These slides are for having better understanding of ZETA converts and their role in Power Factor Correction PFC for Brush-less DC motors.

1. Power quality improvements in a ZETA Converter for
Brushless DC Motor Drives (BLDC)

2. Hello!
I am Rehan Younas
I am here to talk a bit about TECHNOLOGY
You may contact me at rehanyounas980@yahoo.com

3. What is a Converter?A converter is a device used for conversion of AC/DC quantities from one form to other. But in most cases
this term is reserved for converting AC voltages into DC The purpose is accomplished with the help of
Diodes, IGBTS,Thyristors and many other components.
Why Convert AC/DC at
all??
Conversion is done to meet the demand of
electrical machinary with the goal of providing
continous, harmonicless source of energy.
IEC Standard 61000-3-2
It is a standard that limits the total harmonic
distortion (THD) of supply current and power factor
(PF) at ac mains. And every electric machinery
must meet this limit for standardization.

4. Brushless DC Motor
Brushless DC (BLDC) motor is an ideal motor for low and medium power applications because of its high
efficiency, high energy density, high torque/inertia ratio, low maintenance requirement and a wide range of
speed control. It finds applications in a wide range of household appliances, industrial tools, heating,
ventilation and air conditioning and many others.
Failure of Conventional Converters…..
In a conventional scheme of diode bridge rectifier
(DBR) with high value of dc-link capacitor fed
BLDC motor drive, a high amount of harmonics
current is drawn at ac mains. This combination
draws peaky current and leads to a very highly
distorted supply current and very low PF at AC
mains.
So there is a need for
improved power factor
converters which are less
expensive and reliable.

5. ZETA ConverterThe improved power factor demand for a DBR fed Brushless DC Motor Derive entails to use a more
sophisticated converter where ZETA comes to assist…….
The family of converters is growing larger day by day with the advancement in ever changing scientific era
where machine demands better quality operation keeping the resources in mind. Zeta converter is a recent
addition to it acting as an inherent PF corrector. The main feature of its distinction is its wide range operation
with Discontinuous Current Mode operation.

6. Historical Background
Let’s talk about the need for ZETA Converters

7. “
 The conventional scheme of DBR fed BLDC failed to
meet the IEC standards.
 Ammount of distortion at AC mains, THD, low PF quality
issues were significant.
 Conventional converters were inefficacious and
expensive.
Less efficient Expensive Unreliable

8. Techniques for PFC
Two stages PFC
Converters
Efficiency is increased but It
requires higher number of
components and thus has
higher losses associated with it..
Single stage PFC
Converters
It require a single converter
for performing both tasks of
voltage control as well as
PFC operation but is less
efficient…
PFC Boost
Converters
A constant dc-link voltage is
maintained at the dc-link
capacitor of the voltage source
inverter (VSI) feeding the
BLDC motor thus requires
more sensors…

9. BASIC operation
The PFC zeta converter is designed to operate in
DICM, such that the current in input side inductor
becomes discontinuous, whereas the current in
output side inductor and the voltage across
intermediate capacitor remain in continuous
conduction for a complete switching cycle.

10. Performance Parameters
DC Link Capacitance
Constraint (Cdc)
The maximum value of dc-link
capacitor should achieve at
minimum value of dc-link
voltage with K taken as 2% of
Vdcmin.
Input Inductance
Constraint (Lin)
To achieve a discontinuous
conduction at the worst-case
scenario of maximum dc-link
voltage (i.e.Lic200), the value
of input inductor Lin, must be
selected lower than Lic200.
Output Inductance
Constraint (Lo)
The maximum current ripple in
an inductor occurs at the
maximum power and for
minimum value of supply
voltage.

11. 1
1.4
5.00%
0.74
2.6
65%
Power Factor Crest Factor THD
Comparison of Diode Bridge
Rectifier and ZETA Converter
1) ZETA Converter
2) DBR

12. Conclusions
Experimental verification, dynamic performance and
comparative analysis of proposed ZETA converter for BLDC
derive resemble with the predicted simulation results.
 A smooth control of dc-link voltage with limited inrush in
supply and stator current is obtained.
 Voltage and current stresses on the PFC converter
switch are reduced.
 The improved power quality indices have been observed
within the recommended limits of IEC 61000-3-2.

13. Credits
Dr. Bhim Singh
Vashist Bist
Indian Institute of Technology Delhi, India
Origional authors of the paper
“Power quality improvement in a ZETA
converter for saperately excited Brushless DC
motor drives”

14. References
◇Power quality improvements in a zeta converter for brushless DC motor
drives by Bhim Singh, Vishist Basu Department of Electrical Engineering,
Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India.
◇Gopalarathnam, T., Toliyat, H.A.: ‘A new topology for unipolar brushless
DC motor drive with high power factor’, IEEE Trans. Power Electron., 2003,
18, (6), pp. 1397–1404
◇Sokira, T.J., Jaffe, W.: ‘Brushless DC motors: electronic commutation and
control’ (Tab Books, USA, 1989)
◇Handershot, J.R., Miller, T.J.E.: ‘Design of brushless permanent magnet
motors’ (Clarendon Press, Oxford, 2010)

15. Thanks!
Any questions?
You can find me at:
◇ REHAN YOUNAS
◇ rehanyounas980@yahoo.com