Semi-conductor circuit and semi-conductor protection method

Abstract

This disclosure provides a semi-conductor circuit, having at least one branch with at least one gate-controllable semi-conductor; and a gate control circuit (120) for selectively triggering the semi-conductor (110) into a conductive state; the gate control circuit (120) includes a voltage detector configured to determine a voltage value representative of an electrical voltage applied to the semi-conductor (110), wherein the gate control circuit (120) is configured to determine, based on the determined voltage value, the presence of a fault condition and, upon a presence of the fault condition being determined, to trigger the semi-conductor (110) into a conductive state. This disclosure further provides a method of protecting a gate-controllable semi-conductor and an electronic device having a plurality of gate-controllable semi-conductors being connected in series and the semi-conductor circuit according to this disclosure.

Description

DescriptionSemi-Conductor Circuit and Semi-Conductor Protection MethodTECHNICAL FIELD

[0001] This disclosure relates to a semi-conductor circuit, to a semi-conductor protection method for protecting a gate-controllable semi-conductor and to an electronic device having such a semi-conductor circuit.BACKGROUND

[0002] In high voltage, high current applications, electronic devices often employ gate-controllable semi-conductors, such as, e.g., thyristors, as power electronic components. Upon reception of a trigger current at its gate, a semi-conductor may start to conduct an electrical current in a path from its anode terminal to its cathode terminal. In the literature, triggering is also referred to as firing or gating. Unless triggered, the semi-conductor may be in a nonconducting state or blocking state.

[0003] Gate-controllable semi-conductors such as thyristors may thus be used for current control in various applications, e. g. as crow bars, high power rectifiers, static power compensators, static var compensators etc. When gate-controllable semi-conductors or a stack of multiple series-connected gate-controllable semi-conductors are connected in an antiparallel manner, they can be used to control currents in both directions, e. g. in AC applications such as static var compensators.

[0004] In typical applications, an overvoltage condition may occur. In this case, the semi-conductor needs to be switched on to protect the semi-conductor from being damaged. Typically, break-over diodes may be employed to protect the semi-conductor. A break-over diode may be configured to switch a semi-conductor on in case of a predetermined voltage level and / or in case of a predetermined voltage rise. However, break-over diodes are expensive, must be coordinated with a blocking voltage of the used semi-conductor and / or may not always be available as there are only a few suppliers that provide such break-over diodes.SUMMARY

[0005] Aspects and advantages of the disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the disclosure.

[0006] The present disclosure provides a semi-conductor circuit having a gate control circuit that is relatively cheap, easy to employ and / or reduces a dependence on the availability of breakover diodes.

[0007] In one example, the disclosure provides a semi-conductor circuit, having at least one branch including at least one gate-controllable semi-conductor, in particular a thyristor; and a gate control circuit for selectively triggering the semi-conductor into a conductive state; the gate control circuit having: a voltage detector configured to determine a voltage value representative of an electrical voltage applied to the semi-conductor, wherein the gate circuit is configured to determine, based on the determined voltage value, the presence of a fault condition and, upon a presence of a fault condition being determined, to trigger the semi-conductor into a conductive state.

[0008] In another example, the disclosure provides a semi-conductor protection method for protecting a gate-controllable semi-conductor, in particular a thyristor, in at least one branch of a semi-conductor circuit, including: determining a voltage value representative of an electrical voltage applied to the semi-conductor; determining whether the voltage value fulfills a fault condition; and upon a presence of a fault condition being determined, triggering the semi-conductor into a conductive state.

[0009] In yet another example, the disclosure provides an electronic device having a plurality of gate-controllable semi-conductors, in particular thyristors, being connected in series, in particular a static power compensator, a static var compensator, a high-voltage rectifier, a high voltage valve, a crow bar or a by-pass, and the semi-conductor circuit according to the present disclosure.

[0010] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0011] A full and enabling disclosure of the present disclosure is set forth in the specification, which makes reference to the appended figures, in which:

[0012] FIG. 1 is a schematic view of a semi-conductor circuit according to embodiments of the present disclosure.

[0013] FIG. 2 is a schematic view of a method of protecting a gate-controllable semi-conductor according to embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] This disclosure generally relates to the protection of a gate-controllable semi-conductor, in particular a thyristor, from an overvoltage level and / or a voltage rise through integrating protection functions to a gate control circuit. An apparatus operating according to the present disclosure includes the gate control circuit having a voltage detector to determine a voltage value representative of an electrical voltage applied to the semi-conductor. The gate control circuit is configured to determine, based on the determined voltage value, the presence of a fault condition and, upon a presence of the fault condition being determined, to trigger the semi-conductor into a conductive state. In some examples, the apparatus is implemented on a gate driver.

[0015] In general, this disclosure describes protection of at least one gate-controllable semiconductor from an overvoltage level and / or from a voltage rise. Already a short overvoltage can cause the semi-conductor to get damaged respectively to be short circuited.

[0016] Typically, an overvoltage may occur in case a trigger generation for normal operation of the electronic device fails to materialize. For example, if a stack of serial connected semiconductors is provided and all semi-conductors except for one get a firing pulse to switch on, the voltage above the remaining one in the off state will increase very fast. Overvoltage may also occur for other reasons, such as in case of a load drop, in case of certain switching events and / or for similar reasons that may lead to an overvoltage level for one or more of a plurality of semi-conductors.

[0017] Such gate-controllable semi-conductors may be employed in a static power compensator, a static var compensator, a high-voltage rectifier, a high voltage valve, a crow bar, a by-passor similar. In particular, any electronic device, e.g., for applications having a plurality of gate-controllable semi-conductors being connected in series may benefit from a semiconductor circuit of the present disclosure. These applications may be high-voltage, high- current, low-voltage and / or similar applications.

[0018] The semi-conductor circuit includes at least one branch with at least one gate-controllable semi-conductor. Such a gate-controllable semi-conductor may be a thyristor. In some examples, the gate-controllable semi-conductor may be an insulated-gate bipolar transistor (IGBT), an integrated gate-commutated thyristor (IGCT), a (SiC-)MOSFET and / or alike. By triggering the semi-conductor at the gate, the semi-conductor is set to a conductive state and typically remains in the conductive state until a current flowing through the semiconductor falls below a holding current and / or until the semi-conductor is controlled to switch to the off state (non-conductive state).

[0019] The semi-conductor circuit further includes a gate control circuit. The gate control circuit may directly be connected to the gate of the semi-conductor. The gate control circuit selectively triggers the semi-conductor into the conductive state. In some embodiments, the semi-conductor may be triggered into the conductive state by an electrical signal, a light signal and / or alike. The gate control circuit may be implemented on the gate driver. The gate driver is typically implemented on a printed circuit board. The gate driver may also be referred to as semi-conductor electronics or as a semi-conductor firing circuit. The gate control circuit may selectively trigger the semi-conductor into the conductive state during normal operation of the semi-conductor, i.e. to control the semi-conductor to conduct a predetermined task that is assigned to the semi-conductor by an operational logic.

[0020] The gate control circuit includes a voltage detector being configured to determine one or more voltage values representative of an electrical voltage applied to the semi-conductor. For example, the voltage value may be indicative of a voltage level at the semi-conductor and / or of a voltage rise at the semi-conductor. In embodiments, the electrical voltage applied to the semi-conductor is measured. In particular, for a branch having a plurality of semi-conductors being connected in series, the electrical voltage applied to the plurality of semi-conductors is measured individually for each semi-conductor.

[0021] The gate control circuit is configured to determine, based on the determined voltage value, whether a fault condition is present. In case the fault condition is present, the gate control circuit is configured to trigger the semi-conductor into the conductive state. In theconductive state, the semi-conductor is protected from an overvoltage level and from a voltage rise that would damage the semi-conductor.

[0022] According to embodiments, the fault condition may include that the determined voltage value exceeds a predetermined voltage threshold. The determined voltage value may be representative of an amplitude of the electrical voltage applied to the semi-conductor. The predetermined voltage threshold may be infinitely adjustable.

[0023] In embodiments, the fault condition may include that a derivative of the determined voltage value exceeds a predetermined voltage rise threshold. The derivative of the determined voltage value may be representative of a derivative of the electrical voltage applied to the semi-conductor. The derivative of the determined voltage value may refer to a rise of the electrical voltage applied to the semi-conductor. The predetermined voltage rise threshold may be infinitely adjustable.

[0024] According to embodiments, the fault condition may include that the derivative of the determined voltage value exceeds the predetermined voltage rise threshold and that the determined voltage value exceeds the predetermined voltage threshold.

[0025] In embodiments, the fault condition may include that the derivative of the determined voltage value exceeds the predetermined voltage rise threshold and that the determined voltage value exceeds a second voltage threshold, wherein the second voltage threshold may be a fraction of the predetermined voltage threshold, in particular the second voltage threshold may amount to 50% to 70% of the predetermined voltage threshold.

[0026] According to embodiments, the at least one branch may include a plurality of gate- controllable semi-conductors being connected in series. Each of the plurality of semiconductors may include a gate control circuit for selectively triggering the semi-conductor into the conductive state. In embodiments, each semi-conductor of the at least one branch may selectively be triggered by a respective gate control circuit.

[0027] According to embodiments, the gate control circuit may further include a gate amplifier. The gate amplifier may amplify a pulse of the gate control circuit before delivering the pulse to the gate to trigger the semi-conductor into the conductive state.

[0028] In embodiments, the gate control circuit may further include a filter, in particular a low- pass filter. Such embodiments may avoid nuisance triggering of the semi-conductor due to measurement errors, noise, disturbance, interference or similar.

[0029] In some embodiments, the gate control circuit may be programmable. In particular, the gate driver may be programmable. As used herein, the term "programmable" may refer to the technical possibility of adapting certain characteristics of the gate control circuit, e.g. by temporarily connecting processing circuitry to the gate control circuit. In some examples, the fault condition, the gate amplifier and / or the filter may be adjustable by (re-) configuring the gate control circuit accordingly. For example, the predetermined voltage threshold, the predetermined voltage rise threshold, the second voltage threshold or alike may be adjustable.

[0030] According to another aspect of the present disclosure, a semi-conductor protection method for protecting a gate-controllable semi-conductor, in particular a thyristor, in at least one branch of a semi-conductor circuit is provided.

[0031] The method includes determining a voltage value representative of an electrical voltage applied to the semi-conductor, determining whether the voltage value fulfills a fault condition and upon presence of a fault condition being determined, triggering the semiconductor into a conductive state.

[0032] The fault condition may include that the determined voltage value exceeds a predetermined voltage threshold and / or that a derivative of the determined voltage value exceeds a predetermined voltage rise threshold. The fault condition may include that the derivative of the determined voltage value exceeds the predetermined voltage rise threshold and that the determined voltage value exceeds a second voltage threshold, wherein the second voltage threshold may be a fraction of the predetermined voltage threshold, in particular the second voltage threshold may amount to 50% to 70% of the predetermined voltage threshold.

[0033] The at least one branch may include a plurality of gate-controllable semi-conductors being connected in series. Preferably, each semi-conductor of the at least one branch may selectively be triggered by a respective gate control circuit.

[0034] The gate control circuit may include a gate amplifier. The method may include amplifying a gate signal to obtain a trigger for triggering the semi-conductor into the conductive state.

[0035] In embodiments, the method may further include filtering the voltage value, e.g. low-pass filtering the voltage value.

[0036] Reference now will be made in detail to embodiments of the disclosure, some examples of which are illustrated in the drawings. Each example may be provided by way of explanation of the disclosure, not limitation of the disclosure. For instance, features illustrated or described as part of embodiments may be used with other embodiments to yield still further embodiments. The drawings may not be true-to-scale.

[0037] FIG. 1 shows schematically a semi-conductor circuit according to embodiments of the present disclosure. The semi-conductor circuit includes at least one branch comprising at least one gate-controllable semi-conductor 110. The semi-conductor 110 may be a thyristor. In certain applications, the semi-conductor circuit may include a plurality of branches with a plurality of gate-controllable semi-conductors 110 being connected in series. Typically, the plurality of semi-conductors 110 of the branch may be vertically stacked. Other arrangements, such as a horizontal stacking, of the plurality of semiconductors 110 may also be possible.

[0038] The semi-conductor circuit has a gate control circuit 120 being connected to a gate 111 of the semi-conductor. By generating a firing pulse, the gate control circuit 120 can trigger the semi-conductor 110 into a conductive state.

[0039] The gate control circuit 120 may be implemented on a gate driver. Typically, each semiconductor of a branch has a respective gate driver. Similarly, each semi-conductor may be connected to a respective gate control circuit. The gate drivers may be connected and controlled by processing means. The gate driver and / or the gate control circuit 120 may be implemented on a printed circuit board. Similarly as the plurality of semi-conductors, the respective gate control circuits / gate drivers may also be vertically stacked and be arranged adjacent to the respective semi-conductors. In embodiments, a plurality of gate control circuits may be arranged on a single printed circuit board. Such embodiments may be advantageous, e.g., in case two semi-conductors of the semi-conductor circuit are arranged to each other in an antiparallel-manner.

[0040] The gate control circuit 120 is configured to trigger the semi-conductor 110 into the conductive state according to an operational logic 130 of the semi-conductor circuit. The operational logic 130 may include, e.g., a logic of when to trigger the semi-conductor 110into the conductive state in order to achieve, e.g. in cooperation with further semiconductors 110 and / or branches, a certain technical effect depending on the specific application. Such an application may be static power compensation, static var compensation, high-voltage rectification and / or alike.

[0041] It may take place that such a trigger generation of the operational logic 130 does not materialize due to several reasons while further semi-conductors 110 of the branch receive a firing pulse. This may lead, e.g., to overvoltage at the semi-conductor 110, that may damage or even destruct the semi-conductor 110.

[0042] In such a case, in order to protect the semi-conductor 110, it may be necessary to trigger the semi-conductor 110 into the conductive state by alternative means.

[0043] For this reason, the gate control circuit 120 includes a voltage detector that is configured to determine a voltage value representative of an electrical voltage applied to the semiconductor 110. The electrical voltage applied to the semi-conductor 110 is measured to determine the voltage value. Measurement values of the applied electrical voltage may be filtered, in-particular low-pass filtered. A filter (not shown), in particular a low-pass filter may be provided.

[0044] The gate control circuit 120 determines whether a fault condition is present based on the determined voltage value.

[0045] The fault condition includes a voltage level condition 140. In case the determined voltage value exceeds a predetermined voltage threshold, the fault condition is fulfilled. In this case, the gate control circuit 120 is configured to trigger the semi-conductor 110 into the conductive state.

[0046] Additionally or alternatively to the voltage level comparison 140, the fault condition may include a voltage rise condition 152. The voltage rise condition 152 may include a differentiator 151 for determining a derivative of the determined voltage value and a comparator for determining whether the derivative of the determined voltage value exceeds a predetermined voltage rise threshold. In case the derivative of the determined voltage value exceeds the predetermined voltage rise threshold, the fault condition is fulfilled. In this case, the gate control circuit 120 is configured to trigger the semi-conductor 110 into the conductive state.

[0047] In some embodiments and as also illustrated in Fig. 1, the fault condition may include a combined condition. The combined condition may be fulfilled in case a certain voltage value and a certain derivative of the voltage value are present at substantially the same time. For example, the combined condition may be fulfilled in case the derivative of the voltage value amounts to the predetermined voltage rise threshold or to a predetermined percentage, e.g. to at least 50%, of the predetermined voltage rise threshold, and the voltage value amounts to a predetermined percentage, e.g. to at least 60%, of the predetermined voltage threshold. The predetermined percentage of the predetermined voltage threshold may be referred to as a second voltage threshold 153. In this case, the gate control circuit 120 is configured to trigger the semi-conductor 110 into the conductive state.

[0048] To trigger the semi-conductor 110 into the conductive state, a gate signal may be generated by the gate control circuit 120. The gate signal may be amplified by a gate amplifier 160. The gate signal may be delivered to the gate 111 of the semi-conductor to set the semi-conductor into the conductive state. The gate amplifier 160 may also serve as an isolation between the gate 111 and the gate control circuit 120. The gate signal may also be referred to as, e.g. firing pulse. The gate signal may be an electrical signal, a light signal and / or alike.

[0049] The gate control circuit 120 may be connected to processing circuitry to adapt the fault condition, the gate amplifier 160 and / or the filter. For example, the fault condition, the gate amplifier 160 and / or the filter may be adjustable by (re-) configuring the gate control circuit accordingly. For example, the predetermined voltage threshold, the second voltage threshold, the predetermined voltage rise threshold a cut-off frequency of the filter, the amplification of the gate-amplifier 160 and / or alike may be adjustable.

[0050] Fig. 2 shows schematically a semi-conductor protection method for protecting a gate controllable semi-conductor 110, in particular a thyristor, in a branch of a semi-conductor circuit.

[0051] The method includes determining a voltage value representative of an electrical voltage applied to the semi-conductor 210. The voltage value may be determined based on a signal of a measurement of an electrical voltage applied to the semi-conductor 110. The signal may be filtered 211.

[0052] The method further includes to determine, based on the voltage value, whether a fault condition is fulfilled 220.

[0053] Upon presence of the fault condition being determined, a gate signal may be generated. The gate signal may be amplified 221. The method includes triggering the semi-conductor 110 into a conductive state 230.

[0054] It should be understood that, depending on the example, certain acts or events of any of the methods described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the method). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially. In addition, while certain aspects of this disclosure are described as being performed by a single circuit or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or circuits.

[0055] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0056] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0057] Thus, a semi-conductor circuit and a semi-conductor protection method for protecting a gate-controllable semi-conductor, in particular a thyristor, have been presented in theforegoing description with reference to specific examples. It is to be understood that various aspects disclosed herein may be combined in different combinations than the specific combinations presented in the accompanying drawings. It is appreciated that various modifications to the referenced examples may be made without departing from the scope of the disclosure and the following claims.

Claims

Claims1. A semi-conductor circuit, comprising at least one branch comprising at least one gate-controllable semi-conductor (110); and a gate control circuit (120) for selectively triggering the semi-conductor (110) into a conductive state; the gate control circuit (120) comprising: a voltage detector configured to determine a voltage value representative of an electrical voltage applied to the semi-conductor (110), wherein the gate control circuit (120) is configured to determine, based on the determined voltage value, the presence of a fault condition and, upon a presence of the fault condition being determined, to trigger the semi-conductor (110) into a conductive state.

2. The semi-conductor circuit according to claim 1, wherein the at least one branch comprises a plurality of gate-controllable semi-conductors (110) being connected in series.

3. The semi-conductor circuit according to any of the preceding claims, wherein the fault condition includes that the determined voltage value exceeds a predetermined voltage threshold.

4. The semi-conductor circuit according to any of the preceding claims, wherein the fault condition includes that a derivative of the determined voltage value exceeds a predetermined voltage rise threshold.

5. The semi-conductor circuit according to any of claims 2 - 4, wherein each semiconductor (110) of the at least one branch is selectively triggered by a respective gate control circuit (120).

6. The semi-conductor circuit according to any of the preceding claims, wherein the gate control circuit (120) further comprises a gate amplifier (160).

7. The semi-conductor circuit according to any of the preceding claims, wherein the gate control circuit (120) further comprises a filter, in particular a low-pass filter.

8. The semi-conductor circuit according to any of the preceding claims, wherein the gate control circuit (120) is implemented on a gate driver.

9. The semi-conductor circuit according to any of the preceding claims, wherein the at least one gate-controllable semi-conductor is a thyristor.

10. A semi-conductor protection method (200) for protecting a gate-controllable semiconductor in a branch of a semi-conductor circuit, comprising: determining a voltage value representative of an electrical voltage applied to the semi-conductor (210); determining whether the voltage value fulfills a fault condition (220); and upon a presence of the fault condition being determined, triggering the semi-conductor into a conductive state (230).

11. The method according to claim 10, wherein the at least one branch comprises a plurality of gate-controllable semi-conductors being connected in series.

12. The method according to any of claims 10 - 11, wherein the fault condition comprises that the determined voltage value exceeds a predetermined voltage threshold.

13. The method according to any of claims 10 - 12, wherein the fault condition comprises that a derivative of the determined voltage value exceeds a predetermined voltage rise threshold.

14. The method according to any of claims 10 - 13, wherein the method further comprises amplifying a gate signal (221).

15. The method according to any of claims 10 - 14, wherein the method further comprises filtering the voltage value (211).

16. The method according to any of claims 10 - 15, wherein the gate-controllable semiconductor is a thyristor.

17. An electronic device comprising a plurality of gate-controllable semi-conductors (110) being connected in series, in particular a static power compensator, a static var compensator, a high-voltage rectifier, a high voltage valve, a crow bar or a bypass, and the semi-conductor circuit according to any of claims 1 - 8.

18. The electronic device according to claim 17, wherein the plurality of gate- controllable semi-conductors is a plurality of thyristors.

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