Datacenter migration, power supply system planning and design

Datacenter migration, with the progress of power semiconductor devices and power electronics technology, UPS equipment has experienced the evolution process from multiple output transformer to single output power frequency transformer, and the appearance of better performance high-power IGBT devices and more advanced control technology will fundamentally remove the output isolation for UPS devices. The transformer has created material conditions and made great progress in the fields of high frequency, miniaturization, energy saving and green environmental protection. This is what people call "high frequency machine". This type of machine embodies the progress of UPS circuit technology and represents the development direction of UPS technology. Compared with the traditional UPS with output transformer, it has made obvious improvement and progress in reducing the volume, reducing the weight, improving the performance, improving the efficiency, reducing the cost and so on. It has become the first choice of the modern data center UPS equipment.

1, remove the output transformer is the progress of UPS circuit technology.
One of the characteristics of the traditional double conversion UPS circuit is the output of the power frequency isolation transformer. It should be said that the output transformer is determined by the output circuit of the UPS inverter, and the existence of the transformer is more harm than good. A notable manifestation of the evolution of inverter circuit technology is whether it is necessary to use transformers, how to configure transformers, and whether or not to remove transformers.
The progress of UPS circuit technology depends on the progress of the power semiconductor devices. The emergence of power semiconductor devices such as the thyristor to the bipolar power transistor and the IGBT of the integrated controller is accompanied by the evolution of the UPS output circuit from four transformers to a transformer, as shown in Figure 5.1. Since 1880s, the UPS inverter has only one transformer at the beginning.
UPS reverse power
2, the function of the UPS output isolating transformer
It is very important to understand the function of the traditional UPS output isolating transformer, because it is possible to replace and cancel it in a new generation of devices only when the circuit measures can fully realize its function. It should be said that the transformer is an integral part of the full bridge inverter of the power frequency machine, and its function is very simple: the boost and the production of the zero line of the three-phase four line output.
One of the functions of the output transformer is to provide the required zero line for the single-phase load.
An important function of the traditional double conversion UPS output transformer is the neutral line (or zero line) needed to supply the single-phase load to the UPS output terminal.
The DC/AC inverter with output transformer UPS is usually made up of full bridge circuit. The transformer must be added to the output, otherwise it will not be able to output the single-phase or three-phase four wire AC voltage. So this transformer should be regarded as a transformer that produces zero output line.
UPS output
Taking the single phase UPS output DC/AC inverter as an example, it is a full bridge inverter circuit with two series IGBT (VT1-VT4) in series, and the output alternating voltage UAB is derived from the middle point A and B of the two bridge arms.
When VT1 and VT4 are simultaneously guided (VT2 and VT3 cut-off), the current loop formed by the DC voltage E is the negative end of the -VT1- load A end of the voltage E, and the negative end of the -VT4- voltage E on the load -B terminal. The negative end of E is pressed. If the cycle of VT1 and VT4 alternating with VT2 and VT3 is 50Hz, the voltage UAB added to the load is a 50Hz square wave or a quasi square wave with a amplitude of E of the DC voltage E. If VT1 and VT4 and VT2 and VT3 are all on and off with high frequency sine pulse width modulation, the voltage of the load end is an adjustable sine wave of amplitude.