Grid-connected control method, device and storage medium for voltage conversion circuit

Abstract

The present application relates to a grid-connected control method, device and storage medium for a voltage conversion circuit. The method includes: in the process of the voltage conversion circuit being connected to the power grid, detecting whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid; when the output bus voltage is less than the peak voltage, controlling the switch tube included in the primary full-bridge circuit and the switch tube included in the secondary full-bridge circuit to a preset switch state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage. The use of this method can improve the grid-connected adaptability of the voltage conversion circuit.

Description

Technical Field

[0001] The present application relates to the technical field of voltage conversion circuits, and particularly to a grid connection control method, device, and storage medium for a voltage conversion circuit. Background Art

[0002] Currently, when an open-loop LLC circuit is used in an inverter, the output bus voltage gain of the open-loop LLC circuit is fixed. During the process of the inverter connecting to the grid, device damage is likely to occur, resulting in poor grid connection adaptability of the inverter. Summary of the Invention

[0003] Based on this, in view of the above technical problems, it is necessary to provide a grid connection control method, device, and storage medium for a voltage conversion circuit that can improve the grid connection adaptability of the voltage conversion circuit.

[0004] In a first aspect, the present application provides a grid connection control method for a voltage conversion circuit. The voltage conversion circuit includes an open-loop LLC circuit, and the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The method includes:

[0005] During the process of the voltage conversion circuit connecting to the grid, detecting whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the grid;

[0006] When the output bus voltage is less than the peak voltage, controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0007] In one embodiment, the controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state includes:

[0008] Determining the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage;

[0009] Controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching state according to the phase difference between the primary and secondary switching tubes.

[0010] In one embodiment, the determining the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage includes:

[0011] The output bus voltage is adjusted by using a PI adjustment algorithm to obtain the phase difference between the primary and secondary switching tubes, where the reference voltage in the PI adjustment algorithm is configured as the peak voltage.

[0012] In one embodiment, the primary full-bridge circuit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, and the secondary full-bridge circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, and an eighth switching tube. Controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching state according to the phase difference between the primary and secondary switching tubes includes:

[0013] Control the fifth switching tube and the sixth switching tube to turn off;

[0014] According to the phase difference between the primary and secondary switching tubes, control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching state.

[0015] In one embodiment, controlling the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching state according to the phase difference between the primary and secondary switching tubes includes:

[0016] According to the phase difference between the primary and secondary switching tubes, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn on within a first time period, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, and the eighth switching tube form a first energy storage loop, and the first energy storage loop is used to charge the energy storage element included in the resonant circuit;

[0017] According to the phase difference between the primary and secondary switching tubes, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn off within a second time period, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, the seventh switching tube, and the output capacitor form a first charging loop, and the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The second time period is after the first time period in terms of timing.

[0018] In one embodiment, controlling the first switch, the second switch, the third switch, the fourth switch, the seventh switch, and the eighth switch to the preset switching state according to the phase difference between the primary and secondary switching tubes further includes:

[0019] According to the phase difference between the primary and secondary switching tubes, within a third time period, control the first switch to conduct, the second switch to turn off, the third switch to turn off, the fourth switch to conduct, the seventh switch to conduct, and the eighth switch to turn off, so that the first switch, the fourth switch, the transformer, the resonant circuit, the fifth switch, and the seventh switch form a second energy storage loop, and the second energy storage loop is used to charge the energy storage element;

[0020] According to the phase difference between the primary and secondary switching tubes, within a fourth time period, control the first switch to conduct, the second switch to turn off, the third switch to turn off, the fourth switch to conduct, the seventh switch to turn off, and the eighth switch to turn off, so that the first switch, the fourth switch, the transformer, the resonant circuit, the fifth switch, the eighth switch, and the output capacitor form a second charging loop, and the second charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The third time period is after the second time period in time sequence, and the fourth time period is after the third time period in time sequence.

[0021] In one embodiment, the voltage conversion circuit further includes an inverter circuit connected between the open-loop LLC circuit and the power grid. After controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching state, the method further includes:

[0022] Control the switching tubes included in the inverter circuit to turn off, so that the switching tubes included in the inverter circuit form a rectifier circuit.

[0023] In one embodiment, the method further includes:

[0024] When detecting that the power grid voltage passes through zero, control the AC side relay included in the inverter circuit to close, and control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the normal switching state.

[0025] In a second aspect, the present application provides a grid connection control device for a voltage conversion circuit. The voltage conversion circuit includes an open-loop LLC circuit, and the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The device includes:

[0026] A detection module, configured to detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid during the process of the voltage conversion circuit being connected to the power grid;

[0027] A control module, configured to control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state when the output bus voltage is less than the peak voltage, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0028] In a third aspect, the present application provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method described in the first aspect above are implemented.

[0029] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the first aspect above are implemented.

[0030] In a fifth aspect, the present application provides a computer program product, including a computer program. When the computer program is executed by a processor, the steps of the method described in the first aspect above are implemented.

[0031] Grid connection control method, device and storage medium for the above voltage conversion circuit. The voltage conversion circuit includes an open-loop LLC circuit, and the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. During the process of the voltage conversion circuit being connected to the grid, it is detected whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the grid. When the output bus voltage is less than the peak voltage, the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit are controlled to a preset switching state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit. The boost circuit is used to boost the output bus voltage to be equal to the peak voltage. In this way, when the output bus voltage of the voltage conversion circuit is less than the peak voltage of the grid, the output bus voltage of the voltage conversion circuit is boosted through the boost circuit formed by the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor, avoiding the situation that the impact current at the moment of grid connection is too large due to the large gap between the output bus voltage and the peak voltage of the grid, thereby avoiding damage to the devices of the voltage conversion circuit and improving the grid connection adaptability of the voltage conversion circuit. Brief Description of the Drawings

[0032] 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 of the present application 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 related drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is an application environment diagram of the grid connection control method for the voltage conversion circuit in an embodiment;

[0034] Figure 2 It is a flowchart of the grid connection control method for the voltage conversion circuit in an embodiment;

[0035] Figure 3 It is a module diagram of the open-loop LLC circuit in another embodiment;

[0036] Figure 4 It is a flowchart of the computer device controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state in another embodiment;

[0037] Figure 5 It is a circuit diagram of the open-loop LLC circuit in another embodiment;

[0038] Figure 6Schematic diagram of the wave generation mode of each switching transistor in the open-loop LLC circuit in the related art;

[0039] Figure 7 Schematic flowchart of step 402 in another embodiment;

[0040] Figure 8 Schematic circuit diagram of the open-loop LLC circuit in another embodiment;

[0041] Figure 9 Schematic diagram of the current waveform of the switching transistor in the open-loop LLC circuit in another embodiment;

[0042] Figure 10 Schematic diagram of the voltage waveform of the switching transistor in the open-loop LLC circuit in another embodiment;

[0043] Figure 11 Schematic circuit diagram of the open-loop LLC circuit in another embodiment;

[0044] Figure 12 Schematic circuit diagram of the open-loop LLC circuit in another embodiment;

[0045] Figure 13 Schematic circuit diagram of the open-loop LLC circuit in another embodiment;

[0046] Figure 14 Schematic diagram of the wave generation mode of each switching transistor in the open-loop LLC circuit in another embodiment;

[0047] Figure 15 Schematic module diagram of the voltage conversion circuit in another embodiment;

[0048] Figure 16 Schematic flowchart of the grid connection control method of the voltage conversion circuit in another embodiment;

[0049] Figure 17 Schematic circuit diagram of the inverter circuit in another embodiment;

[0050] Figure 18 Structural block diagram of the grid connection control device of the voltage conversion circuit in one embodiment;

[0051] Figure 19 Internal structure diagram of a computer device in one embodiment. Detailed implementation manners

[0052] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to 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.

[0053] When an open-loop LLC circuit is used in an inverter, the output bus voltage gain of the open-loop LLC circuit is fixed. When the input voltage (i.e., the battery voltage) on the primary side of the open-loop LLC circuit is too low, it will cause the output bus voltage of the open-loop LLC circuit to be much lower than the peak voltage of the power grid. If the inverter is forced to be connected to the power grid (or simply referred to as grid connection), due to the large gap between the output bus voltage and the peak voltage of the power grid, it will cause too large an inrush current during grid connection, which is likely to cause damage to the inverter devices, resulting in poor grid connection adaptability of the inverter. At this time, if it is selected that the inverter is not connected to the power grid, it will also weaken the grid connection function adaptability of the inverter, that is, there is also a problem of poor grid connection adaptability of the inverter.

[0054] In view of this, the embodiments of the present application provide a grid connection control method, device and storage medium for a voltage conversion circuit, which can improve the grid connection adaptability of the voltage conversion circuit.

[0055] The grid connection control method for the voltage conversion circuit provided by the embodiments of the present application can be applied to, for example, Figure 1 the application environment shown. Among them, the battery is connected to the voltage conversion circuit, the voltage conversion circuit is connected to the power grid, and the voltage conversion circuit is also connected to the computer device. The voltage conversion circuit can be arranged in the inverter to perform voltage conversion, for example, converting direct current into alternating current.

[0056] The computer device can be a server. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0057] In an exemplary embodiment, as Figure 2 shown, a grid connection control method for a voltage conversion circuit is provided. Taking this method applied to the Figure 1 computer device as an example for description, it includes step 201 and step 202:

[0058] Step 201, during the process of the voltage conversion circuit being connected to the power grid, detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid.

[0059] In the embodiments of the present application, the voltage conversion circuit includes an open-loop LLC circuit. Exemplarily, referring to Figure 3 , Figure 3 as a module schematic diagram of an open-loop LLC circuit. As Figure 3 shown, the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The primary full-bridge circuit is connected to the battery, and the voltage across the output capacitor is the output bus voltage of the voltage conversion circuit.

[0060] The output bus voltage of the voltage conversion circuit is affected by the input voltage (i.e., the battery voltage) on the primary side of the open-loop LLC circuit. If the battery voltage is too low, then the output bus voltage of the open-loop LLC circuit may be lower than the peak voltage of the power grid, resulting in an excessive inrush current during grid connection.

[0061] In the embodiment of the present application, the computer device can sample the output bus voltage of the voltage conversion circuit through a sampling circuit, and detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid after sampling. If the output bus voltage of the voltage conversion circuit is greater than or equal to the peak voltage of the power grid, it indicates that the inrush current during grid connection will not be excessive at this time. Therefore, the existing control strategy can be used to control the voltage conversion circuit to be connected to the power grid.

[0062] If the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid, the following steps of the grid connection control method of the voltage conversion circuit in the embodiment of the present application will be continued to avoid the situation that the inrush current during grid connection of the voltage conversion circuit is excessive due to the large gap between the output bus voltage and the peak voltage of the power grid.

[0063] Step 202, in the case where the output bus voltage is less than the peak voltage, control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit.

[0064] Among them, the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0065] The above preset switching state is different from the conventional switching state of the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit during the process of the traditional voltage conversion circuit being connected to the power grid. That is, in the embodiment of the present application, in the case where the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid, the computer device changes the conduction control logic of the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit, and uses the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor to form a boost circuit to increase the output bus voltage.

[0066] Exemplarily, the boost circuit may include an energy storage stage and a charging stage. In the energy storage stage, energy is stored by charging the energy storage element included in the resonant circuit. In the charging stage, the energy storage element included in the resonant circuit discharges to charge the output capacitor, thereby increasing the voltage across the output capacitor, that is, increasing the output bus voltage of the voltage conversion circuit, and realizing the boost circuit through the charging and discharging of the energy storage element included in the resonant circuit.

[0067] In the above embodiments, when the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid, a boost circuit formed by a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor is used to boost the output bus voltage of the voltage conversion circuit. That is, the existing circuit components are used for improved design to avoid the situation that the impact current at the moment of grid connection is too large due to the large gap between the output bus voltage and the peak voltage of the power grid when the voltage conversion circuit is connected to the grid. Thus, damage to the devices of the voltage conversion circuit can be avoided, and the grid connection adaptability of the voltage conversion circuit is improved.

[0068] In one embodiment, based on Figure 2 the embodiments shown, refer to Figure 4 , this embodiment exemplarily introduces an implementation manner of controlling the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit by a computer device to a preset switching state. As Figure 4 shown, the computer device can execute Figure 4 the steps 401 and 402 shown, including:

[0069] Step 401, determine the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage.

[0070] Please refer to Figure 5 , Figure 5 which is a circuit schematic diagram of an exemplary open-loop LLC circuit. Figure 5 In the open-loop LLC circuit shown, the primary full-bridge circuit includes a first switching tube MOS1, a second switching tube MOS2, a third switching tube MOS3, and a fourth switching tube MOS4. The transformer is Figure 5 the T1 shown. The resonant circuit includes Figure 5 the resonant inductor Lr and the resonant capacitor Cr shown. The secondary full-bridge circuit includes a fifth switching tube MOS5, a sixth switching tube MOS6, a seventh switching tube MOS7, and an eighth switching tube MOS8. The output capacitor is Figure 5 the Cbus shown. R1 is the output dummy load of the open-loop LLC circuit, and the resistance value of R1 is relatively large. Vbus is the output bus voltage of the voltage conversion circuit.

[0071] In the related art, MOS1 / MOS4 and MOS5 / MOS8 are respectively used as the E-group bridge arms on the primary and secondary sides, and the wave generation methods are the same; MOS2 / MOS3 and MOS6 / MOS7 are respectively used as the F-group bridge arms on the primary and secondary sides, and the wave generation methods are the same. MOS1 / MOS2, MOS3 / MOS4, MOS5 / MOS6, and MOS7 / MOS8 are respectively four groups of complementary drives. The driving effective levels (high levels) and duty cycles of the E-group bridge arms and the F-group bridge arms are the same, and the phases differ by 180 degrees. After the open-loop LLC circuit starts up, the output bus voltage Vbus reaches the maximum value. The wave generation methods of each switching tube in the open-loop LLC circuit are as Figure 6 shown. When all the switching tubes (MOS1, MOS4, MOS5, MOS8) included in the E-group bridge arms are turned on, all the switching tubes (MOS2, MOS3, MOS6, MOS7) included in the F-group bridge arms are turned off. When all the switching tubes included in the F-group bridge arms are turned on, all the switching tubes included in the E-group bridge arms are turned off.

[0072] In the related art, due to (where Vbus is the output bus voltage, Vbat is the battery voltage, Ns is the primary-side turns ratio of the transformer in the open-loop LLC circuit, and Np is the secondary-side turns ratio of the transformer in the open-loop LLC circuit), when the battery voltage Vbat decreases as the battery power decreases, Vbus also decreases accordingly. (Vgridpeak is the peak voltage of the power grid). When Vbus < Vgridpeak, , and (Ic is the inrush current at grid connection, Cbus is the capacitance value of the output capacitor, is the instantaneous time at grid connection), the larger it is, the larger the inrush current Ic at grid connection is. When it exceeds the rated current threshold of the device, the device will be damaged.

[0073] In the embodiments of the present application, the computer device determines the phase difference between the primary and secondary switching tubes according to the peak voltage of the power grid and the output bus voltage of the voltage conversion circuit. Please combine Figure 5 , the phase difference Angle between the primary and secondary switching tubes may refer to the phase difference between the first switching tube MOS1 and the eighth switching tube MOS8, and the phase difference between the second switching tube MOS2 and the seventh switching tube MOS7. As is larger, the phase difference Angle between the primary and secondary switching tubes is also larger, that is is positively correlated with the size of the phase difference Angle between the primary and secondary switching tubes. The larger the phase difference Angle between the primary and secondary switching tubes, the larger the boost amplitude of the boost circuit formed by the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor.

[0074] As an implementation, the computer device can use the P (Proportional) I (Integral) regulation algorithm to adjust the output bus voltage, that is, perform PI regulation on the output bus voltage. For the phase difference Angle between the primary and secondary switching tubes, the reference voltage (Vref) in the PI regulation algorithm is set to the peak voltage of the power grid. Based on the PI regulation algorithm, a high-precision phase difference between the primary and secondary switching tubes can be obtained.

[0075] Step 402: According to the phase difference between the primary and secondary switching tubes, control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state.

[0076] After the computer device obtains the phase difference Angle between the primary and secondary switching tubes, the computer device then controls the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state according to the phase difference Angle between the primary and secondary switching tubes.

[0077] In a possible implementation of step 402, referring to Figure 7 , step 402 may include Figure 7 the steps 701 and 702 shown in

[0078] Step 701: Control the fifth switching tube and the sixth switching tube to turn off.

[0079] The computer device controls the fifth switching tube MOS5 and the sixth switching tube MOS6 to turn off. After the fifth switching tube MOS5 and the sixth switching tube MOS6 are turned off, using the unidirectional conduction characteristics of the internal diodes of the fifth switching tube MOS5 and the sixth switching tube MOS6, the fifth switching tube MOS5 and the sixth switching tube MOS6 are equivalent to the diode D in the open-loop LLC circuit.

[0080] Step 702: According to the phase difference between the primary and secondary switching tubes, control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to a preset switching state.

[0081] After the computer device controls the fifth switching tube MOS5 and the sixth switching tube MOS6 to turn off, the other switching tubes in the open-loop LLC circuit can be normally controlled to conduct. Therefore, the computer device controls the remaining first switching tube MOS1, second switching tube MOS2, third switching tube MOS3, fourth switching tube MOS4, seventh switching tube MOS7, and eighth switching tube MOS8 in the open-loop LLC circuit to a preset switching state according to the phase difference between the primary and secondary switching tubes.

[0082] The above embodiments do not require additional hardware circuits. Based on the existing switching transistors and energy storage components in the open-loop LLC circuit topology, the phase difference between the primary and secondary switching transistors is obtained through PI regulation, and the grid connection control method of the embodiments of the present application is executed based on this phase difference between the primary and secondary switching transistors, so that the output bus voltage of the voltage conversion circuit is stabilized at the peak voltage of the power grid. The implementation method is simple and easy to implement, and is conducive to cost control.

[0083] Hereinafter, taking Figure 5 the open-loop LLC circuit shown as an example, the implementation manner of step 702 will be introduced exemplarily.

[0084] In the first time period, the computer device controls the first switching transistor MOS1 to be turned off, the second switching transistor MOS2 to be turned on, the third switching transistor MOS3 to be turned on, the fourth switching transistor MOS4 to be turned off, the seventh switching transistor MOS7 to be turned off, and the eighth switching transistor MOS8 to be turned on according to the phase difference between the primary and secondary switching transistors.

[0085] Please refer to Figure 8 , the computer device controls the conduction times of the second switching transistor MOS2 and the eighth switching transistor MOS8 to have an overlapping part according to the phase difference Angle between the primary and secondary switching transistors, that is, both the second switching transistor MOS2 and the eighth switching transistor MOS8 are in the on state in the first time period. At this time, the second switching transistor MOS2, the third switching transistor MOS3 on the primary side of the transformer, the transformer, the resonant circuit on the secondary side of the transformer, the sixth switching transistor MOS6 (i.e., Figure 8 the diode D6 shown) and the eighth switching transistor MOS8 form a first energy storage loop, and the first energy storage loop is used to charge the energy storage components (i.e., Lr and Cr) included in the resonant circuit. The current flow direction in the first energy storage loop is as shown by the red dotted arrow in Figure 8 , and the output capacitor discharges a small amount in the first time period, and the output capacitor and R1 form a current loop.

[0086] Please refer to Figure 9 and Figure 10 . After the computer device turns off the fifth switching transistor MOS5 and the sixth switching transistor MOS6, as the phase difference Angle between the primary and secondary switching transistors changes, the current waveforms of the switching transistors in the open-loop LLC circuit are as shown in Figure 9 , and the voltage waveforms of the switching transistors in the open-loop LLC circuit are as shown in Figure 10 . Figure 9 and Figure 10 The time period t1 - t2 shown can be the above-mentioned first time period in this embodiment.

[0087] Among them, I(Moss6) / I(Moss7) / I(Moss8) are the currents of the sixth switch MOS6 / the seventh switch MOS7 / the eighth switch MOS8 respectively (the positive direction of the current is from the D pole to the S pole), I(CR) / V(CR) are the current / voltage of the resonant capacitor Cr (the positive direction is the same name terminal), I(LR) / V(LR) are the current / voltage of the resonant inductor Lr (the positive direction is the same name terminal), Vs is the voltage of the secondary side of the transformer, and Vs1 is the voltage at the secondary side of the transformer, the resonant capacitor Cr, and the resonant inductor Lr.

[0088] Under the action of Vs, the energy storage elements (i.e., Lr and Cr) included in the resonant circuit start to be charged and store energy during the first time period (t1 - t2).

[0089] During the second time period, the computer device controls the first switch MOS1 to turn off, the second switch MOS2 to turn on, the third switch MOS3 to turn on, the fourth switch MOS4 to turn off, the seventh switch MOS7 to turn off, and the eighth switch MOS8 to turn off according to the phase difference between the primary and secondary side switch tubes.

[0090] Please refer to Figure 11 , the computer device controls the seventh switch MOS7 to turn off according to the phase difference Angle between the primary and secondary side switch tubes. At this time, the seventh switch MOS7 is equivalent to a diode (i.e., Figure 11 shown as D7), the second switch MOS2, the third switch MOS3, the transformer, the resonant circuit, the sixth switch MOS6, the seventh switch MOS7, and the output capacitor form a first charging loop. The current flow direction in the first charging loop is as shown by the red dotted arrow in Figure 11 . The first charging loop is used to charge the output capacitor through the energy storage elements. The loop current periodically flows through the diode inside the seventh switch MOS7 to the output capacitor to charge the output capacitor, thereby boosting the output bus voltage across the output capacitor.

[0091] In the embodiment of the present application, the second time period is after the first time period in terms of timing. Please continue to refer to Figure 9 and Figure 10 , Figure 9 and Figure 10 The time period t2 - t3 shown in

[0092] can be the above-mentioned second time period in this embodiment. Assume that the boost voltage for boosting the output bus voltage across the output capacitor by the first charging loop is represented by . Then

[0093] During the third time period, the computer device controls the first switch MOS1 to conduct, the second switch MOS2 to turn off, the third switch MOS3 to turn off, the fourth switch MOS4 to conduct, the seventh switch MOS7 to conduct, and the eighth switch MOS8 to turn off according to the phase difference between the primary and secondary side switching tubes during the third time period.

[0094] Please refer to Figure 12 , the computer device controls the conduction times of the first switch MOS1 and the seventh switch MOS7 to have an overlapping part according to the phase difference Angle between the primary and secondary side switching tubes, that is, both the first switch MOS1 and the seventh switch MOS7 are in the conducting state during the third time period. At this time, the first switch MOS1, the fourth switch MOS4, the transformer, the resonant circuit, the fifth switch MOS5 (i.e., Figure 12 the diode D5 shown) and the seventh switch MOS7 form a second energy storage circuit, and the second energy storage circuit is used to charge the energy storage elements (i.e., Lr and Cr). The current flow direction in the second energy storage circuit is as shown by the red dotted arrow in Figure 12 . During the third time period, the output capacitor discharges slightly, and the output capacitor and R1 form a current loop.

[0095] Please continue to refer to Figure 9 and Figure 10 , Figure 9 and Figure 10 The time period t4 - t5 shown in

[0096] can be the above-mentioned third time period in this embodiment, and the third time period is after the second time period in terms of timing.

[0097] Please refer to Figure 13 , the computer device controls the eighth switch MOS8 to turn off according to the phase difference Angle between the primary and secondary side switching tubes. At this time, the turn-off of the eighth switch MOS8 is equivalent to a diode (i.e., Figure 13 the D8 shown). The first switch MOS1, the fourth switch MOS4, the transformer, the resonant circuit, the fifth switch MOS5, the eighth switch MOS8, and the output capacitor form a second charging circuit. The current flow direction in the second charging circuit is as shown by the red dotted arrow in Figure 13 . The second charging circuit is used to charge the output capacitor through the energy storage elements. The loop current periodically flows through the diode inside the eighth switch MOS8 to the output capacitor to charge the output capacitor, so as to boost the output bus voltage across the output capacitor.

[0098] In the embodiment of the present application, the fourth time period is temporally after the third time period. Please continue to refer to Figure 9 and Figure 10 , Figure 9 and Figure 10 . The time period t5 - t6 shown in

[0099] may be the above - mentioned fourth time period in this embodiment. If the boost voltage for boosting the output bus voltage across the output capacitor by the second charging circuit is represented by , then

[0100] Please refer to Figure 14 . In the embodiment of the present application, the wave - generating modes of the switching tubes in the open - loop LLC circuit are as shown in Figure 14 . Control the fifth switching tube MOS5 and the sixth switching tube MOS6 to turn off (these two switching tubes are equivalent to two diodes in the circuit). By changing the phase difference between the primary and secondary switching tubes, adjust the control waveforms of the first switching tube MOS1 - the fourth switching tube MOS4 and the seventh switching tube MOS7, the eighth switching tube MOS8, so that there will be a simultaneous conduction period between the first switching tube MOS1 and the seventh switching tube MOS7, and between the second switching tube MOS2 and the eighth switching tube MOS8. When the second switching tube MOS2 and the eighth switching tube MOS8 conduct simultaneously, the first energy - storage loop charges the energy - storage elements included in the resonant circuit. Thus, after the energy - storage elements are charged, they can discharge to charge the output capacitor, thereby boosting the output bus voltage across the output capacitor. When the first switching tube MOS1 and the seventh switching tube MOS7 conduct simultaneously, the second energy - storage loop charges the energy - storage elements included in the resonant circuit. Thus, after the energy - storage elements are charged, they can discharge to charge the output capacitor, thereby boosting the output bus voltage across the output capacitor. In this way, based on the existing switching tubes and energy - storage elements in the open - loop LLC circuit topology, a boost circuit is formed to boost the output bus voltage, achieving the effect of increasing the output bus voltage.

[0101] In one embodiment, based on any of the above - mentioned embodiments, taking the embodiment shown in Figure 3 as an example, refer to Figure 15 . The voltage conversion circuit of the embodiment of the present application further includes an inverter circuit, and the inverter circuit is connected between the open - loop LLC circuit and the power grid.

[0102] Refer to Figure 16 . After the computer device in this embodiment controls the switching tubes included in the primary full - bridge circuit and the switching tubes included in the secondary full - bridge circuit to the preset switching states, the grid - connection control method of the voltage conversion circuit further includes Figure 16 step 1601 shown in

[0103] Step 1601: Control the switching tubes included in the inverter circuit to turn off, so that the switching tubes included in the inverter circuit form a rectifier circuit.

[0104] Exemplarily, refer to Figure 17 , Figure 17 which is a circuit schematic diagram of an exemplary inverter circuit. The switching tubes included in the inverter circuit may include, for example, Figure 17 the ninth switching tube MOS9, the tenth switching tube MOS10, the eleventh switching tube MOS11, and the twelfth switching tube MOS12 shown in

[0105] When the output bus voltage of the open-loop LLC circuit is less than the peak voltage, the computer device controls the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state to form a boost circuit to boost the output bus voltage to be equal to the peak voltage. After that, at this time, turn off the switching tubes included in the inverter circuit to lock the phase to the power grid. Figure 17 These four switching tubes shown in

[0106] are equivalent to four diodes in the circuit, constituting a rectifier circuit to rectify the power grid input. Figure 16 Please continue to refer to Figure 16 which shows that the grid connection control method of this voltage conversion circuit further includes

[0107] Step 1602: When it is detected that the power grid voltage passes through the zero point, control the AC side relay included in the inverter circuit to close, and control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the normal switching state.

[0108] When the relay S11 is turned on at the zero crossing of the power grid voltage, at this time, since there is no voltage difference between the output bus voltage and the power grid peak voltage, the grid connection impact current can be ignored. At the same time, cancel the grid connection control of the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit, and restore the normal wave generation mode of each switching tube. After rectification by the uncontrolled rectification characteristic of the inverter circuit, charge the bus capacitor. At this time, the battery charging current is the smallest and the battery voltage gradually increases. When the charging current at the battery terminal is small, turn on the full-bridge drive of the inverter circuit to perform PFC (Power Factor Correction) boost regulation charging.

[0109] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are sequentially shown in the direction of the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless specifically stated herein, there is no strict order restriction for the execution of these steps, 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.

[0110] Based on the same inventive concept, an embodiment of the present application further provides a grid connection control device for a voltage conversion circuit for implementing the grid connection control method of the voltage conversion circuit involved above. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the grid connection control device of the voltage conversion circuit provided below can refer to the limitations on the grid connection control method of the voltage conversion circuit in the above text, and will not be repeated here.

[0111] In an exemplary embodiment, as Figure 18 shown, a grid connection control device for a voltage conversion circuit is provided. The voltage conversion circuit includes an open-loop LLC circuit. The open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The device includes:

[0112] A detection module 1801, configured to detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid during the process of the voltage conversion circuit being connected to the power grid;

[0113] A control module 1802, configured to control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state when the output bus voltage is less than the peak voltage, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0114] In one of the embodiments, the control module 1802 includes:

[0115] A determination unit, configured to determine the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage;

[0116] A control unit, configured to control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching states according to the phase difference between the primary and secondary switching tubes.

[0117] In one embodiment, the determining unit is specifically configured to adjust and process the output bus voltage by using a PI regulation algorithm to obtain the phase difference between the primary and secondary switching tubes, where the reference voltage in the PI regulation algorithm is configured as the peak voltage.

[0118] In one embodiment, the primary full-bridge circuit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, and the secondary full-bridge circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, and an eighth switching tube. The control unit is specifically configured to control the fifth switching tube and the sixth switching tube to turn off; and control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching states according to the phase difference between the primary and secondary switching tubes.

[0119] In one embodiment, the control unit is specifically configured to, according to the phase difference between the primary and secondary switching tubes, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn on within a first time period, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, and the eighth switching tube form a first energy storage loop, and the first energy storage loop is used to charge the energy storage element included in the resonant circuit; and control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn off within a second time period according to the phase difference between the primary and secondary switching tubes, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, the seventh switching tube, and the output capacitor form a first charging loop, and the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor, and the second time period is after the first time period in terms of timing.

[0120] In one embodiment, the control unit is specifically configured to control, according to the phase difference between the primary and secondary switching tubes, the first switching tube to conduct, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to conduct, the seventh switching tube to conduct, and the eighth switching tube to turn off within a third time period, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, and the seventh switching tube form a second energy storage loop for charging the energy storage element; and control, according to the phase difference between the primary and secondary switching tubes, the first switching tube to conduct, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to conduct, the seventh switching tube to turn off, and the eighth switching tube to turn off within a fourth time period, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, the eighth switching tube, and the output capacitor form a second charging loop for charging the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The third time period is after the second time period in terms of timing, and the fourth time period is after the third time period in terms of timing.

[0121] In one embodiment, the voltage conversion circuit further includes an inverter circuit connected between the open-loop LLC circuit and the power grid. The control module 1802 is further configured to control the switching tubes included in the inverter circuit to turn off, so that the switching tubes included in the inverter circuit form a rectifier circuit.

[0122] In one embodiment, the control module 1802 is further configured to control the AC-side relay included in the inverter circuit to close and control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the normal switching state when detecting the zero-crossing point of the grid voltage.

[0123] Each module in the grid connection control device of the above voltage conversion circuit can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory in the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to the above modules.

[0124] In an exemplary embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as Figure 19As shown. The computer 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 computer device is used to provide computing and control capabilities. The memory of the computer 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 computer device is used to store grid connection control data of the voltage conversion circuit. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer 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 grid connection control method for a voltage conversion circuit.

[0125] Those skilled in the art can understand that Figure 19 the structure shown in is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0126] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:

[0127] During the process of the voltage conversion circuit being connected to the power grid, detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid;

[0128] When the output bus voltage is less than the peak voltage, control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0129] In one embodiment, when the processor executes the computer program, the following steps are specifically implemented:

[0130] Determine the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage;

[0131] Control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching states according to the phase difference between the primary and secondary switching tubes.

[0132] In one embodiment, when the processor executes the computer program, the following steps are specifically implemented:

[0133] Use the PI regulation algorithm to regulate the output bus voltage to obtain the phase difference between the primary and secondary switching tubes. Among them, the reference voltage in the PI regulation algorithm is configured as the peak voltage.

[0134] In one embodiment, the primary full-bridge circuit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, and the secondary full-bridge circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, and an eighth switching tube. When the processor executes the computer program, the following steps are specifically implemented:

[0135] Control the fifth switching tube and the sixth switching tube to turn off;

[0136] According to the phase difference between the primary and secondary switching tubes, control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching states.

[0137] In one embodiment, when the processor executes the computer program, the following steps are specifically implemented:

[0138] According to the phase difference between the primary and secondary switching tubes, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn on within the first time period, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, and the eighth switching tube form a first energy storage loop, and the first energy storage loop is used to charge the energy storage element included in the resonant circuit;

[0139] According to the phase difference between the primary and secondary switching tubes, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn off within the second time period, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, the seventh switching tube, and the output capacitor form a first charging loop, and the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The second time period is after the first time period in terms of timing.

[0140] In one embodiment, when the processor executes the computer program, the following steps are further specifically implemented:

[0141] According to the phase difference between the primary and secondary switching tubes, within a third time period, control the first switching tube to conduct, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to conduct, the seventh switching tube to conduct, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, and the seventh switching tube form a second energy storage loop, and the second energy storage loop is used to charge the energy storage element;

[0142] According to the phase difference between the primary and secondary switching tubes, within a fourth time period, control the first switching tube to conduct, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to conduct, the seventh switching tube to turn off, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, the eighth switching tube, and the output capacitor form a second charging loop, and the second charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The third time period is after the second time period in terms of timing, and the fourth time period is after the third time period in terms of timing.

[0143] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0144] Control the switching tubes included in the inverter circuit to turn off, so that the switching tubes included in the inverter circuit form a rectifier circuit.

[0145] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0146] When detecting that the grid voltage passes through zero, control the AC side relay included in the inverter circuit to close, and control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the normal switching state.

[0147] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0148] During the process of the voltage conversion circuit being incorporated into the grid, detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the grid;

[0149] When the output bus voltage is less than the peak voltage, control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to a preset switching state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0150] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0151] Determine the phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage;

[0152] Control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the preset switching state according to the phase difference between the primary and secondary switching tubes.

[0153] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0154] Use the PI regulation algorithm to adjust the output bus voltage to obtain the phase difference between the primary and secondary switching tubes, where the reference voltage in the PI regulation algorithm is configured as the peak voltage.

[0155] In one embodiment, the primary full-bridge circuit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, and the secondary full-bridge circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, and an eighth switching tube. When the computer program is executed by a processor, the following steps are specifically implemented:

[0156] Control the fifth switching tube and the sixth switching tube to turn off;

[0157] Control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching state according to the phase difference between the primary and secondary switching tubes.

[0158] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0159] According to the phase difference between the primary and secondary switching tubes, within the first time period, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn on, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, and the eighth switching tube form a first energy storage loop, and the first energy storage loop is used to charge the energy storage element included in the resonant circuit;

[0160] According to the phase difference between the primary and secondary switching tubes, within the second time period, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn off, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, the seventh switching tube, and the output capacitor form a first charging loop, and the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor, and the second time period is after the first time period in terms of timing.

[0161] In one embodiment, when the computer program is executed by the processor, the following steps are further specifically implemented:

[0162] According to the phase difference between the primary and secondary switching tubes, within the third time period, control the first switching tube to turn on, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to turn on, the seventh switching tube to turn on, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, and the seventh switching tube form a second energy storage loop, and the second energy storage loop is used to charge the energy storage element;

[0163] According to the phase difference between the primary and secondary switching tubes, within the fourth time period, control the first switching tube to turn on, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to turn on, the seventh switching tube to turn off, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, the eighth switching tube, and the output capacitor form a second charging loop, and the second charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor, the third time period is after the second time period in terms of timing, and the fourth time period is after the third time period in terms of timing.

[0164] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented:

[0165] Control the switch tubes included in the inverter circuit to turn off, so that the switch tubes included in the inverter circuit form a rectifier circuit.

[0166] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:

[0167] When it is detected that the grid voltage passes through the zero point, control the AC side relay included in the inverter circuit to close, and control the switch tubes included in the primary full-bridge circuit and the switch tubes included in the secondary full-bridge circuit to the normal switch state.

[0168] In one embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0169] During the process of the voltage conversion circuit being incorporated into the grid, detect whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the grid;

[0170] When the output bus voltage is less than the peak voltage, control the switch tubes included in the primary full-bridge circuit and the switch tubes included in the secondary full-bridge circuit to the preset switch state, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit, and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

[0171] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0172] Determine the phase difference between the primary and secondary switch tubes according to the peak voltage and the output bus voltage;

[0173] Control the switch tubes included in the primary full-bridge circuit and the switch tubes included in the secondary full-bridge circuit to the preset switch state according to the phase difference between the primary and secondary switch tubes.

[0174] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0175] Use the PI regulation algorithm to adjust the output bus voltage to obtain the phase difference between the primary and secondary switch tubes, where the reference voltage in the PI regulation algorithm is configured as the peak voltage.

[0176] In one embodiment, the primary full-bridge circuit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, and the secondary full-bridge circuit includes a fifth switching tube, a sixth switching tube, a seventh switching tube, and an eighth switching tube. When the computer program is executed by a processor, the following steps are specifically implemented:

[0177] Control the fifth switching tube and the sixth switching tube to turn off;

[0178] According to the phase difference between the primary and secondary switching tubes, control the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the seventh switching tube, and the eighth switching tube to the preset switching state.

[0179] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0180] According to the phase difference between the primary and secondary switching tubes, within a first time period, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn on, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, and the eighth switching tube form a first energy storage loop, and the first energy storage loop is used to charge the energy storage element included in the resonant circuit;

[0181] According to the phase difference between the primary and secondary switching tubes, within a second time period, control the first switching tube to turn off, the second switching tube to turn on, the third switching tube to turn on, the fourth switching tube to turn off, the seventh switching tube to turn off, and the eighth switching tube to turn off, so that the second switching tube, the third switching tube, the transformer, the resonant circuit, the sixth switching tube, the seventh switching tube, and the output capacitor form a first charging loop, and the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The second time period is after the first time period in terms of timing.

[0182] In one embodiment, when the computer program is executed by a processor, the following steps are further specifically implemented:

[0183] According to the phase difference between the primary and secondary switching tubes, within a third time period, control the first switching tube to turn on, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to turn on, the seventh switching tube to turn on, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, and the seventh switching tube form a second energy storage loop, and the second energy storage loop is used to charge the energy storage element;

[0184] According to the phase difference between the original secondary switching tubes, within the fourth time period, control the first switching tube to conduct, the second switching tube to turn off, the third switching tube to turn off, the fourth switching tube to conduct, the seventh switching tube to turn off, and the eighth switching tube to turn off, so that the first switching tube, the fourth switching tube, the transformer, the resonant circuit, the fifth switching tube, the eighth switching tube, and the output capacitor form a second charging circuit, and the second charging circuit is used to charge the output capacitor through the energy storage element to boost the output bus voltage across the output capacitor. The third time period is after the second time period in terms of timing, and the fourth time period is after the third time period in terms of timing.

[0185] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:

[0186] Control the switching tubes included in the inverter circuit to turn off, so that the switching tubes included in the inverter circuit form a rectifier circuit.

[0187] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented:

[0188] When the zero crossing of the grid voltage is detected, control the AC side relay included in the inverter circuit to close, and control the switching tubes included in the primary full-bridge circuit and the switching tubes included in the secondary full-bridge circuit to the normal switching state.

[0189] 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 memory and volatile memory. 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 processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0190] 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 the scope recorded in the present application.

[0191] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent 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 fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A grid-connected control method for a voltage conversion circuit, characterized in that: The voltage conversion circuit includes an open-loop LLC circuit, and the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The method includes: During the process of the voltage conversion circuit being connected to the power grid, detecting whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid; When the output bus voltage is less than the peak voltage, the phase difference between the primary and secondary switches is determined according to the peak voltage and the output bus voltage, and the switch tubes included in the primary full-bridge circuit and the switch tubes included in the secondary full-bridge circuit are controlled to a preset switching state according to the phase difference between the primary and secondary switches, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit and the output capacitor form a boost circuit, and the boost circuit is used to boost the output bus voltage to be equal to the peak voltage.

2. The method according to claim 1, characterized in that The determining the phase difference between the primary and secondary switches according to the peak voltage and the output bus voltage includes: The output bus voltage is regulated by using a PI regulation algorithm to obtain the primary-secondary switch phase difference, wherein the reference voltage in the PI regulation algorithm is configured as the peak voltage.

3. The method according to claim 1, characterized in that The primary full-bridge circuit includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, and the secondary full-bridge circuit includes a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube. According to the phase difference between the primary and secondary switch tubes, controlling the switch tubes included in the primary full-bridge circuit and the switch tubes included in the secondary full-bridge circuit to the preset switch state includes: Controlling the fifth switch tube and the sixth switch tube to turn off; According to the phase difference between the primary and secondary side switches, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the seventh switch tube and the eighth switch tube are controlled to the preset switch state.

4. The method according to claim 3, characterized in that The controlling the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the seventh switch tube, and the eighth switch tube to the preset switch state according to the phase difference between the primary and secondary switches includes: According to the phase difference between the primary and secondary switches, in a first time period, the first switch is turned off, the second switch is turned on, the third switch is turned on, the fourth switch is turned off, the seventh switch is turned off, and the eighth switch is turned on, so that the second switch, the third switch, the transformer, the resonant circuit, the sixth switch, and the eighth switch form a first energy storage circuit, and the first energy storage circuit is used to charge the energy storage element included in the resonant circuit; According to the phase difference between the primary and secondary side switches, the first switch is controlled to be turned off, the second switch is turned on, the third switch is turned on, the fourth switch is turned off, the seventh switch is turned off, and the eighth switch is turned off in a second time period, so that the second switch, the third switch, the transformer, the resonant circuit, the sixth switch, the seventh switch, and the output capacitor form a first charging loop, wherein the first charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage at both ends of the output capacitor, and the second time period is after the first time period in terms of timing.

5. The method according to claim 4, characterized in that The controlling the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the seventh switch tube and the eighth switch tube to the preset switch state according to the phase difference between the primary and secondary switches also includes: According to the phase difference between the primary and secondary switches, in a third time period, the first switch is turned on, the second switch is turned off, the third switch is turned off, the fourth switch is turned on, the seventh switch is turned on, and the eighth switch is turned off, so that the first switch, the fourth switch, the transformer, the resonant circuit, the fifth switch, and the seventh switch form a second energy storage circuit, and the second energy storage circuit is used to charge the energy storage element; According to the phase difference between the primary and secondary side switches, the first switch is controlled to be turned on, the second switch is turned off, the third switch is turned off, the fourth switch is turned on, the seventh switch is turned off, and the eighth switch is turned off in a fourth time period, so that the first switch, the fourth switch, the transformer, the resonant circuit, the fifth switch, the eighth switch, and the output capacitor form a second charging loop, and the second charging loop is used to charge the output capacitor through the energy storage element to boost the output bus voltage at both ends of the output capacitor. The third time period is after the second time period in timing, and the fourth time period is after the third time period in timing.

6. The method according to any one of claims 1 to 5, characterized in that: The voltage conversion circuit further includes an inverter circuit, and the inverter circuit is connected between the open-loop LLC circuit and the power grid. After the switch tube included in the primary full-bridge circuit and the switch tube included in the secondary full-bridge circuit are controlled to a preset switch state, the method further includes: The switch tube included in the inverter circuit is controlled to be turned off so that the switch tube included in the inverter circuit forms a rectifier circuit.

7. The method according to claim 6, characterized in that The method further comprises: When the grid voltage is detected to pass through a zero point, the AC side relay included in the inverter circuit is controlled to close, and the switch tube included in the primary full-bridge circuit and the switch tube included in the secondary full-bridge circuit are controlled to a normal switching state.

8. A grid-connected control device for a voltage conversion circuit, characterized in that: The voltage conversion circuit includes an open-loop LLC circuit, and the open-loop LLC circuit includes a primary full-bridge circuit, a transformer, a resonant circuit, a secondary full-bridge circuit, and an output capacitor connected in sequence. The device includes: A detection module, used for detecting whether the output bus voltage of the voltage conversion circuit is less than the peak voltage of the power grid during the process of the voltage conversion circuit being connected to the power grid; a control module, configured to control the switch tube included in the primary full-bridge circuit and the switch tube included in the secondary full-bridge circuit to a preset switch state when the output bus voltage is less than the peak voltage, so that the primary full-bridge circuit, the transformer, the resonant circuit, the secondary full-bridge circuit and the output capacitor form a boost circuit, and the boost circuit is configured to boost the output bus voltage to be equal to the peak voltage; Wherein, the control module comprises: A determination unit, used to determine a phase difference between the primary and secondary switching tubes according to the peak voltage and the output bus voltage; A control unit is used to control the switch tube included in the primary full-bridge circuit and the switch tube included in the secondary full-bridge circuit to the preset switch state according to the phase difference between the primary and secondary switches.

9. The device according to claim 8, characterized in that The determination unit is specifically used to adjust the output bus voltage using a PI adjustment algorithm to obtain the primary-secondary switch phase difference, wherein the reference voltage in the PI adjustment algorithm is configured as the peak voltage.

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

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