Actuators
relays & motors
References
• Takashi Kenjo, Akira Sugawara, Stepping
motors and their microprocessor controls,
Oxford University Press, USA , 1995
• T. R. Kuphaldt, Lessons In Electric Circuits,
Volume II – AC, 6th Edition, 2007
(http://www.faqs.org/docs/electric/AC/index.html)
• J. Przepiorkowski, Silniki elektryczne w
praktyce elektronika, BTC
Outline
• relays
– mechanical
– electronic relays (SSR)
• stepper motors ( + microsteps)
• ac motors
1
Relays
SPST
SPDT
Single(Double)Pole
Single(Double;Triple)Throw
DPST
DPDT
CO – centre off/change over
example
SPTT=SPCO
Relay
reed relay
2
Relays
AC relay
Relays - types
• Regular
• Latching (bistable)
• Reed relay
– (mercury wetted)
• polarized relay
• contactor
• solid state relay
– transistor
– triac
– thyristor
• Other (safety switches, over current,……)
3
Relay - diagram symbol
Ohm’s low for inductance
UL = L
dI
dt
U L = X LIL =
1
IL
iωC
TIPS:
•higher voltage applied – faster changes of current
•fast changes in current – higher voltage induced
•when current change direction – voltage change polarity
•positive voltage applied – current increased
•current decreased – negative voltage induced
Switching on and off an inductor
IL
UL
UCE
UCE
UL
VCC
4
Relay – spark discharge
UL
c
Vc
High voltage can destroy
transistor and relay
and can be very dangerous !!!!
R
UCE
+V
GND
Switching on and off an inductor
IL
protection diode;
flyback diode;
clamp diode;
UL
UCE
UCE
UL
VCC+UD
VCC
- UD
Switching on and off an inductor
Vcc
IL
R
UL
VCC+UD+UZ
UCE
+V
GND
VCC+UD
UCE
UL
VCC
- UD-UZ
- UD
5
Switching on and off an inductor
- series resistor influance
Vcc
IL
R
UL
VCC+UD+UZ
UCE
+V
GND
VCC+UD
UCE
UL
VCC
- UD
- UD-UZ
Decreasing rise time
(off to on time)
1. Increase Vcc
2. add Rs to preserve Imax
3. result=> higher power
dissipation
Decreasing rise time with current limit
IL
6
Driving relays and motors
I<=1A
Driving relays and motors
Vcc>Ucc
R
Ucc
R1
BDX…
74HC04
Darlington array ULN2004
http://focus.ti.com/lit/ds/symlink/uln2004a.pdf
7
Driving relay/motor
with MOSFET and IGBT
MOSFET
BUZ…
IRF…..
1-30A…
IGBT
..10-300A…
Solid State Relays (SSR)
Solid State Contractor (SSC)
SSR of different types
can be used for AC driven mechanical relays
•Usually small power
but can drive any
type of load
(including induction)
•AC and DC
applications
•Be carfull with inductive load – the load can
be not switched off !!!
•AC applications only
8
High power SSR
RC snubber
<30V – other load
>30V – over contacts
Protection elements:
•capacitive load
•chock
•NTC,
•PTC( in series)
•induction load
•surge arrester
•varistor
•transil
RC snubber
9
Motors
PMDC
brushed
Electric motors
•
AC motors
•
DC motors
–
–
squirrel cage (3 phase, shade pole, cpacitor, split phase)
synchronous
–
Permanent magnet DC
–
Universal motors
•
•
•
•
Ironless brush motor
series
shunt
compound wound
•
BrushLess DC (BLDC)
•
Step motors
–
–
–
–
–
•
2 phase
3 phase
reluctance
permanent magnet
hybrid
Linear (Voice Coil Motor – VCM)
Motors properties
Type
Advantages
Disadvantages
Typical Application
Typical Drive
AC Induction
(Shaded Pole)
Least expensive
Long life
high power
Rotation slips from
frequency
Low starting torque
Fans
Uni/Poly-phase AC
AC Induction
(split-phase capacitor)
High power
high starting torque
Rotation slips from
frequency
Appliances
Stationary Power Tools
Uni/Poly-phase AC
Universal motor
High starting torque,
compact, high speed
Maintenance (brushes)
Medium lifespan
Drill, blender, vacuum
Uni-phase AC or Direct DC
cleaner, insulation blowers
AC Synchronous
Rotation in-sync with freq hence no slip
More expensive
long-life (alternator)
Industrial motors
Clocks
Audio turntables
tape drives
Uni/Poly-phase AC
Stepper DC
Precision positioning
High holding torque
High initial cost
Requires a controller
Positioning in printers and
floppy drives
DC
Brushless DC
Long lifespan
low maintenance
High efficiency
High initial cost
Requires a controller
Hard drives
CD/DVD players
electric vehicles
DC
Brushed DC
Low initial cost
Simple speed control
Maintenance (brushes)
Medium lifespan
Treadmill exercisers
automotive motors (seats,
blowers, windows)
Direct DC or PWM
Pancake DC
Compact design
Simple speed control
Medium cost
Medium lifespan
Office Equip
Fans/Pumps
Direct DC or PWM
10
Squirrel cage
Squirrel cage – drivig inverter
Inverter
IRAMS10UP60A
by International Rectifier
11
Shaded pole induction motor
advantages
•Very cheap and reliable
•Extremely rugged in nature
•Easy to construct
disadvantages
•Low starting torque
•Low efficiency
•highcopper loss is
Shaded pole
induction
motor
Capacitor Run
Permanent Split Capacitor(PSD Motor)
12
Split Phase Induction Motor
Induction Motor control
by means of slip control
Induction Motor control by means of slip control
13
Synchronous motor
Lessons In Electric Circuits, Volume II – AC By Tony R. Kuphaldt, Sixth Edition, last update July 25, 2007
Multipole synchronous motor
The inductionf or self starting
and the bar magnet as
synchronous motor
14
Synchronous motor
15
Synchronous motor
plat drive of microwave
16
DC motors
PMDC – Permanent Magnet DC
High starting torque,
compact,
high speed,
easy to controll,
cheap
Maintenance (brushes)
Medium lifetime,
Noisy
EMI emission
DC motors
PMDC – Permanent Magnet DC - controll circuit
E=const
RsI
RI I
Direction controll - H bridge
Vcc
TIPS:
BJT, MOSFET, IGBT transistors can be used,
diodes cunduct self inductance currents
MOTOR
current limit
or control
17
H bridge operation 1
Vcc
Vcc
OFF
ON
ON
OFF
OFF
OFF
OFF
OFF
slow decay
drive
H bridge operation 2
Vcc
Vcc
OFF
ON
ON
OFF
OFF
OFF
drive
OFF
OFF
slow decay
Bootstrapping
18
DC motors
PMDC – Permanent Magnet DC -ironless (coil and disc) -pancace
TIP:
very little momentum – fast start
http://www.designworldonline.com/ArticleDetails.aspx?id=1973
http://www.kurz-motor.de/eprodukteframetextgleichstromscheibenlaeufer.htm
Permanent magnet replaced by
electromagnet – universal motor
series motor
shunt motor
compound motor
differential compound m.
Torque vs. speed
speed
differential
1
shunt
series
compound
0
0
1
torque
19
Universal motor – driver /
controller
M
Tips:
1. voltage controlled
2. direction can be changed
by switchin stator or rotor
winding
3. showed example is the
most simple
Universal motor – driver/controller
more sophisticated example
From Motorola materials
(now ON Semiconductor)
step motors- bi/uni-polar
bipolar winding
H bridge needed
unipolar winding
single swich
20
(2 phase) step motor internal conections
4 wires
(bipolar only)
6 wires
(bipolar handicaped/
/unipolar)
8 wires
(bipolar/unipolar)
5 wires
(unipolar only)
Unipolar/Bipolar step motor
driving
Step motor – reluctance motor
Lessons In Electric Circuits, Volume II – AC By Tony R. Kuphaldt, Sixth Edition, last update July 25, 2007
21
Permanent magnet motor
wave driving
Lessons In Electric Circuits, Volume II – AC By Tony R. Kuphaldt, Sixth Edition, last update July 25, 2007
Permanent magnet motor
full step driving
Lessons In Electric Circuits, Volume II – AC By Tony R. Kuphaldt, Sixth Edition, last update July 25, 2007
Permanent magnet motor
half step driving
Lessons In Electric Circuits, Volume II – AC By Tony R. Kuphaldt, Sixth Edition, last update July 25, 2007
22
Full/microstep
driving
1,3,5,7 – phase A
2,4,6,8 – phase B
Hybrid motor
Step =
360 deg
N teeth ⋅ N phases
LMD18245 3A, 55V DMOS Full-Bridge
Motor Driver – National Instrument
23
LMD18245
application
TMC246
24
DRV8811
TI
Clock
BLDC (BrushLess DC) motors
S
N
N
S
rotor
S
N
N
S
25
BLDC
1 phase
TA8420/21 BLDC 2 phase driver
LB1864 2 phase BLDC driver
26
3 phase BLDC
BLDC
BLDC
27
BLDC – bipolar driving - star
A
C
B
BLDC – bipolar driving - triangle
A
C
B
BLDC – bipolar driving - star
A
+Vcc
C
B
28
L6268 driver BLCD + VCM (ST)
Linear motor
VCM motors (hard disk head)
29
Summary
• Electromechanical relays
• SSR
• AC motors
– squirrel cage (3 phase, shade pole, capacitor, split phase)
– synchronous
• DC motors
– Permanent magnet DC
– Universal motors
• Brushless DC (BLDC)
• Step motors
• Linear (Voice Coil Motor – VCM)
30