Browse Prior Art Database

WIDE RANGE ALTERNATING CURRENT INPUT VOLTAGE GRADIENT POWER SUPPLY

IP.com Disclosure Number: IPCOM000236619D
Publication Date: 2014-May-06
Document File: 6 page(s) / 142K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a technique for providing power supply with wide range AC input voltage for gradient driver. Such power supply includes two obvious characteristics. One of the characteristics is that the power supply is able to accept wide range AC input voltage, typically from 90Vac to 265Vac. Another characteristic is that it is easy to employ power factor correction (PFC) circuit into power supply to improve power quality and reduce power loss.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 37% of the total text.

WIDE RANGE ALTERNATING CURRENT INPUT VOLTAGE GRADIENT POWER SUPPLY

FIELD OF INVENTION

The invention generally relates to nuclear magnetic resonance imaging (NMRI) system and more particularly to a technique for providing power supply with wide range alternating current (AC) input voltage for gradient driver in the NMRI system.

BACKGROUND OF THE INVENTION

At present nuclear magnetic resonance imaging (NMRI) technology is applied broadly in medical field. NMRI is a diagnostic method that generates an image by atomic nucleus resonance in a magnetic field. Gradient driver subsystem is designed to produce a desired gradient field so that magnetic field is stronger in some location than others. Gradient driver subsystem includes power supply, amplifier and gradient coil.

There is no power factor correction (PFC) circuit in conventional gradient power supply. A conventional technique includes a three phase rectifier bridge which is directly used to convert AC input voltage to DC bus voltage with poor power factor. FIG. 1 is a conventional PFC circuit in which rectifiers D10, D11, D12, and D13 convert AC input voltage to DC voltage.

FIG. 1

Inductor L1, switch Q1, rectifier D1 and capacitor C1 includes in a boost circuit that raises voltage at point V1 to voltage at point V2. C1 has huge capacitance for a steady voltage at point V2.

FIG. 2 is a conventional full bridge circuit in which transistors Q2, Q3, Q4, Q5 with its own parallel rectifiers D2, D3, D4, D5 invert DC Bus voltage to AC symmetrical square waveform.

FIG. 2

Transformer T1 transfers energy from primary side to secondary side and plays an isolation role. There are four rectifiers D6, D7, D8, D9, that convert AC symmetrical square waveform to a DC output voltage on the secondary side.

However, the conventional technique is not able to accept wide AC input voltage. As a result, there is a power distribution unit (PDU) before gradient power supply for adapting to different state grid which increases cost of power supply.

Hence there exists a need for a technique to provide wide range AC input voltage for gradient driver in nuclear magnetic resonance imaging (NMRI) system.

BRIEF DESCRIPTION OF THE INVENTION

The invention proposes a technique for providing power supply with wide range AC input voltage for gradient driver. Such power supply includes two obvious characteristics. One of the characteristics is that the power supply is able to accept wide range AC input voltage, typically, from 90Vac to 265Vac. Another characteristic is that it is easy to employ power factor correction (PFC) circuit into power supply to improve power quality and reduce power loss.

DETAILED DESCRIPTION OF THE INVENTION

The invention proposes a technique for providing power supply with wide range AC input voltage for gradient driver. Such power supply includes two obvious characteristics. One of the characteristics is that the power supply is able to accept wide range AC input voltage, typically, from 90Vac to 265Vac...