Weitere ähnliche Inhalte Ähnlich wie Maxon presentation sizing of dc servo motors for extreme environment operation 02-2014 (20) Mehr von Electromate (20) Kürzlich hochgeladen (20) Maxon presentation sizing of dc servo motors for extreme environment operation 02-20141. Introduction
drive seminar
maxon seminar:
Sizing of DC Servo Motors for
Extreme Environment Operation
What are the challenges and what is required?
Performance of heavy duty drive systems
© 2012 maxon motor ag, Sachseln, Switzerland
Learning objectives
The participants …
learn to read the data sheets of DC motors, EC motors,
gearheads.
know the main properties and application ranges of DC
and EC motors and be able to select the correct system.
know how the particular features of maxon heavy duty
motors and gearheads can be used for extreme operation
conditions.
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1
© 2014, maxon motor ag
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1
2. Introduction
drive seminar
Agenda Heavy Duty Seminar
09.30 – 10.15
Motor selection: What is it all about?
– Application and situation analysis
– Extracting key load parameters
10.15 – 10.45
Properties of brushed and brushless DC motors
– Design variants
– Commutation systems: brushed, brushless
10.45 – 11.00
Coffee break
11.00 – 11.30
Motor data sheets
– Characteristic motor lines
– Operation ranges
11.30 – 12.15
Heavy Duty motors and gearheads
12.15 – 13.00
Lunch
13.00 – 13.45
Motor selection example
13.45 – 14.30
Questions, discussion
Media
maxon Formulae Handbook
– epaper.maxonmotor.ch/formulaehandbook
maxon catalogue
– epaper.maxonmotor.ch/en/
Presentation hand-outs
www.maxonmotor.com
– Service & Downloads
– Service Desk (FAQ)
– maxon academy
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2
© 2014, maxon motor ag
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2
3. Overview of the selection steps
drive seminar
Selection of
drive components
Systematics of the drive selection
Situation analysis, boundary conditions
How is the integration into the environment?
Preselection
Determining the load requirements
Result: key data for load characterization
© 2012 maxon motor ag, Sachseln, Switzerland
Systematic selection process
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
Page
step 5+6
step 7
motor type sensor
winding
controller
1
© 2013, maxon motor ag
Page
1
4. Overview of the selection steps
drive seminar
Step 1: Gain an overview
analyze
recognize dependencies
problem
mechanics
power
operating mode
motion profile
control concept
checklist
operating points
control accuracy
boundary conditions
Drive system as a black box
environment
electrical power
task
current
voltage
temperature, atmosphere
impacts, vibration
…
boundary conditions
dimensions
service life
…
set values
commands
emissions
mechanical power
quality, accuracy
resolution
mech. play
electro magnetic
heat
noise
…
force, torque
velocity, speed
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2
© 2013, maxon motor ag
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2
5. Overview of the selection steps
drive seminar
Operating mode
What is a working cycle?
How often is it repeated? Which breaks?
continuous operation
cyclic operation
intermittent
Short-time operation
Operating modes
continuous (S1)
load
time
short term (S2)
working cycles
intermittent (S3)
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3
© 2013, maxon motor ag
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3
6. Overview of the selection steps
drive seminar
Control concept
What kind of communication?
– communication with
higher level host system
– set value range
– inputs and outputs
Controlled variable
– torque, current
– speed, velocity
– position
feedback
sensor
Controlled range, accuracy?
– position resolution
– speed stability
Controller: Heart of the drive system
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4
© 2013, maxon motor ag
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4
7. Overview of the selection steps
drive seminar
Sensors in feedback systems
Power
Motion
Controller
Closed loop
system for speed
or position
Commands,
Set values
Control parameter
Feedback, sensor
Position
∆𝑝𝑜𝑠 Speed,
Direction
∆𝑡
Encoder
Hall sensors
Resolver
Speed, Direction
DC Tacho
IxR
Task and control accuracy
The accuracy of control is the combined result
of all components in a drive system!
– resolution, precision
signal
amplification
command
controller
mechanical play
motor
gearhead,
drive
load
control loop
sensor
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5
© 2013, maxon motor ag
phase shifts
time shifts
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5
8. Overview of the selection steps
drive seminar
Accuracy of drive systems
position accuracy
–
–
–
–
absolute, relative, repeatability
overshoot allowed?
mechanical play in couplings, gearheads, …
encoder resolution and accuracy (linearity)
r
speed accuracy
–
–
–
–
Corrected in what time frame?
t
min. speed nmin by encoder resolution
max. speed nmax by limiting frequency of the encoder
Speed ripple by current and / or torque ripple
electronic components
– resolution of A/D-converters, frequency voltage converter
– bandwidth, temperature influences
Time and frequency aspects
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6
© 2013, maxon motor ag
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6
9. Overview of the selection steps
drive seminar
Power flow
power
supply
Losses
controller
gearhead,
drive
motor
Pmech = v * F
Pmech = ω * M
sensor
Pel = U * I
load
energy is not stored: Power flow
– Power: a „constant“ reference value of the drive system
Power consists of 2 components:
– voltage and current
– velocity and force or speed and torque
– One components can only increase at the expense of the other.
Transformation of power
transformation of power efficiency η describes losses
– electrical to electrical:
η = 90 – 95%
η = 90%
– electrical to mechanical:
optimum
η = 80 - 90%
– mechanical to mechanical:
ball screw spindle
η = 80 - 90%
η = 90%
per stage
trapezoidal spindle 40%
worm gear < 40%
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7
© 2013, maxon motor ag
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7
10. Overview of the selection steps
drive seminar
Mechanical drive concept
Drive design: linear – rotation
Drive elements and coupling with load
relative position of motor and load
– e.g. bridge a distance with a belt
Motors up to 500W
n
DC behavior
(shunt)
DC motors
M
I
BLDC motors
linear motors
f
stepper motors
Stator
winding
magnetic
rotor
synchronous motors
start
M
asynchronous motors
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8
© 2013, maxon motor ag
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8
11. Overview of the selection steps
drive seminar
Particular boundary conditions
dimensions
service life
– specific depending on load cycle, ambient conditions and application
– given as service hours or numbers of working cycles
– limited by the weakest component
temperature, atmosphere
– can influence the achievable power and service life
noise, vibration
– specific depending on load cycle, mounting
and ambient conditions, application
– influences on service life
Interfaces: Connections
electrical connections
– cable type, cable length, colours
– plug
– strain relief
mechanical interface
– mounting type, mounting pilot, threads, number and location of bolt
holes
– output shaft: length, diameter, flats
– drive elements, pinions, couplings
– tolerances
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9
© 2013, maxon motor ag
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9
12. Overview of the selection steps
drive seminar
Definition of the load requirements
motion profile and
forces and torques
operation points
v(t), F(t)
mass inertia and
n(t), M(t)
Key values
acceleration
Operating points
Pair of
– torque and speed
– force and velocity
standard representation: (x,y) = (M,n) or (F,v)
speed n
velocity v
deceleration
acceleration
torque M
force F
dwell
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10
© 2013, maxon motor ag
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10
13. Overview of the selection steps
drive seminar
Operating point and motion profile
n
1
2
3
4
1
t
n
extreme
operating point
2
3
4
1
M
(M1,n1)
acceleration
friction and acceleration
(M2,n2)
const. speed
friction only
(M3,n3)
deceleration
friction helps during deceleration
(M4,n4)
dwell
depending on friction
Key load data for characterization
maximum load
average effective load (RMS)
MRMS
1
2
2
t1M1 t 2M2 t 3M3 ...
2
t tot
Fmax / Mmax
F/M
FRMS / MRMS
Δtmax
Δttot
maximum velocity or speed
vmax / nmax
duration of the maximum load
duration of a load cycle
Δtmax
Δttot
required position resolution
required speed accuracy
t
Δs
Δn
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11
© 2013, maxon motor ag
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11
14. Overview of the selection steps
drive seminar
Example: Conveyor belt for samples
pulley diameter
maximum mass on belt
coefficient of friction on
100 mm
3 kg
support
friction force (empty belt)
feed velocity
supply voltage
approx. 0.3
approx. 40 N
0.5 m/s
24 V
Step 1: Situation Analysis
What information is missing?
operating mode
current
task of the drive / setpoints
maximum length / diameter
service life
movement quality
emissions
environmental conditions
control concept
Page
pulley diameter
maximum mass on belt
coefficient of friction on
support
100 mm
3 kg
approx. 0.3
friction force (empty belt) approx. 40N
feed velocity
0.5 m/s
supply voltage
24 V
12
© 2013, maxon motor ag
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12
15. Overview of the selection steps
drive seminar
Step 2: Load requirements
What information is missing?
acceleration value
motion profiles
Mass (rollers, conveyor belt)
Forces / torques
…….
pulley diameter
maximum mass on belt
coefficient of friction on
support
100 mm
3 kg
approx. 0.3
friction force (empty belt) approx. 40N
feed velocity
0.5 m/s
supply voltage
24 V
Example: Conveyor belt for samples
speed
nL =
30
30 vL 30 0.5
100 min 1
d
0.05
2
feed force
FL = m g FR 0.3 3 10 40 9 40 50N
torque
ML =
power
PL = vL FL 0.5 49 25 W
acceleration
Fa = m
d
0.1
FL
49 2.5Nm
2
2
vL
0.5
3
1.5N
t
1
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13
© 2013, maxon motor ag
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13
16. Overview of the selection steps
drive seminar
Example conveyor belt: Key values
Looking for a drive that can accomplish the following:
maximum speed
average torque
maximum torque
duration of Mmax
nmax
100 rpm
Meff
approx. 2.5 Nm
Mmax approx. 2.7 Nm
1s
n
100 rpm
2.5
Page
2.7 Nm
14
© 2013, maxon motor ag
M
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14
17. maxon DC and EC motors
drive seminar
3. Low power motors
DC motors
EC motors
Structure, properties, options
© 2012, maxon motor ag, Sachseln, Switzerland
Top
DC motor designs
conventional, slotted
e.g. Dunkermotor
coreless
e.g. maxon
DC motors - overview
Top
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1
© 2013, maxon motor ag
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1
18. maxon DC and EC motors
drive seminar
Conventional DC motor
el. connections
winding
brush system
iron core
commutator permanent magnet
(external)
flange
housing
(magn. return)
DC motors - overview
Top
Coreless maxon DC motor (RE 35)
self supporting
winding
commutator
plate
press ring
shaft
ball bearing
brushes
el. connections
flange
housing
(magnetic return)
ball bearing
commutator
permanent magnet
(in the centre)
press ring
DC motors - overview
Top
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2
© 2013, maxon motor ag
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2
19. maxon DC and EC motors
drive seminar
What makes maxon motors special?
no cogging
– no soft magnetic teeth to interact with the permanent magnet
– smooth motor running even at low speed
– less vibrations and audible noise
– any rotor position can easily be controlled
– no nonlinearities in the control behavior
compact design
– more efficient design of the magnetic circuit
– compact magnet, high power density
– small rotor mass inertia
– high dynamics
DC motors - overview
Top
What makes maxon motors special?
no iron core - no iron losses
– constantly impressed magnetization
– high efficiency, up to over 90%
– low no-load current, typically < 50 mA
no saturation effects in the iron core
– Even at the highest currents the produced torque
is proportional to the motor current.
– stronger magnets = stronger motors
low inductance
– less brush fire, longer service life
– less electromagnetic emissions
– easier to suppress interferences: capacitor between connections,
ferrite core at motor cable
DC motors - overview
Top
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3
© 2013, maxon motor ag
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3
20. maxon DC and EC motors
drive seminar
maxon DC motor families
DCX motor range
– configurable system
– high performance motor with NdFeB magnet
– high torques and speeds
10 - 35mm
RE motor range
6 - 65mm
– high performance motor with NdFeB magnet
A-max motor range
– attractive price-performance ratio
– DC motor with AlNiCo magnet
12 - 32mm
RE-max motor range
13 - 29mm
– performance between RE and A-max
DC motors - variants
Top
DC commutation systems
Graphite
graphite brush with 50%
copper
copper reduces the contact
and brush resistance
copper commutator
graphite serves as lubricant
spring system (schematic)
Precious metal
bronze brush body with plated silver contact area
silver alloy commutator
smallest contact and brush resistance (50 mW)
CLL for high service life
DC motors – commutation
Top
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4
© 2013, maxon motor ag
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4
21. maxon DC and EC motors
drive seminar
DC commutation: Characteristics
Graphite
+ well suited for high currents and
Precious metal
+ well suited for smallest currents
+
+
+
peak currents
well suited for start-stop and
reversing operation
larger motors (>approx. 10 W)
higher friction, higher no-load
current
not suited for small currents
higher audible noise
higher electromagnetic emissions
higher costs
+
+
+
+
+
and voltages
well suited for continuous
operation
smaller motors
very low friction
low audible noise
low electromagnetic interference
cost effective
not suited for high current and
peak currents
not suited for start-stop operation
DC motors – commutation
Top
EC motors
electronic commutation
– with Hall sensors
– sensorless
– sinusoidal commutation
2/4-pole EC motor
internal rotor
Multipole EC flat motor
external rotor
Multipole ECi motor
internal rotor
EC motors - overview
Top
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5
© 2013, maxon motor ag
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5
22. maxon DC and EC motors
drive seminar
Brushless DC motor
names: EC motor, BLDC motor
motor behavior similar to DC motor
– design similar to synchronous motor (3 phase stator winding,
rotating magnet)
– the powering of the 3 phases according to rotor position
main advantages: higher life, higher speeds
slotless windings: no magnetic detent, less vibrations
becomes more attractive
– costs and size of electronics
– strength of magnets
EC motors - overview
Top
maxon EC motor families
features in common
EC motors - variants
Top
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6
© 2013, maxon motor ag
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6
23. maxon DC and EC motors
drive seminar
maxon EC motor families
maxon EC motor
– high speeds and torques
EC-max
– good value for money
– not optimized for performance: relatively high torque
– speeds up to 12’000 min-1
EC-4pole
– optimized for performance: high torque
– speeds up to 25’000 min-1
EC flat motor
– very good value for money
– speeds up to 12’000 min-1
– relatively large amount of torque
EC motors - variants
Top
maxon EC motor
PCB with
Hall sensors
preloaded
ball bearings
magn. return:
laminated iron stack
control
magnet
housing
el. connections winding
and Hall sensors
3 phase knitted
maxon winding
balancing rings
rotor
(permanent magnet)
EC motors - variants
Top
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7
© 2013, maxon motor ag
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7
24. maxon DC and EC motors
drive seminar
Electronic commutations systems
common goal: applying the current to get the maximum torque
perpendicular magnetic field orientation of
- rotor (permanent magnet)
- and stator (winding)
knowledge of rotor position with respect to winding
commutation
type
block
sensorless
DECS
sine
rotor position
feedback
Hall sensors
ESCON
encoder (+ HS)
EPOS2
maxon
controller
families
ESCON
EPOS2
EPOS3
EtherCAT
EC motors – electronic commutation
Top
Block commutation
rotor position from Hall
sensor signals
north
control magnet
south
Hall sensor
1
0
0
0°
EC-max and EC flat:
Power magnet is probed directly
1
1
0
0
1
0
0
1
1
0
0
1
1
0
1
1
0
0
60° 120° 180° 240° 300° 360°
rotation angle
EC motors – electronic commutation
Top
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8
© 2013, maxon motor ag
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8
25. maxon DC and EC motors
drive seminar
Block commutation
commutation
electronics
+
power stage
(MOSFET)
EC motor
(magnet, winding, sensor)
commutation
logics
Phase 1
HS1
Phase 3
HS3
HS2
Phase 2
–
rotor position feedback
EC motors – electronic commutation
Top
DC and EC motor: Comparison
EC motor
+ long life, high speeds
DC motor
+ simple operation and
preloaded ball bearings
control, even without
electronics
+ no electronic parts in the
motor
brush commutation system
+ no brush fire
iron losses in the
more cables
more expensive
limits motor life
max. speed limited by
magnetic return
needs electronics to run
electronic parts in the
commutation system
motor (Hall Sensor)
Comparison DC and EC
Top
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9
© 2013, maxon motor ag
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9
26. maxon DC and EC motors
drive seminar
DC and EC motor: Comparison
maxon motor family
RE (DC)
EC
EC-max
(20 … 100 Watt)
EC-4pole
EC-flat
EC-i
50 000 min-1
10 W/cm3
25 000 min-1
5 W/cm3
2 mNm/cm3
10 ms
1 mNm/cm3
5 ms
max. speed
power density
torque density
mech. time
(min-1)
(W/cm3)
(mNm/cm3)
const. (ms)
Comparison DC and EC
Top
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10
© 2013, maxon motor ag
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10
27. maxon Motor Data and Operating Ranges
drive seminar
Motor data and
operating ranges of
maxon DC motors
Motor behaviour: speed-torque line, current
Motor data and operating ranges
© 2012, maxon motor ag, Sachseln, Switzerland
Top
DC motor as an energy converter
electrical in mechanical energy
Pel U I
– speed constant
– torque constant
– speed-torque line
Pmech
30
nM
PJ R I2
applies to DC and EC motors
– "EC" = "brushless DC" (BLDC)
Overview
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1
© 2013, maxon motor ag
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1
28. maxon Motor Data and Operating Ranges
drive seminar
Characteristic motor data
describe the motor design and general behaviour
independent of actual voltage or current
strongly winding dependent values (electromechanical)
10
Terminal resistance (phase to phase) R
11
Terminal inductance (phase to phase) L
12
Torque constant kM
13
Ω
Speed constant kn
mH
mNm / A
rpm / V
almost independent of winding (mechanical)
14
Speed / torque gradient Dn/DM
15
Mechanical time constant tm
16
Rotor mass inertia JMot
rpm / mNm
ms
gcm2
Characteristics
Different windings
R
low resistance winding
thick wire, few turns
low rated voltage
high rated and starting
high resistance winding
thin wire, many turns
high rated voltage
low rated and starting
high specific speed
low specific torque (mNm/A)
low specific speed (min-1/V)
high specific torque (mNm/A)
currents
currents
(min-1/V)
Characteristics
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2
© 2013, maxon motor ag
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2
29. maxon Motor Data and Operating Ranges
drive seminar
Electromechanical constants
Torque constant kM
– produced torque is proportional to motor current
– unit:
mNm / A
Speed constant kn
– law of induction: changing flux in a conductor loop
– mostly used for calculating no-load speeds n0
– unit:
min-1 / V
M kM I
n k n Uind
n0 k n U
Correlation
– kM and kn are inverse, but in different units
– expressed in the units from catalog:
kM kn
30'000 mNm min 1
A
V
Characteristics
Motor as an electrical circuit
U
+
I
_
R
L
EMF: induced voltage Uind
(winding) resistance R
EMF
winding inductance L
• voltage losses over L can be
neglected in DC motors
applied motor voltage U:
U L I R I EMF R I Uind
t
30'000 R
M
n kn U
2
kM
Dn
n kn U
M
DM
Uind U R I
n
M
UR
kn
kM
Characteristics
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3
© 2013, maxon motor ag
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3
30. maxon Motor Data and Operating Ranges
drive seminar
Speed-torque line
speed n
n kn U
Dn
M
DM
U > UN
n0
n0 k n U
Dn
U = UN
DM
MH
IA
torque M
current I
Characteristics
Speed-torque gradient
by how much is the speed reduced Dn,
if the output motor torque is enhanced by DM?
Dn 30'000
n
R i
2
DM k M
MiH
speed n
strong motor:
M1, n1
n0
Dn
• flat speed-torque line, small Dn/DM
• not sensitive to load changes
• e.g. strong magnet, bigger motor
M2, n2
DM
weak motor:
• steep speed-torque line, high Dn/DM
• sensitive to load changes
• e.g. weak magnet, smaller motor
MH
torque M
Characteristics
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4
© 2013, maxon motor ag
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4
31. maxon Motor Data and Operating Ranges
drive seminar
Winding series
n
numerous winding variants adjust
at U constant
electrical input power (voltage,
current of power supply)
thick wire
mechanical output power
(speed, torque)
thin wire
M
speed-torque gradient
basically constant for the winding series
constant filling factor: a constant amount of copper fills the air gap
Characteristics
Values at nominal voltage
describe the special working points:
at rated voltage UN
at rated current IN
No-load operating point
n
– resulting no-load speed n0
– resulting no-load current I0
rated working point
– resulting rated speed nN
– resulting rated torque MN
Motor at stall
– resulting stall torque MH
– resulting starting current IA
M
Values at nominal voltage
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5
© 2013, maxon motor ag
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5
32. maxon Motor Data and Operating Ranges
drive seminar
Thermal motor data
plastic
plate
describe the motor heating and thermal limits
depend strongly on mounting conditions
standard mounting:
horizontal
mounting
heating and cooling
– thermal resistance housing-ambient Rth2
– thermal resistance winding-housing Rth1
– thermal time constant of winding tthW
free convection
at 25 °C ambient
temperature
– thermal time constant of motor tthS
temperature limits
– ambient temperature range
– max. winding temperature Tmax
Specifications
Mechanical motor data
describe maximum speed and the properties of bearings
max. permissible speed
– limited by bearing life considerations (EC)
– limited by relative speed between collector and
brushes (DC)
axial and radial play
– suppressed by a preload
axial and radial bearing load
F5
– dynamic: in operation
– static: at stall
axial press fit force
(shaft supported)
l
Fd
d
Specifications
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6
© 2013, maxon motor ag
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6
33. maxon Motor Data and Operating Ranges
drive seminar
maxon standard tolerances
Sources
– winding resistance
– magnetic properties
– friction and losses
n
±7%
±8%
Results
1.1
1.0
0.9
– general tolerance level
– tolerance in no-load current
– tolerance in no-load speed
weaker magnet =>
stronger magnet =>
0.86
1.0
1.16
5 to 10 %
± 50 %
± 10 %
enhanced n0
reduced n0
M
Values at nominal voltage
Influence of temperature
temperature coefficients
Cu
AlNiCo
- 0.02 % per K
Ferrite
- 0.2
% per K
NdFeB
temperature
+ 0.39 % per K
- 0.1
% per K
resistance
magnetic properties
R: + 19.5 %
kn + 5 % (no-load speed)
example: RE motor
DT = + 50K
kM - 5 % (more current!)
stall torque MH : - 22 %
Values at nominal voltage
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7
© 2013, maxon motor ag
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7
34. maxon Motor Data and Operating Ranges
drive seminar
Motor limits: operation ranges
Speed
n
nmax
continuous
operation
- higher ambient temperature
- heat accumulation
short term
operation
torque M
current I
MN
IN
- lower ambient temperature
- good heat dissipation
Operating Range
Short-term operation overload
motor may be overloaded for a short time and repeatedly
– limit: max. permissible winding temperature
– depends on thermal time constant of winding tW and amount
of overload
overload
duration
5tW
4tW
3tW
2tW
continous
operation
1tW
thermally
prohibitted
short term
operation
permissible
short term
operation
torque M
load
MN
2MN
3MN
4MN
Operating Range
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8
© 2013, maxon motor ag
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8
35. Examples for motor and drive selection
drive seminar
Examples for motor and
drive selection
Continuous operation
Cyclic operation
maxon selection program
© 2012 maxon motor ag, Sachseln, Switzerland
Systematic selection process
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
Page
step 5+6
step 7
motor type sensor
winding
controller
1
© 2013, maxon motor ag
Page
1
36. Examples for motor and drive selection
drive seminar
Step 5: Motor selection conveyor belt
selecting the motor type
selection of the winding
planetary Gearhead GP 32 A
– reduction
51:1
Motor requirements (key values)
– Speed
5100 min-1
– average torque
70 mNm
– maximum torque
about 75 mNm, 1s
Selection criteria motor type
Commutation
(Service life)
Sensor
Shaft
Bearing
(Service life)
Electrical
connection
Ambient
condition
Page
2
© 2013, maxon motor ag
Page
2
37. Examples for motor and drive selection
drive seminar
Motor type selection
Combination with
maxon Modular System
+ motor
A-max 32
RE-max 29
(continuous torque)
max. torque
max. permissible
speed
RE 35, 90W
A-max 26
Nominal torque
RE 30, 60W
RE 25, 20W
n
+ motor
RE 25, 10W
selected gearhead
EC 32, 80W
MRMS MN
continuous
operation
nmax
short term
operation
deceleration
acceleration
MN
M
Motor type selection
according
maxon
modular
system
motor type
MN suited?
RE 25
< 30 mNm
too weak
A-max 26
< 18 mNm
too weak
RE-max 29
< 30 mNm
too weak
RE 30
ca. 80 mNm
RE 35
100 mNm
strong
EC 32
< 45 mNm
too weak
A-max 32
< 45 mNm
too weak
EC 32 flat
< 10 mNm
too weak
Page
3
© 2013, maxon motor ag
good
Page
3
38. Examples for motor and drive selection
drive seminar
Step 6: Winding selection
Goal: Reach the required speed at maximum possible motor
voltage under maximum load
for a given motor size (motor type) this means: sufficiently high
speed constant
n0,theor
nmot
n
Mmot
M
n0,theor nmot
speed n
n
k n k n,theor 0,theor
Umot
nmot, Mmot
speed-torque line high enough
for the required load speed
speed-torque line
too low for the
required load speed
torque M
Mmot
Example: Conveyor belt for samples
n
n
Mmot 5100 9 70 5700 min 1
M
n
5700
rpm
k n k n,theor 0,theor
270
Umot
21
V
n0,theor nmot
[rpm]
5700
5100
select motor 310007:
– speed constant
kn = 369 min-1/V
needed current
– with torque constant kM
Imax
70 mNm
M
Page
Mmax
I0
kM
70
0.15 2.8 A
25.9
4
© 2013, maxon motor ag
Page
4
39. Feedback and Motion Control
maxon drive seminar
Feedback and
Motion Control
Feedback systems
– Specifically: Encoder
Properties of controllers
– control value
– performance, motor type
– communication, signal processing
© 2012 maxon motor ag, Sachseln, Switzerland
Motion Control System Overview
Power Supply
CAN
Motion Controller
I/O
Supervisor / Master
(PLC / PC)
v(t), F(t)
Motor
Gearhead
Encoder
Load
Page
1
© 2013, maxon motor ag
Page
1
40. Feedback and Motion Control
maxon drive seminar
Sensors in feedback systems
Power
Motion
Controller
Closed loop
system for speed
or position
Commands,
Set values
Control parameter
Position
∆𝑝𝑜𝑠
∆𝑡
Speed,
Direction
Speed, Direction
Feedback, sensor
Encoder
Hall sensors
Resolver
DC Tacho
IxR
Drive component: Controller
Page
2
© 2013, maxon motor ag
Page
2
41. Feedback and Motion Control
maxon drive seminar
mmc product families
controller
family
EPOS
ESCON
current control
control loops
speed control
position control
system
architecture
commanded by
master system
setup
feedback
sensors
commanded by digital
and analog inputs
graphical user interface (Studios)
needed feedback:
• EC: encoder and Hall
sensor
• DC: encoder
possible feedback:
• encoder
• Hall sensor (EC)
• DC tacho (DC)
Configuration – EPOS/ESCON Studio
Communication
Bus types
Baud rates
…
Motor type
DC
BLDC
Commutation
Feedback type
Encoder (resolution)
Hall sensor
DC Tacho
Configuration
Graphical User
Interface
(GUI)
Inputs / Outputs
Stop
Direction
Enable - disable
Operation mode
Current control
Speed control
Position control
Ready
Speed comparator
….
Page
3
© 2013, maxon motor ag
Page
3
42. Selection example – step by step
Drive seminar
Selection of
drive components
The systematics of the
drive selection on a
practical application
example
© 2013 maxon motor ag, Sachseln, Switzerland
Page
1
© 2013, maxon motor ag
Page
1
43. Selection example – step by step
Drive seminar
Step 1: Situation Analysis
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
step 5+6
step 7
motor type sensor
winding
controller
What information is missing?
operating mode, motion profile
– acceleration
– inertias (rollers, belt)
current power supply
control concept, variable
– set value
– movement quality
Given:
pulley diameter
maximum mass on belt
coefficient of friction on
support
friction force (empty belt)
feed velocity
supply voltage
maximum length / diameter
service life
environmental conditions
– emissions
Page
2
© 2013, maxon motor ag
100 mm
15 kg
approx. 0.2
approx. 30 N
0.5 m/s
24 V
Page
2
44. Selection example – step by step
Drive seminar
Step 2: Load Requirements
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
step 5+6
step 7
motor type sensor
winding
controller
Conveyor belt: load data
Maximum load speed
𝑣 𝐿 = 0.5
𝑚
𝑠
feed force
𝐹𝐿 = 𝐹 𝑅 +
acceleration
𝜇
∙ 𝑚 ∙ 𝑔 = 30 + 0.2 ∙ 15 ∙ 9.8 ≅ 60𝑁
𝐹𝑎 = 𝑚 ∙
∆𝑣 𝐿
0.5
= 15 ∙
= 15𝑁
∆𝑡
0.5
power
𝑃 𝐿 = 𝑣 𝐿 ∙ 𝐹 𝐿 = 0.5 ∙ 60 = 30𝑊
Page
3
© 2013, maxon motor ag
Page
3
45. Selection example – step by step
Drive seminar
Conveyor belt: Key values load
Looking for a drive that can accomplish the following:
maximum velocity
average force
maximum force
duration of Fmax
vmax
= 0.5 m/s
Feff
= approx. 60 N
Fmax
= approx. 80 N
Δtmax = 0.5 s
v
0.5 m/s
60 N 80 N
F
Step 3: Drive
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
Page
step 5+6
step 7
motor type sensor
winding
controller
4
© 2013, maxon motor ag
Page
4
46. Selection example – step by step
Drive seminar
Conveyor belt: load data gear
maximum speed
average torque
maximum torque
𝑛 𝐺 = 30 ∙ 𝜔 = 30 ∙
𝜋
𝜋
𝑣𝐿
𝑑
2
= 30 ∙
𝜋
0.5
≅ 100𝑟𝑝𝑚
0.05
𝑑
0.1
∙ 𝐹𝐿 =
∙ 60 = 3.0𝑁𝑚
2
2
𝑑
0.1
= ∙ 𝐹 𝑚𝑎𝑥 =
∙ 80 = 4.0𝑁𝑚
2
2
𝑀 𝐺,𝑒𝑓𝑓 =
𝑀 𝐺,𝑚𝑎𝑥
Example conveyor belt: Key values
Looking for a drive that can accomplish the following:
maximum speed
average torque
maximum torque
duration of Mmax
nG,max = 100 rpm
MG,eff
= approx. 3.0 Nm
MG,max = approx. 4.0 Nm
Δtmax
= 0.5 s
3.0
4.0 Nm
Page
5
n
100 rpm
© 2013, maxon motor ag
M
Page
5
47. Selection example – step by step
Drive seminar
Step 4: Gearhead selection
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
step 5+6
step 7
motor type sensor
winding
controller
Step 4: Gearhead selection
Looking for a drive that can accomplish the following:
maximum speed
average torque
maximum torque
duration of Mmax
nG,max = 100 rpm
MG,eff
= approx. 3.0 Nm
MG,max = approx. 4.0 Nm
Δtmax
= 0.5 s
?
Page
6
© 2013, maxon motor ag
Page
6
48. Selection example – step by step
Drive seminar
Limits gear selection
torque
MN > MG,eff
output
speed n
Reduction out of input and
output speeds:
𝑖<
nmax,L
𝑛 𝑚𝑎𝑥,𝑖𝑛
𝑛 𝑚𝑎𝑥,𝐿
nmax,in
continuous
operation
nmax,L
short term
operation
MN
Mmax
output
torque M
Selection Guide maxon Gear
3 Nm
Page
7
© 2013, maxon motor ag
Page
7
49. Selection example – step by step
Drive seminar
Conveyor belt: Gearhead selection
planetary gearhead
– continuous torque
– max. input speed
– max. reduction
– selected reduction
– efficiency ηG
GP 32 C
3 Nm (at least 2 stages)
8000 rpm
𝑛 𝑚𝑎𝑥,𝑖𝑛 8000
=
= 80: 1
𝑛 𝑚𝑎𝑥,𝐿
100
𝑖<
79:1
70 %
requirements motor (key values)
– speed
𝑛
– torque
𝑀 𝑚𝑜𝑡 =
𝑚𝑜𝑡
= 𝑛 𝐺 ∙ 𝑖 = 100 ∙ 79 = 7900 𝑟𝑝𝑚
𝑀𝐺
3.0
=
= 54 𝑚𝑁𝑚
𝑖 ∙ 𝜂 𝐺 79 ∙ 70%
Conveyor belt: Key values motor
Looking for a motor that can accomplish the following:
maximum speed
average torque
maximum torque
duration of Mmax
nmax
= 7900 rpm
Meff
= 54 mNm
Mmax = 72 mNm
Δtmax = 0.5 s
n
7900 rpm
54
72 mNm
Page
8
© 2013, maxon motor ag
M
Page
8
50. Selection example – step by step
Drive seminar
Step 5+6: Selection motortyp & winding
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
step 5+6
step 7
motor type sensor
winding
controller
Step 5: Motor type selection
Motor type according
to modular system
RE 25
RE 30
Nominal torque
MN > 54 mNm
RE 35
A-max 26
A-max 32
RE-max 29
EC 32
EC-max 22, 25W
max. permissible speed > 7900 rpm
continuous
operation
short term
operation
EC-max 30, 40W
EC-4pole 22
EC flat 32
EC-i 40
MN
Page
9
© 2013, maxon motor ag
M
Page
9
51. Selection example – step by step
Drive seminar
Further selection criteria motor type
Commutation
(Service life)
Sensor
Shaft
Bearing
(Service life)
Electrical
connection
Ambient
condition
Conveyor belt motor type
Motor type according Nominal
to modular system
torque MN
suitability
RE 25
< 30 mNm
Too weak, with brushes
RE 30
ca. 90 mNm
OK, but with brushes
RE 35
ca. 100 mNm
strong, but with brushes
A-max 26
< 18 mNm
too weak, with brushes
A-max 32
< 45 mNm
too weak, with brushes, nmax= 6000 rpm
RE-max 29
< 30 mNm
too weak, with brushes
EC 32
< 45 mNm
too weak
EC-max 22, 25W
< 23 mNm
too weak
EC-max 30, 40W
< 34 mNm
too weak, (60W version => 63 mNm)
EC-4pole 22
< 64 mNm
OK, only 120W version, builds long
EC flat 32
< 23 mNm
too weak
EC-i 40
< 70 mNm
OK
Page
10
© 2013, maxon motor ag
Page
10
52. Selection example – step by step
Drive seminar
Step 6: Winding selection
Goal: Reach the required speed at maximum possible motor voltage
under maximum load
for a given motor size (motor type) this means: sufficiently high speed
constant
∆𝑛
∙ 𝑀 𝑚𝑎𝑥
∆𝑀
𝑛0,𝑡ℎ𝑒𝑜𝑟
𝑘 𝑛 > 𝑘 𝑛,𝑡ℎ𝑒𝑜𝑟 =
𝑈 𝑚𝑜𝑡
speed n
𝑛0,𝑡ℎ𝑒𝑜𝑟 = 𝑛
n0,theor
nmot, Mmot
nmot
𝑚𝑜𝑡
+
speed-torque line high enough
for the required load speed
speed-torque line
too low for the
required load speed
torque M
Mmot
Example: Conveyor belt for samples
n
∆𝑛
∙ 𝑀 𝑚𝑎𝑥 = 7900 + 17 ∙ 72 ≅ 9100
∆𝑀
𝑛0,𝑡ℎ𝑒𝑜𝑟 9100
𝑚𝑖𝑛−1
𝑘 𝑛 > 𝑘 𝑛,𝑡ℎ𝑒𝑜𝑟 =
=
= 415
𝑈 𝑚𝑜𝑡
22
𝑉
𝑛0,𝑡ℎ𝑒𝑜𝑟 = 𝑛
[rpm]
9100
𝑚𝑜𝑡
+
7900
select motor
311537:
– speed constant kn = 497 rpm/V
needed current
– with torque constant kM
𝐼 𝑚𝑎𝑥 =
72 mNm
M
=
Page
𝑀 𝑚𝑎𝑥
+ 𝐼0
𝑘𝑀
72
+ 0.166 = 3.9 A
19.2
11
© 2013, maxon motor ag
Page
11
53. Selection example – step by step
Drive seminar
Step 7: Sensor and controller
Step 1
overview
situation
power
communication
ambient
condition
step 2
load
step 3
drive
step 4
gearhead
Page
step 5+6
step 7
motor type sensor
winding
controller
12
© 2013, maxon motor ag
Page
12