3. Abstract
Buck-boost converter connected in between the input DC source and
three phase bridge inverter, used for minimizing the commutation
torque ripples in Permanent Magnet Brushless DC Motor is presented
in this project.
Torque during the commutation period depends on phase current
which is not undergoing commutation, so by controlling it, torque
ripple can be minimized.
Moreover, a greater DC link voltage is needed during the commutation
time period in comparison to the normal conduction period.
The Buck-boost converter operates in boost mode in commutation
period for stepping up the DC voltage to the inverter.
A simple mode switching circuit is employed to amend the output
modes of the Buck-boost converter in normal and commutation time
intervals.
Simulation studies of this topology are carried out in MATLAB/
Simulink environment.
4. Introduction
This project presents the design and implementation of neural
network controller for reducing torque ripples in brushless DC
(BLDC) motor drive with trapezoidal back-emf.
The performances of the proposed neural network controller are
compared with the corresponding fuzzy PI controller and
conventional PI controller.
Simulation results are used to show the abilities and
shortcomings of the proposed speed regulation scheme for
brushless dc motor which is considered as a highly nonlinear
dynamic complex system.
Buck-boost converter connected in between the input DC source
and three phase bridge inverter, used for minimizing the
commutation torque ripples in Permanent Magnet Brushless DC
Motor is presented in this project.
5. Introduction
Torque during the commutation period depends on phase
current which is not undergoing commutation, so by controlling
it, torque ripple can be minimized.
Moreover, a greater DC link voltage is needed during the
commutation time period in comparison to the normal
conduction period.
The Buck-boost converter operates in boost mode in
commutation period for stepping up the DC voltage to the
inverter.
A simple mode switching circuit is employed to amend the
output modes of the Buck-boost converter in normal and
commutation time intervals.
Simulation studies of this topology are carried out in
MATLAB/Simulink environment.
6. PROBLEM STATEMENT
To achieve desired level of performance the motor requires
suitable speed controllers. In case of permanent magnet
motors, usually speed control is achieved by using
proportional- integral (PI) controller. Although
conventional PI controllers are widely used in the industry
due to their simple control structure and ease of
implementation, these controllers pose difficulties where
there IS some control complexity such as nonlinearity, load
disturbances and parametric variations. Moreover, PI
controllers require precise linear mathematical models. As
the PMBLDC machine has nonlinear model, the linear PI
may no longer be suitable.
7. LITERATURE REVIEW
The BLDCM drive system’s commutation torque pulsation is
mostly responsible for aberrant vibration, undesired speed
fluctuations, and sound.
To maximize BLDCM drive system torque performance, it is
necessary to minimize the commutation torque pulsation.
A composite switching mode has been proposed to reduce the
torque ripple at all speeds during commutation periods during
the inverter’s 120° and 180° electrical conduction modes.
A variable input voltage solution for efficient torque ripple
reduction during the BLDCM’s freewheeling period was reported
in.
With this approach, the Laplace transformation was used to
predict the freewheeling zone and the ideal voltage.
9. BLOCK DIAGRAM DESCRIPTION
The IPM type used in these studies is PEC16DSM01, its
rated voltage is 1200V, rated current is 25A, the control
voltage is 20V and the switching frequency is 20 KHz. The
experimental setup block diagram of BLDC motor diagram
consists of following systems.
1. Intelligent power module
2. Voltage and current sensor
3. Signal conditioner
4. Protection circuit
5. Opt coupler
6. 3φ diode bridge rectifier
7. Speed sensor
8. Frequency to voltage converter
10. METHODOLOGY
The Artificial Neural Network Controller Model
The controller is represented as a nonlinear map
between the inputs and outputs. Depending on a
specific plant, the map (in the form of a network) can
be trained to implement any kind of control strategy. A
neuro-controller (neural networks based control
system) performs a specific form of the adaptive
control with the controller taking the form of a multi-
layer network and the adaptable parameters being
defined as the adjustable weights.
11. METHODOLOGY
Buck-Boost Converter Model
The configuration comprises of a Buck-boost converter
and a mode selection circuit. During commutation
period a higher DC voltage is required compared to the
normal conduction period. A Buck-boost converter is
inserted between DC source and inverter to control the
DC link voltage. Mode switching circuit effectively
handles the operating approach of the converter in the
commutation interval to boost the input of the
inverter.
14. ADVANTAGE
High dynamic response
High efficiency
Long operating life
Noiseless operation
Higher speed ranges
15. APPLICATIONS:
BLDC motors find applications in every segment of the
market. Such as, appliances, industrial control,
automation, aviation and so on. We can categorize the
BLDC motor control into three major types such as
Constant load
Varying loads
Positioning applications
16. CONCLUSION
On the control side of BLDC motors, this article examines
various control methodologies for decreasing torque ripples.
It is either the motor’s design or the power inverter supply that
causes the pulse torque movements to deviate from ideal
conditions, resulting in non-ideal current waveforms.
BLDC motor torque pulsations are generated by unnecessary
torque pulsations in the drive, which causes oscillations in the
motor speed and resonances in the motor, resulting in noise and
vibration.
There is a ripple in the torque produced by brushless DC motors
(BLDCM) when switching-in and switching-out occurs in
different phases. It would be possible to reduce ripple in the
communication torque if the slew rates were the same.
17. REFERENCES
T. M. Jahns and W. L. Soong, "Pulsating torque minimization
techniques for permanent magnet AC motor drives-a review", IEEE
Trans. on Industrial Electronics, vol. 43, 321-330, 1996.
Z. Cunshan and B. Dunxin, "A PWM control algorithm for eliminating
torque ripple caused by stator magnetic field jump of brushless DC
motors", in Intelligent Control and Automation,2008. WCICA 2008.
The 7th World Congress on, 2008, 6547-6549.
K. Wei, Kun, H. Chang-sheng, Z. Zhong-chao, "A novel PWM scheme
to eliminate the diode freewheeling in the inactive phase in BLDC
motor", Frontiers of Electrical and Electronic Engineering in China,
vol. 1, 194-198, 2006.
X. Zhang and B. Chen, "The different influences of four PWM modes
on the commutation torque ripples in sensorless brushless DC motors
control system," in Electrical Machines and Systems, ICEMS 2001.
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