Current control method of resonance circuit, resonance circuit and energy storage inversion equipment

Abstract

The invention discloses a current control method of a resonant circuit, the resonant circuit and energy storage inversion equipment, the resonant circuit comprises a primary circuit, a secondary circuit, a resonant inductor and a resonant capacitor, the primary circuit is connected to the secondary circuit through the resonant inductor, the resonant capacitor is connected in parallel with the secondary circuit, the primary circuit is used for connecting a DC side, and the secondary circuit is used for connecting a DC side. The secondary circuit is used for connecting an AC side; the current control method comprises the following steps: acquiring a resonant current amplitude of a resonant inductor, a power grid voltage of a power grid and a voltage gain ratio of a primary side circuit to a secondary side circuit; obtaining a target gain ratio according to the power grid voltage and the voltage gain ratio; under a preset soft switching constraint condition, obtaining a corresponding value of the resonance current amplitude based on the target gain ratio as a target current effective value; and adjusting working parameters of the primary circuit and the secondary circuit according to the target current effective value. Harmonic distortion of a current waveform pair in the resonant circuit can be reduced, so that electromagnetic interference is reduced, and the quality of electric energy output by the resonant circuit is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power conversion circuits, and in particular to a current control method of a resonant circuit, a resonant circuit, and an energy storage inverter device. Background Art

[0002] At present, resonant circuits are widely used in various devices with power conversion functions, such as energy storage inverter devices. In the existing resonant circuit, the secondary voltage is a time-varying quantity when working, which causes the current in the resonant inductor to also be a time-varying quantity. However, the existing technology lacks means to optimize the current in the resonant inductor, which causes the current waveform to produce more harmonic distortion, which in turn causes the resonant circuit to generate electromagnetic interference, affecting its output power quality. Summary of the invention

[0003] In view of this, the present application provides a current control method of a resonant circuit, a resonant circuit and an energy storage inverter device, which are used to reduce the harmonic distortion of the current waveform pair in the resonant circuit, so as to reduce electromagnetic interference and improve the quality of the output power of the resonant circuit. The technical solution of the present application is as follows:

[0004] In a first aspect, the present application provides a current control method for a resonant circuit, wherein the resonant circuit comprises a primary circuit, a secondary circuit, a resonant inductor and a resonant capacitor, wherein the primary circuit is connected to the secondary circuit via the resonant inductor, the resonant capacitor is connected in parallel with the secondary circuit, the primary circuit is used to connect to a DC side, and the secondary circuit is used to connect to a power grid via an AC side; the current control method comprises: obtaining a resonant current amplitude of the resonant inductor, a power grid voltage of the power grid, and a voltage gain ratio between the primary circuit and the secondary circuit; obtaining a target gain ratio according to the power grid voltage and the voltage gain ratio; obtaining a corresponding value of the resonant current amplitude based on the target gain ratio as a target current effective value under preset soft switching constraints; and adjusting the operating parameters of the primary circuit and the secondary circuit according to the target current effective value.

[0005] In one embodiment of the present application, obtaining the target gain ratio based on the grid voltage and the voltage gain ratio includes: constructing a target coefficient equation based on the grid voltage and a preset algorithm; and obtaining the target gain ratio based on the target coefficient equation and the voltage gain ratio.

[0006] In one embodiment of the present application, obtaining the resonant current amplitude of the resonant inductor includes: obtaining an inner phase shift angle of the primary circuit and an outer phase shift angle between the primary circuit and the secondary circuit; obtaining a DC voltage on the DC side and an AC voltage on the AC side; obtaining a primary voltage according to the inner phase shift angle and the DC voltage, and obtaining a secondary voltage according to the outer phase shift angle and the AC voltage; and calculating and obtaining the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage.

[0007] In one embodiment of the present application, the primary voltage is obtained according to the inner phase shift angle and the DC voltage, and the secondary voltage is obtained according to the outer phase shift angle and the AC voltage, including: using the inner phase shift angle and the DC voltage to obtain an expression for the primary voltage based on the fundamental wave analysis method; using the outer phase shift angle and the AC voltage to obtain an expression for the secondary voltage based on the fundamental wave analysis method.

[0008] In one embodiment of the present application, obtaining the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage includes: obtaining a resonant current expression according to an expression of the primary voltage, an expression of the secondary voltage and the resonant impedance, wherein the resonant impedance is obtained based on the resonant inductor and the resonant capacitor; obtaining a current amplitude expression according to the resonant current expression, which is the resonant current amplitude.

[0009] According to a second aspect of the present application, there is provided a resonant circuit, including a primary circuit, a secondary circuit, a transformer, a resonant inductor, a resonant capacitor and a controller, wherein the primary circuit is connected to the secondary circuit via the transformer and the resonant inductor, the resonant inductor is connected in series with the secondary circuit, the resonant capacitor is connected in parallel with the secondary circuit, the primary circuit is used to connect to a DC side, and the secondary circuit is used to connect to a power grid via an AC side; the controller is connected to the primary circuit and the secondary circuit, the controller is used to obtain a resonant current amplitude of the resonant inductor, a power grid voltage of the power grid and a voltage gain ratio between the primary circuit and the secondary circuit, obtain a target gain ratio according to the power grid voltage and the voltage gain ratio, obtain a corresponding value of the resonant current amplitude based on the target gain ratio as a target current effective value under a preset soft switching constraint, and adjust the operating parameters of the primary circuit and the secondary circuit according to the target current effective value.

[0010] In one embodiment of the present application, the controller is further used to construct a target coefficient equation according to the grid voltage and a preset algorithm, and obtain the target gain ratio according to the target coefficient equation and the voltage gain ratio.

[0011] In one embodiment of the present application, the primary circuit is a full-bridge circuit, including a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a primary inductor and a primary capacitor; the first end of the first switch tube is used to connect to the positive electrode of the DC side, and the second end of the first switch tube is connected to the first end of the second switch tube; the second end of the second switch tube is used to connect to the negative electrode of the DC side; the first end of the third switch tube is connected to the first end of the first switch tube, and the second end of the third switch tube is connected to the first end of the fourth switch tube; the second end of the fourth switch tube is connected to the second end of the second switch tube; the first input end of the transformer is connected to the second end of the first switch tube, and the second input end of the transformer is connected to the second end of the third switch tube; the primary inductor is connected in parallel with the input end of the transformer; and the primary capacitor is connected in parallel with the DC side.

[0012] In one embodiment of the present application, the secondary circuit is a half-bridge circuit, including a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube, and the resonant capacitor includes a first capacitor and a second capacitor; the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the second capacitor and the first capacitor are connected in series in sequence; the first output end of the transformer is connected between the sixth switch tube and the seventh switch tube through the resonant inductor, and the second output end of the transformer is connected between the first capacitor and the second capacitor.

[0013] A third aspect of the present application provides an energy storage inverter device, comprising the resonant circuit.

[0014] The present application obtains the resonant current amplitude of the resonant inductor in the resonant circuit, the grid voltage of the grid, and the voltage gain ratio of the primary circuit and the secondary circuit, obtains the target gain ratio according to the grid voltage and the voltage gain ratio, and then constructs the target current effective value corresponding to the target gain ratio based on the resonant current amplitude according to the soft switching constraint condition, and then adjusts the actual inductor current of the resonant inductor according to the target current effective value. Since the target current effective value is constrained by the target gain ratio, the harmonic distortion in the current waveform is reduced, thereby improving the quality of the output power of the resonant circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an equivalent schematic block diagram of a resonant circuit provided in an embodiment of the present application.

[0016] Figure 2 It is a flow chart of a current control method of a resonant circuit provided in an embodiment of the present application.

[0017] Figure 3 It is a schematic diagram of a flow chart of obtaining the resonant current amplitude provided in an embodiment of the present application.

[0018] Figure 4 It is a schematic diagram of a flow chart for obtaining a primary voltage and a secondary voltage provided in an embodiment of the present application.

[0019] Figure 5 It is a schematic diagram of a flow chart of obtaining the resonant current amplitude provided in an embodiment of the present application.

[0020] Figure 6 It is a schematic diagram of a flow chart for obtaining a target gain ratio provided in an embodiment of the present application.

[0021] Figure 7 It is a schematic block diagram of a resonant circuit provided in an embodiment of the present application.

[0022] Figure 8 It is a circuit diagram of a resonant circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] It should be noted that in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0024] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0025] At present, resonant circuits are widely used in various devices with power conversion functions, such as energy storage inverter devices. In the existing resonant circuit, the secondary voltage is a time-varying quantity when working, which causes the current in the resonant inductor to also be a time-varying quantity. However, the existing technology lacks means to optimize the current in the resonant inductor, which causes the current waveform to produce more harmonic distortion, which in turn causes the resonant circuit to generate electromagnetic interference, affecting its output power quality.

[0026] The embodiments of the present application provide a resonant circuit and a current control method thereof, which are used to reduce the harmonic distortion of a current waveform pair in the resonant circuit, thereby reducing electromagnetic interference and improving the quality of electrical energy output by the resonant circuit.

[0027] Please refer to Figure 1 , Figure 1An equivalent schematic block diagram of a resonant circuit provided in an embodiment of the present application, wherein the resonant circuit 100 includes a primary circuit 110 , a secondary circuit 120 , a resonant inductor 130 and a resonant capacitor 140 .

[0028] In the embodiment of the present application, the primary circuit 110 is connected to the secondary circuit 120 via the resonant inductor 130, the resonant capacitor 140 is connected in parallel with the secondary circuit 120, the primary circuit 110 is used to connect the DC side, and the secondary circuit 120 is used to connect the AC side.

[0029] It can be understood that when the resonant circuit 100 is working, the DC voltage on the DC side is received through the primary circuit 110, and the DC voltage can be converted into a primary AC voltage and then transmitted to the secondary circuit 120 through the resonant inductor 130, and then the secondary circuit 120 adjusts the waveform of the primary AC voltage, and finally outputs the AC voltage to the AC side. Alternatively, the AC voltage on the AC side is received through the secondary circuit 120, and the AC voltage can be converted into a primary DC voltage and then transmitted to the primary circuit 110 through the resonant inductor 130, and then the primary circuit 110 adjusts the waveform of the primary DC voltage, and finally outputs the DC voltage to the DC side.

[0030] Next, combine Figure 1 A current control method for a resonant circuit provided in an embodiment of the present application is described. Please refer to Figure 2 , specifically including the following steps:

[0031] Step S21: obtaining the resonant current amplitude of the resonant inductor, the grid voltage of the grid, and the voltage gain ratio between the primary circuit and the secondary circuit.

[0032] In the embodiment of the present application, the resonant circuit can also be connected to a controller, which controls it to work and executes the various steps in the present embodiment. For example, in an energy storage inverter device provided with a resonant circuit, the primary circuit and the secondary circuit of the resonant circuit can be connected to the main controller of the energy storage inverter device, and the main controller of the energy storage inverter device controls the switching parameters of the primary circuit and the secondary circuit, thereby controlling them to work, and the main controller also executes the various steps in the present embodiment.

[0033] After controlling the resonant circuit to work, the controller can obtain the resonant current amplitude in the resonant inductor, the grid voltage, and the voltage gain ratio of the primary circuit and the secondary circuit. For example, a voltage sampling circuit can be provided in the resonant circuit to collect the grid voltage, the primary voltage, and the secondary voltage and transmit them to the controller. The controller calculates the resonant voltage based on the primary voltage and the secondary voltage, obtains the resonant current based on the resonant voltage and the impedance of the resonant circuit to obtain the resonant current amplitude, and the control circuit also obtains the above-mentioned voltage gain ratio based on the primary voltage and the secondary voltage.

[0034] Step S22: Obtain a target gain ratio according to the grid voltage and the voltage gain ratio.

[0035] Step S23: Under the preset soft switching constraint condition, a corresponding value of the resonant current amplitude based on the target gain ratio is obtained as a target current effective value.

[0036] It can be understood that the effective value of the current of the resonant inductor is positively correlated with the conduction loss of each switch tube in the resonant circuit. Therefore, under the soft switching condition constraint of the resonant circuit, the optimized target current effective value of the resonant inductor based on the target gain ratio is obtained. The actual inductor current of the resonant inductor is adjusted according to the target current effective value, which can reduce the harmonic distortion in the current waveform and thus improve the quality of the output power of the resonant circuit.

[0037] Step S24: adjusting the operating parameters of the primary circuit and the secondary circuit according to the target current effective value.

[0038] In an embodiment of the present application, after the controller obtains the target current effective value of the resonant inductor according to a preset current effective value algorithm, it can adjust the working parameters of the primary circuit and the secondary circuit according to the target current effective value, so that the current value of the resonant inductor gradually approaches the target current effective value, thereby reducing the harmonic distortion in the current waveform, thereby improving the quality of the output power of the resonant circuit.

[0039] In some embodiments, the controller can adjust the duty cycle and frequency and other operating parameters of each switch tube in the primary circuit and the secondary circuit, thereby adjusting the current value of the resonant inductor. For example, when the controller outputs a PWM signal to each switch tube in the primary circuit and the secondary circuit for control, the controller can adjust the duty cycle and frequency of the PWM signal. Among them, when adjusting the duty cycle of the primary circuit and the secondary circuit, the controller can calculate the corresponding inner phase shift angle and outer phase shift angle according to the above target current effective value, and then control the above duty cycle according to the inner phase shift angle and the outer phase shift angle.

[0040] It can be understood that the present application obtains the resonant current amplitude of the resonant inductor in the resonant circuit, the grid voltage of the grid, and the voltage gain ratio of the primary circuit and the secondary circuit, obtains the target gain ratio according to the grid voltage and the voltage gain ratio, and then constructs the resonant current amplitude based on the target current effective value corresponding to the target gain ratio according to the soft switching constraint condition, and then adjusts the actual inductor current of the resonant inductor according to the target current effective value. Since the target current effective value is constrained by the target gain ratio, the harmonic distortion in the current waveform is reduced, thereby improving the quality of the output power of the resonant circuit.

[0041] In some embodiments, Figure 3 As shown, the above step S21 of obtaining the resonant current amplitude of the resonant inductor may also include the following steps:

[0042] Step S31: obtaining an inner phase shift angle of the primary circuit and an outer phase shift angle between the primary circuit and the secondary circuit.

[0043] In an embodiment of the present application, after controlling the resonant circuit to work, the controller can define a variable of the inner phase shift angle of the primary circuit and a variable of the outer phase shift angle between the primary circuit and the secondary circuit, so that after subsequently calculating the target current effective value of the resonant circuit, the corresponding inner phase shift angle and the corresponding outer phase shift angle can be obtained according to the target current effective value as working parameters to adjust the resonant circuit.

[0044] Step S32: obtaining the DC voltage on the DC side and the AC voltage on the AC side.

[0045] In the implementation of the present application, the controller may also be connected to the DC side and the AC side of the resonant circuit to obtain the DC voltage on the DC side and the AC voltage on the AC side. In some embodiments, a DC voltage sampling circuit may be provided on the DC side, and an AC voltage sampling circuit may be provided on the AC side, the DC voltage sampling circuit is used to collect the DC voltage on the DC side and transmit it to the controller, and the AC voltage sampling circuit is used to collect the AC voltage on the AC side and transmit it to the controller.

[0046] Step S33: obtaining the primary voltage according to the inner phase shift angle and the DC voltage, and obtaining the secondary voltage according to the outer phase shift angle and the AC voltage.

[0047] In an embodiment of the present application, after obtaining the inner phase shift angle and the DC voltage, the controller of the resonant circuit can calculate the primary voltage of the primary circuit based on the inner phase shift angle and the DC voltage; and after obtaining the outer phase shift angle and the AC voltage, the controller can calculate the secondary voltage of the secondary circuit based on the outer phase shift angle and the AC voltage.

[0048] Step S34: Calculate the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage.

[0049] It can be understood that both the primary voltage and the secondary voltage are AC voltages. In some embodiments, after calculating and obtaining the primary voltage and the secondary voltage, the controller can further obtain the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage. For example, the controller can calculate the resonant voltage of the resonant inductor according to the primary voltage and the secondary voltage, obtain the resonant current according to the resonant voltage and the impedance of the resonant inductor, and finally obtain the above-mentioned resonant current amplitude.

[0050] In some embodiments, Figure 4 As shown, the above step S33 of obtaining the primary voltage and the secondary voltage may also include the following steps:

[0051] Step S41: using the internal phase shift angle and the DC voltage to obtain an expression for the primary voltage based on the fundamental wave analysis method.

[0052] In the embodiment of the present application, the expression of the primary voltage constructed based on the fundamental wave analysis method can be:

[0053]

[0054] In the formula, v p is the primary voltage, V dc is the DC voltage on the DC side, n is the turns ratio of the transformer between the primary voltage and the transformed voltage, and D1 is the internal phase shift angle.

[0055] Step S42: using the external phase shift angle and the AC voltage to obtain an expression for the secondary voltage based on the fundamental wave analysis method.

[0056] In the embodiment of the present application, the expression of the secondary voltage constructed based on the fundamental wave analysis method can be:

[0057]

[0058] In the formula, v s is the secondary voltage, U g is the AC voltage on the AC side, and D2 is the external shift phase angle.

[0059] In some embodiments, Figure 5 As shown, the above step S34 of obtaining the resonant current amplitude may also include the following steps:

[0060] Step S51: obtaining a resonant current expression according to an expression of the primary voltage, an expression of the secondary voltage and the resonant impedance, wherein the resonant impedance is obtained based on the resonant inductance and the resonant capacitance.

[0061] In the embodiment of the present application, the resonant current expression based on the fundamental wave analysis method can be:

[0062]

[0063] Where i is the resonant current, X eq is the above-mentioned resonant impedance.

[0064] Step S52: Obtain a current amplitude expression according to the resonant current expression, which is the resonant current amplitude.

[0065] In the embodiment of the present application, the above formula can be written The current amplitude expression can be obtained as That is the above-mentioned resonant current amplitude.

[0066] In the present application embodiment, Figure 6As shown, the above step S22 of obtaining the target gain ratio may further include the following steps:

[0067] Step S61: construct a target coefficient equation according to the grid voltage and a preset algorithm.

[0068] In the embodiment of the present application, the target coefficient equation k m Can be:

[0069]

[0070] Where m is the voltage gain ratio between the primary circuit and the secondary circuit.

[0071] Step S62: Obtain a target gain ratio according to the target coefficient equation and the voltage gain ratio.

[0072] It can be understood that in the above step S23, under the preset soft switching constraint condition, obtaining the corresponding value of the resonant current amplitude based on the target gain ratio as the target current effective value specifically includes:

[0073] According to the resonant current expression The part of the resonant current related to the inner phase shift angle and the outer phase shift angle can be obtained, that is, the part related to the control amount is obtained as: Then we know that the soft switching condition is From the above, we can know that the resonant current amplitude is The part of the resonant current amplitude related to the inner phase shift angle and the outer phase shift angle is obtained, that is, the part related to the control amount is obtained as follows: Where m is the voltage gain ratio of the primary voltage to the secondary voltage.

[0074] If the soft switching constraint is met The optimal G value corresponding to the resonant current amplitude is A, which is the target current effective value. Among them, the maximum value of cos(πD1)cos(b) is 1, and through the target coefficient equation k m Can be constrained Not greater than 1, thereby avoiding harmonic distortion caused by oscillation of the calculated target current effective value.

[0075] It is understandable that the above constraints In the equation, since the maximum value of cos(πD1)cos(b) is 1, There is a case where it is greater than 1. Greater than 1 and without the above coefficient k m The equation of the constraint condition has no solution, but in this scheme, by constructing and introducing the coefficient k m , you can When greater than 1, the limit is equal to 1, thereby avoiding the situation where the constraint equation has no solution and the calculated target current effective value generates harmonic distortion due to oscillation.

[0076] Please refer to Figure 7 An embodiment of the present application provides a schematic block diagram of a resonant circuit, wherein the resonant circuit 700 includes: a primary circuit 710, a secondary circuit 720, a transformer 730, a resonant inductor 740, a resonant capacitor 750 and a controller 760.

[0077] In the embodiment of the present application, the primary circuit 710 is connected to the secondary circuit 720 through the transformer 730 and the resonant inductor 740, the resonant inductor 740 is connected in series with the secondary circuit 720, the resonant capacitor 750 is connected in parallel with the secondary circuit 720, the primary circuit 710 is used to connect the DC side, and the secondary circuit 720 is used to connect the AC side;

[0078] The controller 760 is connected to the primary circuit 710 and the secondary circuit 720. The controller 760 is used to obtain the resonant current amplitude of the resonant inductor 740, the grid voltage of the grid, and the voltage gain ratio between the primary circuit 710 and the secondary circuit 720. According to the grid voltage and the voltage gain ratio, the target gain ratio is obtained. Under the preset soft switching constraint conditions, the corresponding value of the resonant current amplitude based on the target gain ratio is obtained as the target current effective value, and the operating parameters of the primary circuit 710 and the secondary circuit 720 are adjusted according to the target current effective value.

[0079] In some embodiments, the controller 760 is further used to construct a target coefficient equation according to the grid voltage and a preset algorithm, and obtain a target gain ratio according to the target coefficient equation and the voltage gain ratio.

[0080] In some embodiments, the controller 760 is also used to: obtain the inner phase shift angle of the primary circuit 710, and the outer phase shift angle between the primary circuit 710 and the secondary circuit 720, obtain the DC voltage on the DC side, and the AC voltage on the AC side, obtain the primary voltage according to the inner phase shift angle and the DC voltage, obtain the secondary voltage according to the outer phase shift angle and the AC voltage, and obtain the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage.

[0081] In some embodiments, the controller 760 is further used to: obtain an expression of the primary voltage based on the fundamental wave analysis method using the inner phase shift angle and the DC voltage, and obtain an expression of the secondary voltage based on the fundamental wave analysis method using the outer phase shift angle and the AC voltage.

[0082] In some embodiments, the controller 760 is also used to: obtain a resonant current expression based on an expression of the primary voltage, an expression of the secondary voltage, and the resonant impedance, wherein the resonant impedance is obtained based on the resonant inductance and the resonant capacitance, and obtain a current amplitude expression based on the resonant current expression, which is the resonant current amplitude.

[0083] Please refer to Figure 8 , Figure 8 A circuit diagram of a resonant circuit 700 provided in an embodiment of the present application is shown in FIG. 7 , wherein the primary circuit 710 is a full-bridge circuit, including a first switch tube S1 , a second switch tube S2 , a third switch tube S3 , a fourth switch tube S4 , a primary inductor Lm and a primary capacitor Cdc.

[0084] In the embodiment of the present application, the first end of the first switch tube S1 is used to connect to the positive electrode of the DC side Vdc, and the second end of the first switch tube S1 is connected to the first end of the second switch tube S2; the second end of the second switch tube S2 is used to connect to the negative electrode of the DC side Vdc; the first end of the third switch tube S3 is connected to the first end of the first switch tube S1, and the second end of the third switch tube is connected to the first end of the fourth switch tube S4; the second end of the fourth switch tube S4 is connected to the second end of the second switch tube S2.

[0085] The first input end of the transformer 730 is connected to the second end of the first switch tube S1, and the second input end of the transformer 630 is connected to the second end of the third switch tube; the primary inductor Lm is connected in parallel with the input end of the transformer 730; and the primary capacitor Cdc is connected in parallel with the DC side Vdc.

[0086] Among them, the secondary circuit 720 is a half-bridge circuit, including a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7 and an eighth switch tube S8, and the resonant capacitor 650 includes a first capacitor Cr1 and a second capacitor Cr2; the fifth switch tube S5, the sixth switch tube S6, the seventh switch tube S7, the eighth switch tube S8, the second capacitor Cr2 and the first capacitor Cr1 are connected in series in sequence; the first output end of the transformer 730 is connected between the sixth switch tube S6 and the seventh switch tube S7 through the resonant inductor 740, and the second output end of the transformer 730 is connected between the first capacitor Cr1 and the second capacitor Cr2.

[0087] It can be understood that the beneficial effects that can be achieved by the resonant circuit 700 of the embodiment of the present application can refer to the beneficial effects of the current control method of any of the aforementioned embodiments, and will not be repeated here.

[0088] In the embodiment of the present application, a more detailed functional description of each of the above modules can be referred to the corresponding content of the aforementioned part, which will not be repeated here.

[0089] An embodiment of the present application further provides a computer storage medium, which stores a computer program. When the computer program is executed by a processor, the processor executes the above-mentioned current control method.

[0090] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer storage medium or transmitted through the computer storage medium. The computer instructions can be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer storage medium can be any available medium that a computer can access or a data storage device such as a server, data center, etc. that contains one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital versatile disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0091] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes. In the absence of conflict, the technical features in this embodiment and the implementation scheme can be combined arbitrarily.

[0092] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the protection scope determined by the claims of the present application.

Claims

1. A current control method for a resonant circuit, characterized in that: The resonant circuit comprises a primary circuit, a secondary circuit, a resonant inductor and a resonant capacitor, the primary circuit is connected to the secondary circuit via the resonant inductor, the resonant capacitor is connected in parallel with the secondary circuit, the primary circuit is used to connect to the DC side, and the secondary circuit is used to connect to the power grid via the AC side; The current control method comprises: Acquire the resonant current amplitude of the resonant inductor, the grid voltage of the grid, and the voltage gain ratio of the primary circuit to the secondary circuit; Obtaining a target gain ratio according to the grid voltage and the voltage gain ratio; Under the preset soft switching constraint condition, obtaining the corresponding value of the resonant current amplitude based on the target gain ratio as the target current effective value; The operating parameters of the primary circuit and the secondary circuit are adjusted according to the target current effective value.

2. The current control method according to claim 1, characterized in that: The step of obtaining a target gain ratio according to the grid voltage and the voltage gain ratio includes: Constructing a target coefficient equation according to the grid voltage and a preset algorithm; The target gain ratio is obtained according to the target coefficient equation and the voltage gain ratio.

3. The current control method according to claim 1, characterized in that: The obtaining the resonant current amplitude of the resonant inductor includes: Acquire an inner phase shift angle of the primary circuit and an outer phase shift angle between the primary circuit and the secondary circuit; Acquiring a DC voltage on the DC side and an AC voltage on the AC side; Obtaining a primary voltage according to the inner phase shift angle and the DC voltage, and obtaining a secondary voltage according to the outer phase shift angle and the AC voltage; The resonant current amplitude of the resonant inductor is calculated according to the primary voltage and the secondary voltage.

4. The current control method according to claim 3, characterized in that: The step of obtaining the primary voltage according to the inner phase shift angle and the DC voltage, and obtaining the secondary voltage according to the outer phase shift angle and the AC voltage, comprises: Obtaining an expression of the primary voltage based on a fundamental wave analysis method using the inner phase shift angle and the DC voltage; The external phase shift angle and the AC voltage are used to obtain an expression for the secondary voltage based on a fundamental wave analysis method.

5. The current control method according to claim 4, characterized in that: The obtaining the resonant current amplitude of the resonant inductor according to the primary voltage and the secondary voltage comprises: Obtaining a resonant current expression according to the expression of the primary voltage, the expression of the secondary voltage and the resonant impedance, wherein the resonant impedance is obtained based on the resonant inductance and the resonant capacitance; The current amplitude expression is obtained according to the resonant current expression, which is the resonant current amplitude.

6. A resonant circuit, characterized in that: It includes a primary circuit, a secondary circuit, a transformer, a resonant inductor, a resonant capacitor and a controller, wherein the primary circuit is connected to the secondary circuit through the transformer and the resonant inductor, the resonant inductor is connected in series with the secondary circuit, the resonant capacitor is connected in parallel with the secondary circuit, the primary circuit is used to connect to the DC side, and the secondary circuit is used to connect to the power grid through the AC side; The controller is connected to the primary circuit and the secondary circuit, and is used to obtain the resonant current amplitude of the resonant inductor, the grid voltage of the grid, and the voltage gain ratio between the primary circuit and the secondary circuit, obtain a target gain ratio according to the grid voltage and the voltage gain ratio, obtain the resonant current amplitude based on the corresponding value of the target gain ratio as a target current effective value under preset soft switching constraints, and adjust the operating parameters of the primary circuit and the secondary circuit according to the target current effective value.

7. The resonant circuit according to claim 6, characterized in that The controller is also used to construct a target coefficient equation according to the grid voltage and a preset algorithm, and obtain the target gain ratio according to the target coefficient equation and the voltage gain ratio.

8. The resonant circuit according to claim 6, characterized in that The primary circuit is a full-bridge circuit, including a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a primary inductor and a primary capacitor; The first end of the first switch tube is used to connect the positive electrode of the DC side, and the second end of the first switch tube is connected to the first end of the second switch tube; the second end of the second switch tube is used to connect the negative electrode of the DC side; the first end of the third switch tube is connected to the first end of the first switch tube, and the second end of the third switch tube is connected to the first end of the fourth switch tube; the second end of the fourth switch tube is connected to the second end of the second switch tube; The first input end of the transformer is connected to the second end of the first switch tube, and the second input end of the transformer is connected to the second end of the third switch tube; the primary inductor is connected in parallel with the input end of the transformer; and the primary capacitor is connected in parallel with the DC side.

9. The resonant circuit according to claim 6, characterized in that: The secondary circuit is a half-bridge circuit, including a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube, and the resonant capacitor includes a first capacitor and a second capacitor; The fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the second capacitor and the first capacitor are connected in series in sequence; the first output end of the transformer is connected between the sixth switch tube and the seventh switch tube through the resonant inductor, and the second output end of the transformer is connected between the first capacitor and the second capacitor.

10. An energy storage inverter device, characterized in that: Comprising the resonant circuit as claimed in any one of claims 6 to 9.

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