Control method, device and equipment of dual-active bridge inverter, medium and product

Abstract

The invention relates to a control method, device and equipment of a dual-active bridge type inverter, a medium and a product. The method comprises the following steps: acquiring an input voltage of the dual-active bridge type inverter; determining the current adjustment amount of the dual-active bridge inverter according to the fluctuation of the input voltage; and acquiring a current reference value, determining a control parameter according to the updated current reference value and the current adjustment amount, controlling the dual-active bridge type inverter to work by adopting the control parameter, and adjusting the grid-connected current output from the grid-connected port by the dual-active bridge type inverter. By adopting the method, the voltage can be stabilized, and the distortion of the grid-connected current is reduced.

Description

Technical Field

[0001] The present application relates to the field of power grid technology, and in particular to a control method, device, equipment, medium and product of a dual active bridge inverter. Background Art

[0002] With the development of new energy technology, wind power generation system has also made great progress. In the wind power generation system, the inverter feeds the voltage output by the generator into the power grid.

[0003] At present, dual-active bridge microinverters can be used as loads for low-voltage bus capacitors in wind power systems. In this case, the inverter is required to stabilize the voltage of the low-voltage bus capacitor. The current output by the dual-active bridge microinverter is fed into the grid and needs to be synchronized with the grid to meet the phase requirements. The output current needs to be in the same frequency and phase as the grid current. However, the energy stored on the low-voltage bus capacitor is limited. Therefore, changes in the instantaneous power output of the inverter will directly affect the voltage on the low-voltage bus capacitor, so the inverter will introduce large ripples on the low-voltage bus capacitor when it is working normally. In existing wind power generation systems, the control strategy adopts a conventional dual-loop control strategy. Under this control strategy, in order to keep the DC input voltage stable at the reference point, the output current needs to be adjusted frequently within a single grid cycle, resulting in large distortion of the current connected to the grid. Summary of the invention

[0004] Based on this, it is necessary to provide a control method, device, equipment, medium and product for a dual active bridge inverter that can stabilize voltage and reduce grid current distortion in response to the above technical problems.

[0005] In a first aspect, the present application provides a control method for a dual active bridge inverter, the method comprising:

[0006] Obtaining the input voltage of the dual active bridge inverter;

[0007] Determine the current adjustment amount of the dual active bridge inverter according to the fluctuation of the input voltage;

[0008] A current reference value is obtained, a control parameter is determined according to the updated current reference value and the current adjustment amount, and the control parameter is used to control the operation of the dual active bridge inverter to adjust the grid-connected current outputted from the grid-connected port of the dual active bridge inverter.

[0009] In one embodiment, the method further comprises:

[0010] After every half power grid cycle, the effective value of the current is calculated according to the pre-established first corresponding relationship between the instantaneous value and the effective value and the instantaneous value of the current;

[0011] Calculate the current reference value according to the second correspondence between the pre-established effective value and the reference value and the current effective value, and determine the calculated current reference value as the current reference value for the current half grid cycle.

[0012] In one embodiment, determining the control parameter according to the updated current reference value and the current adjustment amount includes:

[0013] Calculate the current peak value of the current control cycle according to the updated current peak value and the current adjustment amount, and calculate the current instantaneous value according to the current peak value;

[0014] Determine the control parameter according to the current instantaneous value; wherein, the control parameter includes at least one of an internal phase shift angle and an external phase shift angle.

[0015] In one embodiment, determining the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage includes:

[0016] When the fluctuation of the input voltage meets the adjustment trigger condition, calculate the voltage excess according to the input voltage and the preset voltage range;

[0017] Perform conversion processing on the voltage excess according to the pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual-active-bridge inverter.

[0018] In one embodiment, the method further includes:

[0019] When the input voltage exceeds the preset voltage range, determine that the fluctuation of the input voltage meets the adjustment trigger condition.

[0020] In one embodiment, the method further includes:

[0021] Calculate the voltage error amount according to the input voltage and the reference voltage;

[0022] Calculate the error amount range according to the preset voltage range and the reference voltage;

[0023] When the voltage error amount exceeds the error amount range, determine that the fluctuation of the input voltage meets the adjustment trigger condition.

[0024] In one embodiment, the method further includes:

[0025] When the dual-active-bridge inverter is in the preset working state, obtain the voltage fluctuation range of the low-voltage bus capacitor; wherein, the preset working state includes that the input device of the dual-active-bridge inverter is a constant-voltage DC source, and the power of the constant-voltage DC source is greater than the peak output power of the dual-active-bridge inverter;

[0026] Determine the preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor.

[0027] In a second aspect, the present application further provides a control device for a dual-active-bridge inverter, the device comprising:

[0028] an input voltage acquisition module, configured to acquire the input voltage of the dual-active-bridge inverter;

[0029] an adjustment amount determination module, configured to determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage;

[0030] a control module, configured to acquire a current reference value, determine control parameters according to the updated current reference value and the current adjustment amount, and control the operation of the dual-active-bridge inverter by using the control parameters to adjust the grid-connected current output by the dual-active-bridge inverter from the grid connection port.

[0031] In a third aspect, the present application further provides an electronic device, comprising a memory and a processor, the memory storing a computer program, and when the processor executes the computer program, the following steps are implemented:

[0032] Acquire the input voltage of the dual-active-bridge inverter;

[0033] Determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage;

[0034] Acquire a current reference value, determine control parameters according to the updated current reference value and the current adjustment amount, and control the operation of the dual-active-bridge inverter by using the control parameters to adjust the grid-connected current output by the dual-active-bridge inverter from the grid connection port.

[0035] In a fourth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0036] Acquire the input voltage of the dual-active-bridge inverter;

[0037] Determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage;

[0038] Acquire a current reference value, determine control parameters according to the updated current reference value and the current adjustment amount, and control the operation of the dual-active-bridge inverter by using the control parameters to adjust the grid-connected current output by the dual-active-bridge inverter from the grid connection port.

[0039] In a fifth aspect, the present application further provides a computer program product, comprising a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0040] Acquire the input voltage of the dual-active-bridge inverter;

[0041] Determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage;

[0042] Obtain the current reference value, determine the control parameter according to the updated current reference value and the current adjustment amount, and use the control parameter to control the operation of the dual-active-bridge inverter to adjust the grid-connected current output from the grid-connected port of the dual-active-bridge inverter.

[0043] For the above control method, device, equipment, medium and product of the dual-active-bridge inverter, obtain the input voltage of the dual-active-bridge inverter; determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage; obtain the current reference value, determine the control parameter according to the updated current reference value and the current adjustment amount, and use the control parameter to control the operation of the dual-active-bridge inverter to adjust the grid-connected current output from the grid-connected port of the dual-active-bridge inverter. In the embodiments of the present application, the grid-connected current output by the dual-active-bridge inverter is adjusted according to the fluctuation of the input voltage of the dual-active-bridge inverter, which can not only achieve the effect of stabilizing the voltage, but also reduce the distortion of the grid-connected current. Description of the Drawings

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1a It is a schematic structural diagram of a wind power generation system in an embodiment;

[0046] Figure 1b It is a schematic structural diagram of a dual-active-bridge inverter in an embodiment;

[0047] Figure 2 It is a schematic flowchart of the control method of a dual-active-bridge inverter in an embodiment;

[0048] Figure 3 It is a schematic flowchart of the step of determining the control parameter in an embodiment;

[0049] Figure 4 It is a schematic flowchart of the step of updating the current reference value in an embodiment;

[0050] Figure 5 It is a schematic flowchart of the step of determining the current adjustment amount in an embodiment;

[0051] Figure 6 It is a schematic flowchart of the step of determining whether the adjustment trigger condition is met in an embodiment;

[0052] Figure 7 A schematic diagram of a flow chart of a step of determining a preset voltage range in one embodiment;

[0053] Figure 8 is a flow chart of a control method of a dual active bridge inverter in another embodiment;

[0054] Figure 9 is a structural block diagram of a control device for a dual active bridge inverter in one embodiment;

[0055] Figure 10 FIG. 4 is a diagram showing the internal structure of an electronic device in one embodiment. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0057] First, before specifically introducing the technical solution of the embodiment of the present application, the technical background or technical evolution context based on which the embodiment of the present application is based is introduced. With the development of new energy technologies, wind power generation systems have also made great progress. Figure 1a A small direct-drive wind power generation system is shown, which uses a rectifier bridge to rectify the current output by the generator stator. The change of wind speed will cause the DC side voltage fluctuation. The grid-side converter is used to stabilize the voltage and feed it into the grid.

[0058] The grid-side converter can be used as follows Figure 1b The dual active bridge type micro-inverter shown in the figure, wherein the dual active bridge type micro-inverter is used as the load of the low voltage bus capacitor in the wind power system. In this case, the inverter is required to stabilize the voltage of the low voltage bus capacitor. The current output by the dual active bridge type micro-inverter is fed into the grid and needs to be synchronized with the grid to meet the phase requirements. The output current needs to be in the same frequency and phase as the grid current.

[0059] However, the energy stored in the low-voltage bus capacitor is limited. Therefore, the change in the instantaneous power output of the inverter will directly affect the voltage on the low-voltage bus capacitor, so when the inverter is working normally, a large ripple will be introduced on the low-voltage bus capacitor. In the existing wind power generation system, the control strategy adopts a conventional dual-loop control strategy. Under this control strategy, in order to keep the DC input voltage stable at the reference point, the output current needs to be adjusted frequently within a single grid cycle, resulting in a large distortion of the current connected to the grid.

[0060] In view of the above problems, an embodiment of the present application provides a control method for a dual-active-bridge inverter. According to the fluctuation of the input voltage of the dual-active-bridge inverter, the grid-connected current output by the dual-active-bridge inverter is adjusted, which can not only achieve the effect of stabilizing the voltage, but also reduce the distortion of the grid-connected current.

[0061] In an exemplary embodiment, as Figure 2 shown, a control method for a dual-active-bridge inverter is provided. Taking the method applied to the Figure 1a grid-side converter in the wind power system, that is, the dual-active-bridge inverter, as an example, the method includes the following steps:

[0062] Step 101, obtain the input voltage of the dual-active-bridge inverter.

[0063] The dual-active-bridge inverter is a load of the low-voltage bus capacitor. Therefore, the input voltage of the dual-active-bridge inverter can be obtained by detecting the voltage of the low-voltage bus capacitor. Alternatively, a voltage sensor can be set, and the input voltage of the dual-active-bridge inverter can be collected through the voltage sensor.

[0064] It should be noted that the acquisition method of the input voltage is not limited to the above examples, and other acquisition methods can also be used.

[0065] Step 102, determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage.

[0066] A corresponding relationship between the fluctuation amount of the input voltage and the current adjustment amount is established in advance. After the input voltage is obtained, the fluctuation amount of the input voltage can be determined according to the input voltage and the preset reference voltage; then, the current adjustment amount is calculated according to the above corresponding relationship and the fluctuation amount of the input voltage.

[0067] For example, the corresponding relationship between the fluctuation amount ΔU of the input voltage and the current adjustment amount ΔI gmref is ΔU = K * ΔI gmref , assuming the input voltage is U1, the reference voltage is Uref, and the fluctuation amount of the input voltage ΔU = U1 - Uref = K * ΔI gmref , then the current adjustment amount ΔI gmref can be calculated.

[0068] Step 103, obtain the current reference value, determine the control parameter according to the updated current reference value and the current adjustment amount, and use the control parameter to control the operation of the dual-active-bridge inverter to adjust the grid-connected current output by the dual-active-bridge inverter from the grid connection port.

[0069] Every half power grid cycle, the current reference value is updated based on the instantaneous current value. After determining the current adjustment amount, obtain the current reference value determined in the previous half power grid cycle. According to the updated current adjustment amount and the current reference value, calculate the current peak value of the current control cycle. Then, according to the pre-established correspondence between the current peak value and the control parameter and the current peak value of the current control cycle, determine the control parameter.

[0070] Use the control parameter to control the operation of the dual active bridge inverter. The dual active bridge inverter will adjust the grid-connected current output from its grid connection port according to the control parameter. Among them, the grid connection port is the port where the dual active bridge inverter is connected to the power grid.

[0071] In the above embodiment, obtain the input voltage of the dual active bridge inverter; determine the current adjustment amount of the dual active bridge inverter according to the fluctuation of the input voltage; obtain the current reference value, determine the control parameter according to the updated current reference value and the current adjustment amount, and use the control parameter to control the operation of the dual active bridge inverter to adjust the grid-connected current output from the grid connection port of the dual active bridge inverter. The embodiment of the present application adjusts the grid-connected current output by the dual active bridge inverter according to the fluctuation of the input voltage of the dual active bridge inverter, which can not only achieve the effect of stabilizing the voltage, but also reduce the distortion of the grid-connected current.

[0072] In an exemplary embodiment, as Figure 3 shown, the current reference value of the present application is updated once every half power grid cycle, and the update process may include the following steps:

[0073] Step 201, every half power grid cycle, calculate the current effective value according to the pre-established first correspondence between the instantaneous value and the effective value and the current instantaneous value.

[0074] For the pre-established first correspondence between the instantaneous value and the effective value, calculate the current instantaneous value every half power grid cycle, and substitute the current instantaneous value into the above first correspondence for calculation to obtain the current effective value.

[0075] Step 202, calculate the current reference value according to the pre-established second correspondence between the effective value and the reference value and the current effective value, and determine the calculated current reference value as the current reference value of the current half power grid cycle.

[0076] For the pre-established second correspondence between the effective value and the reference value, substitute the calculated current effective value into the above second correspondence for calculation to obtain the current reference value, and determine the calculated current reference value as the current reference value of the current half power grid cycle.

[0077] In some embodiments, the second correspondence includes that the product of the effective value and is the reference value, that is, Igmbase = *I grms , where I gmbase is the current reference value, and I grms is the effective value of the current.

[0078] The complete process of updating may include: during grid connection, according to the peak current I gmref and the sine value sinθ of the phase-locked angle of the grid voltage, calculate the instantaneous current value I gref . Substitute the instantaneous current value I gref into the above first corresponding relationship for calculation, then the effective value of the current I grms can be obtained; then substitute the effective value of the current I grms into the above second corresponding relationship for calculation, then the new current reference value I gmbase（n+1） can be obtained; where n is the serial number of half a grid cycle.

[0079] In the above embodiment, every half a grid cycle, according to the first corresponding relationship between the instantaneous value and the effective value established in advance and the instantaneous current value, calculate the effective value of the current; according to the second corresponding relationship between the effective value and the reference value established in advance and the effective value of the current, calculate the current reference value, and determine the calculated current reference value as the current reference value for the current half a grid cycle. In the embodiment of the present application, the current reference value is updated once every half a grid cycle, which can improve the accuracy of the instantaneous current value, thereby more accurately adjusting the grid-connected current and reducing the distortion of the grid-connected current.

[0080] In an exemplary embodiment, as Figure 4 shown, in the above embodiment, "determine the control parameter according to the updated current reference value and the current adjustment amount" may include the following steps:

[0081] Step 301, according to the updated current reference value and the current adjustment amount, calculate the peak current of the current control period, and calculate the instantaneous current value according to the peak current.

[0082] Obtain the current reference value determined in the previous half a grid cycle; calculate according to the current adjustment amount and the current reference value to obtain the peak current of the current control period. Then, multiply the peak current of the current control period by the sine value sinθ of the phase-locked angle of the grid voltage, and the product is the instantaneous current value.

[0083] For example, the current reference value determined in the previous half a grid cycle is I gmbase（n） , the current adjustment amount is ΔI gmref . Calculate the peak current I gmbase（n） of the current control period according to I gmref and ΔI gmref , where n is the serial number of half a grid cycle. The instantaneous current value Igref i(t) = I gmref *sinθ(t), where θ(t) is the grid phase angle at time t.

[0084] Step 302: Determine the control parameters based on the instantaneous current value.

[0085] Among them, the control parameters include at least one of the inner phase-shifting angle and the outer phase-shifting angle.

[0086] Input the instantaneous current value into the grid-connected current loop, and the grid-connected current loop can calculate the inner phase-shifting angle and the outer phase-shifting angle.

[0087] In the above embodiment, according to the updated current reference value and the current adjustment amount, calculate the current peak value of the current control period, and calculate the instantaneous current value based on the current peak value; determine the control parameters according to the instantaneous current value. In the embodiment of the present application, by recalculating the current peak value of the current control period according to the current adjustment amount and the current reference value, a more accurate instantaneous current value can be calculated, so as to determine more suitable control parameters for the dual-active-bridge inverter, and then enable the dual-active-bridge inverter to adjust the grid-connected current in a timely manner and reduce the distortion of the grid-connected current.

[0088] In an exemplary embodiment, as Figure 5 shown, in the above embodiment, "determine the current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage" may include the following steps:

[0089] Step 401: When the fluctuation of the input voltage meets the adjustment trigger condition, calculate the voltage excess according to the input voltage and the preset voltage range.

[0090] After obtaining the input voltage of the dual-active-bridge inverter, determine whether the fluctuation of the input voltage meets the adjustment trigger condition. If it does not meet the adjustment trigger condition, it means that no adjustment is required for the grid-connected current; if it meets the adjustment trigger condition, it means that adjustment is required for the grid-connected current. In this case, calculate the voltage excess according to the input voltage and the preset voltage range.

[0091] For example, if the input voltage exceeds the upper limit of the preset voltage range, calculate the difference between the input voltage and the upper limit of the preset voltage range to obtain the voltage excess. If the input voltage exceeds the lower limit of the preset voltage range, calculate the difference between the lower limit of the preset voltage range and the input voltage to obtain the voltage excess.

[0092] Step 402: Perform conversion processing on the voltage excess according to the pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual-active-bridge inverter.

[0093] Pre-establish a voltage-current conversion relationship, for example, ΔU = K * ΔI gmrefAfter determining the voltage excess ΔU, substitute the voltage excess ΔU into the voltage-current conversion relationship for calculation to obtain the current adjustment amount ΔI of the dual-active-bridge inverter. gmref 。

[0094] In the above embodiments, when the fluctuation of the input voltage meets the adjustment trigger condition, calculate the voltage excess according to the input voltage and the preset voltage range; perform conversion processing on the voltage excess according to the pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual-active-bridge inverter. The embodiments of the present application can determine whether the grid-connected current needs to be adjusted according to the fluctuation of the input voltage, and can calculate the current adjustment amount in a timely manner, so as to adjust the grid-connected current in a timely manner.

[0095] In an exemplary embodiment, the process of determining whether the adjustment trigger condition is met may include: when the input voltage exceeds the preset voltage range, determine that the fluctuation of the input voltage meets the adjustment trigger condition.

[0096] After obtaining the input voltage of the dual-active-bridge inverter, compare the input voltage with the preset voltage range. If the input voltage does not exceed the preset voltage range, determine that the fluctuation of the input voltage does not meet the adjustment trigger condition and there is no need to adjust the grid-connected current.

[0097] If the input voltage exceeds the preset voltage range, determine that the fluctuation of the input voltage meets the adjustment trigger condition, and then it is necessary to adjust the grid-connected current. In this case, calculate the voltage excess, calculate the current adjustment amount of the dual-active-bridge inverter according to the voltage excess, then determine the control parameters according to the current adjustment amount, and use the control parameters to control the dual-active-bridge inverter, so as to adjust the grid-connected current output by the dual-active-bridge inverter.

[0098] In the above embodiments, when the input voltage exceeds the preset voltage range, determine that the fluctuation of the input voltage meets the adjustment trigger condition. The embodiments of the present application determine whether the fluctuation of the input voltage meets the adjustment trigger condition according to the preset voltage range, providing a basis for determining whether to adjust the grid-connected current.

[0099] In an exemplary embodiment, as Figure 6 shown, the process of determining whether the adjustment trigger condition is met may further include the following steps:

[0100] Step 501, calculate the voltage error amount according to the input voltage and the reference voltage.

[0101] The voltage error amount is the difference between the reference voltage and the input voltage. For example, the input voltage is Vbus sample and the reference voltage is Vbus ref , and the voltage error amount Err = Vbus ref - Vbus sample。

[0102] Step 502: Calculate the error quantity range according to the preset voltage range and the reference voltage.

[0103] The upper limit of the error quantity range is the difference between the upper limit of the preset voltage range and the reference voltage; the lower limit of the error quantity range is the difference between the reference voltage and the lower limit of the preset voltage range. For example, if the upper limit of the preset voltage range is VupperLimit and the lower limit of the preset voltage range is VunderLimit, the upper limit of the error quantity range Err_upperLimit = VupperLimit - Vbus ref , and the lower limit of the error quantity range Err_underLimit = Vbus ref - VunderLimit.

[0104] Step 503: When the voltage error quantity exceeds the error quantity range, determine that the fluctuation of the input voltage meets the adjustment trigger condition.

[0105] If the voltage error quantity does not exceed the upper limit of the error quantity range and does not exceed the lower limit of the error quantity range, it is determined that the fluctuation of the input voltage does not meet the adjustment trigger condition, and the grid-connected current does not need to be adjusted.

[0106] If the voltage error quantity exceeds the upper limit of the error quantity range, or if the voltage error quantity exceeds the lower limit of the error quantity range, it is determined that the fluctuation of the input voltage meets the adjustment trigger condition, and the grid-connected current needs to be adjusted. In this case, if the voltage error quantity exceeds the upper limit of the error quantity range, calculate the difference between the voltage error quantity and the upper limit of the error quantity range to obtain the voltage excess; if the voltage error quantity exceeds the lower limit of the error quantity range, calculate the difference between the lower limit of the error quantity range and the voltage error quantity to obtain the voltage excess. After calculating the voltage excess, calculate the current adjustment quantity of the dual-active-bridge inverter according to the voltage-current conversion relationship and the voltage excess. Then, determine the control parameters according to the current adjustment quantity, and use the control parameters to control the dual-active-bridge inverter, so as to adjust the grid-connected current output from the grid-connected port of the dual-active-bridge inverter.

[0107] In the above embodiment, the voltage error quantity is calculated according to the input voltage and the reference voltage; the error quantity range is calculated according to the preset voltage range and the reference voltage; when the voltage error quantity exceeds the error quantity range, it is determined that the fluctuation of the input voltage meets the adjustment trigger condition. The embodiment of the present application determines whether it meets the adjustment trigger condition according to the input voltage, the reference voltage and the preset voltage range, providing a basis for judging whether to adjust the grid-connected current.

[0108] In an exemplary embodiment, as Figure 7 shown, the process of determining the preset voltage range may include the following steps:

[0109] Step 601: When the dual-active-bridge inverter is in a preset operating state, obtain the voltage fluctuation range of the low-voltage bus capacitor.

[0110] Among them, the preset operating state includes that the input device of the dual-active-bridge inverter is a constant-voltage DC source, and the power of the constant-voltage DC source is greater than the peak output power of the dual-active-bridge inverter.

[0111] When determining the preset voltage range, use the constant-voltage DC source as the input device of the dual-active-bridge inverter, and set the power of the constant-voltage DC source to be greater than the peak output power of the dual-active-bridge inverter. The dual-active-bridge inverter operates in this state, and then obtain the voltage fluctuation range of the low-voltage bus capacitor when the dual-active-bridge inverter is operating.

[0112] Step 602: Determine the preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor.

[0113] Determine the upper limit of the preset voltage range as the upper limit of the voltage fluctuation range of the low-voltage bus capacitor; determine the lower limit of the preset voltage range as the lower limit of the voltage fluctuation range of the low-voltage bus capacitor. Alternatively, adjust the upper limit of the voltage fluctuation range of the low-voltage bus capacitor to obtain the upper limit of the preset voltage range; adjust the lower limit of the voltage fluctuation range of the low-voltage bus capacitor to obtain the lower limit of the preset voltage range.

[0114] In the above embodiment, when the dual-active-bridge inverter is in a preset operating state, obtain the voltage fluctuation range of the low-voltage bus capacitor; determine the preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor. The embodiment of the present application uses a constant-voltage DC source to stabilize the input voltage of the dual-active-bridge inverter, so as to determine a relatively accurate preset voltage range, so as to accurately judge whether it is necessary to adjust the grid-connected current according to the preset voltage range.

[0115] In an exemplary embodiment, a control method for a dual-active-bridge inverter is provided. Taking the method applied to the Figure 1a grid-side converter in a wind power generation system as an example for illustration, the method includes the following steps:

[0116] Step 1: When the dual-active-bridge inverter is in a preset operating state, obtain the voltage fluctuation range of the low-voltage bus capacitor.

[0117] Among them, the preset operating state includes that the input device of the dual-active-bridge inverter is a constant-voltage DC source, and the power of the constant-voltage DC source is greater than the peak output power of the dual-active-bridge inverter.

[0118] Step 2: Determine the preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor.

[0119] Step 3, obtain the input voltage of the dual-active-bridge inverter.

[0120] Step 4, in the case that the input voltage exceeds the preset voltage range, determine that the fluctuation of the input voltage meets the adjustment trigger condition, and / or calculate the voltage error amount according to the input voltage and the reference voltage; calculate the error amount range according to the preset voltage range and the reference voltage; in the case that the voltage error amount exceeds the error amount range, determine that the fluctuation of the input voltage meets the adjustment trigger condition.

[0121] Step 5, in the case that the fluctuation of the input voltage meets the adjustment trigger condition, calculate the voltage excess amount according to the input voltage and the preset voltage range.

[0122] Step 6, perform conversion processing on the voltage excess amount according to the pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual-active-bridge inverter.

[0123] Step 7, based on the current instantaneous value, obtain the current reference value.

[0124] Step 8, calculate the current peak value of the current control period according to the updated current reference value and the current adjustment amount, and calculate the current instantaneous value according to the current peak value.

[0125] Among them, every half of the power grid cycle, calculate the current effective value according to the pre-established first correspondence between the instantaneous value and the effective value and the current instantaneous value; calculate the current reference value according to the pre-established second correspondence between the effective value and the reference value and the current effective value, and determine the calculated current reference value as the current reference value of the current half power grid cycle.

[0126] Step 9, determine the control parameters according to the current instantaneous value; among them, the control parameters include at least one of the internal phase shift angle and the external phase shift angle.

[0127] Step 10, use the control parameters to control the operation of the dual-active-bridge inverter and adjust the grid-connected current output by the dual-active-bridge inverter from the grid-connected port.

[0128] The above process can refer to Figure 8As shown, during grid connection, the instantaneous current value is calculated based on the current peak value, the effective current value is calculated based on the instantaneous current value, and the current reference value is updated based on the effective current value. In the current control cycle (50 μs), if the fluctuation of the input voltage meets the adjustment trigger condition, the current adjustment amount is calculated based on the fluctuation of the input voltage, the current peak value of the current control cycle is calculated based on the updated current reference value and the current adjustment amount, then the instantaneous current value is calculated based on the current peak value, and then the control parameter is determined based on the instantaneous current value. The dual-active-bridge inverter is controlled using the control parameter to adjust the grid-connected current output by the dual-active-bridge inverter. Within a cycle of 1 ms, it is detected whether the startup condition is met, and the upper limits of the output power and the grid-connected current are set.

[0129] In the above embodiments, the grid-connected current output by the dual-active-bridge inverter is adjusted according to the fluctuation of the input voltage of the dual-active-bridge inverter, which can not only achieve the effect of stabilizing the voltage, but also reduce the distortion of the grid-connected current.

[0130] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are sequentially shown according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0131] Based on the same inventive concept, an embodiment of the present application also provides a control device for a dual-active-bridge inverter for implementing the control method of the dual-active-bridge inverter involved above. The implementation solution provided by this device for solving problems is similar to the implementation solution described in the above method. Therefore, the specific limitations in one or more embodiments of the control device for the dual-active-bridge inverter provided below can refer to the limitations on the control method of the dual-active-bridge inverter in the above text, and will not be repeated here.

[0132] In an exemplary embodiment, as Figure 9 shown, a control device for a dual-active-bridge inverter is provided, including:

[0133] An input voltage acquisition module 701, configured to acquire the input voltage of the dual-active-bridge inverter;

[0134] An adjustment amount determination module 702, configured to determine a current adjustment amount of the dual-active-bridge inverter according to the fluctuation of the input voltage;

[0135] A control module 703, configured to obtain a current reference value, determine control parameters according to the updated current reference value and the current adjustment amount, and control the operation of the dual-active-bridge inverter by using the control parameters to adjust the grid-connected current output from the grid-connected port of the dual-active-bridge inverter.

[0136] In one embodiment, the device further includes:

[0137] An effective value determination module, configured to calculate the current effective value according to a first correspondence relationship between the instantaneous value and the effective value established in advance and the current instantaneous value every half grid cycle;

[0138] A reference value update module, configured to calculate the current reference value according to a second correspondence relationship between the effective value and the reference value established in advance and the current effective value, and determine the calculated current reference value as the current peak value of the current half grid cycle.

[0139] In one embodiment, the control module 703 is specifically configured to calculate the current peak value of the current control cycle according to the updated current reference value and the current adjustment amount, and calculate the current instantaneous value according to the current peak value; determine the control parameters according to the current instantaneous value; wherein the control parameters include at least one of an internal phase shift angle and an external phase shift angle.

[0140] In one embodiment, the adjustment amount determination module 702 is specifically configured to calculate a voltage excess amount according to the input voltage and a preset voltage range when the fluctuation of the input voltage meets the adjustment trigger condition; perform a conversion process on the voltage excess amount according to a pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual-active-bridge inverter.

[0141] In one embodiment, the device further includes:

[0142] A first determination module, configured to determine that the fluctuation of the input voltage meets the adjustment trigger condition when the input voltage exceeds the preset voltage range.

[0143] In one embodiment, the device further includes:

[0144] An error amount determination module, configured to calculate a voltage error amount according to the input voltage and a reference voltage;

[0145] An error amount range determination module, configured to calculate an error amount range according to the preset voltage range and the reference voltage;

[0146] A second determination module, configured to determine that the fluctuation of the input voltage meets the adjustment trigger condition when the voltage error amount exceeds the error amount range.

[0147] In one embodiment, the device further includes:

[0148] A fluctuation range determination module, configured to obtain the voltage fluctuation range of the low-voltage bus capacitor when the dual-active-bridge inverter is in a preset working state; wherein, the preset working state includes that the input device of the dual-active-bridge inverter is a constant-voltage DC source, and the power of the constant-voltage DC source is greater than the peak output power of the dual-active-bridge inverter;

[0149] A voltage range determination module, configured to determine a preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor.

[0150] Each module in the above control device of the dual-active-bridge inverter can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the electronic device in hardware form or be independent of the processor, or be stored in the memory of the electronic device in software form, so as to facilitate the processor to call and execute the operations corresponding to the above respective modules.

[0151] In an exemplary embodiment, an electronic device is provided. The electronic device can be disposed in an inverter, and its internal structure diagram can be as Figure 10 shown. The electronic device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the electronic device is used to store the control data of the dual-active-bridge inverter. The input / output interface of the electronic device is used for the processor to exchange information with external devices. The communication interface of the electronic device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a control method for a dual-active-bridge inverter.

[0152] Those skilled in the art can understand that Figure 10 the structure shown in

[0153] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions, and the above instructions can be executed by a processor of an electronic device to complete the above method. For example, the non-transitory computer-readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0154] In an exemplary embodiment, a computer program product is also provided. When the computer program is executed by a processor, the above method can be implemented. The computer program product includes one or more computer instructions. When these computer instructions are loaded and executed on a computer, part or all of the above method can be implemented in accordance with the process or function described in the embodiments of the present application.

[0155] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0156] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0157] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A control method for a dual-active-bridge inverter, characterized in that, The method includes: Obtaining the input voltage of the dual active bridge inverter; Determining the current adjustment amount of the dual active bridge inverter according to the fluctuation of the input voltage; Obtaining a current reference value, determining a control parameter according to the updated current reference value and the current adjustment amount, and using the control parameter to control the operation of the dual active bridge inverter to adjust the grid-connected current output from the grid connection port of the dual active bridge inverter.

2. The method according to claim 1, characterized in that, The method further includes: Every half of the grid cycle, calculating the current effective value according to the first correspondence relationship between the instantaneous value and the effective value established in advance and the current instantaneous value; Calculating the current reference value according to the second correspondence relationship between the effective value and the reference value established in advance and the current effective value, and determining the calculated current reference value as the current reference value for the current half grid cycle.

3. The method according to claim 2, characterized in that, The determining the control parameter according to the updated current reference value and the current adjustment amount includes: Calculating the current peak value of the current control cycle according to the updated current reference value and the current adjustment amount, and calculating the current instantaneous value according to the current peak value; Determining the control parameter according to the current instantaneous value; wherein, the control parameter includes at least one of an internal phase shift angle and an external phase shift angle.

4. The method according to claim 1, wherein The determining the current adjustment amount of the dual active bridge inverter according to the fluctuation of the input voltage includes: When the fluctuation of the input voltage meets the adjustment trigger condition, calculating the voltage excess according to the input voltage and the preset voltage range; Performing conversion processing on the voltage excess according to the pre-established voltage-current conversion relationship to obtain the current adjustment amount of the dual active bridge inverter.

5. The method according to claim 4, wherein The method further includes: When the input voltage exceeds the preset voltage range, determining that the fluctuation of the input voltage meets the adjustment trigger condition.

6. The method according to claim 4, wherein The method further includes: Calculating a voltage error amount according to the input voltage and the reference voltage; Calculating an error amount range according to the preset voltage range and the reference voltage; When the voltage error amount exceeds the error amount range, determining that the fluctuation of the input voltage meets the adjustment trigger condition.

7. The method according to claim 4, wherein The method further includes: When the dual active bridge inverter is in a preset working state, obtaining the voltage fluctuation range of the low-voltage bus capacitor; wherein, the preset working state includes that the input device of the dual active bridge inverter is a constant-voltage DC source, and the power of the constant-voltage DC source is greater than the peak output power of the dual active bridge inverter; Determining the preset voltage range according to the voltage fluctuation range of the low-voltage bus capacitor.

8. A control device for a dual-active-bridge inverter, characterized in that, The device includes: An input voltage acquisition module for acquiring the input voltage of the dual active bridge inverter; An adjustment amount determination module for determining the current adjustment amount of the dual active bridge inverter according to the fluctuation of the input voltage; A control module for acquiring a current reference value, determining a control parameter according to the updated current reference value and the current adjustment amount, and using the control parameter to control the operation of the dual active bridge inverter to adjust the grid-connected current output from the grid connection port of the dual active bridge inverter.

9. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in any one of claims 1 to 7.

11. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in any one of claims 1 to 7.

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