Transcript الاسبوع واحد وعشرون

‫االسبوع الحادي والعشرون‬
‫تطبيقات المبدالت‬
‫‪Inverter Application‬‬
Study the following :
 Inverter application.
 Emergency power supply
 Single phase motor speed control
Enumerate the inverter
application.
How we can gat on constant
speed D.C motor by using
inverter .
Q1
Potential
If
Comparator
Amp.
Trigger
cct.
Feed back loop
M
T
G
Inverter Application :
• The converter change a D.C to A.C is called an
inverter. Earlier inverters were built with SCRs. Since
the circuit required to turn the SCR off tends to be
complex, other power semiconductor devices such
as bipolar junction transistors , power MOSFETs,
insulated gate bipolar transistor(IGBT)and MOS-controlled
thyristors (MCTs)are used nowadays. Currently only
the inverters with a high power rating . Such as 500kw
or higher .adding to that we can used it in the following :
• Good inverter :
Here, some of requirements of a good inverter are enumerated .
1. Its output voltage waveform should be sinusoidal .
2. Its gain (ac output voltage /dc input voltage ) should be high .
3. Its output voltage and frequency should be controllable in the desired
usage . For example , inverter must be capable of keeping V/f constant
for some application .
4. The power required by its controlling circuit should be minimum.
5. The semiconductor devices used in the inverter should have minimum
switching and conduction losses.
6. Its overall cost must be minimum without sacrificing its reliability .
7. Its working life must be long .
8. It should produce minimum electromagnetic interference (EMI).
9. The size of the filters required should be small.
Many of the points listed above, apply equally well to other type of powerelectronics converters
1-Uninterruptible power supplies
Main
feeder
converter
invertor
~
~
Battery
Switch
ON
or
OFF
Loads
• Static UPS system are two types :
1. short-break UPS .
Normally “ON”
Static transfer
switch
Power flow
Main
ac
supply
Rectifier
ac-dc
Inverter
dc-ac
Critical
load
Filter
Normally “OFF”
Normally off
Batteries
Fig ( 2 )
2-No-break UPS
Normally “OFF”
Static transfer
switch
Power flow
Main
ac
supply
Rectifier
ac-dc
Inverter
dc-ac
Critical
load
Filter
Normally “ON”
Normally on
Batteries
Fig (3 )
3-rotating – type UPS system based on dc motor /alternator set .
UPS to critical
loads
3-phase
supply
mains
~
DC
M
−
Alternator
Flywheel
Rectifier
Battery
Bank
Fig 4: rotating – type UPS system based on dc motor /alternator set .
Diesel
engine
2- Electrical Drive
Variable speed motor drives
* DC drives
▹ Power supply for DC motor
▹Usually controlled rectifier to convert constant AC to
variable DC
*AC drives
▹Power supply for AC motor
▹Mostly for induction motors, but can be used with
synchronous motors
▹Fixed AC →DC (fixed or variable) →Variable
frequency and voltage AC
• Speed control on D.C motor .
If
Ia
V
M
Potential
If
Comparator
Amp.
Trigger
cct.
Feed back loop
M
T
G
Variable Speed AC Drive
VVVF control of induction motor
600V DC Link
415V
3- phase
rectifier
3-phase
rectifier
3-phase
rectifier
AC
motor
Three-phase inverter for speed control
(by using PWM METHODS)
Three phase inverter
Waveforms of voltages
Key answer
:
Main
feeder
converter
invertor
~
~
Battery
Switch
ON
or
OFF
Loads