Abstract:
Ce convertisseur AC/DC est un convertisseur isolé à régulation par hachage du courant au moyen d’un interrupteur commandé (5). L’interrupteur commandé (5) est protégé par un dispositif de limitation de courant (9, 7) obéissant à une consigne de courant crête proportionnelle à la tension instantanée de la source d’alimentation (Vin). Cela permet d’améliorer la qualité du courant absorbé et limite les risques de pertubations de l’alimentation é découpage tout en satisfaisant aux nouvelles exigences des réseaux avioniques.
Abstract:
The invention proposes a single stage, single switch, input-output isolated converter configuration using a hybrid combination of forward and flyback converters. The converter operates at a high input power factor with a regulated DC output voltage. It makes use of a novel control scheme utilizing duty cycle control at two discrete operating frequencies. Although the invention employs two frequencies, it does not use a continuous frequency variation. The proposed configuration has the advantage of reduced peak current stresses on the components and is specifically suited for " buck" applications where low DC output voltages (e.g. 24V, 48V) are needed. The proposed configuration will be of specific interest to industries associated with battery charging and uninterruptible power supply (UPS) systems. A part from having several competitive features compared with prior art techniques, the proposed dual frequency operation scheme reduces the amplitude of its noise spectrum by spreading it over a wider frequency range thus making it more electromagnetic compatible.
Abstract:
Die Erfindung betrifft eine elektrische Schaltung zur Spannungswandlung. Die elektrische Schaltung ist zur Leistungsfaktorkorrektur geeignet. Dabei ist eine gute Leistungsfaktorkorrektur mit einem hohen Wirkungsgrad von 80% bis 95% im MHz-Frequenzbereich erzielbar. Dazu werden wenige, hochfrequenztaugliche Bauelemente (Kapazitäten, Induktivitäten, Dioden und Hochfrequenzschalter) verwendet. Die Dioden sind beispielsweise Schottkydioden mit SiC als Diodenmaterial. Der Hochfrequenzschalter weist einen leistungsfähigen MOS-Transistor auf.
Abstract:
The circuit arrangement has a mains connection (NA), a mains switch (S1) and a switched-mode power supply which contains a power factor coil (NS) for power factor correction. In this case, the mains switch (S1) has two switching contacts (1, 2), one (1) of which is arranged in a supply line between the mains connection (NA) and the switched-mode power supply, and in this way switches the phase or neutral conductor of the 50 Hz line network off and on. The connections (c, d) of the second switching contact (2) are located in a voltage supply for the driver circuit (DC) of the switched-mode power supply, and the second switching contact (2) switches the switching transistor in the switched-mode power supply off when the circuit arrangement is switched off, by its control voltage (DS) being switched off directly or indirectly. The switching contact (3) of a relay (R1) is arranged in parallel with the first switching contact (1) of the mains switch (S1), and the control coil (ST) of this relay (R1) is connected to an output voltage of the switched-mode power supply. Since the output voltages of the switched-mode power supply are each buffered by a capacitor, the relay is thus still open for a certain time after the arrangement has been switched off. The energy which is stored in the power factor coil is thus dissipated by the relay, by the coil drawing the current which is required to dissipate the energy from the mains via the relay.
Abstract:
A dual mode converter is provided that may be operated as a variable-frequency, naturally-commutated controller in a Zero-Voltage-Switching mode and as a fixed-off-time controller in a Fixed-Off-Time mode. The converter includes four functional elements. A reference and biases element generates voltage references and biases utilized to determine various signal states. A Timing element generates a fixed off time signal and a voltage ramp signal utilized to create the dual modes of operation. A Catastrophic-Event element detects events that cause the converter output to be inhibited and the controller to be restarted. A Mode Detection and Pulse Width Modulation element determines the mode of operation for the converter based on signal inputs from the other functional elements and modulates the output accordingly. In a primary mode, the controller utilizes variable frequency operation to deliver primary power. In a standby mode, the controller utilizes fixed frequency operation to provide low power (less than 5W).
Abstract:
A converter utilizing a multifilar transformer having its primary and auxiliary windings made simultaneously, a technique known as bifilar winding, provides high efficiency and low noise. The multifilar winding technique yields minimum leakage inductance between the windings and reduces the proximity effect to a minimum achievable using most well-known wires. The converter utilizes an improved soft-switcher topology which advantageously reduces the interwinding capacitance between the primary and auxiliary windings of the transformer. The topology includes a resonant LC circuit interposed in series with one leg of the auxiliary winding and the auxiliary switch. The other leg of the auxiliary winding is at ground. A controller is provided to control switch timing such that the converter optimizes switch loss and resonant pulse loss.
Abstract:
Effective harmonic correction without frequency, power or voltage limitations is achieved in a single-stage DC-to-DC converter by disconnecting the bulk capacitor (38) of a typical single-stage converter during low voltage conditions, and by using various phase and cycle modulation techniques associated with a switchable auxiliary transformer winding (48) which charges the bulk capacitor to control its voltage. A means is thus provided to control the level of harmonics generated depending upon the level of the AC output voltage. When the auxiliary winding is used as a clamp winding, full ZVS conditions are provided for both the auxiliary winding switch (66) and the converter's primary winding switch (52). Energy can then also be directed, under independent control of the switched auxiliary winding, to independent power nodes, i.e., either the output capacitance and load, or the bulk capacitor. This ensures that the output voltage will not be affected during any period needed to recharge the bulk capacitor.
Abstract:
An arrangement for converting an AC supply to a DC supply (as hereinbefore defined) comprising an inverter circuit and a boost power correction stage wherein said inverter circuit comprises switchable components and means utilising a pulsed wavefrorm indicative of power factor correction for causing some at least of said components repeatedly to adopt a condition permitting said boost power factor correction stage to draw current from said AC supply.
Abstract:
A power supply having a high power factor and low harmonic distortion which is stable in either an electrically isolated system or an electrically non-isolated system is provided. In the power supply for the electrically isolated system, a controller (207) is coupled to an AC voltage source and a primary winding (205). The primary winding (205) is inductively coupled to a secondary (270) and an auxiliary winding (212). The secondary winding (270) provides the output DC voltage. The secondary winding (270) and auxiliary winding (212) are formed in a tight magnetic coupling. The auxiliary winding (212) provides a voltage supply for the controller (207) and also provides an accurate representation of the output voltage to the controller (207) in a voltage feedback path. The separate voltage feedback path to the controller isolates the distortion which is inherent in the voltage supplied to the controller (207).