Isolated Low-Voltage UPS Architecture for Medium-Voltage Data Centers
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Solution Overview
Problem
Data centers face high power and medium voltage requirements, leading to increased electrical losses and power usage effectiveness (PUE), necessitating efficient uninterruptible power supplies (UPS) that can handle short and long interruptions in utility power.
Innovation Solution
A bi-directional high-frequency DC-DC converter with isolation, utilizing low-voltage energy storage devices, H-bridge circuits, and high-frequency transformers, controlled by a phase-shifted zero voltage switching (ZVS) controller to charge or discharge energy storage devices, enabling efficient power transfer and reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If medium voltage operation is used to reduce electrical losses and power usage effectiveness, then electrical losses and PUE are reduced, but high power and high/medium voltage requirements necessitate complex uninterruptible power supplies
Solution Approach 1:
The system segments the power conversion function into multiple isolated DC-DC converter circuits, each handling a portion of the power conversion task. This segmentation allows the system to manage high voltage requirements through modular units rather than a single complex converter, reducing overall system complexity while maintaining medium voltage operation for reduced electrical losses
Solution Approach 2:
Isolated DC-DC converter circuits serve as intermediary devices between the low-voltage energy storage and the medium-voltage data center load. These converters act as mediators that safely step up voltage while providing isolation, enabling the system to operate at medium voltage for reduced losses without directly exposing the energy storage devices to high voltage conditions
2Object-affected harmful factors
If isolated DC-DC converter circuits are used with low-voltage energy storage, then safety and electromagnetic interference are reduced, but multiple components (H-bridge circuits, transformers) increase device complexity
Solution Approach 1:
The patent merges multiple functional components (H-bridge circuits, high-frequency transformers, and control logic) into integrated isolated DC-DC converter circuits. This consolidation achieves electromagnetic isolation and reduced interference while managing the complexity through unified modular designs rather than separate discrete components
Solution Approach 2:
The system changes the operating parameters by using high-frequency transformation within the DC-DC converters. This parameter change enables efficient voltage conversion with reduced electromagnetic interference compared to traditional low-frequency systems, while the modular nature manages the inherent complexity
3Loss of energy
If high frequency transformers are used in DC-DC converters, then switching losses are reduced through zero voltage switching, but precise phase shift control is required
Solution Approach 1:
The system implements feedback control mechanisms in the DC-DC converter circuits to precisely manage phase shift between primary and secondary H-bridge circuits. This feedback enables zero voltage switching operation that minimizes switching losses while automatically adjusting to maintain the required phase relationship, reducing the difficulty of precise control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a compact, efficient, and reliable power supply system that reduces electrical losses, enhances power usage effectiveness, and ensures uninterrupted power to data centers by effectively managing energy storage and transfer.
Implementation Method 1
a high frequency transformer, and a second H-bridge circuit. A primary side of the high frequency transformer is coupled to the first H-bridge circuit and a secondary side of the high frequency transformer is coupled to the second H-bridge circuit
Implementation Method 2
Each DC-DC converter circuit includes a low voltage energy storage device, a first H-bridge circuit coupled to the low voltage energy storage device
Implementation Method 3
a controller coupled to the first switching device drivers and the second switching device drivers, the controller configured to control the first switching device drivers and the second switching device drivers to charge or discharge the low voltage energy storage device, by controlling a phase shift between a first drive signal output from the first switching device drivers and a second drive signal output from the second switching device drivers
Data Source
AI summary
Systems and methods of this disclosure use low voltage energy storage devices to supply power at a medium voltage from an uninterruptible power supply (UPS) to a data center load. The UPS includes a low voltage energy storage device (ultracapacitor/battery), a high frequency (HF) bidirectional DC-DC converter, and a multi-level (ML) inverter. The HF DC-DC converter uses a plurality of HF planar transformers, multiple H-bridge circuits, and gate drivers for driving IGBT devices to generate a medium DC voltage from the ultracapacitor/battery energy storage. The gate drivers are controlled by a zero voltage switching (ZVS) controller, which introduces a phase shift between the voltage on the primary and secondary sides of the transformers. When the primary side leads the secondary side, the ultracapacitor/battery discharges and causes the UPS to supply power to the data center, and when the secondary side leads the primary side, power flows from the grid back to the UPS, thereby recharging the ultracapacitor/battery.