The Power Conversion System (PCS) is the core energy conversion device in the energy storage system that connects the energy storage battery with the external power grid or load. It can be called the "energy center" of the entire system. Its core function is to achieve bidirectional conversion between direct current (DC) and alternating current (AC), and it also undertakes key tasks such as energy scheduling and safety control of the energy storage system.

At the energy conversion level, the core value of PCS lies in breaking down the energy barriers between energy storage batteries, the grid, and loads. Because energy storage batteries store direct current (DC), while the grid and most loads use alternating current (AC), PCS achieves seamless charging and discharging thanks to its bidirectional conversion capabilities. During charging, it rectifies the grid's AC power into DC, efficiently storing it in the energy storage battery. This can be used, for example, to utilize low-peak electricity at night or surplus power generated by photovoltaic or wind power. During discharge, it inverts the battery's DC power into AC, which can be used by loads during peak demand or fed back to the grid for peak load regulation or power sales. This bidirectional conversion capability is the foundation for the energy storage system to complete the "energy storage and release" closed loop.

The PCS doesn't simply perform energy conversion passively; instead, it proactively dispatches energy based on system strategies. It interacts with the battery management system (BMS) in real time, dynamically monitoring key battery parameters such as state of charge (SOC), temperature, and state of health (SOH). It adjusts the charge and discharge current and voltage accordingly to prevent overcharging and over-discharging, effectively protecting battery life. Furthermore, it works closely with the energy management system (EMS) to automatically switch charge and discharge modes based on electricity pricing policies (such as peak-valley arbitrage), grid dispatch instructions (such as peak and frequency regulation), and load demand (such as peak shaving and valley filling), maximizing the economic efficiency and functionality of the energy storage system.

The PCS plays a key role in grid adaptation and safety protection. During discharge, it ensures that the output AC power fully matches the voltage, frequency, and phase of the grid or load (e.g., meeting the 380V/50Hz standard) to avoid harmonic pollution or current surges, ensuring stable grid operation. Furthermore, the PCS has multiple built-in safety protection features, including overcurrent, overvoltage, overtemperature, short-circuit protection, and islanding protection (preventing reverse power flow to the line during a grid outage), effectively preventing equipment damage and safety accidents.

Furthermore, PCS performance indicators (such as conversion efficiency, response speed, and power level) directly determine the applicability of energy storage systems. In residential and commercial energy storage scenarios, it helps reduce electricity costs through peak-valley arbitrage and emergency backup. In renewable energy storage, it can absorb the volatility of photovoltaic and wind power, improving renewable energy utilization. In grid-side energy storage, it can participate in frequency and peak regulation, supporting grid stability. In microgrid systems, it serves as the core device for off-grid and grid-connected switching, ensuring power supply to remote areas or critical facilities.

In short, the power storage converter (PCS) is not only the "bridge" for the energy storage system to achieve bidirectional flow of AC and DC energy, but also the "hub" for ensuring the safe and efficient operation of the system. Its performance directly determines the economy, reliability and scope of application of the energy storage system, and is the core pillar equipment for the implementation of energy storage technology.