The document discusses two types of inverters - current source inverters (CSI) and voltage source inverters (VSI). It describes the construction and working of CSI, which uses thyristors to control current, and VSI, which uses switches to control voltage. CSI is useful for applications like AC motor drives due to inherent short circuit protection and limited peak currents. VSI has smaller size but difficult short circuit protection. The document also covers applications of CSI for induction motor drives and VSI-based flexible AC transmission systems (FACTS) devices for improving power flow.

1. CURRENT SOURCE INVERTER(CSI)
&
VOLTAGE SOURCE INVERTER(VSI)
Presented by- Sadanand.C.Purohit
G.E.S.R.H.Sapat College of Engineering, Nasik
(University of Pune), Maharashtra, India

2. INDEX
 What is inverter.
 What is Current source inverter(CSI).
 Working of CSI.
 What is Voltage source inverter(VSI).
 Working of VSI.

3. INVERTER..
 We use converter as a generic term to refer
power conversion.
 Inverter refers to the converter when the
average flow is from DC to AC side.

4. CURRENT SOURCE INVERTER
 A current-source inverter (CSI) is one in
which the source current is predetermined
and the load impedance determines the
output voltage.
 The supply current cannot change quickly.
 The current is controlled by series dc supply
inductance.

5. CSI

6. CONSTRUCTION...
 The type of operation in this case is Auto-
Sequential Commutated Inverter (ASCI).
 In this circuit, six thyristors, six diodes, three
capacitors are needed here.

7. WORKING OF CSI.
 For 3 phase CSI

8. WORKING OF CSI
MODE 1

9. MODE 2

10. MODE 3

11. CSI....
Advantages
• Thyristor used for commutation are simpler
• The peak current flow through thyristor is limited
to safe value.
Disadvantages
• It needs a extra converter stage.
• At light load it has sluggish performance &
stability problem.
Application
• AC motor drives.

12. VOLTAGE SOURCE INVERTER.
 A voltage-source inverter (VSI) is one in
which the dc input voltage is essentially
constant
 Feedback diodes are necessary.
 Classification:- series, parallel, bridge
inverter

13. VSI
Advantages
• Output voltage waveform does not depend on
type of load.
• Size is small.
Disadvantages
• Protection against short circuit is difficult.
Application
• UPS
• AC drives

14. VOLTAGE SOURCE INVERETER
There are six combinations of conducting switches during an output
cycle:- (Sw5, Sw6, Sw1), (Sw6, Sw1, Sw2), (Sw1, Sw2, Sw3), (Sw2,
Sw3, Sw4), (Sw3, Sw4, Sw5), (Sw4, Sw5, Sw6).

15. Application of
Current Source Inverter

16. CSI FED INDUCTION MOTOR
 A three phase filter capacitor CS is required
for the commutation of switching devices
 CSI drives employ self commutating devices
such as gate turn-off thyristors (GTOs)
 Pulse width modulation (PWM) techniques
can be used to get improved output currents
and voltages

17. CSI FED INDUCTION MOTOR
 It is an attractive solution for high-power
applications due to its regenerative capability.
 A large dc link inductor connected at the
output of the phase controlled rectifier
 Suitable for fan and pump type of load
 smoother set of output voltage waveforms
suitable for driving ac motors

18. CHARACTERISTICS.
 Simple converter topology,
 Inherent four quadrant operation,
 Reliability,
 Motor friendly waveforms with
 Low dv/dt.

19. CONTINUED..
 The current-source inverter (CSI) topology
offers a number of advantages:
1) short-circuit protection,
2) low output voltage
3) instantaneous and continuous
regenerative capabilities.
Disadvantages;
 Poor and variable overall input power factor

20. Application of
Voltage Source Inverter

21. WHAT IS FACTS
 “Alternating current transmission systems
incorporating power electronics based and other
static controllers to enhance controllability and
Available Power Transfer Capacity”.
 The major problems faced by power industries
in establishing the match between supply and
demand are:
1) Transmission & Distribution; supply the electric
demand without exceeding the thermal limit.
2)In large PS, stability problems causing power
disruptions and blackouts leading to huge
losses.

22. VSI BASED FACTS
 FACTS controllers provide fast and reliable
control over the three main transmission
parameters, i.e., voltage magnitude, phase
angle and line impedance to facilitate optimal
power system performance.
 Static synchronous compensator, static
synchronous series compensator and unified
power flow controller are the voltage source
inverter based FACTS devices

23. VSI BASED FACTS
 It is composed of a VSC and its associated
shunt connected transformer with system
bus.
 The transformer is used as a link between
the VSI and the system bus

24. VSI BASED FACTS CONTROLLERS
 Includes dc-ac inverters to exchange shunt
or series reactive power with the
transmission system.
 To enhance the power flow over the
transmission line the parameters namely
voltage, impedance or angle must be
adjusted.

25. FACTS CONTROLLERS
 The shunt connected compensator
(STATCOM) is used to control the
transmission line voltage.
 The series connected compensator (SSSC)
controls the effective line impedance, XL
 The UPFC controls all variables (voltage,
impedance and angle) selectively or
concurrently.

26. CONTINUED..
 VSI based FACTS devices have several
advantages such as :
1)being small/compact
2)High response speed
3) No harmonic pollution.

27. THANK YOU