KUPPAM ENGINEERING COLLEGE DEPARTMENT OFELECTRICAL & ELECTRONICS ENGINEERING

PRESENTED BY:S.FIRDOSE BEGUM 11F41A0239B.V.PAVAN KUMAR :11F41A0204R.BHABITHA :11F41A0236P.JAYALAKSHMI :11F41A0233

UNDER THE GUIDANCE OF Mr P.KIRAN KUMAR M.Tech Assistant professor

HIGH STEP-UP CONVERTER WITH THREE- WINDING COUPLED INDUCTOR

INTRODUCTION

To increase conversion efficiency many technologies have been investigated such as

a) ZERO VOLTAGE SWITCHING(ZVS),b) ZERO CURRENT SWITCHING(ZCS), c) COUPLED INDUCTOR,d) ACTIVE CLAMP,e) SWITCHED CAPACITOR,f) VOLTAGE LIFT TECHNIQUES which suffers from high current and

conduction losses.

CONTINUATION OF INTRODUCTIONRecently coupled inductor technique with performance of

i. Leakage energy recycle,ii. Adjustable voltage gain,iii.High efficiency continuous conduction mode,iv. Low voltage stress is developed.

It Avoids high peak current ripple, large input current ripple It employs a switched capacitor to supply an extra step up performance and voltage doubler circuit to lift the output voltage by increasing the turns ratio of coupled inductor.

FEATURES OF COUPLED INDUCTOR TECHNOLOGY

Coupled inductor technology as performance of1. Leakage energy recycle,2. Adjustable voltage gain.

Many high step-up converters with the characteristics of a)High voltage gain,b)High efficiency,c) Low voltage stress.

Three-winding coupled inductor have also been proposed, which possess more flexible adjustment of

i. voltage conversion ratio,ii. Voltage stress.

It helps to operate in continuous conduction mode because the discontinuous conduction mode operation results in large input current ripple and high peak current, which makes burst of components

CONVENTIONAL METHOD

A conventional current-fed half-bridge converter has the input-current doubler function Since the input current divides into two inductor currents, reducing the primary current of the transformer, the related conduction loss is reduced.It has several problems such as

a.Voltage spikes of switches resulting from the leakage inductance of the transformer,

b.High-voltage stress of the rectifying diodes,c. Low power conversion efficiency.

PROPOSED METHOD The proposed system consists of

a) Input-current doubler, b) Output-voltage doubler, and c) Active-clamp circuit.

The input-current doubler and the outputvoltage doubler provide a higher voltage conversion ratio without using a high turns ratio in the transformer and increase the overall efficiency. A series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the rectifying diodes. The proposed dc–dc converter has low conduction loss in the primary side, since the input-current doubler divides the input current into two inductor currents, reducing the primary current of the transformer, and the primary switches with the active-clamp circuit have low ON-resistance by reducing voltage stress.

DESIGN CONSIDERATIONS

The required step-up conversion ratio is up to 6.7. Therefore, in order to make the duty cycle lower than 0.5 to decrease the conduction losses, the key design step is to determine the turns ratio of the coupled inductor.

Thus, the turns ratio of the coupled inductor is set as 1:1:1.5. The magnetizing inductor can be designed based on the current ripple

percentage of magnetizing inductor under full-load operation, and the related equations are given as

ILm ={(1 + n3)/( 1 − Dmax)} Io,max Lm = (Vin,min × Dmax) /(f × 2ΔiLm) The capacitors can be designed based on the voltage ripple

percentage of capacitor under full-load operation, and the related equations are given as

C1 = C3 = (Io,max × Dmax) /(f × ΔvC) Cb = C2 = (Io,max)/(f × ΔvC)

BLOCK DIAGRAM

TRANSFORMER 15V AC RECTIFIER

FLY BACK DC TO DC BOOST CONVERTER

RECHARGABLE BATTERY 12V 7.5AH

PWM DRIVER

3 WINDING COUPLED INDUCTOR

AURDINO CONTROLLER

MOSFET SWITCH IRF

230V AC

CURRENT T/F COIL

FEEDBACK

LCD DISPLAY

COMPONENTSLCD DisplayTransformer 15-0-15, 1AThree winding coupled inductor—1:1:1.5Capacitors—220UFDiodes—3A,free wheeling diodesCrystal oscillator7805 RegulatorHeat sinkRectifierRessssschargable battery---12V,7.5AHArduino controllerBoost circuitMPPT(maximum power point tracker )board

PWM driver IC DSPAC 30F2010 Current tranformer coil --3A Board protection relay—12V Load protection relay—12V MOSFET P55NF60

DESCRIPTION

1. Power supply is given.2. Rectifier converts 15V AC to 15V DC3. Boost circuit boosts voltage up to 30V

DC4. MPPT board by using PWM converts 30V

DC to 300V AC by using switching frequency of31khz

5. Three winding coupled inductor reduces ripples and gives pure sinusoidal 230V AC output

6. Board protection relay protects internal circuitry

7. Load protection relay protects external circuitry

FEED BACK PATHS

ARDUINO controlles the circuitry and obtains feedbackTotal feedback is obtained from three devices

a) ARDUINO b) THREE WINDING COUPLED INDUCTORc) PWM DRIVER

Error signal is displayed in LCD display device

ADVANTAGES Through adjusting the turns ratio of coupled inductor, the proposed converter achieves high step-up gain that renewable energy systems require;Leakage energy is recycled to the output terminal, which improves the efficiency and alleviates large voltage spikes across the main switch;Due to the passive lossless clamped performance, the voltage stress across main switch is substantially lower than the output voltage;Low cost and high efficiency are achieved by adopting low-voltage-rated power switch with low RDS-ON;By using three-winding coupled inductor, the proposed converter possesses more flexible adjustment of voltage conversion ratio and voltage stress on each diode

DISADVANTAGES AND THEIR ANALYSISAll the leakage inductors of coupled inductor are neglected and all of components are ideal without any parasitic components as energy recycling process occurs. The voltages are considered to be constant due to infinitely large capacitances.Some conduction losses are caused by resistances of semiconductor components and coupled inductor ,which is calculated by small ripple approximation.Large input current ripple and peak current is avoided as all currents passing through components were approximated by dc components. Thus, magnetizing current and capacitor voltages are assumed to be constant.

ANALYSIS:(A)STEP UP GAIN:

During the turn-on period of switch S, the following equations can be written as:

VC3 = VN 3 = n3 · Vin .............................(1) VCb = Vin + VN 2 = (n2 + 1) · Vin...........(2)

During the turn-off period of switch S, the following equations can be expressed as:

VC2 = n3 [VC1 − (2 + n2 ). Vin ]...................... (3) VC1 ={[D/(1 − D)]+2+n2 }.Vin ………….... (4)

Thus, the output voltage VO can be expressed as VO = VC1 + VC2 + VC3 …………………… . (5)

By substituting (1), (3), and (4) into (5), the voltage gain of the proposed converter is given by

MCCM = Vo/Vin= n2 +(2 − D + n3/1 − D)

B)VOLTAGE STRESS

The voltage stress on the main switch is given as :MS = VS1/Vout = 1/(2 − D + (1 − D) n2 + n3.)........(7)

When the switching S is turned OFF, the diodes D1 and D3 are reverse biased.

Therefore, the voltage stresses of D1 and D3 are as follows: MD1 = VD1/Vout =(1 + n2)/( 2 − D + (1 − D) n2 + n3).......(8) MD4 = VD3/Vout = n3/(2 − D + (1 − D) n2 + n3)..............(9)

When the switch S is in turn-on period and the diodes D2 and D3 are reverse biased.

Therefore, the voltage stresses of D2 and D3 are as follows: MD2 = VD2/Vout=1/(2 − D + (1 − D) n2 + n3.............(10) MD3 = VD4/Vout= n3/(2 − D + (1 − D) n2 + n3..........(11)

Equations (7)–(11) can be illustrated to determine the maximum voltage stress on each power drives.

(C) CONDUCTION LOSSES:

Some conduction losses are caused by resistances of semiconductor components and coupled inductor ,which is calculated by small ripple approximation.Voltage conversion ratio with conduction losses is given as:

V0/Vin=[n2 + (2−D+n3/1−D)− K]/[1 +( α /RL (1−D)2) + (rL 3/ RL D(1−D)) +( β/RL (1−D) )+ (γ/RLD) …………………..(12)

where K = (VD 1 +VD 2 +VD 3 +VD 4)/Vin α = (1+n2 )D · rL1 + (1 + n3 )D · rDS β = (1+2n2 + n3 ) rL1 + rL3 + rD2 + rD3+(2+n2 + 2n3 ) rDS γ = rL2 + rD1 + rD4 + (1 + n2 + n3 ) rDS

Efficiency is expressed as follows: η ={Vin − n2 + (2−D+n3/1−D). (VD1 + VD2 + VD3 + VD4) /{Vin +(

α/(RL (1−D)2)) + (rL3/(RL D(1−D) ))+ (β/(RL (1−D)) + γ/RL D}………………………………………………...(13

APPLICATIONS

Laptop,computers, Battery chargers, Cell phones, Small power tools, Lamps, Low power kitchen appliances,  Fluorescent lamps, Small motors, Power televisions and other consumer

components

CONCLUSION

By using technologies of three winding coupled inductor, switched capacitor, and voltage doubler circuit, the high step-up conversion can be efficiently obtained. The leakage energy is recycled and large voltage spike is alleviated; thus, the voltage stress is limited and the efficiency is improved.The low-voltage-rated switch with low RDS-ON can

selected for the reduction of conduction losses