Method and device for acquiring input current of single-phase alternating-current frequency converter and frequency converter

Abstract

The invention discloses a single-phase AC frequency converter input current obtaining method and device and a frequency converter, and the method comprises the steps: obtaining a DC bus voltage in a single-phase AC frequency converter, determining a load current and a bus capacitor ripple current according to the DC bus voltage, and determining a DC side current according to the load current and the bus capacitor ripple current; and determining the input current in the single-phase alternating-current frequency converter according to the direct-current side current. According to the application, the input current in the single-phase alternating current frequency converter can be obtained through the circuit parameters which can be directly obtained in the single-phase alternating current frequency converter, and the cost of obtaining the input current of the single-phase alternating current frequency converter can be greatly reduced.

Description

Technical Field

[0001] The present application relates to the technical field of frequency converters, and in particular to a method and device for obtaining input current of a single-phase AC frequency converter, and a frequency converter. Background Art

[0002] A typical drive structure of a single-phase AC inverter is an AC-DC-AC inverter system consisting of a rectifier, a DC-side reactor, a DC bus capacitor, and an inverter. The input quantity of a single-phase AC inverter mainly includes single-phase input voltage, input current, and input power factor. Generally, it is necessary to obtain relevant information of the input quantity in real time for voltage frequency limiting, current frequency limiting, overvoltage, undervoltage, and overcurrent protection on the input side.

[0003] In the related art, when obtaining the input current of a single-phase AC inverter, a current transformer is usually required to obtain the input current. This method requires the current transformer to be connected to the circuit, which makes the hardware cost of obtaining the input current of the single-phase AC inverter high. Summary of the invention

[0004] The embodiments of the present application provide a method, device and inverter for obtaining the input current of a single-phase AC inverter, which can greatly reduce the cost of obtaining the input current of the single-phase AC inverter.

[0005] In a first aspect, an embodiment of the present application provides a method for obtaining input current of a single-phase AC inverter, comprising:

[0006] Obtain the DC bus voltage in a single-phase AC inverter;

[0007] Determine the load current according to the DC bus voltage;

[0008] Determine the bus capacitor ripple current based on the DC bus voltage;

[0009] Determine the DC side current based on the load current and the bus capacitor ripple current;

[0010] The input current in a single-phase AC inverter is determined based on the DC side current.

[0011] In some embodiments, determining the input current in the single-phase AC inverter according to the DC side current includes:

[0012] Determine the effective value of the DC side current;

[0013] The effective value of the DC side current is taken as the effective value of the input current of the single-phase AC inverter.

[0014] In some embodiments, determining the load current according to the DC bus voltage includes:

[0015] Obtain the load active power in a single-phase AC inverter;

[0016] Calculate the quotient of load active power and DC bus voltage;

[0017] The quotient is taken as the load current.

[0018] In some embodiments, determining the bus capacitor ripple current according to the DC bus voltage includes:

[0019] Extracting the DC bus voltage harmonic components corresponding to the DC bus voltage;

[0020] The bus capacitor ripple current is determined based on the DC bus voltage harmonic components.

[0021] In some embodiments, extracting the DC bus voltage harmonic component corresponding to the DC bus voltage includes:

[0022] A DC component, a 1-time grid frequency component and a 2-time grid frequency component are extracted from the DC bus voltage.

[0023] In some embodiments, determining the bus capacitor ripple current according to the DC bus voltage harmonic component includes:

[0024] Get the DC bus capacitance value in a single-phase AC inverter;

[0025] The bus capacitor ripple current is determined based on the DC component, 1 times the grid frequency component, 2 times the grid frequency component and the DC bus capacitor value.

[0026] In some embodiments, determining the DC side current according to the load current and the bus capacitor ripple current includes:

[0027] Calculate the sum of the load current and the bus capacitor ripple current;

[0028] The sum is taken as the DC side current.

[0029] In a second aspect, an embodiment of the present application further provides a device for acquiring input current of a single-phase AC inverter, comprising:

[0030] An acquisition module, used for acquiring a DC bus voltage in a single-phase AC inverter;

[0031] A first determination module, used to determine the load current according to the DC bus voltage;

[0032] A second determination module is used to determine the bus capacitor ripple current according to the DC bus voltage;

[0033] A third determination module is used to determine the DC side current according to the load current and the bus capacitor ripple current;

[0034] The fourth determination module is used to determine the input current in the single-phase AC inverter according to the DC side current.

[0035] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program runs on a computer, the computer executes a method for obtaining the input current of a single-phase AC inverter as provided in any embodiment of the present application.

[0036] In a fourth aspect, an embodiment of the present application further provides a frequency converter, including a processor and a memory, the memory having a computer program, and the processor calls the computer program to execute a method for obtaining the input current of a single-phase AC frequency converter as provided in any embodiment of the present application.

[0037] In a fifth aspect, an embodiment of the present application further provides an air-conditioning device, which includes the inverter provided in an embodiment of the present application.

[0038] The technical solution provided by the embodiment of the present application obtains the DC bus voltage in the single-phase AC inverter, determines the load current and the bus capacitor ripple current according to the DC bus voltage, determines the DC side current according to the load current and the bus capacitor ripple current, and determines the input current in the single-phase AC inverter according to the DC side current. In the present application, the input current in the single-phase AC inverter can be obtained through the circuit parameters that can be directly obtained in the single-phase AC inverter, which can greatly reduce the cost of obtaining the input current of the single-phase AC inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 A schematic flow chart of a method for obtaining input current of a single-phase AC inverter provided in an embodiment of the present application.

[0041] Figure 2 A single-phase AC side reactance passive PFC circuit topology is provided in an embodiment of the present application.

[0042] Figure 3 A schematic diagram showing that the effective value of the input current provided in the present application is equal to the effective value of the DC side current.

[0043] Figure 4 A schematic diagram of the structure of a device for acquiring input current of a single-phase AC inverter provided in an embodiment of the present application.

[0044] Figure 5A first structural schematic diagram of the frequency converter provided in an embodiment of the present application.

[0045] Figure 6 A second structural schematic diagram of the frequency converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0047] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0048] An embodiment of the present application provides a method for obtaining the input current of a single-phase AC inverter. The executor of the method for obtaining the input current of a single-phase AC inverter can be the single-phase AC inverter input current obtaining device provided in the embodiment of the present application, or an inverter integrating the single-phase AC inverter input current obtaining device, wherein the single-phase AC inverter input current obtaining device can be implemented in hardware or software.

[0049] A typical drive structure of a single-phase AC inverter is an AC-DC-AC inverter system consisting of a rectifier, a DC-side reactor, a DC bus capacitor, and an inverter. The input quantity of a single-phase AC inverter mainly includes single-phase input voltage Vac, single-phase input current Iac, and input power factor PF. Generally, it is necessary to obtain relevant information of the input quantity in real time for voltage frequency limiting, current frequency limiting, overvoltage, undervoltage, and overcurrent protection on the input side.

[0050] At present, most solutions use current transformers to obtain input current Iac, which has the highest hardware cost. In order to solve the above-mentioned problem of high cost, the present application provides a method for obtaining the input current of a single-phase AC inverter, which obtains the DC bus voltage in the single-phase AC inverter, determines the load current and the bus capacitor ripple current according to the DC bus voltage, determines the DC side current according to the load current and the bus capacitor ripple current, and determines the input current in the single-phase AC inverter according to the DC side current. In the present application, the input current in the single-phase AC inverter can be obtained through the circuit parameters that can be directly obtained in the single-phase AC inverter, which can greatly reduce the cost of obtaining the input current of the single-phase AC inverter.

[0051] In addition, in the related art, Vac can be sampled through a voltage sampling circuit, and then the input current Iac is calculated based on the sampled Vac and the load power. This method also increases the hardware cost, and the input power factor is required to participate in the calculation of Iac, and the input power factor is difficult to obtain. If a fixed value is taken, the calculation error of Iac will become larger. There are also solutions without voltage sampling circuits in the related art, that is, Vac is calculated based on the DC bus voltage, and the DC bus voltage is compensated according to the load size, and then Iac is calculated based on the estimated Vac and load power. This method requires the compensation coefficient to be calibrated in advance, and the compensation error is large. In addition, the power factor is difficult to obtain, resulting in a large error in the calculation of Iac.

[0052] The method for obtaining the input current of a single-phase AC inverter provided by the present application can also solve the problem of large calculation errors and improve the accuracy of the input current of the single-phase AC inverter obtained. The present application directly uses the physical model of the single-phase AC side reactance passive PFC circuit for calculation, has a strong theoretical basis, high calculation accuracy, does not require an input side sampling circuit, and does not require advance test calibration data, which can not only greatly save hardware costs and development and testing resources, but also improve the accuracy of the input current of the single-phase AC inverter obtained.

[0053] Next, see Figure 1 , Figure 1 The first flow chart of the method for obtaining the input current of a single-phase AC inverter provided in the embodiment of the present application is as follows:

[0054] S110. Obtain a DC bus voltage in a single-phase AC inverter.

[0055] The DC bus voltage in the inverter refers to the voltage on the DC bus inside the inverter, which is an important reference value for the inverter's output AC voltage. The DC bus voltage directly affects the quality and stability of the inverter's output voltage.

[0056] Specifically, the DC bus voltage in the DC bus can be sampled by a voltage sampling module, and the sampling period can be set to real-time sampling or sampling once every preset time interval according to actual needs, and the preset time is the time interval between two adjacent sampling periods. Among them, the voltage sampling module can be an analog to digital converter (ADC).

[0057] For example, the inverter can automatically sample the DC bus voltage according to the sampling period during operation, or the user can input sampling instructions through the inverter's human-machine interaction device according to actual needs, or send sampling instructions to the inverter through a user terminal connected to the inverter to control the inverter to start sampling the DC bus voltage.

[0058] Among them, the human-machine interaction device of the frequency converter may include at least one of a physical button, a touch sensor, a gesture recognition sensor and a voice recognition unit, so that the user can input instructions through the corresponding touch mode, gesture control mode or voice control mode. The physical button and the touch sensor can be set at any position of the frequency converter, for example, a control panel. The touch mode of the physical button can be specifically pressing or toggling. The touch mode of the touch sensor can be specifically pressing or touching. The gesture recognition sensor can be set at any position outside the housing of the frequency converter. The gestures used to control the frequency converter can be customized by the user according to actual needs or adopt the factory default settings. The voice recognition unit may include a microphone and a voice recognition chip, or may only include a microphone and the voice recognition function is realized by the processor of the frequency converter. The voice used to control the frequency converter can be customized by the user according to actual needs or adopt the factory default settings.

[0059] Among them, the user terminal can be a mobile phone, a smart bracelet, a tablet computer, a laptop computer, a personal digital assistant (PDA), a computer, a server, etc., which has wireless or wired communication functions and can communicate with the inverter. The embodiment of the present application does not impose any restrictions on the specific type of the user terminal. The user can control the user terminal to send instructions to the inverter through any human-computer interaction method supported by the user terminal. The human-computer interaction method supported by the user terminal can be the same as that of the inverter, which will not be repeated here. For example, when the inverter is applied to air-conditioning equipment, the user terminal can specifically be a computer device applied to the air-conditioning centralized control system.

[0060] S120. Determine the load current according to the DC bus voltage.

[0061] In an embodiment of the present application, when determining the load current based on the DC bus voltage, the load active power in the single-phase AC inverter can be obtained, and then the quotient of the load active power and the DC bus voltage is calculated, and the quotient is the load current.

[0062] Specifically, the expression of the load current is as follows:

[0063] Iload=Pout / Vdc

[0064] Where Iload is the load current, Pout is the load active power, and Vdc is the DC bus voltage.

[0065] S130. Determine a bus capacitor ripple current according to the DC bus voltage.

[0066] In the embodiment of the present application, when determining the bus capacitor ripple current based on the DC bus voltage, the DC bus voltage harmonic component corresponding to the DC bus voltage can be extracted, and the bus capacitor ripple current can be determined based on the DC bus voltage harmonic component.

[0067] In this embodiment, the DC bus voltage can be low-pass filtered to remove the high-frequency component therein to obtain the DC component containing the low-frequency component. For example, the DC bus voltage can be filtered by a low-pass filter, and the low-pass filter can select a filter device with a corresponding cut-off frequency according to actual needs, for example, a first-order low-pass filter. The cut-off frequency of the low-pass filter needs to be low enough to ensure that the high-frequency component can be accurately filtered out to obtain the DC component.

[0068] The part of the DC bus voltage minus the DC component is the ripple component, and the ripple component can be obtained by calculating the difference between the DC bus voltage and the DC component. For example, the difference between the DC bus voltage and the DC component can be calculated by a first subtractor, and the first subtractor can be a differential amplifier. The ripple component is further filtered to obtain the harmonic component therein, that is, to obtain a 1x grid frequency component and a 2x grid frequency component.

[0069] Specifically, when extracting the DC bus voltage harmonic component corresponding to the DC bus voltage, a DC component VDC, a 1 times grid frequency component Vh1, and a 2 times grid frequency component Vh2 are extracted from the DC bus voltage.

[0070] That is, Vdc = VDC + Vh1 + Vh2

[0071] Vh1=VH1·sin(ωt+θ1)

[0072] Vh2=VH2·sin(2ωt+θ2)

[0073] Where VH1 and VH2 are the voltage amplitudes of 1 and 2 times the grid frequency components, θ1 and θ2 are the voltage phases of 1 and 2 times the grid frequency components, and ω is the grid frequency.

[0074] Specifically, when determining the bus capacitor ripple current according to the harmonic component of the DC bus voltage, the DC bus capacitor capacitance in the single-phase AC inverter is obtained, and the bus capacitor ripple current is determined according to the DC component, 1 times the grid frequency component, 2 times the grid frequency component and the DC bus capacitor capacitance.

[0075] Among them, the expression for determining the bus capacitor ripple current based on the DC bus voltage is as follows:

[0076] Icap=C·d(Vdc) / dt

[0077] =C·d(VDC+Vh1+Vh2) / dt

[0078] =C·dVh1 / dt+C·dVh2 / dt

[0079] =ωCVH1·sin(ωt+θ1+π / 2)+2ωCVH2·sin(2ωt+θ2+π / 2)

[0080] Where Icap is the bus capacitor ripple current, and C is the DC bus capacitor value.

[0081] S140. Determine the DC side current according to the load current and the bus capacitor ripple current.

[0082] Specifically, in the embodiment of the present application, when the DC side current is determined according to the load current and the bus capacitor ripple current, the sum of the load current and the bus capacitor ripple current is calculated, and the sum is used as the DC side current.

[0083] The expression of the DC side current is as follows:

[0084] Idcin=Icap+Iload

[0085] Where, Idcin is the DC side current, Icap is the bus capacitor ripple current, and Iload is the load current.

[0086] S150. Determine the input current in the single-phase AC inverter according to the DC side current.

[0087] In this embodiment, when the DC side current is obtained, the effective value Idcin_rms of the DC side current can be calculated according to the effective value definition, and the effective value Idcin_rms is used as the effective value Iac_rms of the input current of the single-phase AC inverter.

[0088] Please note that, please refer to Figure 2 , Figure 2 A single-phase AC side reactance passive PFC circuit topology is provided in an embodiment of the present application, and the circuit topology illustrates the relationship between the circuit parameters involved in the present application. Wherein, Idcin is the DC side current, Icap is the bus capacitor ripple current, C is the DC bus capacitor capacitance, Iload is the load current, Vdcin is the DC bus voltage, L1 is the power supply, VLin is the AC voltage input to the circuit, Lin is the reactance, iLi is the input current, and Motor is the motor. It should be noted that Vdc is used to indicate the DC bus voltage, and Iac is used to indicate the input current. Please refer to Figure 3 , Figure 3 The schematic diagram of the input current effective value provided by this application is equal to the DC side current effective value, Figure 3 Provided in the embodiments of this application Figure 2 When the single-phase AC side reactance passive PFC circuit is working normally, the relationship between the DC side current and the input current, where the red line corresponds to the DC side current and the blue line corresponds to the input current. From the figure, it can be seen that the effective value of the input current Iac is equal to the effective value of the DC side current Idcin. Figure 2 , Figure 3 The above relationship between the circuit parameters illustrated in the figure can be used to directly calculate the input current based on the physical model of the single-phase AC side reactance passive PFC circuit.

[0089] In order to verify the effectiveness of the method for obtaining the input current of a single-phase AC inverter provided in the embodiment of the present application, in an actual application scenario, the method was verified on a 615 three-phase small multi-split air conditioner system. Specifically, the calculated input current values ​​of the compressors running at different frequencies under different voltages were tested and compared with the current measured by the oscilloscope. The test results are shown in Tables 1, 2 and 3 below:

[0090]

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095]

[0096] Table 3

[0097] From the above test results, it can be seen that the average error between the calculated value and the measured value of the input current Iac under various voltages and loads is within 0.5A, and part of it is the calculation accuracy deviation (different decimal places). This confirms the effectiveness and practical application value of the method for obtaining the input current of a single-phase AC inverter provided in the embodiment of the present application.

[0098] In specific implementation, the present application is not limited by the execution order of the various steps described. If no conflict occurs, some steps can be performed in other orders or simultaneously.

[0099] As can be seen from the above, the method for obtaining the input current of a single-phase AC inverter provided in an embodiment of the present application obtains the DC bus voltage in the single-phase AC inverter, determines the load current and the bus capacitor ripple current according to the DC bus voltage, determines the DC side current according to the load current and the bus capacitor ripple current, and determines the input current in the single-phase AC inverter according to the DC side current. In the present application, the input current in the single-phase AC inverter can be obtained through the circuit parameters that can be directly obtained in the single-phase AC inverter, which can greatly reduce the cost of obtaining the input current of the single-phase AC inverter.

[0100] In one embodiment, a device for obtaining input current of a single-phase AC inverter is also provided. Figure 4 , Figure 4 A schematic diagram of the structure of a device 200 for acquiring input current of a single-phase AC inverter provided in an embodiment of the present application. The device 200 for acquiring input current of a single-phase AC inverter is applied to an inverter, and the device 200 for acquiring input current of a single-phase AC inverter includes an acquisition module 201, a first determination module 202, a second determination module 203, a third determination module 204, and a fourth determination module 205, as follows:

[0101] An acquisition module 201 is used to acquire a DC bus voltage in a single-phase AC inverter;

[0102] A first determination module 202, configured to determine a load current according to a DC bus voltage;

[0103] A second determination module 203, configured to determine a bus capacitor ripple current according to a DC bus voltage;

[0104] A third determination module 204 is used to determine the DC side current according to the load current and the bus capacitor ripple current;

[0105] The fourth determination module 205 is used to determine the input current in the single-phase AC inverter according to the DC side current.

[0106] In some embodiments, the fourth determination module 205 may be used to:

[0107] Determine the effective value of the DC side current;

[0108] The effective value of the DC side current is taken as the effective value of the input current of the single-phase AC inverter.

[0109] In some embodiments, the first determining module 202 may be used to:

[0110] Obtain the load active power in a single-phase AC inverter;

[0111] Calculate the quotient of load active power and DC bus voltage;

[0112] The quotient is taken as the load current.

[0113] In some embodiments, the second determining module 203 may be used to:

[0114] Extracting the DC bus voltage harmonic components corresponding to the DC bus voltage;

[0115] The bus capacitor ripple current is determined based on the DC bus voltage harmonic components.

[0116] In some embodiments, the second determining module 203 may be used to:

[0117] A DC component, a 1-time grid frequency component and a 2-time grid frequency component are extracted from the DC bus voltage.

[0118] In some embodiments, the second determining module 203 may be used to:

[0119] Get the DC bus capacitance value in a single-phase AC inverter;

[0120] The bus capacitor ripple current is determined based on the DC component, 1 times the grid frequency component, 2 times the grid frequency component and the DC bus capacitor value.

[0121] In some embodiments, the third determination module 204 may be used to:

[0122] Calculate the sum of the load current and the bus capacitor ripple current;

[0123] The sum is taken as the DC side current.

[0124] It should be noted that the single-phase AC inverter input current acquisition device provided in the embodiment of the present application and the single-phase AC inverter input current acquisition method in the above embodiment belong to the same concept, and any method provided in the single-phase AC inverter input current acquisition method embodiment can be implemented through the single-phase AC inverter input current acquisition device. The specific implementation process is detailed in the single-phase AC inverter input current acquisition method embodiment, which will not be repeated here.

[0125] In addition, in order to better implement the method for obtaining the input current of the single-phase AC inverter in the embodiment of the present application, based on the method for obtaining the input current of the single-phase AC inverter, the present application also provides a frequency converter, please refer to Figure 5 , Figure 5 A schematic diagram of the structure of the frequency converter 300 provided in the present application is shown. Figure 5 As shown, the inverter 300 provided in the present application includes a processor 301 and a memory 302. The processor 301 is used to implement the steps of the method for obtaining the input current of the single-phase AC inverter in the above embodiment of the present application when executing the computer program stored in the memory 302, such as:

[0126] Obtain the DC bus voltage in a single-phase AC inverter;

[0127] Determine the load current according to the DC bus voltage;

[0128] Determine the bus capacitor ripple current based on the DC bus voltage;

[0129] Determine the DC side current based on the load current and the bus capacitor ripple current;

[0130] The input current in a single-phase AC inverter is determined based on the DC side current.

[0131] In some implementations, when the processor 301 determines the input current in the single-phase AC inverter according to the DC side current, the processor 301 may execute:

[0132] Determine the effective value of the DC side current;

[0133] The effective value of the DC side current is taken as the effective value of the input current of the single-phase AC inverter.

[0134] In some implementations, when determining the load current according to the DC bus voltage, the processor 301 may execute:

[0135] Obtain the load active power in a single-phase AC inverter;

[0136] Calculate the quotient of load active power and DC bus voltage;

[0137] The quotient is taken as the load current.

[0138] In some implementations, when determining the bus capacitor ripple current according to the DC bus voltage, the processor 301 may execute:

[0139] Extracting the DC bus voltage harmonic components corresponding to the DC bus voltage;

[0140] The bus capacitor ripple current is determined based on the DC bus voltage harmonic components.

[0141] In some implementations, when extracting the DC bus voltage harmonic component corresponding to the DC bus voltage, the processor 301 may execute:

[0142] A DC component, a 1-time grid frequency component and a 2-time grid frequency component are extracted from the DC bus voltage.

[0143] In some implementations, when determining the bus capacitor ripple current according to the DC bus voltage harmonic component, the processor 301 may execute:

[0144] Get the DC bus capacitance value in a single-phase AC inverter;

[0145] The bus capacitor ripple current is determined based on the DC component, 1 times the grid frequency component, 2 times the grid frequency component and the DC bus capacitor value.

[0146] In some implementations, when determining the DC side current according to the load current and the bus capacitor ripple current, the processor 301 may execute:

[0147] Calculate the sum of the load current and the bus capacitor ripple current;

[0148] The sum is taken as the DC side current.

[0149] Exemplarily, the computer program may be divided into one or more modules / units, one or more modules / units are stored in the memory 302, and executed by the processor 301 to complete the embodiment of the present application. One or more modules / units may be a series of computer program instruction segments that can complete specific functions, and the instruction segments are used to describe the execution process of the computer program in the computer device.

[0150] The inverter 300 may include, but is not limited to, a processor 301 and a memory 302. Those skilled in the art will appreciate that the illustration is merely an example of the inverter 300 and does not constitute a limitation on the inverter 300. The inverter 300 may include more or fewer components than shown in the illustration, or may combine certain components, or different components. The inverter provided in the embodiment of the present application may be applied to air conditioning equipment.

[0151] The processor 301 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the inverter 300, and uses various interfaces and lines to connect various parts of the entire inverter 300.

[0152] The memory 302 can be used to store computer programs and / or modules. The processor 301 implements various functions of the computer device by running or executing the computer programs and / or modules stored in the memory 302 and calling the data stored in the memory 302. The memory 302 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the inverter 300 (such as audio data, video data, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0153] Technicians in the relevant field can clearly understand that, for the convenience and simplicity of description, the specific working process of the single-phase AC inverter input current acquisition device, the inverter 300 and its corresponding units described above can refer to the description of the single-phase AC inverter input current acquisition method in the above embodiments of the present application, and the details will not be repeated here.

[0154] A person of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0155] In some embodiments, see Figure 6 , Figure 6The second structural diagram of the frequency converter provided in the embodiment of the present application. The frequency converter includes: a rectifier 303, an inverter 304, at least one processor 301 ( Figure 6 Only one processor is shown in the figure), a memory 302, and a computer program 305 stored in the memory 302 and executable on at least one processor 301, the rectifier 303 is used to connect to the DC bus 306, the inverter 304 is used to connect to the DC bus 306 and the motor 400 respectively, and when the processor 301 executes the computer program 305, the steps in the above-mentioned method for obtaining the input current of each single-phase AC inverter are implemented.

[0156] In some embodiments, the frequency converter may include, but is not limited to, a rectifier, an inverter, a processor, and a memory, and may also include an analog-to-digital converter, a low-pass filter, a subtractor, a notch filter, a second-order generalized integrator, a phase-locked loop, an amplitude-locked loop, a subtractor, etc. Those skilled in the art will understand that Figure 6 This is only an example of a frequency converter and does not constitute a limitation on the frequency converter. It may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, it may also include input and output devices, network access devices, etc. The input and output devices may include the aforementioned human-computer interaction devices, and may also include a display screen for displaying the working parameters of the frequency converter. The network access device may include a communication module for the frequency converter to communicate with the aforementioned user terminal.

[0157] Among them, the inverter is a device used to convert direct current power into alternating current, which can be composed of a three-phase inverter bridge arm, a logic control circuit and a filter circuit.

[0158] It should be noted that, a person skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the storage medium can include but is not limited to: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0159] Since the instructions stored in the computer-readable storage medium can execute the steps in the method for obtaining the input current of the single-phase AC inverter in the above embodiments of the present application, the beneficial effects that can be achieved by the method for obtaining the input current of the single-phase AC inverter in the above embodiments of the present application can be achieved. Please see the previous description for details and will not be repeated here.

[0160] In addition, the terms "first", "second", and "third" in this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or modules is not limited to the listed steps or modules, but some embodiments also include steps or modules that are not listed, or some embodiments also include other steps or modules inherent to these processes, methods, products, or devices.

[0161] The above is a detailed introduction to a method, device, inverter and storage medium for obtaining the input current of a single-phase AC inverter provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for obtaining input current of a single-phase AC inverter, characterized in that: include: Obtaining a DC bus voltage in the single-phase AC inverter; Determining a load current according to the DC bus voltage; Determining a bus capacitor ripple current according to the DC bus voltage; Determine the DC side current according to the load current and the bus capacitor ripple current; An input current in the single-phase AC inverter is determined according to the DC side current.

2. The method for obtaining the input current of a single-phase AC inverter according to claim 1, characterized in that: The step of determining the input current in the single-phase AC inverter according to the DC side current comprises: Determining the effective value of the DC side current; The effective value of the DC side current is used as the effective value of the input current of the single-phase AC inverter.

3. The method for obtaining the input current of a single-phase AC inverter according to claim 1, characterized in that: The step of determining the load current according to the DC bus voltage comprises: Obtaining load active power in the single-phase AC inverter; Calculating a quotient of the load active power and the DC bus voltage; The quotient is used as the load current.

4. The method for obtaining the input current of a single-phase AC inverter according to claim 1, characterized in that: The determining of the bus capacitor ripple current according to the DC bus voltage includes: Extracting a DC bus voltage harmonic component corresponding to the DC bus voltage; The bus capacitor ripple current is determined according to the DC bus voltage harmonic component.

5. The method for obtaining the input current of a single-phase AC inverter according to claim 4, characterized in that: The step of extracting the DC bus voltage harmonic component corresponding to the DC bus voltage includes: A DC component, a 1-time grid frequency component and a 2-time grid frequency component are extracted from the DC bus voltage.

6. The method for obtaining the input current of a single-phase AC inverter according to claim 5, characterized in that: The determining the bus capacitor ripple current according to the DC bus voltage harmonic component includes: Obtaining the capacitance value of a DC bus capacitor in the single-phase AC inverter; The bus capacitor ripple current is determined according to the DC component, the 1 times grid frequency component, the 2 times grid frequency component and the DC bus capacitor value.

7. The method for obtaining the input current of a single-phase AC inverter according to claim 1, characterized in that: The determining of the DC side current according to the load current and the bus capacitor ripple current comprises: Calculating the sum of the load current and the bus capacitor ripple current; The sum is taken as the DC side current.

8. A device for obtaining input current of a single-phase AC inverter, characterized in that: include: An acquisition module, used for acquiring a DC bus voltage in the single-phase AC inverter; A first determination module, configured to determine a load current according to the DC bus voltage; A second determination module, configured to determine a bus capacitor ripple current according to the DC bus voltage; A third determination module, used to determine the DC side current according to the load current and the bus capacitor ripple current; The fourth determination module is used to determine the input current in the single-phase AC inverter according to the DC side current.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed on a computer, the computer is enabled to execute the method for obtaining the input current of a single-phase AC inverter according to any one of claims 1 to 7.

10. A frequency converter, comprising a processor and a memory, wherein the memory stores a computer program, characterized in that: The processor is used to execute the method for obtaining the input current of the single-phase AC inverter according to any one of claims 1 to 7 by calling the computer program.

11. An air conditioning device, characterized in that: Comprising the frequency converter as claimed in claim 10.

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