Inverter direct current side current frequency doubling fluctuation suppression device and method

Abstract

The invention discloses a device and a method for suppressing frequency doubling fluctuation of direct-current side current of an inverter. The device comprises a full-bridge converter, an output filter, a direct-current side capacitor and a control device, wherein the suppression device is connected in series between a direct-current power source and a direct-current capacitor of the inverter; the control device is used for generating PWM (Pulse Width Modulation) waves according to the real-time parameters of the direct-current power source and the suppression device, and controlling the switching conversion of the full-bridge converter based on the PWM waves, so that the full-bridge converter outputs frequency doubling voltage opposite to the equivalent frequency doubling voltage of the inverter, and the voltage of the direct-current side capacitor is maintained to be a stable value; and the output filter is used for filtering the output signal of the full-bridge converter. Based on the mode that the device is connected between the direct current capacitor and the direct current power source of the inverter in series, borne voltage is reduced, and suppression of frequency doubling fluctuation of current on the direct current side of the inverter can be achieved with low cost.

Description

Technical Field

[0001] The present application relates to the technical field of inverter regulation, and in particular to a device and method for suppressing double frequency fluctuation of current on the direct current side of an inverter. Background Art

[0002] At present, inverters are an indispensable and important component in various systems and energy storage devices. The double frequency fluctuation of the DC side current of the inverter is one of the key factors affecting system performance and the life of energy storage equipment. The double frequency fluctuation of the current will cause the DC side energy storage components, such as capacitors and batteries, to bear greater current and voltage stress, thereby accelerating their aging and performance degradation. Therefore, reducing the double frequency fluctuation of the DC side current can not only reduce the damage to the energy storage components and extend their service life, but also improve the reliability and stability of the entire system.

[0003] Among them, in a typical single-stage inverter system, the energy on the DC side is usually filtered and stored by capacitors. However, due to the presence of double frequency current, the voltage fluctuation on the DC side will also increase significantly, which not only puts higher requirements on the capacity and life of the energy storage capacitor, but also causes the DC power to introduce more harmonic interference during the inverter process, especially for low-order harmonics. Therefore, suppressing the double frequency fluctuation of the DC side current of the inverter becomes an important part of the inverter operation process.

[0004] In the related art, when suppressing the double frequency fluctuation of the DC side current of the inverter, the capacity of the filter capacitor or inductor is usually increased to weaken the double frequency current component on the DC side. However, this method leads to a significant increase in the volume, weight and cost of the system, especially in high-power applications, which significantly increases the cost required for suppression. In some suppression schemes that add bus voltage regulators, a parallel access method is adopted at both ends of the DC bus. This scheme has high requirements on the voltage resistance of the device, and the switching loss during operation is large, and the cost required for suppression is also high.

[0005] Therefore, how to accurately suppress the double frequency fluctuation of the DC side current of the inverter at a lower cost has become a problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of this application is to solve one of the above-mentioned technical problems at least to a certain extent.

[0007] To this end, the first purpose of the present application is to propose a device for suppressing the double frequency fluctuation of the DC side current of the inverter. The device is connected in series between the DC capacitor of the inverter and the DC power source, does not need to fully withstand the higher voltage of the DC side power source, has a low hardware cost, and can suppress the double frequency fluctuation of the DC side current of the inverter at a low cost.

[0008] The second objective of the present application is to provide a method for suppressing the double frequency fluctuation of the DC side current of the inverter.

[0009] The third object of this application is to provide an electronic device

[0010] A fourth objective of the present application is to provide a computer-readable storage medium.

[0011] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a device for suppressing the double frequency fluctuation of the DC side current of the inverter, the device comprising: a full-bridge converter, an output filter, a DC side capacitor and a control device; wherein,

[0012] The suppression device is connected in series between the DC power source and the DC capacitor of the inverter, the output filter is connected to the DC power source of the inverter, and the full-bridge converter is connected to the DC capacitor of the inverter;

[0013] The control device is used to generate a PWM modulation wave according to the real-time parameters of the DC power source and the suppression device, and control the switching conversion of the full-bridge converter based on the PWM modulation wave, so that the full-bridge converter outputs a double-frequency voltage opposite to the equivalent double-frequency voltage of the inverter, and maintains the voltage of the DC side capacitor at a stable value;

[0014] The output filter is also connected to the full-bridge converter, and is used to filter the output signal of the full-bridge converter.

[0015] In addition, the device for suppressing double frequency fluctuation of the DC side current of the inverter according to the embodiment of the present application also has the following additional technical features:

[0016] Optionally, in some embodiments, the control device includes: a double-frequency fluctuation suppression control unit, which is used to generate a first PWM modulation wave for suppressing double-frequency fluctuations, and control the switching transformation of the full-bridge converter based on the first PWM modulation wave so that the full-bridge converter outputs the opposite double-frequency voltage; a DC voltage stabilization control unit, which is used to generate a second PWM modulation wave for stabilizing the DC side voltage of the suppression device, and control the switching transformation of the full-bridge converter based on the second PWM modulation wave so that the full-bridge converter absorbs energy from the circuit in which it is located.

[0017] Optionally, in some embodiments, the output filter is a single inductor filter; and the DC power source includes a DC energy storage battery.

[0018] Optionally, in some embodiments, the full-bridge converter is composed of a plurality of low-voltage switching tubes.

[0019] To achieve the above object, a second embodiment of the present invention provides a method for suppressing double frequency fluctuation of the DC side current of an inverter, which is applied to the device for suppressing double frequency fluctuation of the DC side current of the inverter of the first aspect. The method comprises:

[0020] Connecting the DC bus of the inverter to a DC power source, and connecting a device for suppressing double frequency fluctuation of the DC side current of the inverter in series between the DC power source and the DC capacitor of the inverter;

[0021] In each sampling period, the output current of the DC power source and the voltage of the DC side capacitor of the suppression device are collected in real time;

[0022] Calculating a first difference between zero and the output current, inputting the first difference into a proportional resonant controller for operation to obtain a double frequency fluctuation suppression component, and calculating a second difference between a preset DC voltage reference value and the voltage of the DC link capacitor, inputting the second difference into a proportional integral controller for operation to obtain a DC voltage stabilization control component;

[0023] A modulation parameter value is generated according to the double frequency fluctuation suppression component and the DC voltage stabilization control component, PWM modulation is performed based on the modulation parameter value, and the switching conversion of the full-bridge converter in the suppression device is controlled based on the generated PWM modulation wave.

[0024] In addition, the method for suppressing the double frequency fluctuation of the DC side current of the inverter in the embodiment of the present application also has the following additional technical features:

[0025] Optionally, in some embodiments, inputting the first difference into a proportional resonant controller for operation includes:

[0026] The first difference is used as the double frequency fluctuation component in the DC current output by the DC power source, and the double frequency fluctuation component is multiplied by the transfer function of the proportional resonant controller, wherein the product of the double frequency fluctuation component and the transfer function is calculated by the following formula:

[0027]

[0028] Among them, I bat is the output current of the DC power source, k p is the proportionality coefficient, k i is the integral coefficient, S is a complex variable, h is a constant, ω 0 is the resonant frequency, ω c is the resonant bandwidth.

[0029] Optionally, in some embodiments, inputting the second difference into a proportional-integral controller for operation includes:

[0030] The second difference is multiplied by the transfer function of the proportional-integral controller, wherein the product of the second difference and the transfer function is calculated by the following formula:

[0031]

[0032] Among them, V * C2 is the DC voltage reference value, V C2 is the voltage of the DC capacitor, k p is the proportionality coefficient, k i is the integration coefficient and S is a complex variable.

[0033] Optionally, in some embodiments, before the device for suppressing the double frequency fluctuation of the DC side current of the inverter is connected in series, it also includes: setting the filtering parameters of the single inductor filter in the suppression device; after controlling the switching transformation of the full-bridge converter in the suppression device based on the generated PWM modulation wave, it also includes: filtering the output signal of the full-bridge converter through the single inductor filter to obtain a double frequency voltage for suppressing the double frequency fluctuation.

[0034] To achieve the above-mentioned purpose, the third aspect of the present invention proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement a method for suppressing the double frequency fluctuation of the DC side current of the inverter as described in any one of the second aspect embodiments above.

[0035] To achieve the above-mentioned purpose, the fourth aspect of the present invention proposes a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it implements the method for suppressing the double frequency fluctuation of the DC side current of the inverter as described in any of the above-mentioned second aspect embodiments.

[0036] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0037] The present application connects the suppression device of the double frequency fluctuation of the DC side current of the inverter in series between the DC capacitor of the inverter and the DC power source. When performing double frequency current suppression, the switch conversion of the full-bridge converter of the suppression device is controlled by PWM modulation wave. On the one hand, the DC side voltage of the suppression device can be kept stable. On the other hand, the suppression device can output a double frequency voltage opposite to the system equivalent double frequency voltage source according to sampling feedback control to accurately suppress the double frequency fluctuation of the current. Therefore, the present application does not affect the power exchange between the DC power supply and the converter during the normal inverter output during the suppression process. In addition, due to the serial connection mode of the suppression device of the present application, it is not necessary to fully withstand the higher voltage of the DC side power source, but only to withstand part of the lower voltage. Therefore, the switch device of the suppression device of the present application can adopt a device with a smaller withstand voltage value, and the switching loss of the device is small, which is conducive to reducing the system volume and reducing the hardware cost of the suppression device. In addition, the control logic of the present application is relatively simple, and the double frequency fluctuation suppression can be achieved without detecting the DC capacitor voltage of the inverter, further reducing the resources consumed in the suppression process. Therefore, the present application can achieve accurate suppression of the double frequency fluctuation of the inverter DC side current at a relatively low cost, thereby improving the convenience, applicability and reliability of suppressing the double frequency fluctuation of the inverter.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0040] Figure 1 A schematic diagram of an application scenario of a device for suppressing double frequency fluctuation of current on the DC side of an inverter proposed in an embodiment of the present application;

[0041] Figure 2 A flow chart of a method for suppressing double frequency fluctuation of the DC side current of an inverter proposed in an embodiment of the present application;

[0042] Figure 3 A schematic diagram of the principle of a low-cost DC current double frequency fluctuation suppression control strategy proposed in an embodiment of the present application;

[0043] Figure 4 A schematic diagram of a frequency doubling equivalent circuit under closed-loop control proposed in an embodiment of the present application;

[0044] Figure 5 A schematic diagram of a DC side equivalent circuit under closed-loop control proposed in an embodiment of the present application;

[0045] Figure 6A schematic diagram of a DC voltage simulation waveform proposed in an embodiment of the present application;

[0046] Figure 7 A schematic diagram of a DC current simulation waveform proposed in an embodiment of the present application;

[0047] Figure 8 This is a spectrum diagram of a DC current when no suppression device is provided, as proposed in an embodiment of the present application;

[0048] Fig. 9 This is a diagram of a DC current spectrum after a suppression device is provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0049] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0050] The following describes a device and method for suppressing double frequency fluctuations of the DC side current of an inverter according to an embodiment of the present application with reference to the accompanying drawings.

[0051] Figure 1 This is a schematic diagram of an application scenario of a device for suppressing double frequency fluctuation of the DC side current of an inverter proposed in an embodiment of the present application, such as Figure 1 As shown, the suppression device includes: a full-bridge converter 10, an output filter L, a DC side capacitor C2 and a control device (not shown in the figure).

[0052] The suppression device is connected in series between the DC power source and the DC capacitor of the inverter. When specifically connected, the output filter L is connected to the DC power source of the inverter, the full-bridge converter 10 is connected to the DC capacitor C1 of the inverter, and the output filter L is also connected to the full-bridge converter 10.

[0053] The suppression device of the present application can be applied to ordinary single-stage inverters, and can also be applied to Figure 1 In a single inverter unit of the single-phase cascade converter shown in FIG. Figure 1 The suppression device set in a single inverter unit is magnified and displayed. In the inverter used in the present application, the DC side of the inverter is connected to a DC power source, which is a power source or energy source in the form of DC, and can include various energy storage devices and other types of DC power units, such as Figure 1 The DC energy storage battery shown.

[0054] When setting up the suppression device, as a possible implementation method, Figure 1As shown, the DC energy storage battery is first connected in series with the double frequency fluctuation suppression device, and then the suppression device is connected in series with the DC capacitor C1 of the inverter. In one embodiment of the present application, the full-bridge converter is composed of multiple low-voltage switch tubes, such as Figure 1 In the example, four low-voltage switching tubes form a full-bridge conversion topology, and the output filter is a single-inductor L filter.

[0055] The control device is used to generate a PWM modulation wave according to the real-time parameters of the DC power source and the suppression device, and control the switching conversion of the full-bridge converter based on the PWM modulation wave, so that the full-bridge converter outputs a double-frequency voltage opposite to the equivalent double-frequency voltage of the inverter, and maintains the voltage of the DC side capacitor at a stable value.

[0056] Specifically, when the suppression device of the present application performs double frequency current suppression, a PWM modulation wave is generated, and the PWM modulation wave is used to control the switching transformation of the full-bridge converter, so that the full-bridge converter of the suppression device outputs a double frequency voltage opposite to the double frequency voltage source equivalent to the inverter, while keeping the DC side voltage of the suppression device at a stable value. In this way, the DC side voltage of the suppression device can be controlled to be stable, and a voltage opposite to the equivalent double frequency voltage source of the inverter can be output according to sampling feedback control to suppress the double frequency fluctuation of the current. The opposite voltage can be a double frequency voltage with the same frequency and phase as the equivalent double frequency voltage of the inverter.

[0057] In one embodiment of the present application, the control device includes: a double frequency fluctuation suppression control unit, which is used to generate a first PWM modulation wave for suppressing double frequency fluctuations, and control the switch conversion of the full-bridge converter based on the first PWM modulation wave, so that the full-bridge converter outputs an opposite double frequency voltage. A DC voltage stabilization control unit, which is used to generate a second PWM modulation wave for stabilizing the DC side voltage of the suppression device, and control the switch conversion of the full-bridge converter based on the second PWM modulation wave, so that the full-bridge converter absorbs energy from the circuit in which it is located.

[0058] Specifically, the double frequency fluctuation suppression control unit is used to generate the PWM modulation wave required for suppressing the output voltage of the double frequency fluctuation, and use the PWM modulation wave to control the switch conversion of the full-bridge converter of the suppression device, so that the DC side current double frequency fluctuation suppression device outputs a double frequency AC voltage opposite to the equivalent double frequency voltage source of the inverter. The DC voltage stabilization control unit of the suppression device is used to generate a PWM modulation wave for stabilizing the DC side voltage of the suppression device, and use the PWM modulation wave to control the switch conversion of the full-bridge converter of the suppression device, so that the full-bridge converter of the suppression device can absorb energy from the connected circuit to maintain the stability of the DC voltage.

[0059] The output filter is used to filter the output signal of the full-bridge converter. Figure 1As shown, the full-bridge converter is connected to the DC energy storage battery of the inverter through an output filter. The output filter is at the output end of the suppression device of the present application, and filters the output of the full-bridge converter in the suppression device, so that a double frequency voltage opposite to the equivalent double frequency voltage of the inverter can be obtained for suppressing double frequency fluctuations. In this embodiment, a single inductor is used as a filter, which has a simple structure and can further reduce costs.

[0060] Therefore, the suppression device of the present application is connected in series between the DC capacitor of the inverter and the DC power source to suppress the double frequency fluctuation of the DC current from the DC power source to the DC capacitor. Since the full-bridge power switch device of the present device is connected in series between the DC power source and the DC capacitor, the power switch device can withstand a lower voltage.

[0061] In summary, the device for suppressing the double frequency fluctuation of the DC side current of the inverter of the embodiment of the present application is connected in series between the DC capacitor of the inverter and the DC power source. When performing double frequency current suppression, the PWM modulation wave is used to control the switch conversion of the full-bridge converter. On the one hand, the DC side voltage of the suppression device can be kept stable. On the other hand, the suppression device can output a double frequency voltage opposite to the system equivalent double frequency voltage source according to the sampling feedback control to accurately suppress the double frequency fluctuation of the current. Therefore, the device does not affect the power exchange between the DC power supply and the converter during the normal inverter output during the fluctuation suppression process. In addition, due to the series connection mode of the device, it is not necessary to fully withstand the higher voltage of the DC side power source, but only to withstand part of the lower voltage. Therefore, the switch device of the suppression device can use a device with a smaller withstand voltage value, and the switching loss of the device is small, which is conducive to reducing the system volume and reducing the hardware cost of the suppression device.

[0062] In order to more clearly illustrate the specific implementation process of suppressing the double frequency fluctuation of the inverter DC side current by the suppression device, a method for suppressing the double frequency fluctuation of the inverter DC side current proposed in the embodiment of the present application is described in detail below. The method is applied to the suppression device for suppressing the double frequency fluctuation of the inverter DC side current in the above embodiment, that is, the suppression device in the above embodiment is controlled, and the double frequency fluctuation suppression method of this embodiment is implemented by using the above suppression device. The suppression device involved in the method includes various components as described in the above embodiment, which will not be repeated here.

[0063] Figure 2 A flowchart of a method for suppressing double frequency fluctuation of the DC side current of an inverter proposed in an embodiment of the present application, the method comprising the following steps:

[0064] Step S101: Connect the DC bus of the inverter to a DC power source, and connect a device for suppressing double frequency fluctuation of the DC side current of the inverter in series between the DC power source and the DC capacitor of the inverter.

[0065] Specifically, the DC bus of the inverter to be used is first connected to a power source such as an energy storage battery on the DC side of the inverter to provide DC voltage and power support to the DC power source. Then, a device for suppressing the double frequency fluctuation of the DC side current of the inverter is connected, and the DC power source of the inverter is connected in series with the suppression device, and then connected to the DC capacitor of the inverter unit.

[0066] For example, according to Figure 3 After setting the suppression device in the manner shown, the DC power source output current is I bat , the voltage of the DC side capacitor of the double frequency fluctuation suppression device is V C2 The topology of the suppression device is a full-bridge converter circuit composed of four switch tubes S1 to S4, and the output filter of the double frequency suppression device adopts a single L filter.

[0067] In one embodiment of the present application, before the device for suppressing the double frequency fluctuation of the current on the DC side of the inverter is connected in series, it also includes: setting the filtering parameters of the single inductor filter in the suppression device. Specifically, in this embodiment, the filtering parameters of the single inductor filter can be reasonably set in combination with actual factors such as the parameters of the inverter to be suppressed, the parameters of the full-bridge converter, and the requirements for fluctuation suppression, so that the output of the full-bridge converter can be filtered later by the filter after the parameter setting.

[0068] Step S102: In each sampling period, the output current of the DC power source and the voltage of the DC side capacitor of the suppression device are collected in real time.

[0069] Specifically, the present application performs closed-loop suppression control based on real-time sampling feedback data. In each sampling period, the output current I of the DC power source in the current period is collected. bat and the voltage V of the DC capacitor of the suppression device C2 , so that the double frequency fluctuation within this period can be suppressed according to the sampling data later.

[0070] As an example, the equivalent circuit of the inverter system when the present application performs closed-loop control is as follows: Figure 4 and Figure 5 As shown, Figure 4 The double frequency equivalent circuit shown includes a double frequency DC power source voltage V bat_2 , the output current I of the double frequency DC power source bat_2 Multiply the loop conductance G and the voltage V of the DC capacitor of the double frequency inverter C1_2 .

[0071] Step S103: Calculate the first difference between zero and the output current, input the first difference into the proportional resonant controller for operation to obtain the double frequency fluctuation suppression component, and calculate the second difference between the preset DC voltage reference value and the voltage of the DC side capacitor, input the second difference into the proportional integral controller for operation to obtain the DC voltage stabilization control component.

[0072] Specifically, when controlling the suppression of double frequency fluctuations on the DC side, the present application uses the preset ideal value as a control reference and compares it with the DC power source output current I obtained by actual sampling. bat The difference is then input into the proportional resonant controller for calculation and control to obtain the double frequency fluctuation suppression component.

[0073] Furthermore, when performing DC voltage stabilization control of the suppression device, a preset DC voltage reference value is used as a control reference, and the difference is made between the DC side voltage of the suppressor obtained by actual sampling, and the difference is input into a proportional-integral controller for calculation control to obtain a DC voltage stabilization control component of the suppressor.

[0074] In one embodiment of the present application, Figure 3 As shown, the first difference is input into the proportional resonant controller for operation, including: taking the first difference as the double frequency fluctuation component in the DC current output by the DC power source, multiplying the double frequency fluctuation component by the transfer function of the proportional resonant controller, wherein the product of the double frequency fluctuation component and the transfer function is calculated by the following formula:

[0075]

[0076] Among them, I bat is the output current of the DC power source, k p is the proportionality coefficient, k i is the integral coefficient, S is a complex variable, h is a constant, ω 0 is the resonant frequency, ω c is the resonant bandwidth.

[0077] Specifically, in this embodiment, 0 is taken as the ideal value, and the first difference is: 0-I bat Thus, the DC current double frequency fluctuation component in the DC power source output of the inverter at the current moment is obtained, and the fluctuation component is passed through the proportional resonant controller and calculated according to the above formula to obtain the double frequency fluctuation suppression component

[0078] Therefore, in this embodiment, the H-bridge converter of the suppression device outputs a double frequency voltage connected in series between the inverter DC capacitor and the DC power source. The double frequency voltage can actively suppress the double frequency current, thereby weakening the double frequency fluctuation of the voltage at both ends of the DC power source and the power fluctuation.

[0079] In one embodiment of the present application, continue to refer to Figure 3 In an example, the second difference is input into the proportional-integral controller for operation, including: multiplying the second difference by a transfer function of the proportional-integral controller, wherein the product of the second difference and the transfer function is calculated by the following formula:

[0080]

[0081] Among them, V * C2 is the DC voltage reference value, V C2 is the voltage of the DC capacitor, k p is the proportionality coefficient, k i is the integration coefficient and S is a complex variable.

[0082] Specifically, in this embodiment, the second difference is a given DC voltage reference V * C2 Subtract the voltage V of the DC link capacitor C2 The second difference is calculated by the proportional-integral controller according to the above formula to obtain the DC voltage stability control component

[0083]

[0084] Step S104: Generate a modulation parameter value according to the double frequency fluctuation suppression component and the DC voltage stabilization control component, perform PWM modulation based on the modulation parameter value, and control the switching conversion of the full-bridge converter in the suppression device based on the generated PWM modulation wave.

[0085] Specifically, the double frequency fluctuation suppression component obtained in step S103 is and DC voltage stabilization control component Add together to get the total modulation reference value of the suppressor The modulation reference value is then sent to the PWM signal generator for PWM modulation to generate a PWM modulation wave of the suppression device, and the H-bridge switching device of the suppression device is controlled based on the PWM modulation wave, thereby suppressing the double frequency current fluctuation.

[0086] In one embodiment of the present application, after the switch transformation of the full-bridge converter in the suppression device is controlled based on the generated PWM modulation wave, it also includes: filtering the output signal of the full-bridge converter through a single inductor filter to obtain a double-frequency voltage for suppressing double-frequency fluctuations.

[0087] Specifically, the output of the H-bridge converter of the suppression device is filtered by the single inductor filter after the filter parameters are set as described in step S101 to generate a double frequency voltage opposite to the equivalent double frequency voltage of the inverter for suppressing double frequency fluctuations as described in the above embodiment.

[0088] Based on the above embodiments, in order to more clearly describe the suppression effect of the device and method for suppressing the double frequency fluctuation of the inverter DC side current of the present application, in actual application, the suppression device of the present application is set on a certain inverter, and the suppression method of the present application is used for control. Then, the waveforms of the DC side of the inverter in the two states are compared without loading the suppression device of the present application and after adopting the suppression scheme of the present application. The final experimental results are as follows: Figures 6 to 9 As shown. Figure 6 and Figure 7 The two waveforms in the figure show that the waveform after the suppression device of the present application is used (the waveform shown by the group line) is significantly lower than the waveform without the suppression device of the present application (the waveform shown by the thin line). Figure 8 and Fig. 9 It can be seen that the suppression device of the present application can significantly reduce the spectrum of the DC current.

[0089] In summary, the method for suppressing the double frequency fluctuation of the DC side current of the inverter of the embodiment of the present application uses the PWM modulation wave to control the switching conversion of the full-bridge converter of the suppression device. On the one hand, the DC side voltage of the suppression device can be kept stable. On the other hand, the suppression device can output a double frequency voltage opposite to the system equivalent double frequency voltage source according to the sampling feedback control to accurately suppress the double frequency fluctuation of the current. Therefore, the method does not affect the power exchange between the DC power supply and the converter during the normal inverter output during the fluctuation suppression process. In addition, the control logic of the method is relatively simple, and the double frequency fluctuation suppression can be achieved without detecting the DC capacitor voltage of the inverter, which further reduces the resources consumed in the suppression process. Therefore, the method can achieve accurate suppression of the double frequency fluctuation of the DC side current of the inverter at a lower cost, and improves the convenience, applicability and reliability of the inverter double frequency fluctuation suppression.

[0090] In order to implement the above-mentioned embodiments, the present application also proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement a method for suppressing the double frequency fluctuation of the DC side current of the inverter as described in any one of the above-mentioned second aspect embodiments.

[0091] In order to implement the above-mentioned embodiments, the present application also proposes a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the method for suppressing the double frequency fluctuation of the DC side current of the inverter proposed in the aforementioned second aspect embodiment of the present application.

[0092] It should be noted that it should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0093] In addition, in the description of the present application, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0094] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0095] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0096] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0097] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A device for suppressing double frequency fluctuation of the DC side current of an inverter, characterized in that: include: Full-bridge converter, output filter, DC side capacitor and control device; wherein, The suppression device is connected in series between the DC power source and the DC capacitor of the inverter, the output filter is connected to the DC power source of the inverter, and the full-bridge converter is connected to the DC capacitor of the inverter; The control device is used to generate a PWM modulation wave according to the real-time parameters of the DC power source and the suppression device, and control the switching conversion of the full-bridge converter based on the PWM modulation wave, so that the full-bridge converter outputs a double-frequency voltage opposite to the equivalent double-frequency voltage of the inverter, and maintains the voltage of the DC side capacitor at a stable value; The output filter is also connected to the full-bridge converter, and is used to filter the output signal of the full-bridge converter.

2. The device for suppressing double frequency fluctuation of the DC side current of the inverter according to claim 1, characterized in that: The control device comprises: A double frequency fluctuation suppression control unit, used for generating a first PWM modulation wave for suppressing double frequency fluctuation, and controlling the switch conversion of the full-bridge converter based on the first PWM modulation wave, so that the full-bridge converter outputs the opposite double frequency voltage; A DC voltage stabilization control unit is used to generate a second PWM modulation wave for stabilizing the DC side voltage of the suppression device, and control the switching conversion of the full-bridge converter based on the second PWM modulation wave so that the full-bridge converter absorbs energy from the circuit in which it is located.

3. The device for suppressing double frequency fluctuation of the DC side current of the inverter according to claim 1, characterized in that: The output filter is a single inductor filter; The DC power source includes a DC energy storage battery.

4. The device for suppressing double frequency fluctuation of the DC side current of the inverter according to claim 3, characterized in that: The full-bridge converter is composed of a plurality of low-voltage switching tubes.

5. A method for suppressing double frequency fluctuation of the DC side current of an inverter, characterized in that: The device for suppressing double frequency fluctuation of the DC side current of the inverter according to any one of claims 1 to 4, wherein the suppression method comprises the following steps: Connecting the DC bus of the inverter to a DC power source, and connecting a device for suppressing double frequency fluctuation of the DC side current of the inverter in series between the DC power source and the DC capacitor of the inverter; In each sampling period, the output current of the DC power source and the voltage of the DC side capacitor of the suppression device are collected in real time; Calculating a first difference between zero and the output current, inputting the first difference into a proportional resonant controller for operation to obtain a double frequency fluctuation suppression component, and calculating a second difference between a preset DC voltage reference value and the voltage of the DC link capacitor, inputting the second difference into a proportional integral controller for operation to obtain a DC voltage stabilization control component; A modulation parameter value is generated according to the double frequency fluctuation suppression component and the DC voltage stabilization control component, PWM modulation is performed based on the modulation parameter value, and the switching conversion of the full-bridge converter in the suppression device is controlled based on the generated PWM modulation wave.

6. The suppression method according to claim 5, characterized in that: The step of inputting the first difference into a proportional resonant controller for operation comprises: The first difference is used as the double frequency fluctuation component in the DC current output by the DC power source, and the double frequency fluctuation component is multiplied by the transfer function of the proportional resonant controller, wherein the product of the double frequency fluctuation component and the transfer function is calculated by the following formula: Among them, I bat is the output current of the DC power source, k p is the proportionality coefficient, k i is the integral coefficient, S is a complex variable, h is a constant, ω0 is the resonant frequency, ω c is the resonant bandwidth.

7. The suppression method according to claim 5, characterized in that: The step of inputting the second difference into a proportional-integral controller for operation comprises: The second difference is multiplied by the transfer function of the proportional-integral controller, wherein the product of the second difference and the transfer function is calculated by the following formula: Among them, V * C2 is the DC voltage reference value, V C2 is the voltage of the DC capacitor, k p is the proportionality coefficient, k i is the integration coefficient and S is a complex variable.

8. The inhibition method according to any one of claims 5 to 7, characterized in that: Before the device for suppressing the double frequency fluctuation of the DC side current of the inverter is connected in series, it also includes: Setting filtering parameters of a single inductor filter in the suppression device; After controlling the switch conversion of the full-bridge converter in the suppression device based on the generated PWM modulation wave, the method further includes: The output signal of the full-bridge converter is filtered by the single inductor filter to obtain a double frequency voltage for suppressing double frequency fluctuations.

9. An electronic device, comprising: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instruction to implement the method for suppressing double frequency fluctuation of the DC side current of the inverter as described in any one of claims 5-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for suppressing the double frequency fluctuation of the DC side current of the inverter as described in any one of claims 5-8 is implemented.

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