The use of cloud computing in today's world is increasing, and it is normal to connect to the Internet at any time. People walk around with their smartphones, which are always connected to the Internet. Enjoying the entire season of shows through streaming services has become the preferred method of watching TV shows. Cloud has so many uses, it is impossible for me to list them all here. One thing is for sure. All these devices that use the Internet and the cloud require very large storage space and infrastructure. This is the job of the data center. The data center is the core of the Internet. To ensure that this information is available 100% of the time, the data center is designed for maximum reliability.

Uninterruptible power supply (UPS) is one of the equipment used in every data center to ensure that servers and all sensitive computing equipment are not affected by power line interference and power quality issues.

DC power supply in data center system

Computing devices such as servers and routers rely on internal power sources to provide the regulated DC power required to run processors and peripherals. These power supplies can only handle certain changes in power supply voltage before the computing device is prone to shut down or overload. The Information Technology Industry Council (ITI) has created a curve and application note describing the range of input voltages that typical information technology equipment can tolerate. It is called the ITI (CBEMA) curve.

The application note defines seven power quality events described by the ITI curve. For example, the curve shows that most devices can withstand voltage drops of up to 20 ms. The UPS is designed to ensure that the input voltage of the computing device is within the "non-interrupted functional area" range of the voltage range.

Uninterruptible power supply components

There are several types of uninterruptible power supplies, which will be defined below, but all UPS systems will use the following components.

Rectifier: The rectifier converts the input AC power into DC power. This direct current will be used to power the energy storage system.

Energy storage: Every UPS uses some kind of system to store energy in case of input power failure. This energy can be stored in the form of batteries, flywheels or super capacitors, which is why UPS provides uninterrupted power.

Inverter: The inverter converts the direct current from the rectifier or energy storage system into the required alternating current used by the load.

Type of uninterruptible power supply

Standby/Offline: Standby UPS has two modes. During normal operation, the input power is directly fed to the output load without filtering. When a power failure is detected, a solid-state switch is used to transfer the load to battery power.

Line interaction: similar to the backup UPS, but can adjust the output according to overvoltage and undervoltage conditions without switching to the battery. When a power failure is detected, a solid-state switch is used to transfer the load to battery power.

Online/Double Conversion: Online UPS uses double conversion power electronic equipment. In this topology, the battery system is always connected and does not need to switch to a backup power source. The power flow in normal operation is charged through the rectifier, energy storage system and through the inverter.

Online double conversion UPS system

Critical data centers usually use online double conversion UPS systems. We already know that online UPS will be equipped with rectifiers, energy storage systems and inverters. In order to further improve the reliability of the system, an internal automatic static transfer switch will be included to realize the conversion to the bypass power supply. If a problem or malfunction is detected in the UPS, it will automatically transfer.

UPS systems in critical data centers also use external maintenance bypasses. This is a switching device that allows manual transfer of critical loads from the UPS to the bypass source. Manual transfer to the external bypass power supply allows the power supply to be completely cut off for safe maintenance work inside the UPS.

UPS redundancy requires high uptime

In order to meet the high uptime requirements of data centers, UPS systems usually adopt redundant configurations.

N + 1 redundancy

Let us define "N" as the total UPS capacity required to handle the total load. For simple redundancy, additional modules are installed. In this multi-module system, each UPS can provide the required "N" power. This is called N + 1 redundancy.

N redundancy

Enterprise-level IT equipment usually supports dual power supply operation. The device can be connected to multiple power sources. In the data center, these two sources will be independent UPS systems. "A side" and "B side" can supply power to computer equipment. Each party can handle 100% of the load capacity. This is called 2N redundancy.

2 (N + 1) redundancy

These two concepts can also be combined. Take the 2N redundant power distribution system as an example, instead of one module UPS on each side, but multiple modules. This provides N+1 redundancy on each side. This is called 2 (N + 1) redundancy.

Transformerless multi-stage UPS topology

Today, the most advanced UPS systems deployed in data centers use a transformerless multi-level topology. This topology ensures the highest reliability and efficiency. Manufacturers are also beginning to use wide band gap transistors, such as silicon carbide (SiC). This increases the efficiency of the UPS system by 98% in double conversion mode.

to sum up

With the increasing use of the Internet, more and more data centers are under construction. The UPS system is the core to ensure that every computer in the data center is always running. Next time when you play your favorite show, please remember that all information is provided continuously through UPS.

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