iNTRODUCTION TO INVERTERS _ UPS

							  ECE , ME– I SEM

INTRODUCTION TO
 INVERTERS & UPS
     INTRODUCTION TO INVERTERS
   It’s an electrical device that converts DC to AC.
   It’s essentially the opposite of a rectifier.
   Static inverters have no moving parts and are
    used in wide range of applications from small
    switching power supplies in computers to large
    electrical utility high- voltage DC applications.
   Commonly used to supply AC power from DC
    sources such as solar panels or batteries.
   High-power electrical oscillator.
   It is so named because early mechanical AC to
    DC converters were made to work in reverse, and
    thus were “inverted” to convert DC to AC.
   INTRODUCTION TO INVERTERS
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BASIC DESIGN=>
 In one simple inverter circuit, DC power is
  connected to a transformer through a 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.
    INTRODUCTION TO INVERTERS
             CONTD…
The following diagram represents simple inverter circuit shown with
  an electromechanical switch and automatic equivalent auto-
  switching device implemented with two transistors and split
  winding auto-transformer in place of the mechanical switch.
     INTRODUCTION TO INVERTERS
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   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.
   INTRODUCTION TO INVERTERS
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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 as shown
  in the figure.
   INTRODUCTION TO INVERTERS
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Applications=>
 DC power source utilization such as Grid tie
  inverters and micro inverters.
 UPS

 Induction Heating

 HVDC power transmission

 Variable Frequency Drives

 Electric Vehicle drives

 Air Conditioning
          INTRODUCTION TO UPS
   It is an electrical apparatus that provides
    emergency power to a load when the input power
    source, typically the utility mains, fails.
   The figure show
    the front and rear
    view of a small
    free-standing
    UPS.
           INTRODUCTION TO UPS
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   The UPS or Uninterruptible Power supply is
    also known as Uninterruptible power source
    or Battery/flywheel backup.
   A UPS differs from an auxiliary or emergency
    power system or standby generator in that it will
    provide instantaneous or near-instantaneous
    protection from input power interruptions by
    means of one or more attached batteries and
    associated electronic circuitry for low power
    users, and or by means of diesel generators and
    flywheels for high power users.
           INTRODUCTION TO UPS
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    The on-battery runtime of most uninterruptible
    power sources is relatively short—5–15 minutes
    being typical for smaller units—but sufficient to
    allow time to bring an auxiliary power source on
    line, or to properly shut down the protected
    equipment.
   Typically used to protect computers, data centers,
    telecommunication equipment or other electrical
    equipment.
   They can correct many power related problems
    such as power failure, surge, sag, spikes, noise,
    frequency instability and harmonic distortion.
           INTRODUCTION TO UPS
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    The general categories of UPS are:
1.    On- Line
2.    Line interactive
3.    Standby
     The applications of UPS are:
1.    N+1
2.    Multiple redundancy
3.    Outdoor use
4.    Internal Systems