what is the difference of single phase and three phase of on grid inverter

In general, we call the process of converting DC power into AC power as inverter, the circuit that completes the inverter function is called inverter circuit, and the device that realizes the inverter process is called inverter equipment or inverter.

Why are common grid-connected inverters only single-phase and three-phase? In fact, the main reason is the type of grid connected to the inverter.

First of all, let's understand, what is "phase"? "Phase" refers to the three-phase live wire (A/B/C or L1/L2/L3). The transformer generally outputs three live wires and one neutral wire (N wire), and some also lead to a ground wire ( PE).

So what are single-phase, two-phase, three-phase? What is the voltage of each type of electricity used daily?

Single phase

It consists of a live wire and a neutral wire. "Single" refers to any one of the three phases. The standard voltage between A-N, B-N, and C-N is 220V(some countries apply 120V)

two-phase
Also known as two-phase, it is composed of any two-phase live wires (A-B, B-C, A-C) in the three-phase, and the voltage is 380V. It isnot often seen in daily life. For example, electric welding machine is an electrical appliance that uses two live wires of 380V.

three phase
It is three live wires, which are represented by ABC. If only three-phase voltage is 380V, it is also called three-phase triangle; if there is a neutral wire in addition to the three live wires, the voltage will also have 220V and 380V, which is three-phase star. shape connection.

The phase angles between the three phases A, B, and C are 120 degrees to each other, which is symmetrical in electrical space. 380V is the line voltage, 220V is the phase voltage, the calculation formula between the two is as follows, and there will be 400V/230V in the inverter representation, which is also the same calculation method.

U(LINE)=U(PHASE)*√3

When installing a three-phase inverter, you often hear three-phase four-wire and three-phase five-wire. After talking about "phase", let's talk about "line". The common types are as follows:
_
Single-phase two-wire:
One live wire + one neutral wire.
_
Single-phase three-wire:
A live wire + a neutral wire + a ground wire.
_
Three-phase three-wire (TT system):
Three live wires, most of which are above 10KV.
_
Three-phase four-wire (TN-C system):
Three live lines + one neutral line, mainly 380V/220V low-voltage lines, the working neutral line N is also used as the zero protection line PE, which can be called the protective neutral line, which is represented by NPE, and is suitable for power consumption with basically balanced three-phase loads.
_
Three-phase five-wire (TN-S system):
Three live wires + one neutral wire + one ground wire, a power supply system that strictly separates the working neutral wire N and the special protection wire PE, and is used in places with high safety requirements and electrical equipment requiring grounding.

In general, single-phase grid-connected inverters are integrated into single-phase two-wire and single-phase three-wire grid lines.

The three-phase grid-connected inverter incorporates three-phase four-wire and three-phase five-wire grid lines.

There is also a medium and high voltage grid-connected three-phase inverter, such as 480V/800V grid-connected, it is necessary to add a corresponding step-up transformer to connect to the three-phase three-wire grid (above 10KV).