Design and Comparison of Quadratic Boost Converter with Boost Converter

Design and Comparison of Quadratic Boost Converter with Boost Converter

Selva Kumar. R

M.E-Power Electronics and Drives, Bit Sathyamangalam, India

Vignesh.C. J

M.E-Power Electronics and Drives, Bit Sathyamangalam, India

Gayathri Deivanayaki. V. P M.E-Power Electronics and Drives, Bit Sathyamangalam, India

Naveena.P

M.E-Power Electronics and Drives, Bit Sathyamangalam,India

Abstract- In this paper the output voltage in renewable energy sources is improved by using DC-DC converter topology. Basically Boost converter is used for improving the voltage gain. In this converter switching frequency is limited, hence the output voltage is reduced. To overcome this issue, by combining the components of two boost converter by using single switch which improves the switching frequency and output voltage of converter. In this proposed paper for comparing the voltage stress and efficiency by using two converters topology.

Keywords- Boost converter, Quadratic Boost Converter, Voltage stress.

I.INTRODUCTION

In recent years for a great number of appliances dc- dc converter topology is employed. Normally in renewable energy system, the system having low output characteristics to recover this demand DC-DC converter topology is implemented. For maintaining the dc output voltage range in PV array and fuel cells, converter can be used to improve the output voltage. But during the switching operation the voltage stress will be raised. While choosing the converter the concentrating features are; when switch is turn on it must attain the zero voltage crossing, when Photovoltaic array is connected to the grid the converter should provide the high terminal voltage for low input range. The converter which

gives the high output range at low voltage stress is more

L D

Vin S C R

Fig.1 Circuit diagram for Boost converter

Two modes of operations are there,

Mode 1:

When the switch S is closed the inductor gets charged through the supply voltage and stores the energy. In this mode inductor current increases gradually, but we assume that the charging and the discharging of the inductor are linear. The diode blocks the current flowing and so load current remains constant which is being supplied due to the discharging of the capacitor.

L

D

efficient. Voltage gain generally based on the duty ratio hence by choosing the passive components the duty cycle ratio can be limited [7].

1. BOOST CONVERTER

   Boost converter is used to step up the given voltage to the desired voltage. The input to this converter may be from any DC source like rectifiers,solar panel,battaries etc,.

   Vin

   Mode 2:

   S C R

   Fig.2 Circuit Diagram for Mode 1 Operation

   When the switch S is open, the diode becomes

   The circuit diagram for Boost Converter is shown below,

   forward biased. The energy stored in the inductor changes it

   polarity to discharge through diode and charge the capacitor. Now, the capacitor supplies voltage to load. The load current remains constant throughout the operation.

   L D

   Vin S C R

   Fig.3 Circuit Diagram for Mode 2 Operation

   2.1 Output Equation for Boost Converter

   The voltage-current relation for the inductor L is,

   0

   0

   = 1 + 0 or

   Fig.4 Simulation Circuit for Boost Converter

   The inductor values for the converter is designed by using the formula given below,

   =

   When the switch is turned on,

   (1)

   = (1)2

   2

   Where,

   = duty cycle R = load

   (5)

   = ()

   When the switch is turned off,

   (2)

   Fs = switching frequency

   The capacitor values are designed from the formula given below,

   = (+)

   By equating the , we can solve the Vout

   (3)

   =

   Where,

   (6)

   (1)

   (1)

   =

   Neglecting the voltage drop across diode and transistor

   ,

   Vr = Ripple voltage Vo = Output Voltage

   =

   (1)

   (4)

   2.3 Simulation results for boost converter

   The Boost converter is simulated by using MATLAB 2013 and the circuit is shown in Fig.4. The input voltage given to the circuit is 10V and it works on 1 kHz switching frequency. Duty ratio () is varied to boost the output voltage in desired value.

   Fig.5 Output Voltage for Boost Converter

   Theoretically, the switches are ideal so there are no losses in the circuit. But in simulation circuit switches are non-ideal, therefore losses will occurs in the output voltage Thus the comparison is shown in Fig.6

   Boost Converter

   Boost Converter

   D2

   120

   100

   80

   60

   40

   20

   0

   120

   100

   80

   60

   40

   20

   0

   Output Voltage (Vout)

   Output Voltage (Vout)

   L1 L2

   Cal Vout

   Sim Vout

   Cal Vout

   Sim Vout

   Vin

   D1 D3

   C1 S C2 R

   0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

   Duty Cycle ()

   0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

   Duty Cycle ()

   Fig.6 Calculated and Simulated Output Voltage for Boost Converter

2. QUADRATIC BOOST CONVERTER

   The quadratic boost converter with a single switch is shown in Fig.7 where E is the input voltage, VC2 the output voltage and S independent switch. This model usually requires active and passive switches are to be appearing in pairs and to form a three-terminal network. However, this methodology can be extended for the analysis of the quadratic boost converter with a single switch, which

   Fig.8 Circuit Diagram for Mode 1 Operation of Quadratic Boost Converter

   Mode 2:

   In this condition D1 and D3 are forward biased, whereas D2 reverse biased. L1 and L2 are charging C1 and C2 respectively. During this state, iL1 and iL2 is decreased. The mode 2 circuit of quadratic boost converter is given in Fig.9

   3.1 Equation for Quadratic Boost Converter

   During mode 1state, iL1 and iL2 are increased by the amount defined by

   contains an active switch and three passive switches. Thus,

   ( ) =

   (5)

   diode D2 and transistor switch S are replaced by the corresponding current source, and diodes D1 and D3 by

   1

   ( )

   1

   = 1

   (6)

   voltage sources.

   D2

   2

   D2

   2

   L1 L2

   D1 D3

   L1 L2

   D1 D3

   Vin

   C1 S C2 R

   Vin

   C1 S C2 R

   Mode 1:

   Fig.7 Circuit Diagram for Quadratic Boost Converter

   The circuit operation is based on the assumption that

   Fig.9 Circuit operation for Mode 2 of Quadratic Boost converter

   In mode 2 state, 1 and 2 are decreased and it is expressed by

   the switch S is ideal in operation and capacitors C1 and C2 is taken as large value so that the voltage across the capacitors VC1 and VC2 are nearly constant over a switching period. When switch S is turned on D2 is forward biased, whereas D1 and D3 reverse biased. Currents are supplied to L1 and L2

   (

   (

   1 )

   2 )

   = (1)(1) . (7)

   1

   = (1)(1) ….. (8)

   2

   by Vin and C1 respectively. The mode 1 circuit of quadratic boost converter is given below in Fig.8.

   Hence the output voltage from the mode 1 and mode 2 operation is

   =

   =

   (1)2

   . (9)

   The inductor (1) is elected as per the formula given below,

   If =10V, =0.5 then the output voltage is given by 40V for the duty cycle 0.5 whereas the simulation output is

   1 =

   21

   …. (10)

   35.45V for the same input voltage.The simulation output of quadratic boost converter is shown below in Fig .11

   1

   0

   =

   =

   (1)2

   (11)

   The inductor (2) is selected as per the formula given below,

   2 =

   22

   (12)

   2

   = 0

   1

   (13)

   The capacitor (C1) is selected as per the formula given below,

   1 =

   (1)1

   (14)

   Fig.11 Output Voltage of Quadratic Boost Converter

   1

   = 1

   (15)

   Theoretically, the switches are ideal so there are no losses in the circuit. But in simulation circuit switches are non-ideal, therefore losses will occurs in the output voltage

   The capacitor (C2) is selected as per the formula given below,

   Thus the comparison is shown in Fig.12

   2 =

   300

   250

   200

   150

   100

   50

   0

   300

   250

   200

   150

   100

   50

   0

   Output Voltage (Vout)

   Output Voltage (Vout)

   2

   …. (16)

   2

   = 1

   Quadratic Boost Converter

   Quadratic Boost Converter

   1

   (17)

   Calculated

   Vout

   Simulated Vout

   Calculated

   Vout

   Simulated Vout

   On the component selection, For duty cycle ratio 0.1

   the inductor L1

   is 0.004 H, capacitor selection C1

   is 0.0004

   F, inductor L2 is 0.005 H and capacitor selection C2 is 0.0072F.

   3.3 Simulation results for Quadratic Boost Converter

   The quadratic boost converter is simulated with the input voltage of 10V. The switching frequency used is 1 kHz. The simulation circuit diagram for the quadratic boost converter is given below in Fig 10.

   Fig.10 Simulation Circuit Diagram for Quadratic Boost Converter

   0.10.20.30.40.50.60.70.8

   Duty Ratio (D)

   0.10.20.30.40.50.60.70.8

   Duty Ratio (D)

   Fig.12 Calculated and Simulated Output Voltage for Quadratic Boost Converter

3. COMPARISON RESULTS

   For Boost converter on the basis of theoretical and simulated output it is verified that for the input voltage of 10V the output get boosted only upto 20V at duty ratio 0.5.But in Quadratic Boost converter for the same input voltage the output get boosted up to 40V for same duty ratio.

   Duty Ratio	Boost Converter
   	Input Voltage (V)	Input Current (A)	Output Voltage (V)	Output Current (A)	Efficiency
   0.2	10	3	11.63	1.173	45%
   0.5	10	7.5	18.91	1.891	48%
   0.7	10	14.9	30.57	3.057	62%

   Duty Ratio	Boost Converter
   	Input Voltage (V)	Input Current (A)	Output Voltage (V)	Output Current (A)	Efficiency
   0.2	10	3	11.63	1.173	45%
   0.5	10	7.5	18.91	1.891	48%
   0.7	10	14.9	30.57	3.057	62%

   Table.1 Output Analysis of Boost Converter

   Table.2 Output Analysis of Quadratic Boost Converter

   Duty Ratio	Quadratic Boost Converter
   	Input Voltage (V)	Input Current (A)	Output Voltage (V)	Output Current (A)	Efficiency
   0.2	10	0.3	13.54	0.1354	61%
   0.5	10	1.85	35.35	0.3535	67%
   0.7	10	10.5	88.26	0.8826	74%

   Table.3 Efficiency Comparison

   Duty Ratio	Efficiency
   	Boost Converter	Quadratic Boost Converter
   0.2	45%	61%
   0.5	48%	67%
   0.7	62%	74%

   Voltage stress on switches

   The switching pulse is given to the switches to transfer the maximum output to the load from the given input. When the switching pulse is given to the switches then there will be some stress on the switches due to frequent turn on and turn off. The stress on the switches is shown below in Fig.13.

   Fig.13 Waveform For Voltage Stress On Switches

4. CONCLUSION

   The voltage stress across the switches should be reduced to increase the efficiency of the converter. The boost converter is limited by switching frequency because of the stress on the switch. The quadratic boost converter has more switching components but it has equal stress as boost converter. On same duty ratio quadratic boost converter provides with high output voltage then the boost converter. As comparison results the quadratic boost converter is convinent for the PV panel and fuel cells then the boost converter.

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