Voltage converter

Abstract

The present disclosure relates to a voltage converter, including a circuit formed by a parallel combination of a first branch and a second branch connected between a first node and a second node. The first branch includes a first controlled rectifying element having a first impedance. The second branch includes a resistor in series combination with a second rectifying element having a second impedance substantially equal to the first impedance. For example, the second rectifying element may be a triac, the gate of which is coupled to receive a signal from an intermediate node in the series combination of the second branch. Alternatively, the second rectifying element may be a thyristor, the gate of which is coupled to receive a signal at the anode of the thyristor.

Description

[0001] Priority Claim

[0002] This application claims the priority of French Patent Application No. 2013664, filed on December 18, 2020, the content of which is incorporated herein by reference in its entirety to the maximum extent permitted by law. Technical Field

[0003] The present disclosure generally relates to electronic devices, and more particularly to rectifier-type voltage converters or AC / DC converters that can output a rectified voltage, such as substantially DC, from an AC voltage source. Background Art

[0004] Many AC / DC converters are known, and they typically include rectifying elements (controllable or uncontrollable) assembled as a rectifier bridge and at least one capacitor for filtering or smoothing the rectified voltage. Such converters are particularly present in switching mode power supplies commonly found in televisions, central units of desktop computers, lamps, etc. When a device including such a converter is powered on, the filter capacitor element causes a strong current inrush due to its charge. This current inrush disturbs the power network and damages the converter elements as well as the components or circuits of the devices coupled thereto.

[0005] To overcome this problem, certain AC / DC converters include a surge current limiting circuit. However, once the current has been established, the surge current limiting circuit causes undesirable power consumption and heating.

[0006] There is a need in the art to address all or some of the drawbacks of known voltage converters. Summary of the Invention

[0007] Embodiments of the present disclosure improve the power efficiency of known voltage converters. Embodiments of the present disclosure further increase the reliability of the voltage converter.

[0008] An embodiment of a voltage converter includes a circuit that includes a parallel combination between a first node and a second node, the series combination including: a first branch including a first controlled rectifying element having a first impedance; and a second branch including a resistor in series combination with one or more second rectifying elements, the second impedance of the second rectifying element being substantially equal to the first impedance.

[0009] According to one embodiment, the first controlled rectifying element is a first triac.

[0010] According to one embodiment, the first controlled rectifying element is a first thyristor.

[0011] According to one embodiment, the second branch includes only one second rectifying element.

[0012] According to one embodiment, the second rectifying element is controlled.

[0013] According to one embodiment, the second rectifying element is a second triac.

[0014] According to one embodiment, the gate of the second triac is coupled (preferably connected) to the second anode of the second triac.

[0015] According to one embodiment, the first and second triacs are integrated in the same package.

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

[0017] According to one embodiment, the gate of the second thyristor is coupled (preferably connected) to the anode of the second thyristor.

[0018] According to one embodiment, the second rectifying element is a diode.

[0019] According to one embodiment, a resistor is in series with the antiparallel combination of the first and second diodes, and the antiparallel combination of the first and second diodes has a second impedance.

[0020] According to one embodiment, the resistor is configured to consume inrush current.

[0021] According to one embodiment, the resistor is a thermistor with a negative temperature coefficient.

[0022] According to one embodiment, the converter further includes: a rectifier bridge; and a capacitor.

[0023] One embodiment provides an apparatus including the above converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other features and advantages will be described in detail with reference to the accompanying drawings in the description of specific embodiments given by way of example and not limitation, in which:

[0025] Figure 1 is a diagram showing an example of a voltage converter.

[0026] Figure 2A is a diagram showing another example of a voltage converter including a surge current limiting circuit.

[0027] Figure 2B is a diagram showing yet another example of a voltage converter including a surge current limiting circuit.

[0028] Figure 3AIt is a diagram showing an example of a surge current limiting circuit.

[0029] Figure 3B It is a diagram showing another example of a surge current limiting circuit.

[0030] Figure 4A It is a diagram showing an embodiment of a surge current limiting circuit;

[0031] Figure 4B It is a diagram showing another embodiment of a surge current limiting circuit;

[0032] Figure 5A It is a diagram showing Figure 4A an alternative embodiment of the circuit of;

[0033] Figure 5B It is a diagram showing Figure 4B an alternative embodiment of the circuit of;

[0034] Figure 6A It is a diagram showing an embodiment of a voltage converter;

[0035] Figure 6B It is a diagram showing another embodiment of a voltage converter; and

[0036] Figure 7 It shows a device including a voltage converter. Detailed Description

[0037] The same features are designated by the same reference numerals in different drawings. In particular, structural and / or functional features common to the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.

[0038] For clarity, only the steps and elements useful for understanding the embodiments described herein are detailed and described. In particular, the possible applications of the voltage converter are not detailed, and the described embodiments are compatible with the usual applications of implementing a voltage converter.

[0039] Unless otherwise stated, when referring to two elements connected together, this means a direct connection without any intermediate elements other than a conductor, and when referring to two elements coupled together, this means that the two elements may be connected or they may be coupled through one or more other elements.

[0040] In the following disclosure, unless otherwise stated, when referring to absolute position determiners, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or relative position determiners, such as the terms "above", "below", "upper", "lower", etc., or direction determiners, such as "horizontal", "vertical", etc., reference is made to the directions shown in the figures.

[0041] Unless otherwise specified, the terms "about", "approximately", "substantially" and "circa" mean within 10%, preferably within 5%.

[0042] Figure 1 is a diagram showing an example of the voltage converter 100.

[0043] In the example shown, the voltage converter 100 includes a rectifier bridge 101. The rectifier bridge 101 receives the AC voltage Vin as input and outputs a rectified voltage Vout.

[0044] The input voltage Vin is, for example, a sinusoidal voltage. The voltage Vin is, for example, a single-phase supply voltage derived from a power distribution network (not shown), such as a main line. For example, the root mean square (rms) value of the input voltage Vin is approximately 230V and the frequency is approximately 50Hz, or the rms value is approximately 110V and the frequency is approximately 60Hz.

[0045] In Figure 1 the example shown, 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 available, for example, 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 brought, for example, to a reference potential, such as ground.

[0046] In the example shown, the rectifier bridge 101 of the converter 100 is of the uncontrolled full-wave type. In this example, the rectifier bridge 101 is more specifically a diode bridge, including: a first diode 111, whose anode is connected to the node 103 and whose cathode is connected to the node 107; a second diode 113, whose anode is connected to the node 109 and whose cathode is connected to the node 103; a third diode 115, whose anode is connected to the node 105 and whose cathode is connected to the node 107; and a fourth diode 117, whose anode is connected to the node 109 and whose cathode is connected to the node 105.

[0047] In the example shown, the first node 103 of the rectifier bridge 101 is coupled to the main line via a switch 119. For example, the switch 119 more specifically includes a terminal 121 connected to the phase conductor of the main line and another terminal 123 connected to the node 103 of the bridge 101. In this example, the second node 105 of the rectifier bridge 101 is connected to the main line, for example, to the neutral conductor of the main line. The switch 119 is capable of powering the converter 100, that is, applying the voltage Vin (within the voltage drop in the conductors) conveyed by the main line between the nodes 103 and 105 of the bridge 101.

[0048] In the illustrated example, the converter 100 further includes a capacitive element 125, such as a capacitor. In this example, the capacitor 125 is connected between nodes 107 and 109 of the rectifier bridge 101. For example, the capacitor 125 more specifically includes a terminal 127 connected to node 107 and another terminal 129 connected to node 109. The capacitor 125 is used, for example, configured to filter or smooth the voltage Vout. For example, the output voltage Vout is then substantially a DC voltage.

[0049] For example, the voltage Vout can power a load 131 (L), as Figure 1 shown by the dashed line in, in parallel combination with the capacitor 125. The load 131 is, for example, coupled or connected to nodes 107 and 109 of the rectifier bridge 101 of the converter 100.

[0050] When the converter 100 is powered on, for example when the switch 119 is switched from the off state to the on state, the capacitor 125 generates a transient overcurrent commonly referred to as inrush current or current surge. For example, an inrush current having an intensity of five to twenty times the rated current particularly damages the diodes 111, 113, 115, and 117 of the rectifier bridge 101 each time the converter is powered on. This adversely affects the reliability of the converter 100. The inrush current can also deteriorate the capacitor 125, resulting in non-compliance with the flicker standard and interference with the power supply network.

[0051] Figure 2A is a diagram showing another example of a voltage converter 200A. Figure 2A The voltage converter 200A includes elements common to Figure 1 the voltage converter 100. These common elements will not be described in detail hereinafter.

[0052] Figure 2A The converter 200A differs from Figure 1 the converter 100 mainly in that the converter 200A further includes a surge current limiting circuit 201A in addition to the rectifier bridge 101.

[0053] In the illustrated example, the circuit 201A is located at the input of the converter 200A, on the side of the AC input Vin. In this example, the circuit 201A is more specifically connected between the first node 103 of the rectifier bridge 101 and the terminal 123 of the switch 119.

[0054] In the illustrated example, the circuit 210A includes a resistor 203. For example, the resistor 203 of the circuit 201A includes 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.

[0055] In the example shown, the circuit 201A further includes a switch 209 combined in parallel with a resistor 203, for example connected between terminals 205 and 207 of the resistor 203. In the off position, the switch 209 forces current to flow through the resistor 203.

[0056] In the on position, the switch 209 connects terminal 205 to terminal 207, which shorts the resistor 203. Then the current mainly flows through the switch 209.

[0057] As an example, the switch 209 is a relay, such as a single-pole electromechanical relay, Figure 2A only its power contacts of which are shown.

[0058] When the converter 200A is powered on, for example when the switch 119 is switched to the on position, the relay 209 remains in the off position. Then the current flows through the resistor 203. The resistor 203 causes a voltage drop between its terminals 205 and 207. This enables limiting the inrush current during the charging of the capacitor 125 when powered on.

[0059] Once the capacitor 125 is charged, for example after a delay after the converter 200A is powered on, the relay 209 is switched to the on position. The current then mainly flows through the relay 209. This enables the rectifier bridge 101 of the converter 200A to conduct a nominal current adapted to the application.

[0060] Figure 2B is a diagram showing yet another example of a voltage converter 200B. Figure 2B The voltage converter 200B of Figure 1 includes elements common to the voltage converter 100 of

[0061] Figure 2B The converter 200B of Figure 1 differs from the converter 100 of

[0062] 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 specifically connected between the third node 107 of the rectifier bridge and the terminal 127 of the capacitor 125. Figure 2A The circuit 201B is, for example, the same as the circuit 201A of the converter 200B of

[0063] The operation of the circuit 201B of the converter 200B is similar to the operation of the circuit 201A of the converter 200A, as described above with respect toFigure 2A as described

[0064] The disadvantages of circuits 201A and 201B mainly stem from the presence of relay 209. Relay 209 can indeed experience wear, for example, due to the corrosion of its power contacts during each load switch. This adversely affects the reliability of circuits 201A and 201B that form part of converters 200A and 200B.

[0065] Relay 209 also emits noise during each switch, typically a clicking sound. Such a clicking sound proves to be unpleasant for the user and may further interfere with a sound recognition system located near relay 209, such as one integrated into a device including converter 200A or 200B.

[0066] Figure 3A is a diagram showing an example of a surge current limiting circuit 301A.

[0067] Surge current limiting circuit 301A includes resistor 303. In the example shown, resistor 303 is a thermistor, more specifically a negative temperature coefficient (NTC) thermistor. In this example, thermistor 303 is connected between nodes 305 and 307 of circuit 301A.

[0068] Circuit 301A also includes, for example, a triac 309 in parallel combination with thermistor 303. In the example shown, triac 309 more specifically has its first anode (A1) connected to node 305 of circuit 301A and its second anode (A2) connected to node 307 of circuit 301A. The first anode of the triac represents the anode on the side of the gate (G) of the triac, while the second anode of the triac represents the anode opposite the first anode.

[0069] For example, Figure 3A the circuit 301A shown in Figure 2A is configured to replace circuit 201A of converter 200A. Node 305 of circuit 301A, similar to node 205 of circuit 201A, is then connected, for example, to terminal 123 of switch 119, while node 307 of circuit 301A, similar to node 207 of circuit 201A, is connected, for example, to node 103 of rectifier bridge 101.

[0070] For example, similar to that previously described for Figure 2AAs described for the electromechanical relay 209 of circuit 201A, triac 309 switches between the conducting state and the off state. More specifically, for example, during the power-up phase of the converter, triac 309 remains in the off state to force current to flow through thermistor 303. Once capacitor 125 has been charged, i.e., is in the steady state, triac 309 switches to the conducting state, for example, by applying a current pulse to its gate G. Triac 309 then conducts current in both directions, i.e., from its first anode A1 to its second anode A2 and from its second anode A2 to its first anode A1.

[0071] In the conducting state, the impedance of triac 309 is much lower than its impedance in the off state. However, this on-state impedance is not zero. Therefore, triac 309 causes a voltage drop Vtriac between terminals 305 and 307 of circuit 301A. For example, the voltage drop Vtriac is on the order of 1V.

[0072] Due to its parallel combination with triac 309, thermistor 303 is subject to voltage drop Vntc. In this case, voltage drop Vntc is substantially equal to voltage drop Vtriac, within the voltage drop range in the conductor.

[0073] When triac 309 is in the conducting state, the voltage drop Vntc present across thermistor 303 causes current Intc to flow through thermistor 303. For example, the inventors estimate that for an input current I of on the order of 6A arriving at node 305, for a current Intc of on the order of 2A flowing through thermistor 303, triac 309 conducts only a current Itriac of on the order of 4A.

[0074] Current Intc is responsible for heating thermistor 303 by the Joule effect. This heating causes a significant reduction in the power efficiency of the converter including circuit 301A and causes premature wear of thermistor 303. In the example shown, where thermistor 303 has a negative temperature coefficient, the heating of thermistor 303 also causes a reduction in resistance, thus amplifying this phenomenon. This reduction in resistance does indeed facilitate a more efficient flow of current Intc through thermistor 303, thus facilitating additional heating, and so on.

[0075] Figure 3B FIG. is a diagram showing another example of a surge current limiting circuit 301B. Figure 3B Circuit 301B of... includes elements shared with Figure 3A Circuit 301A of... These shared elements will not be described further below.

[0076] Figure 3B Circuit 301B of... is shared withFigure 3A The circuit 301A differs mainly in that the circuit 301B includes a thyristor 311 instead of a triac 309. In the example shown, the thyristor 311 (silicon controlled rectifier (SCR)) has an anode connected to node 305 of the circuit 301B and a cathode connected to node 307 of the circuit 301B.

[0077] For example, Figure 3B the circuit 301B shown is configured to replace Figure 2B the circuit 201B of the converter 200B. Node 305 of the circuit 301B, similar to node 205 of the circuit 201B, is then connected, for example, to node 107 of the rectifier bridge 101, while node 307 of the circuit 301B, similar to node 207 of the circuit 201B, is connected, for example, to terminal 127 of the capacitor 125.

[0078] For example, similar to that previously described for Figure 2B the electromechanical relay 209 of the circuit 201B, the thyristor 311 switches between the on and off states. More specifically, during the power - on phase of the converter, the thyristor 311 remains in the off state, for example, to force current to flow through the thermistor 303. Once the capacitor 125 has been charged, i.e., in the steady state, the thyristor 311 is switched to the on state, for example, by applying a current pulse to its gate G. The thyristor then conducts current in a single direction, i.e., from its anode to its cathode.

[0079] In the on state, the impedance of the thyristor 311 is much smaller than that in the off state. However, this on - state impedance is not zero. Therefore, the thyristor 311 causes a voltage drop Vscr between terminals 305 and 307 of the circuit 31B.

[0080] Due to its parallel combination with the thyristor 311, the thermistor 303 undergoes a voltage drop Vntc that is substantially equal to the voltage drop Vscr, within the range of voltage drops in the conductor. Similar to that previously described for Figure 3A , the voltage Vntc causes heating of the thermistor 303, thus Figure 3B the circuit 301B has similar drawbacks to those of the Figure 3A circuit 301A described above.

[0081] Figure 4A is a diagram showing an embodiment of a surge current limiting circuit 401A. Figure 4A The circuit 401A includes elements shared with the Figure 3A circuit 301A. These shared elements will not be described further below.

[0082] Figure 4A The circuit 401A of Figure 3AThe difference in circuit 301A mainly lies in that circuit 401A includes another triac element 403 coupled (preferably connected) between node 305 and thermistor 303. More specifically, in the illustrated example, the triac element 403 has a first anode A1 coupled (preferably connected) to node 305 and a second anode A2 coupled (preferably connected) to node 405. For example, the gate G of the triac element 403 is connected to node 405 such that as long as the converter including circuit 401A remains powered on, the triac element remains controlled in the conducting state. The thermistor 303 is connected, for example, between nodes 405 and 307 of circuit 401A.

[0083] As an example, the triac element 403 exhibits a rated operating current smaller than that of the triac element 309. This advantageously enables the provision of a triac element 403 with a smaller size than the triac element 309.

[0084] According to this embodiment, circuit 401A thus includes a parallel combination between nodes 305 and 307, which includes: a first branch including a first controlled rectifying element, such as a triac element 309; and a second branch including a resistor, such as a thermistor 303, in series combination with a second rectifying element (e.g., a second controlled rectifying element, such as a triac element 403).

[0085] For example, the triac elements 309 and 403 can be part of separate components. For example, the triac elements 309 and 403 are integrated in a separate package. Alternatively, the triac elements 309 and 403 are part of the same component. For example, the triac elements 309 and 403 are integrated in the same package, which contains, for example, two chips, each corresponding to one of the triac elements 309 and 403.

[0086] In the conducting state, the impedance of the triac element 403 is much lower than that in the off state. However, this on-state impedance is not zero. Therefore, the triac element 403 causes a voltage drop Vtriac2 between terminals 305 and 405 of circuit 401A.

[0087] According to a preferred embodiment, the triacs 309 and 403 have substantially equal on-resistances. Thus, the voltage drop Vtriac2 caused by the triac 403 is substantially equal to the voltage drop Vtriac caused by the triac 309 within the voltage drop range in the conductor. Due to the series combination of the triac 403 and the thermistor 303, the voltage drop Vntc across the thermistor 303 is then substantially zero.

[0088] For example, the inventors have estimated that for an input current I of the order of 6 A arriving at node 305, the triac 309 conducts a current Itriac of the order of 5.9 A, while the current Intc flowing through the triac 403 and the thermistor 303 is only of the order of 100 mA.

[0089] 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 extending the service life.

[0090] Figure 4B is a diagram showing another embodiment of the surge current limiting circuit 401B. Figure 4B The circuit 401B includes elements common to Figure 3B the circuit 301B. These common elements will not be described further below.

[0091] Figure 4B The circuit 401B differs from Figure 3B the circuit 301B mainly in that the circuit 401B includes another thyristor 407 which is coupled (preferably connected) between the node 305 and the thermistor 303. More specifically, in the example shown, the thyristor 407 has an anode coupled (preferably connected) to the node 305 and a cathode coupled (preferably connected) to the node 409. The gate G of the thyristor 407 is connected to the node 305 such that, for example, the thyristor remains controlled to the conducting state as long as the converter including the circuit 401B remains powered on. The thermistor 303 is connected, for example, between the nodes 409 and 307 of the circuit 401B.

[0092] For example, the thyristor 407 has a nominal operating current less than the rated operating current of the thyristor 311. This advantageously enables a thyristor 407 to be provided which is smaller in size than the thyristor 311.

[0093] According to this embodiment, the circuit 401B thus includes a parallel combination between nodes 305 and 307, which parallel combination includes: a first branch including a first controlled rectifying element, such as thyristor 311; and a second branch including a resistor, such as a thermistor 303, in series combination with a second rectifying element (e.g., a controlled rectifying element, such as thyristor 407).

[0094] In the conducting state, the thyristor 407 has an impedance much smaller than that in the off state. However, this on-state impedance is not zero. Thus, the thyristor 407 causes a voltage drop Vscr2 between terminals 305 and 409 of the circuit 401B.

[0095] According to a preferred embodiment, the thyristors 311 and 407 have substantially equal on-state impedances. Thus, the voltage drop Vscr2 caused by the thyristor 407 is substantially equal to the voltage drop Vscr caused by the thyristor 311 within the voltage drop range in the conductor. Due to the series combination of the thyristor 407 and the thermistor 303, the voltage drop Vntc across the thermistor 303 is then substantially zero.

[0096] Similar to that previously described with respect to Figure 4A the current flowing through the thyristor 407 and the thermistor 303 is thus greatly reduced, such that Figure 4B the circuit 401B has similar advantages to the circuit 401A described above Figure 4A .

[0097] Figure 5A FIG. is a diagram showing the circuit 501A. For example, the circuit 501A corresponds to Figure 4A an alternative embodiment of the circuit 401A. In this variant, the triac 403 is replaced by an antiparallel combination of two diodes 503 and 505 between nodes 305 and 405. In other words, the diodes 503 and 505 are combined in parallel and assembled head-to-tail between nodes 305 and 405 of the circuit 501A. In yet other words, the diodes 503 and 505 are parallel and interconnected by opposite electrodes. More specifically, in the example shown, the anode of the diode 503 is connected to node 305 and its cathode is connected to node 405, while the anode of the diode 505 is connected to node 405 and its cathode is connected to node 305. In Figure 5A the circuit 501A, the diodes 503 and 505 correspond to two non-controlled rectifying elements in antiparallel.

[0098] The antiparallel combination of the diodes 503 and 505 preferably has an impedance substantially equal to that of the triac 309, such that a voltage drop Vdiode substantially equal to the voltage drop Vtriac between nodes 305 and 307 can be generated between nodes 305 and 405. Thus,Figure 5A The alternative embodiments shown have advantages similar to those regarding Figure 4A those described.

[0099] Figure 5B is a diagram showing circuit 501B. For example, circuit 501B corresponds to Figure 4B an alternative embodiment of circuit 401B of Figure 5B In this variant, thyristor 407 is replaced by diode 507. Diode 507 is connected, for example, between nodes 305 and 409 of circuit 501B. More specifically, in the example shown, the anode of diode 507 is connected to node 305 and its cathode is connected to node 409. In Figure 5B circuit 501B of

[0100] Diode 507 has an impedance preferably substantially equal to that of thyristor 311, so that it can produce a voltage drop Vdiode between nodes 305 and 409 that is substantially equal to the voltage drop Vscr between nodes 305 and 307. Thus, Figure 5B the alternative embodiments shown have advantages similar to those regarding Figure 4B those described.

[0101] Although not shown, it is possible to provide a triac to replace Figure 4B and Figure 5B thyristor 311 of circuits 401B and 501B, for example, Figure 4A and Figure 5A triac 309 of circuits 401A and 501A. It is further possible to provide a triac, for example similar to Figure 4A triac 403, to replace Figure 4B thyristor 407 of circuit 401B. In both cases, advantages similar to those previously described regarding Figure 4B and 5B those described will be obtained.

[0102] Figure 6A is a diagram showing an embodiment of voltage converter 600A. Figure 6A More specifically shown is Figure 4A another embodiment of the inrush current limiting circuit 401A of

[0103] In the example shown, the voltage converter 600A includes a hybrid rectifier bridge 601, i.e., including uncontrolled rectifier elements and controlled rectifier elements. The rectifier bridge 601 is more specifically a symmetric hybrid bridge having two input nodes 603, 605 and two output nodes 607, 609. In the example shown, the rectifier bridge 601 includes: a first diode 611, whose anode is connected to node 609 and whose cathode is connected to node 603; a second diode 613, whose anode is connected to node 609 and whose cathode is connected to node 605; a first inductor 615, such as an inductor, one end of which is connected to node 603 and the other end of which is connected to an intermediate node 617; a second inductor 619, such as an inductor, one end of which is connected to node 605 and the other end of which is connected to another intermediate node 621; a third diode 623, whose anode is connected to node 617 and whose cathode is connected to node 607; a fourth diode 625, whose anode is connected to node 621 and whose cathode is connected to node 607; a first transistor 627, such as an N-channel metal oxide semiconductor (MOS) type, whose source is connected to node 609 and whose drain is connected to node 617; and a second transistor 629, such as an N-channel MOS type, whose source is connected to node 609 and whose drain is connected to node 621.

[0104] The rectifier bridge 601 further includes a capacitive element, such as a chemical capacitor 631, connected between the output nodes 607 and 609 of the rectifier bridge 601. The capacitor 631 is configured, for example, to smooth the rectified voltage at the output of the bridge 601.

[0105] For example, node 609 is brought to a reference potential, such as ground in the example shown.

[0106] The load 633 (L) to be powered is connected, for example, between the nodes 607 and 609 of the rectifier bridge 601. The load 633 receives a smoothed rectified supply voltage at the output of the rectifier bridge 601.

[0107] In the example shown, the bridge 601 is powered by an AC voltage source 635. For example, the power supply 635 includes a terminal 637, which is coupled to the input node 603 of the rectifier bridge 601 via the surge current limiting circuit 401A described previously with respect to Figure 4A In this case, the node 305 of the circuit 401A is connected to the terminal 637, for example, and the node 307 of the circuit 401A is connected to the node 603, for example.

[0108] The converter 600A having the rectifier bridge 601 may include Figure 6A other components or circuits not shown. The bridge 601 may particularly include a protection circuit (not shown) against possible overvoltages.

[0109] Rectifier bridge 601 is an example of a controlled bridge of the pulse width modulation (PWM) type that can adjust the DC current supply according to the load 633. The transistors 627 and 629 of the bridge 601, which are equivalent to switches here, switch between off and on, for example, at a frequency higher than the frequency of the AC power supply voltage of the converter 600A. For example, the switching frequency of the transistors 627 and 629 is on the order of ten kilohertz. The transistors 627 and 629 are switched to the on state during the positive and negative half-waves of the AC power supply voltage of the converter 600A, respectively.

[0110] When the transistors 627, 629 are in the on state (equivalent to a conducting switch), energy is temporarily stored in the corresponding inductors 615, 619. When the transistors 627, 629 are switched to the off state (equivalent to a non-conducting switch), the energy stored in the inductors 615, 619 is then released and can charge the capacitive element 631 through the corresponding diodes 623, 625. By allowing the current to flow through the corresponding inductors 615, 619 when the associated transistors 627, 629 are in the off state (non-conducting switch), each diode 611, 613 of the bridge 601 functions as a freewheeling diode.

[0111] Converter 600A including rectifier bridge 601 and surge current limiting circuit 401A is particularly improved in power efficiency and increased in reliability compared to Figure 1 converter 100 and compared to converters 200A and 200B that respectively include circuits 201A and 201B or 301A and 301B Figure 2A and Figure 2B respectively.

[0112] Figure 6B is a diagram showing another embodiment of voltage converter 600B. Figure 6B Converter 600B includes elements shared with Figure 6A converter 600A. These shared elements will not be described further below.

[0113] Figure 6B Converter 600B is mainly different from Figure 6A converter 600A in that converter 600B does not include the circuit 401A on the AC current side but includes the Figure 4B circuit 401B on the DC current side. More specifically, in the illustrated example, the circuit 401B is connected between the node 607 and the node 641 of the rectifier bridge 601. In this case, the node 305 of the circuit 401B is connected to the node 607, for example, and the node 307 of the circuit 401B is connected to the node 641, for example.

[0114] In the illustrated example, one end of the chemical capacitor 631 and the load 633(L) is connected to the node 641, and the other end is connected to the node 609 to which the reference potential is applied.

[0115] Converter 600B has advantages similar to those of converter 600A. Specifically, compared with existing converters, converter 600B has improved power efficiency and increased reliability.

[0116] Another advantage of converter 600B is that the circuit 401B conducts only when the transistors 627 or 629 are off. This results in even lower conduction losses in the circuit 401A of converter 600A, where the circuit 401A conducts continuously.

[0117] Figure 7 An apparatus 700 including a voltage converter is shown, such as the converter 600A previously described with respect to Figure 6A Description of the converter 600A.

[0118] In the illustrated example, the apparatus 700 is a television screen or a television set. The provision of the voltage converter 600A enables the television set 700 to have lower power consumption and less heat dissipation than television sets that particularly include the converter 200A ( Figure 2A ), where the converter 200A ( Figure 2A ) includes the circuit 201A or 301A, or the converter 200B ( Figure 2B ) includes the circuit 201B or 301B. This further enables the reliability and lifespan of the television set 700 to be improved.

[0119] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations can be combined, and other variations will occur to those skilled in the art. In particular, Figure 6A And 6B The converters 600A and 600B of Figure 5A And 5B Can respectively implement the embodiments of the circuits 501A and 501B discussed with respect to

[0120] Finally, based on the functional indications given above, the actual implementation of the described embodiments and variations is within the capabilities of those skilled in the art. In particular, the sizing of the rectifying elements, especially the triac 403, thyristor 407, and diodes 503, 505, and 507, is within the capabilities of those skilled in the art.

[0121] In addition, although examples of applying the embodiments to a television set have been described in connection with Figure 7 , the embodiments can be transferred to other types of devices including at least one AC / DC converter, for example, Figure 2A ,Figure 2B , Figure 6A and Figure 6B types of converters 200A, 200B, 600A, and 600B.

[0122] The Figure 4A and Figure 5A circuits 401A and 501A or Figure 4B and Figure 5B circuits 401B and 501B are described within the ability of those skilled in the art to integrate into a voltage converter having a different structure and / or rectifying element from these. In particular, the embodiments are not limited to the examples of rectifier bridges 101 and 601 described.

Claims

1. A voltage converter, comprising a circuit, the circuit including a parallel combination connected between a first node and a second node, the parallel combination comprising: a first branch including a controlled rectifying element having a first impedance; and a second branch including a resistor in series combination with a first triac having a second impedance substantially equal to the first impedance; wherein the first triac includes a first anode, a second anode serially coupled to the resistor at an intermediate node, and a gate configured to receive a first signal generated at the intermediate node.

2. The converter according to claim 1, wherein the controlled rectifying element is a thyristor.

3. The converter according to claim 1, wherein the controlled rectifying element is a second triac, the first anode of the second triac being connected to the first anode of the first triac, the second anode of the second triac being connected to the resistor, and the gate of the second triac being configured to receive a second signal.

4. The converter according to claim 3, wherein the first triac and the second triac are integrated in the same package.

5. The converter according to claim 1, wherein the first triac is the only rectifying circuit element present in the second branch.

6. The converter according to claim 1, wherein the second anode of the first triac is directly electrically connected to the intermediate node, and wherein the terminals of the resistor are directly electrically connected to the intermediate node, and wherein the gate of the first triac is directly electrically connected to the intermediate node.

7. The converter according to claim 1, wherein the resistor is a negative temperature coefficient (NTC) thermistor.

8. The converter according to claim 1, further comprising: a rectifier bridge; and a capacitor.

9. An apparatus comprising the converter according to claim 1.

10. A voltage converter, comprising a circuit, the circuit including a parallel combination connected between a first node and a second node, the parallel combination comprising: a first branch including a controlled rectifying element having a first impedance; and a second branch including a resistor in series combination with a first thyristor having a second impedance substantially equal to the first impedance; wherein the first thyristor includes an anode, a cathode serially coupled to the resistor at an intermediate node, and a gate configured to receive a first signal generated at the anode of the first thyristor.

11. The converter according to claim 10, wherein the controlled rectifying element is a triac.

12. The converter according to claim 10, wherein the controlled rectifying element is a second thyristor, the anode of the second thyristor is connected to the anode of the first thyristor, the cathode of the second thyristor is connected to the resistor, and the gate of the second thyristor is configured to receive a second signal.

13. The converter according to claim 12, wherein the first thyristor and the second thyristor are integrated in the same package.

14. The converter according to claim 10, wherein the first thyristor is the only rectifying circuit element present in the second branch.

15. The converter according to claim 10, wherein the cathode of the first thyristor is directly electrically connected to the intermediate node, and wherein the terminals of the resistor are directly electrically connected to the intermediate node, and wherein the gate of the first thyristor is directly electrically connected to the anode of the first thyristor.

16. The converter according to claim 10, wherein the resistor is a negative temperature coefficient (NTC) thermistor.

17. The converter according to claim 10, further comprising: a rectifier bridge; and a capacitor.

18. An apparatus comprising the converter according to claim 10.

19. A voltage converter comprising a circuit, the circuit comprising a parallel combination connected between a first node and a second node, the parallel combination comprising: a first branch comprising a controlled rectifying element having a first impedance; and a second branch comprising a resistor in series combination with an uncontrolled rectifying element having a second impedance substantially equal to the first impedance; wherein the uncontrolled rectifying element is an antiparallel combination of a first diode and a second diode.

20. The converter according to claim 19, wherein the controlled rectifying element is one of a triac or a thyristor.

21. The converter according to claim 19, wherein the antiparallel combination of the first diode and the second diode comprises: the anode of the first diode, being directly electrically connected to the cathode of the second diode; and the cathode of the first diode, being directly electrically connected to both the anode of the second diode and the resistor.

22. The converter according to claim 19, wherein the resistor is a negative temperature coefficient (NTC) thermistor.

23. The converter according to claim 19, further comprising: a rectifier bridge; and a capacitor.

24. An apparatus comprising the converter according to claim 19.

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