Speed Control of BLDC - Copy (2)
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OFBLDC MOTOR
SPEED CONTROL
K. Sai Srikanth
BE 4/4(EEE)
1005-10-734038
Presented By
Under the supervision of..
Mr. M. V. Ramana Rao
Assistant professor
EED, UCE(A), OU
CONTENTS
Significance of BLDC motor and its veteran applications
Construction, working and analysis
Demerits of usage
Speed control of BLDC motor - briefing
Digital Signal Processing (DSP) speed control
Our future endeavors
PWM speed control
CONSTRUCTION
Stator may be a conventional 3-Ø winding or armature winding of DC motor
Power circuit
Rotor may be a permanent magnet or a electromagnet
Control Circuit Power electronic circuit in inverter configuration Rotor shaft position sensor Electronic timing device
Supply Circuit Full wave diode rectifier
Supply Circuit Control Circuit
Power Circuit
N
S
R
B
Y
1-Ø AC supply
D1
D2D3
D4
CS3 S2 S1
Electronic timing device
Rotor position sensor
WORKING
\\
N
S
Y
R
B
Y’
R’
B’
WORKING
ANALYSIS Instantiating the rotor to be displaced by Ɵ wrt phase R
Electromagnetic torque, TeR = k * iR * sin(Ɵ)
Similarly, TeY = k * iY * sin(Ɵ-120)
And, TeB = k * iB * sin(Ɵ+120)
The instantaneous currents in the phases
iR = IM * sin(Ɵ)
iY = IM * sin(Ɵ-120)
iB = IM * sin(Ɵ+120)
IM is the maximum current flowing in a phaseContd…...
The resultant torque Te = 1.5 * k * Im
Substituting… TeR = k * Im * sin2(Ɵ)
Similarly, TeY = k * Im * sin2(Ɵ-120)
And, TeB = k * Im * sin2(Ɵ+120)
The resultant torque, Te = TeR + TeY + TeB
On solving,
CONCLUSIONS
Resultant torque of BLDC motor is independent of rotor position angle
Hence by, torque can be controlled by varying the amplitude of phase winding currents
Henceforth, speed can be controlled by varying the current flow in to the phases
HALL EFFECT SENSOR
A 3-pin Transducer
Varies its output voltage in response to magnetic field
Proximity, positioning, speed detection current sensing applications
SIGNIFICANCE OF BLDC Absence of mechanical commutator and brushes
Longer period of life and efficient operation
Minimal electromagnetic interference
Rapid response even when submerged in fluids
Hybrid of synchronous motor and brushed DC motor
Low risk of explosion, Little maintenance
More torque to weight ratio
APPLICATIONS OF BLDC Robotics
Air crafts and satellite systems
Miniature applications Turn table drives for record players
Hard disk drives for computers
Low cost instruments
Small fans for cooling electronic equipment
Road Transportation
Motor drive-load control systems
Power factor improvement
DEMERITS
High installation cost
Requirement of the skilled for operation and maintenance
Complexity in design
Absence of continuous duty as in 3-Ø induction motor
RATINGS OF THE BLDC DRIVE
Motor Rating 1.2 HP 3 HP
Voltage 380 V 380 V
Rotor inertia 1.28 kg.cm2 2.8 kg.cm2
Torque constant 0.61 Nm/A 0.61 Nm/A
Peak torque 6 Nm 14 Nm
Max. Coupling torque 0.06 Nm 0.013 Nm
Max. Speed 6000 rpm 6000 rpm
Nominal Torque 1.25 Nm 3.2 Nm
Nominal Power 0.4 kW 1.0 kW
Feed back 3 V 3 V
SPEED CONTROL OF BLDC
Conventional methods
Field control
Stator flux control
Non-conventional/special methods
PWM method of control
DSP method of control
Tedious operation, involves losses
Flexible operation, Better scope of control, High η
DSP SPEED CONTROL
μ – 2407 chip
Comprises registers and flags for storing and processing the memory
The inverter switching sequence is encoded is into the registers
BLOCK DIAGRAM
Diode Rectifier Inverter
RotorShaft
Sensor
Feedback
1-ØAC SUPPLY
DSPController
TmωM
PULSE WIDTH MODULATION
PWM CONTROL
Varying the amplitude of the carrier wave the desired pulse width is obtained
Hence by, current pulses of varying magnitude(i.e., different pulse widths) are fed to the stator
Henceforth, the torque is varied and controlled desirably
SIMULATION
Depicting the desired response considering a virtual model
Software packages
PWM speed control of the virtual BLDC drive is achieved
OUR FUTURE ENDEAVORS
To study the interfacing of the BLDC drive to the DSP
Achieving the speed control and recording the results
Creating the virtual BLDC drive using MATLAB - SIMULINK
Simulating the speed response by the method of PWM control
Verifying and contrasting the characteristics from the two methods
APPLICATIONS
REFERENCES
GENERALISED THEORY OF ELECTRICAL MACHINES, Dr. P.S. Bimbhra
THEORY AND PERFORMANCE OF ELECTRICAL MACHINES, J.B. Gupta
SPEED CONTROL OF BLDC MOTOR USING MICRO-2407, Vi Microsystems pvt ltd
WIKIPEDIA - en.wikipedia.org
Queries.......
Thank You....