Voltage converter

Abstract

The embodiment of the invention relates to a voltage converter. The voltage converter passes an output voltage between the first and second nodes. The voltage converter includes a capacitor coupled in series with a resistor between the first and second nodes. The resistor is coupled in parallel with the bidirectional switch, and the bidirectional switch receives a positive bias voltage referenced to the second node at a control terminal of the bidirectional switch.

Description

[0001] Divisional Application Instructions

[0002] This application is a divisional application of the Chinese patent application with the application date of November 25, 2021, application number 202111409374.5, and name “Voltage Converter”. Technical Field

[0003] The present disclosure relates generally 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] Numerous AC / DC converter architectures are known that are based on controlled rectifying elements, such as thyristors (or SCRs, silicon controlled rectifiers), or uncontrolled rectifying elements, such as diodes assembled as a rectifying bridge, to supply an AC voltage and deliver a DC voltage.

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

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

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

[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 positive current from flowing from the first node to the second node. For a second value of the control current, the switch allows positive current to flow from the first node to the second node.

[0010] According to one embodiment, the flow of the 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, the cathode of which is coupled to the first node and the anode of which is coupled to the second node.

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

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

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

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

[0016] According to one embodiment, 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.

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

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

[0019] This document also discloses a voltage converter, including: a rectifier bridge having first and second outputs directly electrically connected to a first node and a second node, wherein an input voltage is received between the first and second inputs of the rectifier bridge; a capacitor directly electrically connected between the first and third nodes; a resistor directly electrically connected between the third and second nodes; and a bidirectional switch directly electrically connected between the third and second nodes, the bidirectional switch having a control terminal, wherein the control terminal receives a control signal.

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

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

[0022] The transient voltage suppressor circuit can 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 electrically connected directly between the third node and the fourth node.

[0025] The transient voltage suppressor circuit can be a transil diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above features and advantages and other features and advantages will be described in detail in the following description of specific embodiments given by way of example and not limitation with reference to the accompanying drawings, in which:

[0027] Figure 1 schematically illustrates an embodiment of a voltage converter disclosed herein;

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

[0029] Figure 3 Another embodiment of the voltage converter disclosed herein is shown in greater detail. DETAILED DESCRIPTION

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

[0031] For the sake of clarity, the steps and elements that are helpful for understanding the embodiments described herein have been described and illustrated in detail. In particular, various possible applications of the embodiments of the voltage converter have not been described in detail.

[0032] Unless otherwise specified, when two elements are referred to as being connected together, this means a direct connection without any intermediate elements other than conductors, and when two elements are referred to as being connected together, this means the two elements may be connected or may be connected through one or more other elements.

[0033] In the following disclosure, unless otherwise stated, 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", "higher", "lower", etc., or direction qualifiers, such as "horizontal", "vertical", etc., reference is made to the direction shown in the figures.

[0034] Unless otherwise stated, the expressions "about," "approximately," "substantially," and "on 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 transmitted between the nodes 12 and 14. For example, the input nodes 12 and 14 are coupled across an AC voltage source (not shown), which may be, for example, a power distribution system.

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

[0038] Converter 10 includes circuitry 20 that receives voltage Vin and delivers voltage Vout. Circuitry 20 is coupled, preferably connected, to input nodes 12 and 14 and output nodes 16 and 18. Circuitry 20 includes a rectifier bridge, details of which are not shown. Figure 1 Shown in.

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

[0040] Converter 10 also includes circuit 28. One terminal of circuit 28 is coupled to, and preferably connected to, node 26. Another terminal of circuit 28 is coupled to, and preferably connected to, node 18. 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 on node 18, in other words, referenced to the same voltage as the output voltage (i.e., for example, ground), and also receives a control current.

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

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

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

[0044] When the converter begins operating, a current peak typically occurs in the current flowing through capacitor 22. Such a current peak can 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. Therefore, circuit 28 prevents positive current from flowing from node 26 to node 18 through the branch including circuit 28 and ensures that the current flows through resistor 24. In other words, during the period that may include a current peak, that is, at the start of the converter, the value of the current is controlled so that the positive current is blocked between the input and output of circuit 28 and the positive current is caused to flow through the resistor.

[0045] When such a current peak occurs at the start-up of the converter, current flows from node 16 to node 18. Therefore, preventing negative current from flowing through circuit 28 is generally useless.

[0046] Figure 2 An embodiment of a voltage converter 50 is shown in more detail. The converter 50 is Figure 1 Thus, the converter 50 includes a capacitor 22, a circuit 28, and a circuit 20, coupled as associated Figure 1 As stated.

[0047] The circuit 20 includes a rectifier bridge. Figure 2 In the example of FIG, the rectifier bridge is a diode rectifier bridge. Therefore, the rectifier bridge includes four diodes 52, 54, 56 and 58.

[0048] Diodes 52 and 56 are coupled in series between nodes 16 and 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. Furthermore, 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 coupled in series between nodes 16 and 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. Furthermore, 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 comprises two branches coupled in parallel, each branch comprising two diodes coupled in series, diodes 52 and 56 or diodes 54 and 58. The diodes of the same branch are coupled in series so 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 the diodes 52, 54, 56, and 58 may be replaced by another electronic component capable of forming a rectifier bridge. For example, at least one of the diodes 52, 54, 56, and 58, for example two of the diodes 52, 54, 56, and 58, may 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 coupled, for example, between node 60 and input node 12. Inductor 66 is coupled, for example, between node 62 and input node 14. More specifically, one terminal of inductor 64 is coupled, preferably connected, to node 60, and another 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 another terminal of inductor 66 is coupled, preferably connected, to node 14.

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

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

[0055] Thyristor 70 is, for example, a cathode-gate thyristor. The thyristor receives a voltage at its gate referenced to node 18. The thyristor gate receives a bias voltage corresponding to control signal Comm. The thyristor gate 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] When the converter starts, a positive current flows from node 26 to node 18. At startup, the control current has a value capable of turning on thyristor 70. In addition, diode 68 does not conduct the current flowing from node 26 to node 18. The current therefore flows through resistor 24, which attenuates the current peak that occurs 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. Therefore, during operation, i.e. during the steady state of the converter, the current flows at least partially, preferably mostly, through the diode 68 or the thyristor 70, depending on the direction of the current.

[0058] Preferably, circuit 28 includes a transient voltage suppressor (TSV) circuit 72. When the system is off, i.e., when capacitor 22 is discharged and thyristor 70 is blocked (meaning that thyristor 70 is not receiving a control signal corresponding to the on-state), circuit 72 protects the converter from potential damage caused by transient voltages or overvoltages. For example, during an overvoltage caused by lightning, a high current flows through capacitor 22 and resistor 24. This current causes the voltage across the terminals of resistor 24 to rise and reach a threshold voltage of circuit 72. Once this threshold voltage is reached, current flows from node 26 through circuit 72 to node 18, triggering thyristor 70 and causing it to turn on. By turning on, thyristor 70 shorts out resistor 24 and prevents the voltage from reaching the converter's critical value. For example, circuit 72 is a transilluminator, such as a unidirectional transilluminator. Preferably, circuit 72 is coupled between node 26 and the gate of thyristor 70. One terminal of circuit 72 is coupled, preferably connected, to node 26 , for example, and another terminal of circuit 72 is coupled, preferably connected, to node 18 , for example.

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

[0060] Figure 3 An embodiment of a voltage converter 80 is shown in more detail. The converter 80 is Figure 1 Thus, the converter 80 includes a capacitor 22, a circuit 28, and a circuit 20, coupled as associated Figure 1 As stated. Figure 3 In the example of FIG. 1 , the circuit 20 includes an associated Figure 2 The same elements of the circuit 20 are described. Figure 3 The circuit 20 is therefore Figure 2 The circuit 20 is the same.

[0061] Figure 3 The converter 80 with Figure 2 Converter 50 differs in the composition of circuit 28 . Figure 3Circuit 28 includes a triac 82 coupled between node 26 and node 18. In other words, one terminal of triac 82, preferably a first anode, i.e., the anode on the gate side, is coupled, preferably connected, to node 26, and another terminal of triac 82, e.g., a 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 in which 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 toward the triac 82. The third quadrant Q3 represents an operating state in which 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 is preferably capable of withstanding high current, for example, a power range of 500W to 10kW at 230V.

[0064] Circuit 28 also includes a triac 84 coupled between the gate of triac 82 and node 18. In other words, a terminal of triac 84, preferably a first anode, is coupled, preferably connected to node 18, and another terminal of triac 84, such as a second anode, is coupled, preferably connected, to the gate of triac 82. Triac 84 receives a control current Comm at its gate to control triac 84. In addition, the gate of triac 84 is biased by a bias voltage. Therefore, the gate of triac 84 is biased to a positive voltage referenced to node 18.

[0065] Preferably, triac 84 is capable of operating in the first quadrant Q1 and the fourth quadrant Q4. The fourth quadrant Q4 represents an operating state in which 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 triac 84 flows to triac 84.

[0066] When the converter starts, a positive current flows from node 26 to node 18. The control current has a value, for example, zero, at startup, which turns off triac 84. As a result, triac 82 is turned off. Current thus flows through resistor 24, which reduces 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 that turns on the triac 84, thereby turning on the triac 82. Therefore, during operation, i.e., during steady state in the converter, the current flows at least partially, preferably mostly, through the triac 82.

[0068] Circuit 28 preferably includes a transient voltage suppressor (TSV) circuit 86. Circuit 86 can prevent damage to the converter caused by overcurrent during system shutdown, such as that caused by lightning. Circuit 86 is, for example, a transilluminator diode. Circuit 86 is preferably coupled between node 18 and the gate of triac 82. One terminal of circuit 86 is, for example, coupled to, and preferably connected to, node 18, and the other terminal of circuit 86 is, for example, coupled to, and preferably connected to, triac 82.

[0069] Preferably, if the voltage across the triac 82 is greater than, for example, 50 V, preferably greater than 100 V, and preferably greater than 200 V, 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 a selected threshold, the triac 82 receives the voltage on the node 18 on its gate and turns on, thereby allowing the current peak in the triac 82 to dissipate.

[0070] An advantage of the described embodiments is that they are able to attenuate current peaks in the capacitor 22 when the converter starts up.

[0071] An advantage of the described embodiments is that they enable the use of control signals for circuit 28 that are referenced to the same nodes as other voltages already present in the circuit, for example, to the same node as voltage Vout. It is therefore not necessary to provide a different auxiliary power supply, and voltages already present in the device can be used.

[0072] Various embodiments and variations have been described. Those skilled in the art will appreciate that certain features of these various embodiments and variations may be combined, and those skilled in the art will recognize other variations.

[0073] Finally, based on the functional indications given above, the actual implementation of the described embodiments and variants is within the capabilities of a person skilled in the art.

Claims

1. A voltage converter, comprising: an input node for receiving an input voltage; an output node for delivering an output voltage; a rectifier bridge coupled between the input node and the output node; a capacitor and a resistor coupled in series between the output nodes; a thyristor coupled between one terminal of the resistor and a given one of the output nodes, wherein the thyristor is configured to allow a positive current to flow from the resistor to the given one of the output nodes; a control input configured to receive a control signal, wherein the control signal biases a gate of the thyristor to control the flow of current through the thyristor; as well as A transient voltage suppressor circuit coupled to the gate of the thyristor is configured to activate the thyristor when a threshold voltage is exceeded.

2. The voltage converter according to claim 1 , wherein the rectifier bridge comprises: diodes arranged in parallel branches, each branch having two diodes coupled in series between the output nodes; as well as An inductor is coupled between each branch of the diode and a corresponding input node.

3. The voltage converter according to claim 1, wherein The control input receives the control signal as a positive bias voltage referenced to one of the output nodes.

4. The voltage converter according to claim 1, wherein The thyristor is a cathode-gate thyristor, and wherein a gate of the cathode-gate thyristor is configured to receive the control signal to switch the cathode-gate thyristor between an on-state and an off-state based on a current injected into the gate by the control signal.

5. The voltage converter according to claim 1, wherein The transient voltage suppressor circuit is configured to form a short circuit between a gate of the thyristor and one of the output nodes when the voltage across the thyristor exceeds the threshold voltage, thereby turning on the thyristor to limit the voltage across the resistor under an overvoltage condition.

6. The voltage converter of claim 1 , further comprising a diode coupled in parallel with the thyristor between a given terminal of the resistor and a given one of the output nodes, wherein a cathode of the diode is connected to the given one of the output nodes and an anode of the diode is connected to the given terminal of the resistor, the diode being configured to allow a negative current to flow opposite to the positive current allowed by the thyristor. 7 . The voltage converter of claim 1 , wherein the resistor is configured to attenuate a current peak occurring when the voltage converter starts up by providing a path for the current during a thyristor off-time. 8 . The voltage converter of claim 1 , further comprising a diode coupled in parallel with the thyristor and connected end to end, the diode being configured to allow a negative current to flow opposite to the positive current allowed by the thyristor.

9. The voltage converter according to claim 8, wherein The diode is reverse-coupled such that the diode does not conduct the positive current flowing out of the resistor, thereby ensuring that the positive current flows through the resistor during startup of the voltage converter.

10. A method for performing voltage conversion using a voltage converter, the method comprising: receiving an input voltage at an input node of the voltage converter; rectifying the input voltage using a rectifier bridge to generate an output voltage; transferring the output voltage between output nodes of the voltage converter; directing a portion of the output voltage through a series arrangement of a capacitor and a resistor; controlling a flow of positive current through the thyristor coupled between one terminal of the resistor and a given one of the output nodes by applying a control signal to a gate of the thyristor; as well as When a voltage threshold is exceeded, a transient voltage suppressor circuit is used to activate the thyristor to control the voltage peak.

11. The method according to claim 10, wherein: The rectification includes using diodes arranged in parallel branches, each branch having two diodes coupled in series between the output nodes.

12. The method according to claim 10, wherein: The control signal includes a positive bias voltage referenced to the output node.

13. The method according to claim 10, wherein: Controlling the flow of the positive current through the thyristor further includes injecting a control current into a gate of the thyristor to switch the thyristor between an on state and an off state.

14. The method according to claim 10, wherein: The activation of the thyristor includes: detecting that the voltage across the thyristor exceeds a voltage threshold, thereby forming a short circuit between the gate of the thyristor and the output node to turn on the thyristor.

15. The method of claim 10, further comprising allowing a negative current to flow through a diode coupled in parallel with the thyristor, wherein the diode does not conduct a positive current such that the positive current flows through the resistor during startup of the voltage converter.

16. The method of claim 10, wherein directing a portion of the output voltage through the resistor comprises: When the thyristor is turned off, a current peak at the start-up of the voltage converter is attenuated by providing a path for the current to flow through the resistor.

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