Patent ID: 7019493
Filing Date: 2006-03-28
Classification: H02J

Abstract:
1. A protection circuit ( 30 ) which comprises at least one switch (FET 1 , FET 2 ) comprising at least one control means (G 1 , G 2 ) for adjusting the conductivity of at least one switch (FET 1 , FET 2 ), the conductivity being arranged to be adjustable by means of an electrical control applied to the control means (G 1 , G 2 ), characterized in that the protection circuit ( 30 ) comprises means ( 22 , 25 , 26 ) for forming the electrical control, means ( 27 , 28 ) for measuring at least one physical quantity affecting said at least one switch (FET 1 , FET 2 ), means ( 10 ) for providing information about the dependence of the conductivity properties of said at least one switch (FET 1 , FET 2 ) on said at least one physical quantity, means ( 29 ) for determining the conductivity of said at least one switch (FET 1 , FET 2 ) on the basis of said at least one physical quantity and the conductivity properties of said at least one switch (FET 1 , FET 2 ) and means ( 29 , 27 ) for determining the current (I TOT ) passing through said at least one switch (FET 1 , FET 2 ) at least partly on the basis of said conductivity, wherein said electrical control is arranged to be formed at least partly on the basis of said determined current.