VFD SYSTEM- Variable Frequency Drive applications

Prepared by :-
Thamizharasan k
VARIABLE FREQUENCY DRIVE

CONTENTS
1. What is Ac and Dc
2. Sine wave generation
3. What is Hz
4. What is Single phase and three phase.
5. What is starter and history
6. Type of starter
7. Explain each starter
8. What is VFD
9. Type of speed controlling method
10. Block diagram
11. Circuit diagram
12. Circuit diagram explanation
13. How its working
14. Application
15. Advantage and disadvantage
15. Troubleshoot in VFD.
16. What are the Communication in VFD.
17. Type of VFD.
18. Where is used VFD in our industry.
DURATION HRS :- 1.00 Hrs
Total Slide:-93

What is AC and DC
Alternating current
Direct current
What is Alternating current?
The current, which reverses its
direction periodically in second , is called
“Alternating Current”.
What is Direct current?
Direct current is the unidirectional
flow of an electric charge.

Sine wave generation
 A.C voltage may
be generated by rotating a coil in
a magnetic field or by rotating a
magnetic field within a stationary
coil. Induction.
 It says that whenever there is
a relative motion between the
conductor and the magnetic field
in which it is kept,an e.m.f gets
induced in the conductor

 The number of hertz (abbreviated Hz) equals the
number of cycles per second.
 Usually, the single phase voltage is 230V and the
frequency is 50Hz (depending on where you live).
What is Hz

Difference Between 1φ and 3φ Power Supplies
 Almost 90% of the electrical energy we use in our
day-to-day life is from alternating source like.
I) Our home appliances,
II)Office equipment
III)Industrial machines, etc..,
 Depending on the application, AC Power can be
delivered in either a Single Phase or a Three Phase
system.

What is Single Phase Power Supply?
 As mentioned earlier, in a Single Phase Power
Supply, the power is distributed using only two
wires called Phase and neutral.
 Since AC Power takes the shape of a sinusoidal
wave, the voltage in a single phase supply peaks
at 900 during the positive cycle and again at
2700 during the negative cycle.

.  The phase wire carries the current to
the load and the neutral wire
provides the return path of the
current.
 Since the voltage in a single phase
supply rises and falls, a constant
power cannot be delivered to the
load

What is three Phase Power Supply?
 A Three Phase Power Supply consists of three
power wires (or the three phases).
Additionally, depending on the type of the
circuit (which there are two types), you might
or might not have a neutral wire.

 In a three phase power supply system,
each AC Power Signal is 1200 out of phase
with each other. during one cycle of
3600,
This steady stream of power and ability to
handle higher loads makes a three phase
supply suitable for industrial commercial
operations.

What is Starter
 A Starter is a device that controls the use
of electrical power to equipment, usually a motor
 It is a switching device that consists of electrical
contacts
 As the name starters "start" motors. They can also
stop them, reverse them, and protect them.
 Contactors control the electric current to
the motor.

DOL Starter
Star Delta Starter
Auto Transformer starter
Soft Starter
VFD Starter
Type of Stater

Direct On Line Starter
 Direct on line starter (DOL) mainly used
small capacity motors (below 5 HP)
doesn’t have very high starting current,
such motors can withstand the starting
currents.
 There is no need to reduce the voltage to
the motor at start and hence motor can
be connected directly to the supply lines.

Star Delta starter
 A star delta starter is the most
commonly used method for the
starting of a 3 phase induction motor.
 When motor reaches about 80% of
its full load speed, it will begin to run
in a delta connected stator winding.
 A star delta starter is a type of
reduced voltage starter

Auto Transformer Starter
 Three-phase auto transformer is connected
in series with the motor. This transformer
reduces the voltage applied to the motor
and hence the current.
 This starter consists of changeover switch
that switches the motor between reduced
voltage and full voltage conditions. When
this switch is in the start position, a reduced
voltage is applied to the motor.

Soft Stater
 In this method, semiconductor power
switches are employed for reducing the
starting current to the induction motor.
 It is another type of reduced voltage starter
and it connected in series with the line
voltage applied to the motor.
 This starter consists of back to back thyristors
or TRIACs in each phase of the stator winding

What is VFD
A variable frequency drive (VFD) is a type of motor controller
that drives an electric motor by varying the frequency and voltage of
its power supply.
The VFD also has the capacity to control ramp-up and ramp-down of
the motor during start or stop, respectively.
Other names:-
I). Adjustable speed drive
II). Adjustable frequency drive
III). AC drive (or) inverter.

Speed controlling methods:
Change supply voltage
Changing rotor resistance
Change frequency

Frequency Changing method
Formula for speed:-
NS = 120 X F/P
NS = Speed. ( motor RPM)
120 = Phase Angle. (Phase to phase angle)
F = Frequency. (No of cycle per second)
P = No of Poles.

No of poles (P) = 4
Frequency (F) = 50Hz
NS = 120 X 50/4 = 1500 RPM
No of poles (P) = 4
Frequency (F) = 40Hz
NS = 120 X 40/4 = 1200 RPM
Frequency controlling method
For examples:- NS = 120 X F/P

Block diagram of VFD system
Block diagram:-
DC BUS
CONTROLLER
INVERTER
(DC TO AC)
RECTIFIER
(AC TO DC)
MOTOR
3PHASE
POWER
SUPPLY
+
_
+
_

D1 D3 D5 T1 T3 T5
C1
D4 D6 D2 T4 T6 T2
Circuit diagram of VFD
Motor
R
Y
B
1 2 3 4 5 6
Rectifier DC bus Inverter controlled by PWM

Components are :- Area:-
Diodes
Capacitor
 MOSFET or IGBT
Pulse width Modulations
What are the major components used
RECTIFIER
(AC TO DC)
DC BUS
INVERTER
(DC TO AC)
CONTROLLER

D1 D3 D5 T1 T3 T5
C1
D4 D6 D2 T4 T6 T2
Motor
R
Y
B
RECTIFIER CIRCUITS

Rectifier:-
 A diode is defined as a two-terminal
semiconductor device.
Anode (+)
Cathode(-)
 That only conducts current in one direction.
(so long as it is operated within a specified
voltage level).

Rectifier:-
 A bridge rectifier makes use of four
diodes in a bridge arrangement to
achieve full-wave rectification.
 The Red colour indicates that those
diodes are in forward bias and the
black colour indicates that those
diodes are in reverse bias

Rectifier:-
 The arrows shows the direction of
current flow.
 At a particular time any of the two
diodes will be Forward Biased and
the other two will be Reverse Biased,

Rectifier:-
R
Y
B
1 2 3 4 5 6
Load
D1 D3 D5
D4 D6 D2
Diode = D1 to D6
Load = Dc motor

R
Y
B
1 2 3 4 5 6
Load
R
Y
B
Alternating current
1 2 3 4 5 6
Rectifier:-
Peak positive (supply) =
Peak negative (return) =
Rough Direct current
D1 D3 D5
D4 D6 D2

R
Y
B
1 2 3 4 5 6
Load
R
Y
B
1 2 3 4 5 6
Rectifier:-
Alternating current
Peak positive (supply) =
Peak negative (return) =
D1 D3 D5
D4 D6 D2

D1 D3 D5 T1 T3 T5
C1
D4 D6 D2 T6 T4 T2
Motor
R
Y
B
DC BUS CIRCUIT

DC bus:-
 DC bus is nothing but It capacitor
 Its function is to store the electrical energy and
give this energy again to the circuit when
necessary.
 In other words, it charges and discharges the
electric charge stored in it.
 It blocks the flow of DC and permits the flow of
AC.

DC bus:-
R
Y
B
1 2 3 4 5 6
R
Y
B
Alternating current
1 2 3 4 5 6
Load
Smooth Direct current
1 2 3 4 5 6
D1 D3 D5
C1
D4 D6 D2

R
Y
B
1 2 3 4 5 6
R
Y
B
Alternating current
1 2 3 4 5 6
Load
1 2 3 4 5 6
DC bus:-
D1 D3 D5
C1
D4 D6 D2

R
Y
B
1 2 3 4 5 6
R
Y
B
1 2 3 4 5 6
Load
1 2 3 4 5 6
DC bus:-
Alternating current
D1 D3 D5
C1
D4 D6 D2

R
Y
B
1 2 3 4 5 6
Load
R
Y
B
Alternating current Rough Direct current
1 2 3 4 5 6
1 2 3 4 5 6
DC bus:-
D1 D3 D5
C1
D4 D6 D2

D1 D3 D5 T1 T3 T5
C1
D4 D6 D2 T6 T4 T2
Motor
R
Y
B
INVERTER CIRCUIT

Inverter
 Inverter converted Direct current to
Alternating current.
 Mainly using the components are:
 IGBT -----using in high capacity
application.
(OR)
 MOSFET---- using in Low capacity
application.

Inverter
 The MOSFET (Metal Oxide
Semiconductor Field Effect Transistor)
transistor is a semiconductor device.
 which is widely used for switching
and amplifying electronic signals in
the electronic devices.
 The MOSFET is a three terminal
device such as source, gate, and
drain.

Inverter
.
 An insulated-gate bipolar transistor
(IGBT) is a three-terminal power
semiconductor device.
 It is primarily used as an electronic
switch which, as it was developed,
came to combine high efficiency and
fast switching.

Inverter
 It is a solid state device (with no
moving parts).
 An IGBT works by applying voltage to
a semiconductor component,
therefore changing its properties to
block or create an electrical path.
 Much like an Solid State Relay but
built for higher power applications.

Inverter
 PWM – Pulse width modulation Digital
control is used to create a square wave,
a signal switched between on and off.
 The duration off "on time" is called
the pulse width.
 Inverter signal controlled by Pulse
width modulation

Inverter
 Duty cycle is the percentage of
the ratio of pulse duration,
or pulse width (PW) to the total period
(T) of the waveform.

Inverter
Motor
+
0
-
+
0
-
+
0
-
1 2 3 4 5 6
Output wave form
R
Y
B
+
-
IGBT OR MOSET = T1 TO T6
T1 T3 T5
T4 T6 T2
+
0
-
Alternating current Waveform

Inverter
Motor
+
0
-
+
0
-
+
0
-
+
0
-
1 2 3 4 5 6
Output wave form
R
Y
B
+
-
T1 T3 T5
T4 T6 T2

How does its Working
T1 T3 T5
T4 T6 T2
Motor
R
Y
B
+
-
R
Y
B
R
Y
B
D1 D3 D5
C1
D4 D6 D2
AC INPUT CHANGE IN TO DC VARIABLE FREQUNCY AC OUTPUT

How does its Working
R
Y
B
R
Y
B
Motor
R
Y
B
+
-
D1 D3 D5
C1
D4 D6 D2
T1 T3 T5
T4 T6 T2
AC INPUT CHANGE IN TO DC VARIABLE FREQUNCY AC OUTPUT

VFD Basic wiring connection
T1 T2 T3
L1 L2 L3
3POLE MCB
3PHASE INDUCTION
MOTOR
3 PHASE LINE
COM|FOR|REV|LOW|MID|HIG|
+VDC|REF|COM

Wiring Diagram
SPL - LOW SPEED
SPM - MEDIUM SPEED
SPH – HIGH SPEED
RST - RESTART
REV – REVERSE DIRECTION
FOR – FORWARD DIRECTION
ACM – COMMON
AI – CURRENT INPUT
VI –VOLTAGE INPUT
FA,FB,FC – REALAY OUTPUT

Some of the VFD Application
Cooling Tower
 Compressor
Blower
Boiler
Lathe work shops
Modern lift system
Pumping system etc..,

Advantage and Disadvantage of VFD
Advantage:-
 Smooth starting.
 Smooth acceleration & deceleration time.
 Zero RPM Achive.
 Stopping methods.
 Power saving
Disadvantage:-
 Cost is higher
 Skilled person required to change the parameter

Troubleshoot in VFD
Loose connections are among the most
common causes of faulty operation
in VFD applications. Just eyeballing a
connection is sometimes enough to know it's
loose.
VFD overload condition.
VFD overheat.

What are the communication
1. Delta VFD (MODBUS RS-485COMMUNICATION).
2. SIEMENS VFD(PROFI BUS COMMUNICATION).
3. ABB VFD (MODBUS COMMUNICATION).
4. Schneider (MODBUS COMMUNICATION) .

Where is used VFD in our industry
1. scrubber Schneider VFD 22kw 11kw
2. Cooling 150TR ABB VFD 5Kw
3. Secondary pump Vogon VFD 11Kw
4. Dust collector ABB VFD 4kw

VFD SYSTEM- Variable Frequency Drive applications

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