Abstract: The invention relates to a control means and method for a transistor switch circuit controlling a power supply circuit for providing electric power to a load, comprising: a power supply stage having an LC circuit with an inductor, and a control stage having an estimation of the inductor current as a feedback signal. According to the invention, the current through the inductor is measured by means of a measuring winding (17) and an integrator having the function of an RC network. The current measuring circuit is very stable and absolutely free from any source of offset signals. Also, it has no frequency limitations.

Abstract: The invention relates to a control means for a transistor switch circuit controlling a power supply circuit for providing electric power to a load, comprising: a power supply stage having a transistor bridge circuit and an LC circuit with an inductor and filter capacitors, and a control stage. The control stage comprises a monitor circuit for monitoring a bridge voltage of a connection between two semiconductor members and the current through the inductor, said monitor circuit comprising a first comparator for comparing when the current through the inductor exceeds a reference value and a second comparator for comparing when the bridge voltage changes polarity towards the corresponding rail polarity; and a drive circuit adapted to provide a firing pulse to one of said switchable members of said semiconductor members for initiating the conduction thereof.

Abstract: This invention relates to a multiple stage switch circuit for power electronics. The switch circuit is intended to supply electric power to any type of load. The invention provides a power supply circuit for providing power to a load, comprising: power supply stages each comprising a pair of switchable members in a bridge circuit and an LC filter connected between the center of the bridge circuit and the load, and a control stage for controlling turning on and off of the switchable members. According to the invention at least two power supply stages are connected in parallel with a common output to the load, and said power supply stages are synchronized by a common master control unit. The power supply circuit further comprises a unit for enabling a number of power supply stages while the rest of the power supply stages may be disabled in response to required output power characteristics.