Gradient amplifier applying coupled inductors to output filter

Abstract

The invention provides a gradient amplifier applying coupled inductors to output filter, so as to meet requirements of an imaging system with low output ripple current and quick output response. The gradient amplifier by applying the coupled inductors to output filter is composed of a PWM control part, a power conversion part and a low pass filter part. According to the gradient amplifier of the invention, design of the coupled inductors is optimized, different control logics of the PWM control signals drive power conversion and output, a low pass filter capacitor part is combined, and requirements of the imaging system with low output ripple current and quick gradient current output response can be met. According to the gradient amplifier of the invention, the coupled inductors are applied to output filter, design of the high-voltage large-current amplifier can be simplified and optimized, effectiveness and performance of the gradient system are enhanced, the hardware cost is reduced, and the cost performance of the gradient system is greatly improved.

Description

technical field [0001] The invention relates to the field of gradient amplifiers, in particular to a gradient amplifier using coupled inductance output filtering, which is used to generate and control pulse currents in gradient coils in a magnetic resonance imaging system. Background technique [0002] The gradient system refers to all circuit units related to the gradient magnetic field. Its function is to provide the system with a rapidly switchable gradient field with linearity and precision that meets the requirements, so as to dynamically modify the main magnetic field and realize the spatial positioning of imaging voxels. In the gradient system, the control signal generated by the gradient waveform generator is used as the input of the gradient amplifier, and the current output of the gradient amplifier drives three sets of gradient coils to generate a gradient field in the imaging space, giving the spatial coordinates of the imaging site, so that each pixel in the ima...

AI Technical Summary

Problems solved by technology

The gradient amplifiers commonly used at the present stage, in the design of the output inductor filter part, the working voltage is low, most of them directly use high saturation current and low AL value magnetic core winding inductors for filtering. This design requires high switching frequency. Or multi-channel relatively low-frequency switching circuits are phase-shifted to achieve high-frequency effects, otherwise the requirements for low ripple and fast response cannot be met; in designs with high operating voltages, large inductors are generally connected in parallel or multiple small inductors are connected in series, or a series-parallel combination

The gradient amplifier designed with the above design method has large volume, complex structure and high cost, but the key performances such as fast response, low ripple and high fidelity are not satisfactory

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