电力电子中的逆变电源英文资料

2021年1月25日发(作者：落伍的英文怎么写)
Inverter

1

Introduction
An inverter is an electrical device that converts direct current (DC) to alternating current
(AC);
the
converted
AC
can
be
at
any
required
voltage
and
frequency
with
the
use
of
appropriate transformers, switching, and control -state inverters have no moving
parts and are used in
a wide range of applications, from
small
switching power supplies in
computers, to large electric utility high-voltage direct current applications that transport bulk
power.
Inverters
are
commonly
used
to
supply
AC
power
from
DC
sources
such
as
solar
panels or batteries.
There
are
two
main
types
of
inverter.
The
output
of
a
modified
sine
wave
inverter
is
similar
to
a
square
wave
output
except
that
the output
goes
to
zero
volts
for
a
time
before
switching
positive
or
negative.
It
is
simple
and
low
cost
and
is
compatible
with
most
electronic
devices,
except
for
sensitive
or
specialized
equipment,
for
example
certain
laser
printers.
A
pure
sine
wave
inverter
produces
a
nearly
perfect
sine
wave
output
(<3%
total
harmonic
distortion)
that
is
essentially
the
same
as
utility-supplied
grid
power.
Thus
it
is
compatible with all AC electronic devices. This is the type used in grid- tie inverters. Its design
is more complex, and costs 5 or 10 times more per unit power

The electrical inverter is a
high-power
electronic
oscillator.
It
is
so
named
because
early
mechanical
AC
to
DC
converters were made to work in reverse, and thus were
inverter performs the opposite function of a rectifier.
2

Applications
2.1

DC power source utilization
An inverter converts the DC electricity from sources such as
batteries, solar panels, or
fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can
operate AC equipment designed for mains operation, or rectified to produce DC at any desired
voltageGrid
tie
inverters
can
feed
energy
back
into
the
distribution
network
because
they
produce
alternating
current
with
the
same
wave
shape
and
frequency
as
supplied
by
the
distribution
system.
They
can
also
switch
off
automatically
in
the
event
of
a
-inverters
convert
direct
current
from
individual
solar
panels
into
alternating
current for the electric grid. They are grid tie designs by default.

2.2

Uninterruptible power supplies
An
uninterruptible
power
supply
(UPS)
uses
batteries
and
an
inverter
to
supply
AC
power when main power is not available. When main power is restored, a
rectifier supplies
DC power to recharge the batteries.
2.3

Induction heating
Inverters
convert
low
frequency
main
AC
power
to
a
higher
frequency
for
use
in
induction heating. To do this, AC power is first rectified to provide DC power. The inverter
then changes the DC power to high frequency AC power.

2.4

HVDC power transmission
With HVDC power transmission, AC power is rectified and high voltage DC power is
transmitted to another location. At the receiving location, an inverter in a static inverter plant
converts the power back to AC.
2.5

Variable- frequency drives
A variable-frequency drive controls the operating speed of an AC motor by controlling
the
frequency
and
voltage
of
the
power
supplied
to
the
motor.
An
inverter
provides
the
controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC
power
for
the
inverter
can
be
provided
from
main
AC
power.
Since
an
inverter
is
the
key
component, variable-frequency drives are sometimes called inverter drives or just inverters.
2.6

Electric vehicle drives
Adjustable
speed
motor
control
inverters
are
currently
used
to
power
the
traction
motors
in
some
electric
and
diesel-electric
rail
vehicles
as
well
as
some
battery
electric
vehicles
and
hybrid
electric
highway vehicles such as the Toyota Prius and Fisker Karma. Various improvements in inverter technology
are being developed specifically for electric vehicle applications.
[2]
In vehicles with regenerative braking,

the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries.
2.7

The general case
A transformer allows AC power to be converted to any desired voltage, but at the same
frequency. Inverters, plus rectifiers for DC, can be designed to convert from any voltage, AC
or DC, to any other voltage, also AC or DC, at any desired frequency. The output power can
never
exceed
the
input
power,
but
efficiencies
can
be
high,
with
a
small
proportion
of
the
power dissipated as waste heat.

3

Circuit description


3.1

Basic designs


In one simple inverter circuit, DC power is connected to a transformer through the centre
tap of the primary winding. A switch is rapidly switched back and forth to allow current to
flow
back
to
the
DC
source
following
two
alternate
paths
through
one
end
of
the
primary
winding and then the other. The alternation of the direction of current in the primary winding
of the transformer produces alternating current (AC) in the secondary circuit.

The electromechanical version of the switching device includes two stationary contacts and a
spring
supported
moving
contact.
The
spring
holds
the
movable
contact
against
one
of
the
stationary contacts and an electromagnet pulls the movable contact to the opposite stationary
contact. The current in the electromagnet is interrupted by the action of the switch so that the
switch
continually
switches
rapidly
back
and
forth.
This
type
of
electromechanical
inverter
switch,
called
a
vibrator
or
buzzer,
was
once
used
in
vacuum
tube
automobile
radios.
A
similar mechanism has been used in door bells, buzzers and tattoo guns.
As they became available with adequate power ratings, transistors and various other types of
semiconductor switches have been incorporated into inverter circuit designs

1
3.2

Output waveforms
The
switch
in
the
simple
inverter
described
above,
when
not
coupled
to
an
output
transformer,
produces
a
square
voltage
waveform
due
to
its
simple
off
and
on
nature
as
opposed to the sinusoidal waveform that is the usual waveform of an AC power supply. Using
Fourier analysis, periodic waveforms are represented as the sum of an infinite series of sine
waves.
The
sine
wave
that
has
the
same
frequency
as
the
original
waveform
is
called
the
fundamental
component.
The
other
sine
waves,
called
harmonics
,
that
are
included
in
the
series have frequencies that are integral multiples of the fundamental frequency.
The quality of output waveform that is needed from an inverter depends on the characteristics
of the connected load. Some loads need a nearly perfect sine wave voltage supply in order to
work properly. Other loads may work quite well with a square wave voltage.

3.3

Three phase inverters
Three-phase
inverters
are
used
for
variable-frequency
drive
applications
and
for
high
power
applications such as HVDC power transmission. A basic three-phase inverter consists of three single-phase
inverter switches each connected to one of the three load terminals. For the most basic control scheme, the
operation of the three switches is coordinated so that one switch operates at each 60 degree point of the
fundamental output waveform. This creates a line-to-line output waveform that has six steps. The six-step
waveform has a zero- voltage step between the positive and negative sections of the square-wave such that
the
harmonics
that
are
multiples
of
three
are
eliminated
as
described
above.
When
carrier- based
PWM
techniques
are
applied
to
six-step
waveforms,
the
basic
overall
shape,
or
envelope
,
of
the
waveform
is
retained so that the 3rd harmonic and its multiples are cancelled

4

History
4.1

Early inverters
From the late nineteenth century through the middle of the twentieth century, DC-to-AC
power
conversion
was
accomplished
using
rotary
converters
or
motor-generator
sets
(M-G
sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as
switches in inverter circuits. The most widely used type of tube was the thyratron.
The
origins
of
electromechanical
inverters
explain
the
source
of
the
term
inverter
.
Early
AC-to-DC
converters
used
an
induction
or
synchronous
AC
motor
direct-connected
to
a
generator (dynamo) so that the generator's commutator reversed its connections at exactly the
right moments to produce DC. A later development is the synchronous converter, in which the
motor and generator windings are combined into one armature, with slip rings at one end and
a commutator at the other and only one field frame. The result with either is AC-in, DC-out.
With an M-G set, the DC can be considered to be separately generated from the AC; with a
synchronous converter, in a certain sense it can be considered to be
AC




2
4.2

Controlled rectifier inverters
Since early transistors were not available with sufficient voltage and current ratings for
most inverter applications, it was the 1957 introduction of the thyristor or silicon-controlled
rectifier (SCR) that initiated the transition to solid state inverter circuits.
The
commutation
requirements of SCRs are a key consideration in SCR circuit designs. SCRs
do not turn off or
commutate
automatically when the gate control signal is shut off. They only
turn off when the forward current is reduced to below the minimum holding current, which
varies with each kind of SCR, through some external process. For SCRs connected to an AC
power
source,
commutation
occurs
naturally
every
time
the
polarity
of
the
source
voltage
reverses.
SCRs
connected
to
a
DC
power
source
usually
require
a
means
of
forced
commutation
that
forces
the
current
to
zero
when
commutation
is
required.
The
least
complicated SCR circuits employ natural commutation rather than forced commutation. With
the
addition
of
forced
commutation
circuits,
SCRs
have
been
used
in
the
types
of
inverter
In
applications
where
inverters
transfer
power
from
a
DC
power
circuits
described
above.
source
to
an
AC
power
source,
it
is
possible
to
use
AC-to-DC
controlled
rectifier
circuits
operating in the inversion mode. In the inversion mode, a controlled rectifier circuit operates
as
a
line
commutated
inverter.
This
type
of
operation
can
be
used
in
HVDC
power
transmission systems and in regenerative braking operation of motor control systems.
Another
type
of
SCR
inverter
circuit
is
the
current
source
input
(CSI)
inverter.
A
CSI
inverter is the dual of a six-step voltage source inverter. With a current source inverter, the DC
power
supply
is
configured
as
a
current
source
rather
than
a
voltage
source.
The
inverter
SCRs are switched in a six-step sequence to direct the current to a three-phase AC load as a
stepped current waveform. CSI inverter commutation methods include load commutation and
parallel
capacitor
commutation.
With
both
methods,
the
input
current
regulation
assists
the
commutation. With load commutation, the load is a synchronous motor operated at a leading
power
factor.
As
they
have
become
available
in
higher
voltage
and
current
ratings,
semiconductors
such
as
transistors
or
IGBTs
that
can
be
turned
off
by
means
of
control
signals have become the preferred switching components for use in inverter circuits.

4.3

Rectifier and inverter pulse numbers
Rectifier circuits are often classified by the number of current pulses that flow to the DC
side
of
the
rectifier
per
cycle
of
AC
input
voltage.
A
single-phase
half-wave
rectifier
is
a
one- pulse circuit and a single-phase full-wave rectifier is a two-pulse circuit. A three-phase
half-wave rectifier is a three-pulse circuit and a three-phase full-wave rectifier is a six- pulse
circuit
。
With three-phase rectifiers, two or more rectifiers are sometimes connected in series
or parallel to obtain higher voltage or current ratings. The rectifier inputs are supplied from
special
transformers
that
provide
phase
shifted
outputs.
This
has
the
effect
of
phase
multiplication.
Six
phases
are
obtained
from
two
transformers,
twelve
phases
from
three
transformers
and
so
on.
The
associated
rectifier
circuits
are
12-pulse
rectifiers,
18-pulse
rectifiers and so on. When controlled rectifier circuits are operated in the inversion mode, they
would be classified by pulse number also. Rectifier circuits that have a higher pulse number
have reduced harmonic content in the AC input current and reduced ripple in the DC output

3