Interface circuit of inverter and inverter

Abstract

The present invention relates to the technical field of inverters, and relates to an interface circuit of an inverter and an inverter. The interface circuit comprises a main control chip, a disconnection detection unit, a voltage dividing unit, and a signal amplification unit. The disconnection detection unit is connected to the other end of a disconnection switch unit, and the disconnection detection unit is used for detecting the disconnection state of a demand response enabling device and pulling down the voltage of an input terminal of the signal amplification unit when a disconnection occurs. The voltage dividing unit comprises a first voltage dividing module and a plurality of second voltage dividing modules having different resistance values. The plurality of second voltage dividing modules are connected in series to a plurality of power regulating switch units in a one-to-one correspondence and then connected in parallel. A first parallel node is grounded, and a second parallel node is connected to one end of the first voltage dividing module and the input terminal of the signal amplification unit. The other end of the first voltage dividing module is connected to an external power supply. The main control chip is used to determine the voltage outputted by the signal amplification unit and control grid-connected power generation on the basis of a determination result. The present application simultaneously has the functions of power regulation and performing disconnection detection on the demand response enabling device.

Description

An interface circuit for an inverter and an inverter Technical Field

[0001] This invention relates to the field of inverter technology, and in particular to an inverter interface circuit and an inverter. Background Technology

[0002] With the rapid development of the power industry, photovoltaic new energy is gradually becoming the mainstream of the market. As a core power generation device, inverters are facing increasingly stringent technical and quality requirements. Various countries are also considering their market access requirements for inverters. In Australia, the inverter access requirement standard AS / NZS 4777.2:2020 has been officially revised and released, requiring inverters to add a grid-connected power dispatch interface to connect to a DRED (Demand Response Enabling Device) for real-time adjustment and control of grid-connected power. The control logic must be set according to the mode specified in the standard.

[0003] According to the standard requirements, multiple external I / O interfaces need to be added to the inverter, one of which is used for forced grid disconnection. While existing inverters have added only one I / O interface, meeting the basic mandatory requirement, they cannot achieve power dispatch. Some inverters have added multiple I / O interfaces, but they cannot detect grid disconnection in the event of a grid dispatching device failure, thus posing a safety hazard. Technical issues

[0004] The technical problem to be solved by the embodiments of the present invention is to provide an interface circuit and an inverter for an inverter, so as to solve the problem that the inverter in the prior art cannot simultaneously have the functions of power dispatching and disconnection detection of grid dispatching equipment. Technical solutions

[0005] This invention discloses an interface circuit for an inverter, used to connect to an external power grid dispatching device. The power grid dispatching device includes a disconnection detection resistor, a disconnection switch unit, and multiple power regulation switch units. The disconnection detection resistor is connected in parallel with the disconnection switch unit, and one end of the disconnection switch unit is grounded. The inverter interface circuit includes a main control chip, a disconnection detection unit, a voltage divider unit, and a signal amplification unit.

[0006] The disconnection detection unit is connected to the other end of the disconnection switch unit. The disconnection detection unit is used to detect the disconnection status of the power grid dispatching equipment and pull down the input voltage of the signal amplification unit when the disconnection occurs.

[0007] The voltage divider unit includes a first voltage divider module and multiple second voltage divider modules with different resistance values. The multiple second voltage divider modules are connected in series and then in parallel with the multiple power adjustment switch units in a one-to-one correspondence. The first parallel node is grounded, and the second parallel node is connected to one end of the first voltage divider module and the input terminal of the signal amplification unit. The other end of the first voltage divider module is connected to an external power supply.

[0008] The analog input port of the main control chip is connected to the output terminal of the signal amplification unit. The main control chip is used to judge the voltage output by the signal amplification unit and control the grid-connected power generation or disconnect the grid according to the judgment result.

[0009] Optionally, the disconnection detection unit includes a first switching transistor, a second switching transistor, a first Zener diode, a second Zener diode, a first pull-up module, and a second pull-up module. The driving terminal of the first switching transistor is connected to the negative terminal of the first Zener diode. The first terminal of the first switching transistor is connected to an external power supply. The second terminal of the first switching transistor is connected to the positive terminal of the second Zener diode and one end of the second pull-up module. The first terminal of the second switching transistor is grounded. The second terminal of the second switching transistor is connected to the input terminal of the signal amplification unit. The positive terminal of the first Zener diode is connected to the negative terminal of the second Zener diode and one end of the first pull-up module. The other end of the first pull-up module is connected to an external power supply. The other end of the second pull-up module is connected to the driving terminal of the second switching transistor.

[0010] Optionally, the wire breakage detection unit further includes a first resistor and a second resistor, wherein the first resistor is connected in series between the negative terminal of the first Zener diode and the driving terminal of the first switching transistor, and the second resistor is connected in series between the positive terminal of the first Zener diode and the negative terminal of the second Zener diode.

[0011] Optionally, the interface circuit of the inverter further includes a signal isolation unit, the input of which is connected to the connection node between the first voltage divider module and the second voltage divider module, and the output is connected to the input of the signal amplification unit.

[0012] Optionally, the signal isolation unit includes a third resistor and an isolation linear optocoupler. The third resistor is connected in series between the connection node of the first voltage divider module and the second voltage divider module and the input terminal of the isolation linear optocoupler. The output terminal of the isolation linear optocoupler is connected to the input terminal of the signal amplification unit.

[0013] Optionally, the signal amplification unit includes an operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. The fourth resistor is connected in series between the positive terminal of the output of the isolated linear optocoupler and the non-inverting input terminal of the operational amplifier. The fifth resistor is connected in series between the negative terminal of the output of the isolated linear optocoupler and the inverting input terminal of the operational amplifier. The sixth resistor is connected in series between the non-inverting input terminal of the operational amplifier and ground. The seventh resistor is connected in series between the output terminal and the inverting input terminal of the operational amplifier.

[0014] Optionally, the signal amplification unit further includes a first capacitor and a second capacitor, wherein the first capacitor is connected in parallel with the sixth resistor, and the second capacitor is connected in parallel with the seventh resistor.

[0015] Optionally, the first voltage divider module includes a first voltage divider resistor, the second voltage divider module includes a second voltage divider resistor, and a plurality of second voltage divider resistors are connected in series and then in parallel with a plurality of power adjustment switch units in a one-to-one correspondence. The first parallel node is grounded, the second parallel node is connected to one end of the first voltage divider resistor and the input terminal of the signal isolation unit, the other end of the first voltage divider resistor is connected to an external power supply, and the resistance values ​​of the plurality of second voltage divider resistors are different.

[0016] Optionally, the first pull-up module includes a first pull-up resistor, one end of which is connected to an external power supply, and the other end is connected to one end of the disconnect switch unit, the positive terminal of the first Zener diode, and the negative terminal of the second Zener diode. The second pull-up module includes a second pull-up resistor, one end of which is connected to the positive terminal of the second Zener diode and the second terminal of the first switching transistor, and the other end is connected to the driving terminal of the second switching transistor.

[0017] The present invention also discloses an inverter, including the interface circuit of the inverter as described above. Beneficial effects

[0018] Compared with the prior art, the interface circuit of the inverter and the inverter provided in this embodiment of the invention have the following advantages: The interface circuit of the inverter is used to connect to an external power grid dispatching device. By setting a main control chip, a disconnection detection unit, a voltage divider unit, and a signal amplification unit, the voltage divider unit includes a first voltage divider module and multiple second voltage divider modules with different resistance values. The multiple second voltage divider modules are connected in series and then in parallel with multiple power regulation switch units in a one-to-one correspondence. When a power regulation switch unit is turned on, the corresponding series-connected second voltage divider module is connected to the first voltage divider module, and the voltage obtained by voltage division with the first voltage divider module is... After being amplified by the signal amplification unit, the signal is transmitted to the main control chip. The main control chip judges the voltage and controls the output of the corresponding grid-connected power generation, thus having a power dispatch function. Furthermore, the disconnection detection unit is connected to the other end of the disconnection switch unit, which can detect the disconnection status of the external grid dispatching equipment and pull down the input voltage of the signal amplification unit when the disconnection occurs. This voltage is amplified by the signal amplification unit and transmitted to the main control chip. The main control chip controls the disconnection of the grid based on the voltage input by the analog input port. Therefore, this application enables the inverter to have both power dispatch and disconnection detection functions for grid dispatching equipment. Attached Figure Description

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0020] Figure 1 is a structural block diagram of the interface circuit of the inverter provided in an embodiment of the present invention;

[0021] Figure 2 is a circuit diagram of the interface circuit of the inverter provided in an embodiment of the present invention.

[0022] The labels for the attached figures are as follows:

[0023] 100. Power grid dispatching equipment; 110. Disconnection detection resistor; 120. Disconnection switch unit; 130. Power regulation switch unit;

[0024] 200. Inverter interface circuit;

[0025] 210 (U1), Main control chip; 220, Disconnection detection unit; 221, First pull-up module; 222, Second pull-up module; 230, Voltage divider unit; 231, First voltage divider module; 232, Second voltage divider module; 240, Signal amplification unit; 250, Signal isolation unit;

[0026] Q1, First switching transistor; Q2, Second switching transistor; ZD1, First Zener diode; ZD2, Second Zener diode; R1, First pull-up resistor; R2, Second pull-up resistor; R3, First resistor; R4, Second resistor; R5, Third resistor; U2, Isolated linear optocoupler; U3, Operational amplifier; R6, Fourth resistor; R7, Fifth resistor; R8, Sixth resistor; R9, Seventh resistor; C1, First capacitor; C2, Second capacitor; R10, First voltage divider resistor. The best embodiment of the present invention

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] This invention provides an interface circuit 200 for an inverter, used to connect to an external power grid dispatching device 100. Referring to FIG1, the power grid dispatching device 100 includes a disconnection identification resistor 110, a disconnection switch unit 120, and multiple power regulation switch units 130. The disconnection identification resistor 110 is connected in parallel with the disconnection switch unit 120, and one end of the disconnection switch unit 120 is grounded.

[0029] The disconnection detection resistor 110 is a built-in resistor in the power grid dispatching equipment 100 used to identify whether the power grid dispatching equipment 100 is disconnected. When the disconnection detection resistor 110 is abnormal, such as exceeding a preset value or being damaged, the power grid dispatching equipment 100 can perform corresponding abnormal control operations. Its identification and control process is conventional technology and will not be elaborated here. Users can operate the power dispatching switch unit of the power grid dispatching equipment 100 to adjust the grid-connected power of the inverter. The disconnection switch unit 120 being activated indicates that the user needs to disconnect the power grid. The number of power regulation switch units 130 can be two or more. For example, the power grid dispatching equipment 100 is equipped with four power regulation switch units 130, as shown in Figure 2 (K1-K4).

[0030] Referring to Figures 1 and 2, in this embodiment of the application, the inverter interface circuit 200 includes a main control chip 210 (U1), a disconnection detection unit 220, a voltage divider unit 230, and a signal amplification unit 240.

[0031] The disconnection detection unit 220 is connected to the other end of the disconnection switch unit 120. The disconnection detection unit 220 is used to detect the disconnection status of the power grid dispatching equipment 100 and pull down the input voltage of the signal amplification unit 240 when the disconnection occurs.

[0032] The voltage divider unit 230 includes a first voltage divider module 231 and multiple second voltage divider modules 232 with different resistance values. The multiple second voltage divider modules 232 are connected in series and then in parallel with multiple power adjustment switch units 130 in a one-to-one correspondence. The first parallel node is grounded, and the second parallel node is connected to one end of the first voltage divider module 231 and the input terminal of the signal amplification unit 240. The other end of the first voltage divider module 231 is connected to an external power supply.

[0033] The analog input port of the main control chip 210 (U1) is connected to the output terminal of the signal amplification unit 240. The main control chip 210 (U1) is used to judge the voltage output by the signal amplification unit 240 and control the grid-connected power generation or disconnect the grid according to the judgment result.

[0034] The inverter interface circuit 200 in this embodiment of the application includes a main control chip 210 (U1), a disconnection detection unit 220, a voltage divider unit 230, and a signal amplification unit 240. The voltage divider unit 230 includes a first voltage divider module 231 and multiple second voltage divider modules 232 with different resistance values. The multiple second voltage divider modules 232 are connected in series and then in parallel with multiple power regulation switch units 130. When a power regulation switch unit 130 is turned on, the corresponding second voltage divider module 232 connected in series is connected to the first voltage divider module 231. The voltage obtained by voltage division with the first voltage divider module 231 is amplified by the signal amplification unit 240 and then transmitted to the main control chip 210 (U1). 1) The main control chip 210 (U1) judges the voltage and controls the output of the corresponding grid-connected power generation, thus having a power dispatch function; and the disconnection detection unit 220 is connected to the other end of the disconnection switch unit 120, which can detect the disconnection status of the external grid dispatching equipment 100 and pull down the input voltage of the signal amplification unit 240 when a disconnection is detected. The voltage is amplified by the signal amplification unit 240 and transmitted to the main control chip 210 (U1). The main control chip 210 (U1) controls the grid to be cut off based on the voltage input by the analog input port. Therefore, this application enables the inverter to have both power dispatch and disconnection detection functions for the grid dispatching equipment 100.

[0035] The main control chip 210 (U1) in this application only needs to use one analog input port to realize power dispatch, and perform the functions of disconnection detection and forced disconnection of the power grid dispatching equipment 100, which can save the analog input port resources of the main control chip 210 (U1).

[0036] The main control chip 210 (U1) has multiple preset voltage values. The main control chip 210 (U1) judges the voltage output by the signal amplification unit 240 and performs corresponding grid-connected power generation control according to the corresponding voltage value. For example, it cuts off the power grid and outputs different levels of grid-connected power generation.

[0037] Referring to Figures 1 and 2, in an optional embodiment of this application, the disconnection detection unit 220 includes a first switch Q1, a second switch Q2, a first Zener diode ZD1, a second Zener diode ZD2, a first pull-up module 221, and a second pull-up module 222. The driving terminal of the first switch Q1 is connected to the negative terminal of the first Zener diode ZD1, the first terminal of the first switch Q1 is connected to an external power supply, the second terminal of the first switch Q1 is connected to the positive terminal of the second Zener diode ZD2 and one end of the second pull-up module 222, the first terminal of the second switch Q2 is grounded, the second terminal of the second switch Q2 is connected to the input terminal of the signal amplification unit 240, the positive terminal of the first Zener diode ZD1 is connected to the negative terminal of the second Zener diode ZD2 and one end of the first pull-up module 221, the other end of the first pull-up module 221 is connected to an external power supply, and the other end of the second pull-up module 222 is connected to the driving terminal of the second switch Q2.

[0038] By setting the first switch Q1, the second switch Q2, the first Zener diode ZD1, the second Zener diode ZD2, the first pull-up module 221, and the second pull-up module 222, when the grid dispatching equipment 100 is disconnected or the resistance of its disconnection identification resistor 110 is greater than the preset value, the voltage at point REF_GEN in Figure 2 will be pulled up through the first pull-up module 221 and the external power supply. If the voltage at point REF_GEN exceeds the sum of the breakdown voltage of the second Zener diode ZD2 and the junction voltage of the second switch Q2, then the second switch Q2 will be turned on, pulling the input voltage of the signal amplification unit 240 down to zero volts, and the main control chip 210 (U1) will control the inverter to disconnect the grid.

[0039] When the disconnection switch unit 120 is activated, the voltage at point REF_GEN in the figure is pulled down to zero volts, which is less than the sum of the breakdown voltage of the first Zener diode ZD1 and the junction voltage of the first switching transistor Q1. Therefore, the first switching transistor Q1 is turned on, and the second pull-up module 222 pulls up the driving terminal of the second switching transistor Q2, so that the second switching transistor Q2 is also turned on. This pulls down the input voltage of the signal amplification unit 240 to zero volts, and the main control chip 210 (U1) controls the inverter to disconnect the power grid.

[0040] When not connected to the grid dispatching equipment 100, the voltage at point REF_GEN in Figure 2 will be pulled up through the first pull-up module 221 and the external power supply. If the voltage at point REF_GEN exceeds the sum of the breakdown voltage of the second Zener diode ZD2 and the junction voltage of the second switch Q2, then the second switch Q2 will be turned on, pulling the input voltage of the signal amplification unit 240 down to zero volts. The main control chip 210 (U1) controls the inverter to disconnect from the grid.

[0041] When the resistance value of the disconnection identification resistor 110 is normal and the disconnection switch unit 120 is in the open state, the voltage at the REF_GEN point does not exceed the sum of the breakdown voltage of the second Zener diode ZD2 and the junction voltage of the second switch Q2. The first switch Q1 and the second switch Q2 are both in the off state, the input voltage of the signal amplification unit 240 will not be pulled down, and the main control chip 210 (U1) will not perform the control of disconnecting the power grid.

[0042] This application implements the disconnection detection of the power grid dispatching equipment 100 with a relatively simple circuit structure, which is beneficial to reducing the volume occupied by the circuit, miniaturizing the inverter, and reducing the cost.

[0043] Optionally, the first switching transistor Q1 is an NPN transistor, with its base serving as the driving terminal, emitter as the first terminal, and collector as the second terminal. Alternatively, the first switching transistor Q1 is a PMOS transistor, with its gate serving as the driving terminal, source as the first terminal, and drain as the second terminal.

[0044] The second switch Q2 is an NPN transistor, with its base serving as the driving terminal, emitter as the first terminal, and collector as the second terminal. Alternatively, the second switch Q2 can be an NMOS transistor, with its gate serving as the driving terminal, source as the first terminal, and drain as the second terminal.

[0045] Optionally, the first pull-up module 221 includes a first pull-up resistor R1, one end of which is connected to an external power supply, and the other end is connected to one end of the disconnect switch unit 120, the positive terminal of the first Zener diode ZD1, and the negative terminal of the second Zener diode ZD2. The second pull-up module 222 includes a second pull-up resistor R2, one end of which is connected to the positive terminal of the second Zener diode ZD2 and the second terminal of the first switching transistor Q1, and the other end is connected to the driving terminal of the second switching transistor Q2.

[0046] When the disconnection switch unit 120 is open or the resistance of the disconnection identification resistor 110 is greater than the preset value, the first pull-up resistor R1 and the external power supply can pull up the voltage at the REF_GEN point, thereby turning on the second switch Q2. When the first switch Q1 is turned on, the second pull-up resistor R2 can pull up the driving terminal voltage of the second switch Q2, turning on the second switch Q2 and thus pulling down the input terminal voltage of the signal amplification unit 240. Using the first pull-up resistor R1 as the first pull-up module 221 and the second pull-up resistor R2 as the second pull-up module 222 results in a simple circuit structure, simplified circuitry, and lower cost.

[0047] In other embodiments, the first pull-up module 221 and the second pull-up module 222 can both use two or more resistors connected in series or in parallel to achieve voltage pull-up.

[0048] Referring to Figures 1 and 2, in an optional embodiment of this application, the disconnection detection unit 220 further includes a first resistor R3 and a second resistor R4. The first resistor R3 is connected in series between the negative terminal of the first Zener diode ZD1 and the driving terminal of the first switching transistor Q1, and the second resistor R4 is connected in series between the positive terminal of the first Zener diode ZD1 and the negative terminal of the second Zener diode ZD2.

[0049] The first resistor R3 limits the current, preventing excessive current from damaging the first switching transistor Q1 and ensuring stable circuit operation. The second resistor R4 also limits the current, preventing excessive current from damaging the second switching transistor Q2 and ensuring stable circuit operation.

[0050] Referring to Figures 1 and 2, in an optional embodiment of this application, the interface circuit 200 of the inverter further includes a signal isolation unit 250. The input terminal of the signal isolation unit 250 is connected to the connection node between the first voltage divider module 231 and the second voltage divider module 232, and the output terminal is connected to the input terminal of the signal amplification unit 240.

[0051] By setting up the signal isolation unit 250, electrical isolation can be provided, which can isolate external signals from the internal power supply of the inverter, isolate external signals from interference to the internal circuit of the inverter, and improve the stability and reliability of the circuit operation.

[0052] Optionally, the signal isolation unit 250 includes a third resistor R5 and an isolation linear optocoupler U2. The third resistor R5 is connected in series between the connection node of the first voltage divider module 231 and the second voltage divider module 232 and the input terminal of the isolation linear optocoupler U2. The output terminal of the isolation linear optocoupler U2 is connected to the input terminal of the signal amplification unit 240.

[0053] An isolation linear optocoupler U2 is an electronic component used to isolate signal transmission between two circuits. It typically consists of a light-emitting diode (LED) and a photodiode, with signal transmission occurring optically. When an electrical signal is applied to the LED, it emits a light signal, which is then received by the photodiode and converted into an electrical signal for output to the other circuit. Specifically, the isolation linear optocoupler U2 employs a 1:1 transmission method.

[0054] The third resistor R5 can limit the current and prevent excessive current from damaging the isolation linear optocoupler U2.

[0055] By setting a third resistor R5 and an isolation linear optocoupler U2, the external signal and internal power supply can be isolated with a relatively simple circuit structure, reducing the size occupied by the circuit and facilitating the miniaturization of the inverter.

[0056] Referring to Figures 1 and 2, in an optional embodiment of this application, the signal amplification unit 240 includes an operational amplifier U3, a fourth resistor R6, a fifth resistor R7, a sixth resistor R8, and a seventh resistor R9. The fourth resistor R6 is connected in series between the positive terminal of the output of the isolation linear optocoupler U2 and the non-inverting input terminal of the operational amplifier U3. The fifth resistor R7 is connected in series between the negative terminal of the output of the isolation linear optocoupler U2 and the inverting input terminal of the operational amplifier U3. The sixth resistor R8 is connected in series between the non-inverting input terminal of the operational amplifier U3 and ground. The seventh resistor R9 is connected in series between the output terminal and the inverting input terminal of the operational amplifier U3.

[0057] By setting up operational amplifier U3, fourth resistor R6, fifth resistor R7, sixth resistor R8 and seventh resistor R9, a differential operational amplifier circuit is constructed. This circuit can amplify the differential part of the input signal, that is, the difference between the two input signals, while suppressing the common-mode part, that is, the common part of the two input signals. This helps to improve the signal's anti-interference capability.

[0058] Optionally, the signal amplification unit 240 further includes a first capacitor C1 and a second capacitor C2, wherein the first capacitor C1 is connected in parallel with the sixth resistor R8, and the second capacitor C2 is connected in parallel with the seventh resistor R9.

[0059] By connecting the first capacitor C1 in parallel with the sixth resistor R8, and the second capacitor C2 in parallel with the seventh resistor R9, the bandwidth and attenuation factor of the input signal can be improved.

[0060] Referring to Figures 1 and 2, in an optional embodiment of this application, the first voltage divider module 231 includes a first voltage divider resistor R10, and the second voltage divider module 232 includes a second voltage divider resistor. Multiple second voltage divider resistors are connected in series and then in parallel with multiple power adjustment switch units 130 in a one-to-one correspondence. The first parallel node is grounded, and the second parallel node is connected to one end of the first voltage divider resistor R10 and the input terminal of the signal isolation unit 250. The other end of the first voltage divider resistor R10 is connected to an external power supply, and the resistance values ​​of the multiple second voltage divider resistors are different.

[0061] A first voltage divider resistor R10 is used as the first voltage divider module 231, and a second voltage divider resistor is used as the second voltage divider module 232. When a power regulation switch unit 130 is closed, the corresponding series-connected second voltage divider resistor is connected in series with the first voltage divider resistor R10. The series connection node is connected to the input terminal of the signal isolation unit 250. Since the resistance value of the second voltage divider resistor connected in series with each power regulation unit is different, when the user performs power dispatch, the corresponding voltage point input to the input terminal of the signal isolation unit 250 is different each time one of the power regulation units is switched on. The main control chip 210 (U1) can control the output of the corresponding grid-connected power according to the different voltage points to realize power dispatch. For example, four power regulation units are set, K1-K4 as shown in Figure 2, and four corresponding second voltage divider resistors R111, R112, R113, and R114 are set; the disconnection switch unit 120 is K0 as shown in Figure 2. When K0 is closed, the voltage input to the input terminal of the signal isolation unit 250 is 0; when K1 is closed, the voltage input to the input terminal of the signal isolation unit 250 is... V1 is defined as follows: When K2 is closed, the voltage input to the signal isolation unit 250 is... V2 is defined as follows: When K3 is closed, the voltage input to the signal isolation unit 250 is... Defined as V3; when K4 is closed, the voltage input to the signal isolation unit 250 is V4 is defined as the input voltage. The control logic of the main control chip 210 (U1) for these four voltage points can be as follows: when the input voltage is 0, control the inverter to disconnect from the grid; when the input voltage is V1, control the inverter to not output power; when the input voltage is V2, control the inverter to output grid-connected power not exceeding 25%; when the input voltage is V3, control the inverter to output grid-connected power not exceeding 75%; when the input voltage is V4, control the inverter to output the maximum grid-connected power.

[0062] Using a first voltage divider resistor R10 as the first voltage divider module 231 and a second voltage divider resistor as the second voltage divider module 232, the circuit structure of the entire voltage divider unit 230 is relatively simple and the cost is low. In other embodiments, the first voltage divider module 231 and the second voltage divider module 232 can also be composed of multiple resistors connected in series or in parallel.

[0063] This application also provides an inverter. The inverter includes the interface circuit 200 of the inverter as described above.

[0064] In this embodiment of the inverter, the interface circuit includes a main control chip 210 (U1), a disconnection detection unit 220, a voltage divider unit 230, and a signal amplification unit 240. The voltage divider unit 230 includes a first voltage divider module 231 and multiple second voltage divider modules 232 with different resistance values. The multiple second voltage divider modules 232 are connected in series and then in parallel with multiple power regulation switch units 130. When a power regulation switch unit 130 is turned on, the corresponding series-connected second voltage divider module 232 is connected to the first voltage divider module 231. The voltage obtained by voltage division with the first voltage divider module 231 is amplified by the signal amplification unit 240 and then transmitted to the main control chip 210 (U1). The main control chip 210 (U1) judges the voltage and controls the output of the corresponding grid-connected power generation, thus having a power dispatch function. Furthermore, the disconnection detection unit 220 is connected to the other end of the disconnection switch unit 120, which can detect the disconnection status of the external grid dispatching equipment 100 and pull down the input voltage of the signal amplification unit 240 when a disconnection is detected. This voltage is amplified by the signal amplification unit 240 and transmitted to the main control chip 210 (U1). The main control chip 210 (U1) controls the grid to be cut off based on the voltage input by the analog input port. Therefore, this application enables the inverter to have both power dispatch and disconnection detection functions for the grid dispatching equipment 100.

[0065] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. An interface circuit for an inverter, characterized in that, For connecting to external power grid dispatching equipment, the power grid dispatching equipment includes a disconnection detection resistor, a disconnection switch unit, and multiple power regulation switch units. The disconnection detection resistor is connected in parallel with the disconnection switch unit, and one end of the disconnection switch unit is grounded. The inverter's interface circuit includes a main control chip, a disconnection detection unit, a voltage divider unit, and a signal amplification unit. The disconnection detection unit is connected to the other end of the disconnection switch unit. The disconnection detection unit is used to detect the disconnection status of the power grid dispatching equipment and pull down the input voltage of the signal amplification unit when the disconnection occurs. The voltage divider unit includes a first voltage divider module and multiple second voltage divider modules with different resistance values. The multiple second voltage divider modules are connected in series and then in parallel with the multiple power adjustment switch units in a one-to-one correspondence. The first parallel node is grounded, and the second parallel node is connected to one end of the first voltage divider module and the input terminal of the signal amplification unit. The other end of the first voltage divider module is connected to an external power supply. The analog input port of the main control chip is connected to the output terminal of the signal amplification unit. The main control chip is used to judge the voltage output by the signal amplification unit and control the grid-connected power generation or disconnect the grid according to the judgment result.

2. The interface circuit of the inverter according to claim 1, characterized in that, The disconnection detection unit includes a first switching transistor, a second switching transistor, a first Zener diode, a second Zener diode, a first pull-up module, and a second pull-up module. The driving terminal of the first switching transistor is connected to the negative terminal of the first Zener diode. The first terminal of the first switching transistor is connected to an external power supply. The second terminal of the first switching transistor is connected to the positive terminal of the second Zener diode and one terminal of the second pull-up module. The first terminal of the second switching transistor is grounded. The second terminal of the second switching transistor is connected to the input terminal of the signal amplification unit. The positive terminal of the first Zener diode is connected to the negative terminal of the second Zener diode and one terminal of the first pull-up module. The other terminal of the first pull-up module is connected to an external power supply. The other terminal of the second pull-up module is connected to the driving terminal of the second switching transistor.

3. The interface circuit of the inverter according to claim 2, characterized in that, The wire breakage detection unit further includes a first resistor and a second resistor. The first resistor is connected in series between the negative terminal of the first Zener diode and the driving terminal of the first switching transistor, and the second resistor is connected in series between the positive terminal of the first Zener diode and the negative terminal of the second Zener diode.

4. The interface circuit of the inverter according to any one of claims 1-3, characterized in that, The inverter's interface circuit also includes a signal isolation unit. The input terminal of the signal isolation unit is connected to the connection node between the first voltage divider module and the second voltage divider module, and the output terminal is connected to the input terminal of the signal amplification unit.

5. The interface circuit of the inverter according to claim 4, characterized in that, The signal isolation unit includes a third resistor and an isolation linear optocoupler. The third resistor is connected in series between the connection node of the first voltage divider module and the second voltage divider module and the input terminal of the isolation linear optocoupler. The output terminal of the isolation linear optocoupler is connected to the input terminal of the signal amplification unit.

6. The interface circuit of the inverter according to claim 5, characterized in that, The signal amplification unit includes an operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. The fourth resistor is connected in series between the positive terminal of the output of the isolated linear optocoupler and the non-inverting input terminal of the operational amplifier. The fifth resistor is connected in series between the negative terminal of the output of the isolated linear optocoupler and the inverting input terminal of the operational amplifier. The sixth resistor is connected in series between the non-inverting input terminal of the operational amplifier and ground. The seventh resistor is connected in series between the output terminal and the inverting input terminal of the operational amplifier.

7. The interface circuit of the inverter according to claim 6, characterized in that, The signal amplification unit further includes a first capacitor and a second capacitor, wherein the first capacitor is connected in parallel with the sixth resistor, and the second capacitor is connected in parallel with the seventh resistor.

8. The interface circuit of the inverter according to claim 4, characterized in that, The first voltage divider module includes a first voltage divider resistor, and the second voltage divider module includes a second voltage divider resistor. Multiple second voltage divider resistors are connected in series with multiple power adjustment switch units and then connected in parallel. The first parallel node is grounded, and the second parallel node is connected to one end of the first voltage divider resistor and the input terminal of the signal isolation unit. The other end of the first voltage divider resistor is connected to an external power supply. The resistance values ​​of the multiple second voltage divider resistors are different.

9. The interface circuit of the inverter according to claim 2, characterized in that, The first pull-up module includes a first pull-up resistor, one end of which is connected to an external power supply, and the other end is connected to one end of the disconnect switch unit, the positive terminal of the first Zener diode, and the negative terminal of the second Zener diode. The second pull-up module includes a second pull-up resistor, one end of which is connected to the positive terminal of the second Zener diode and the second terminal of the first switch, and the other end is connected to the driving terminal of the second switch.

10. An inverter, characterized in that, Includes the interface circuit of the inverter as described in any one of claims 1-9.

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