UPS PFC Front-End Circuit Reuse for Battery Boost Conversion
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Solution Overview
Problem
Conventional uninterruptible power supplies (UPS) face inefficiencies in converting battery voltage to appropriate levels for the inverter stage during backup mode, particularly in high-power systems where the high voltage battery requires non-isolated boost converters, leading to suboptimal efficiency.
Innovation Solution
A more efficient Power Factor Correction (PFC) converter front-end circuit is reused as a boost converter during on-battery mode to convert DC power from the battery to regulated DC power for the inverter, utilizing a controller to manage switches and capacitors to generate positive and negative DC voltages on the DC buses, synchronizing with AC power waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a non-isolated boost converter is used to convert battery voltage to appropriate levels during backup mode in high-power UPS systems, then the voltage conversion function is achieved, but the conversion efficiency deteriorates
Solution Approach 1:
The PFC converter front-end circuit is designed to perform dual functions: during online mode it operates as a Power Factor Correction converter, and during backup mode it operates as a boost converter to convert battery voltage to appropriate levels for the inverter stage. This eliminates the need for a separate boost converter, reducing overall system complexity while improving efficiency.
Solution Approach 2:
The patent merges the PFC converter and boost converter functions into a single integrated circuit. The same converter hardware is controlled to perform voltage conversion during backup mode while maintaining power factor correction during online mode, thereby eliminating redundant components and reducing energy losses associated with multiple conversion stages.
2Loss of energy
If the PFC converter front end is reused as a boost converter during on-battery mode, then conversion efficiency is improved, but the control complexity increases
Solution Approach 1:
The controller dynamically reconfigures the PFC converter circuit topology based on the operating mode. During online mode, the converter operates in standard PFC mode; during backup mode, the controller switches the circuit to boost converter mode by adjusting switch configurations and control parameters, enabling efficient battery voltage conversion without requiring separate hardware.
Solution Approach 2:
The controller changes operational parameters (switching frequencies, duty cycles, and circuit connectivity) to transform the PFC converter into a functional boost converter. By modifying control parameters rather than hardware architecture, the system achieves efficient voltage conversion during backup mode while maintaining a relatively simple overall structure.
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
This approach enhances efficiency and reliability by effectively converting battery voltage to suitable levels for the inverter, ensuring uninterrupted power delivery with reduced losses and improved performance in both online and backup modes.
Implementation Method 1
a PFC stage configured to convert the input AC power into regulated DC power provided to the positive DC bus and the negative DC bus
Implementation Method 2
utilizing a controller to manage switches and capacitors to generate positive and negative DC voltages on the DC buses
Data Source
AI summary
A UPS comprising an input, an output, a battery circuit, a PFC stage, a switch configured to selectively couple an interface of the PFC stage to the input in an online mode and to the battery circuit in a backup mode, a positive DC bus, a negative DC bus, and a controller configured to operate, in the online mode, the PFC stage to provide DC power, derived from the input AC power, to the DC busses, to operate, in the backup mode, the PFC stage to provide DC power, derived from the backup DC power, to the DC busses, to operate, in a first stage of the backup mode, the battery circuit to couple a positive terminal of a DC source to the interface, and to operate, in a second stage of the backup mode, the battery circuit to couple a negative terminal of the DC source to the interface.