SLVAFT9 June   2024 TPS61022 , TPS61023

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction of Photovoltaic Cell and MPPT Requirement
  5. 2Typical Battery Powered Outdoor System with PV Panel
  6. 3MPPT Method with Generic DC/DC Converter
    1. 3.1 TPS61023 Introduction
    2. 3.2 Hysteresis Control MPPT Method with TPS61023
    3. 3.3 Experiment Results
  7. 4Summary
  8. 5References

1 Introduction of Photovoltaic Cell and MPPT Requirement

As an important component of PV system, photovoltaic cells have a complex relationship about operating voltage and the power produced. The equivalent circuit of the solar cell is shown as Figure 1-1, RS is the series resistance of a single cell connected to others, RP is parallel leakage resistance and large, typically > 100kΩ.

Solar Cell Equivalent Circuit Figure 1-1 Solar Cell Equivalent Circuit

For any given set of conditions, cells have a single operating point where the values of the current (I) and voltage (V) of the cell allow maximum power output. Figure 1-2 shows the typical I-V curve and P-V curve of a general PV panels at different times in a day, where the light is strongest at noon, moderate in the morning and poor in the evening.

Solar Panel I-V and P-V Curve Figure 1-2 Solar Panel I-V and P-V Curve

The no-load output voltage VOC is 3.3V approximately 3.5V under different light conditions. The output voltage of the solar cells decreases at first as the load current increases. When the output voltage is less than 2.9V, the output current almost unchanged, so 2.9V here is the so called maximum power point (MPP) of this PV panel, and generally engineer needs to make sure that the PV panel operates at this MPP so that the PV panel can always output maximum power.

Therefore, a MPPT (maximum power point tracking) method is used to maximize energy extraction as conditions vary, make sure that the PV system always operate at the maximum output power point.