Filter capacitor charging circuit, monitoring system and monitoring processing method

Abstract

The present application relates to a filter capacitor charging circuit, a monitoring system and a monitoring processing method, and belongs to the field of power supply filtering technology. The present application includes: a filter capacitor module, having at least one charging input terminal; at least one controllable resistor, wherein each charging input terminal of the filter capacitor module is connected in series with a controllable resistor; a controllable switch module, wherein the controllable switch module has at least one switch unit, and each controllable resistor is connected to a switch unit. Through the present application, it is helpful to solve the problem of filter capacitor charging current impact during filter power supply filtering while ensuring the filtering effect of the filter.

Description

Technical Field

[0001] The present application belongs to the field of power supply filtering technology, and specifically relates to a filter capacitor charging circuit, a monitoring system and a monitoring processing method. Background Art

[0002] At present, in the fields of high-power inverters, converters, and frequency converters, in order to reduce the high-frequency harmonic interference generated by nonlinear loads on the AC power grid side, designers are gradually popularizing the use of LC and LCL filters in the main circuit. However, whether it is an LC filter or an LCL filter, the pre-charging of the capacitor at startup is an important part of the equipment safety protection. In order to reduce the instantaneous impact current of capacitor charging, protect the safety of the equipment, and reduce the harmonic interference of the equipment to the power grid, the method of connecting high-power resistors in series with filter capacitors is now generally used. Please refer to Figure 1 , Figure 1 This is a schematic diagram of the electrical structure of an LCL filter in the related art according to an exemplary embodiment. However, in this way, due to the existence of the resistor, the filtering effect of the filter is weakened. Other designers choose the right time to short-circuit the resistor through the contactor after starting up. Please refer to Figure 2 , Figure 2 It is a schematic diagram of the electrical structure of the LCL filter in the related technology shown according to another exemplary embodiment. The resistor is short-circuited by a contactor. However, in this way, if the resistance value of the resistor is too small, the impact current cannot be effectively weakened. If the resistance is too large, there is a phase difference between the capacitor voltage and the grid side voltage before and after the resistor is short-circuited, which generates an impact current. Both cannot effectively solve the problem of charging current impact. Summary of the invention

[0003] In order to overcome the problems existing in the related art at least to a certain extent, the present application provides a filter capacitor charging circuit, a monitoring system and a monitoring processing method, which helps to solve the problem of filter capacitor charging current impact during filter power supply filtering while ensuring the filtering effect of the filter.

[0004] To achieve the above objectives, this application adopts the following technical solutions:

[0005] First,

[0006] The present application provides a filter capacitor charging circuit, comprising:

[0007] The filter capacitor module has at least one charging input terminal;

[0008] At least one controllable resistor, wherein each charging input terminal of the filter capacitor module is connected in series with the controllable resistor;

[0009] A controllable switch module, wherein the controllable switch module has at least one switch unit, and each of the controllable resistors corresponds to and is connected to the switch unit.

[0010] Furthermore, the controllable switch module is a contactor, wherein the contactor has at least one main contact, and both ends of each controllable resistor are connected to the main contact.

[0011] Furthermore, the filter capacitor module has three filter capacitors, and the three filter capacitors form a triangle connection or a star connection.

[0012] Furthermore, the filter capacitor charging circuit is an LC filter capacitor charging circuit or an LCL filter capacitor charging circuit.

[0013] Furthermore, the filter capacitor charging circuit also includes:

[0014] At least one current sampling element, wherein the current sampling element is configured on the circuit corresponding to each of the charging input terminals of the filter capacitor module;

[0015] At least one voltage sampling element, wherein the voltage sampling element is configured on the circuit corresponding to each of the charging input terminals of the filter capacitor module and is configured between the charging input terminal and the controllable resistor;

[0016] A charging controller, each of the current sampling elements, each of the voltage sampling elements and the controllable switch module are respectively connected to the charging controller.

[0017] Furthermore, the current sampling element is configured on a circuit located at an input side of the controllable resistor.

[0018] Furthermore, the charging controller adopts a PLC controller.

[0019] Second,

[0020] The present application provides a filter capacitor charging monitoring system, comprising:

[0021] A filter capacitor charging circuit as described in any one of the above; and

[0022] A main controller is connected to the charging controller.

[0023] Furthermore, the filter capacitor charging monitoring system also includes: a controlled device connected to the main controller.

[0024] Furthermore, the controlled device includes one or more of an inverter, a frequency converter and a current converter.

[0025] Thirdly,

[0026] The present application provides a filter capacitor charging monitoring processing method, the method is applied to the charging controller in the filter capacitor charging monitoring system as described in any one of the above items, the method comprising:

[0027] After receiving the power-on instruction of the main controller, obtaining the sampled current sampled by each current sampling element, and obtaining the resistance value of each controllable resistor;

[0028] Calculating the voltage difference between the capacitor side and the grid side of the filter capacitor module according to each of the sampled currents and the resistance value of each of the controllable resistors;

[0029] If the calculated voltage difference reaches a set value, controlling the controllable switch module to close each of the switch units;

[0030] If the calculated voltage difference does not reach the set value, each of the controllable resistors is adjusted to make the voltage difference reach the set value, and when the voltage difference reaches the set value, the controllable switch module is controlled to turn off each of the switch units.

[0031] Further, calculating the voltage difference between the capacitor side and the grid side of the filter capacitor module according to each of the sampled currents and the resistance value of each of the controllable resistors includes:

[0032] Calculate the difference between the instantaneous line voltages of any two phases between the capacitor side of the filter capacitor module and the grid side according to the sampled currents and the resistance values ​​of the controllable resistors;

[0033] The mean value is calculated according to the maximum value of the difference between the instantaneous line voltages of any two phases of electricity, and the calculated mean value difference is used as the voltage difference.

[0034] Further, the adjusting each of the controllable resistors so that the voltage difference reaches the set value includes:

[0035] Obtaining the maximum instantaneous current of each of the sampled currents, and calculating the average current;

[0036] The controllable resistors are adjusted according to the mean current and a preset control curve so that the voltage difference reaches the set value.

[0037] Furthermore, the method further comprises:

[0038] If the controllable resistor is adjusted to the minimum, the controllable switch module is controlled to close each of the switch units.

[0039] Furthermore, the method further comprises:

[0040] After the charging controller is powered on, an initialization operation is performed to adjust each of the controllable resistors to a maximum resistance value and to place each switch unit in a disconnected state;

[0041] After determining that the master controller is initialized, the voltage is sampled through each of the voltage sampling elements, and the current is sampled through each of the current sampling elements, and the power-on instruction of the master controller is waited.

[0042] Furthermore, the method further comprises:

[0043] Acquiring a sampling voltage sampled by each of the voltage sampling elements;

[0044] The instantaneous line voltage of any two-phase electricity on the capacitor side of the filter capacitor module is calculated according to each of the sampled voltages, and the instantaneous line voltage of each two-phase electricity on the grid side is calculated by combining the difference in the instantaneous line voltage of each two-phase electricity between the capacitor side of the filter capacitor module and the grid side.

[0045] This application adopts the above technical solution, which has at least the following beneficial effects:

[0046] The present application sets a controllable resistor in series on the lines corresponding to each charging input terminal of the filter capacitor module, and connects each controllable resistor in parallel to each switch unit of the controllable switch module, and initially sets the controllable resistor at the maximum resistance position. When the filter power is filtered, the impact current can be effectively weakened at the moment when the filter capacitor is charged. Then, by gradually adjusting the controllable resistor to a suitable position and short-circuiting the controllable resistor, the impact current generated by the phase difference between the capacitor side and the grid side voltage before and after the short circuit can be effectively reduced. At the same time, the short circuit also ensures the filtering effect of the filter.

[0047] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 is a schematic diagram of an electrical structure of an LCL filter in a related art according to an exemplary embodiment;

[0050] Figure 2 is a schematic diagram of an electrical structure of an LCL filter in the related art according to another exemplary embodiment;

[0051] Figure 3 is a structural schematic diagram of a filter capacitor charging circuit according to an exemplary embodiment;

[0052] Figure 4 is a structural schematic diagram of a filter capacitor charging circuit according to another exemplary embodiment;

[0053] Figure 5 is a structural schematic diagram of a filter capacitor charging monitoring system according to an exemplary embodiment;

[0054] Figure 6 is a flow chart of a filter capacitor charging monitoring processing method according to an exemplary embodiment;

[0055] Figure 7 The figure is a schematic diagram showing the principle of using PID control adjustment according to an exemplary embodiment. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without creative work belong to the scope of protection of the present application.

[0057] See also Figure 3 , Figure 3 is a schematic structural diagram of a filter capacitor charging circuit according to an exemplary embodiment. Figure 3 As shown, the filter capacitor charging circuit 1 includes:

[0058] The filter capacitor module 11 has at least one charging input terminal;

[0059] At least one controllable resistor 12, wherein each charging input terminal of the filter capacitor module 11 is correspondingly connected in series with the controllable resistor 12;

[0060] The controllable switch module 13 has at least one switch unit, and each of the controllable resistors 13 corresponds to and is connected to the switch unit.

[0061] Specifically, Figure 3 What is shown in FIG. 1 is an LCL filter, which realizes filtering of alternating current through the cooperation of a filter capacitor module 11 and a reactor module 14 . Figure 3As shown, the filter capacitors of the filter capacitor module 11 form a triangle connection, and the place where the filter capacitors are connected in pairs forms a charging input terminal. By setting a controllable resistor 12 on the line where the charging input terminals of the filter capacitor module 11 are connected to the live wire, and connecting each controllable resistor 12 in parallel to each switch unit of the controllable switch module 13, the controllable resistor 12 is initially set at the maximum resistance position. When the filter power is filtered, the initial charging moment of the filter capacitor can effectively weaken the impact current. Then, by gradually adjusting the controllable resistor 12 to a suitable position and short-circuiting the controllable resistor 12, the impact current generated by the phase difference between the capacitor side voltage of the filter capacitor module 11 and the grid side voltage before and after the short circuit can be effectively reduced. At the same time, the short circuit also ensures the filtering effect of the filter.

[0062] Figure 3 Taking alternating current as an example, in practical applications, direct current filtering can also be performed through capacitors, and therefore, the filter capacitor charging circuit 1 can also be applied to direct current.

[0063] In one embodiment, the controllable switch module 13 is a contactor, wherein the contactor 13 has at least one main contact, and each of the controllable resistors 12 corresponds to and is connected to the main contact.

[0064] Specifically, the contactor has a main contact and an auxiliary contact. The auxiliary contact is used to receive a control signal to control the main contact. The on and off of each main contact can be simultaneously controlled by a control signal of the auxiliary contact. Figure 3 A three-phase electrical application is shown, and accordingly, the contactor is configured to have three main contacts.

[0065] In practical applications, each switch unit of the controllable switch module 13 can be independently controlled, that is, each switch unit has an independent control signal control. During actual control, each independent control signal is sent simultaneously to realize the simultaneous switching of each switch unit.

[0066] In one embodiment, the filter capacitor module 11 has three filter capacitors, and the three filter capacitors form a delta connection or a star connection.

[0067] Specifically, Figure 3 The filter capacitor module 11 shown in FIG. 1 is connected in a triangle shape between the filter capacitors. The star connection can be obtained by referring to the relevant technology and will not be further described here.

[0068] In one embodiment, the filter capacitor charging circuit 1 is an LC filter capacitor charging circuit or an LCL filter capacitor charging circuit.

[0069] Specifically, Figure 3What is shown in FIG. 1 is an LCL filter capacitor charging circuit, which has two reactor modules 14 . The LC filter capacitor charging circuit has one less reactor module 14 than the LCL filter capacitor charging circuit.

[0070] See also Figure 4 , Figure 4 is a structural schematic diagram of a filter capacitor charging circuit 1 according to another exemplary embodiment. Figure 4 As shown, the filter capacitor charging circuit 1 also includes:

[0071] At least one current sampling element 15, wherein the current sampling element 15 is configured on the circuit corresponding to each charging input end of the filter capacitor module 11;

[0072] At least one voltage sampling element 16, wherein the voltage sampling element 16 is configured on the circuit corresponding to each of the charging input terminals of the filter capacitor module 11, and is configured between the charging input terminal and the controllable resistor 12;

[0073] The charging controller 17 , each of the current sampling elements 15 , each of the voltage sampling elements 16 , and the controllable switch module 13 are respectively connected to the charging controller 17 .

[0074] Specifically, the charging controller 17 can be used to adjust and control each controllable resistor 12 and obtain the current and voltage sampling values ​​of the filter capacitor module 11. Figure 4 In the figure, the voltage sampling element 16 is formed between the live line node and the controllable resistor 12, that is, the voltage sampling point is set between the capacitor and the controllable resistor 12, so as to collect the instantaneous line voltage of each phase on the capacitor side of the filter capacitor module 11.

[0075] Figure 4 Regarding the setting of the current sampling point, the current sampling element 15 is configured on a circuit located at the input side of the controllable resistor 12 .

[0076] In practical applications, the charging controller 17 may adopt a PLC controller, which may provide sufficient interfaces for the connection of each current sampling element 15 and voltage sampling element 16. At the same time, the PLC controller may also control the controllable switch module 13 and adjust each controllable resistor 12. For example, the PLC controller adjusts each controllable resistor 12 by implementing PID control.

[0077] See also Figure 5 , Figure 5 is a structural schematic diagram of a filter capacitor charging monitoring system according to an exemplary embodiment. Figure 5 As shown, the filter capacitor charging monitoring system includes:

[0078] A filter capacitor charging circuit 1 as described in any one of the above items; and

[0079] The main controller 2 is connected to the charging controller 17 .

[0080] Furthermore, the filter capacitor charging monitoring system further includes: a controlled device 3 connected to the main controller 2 .

[0081] Furthermore, the controlled device 3 may include one or more of an inverter, a frequency converter and a current converter.

[0082] Regarding the filter capacitor charging monitoring system of the present application, the hardware modules of the filter capacitor charging circuit 1 thereof have been described in detail in the relevant embodiments, and will not be elaborated on here.

[0083] The above-mentioned related embodiments of the present application provide hardware-related solutions for the present application to solve the problem of charging current impact while ensuring the filtering effect of the filter.

[0084] The present application describes the improvements in charging monitoring processing using a filter capacitor charging monitoring system in the following related embodiments.

[0085] See also Figure 6 , Figure 6 is a flow chart of a filter capacitor charging monitoring processing method according to an exemplary embodiment, the method is applied to the charging controller 17 in the filter capacitor charging monitoring system as described in any one of the above items, such as Figure 6 As shown, the filter capacitor charging monitoring processing method includes the following steps:

[0086] Step S601, after receiving the power-on instruction of the main controller 2, obtaining the sampled current sampled by each current sampling element 15, and obtaining the resistance value of each controllable resistor 12;

[0087] Step S602, calculating the voltage difference between the capacitor side of the filter capacitor module 11 and the grid side according to each of the sampled currents and the resistance value of each of the controllable resistors 12;

[0088] Step S603: if the calculated voltage difference reaches a set value, control the controllable switch module 13 to close each switch unit;

[0089] If the calculated voltage difference does not reach the set value, each of the controllable resistors 12 is adjusted to make the voltage difference reach the set value, and when the voltage difference reaches the set value, the controllable switch module 13 is controlled to close each of the switch units.

[0090] Specifically, the voltage difference between the capacitor side and the grid side of the filter capacitor module 11 is used as a manifestation of the phase difference. The voltage difference between the capacitor side and the grid side of the filter capacitor module 11 can be used as a judgment parameter. The above-mentioned set value can be the voltage difference corresponding to the system allowing impact current, or it can be a slightly larger value.

[0091] After the main controller controls each controlled device 3 to start up, the charging controller 17 calculates the voltage difference between the capacitor side and the grid side of the current filter capacitor module 11 through the sampled currents and the resistance values ​​of each controllable resistor 12. If the current voltage difference reaches the set value, it means that when each controllable resistor 12 is short-circuited, the phase difference between the capacitor voltage and the grid side voltage before and after the short circuit can be effectively reduced to generate an impact current, thereby realizing the impact-free switching of the pre-charge transition to the normal working state, and the pre-charge transitions smoothly to the normal working state to complete the charging process. If the current voltage difference does not reach the set value, it means that when each controllable resistor 12 is short-circuited, the pre-charge transition to the normal working state is a large impact switch, and the pre-charge cannot transition smoothly to the normal working state. Therefore, when the voltage difference does not reach the set value, each controllable resistor 12 is adjusted so that the voltage difference reaches the set value, and then each controllable resistor 12 is short-circuited to realize the impact-free switching of the pre-charge transition to the normal working state, and the pre-charge transitions smoothly to the normal working state to complete the charging process, while ensuring the filtering effect.

[0092] For step S602, in one embodiment, taking the application to three-phase alternating current as an example, the voltage difference between the capacitor side of the filter capacitor module 11 and the grid side is calculated according to each of the sampled currents and the resistance value of each of the controllable resistors 12, including:

[0093] Calculate the difference between the instantaneous line voltages of any two phases between the capacitor side of the filter capacitor module and the grid side according to the sampled currents and the resistance values ​​of the controllable resistors;

[0094] The mean value is calculated according to the maximum value of the difference between the instantaneous line voltages of any two phases of electricity, and the calculated mean value difference is used as the voltage difference.

[0095] Specifically, the charging controller 17 can obtain the resistance value of each controllable resistor 12, the instantaneous current I of the phase A A (t), B phase instantaneous current I B (t), A phase instantaneous current I C (t).

[0096] Using the following formula:

[0097]

[0098] Among them, U CAB (t) is the instantaneous line voltage between phase A and phase B at the three-phase voltage sampling point on the capacitor side of the filter capacitor module 11, U CBC (t) is the instantaneous line voltage between phase B and phase C at the three-phase voltage sampling point on the capacitor side of the filter capacitor module 11, U CCA (t) is the instantaneous line voltage between phases C and A at the three-phase voltage sampling point on the capacitor side of the filter capacitor module 11, U AB (t) is the instantaneous line voltage between phases A and B on the three-phase AC grid side, U BC (t) is the instantaneous line voltage of phase B and phase C on the three-phase AC power grid side, U CA (t) is the instantaneous line voltage between phase C and phase A on the three-phase AC grid side, R A (t), R B (t), R C (t) are the instantaneous resistance values ​​of the three phases of the controllable resistor 12 respectively.

[0099] Using the above formula, ΔU can be calculated through each sampling current and each controllable resistor 12. AB (t), ΔU BC (t) and ΔU CA (t).

[0100] The voltage difference between the capacitor side of the filter capacitor module 11 and the AC grid side is:

[0101]

[0102] In practical applications, the models of the controllable resistors 12 can be configured the same, so the variable resistors can be controlled as follows, R(t) = R A (t) = R B (t) = R C (t).

[0103] In one embodiment, for step S603, the step of adjusting each of the controllable resistors 12 so that the voltage difference reaches the set value includes:

[0104] Obtaining the maximum instantaneous current of each of the sampled currents, and calculating the average current;

[0105] Each of the controllable resistors 12 is adjusted according to the mean current and a preset control curve so that the voltage difference reaches the set value.

[0106] Specifically, the current mean calculation formula is as follows:

[0107]

[0108] In the process of adjusting the phase of the capacitor voltage and the grid voltage by the resistance value, a given control curve ΔU(t)=f(t) is assumed, wherein f(t) is a transformation curve of the voltage sampling point set during the charging process and the voltage difference between the three-phase lines of the AC grid, that is, the control realizes the change curve of the voltage sampling point and the three-phase voltage difference of the AC grid from the moment the system is powered on to the moment the controllable resistor 12 is short-circuited and cut off after charging is completed.

[0109] according to

[0110] See also Figure 7 , Figure 7 It is a principle diagram of using PID control adjustment according to an exemplary embodiment. PID is used to control each R(t), and finally ΔU(t) is smoothly reduced to the set value. The charging controller 17 controls the controllable switch module 13 to close each switch unit and short-circuit each controllable resistor 12 to achieve impact-free switching from pre-charging to normal working state. The pre-charging smoothly transitions to the normal working state to complete the charging process while ensuring the filtering effect.

[0111] In one embodiment, the method further comprises:

[0112] If the controllable resistor 12 is adjusted to the minimum, the controllable switch module 13 is controlled to close each of the switch units.

[0113] Specifically, the actual resistance of the controllable resistor 12 cannot absolutely reach zero. As the resistance decreases, the current flowing through the resistor increases rapidly. If the resistor is not short-circuited and cut off from the loop, it will be burned out over a long period of time. Therefore, this solution can further ensure the safety of the circuit.

[0114] In one embodiment, the method further comprises:

[0115] After the charging controller 17 is powered on, an initialization operation is performed to adjust each of the controllable resistors 12 to a maximum resistance value and to place each switch unit in a disconnected state;

[0116] After determining that the initialization of the main controller 2 is completed, the voltage is sampled through each of the voltage sampling elements 16 , and the current is sampled through each of the current sampling elements 15 , and the power-on instruction of the main controller 2 is waited.

[0117] For details, please refer to Figure 3After the main controller is powered on, the charging controller 17 is powered on and initialized synchronously with the main controller, enters the initialization program to perform fault scanning, scans the switch state of the contactor Kx (including K1, K2, K3), ensures that the main contacts of the contactor are in the disconnected state, and controls the resistance of the controllable resistor 12Rx (including RA, RB, RC) to adjust the resistance to the maximum value. After completion, wait for the main controller. After the program initialization fault scan is completed, the charging controller 17 detects current sampling and voltage sampling, and waits for the main controller startup instruction. When the charging controller 17 detects the current and voltage sampling signals and receives the startup instruction issued by the main controller, the voltage difference is calculated, and the controllable resistor 12 is controlled to adjust the resistance. When the resistance value changes to the minimum or the voltage difference reaches the set value, the charging controller 17 controls the main contacts of the contactor Kx to close, short-circuit the controllable resistor 12 to reduce the resistance load, and the LC and LCL filters enter the normal working state and continue to provide the sampling current and voltage of the filter capacitor C to the main controller.

[0118] In one embodiment, the method further comprises:

[0119] Acquire the sampled voltage sampled by each of the voltage sampling elements 16;

[0120] The instantaneous line voltage of any two phases of electricity on the capacitor side of the filter capacitor module 11 is calculated based on each of the sampled voltages, and the instantaneous line voltage of each two phases of electricity on the grid side is calculated based on the difference in the instantaneous line voltage of each two phases of electricity between the capacitor side of the filter capacitor module 11 and the grid side.

[0121] Specifically, through the above mentioned formula:

[0122]

[0123] It can be seen that the instantaneous line voltage U of any two phases of the capacitor side of the filter capacitor module 11 can be calculated through each sampling voltage. CAB (t), U CBC (t) and U CCA (t), and then use the instantaneous line voltage difference ΔU between the capacitor side of the filter capacitor module 11 and the AC grid side obtained above AB (t), ΔU BC (t) and ΔU CA (t), the instantaneous line voltage U of each two-phase power on the AC grid side can be calculated AB (t), U BC (t) and U CA (t), and then realize the AB (t), U BC (t) and U CA (t) monitoring.

[0124] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0125] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" and "multiple" refers to at least two.

[0126] It should be understood that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. In addition, the "connection" used here may include wireless connection; the wording "and / or" used includes any unit and all combinations of one or more associated listed items.

[0127] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0128] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0129] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0130] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0131] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0132] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means 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 application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0133] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A filter capacitor charging circuit, comprising: The filter capacitor module has at least one charging input terminal; characterized in that it also includes: At least one controllable resistor, wherein each charging input terminal of the filter capacitor module is connected in series with the controllable resistor; A controllable switch module, wherein the controllable switch module has at least one switch unit, and each of the controllable resistors corresponds to and is connected to the switch unit; Also includes: At least one current sampling element, wherein the current sampling element is configured on the circuit corresponding to each of the charging input terminals of the filter capacitor module; At least one voltage sampling element, wherein the voltage sampling element is configured on the circuit corresponding to each of the charging input terminals of the filter capacitor module and is configured between the charging input terminal and the controllable resistor; A charging controller, each of the current sampling elements, each of the voltage sampling elements and the controllable switch module are respectively connected to the charging controller.

2. The filter capacitor charging circuit according to claim 1, characterized in that: The controllable switch module is a contactor, wherein the contactor has at least one main contact, and each of the controllable resistors corresponds to and is connected to the main contact.

3. The filter capacitor charging circuit according to claim 1, characterized in that: The filter capacitor module has three filter capacitors, and the three filter capacitors form a delta connection or a star connection.

4. The filter capacitor charging circuit according to claim 3, characterized in that: The filter capacitor charging circuit is an LC filter capacitor charging circuit or an LCL filter capacitor charging circuit.

5. The filter capacitor charging circuit according to claim 1, characterized in that: The current sampling element is configured on a circuit located at the input side of the controllable resistor.

6. The filter capacitor charging circuit according to claim 1, characterized in that: The charging controller adopts a PLC controller.

7. A filter capacitor charging monitoring system, characterized in that: include: The filter capacitor charging circuit according to any one of claims 4 to 6; as well as A main controller is connected to the charging controller.

8. The filter capacitor charging monitoring system according to claim 7, characterized in that: The filter capacitor charging monitoring system further includes: a controlled device connected to the main controller.

9. The filter capacitor charging monitoring system according to claim 8, characterized in that: The controlled device includes one or more of an inverter, a frequency converter and a current converter.

10. A filter capacitor charging monitoring processing method, characterized in that: The method is applied to the charging controller in the filter capacitor charging monitoring system according to any one of claims 7 to 9, and the method comprises: After receiving the power-on instruction of the main controller, obtaining the sampled current sampled by each current sampling element, and obtaining the resistance value of each controllable resistor; Calculating the voltage difference between the capacitor side and the grid side of the filter capacitor module according to each of the sampled currents and the resistance value of each of the controllable resistors; If the calculated voltage difference reaches a set value, controlling the controllable switch module to close each of the switch units; If the calculated voltage difference does not reach the set value, each of the controllable resistors is adjusted to make the voltage difference reach the set value, and when the voltage difference reaches the set value, the controllable switch module is controlled to turn off each of the switch units.

11. The method according to claim 10, characterized in that Calculating the voltage difference between the capacitor side and the grid side of the filter capacitor module according to each of the sampled currents and the resistance value of each of the controllable resistors includes: Calculate the difference between the instantaneous line voltages of any two phases between the capacitor side of the filter capacitor module and the grid side according to the sampled currents and the resistance values ​​of the controllable resistors; The mean value is calculated according to the maximum value of the difference between the instantaneous line voltages of any two phases of electricity, and the calculated mean value difference is used as the voltage difference.

12. The method according to claim 10, characterized in that The adjusting each of the controllable resistors so that the voltage difference reaches the set value includes: Obtaining the maximum instantaneous current of each of the sampled currents, and calculating the average current; The controllable resistors are adjusted according to the mean current and a preset control curve so that the voltage difference reaches the set value.

13. The method according to claim 10, characterized in that The method further comprises: If the controllable resistor is adjusted to the minimum, the controllable switch module is controlled to close each of the switch units.

14. The method according to claim 10, characterized in that The method further comprises: After the charging controller is powered on, an initialization operation is performed to adjust each of the controllable resistors to a maximum resistance value and to place each switch unit in a disconnected state; After determining that the master controller is initialized, the voltage is sampled through each of the voltage sampling elements, and the current is sampled through each of the current sampling elements, and the power-on instruction of the master controller is waited.

15. The method according to claim 11, characterized in that The method further comprises: Acquiring a sampling voltage sampled by each of the voltage sampling elements; The instantaneous line voltage of any two-phase electricity on the capacitor side of the filter capacitor module is calculated according to each of the sampled voltages, and the instantaneous line voltage of each two-phase electricity on the grid side is calculated by combining the difference in the instantaneous line voltage of each two-phase electricity between the capacitor side of the filter capacitor module and the grid side.

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