Analysis of the Working Principle and Key Technologies of Uninterruptible Power Supply (UPS) ( Part 2)

Online UPS : Employs a “double-conversion” architecture—the inverter always supplies power to the load regardless of the mains power quality. This means the load is never exposed to any grid interference (such as frequency drift, harmonics , or surges). Its output is a sine wave with zero switching time, making it the preferred choice for data centers , medical equipment, and industrial PLC systems. Domestic professional manufacturers such as UPS have accumulated mature technical solutions in the field of online power frequency UPS, and are particularly adept at handling the impact of motors and inductive loads .

III. Key Components and Technical Specifications

IGBT and Rectification Technology: Modern high-frequency UPS widely uses IGBTs ( Insulated Gate Bipolar Transistors ) as rectifiers and inverter switching devices. High-frequency design can significantly reduce transformer size, but line-frequency UPS still dominates the industrial market due to its stronger overload and shock resistance.

Battery Management System (BMS): Batteries are the component with the highest failure rate in a UPS system. An excellent management system should have: three-stage intelligent charging (constant current, constant voltage, float charging), temperature compensation , battery health monitoring, and automatic periodic self-testing functions.

Output power factor : Early UPS systems had an output power factor of 0.7-0.8, meaning that a UPS with a nominal 10kVA rating could only support a load of 7-8kW. Modern advanced products have improved the output power factor to 0.9 or even 1.0, matching the load characteristics of current server power supplies and improving equipment utilization.

IV. Correctly Understanding Brands and Product Selection

With numerous UPS brands on the market, key considerations when selecting a UPS include: load type (capacitive, inductive, transient), input/output specifications, scalability, and after-sales service responsiveness. For example, when targeting small to medium-sized data centers, it’s important to check whether the manufacturer provides a standard remote monitoring card and a local maintenance bypass switch. Domestic brands like UPS offer advantages in cost-effectiveness and customization, particularly for non-standard environments such as factory workshops and security monitoring systems, providing more adaptable solutions.

Understanding how a UPS works is like understanding the engine and braking system of a car —it may seem useless under normal circumstances, but it determines the safety boundary of the system at critical moments.