permanant magnet synchronous motor
DESCRIPTION
SPECIAL MACHINES - PMSMTRANSCRIPT
PERMANENT MAGNET SYNCHRONOUS PERMANENT MAGNET SYNCHRONOUS MOTOR AND ITS DRIVESMOTOR AND ITS DRIVES
Presented By: Prof. B.AdhavanAssistant Professor
Dept. of Electrical and Electronics Engg [PG]
Email: [email protected] No: 9994869720
1
Sri Ramakrishna Engineering College(An Autonomous Co-education Institution, approved b y AICTE,
Re Accredited by NBA, Affiliated to Anna University Coimbatore)Vattamalaipalayam, NGGO Colony (Post)
Coimbatore - 641 022, TAMILNADU.
Mobile No: 9994869720
OUTLINEOUTLINE
CONSTRUCTION & PRINCIPLE OF OPERATION OF CONSTRUCTION & PRINCIPLE OF OPERATION OF PMSMPMSM
TYPESTYPES OFOF PMSMPMSM PMSMPMSMVsVs BLDCBLDC
TORQUETORQUE--SPEEDSPEEDCHARACTERISTICSCHARACTERISTICS
2
TORQUETORQUE--SPEEDSPEEDCHARACTERISTICSCHARACTERISTICS APPLICATIONSAPPLICATIONS CONTROLCONTROL METHODSMETHODS
Types of Electric Motors
3
Permanent Magnet Synchronous Motor (PMSM) willhave the same operating and performance characteristics assynchronous machines operating at synchronous speed, asingle or polyphase source of ac supplying the armaturewindings,
CONSTRUCTION & OPERATION
4
windings,
Absence of slip rings and field windings.
Parts of a Motor
1. End Bell Fastners2. Shaft Key & Keyways3. Bearing & Brushings4. End Ball Flanges5. Identification Plates5. Identification Plates6. Wire Warnish7. Commutators8. Brush Holders9. Laminations10. Conduit Connection Box11. Magnets (Ferrites)
Brushless Motor Components
Brush Type Motor Components
PMSM MOTOR TRANSVERSESECTION
STATORSTATOR Stator laminations –Axial airgap Armature windings are double layered and lap
wound.
CONSTRUCTION
7
wound. Single phase or Poly phase windings –
connected in star or delta.
Synchronous machinesare classified according to their
Rotor Configurations
Rotor Types
ROTOR
8
Peripheral or Surface
Interior
Claw-pole
Transverse
ROTOR ConfigurationROTOR Configuration--PeripheralPeripheral
9
PM flux developed is radial.
ROTOR ConfigurationsROTOR Configurations
10
PM flux developed is radial in interior PM flux developed is Circumferential in Transverse
•• PMs are discs shaped and magnetized axially.• Periphery of the discs extends like claws or lundell poles.• Set of equally spaced claws on each disc alternates to north and south poles.
ROTOR ConfigurationsROTOR Configurations
11
PM Motor Types
Based on Wave shape of their induced emf1) Sinusoidal (PMSM)2) Trapezoidal (BLDC)
12
13
Sinusoidal distribution of magnet flux in the air gap
Sinusoidal current waveforms Sinusoidal distribution of stator conductors.
Sinusoidal (PMSM)
14
Trapezoidal (BLDC) Rectangular distribution of magnet flux in the
air gap Rectangular current waveform Concentrated stator windings.
Rotor is carrying a constant magnetic field created either by permanent magnets or current fed coils
The interaction between the rotating stator flux, and the rotor flux produces a torque which will cause the motor to rotate.
Rotor fieldA`
B
C`
AB`
C N
S
φ
Stator field
S
N
Theory of operation:
15
The rotation of the rotor in this case will be at t he same exact frequency as the applied excitation to the rotor.
This is synchronous operation.
A
phaseper pair polesmotor :p
(Hz)frequency supply AC :
(r.pm) .60
:(rad/s) speedRotor
f
p
fgives
p
ω=Ω Example: a 2 poles pair synchronous motor will run at 1500 r.pm for a 50Hz AC supply frequency
How It Works
When electric current passes through a coil in a magnetic field, the magnetic force produces a torque which turns the motor.
Force in Motor:
F=ILBF=ILBF = Force
B = Magnetic Field
L = Length of Conductor
I = Current in Conductor
Torque in Motor:
T = IBA sin θA = LW
L = Length of Winding
W = Width of Winding
PRINCIPLE OF OPERATION
BLPM SNW motor carries a 3 phase winding connected to a dc
supply through an electronic commutator.
The voltage available at the input terminals of the armaturewinding
is assumed to be sinusoidally varying 3 phase balanced voltage.
17
Electronic commutator acts as an ideal inverter, whose freqis
influenced by rotor speed.
Under this condition, revolving magnetic field is set up in the air
gap.
Its flux density is sine distributed.
Synchronous operation
18
Synchronous operation
19
Synchronous operation
20
Synchronous operation
21
Synchronous operation
22
Synchronous operation
23
Advantages of PM machines
They have high torque to inertia (lower weight). That is better dynamic performance than conventional one.
High power density. High efficiency (That is no current in the rotor means
24
High efficiency (That is no current in the rotor means no copper loss) and reliability.
Avoidance of brushes and slip rings makes the machine less audible noise,
Longer life, sparkless (no fire hazard) and high speed.
Efficient heat dissipation.
Loss of flexibility of field flux control Cost permanent magnets is high They have complex control. There is a possibility of demagnetization of the
Disadvantages of PM machines
25
There is a possibility of demagnetization of the rotor magnet.
If demagnetization occurs, there will be a reduction of torque production.
There is a problem of maintenance of rotor magnet.
BLDC Vs. PMSMBLDC
Synchronous machine
Fed with direct currents
Trapezoidal BEMF
PMSM
• Synchronous machine
• Fed with sinusoidal currents
• Sinusoidal BEMF
• Continuous stator flux position
26
Stator Flux position commutation each 60 degrees
Only two phases ON at the same time
Torque ripple at commutations
• Continuous stator flux position variation
• Possible to have three phases ON at the same time
• No torque ripple at commutations
TORQUETORQUE--SPEED SPEED CHARACTERISTICSCHARACTERISTICS
27
•Maximum torque is developed in PMSM by varying
the frequency from 0 to f0 .
•Further increase in frequency, the torque gets reduced
and goes to 0 at a frequency fd .
Washing machines Electrical power steering Industrial drive Servo drives
PMSM Motor Applications
28
Servo drives Electric vehicle traction drive Automotive applications Refrigerator Air conditioning Fan
HighHigh speedspeed andand highhigh powerpower drivesdrives forfor
CompressorsCompressors
BlowersBlowers
PMSM Motor Applications
29
BlowersBlowers
ConveyersConveyers
SteelSteel rollingrolling millsmills
AirAir craftcraft
PMSM DRIVE TOPOLOGY
30
PMAC
& feedback
DRIVE
180°Conduction mode of 3 Phase Inverter- For PMSM 120°Conduction mode of 3 Phase Inverter-For BLDC
32
180°Conduction
For this mode of operation, each device conducts 180 degrees.
The sequence of firing is: 123, 234, 345, 456, 561, 612. The gating signals are shifted from each other by 60
degrees.
Waveforms for 180 °°°° Conduction
34
120° Conduction
In this mode, each transistor conducts for 120 degrees.
The sequence of firing is: 61, 12, 23, 34, 45, 56, 61.56, 61.
35
Waveforms for 120 °°°° Conduction
36
FEEDBACK SENSORS
37
PMSM Motor Control
38
SCALAR CONTROL - Volt/Hertz
Scalar control is based on relationships validin steady state.
Only magnitude and frequency of voltage,current, etc. are controlled.The control is an open-loop scheme and
39
The control is an open-loop scheme anddoes not use any feedback loops.
The idea is to keep stator flux constant atrated value so that the motor develops ratedtorque/ampere ratio over its entire speedrange
VECTOR CONTROL
In vector control amplitude and position of a controlled space vector is considered.
Closed loop control These relationships are valid even during
40
These relationships are valid even during transients which is essential for precise torque and speed control.
Types – Field Oriented Control (FOC) Direct Torque Control (DTC)
VECTOR CONTROLVECTOR CONTROL
Electromagnetic torque developed due to the interaction of the current carrying conductor and magnetic field.
CASE 1 Flux axis is in quadrature with the armature mmf axis. Angle between the axis of the flux and the
41
Angle between the axis of the flux and the armature mmf axis is 90°.
Armature mmf axis
Field axis
CASE 2 Angle between the axis of the flux and the
armature mmf axis is different from 90°. For a BLDCSNW motor to have better steady state and
dynamic performance, it is essential that the armaturemmf axis and the axis of the PMare to be in quadrature inall operating conditions.
I = Id + IqI Direct axis Current
42
Id Direct axis CurrentIq Quadrature axis Current
Desired operating point of current is such that Id = 0.
Controlling the BLPM SNW motor considering above mentioned aspects is known as vector control of BLPM SNW motor.
Field axis
43
Armature mmf axis
SENSORED CONTROL-FOC
44Id ref = 0
SENSORLESS CONTROL-FOC
45
DTC-PMSM
46
THANK YOUTHANK YOU
47
THANK YOUTHANK YOU