Function
of the
Inverter
The
function of the inverter is to convert fixed DC into variable voltage, variable
frequency alternating supply.
Explain the term : DC link
converter
DC link converter
It
is a combination of the AC to DC converter and DC to AC converter. The input
and output stage are AC whereas the intermediate stage is DC.
The
DC link converter consists of rectifier at the input stage and inverter at the
output stage. It is a two-stage static frequency converter in which the
alternating power at source frequency is rectified and filtered. The output of
the rectifier is fed to the input of the inverter which convert fixed DC into
variable voltage, variable frequency alternating supply.
What should be input of the
inverter?
It
may be DC source, battery, fuel cell, solar cell or rectifier.
Which semiconductor device
is used in the inverter circuit for the high-power output?
Silicon
controlled rectifier ( SCR )
Which semiconductor device
is used in the inverter circuit for the low power output?
Semiconductor Devices
Bi
– junction transistor ( BJT )
Gate
turn off thyristor ( GTO )
MOS
controlled thyristor ( MCT )
Metal
oxide field effect transistor ( MOSFET )
Which type of wave shape
the output voltage of the ideal inverter consists of?
Sinusoidal
On which factor the output
frequency of the inverter depends?
Switching
time of the semiconductor device
Describe the different
types of the inverter.
Types
of inverters
According
to output supply
Single
phase & Three phase
According
to input source
Voltage
source & Current source
According
to output waveform
Square
wave
Pulse
width modulation
Quasi
square wave
According
to commutating components connections
Series
& Parallel
Bridge
inverter : Half bridge and Full bridge
According
to method of commutation
Line
& Forced
What is meaning of the
forced commutated inverter and line commutated inverter?
Forced commutated inverter
The
inverter in which the SCR turns off by naturally zero is called as the
naturally commutated inverter.
Line
commutated inverter
The
inverter in which the SCR turns off by forced commutation is called as the
forced commutation inverter.
How many switching
semiconductor devices are used in the single-phase half bridge inverter?
Two
Explain the term : Cross
conduction or shoot – through – fault
Cross
conduction ( shoot
– through – fault
)
The
single-phase half bridge inverter in which incoming and outgoing semiconductor
switches conduct simultaneously for a short time is called as cross conduction or
shoot – through – fault.
Describe the effect of
shoot – through – fault effect.
Effect
of shoot
– through – fault
The
DC input supply is short circuited and both switching semiconductors are
damaged.
How the cross conduction of
the semi – conductor device is avoided?
Cross
conduction
The
cross conduction of the semi – conductor device is avoided by dead band or
delay is introduced between the trailing edge of the base drive of the outgoing
semi – conductor device and leading edge of the base drive of the incoming semi
– conductor device. The dead band should
be longer time than that of the turn off time of the switching semiconductor
devices.
How many switching semi –
conductor devices conduct during dead band in the single-phase half bridge
inverter?
Not
a single semi – conductor
How many switching
semiconductor devices are used in the single-phase full bridge inverter?
Four
1What is
meaning of the voltage source inverter and current source inverter?
Voltage
source inverter
It
is inverter in which the output voltage remains constant for a given type of
load. The large capacitor is connected at the input side of the inverter.
Current
source inverter
It
is inverter in which the input current remains constant for a given type of
load. The large inductor is connected in series with the supply source at the
input side.
Describe the different
method of voltage control of the single-phase inverter.
Method of voltage control
External control
AC
output voltage
DC
input voltage
Internal
control
Series
parallel control
Pulse
width modulation (PWM) control
1.
Single PWM
2.
Multiple PWM
3.
Sinusoidal PWM
What is meaning of the
pulse width modulation technique?
Pulse
width modulation
It is technique in which the on and off time of the switching semiconductor is varied.
Describe the advantages and
disadvantages of the PWM techniques.
Advantages
The
output voltage can be control without any external components. Lower order
harmonics are eliminated therefore the filter requirement is minimized whereas
the higher order harmonics are easily filtered.
Disadvantages
The inverter grade SCRs requires which have low turn on and turn off time.
No comments:
Post a Comment