Chapter 1 Overview; Features; Design Concept; System Design - Liebert NXC 30kVA User Manual

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Table Of Contents

Table of Contents

This chapter briefly introduces the features, design concept, parallel system, operation mode, battery management

and battery protection of the Liebert NXC 30kVA and 40kVA UPS (UPS for short).

1.1 Features

The UPS is connected between a critical load (e.g. a computer) and mains power to provide high quality power for the

loads. The UPS has the following advantages:

Increase power quality

The UPS protects its output against the input power change through the internal voltage and frequency controller.

Improve noise rejection

Due to the application of AC-DC-AC conversion mode, the noise in the input power is effectively filtered, and the load

gets clean power supply.

Provide mains failure protection

If the input power fails, the UPS will work in battery mode, and the power supply to the loads will not be interrupted.

1.2 Design Concept

1.2.1 System Design

This section introduces the working principle of the single UPS module. The UPS adopts AC-DC-AC converter (as

shown in Figure 1-1). The first stage conversion (AC-DC) adopts three-phase high frequency rectifier to convert the

three-phase input voltage into stable DC bus voltage.

Input

Bypass input

Mains input

Rectifier input switch

The UPS has its own battery charger and adopts advanced temperature compensation technology to effectively

prolong the battery service life. The inverter mainly adopts large power IGBT, and adopts advanced SVPWM

technology for control, to invert the DC bus voltage back to AC voltage.

When the mains is normal, the rectifier and inverter work together to supply the loads and charge the battery.