Electronic circuits and methods for operating electronic circuits

Abstract

This invention provides electronic circuits and methods for operating them. [Solution] An electrical circuit (1) comprising a power thyristor (2) device (2) is described. The gate (21) of the power thyristor device (2) is connected to an internal reference (10) of the electrical circuit (1) via a first switch (31), and the cathode (22) of the power thyristor device (2) is connected to an internal reference (10) of the electrical circuit (1) via a second switch (32). Furthermore, a method (1) for operating the electrical circuit is described.

Description

Technical Field

[0001] The present disclosure relates to an electrical circuit and a method of operating the electrical circuit.

Background Art

[0002] Thyristors are optimal for power applications because they can be used to switch high-current and / or high-voltage electrical signals.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Embodiments of the present disclosure relate to a method of improving the capabilities of an electrical circuit including a thyristor device.

Means for Solving the Problems

[0004] According to an embodiment, an electrical circuit includes a power thyristor device, and a gate of the power thyristor device is connected to an internal reference of the electrical circuit via a first switch. A cathode of the power thyristor device is connected to the internal reference of the electrical circuit via a second switch.

[0005] Thus, when the first switch and the second switch are in a conductive on-state, the gate is electrically connected to the cathode. The first switch and the second switch can ensure that the blocking capability of the power thyristor device is always maintained. In particular, the blocking capability can be maintained during the start-up mode and the stop or fault mode of the electrical circuit.

[0006] During normal operation of the electrical circuit, the first switch and / or the second switch can be electrically turned off (or in a blocked state) so that there is no low-impedance connection between the cathode and the gate of the power thyristor device.

[0007] For example, a power thyristor device is configured to operate with a high current of at least 100A and / or a high voltage of at least 1000V.

[0008] The internal reference of an electrical circuit is, in particular, the power level that all power supply voltages in the electrical circuit refer to. Specifically, the internal reference may be both a positive and a negative voltage level. The internal reference may be at ground potential or isolated from ground potential.

[0009] According to another embodiment of the electrical circuit, the power thyristor device is a gate commutation type thyristor.

[0010] The gate-commutated thyristor can be switched on or off by a gate signal applied to its gate.

[0011] In other embodiments of the electrical circuit, the first switch and / or the second switch are semiconductor elements. Since semiconductor elements are not affected by vibration, they can provide extremely reliable switches. Semiconductor elements are particularly less affected by vibration than relays.

[0012] In particular, the first switch and / or the second switch may be normally-on semiconductor elements. Therefore, the first switch and / or the second switch are conductive when no voltage is applied to their respective gates.

[0013] If both the first and second switches are normally-on semiconductor devices, the electrical circuit electrically connects the cathode and gate of a power thyristor device in case no voltage is applied to the gates of these switches. This helps ensure the power thyristor device's complete shutoff capability in the event that the gate of the power thyristor device becomes unpowered.

[0014] In other embodiments of the electrical circuit, the first and second switches are depletion-mode n-channel field-effect transistors, such as MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors). This type of transistor is conductive when no voltage is applied to its gate.

[0015] A depletion-mode n-channel field-effect transistor can be turned off by applying a negative voltage between the gate and source of the transistor.

[0016] In another embodiment of the electrical circuit, a resistor configured to limit the discharge current is placed in the current path through a second switch between the cathode and an internal reference. The resistor will limit the discharge current when the electrical circuit is shut down. For example, the resistor is placed between the cathode and the second switch. For example, the resistance of the resistor is at least 0.1Ω, or at least 1Ω. Alternatively, or in addition to this, the resistance may be up to 30Ω, up to 20Ω, or up to 7Ω. Alternatively, or in addition to this, the gate voltage of the second switch may be controlled to limit the discharge current. In this case, the resistor may be omitted, or the resistor may be used as a shunt resistor.

[0017] According to another embodiment of the electrical circuit, the electrical circuit further comprises a gate control unit configured to control the gate of a power thyristor, a first switch, and a second switch. The gate control unit may provide one or more power supplies with different voltage levels, and / or monitoring and control logic and / or a driver and / or a trigger circuit and / or a back porch circuit or other active or passive components. For example, the gate control unit is configured to provide different pulse patterns in different operating modes. That is, the electrical circuit is configured to operate in multiple operating modes.

[0018] According to another embodiment of the electrical circuit, the electrical circuit is configured as an integrated gate commutation thyristor (IGCT). The IGCT comprises a power thyristor device and a gate section, in particular, for controlling the power thyristor device.

[0019] However, in contrast to conventional IGCTs, high DC interruption and / or dV / dt robustness can be provided in all operating modes using the first and second switches of the electrical circuit, especially when the IGCT is unpowered or the gate voltage is off.

[0020] According to another embodiment of the electrical circuit, the electrical circuit further comprises a capacitor section connected to the gate via a third switch. In particular, the capacitor section is configured to provide a switch-off current to the gate of the thyristor device. For example, the capacitor section comprises a plurality of capacitors electrically connected in parallel.

[0021] For example, the gate control unit is configured to control the third switch. According to another embodiment of the electrical circuit, the third switch comprises normally-off semiconductor elements. For example, the third switch comprises a plurality of semiconductor elements electrically connected in parallel.

[0022] For example, a normally-off semiconductor device is an enhancement-mode field-effect transistor. Therefore, as long as there is charge in the thyristor device, the capacitor is discharged to some extent when the third switch is in the ON state. That is, the charge emanating from the capacitor is equal to, or approximately equal to, the charge between the gate and cathode inside the thyristor device.

[0023] Furthermore, the capacitor section can discharge, for example, through a resistor, when the second switch is in the ON state.

[0024] The electrical circuit may be configured to operate in different operating modes, such as a start mode and / or a normal operation mode and / or a stop or fault mode.

[0025] During all of these operating modes, particularly, the full blocking ability of the power thyristor device can be ensured by a pulse pattern that shorts between the gate and the cathode of the power thyristor device when necessary.

[0026] Furthermore, a method of operating the above-described electrical circuit will be described. According to an embodiment of the electrical circuit, the electrical circuit is operated in a start mode, and after the capacitor is charged, the first switch turns off. In particular, the second switch is already off when the first switch turns off.

[0027] After the first switch turns off, the electrical circuit can be operated in a normal operation mode. In the normal operation mode, the power thyristor device can be turned on and off by applying an appropriate signal to the gate of the power thyristor device.

[0028] According to another embodiment of the method, the second switch turns off before the first switch turns off. In particular, the second switch may turn off before the capacitor unit is charged.

[0029] During the start mode, the on state of the first switch ensures the blocking ability of the power thyristor device. During normal operation, the power thyristor device can be switched off by discharging the capacitor unit to some extent through the third switch. The charge coming out of the capacitor unit may be equal to or approximately equal to the charge between the gate and the cathode inside the thyristor device. Furthermore, the thyristor device can be turned on when a signal is applied from the gate control unit to the gate of the thyristor device.

[0030] According to another embodiment of the method, the electrical circuit is operated in a stopped or faulty mode, and the first and second switches are turned ON when the capacitor section has discharged at least to some extent.

[0031] At the start of the discharge process, the capacitor section may provide sufficient power to operate the gate control section. If the power decreases, it will no longer be sufficient to maintain or deliver the back-porch current or to turn on the power thyristor device. In this case, the gate section will no longer respond to the input signal.

[0032] If the power thyristor device is in the ON state, the gate control unit turns off the power thyristor device by turning on its off-channel via the third switch.

[0033] Furthermore, when the first switch becomes conductive, the gate is electrically connected to the internal reference.

[0034] Furthermore, when the second switch is turned on, the cathode is connected to the internal reference. This occurs before, during, or shortly after the power loss in the gate control unit's control logic. In this state, any remaining charge in the capacitor is discharged.

[0035] According to another embodiment of the method, in a stop or failure mode, the first switch turns ON before the second switch.

[0036] Therefore, the gate is connected to the internal reference before the cathode. With an appropriate pulse pattern, this method ensures good DC interruption capability and high dV / dt robustness in all operating modes of the electrical circuit. In particular, it can guarantee reliable shielding operation of the power thyristor device when the electrical circuit is unpowered and / or when there is no voltage applied to the gate.

[0037] Furthermore, the electrical circuit is black-start resistant. This means that, in particular, the unpowered gate of the power thyristor device is capable of withstanding a voltage ramp with a slope of at least 100V / μs.

[0038] Therefore, the first and second switches ensure a low-impedance connection between the gate and cathode of the power thyristor device under the condition that no power is supplied to the gate. In particular, the black start function requires no power or any kind of energy storage.

[0039] For example, the electrical circuit may be configured for high-voltage direct current (HVDC) power transmission applications. For example, electrical circuit 1 may be configured for a modular multilevel converter (MMC).

[0040] The characteristics and advantages described for electrical circuits also apply to methods, and the characteristics and advantages described for methods also apply to electrical circuits.

[0041] As long as the embodiments are not contradictory, each feature described in one embodiment can be combined with one or more features described in another embodiment.

[0042] For further understanding, please refer to the attached drawings. In the drawings, elements of the same structure and / or function may be referred to by the same reference numerals. Please understand that the embodiments shown in the drawings are illustrative and not necessarily drawn to scale. [Brief explanation of the drawing]

[0043] [Figure 1] A schematic diagram of the electrical circuit according to the embodiment is shown. [Figure 2] A schematic diagram of the electrical circuit according to the embodiment is shown. [Figure 3] This figure illustrates a pulse pattern in the start mode according to an embodiment of an electrical circuit operation method. [Figure 4]This figure illustrates a pulse pattern during a stop or failure mode, according to an embodiment of an electrical circuit operation method. [Modes for carrying out the invention]

[0044] This disclosure is applicable to a variety of modifications and alternative forms, the details of which are shown in the drawings as examples and will be described in detail thereafter. However, it should be understood that the intent is not to limit this disclosure to the specific embodiments described. Rather, the intent is to cover all modifications, equivalents, and substitutions that fall within the scope of this disclosure as set forth by the appended claims.

[0045] In the exemplary embodiment shown in Figure 1, the electrical circuit 1 includes a power thyristor device 2, the gate 21 of the power thyristor device 2 is connected to the internal reference 10 of the electrical circuit 1 via a first switch 31, and the cathode 22 of the power thyristor device 2 is connected to the internal reference 10 of the electrical circuit 1 via a second switch 32.

[0046] Therefore, when the first switch 31 and the second switch 32 are in a conductive ON state, the gate 21 and cathode 22 of the power thyristor device 2 are connected to the same internal reference 10 of the electrical circuit 1.

[0047] In the exemplary embodiment shown in Figure 1, the first switch 31 and the second switch 32 are normally-on semiconductor devices, such as depletion-mode n-channel MOSFETs.

[0048] In Figure 1, the internal reference 10 is at ground potential. However, this is not essential. Rather, the internal reference may be electrically isolated from ground.

[0049] The electrical circuit 1 further includes a capacitor section 7. During normal operation of the electrical circuit 1, the capacitor section 7 may provide a current to switch the power thyristor device 2 off when the third switch 33 located on the off-channel line 53 is in the ON state.

[0050] In contrast, the first switch 31 and the second switch 32 are in the off state during normal operation of the electrical circuit 1.

[0051] However, in start mode and / or stop or failure mode, the first switch 31 and the second switch 32 may be in a conductive ON state that electrically connects the cathode 22 and gate 21 of the power thyristor device 2, ensuring the power thyristor device's ability to shut off during these operating modes.

[0052] This will be explained in more detail with reference to Figures 3 and 4. The electrical circuit 1 further includes a resistor 6 positioned in the current path through a second switch between the cathode 22 of the electrical circuit 1 and the internal reference 10.

[0053] For example, the resistance value of resistor 6 is in the range of 0.1Ω to 20Ω. The explanation for Figure 1 also applies to Figure 2. Figure 2 is a diagram that further illustrates the details of electrical circuit 1, which is configured as an integrated gate commutation type thyristor.

[0054] The electrical circuit 1 comprises a power thyristor device 1 and a gate unit 4 having a gate control unit 40.

[0055] For example, the gate control unit 40 includes one or more power supplies. Furthermore, the gate control unit 40 may include, for example, monitoring and control logic and / or a driver and / or a trigger circuit and back porch circuit. When the electrical circuit 1 is in operation, the electrical circuit 1 is externally connected via an input power line 41. Furthermore, the gate control unit 40 is configured to receive an input signal 42 and output an output signal 43.

[0056] The cathode wire 52 connects the gate control unit 40 to the cathode 22 of the power thyristor device. The gate wire 51 connects the gate control unit 40 to the gate 21 of the power thyristor device 2.

[0057] Furthermore, the gate section 4 includes the first switch 31, the second switch 32, the third switch 33, and the capacitor section 7, as described in Figure 1. In particular, the electrical circuit is configured to be able to operate in different operating modes.

[0058] The third switch 33 is a normally-off semiconductor device. During normal operation of the electrical circuit 1, the power thyristor device 2 can be switched off by applying a gate voltage to the gate of the third switch 33.

[0059] Figure 3 illustrates the pulse pattern of electrical circuit 1 in its startup mode. This figure schematically shows the gate power 80, the signal level 81 at the second switch, the signal level 82 at the first switch, the off-channel signal level 83, and the capacitor voltage 84 with a maximum voltage 840 as time progresses.

[0060] The start mode 85 is indicated by an arrow extending between dashed lines. In start mode, the capacitor 9 is charged. After that, the electrical circuit becomes operable in normal operation mode 86.

[0061] As shown in Figure 3, first, the power 80 of the gate section is activated and supplied to the gate control unit 40.

[0062] Subsequently, the second switch 32 is switched off by the HIGH signal applied to its gate. As indicated by the capacitor voltage 84, the capacitor section 9 is fully charged in the start mode 85.

[0063] The off-channel 83 is turned on (HIGH signal) before, during, or after charging of the capacitor section 7, and at least before the IGCT enters the operating state (arrow 86). This is illustrated by the shaded area. The other shaded area illustrates that the power thyristor device 2 can be directly turned on at the start of normal operation mode 86 if the signal corresponding to the IGCT is applied in the start mode. For example, this signal may be received as an optical signal via fiber. Subsequently, the off-channel 83 (third switch) is turned off and a gate signal is applied. For example, a trigger current and a back-porch current are applied to the gate of the power thyristor device 2.

[0064] After the capacitor section 7 is charged and the applied HIGH signal causes the off-channel 83 (third switch) to enter conductive mode, the first switch 31 turns off (HIGH signal). When the capacitor section 7 is fully charged, the electrical circuit 1 can operate normally. In normal operation, the power thyristor device 2 is turned on or off by switching the third switch 33 to a conductive state, or the gate control unit 40 applies an arbitrary trigger current or back-porch current to turn the power thyristor on or keep it on.

[0065] It goes without saying that the gate control unit 40 may perform other functions and / or provide other signals such as a retriggering signal.

[0066] Figure 4 shows an example of a pulse pattern in the stop or failure mode of electrical circuit 1. Stop 87 is indicated as an arrow extending between two dashed lines.

[0067] In stop or failure mode 87, the capacitor section 7 is discharged as indicated by the capacitor voltage 84. At the start of the discharge process, the off-channel signal 83 may be HIGH or LOW. This is shown by the shaded area in Figure 4.

[0068] When the capacitor voltage 84 drops to a certain value, the electrical circuit 1 becomes unable to maintain or deliver back porch current, or is unable to turn on the power thyristor device 2. The gate control unit 40 becomes unable to respond to the input signal.

[0069] When the gate 21 of the power thyristor device 2 is ON due to the applied signal, the gate control unit 4 turns off the power thyristor device 2 by turning on the off channel. Subsequently, the first switch 31 becomes conductive ON (LOW signal), electrically connecting the gate 21 of the power thyristor device 2 to the internal reference 10.

[0070] When the second switch 32 switches to the conductive ON state (LOW signal), a short circuit occurs between the cathode 22 and the internal reference 10. This occurs before, during, or shortly after power loss in the control logic. At this point, the off-channel signal level 83 switches to the LOW level, and the third switch 33 turns OFF.

[0071] The remaining charge in the capacitor section 7 may be discharged through the second switch 32 and the resistor 6. The resistor 6 may be omitted. For example, the discharge current may be limited by applying an appropriate signal to the gate of the second switch 32.

[0072] The different operating modes demonstrate that electrical circuit 1 provides reliable DC interruption and / or dV / dt robustness capability for all operating modes.

[0073] Furthermore, electrical circuit 1 fully supports black start, which is necessary for various applications. In particular, the black start function requires no power or any type of energy storage.

[0074] Electrical circuit 1 may be configured for HVDC applications. For example, electrical circuit 1 may be configured for a modular multilevel converter.

[0075] The embodiments shown in Figures 1 to 4 are illustrative examples of the improved electrical circuits and methods, and do not constitute a complete list of all embodiments relating to the improved electrical circuits and methods. Actual electrical circuits and methods may differ from the embodiments shown, for example, in terms of layout, electrical components, and signals.

[0076] Reference sign 1. Electrical Circuit 10 Internal References 2 Power Thyristor Devices Gate 21 22 Cathode 23 Anodes 31. Switch 1 32 Second switch 33 Third switch 4 Gate section 40 Gate control unit 41 Input power lines 42 Input Signals 43 Output signal 51 Gate Line 52 Cathode wire 53 Off-channel lines 6 resistor 7 Capacitor section 80 Power of the gate section 81 Signal level at the second switch 82 Signal level at the first switch 83 Off-channel signal level 84 Capacitor Voltage 840 Maximum Voltage 85 Start Mode 86 Normal Mode 87 Stop or failure mode

Claims

1. Electrical circuit (1), The power thyristor (2) device (2) is equipped with The gate (21) of the power thyristor device (2) is connected to the internal reference (10) of the electrical circuit (1) via the first switch (31). The cathode (22) of the power thyristor device (2) is connected to the internal reference (10) of the electrical circuit (1) via a second switch (32) in the electrical circuit.

2. The electrical circuit according to claim 1, wherein the power thyristor device (2) is a gate commutation type thyristor.

3. The electrical circuit according to claim 1 or 2, wherein the first switch (31) and the second switch (32) are normally-on semiconductor elements.

4. The electrical circuit according to any one of the preceding claims, wherein the first switch (31) and the second switch (32) are depletion-mode n-channel field-effect transistors.

5. The electrical circuit according to any one of the preceding claims, wherein a resistor (6) configured to limit the discharge current is placed in the current path through the second switch (32) between the cathode (22) and the internal reference (10).

6. The electrical circuit (1) further comprises a gate control unit (40) configured to control the gate (21) of the power thyristor device (2), the first switch (31), and the second switch (32), according to any one of the preceding claims.

7. The electrical circuit (1) is configured as an integrated gate commutation type thyristor, as described in any one of the preceding claims.

8. The electrical circuit (1) further comprises a capacitor section (7) connected to the gate (21) via a third switch (33), as described in any one of the preceding claims.

9. The electrical circuit according to claim 8, wherein the third switch (33) comprises a normally-off semiconductor element.

10. The method for operating the electrical circuit (1) according to claim 8 or 9, wherein the electrical circuit (1) is capable of operating in multiple operating modes.

11. The method according to claim 10, wherein the electrical circuit (1) is operated in start mode (85), and the first switch (31) is turned off after the capacitor (7) has been charged.

12. The method according to claim 11, wherein the second switch (32) turns off before the first switch (31) turns off.

13. The method according to claim 11, wherein the electrical circuit (1) is operated in a stop or failure mode (87), and the first switch (31) and the second switch (32) are turned ON when the capacitor portion (7) has discharged to at least a certain extent.

14. The method according to claim 13, wherein the first switch (31) turns ON before the second switch (32).

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