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ケーススタディ: Portable X-ray system

Bidirectional converter shrinks battery array to one cell

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お客様の課題

New solid-state X-ray technology allows medical X-ray scanners to be more portable and battery operated, enabling medical professionals to check patients in any location. Medical X-rays typically need a short pulse of high-intensity radiation energy, which can conveniently be stored and supplied to the X-ray diode by a supercapacitor, in this case charged to 28V. Normally the 28V would be sourced from a number of Li-ion batteries in series. However, in a portable application, this type of battery array and charging system is too large and too heavy. The key goals were:

Find an alternative to heavy and bulky multiple-cell battery solutions
Fast charging of the supercapacitor requires a high current pulse
Long battery life to minimize the need for recharging

Vicorソリューション

Use of a bi-directional DC-DC converter reduced the battery array to just one 2.7V Li-ion cell, reducing size and weight significantly compared to a typical boost converter solution. In addition, the bi-directional converter delivered higher efficiencies when charging the supercapacitor from a low voltage source, extending battery life.

主な利点

Ultra-small, lightweight solution (8.6cm2 footprint, 16g weight) compared to a boost converter solution

Unique bi-directional converters (DC-DC transformer) available as standard products

Higher efficiency achieved using low-loss Sine Amplitude Conversion topology

Bi-directional VTM, operating in reverse mode, enabled highly-efficient x12 transformation

A Vicor VTM, operating in reverse, stepped-up the 2.7V input to provide a nominal 32V rail with an efficiency of more than 94%. For the supercapacitor charging circuit, a ZVS Buck-Boost converter regulated the 32V and provided the necessary current limiting. This architecture was accomplished in a footprint of just 8.6cm². To analyze this power chain, go to Vicor Whiteboard online tool.

Learn more about the modular approach power.