What is the difference between a UPS and an inverter?
UPS Uninterruptible Power Supply System
I. Definition and Function
UPS Uninterruptible Power Supply, full name Uninterruptible Power Supply, is a power protection device that contains energy storage device and uses inverter as main unit to stabilize voltage and frequency output. It can provide stable and uninterrupted power supply to equipment when the mains power is abnormal or interrupted, and protect the equipment from power failure.
II. Working Principle
The working principle of UPS mainly includes four links: rectification, energy storage, conversion and switch control. When the mains power is normal, AC power is converted into DC power by rectifier and stored in the battery. At the same time, DC power is supplied to the inverter, which converts it into stable AC power and outputs it to the load. When the mains power is abnormal or power outage, the static switch quickly switches to battery power supply to ensure the voltage stability at the load end.
III. Components
The UPS system is mainly composed of battery pack, rectifier and inverter, static switch and other parts. The battery pack is used to store electrical energy; the rectifier converts AC power into DC power; the inverter converts DC power into AC power output; the static switch realizes fast switching when the mains power is abnormal.
IV. Classification
Based on the power supply mode (working mode) of the load, UPS is divided into three types: online backup type and online interactive type. For online UPS, the inverter is always in working state regardless of whether the mains power is normal, and the output is stable. It is suitable for places with high requirements for power quality. The backup UPS directly supplies power to the load when the mains power is normal, and the inverter supplies power when the mains power is abnormal. It is suitable for places with low requirements for power supply. The online interactive UPS combines the advantages of high efficiency of the backup type and high power quality of the online type.
V. Application Scenarios
UPS is widely used in computer security, transportation, aerospace, medical, industrial control and other fields. For example, in data centers and server rooms, UPS can ensure the normal operation of servers and storage devices and protect data integrity; in medical facilities, UPS can ensure the power supply of key areas such as operating rooms and intensive care units to ensure patient safety.
VI. Advantages And Disadvantages
Advantages include protecting equipment, providing backup power, and optimizing power quality. However, UPS also has disadvantages such as high cost, large footprint, and the need for regular inspection and maintenance. Therefore, when selecting and using UPS, it is necessary to comprehensively consider actual needs and maintenance costs.
Inverter System
I.Concept Of Inverter
Generally, the process of converting AC power into DC power is called rectification, the circuit that completes the rectification function is called a rectification circuit, and the device that realizes the rectification process is called a rectification device or a rectifier. Correspondingly, the process of converting DC power into AC power is called inversion, the circuit that completes the inversion function is called an inverter circuit, and the device that realizes the inversion process is called an inverter device or an inverter. Modern inverter technology is a science and technology that studies the theory and application of inverter circuits. It is a practical technology based on industrial electronic technology, semiconductor device technology, modern control technology, modern power electronics technology, semiconductor conversion technology, pulse width modulation (PWM) technology and other disciplines. It mainly includes three parts: semiconductor power integrated devices and their applications, inverter circuits and inverter control technology.
II. Working principle and structure of inverter
The inverter is mainly composed of DC input, power conversion part, filter and output part. The working principle is roughly as follows: DC is inverted through the power conversion part (usually a circuit composed of multiple power switching devices such as IGBTS) to generate high-frequency AC, which is then filtered out by the filter to remove high-frequency harmonics and finally output smooth AC.
III.Classification And Application Scenarios Of Photovoltaic Inverters
Photovoltaic inverters can be divided into centralized inverters, string inverters, and other inverters (distributed inverters and micro inverters) according to their power. The main difference between the three is that the single capacity of the inverter is different and the application field is different. The string inverter is mainly used in household distributed photovoltaics and small and medium-sized industrial and commercial rooftop photovoltaics.
Centralized Photovoltaic Inverters: It has the advantages of large output power, mature technology, high power quality, and low cost, but its maximum power tracking voltage range is relatively narrow, the component configuration flexibility is low, and the power generation time is short. It is mainly used in large centralized photovoltaic power stations.
String Photovoltaic Inverter: The inverter method is to track the maximum power point of a single string or several strings of photovoltaic components separately, and then connect them to the AC power grid after inversion. A string inverter can have multiple maximum power peak tracking modules, and the single machine capacity is generally below 200kW. The maximum power tracking voltage range of the string photovoltaic inverter is wide, the component configuration is flexible, and the power generation time is long. Moreover, it has high power density and simple installation and maintenance. It can meet the requirements of different application environments such as indoor and outdoor, and is widely used in smaller power stations, such as household distributed power generation, small and medium-sized industrial and commercial rooftop power stations, etc.
Distributed Inverter: It combines the centralized inverter advantages of large centralized photovoltaic inverters and the decentralized MPPT tracking advantages of string photovoltaic inverters: it achieves low cost and high reliability of centralized inverters and high power generation of string inverters
Micro Inverter: The inverter mode is that each micro inverter generally corresponds to only one or several photovoltaic modules, and each photovoltaic module can be tracked separately. The maximum power point is then connected to the AC power grid after inversion. The single capacity of the micro inverter is generally below 5kW. It is widely used in household photovoltaic power generation systems such as residential roofs and courtyards.