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AssigneeKoninklijke Philips Electronics N.V.
InventorsThomas Scheel, Christian Hattrup
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A state space feedback controller operates in the digital domain for the regulation of the current supply to MRI gradient coils from a multiple-bridge PWM power amplifier. The P1-controller includes an integration part (for the integration of the difference between the demand current and the measured gradient coil current) and a subsequent P-controlled system which in turn includes a delay compensator/stabilizer and a plant. The delay compensator/stabilizer includes a multi-path feedback loop by means of which its digital output signal is fed back through delay blocks, on the one hand, and through filter units, on the other hand. The filter units model the transfer functions of a gradient coil output filter for the gradient coil voltage and the output current of the amplifier inverter units, respectively. In the plant, a filter unit, which models the gradient coil transfer function, is connected in series to a delay chain for the delay of the measurement value of the gradient coil current.
A method for operating an MRI gradient magnet system for generating gradient magnetic fields, by driving gradient coil currents through gradient coils of the gradient magnet system, wherein the gradient coil currents are controlled by a controller which is realized in the form of a state space feedback controller in the digital domain and which generates a digital output value by means of which a pulse-width modulated voltage is generated for driving the gradient coil currents through the gradient coils with a predetermined waveform wherein a control deviation is integrated which is generated in the form of a difference between the gradient coil current and a reference current,
A digital amplifier system for operating an MRI gradient magnet system for generating gradient magnetic fields, by driving gradient coil currents through gradient coils (GC) of the gradient magnet system, wherein the amplifier system comprises a digital controller (Con) for controlling the gradient coil currents, which controller (Con) is realized in the form of a state space feedback controller in the digital domain for generating a digital output value (u) by means of which a pulse-width modulated voltage is generated for driving the gradient coil currents through the gradient coils with a predetermined waveform,
A digital amplifier system for a magnetic resonance gradient magnet system which includes gradient coils configured to generate gradient magnetic fields in response to driving gradient coil currents, the amplifier system comprising:
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