current source inverter

Seminar onCurrent Source Inverter

Presented to: Presented by:Shimi S.L Prashant KumarAsst. Professor Roll: 142517NITTTR; Chandigarh I&C(Regular)

CONTENTS

Introduction

Single phase CSI with Ideal Switches

Advantages & Disadvantages of CSI

Single phase Capacitor Commutated CSI

Single phase Auto Sequential Commutated Inverter(ASCI)

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 Loade.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.

Single phase CSI with Ideal Switches

For C load

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.

Advantages of CSI

Feedback diode are not required in CSI.

Commutation is Simple.

Inherently, there is Short Circuit protection for supply whenincoming thyristor are switched on before the outgoingthyristor become off.

For C load i.e PF leading load, Load commutation (NaturalCommutation) takes place.

Though for lagging PF load, Forced Commutation Needed.

(1-phase capacitor Commutated CSI with R Load)

DisAdvantages of CSI

The load applies high reverse voltage across the deviceduring commutation process, therefore the devices having lowreverse voltage blocking capacity such as GTO, IGBT &other transistor are generally not preferred.

Here we prefer SCR because it has high reverse voltageblocking capacity.

When commutating capacitor is directly connected across theload then it will be continuously discharging through the loadeven at steady state condition.

To avoid this property, we must connect blocking diodebetween commutating capacitor.

(Single phase Auto Sequential CommutatedInverter(ASCI))

Single phase Capacitor Commutated CSI

Design Consideration

Single phase Auto Sequential Commutated Inverter