specification and knowing (experience) the values of the key design parameters the dimensioning process can be done
• outer rotor diameter
• stack length
• Motor geometry dimensioning using adopted values for the magnetic and electric loadings in the stator and rotor• Motor parameter and performance (including losses, efficiency, temperature rise, weight, costs)
32 e
rosav
TDfλ
π=
roDLλ
=
Dr. Dorin ILES ([email protected]) 46 /
Experimental analysis
• Goal - to offer accurate estimated and validated• machine parameters which can be used for later system simulations and control tasks• machine operational performance parameters as validation of the design method and design solution
• The measurement procedure consists of several tests chosen to allow the estimation of machine parameters and operational parameters in different approaches and in a wide area of variation
Dr. Dorin ILES ([email protected]) 47 /
Experimental analysisOverview of measurement procedure
• Standstill tests• Running tests• Thermal analysis• Vibro-acoustic analysis
Dr. Dorin ILES ([email protected]) 48 /
Experimental analysisOverview of measurement procedure - Standstill tests
• Resistances• phase• line-line
• Inductances (RLC-bridge, AC-, DC-decay method)• phase self• line-line• phase leakage• saturated synchronous• decoupled saturated sysnchronous
Dr. Dorin ILES ([email protected]) 49 /
Experimental analysisOverview of measurement procedure - Running tests
• unloaded machine• machine parameters
• no-load phase&line-line BEMF• friction torque• no-load iron losses torque• cogging torque
• loaded (current controled) motor• machine parameters
• synchronous inductances• dq-flux linkages• iron losses
• machine operational parameters• torque-speed char.• efficiency-speed char.
• loaded generator• generator characteristics
• torque-speed char.• efficiency-speed char.
• faulted inverter/machine• braking torque-speed char.• braking current-speed char.
Dr. Dorin ILES ([email protected]) 50 /
Experimental analysisOverview of measurement procedure – Thermal and vibroacoustic analysis
• steady state characteristics• continuous duty cycle SOA
• transient parameters• thermal resistances• thermal capacities
• Thermal analysis
• time-domain signals• vibration• sound
• frequency-domain signals (frequency spectrum)• vibration• sound
• Vibro-acoustic analysis
Dr. Dorin ILES ([email protected]) 51 /
Software-tools for PMSM design and analysis
Dr. Dorin ILES ([email protected]) 52 /
Fundamental control issues
• Accurate stator current synchronization with the rotor position is mandatory for good quality torque
Basic configuration of a drive system with a three-phase PMSM - used for both types of PMSM
• Rotor position feedback• trapezoidal PMSM-drive: three Hall-elements (with a resolution of 60 electrical degrees)• sinusoidal PMSM-drive: higher resolution rotor position sensor (encoder or resolver)
3phPMSMVDC
Drive power end
stage
Drive control
position feedback
currents feedback
Dr. Dorin ILES ([email protected]) 53 /
Fundamental control issuesBasic control methods
• Two different major classes of control techniques are available for the two PMSM types: • trapezoidal control for trapezoidal excited machines• sinusoidal control for sinusoidal machines
• The different applications require• torque• speed• position control
• Therefore a wide range of controller types may be used (e.g. classical proportional-integral, adaptive, or intelligent)• For high performance applications - where a high quality of the torque output is crucial - closed-loop sinusoidal vector current control is mandatory• In the following only the control methods for sinusoidal PMSM will be presented
Dr. Dorin ILES ([email protected]) 54 /
Fundamental control issuesV/s (scalar) control
• PMSM with rotor damper cage - simple open-loop V/f control method to achieve speed control for some applications like pumps and fans with slower dynamic response
• PMSM without rotor cage - control scheme with speed information for the synchronization of the currents and rotor frequency (closed-loop control with rotor frequency and not rotor position monitoring for lower dynamic performance applications)
3phPMSM
Frequency command
Voltage calculation
PWMVSI
f*
Vs*
f*
3phPMSM
Frequency command
Voltage calculation
PWMVSI
f*
Vs*
f
d/dtΔf calculation
Δf
ωr
Rotor angular position
θr
Dr. Dorin ILES ([email protected]) 55 /
Fundamental control issuesClosed-loop torque and speed
• For higher performance torque and speed control structures can be employed using current and rotor angular position feedback (for the speed control a second speed control loop is necessary)
Speed command
PWMVSI
Speed controllerωr*
Vs*
d/dtωr
Rotor angular position
θr
Δωr
θr
Torque controller PMSM
Te*
Current feedback
ω r
Dr. Dorin ILES ([email protected]) 56 /
Fundamental control issuesPosition sensorless control
• In the above presented closed-loop control methods the presence of the rotor angular position sensor is mandatory for the stator current excitation synchronization with the rotor position• The rotor position sensor is undesired
• costs• mechanical mounting• sensitivity to temperature and vibration• need of wired connection to the controller
• In the last decade a lot of research work was done in order to find control methods which can work properly without rotor position sensors – position sensorless control
Dr. Dorin ILES ([email protected]) 57 /
Fundamental control issuesPosition sensorless control
• V/f closed-loop position sensorless speed control - the measurement of currents and voltages at the motor terminalsor DC-link are used to calculate the error in the synchronization of the stator current excitation and the rotor speed
• Closed-loop position-sensorless torque and speed control using an accurate rotor angular position and speed estimation from the measured voltages and currents at the motor terminals or DC-link
3phPMSM
Frequency command
Voltage calculation
PWMVSI
f*
Vs*
f
Δf calculation
Δf V and I measurements
Speed command
PWMVSI
Speed controllerωr*
Vs*
Rotor position and speed
estimator
V, Imeasurements
Δωr
Θr_est
Torque controller PMSM
Te*
Current feedback
ωr_est
Dr. Dorin ILES ([email protected]) 58 /
Case studyPMSM for an electric active front steering drive
• illustrate relevant aspects related to the motor design and control for the sinusoidal and trapezoidal technologies• motor specification, geometrical and technological design constraints for both technologies
Dr. Dorin ILES ([email protected]) 59 /
Case studyPMSM for an electric active front steering drive – Sinusoidal design solution
Dr. Dorin ILES ([email protected]) 60 /
Case studyPMSM for an electric active front steering drive – Trapezoidal design solution
Dr. Dorin ILES ([email protected]) 61 /
Case studyPMSM for an electric active front steering drive
Sinusoidal indirect current vector control structure
Dr. Dorin ILES ([email protected]) 62 /
Case studyPMSM for an electric active front steering drive – BLAC experimental results
The torque production
can be maximized through optimizing the torque angle γ
• torque vs. speed characteristics for different torque angle γ
• torque vs. torque angles for different phase currents
• torque pulsations
( )( ).23
qdqdqPMem IILLIpT −−= ψShaft output torque vs. torque angle
(variable phase current)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 1000 2000 3000 4000 5000 6000 7000Speed [1/min]
Shaf
t out
put t
orqu
e [N
m]
T2_gamma = 0T2_gamma = 20T2_gamma = 40T2_gamma = 60
Shaft output torque vs. torque angle and phase current
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
0 10 20 30 40 50 60 70 80 90
Torque angle [deg_el]Sh
aft o
utpu
t tor
que
[Nm
]
6.6 Arms
19.7 Arms
32.6 Arms
45.6 Arms
71.3 Arms
Dr. Dorin ILES ([email protected]) 63 /
Conclusion
• PMSM technology was presented in an overview covering a wide area
• Included material is intended to give an orientation and to facilitate individual in-depth work in particular cases
Dr. Dorin ILES ([email protected]) PCIM Europe 2008
May 27 – 29 Nuremberg, Germany
Thank you for your attention!