Method and device for calculating input quantity of alternating current frequency converter, air conditioner and storage medium

Abstract

The application discloses an alternating current frequency converter input quantity calculation method and device, an air conditioner and a storage medium, relates to the field of frequency converters, and aims to solve the technical problem of poor accuracy of input quantity calculation of an alternating current frequency converter. The alternating current frequency converter comprises a rectification module, a direct current side reactance component, a direct current bus capacitor, and an inverter module. The method comprises the following steps: obtaining a target harmonic component corresponding to a target voltage; the target voltage is a voltage between the direct current bus capacitor; obtaining a ripple current flowing through the direct current bus capacitor according to the target harmonic component corresponding to the target voltage; and determining an input current and / or an input voltage of the alternating current frequency converter according to the ripple current flowing through the direct current bus capacitor and a load current flowing through a load. The alternating current frequency converter input quantity calculation method and device, the air conditioner and the storage medium disclosed by the application are used for solving the defects of poor accuracy of input quantity calculation of the existing alternating current frequency converter.

Description

Technical Field

[0001] This application relates to the field of frequency converter technology, specifically to a method, device, air conditioner, and storage medium for calculating the input of an AC frequency converter. Background Technology

[0002] An AC frequency converter can be used as a speed control device. For example, the electrical control box of an air conditioner can adjust the output voltage or frequency of the AC frequency converter, thereby controlling the speed of the outdoor unit fan. When controlling the AC frequency converter to operate, protection measures such as voltage frequency limiting, current frequency limiting, overvoltage, undervoltage, and overcurrent protection can be implemented on the input side of the AC frequency converter based on input quantities such as input voltage or input current.

[0003] Currently, existing methods for obtaining the aforementioned input quantities of AC frequency converters mainly include: estimating the input voltage of the AC frequency converter based on the DC bus voltage and a pre-calibrated compensation coefficient; and then estimating the input current of the AC frequency converter based on the estimated input voltage and the input power factor of the AC frequency converter.

[0004] However, the aforementioned compensation coefficients and input power factor are difficult to obtain and often have large errors. Therefore, existing methods for obtaining the input quantities of AC frequency converters suffer from poor accuracy. Summary of the Invention

[0005] The main objective of this application is to provide a method, device, air conditioner, and storage medium for calculating the input quantity of an AC frequency converter, aiming to solve the technical problem of poor accuracy in the method for calculating the input quantity of an AC frequency converter.

[0006] The AC frequency converter includes: a rectifier module, a DC-side reactor assembly, a DC bus capacitor, and an inverter module. A first terminal of the rectifier module is connected to an AC power supply. A second terminal of the rectifier module is connected to the first terminal of the DC bus capacitor and the first terminal of the inverter module via the DC-side reactor assembly. A third terminal of the rectifier module is connected to the second terminal of the DC bus capacitor and the second terminal of the inverter module. The third terminal of the inverter module is connected to a load. To achieve the above objective, in a first aspect, the AC frequency converter input calculation method provided in this application includes:

[0007] Obtain the target subharmonic component corresponding to the target voltage; the target voltage is the voltage across the DC bus capacitor;

[0008] Based on the target subharmonic component corresponding to the target voltage, obtain the ripple current flowing through the DC bus capacitor;

[0009] The input quantities of the AC frequency converter are determined based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load; the input quantities include the input current of the AC frequency converter and / or the input voltage.

[0010] The beneficial effects of this application are as follows: The ripple current flowing through the DC bus capacitor can be determined by the target subharmonic component corresponding to the voltage across the DC bus capacitor. The input quantity of the AC inverter can then be determined by the ripple current flowing through the DC bus capacitor and the load current flowing through the load. Using this method, the air conditioner can obtain the input quantity of the AC inverter based on the voltage across the DC bus capacitor and the load current flowing through the load. In other words, the method for obtaining the input quantity of the AC inverter provided in this application does not require the input power factor and compensation coefficient of the AC inverter. Therefore, it avoids the influence of errors in the input power factor and the pre-calibrated compensation coefficient on the calculation of the AC inverter input quantity, thereby improving the accuracy of obtaining the AC inverter input quantity.

[0011] Based on the above technical solution, the following improvements can be made to this application.

[0012] Furthermore, the input quantity includes: the input current of the AC inverter; determining the input quantity of the AC inverter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes:

[0013] Obtain the active power of the load;

[0014] The load current is obtained based on the target voltage and the active power of the load;

[0015] The current flowing through the DC-side reactor component is obtained by summing the load current and the ripple current.

[0016] The input current of the AC frequency converter is determined based on the current flowing through the DC-side reactor component.

[0017] Further, the input quantities include: the input voltage of the AC inverter; determining the input quantities of the AC inverter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes:

[0018] The current flowing through the DC-side reactor component is determined based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load.

[0019] The inductance voltage across the DC-side reactor component is obtained based on the current flowing through the DC-side reactor component.

[0020] The rectified voltage output by the rectifier module is obtained based on the inductor voltage and the target voltage.

[0021] The input voltage of the AC frequency converter is obtained based on the rectified voltage.

[0022] Furthermore, the input quantity further includes: input power factor, and the method further includes:

[0023] The input power factor is obtained based on the input voltage and the input current of the AC frequency converter.

[0024] Output the input power factor.

[0025] Further, obtaining the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage includes:

[0026] For any target subharmonic component, the ripple current corresponding to that subharmonic component is obtained based on the subharmonic component corresponding to the target voltage.

[0027] The ripple current of the DC bus capacitor is obtained by summing the ripple currents corresponding to each target harmonic component.

[0028] Furthermore, after determining the input quantity of the AC frequency converter, the method further includes:

[0029] Based on the input of the AC frequency converter, at least one control operation is performed on the AC frequency converter, the control operation including: voltage frequency limiting on the input side of the AC frequency converter, current frequency limiting on the input side of the AC frequency converter, overvoltage protection on the AC frequency converter, undervoltage protection on the AC frequency converter, and overcurrent protection on the AC frequency converter.

[0030] Furthermore, the target number of times is 1 time, 2 times, and 6 times.

[0031] Secondly, this application also provides an AC inverter input quantity calculation device, the device comprising:

[0032] The first acquisition module is used to acquire the target subharmonic component corresponding to the target voltage; the target voltage is the voltage across the DC bus capacitor;

[0033] The second acquisition module is used to acquire the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage.

[0034] The processing module is used to determine the input quantities of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load; the input quantities include the input current of the AC frequency converter and / or the input voltage.

[0035] The beneficial effects of the AC inverter input calculation device provided in this application are the same as those of the AC inverter input calculation method described above, and will not be repeated here.

[0036] Thirdly, this application also provides an air conditioner, comprising: a processor, a memory, an AC inverter, and a load; the processor is communicatively connected to the memory; the AC inverter is coupled to the processor and connected to the load;

[0037] The processor controls the speed of the load via the AC frequency converter;

[0038] The memory stores computer-executed instructions;

[0039] The processor executes computer execution instructions stored in the memory to implement the method as described in any one of the first aspects.

[0040] Fourthly, this application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the AC inverter input calculation method as described in any of the first aspects.

[0041] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the AC inverter input calculation method described in any one of the first aspects. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram illustrating an application scenario of an AC frequency converter.

[0044] Figure 2 This is a schematic diagram of the structure of an AC frequency converter;

[0045] Figure 3 A schematic diagram of an electronic device structure is provided in this application;

[0046] Figure 4 A flowchart illustrating a method for calculating the input quantity of an AC frequency converter provided in this application;

[0047] Figure 5 A flowchart illustrating another method for calculating the input quantity of an AC frequency converter provided in this application;

[0048] Figure 6 This is a schematic diagram of the structure of an AC frequency converter input calculation device provided in this application. Detailed Implementation

[0049] An AC frequency converter can be used as a speed control device. For example, Figure 1 This is a schematic diagram illustrating one application scenario of an AC frequency converter. For example... Figure 1 As shown, the control module of the electronic device can be connected to an AC frequency converter via an AC power supply. This AC frequency converter can also be connected to a motor. The control module of the electronic device can control the output voltage of the AC power supply. By changing the output voltage of the AC power supply, the AC frequency converter can control the speed of the motor to change.

[0050] Taking an air conditioner as an example, the control module can be, for example, the air conditioner's electrical control box. The motor can be, for example, the fan of the air conditioner's outdoor unit. In this example, the air conditioner's electrical control box can control the speed of the air conditioner's outdoor unit fan through the AC power supply and AC inverter.

[0051] It should be understood that the air conditioner described above is merely an example of an application scenario for AC frequency converters in this application, and this application does not limit the application scenario of AC frequency converters. In other words, the electronic device described above is not limited. The electronic device can be any electronic device with processing capabilities that includes an AC frequency converter.

[0052] For example, Figure 2 This is a schematic diagram of the structure of an AC frequency converter. (Example) Figure 2 As shown, the AC frequency converter may include: a rectifier module, a DC-side reactor component Ldc, a DC bus capacitor C, and an inverter module. The first terminal of the rectifier module can be connected to an AC power source. The second terminal of the rectifier module can be connected to the first terminal of the DC bus capacitor and the first terminal of the inverter module via the DC-side reactor component. The third terminal of the rectifier module can be connected to the second terminal of the DC bus capacitor and the second terminal of the inverter module. The third terminal of the inverter module can be connected to a load.

[0053] It should be understood that this application does not limit the type of AC power supply described above. For example, the AC power supply can be a single-phase AC power supply, or a three-phase AC power supply, or a multi-phase AC power supply. Figure 2 Therefore, this AC power supply is a three-phase AC power supply (e.g.) Figure 2 The following is an exemplary description of an AC power supply, using L1, L2, and L3 as an example (which together constitute a three-phase AC power supply).

[0054] Accordingly, the AC frequency converter connected to the three-phase AC power supply can be a three-phase AC frequency converter. Taking the aforementioned AC power supply as a single-phase AC power supply as an example, the AC frequency converter can also be a single-phase AC frequency converter. That is to say, this application does not limit the type of the AC frequency converter. The AC frequency converter can be a single-phase AC frequency converter, or a multi-phase AC frequency converter such as a three-phase AC frequency converter.

[0055] In the AC frequency converter, the aforementioned rectifier module can be any existing rectifier capable of rectification. The aforementioned inverter module can be any existing inverter capable of inversion. Furthermore, this application does not limit the type and size of the DC-side reactor components, or the DC bus capacitor.

[0056] The load connected to the AC frequency converter mentioned above, namely the aforementioned motor (such as...) Figure 2 (The motor shown). An AC frequency converter can control the speed of the load based on the magnitude of the AC power supply output voltage.

[0057] When controlling an AC frequency converter to operate, the AC frequency converter can be protected against voltage and current limiting, overvoltage, undervoltage, and overcurrent protection on the input side based on input quantities such as input voltage or input current.

[0058] Currently, existing methods for obtaining the input parameters of AC frequency converters mainly include: first, using a voltage sampling circuit to acquire the input voltage of the AC frequency converter; then, estimating the input current of the AC frequency converter based on the acquired input voltage, the load power of the AC frequency converter, and the input power factor (PF). Alternatively, the input voltage of the AC frequency converter can also be estimated based on the DC bus voltage (i.e., the voltage difference across the DC bus capacitor mentioned above) and a pre-calibrated compensation coefficient. Then, the input current of the AC frequency converter can be estimated based on the estimated input voltage, the load power of the AC frequency converter, and the input power factor.

[0059] However, the input power factor of the AC frequency converter, as well as the aforementioned compensation coefficient, are difficult to obtain. Furthermore, if the input power factor is preset to a fixed value, it will lead to a large error in the calculation of the input quantities of the AC frequency converter. Therefore, existing methods for obtaining the input quantities of AC frequency converters suffer from poor accuracy.

[0060] Considering that the existing methods for calculating AC inverter input quantities suffer from poor accuracy due to significant errors in the input power factor and pre-calibrated compensation coefficients, this application proposes a method for calculating AC inverter input quantities without requiring the input power factor and the aforementioned compensation coefficients. This method eliminates the need for the input power factor and compensation coefficients, avoiding the impact of errors in these factors on the calculation of AC inverter input quantities, thereby improving the accuracy of obtaining the AC inverter input quantities.

[0061] The subject of this method can be any electronic device that includes an AC frequency converter and has processing capabilities, such as an air conditioner. Figure 3 This is a schematic diagram of an electronic device structure provided in this application. Figure 3 As shown, the electronic device 10 may include: at least one processor 11, a memory 12, an AC inverter 14, and a load 15.

[0062] The memory 12 is used to store programs. Specifically, the program may include program code, which includes computer operation instructions.

[0063] The memory 12 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage.

[0064] An AC frequency converter 14 is coupled to a processor 11 and connected to a load 15. The processor 11 can control the speed of the load 15 through the AC frequency converter 14. The load 15 can be, for example, the aforementioned motor.

[0065] The processor 11 is used to execute computer execution instructions stored in the memory 12 to implement the AC inverter input quantity calculation method described in the following method embodiments. The processor 11 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0066] Optionally, the electronic device 10 may also include a communication interface 13. In specific implementations, if the communication interface 13, memory 12, and processor 11 are implemented independently, they can be interconnected via a bus to complete communication. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc., but this does not imply that there is only one bus or one type of bus.

[0067] Optionally, in a specific implementation, if the communication interface 13, memory 12 and processor 11 are integrated on a single chip, then the communication interface 13, memory 12 and processor 11 can communicate through an internal interface.

[0068] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0069] Figure 4 This is a flowchart illustrating a method for calculating the input quantity of an AC frequency converter, as provided in this application. Figure 4 As shown, the method may include the following steps:

[0070] S101. Obtain the target subharmonic component corresponding to the target voltage. The target voltage is the voltage across the DC bus capacitor mentioned above.

[0071] Optionally, the target harmonic component corresponding to the target voltage can be at least one of the 1st, 2nd, ..., Nth harmonic components (where N is an integer greater than or equal to 1) of the target voltage. For example, the target harmonic can be the 1st, 2nd, and 6th harmonics. Taking a three-phase AC frequency converter as an example, the 6th harmonic component of the target voltage usually appears when the three-phase input voltage to the three-phase AC frequency converter is unbalanced or balanced. The 1st and 2nd harmonic components of the target voltage usually appear when the three-phase input voltage to the three-phase AC frequency converter is unbalanced. Therefore, by obtaining the 1st, 2nd, and 6th harmonic components corresponding to the target voltage, the harmonic components of the target voltage under various conditions of balanced and unbalanced three-phase input voltage can be considered, thereby improving the accuracy of calculating the input quantity of the AC frequency converter based on the target harmonic component.

[0072] Optionally, the electronic device can first sample the voltage across the DC bus capacitor using an electronic sampling circuit to obtain the target voltage (e.g., Figure 2 The V shown dc Then, the electronic device can extract the harmonic components of the target voltage using any existing harmonic component extraction method to obtain the target subharmonic components corresponding to the target voltage.

[0073] S102. Obtain the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage.

[0074] Optionally, the electronic device can first obtain the ripple current corresponding to any harmonic component in the target harmonic component. Then, the electronic device can use the sum of the ripple currents corresponding to all harmonic components in the target harmonic component as the ripple current flowing through the DC bus capacitor. Alternatively, taking the target harmonic component as a certain harmonic component corresponding to the target voltage as an example, the electronic device can directly use the ripple current obtained from the harmonic component corresponding to the target voltage as the ripple current flowing through the DC bus capacitor.

[0075] It should be understood that the above-described method of obtaining the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage is one possible implementation method provided by this application. This application does not limit how the electronic device obtains the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage. Optionally, any existing method based on the voltage-corresponding multiple harmonic components or ripple current can be referred to.

[0076] S103. Determine the input quantity of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load.

[0077] The aforementioned input quantities may include: the input current of the AC frequency converter, or the input voltage, or "input current and input voltage".

[0078] Taking the input quantity mentioned above, including the input current of the AC frequency converter, as an example, the electronic equipment can first use the sum of the ripple current flowing through the DC bus capacitor and the load current as the current flowing through the DC side reactor component. Then, the electronic equipment can determine the input current of the AC frequency converter based on the current of the DC side reactor component.

[0079] Taking the input quantity, including the input voltage of the AC frequency converter, as an example, the electronic equipment can first determine the current flowing through the DC-side reactor component based on the ripple current flowing through the DC bus capacitor and the load current. Then, based on the current of the DC-side reactor component, the electronic equipment can determine the voltage across the DC-side reactor component. Finally, the electronic equipment can determine the input voltage of the AC frequency converter based on the voltage across the DC-side reactor component.

[0080] In this embodiment, the ripple current flowing through the DC bus capacitor can be determined by the target subharmonic component corresponding to the voltage across the DC bus capacitor. The input quantity of the AC inverter can then be determined by the ripple current flowing through the DC bus capacitor and the load current flowing through the load. Using this method, the electronic device can obtain the input quantity of the AC inverter based on the voltage across the DC bus capacitor and the load current flowing through the load. In other words, the method for obtaining the input quantity of the AC inverter provided in this application does not require the input power factor and compensation coefficient of the AC inverter. Therefore, it avoids the influence of errors in the input power factor and the pre-calibrated compensation coefficient on the calculation of the AC inverter input quantity, thereby improving the accuracy of obtaining the AC inverter input quantity.

[0081] Furthermore, as a possible implementation, after determining the input quantity of the AC frequency converter, the electronic device can also perform at least one control operation on the AC frequency converter based on the aforementioned input quantity. For example, the control operation may include: voltage frequency limiting on the input side of the AC frequency converter, current frequency limiting on the input side of the AC frequency converter, overvoltage protection for the AC frequency converter, undervoltage protection for the AC frequency converter, and overcurrent protection for the AC frequency converter.

[0082] Taking the input quantities of an AC frequency converter, including its input voltage, as an example, electronic equipment can, for instance, perform voltage frequency limiting, overvoltage protection, and undervoltage protection on the input side of the AC frequency converter based on its input voltage. Optionally, the specific implementation method of the electronic equipment performing voltage frequency limiting, overvoltage, and undervoltage protection on the input side of the AC frequency converter based on its input voltage can refer to any existing implementation method, which will not be elaborated here.

[0083] Taking the input quantities of an AC frequency converter, including the input current, as an example, electronic equipment can, for instance, limit the input frequency of the AC frequency converter and provide overcurrent protection based on the input current. Optionally, the specific implementation method of the electronic equipment performing current limiting and overcurrent protection on the input side of the AC frequency converter based on the input current can refer to any existing implementation method, which will not be elaborated here.

[0084] Using the above method, electronic devices can perform at least one control operation on the AC frequency converter based on the input of the AC frequency converter with high accuracy, thus improving the accuracy of voltage frequency limiting, current frequency limiting, overvoltage, undervoltage and overcurrent protection of the AC frequency converter.

[0085] In some embodiments, the electronic device may also perform other controls on the AC frequency converter based on the input of the AC frequency converter, which is not limited in this application.

[0086] The following provides a detailed explanation of how electronic devices obtain the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage:

[0087] As one possible implementation, for any target subharmonic component, the electronic device can obtain the ripple current corresponding to that subharmonic component based on the subharmonic component corresponding to the target voltage.

[0088] For example, taking the target harmonics as the 1st, 2nd, and 6th harmonics, the electronic device can obtain the ripple current corresponding to the harmonic component according to the following formula (1):

[0089] I N =N×ω×C×VH N ×sin(Nωt+θ N +π / 2) (1)

[0090] Where N can be 1, 2, or 6. ω is the grid frequency. C is the value of the DC bus capacitance mentioned above. VH N This represents the Nth harmonic component corresponding to the target voltage. Nθ represents the ripple current corresponding to the Nth harmonic component. N This represents the voltage phase at N times the grid frequency component.

[0091] Once the electronic device obtains the ripple current corresponding to each of the above harmonic components, it can obtain the ripple current of the DC bus capacitor based on the sum of the ripple currents corresponding to each target harmonic component.

[0092] For example, taking the target times as 1, 2 and 6 as examples, the electronic device can obtain the ripple current of the DC bus capacitor according to the following formula (2).

[0093] I cap =ωCV H1 sin(ωt+θ1+π / 2)+2ωCV H2 sin(2ωt+θ2+π / 2)+6ωCV H6 sin(6ωt+θ6+π / 2) (2)

[0094] Among them, I cap This represents the ripple current of the DC bus capacitor.

[0095] In this embodiment, the ripple current corresponding to each target harmonic component can be obtained from the target voltage. This allows the electronic device to calculate the ripple current of the DC bus capacitor based on the sum of the ripple currents corresponding to each target harmonic component. This method lays the foundation for the electronic device to determine the input quantity of the AC frequency converter based on the ripple current of the DC bus capacitor.

[0096] Taking the input current of the AC frequency converter as an example, the following is a detailed explanation of how electronic equipment determines the input quantities of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load:

[0097] As one possible implementation, the electronic device can first obtain the load current, and then obtain the input current of the AC frequency converter based on the ripple current and the load current.

[0098] Optionally, electronic devices may sample the load current flowing through the load, for example, using a current transformer.

[0099] Alternatively, the electronic device can determine the load current based on the active power of the load. In this implementation, the electronic device may first obtain the active power of the load, and then obtain the load current based on the target voltage and the active power of the load. For example, the electronic device may obtain the load current based on the following formula (3).

[0100] I load =Pout / V dc (3)

[0101] Among them, P out This represents the active power of the load. (V) dc This indicates the aforementioned target voltage. I load This indicates the load current.

[0102] It should be understood that the method by which electronic devices obtain the active power of the load can refer to any existing implementation, and will not be elaborated here.

[0103] After obtaining the load current flowing through the load, the electronic device can determine the current flowing through the DC-side reactance component based on the sum of the load current and the ripple current. For example, the electronic device can directly use the sum of the load current and the ripple current as the current flowing through the DC-side reactance component. That is, the electronic device can determine the current flowing through the DC-side reactance component according to the following formula (4):

[0104] I Ldc =I cap +I load (4)

[0105] Among them, I cap I represents the ripple current flowing through the DC bus capacitor. load I represents the load current flowing through the load. Ldc This indicates the current flowing through the DC-side reactor component.

[0106] After acquiring the current flowing through the DC-side reactor component, the electronic equipment can determine the input current of the AC frequency converter based on this current. Optionally, the electronic equipment can first calculate the effective current flowing through the DC-side reactor component based on the current flowing through it and the definition of the effective value of current. Then, the electronic equipment can obtain the input current of the AC frequency converter based on the effective current flowing through the DC-side reactor component.

[0107] For example, the input current of the AC frequency converter can be obtained from the following formula (5):

[0108]

[0109] Among them, I ac_rms_avg This represents the input current of the AC frequency converter. Ldc_rms This represents the effective current flowing through the DC-side reactor component. It should be understood that this application does not limit how the electronic device calculates the effective current flowing through the DC-side reactor component based on the current flowing through it.

[0110] Taking the input voltage of the AC frequency converter as an example, the following is a detailed explanation of how electronic equipment determines the input quantities of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load:

[0111] As one possible implementation, the electronic device can first determine the current flowing through the DC-side reactor component based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load. Optionally, the specific implementation method of the electronic device determining the current flowing through the DC-side reactor component based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load can refer to the method described in the foregoing embodiments, and will not be repeated here.

[0112] Then, the electronic device can obtain the inductor voltage across the DC-side reactor component based on the current flowing through it. For example, the electronic device can obtain the inductor voltage across the DC-side reactor component according to the following formula (6):

[0113] V Ldc =ω 2 LCV H1 sin(ωt+θ1+π)+4ω 2 LCV H2 sin(2ωt+θ²+π)+36ω 2 LCV H6 ·sin(6ωt+θ6+π)(6)

[0114] Where L is the inductance value of the DC-side reactor component, and the explanations of the other parameters can be found in the aforementioned embodiments, and will not be repeated here.

[0115] After obtaining the inductor voltage across the DC-side reactance component, the electronic device can obtain the rectified voltage output by the rectifier module based on the inductor voltage and the aforementioned target voltage. In some embodiments, the rectified voltage output by the rectifier module can also be referred to as the rectified voltage after the bridge rectifier. Optionally, the electronic device can obtain the rectified voltage output by the rectifier module based on, for example, the sum of the inductor voltage and the aforementioned target voltage. For example, the electronic device can obtain the rectified voltage output by the rectifier module using the following formula (7):

[0116] V dc_in =V Ldc +V dc (7)

[0117] Among them, V Ldc This represents the inductance voltage across the DC-side reactor component. (V) dc Indicates the target voltage. V dc_in This indicates the rectified voltage output by the rectifier module.

[0118] Then, the electronic device can obtain the input voltage of the AC inverter based on the rectified voltage. Optionally, the electronic device can, for example, perform peak detection on the rectified voltage to obtain the peak value of the rectified voltage, and calculate the input voltage of the AC inverter based on the peak value of the rectified voltage. In some embodiments, the input voltage of the AC inverter can also be referred to as the effective value of the input voltage. For example, taking the AC inverter as a three-phase AC inverter, the electronic device can obtain the input voltage of the AC inverter using the following formula (8):

[0119]

[0120] Among them, V dc_max This indicates the peak value of the rectified voltage. V ac_rms This indicates the input voltage of the AC frequency converter.

[0121] For example, taking a single-phase AC frequency converter as an example, the electronic equipment can, for instance, [details about the electronic equipment]. The result is used as the input voltage of the AC frequency converter.

[0122] In some embodiments, the input parameters of the AC frequency converter may further include, for example, the input power factor. In this implementation, optionally, the electronic device can obtain the input power factor based on the input voltage and input current of the AC frequency converter. Optionally, the method by which the electronic device obtains the input power factor based on the input voltage and input current of the AC frequency converter can refer to any existing implementation, and will not be elaborated here. For example, the electronic device can obtain the input power factor using the following formula (9):

[0123] PF=Pin / (3·Vac·Iac)=Pout·1.03 / (3·Vac_rms·Iac_rms_avg) (9)

[0124] In the formula, Pin is the total input active power, which is taken as 1.03 times the load active power Pout, that is, the total circuit loss is taken as 3%.

[0125] The electronic device can then output the input power factor. For example, if the electronic device includes a display device, it can display the input power factor through its own display device, thus outputting the input power factor. Alternatively, the electronic device can also send the input power factor to other devices, thereby outputting the input power factor.

[0126] The input power factor of an AC frequency converter can be used to reflect the state of work performed by the AC frequency converter on the load. For example, a smaller input power factor indicates higher grid harmonics, meaning more ineffective power is being used by the AC frequency converter to perform work on the load. Conversely, a larger input power factor indicates lower grid harmonics, meaning less ineffective power is being used by the AC frequency converter to perform work on the load. Therefore, by obtaining and outputting the input power factor of the AC frequency converter, users can know whether the ineffective power being used by the AC frequency converter to perform work on the load is excessive.

[0127] Taking the above-mentioned AC frequency converter as a three-phase AC frequency converter as an example, Figure 5 A flowchart illustrating another method for calculating the input quantity of an AC frequency converter provided in this application. Figure 5 As shown, the electronic device can first collect the voltage V across the DC bus capacitor. dc Then, the first, second, and sixth harmonics of this voltage (also known as the bus voltage) are extracted to obtain the first harmonic V. h1 2nd harmonic V h2 6th harmonic V h6 V h1 It can also be called the 1x grid frequency component, V h2 It can also be called twice the power grid frequency component, V h6 It can also be referred to as the 6-times grid frequency component.

[0128] Optionally, the electronic device can obtain the voltage V across the DC bus capacitor by performing Fourier decomposition on the target voltage or other existing bus harmonic extraction methods. dc The first harmonic V h1 2nd harmonic V h2 6th harmonic V h6 For example, V dc =V DC +V h1 +V h2 +V h6 And V h1 =V H1 ·sin(ωt+θ1),V h2 =V H2 ·sin(2ωt+θ2),V h6 =V H6 ·sin(6ωt+θ6). Where, V H1 V H2 V H6 θ1, θ2, and θ6 are the voltage amplitudes of 1, 2, and 6 times the grid frequency component, respectively, and ω is the grid frequency.

[0129] Then, the electronic device can calculate the ripple current generated by each harmonic voltage on the bus capacitor according to the aforementioned formula (2), and obtain the ripple current flowing through the DC bus capacitor based on the sum of the ripple currents.

[0130] The load current I of the electronic device can be obtained according to formula (3). load The load current I load In addition, the ripple current I of the DC bus capacitor cap The current I flowing through the DC-side reactor component is obtained. Ldc Then, the electronic device can first calculate the effective current I flowing through the DC-side reactor component based on the current flowing through the DC-side reactor component and the definition of the effective value of the current. Ldc_rms Then, according to formula (5), the electronic device can obtain the input current I of the AC frequency converter. ac_rms_avg .

[0131] The derivation of formula (5) will be explained in detail below. The inventors discovered through research that in the waveform diagrams of three-phase input current and inductor current, the area enclosed by the three-phase input current is equal to twice the area formed by the current flowing through the DC-side reactor component. Since the area represents the square of the effective value, the relationship between the effective value of the three-phase input current and the effective value of the current flowing through the DC-side reactor component can be expressed by the following formula (10):

[0132] I L1_rms 2 + I L2_rms 2 + I L3_rms 2 = 2I Ldc_rms 2 (10)

[0133] Based on formula (10), formula (5) can be derived. In this implementation, I in formula (5) ac_rms_avg It can also be referred to as the average value of the effective value of the three-phase input current.

[0134] The electronic device can calculate the inductance voltage V across the DC-side reactance component according to formula (6). Ldc The inductor voltage drop V Ldc Add bus capacitor voltage V dc The voltage V after rectifying the bridge rectifier is obtained. dc_in Then, the electronic device can, for example, perform peak detection on the rectified voltage to obtain the peak value V of the rectified voltage. dc_max And based on the peak value of the rectified voltage, and formula (8), the input voltage V of the AC frequency converter is calculated. ac_rms .

[0135] Then, the electronic device can determine the load active power Pout and input current I based on the above parameters. ac_rms_avg And, the input voltage V ac_rms The input power factor PF is obtained through formula (9).

[0136] In this embodiment, the input quantity of the AC frequency converter is calculated based on the harmonic components of the DC bus voltage. No input-side sampling circuit is required, no estimation or compensation correction is needed, and no prior testing or calibration data is required to obtain the compensation coefficient. This improves the accuracy of input quantity acquisition and saves hardware costs and development and testing resources.

[0137] Based on the above method, the following is a verification result of the effect achievable by the AC inverter input quantity calculation method provided in this application, taking the aforementioned electronic equipment as a multi-split air conditioning unit as an example. The verification process tested the calculated values ​​of the AC inverter's input voltage and input current Iac at different frequencies when the compressor (the aforementioned load) was running under different voltages, and compared them with the actual input voltage and the oscilloscope-measured current. The test results are shown in Tables 1-3 below.

[0138] Table 1 shows the calculated input voltage Vac and input current Iac of the AC inverter at different compressor frequencies when the actual input voltage of the AC inverter is 220V, as well as the actual currents Ia, Ib, and Ic of the three-phase AC power supply output, the average value of actual Iac calculated based on these actual currents Ia, Ib, and Ic, and the Iac error between the input current Iac and the average value of actual Iac.

[0139] Table 1

[0140]

[0141] Table 2 shows the calculated input voltage Vac and input current Iac of the AC inverter at different compressor frequencies when the actual input voltage of the AC inverter is 187V, as well as the actual currents Ia, Ib, and Ic of the three-phase AC power supply output, the average value of actual Iac calculated based on these actual currents Ia, Ib, and Ic, and the Iac error between the input current Iac and the average value of actual Iac.

[0142] Table 2

[0143]

[0144]

[0145] Table 3 shows the calculated input voltage Vac and input current Iac of the AC inverter at different compressor frequencies when the actual input voltage of the AC inverter is 254V, as well as the actual currents Ia, Ib, and Ic of the three-phase AC power supply output, the average value of actual Iac calculated based on these actual currents Ia, Ib, and Ic, and the Iac error between the input current Iac and the average value of actual Iac.

[0146] Table 3

[0147]

[0148] The test results show that the calculated input voltage Vac deviates from the actual value by less than 3V under various voltages and loads, and is consistently 2-3V lower, due to the voltage drop generated by the filter circuit at the front end of the rectifier. The average error between the calculated and measured input current Iac is within 1A. This confirms the effectiveness and practical application value of this application.

[0149] Figure 6 This is a schematic diagram of the structure of an AC frequency converter input calculation device provided in this application. Figure 6 As shown, the device includes: a first acquisition module 21, a second acquisition module 22, and a processing module 23. Among them,

[0150] The first acquisition module 21 is used to acquire the target subharmonic component corresponding to the target voltage. The target voltage is the voltage across the DC bus capacitor.

[0151] The second acquisition module 22 is used to acquire the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage.

[0152] Processing module 23 is used to determine the input quantities of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load. The input quantities include the input current and / or input voltage of the AC frequency converter.

[0153] Optionally, the input quantity includes the input current of the AC frequency converter. Optionally, the processing module 23 is specifically used to obtain the active power of the load; obtain the load current based on the target voltage and the active power of the load; obtain the current flowing through the DC-side reactor component based on the sum of the load current and the ripple current; and determine the input current of the AC frequency converter based on the current flowing through the DC-side reactor component.

[0154] Optionally, the input quantity includes: the input voltage of the AC frequency converter. Optionally, the processing module 23 is specifically used to determine the current flowing through the DC-side reactor component based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load; to obtain the inductor voltage across the DC-side reactor component based on the current flowing through the DC-side reactor component; to obtain the rectified voltage output by the rectifier module based on the inductor voltage and the target voltage; and to obtain the input voltage of the AC frequency converter based on the rectified voltage.

[0155] Optionally, the input quantity further includes an input power factor. Optionally, the processing module 23 is further configured to obtain the input power factor based on the input voltage of the AC inverter and the input current. Optionally, the device may also include an output module 24 for outputting the input power factor.

[0156] Optionally, the second acquisition module 22 is specifically used to obtain the ripple current corresponding to any target subharmonic component based on the target voltage corresponding to that subharmonic component; and to obtain the ripple current of the DC bus capacitor based on the sum of the ripple currents corresponding to each target subharmonic component.

[0157] Optionally, the processing module 23 is further configured to, after determining the input quantity of the AC frequency converter, perform at least one control operation on the AC frequency converter based on the input quantity. The control operation includes: voltage frequency limiting on the input side of the AC frequency converter, current frequency limiting on the input side of the AC frequency converter, overvoltage protection on the AC frequency converter, undervoltage protection on the AC frequency converter, and overcurrent protection on the AC frequency converter.

[0158] Optionally, the target number of times is 1, 2, or 6.

[0159] The AC inverter input calculation device provided in this application is used to execute the aforementioned AC inverter input calculation method embodiment. Its implementation principle and technical effect are similar, and will not be described again.

[0160] This application also provides a method such as Figure 3 The electronic device 10 shown has a processor 11 that reads a set of computer instructions stored in the memory 12 to execute the aforementioned AC inverter input calculation method.

[0161] This application also provides a computer-readable storage medium, which may include various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. Specifically, the computer-readable storage medium stores program instructions, which are used in the methods described in the above embodiments.

[0162] This application also provides a program product including executable instructions stored in a readable storage medium. At least one processor of an electronic device can read the executable instructions from the readable storage medium, and the processor executes the executable instructions to cause the electronic device to implement the AC inverter input calculation method provided in the various embodiments described above.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for calculating the input quantity of an AC frequency converter, characterized in that, The AC frequency converter includes: a rectifier module, a DC-side reactor assembly, a DC bus capacitor, and an inverter module. A first terminal of the rectifier module is connected to an AC power supply. A second terminal of the rectifier module is connected to the first terminal of the DC bus capacitor via the DC-side reactor assembly, and also to the first terminal of the inverter module. A third terminal of the rectifier module is connected to the second terminal of the DC bus capacitor, and also to the second terminal of the inverter module. The third terminal of the inverter module is connected to a load. The method includes: Obtain the target subharmonic component corresponding to the target voltage; the target voltage is the voltage across the DC bus capacitor; Based on the target subharmonic component corresponding to the target voltage, obtain the ripple current flowing through the DC bus capacitor; The input quantities of the AC frequency converter are determined based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load; the input quantities include: the input current of the AC frequency converter and / or, the input voltage. When the input quantity includes: the input current of the AC frequency converter, determining the input quantity of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes: Obtain the active power of the load; The load current is obtained based on the target voltage and the active power of the load; The current flowing through the DC-side reactor component is obtained by summing the load current and the ripple current. The input current of the AC inverter is determined based on the current flowing through the DC-side reactor component; when the input quantity includes: the input voltage of the AC inverter, the determination of the input quantity of the AC inverter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes: The current flowing through the DC-side reactor component is determined based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load. The inductance voltage across the DC-side reactor component is obtained based on the current flowing through the DC-side reactor component. The rectified voltage output by the rectifier module is obtained based on the inductor voltage and the target voltage. The input voltage of the AC frequency converter is obtained based on the rectified voltage.

2. The method according to claim 1, characterized in that, The input quantity further includes: input power factor, and the method further includes: The input power factor is obtained based on the input voltage of the AC frequency converter and the input current. Output the input power factor.

3. The method according to claim 1 or 2, characterized in that, The step of obtaining the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage includes: For any target subharmonic component, the ripple current corresponding to that subharmonic component is obtained based on the subharmonic component corresponding to the target voltage; The ripple current of the DC bus capacitor is obtained by summing the ripple currents corresponding to each target subharmonic component.

4. The method according to claim 1 or 2, characterized in that, After determining the input of the AC frequency converter, the method further includes: Based on the input of the AC frequency converter, at least one control operation is performed on the AC frequency converter, the control operation including: voltage frequency limiting on the input side of the AC frequency converter, current frequency limiting on the input side of the AC frequency converter, overvoltage protection on the AC frequency converter, undervoltage protection on the AC frequency converter, and overcurrent protection on the AC frequency converter.

5. The method according to claim 1 or 2, characterized in that, The target number of times is 1, 2, and 6.

6. An AC frequency converter input quantity calculation device, characterized in that, The AC frequency converter includes: a rectifier module, a DC-side reactor assembly, a DC bus capacitor, and an inverter module. A first terminal of the rectifier module is connected to an AC power supply. A second terminal of the rectifier module is connected to the first terminal of the DC bus capacitor and the first terminal of the inverter module via the DC-side reactor assembly. A third terminal of the rectifier module is connected to the second terminal of the DC bus capacitor and the second terminal of the inverter module. The third terminal of the inverter module is connected to a load. The device includes: The first acquisition module is used to acquire the target subharmonic component corresponding to the target voltage; the target voltage is the voltage across the DC bus capacitor; The second acquisition module is used to acquire the ripple current flowing through the DC bus capacitor based on the target subharmonic component corresponding to the target voltage. The processing module is used to determine the input quantities of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load; the input quantities include: the input current of the AC frequency converter and / or, the input voltage; When the input quantity includes: the input current of the AC frequency converter, determining the input quantity of the AC frequency converter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes: Obtain the active power of the load; The load current is obtained based on the target voltage and the active power of the load; The current flowing through the DC-side reactor component is obtained by summing the load current and the ripple current. The input current of the AC frequency converter is determined based on the current flowing through the DC-side reactor component. When the input quantity includes: the input voltage of the AC inverter, determining the input quantity of the AC inverter based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load includes: The current flowing through the DC-side reactor component is determined based on the ripple current flowing through the DC bus capacitor and the load current flowing through the load. The inductance voltage across the DC-side reactor component is obtained based on the current flowing through the DC-side reactor component. The rectified voltage output by the rectifier module is obtained based on the inductor voltage and the target voltage. The input voltage of the AC frequency converter is obtained based on the rectified voltage.

7. An air conditioner, characterized in that, include: The processor, memory, AC frequency converter, and load; the processor is communicatively connected to the memory; The AC frequency converter is coupled to the processor and connected to the load; The processor controls the speed of the load via the AC frequency converter; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the AC inverter input calculation method as described in any one of claims 1 to 5.

9. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the AC inverter input calculation method according to any one of claims 1 to 5.

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