Switch circuit, switch circuit control method, and energy storage converter

Abstract

The present disclosure relates to the technical field of energy storage control, and provides a switch circuit, a switch circuit control method, and an energy storage converter. The switch circuit comprises a static switch and a back-voltage turn-off circuit. The back-voltage turn-off circuit is electrically connected between two ends of the static switch, and is configured to provide a target current for the static switch when the static switch is turned off. The current value of the target current is greater than or equal to the current value of a turn-off current flowing through the static switch.

Description

Switching circuit, switching circuit control method and energy storage converter

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on the Chinese patent application with application number: 2023117509200 and application date of December 18, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into the present disclosure as a reference. Technical Field

[0003] The present disclosure relates to the field of energy storage control technology, and in particular to a switching circuit, a control method for the switching circuit, and an energy storage converter. Background Art

[0004] The currently common method for switching microgrid energy storage between on-grid and off-grid conditions involves continuously monitoring the grid voltage amplitude and frequency while the energy storage converter is connected to the grid. If the converter detects a grid anomaly, it disconnects the connection point switch. After the connection point switch status signal changes, the converter switches from on-grid mode to off-grid V / f mode, providing stable voltage amplitude and frequency for the loads within the microgrid. However, the connection point switches currently used in microgrid energy storage systems utilize mechanical switches with a relatively long action delay. If a connection fault occurs at the upper end of the connection point, the converter risks losing power and shutting down during the switch's shutdown delay.

[0005] Summary of the Invention

[0006] The present disclosure aims to address at least one of the technical problems existing in the prior art. To this end, the present disclosure proposes a switching circuit, a control method for the switching circuit, and an energy storage converter, which can rapidly switch between the grid-connected and off-grid states of the energy storage converter, thereby avoiding the risk of power failure and shutdown of the energy storage converter during the static switch off time.

[0007] In a first aspect, the present disclosure provides a switching circuit, comprising:

[0008] Static switch;

[0009] The reverse voltage shutdown circuit is electrically connected between two ends of the static switch and is configured to provide a target current to the static switch when the static switch is turned off, wherein the current value of the target current is greater than or equal to the current value of the shutdown current flowing through the static switch.

[0010] According to the switching circuit disclosed in the present invention, when the static switch is turned off, the reverse voltage shutdown circuit provides the static switch with a target current greater than or equal to the shutdown current value, so that the current of the static switch quickly drops from the shutdown current to zero, thereby quickly switching the static switch from the on state to the off state. By applying the static switch to the energy storage converter, the energy storage converter can be quickly switched between the grid-connected state and the off-grid state, avoiding the risk of power failure and shutdown of the energy storage converter during the off time of the static switch.

[0011] According to one embodiment of the present disclosure, the reverse voltage shutdown circuit includes multiple parallel discharge circuits, the discharge circuit includes a switch tube and a capacitor connected in series, one end of the capacitor is electrically connected to the first end of the static switch, and one end of the switch tube is electrically connected to the second end of the static switch.

[0012] According to one embodiment of the present disclosure, the switching tube is a thyristor.

[0013] According to one embodiment of the present disclosure, the multi-channel discharge circuit is divided into a first discharge circuit and a second discharge circuit, and the arrangement direction of the thyristors in the first discharge circuit is opposite to the arrangement direction of the thyristors in the second discharge circuit.

[0014] According to one embodiment of the present disclosure, the capacitors in the first discharge circuit are connected in parallel, and the capacitors in the second discharge circuit are connected in parallel.

[0015] According to an embodiment of the present disclosure, the reverse voltage shutdown circuit further includes a resistor, which is electrically connected to a connection point between the switch tube and the capacitor.

[0016] According to one embodiment of the present disclosure, the reverse voltage shutdown circuit further includes:

[0017] The fault detection circuit is electrically connected to the capacitor and is configured to detect whether the capacitor is faulty.

[0018] In a second aspect, the present disclosure provides a method for controlling a switching circuit. The method for controlling a switching circuit is applied to the above-mentioned switching circuit, and the control method includes:

[0019] When the static switch is turned off, the target current value is determined according to the current value of the off current flowing through the static switch;

[0020] The reverse voltage shutdown circuit is controlled to provide a target current for the static switch, the target current is opposite to the shutdown current, and the reverse current has a target current value.

[0021] According to the control method of the switching circuit disclosed in the present invention, when the static switch is turned off, the reverse voltage shutdown circuit provides the static switch with a target current greater than or equal to the shutdown current value, so that the current of the static switch quickly drops from the shutdown current to zero, thereby quickly switching the static switch from the on state to the off state. By applying the static switch to the energy storage converter, the energy storage converter can be quickly switched between the grid-connected state and the off-grid state, avoiding the risk of power failure and shutdown of the energy storage converter during the off time of the static switch.

[0022] According to one embodiment of the present disclosure, determining a target current value according to a current value of an off current flowing through a static switch includes:

[0023] The current margin is determined by multiplying the current value of the off current flowing through the static switch by the target percentage;

[0024] The target current value is determined by adding the current value of the off current flowing through the static switch to the current margin.

[0025] According to one embodiment of the present disclosure, the reverse voltage shutdown circuit includes multiple parallel discharge circuits, each of which includes a switch tube and a capacitor connected in series;

[0026] Controlling the reverse voltage shutdown circuit to provide the target current for the static switch includes:

[0027] Determine a target capacitance value according to a target current value;

[0028] determining a target capacitance from a plurality of capacitors according to the target capacitance value, wherein a sum of capacitance values ​​of the target capacitors is equal to the target capacitance value;

[0029] Control the switch tube connected in series with the target capacitor to turn on.

[0030] According to one embodiment of the present disclosure, determining a target capacitance from a plurality of capacitances according to a target capacitance value includes:

[0031] Obtain capacitor fault information;

[0032] Determine the capacitors that are not at fault from the capacitors according to the fault information;

[0033] A target capacitance is determined from a plurality of non-faulty capacitors according to the target capacitance value.

[0034] In a third aspect, the present disclosure provides an energy storage converter, which includes a controller and the above-mentioned switching circuit. The energy storage converter is electrically connected to the power grid through the switching circuit, and the controller is configured to implement the above-mentioned control method.

[0035] According to the energy storage converter disclosed in the present invention, when the static switch is turned off, the reverse voltage shutdown circuit provides the static switch with a target current greater than or equal to the shutdown current value, so that the current of the static switch quickly drops from the shutdown current to zero, thereby quickly switching the static switch from the on state to the off state, thereby realizing rapid switching of the energy storage converter between the grid-connected state and the off-grid state, and avoiding the risk of power failure and shutdown of the energy storage converter during the static switch off time.

[0036] Additional aspects and advantages of the present disclosure will be given in part in the description that follows and, in part, will be obvious from the description that follows, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0038] FIG1 is a schematic diagram of a switch circuit according to an embodiment of the present disclosure;

[0039] FIG2 is a second structural diagram of a switch circuit provided in an embodiment of the present disclosure;

[0040] FIG3 is a flow chart of a method for controlling a switching circuit according to an embodiment of the present disclosure;

[0041] FIG4 is a second flowchart of a method for controlling a switch circuit according to an embodiment of the present disclosure;

[0042] FIG5 is a third flowchart of the method for controlling a switch circuit provided in an embodiment of the present disclosure.

[0043] Reference numerals:

[0044] Switch circuit 100, static switch 110, reverse voltage shutdown circuit 120, first discharge loop 121, second discharge loop 122, current sensor 130, first thyristor T1, first thyristor T2, first resistor R1, second resistor R2, first capacitor group C1, second capacitor group C2.

[0045] Detailed Description of the Invention

[0046] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, and are not to be construed as limiting the present disclosure.

[0047] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or subcircuit connected electrically or electromagnetically. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled to" or "connected between" two nodes, it can be directly coupled or connected to the other element or there can be intervening elements. The connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intervening elements between the two elements.

[0048] In the description, the terms "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the numerical descriptors used in this way are interchangeable where appropriate, so that the embodiments of the present disclosure can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally indicates that the objects connected before and after are in an "or" relationship.

[0049] In addition, descriptions with reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0050] As shown in FIG1 , one embodiment of the present disclosure provides a switch circuit 100, which includes a static switch 110 and a reverse voltage shutdown circuit 120. The reverse voltage shutdown circuit 120 is electrically connected between two ends of the static switch 110 and is configured to provide a target current to the static switch 110 when the static switch 110 is turned off, wherein the current value of the target current is greater than or equal to the current value of the shutdown current flowing through the static switch 110.

[0051] The static switch 110 has two states, on and off, and can be used to control the charging and discharging process of energy storage devices (such as energy storage converters, batteries, and supercapacitors), ensuring that energy can be efficiently stored and released when needed.

[0052] The static switch 110 may include a first thyristor T1 and a second thyristor T2. The anode of the first thyristor T1 is electrically connected to the cathode of the second thyristor T2, where the connection point is the first terminal of the static switch 110. The cathode of the first thyristor T1 is electrically connected to the anode of the second thyristor T2, where the connection point is the second terminal of the static switch 110. The first terminal of the static switch 110 may be electrically connected to the power grid.

[0053] The switch circuit 100 may be disposed inside an energy storage converter, which also includes a controller. The energy storage converter is electrically connected to a power grid via the switch circuit 100 .

[0054] The controller is electrically connected to the first thyristor T1 and the second thyristor T2, respectively. It turns the first and second thyristors T1 and T2 on and off by applying drive signals to their gates. When the grid is operating normally, the controller turns the second thyristor T2 on during the positive half-cycle of the grid voltage and turns the first thyristor T1 on during the negative half-cycle.

[0055] It should be noted that the driving signal applied to the gates of the first thyristor T1 and the second thyristor T2 may be a pulse group to ensure that the first thyristor T1 and the second thyristor T2 can be successfully commutated.

[0056] When the grid is supplying power normally, the controller can control the static switch 110 to turn on and control the energy storage converter to run in parallel with the grid. When the grid fails, the controller can control the static switch 110 to turn off and control the energy storage converter to run off the grid.

[0057] The current at the moment the static switch 110 is turned off is the turn-off current. The reverse voltage turn-off circuit 120 can be used to provide the static switch 110 with a target current that is opposite to the turn-off current and has a value greater than or equal to the current value of the turn-off current when the static switch 110 is turned off. The target current can make the current value of the static switch 110 drop from the turn-off current to zero quickly, so as to achieve rapid shutdown of the static switch 110, thereby enabling the energy storage converter to quickly switch from the grid-connected state to the off-grid state, avoiding the risk of power failure and shutdown of the energy storage converter during the shutdown time of the static switch 110.

[0058] According to the switching circuit 100 disclosed herein, when the static switch 110 is turned off, the reverse voltage shutdown circuit 120 provides the static switch 110 with a target current greater than or equal to the shutdown current value, so that the current of the static switch 110 quickly drops from the shutdown current to zero, thereby quickly switching the static switch 110 from the on state to the off state. By applying the static switch 110 to the energy storage system, it is possible to achieve rapid switching between the grid-connected state and the off-grid state of the energy storage system, thereby avoiding the risk of power failure and shutdown of the energy storage converter during the off time of the static switch 110.

[0059] In some embodiments, the reverse voltage shutdown circuit 120 includes multiple parallel discharge circuits, each of which includes a switch tube and a capacitor connected in series, one end of the capacitor is electrically connected to the first end of the static switch 110, and one end of the switch tube is electrically connected to the second end of the static switch 110.

[0060] When the static switch 110 is turned on, the electric energy provided by the power grid can charge the capacitors in each discharge circuit through the static switch 110, and each switch tube is in the off state; when the static switch 110 is turned off, each switch tube switches from the off state to the on state, and the capacitors in each discharge circuit release electric energy through the corresponding switch tube, generating a target current in the opposite direction to the shutdown current, quickly reducing the shutdown current of the static switch 110 to zero, and realizing the shutdown of the static switch 110 tube.

[0061] In some embodiments, the switch is a thyristor.

[0062] The control electrodes of each thyristor are electrically connected to a controller. The controller applies a drive signal to the control electrodes of each thyristor, causing the thyristor to switch from the off state to the on state. When static switch 110 is disconnected, the controller drives the thyristor to conduct, causing the capacitors in each discharge circuit to release stored energy through the thyristor, quickly turning off static switch 110.

[0063] As shown in FIG. 2 , in some embodiments, the multiple discharge circuits are divided into a first discharge circuit 121 and a second discharge circuit 122 . The arrangement direction of the thyristors in the first discharge circuit 121 is opposite to that of the thyristors in the second discharge circuit 122 .

[0064] In the first discharge circuit 121, the anode of each thyristor is electrically connected to the corresponding capacitor, and the cathode of each thyristor is electrically connected to the first end of the static switch 110; in the second discharge circuit 122, the cathode of each thyristor is electrically connected to the corresponding capacitor, and the anode of each thyristor is electrically connected to the first end of the static switch 110.

[0065] When the grid is supplying power normally, if the grid voltage is in the positive half cycle, the grid provides power to the energy storage converter through the second thyristor T2; if the grid voltage is in the negative half cycle, the grid provides power to the energy storage converter through the first thyristor T1.

[0066] When a grid fault occurs and the static switch 110 is disconnected, if the grid voltage is in a positive half cycle, the controller controls the thyristor in the second discharge circuit 122 to be turned on, and the capacitor in the second discharge circuit 122 provides the target current; if the grid voltage is in a negative half cycle, the controller controls the thyristor in the first discharge circuit 121 to be turned on, and the capacitor in the first discharge circuit 121 provides the target current.

[0067] 2 , in some embodiments, the capacitors in the first discharge circuit 121 are connected in parallel, and the capacitors in the second discharge circuit 122 are connected in parallel.

[0068] The capacitors in the first discharge circuit 121 are connected in parallel to form a first capacitor group C1, and the capacitors in the second discharge circuit 122 are connected in parallel to form a second capacitor group C2. The first end of each capacitor in the first capacitor group C1 is electrically connected to the anode of the thyristor in the discharge circuit, and the second end of each capacitor is electrically connected to the first end of each capacitor in the second capacitor group C2. The second end of each capacitor in the second capacitor group C2 is electrically connected to the cathode of the thyristor in the discharge circuit.

[0069] When at least one thyristor in the first discharge circuit 121 is turned on, the capacitor connected in series with the turned-on thyristor provides current. The capacitance of the first discharge circuit 121 is the sum of the capacitances of all the capacitors in the first discharge circuit 121 that are turned on. The target current generated by the first discharge circuit 121 is the sum of the currents generated by all the capacitors in the first discharge circuit 121 that are turned on. Similarly, the target current generated by the second discharge circuit 122 is the sum of the currents generated by all the capacitors in the second discharge circuit 122 that are turned on.

[0070] The controller may select to turn on an appropriate number of discharge loops according to the turn-off current of the static switch 110 .

[0071] As an example, when the grid voltage is in the positive half cycle and the static switch 110 is turned off, the turn-off current is 100A. The capacitance value of each discharge circuit in the second discharge circuit 122 is the same, and each can generate a current of 20A when turned on. Therefore, the controller can control at least five discharge circuits in the second discharge circuit 122 to be turned on to generate a target current greater than or equal to 100A in the opposite direction to the turn-off current, so that the current of the static switch 110 will quickly become zero, so as to quickly turn off the static switch 110.

[0072] It should be noted that the capacitors in the first capacitor group C1 and the second capacitor group C2 may have the same or different values. The specific values ​​may be selected according to the application scenario and are not limited here.

[0073] As an example, the capacitance of each capacitor in the first capacitor group C1 and the second capacitor group C2 increases in sequence as follows: the capacitance value of the first capacitor is 1F, the capacitance value of the second capacitor is 2F, and the capacitance value of the third capacitor is 3F.

[0074] In some other embodiments, the capacitance value of each capacitor in the first capacitor group C1 and the second capacitor group C2 is 1F.

[0075] 2 , in some embodiments, the reverse voltage shutdown circuit 120 further includes a resistor, which is electrically connected to the connection point between the switch tube and the capacitor.

[0076] The resistors include a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 are connected in series with the first capacitor group C1 and the second capacitor group C2, respectively, to limit the current in the branch containing the first capacitor group C1 and the second capacitor group C2 when the static switch 110 is turned on, thereby preventing excessive charging current from burning out the capacitors in the first capacitor group C1 and the second capacitor group C2.

[0077] In some embodiments, the reverse voltage shutdown circuit 120 further includes a fault detection circuit electrically connected to the capacitor and configured to detect whether the capacitor is faulty.

[0078] The fault detection circuit is electrically connected to the controller, which stores the capacitance value of each capacitor under normal conditions. The fault detection circuit can be used to detect the capacitance value of the capacitor in real time and upload the detected capacitance value to the controller. The controller compares the capacitance value detected by the fault detection circuit with the capacitance value of each capacitor under normal conditions to detect whether the capacitor is faulty.

[0079] The controller stores the information of the faulty capacitor. The controller can drive the thyristor of the circuit where the faulty capacitor is located to be in a normally closed state. When the reverse voltage shutdown circuit 120 is running, the discharge circuit where the faulty capacitor is located is no longer called to avoid the capacitor failure affecting the operation of the reverse voltage shutdown circuit 120.

[0080] As shown in FIG3 , an embodiment of the present disclosure provides a control method for a switch circuit 100 . The control method for the switch circuit 100 is applied to the above-mentioned switch circuit 100 , and the control method includes step 10 and step 20 .

[0081] Step 10: When the static switch 110 is turned off, determine the target current value according to the current value of the off current flowing through the static switch 110;

[0082] Step 20 : Control the reverse voltage shutdown circuit 120 to provide a target current for the static switch 110 . The target current is opposite to the shutdown current, and the reverse current has a target current value.

[0083] The execution subject of the control method provided in the embodiment of the present disclosure may be the controller of the aforementioned energy storage converter or a functional module or functional entity in the controller that can implement the control method. The control method provided in the embodiment of the present disclosure is described below by taking the reverse voltage shutdown circuit 120 set in the energy storage converter and the controller as the execution subject as an example.

[0084] The reverse voltage shutdown circuit 120 is further provided with a current sensor 130 . The current sensor 130 can collect the magnitude and direction of the current flowing through the static switch 110 in real time and transmit the collected data to the controller.

[0085] It can be understood that, since the static switch 110 includes the first thyristor T1 and the second thyristor T2 , when the current flowing through the thyristors is zero, the thyristors are turned off, and thus the static switch 110 is turned off.

[0086] When the static switch 110 is normally turned on, the controller can use a pulse group to control the first thyristor T1 and the second thyristor T2 to alternately turn on according to the state of the grid voltage in the positive half cycle and the negative half axis, thereby providing power to various components in the energy storage converter.

[0087] At the moment the static switch 110 is turned off, the controller blocks the pulse group signals of the first thyristor T1 and the second thyristor T2. The current value flowing through the static switch 110 collected by the current sensor 130 is the turn-off current value. When the target current value is greater than or equal to the turn-off current value, the current of the thyristor turned on in the static switch 110 will pass through zero. Therefore, it can be determined that the target current value is greater than or equal to the turn-off current value.

[0088] The controller can calculate the target current value based on the shutdown current value collected by the current sensor 130, and control the reverse voltage shutdown circuit 120 to provide the static switch 110 with a target current in the opposite direction of the shutdown current, so that the tube current of the static switch 110 will quickly become zero, thereby realizing the rapid switching of the energy storage converter between grid connection and off-grid.

[0089] According to the control method of the switching circuit 100 disclosed in the present invention, when the static switch 110 is turned off, the reverse voltage shutdown circuit 120 provides the static switch 110 with a target current greater than or equal to the shutdown current value, so that the current of the static switch 110 quickly drops from the shutdown current to zero, thereby enabling the static switch 110 to quickly switch from the on state to the off state. By applying the static switch 110 to the energy storage converter, it is possible to achieve rapid switching between the grid-connected state and the off-grid state of the energy storage converter, thereby avoiding the risk of power failure and shutdown of the energy storage converter during the off time of the static switch 110.

[0090] As shown in FIG. 4 , in some embodiments, determining the target current value according to the current value of the turn-off current flowing through the static switch 110 includes step 11 and step 12 .

[0091] Step 11: multiply the current value of the off current flowing through the static switch 110 by the target percentage to determine the current margin;

[0092] Step 12: Add the current value of the turn-off current flowing through the static switch 110 to the current margin to determine the target current value.

[0093] It is understandable that the reverse voltage shutdown circuit 120 is provided with components such as resistors, which consume a portion of the current. Therefore, the target current of the reverse voltage shutdown circuit 120 is provided with a current margin, that is, the target current value is greater than the shutdown current value.

[0094] The controller is set with a target percentage, and the controller multiplies the shutdown current value collected by the current sensor 130 by the target percentage to obtain the current margin. The controller adds the current margin to the shutdown current value collected by the current sensor 130 to obtain the target current value.

[0095] The controller controls the reverse voltage shutdown circuit 120 to provide a current having a target current value and a direction opposite to the shutdown current, so as to ensure that the current of the static switch 110 can be reduced to zero.

[0096] As an example, the target percentage set in the controller is 20%, and the shutdown current value collected by the current sensor 130 is 1000 A, then the current margin = 1000 A * 20% = 200 A. Target current value = 1000 A + 200 A = 1200 A.

[0097] As shown in FIG5 , in some embodiments, the reverse voltage shutdown circuit 120 includes multiple parallel discharge circuits, each of which includes a switch tube and a capacitor connected in series. Controlling the reverse voltage shutdown circuit 120 to provide a target current for the static switch 110 includes steps 21 , 22 , and 23 .

[0098] Step 21: determining a target capacitance value according to a target current value;

[0099] Step 22: determining a target capacitance from a plurality of capacitors according to the target capacitance value, wherein the sum of the capacitance values ​​of the target capacitors is equal to the target capacitance value;

[0100] Step 23: Control the switch tube connected in series with the target capacitor to be turned on.

[0101] From the relationship between current and capacitance I = C*U / t, it can be seen that the ratio of the current passing through the capacitor per unit time to the amount of charge stored in the capacitor is proportional to the potential difference across the capacitor, where U is the grid voltage. Therefore, the target capacitance value can be determined based on the target current value.

[0102] The controller selects the target capacitor group to be turned on according to the state of the grid. If the grid voltage is in the positive half cycle, the controller controls the thyristors in the second discharge circuit 122 to be turned on, and the capacitors in the second capacitor group C2 provide the target current. If the grid voltage is in the negative half cycle, the controller controls the thyristors in the first discharge circuit 121 to be turned on, and the capacitors in the first capacitor group C1 provide the target current.

[0103] After determining the target capacitor group to be turned on, the controller selects one or more appropriate target capacitors according to the target capacitance value, and controls the thyristors of the discharge circuit where the target capacitors are located to turn on, so that the target capacitors release a target current in the opposite direction to the turn-off current, so as to reduce the current flowing through the static switch 110 to zero.

[0104] As an example, the target capacitor group is the first capacitor group C1, and the capacitors in the first capacitor group C1 are arranged in sequence according to the size of the first capacitor 1F, the second capacitor 2F, the third capacitor 3F... If the target capacitance is 4F, the thyristors connected in series with the first capacitor and the third capacitor can be turned on respectively, or only the thyristor connected in series with the fourth capacitor can be turned on.

[0105] In some embodiments, determining a target capacitance from multiple capacitors according to a target capacitance value includes: obtaining fault information of the capacitor; determining a non-faulty capacitor from the capacitor according to the fault information; and determining the target capacitance from multiple non-faulty capacitors according to the target capacitance value.

[0106] The controller controls the fault detection circuit to detect the capacitance values ​​of the first capacitor group C1 and the second capacitor group C2 in real time, and compares the detected capacitance values ​​with the capacitance values ​​of the capacitors in their normal state to obtain capacitor fault information. The controller then sets the thyristors in the discharge circuits of the faulty capacitors to a normally closed state. The controller records the capacitors that have not failed and selects one or more capacitors whose total capacitance values ​​meet the target capacitance value from the capacitors that have not failed as target capacitance as the target capacitors.

[0107] In other embodiments, the controller may first determine one or more capacitors as target capacitors from the target capacitor group based on the target capacitance value, and then control the fault detection circuit to detect the selected target capacitor to determine whether the target capacitor has a fault. If there is no fault, the thyristor connected in series with the target capacitor is normally turned on. If there is a fault in the target capacitor, the controller controls a capacitor with the same capacitance as the faulty capacitor to replace the faulty capacitor, and controls the fault detection circuit to perform fault detection on the selected target capacitor until there is no fault in the target capacitor.

[0108] This prevents the faulty capacitor from being unable to discharge and generate current, so that the current of the static switch 110 cannot be reduced to zero, thereby affecting the switching of the energy storage converter between the grid-connected state and the off-grid state.

[0109] An embodiment of the present disclosure provides an energy storage converter, which includes a controller and the aforementioned switching circuit. The energy storage converter is electrically connected to a power grid via the switching circuit, and the controller is configured to implement the aforementioned control method.

[0110] The controller in the energy storage converter can quickly shut down the static switch 110 by executing the above control method, thereby quickly switching from the grid-connected state to the off-grid state. Specific implementation methods can refer to the above embodiments and will not be repeated here.

[0111] According to the energy storage converter disclosed herein, when the static switch 110 is turned off, the reverse voltage shutdown circuit provides the static switch 110 with a target current greater than or equal to the shutdown current value, so that the current of the static switch 110 quickly drops from the shutdown current to zero, thereby enabling the static switch 110 to quickly switch from the on state to the off state, thereby realizing rapid switching between the grid-connected state and the off-grid state of the energy storage converter, and avoiding the risk of power failure and shutdown of the energy storage converter during the off time of the static switch 110.

[0112] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present disclosure is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0113] Although the embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A switching circuit, wherein: include: Static switch; The reverse voltage shutdown circuit is electrically connected between two ends of the static switch and is configured to provide a target current for the static switch when the static switch is turned off, wherein the current value of the target current is greater than or equal to the current value of the shutdown current flowing through the static switch.

2. The switch circuit according to claim 1, wherein: The reverse voltage shutdown circuit includes a multi-channel parallel discharge circuit, and the discharge circuit includes a switch tube and a capacitor connected in series, one end of the capacitor is electrically connected to the first end of the static switch, and one end of the switch tube is electrically connected to the second end of the static switch.

3. The switch circuit according to claim 2, wherein: The switch tube is a thyristor.

4. The switch circuit according to claim 3, wherein: The multiple discharge circuits are divided into a first discharge circuit and a second discharge circuit, and the arrangement direction of the thyristors in the first discharge circuit is opposite to the arrangement direction of the thyristors in the second discharge circuit.

5. The switch circuit according to claim 4, wherein: The capacitors in the first discharge circuit are connected in parallel, and the capacitors in the second discharge circuit are connected in parallel.

6. The switch circuit according to any one of claims 2 to 5, wherein: The reverse voltage shutdown circuit also includes a resistor, which is electrically connected to a connection point between the switch tube and the capacitor.

7. The switch circuit according to any one of claims 2 to 6, wherein: The reverse voltage shutdown circuit further includes: The fault detection circuit is electrically connected to the capacitor and is configured to detect whether the capacitor is faulty.

8. A method for controlling a switch circuit, wherein: Applied to the switch circuit according to any one of claims 1 to 7, the control method comprises: When the static switch is turned off, determining the target current value according to the current value of the turn-off current flowing through the static switch; The reverse voltage shutdown circuit is controlled to provide a target current for the static switch, wherein the target current is opposite to the shutdown current, and the reverse current has the target current value.

9. The control method according to claim 8, wherein: The step of determining the target current value according to the current value of the off current flowing through the static switch comprises: Multiplying the current value of the off current flowing through the static switch by the target percentage to determine the current margin; The current value of the off current flowing through the static switch is added to the current margin to determine a target current value.

10. The control method according to claim 8 or 9, wherein: The reverse voltage shutdown circuit includes multiple discharge circuits connected in parallel, and the discharge circuit includes a switch tube and a capacitor connected in series; The control reverse voltage shutdown circuit provides a target current for the static switch, including: Determining a target capacitance value according to the target current value; determining a target capacitance from a plurality of the capacitors according to the target capacitance value, wherein a sum of capacitance values ​​of the target capacitances is equal to the target capacitance value; The switch tube connected in series with the target capacitor is controlled to be turned on.

11. The control method according to claim 10, wherein: The step of determining a target capacitance from a plurality of the capacitances according to the target capacitance value comprises: Obtaining fault information of the capacitor; Determine a non-faulty capacitor from the capacitors according to the fault information; A target capacitance is determined from the plurality of non-faulty capacitors according to the target capacitance value.

12. An energy storage converter, wherein: The energy storage converter comprises a controller and a switch circuit according to any one of claims 1-7, the energy storage converter is electrically connected to a power grid via the switch circuit, and the controller is configured to implement a control method according to any one of claims 8-11.

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