ABB ACS355 series, Manual

Page: 16 / 78

16 Operating principle and hardware description
To switch between local and remote control modes use the LOC/REM key on the control
panel. For more information, see section
How to start, stop and switch between local and
remote control in ACS355 user’s manual (3AUA0000066143[English]) .
Note : Ensure that the inverter is in local control before starting or stopping the inverter
using the control panel.

Control panels
The solar pump inverter works with either of the two different control panel types:
•
Basic control panel—provides basic tools for manual entry of parameter values.
•
Assistant control panel—includes pre-programmed assistants to automate the most
common parameter setups and provides language support.
For more information, see section Control panels in ACS355 User’s manual
(3AUA0000066143 [English]) .
See Start-up procedure section for information on Viewing or Editing parameter values
using control panel.
MPPT overview

Theory
The solar pump inverter uses the maximum power point tracking (MPPT) control program
to improve the efficiency of solar energy systems. The output of the photovoltaic (PV) cell
is proportional to its area and intensity, while the output voltage is limited by p-n junction
from 0.6 to 0.7 V. Therefore when the output voltage is constant, output power is
proportional to intensity and surface area. The current and voltage at which the PV cell
generates maximum power is known as the maximum power point.

Operation
The MPPT controller follows different strategies to derive the maximum power from the PV
array. The internal MPPT algorithm is used to derive maximum power from the PV cell at
any instant. This is achieved by modifying the operating voltage or current in the PV cell
until the maximum power is obtained.
When the output voltage is zero, the PV cells create short circuit current. If the PV cells are
not connected to any load, the output voltage is equal to the open circuit voltage. The
maximum power point is obtained at the knee of the I-V curve. See the I-V characteristics
shown below.