General Description And Principles Of Operation - Samlexpower Evolution EVO-2212 Owner's Manual

SECTIOn 4 |
4.1 generAl DeScriPtion
EVO is a Pure Sine Wave, bi-directional, Single-Phase Inverter / Charger with a Transfer relay that
operates either as an inverter Or as a smart battery charger. It uses a common Converter Section
that can work in two directions – in one direction it converts external AC power to DC power
to charge the batteries using Grid or Generator (Charging Mode) and in the other direction, it
converts DC power from the battery to AC power (Inverting Mode). This allows the same power
components to be used in both directions resulting in high-energy transfer efficiency with fewer
components. Please note that it can NOT work in both the directions at the same time (i.e. it can-
not work as an inverter and as a charger at the same time).
high performance 100 Mhz DSP (Digital Signal Processing) type of micro-controller and Pulse
Width Modulated (PWM) conversion circuits are used for the above implementation.
4.2 comPonentS of the SyStem
It consists of 3 Sections – Inverter Section, battery Charger Section and AC Input/Transfer relay
Section. The unit is fed with the following inputs:
up to 2 external AC input power sources – Grid or Generator or both with PrIOrITy for Grid
–
if both Grid and Generator inputs are available at the same time
DC battery Source consisting of 12V/24V battery bank. - 4 versions of EVO are available. 2
–
versions for 12 VDC battery input (EVO-2212 and EVO-3012) & 2 for 24 VDC battery input
(EVO-2224 and EVO-4024)
Additional external charging source like Solar Charge Controller / AC charger of up to 50A
–
capacity. The output of the external charging source is routed through this unit and operates
in parallel with the internal charger. The internal charging current is controlled to ensure that
the combined current fed to the battery does not exceed the programmed bulk Charging
Current. This improves the life of the battery.
4.3 inverter Section
The Inverter Section is a heavy-duty, continuous rated, DSP micro-controller based inverter gen-
erating a Pure Sine Wave output of 120 VAC, 60 hz / 50 hz (60 hz default) from the DC battery
Source. It is able to supply AC power to various types of AC loads such as resistive loads (heaters,
incandescent lamps etc) or reactive loads (motors, air conditioners, refrigerators, vacuum clean-
ers, fans, pumps, Switched Mode Power Supplies (SMPS) used in audio / video equipment and
computers, etc.).
4.3.1 Principle of working of inverter Section
The low DC voltage from the DC battery Source is inverted to the AC voltage in two steps. The low
DC voltage from the DC battery Source is first converted to low frequency (60 hz or 50 hz), low
voltage synthesized sine wave AC using an h-bridge configuration and high frequency PWM (Pulse
Width Modulation) technique. The low frequency, low voltage synthesized sine wave is then stepped
up to 120 VAC pure sine wave voltage using a low frequency Isolation Transformer and filtration
circuit. This type of DC to AC inversion is called hybrid Type – a combination of low frequency and
high frequency implementation. Other distinctive features of the Inverter Section are given below:
Soft Start: The inverter design incorporates "Soft Start" feature with the following advan-
tages and protections:
62 | SAMLEX AMErICA INC.
general Description & Principles of Operations