Abstract: A synchronous rectifier comprises at least one rectification switch (102, 103), and a control circuit (104) for controlling the at least one rectification switch to allow unidirectional current flow only. The control circuit comprises at least one current sensor (105, 106) for sensing an alternating component of current of the at least one rectification switch, and at least one driver circuit (107, 108) for controlling the at least one rectification switch at least partly on the basis of the direction of the sensed alternating component. Using the alternating component for controlling the rectification switch removes a need to compare the current to any non-zero constant or adjustable threshold value, and thus challenges related to defining the threshold value can be avoided. The synchronous rectifier can be for example a part of a resonant converter.

Abstract: A transformer comprises first winding portions (101, 102) constituting a first foil winding and second winding portions (103, 104) constituting a second foil winding having a substantially same magnetic axis as the first foil winding. The first and second winding portions are interleaved in directions substantially perpendicular to the magnetic axis so as to reduce the leakage inductances of the first and second foil windings. The first winding portions are electrically interconnected so that at least one end-portion of each first winding portion is split to constitute two strips (105a, 105b) folded to mutually opposite directions substantially parallel with the magnetic axis, and ends of the strips of different first winding portions are interconnected to constitute connection bridges over a particular one of the second winding portions located between these first winding portions. The second winding portions are electrically interconnected in the corresponding way to constitute the second foil winding.

Abstract: A circuit breaker arrangement in supply of electric power has advantageous applications especially in power distribution units which supply DC power to electrical devices. Electromechanical circuit breakers are commonly used for circuit protection. They have a disadvantage of fixed tripping conditions, which can only be changed by changing the circuit breaker component. This is solved by providing a circuit breaker arrangement which has an electromechanical circuit breaker with a first, fixed tripping condition, and an additional circuit, which monitors the output current and mechanically trips the circuit breaker if the current exceeds a second tripping condition. This way, it is possible to use the first tripping condition of the electromechanical circuit breaker and/or a second, controllable tripping condition.

Abstract: An overload protection circuit for supplying electric power has advantageous applications especially in supplying power to capacitive loads. In prior art circuits, the charging current is lead to the capacitive load through a linearly operating transistor or through a power resistor. Therefore, prior art circuits often involve a risk of exceeding safe operating area of a power transistor, or circuits with a large number of components are needed. The present overload protection circuit has an inductor (L) coupled in series with a switching element (Q). Load current is measured (35, 38), and the switching element (Q) is controlled (35, 36) to supply current to the load via the inductor (L) until a determined current limit is achieved. After achieving the current limit the switching element (Q) is controlled to off-state, during which the freewheeling current of the inductor (L) is lead through a voltage dependent element (Z).

Abstract: A circuit breaker arrangement in supply of electric power has advantageous applications especially in power distribution units which supply DC power to electrical devices. Electromechanical circuit breakers are commonly used for circuit protection. They have a disadvantage of fixed tripping conditions, which can only be changed by changing the circuit breaker component. This is solved by providing a circuit breaker arrangement which has an electromechanical circuit breaker with a first, fixed tripping condition, and an additional circuit, which monitors the output current and mechanically trips the circuit breaker if the current exceeds a second tripping condition. This way, it is possible to use the first tripping condition of the electromechanical circuit breaker and/or a second, controllable tripping condition.

Abstract: The invention relates to power supplies where the output current is controllable. In prior art, there is a problem to provide both high rate of change in the current output and high efficiency. The solution of the present invention is based on combining current elements, whereby the current is controlled by switching the outputs of the current elements. The current elements can be implemented with e.g. buck converters, whereby the power dissipation is small.

Abstract: An overload protection circuit for supplying electric power has advantageous applications especially in supplying power to capacitive loads. In prior art circuits, the charging current is lead to the capacitive load through a linearly operating transistor or through a power resistor. Therefore, prior art circuits often involve a risk of exceeding safe operating area of a power transistor, or circuits with a large number of components are needed. The present overload protection circuit has an inductor (L) coupled in series with a switching element (Q). Load current is measured (35, 38), and the switching element (Q) is controlled (35, 36) to supply current to the load via the inductor (L) until a determined current limit is achieved. After achieving the current limit the switching element (Q) is controlled to off-state, during which the freewheeling current of the inductor (L) is lead through a voltage dependent element (Z).

Abstract: The invention relates to power supplies where the output current is controllable. In prior art, there is a problem to provide both high rate of change in the current output and high efficiency. The solution of the present invention is based on combining current elements, whereby the current is controlled by switching the outputs of the current elements. The current elements can be implemented with e.g. buck converters, whereby the power dissipation is small.