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CN-224232171-U - A backward active noise reduction circuit for gradient coil

CN224232171UCN 224232171 UCN224232171 UCN 224232171UCN-224232171-U

Abstract

The utility model relates to a backward active noise reduction circuit for a gradient coil, belonging to the technical field of MRI equipment and solving the problems of reducing electromagnetic noise in the current of the gradient coil and improving imaging quality, wherein one end of the gradient coil is connected with one end of a secondary side of a current transformer Tc1, the other end of the secondary side of the current transformer Tc1 is connected with an output end of an amplifier PA1, and the other end of the gradient coil is connected with a grounding end of the amplifier PA 1. And further, the imaging resolution and the system reliability are improved, the imaging device is suitable for mobile and portable MRI systems, and has the advantages of small volume and low cost.

Inventors

  • WANG ZHUO

Assignees

  • 中国科学技术大学

Dates

Publication Date
20260512
Application Date
20250529

Claims (3)

  1. 1. The backward active noise reduction circuit for the gradient coil is characterized by comprising a backward active noise reduction unit and the gradient coil, wherein the input end of the backward active noise reduction unit receives an input signal, and the output end of the backward active noise reduction unit is connected with the gradient coil; The backward active noise reduction unit comprises an amplifier PA1, an amplifier PA2, a current transformer Tc1, a current transformer Tc2, a resistor R1 and a subtracter, wherein one end of the gradient coil is connected with one end of the secondary side of the current transformer Tc1, the other end of the secondary side of the current transformer Tc1 is connected with the output end of the amplifier PA1, and the other end of the gradient coil is connected with the grounding end of the amplifier PA 1; The two ends of the primary side of the current transformer Tc1 are connected in parallel with a resistor R1, one end of the resistor R1 is connected with a reference ground, the other end of the resistor R1 is connected with the positive input end of a subtracter, the input end of the amplifier PA1 is connected with the negative input end of the subtracter, the output end of the subtracter is connected with the input end of the amplifier PA2, the output end of the amplifier PA2 is connected with one end of the primary side of the current transformer Tc2, the other end of the primary side of the current transformer Tc2 is connected with the reference ground, one end of the secondary side of the current transformer Tc2 is connected with the output end of the amplifier PA1, and the other end of the secondary side of the current transformer Tc2 is connected with the ground end of the amplifier PA 1.
  2. 2. A backward active noise reduction circuit for a gradient coil according to claim 1, wherein the amplifier PA2 comprises an error amplifier and a current power amplifier, the input of the error amplifier being connected to the output of the subtractor, the output of the error amplifier being connected to the input of the current power amplifier, the output of the current power amplifier being connected to one end of the primary side of the current transformer Tc 2.
  3. 3. A backward active noise reduction circuit for a gradient coil as defined in claim 1, wherein the amplifier PA1 is a gradient power amplifier.

Description

A backward active noise reduction circuit for gradient coil Technical Field The utility model belongs to the technical field of MRI equipment, and relates to a backward active noise reduction circuit for a gradient coil. Background Gradient systems play a critical role in MRI equipment, and are composed of a number of key components that work together, including gradient waveform generators, gradient controllers, gradient amplifiers, and gradient coils. Gradient Coil (Gradient Coil) is a core component of MRI spatial encoding, which is accomplished by generating magnetic field gradients. According to the electromagnetic induction principle, when a rapidly-changing current is introduced into a gradient coil arranged in a strong static magnetic field, the gradient coil is subjected to the action of Lorentz force, so that the coil structure is subjected to tiny mechanical deformation and high-speed vibration, the vibration is transmitted through a coil fixing device and an equipment structure, and finally the vibration is radiated in an acoustic wave form, so that main noise heard in the inspection process is formed. The utility model patent with the patent publication number of CN213758224U discloses a medical MRI noise reduction structure, which utilizes a first buffer layer to buffer vibration of a gradient coil, so that noise generated by the gradient coil during vibration is reduced, and the noise is reduced by utilizing the first noise reduction layer, so that the intensity of the noise transmitted from an inner shell layer is reduced, and the interference of the noise to a patient is reduced. The existing noise reduction method for the gradient system mainly reduces the mechanical vibration generated by equipment in a mode of arranging a sound insulation layer, a buffer layer or a sound absorption hole and the like, and electromagnetic noise contained in the driving current of a gradient coil in the gradient system is not considered in the noise reduction method, and the electromagnetic noise is coupled into a radio frequency coil through the gradient coil, so that the quality of an MRI image is degraded, and the imaging quality of the equipment is poor. Disclosure of utility model The technical scheme of the utility model is used for solving the problems of reducing electromagnetic noise in gradient coil current and improving imaging quality. The utility model solves the technical problems through the following technical scheme: The backward active noise reduction circuit for the gradient coil comprises a backward active noise reduction unit and the gradient coil, wherein the input end of the backward active noise reduction unit receives an input signal, and the output end of the backward active noise reduction unit is connected with the gradient coil; The backward active noise reduction unit comprises an amplifier PA1, an amplifier PA2, a current transformer Tc1, a current transformer Tc2, a resistor R1 and a subtracter, wherein one end of the gradient coil is connected with one end of the secondary side of the current transformer Tc1, the other end of the secondary side of the current transformer Tc1 is connected with the output end of the amplifier PA1, and the other end of the gradient coil is connected with the grounding end of the amplifier PA 1; The two ends of the primary side of the current transformer Tc1 are connected in parallel with a resistor R1, one end of the resistor R1 is connected with a reference ground, the other end of the resistor R1 is connected with the positive input end of a subtracter, the input end of the amplifier PA1 is connected with the negative input end of the subtracter, the output end of the subtracter is connected with the input end of the amplifier PA2, the output end of the amplifier PA2 is connected with one end of the primary side of the current transformer Tc2, the other end of the primary side of the current transformer Tc2 is connected with the reference ground, one end of the secondary side of the current transformer Tc2 is connected with the output end of the amplifier PA1, and the other end of the secondary side of the current transformer Tc2 is connected with the ground end of the amplifier PA 1. Further, the amplifier PA2 comprises an error amplifier and a current power amplifier, wherein the input end of the error amplifier is connected with the output end of the subtracter, the output end of the error amplifier is connected with the input end of the current power amplifier, and the output end of the current power amplifier is connected with one end of the primary side of the current transformer Tc 2. Further, the amplifier PA1 is a gradient power amplifier. The utility model has the advantages that: According to the utility model, the subtracter is used for eliminating the effective component in the driving current of the gradient coil, the current transformer is combined to be coupled to the output end of the gradient power amplifier, the noise compo