Current Source Inverter(CSI) Ckt diagram and waveforms

1. Seminar on
Current Source Inverter
Presented to: Presented by:
Shimi S.L Prashant Kumar
Asst. Professor Roll: 142517
NITTTR; Chandigarh I&C(Regular)

2. CONTENTS
 Introduction
 Single phase CSI with Ideal Switches
 Advantages & Disadvantages of CSI
 Single phase Capacitor Commutated CSI
 Single phase Auto Sequential Commutated
Inverter(ASCI)

3. Introduction
Use of CSI:-
• Speed Control of ac motor
• Induction Heating
• Lagging Var Compensation
• Synchronous motor starting
VSI:-
V
I as Load
CSI:-
I
V as Load
e.g In IM; Tload ; Tdeveloped; Speed
No Acceln/No Deacceln
Thyristor is used as self-commutated switching device.
Transistor is used as self-commutated switching device.

4. Single phase CSI with Ideal
Switches
For C load

5. From Waveform;
To=2Tin
i.e fin=2fo
 In CSI;
For Voltage Reversal , Diode is not required.
 In VSI;
For Current Reversal, Antiparallel Diode required.

6. Advantages of CSI
 Feedback diode are not required in CSI.
 Commutation is Simple.
 Inherently, there is Short Circuit protection for supply when
incoming thyristor are switched on before the outgoing
thyristor become off.
 For C load i.e PF leading load, Load commutation (Natural
Commutation) takes place.
Though for lagging PF load, Forced Commutation Needed.
(1-phase capacitor Commutated CSI with R Load)

7. DisAdvantages of CSI
 The load applies high reverse voltage across the device
during commutation process, therefore the devices having low
reverse voltage blocking capacity such as GTO, IGBT &
other transistor are generally not preferred.
Here we prefer SCR because it has high reverse voltage
blocking capacity.
 When commutating capacitor is directly connected across the
load then it will be continuously discharging through the load
even at steady state condition.
To avoid this property, we must connect blocking diode
between commutating capacitor.
(Single phase Auto Sequential Commutated
Inverter(ASCI))

8. Single phase Capacitor Commutated
CSI

10. Design Consideration

11. Single phase Auto Sequential
Commutated Inverter