Solar Panel for House Hold application with Input Voltage Feed Forward for the Two Switch Buck Boost DC DC Converter

Solar Panel for House Hold application with Input Voltage Feed Forward for the Two Switch Buck Boost DC DC Converter

Nivya Varghese M Tech Scholar

Department of Electrical Engineering Federal Institute of Science and Technology, Kerala

Rakhee R Assistant Professor

Department of Electrical Engineering Federal Institute of Science and Technology, Kerala

Abstract- Now days we are facing voltage crisis, shortage of generated power make as to this to think about an alternate source such as solar panel. This paper focus on solar panel for house hold application with input voltage feed forward for the two switch buck boost (TSBB) dc dc converter. It consist of a solar panel , input voltage feed forward(IVFF) for the two switch buck boost dc dc converter, inverter, load, we know panel voltage may vary according to time but even if solar power changes output will remain constant based on reference value. for wide input voltage applications two- switch buck-boost (TSBB) converter is suitable. By two mode control scheme we can easy buck or boost the input voltage. TSBB converter is said to be two-mode control scheme when it is operated in buck mode at high input voltage and boost mode at low input voltage in order to achieve high efficiency over the entire input voltage range. The influence of the input voltage disturbance on the output voltage is reduced by this method that is whatever the input voltage output will be constant based on reference voltage.

Index terms- Two switch buck boost converter, small signal model, input voltage feed forward, two mode controls.

1. INTRODUCTION

   Now a days it is an effective way to use solar panel in house hold basis, a lot of energy can conserve by this way. In this paper we are using solar panel along with TSBB converter for buck operation and boost operation. If available solar power is low we boost the voltage up to the reference voltage, here we kept dc output as constant based on reference and we provide an inverter for ac output. Simplified cascade connection of buck and boost converters are shown in fig 1

   Various control methods for this converter is achieve by two active switches in the TSBB converter. TSBB converter behaves the same as the single switch buck-boost

   the output voltage, the TSBB converter is equivalent to a boost converter.

   Fig 1 Two switch buck boost converter

   This type of control method is called two mode control scheme. Two modulation signals with one carrier or one modulation signal with two carriers was proposed in order to achieve automatic switching between buck and boost modes.

   Only one voltage regulator is used for both buck and boost modes. Several methods are there to implement IVFF.

   1. finding value of duty ratio, duty ratio is inversely proportional to the input voltage.2) changing amplitude of carrier signal or change value of modulation signal. Both this are inversely proportional to input voltage.

2. TWO-MODE CONTROL SCHEME WITH AUTOMATIC

   MODE-SWITCHING ABILITY

   In continuous current mode (CCM) the voltage conversion of the TSBB converter is

   converter, If Q1 and Q2 are switched ON and OFF simultaneously, this method is known as one mode control scheme. Other controlling methods are possible for Q1 and

   0

   = 1

   1 2

   Q2 . Operation is said to be buck mode, when Q1 is controlled to regulate the output voltage and Q2 is always kept OFF, when the input voltage is higher than the output voltage TSBB converter is equivalent to a buck converter. On the other hand operation is said to be boost mode when Q2 is controlled to regulate the output voltage, Q1 is always kept ON, and when the input voltage is lower than

   Duty cycles of switches Q1 and Q2 are d1 and d2, d1 and d2 are controlled independently in two mode control scheme.

   According to fig 2, TSBB converter operates in buck mode, When the input voltage is higher than the output Voltage, Q2 is always OFF where d2 = 0 and d1 is controlled to regulate the output voltage. TSBB converter

   operates in boost mode, when the input voltage is lower than the output voltage Q1 is always ON, where d1 = 1 and d2 is controlled to regulate the output voltage. As shown in figure output voltage is compared with reference signal and given to PID controller. Output signal of PID controller is compare with saw tooth Waveform ,pulse generated by this trigger Q2 .In order to limit triggering of Q1 with same signal we add bias before comparing it with saw tooth. Two-mode control scheme the voltage conversion of the TSBB converter can be written as

   d1Vin, d2 = 0 (Vin )

   VH VL O

   Q2

   d1 Ts

   Mode switching point ve buck= vea + vbias Ts vsaw

   vea

   ve boost =

   d2 Ts

   Vo = {

   Vin d1 = 1(Vin < VO)

   1d

   2 Q1

   As shown in figure output voltage is compared with reference signal and given to PID controller. Output signal of PID controller is compare with saw tooth Waveform

   ,pulse generated by this trigger Q2 .In order to limit triggering of Q1 with same signal we add bias before comparing it with saw tooth

   Fig 2.TSBB converter under the two-mode control scheme.

   Control scheme is shown in fig 3

   Vo = VH – VL is the peak to peak value of the carrier. only one of Ve buck and Ve boost can intersect Vsaw at any time With the same carrier, in order to achieve the two-mode operation. So, it is required that

   Vebuck-Veboost Vsaw.

   Ve boost , and Ve buck is composed by adding a dc bias voltage, Vbias, to Vea. The output signal of the voltage regulator vea

   Ve buck= Vea + Vbias Ve boost = Vea

   Vbias Vsaw

   Two modulation signals and one carrier, Vbuck and Vboost are modulation signals of Q1 and Q2 and Vsaw is the carrier signal, VH and VL are maximum minimum value of carrier, When Vbuck is within VH and VL ,d1 Ts pulse generate. If same signal is given to trigger both switch we cant get desire output. So we introduce a bias value, that is bias value is added to the error signal before compare with saw tooth waveform in order to trigger Q1.When Vboost with in VH and VL ,d2 Ts pulse generate and it will trigger switch Q2.

   Fig 3 two-mode control scheme with two modulation signals and one carrier

   1. Modes of operation

      (a)

      (b)

      Fig4.Modes of operation (a) Buck mode: When Vin>Vo (b) Boost mode

      :When Vin<Vo

      VO = ton = D

      Vd Ts

      Vin=500V, Vout=360V

      D = 360 = 0.388 (3)

      500

      L = Ts VO (1 D)

      (2 IOMAX)

      L = 10(106)360(1.388)

      (216.67)

      L=66.08*10-6 H

      Boost converter:

      (4)

      VO = TS = 1

      Fig 5. Stimulation model of TSBB converter under the two-mode control scheme.

      Vd toff

      1 D

      Table 1.Parameters of the prototype:

      Vin=250V, Vout=360V

      parameter	symbol	value
      Input voltage	Vin	250-500V
      Output voltage	Vo	360V
      Output power	Po	6KW
      Full load resistor	RLd	21.6
      Switching frequency	fs	100KHZ
      Switches	Q1, Q2	SPW47N60C3
      Diodes	D1, D2	SDP30S120
      Filter capacitor	Cf	4080µF
      <>Filter inductor	Lf	320µH
      Peak to peak value of the carrier	Vsaw	2.5V

      D = 3 60 = 1.44 = 1 (5)

      250

      L = Ts VO D(1 D)

      (2 IOMAX)

      L = 10(106)360(216.67)

      (216.67)

      L=107.978*10-6H

      (6)

      Comparing buck and boost value we choose a higher value

      as 320µH Ripple RC =.004%

3. DESIGN

Input voltage, Vi = 250-500V Output voltage VO = 360V

1. Design of inductance value

Boost converter:

0

Output power PO = 6KW Full load resistor = 21.6

=

100

Switching frequency =100KHZ Filter capacitor= 4080µF

Filter inductor= 320 µH

Peak to peak value of carrier = 2.5V T=10µS

= .4360 = .0158 (8)

100

= 0

V2 =

R = 3602 = 21.6 (1)

6

OMAX

I = = 6 = 16 (2)

360

A. Design of capacitor Value

Buck converter:

= 360.388

3

10010 .01582

=4092.82µF

Buck converter: Ripple RC=.011%

= 0

100

(9)

= .11360 = .0408 (10)

100

= 0

3

C = 360.388

10010 .040821.6

= 4084.96µF

Comparing buck and boost value we choose a value as 4080 µH

1. MODIFIED CIRCUIT

   (11)

   Here we incorporate solar panel for house hold application with input voltage feed forward for the two switch buck boost (TSBB) dc dc converter. As we know voltage availability of solar panel chances with time, so we have to keep output voltage constant.

   Fig 6 shows modified circuit.

   Circuit consist of two switch buck boost cascaded circuit with input voltage feed forward path. Input voltage is from solar panel, for house hold application we have to keep output voltage constant. We keep a reference as 230V.When ever input voltage increase or decrease it keep output voltage constant. When input higher that output voltage buck operation occur, that is switch Q1 will trigger and step down the voltage to 230V.When input voltage is lower than output voltage boost operation occur, that switch Q2 will trigger and step up the voltage to 230V.

   Fig 6 .modified circuit

   (a)

   (b)

   Fig 7 (a) stimulation diagram of modified circuit(b) Sub system stimulation diagram

2. EXPERIMENTAL RESULT

   (a)

   (b)

   Fig8 .waveform of (a)DC Voltage(b)AC output

3. CONCLUSION

   By implementing solar panel along with two mode control scheme input voltage feed forward we can keep the output voltage a constant even if input voltage available from solar panel varies. The switching between buck and boost modes in this proposed control scheme is nearly smooth Reduce conduction loss, Reduce switching losses. High efficiency over the whole input voltage range and improved input voltage transient response. Reduce input disturbance.

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