1 / 62

Solar Power DC-DC Converter

Solar Power DC-DC Converter. CONTENT. Abstract: Solar Cell Knowledge;. Characteristic Equation: I = I L − I D − I SH V j = V + IR S Shockely Diode Equation:. Variation in internal R cause o/p voltage variation.

gail-lane
Download Presentation

Solar Power DC-DC Converter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Solar Power DC-DC Converter

  2. CONTENT

  3. Abstract:Solar Cell Knowledge; Characteristic Equation: I = IL − ID − ISH Vj = V + IRS Shockely Diode Equation: • Variation in internal R cause o/p voltage variation. • Intensity is inversely proportional to current, which limits at constant voltage.

  4. I-V characteristic Of Solar cell: • Direct connection to battery is not possible due to variation in battery voltage. • Varying sunlight affects current, hence electronics to optimize power is needed.

  5. BOOST TOPOLOGY:

  6. IC No:MAX856-MAX859 Features: • 0.8V to 6.0V Input Supply Voltage • 85% Efficiency at 100mA • Pin-selectable output voltage of 3.3V or 5V • Circuit extracts the maximum power from a solar array to charge a battery stack • Up to 500kHz Switching Frequency Relevant Link: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1207 http://www.maxim-ic.com/appnotes.cfm/an_pk/484

  7. Circuit For MAX856

  8. This circuit enables a seven-cell solar panel to charge a three-cell NiCd battery

  9. Operation:High Efficiency C-MOS switching regulator: • The MOSFET used has very low threshold voltage to ensure start-up at low voltages. • Unique minimum turn-off time PFM control scheme is unique feature of the device. • No oscillator; switching is accomplished by a pair of one shots that set a maximum LX on-time (4.5μs type) and a minimum LX off-time(1μs). LX on-time will be terminated early if the inductor current reaches 0.5A before 4.5μs elapses. • Device has a low battery detection facility. • Bootstrapped device , hence can turn on at very low voltage.

  10. Usage: • 2-Cell and 3-Cell Battery-Operated Equipment • 3.3V to 5V Step-Up Conversion • Glucose Meters • Medical Instrumentation • Palmtop Computers • Personal Data Communicators/Computers • Portable Data-Collection Equipment • Solar Powered Applications

  11. IC No:MAX866-MAX867(Using MAX1771 boost controller) Features: • 0.8V to 6.0V Input Supply Voltage • 80% Efficiency Over Wide Load Range • 0.9V Guaranteed Start-Up Supply Voltage • Provide 5V rail under full load and as low as 0.8V input voltage • Up to 250khz Switching Frequency • A two-step approach (Figure ) enables the system to start up and produce the 5V rail under full load. Relevant Link: http://www.maxim-ic.com/appnotes.cfm/an_pk/1029

  12. Typical Operating Circuit:

  13. This two-stage step-up converter derives 0.5A at 5V from a typical solar-cell array, and guarantees start-up under full load.

  14. Usage: • 1-Cell Battery-Operated Equipment • Backup Supplies • Detectors • Pagers • Remote Controls • Solar Powered Applications

  15. IC No:TPS61200 TPS61201 TPS61202 Features: • Operating Input Voltage Range from 0.3 to 5.5 • More than 90% Efficiency at • 300 mA Output Current at 3.3 V (VIN ≥ 2.4 V) • 600 mA Output Current at 5 V (VIN ≥ 3 V) • Start-up into Full Load at 0.5 V Input Voltage • Fixed and Adjustable Output Voltage Options from 1.8 V to 5.5 V Relevant Link: http://focus.ti.com/docs/prod/folders/print/tps61200.html

  16. Solar cell current depends on area and light intensity. As an effect its important to control current in an application. • This can be done either by limiting current to a certain value or controlling power circuit to operate in most efficient manner. • This is accomplished by keeping I/p voltage to a Certain value where power delivered to supply is maximum , called as maximum power point regulation(MPP). • This circuit also helps in start-up by avoiding access current to flow.

  17. Operation:Average Current Mode topology: • Fixed frequency PWM with synchronous rectification. • Average inductor current is regulated by a fast current regulator which is controlled by a voltage control loop. • Changes in i/p and o/p voltages is monitored through feed-forward , and can immediately change the o/p to achieve fast response to these errors. • Controller also sense the maximum peak current for stable and safe operation. • 3 N-MOSFETs to maintain synchronous power conversion. • Down regulation circuit is turned on when i/p exceeds o/p voltage, in this mode controller changes the behavior of 2 MOSFET switches to ensure proper and stable regulation of o/p voltage.

  18. Power saving mode facility is available to improve efficiency at light loading conditions and low frequency. • Under-voltage lock out, over temperature protection, over voltage protection, soft start , short circuit protection is provided. • Due to efficiency constraints i/p current can sometimes be more than 10-20 times that of o/p current at some of operating states and during start-up as impedance is low high current flow can occur.

  19. Usage: • All Single-Cell, Two-Cell and Three-Cell Alkaline, • NiCd or NiMH or Single-Cell Li Battery Powered Products • Fuel Cell And Solar Cell Powered Products • Portable Audio Players • PDAs

  20. IC No:TPS61097-33 Features: • Operating Input Voltage Range From 0.9 V to 5.5 V • Up to 95% Efficiency at Typical Operating Conditions • Fixed Output Voltage Options From 1.8 V to 5.0 V • Power-Save Mode for Improved Efficiency at Low Output Power • Over temperature Protection Relevant Link: http://focus.ti.com/docs/prod/folders/print/tps61097-33.html

  21. Typical Operating Circuit:

  22. OPERATION:Synchronous boost topology. For power switching two actively controlled low R MOSFETs are used. • Controller Circuit • Hysteretic Current Mode controller. • VOUT is monitored through FB n o/p is reflected in current offsetwhich regulates the o/p voltage. • Bypass switch turns off when EN is high to make IC as standard Boost Converter , when EN is low it turns on n bypasses I/p to O/p. • For low i/p start up circuit turns on to build up sufficient voltage. And as soon as voltage reaches 1.8V it turns of and i/p voltage controls the circuit. • Circuit provides under voltage lockout, overvoltage protection, over temperature protection.

  23. Inductor Selection: 4.7μH show good performance over wide range of i/p and o/p.

  24. Usage: • All Single-Cell, Two-Cell, and Three-Cell Alkaline, NiCd, NiMH, or Single-Cell Li-Battery Powered Products • Personal Medical Products • Fuel Cell and Solar Cell Powered Products PDAs • Mobile Applications • White LEDs

  25. IC No:TPS61220,TPS61221,TPS61222 Features: • Operating Input Voltage Range From 0.7 V to 5.5 V • Up to 95% Efficiency at Typical Operating Conditions • Fixed Output Voltage Options From 1.8 V to 5.0 V(also available in fixed voltage) • Power-Save Mode for Improved Efficiency at Low Output Power • Over temperature Protection Relevant Link: http://focus.ti.com/docs/prod/folders/print/tps61220.html

  26. Typical Operating Circuit:

  27. Working is same as TPS61097-33:

  28. Usage: • All Single-Cell, Two-Cell, and Three-Cell Alkaline, NiCd, NiMH, or Single-Cell Li-Battery Powered Products • Fuel Cell and Solar Cell Powered Products • PDAs • Mobile Applications • White LEDs

  29. IC No:TPS61020,TPS61024,TPS61025,TPS61026,TPS61027, TPS61028, TPS61029 Features: • Input Voltage Range: 0.9 V to 6.5 V • 96% Efficient Synchronous Boost Converter • Fixed and Adjustable Output Voltage Options Up to 5.5 V • Output Voltage Remains Regulated When Input Voltage Exceeds Nominal Output Voltage • Low EMI-Converter (Integrated Anti ringing Switch) Relevant Link: http://focus.ti.com/docs/prod/folders/print/tps61020.html

  30. Operation:Fixed Frequency PWM using Multiple feed forward topology : • I/p , o/p and voltage drop on N MOSFET is monitored and forwarded to regulator.(It avoids a slow way through control circuit and error amplifier, and hence increased o/p response). • So control circuit has to handle only small error signal through FB to create more stable o/p. • Peak current on N-MOSFET is sensed to limit current to 1.5A. • Device integrates 2 N and P MOSFETS, due to use of low R P channel MOSFET instead of Schottky rectifier increases efficiency. • Special circuit is deployed using back-gate diode of P-MOSFET to disconnect the o/p load from battery when EN is low. IT hence avoids depletion of battery during shutdown.

  31. Two grounds(GND & PGND) to avoid ground shift. • Down regulation mode is turned on when i/p voltage exceeds o/p voltage, in this mode behavior of P-MOSFET changes accordingly to regulate the voltage. • Circuit enters into a PRECHARGE phase during startup to avoid large current. In this phase it charges the different capacitor till o/p reaches to a certain value. • Circuit provides short circuit protection, under voltage lockout, thermal protection, overvoltage protection. • Device integrates a circuit to avoid ringing when device enters into discontinuous mode.

  32. Usage: • All One-Cell, Two-Cell and Three-Cell Alkaline, NiCd or NiMH or Single-Cell Li Battery, Solar Powered Products • Portable Audio Players • PDAs • Cellular Phones • Personal Medical Products • Camera White LED Flash Light

  33. IC No:ZXSC100 Features: • Efficiency maintained over a wide range of input voltages and load currents82% efficiency @ Vin=1V • Start up under full load • Minimum operating input voltage Vin=0.926V • Adjustable output voltage down to Vin to 20 v • Quiescent current typically 150μA referred to input voltage Relevant Link: http://diodes.com/products/catalog/detail.php?item-id=1624&popup=datasheet

  34. Operation:Non-Synchronous PFM DC-DC controller IC: • Shutdown circuits turns on/off when VCC=1v. • At start up COMP1 turns on, hence driver circuit and switching transistor. This circuit will remain active until voltage at FB exceeds 730mV. • An external resistive network at FB sets the o/p voltage level . • COMP 2 forces switching transistor to turn off when Isense (voltage at emitter of switching transistor)voltage exceeds 25mV. • A mono-stable following the COMP2 extends turn off time of drive to minimum of 2 µS ensuring sufficient time for discharge of inductor. • AND gate ensures switching transistor is always on until Isense threshold is reachedand minimum discharge period is always asserted.

  35. Usage: • Cordless telephones• MP3 players• PDA• Pagers• Battery backup supplies• Electronic toothbrush• GPS receivers• Digital camera• Palmtop computers• Hand held instruments• Portable medical equipment• Solar powered equipment

  36. Other Important IC`s MAX1678(Efficient 1-Cell Step-Up Converter) • 0.87V Guaranteed Start-Up • Up to 90% Efficiency • Efficient 1-Cell Step-Up Converter • Output voltage is preset to 3.3V or can be adjusted from +2V to +5.5V • Vin=.7v to 5.5 v • 45mA Output Current at 3.3V for 1-Cell Input • 90mA Output Current at 3.3V for 2-Cell Input

  37. Circuit For MAX1678

  38. IC No:TPS63000,TPS63001,TPS63002 Features: • Input Voltage Range: 1.8V to 5.5V • Up to 96% Efficiency • Fixed and Adjustable Output Voltage Options from 1.2V to 5.5V • Automatic Transition between Step Down and Boost Mode • Up to 800-mA Output Current at 3.3V in Boost Mode (VIN > 2.4V) Relevant Link: http://focus.ti.com/docs/prod/folders/print/tps63000.html

  39. Operation:Device is based on average current topology: • Almost same as that of TPS61200 with some minor differences in voltage levels .

  40. Usage: • All Two-Cell and Three-Cell Alkaline, NiCd or NiMH or Single-Cell Li Battery Powered Products • Portable Audio Players • PDAs • Cellular Phones • Personal Medical Products • White LEDs

More Related