Keyboard switching circuit and frequency converter

Abstract

The utility model discloses a keyboard switching circuit and a frequency converter, and relates to the technical field of frequency converters, the keyboard switching circuit comprises an inversion side signal transmission module, a rectification side signal transmission module and a keyboard switching module; an inversion controller of the frequency converter is electrically connected with a first side of the keyboard switching module through the inversion side signal transmission module, and a rectification controller of the frequency converter is electrically connected with a second side of the keyboard switching module through the rectification side signal transmission module; and the third side of the keyboard switching module is electrically connected with a manual operation plate controller of the frequency converter, and is used for receiving a keyboard switching signal sent by the manual operation plate controller and selectively connecting the inversion controller or the rectification controller with the manual operation plate controller according to the keyboard switching signal. According to the utility model, resource waste of a keyboard window and an intrinsic safety isolation manual operation keyboard in coal mine application of a conventional frequency converter is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to frequency converter technical field especially relates to a keyboard switching circuit and frequency converter. BACKGROUND

[0002] With the continuous progress of coal mine production technology and the diversification of transportation application scene, four quadrant frequency converter is widely used because it can run efficiently in electric and braking mode and can feedback energy to the power grid.

[0003] In the main transportation belt scene of coal mine, the traditional four quadrant frequency converter needs to be configured with two independent keyboard windows and intrinsically safe isolated hand-operated keyboards, which are respectively used for the control of the rectifier side and the inverter side. However, this design has obvious drawbacks in special application conditions such as coal mine. On the one hand, after the core debugging is completed, the use frequency of the keyboard window and the intrinsically safe isolated hand-operated keyboard is greatly reduced, resulting in resource waste; on the other hand, the design of two independent keyboard windows and intrinsically safe isolated hand-operated keyboards needs to occupy more explosion-proof shell space and increase the complexity and cost of explosion-proof design, further aggravating the problem of resource waste.

[0004] Therefore, solving the resource waste of the keyboard window and the intrinsically safe isolated hand-operated keyboard of the existing four quadrant frequency converter in coal mine application is a technical problem to be solved at present. CONTENT OF THE UTILITY MODEL

[0005] The main purpose of the utility model is to provide a keyboard switching circuit and frequency converter, which aims to solve the resource waste of the keyboard window and the intrinsically safe isolated hand-operated keyboard of the existing frequency converter in coal mine application.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a keyboard switching circuit, which is applied to a frequency converter, and the keyboard switching circuit comprises an inverter side signal transmission module, a rectifier side signal transmission module and a keyboard switching module.

[0007] The inverter controller of the frequency converter is electrically connected with the first side of the keyboard switching module through the inverter side signal transmission module, and the rectifier controller of the frequency converter is electrically connected with the second side of the keyboard switching module through the rectifier side signal transmission module.

[0008] The third side of the keyboard switching module is electrically connected with the hand-operated disc controller of the frequency converter, is used for receiving the keyboard switching signal sent by the hand-operated disc controller, and selectively connects the inverter controller or the rectifier controller with the hand-operated disc controller according to the keyboard switching signal.

[0009] In an embodiment, the inverter side signal transmission module comprises a plurality of inverter side signal output links, an inverter side signal feedback link and an inverter side keyboard signal interface.

[0010] The inverter-side keyboard signal interface comprises at least an inverter-side signal feedback end and an inverter-side signal end corresponding to each of the inverter-side signal output links;

[0011] The first side of each of the inverter-side signal output links is electrically connected to the inverter controller through the corresponding inverter-side signal end, and the first side of the inverter-side signal feedback link is electrically connected to the inverter controller through the inverter-side signal feedback end;

[0012] The second side of each of the inverter-side signal output links and the second side of the inverter-side signal feedback link are electrically connected to the first side of the keyboard switching module.

[0013] In an embodiment, each of the inverter-side signal output links comprises a first inverter optocoupler unit, the positive input end of the first inverter optocoupler unit is connected to a first power supply, the negative input end of the first inverter optocoupler unit is electrically connected to the corresponding inverter-side signal end, the positive output end of the first inverter optocoupler unit is electrically connected to a third power supply and the first side of the keyboard switching module respectively, and the negative output end of the first inverter optocoupler unit is grounded; and / or,

[0014] The inverter-side signal feedback link comprises a second inverter optocoupler unit, the positive input end of the second inverter optocoupler unit is connected to the third power supply, the negative input end of the second inverter optocoupler unit is electrically connected to the first side of the keyboard switching module, the positive output end of the second inverter optocoupler unit is electrically connected to the first power supply and the inverter-side signal feedback end respectively, and the negative output end of the second inverter optocoupler unit is grounded.

[0015] In an embodiment, each of the inverter-side signal output links further comprises an inverter input protection unit and / or an inverter input filter unit and / or an inverter output filter unit; wherein,

[0016] The inverter input protection unit is connected between the negative input end of the first inverter optocoupler unit and the corresponding inverter-side signal end, the inverter input filter unit is connected between the negative input end of the first inverter optocoupler unit and the corresponding inverter-side signal end, and the inverter output filter unit is connected between the positive output end of the first inverter optocoupler unit and the first side of the keyboard switching module.

[0017] In an embodiment, the rectifier-side signal transmission module comprises a plurality of rectifier-side signal output links, a rectifier-side signal feedback link, and a rectifier-side keyboard signal interface;

[0018] The rectifier-side keyboard signal interface comprises at least a rectifier-side signal feedback end and a rectifier-side signal end corresponding to each of the rectifier-side signal output links;

[0019] The first side of each of the rectifier-side signal output links is respectively electrically connected with the corresponding rectifier-side signal terminal and the rectifier controller, and the first side of the rectifier-side signal feedback link is electrically connected with the rectifier-side signal feedback terminal and the rectifier controller;

[0020] The second side of each of the rectifier-side signal output links and the second side of the rectifier-side signal feedback link are respectively electrically connected with the second side of the keyboard switching module.

[0021] In an embodiment, each of the rectifier-side signal output links comprises a first rectifier optocoupler unit, the positive input terminal of the first rectifier optocoupler unit is connected with a first power supply, the negative input terminal of the first rectifier optocoupler unit is electrically connected with the corresponding rectifier-side signal terminal, the positive output terminal of the first rectifier optocoupler unit is respectively electrically connected with a third power supply and the second side of the keyboard switching module, and the negative output terminal of the first rectifier optocoupler unit is grounded; and / or,

[0022] The rectifier-side signal feedback link comprises a second rectifier optocoupler unit, the positive input terminal of the second rectifier optocoupler unit is connected with a third power supply, the negative input terminal of the second rectifier optocoupler unit is electrically connected with the second side of the keyboard switching module, the positive output terminal of the second rectifier optocoupler unit is respectively electrically connected with a first power supply and the rectifier-side signal feedback terminal, and the negative output terminal of the second rectifier optocoupler unit is grounded.

[0023] In an embodiment, each of the rectifier-side signal output links further comprises a rectifier input protection unit and / or a rectifier input filter unit and / or a rectifier output filter unit; wherein,

[0024] The rectifier input protection unit is connected between the negative input terminal of the first rectifier optocoupler unit and the corresponding rectifier-side signal terminal, the rectifier input filter unit is connected between the negative input terminal of the first rectifier optocoupler unit and the corresponding rectifier-side signal terminal, and the rectifier output filter unit is connected between the positive output terminal of the first rectifier optocoupler unit and the second side of the keyboard switching module.

[0025] In an embodiment, the keyboard switching module comprises a tri-state buffer output link and a hand-operated panel signal interface;

[0026] The first side of the tri-state buffer output link is electrically connected with the inverter controller through the inverter-side signal transmission module, the second side of the tri-state buffer output link is electrically connected with the rectifier controller through the rectifier-side signal transmission module, and the third side of the tri-state buffer output link is electrically connected with the hand-operated panel controller through the hand-operated panel signal interface.

[0027] The controlled side of the tri-state buffer output link is electrically connected with the hand-operated panel controller through the hand-operated panel signal interface, and is used for receiving the keyboard switching signal, so that the tri-state buffer output link selectively connects the inverter controller or the rectifier controller with the hand-operated panel controller according to the keyboard switching signal.

[0028] In an embodiment, the tri-state buffer output link comprises an inverter-side tri-state output unit, a rectifier-side tri-state output unit, an inverter-side feedback unit and a rectifier-side feedback unit.

[0029] The input end of the inverter-side tri-state output unit is electrically connected with the inverter-side signal transmission module, the output end of the inverter-side tri-state output unit is electrically connected with the signal transmission end of the hand-operated panel signal interface, the input end of the inverter-side feedback unit is electrically connected with the signal feedback end of the hand-operated panel signal interface, the output end of the inverter-side feedback unit is electrically connected with the inverter-side signal transmission module, and the controlled ends of the inverter-side tri-state output unit and the inverter-side feedback unit are respectively electrically connected with the first keyboard switching signal end of the hand-operated panel signal interface.

[0030] The input end of the rectifier-side tri-state output unit is electrically connected with the rectifier-side signal transmission module, the output end of the rectifier-side tri-state output unit is electrically connected with the signal transmission end, the input end of the rectifier-side feedback unit is electrically connected with the signal feedback end, the output end of the rectifier-side feedback unit is electrically connected with the rectifier-side signal transmission module, and the controlled ends of the rectifier-side tri-state output unit and the rectifier-side feedback unit are respectively electrically connected with the second keyboard switching signal end of the hand-operated panel signal interface.

[0031] In addition, the utility model still puts forward a kind of frequency converter, and the frequency converter at least includes above-mentioned keyboard switching circuit.

[0032] The keyboard switching circuit provided by the utility model can be applied to a frequency converter, and the keyboard switching circuit is integrated with an inverter side signal transmission module, a rectifier side signal transmission module and a keyboard switching module, the inverter controller of the frequency converter is electrically connected to the first side of the keyboard switching module through the inverter side signal transmission module, the rectifier controller of the frequency converter is electrically connected to the second side of the keyboard switching module through the rectifier side signal transmission module, and the third side of the keyboard switching module is connected to the hand-operated panel controller. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to the structure shown in these drawings without creating labor.

[0034] Figure 1 The structural schematic diagram of the keyboard switching circuit one embodiment provided by the utility model;

[0035] Figure 2 The inverter side signal transmission module related to the embodiment of the utility model;

[0036] Figure 3 The inverter optical coupling unit related to the embodiment of the utility model;

[0037] Figure 4 A schematic diagram of the signal feedback link of the inverter side related to the embodiment of the utility model;

[0038] Figure 5 A schematic diagram of the signal output link circuit of the inverter side related to the embodiment of the utility model;

[0039] Figure 6 A schematic diagram of the signal transmission module circuit of the inverter side related to the embodiment of the utility model;

[0040] Figure 7 A schematic diagram of the signal transmission module of the rectifier side related to the embodiment of the utility model;

[0041] Figure 8 A schematic diagram of the rectifier optocoupler unit related to the embodiment of the utility model;

[0042] Figure 9 A schematic diagram of the signal feedback link circuit of the rectifier side related to the embodiment of the utility model;

[0043] Figure 10 A schematic diagram of the signal output link circuit of the rectifier side related to the embodiment of the utility model;

[0044] Figure 11 A schematic diagram of the signal transmission module circuit of the rectifier side related to the embodiment of the utility model;

[0045] Figure 12 A schematic diagram of the keyboard switching module circuit related to the embodiment of the utility model.

[0046] Explanation of the drawing reference signs:

[0047] 100, keyboard switching circuit; 10, inverter side signal transmission module; 20, rectifier side signal transmission module; 30, keyboard switching module; T10, frequency converter; T101, inverter controller; T102, rectifier controller; T103, hand-operated panel controller; 101, inverter side signal output link; 102, inverter side signal feedback link; 103, inverter side keyboard signal interface; J1, inverter side signal end; J2, inverter side signal feedback end; 11, first inverter optocoupler unit; 12, second inverter optocoupler unit; L1, inverter input protection unit; L2, inverter input filter unit; L3, inverter output filter unit; 201, rectifier side signal output link; 202, rectifier side signal feedback link; 203, rectifier side keyboard signal interface; J3, rectifier side signal end; J4, rectifier side signal feedback end; 21, first rectifier optocoupler unit; 22, second rectifier optocoupler unit; X1, rectifier input protection unit; X2, rectifier input filter unit; X3, rectifier output filter unit; 301, tri-state buffer output link; 302, output interface protection link; 31, inverter side tri-state output unit; 32, rectifier side tri-state output unit; 33, inverter side feedback unit; 34, rectifier side feedback unit; Y1, current-limiting protection unit; Y2, overvoltage protection unit; Y3, hand-operated panel signal interface; D1, first transient suppression tube; R1, first resistor; C1, first capacitor; G1, first buffer; PC1, first optoelectronic coupler; R2, second resistor; R3, third resistor; G2, second buffer; R4, fourth resistor; C2, second capacitor; D2, second transient suppression tube; C3, third capacitor; R5, fifth resistor; G3, third buffer; R6, sixth resistor; PC2, second optoelectronic coupler; R7, seventh resistor; G4, fourth buffer; C4, fourth capacitor; R8, eighth resistor; R9, ninth resistor; C5, fifth capacitor; G5, fifth buffer; PC3, third optoelectronic coupler; R10, tenth resistor; R11, eleventh resistor; G6, sixth buffer; R12, twelfth resistor; C6, sixth capacitor; D4, fourth transient suppression tube; C7, seventh capacitor; R13, thirteenth resistor; G7, seventh buffer; R14, fourteenth resistor; PC4, fourth optoelectronic coupler; R15, fifteenth resistor; G8, eighth buffer; C8, eighth capacitor; R16, sixteenth resistor; G9, ninth buffer; G10, tenth buffer; G11, eleventh buffer; G12, twelfth buffer; R17, seventeenth resistor; R18, eighteenth resistor; R19, nineteenth resistor; R20, twentieth resistor; C9, ninth capacitor; C10, tenth capacitor; D5, fifth steady-state suppression tube; D6, sixth steady-state suppression tube; D7, seventh steady-state suppression tube; D8, eighth steady-state suppression tube.

[0048] The purposes, functional features and advantages of the utility model will be further explained in combination with embodiments with reference to the drawings. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the utility model.

[0050] It should be noted that if the embodiments of the utility model involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0051] In addition, if the embodiments of the utility model involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one feature. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously satisfy the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the utility model.

[0052] With the diversification of coal mine production, transportation and other application scenarios across the country, and the requirement of power grid voltage on high-order harmonics, frequency converters are also more and more widely used in coal mine and other industries. Before that, the main transportation belt scene in coal mine and other industries is mainly flat transportation, and two-quadrant frequency converters are mainly used in the field. The two-quadrant frequency converter has only one inverter working mode, and the frequency converter only needs to make a set of keyboard window and intrinsically safe isolation hand-operated keyboard. After using the four-quadrant frequency converter, two sets of keyboard windows and intrinsically safe isolation hand-operated keyboards are needed, and such design and use waste a set of keyboard window and intrinsically safe isolation hand-operated keyboard.

[0053] There are mainly two kinds of keyboard uses of the current four-quadrant frequency converter:

[0054] 1. The four-quadrant frequency converter rectifier side controller and inverter side controller respectively adopt a set of keyboard window and intrinsically safe isolated hand-operated keyboard, which is independently used by the keyboard window and intrinsically safe hand-operated keyboard of the rectifier side and the inverter side, and in the special application conditions such as coal mines, the keyboard window and intrinsically safe hand-operated keyboard are rarely used after the core debugging is completed, the keyboard window and intrinsically safe hand-operated keyboard are wasted, and the keyboard window and intrinsically safe hand-operated keyboard need to be designed on the explosion-proof shell, which wastes the shell space and increases the explosion-proof design processing.

[0055] 2. The existing close keyboard switching technology is a communication selection keyboard switching circuit used to solve the long-distance control panel keyboard line interference problem, mainly to realize the use of long and short keyboard lines, the communication selection method used in the switching mode is complex, and mainly designed for the use of the same control panel, the circuit is not isolated, and the input interface overvoltage protection is not needed. However, the four-quadrant frequency converter rectifier side controller and inverter side controller adopt two independent control systems, and the signals and circuits on both sides need to be isolated, and due to the complexity of the power supply system in the coal mine field application, the controller needs to do interface filtering and overvoltage protection measures on the external circuit interface to prevent external surge voltage or common mode interference signals from damaging the internal circuit devices of the controller.

[0056] In summary, in order to solve the technical defects described above and save the cost of the keyboard window and intrinsically safe isolated hand-operated keyboard of the frequency converter matched in the coal mine application, the utility model provides a keyboard switching circuit and a frequency converter.

[0057] In an embodiment of the utility model, please refer to Figure 1 , Figure 1 The structure schematic view of the keyboard switching circuit one embodiment provided by the utility model. The keyboard switching circuit 100 provided by the application includes an inverter side signal transmission module 10, a rectifier side signal transmission module 20 and a keyboard switching module 30; the inverter controller T101 of the frequency converter T10 is electrically connected with the first side of the keyboard switching module 30 through the inverter side signal transmission module 10, the rectifier controller T102 of the frequency converter T10 is electrically connected with the second side of the keyboard switching module 30 through the rectifier side signal transmission module 20; the third side of the keyboard switching module 30 is connected with the hand-operated disc controller T103 of the frequency converter T10, is used for receiving the keyboard switching signal sent by the hand-operated disc controller T103, and selectively connecting the inverter controller T101 or the rectifier controller T102 with the hand-operated disc controller T103 according to the keyboard switching signal.

[0058] In the present embodiment, the hand-operated panel controller T103 is connected with the keyboard window and the intrinsically safe isolated hand-operated keyboard respectively, and the keyboard switching circuit 100 is configured to realize the parameter setting, debugging and data display of the inverter controller T101 and the rectifier controller T102 by using the same set of keyboard window and intrinsically safe isolated hand-operated keyboard. Specifically, the inverter controller T101 is electrically connected with the inverter side signal transmission module 10, and the rectifier controller T102 is electrically connected with the rectifier side signal transmission module 20, so that the circuit signals of the inverter controller T101 and the rectifier controller T102 are completely independent by using the optical coupling isolation mode to avoid the interference between the circuit signals of the inverter controller T101 and the rectifier controller T102. The inverter controller T101 of the frequency converter T10 is connected to the hand-operated panel controller T103 via the electrical connection between the inverter side signal transmission module 10 and the keyboard switching module 30, or the rectifier controller T102 of the frequency converter T10 is connected to the hand-operated panel controller T103 via the electrical connection between the rectifier side signal transmission module 20 and the keyboard switching module 30, so that the hand-operated panel controller can display the data sent by the inverter controller or the rectifier controller on the same set of keyboard window, thereby realizing the control of the inverter controller and the rectifier controller by using only one set of keyboard window and intrinsically safe isolated hand-operated keyboard, without the need to install two sets of keyboard window and intrinsically safe isolated hand-operated keyboard on the explosion-proof housing, thereby greatly optimizing the space utilization of the explosion-proof housing, effectively solving the resource waste of the keyboard window and the intrinsically safe isolated hand-operated keyboard in the existing frequency converter T10 applied in coal mines, and significantly saving the cost of the keyboard window and the intrinsically safe isolated hand-operated keyboard matched with the frequency converter T10 applied in coal mines.

[0059] It should be noted that the keyboard window can be understood as a display screen or a display window. The intrinsically safe isolated hand-operated keyboard refers to a keyboard device specially designed for a specific environment (such as an environment with explosive gas or dust in a coal mine, etc.), wherein the intrinsic safety refers to maintaining the electrical energy in the signal and control circuit below a safe level by using a set of low-power devices, thereby preventing the occurrence of fire or explosion accidents caused by internal electrical faults such as sparks and arcs.

[0060] The hand-operated panel refers to a device used for manually controlling the operation of a machine or equipment. The device usually contains a series of buttons, knobs, switches and other control elements, allowing the operator to adjust the operating state, parameters or perform specific control tasks of the machine by manual operation.

[0061] The circuit topology layout of the inverter-side signal transmission module 10 is the same as that of the rectifier-side signal transmission module 20. In addition, the frequency converter provided in the present application may be a four-quadrant frequency converter, and the present application does not impose any limitation thereto.

[0062] Further, in some feasible embodiments, please refer to Figure 2 , Figure 2 Schematic diagram of the inverter-side signal transmission module 10 according to an embodiment of the present invention. The inverter-side signal transmission module 10 includes a plurality of inverter-side signal output links 101, an inverter-side signal feedback link 102, and an inverter-side keyboard signal interface 103;

[0063] The inverter side keyboard signal interface 103 at least includes an inverter side signal feedback terminal J2 and an inverter side signal terminal J1 corresponding to each inverter side signal output link 101;

[0064] The first side of each inverter-side signal output link 101 is electrically connected to the inverter controller T101 via the corresponding inverter-side signal terminal J1, and the first side of the inverter-side signal feedback link 102 is electrically connected to the inverter controller T101 via the inverter-side signal feedback terminal J2;

[0065] The second side of each of the inverter-side signal output links 101 and the second side of the inverter-side signal feedback link 102 are electrically connected to the first side of the keyboard switching module 30 , respectively.

[0066] In this embodiment, taking three inverter-side signal output links 101 as an example, the three inverter-side signal output links 101 can be respectively Figure 2 The inverter side signal output link 101 - 1 , the inverter side signal output link 101 - 2 and the inverter side signal output link 101 - 3 are shown.

[0067] Further, in some feasible embodiments, please refer to Figure 3 , Figure 3 This is a schematic diagram of an inverter optocoupler unit involved in an embodiment of the present utility model. Each of the inverter-side signal output links 101 includes a first inverter optocoupler unit 11. The positive input terminal of the first inverter optocoupler unit 11 is connected to the first power supply VCC1, the negative input terminal of the first inverter optocoupler unit 11 is electrically connected to the corresponding inverter-side signal terminal J1, the positive output terminal of the first inverter optocoupler unit 11 is electrically connected to the third power supply VCC3 and the first side of the keyboard switching module 30, respectively, and the negative output terminal of the first inverter optocoupler unit 11 is grounded; and / or,

[0068] The inverter side signal feedback link 102 comprises a second inverter photocoupling unit 12, a positive input end of the second inverter photocoupling unit 12 is connected with a third power supply VCC3, a negative input end of the second inverter photocoupling unit 12 is electrically connected with the first side of the keyboard switching module 30, positive output ends of the second inverter photocoupling unit 12 are respectively electrically connected with the first power supply VCC1 and the inverter side signal feedback end J2, and a negative output end of the second inverter photocoupling unit 12 is grounded.

[0069] In specific embodiments, the first inverter photocoupling unit 11 provided by the application can comprise a first photocoupler PC1, a second resistor R2 and a third resistor R3, as shown in the figure. Figure 3 For example, the positive input end of the first photocoupler PC1 constitutes the positive input end of the first inverter photocoupling unit 11 and is connected with the first power supply VCC1, the negative input end of the first photocoupler PC1 constitutes the negative input end of the first inverter photocoupling unit 11 and is electrically connected with the corresponding inverter side signal end J1 through the second resistor R2, the positive output end of the first photocoupler PC1 constitutes the positive output end of the first inverter photocoupling unit 11 and is electrically connected with the first end of the third resistor R3 and the first side of the keyboard switching module 30 respectively, the second end of the third resistor R3 is connected with the third power supply VCC3, and the negative output end of the first photocoupler PC1 constitutes the negative output end of the first inverter photocoupling unit 11 and is grounded.

[0070] In addition, the second inverter photocoupling unit 12 provided by the application can comprise a second photocoupler PC2 and a sixth resistor R6, as shown in the figure. Figure 3 For example, the positive input end of the second photocoupler PC2 constitutes the positive input end of the second inverter photocoupling unit 12 and is connected with the third power supply VCC3, the negative input end of the second photocoupler PC2 constitutes the negative input end of the second inverter photocoupling unit 12 and is electrically connected with the first side of the keyboard switching module 30, the positive output end of the second photocoupler PC2 constitutes the positive output end of the second inverter photocoupling unit 12 and is electrically connected with the first end of the sixth resistor R6 and the inverter side signal feedback end J2 respectively, the second end of the sixth resistor is connected with the first power supply VCC1, and the negative output end of the second photocoupler PC2 constitutes the negative output end of the second inverter photocoupling unit 12 and is grounded.

[0071] It should be noted that the inverter side signal feedback link 102 provided by the application is shown in the figure. Figure 4 , Figure 4 The inverter side signal feedback link 102 provided by the application is shown in the figure. Figure 5The second transient suppression tube D2, the third capacitor C3, the fifth resistor R5, the third buffer G3, the sixth resistor R6, the second optocoupler PC2, the seventh resistor R7, the fourth buffer G4, the fourth capacitor C4 and the eighth resistor R8 shown constitute an electrically connected link.

[0072] Further, in some possible embodiments, each of the inverter-side signal output links 101 further comprises an inverter input protection unit L1 and / or an inverter input filter unit L2 and / or an inverter output filter unit L3; wherein,

[0073] The inverter input protection unit L1 is connected between the negative input end of the first inverter optocoupler unit and the corresponding inverter-side signal end, the inverter input filter unit is connected between the negative input end of the first inverter optocoupler unit and the corresponding inverter-side signal end, and the inverter output filter unit is connected between the positive output end of the first inverter optocoupler unit and the first side of the keyboard switching module.

[0074] In the embodiment, refer to Figure 5 , Figure 5 The inverter-side signal output link circuit is shown in the schematic diagram of the embodiment of the utility model. Each of the inverter-side signal output links 101 comprises an inverter input protection unit L1, an inverter input filter unit L2, a first inverter optocoupler unit 11 and an inverter output filter unit L3 connected electrically in sequence; wherein, Figure 5 The first transient suppression tube D1 shown constitutes the inverter input protection unit L1, Figure 5 The first resistor R1, the first capacitor C1 and the first buffer G1 shown constitute the inverter input filter unit L2, Figure 5 The first optocoupler PC1, the second resistor R2 and the third resistor R3 shown constitute the first inverter optocoupler unit 11, Figure 5 The second buffer G2, the fourth resistor R4 and the second capacitor C2 shown constitute the inverter output filter unit L3.

[0075] In the embodiment, refer to Figure 6 , Figure 6 The inverter-side signal transmission module circuit is shown in the schematic diagram of the embodiment of the utility model. The three inverter-side signal output links 101 can be represented by a first inverter-side signal output link 101-1, a second inverter-side signal output link 101-2 and a third inverter-side signal output link 101-3 respectively, wherein the first inverter-side signal output link 101-1 comprises Figure 6 The first transient suppression tube D1-1 shown constitutes the inverter input protection unit L1-1, Figure 6 The first resistor R1-1, the first capacitor C1-1 and the first buffer G1-1 shown constitute the inverter input filter unit L2-1,Figure 6 The first optocoupler PC1-1, the second resistor R2-1 and the third resistor R3-1 shown constitute a first inverter light coupling unit 11-1; Figure 6 The second buffer G2-1, the fourth resistor R4-1 and the second capacitor C2-1 shown constitute an inverter output filter unit L3-1. The second inverter side signal output link 101-2 includes Figure 6 The first transient suppression tube D1-2 shown constitutes an inverter input protection unit L1-2, Figure 6 The first resistor R1-2, the first capacitor C1-2 and the first buffer G1-2 shown constitute an inverter input filter unit L2-2, Figure 6 The first optocoupler PC1-2, the second resistor R2-2 and the third resistor R3-2 shown constitute a first inverter light coupling unit 11-2; Figure 6 The second buffer G2-2, the fourth resistor R4-2 and the second capacitor C2-2 shown constitute an inverter output filter unit L3-2; the third inverter side signal output link 101-3 includes Figure 6 The first transient suppression tube D1-3 shown constitutes an inverter input protection unit L1-3, Figure 6 The first resistor R1-3, the first capacitor C1-3 and the first buffer G1-3 shown constitute an inverter input filter unit L2-3, Figure 6 The first optocoupler PC1-3, the second resistor R2-3 and the third resistor R3-3 shown constitute a first inverter light coupling unit 11-3; Figure 6 The second buffer G2-3, the fourth resistor R4-3 and the second capacitor C2-3 shown constitute an inverter output filter unit L3-3.

[0076] It should be noted that, Figure 6 The inverter side signal end J1-1 shown is a signal channel of the signal KEYCLK1, Figure 6 The inverter side signal end J1-2 shown is a signal channel of the signal KEYCS1, Figure 7 The inverter side signal end J1-3 shown is a signal channel of the signal KEYW1, Figure 7 The inverter side signal feedback end J2 shown is a signal channel of the signal KEYR1; Figure 7 The VCC1 shown is a power supply end of the inverter side, Figure 8 The GND1 shown is a ground end of the inverter side, Figure 8 The VCC3 shown is a power supply end of the hand-operated keyboard side.

[0077] Further, in other possible embodiments, please refer to Figure 8 , Figure 8The utility model discloses an embodiment relates to rectification side signal transmission module schematic drawing. Rectification side signal transmission module 20 includes several rectification side signal output link 201, a rectification side signal feedback link 202 and rectification side keyboard signal interface, rectification side keyboard signal interface includes at least rectification side signal feedback end J4 and rectification side signal end J3 corresponding to each rectification side signal output link 201, and the first side of each rectification side signal output link 201 is connected with rectification controller respectively through corresponding rectification side signal end J3, and the first side of rectification side signal feedback link 202 is connected with rectification controller through rectification side signal feedback end J4, and the second side of each rectification side signal output link 201 and the second side of rectification side signal feedback link 202 are connected with the second side of keyboard switch module respectively.

[0078] In the embodiment, taking three rectification side signal output links 201 as an example, the three rectification side signal output links 201 set by the application can be represented by rectification side signal output link 201-1, rectification side signal output link 201-2 and rectification side signal output link 201-3 as shown in the figure. Figure 9

[0079] Further, in some feasible embodiments, referring to Figure 9 , Figure 9 The utility model discloses an embodiment relates to rectification light coupling unit schematic drawing. Each rectification side signal output link 201 includes first rectification light coupling unit 21, the positive input end of first rectification light coupling unit 21 is connected first power supply VCC1, and the negative input end of first rectification light coupling unit 21 is connected with corresponding rectification side signal end only, and the positive output end of first rectification light coupling unit 21 is connected with third power supply VCC3 and the second side of keyboard switch module 30 respectively, and the negative output end of first rectification light coupling unit 21 is grounded, and / or, rectification side signal feedback link 202 includes second rectification light coupling unit 22, the positive input end of second rectification light coupling unit 22 is connected third power supply VCC3, and the negative input end of second rectification light coupling unit 22 is connected with the second side of keyboard switch module 30, and the positive output end of second rectification light coupling unit 22 is connected with first power supply VCC1 and rectification side signal feedback end J4 respectively, and the negative output end of second rectification light coupling unit is grounded.

[0080] In specific embodiments, the first rectification light coupling unit 21 set by the application is as shown in the figure. Figure 10 ​The third optoelectronic coupler PC3, the tenth resistor R10 and the eleventh resistor R11 are shown. The positive input end of the third optoelectronic coupler PC3 is connected with the first power supply VCC1 to form the positive input end of the first rectification optoelectronic coupler unit 21, the negative input end of the third optoelectronic coupler PC3 is connected with the corresponding rectification side signal end J3 through the tenth resistor R10 to form the negative input end of the first rectification optoelectronic coupler unit 21, the positive output end of the third optoelectronic coupler PC3 is connected with the first end of the eleventh resistor R11 and the second side of the keyboard switching module 30 respectively to form the positive output end of the first rectification optoelectronic coupler unit 21, the second end of the eleventh resistor R11 is connected with the third power supply VCC3, and the negative output end of the third optoelectronic coupler PC3 is grounded to form the negative output end of the first rectification optoelectronic coupler unit 21.

[0081] In addition, the second rectification optoelectronic coupler unit 22 provided by the application is shown in the figure. Figure 10 The fourth optoelectronic coupler PC4 and the fourteenth resistor R14 are shown. The positive input end of the fourth optoelectronic coupler PC4 is connected with the third power supply VCC3 to form the positive input end of the second rectification optoelectronic coupler unit 22, the negative input end of the fourth optoelectronic coupler PC4 is connected with the second side of the keyboard switching module 30 to form the negative input end of the second rectification optoelectronic coupler unit 22, the positive output end of the fourth optoelectronic coupler PC4 is connected with the first end of the fourteenth resistor R14 and the rectification side signal feedback end J4 respectively to form the positive output end of the second rectification optoelectronic coupler unit 22, the second end of the fourteenth resistor R14 is connected with the first power supply VCC1, and the negative output end of the fourth optoelectronic coupler PC4 is grounded to form the negative output end of the second rectification optoelectronic coupler unit 22.

[0082] It should be noted that the rectification side signal feedback link circuit shown in the figure is used for the keyboard switching module 30. Figure 10 Figure 10 The rectification side signal feedback link circuit shown in the figure is used for the keyboard switching module 30. Figure 5 The fourth transient suppression tube D4, the seventh capacitor C7, the thirteenth resistor R13, the seventh buffer G7, the fourteenth resistor R14, the fourth optoelectronic coupler PC4, the fifteenth resistor R15, the eighth buffer G8, the eighth capacitor C8 and the sixteenth resistor R16 are shown.

[0083] ​Further, in some possible embodiments, each of the rectification side signal output links further comprises a rectification input protection unit and / or a rectification input filter unit and / or a rectification output filter unit; wherein the rectification input protection unit is connected between the negative input end of the first rectification optocoupler unit and the corresponding rectification side signal end, the rectification input filter unit is connected between the negative input end of the first rectification optocoupler unit and the corresponding rectification side signal end, and the rectification output filter unit is connected between the positive output end of the first rectification optocoupler unit and the second side of the keyboard switching module.

[0084] In the embodiments, refer to Figure 10 , Figure 11 The utility model discloses an embodiment relates to rectification side signal output link circuit schematic diagram. Each rectification side signal output link 201 comprises rectification input protection unit X1, rectification input filter unit X2, first rectification optocoupler unit 21 and rectification output filter unit X3 that connect gradually, and wherein, Figure 11 The third transient suppression tube D3 shown in the figure constitutes rectification input protection unit X1, Figure 11 The ninth resistance R9, fifth capacitor C5 and fifth buffer G5 shown in the figure constitute rectification input filter unit X2, Figure 11 The third optoelectronic coupler PC3, tenth resistance R10 and eleventh resistance R11 shown in the figure constitute first rectification optocoupler unit 21, Figure 11 The sixth buffer G6, twelfth resistance R12 and sixth capacitor C6 shown in the figure constitute rectification output filter unit X3.

[0085] In specific embodiments, refer to Figure 11 , Figure 11 The utility model discloses an embodiment relates to rectification side signal transmission module circuit schematic diagram. Three rectification side signal output links 201 can be represented as first rectification side signal output link 201-1, second rectification side signal output link 201-2 and third rectification side signal output link 201-3 respectively, wherein the first rectification side signal output link 201-1 comprises Figure 11 Rectification input protection unit X1-1 constituted by the third transient suppression tube D3-1 shown in the figure, Figure 11 Rectification input filter unit X2-1 constituted by the ninth resistance R9-1, fifth capacitor C5-1 and fifth buffer G5-1 shown in the figure. Figure 11 The third optoelectronic coupler PC3-1, tenth resistance R10-1 and eleventh resistance R11-1 shown in the figure constitute first rectification optocoupler unit 21-1, Figure 11 The sixth buffer G6-1, twelfth resistance R12-1 and sixth capacitor C6-1 shown in the figure constitute rectification output filter unit X3-1; the second rectification side signal output link 201-2 comprisesFigure 11 The third transient suppression tube D3-2 shown constitutes a rectifier input protection unit X1-2, Figure 11 The ninth resistor R9-2, the fifth capacitor C5-2 and the fifth buffer G5-2 shown constitute a rectifier input filter unit X2-2, Figure 11 The third optocoupler PC3-2, the tenth resistor R10-2 and the eleventh resistor R11-2 shown constitute a first rectifier light coupling unit 21-2, Figure 12 The sixth buffer G6-2, the twelfth resistor R12-2 and the sixth capacitor C6-2 shown constitute a rectifier output filter unit X3-2; the third rectifier side signal output link 201-3 includes Figure 12 The third transient suppression tube D3-3 shown constitutes a rectifier input protection unit X1-3, Figure 12 The ninth resistor R9-3, the fifth capacitor C5-3 and the fifth buffer G5-3 shown constitute a rectifier input filter unit X2-3, Figure 6 The third optocoupler PC3-3, the tenth resistor R10-3 and the eleventh resistor R11-3 shown constitute a first rectifier light coupling unit 21-3, Figure 11 The sixth buffer G6-3, the twelfth resistor R12-3 and the sixth capacitor C6-3 shown constitute a rectifier output filter unit X3-3.

[0086] Further, in other possible embodiments, with reference to Figure 12 , Figure 6 A keyboard switching module circuit schematic diagram is related to the embodiments of the utility model. The keyboard switching module 30 includes tri-state buffer output link 301 and hand-operated panel signal interface Y3;The first side of tri-state buffer output link 301 is electrically connected with inverter controller T101 through inverter side signal transmission module 10, the second side of tri-state buffer output link 301 is electrically connected with rectifier controller T102 through rectifier side signal transmission module 20, the third side of tri-state buffer output link 301 is electrically connected with hand-operated panel controller T103 through hand-operated panel signal interface Y3;The controlled side of tri-state buffer output link 301 is electrically connected with hand-operated panel controller T103 through hand-operated panel signal interface Y3, and the controlled side of tri-state buffer output link 301 is used to receive keyboard switching signal, so that tri-state buffer output link 301 selectively connects inverter controller T101 or rectifier controller T102 with hand-operated panel controller T103 according to keyboard switching signal.

[0087] Further, in some possible embodiments, the tri-state buffer output link 301 comprises an inverter-side tri-state output unit 31, a rectifier-side tri-state output unit 32, an inverter-side feedback unit 33, and a rectifier-side feedback unit 34; an input end of the inverter-side tri-state output unit 31 is electrically connected with the inverter-side signal transmission module 10, an output end of the inverter-side tri-state output unit 31 is electrically connected with a signal transmission end of the hand-operated panel signal interface Y3, an input end of the inverter-side feedback unit 33 is electrically connected with a signal feedback end of the hand-operated panel signal interface Y3, an output end of the inverter-side feedback unit 33 is electrically connected with the inverter-side signal transmission module 10, and a controlled end of the inverter-side tri-state output unit 31 and a controlled end of the inverter-side feedback unit 33 are respectively electrically connected with a first keyboard switching signal end of the hand-operated panel signal interface Y3; an input end of the rectifier-side tri-state output unit 32 is electrically connected with the rectifier-side signal transmission module 20, an output end of the rectifier-side tri-state output unit 32 is electrically connected with the signal transmission end, an input end of the rectifier-side feedback unit 34 is electrically connected with the signal feedback end, an output end of the rectifier-side feedback unit 34 is electrically connected with the rectifier-side signal transmission module 20, and a controlled end of the rectifier-side tri-state output unit 32 and a controlled end of the rectifier-side feedback unit 34 are respectively electrically connected with a second keyboard switching signal end of the hand-operated panel signal interface Y3.

[0088] In the embodiment, referring to Figure 6 , the keyboard switching module 30 can further comprise a current-limiting protection unit Y1 and an overvoltage protection unit Y2; the inverter-side feedback unit 33, the rectifier-side feedback unit 34, the inverter-side tri-state output unit 31, and the rectifier-side tri-state output unit 32 are all electrically connected with a first side of the hand-operated panel signal interface Y3 through the current-limiting protection unit Y1; the overvoltage protection unit Y2 is also electrically connected with the first side of the hand-operated panel signal interface Y3, and a second side of the hand-operated panel signal interface Y3 is electrically connected with the hand-operated panel controller T103.

[0089] In the embodiment, referring to Figure 6 , Figure 6 , and Figure 6 ; the first transient suppression tube D1-1, the first transient suppression tube D1-2, the first transient suppression tube D1-3, and the second transient suppression tube D2 shown in Figure 12 can be understood as an inverter-side controller input interface overvoltage protection circuit; the first resistor R1-1 and the first capacitor C1-1, the first resistor R1-2 and the first capacitor C1-2, the first resistor R1-3 and the first capacitor C1-2, and the fifth resistor R5 and the third capacitor C3 shown in Figure 11 can be understood as an inverter-side input signal RC filtering circuit; the first buffer G1-1, the first buffer G1-2, the first buffer G1-3, and the third buffer G3 can be understood as an inverter-side output signal buffering circuit;Figure 11 The three first optocouplers PC1, three second resistors R2, three third resistors R3, the second optocoupler PC2, the sixth resistor R6 and the seventh resistor R7 are the inverter side signal isolation transmission circuit; Figure 11 The fourth buffer and the three second buffers G2 are the inverter side output signal buffer circuit; Figure 11 Each fourth resistor R4 with the corresponding second capacitor C2, the eighth resistor R8 and the fourth capacitor C4 are the inverter side output signal RC filter circuit; Figure 11 The ninth buffer G9 (i.e. the ninth buffer G9-1, the ninth buffer G9-2 and the ninth buffer G9-3) and the tenth buffer G10 are the inverter side output signal tri-state output buffer circuit.

[0090] Similarly, Figure 11 The third transient voltage suppressor D3-1, the third transient voltage suppressor D3-2, the third transient voltage suppressor D3-3 and the fourth transient voltage suppressor D4 are the rectifier side controller input interface overvoltage protection circuit; Figure 12 The ninth resistor R9-1 with the fifth capacitor C5-1, the ninth resistor R9-2 with the fifth capacitor C5-2, the ninth resistor R9-3 with the fifth capacitor C5-2 and the thirteenth resistor R13 with the seventh capacitor C7 are the rectifier side input signal RC filter circuit; Figure 12 Each fifth buffer G5 and the seventh buffer G7 are the rectifier side input signal buffer circuit; Figure 12 Each third optocoupler PC3, fourth optocoupler PC4, each tenth resistor R10, each eleventh resistor R11, the fourteenth resistor R14 and the fifteenth resistor R15 are the rectifier side signal isolation transmission circuit; Figure 12 Each sixth buffer G6 and the eighth buffer G8 are the rectifier side output signal buffer circuit; Figure 6 Each twelfth resistor R12 with the corresponding sixth capacitor C6, the sixteenth resistor R16 and the eighth capacitor C8 are the rectifier side output signal RC filter circuit; Figure 11 The eleventh buffer G11 (i.e. the eleventh buffer G11-1, the eleventh buffer G11-2 and the eleventh buffer G11-3) and the twelfth buffer G12 are the rectifier side output signal tri-state output buffer circuit.

[0091] In addition, Figure 12 The seventeenth resistor R17 (i.e. the seventeenth resistor R17-1, the seventeenth resistor R17-2 and the seventeenth resistor R17-3) and the eighteenth resistor R18 are the PLC controller (i.e. the hand-operated panel controller T103) signal current limiting protection resistor; ​The nineteenth resistor R19, the twentieth resistor R20, the ninth capacitor C9 and the tenth capacitor C10 shown are tri-state output buffer enable signals RC filter circuit; ​ The fifth steady-state suppression tube D5, the sixth steady-state suppression tube D6, the seventh steady-state suppression tube D7 and the eighth steady-state suppression tube D8 shown are PLC controller interface (hand-operated panel signal interface Y3) overvoltage protection circuit.

[0092] For example, with reference to ​ , ​ and ​ When the frequency converter T10 needs to be debugged or the inverter side controller data is viewed, the technician inputs a set of named keys through the PLC intrinsically safe isolation hand-operated keyboard, gives a low-level signal to EN1 of the keyboard switching circuit 100, and gives a high-level signal to the opposite EN2, the tenth buffer G10 and each ninth buffer G9 inverter side output signal tri-state output buffer enable work, the twelfth buffer G12 and each eleventh buffer G11 rectifier side output signal tri-state output buffer keeps high resistance output state, the inverter side controller signal works normally, interacts with the PLC controller signal, and the keyboard window and the PLC intrinsically safe isolation hand-operated keyboard can complete the inverter side controller parameter setting and data display functions.

[0093] When the frequency converter T10 needs to be debugged or the rectifier side controller data is viewed, the technician inputs a set of named keys through the PLC intrinsically safe isolation hand-operated keyboard, gives a low-level signal to EN1 of the keyboard switching circuit 100, and gives a high-level signal to the opposite EN2, the twelfth buffer G12 and each eleventh buffer G11 rectifier side output signal tri-state output buffer enable work, the tenth buffer G10 and each ninth buffer G9 inverter side output signal tri-state output buffer keeps high resistance output state, the rectifier side controller signal works normally, interacts with the PLC controller signal, and the keyboard window and the PLC intrinsically safe isolation hand-operated keyboard can complete the rectifier side controller parameter setting and data display functions.

[0094] In the keyboard switching circuit 100, the first to eighth transient suppression tubes D1-D8 provided in the application are used to prevent the input and output interface from appearing instantaneous surge voltage or overvoltage, so as to burn the rectifier and inverter controller T101 circuit devices and the PLC controller circuit devices, and increase the overvoltage protection; the RC filter circuit and the buffer circuit provided in the application are used to increase the anti-interference ability of the signal in the complex power supply scene application, and prevent the interference signal from malfunctioning; the optocoupler provided in the application can realize the independence of the controller signal and circuit between the inverter controller T101 and the rectifier controller T102 of the four-pole frequency converter, and between the four-pole frequency converter and the PLC controller, and ensure the stability and reliability of the circuit.

[0095] In summary, the keyboard switching circuit 100 provided by the application can realize the functions of parameter setting, debugging and data display of the rectifier controller T102 and the inverter controller T101 in the frequency converter T10 by using the same set of keyboard window and the intrinsically safe isolated hand-operated keyboard; in addition, the circuit signals of the rectifier controller T102 and the inverter controller T101 are isolated by using optical coupling, so that the circuits are independent of each other and the stability and reliability of the circuits are improved; furthermore, the input and output interfaces are provided with surge and overvoltage protection and filter circuits, so that the anti-interference ability in different use environments is improved; in addition, the keyboard signal switching uses a three-state output buffer, and when the external PLC selects the rectification or the inversion, the corresponding enable level signal is given, so that the keyboard signal switching function of the rectifier controller T102 and the inverter controller T101 is realized.

[0096] The utility model further provides a kind of frequency converter, and the frequency converter at least includes above-mentioned keyboard switching circuit, and the specific structure of the keyboard switching circuit refers to above-mentioned embodiment, since frequency converter has adopted all technical solutions of above-mentioned all embodiments, it at least has all beneficial effects brought by the technical solutions of above-mentioned embodiments, and here is not again elaborated.

[0097] The above is only exemplary embodiment of the utility model, and not therefore limit the patent range of the utility model, all equivalent structural transformations made by using the utility model specification and drawing contents, or direct / indirect application in other related frequency converter technical field are included in the patent protection range of the utility model.

Claims

1. A keyboard switching circuit, characterized in that: Applied to the frequency converter, the keyboard switching circuit includes an inverter side signal transmission module, a rectifier side signal transmission module and a keyboard switching module; The inverter controller of the frequency converter is electrically connected to the first side of the keyboard switching module through the inverter-side signal transmission module, and the rectifier controller of the frequency converter is electrically connected to the second side of the keyboard switching module through the rectifier-side signal transmission module; The third side of the keyboard switching module is electrically connected to the manual operation panel controller of the inverter, and is used to receive the keyboard switching signal sent by the manual operation panel controller, and selectively connect the inverter controller or the rectifier controller to the manual operation panel controller according to the keyboard switching signal.

2. The keyboard switching circuit according to claim 1, wherein: The inverter side signal transmission module includes a plurality of inverter side signal output links, an inverter side signal feedback link and an inverter side keyboard signal interface; The inverter side keyboard signal interface at least includes an inverter side signal feedback terminal and an inverter side signal terminal corresponding to each inverter side signal output link; The first side of each of the inverter-side signal output links is electrically connected to the inverter controller via the corresponding inverter-side signal terminal, and the first side of the inverter-side signal feedback link is electrically connected to the inverter controller via the inverter-side signal feedback terminal; The second side of each of the inverter-side signal output links and the second side of the inverter-side signal feedback link are electrically connected to the first side of the keyboard switching module respectively.

3. The keyboard switching circuit according to claim 2, wherein: Each of the inverter-side signal output links includes a first inverter optocoupler unit, wherein the positive input terminal of the first inverter optocoupler unit is connected to the first power supply, the negative input terminal of the first inverter optocoupler unit is electrically connected to the corresponding inverter-side signal terminal, the positive output terminal of the first inverter optocoupler unit is electrically connected to the third power supply and the first side of the keyboard switching module respectively, and the negative output terminal of the first inverter optocoupler unit is grounded; and / or, The inverter side signal feedback link includes a second inverter optocoupler unit, the positive input end of the second inverter optocoupler unit is connected to the third power supply, the negative input end of the second inverter optocoupler unit is electrically connected to the first side of the keyboard switching module, the positive output end of the second inverter optocoupler unit is electrically connected to the first power supply and the inverter side signal feedback end respectively, and the negative output end of the second inverter optocoupler unit is grounded.

4. The keyboard switching circuit according to claim 3, wherein: Each of the inverter-side signal output links further includes an inverter input protection unit and / or an inverter input filter unit and / or an inverter output filter unit; wherein, The inverter input protection unit is connected between the negative input terminal of the first inverter optocoupler unit and the corresponding inverter side signal terminal, the inverter input filter unit is connected between the negative input terminal of the first inverter optocoupler unit and the corresponding inverter side signal terminal, and the inverter output filter unit is connected between the positive output terminal of the first inverter optocoupler unit and the first side of the keyboard switching module.

5. The keyboard switching circuit according to claim 1, wherein: The rectifier side signal transmission module includes several rectifier side signal output links, a rectifier side signal feedback link and a rectifier side keyboard signal interface; The rectifier side keyboard signal interface at least includes a rectifier side signal feedback terminal and a rectifier side signal terminal corresponding to each rectifier side signal output link; The first side of each of the rectifier-side signal output links is electrically connected to the rectifier controller via the corresponding rectifier-side signal terminal, and the first side of the rectifier-side signal feedback link is electrically connected to the rectifier controller via the rectifier-side signal feedback terminal; The second side of each of the rectifier-side signal output links and the second side of the rectifier-side signal feedback link are electrically connected to the second side of the keyboard switching module respectively.

6. The keyboard switching circuit according to claim 5, wherein: Each of the rectifier-side signal output links includes a first rectifier optocoupler unit, wherein the positive input terminal of the first rectifier optocoupler unit is connected to the first power supply, the negative input terminal of the first rectifier optocoupler unit is electrically connected to the corresponding rectifier-side signal terminal, the positive output terminal of the first rectifier optocoupler unit is electrically connected to the third power supply and the second side of the keyboard switching module, respectively, and the negative output terminal of the first rectifier optocoupler unit is grounded; and / or, The rectifier side signal feedback link includes a second rectifier optocoupler unit, the positive input end of the second rectifier optocoupler unit is connected to the third power supply, the negative input end of the second rectifier optocoupler unit is electrically connected to the second side of the keyboard switching module, the positive output end of the second rectifier optocoupler unit is electrically connected to the first power supply and the rectifier side signal feedback end respectively, and the negative output end of the second rectifier optocoupler unit is grounded.

7. The keyboard switching circuit according to claim 6, wherein: Each of the rectifier-side signal output links further includes a rectifier input protection unit and / or a rectifier input filter unit and / or a rectifier output filter unit; wherein, The rectifier input protection unit is connected between the negative input terminal of the first rectifier optocoupler unit and the corresponding rectifier side signal terminal, the rectifier input filter unit is connected between the negative input terminal of the first rectifier optocoupler unit and the corresponding rectifier side signal terminal, and the rectifier output filter unit is connected between the positive output terminal of the first rectifier optocoupler unit and the second side of the keyboard switching module.

8. The keyboard switching circuit according to claim 1, wherein: The keyboard switching module includes a tri-state buffer output link and a hand-operated panel signal interface; The first side of the tri-state buffer output link is electrically connected to the inverter controller via the inverter-side signal transmission module, the second side of the tri-state buffer output link is electrically connected to the rectifier controller via the rectifier-side signal transmission module, and the third side of the tri-state buffer output link is electrically connected to the hand-operated controller via the hand-operated signal interface; The controlled side of the three-state buffer output link is electrically connected to the hand-operated controller through the hand-operated signal interface. The controlled side of the three-state buffer output link is used to receive the keyboard switching signal so that the three-state buffer output link selectively connects the inverter controller or the rectifier controller to the hand-operated controller according to the keyboard switching signal.

9. The keyboard switching circuit according to claim 8, wherein: The three-state buffer output link includes an inverter side three-state output unit, a rectifier side three-state output unit, an inverter side feedback unit and a rectifier side feedback unit; The input end of the inverter-side three-state output unit is electrically connected to the inverter-side signal transmission module, the output end of the inverter-side three-state output unit is electrically connected to the signal transmission end of the hand-operated panel signal interface, the input end of the inverter-side feedback unit is electrically connected to the signal feedback end of the hand-operated panel signal interface, the output end of the inverter-side feedback unit is electrically connected to the inverter-side signal transmission module, and the controlled end of the inverter-side three-state output unit and the controlled end of the inverter-side feedback unit are respectively electrically connected to the first keyboard switching signal end of the hand-operated panel signal interface; The input end of the rectifier side three-state output unit is electrically connected to the rectifier side signal transmission module, the output end of the rectifier side three-state output unit is electrically connected to the signal transmission end, the input end of the rectifier side feedback unit is electrically connected to the signal feedback end, the output end of the rectifier side feedback unit is electrically connected to the rectifier side signal transmission module, and the controlled end of the rectifier side three-state output unit and the controlled end of the rectifier side feedback unit are respectively electrically connected to the second keyboard switching signal end of the hand-operated panel signal interface.

10. A frequency converter, characterized in that: The frequency converter at least includes the keyboard switching circuit according to any one of claims 1 to 9.

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