Methods and devices for sensing current through a power converter circuit are presented. According to one aspect, currents through high-/low-side transistors are sensed via respective reduced size replica transistors. According to another aspect, the sensed currents are used to generate bridging currents that are combined with the sensed currents to generate a continuous current sense signal. According to another aspect, the bridging currents include slopes that are generated from slopes of the sensed currents. According to another aspect, the sensed currents are combined and filtered to generate a continuous sense signal. According to another aspect, the continuous current sense signal is a voltage that is compared to a reference voltage to generate a current limit status flag used to control operation of the power converter circuit. According to other aspects, the current sense voltage is used to control ON/OFF duty cycle of the power converter circuit.

A power supply circuit can include: a constant current control circuit configured to receive a first voltage and a first current from a power supply, and to generate a second voltage and a second current that are substantially constant; a shunt circuit, where when the second current is greater than the output current, the shunt current circuit is configured to shunt the second current, and when the second current is less than or equal to the output current, the shunt circuit stops operating; and an energy storage circuit, where when the second current is greater than the output current, the energy storage circuit is configured to store energy, and when the second current is less than or equal to the output current, the energy storage circuit is configured to release energy and provide power for the load together with the constant current control circuit.

A sampling circuit for a switching power supply, can include: a first sampling circuit configured to acquire a first sampling signal of a current flowing through an inductor in the switching power supply; and a second sampling circuit configured to obtain a compensation signal with a same rising slope as the first sampling signal within a turn-off delay time of a power switch in the switching power supply, and to superimpose the compensation signal on the first sampling signal to generate a second sampling signal.

There is provided a fuel cell system. This fuel cell system comprises a fuel cell configured to generate electric power using reactive gases; a voltage sensor configured to measure a voltage output from the fuel cell; a converter configured to boost an input voltage that is input from the fuel cell; and a controller configured to control the converter. In the case where the voltage output from the fuel cell to the converter is to be boosted after a changeover of an operating state of the fuel cell system from an intermittent operation to an ordinary operation, when a duty ratio D1 calculated by Mathematical Formula I is greater than a duty ratio D2 calculated by Mathematical Formula II, the controller causes the converter to boost the voltage output from the fuel cell at the duty ratio D2. $\begin{array}{cc}\left[\mathrm{Math}.1\right]& \\ D1=1-\frac{\mathrm{Vltrg}}{\mathrm{VH}}& \left(I\right)\end{array}$
where VH (V) denotes a value of output voltage that is output from the converter, and Vltrg (V) denotes an estimated value of voltage that is output from the fuel cell, $\begin{array}{cc}\left[\mathrm{Math}.2\right]& \end{array}$

A power scavenger circuit (180) in a sensor device (100) for a lighting system (1) comprises: a controllable boost converter (110) having an input (111, 112) for receiving an input current (Iin) from an interface (2), and having an output (119a, 119b) for providing an output voltage (VB); a capacitor (130) coupled to the output of the boost converter (110); a second converter (140) having an input (141, 142) coupled to the capacitor and having an output (149a, 149b) for providing a supply voltage (VDD) for a microprocessor (150). A scavenging control device (120) has a sensing input (121) coupled to said converter input for sensing the voltage (Vout) at said converter input. The scavenging control device controls the boost converter in such manner that the sensed voltage is kept constant, so that the voltage at said interface can be considered as an output signal from the sensor device.

A regulated current-fed power system employs power branching units connected in series. Each power branching unit includes a plurality of parallel-redundant converter groups connected in series with each other within a current path for the regulated current. Each parallel-redundant converter group includes at least two direct current (DC)/DC converters connected in parallel with each other, each sharing the power load. A protection device connected in series with each DC/DC converter disconnects the respective DC/DC converter from the regulated current when the respective DC/DC converter short circuits, with the remaining DC/DC converter(s) then receiving more of the power load. An active clamp connected in parallel with all of the DC/DC converters within a parallel-redundant converter group temporarily sinks a portion of the regulated current when one of the DC/DC converters fails in a short-circuit condition. The active clamp shunts the regulated current around all DC/DC converters within the parallel-redundant converter group converters fail in a short-circuit condition.

Method for protecting against overvoltage a current fed converter, comprising a switching cell having two or more legs, each leg being provided with at least one switching device, in an open circuit failure condition of a switching device in a leg of said switching cell, comprising measuring current derivative signals in respective upper switching devices or lower switching devices of at least two of said legs where a switching transition occurs, said switching transition comprising a change of current conducting switching device within said upper switching devices or lower switching devices and triggering a protection, based on said current derivative signals, when either: the absolute value of one of said current derivative signal being lower than a first predefined value or null, or a sum of the absolute values of said current derivative signals being lower than a second predefined value,
during said switching transition.

A method for converting an input voltage (V.sub.in) of a converter (1) into an output voltage (V.sub.out), the circuit comprising a first bridge arm consisting of two switches (A) and (B), a second bridge arm consisting of two switches (C) and (D), connected in parallel, a primary coil coupled to a secondary coil, and connected by a center point pole (PAB) of the first bridge arm, and by another center point pole (PCD) of the second bridge arm; the circuit further comprising a capacitor in parallel between the respective terminals of each of the switches (A, B, C, D); a third bridge arm formed by two switches (E) and (F), connected in series; each of the switches (A, B, C, D, E, F) being associated with a diode at the terminals of said switch; an injection inductance (L.sub.inj) connected to the center point (P.sub.AB) of the first bridge arm, and to the center point (P.sub.EF) of the third bridge arm; a monitoring-control unit configured to control the switches to turn them ON or OFF, according to a control cycle configured to ensure soft switching between ON and OFF.

A regulated current-fed power system employs power branching units connected in series. Each power branching unit includes a plurality of parallel-redundant converter groups connected in series with each other within a current path for the regulated current. Each parallel-redundant converter group includes at least two direct current (DC)/DC converters connected in parallel with each other, each sharing the power load. A protection device connected in series with each DC/DC converter disconnects the respective DC/DC converter from the regulated current when the respective DC/DC converter short circuits, with the remaining DC/DC converter(s) then receiving more of the power load. An active clamp connected in parallel with all of the DC/DC converters within a parallel-redundant converter group temporarily sinks a portion of the regulated current when one of the DC/DC converters fails in a short-circuit condition. The active clamp shunts the regulated current around all DC/DC converters within the parallel-redundant converter group converters fail in a short-circuit condition.

A current control apparatus arranged to regulate an electric current flowing between a load and an external electric circuit includes a current control loop having a current regulator arranged to manipulate an amount of the electric current flowing between the load and the external electric circuit; and a voltage control loop having a voltage regulator arranged to manipulate a voltage across the current regulator.