With societal development, electricity supply in power generation has evolved from simply supplying electricity to energy storage. A solar energy storage system is a system capable of both storing and supplying electrical energy. It greatly simplifies electricity management for users and allows for more efficient use of electrical equipment, thereby reducing electricity supply costs. Within a solar energy storage system, there is an even more crucial component—the energy storage inverter, which serves as a bridge between the solar energy storage system and the electrical equipment.
Energy storage systems are an important component of the power generation process, and energy storage inverters play a crucial role in these systems, effectively utilizing electrical equipment and reducing power supply costs. We typically categorize energy storage inverters into three types: grid-connected energy storage inverters, off-grid energy storage inverters, and multi-series series energy storage inverters.
The role of energy storage inverters
An energy storage inverter converts AC mains power into DC power to charge and store electricity in a battery (storage battery). When the mains power is cut off, the electricity stored in the battery is converted into the household or industrial three-phase power we need.
Grid-connected energy storage inverter
Grid-connected energy storage inverters, also known as grid-connected energy storage inverters, not only convert direct current (DC) to alternating current (AC), but also synchronize the output AC power with the frequency and phase of the mains power, allowing the output AC power to be returned to the mains. Grid-connected inverters are typically used in applications where DC voltage sources (such as solar panels or small wind turbines) are connected to the power grid.
Off-grid energy storage inverter
The off-grid inverter employs a complete system solution with modular components. It consists of several easy-to-manage modules: the XW inverter, charger, solar charge controller, generator automatic start module, and system control panel.
Multiple series-connected energy storage inverter
The application of multi-series inverters in electric vehicles offers numerous advantages. The series structure significantly increases the number of output voltage vector types, improving control flexibility and accuracy; simultaneously, it reduces fluctuations in the motor neutral point voltage. The inverter's bypass characteristics enhance the flexibility of charging and regenerative braking control.
Inverter Classification
(1) According to the nature of the source and flow
Based on the nature of the current source, inverters can be divided into active inverters and passive inverters.
An active inverter is an inverter that connects the current in a current circuit to the power grid on the AC side instead of directly connecting it to the load.
Passive inverter: An inverter that allows the current in a current circuit to be directly connected to the load on the AC side without being connected to the power grid (i.e., converting DC power into AC power of a certain frequency or adjustable frequency to supply the load).
The difference between an active inverter and a passive inverter is that the output side of a passive inverter is connected to the load, while the output side of an active inverter is connected to the power grid.
(2) By grid connection type
Based on the grid connection type, inverters can be divided into off-grid inverters and grid-connected inverters.
Off-grid inverters: As the core equipment for power conversion in off-grid power generation systems, off-grid inverters are responsible for converting DC power supplied by the DC bus into high-quality AC power for AC loads. They primarily focus on the waveform quality of the output voltage.
Grid-connected inverters: The output filters of grid-connected inverters generally adopt four structures: single-L filter, LC filter, LCL filter and LLCL. Among them, LCL filters have received increasing attention from researchers and widespread importance due to their unique advantages such as good harmonic suppression capability, low inductance and small size when used in grid-connected inverters.
(3) By topology
Based on their topology, inverters can be divided into two-level inverters and multi-level inverters.
Two-level inverter: A two-level inverter has two output levels, with the output voltage alternating between positive and negative at a basic frequency.
Multilevel inverter: A multilevel inverter converts a DC signal into a multilevel stepped waveform. The output waveform of a multilevel inverter does not directly alternate between positive and negative, but rather alternates between multiple levels.
