Voltage converter

Abstract

Embodiments of the present disclosure relate to a voltage converter. The voltage converter transfers an output voltage between a first and a second node. The voltage converter includes a capacitor coupled in series with a resistor between the first and the second node. The resistor is coupled in parallel with a bidirectional switch that receives a positive bias voltage referenced to the second node at its control terminal.

Description

[0001] Priority Claim

[0002] This application claims priority to French Patent Application No. 2012211, filed on November 26, 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 AC / DC converters. The present disclosure is generally applicable to any circuit using a rectifier bridge as an AC / DC converter. Background Art

[0004] Many AC / DC converter architectures based on controlled rectifying elements, such as thyristors (or SCRs, i.e., silicon controlled rectifiers), or uncontrolled rectifying elements, such as diodes assembled as a rectifier bridge, powered by an AC supply voltage and delivering a DC voltage are known.

[0005] It is generally desirable to limit the inrush current, i.e., the current peak that appears on each half-wave of the AC voltage, especially during the start-up phase, as long as the voltage across the capacitor at the output of the rectifier bridge has not reached a sufficient level.

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

[0007] One embodiment provides a voltage converter that transfers an output voltage between a first node and a second node. The voltage converter is or includes a capacitor coupled in series with a resistor between the first node and the second node. The resistor is coupled in parallel to a bidirectional switch that receives a positive bias voltage referenced to the second node at its control terminal.

[0008] According to one embodiment, the converter may include a voltage rectifier bridge.

[0009] According to one embodiment, a control current is injected into the control terminal, and for a first value of the control current, the switch blocks the flow of positive current from the first node to the second node. For a second value of the control current, the switch allows the flow of positive current from the first node to the second node.

[0010] According to one embodiment, the flow of negative current from the second node to the first node is independent of the control current.

[0011] According to one embodiment, the switch may be or include a diode whose cathode is coupled to the first node and whose anode is coupled to the second node.

[0012] According to one embodiment, the switch may be or include a thyristor having a cathode coupled to a second node and an anode coupled to a first node, the thyristor receiving a bias voltage on its gate and a control current being injected into the gate.

[0013] According to one embodiment, the switch may be or include a transient voltage suppressor circuit coupled between the anode of the thyristor and the gate of the thyristor.

[0014] According to one embodiment, the switch may be or include a first triac having a first anode coupled to the first node and a second anode coupled to the second node.

[0015] According to one embodiment, the switch may be or include a second triac coupled between the gate of the first triac and the second node, the second triac being controlled by a control current.

[0016] According to one embodiment, the first anode of the second triac is coupled to the second node and the second anode of the second triac is coupled to the gate of the first triac.

[0017] According to one embodiment, the switch may be or include a transient voltage suppressor circuit coupled between the gate of the first triac and the second node.

[0018] According to one embodiment, the transient voltage suppressor circuit may be a transient voltage suppression (transil) diode.

[0019] Also disclosed herein is a voltage converter including: a rectifier bridge having a first output and a second output directly electrically connected to the first node and the second node, wherein an input voltage is received between a first input and a second input of the rectifier bridge; a capacitor directly electrically connected between the first node and a third node; a resistor directly electrically connected between the third node and the second node; and a bidirectional switch directly electrically connected between the third node and the second node, the bidirectional switch having a control terminal, wherein the control terminal receives a control signal..

[0020] The bidirectional switch may include: a first triac having a first anode directly electrically connected to the third node and a second anode directly electrically connected to the second node, the first triac further having a gate directly electrically connected to a fourth node; and a second triac having a first anode directly electrically connected to the gate of the first triac and a second anode directly electrically connected to the second node, the second triac having a gate receiving the control signal.

[0021] The transient voltage suppressor circuit may be directly electrically connected between the fourth node and the second node.

[0022] The transient voltage suppressor circuit may be a transil diode.

[0023] The bidirectional switch may include: a diode having a cathode directly electrically connected to the third node and an anode directly electrically connected to the second node; and a thyristor having an anode directly electrically connected to the third node, a cathode directly electrically connected to the second node, and a gate directly electrically connected to the fourth node, wherein the gate receives a control signal.

[0024] The transient voltage suppressor circuit may be directly electrically connected between the third node and the fourth node.

[0025] The transient voltage suppressor circuit may be a transil diode. Description of the Drawings

[0026] 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, wherein:

[0027] Figure 1 An embodiment of the voltage converter disclosed herein is schematically shown;

[0028] Figure 2 An embodiment of the voltage converter disclosed herein is shown in more detail; and

[0029] Figure 3 Another embodiment of the voltage converter disclosed herein is shown in more detail. Detailed Description of the Invention

[0030] In the figures, the same features are denoted by the same reference numerals. Specifically, common structural and / or functional features in the various embodiments may have the same reference, and the same structure, dimensions, and material properties may be provided.

[0031] For clarity, the steps and elements that contribute to an understanding of the embodiments described herein have been described and illustrated in detail. Specifically, the various possible applications of the embodiments of the voltage converter have not been elaborated.

[0032] Unless otherwise specified, 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 may be connected through one or more other elements.

[0033] In the following disclosure, unless otherwise specified, when referring to absolute position qualifiers, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "higher", "lower", etc., or direction qualifiers, such as "horizontal", "vertical", etc., reference is made to the directions shown in the figures.

[0034] Unless otherwise specified, the expressions "about", "approximately", "substantially" and "in the order of" mean within 10%, preferably within 5%.

[0035] Figure 1 An embodiment of a voltage converter 10 is schematically shown.

[0036] The voltage converter 10 receives a voltage Vin as an input. In other words, the converter 10 includes two input nodes 12 and 14, and the voltage Vin is transferred between nodes 12 and 14. For example, the input nodes 12 and 14 are coupled across the terminals of an AC voltage source (not shown), which can be, for example, a power distribution system.

[0037] The converter 10 outputs an output voltage Vout. The voltage Vout is, for example, a DC voltage. The voltage Vout is transferred between two nodes 16 and 18. Node 18 corresponds to a reference potential, such as ground. The voltage Vout is referenced to the reference potential at node 18.

[0038] The converter 10 includes a circuit 20 that receives the voltage Vin and transfers the voltage Vout. The circuit 20 is coupled, preferably connected, to the input nodes 12 and 14 and the output nodes 16 and 18. The circuit 20 includes a rectifier bridge, the details of which are not shown Figure 1 herein.

[0039] The converter 10 includes a capacitor 22 and a resistor (R) 24 coupled in series between the output nodes 16 and 18. More specifically, one terminal of the capacitor 22 is coupled, preferably connected, to node 16. The capacitor is coupled, preferably connected, to node 26. One terminal of the resistor 24 is coupled, preferably connected, to node 26. The other terminal of the resistor 24 is coupled, preferably connected, to node 18.

[0040] The converter 10 further includes a circuit 28. One terminal of the circuit 28 is coupled, preferably connected, to node 26. The other terminal of the circuit 28 is coupled, preferably connected, to node 18. The circuit 28 includes a control input or terminal. The control input receives a control signal Comm. More specifically, a positive bias voltage referenced to the voltage at node 18, in other words, referenced to the same voltage as the output voltage (i.e., referenced to ground, for example), and the control input also receives a control current.

[0041] Circuit 28 corresponds to a bidirectional switch. In other words, current can flow in one direction or in the opposite direction through circuit 28. In other words, positive current can flow from node 26 to node 18, while negative current can flow from node 18 to node 26. At least one direction, namely the direction from node 26 to node 18 corresponding to positive current, can be controlled by the control signal Comm. Thus, preferably, for one or more first values of the control current, circuit 28 conducts positive current from node 26 to node 18, and for one or more second values of the control current blocks (i.e., prevents the flow of) negative current.

[0042] According to one embodiment, negative current will flow regardless of the value of the control signal Comm.

[0043] According to another embodiment, for a signal Comm having one of the (one or more) first values, negative current is conducted by circuit 28, and for a signal Comm having one of the (one or more) second values, negative current is blocked by circuit 28. In other words, the (one or more) first values enable current to flow in both directions, while the (one or more) second values prevent current from flowing in both directions.

[0044] When the converter starts operating, a current peak typically appears in the current flowing through capacitor 22. Such a current peak may cause damage to components. To limit such a current peak, it is necessary to pass the current through resistor 24 to attenuate the peak without attenuating the current outside the peak. Thus, circuit 28 blocks positive current from flowing from node 26 through the branch including circuit 28 to node 18, and ensures that the current flows through resistor 24. In other words, during a period that may include a current peak, i.e., when the converter starts up, the value of the control current is such that positive current is blocked between the input and output of circuit 28, and such that the positive current flows through the resistor.

[0045] When such a current peak appears at the startup of the converter, current flows from node 16 to node 18. Thus, it is usually not useful to block the negative current flowing through circuit 28.

[0046] Figure 2 An embodiment of the voltage converter 50 is shown in more detail. Converter 50 is Figure 1 an embodiment of converter 10. Thus, converter 50 includes capacitor 22, circuit 28, and circuit 20, coupled as associated Figure 1 described.

[0047] Circuit 20 includes a rectifier bridge. In Figure 2 the example, the rectifier bridge is a diode rectifier bridge. Thus, the rectifier bridge includes four diodes 52, 54, 56, and 58.

[0048] Diodes 52 and 56 are serially coupled between node 16 and node 18, i.e., between the output nodes, i.e., between the nodes to which the output voltage Vout is applied. More specifically, diode 52 is coupled between node 16 and node 60, and diode 56 is coupled between node 60 and node 18. In other words, the cathode of diode 52 is coupled, preferably connected, to node 16, and the anode of diode 52 is coupled, preferably connected, to node 60. Further, the cathode of diode 56 is coupled, preferably connected, to node 60, and the anode of diode 56 is coupled, preferably connected, to node 18.

[0049] Diodes 54 and 58 are serially coupled between node 16 and node 18, i.e., between the output nodes, i.e., between the nodes to which the output voltage Vout is applied. More specifically, diode 54 is coupled between node 16 and node 62, and diode 58 is coupled between node 62 and node 18. In other words, the cathode of diode 54 is coupled, preferably connected, to node 16, and the anode of diode 54 is coupled, preferably connected, to node 62. Further, the cathode of diode 58 is coupled, preferably connected, to node 62, and the anode of diode 58 is coupled, preferably connected, to node 18.

[0050] Thus, the rectifier bridge includes two branches coupled in parallel, each branch including two diodes serially coupled, diode 52 and 56 or diode 54 and 58. The diodes in the same branch are serially coupled such that the cathode of one of the two diodes is coupled, preferably connected, to the anode of the other diode.

[0051] As a variant, at least some of diodes 52, 54, 56, and 58 can be replaced by another electronic component capable of forming a rectifier bridge. For example, at least one of diodes 52, 54, 56, and 58, e.g., two of diodes 52, 54, 56, and 58, can be replaced by a controllable element, such as a thyristor or a transistor.

[0052] For example, circuit 20 includes inductors 64 and 66. Inductor 64 is, for example, coupled between node 60 and input node 12. Inductor 66 is, for example, coupled between node 62 and input node 14. More specifically, one terminal of inductor 64 is coupled, preferably connected, to node 60, and the other terminal of inductor 64 is coupled, preferably connected, to node 12. Similarly, one terminal of inductor 66 is coupled, preferably connected, to node 62 and the other terminal of inductor 66 is coupled, preferably connected, to node 14.

[0053] The circuit 28 includes a diode 68. The diode 68 is coupled between node 26 and node 18. The diode 68 is reversely coupled. In other words, the diode 68 is coupled to allow negative current to flow from node 18 to node 26. In other words, the cathode of the diode 68 is coupled, preferably connected, to node 26. The anode of the diode 68 is coupled, preferably connected, to node 18. The diode 68 is thus in parallel with the resistor 24.

[0054] The circuit 28 includes a thyristor 70. The thyristor 70 is coupled between node 26 and node 18. The thyristor 70 is coupled to allow positive current to flow from node 26 to node 18. In other words, the cathode of the thyristor 70 is coupled, preferably connected, to node 18. The anode of the thyristor 70 is coupled, preferably connected, to node 26. The thyristor 70 is thus coupled in parallel with the resistor 24. The thyristor 70 is thus coupled in parallel with the diode 68 and is connected end-to-end.

[0055] The thyristor 70 is, for example, a cathode-gate thyristor. The thyristor receives a voltage referenced to node 18 at its gate. The gate of the thyristor receives the bias voltage of the control signal Comm. The gate of the thyristor is thus biased by a positive voltage referenced to node 18. A control current is injected into the gate to determine the on or off state of the thyristor.

[0056] At the start of the converter, positive current flows from node 26 to node 18. At startup, the control current has a value capable of turning on the thyristor 70. In addition, the diode 68 does not conduct the current flowing from node 26 to node 18. The current thus flows through the resistor 24, which attenuates the current peak that appears at startup.

[0057] After startup, i.e., after the current peak generated at startup, the control current takes on a value that turns on the thyristor 70. Thus, during operation, i.e., during the steady state of the converter, depending on the direction of the current, the current flows at least partially, preferably mostly, through the diode 68 or the thyristor 70.

[0058] Preferably, circuit 28 includes a transient voltage suppressor TSV circuit 72. When the system is turned off, i.e., when the capacitor 22 discharges and the thyristor 70 is blocked (which means that the thyristor 70 does not receive a control signal corresponding to the conducting state), the circuit 72 can avoid damage that transient voltage or overvoltage may cause to the converter. For example, during an overvoltage caused by lightning, a strong current flows through the capacitor 22 and the resistor 24. Under the action of this current, the voltage across the terminals of the resistor 24 rises and reaches the threshold voltage of the circuit 72. Once this threshold voltage is reached, by triggering the thyristor 70 and making the thyristor enter the conducting state, the current flows from node 26 through the circuit 72 to node 18. The thyristor 70 shorts the resistor 24 by becoming conducting and stops the voltage from reaching the critical value of the converter. For example, the circuit 72 is a transil diode, such as a unidirectional transil diode. Preferably, the circuit 72 is coupled between node 26 and the gate of the thyristor 70. One terminal of the circuit 72 is, for example, coupled, preferably connected, to node 26 and the other terminal of the circuit 72 is, for example, coupled, preferably connected, to node 18.

[0059] Preferably, if the voltage across the thyristor 70 is, for example, greater than 50V, preferably greater than 100V, preferably greater than 200V, then the circuit 72 is configured to form a short circuit between the gate of the thyristor 70 and node 26. Thus, when the voltage across the thyristor 70 is greater than the selected threshold, the thyristor receives the voltage at node 26 at its gate and conducts, thereby allowing the peak current in the thyristor to dissipate while limiting the voltage affecting the circuit powered by the voltage Vout.

[0060] Figure 3 An embodiment of the voltage converter 80 is shown in more detail. The converter 80 is Figure 1 an embodiment of the converter 10. Thus, the converter 80 includes the capacitor 22, the circuit 28, and the circuit 20, coupled as described Figure 1 above. In Figure 3 the example of Figure 2 above, the circuit 20 includes the same components as the circuit 20 described in Figure 3 above and is coupled in the same manner. Figure 2 The circuit 20 of

[0061] Figure 3 above is thus the same as the circuit 20 of Figure 2 above. Figure 3The circuit 28 includes a triac 82 coupled between node 26 and node 18. In other words, one terminal of the triac 82, preferably the first anode, i.e., the anode on the gate side, is coupled, preferably connected, to node 26, and the other terminal of the triac 82, such as the second anode, is coupled, preferably connected, to node 18.

[0062] Preferably, the triac 82 is capable of operating in the first quadrant Q1 and the third quadrant Q3. The first quadrant Q1 represents an operating state where current flows from node 18 to node 26, the voltage on node 18 is greater than the voltage on node 26, and the current in the gate of the triac 82 flows into the triac 82. The third quadrant Q3 represents an operating state where current flows from node 26 to node 18, the voltage on node 26 is greater than the voltage on node 18, and the current in the gate of the triac 82 flows out of the triac 82.

[0063] The triac 82 preferably can withstand high currents. For example, the power range at 230V voltage is 500W to 10kW.

[0064] The circuit 28 further includes a triac 84 coupled between the gate of the triac 82 and node 18. In other words, the terminal of the triac 84, preferably the first anode, is coupled, preferably connected, to node 18, and the other terminal of the triac 84, such as the second anode, is coupled, preferably connected, to the gate of the triac 82. The triac 84 receives a control current Comm on its gate to control the triac 84. In addition, the gate of the triac 84 is biased by a bias voltage. Thus, the gate of the triac 84 is biased to a positive voltage with respect to node 18.

[0065] Preferably, the triac 84 is capable of operating in the first quadrant Q1 and the fourth quadrant Q4. The fourth quadrant Q4 represents an operating state where current flows from node 26 to node 18, the voltage on node 26 is greater than the voltage on node 18, and the current in the gate of the triac 84 flows into the triac 84.

[0066] At converter startup, a positive current flows from node 26 to node 18. The control current has a value, such as zero, at startup, so that the triac 84 can be turned off. Thus, the triac 82 is turned off. The current then flows through the resistor 24, which enables the reduction of the current peak that occurs at startup.

[0067] After startup, i.e., after the current peak generated at startup, the control current takes a value to turn on the triac 84, thereby turning on the triac 82. Thus, during operation, i.e., in the converter during the steady state, the current flows at least partially, preferably mostly, through the triac 82.

[0068] Preferably, the circuit 28 includes a transient voltage suppressor TSV circuit 86. The circuit 86 can avoid damage to the converter that may be caused by overcurrent when the system is turned off, for example, overcurrent caused by lightning. For example, the circuit 86 is a transil diode. Preferably, the circuit 86 is coupled between the node 18 and the gate of the triac 82. One terminal of the circuit 86 is coupled, preferably connected, to the node 18 for example, and the other terminal of the circuit 86 is coupled, preferably connected, to the triac 82.

[0069] Preferably, if the voltage across the triac 82 is greater than, for example, 50V, preferably greater than 100V, preferably greater than 200V, then the circuit 86 is configured to form a short circuit between the gate of the triac 82 and the node 18. Thus, when the voltage across the triac 82 is greater than the selected threshold, the triac 82 receives the voltage on the node 18 at its gate and conducts, thereby allowing the dissipation of the current peak in the triac 82.

[0070] An advantage of the described embodiments is that they can attenuate the current peak in the capacitor 22 when the converter is started.

[0071] An advantage of the described embodiments is that they can use the control signal of the circuit 28, which refers to the same node as other voltages already present in the circuit, for example, at the same node as the voltage Vout. Therefore, there is no need to provide a different auxiliary power supply, and the voltages already present in the device can be used.

[0072] 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.

[0073] 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.

Claims

1. A voltage converter for transmitting an output voltage between a first node and a second node, comprising: A capacitor serially coupled between the first node and the second node with a resistor; And A bidirectional switch parallely coupled with the resistor, wherein the bidirectional switch is configured to receive a positive bias voltage referenced to the second node at a control terminal of the bidirectional switch; Wherein the bidirectional switch comprises: a first triac having a first anode coupled to the first node via the capacitor and a second anode coupled to the second node; And a second triac coupled between a gate of the first triac and the second node, the second triac being controlled by the positive bias voltage.

2. The voltage converter according to claim 1, further comprising a voltage rectifier bridge coupled between the first node and the second node.

3. The voltage converter according to claim 1, wherein a control current is injected into the control terminal of the bidirectional switch, and if the control current has a first value, the bidirectional switch blocks the flow of positive current from the first node to the second node, and if the control current has a second value different from the first value, the bidirectional switch allows the positive current to flow from the first node to the second node.

4. The voltage converter according to claim 3, wherein a negative current flowing from the second node to the first node is independent of the control current.

5. The voltage converter according to claim 1, wherein a first anode of the second triac is coupled to the second node, and a second anode of the second triac is coupled to the gate of the first triac.

6. The voltage converter according to claim 1, wherein the bidirectional switch comprises a transient voltage suppression circuit coupled between the gate of the first triac and the second node.

7. The voltage converter according to claim 6, wherein the transient voltage suppression circuit comprises a transient voltage suppression diode.

8. A voltage converter, comprising: A rectifier bridge having a first output and a second output directly electrically connected to a first node and a second node, wherein an input voltage is received between a first input and a second input of the rectifier bridge; A capacitor directly electrically connected between the first node and a third node; A resistor directly electrically connected between the third node and the second node; And A bidirectional switch directly electrically connected between the third node and the second node, the bidirectional switch having a control terminal, wherein the control terminal receives a control signal, Wherein the bidirectional switch comprises: A first triac having a first anode directly electrically connected to the third node and a second anode directly electrically connected to the second node, the first triac further having a gate directly electrically connected to a fourth node; And A second triac having a first anode directly electrically connected to the gate of the first triac and a second anode directly electrically connected to the second node, the second triac having a gate receiving the control signal.

9. The voltage converter according to claim 8 further includes a transient voltage suppression circuit directly electrically connected between the fourth node and the second node.

10. The voltage converter according to claim 9, wherein the transient voltage suppression circuit includes a transient voltage suppression diode.

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