| 摘要 |
A circuit arrangement for producing in an inductive load, especially a gradient coil for nuclear magnetic resonance tomography, a current pulse of trapezoidal shape, applies a series of supply voltage pulses, some of positive and some of negative polarity, via an auxiliary inductor to a parallel arrangement of the load and oppositely directed current drains, which are controlled by respective associated control elements. Each applied supply voltage pulse produces a variation of current through the parallel arrangement during the voltage pulse which is more steep than the leading or trailing edge of the current pulse through the load. The durations and spacings of the voltage pulses are such that the current through the parallel arrangement is larger than the current through the load in a first interval spanning the entire leading edge and constant current portion of the current pulse and is smalller than the current through the load throughout a second interval spanning the trailing edge of the current pulse, except for points at the very beginning and very end of these intervals at which the current through the parallel arrangement equals the current through the load. The difference between the current through the parallel arrangement and the current pulse through the load is passed by the applicably directed current drain under control of the respective control element.
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