Circuit arrangement for an MRT system, MRT system and method for operating an MRT system

An MRT system, comprising:

• a circuit arrangement, including
• a gradient coil,
• a gradient amplifier, the gradient amplifier including
• a switch-mode output stage to provide a voltage for the gradient coil at an output of the switch-mode output stage,
• a regulator device to regulate a current for the gradient coil based upon a current setpoint value and a current actual value, tappable on an output side of the switch-mode output stage, and
• a modulator, electrically connected between the regulator device and the switch-mode output stage, to generate a modulator signal for driving the switch-mode output stage, the modulator signal specifying a pulse width modulation for the switch-mode output stage based upon a control signal output by the regulator device, and
• a circuit arrangement, to drive the gradient coil to ensure patient safety, a control path being integrated into a drive path of the circuit arrangement, the control path including
• a limiter stage, connected downstream of the regulator device, the modulator, the switch-mode output stage, and
• a supply voltage of the switch-mode output stage, wherein the limiter stage is connected between the regulator device and an input of the modulator, the limiter stage being configured to limit the control signal and being configured to limit the supply voltage of the switch-mode output stage;
• a control device, connected to the circuit arrangement, to specify a limit setting for the limiter stage;
• and
• a current measuring unit, arranged on an output side of the switch-mode output stage, to measure a current actual value, the current measuring unit being electrically connected to the regulator device to transmit the current actual value measured, to the regulator device.

A method for an MRT system, comprising:

• generating a control signal, via a regulator device of the MRT system, as a function of a difference between a current setpoint value and a current actual value, the current actual value being tapped on an output side of a switch-mode output stage of the MRT system and being output to a limiter stage of the MRT system;
• defining a current limit setting for the limiter stage, via a control device of the MRT system;
• limiting the control signal in accordance with the current limit setting defined, and outputting a limited control signal to a modulator of the MRT system, via the limiter stage;
• generating a modulator signal, via the modulator, as a function of the limited control signal;
• and
• specifying a pulse width modulation, for the switch-mode output stage, by the modulator signal to provide a voltage for a gradient coil of the MRT system, wherein a supply voltage of the switch-mode output stage is limited by the current limit setting.