Surge protection device

Abstract

Surge Protection Device This description concerns a surge protection device comprising, between a first terminal (N201) and a second terminal (N202): - a first Zener diode (DZ201); - a series circuit comprising a varistor (MOV201), a first capacitor (C201) and a thyristor (T201), having its gate terminal connected to said first terminal (N201), and a first resistor (R203) arranged in parallel with said first capacitor (C201). Figure for the abbreviation: Fig. 2

Description

Title of the invention: Overvoltage protection device technical field

[0001] This description relates generally to electronic systems and devices, and more particularly to the protection of these systems and devices against various physical phenomena. More specifically, this description concerns the protection of electronic systems and devices against overvoltages. Previous technique

[0002] Nowadays, it is essential to equip electronic systems and devices with overcurrent and overvoltage protection circuits. Indeed, the occurrence of an overcurrent or overvoltage can severely damage an unprotected system or device.

[0003] It would be desirable to be able to improve, at least in part, certain aspects of the overvoltage protection circuits. Summary of the invention

[0004] There is a need for a more efficient overvoltage protection device.

[0005] There is a need for a surge protection device protecting a DC voltage bus.

[0006] There is a need for a surge protection device protecting a DC voltage bus capable of stopping an overvoltage greater than 900 V.

[0007] An embodiment overcomes all or part of the drawbacks of known overvoltage protection devices.

[0008] An embodiment overcomes all or part of the drawbacks of known surge protection methods.

[0009] One embodiment provides for an overvoltage protection device comprising, between a first terminal and a second terminal: - a first Zener diode; - a series circuit comprising a varistor, a first capacitor and a thyristor, having its gate terminal connected to said first terminal, and a first resistor arranged in parallel with said first capacitor.

[0010] Another embodiment provides for a method of protection against overvoltages using an overvoltage protection device comprising, between a first terminal and a second terminal: - a first Zener diode; - a series circuit comprising a varistor, a first capacitor and a thyristor, having its gate terminal connected to said first terminal, and a first resistor arranged in parallel with said first capacitor.

[0011] According to one embodiment, a cathode terminal of said thyristor is connected to said second terminal, and an anode terminal of said thyristor is connected to said first terminal.

[0012] According to one embodiment, a cathode terminal of said first Zener diode is connected to said first terminal, and an anode terminal of said first Zener diode is connected to said second terminal.

[0013] According to one embodiment, said device further comprises at least one second resistor arranged in series with said first Zener diode.

[0014] According to one embodiment, said device further comprises at least one third resistor arranged in series between the gate of said thyristor and said second terminal.

[0015] According to one embodiment, said device further comprises at least one second Zener diode arranged in series with said first Zener diode.

[0016] According to one embodiment, said device further comprises at least one second capacitor arranged in series with said first capacitor.

[0017] Another embodiment provides for a DC voltage transmission bus comprising a device described above adapted to protect said bus against overvoltages.

[0018] According to one embodiment, the bus includes a three-phase connector. Brief description of the drawings

[0019] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0020] [Fig.1] represents an example of an electronic system using an embodiment of a surge protection device;

[0021] [Fig.2] represents an embodiment of a surge protection device;

[0022] [Fig.3] represents another embodiment of a surge protection device;

[0023] [Fig. 4] shows graphs illustrating the operation of the embodiment of [Fig. 3]; and

[0024] [Fig.5] represents other graphs illustrating the operation of the embodiment of [Fig.3]. Description of the implementation methods

[0025] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0026] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0027] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0028] In the following description, when reference is made 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", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0029] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0030] The embodiments described below relate to the implementation of overvoltage protection, and more particularly to the implementation of overvoltage protection against overvoltages exceeding 900 V that may occur on a DC voltage bus, i.e., a bus adapted to supply a DC voltage. The embodiments described below relate to an overvoltage protection device and a protection method using this device. This device includes a thyristor that is made to conduct when an overvoltage is detected.This thyristor could, however, present problems and remain conductive after the passage of an overvoltage; therefore, the embodiments described below include, in addition, a capacitor and a resistor both mounted in parallel to reduce the current supply to the thyristor and thus ensure its opening, that is to say, becoming non-conductive, after the passage of an overvoltage.

[0031] Moreover, the embodiments described below are particularly suitable for use in fields where a DC voltage bus is used, such as the field of electric cars, DC charging stations for electric vehicles, the field of thyristors, the field of power electronics using thyristors, the field of data centers intended, for example, to implement artificial intelligence programs.

[0032] More generally, the embodiments described above are particularly suitable for use in all types of industrial markets where Surge protection is necessary. More specifically, such surge protection may be intended to: - the automotive industry, for example in the field of automotive electrification or in the field of advanced driver assistance systems (ADAS); - the industrial sector, for example in the field of green energy, in the field of infrastructure electrification, the Internet of Things (IoT) and Smart Homes, where electricity and energy consumption and data exchange are key elements; - the communications equipment, computer and peripherals industry, for example in the field of infrastructure and data centers.

[0033] Fig. 1 is an electrical diagram of an example of an embodiment of a DC voltage transmission bus 100, or DC voltage bus 100, that is to say a bus adapted to supply a DC voltage to an electronic device.

[0034] Bus 100 is represented by two rails N101 and N102.

[0035] The bus 100 is adapted to receive a DC voltage from a DC voltage source 101. A first terminal of the source 101 is connected, preferably connected, to rail N101, and a second terminal of the source 101 is connected, preferably connected, to rail N102. In one example, the voltage source 101 is part of the bus 100. In another variant, the voltage source 101 may be external to the bus 100. In one example, the voltage source 101 is adapted to supply a DC voltage between 0 and 1500 V. In a particular example, the bus 100 is adapted to supply a high voltage, so the voltage source 101 is adapted to supply a voltage between 200 and 1500 V.

[0036] The bus 100 further includes an overvoltage protection device 102 (OVP) which is connected directly in parallel with the terminals of the voltage source 101. This device 102 is adapted to filter overvoltages so as not to damage the other components of the bus 100 and the electronic devices using the bus 100. Two embodiments of the protection devices and their operation are described in detail with reference to Figures 2 to 5.

[0037] In one example, the bus 100 further comprises a common-mode inductor 103 represented by two coils. In one example, a first coil is connected in series with the first rail N101. In another example, a second coil is connected in series with the second rail N102. The inductor 103 is intended to reduce electromagnetic noise by coupling.

[0038] According to one example, the bus 100 further comprises a resistor R101 arranged, for example, in parallel with the protection device 102. According to one example, the resistor R101 allows a capacitor mounted in parallel with it to be discharged, for example the capacitor C103 described below.

[0039] According to one example, the bus 100 further comprises two filter capacitors C101 and C102. According to one example, a first filter capacitor C101 connects, preferably connects, the first rail N101 to a reference potential. According to one example, a second filter capacitor C102 connects, preferably connects, the second rail N102 to the reference potential.

[0040] According to one example, the bus 100 further includes a capacitor C103 arranged, for example, in parallel with the protection device 102. According to one example, the protection device 102 is sized to protect the capacitor C103 from overvoltages.

[0041] According to one example, bus 100 is adapted to supply a three-phase alternating voltage. For this purpose, bus 100 includes a three-phase connector 104. The three-phase connector 104 includes six transistors T101 to T106. According to one example, transistors T101 to T106 are metal-oxide-semiconductor field-effect transistors (MOSFETs). In addition, transistors T101 to T106 are N-channel MOS transistors. According to another example, transistors T101 to T106 may be insulated-gate bipolar transistors (IGBTs).

[0042] According to one example, a drain terminal of transistor T101 is connected, preferably connected, to the first rail N101, and a source terminal of transistor T101 is connected, preferably connected, to a first output N103. According to one example, a drain terminal of transistor T102 is connected, preferably connected, to the first rail N101, and a source terminal of transistor T102 is connected, preferably connected, to a second output N104. According to one example, a drain terminal of transistor T103 is connected, preferably connected, to the first rail N101, and a source terminal of transistor T103 is connected, preferably connected, to a fourth output N105.

[0043] According to one example, a drain terminal of transistor T104 is connected, preferably connected, to the first output N103, and a source terminal of transistor T104 is connected, preferably connected, to the second rail N102. According to one example, a drain terminal of transistor T105 is connected, preferably connected, to the second output N104, and a source terminal of transistor T104 is connected, preferably connected, to the second rail N102. According to one example, a drain terminal of transistor T106 is connected, preferably connected, to the third output N105, and a source terminal of transistor T106 is connected, preferably connected, to the second rail N102.

[0044] The [Fig.2] is an electrical diagram of a first embodiment of a 200 overvoltage protection device.

[0045] According to an example, in [Fig. 2], a voltage source 250 and a capacitor C250 to be protected are also shown. More particularly, the capacitor C250 comprises a first terminal connected, preferably connected, to a first terminal of the voltage source 250, and a second terminal connected, preferably connected, to a second terminal of the voltage source 250.

[0046] According to an example, in [Fig.2], a voltage source 251 adapted to simulate an overvoltage is also shown.

[0047] The device 200 comprises two terminals N201 and N202. According to one example, terminal N201 is connected, preferably connected, to the first terminal of the source 250, the first terminal of the capacitor C250 and to a first terminal of the voltage source 251. According to another example, terminal N202 is connected, preferably connected, to the second terminal of the source 250, the second terminal of the capacitor C250 and to a second terminal of the voltage source 251.

[0048] In one embodiment, the device 200 comprises a first branch, disposed between terminals N201 and N202, including a Zener diode DZ201. In one embodiment, a cathode terminal of diode DZ201 is connected, preferably connected, to terminal N201. In another embodiment, an anode terminal of diode DZ201 is connected to terminal N202. In one example, this first branch further comprises a resistor R201 disposed between the anode terminal of diode DZ201 and terminal N202.

[0049] In one embodiment, the device 200 comprises a second branch, disposed between terminals N201 and N202, including a varistor MOV201, i.e., a variable resistor, and a thyristor T201. In one embodiment, a first terminal of the varistor MOV201 is connected, preferably connected, to terminal N201, and a second terminal of the varistor MOV201 is connected to an anode terminal of the thyristor T201. In one example, the varistor MOV201 is a metal oxide varistor. In one embodiment, a cathode terminal of the thyristor T201 is connected, preferably connected, to terminal N202. According to one embodiment, a gate terminal of the thyristor T201 is connected to the first branch and, in particular, is connected to the anode terminal of the Zener diode DZ201. According to one example, the gate terminal of the thyristor T201 is connected to the anode terminal of the Zener diode DZ201 via a resistor R202.

[0050] According to one embodiment, this second branch further comprises an assembly including a capacitor C201 and a resistor R203 in parallel arranged between the varistor MOV201 and the thyristor T201. More particularly, a first terminal of the capacitor C201 and the resistor R203 are connected, preferably connected, to each other and to the second terminal of the varistor MOV201, and a second terminal of capacitor C201 and resistor R203 are connected, preferably connected, to each other and to the anode terminal of thyristor T201.

[0051] The protection device operates as follows. When an overvoltage occurs between terminals N201 and N202, a high voltage appears across the first and second branches. When this high voltage exceeds the avalanche voltage of Zener diode DZ201, it is accompanied by a current flowing through Zener diode DZ201 in reverse, which acts as a gate control current for thyristor T201. As soon as the gate control current exceeds the trigger current of thyristor T201, thyristor T201 becomes conductive, allowing the current due to the overvoltage to flow.

[0052] When the overvoltage ceases, the overcurrent through thyristor T201 also ceases, but the direct current generated by the 250V power supply now flows through thyristor T201 and prevents it from becoming non-conductive. Even in the absence of a gate control current, thyristor T201 remains conductive as long as the current flowing through it does not drop to zero. This is why capacitor C201 and resistor R203 are present. Capacitor C201 charges with the current from the 250V power supply. The increase in the capacitor's voltage reduces the voltage across varistor MOV201 by the same amount. When the voltage across varistor MOV201 falls below its avalanche voltage, the current through thyristor T201 is significantly reduced and becomes less than its holding current. As a result, the T201 thyristor opens and is no longer conducting.Resistor R203 allows capacitor C201 to be discharged periodically to allow current to flow again in this branch during a subsequent voltage overload.

[0053] An advantage of this embodiment is that the presence of capacitor C201 and resistor R203 helps to make the thyristor non-conducting once an overvoltage has been detected.

[0054] According to one embodiment, a method of protection against overvoltages is a method of using the protection device 200.

[0055] The [Fig.3] is an electrical diagram of a second embodiment of a 300 overvoltage protection device.

[0056] According to an example, in [Fig. 3], a voltage source 350 and a capacitor C350 to be protected are also shown. More particularly, the capacitor C350 comprises a first terminal connected, preferably connected, to a first terminal of the voltage source 350, and a second terminal connected, preferably connected, to a second terminal of the voltage source 350.

[0057] According to an example, in [Fig.3], a voltage source 351 adapted to simulate an overvoltage is also shown.

[0058] Device 300 is similar to Device 200 described in relation to [Fig. 2]. The features common to Devices 200 and 300 are not described again in detail. Only the differences between Devices 200 and 300 are highlighted.

[0059] Thus, like device 200, device 300 comprises: - terminals N201 and N202; - the Zener diode DZ201; - resistors R201 and R202, if applicable; - the MOV201 varistor; - the T201 thyristor; - capacitor C201; and - the R203 resistor.

[0060] According to one embodiment, the device 300 further comprises a second Zener diode DZ301 arranged in series with the Zener diode DZ201. More particularly, the Zener diode DZ301 is arranged between the Zener diode DZ201 and the resistor R201.

[0061] According to one embodiment, the device 300 further comprises a second capacitor C301 arranged in series with capacitor C201. More specifically, capacitor C301 is arranged in series with capacitor C201, and both capacitors C201 and C301 are in parallel with resistor R203.

[0062] The addition of the Zener diode DZ301 and the capacitor C301 allows the value of an overvoltage detected by the protection device 300 to be modified. The addition of these components can also allow a better distribution of the costs and size of the components in the circuit.

[0063] The operation of device 300 is identical to that of protection device 200 described in relation to [Fig.2].

[0064] According to one embodiment, a method of protection against overvoltages is a method of using the protection device 300.

[0065] Figures 4 and 5 include graphs illustrating the operation of the embodiments described in relation to Figures 2 and 3, and in particular the embodiment described in relation to Figure 3.

[0066] More specifically, in [Fig.4], the following are shown: - a curve 401 (blue in [Fig.4]) representing the evolution of the voltage across the capacitor C350; - a curve 402 (green in [Fig.4]) representing the evolution of the voltage across the terminals of the thyristor T201; - a curve 403 (pink in [Fig.4]) representing the evolution of the voltage across the terminals of the MOV201 varistor; - a curve 404 (orange in [Fig.4]) representing the evolution of the voltage across the resistor R203; - a curve 405 (blue in [Fig.4]) representing the evolution of the current passing through the thyristor T201; and - a curve 406 (yellow in [Fig.4]) representing the evolution of the overvoltage current supplied by the voltage source 351.

[0067] More specifically, in [Fig. 5], the following are shown: - a curve 501 (light blue in [Fig.5]) representing the evolution of the voltage across the resistor R202; - a curve 502 (blue in [Fig.5]) representing the evolution of the voltage across the capacitor C350; - a curve 503 (green in [Fig.5]) representing the evolution of the voltage across the terminals of the thyristor T201; - a curve 504 (pink in [Fig.5]) representing the evolution of the voltage across the terminals of the MOV201 varistor; - a curve 505 (orange in [Fig.5]) representing the evolution of the voltage across the resistor R203; - a curve 506 (blue in [Fig.5]) representing the evolution of the current passing through the thyristor T201; and - a curve 507 (yellow in [Fig.5]) representing the evolution of the overvoltage current supplied by the voltage source 351.

[0068] As described previously, when an overvoltage occurs at terminal N201, a high voltage flows through the first and second branches of device 300. This voltage is accompanied by a current that flows through the Zener diode DZ201 in reverse and acts as a gate control current for thyristor T201. This voltage also causes a current to flow through thyristor T201, which then becomes conductive (SCR ON).

[0069] When the overvoltage ceases, the current through the thyristor also ceases, but sometimes enough current may remain to prevent it from becoming non-conductive (SCR OFF). This is why capacitor C201 and resistor R203 are present. Capacitor C201 charges with the remaining current and reduces the current through thyristor T201. Resistor R203 periodically discharges capacitor C201 to reduce the residual current.

[0070] It is then observed that the voltage across capacitor C350 remains constant despite the arrival of the overvoltage. According to a specific example, such an arrangement can protect a high-voltage device, for example receiving a voltage of 600 V across its terminals, against overvoltages exceeding 4000 V by maintaining the potential between rails N201 and N202 at 900 V during the overload.

[0071] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0072] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Overvoltage protection device comprising, between a first terminal (N201) and a second terminal (N202): - a first Zener diode (DZ201); - a series assembly comprising a varistor (MOV201), a first capacitor (C201) and a thyristor (T201), having its gate terminal connected to said first terminal (N201), and a first resistor (R203) arranged in parallel with said first capacitor (C201).

2. Surge protection method using a surge protection device comprising, between a first terminal (N201) and a second terminal (N202): - a first Zener diode (DZ201); - a series assembly comprising a varistor (MOV201), a first capacitor (C201) and a thyristor (T201), having its gate terminal connected to said first terminal (N201), and a first resistor (R203) arranged in parallel with said first capacitor (C201).

3. Device according to claim 1, or method according to claim 2, wherein a cathode terminal of said thyristor (T201) is connected to said second terminal (N202), and an anode terminal of said thyristor (T201) is connected to said first terminal (N201).

4. Device according to claim 1 or 3, or method according to claim 2 or 3, wherein a cathode terminal of said first Zener diode (DZ201) is connected to said first terminal (N201), and an anode terminal of said first Zener diode (DZ201) is connected to said second terminal (N202).

5. Device according to any one of claims 1, 3 or 4, or method according to any one of claims 2 to 4, wherein said device further comprises at least one second resistor (R201) arranged in series with said first Zener diode (DZ201).

6. A device according to any one of claims 1, 3 to 5, or a method according to any one of claims 2 to 5, wherein said device further comprises at least a third resistance (R202) arranged in series between the trigger of said thyristor (T201) and said second terminal (N202).

7. Device according to any one of claims 1, 3 to 6, or method according to any one of claims 2 to 6, wherein said device further comprises at least one second Zener diode (DZ301) arranged in series with said first Zener diode (DZ201).

8. Device according to any one of claims 1, 3 to 7, or method according to any one of claims 2 to 7, wherein said device further comprises at least one second capacitor (C301) arranged in series with said first capacitor (C201).

9. Bus (100) for transmitting a DC voltage comprising a device (200; 300) according to any one of claims 1, 3 to 8 adapted to protect said bus against overvoltages.

10. Bus according to claim 9, comprising a three-phase connector (104).

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