Abstract: A power supply module having a PFC stage has a hold-up capacitor (34) for continuing output power for a time after an ac power supply (2) stops. The hold-up capacitor is charged by a winding (40) driven magnetically from a first winding (24); the first winding (24) may be the winding used in a boost converter stage, such as commonly used in a PFC stage, or alternatively the winding in an alternative stage such as a flyback converter.

Abstract: A resonant converter (10) comprising a voltage compensation circuit (72, 73) configured to generate a periodic compensation voltage signal (Vslopecompens) at a switching frequency of the converter such that conduction intervals (31, 32) are ended according to first and second voltage levels in combination with the periodic compensation signal.

Abstract: Consistent with an example embodiment, there is a method of controlling a synchronous rectifier having an input signal having oscillations therein and a switch which is switchable between an open state and a closed state. The method comprises filtering the input signal to produce a filtered signal, comparing the filtered signal with a reference value, and opening the switch in response to the comparison, in which the filtering is active filtering. The active filtering may be based on determination of the peaks (positive and/or negative) of the signal, either directly, including a quarter period offset, or including decay—or a combination of the above; alternatively, the active filtering may be based on the a smoothing functions such as a switched low-pass filter or a short time integrator.

Abstract: An electrical power converter includes a transformer (4) with a primary circuit and a secondary circuit. Detecting circuitry is employed to compute a signal representative of the output current in the secondary circuit, and this signal controls the timing of the switching function of rectification switches (49,50) which rectify the secondary AC signal.

Abstract: An electrical power converter has a transformer (4) and detecting circuitry for deriving a reconstructed output or load current. In a first aspect of the invention the load current is computed by subtracting a scaled version of the time integral of the primary voltage (Vcap) from a scaled version of the primary current (Iprim). In a second aspect of the invention the load current is computed by subtracting a scaled version of the time integral of the voltage (Vaux) across an auxiliary winding (24) from a scaled version of the primary current (Iprim).

Abstract: The invention deals with the control of a resonant LLC converter by use of control parameters. The primary current flowing in the resonant tank and a voltage at a predetermined point in the resonant tank are monitored and control parameters are set for a high side conduction interval and control parameters are set for a low side conduction interval, the control parameters for the two conduction intervals being: a peak current of the interval and a predetermined voltage of the interval. The resonant converter comprises series-arranged controllable switches to be connected to the supply source. The resonant converter is operated by setting up criteria for turning off a switch in accordance with criteria including the four control parameters.

Abstract: In order to improve the efficiency of a Power Factor Convertor (PFC) first stage to a AC-DC converter the switching cell is split into two smaller ones (each comprising a switched inductor with an output diode). Below a certain load only one cell is active. The second cell only becomes active, out of phase with the first, but not generally in antiphase, after a predefined load level is surpassed in such a way that above that level the first cell has a fixed on time and the second cell a variable one.

Abstract: A method of operating a resonant power converter(1, 2), having a high side switch(3) and a low side switch(4), is disclosed in which the switching is controlled to allow for improved operation at low power levels. The method involved an interruption to the part of the switching cycle in which the low side switch (4) is normally closed, by opening the switch at a particular moment in the cycle which allows the energy to be store in the resonance capacitor (5). Since, as a result, the energy is largely not resonating but stored in a single component, the time quantisation of the mode of operation is significantly reduced or eliminated.

Abstract: A method of operating a resonant power supply in standby mode is disclosed, in which the switching period of the power supply is longer than the resonance period. The power converter is operated in normal mode for a significant fraction of one resonance period. Efficient operation is maintained, despite the switching period being extended beyond the resonance period, by using resonance current to enable soft switching, where this is beneficial, and dumping the resonance current into the load where this is more beneficial. Control methodologies to regulate the output power are also disclosed.

Abstract: A resonant converter comprises switching circuitry (1) for supplying pulses, at a controllable frequency, to a resonant circuit so as to power the primary circuit (3, 12) of a transformer (4). The secondary winding (5a, 5b) of the transformer (4) delivers an AC signal which is rectified and then produces a load current. On the primary side, the converter has a resistor (13) for deriving a first electrical signal representative of the current in the primary circuit (3, 12), and an auxiliary winding (14) which is closely coupled to the secondary winding (5a, 5b) and across which an auxiliary voltage is induced as a consequence of the close coupling of the winding (14) to the secondary winding (5a, 5b). A resistor/capacitor combination (16, 17) integrates the auxiliary voltage with respect to time to derive a second electrical signal.

Abstract: The invention deals with the control of a resonant LLC converter by setting up criteria for state parameters of the resonant converter, so that the converter may be operated in a near capacitive mode. The current flowing in the resonant tank and optionally the voltage at the a predetermined point in the resonant tank are monitored, and wherein a switch (a high side switch or a low side switch) is turned off when a first criterion is fulfilled together with a second criterion or optionally a third criterion, the first criterion ensuring a minimum time has lapsed after the switch is turned on, the second criterion being that the absolute value of the current is reaching a predetermined current level, the third criterion being that the voltage at the predetermined point reaches a predetermined voltage level.

Abstract: The invention deals with the control of a resonant LLC converter by use of control parameters. The primary current flowing in the resonant tank and a voltage at a predetermined point in the resonant tank are monitored and control parameters are set for a high side conduction interval and control parameters are set for a low side conduction interval, the control parameters for the two conduction intervals being: a peak current of the interval and a predetermined voltage of the interval. The resonant converter comprises series-arranged controllable switches to be connected to the supply source. The resonant converter is operated by setting up criteria for turning off a switch in accordance with criteria including the four control parameters.