Electronic Engl

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    Electronic Components for

    Photovoltaic Solarsystems

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    LoadSolar

    Generator

    Principal Circuit of a PV-Solarsystem

    StorageElectronicControl Syste

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    Lead Acid

    Accumulator

    LoadSolarGenerator

    Charge Controller

    Circuit of a Solar Home System with

    Charge Controller

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    Tasks of a Charge Controller:

    Overcharge protection

    Over charge protection: - Strom Gassing has to be prevented- Circulation of the Acid- Battery has to be charged properly

    - Preventing Backward Current at NightV [V]

    t [h]

    UnlimitedCharging

    Boost

    Stand By Charging

    Vopt=f(T;SOC)

    Equalize

    LimitedCharging

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    Overcharge Protection:

    Types of Charge Controllers

    SolarGenerator

    +

    -

    Parallel- or Shunt- Controller Design:

    PowerSwitch

    ControlCircuit

    BackwardDiode

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    Overcharge Protection:

    Types of Charge Controllers

    Parallel- or Shunt- Controller Design:

    Problems:

    - Current from Solar Generator cannot beinterrupted

    - Short Circuit can Effect Hot Spot

    I

    V

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    Overcharge Protection:

    Types of Charge Controllers

    SolarGenerator

    +

    -

    Serial- Controller Design:

    PowerSwitch

    ControlCircuit

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    Overcharge Protection:

    Types of Charge Controllers

    Serial- Controller Design:

    Advantages:

    - Current can be Interrupted

    - No risk of Hot Spot

    I

    V

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    Overcharge Protection:

    Types of Charge Controllers

    Different Control Circuits:

    Continues Regulation (Switch is partly conductive)

    - Very high power losses

    On-Off Regulation (with Hysteresis)

    - No Prober Charging!!!

    - only way to use relay

    PWM Regulation

    - Low losses and proper charging

    - Need MOS-FET

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    Overcharge Protection:

    Types of Charge Controllers

    +-

    PWM:

    Signal for Power Switch

    PowerSwitch

    ControlCircuit

    t [ms]

    Switch

    Conductive

    Non conductive

    T < 100ms

    t 1 t 2

    t1 and t2 are variable; T is fixed

    t 1 t 2

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    Overcharge Protection:

    Types of Charge Controllers

    Conclusions:

    Best solution is

    - Series Controller- PWM

    - Temperature Compensation

    - Float, Boost and Equalize Cycle

    Never use

    - Relay

    Be careful

    - Shunt Controller

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    Tasks of a Charge Controller:

    Overdischarge Protection

    Overdischargecharge protection:

    - Prevention of deep discharging

    - Prevention of Sulfation

    - Prevention of Overcurrent and

    Short Circuit

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    Overdischarge Protection:

    Types of Charge Controllers

    +

    -

    Power Electronic Design:

    PowerSwitchControl

    Circuit

    Load

    I

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    Overdischarge Protection:

    Types of Charge Controllers

    State Of Charge (SOC) Calculation:

    Target

    -Load Cut Off at SOC=30%

    ISIL

    UBSOC=90%

    SOC=30%

    SOC=f(I;SOC;T;Age;.......)

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    Overdischarge Protection:

    Types of Charge Controllers

    Load Cut Off at

    Constant Voltage

    Evaluation- average failure 50%

    - max. failure 100%!!

    ISIL

    UBSOC=90%

    SOC=30%

    SOC=f(I;SOC;T;Age;.......)

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    Overdischarge Protection:

    Types of Charge Controllers

    Load Cut Off at

    Current Controlled

    Voltage

    Evaluation

    - average failure 20%

    - max. failure 30%

    ISIL

    UBSOC=90%

    SOC=30%

    SOC=f(I;SOC;T;Age;.......)

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    Overdischarge Protection:

    Types of Charge Controllers

    SOC Calculation

    with Fuzzy Logic

    Evaluation- average failure 10%

    - max. failure 20%

    ISIL

    UBSOC=90%

    SOC=30%

    SOC=f(I;SOC;T;Age;.......)

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    Tasks of an charge controller:

    Communication

    Display:

    - SOC- Load and Charge Current

    - Voltage

    - Failure Display

    - Additional acoustical

    signal support warnings!!

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    Main problem in rural electrification: Sulfation

    1.Tag Nacht 2.Tag Nacht 3.Tag Nacht 4.Tag Nacht 5.Tag Nacht 6.Tag Nacht 7.Tag Nacht 8.Tag Nacht

    0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    100

    Abs cha ltsch we lle

    Ladezustand

    Lead sulfate grows to large crystals --> accumulator cannot be charged

    and discharged anymore!!!

    Overdischarge Protection:

    Types of Charge Controllers

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    Main problem in rural electrification: Sulfation

    Overdischarge Protection:

    Types of Charge Controllers

    Sulfation depends on:

    - SOC

    - Acid density

    - duration of discharge

    A new type algorithm can calculate

    the risk of sulfation

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    1 .Ta g N a ch t 2 .Ta g N ac ht 3 .Ta g N ac ht 4 .Ta g N ac ht 5 .Ta g N ac ht 6 .Ta g N ac ht 7 .Ta g N ac ht 8 .Ta g N a ch t

    0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    100

    Abschaltschwelle

    Ladezustand

    SOS Parameter

    New method against sulfation:

    The Cut off level is increased under higher risk of sulfation

    Overdischarge Protection:

    Types of Charge Controllers

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    Advances charge controllers:

    MPP-Tracking

    V

    IMaximum Power PointMPP

    IMPP=f(B)UMPP=f(T)

    ==

    UMPP UL

    V

    PAdaptiv-

    Regler

    Power Gain:

    10-25%

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    Solar

    Generator

    +

    -

    Power

    Switch

    ControlCircuit

    Advanced charge controllers:

    MPP-Tracking

    Switch is PWM controlled

    Vi Vo

    Vo = t1/T x ViFunction of MPPT

    t 1

    T

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    Advanced charge controllers:

    Excess Energy Management

    SolarGenerator

    +

    -

    PowerSwitch

    ControlCircuit

    Excessload

    PWM1

    PWM2

    (sometimes

    On-Off Signal)

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    Advanced charge controllers:

    Hybridsystems

    SolarGenerator

    +

    -

    PowerSwitch

    ControlCircuit

    Dumpload

    PWM1

    PWM2

    G

    Wind- or

    Hydrogenerator

    Solar Hybrid System with Wind or Hydrogenerator

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    Advanced charge controllers:

    Hybridsystems

    SolarGenerator

    +

    -

    PowerSwitch

    ControlCircuit

    PWM

    G

    Fuelcell or

    Dieselgenerator

    Solar Hybrid System with Fuelcell or Dieselgenerator

    On-Off

    Signal