Voltage converter

Abstract

Voltage Converter. This description relates to a voltage converter comprising a circuit (401A) including a parallel connection, between first (305) and second (307) nodes, of a first branch comprising a first controlled rectifier element (309) having a first impedance and a second branch comprising a resistor (303) connected in series with one or more second rectifier elements (403) having a second impedance substantially equal to the first impedance. Figure for the abbreviation: Fig. 4A

Description

Title of the invention: Voltage converter Technical field

[0001] The present description relates generally to electronic devices. The present description relates more particularly to rectifier-type voltage converters, or AC-DC converters, making it possible to supply a rectified voltage, for example substantially DC, from an AC voltage source. Prior art

[0002] Numerous AC-DC converters are known, typically comprising rectification elements, controllable or not, mounted in a rectifier bridge, and at least one filtering, or smoothing, capacitor for the rectified voltage. These converters are notably present in switching power supplies commonly found in television screens, desktop computer central units, light fixtures, etc. When a device comprising such a converter is switched on, the filtering capacitor causes, due to its load, a high current draw. This current draw disrupts the power supply network and damages the elements of the converter as well as the components or circuits of the device connected to it.

[0003] To overcome this problem, some AC-DC converters include an inrush current limiting circuit. Once the current is established, however, the inrush current limiting circuit causes undesirable power consumption and heating. Summary of the invention

[0004] One embodiment overcomes all or part of the drawbacks of known voltage converters.

[0005] An object of the described embodiments is to increase the energy efficiency of known voltage converters. Another object of the described embodiments is to increase the reliability of known voltage converters.

[0006] One embodiment provides a voltage converter comprising a circuit comprising a parallel association, between first and second nodes: - of a first branch comprising a first controlled rectification element having a first impedance; and - a second branch comprising a resistor associated in series with one or more second rectifying elements having a second impedance substantially equal to the first impedance.

[0007] According to one embodiment, the first controlled rectification element is a first triac.

[0008] According to one embodiment, the first controlled rectification element is a first thyristor.

[0009] According to one embodiment, the second branch comprises a single second straightening element.

[0010] According to one embodiment, the second rectifying element is controlled.

[0011] According to one embodiment, the second rectifying element is a second triac.

[0012] According to one embodiment, the trigger of the second triac is connected, preferably connected, to the second anode of the second triac.

[0013] According to one embodiment, the first and second triacs are integrated in the same housing.

[0014] According to one embodiment, the second controlled rectification element is a second thyristor.

[0015] According to one embodiment, the trigger of the second thyristor is connected, preferably connected, to the anode of the second thyristor.

[0016] According to one embodiment, the second rectifying element is a diode.

[0017] According to one embodiment, the resistance is in series with an association in antiparallel of first and second diodes, the antiparallel association of the first and second diodes having the second impedance.

[0018] According to one embodiment, the resistor is intended to dissipate inrush currents.

[0019] According to one embodiment, the resistor is a thermistor with a negative temperature coefficient.

[0020] According to one embodiment, the converter further comprises: - a rectifier bridge; and - a capacitor.

[0021] One embodiment provides a device comprising a converter as described. Brief description of the drawings

[0022] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0023] [Fig.l] is a diagram illustrating an example of a voltage converter;

[0024] [Fig.2A] is a diagram illustrating another example of a voltage converter comprising an inrush current limiting circuit;

[0025] [Fig.2B] is a diagram illustrating yet another example of a voltage converter having an inrush current limiting circuit;

[0026] [Fig.3A] is a diagram illustrating an example of an inrush current limiting circuit;

[0027] [Fig.3B] is a diagram illustrating another example of an inrush current limiting circuit;

[0028] [Fig.4A] is a diagram illustrating one embodiment of an inrush current limiting circuit;

[0029] [Fig.4B] is a diagram illustrating another embodiment of an inrush current limiting circuit;

[0030] [Fig.5A] is a diagram illustrating an alternative embodiment of the circuit of [Fig.4A];

[0031] [Fig.5B] is a diagram illustrating an alternative embodiment of the circuit of [Fig.4B];

[0032] [Fig.6A] is a diagram illustrating one embodiment of a voltage converter;

[0033] [Fig.6B] is a diagram illustrating another embodiment of a voltage converter; and

[0034] [Fig.7] represents a device comprising a voltage converter. Description of the embodiments

[0035] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0036] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the possible applications of the voltage converters are not detailed, the described embodiments being compatible with the usual applications implementing voltage converters.

[0037] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0038] In the following description, when referring to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., are used, unless otherwise specified, to refer to the orientation of the figures.

[0039] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0040] [Fig.l] is a diagram illustrating an example of a voltage converter 100.

[0041] In the example shown, the voltage converter 100 comprises a rectifier bridge 101. The rectifier bridge 101 receives, at its input, an alternating voltage Vin and provides, at its output, a rectified voltage Vout.

[0042] The input voltage Vin is for example a sinusoidal voltage. The voltage Vin is for example a single-phase supply voltage from an electrical distribution network (not shown), for example the mains. By way of example, the input voltage Vin has an effective value equal to approximately 230 V and a frequency equal to approximately 50 Hz, or an effective value equal to approximately 110 V and a frequency equal to approximately 60 Hz.

[0043] In the example illustrated in [Fig.l], the input voltage Vin is applied between a first node 103 and a second node 105 of the rectifier bridge 101 of the converter 100. The output voltage Vout is for example available between a third node 107 and a fourth node 109 of the rectifier bridge 101 of the converter 100. The node 109 of the rectifier bridge 101 is for example brought to a reference potential, for example ground.

[0044] In the example shown, the rectifier bridge 101 of the converter 100 is of the uncontrolled full-wave type. The rectifier bridge 101 is more precisely, in this example, a diode bridge comprising: - a first diode 111, the anode of which is connected to node 103 and the cathode of which is connected to node 107; - a second diode 113, the anode of which is connected to node 109 and the cathode of which is connected to node 103; - a third diode 115, the anode of which is connected to node 105 and the cathode of which is connected to node 107; and - a fourth diode 117, the anode of which is connected to node 109 and the cathode of which is connected to node 105.

[0045] In the example shown, the first node 103 of the rectifier bridge 101 is connected to the mains via a switch 119. The switch 119 comprises, for example, more precisely, a terminal 121 connected to a phase conductor of the mains and another terminal 123 connected to the node 103 of the bridge 101. The second node 105 of the rectifier bridge 101 is, in this example, connected to the mains, for example to a neutral conductor of the mains. The switch 119 is adapted to power up the converter 100, i.e. to apply between the nodes 103 and 105 of the bridge 101 the voltage Vin (except for the voltage drops in the conductors) supplied by the mains.

[0046] In the example shown, the converter 100 further comprises an electrical capacitance 125, for example a capacitor. The capacitor 125 is, in this example, connected between the nodes 107 and 109 of the rectifier bridge 101. The capacitor 125 comprises, for example, more precisely, a terminal 127 connected to the node 107 and another terminal 129 connected to the node 109. The capacitor 125 is, for example, intended to filter or smooth the voltage Vout. The output voltage Vout is then, for example, a substantially continuous voltage.

[0047] The voltage Vout makes it possible, for example, to supply a load 131 (L), shown in dotted lines in [Fig.l], associated in parallel with the capacitor 125. The load 131 is, for example, connected to the nodes 107 and 109 of the rectifier bridge 101 of the converter 100.

[0048] When the converter 100 is powered up, for example when the switch 119 is switched from an open state to a closed state, the capacitor 125 produces a transient overcurrent commonly referred to as inrush current or inrush current. The inrush current, with an intensity reaching for example five to twenty times that of the nominal current, damages in particular the diodes 111, 113, 115 and 117 of the rectifier bridge 101 each time it is powered up. This is detrimental to the reliability of the converter 100. The inrush current is also likely to damage the capacitor 125, cause non-compliance with flicker standards and disrupt the power supply network.

[0049] [Fig.2A] is a diagram illustrating another example of a 200A voltage converter. The 200A voltage converter of [Fig.2A] includes elements in common with the 100A voltage converter of [Fig.1]. These common elements will not be detailed again below.

[0050] The converter 200A of [Fig.2A] differs from the converter 100 of [Fig.1] mainly in that the converter 200A comprises, in addition to the rectifier bridge 101, a circuit 201A for limiting the inrush current.

[0051] In the example shown, the circuit 201A is located at the input of the converter 200A, on the alternating voltage Vin side. In this example, the circuit 201A is more precisely connected between the first node 103 of the rectifier bridge 101 and the terminal 123 of the switch 119.

[0052] In the example shown, the circuit 201A comprises a resistor 203. The resistor 203 of the circuit 201A comprises, for example, a terminal 205 connected to the terminal 123 of the switch 119 and another terminal 207 connected to the node 103 of the rectifier bridge 101.

[0053] In the example shown, the circuit 201A further comprises a switch 209 associated in parallel with the resistor 203, for example connected between the terminals 205 and 207 of the resistor 203. In the open position, the switch 209 forces the passage of current through the resistor 203.

[0054] In the closed position, the switch 209 connects the terminal 205 to the terminal 207, which has the effect of short-circuiting the resistor 203. The current then flows mainly through the switch 209.

[0055] For example, the switch 209 is a relay, for example a single-pole electromechanical relay of which only the power contact is shown in [Fig.2A].

[0056] When the converter 200A is powered up, for example when the switch 119 is switched to the closed position, the relay 209 is held in the open position. The current then flows through the resistor 203. The resistor 203 causes a voltage drop between its terminals 205 and 207. This makes it possible to limit the inrush current when the capacitor 125 is charged when the power is switched on.

[0057] Once the capacitor 125 is charged, for example after a delay following the switching on of the 200A converter, the relay 209 is switched to the closed position. The current then flows mainly in the relay 209. This allows the rectifier bridge 101 of the 200A converter to be traversed by a nominal current adapted according to the application.

[0058] [Fig.2B] is a diagram illustrating yet another example of a voltage converter 200B. The voltage converter 200B of [Fig.2B] includes elements in common with the voltage converter 100 of [Fig.1]. These common elements will not be detailed again below.

[0059] The converter 200B of [Fig.2B] differs from the converter 100 of [Fig.1] mainly in that the converter 200B includes an inrush current limiting circuit 201B located at the output of the rectifier bridge 101, on the rectified voltage Vout side. In this example, the circuit 201B is more precisely connected between the third node 107 of the rectifier bridge 101 and the terminal 127 of the capacitor 125.

[0060] The circuit 201B is for example identical to the circuit 201A of the converter 200B of [Fig.2A]. In this case, the terminal 205 of the resistor 203 of the circuit 201B is connected to the node 107 of the rectifier bridge 101 and the terminal 207 of the resistor 203 is connected to the terminal 127 of the capacitor 125.

[0061] The operation of the circuit 201B of the converter 200B is similar to that of the circuit 201A of the converter 200A as previously described in relation to [Fig.2A].

[0062] A disadvantage of the circuits 201A and 201B comes in particular from the presence of the relay 209. The relay 209 is in fact liable to wear out, for example by erosion of its power contact at each load switching. This harms the reliability of the circuit 201A, 201B forming part of the converter 200A, 200B.

[0063] The relay 209 also emits a noise, typically a clicking sound, with each switching. This clicking sound is unpleasant for the user and can also disrupt voice recognition systems located near the relay 209, for example integrated into the device comprising the converter 200A or 200B.

[0064] [Fig.3A] is a diagram illustrating an exemplary inrush current limiting circuit 301A.

[0065] The inrush current limiting circuit 301A comprises a resistor 303. In the example shown, the resistor 303 is a thermistor, more precisely a negative temperature coefficient (NTC) thermistor. The thermistor 303 is, in this example, connected between nodes 305 and 307 of the circuit 301A.

[0066] The circuit 301A further comprises a triac 309, for example associated in parallel with the thermistor 303. In the example shown, the triac 309 has more precisely its first anode (A1) connected to the node 305 of the circuit 301A and its second anode (A2) connected to the node 307 of the circuit 301A. By first anode of a triac, we mean the anode located on the trigger (G) side of the triac while, by second anode of a triac, we mean the anode opposite the first anode.

[0067] The circuit 301A illustrated in [Fig.3A] is for example intended to replace the circuit 201A of the converter 200A of [Fig.2A]. The node 305 of the circuit 301A, analogous to the node 205 of the circuit 201 A, is then for example connected to the terminal 123 of the switch 119 while the node 307 of the circuit 301A, analogous to the node 207 of the circuit 201A, is for example connected to the node 103 of the rectifier bridge 101.

[0068] The triac 309 is for example switched between on and off states in a manner similar to what was previously described for the electromechanical relay 209 of the circuit 201A of [Fig.2A]. More precisely, the triac 309 is for example maintained in a off state during the converter power-up phase, in order to force the flow of current in the thermistor 303. Once the capacitor 125 is charged, that is to say in steady state, the triac 309 is then switched to an on state, for example by applying a current pulse to its trigger G. The triac 309 then allows the current to flow in both directions, namely from its first anode A1 to its second anode A2 and from its second anode A2 to its first anode A1.

[0069] In the on state, the triac 309 has an impedance much lower than that of the blocked state. This impedance in the on state is however non-zero. As a result, the triac 309 is the origin of a voltage drop Vtriac between terminals 305 and 307 of the circuit 301A. For example, the voltage drop Vtriac is of the order of 1 V.

[0070] Due to its association in parallel with the triac 309, the thermistor 303 undergoes a voltage drop Vntc. The voltage drop Vntc is in this case substantially equal to the voltage drop Vtriac, apart from the voltage drops in the conductors.

[0071] The voltage drop Vntc present at the terminals of the thermistor 303 when the triac 309 is in the on state causes a current Intc to flow through the thermistor 303. For example, the inventors have estimated that, for an input current I of the order of 6 A reaching the node 305, the triac 309 is traversed by a current Itriac of the order of only 4 A, for a current Intc flowing through the thermistor 303 of the order of 2 A.

[0072] The current Intc is responsible for heating of the thermistor 303 by Joule effect. This heating is the cause of a significant drop in energy efficiency of the converter comprising the circuit 301A, and causes premature wear of the thermistor 303. In the example shown, where the thermistor 303 has a negative temperature coefficient, heating of the thermistor 303 also causes a drop in resistance tending to amplify the phenomenon. This drop in resistance in fact promotes the passage of a greater current Intc in the thermistor 303, therefore additional heating, and so on.

[0073] [Fig.3B] is a diagram illustrating another example of inrush current limiting circuit 301B. Circuit 301B of [Fig.3B] includes elements in common with circuit 301A of [Fig.3A]. These common elements will not be detailed again below.

[0074] The circuit 301B of [Fig.3B] differs from the circuit 301A of [Fig.3A] mainly in that the circuit 301B comprises, instead of the triac 309, a thyristor 311. In the example shown, the thyristor 311 (Silicon-Controlled Rectifier - SCR) has its anode connected to the node 305 of the circuit 301B and its cathode connected to the node 307 of the circuit 30IB.

[0075] The circuit 301B illustrated in [Fig.3B] is for example intended to replace the circuit 201B of the converter 200B of [Fig.2B]. The node 305 of the circuit 301B, analogous to the node 205 of the circuit 20IB, is then for example connected to the node 107 of the rectifier bridge 101, while the node 307 of the circuit 301B, analogous to the node 207 of the circuit 201B, is for example connected to the terminal 127 of the capacitor 125.

[0076] The thyristor 311 is for example switched between on and off states in a manner similar to what was previously described for the electromechanical relay 209 of the circuit 201B of [Fig.2B]. More precisely, the thyristor 311 is for example maintained in a off state during the converter power-up phase, in order to force the flow of current in the thermistor 303. Once the capacitor 125 is charged, that is to say in steady state, the thyristor 311 is then switched to an on state, for example by applying a current pulse to its trigger G. The The thyristor then allows current to pass in only one direction, namely from its anode to its cathode.

[0077] In the on state, thyristor 311 has an impedance much lower than that of the off state. This impedance in the on state is however non-zero. As a result, thyristor 311 is the source of a voltage drop Vscr between terminals 305 and 307 of circuit 30IB.

[0078] Due to its association in parallel with the thyristor 311, the thermistor 303 undergoes a voltage drop Vntc substantially equal to the voltage drop Vscr, apart from the voltage drops in the conductors. In a manner similar to what was described previously in relation to [Fig.3A], the voltage drop Vntc is the cause of heating of the thermistor 303, so that the circuit 301B of [Fig.3B] has disadvantages similar to those of the circuit 301A of [Fig.3A] mentioned above.

[0079] [Fig.4A] is a diagram illustrating an embodiment of an inrush current limiting circuit 401A. The circuit 401A of [Fig.4A] includes elements in common with the circuit 301A of [Fig.3A]. These common elements will not be detailed again below.

[0080] The circuit 401A of [Fig.4A] differs from the circuit 301A of [Fig.3A] mainly in that the circuit 401A comprises another triac 403 connected, preferably connected, between the node 305 and the thermistor 303. More precisely, in the example shown, the triac 403 has its first anode A1 connected, preferably connected, to the node 305 and its second anode A2 connected, preferably connected, to a node 405. The trigger G of the triac 403 is for example connected to the node 405, so that the triac remains controlled in the on state as long as the converter comprising the circuit 401A is kept under voltage. The thermistor 303 is for example connected between the nodes 405 and 307 of the circuit 401A.

[0081] For example, triac 403 has a lower nominal operating current than triac 309. This advantageously makes it possible to provide a triac 403 with smaller dimensions than triac 309.

[0082] According to this embodiment, the circuit 401A thus comprises a parallel association, between the nodes 305 and 307: - a first branch comprising a first controlled rectification element, for example triac 309; and - a second branch comprising a resistor, for example the thermistor 303, associated in series with a second rectifier element, for example a controlled rectifier element, for example the triac 403.

[0083] For example, the triacs 309 and 403 may be part of separate components. The triacs 309 and 403 are for example integrated in separate housings. Alternatively, triacs 309 and 403 are part of the same component. Triacs 309 and 403 are for example integrated in the same package, the package comprising for example two chips each corresponding to one of triacs 309 and 403.

[0084] In the on state, the triac 403 has an impedance much lower than that of the blocked state. This impedance in the on state is however non-zero. As a result, the triac 403 is the origin of a voltage drop Vtriac2 between terminals 305 and 405 of the circuit 401 A.

[0085] According to a preferred embodiment, the triacs 309 and 403 have substantially equal on-state impedances. As a result, the voltage drop Vtriac2 caused by the triac 403 is substantially equal, apart from the voltage drops in the conductors, to the voltage drop Vtriac caused by the triac 309. Due to the series connection of the triac 403 and the thermistor 303, the voltage drop Vntc across the thermistor 303 is then substantially zero.

[0086] By way of example, the inventors have estimated that, for an input current I of the order of 6 A reaching the node 305, the triac 309 is traversed by a current Itriac of the order of 5.9 A, while the current Intc flowing through the triac 403 and the thermistor 303 is of the order of only 100 mA.

[0087] An advantage of the circuit 401A is that the current Intc flowing through the thermistor 303 is much lower than in the case of the circuit 301A. This results in less heating of the thermistor 303 in the circuit 401A, thus limiting the heating of the ambient air and providing a longer service life.

[0088] [Fig.4B] is a diagram illustrating another embodiment of an inrush current limiting circuit 401B. The circuit 401B of [Fig.4B] includes elements in common with the circuit 301B of [Fig.3B]. These common elements will not be detailed again below.

[0089] The circuit 401B of [Fig.4B] differs from the circuit 301B of [Fig.3B] mainly in that the circuit 401B comprises another thyristor 407 connected, preferably connected, between the node 305 and the thermistor 303. More precisely, in the example shown, the thyristor 407 has its anode connected, preferably connected, to the node 305 and its cathode connected, preferably connected, to a node 409. The gate G of the thyristor 407 is for example connected to the node 305, so that the thyristor remains controlled in the on state as long as the converter comprising the circuit 401B is kept under voltage. The thermistor 303 is for example connected between the nodes 409 and 307 of the circuit 401B.

[0090] For example, thyristor 407 has a lower nominal operating current than thyristor 311. This advantageously makes it possible to provide a thyristor 407 of smaller dimensions than thyristor 311.

[0091] According to this embodiment, the circuit 401B thus comprises a parallel association, between the nodes 305 and 307: - a first branch comprising a first controlled rectification element, for example thyristor 311; and - a second branch comprising a resistor, for example the thermistor 303, associated in series with a second rectifier element, for example a controlled rectifier element, for example the thyristor 407.

[0092] In the on state, thyristor 407 has an impedance much lower than that of the off state. This impedance in the on state is however non-zero. As a result, thyristor 407 is the source of a voltage drop Vscr2 between terminals 305 and 409 of circuit 40IB.

[0093] According to a preferred embodiment, the thyristors 311 and 407 have substantially equal on-state impedances. As a result, the voltage drop Vscr2 caused by the thyristor 407 is substantially equal, apart from the voltage drops in the conductors, to the voltage drop Vscr caused by the thyristor 311. Due to the series connection of the thyristor 407 and the thermistor 303, the voltage drop Vntc across the terminals of the thermistor 303 is then substantially zero.

[0094] In a manner similar to what was previously described in relation to [Fig.4A], the current flowing in the thyristor 407 and in the thermistor 303 is thus greatly reduced, so that the circuit 401B of [Fig.4B] has advantages similar to those of the circuit 401A of [Fig.4A] mentioned above.

[0095] [Fig.5A] is a diagram illustrating a circuit 501A. The circuit 501A corresponds for example to an alternative embodiment of the circuit 401A of [Fig.4A]. In this alternative, the triac 403 is replaced by an antiparallel association of two diodes 503 and 505 between the nodes 305 and 405. In other words, the diodes 503 and 505 are associated in parallel and mounted head to tail between the nodes 305 and 405 of the circuit 501A. In other words, the diodes 503 and 505 are in parallel and interconnected by opposite electrodes. More specifically, in the example shown, diode 503 has its anode connected to node 305 and its cathode connected to node 405 while diode 505 has its anode connected to node 405 and its cathode connected to node 305. In circuit 501A of [Fig.5A], diodes 503 and 505 correspond to two non-controlled rectifier elements in antiparallel.

[0096] The antiparallel association of the diodes 503 and 505 preferably has an impedance substantially equal to that of the triac 309 so that it is suitable for producing, between the nodes 305 and 405, a voltage drop Vdiode substantially equal to the voltage drop Vtriac between the nodes 305 and 307. The variant embodiment illustrated in [Fig.5A] thus has advantages similar to those described in relation to [Fig.4A].

[0097] [Fig.5B] is a diagram illustrating a circuit 501B. Circuit 501B corresponds for example to an alternative embodiment of circuit 401B of [Fig.4B]. In this alternative, thyristor 407 is replaced by a diode 507. Diode 507 is for example connected between nodes 305 and 409 of circuit 501B. More precisely, in the example shown, diode 507 has its anode connected to node 305 and its cathode connected to node 409. In circuit 501B of [Fig.5B], diode 507 constitutes an uncontrolled rectification element.

[0098] The diode 507 preferably has an impedance substantially equal to that of the thyristor 311 so that it is suitable for producing, between the nodes 305 and 409, a voltage drop Vdiode substantially equal to the voltage drop Vscr between the nodes 305 and 307. The embodiment variant illustrated in [Fig.5B] thus has advantages similar to those described in relation to [Fig.4B].

[0099] Although this has not been shown, it could be provided to replace the thyristor 311 of the circuits 401B and 501B of FIGS. 4B and 5B with a triac, for example the triac 309 of the circuits 401A and 501A of FIGS. 4A and 5A. It could also be provided to replace the thyristor 407 of the circuit 401B of [Fig. 4B] with a triac, for example similar to the triac 403 of [Fig. 4A]. In these two cases, advantages similar to those described previously in relation to FIGS. 4B and 5B would be obtained.

[0100] [Fig.6A] is a diagram illustrating one embodiment of a 600A voltage converter. [Fig.6A] more specifically represents another example of implementation of the inrush current limiting circuit 401A of [Fig.4A].

[0101] In the example shown, the voltage converter 600A comprises a rectifier bridge 601 of mixed type, that is to say comprising uncontrolled rectifier elements and controlled rectifier elements. The rectifier bridge 601 is more precisely a symmetrical mixed bridge having two input nodes 603, 605 and two output nodes 607, 609. In the example shown, the rectifier bridge 601 comprises: - a first diode 611, the anode of which is connected to node 609 and the cathode of which is connected to node 603; - a second diode 613, the anode of which is connected to node 609 and the cathode of which is connected to node 605; - a first inductor 615, one terminal of which is connected to node 603 and the other terminal of which is connected to an intermediate node 617; - a second inductor 619, one terminal of which is connected to node 605 and the other terminal of which is connected to another intermediate node 621; - a third diode 623, the anode of which is connected to node 617 and the cathode of which is connected to node 607; - a fourth diode 625, the anode of which is connected to node 621 and the cathode of which is connected to node 607; - a first transistor 627, for example of the N-channel metal-oxide-semiconductor (MOS) type, the source of which is connected to node 609 and the drain of which is connected to node 617; and - a second transistor 629, for example of the N-channel MOS type, the source of which is connected to node 609 and the drain of which is connected to node 621.

[0102] The rectifier bridge 601 further comprises a capacitor, for example a chemical capacitor 631, for example connected between the output nodes 607 and 609 of the rectifier bridge 601. The capacitor 631 is for example intended to smooth the rectified voltage at the output of the bridge 601.

[0103] Node 609 is for example brought to a reference potential, ground in the example shown.

[0104] A load 633 (L) to be supplied is for example connected between terminals 607 and 609 of the rectifier bridge 601. The load 633 receives a rectified and smoothed supply voltage at the output of the rectifier bridge 601.

[0105] In the example shown, the bridge 601 is powered by an alternating voltage source 635. The source 635 comprises, for example, a terminal 637 connected to the input node 603 of the rectifier bridge 601 via the inrush current limiter circuit 401A previously described in relation to [Fig. 4A]. In this case, the node 305 of the circuit 401A is, for example, connected to the terminal 637 and the node 307 of the circuit 401A is, for example, connected to the node 603.

[0106] The converter 600A, for example the rectifier bridge 601, may comprise other components or circuits not shown in [Fig.6A]. The bridge 601 may in particular comprise a protection circuit against possible overvoltages (not shown).

[0107] The rectifier bridge 601 is an example of a controlled bridge of the pulse-width modulation (PWM) type for regulating the direct current supply as a function of the load 633. The transistors 627 and 629 of the bridge 601, equivalent here to switches, are for example switched between open and closed states at a frequency higher than that of the alternating supply voltage of the converter 600A. For example, the switching frequency of the transistors 627 and 629 is of the order of tens of kilohertz. The transistors 627 and 629 are switched to the on state during respectively positive and negative alternations of the alternating supply voltage of the converter 600A.

[0108] When transistor 627, 629 is in the on state (equivalent to a closed switch), energy is temporarily stored in the corresponding inductor 615, 619. When transistor 627, 629 is switched to the off state (equivalent to an open switch), the energy stored in inductor 615, 619 is then restored and allows to charge, via the corresponding diode 623, 625, the capacitor 631. Each diode 611, 613 of the bridge 601 plays here a role of freewheel diode, by allowing the circulation of the current in the corresponding inductance 615, 619 when the associated transistor 627, 629 is in the blocked state (open switch).

[0109] The converter 600A, comprising the rectifier bridge 601 and the inrush current limiting circuit 401A, has in particular improved energy efficiency and increased reliability compared to the converter 100 of [Fig.l] and compared to the converters 200A and 200B of FIGS. 2A and 2B respectively comprising the circuits 201A and 201B or 301A and 301B.

[0110] [Fig.6B] is a diagram illustrating another embodiment of a voltage converter 600B. The converter 600B of [Fig.6B] comprises elements in common with the converter 600A of [Fig.6A]. These common elements will not be described again below.

[0111] The converter 600B of [Fig.6B] differs from the converter 600A of [Fig.6A] mainly in that the converter 600B does not include the circuit 401A on the AC side, but does include the circuit 401B of [Fig.4B] on the DC side. More specifically, in the example shown, the circuit 401B is connected between the node 607 of the rectifier bridge 601 and a node 641. In this case, the node 305 of the circuit 401B is for example connected to the node 607 and the node 307 of the circuit 401B is for example connected to the node 641.

[0112] In the example shown, the chemical capacitor 631 and the load 633 (L) each have one terminal connected to the node 641 and another terminal connected to the node 609 for applying the reference potential.

[0113] The 600B converter has similar advantages to the 600A converter. In particular, the 600B converter has improved energy efficiency and increased reliability compared to existing converters.

[0114] Another advantage of the 600B converter is that the 401B circuit only conducts when the transistor 627 or 629 is in the open state. This results in even lower conduction losses than in the 401A circuit of the 600A converter, where the 401A circuit conducts continuously.

[0115] [Fig.7] represents a device 700 comprising a voltage converter, for example the 600A converter previously described in relation to [Fig.6A].

[0116] The device 700 is, in the example shown, a television screen, or television. The provision of the voltage converter 600A allows the television 700 to have reduced electrical consumption as well as lower heat dissipation than those of a television which would include in particular the converter 200A ([Fig.2A]) comprising the circuit 201A or 301A, or the converter 200B ([Fig.2B]) comprising the 201B or 30IB circuit. This also increases the reliability and longevity of the 700 TV.

[0117] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. In particular, converters 600A and 600B of FIGS. 6A and 6B may respectively implement the embodiments of circuits 501A and 501B discussed in connection with FIGS. 5A and 5B.

[0118] Finally, the practical implementation of the embodiments and variants described is within the reach of the person skilled in the art from the functional indications given above. In particular, the dimensioning of the rectification elements, in particular the triac 403, the thyristor 407 and the diodes 503, 505 and 507, is within the reach of the person skilled in the art.

[0119] Furthermore, although an example of application of the described embodiments to a television set has been explained in relation to [Fig. 7], the described embodiments can be transposed to other types of devices comprising at least one AC-DC converter, for example of the type of converters 200A, 200B, 600A and 600B of FIGS. 2A, 2B, 6A and 6B, respectively.

[0120] The person skilled in the art is also capable of integrating the circuits 401A and 501A of FIGS. 4A and 5A or the circuits 401B and 501B of FIGS. 4B and 5B in voltage converters having an architecture and / or rectification elements different from those described. In particular, the embodiments are not limited to the examples of rectifier bridges 101 and 601 described.

Claims

Claims

1. Voltage converter (200A; 200B; 600A; 600B) comprising a circuit (401A; 501A; 401B; 501B) comprising a parallel association, between first (305) and second (307) nodes: - of a first branch comprising a controlled rectification element (309; 311) having a first impedance; and - of a second branch comprising a resistor (303) associated in series with a triac (403) having a second impedance substantially equal to the first impedance, in which a trigger (G) of the triac (403) is connected, preferably connected, to a second anode (A2) of the triac.

2. A converter according to claim 1, wherein said controlled rectification element (309) is another triac.

3. A converter according to claim 1, wherein said controlled rectification element (311) is a thyristor.

4. Converter according to claim 2, in which the triacs (403, 309) are integrated in the same housing.

5. A converter according to any one of claims 1 to 4, wherein the resistor (303) is a negative temperature coefficient thermistor for dissipating inrush currents.

6. Converter according to any one of claims 1 to 5, further comprising: - a rectifier bridge (101; 601); and - a capacitor (125; 631).

7. Device (700) comprising a converter (600A; 600B) according to any one of claims 1 to 6.

Images