| 摘要 |
PCT No. PCT/DE96/00899 Sec. 371 Date Mar. 10, 1998 Sec. 102(e) Date Mar. 10, 1998 PCT Filed May 23, 1996 PCT Pub. No. WO96/38893 PCT Pub. Date Dec. 5, 1996The magnetic residual energy stored in a coil is made to decay within a shorter and/or definite time period by the use of a free-wheeling circuit connected in parallel. The free-wheeling circuit comprises a series circuit, which includes a first diode and a first switching transistor connected in parallel to a non-linear resistor, connected in parallel to the coil. The first switching transistor is driven by a parallel circuit formed by a capacitor and a first ohmic resistor, which is connected in parallel to a second switching transistor. When a switch-off overvoltage appears in the coil, the second switching transistor becomes conductive and thus the first switching transistor is reliably blocked, so that the residual energy decays through the non-linear resistor.
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