| 摘要 |
The invention relates to a state space feedback controller operating in the digital domain for the regulation of the current supply to MRI gradient coils from a multiple-bridge PWM power amplifier. The Pl-controller comprises 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 comprises a delay compensator/stabilizer and a plant. The delay compensator/stabilizer comprises 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, whereby 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.
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