Patent ID: 7161330

Claim:
An energy discharge apparatus for dissipating a quantity of stored magnetic energy in a coil, the coil having a current signal, the apparatus comprising: a variable impedance device having a first device terminal, a second device terminal and a third device terminal, the device being in series with the coil with the second device terminal being connected to a first coil terminal, a first voltage signal being between a second coil terminal and the third device terminal, a second voltage signal being between the second and the third device terminals, a third voltage signal being between the first and the third device terminals; a first control means for adjusting the variable impedance device, the first control means being connected to the first device terminal, the third device terminal and the second coil terminal, the first control means being responsive to the first voltage signal and being operable to adjust the third voltage signal, the third voltage signal being operable to adjust an impedance between the second and the third device terminals; and a second control means for rapidly adjusting the variable impedance device, the second control means being connected between the first device terminal, the second device terminal and the third device terminal, the second control means being responsive to the second voltage signal and being operable to decrease the third voltage signal thereby increasing the impedance.