Bidirectional DC-DC Converter for UPS Load Leveling
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Solution Overview
Problem
Conventional UPS systems for medical imaging are oversized and expensive due to being designed for peak power ratings, which exceed the average power requirements, and often require infrastructure that exceeds the power rating needed for continuous operation, leading to inefficiencies and higher costs.
Innovation Solution
A series-parallel line-interactive UPS topology with a bidirectional DC-DC converter and a battery energy storage system, coupled with an AC-DC converter, regulates power delivery to match the pulsed load profiles of medical imaging systems, allowing operation with AC power rated lower than peak power, and includes a control system to manage power from both AC and DC sources efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UPS systems are designed to meet peak power demand of medical imaging systems, then power reliability is improved, but system size and cost increase
Solution Approach 1:
The patent implements dynamic power delivery by using a bidirectional DC-DC converter that can rapidly switch between charging and discharging modes. The converter dynamically adjusts power flow based on real-time load conditions, allowing the UPS to provide peak power only when needed while maintaining a smaller battery capacity than traditional static designs would require.
Solution Approach 2:
The system utilizes periodic charging during low-load intervals and discharging during high-load periods. The bidirectional converter enables the battery to charge from the AC-DC converter when power demand is low, and discharge to supplement power during peak demand periods, creating a periodic charge-discharge cycle that reduces overall system size.
2Reliability
If conventional UPS systems are designed to meet peak power demand, then power reliability is improved, but system cost increases
Solution Approach 1:
The patent changes the operating parameters of the power conversion system by using a bidirectional DC-DC converter that operates in both charging and discharging modes. This parameter change allows the same hardware to serve dual functions, eliminating the need for oversized components and reducing overall system cost while maintaining peak power reliability.
Solution Approach 2:
The bidirectional DC-DC converter serves multiple functions: it acts as a rectifier during charging phases, a power supply during discharging phases, and a regulation device for the DC bus. This multi-functionality reduces the total component count and system complexity, leading to lower manufacturing costs.
3Reliability
If AC power infrastructure is designed to provide peak power, then power availability is improved, but infrastructure cost and complexity increase
Solution Approach 1:
The bidirectional DC-DC converter acts as an intermediary between the AC power infrastructure and the medical imaging load. It mediates power flow by charging from the AC-DC converter during low-demand periods and discharging during peak periods, allowing the AC infrastructure to be sized for average rather than peak demand.
Solution Approach 2:
The system performs preliminary charging of the battery during low-load periods before peak demand occurs. The bidirectional converter proactively stores energy in advance, so when peak power is needed, the battery can immediately supplement the AC supply without requiring the AC infrastructure to be oversized.
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 solution reduces the size and cost of UPS systems by optimizing power delivery to match average power needs, improving efficiency, and providing regulated output voltage while minimizing transients and synchronization delays, thus enabling reliable operation with lower-rated power infrastructure.
Implementation Method 1
a bidirectional direct current (DC)-DC converter configured to transform power from the AC-DC converter to charge the battery energy storage system and to transform power from the battery energy storage system to discharge power to provide additional power to the medical imaging load
Data Source
AI summary
A system includes an AC-DC converter configured to convert power from an AC supply to a DC bus to provide a first portion of power a medical imaging load. The system includes an uninterruptible power supply (UPS) coupled to the DC bus. The UPS comprises at least one battery cell and a DC-DC converter comprising one or more switches and coupled between the at least one battery cell and the DC bus. The system includes a control system comprising a processor configured to send one or more signals to control operation of the one or more switches to cause the DC-DC converter to control power discharged from the at least one battery cell to the DC bus to provide a second portion of power to the medical imaging load.