System and method to reduce power loss in a gradient amplifier

摘要

A gradient amplifier system, includes: a power stage comprising a plurality of bridge amplifiers, each operates at a first switching frequency; a gradient coil coupled to the power stage and configured to produce a magnetic field proportional to a coil current signal supplied by the power stage; a controller stage coupled to an input terminal of the power stage and configured to: generate a pulse width modulated gate signal based on the coil current signal and a reference current signal, wherein the pulse width modulated gate signal is generated at a second switching frequency when a slew rate associated with the reference current signal is below a threshold rate for at least a first time period; and apply the pulse width modulated gate signal to the power stage for changing an operating frequency of each of the plurality of bridge amplifiers from the first to the second switching frequency.

主权项

1. A gradient amplifier system, comprising:
a power stage comprising a plurality of bridge amplifiers, wherein each of the plurality of bridge amplifiers operates at a first switching frequency; a gradient coil coupled to the power stage and configured to produce a magnetic field proportional to a coil current signal supplied by the power stage; a controller stage coupled to an input terminal of the power stage and configured to:
generate a pulse width modulated gate signal based on the coil current signal and a reference current signal, wherein the pulse width modulated gate signal is generated at a second switching frequency upon occurrence of a slew rate associated with the reference current signal is below a determined threshold rate for at least a first time period; andapply the generated pulse width modulated gate signal to the power stage for changing an operating frequency of each of the plurality of bridge amplifiers from the first switching frequency to the second switching frequency.