Speaker:
Juan A. Sabate, Ph.D.

Senior Principal Engineer, General Electric

When: 12:00 PM, April 20, 2022

Abstract:

The improvements in MRI as a diagnostic tool in terms of image quality, speed, and clinical use have required increased capabilities and performance of the gradient amplifier. In addition, extremely high fidelity for reproducing the current command from the central system is very critical for imaging quality. Therefore, high power and high bandwidth gradient driver is needed for a high-performance MRI system. The driver output is arbitrary bidirectional currents that can be pulsating between zero and full power and must be reproduced with errors on the ppm range.

The gradient Driver is one of the key components in a magnetic resonance imaging (MRI) scanner. The driver is responsible to create gradient fields by supplying the gradient coil with a large current (>1000A) and high voltage (>2000V) to achieve a strong gradient field and fast slew rate.

The gradient driver consists of three switching power amplifiers (inverters), multiple power supplies, and high-performance digital control:

• Switched amplifiers are implemented with cascaded H-bridges to have high ripple frequencies (>125kHz) for the required bandwidth at power levels needed. High-performance modular solution with SiC devices enables solutions with only two bridges and 99% efficiency.
• The accuracy for the currents supplied to the gradient coils requires regulated voltages provided to the inverter with reduced voltage change (<10%). The power supplies must be designed for peak power. Capacitors for energy storage in the system limit voltage sag and peak power draw from the facility power utilities.,

The presentation will provide a description of the electronics technology and technical implementation of the amplifiers currently used on high-performance MRI systems.

Zoom Meeting: https://fiu.zoom.us/j/98364582724

Meeting ID: 983 6458 2724, Passcode: YznTR7 

Flyer for Event: Link