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Presented ByMalik Sameeullah

M.Tech (RES)

NATIONAL INSTITUTE OF TECHNOLOGY, KURUKSHETRA

MPPT BASED OPTIMAL BATTERY CHARGE CONTROLLER IN PV SYSTEM

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ContentsSolar PV SectorType of Solar PV systemNeed of Charge Controller and MPPTSolar PV Cell: Basic modelType of Battery: features and characteristicsBasic Charge controller modelBuck Boost ConverterMPPT modelMPPT Based Optimum Controller DesignConclusionResearch Work and Future WorkReferences

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Solar Power Sector India lies in a sunny tropical belt (High

insolation) Total approximate potential annually over 5000 trillion kWh

Over 70% of India’s households experience significant power cuts every year

National Solar Mission and other Generation Based Incentives (GBI) are available through Ministry of New and Renewable Energy (MNRE)

JNNSM have a mission to install 20 GW solar PV plant by 2022

Cost of PV module, land scarcity and technological barrier is a main restriction.

Current cost of production is ` 12/KWh and expected cost is ` 6/KWh by 2020

Jawahar Lal Nehru National Solar Mission Target

2010-2013

On grid PV power of 1000-2000 MWOff grid PV application 200 MWSolar collector 7 million sq. meter

2013-2017

On grid PV power of 4000-10000 MWOff grid PV application 1000 MWSolar collector 15 million sq. meter

2017-2022

On grid PV power of 22000 MWOff grid PV application 2000 MWSolar collector 20 million sq. meter

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Type of Solar PV SystemSolar PV System

Grid Connected

PV

Large scale production

(Without Battery)

With Battery(Smart Grid

concept)

Off Grid PV System

With Battery(e.g. for houses and

industries)

Without Battery(PV water Pump)

Hybrid PV System

Wind-PV hybrid system

PV-Diesel hybrid System

PV based Utilities

Solar Lamp, Solar mobile charger etc.

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Need of Charge Controller and MPPTBattery is a costly device and must be managed properly.

It is found if proper care is taken then life of battery increase significantly

A charge controller limits the rate at which electric current is added to or drawn from electric batteries

Charge Controller take care of battery under voltage and over voltage condition

MPPT (Maximum Power Point Tracker) is a electronic device which maximize PV module output under varying operating condition

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Solar PV Cell: Basic ModelSolar cell is a device that converts the light energy into

electrical energy based on the principles of photovoltaic effect.

A typical silicon PV cell is composed of a thin wafer consisting of an ultra-thin layer of phosphorus-doped (N-type) silicon on top of a thicker layer of boron-doped (P-type) silicon.

Current flow caused by light is known as light generated current

Illumination

Dark conditionI

V

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Solar PV Diode Model

Equivalent circuit of PV cell I-V curve of PV cell

P-V curve of PV cellMatlab simulation model of PV cell for Isc 1 amp and Voc 0.55 V, Insolation of 1000 W/

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BatteryThe cell is the basic electrochemical unit in a battery,

consisting of a set of positive and negative plates divided by separators, immersed in an electrolyte solution and enclosed in a case.

Nominal cell voltage is 2.1 V for lead acid battery

Primary function of battery in PV system:

1. Energy storage and autonomy

2. Voltage and current stabilization

3. Supply surge current

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Secondary battery types and characteristicsBattery Type Cost Deep cycle

PerformanceMaintenance

Flooded Lead Acid

Lead Antimony Low Good highLead-Calcium open vent Low Poor MediumLead-Calcium sealed vent Low Poor LowLead Antimony/Calcium hybrid

Medium Good Medium

Captive Electrolyte Lead Acid

Gelled Medium Fair LowAbsorbed glass Mat Medium Fair LowNickel-Cadmium

Sintered Plate High Good NonePocket Plate high good Medium

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Battery ParametersBattery Capacity (Ah): It is the

maximum charge storage capacity of a battery.

Battery Voltage (V): It is the terminal voltage of battery under no load condition

Depth of Discharge (DoD): This is a measure of how much energy has been withdraw from a battery.

Battery Life cycle: It is defined as number of complete charge-discharge cycle that battery can perform before it nominal capacity fall below 80% of initial value

Graph between Depth of Discharge and Life cycle of batteries(data is approx.)

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Factor Affecting Battery PerformanceOperating voltage rangeMagnitude of battery discharge currentBattery temperature during dischargeChoice of battery for particular application

Ideal charging characteristics for a lead-acid battery

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DC-DC ConverterUsed for converting DC voltage from one level to anotherIt is used to convert unregulated DC into a controlled DC

outputSuitable for PV system where due to change in

atmospheric condition DC output change continuouslyIt is also a basic component of MPPT system

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Topologies of DC-DC Converter

Isolated type converter

Flyback

Half Bridge

Full Bridge

Non-Isolated type converter

Buck-Boost

SEPIC

Cuk

Grid tied system used this topologies, as isolation is required for safety reason

Most of the DC drive used this converter. No need of transformer .

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Basic ConverterIt consist of switch which operate

continuously to maintain output voltage

Fundamental switching converter circuit

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BUCK Converter• Used for step down of DC

voltage

Output Voltage where D is a duty cycle

BOOST Converter• Used for step up of DC

voltage

Output Voltage

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BUCK-BOOST ConverterBuck-Boost converters make it possible to

efficiently convert a DC voltage to either low or high voltage

It is useful for PV maximum power point tracking

It can be obtained by cascade connection of Buck and Boost converter

Output Voltage The basic principle of the buck–boost operation1. While in the On-state, the input

voltage source is directly connected to the inductor (L). This results in accumulating energy in L. In this stage, the capacitor supplies energy to the output load.

2. While in the Off-state, the inductor is connected to the output load and capacitor, so energy is transferred from L to C and R.

Buck Boost Converter

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Type of Charge Controller Shunt Type Charge Controller Series Type Charge Controller

DC-DC Converter Type Charge Controller

MPPT Charge Controller

Shunt Converter Series Converter

No additional losses due to switch and better regulation of battery charging

DC-DC converterPV

array

LOAD

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Maximum Power Point TrackingIt consist of electronic circuit allow to collect maximum power from PV module under different condition

PVarray

R

• Control signal vary duty cycle of converter

• For Buck converter , equivalent impedance of load reflected at source side is given by:

a

b

c

b’

c’

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Hill Climbing MethodMost popular algorithm for MPPT In this method Panel power and voltage is measure

continu0solyOn the left side of Maximum power point, slope is positiveOn the right side of Maximum power point, slope is positiveRegion near to maximum power point slope is zero Function of algorithm is given by:

1. In the voltage source region, D=D + D2. In the current source region, D=D - 3. At MPP, =0 D=D (no change)

• Hill climbing method fail under rapid environment change condition

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Algorithm of Hill Climbing MethodStart

Set duty

Read ,

=*

𝑃𝑛𝑒𝑤>𝑃𝑜𝑙𝑑

𝑉 𝑛𝑒𝑤>𝑉𝑜𝑙𝑑

D=D -

= ,

D=D +

𝑉 𝑛𝑒𝑤>𝑉𝑜𝑙𝑑, Yes

Yes

Yes

NoNoNo

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Standalone PV SystemFor standalone system to category of converter

used, 1. Renewable side converter (RSC) and 2. Storage side converter

Inputs are actual PV voltage, PV current, battery voltage and battery current

Measurement of battery current provide additional protection again overcurrent condition

Circuit diagram of charge controller

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Optimal Charge Controller Logic

Controller of DC-DC converter

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Study of Output Response of Controller

Conventional controller outputHill Climbing MPPT Method track for maximum power and for battery voltage higher than maximum limit than need to open switch

Proposed schemeIt always track for maximum power condition. when battery voltage or current is above the set limit than it try to push converter toward low power extraction region and provide better charging control

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ConclusionIn solar PV based battery charging, MPPT

algorithms are used When the state of charge (SoC) of battery is

high and system is on no-load, excess power flows into the battery

This results in low operational life of the battery

Slight variation in design of MPPT improve the charging condition of battery

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Research Area and Future WorkThere is number of MPPT control algorithm.

Fuzzy and Neural network based MPPT algorithm are more accurate.

No of improved DC-DC converter topologies are in picture like CUK converter, Isolated converter etc.

By choosing the optimal combination of DC-DC converter and MPPT algorithm better regulation of battery is possible

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References1. Sandeep Anand, Rajesh Singh Farswan, Bhukya Mangu, B.G. Fernades, “Optimal

charging of Battery Using Solar PV in Standalone DC System,” Industrial Electronics Magazine , vol.7, no-3,pp.6 – 20, Sep 2013

2. Trishan Esram, and Patrick L. Chapman, “Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques,” IEEE Trans. on Energy Conversion, vol. 22, no. 2, June 2007

3. Tom Markvark, Luis Castaner,” Solar Cells: Material, Manufactures and operation,” Elsevier, ISBN-1856174573

4. Chetan Singh Solanki, “Solar Photovoltaic: Fundamentals, Technology and Applications,” Eastern Economy Edition, ISBN-9788120343863

5. Simon S. Ang, “Power Switching Converters,” Marcel Dekker Inc., ISBN-0824796306

6. Paras Karki, Brijesh Adhikary, “ MATLAB/Simulink based Modeling and Simulation of Gird-connected Solar Photovoltaic System in Distribution Power Network,”Fifth International Conference on Power and Energy Systems, Kathmandu, Nepal, pp.28 - 30 October, 2013

7. James P. Dunlop, P. E. Florida, “Batteries and Charge Control in Stand-Alone Photovoltaic Systems Fundamentals and Application,” Solar Energy Center1-679, Clearlake RoadCocoa, FL 32922-5703

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