Energy storage conversion circuit and working method thereof

Abstract

An energy storage conversion circuit and a working method thereof include: three phase conversion circuits, each conversion circuit also includes a first switch module and a second switch module, the first switch module is used to output a first output current according to a first switching frequency, the second switch module is used to output a second output current according to a second switching frequency, the first switching frequency is less than the second switching frequency, and the output end of the conversion circuit is used to output a third output current, which is the sum of the first output current and the second output current. The first switch module and the second switch module are controlled by different switching frequencies, so that the power consumption of the first switch module is reduced at a low switching frequency, while ensuring the dynamic performance of the second switch module at a high switching frequency, thereby improving the performance of the energy storage conversion circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical automation equipment, and in particular to an energy storage conversion circuit and a working method thereof. Background Art

[0002] As the interface between distributed power generation systems, energy storage systems and the power grid, the converter plays a key role in the mutual conversion of different forms of energy. Its working efficiency and dynamic performance are the main indicators of concern. Traditional energy storage converters are usually single-stage and bipolar. Single-stage energy storage converters only need to undergo one power conversion, with a simple circuit and relatively small losses. They are the first choice for high-power centralized new energy power station converters. For the design of high-power converters, there are three main considerations: on the one hand, to improve efficiency, this can be achieved by reducing the switching frequency of the power tube, that is, reducing the loss of the power tube; on the other hand, in order to dissipate heat, a large and heavy heat sink is required to assist, which also requires reducing the loss of the power tube; and finally, to improve the dynamic performance of the equipment, it is necessary to increase the switching frequency of the power tube to increase the control bandwidth of the equipment.

[0003] At present, for centralized high-power converters, the switching frequency is a compromise. If it is too high, the switching loss of the power device will be too high, not only the equipment efficiency will be reduced, but also the heat dissipation of the equipment will become a problem, especially for outdoor units, which are more difficult to dissipate heat in a relatively closed environment; if the switching frequency is too low, it will lead to insufficient grid-connected performance, such as low grid stability and robustness, weak grids are prone to resonance, such as large grid current harmonic content, unable to meet grid harmonic requirements, and too low equipment dynamic performance, unable to meet indicators such as fault ride-through and power fast switching, reducing the performance of the energy storage conversion circuit.

[0004] Therefore, the existing energy storage conversion circuit still has many problems. Summary of the invention

[0005] The technical problem solved by the present invention is to provide an energy storage conversion circuit and a working method thereof, which can reduce the power consumption of the energy storage conversion circuit and improve the performance of the energy storage conversion circuit.

[0006] To solve the above technical problems, an embodiment of the present invention provides an energy storage conversion circuit, including: three phase conversion circuits, each phase conversion circuit includes a first input terminal, a second input terminal and an output terminal, the first input terminals of each phase conversion circuit are connected, and the second input terminals of each phase conversion circuit are connected, each of the conversion circuits also includes a first switch module and a second switch module, the first switch module is used to output a first output current according to a first switching frequency, and the second switch module is used to output a second output current according to a second switching frequency, the first switching frequency is less than the second switching frequency, and the output terminal of the conversion circuit is used to output a third output current, and the third output current is the sum of the first output current and the second output current; a DC input port, the DC input port is connected to the first input terminal and the second input terminal of each phase conversion circuit; an AC output port, the AC output port is connected to the output terminal of each phase conversion circuit.

[0007] Optionally, the first switch module includes a first switch unit and a second switch unit, each of which includes a first end, a second end and a control end, the first end of the first switch unit is connected to the DC input port, the second end of the first switch unit is respectively connected to the first end of the second switch unit and the second switch module, the second end of the second switch unit is connected to the DC input port, the first switch unit and the second switch unit are used to be turned on or off according to the first switching frequency, and the turn-on time of the first switch unit and the second switch unit are complementary.

[0008] Optionally, the first switch unit includes a plurality of first switch tubes connected in parallel, and the second switch unit includes a plurality of second switch tubes connected in parallel, and the number of the first switch tubes is the same as the number of the second switch tubes.

[0009] Optionally, the first switch module further includes a first inductor, a first end of the first inductor is connected to an output end of the first switch module, and a second end of the first inductor is connected to an output end of the second switch module.

[0010] Optionally, the second switch module includes a third switch unit and a fourth switch unit, each of the third switch unit and the fourth switch unit includes a first end, a second end and a control end, the first end of the third switch unit is connected to the first end of the first switch unit, the second end of the third switch unit is respectively connected to the first end of the fourth switch unit and the AC output port, the second end of the fourth switch unit is connected to the second end of the second switch unit, the third switch unit and the fourth switch unit are used to be turned on or off according to the second switching frequency, and the conduction time of the third switch unit and the fourth switch unit are complementary.

[0011] Optionally, the third switch unit includes a third switch tube, and the fourth switch unit includes a fourth switch tube.

[0012] Optionally, the DC input port includes a bus positive voltage terminal, a bus negative voltage terminal and a first capacitor, and the first capacitor is connected between the bus positive voltage terminal and the bus negative voltage terminal.

[0013] Optionally, the AC output port includes three filter modules connected in parallel, and each of the filter modules is connected to an output end of the phase conversion circuit.

[0014] Optionally, the three filtering modules all include a second inductor and a second capacitor connected in parallel.

[0015] Optionally, the energy storage conversion circuit also includes: a control module, which is used to: apply a first switching frequency to the first switching module so that the first output current at the output end of the conversion circuit reaches a first preset threshold; apply a second switching frequency to the second switching module so that the third output current at the output end of the conversion circuit reaches a second preset threshold.

[0016] Optionally, the control module is further used to: adjust the duty cycle of the first switch module according to the first output current and the first preset threshold; and adjust the duty cycle of the second switch module according to the third output current and the second preset threshold.

[0017] Optionally, the control module is also used to: when the first output current is less than a first preset threshold, apply a first level to the first switch unit so that the first switch unit is turned on; when the third output current is less than a second preset threshold, apply a second level to the third switch unit so that the third switch unit is turned off.

[0018] Optionally, the control module is also used to: when the first output current is greater than a first preset threshold, apply a first level to the second switch unit so that the second switch unit is turned on; when the third output current is greater than a second preset threshold, apply a first level to the third switch unit so that the third switch unit is turned on.

[0019] Optionally, the control module is also used to: when the first output current is equal to a first preset threshold, apply a first level to the first switch unit so that the first switch unit is turned on; when the third output current is equal to a second preset threshold, apply a first level to the third switch unit so that the third switch unit is turned on.

[0020] Optionally, the control module is also used to: when the first output current is equal to a first preset threshold, apply a first level to the second switch unit so that the second switch unit is turned on; when the third output current is equal to a second preset threshold, apply a first level to the fourth switch unit so that the fourth switch unit is turned on.

[0021] Correspondingly, the technical solution of the present invention also provides a working method of an energy storage conversion circuit, including: applying a first switching frequency to a first switching module so that a first output current at the output end of the conversion circuit reaches a first preset threshold; applying a second switching frequency to a second switching module so that a third output current at the output end of the conversion circuit reaches a second preset threshold.

[0022] Optionally, the working method of the energy storage conversion circuit also includes: adjusting the duty cycle of the first switch module according to the first output current and the first preset threshold; adjusting the duty cycle of the second switch module according to the third output current and the second preset threshold.

[0023] Optionally, adjusting the duty cycle of the first switch module and the second switch module includes: when the first output current is less than a first preset threshold, applying a first level to the first switch unit so that the first switch unit is turned on; when the third output current is less than a second preset threshold, applying a second level to the third switch unit so that the third switch unit is turned off.

[0024] Optionally, adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is greater than a first preset threshold, applying a first level to the second switch unit so that the second switch unit is turned on; when the third output current is greater than a second preset threshold, applying a first level to the third switch unit so that the third switch unit is turned on.

[0025] Optionally, adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is equal to a first preset threshold, applying a first level to the first switch unit so that the first switch unit is turned on; when the third output current is equal to a second preset threshold, applying a first level to the third switch unit so that the third switch unit is turned on.

[0026] Optionally, adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is equal to a first preset threshold, applying a first level to the second switch unit so that the second switch unit is turned on; when the third output current is equal to a second preset threshold, applying a first level to the fourth switch unit so that the fourth switch unit is turned on.

[0027] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0028] The energy storage conversion circuit provided by the technical solution of the present invention divides each phase conversion circuit into a first switch module and a second switch module, and controls the first switch module and the second switch module by different switching frequencies, so that the power consumption of the first switch module is reduced at a low switching frequency, while ensuring the dynamic performance of the second switch module at a high switching frequency, thereby improving the performance of the energy storage conversion circuit; and at different switching frequencies, the output currents of the first switch module and the second switch module are different, thereby increasing the third output current of the energy storage conversion circuit, ensuring the large current output capability of the energy storage conversion circuit, and further improving the performance of the energy storage conversion circuit.

[0029] Furthermore, in the energy storage conversion circuit provided by the technical solution of the present invention, the first switch module includes a first switch unit and a second switch unit, and the second switch module includes a third switch unit and a fourth switch unit. By controlling the complementary conduction of the first switch unit and the second switch unit and the complementary conduction of the third switch unit and the fourth switch unit, flexible adjustment of the third output current of the energy storage conversion circuit is achieved, thereby improving the accuracy of the third output current of the energy storage conversion circuit.

[0030] Furthermore, in the energy storage conversion circuit provided by the technical solution of the present invention, a first inductor is connected to the first switch module, and the characteristic that the current in the inductor cannot change suddenly is utilized, so that the first output current output by the first switch module is continuous and the stability of the output current is guaranteed.

[0031] The working method of the energy storage conversion circuit provided by the technical solution of the present invention controls the first switch module and the second switch module by different switching frequencies, so that the power consumption of the first switch module is reduced at a low switching frequency, while ensuring the dynamic performance of the second switch module at a high switching frequency, thereby improving the performance of the energy storage conversion circuit; and at different switching frequencies, the output currents of the first switch module and the second switch module are different, thereby increasing the third output current of the energy storage conversion circuit, ensuring the large current output capability of the energy storage conversion circuit, and further improving the performance of the energy storage conversion circuit.

[0032] Furthermore, the working method of the energy storage conversion circuit provided by the technical solution of the present invention realizes flexible adjustment of the third output current of the energy storage conversion circuit by controlling the complementary conduction of the first switch unit and the second switch unit and the complementary conduction of the third switch unit and the fourth switch unit, thereby improving the accuracy of the third output current of the energy storage conversion circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of an energy storage conversion circuit;

[0034] Figure 2 is a schematic structural diagram of an energy storage conversion circuit in one embodiment of the present invention;

[0035] Figure 3 The structure of a phase conversion circuit in an energy storage conversion circuit in an embodiment of the present invention is shown in FIG. Figure 1 ;

[0036] Figure 4 The structure of a phase conversion circuit in an energy storage conversion circuit in an embodiment of the present invention is shown in FIG. Figure 2 . DETAILED DESCRIPTION

[0037] As can be seen from the background technology, the energy storage conversion circuit in the prior art has the problems of high power tube loss and low dynamic performance of the equipment. Now, the reasons are analyzed in combination with the detection method of the existing energy storage conversion circuit:

[0038] Figure 1 The present invention is a structural schematic diagram of the energy storage conversion circuit.

[0039] Please refer to Figure 1 , Figure 1 Only the structure of one phase conversion circuit in the energy storage conversion circuit is shown, and the energy storage conversion circuit includes: a plurality of phase conversion circuits 6, each of the phase conversion circuits 6 includes a first input terminal, a second input terminal and an output terminal, the first input terminals of the phase conversion circuits 6 are connected, the second input terminals of the phase conversion circuits 6 are connected, and each of the phase conversion circuits 6 includes two switching tubes; a DC input port 5, the DC input port 5 is connected to the input terminals of the plurality of phase conversion circuits 6; an AC output port 7, the AC output port 7 is connected to the output terminals of the plurality of phase conversion circuits 6.

[0040] In the above scheme, the switching frequency of the switch module adopts a compromise selection, that is, a unified opening frequency is used to control the phase conversion circuit, so that the switch module loss and dynamic performance are at medium values, but the above scheme still has the problem of high switch module loss and low dynamic performance.

[0041] In order to solve the above technical problems, the technical solution of the present invention provides an energy storage conversion circuit and a working method thereof, which divides each phase conversion circuit into a first switch module and a second switch module, and controls the first switch module and the second switch module by different switching frequencies, so that the power consumption of the first switch module is reduced at a low switching frequency, while ensuring the dynamic performance of the second switch module at a high switching frequency, thereby improving the performance of the energy storage conversion circuit; and at different switching frequencies, the output currents of the first switch module and the second switch module are different, thereby increasing the third output current of the energy storage conversion circuit, ensuring the large current output capacity of the energy storage conversion circuit, and further improving the performance of the energy storage conversion circuit.

[0042] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] Figure 2 It is a schematic diagram of the structure of an energy storage conversion circuit in one embodiment of the present invention.

[0044] Please refer to Figure 2 The energy storage conversion circuit includes: three phase conversion circuits 2, each phase conversion circuit 2 includes a first input end, a second input end and an output end, the first input ends of each phase conversion circuit 2 are connected, and the second input ends of each phase conversion circuit 2 are connected.

[0045] Figure 3 The structure of a phase conversion circuit in an energy storage conversion circuit in an embodiment of the present invention is shown in FIG. Figure 1 .

[0046] Please refer to Figure 3 Each of the conversion circuits further includes a first switch module 201 and a second switch module 202; a DC input port 1, wherein the DC input port 1 is connected to the first input terminal and the second input terminal of each phase conversion circuit 2; and an AC output port 3, wherein the AC output port 3 is connected to the output terminal of each phase conversion circuit 2.

[0047] The first switch module 201 is configured to output a first output current I1 according to a first switching frequency.

[0048] The second switch module 202 is used to output a second output current I2 according to a second switching frequency, the first switching frequency is less than the second switching frequency, and the output end of the conversion circuit is used to output a third output current I3, and the third output current I3 is the sum of the first output current I1 and the second output current I2.

[0049] The first switching frequency ranges from 500 Hz to 1500 Hz, and the second switching frequency ranges from 5000 Hz to 10000 Hz.

[0050] The first switch module 201 includes a first switch unit 2011 and a second switch unit 2012, each of which includes a first end, a second end and a control end. The first end of the first switch unit 2011 is connected to the DC input port 1, the second end of the first switch unit 2011 is respectively connected to the first end of the second switch unit 2012 and the AC output port 3, the second end of the second switch unit 2012 is connected to the DC input port 1, the first switch unit 2011 and the second switch unit 2012 are used to be turned on or off according to the first switching frequency, and the turn-on time of the first switch unit 2011 and the second switch unit 2012 are complementary.

[0051] The purpose of the first switch module 201 is to reduce the switching frequency to reduce the loss of the switch tube, improve efficiency and reduce the design requirements of the heat sink of the device; the purpose of the second switch module 202 is to increase the control frequency of the energy storage conversion circuit to increase the bandwidth of the entire device. The third output current I3 finally obtained is a high-frequency large current, which has both high-frequency dynamic performance and can ensure the output capacity of large current.

[0052] The second switch module 202 includes a third switch unit 2021 and a fourth switch unit 2022, and the third switch unit 2021 and the fourth switch unit 2022 each include a first end, a second end and a control end. The first end of the third switch unit 2021 is connected to the first end of the first switch unit 2011, the second end of the third switch unit 2021 is respectively connected to the first end of the fourth switch unit 2022 and the AC output port 3, the second end of the fourth switch unit 2022 is connected to the second end of the second switch unit 2012, the third switch unit 2021 and the fourth switch unit 2022 are used to be turned on or off according to the second switching frequency, and the conduction time of the third switch unit 2021 and the fourth switch unit 2022 are complementary.

[0053] In the above scheme, each phase conversion circuit 2 is divided into a first switch module 201 and a second switch module 202, and the first switch module 201 and the second switch module 202 are controlled by different switching frequencies, so that the power consumption of the first switch module 201 is reduced at a low switching frequency, while ensuring the dynamic performance of the second switch module 202 at a high switching frequency, thereby improving the performance of the energy storage conversion circuit; and at different switching frequencies, the output currents of the first switch module 201 and the second switch module 202 are different, thereby increasing the third output current I3 of the energy storage conversion circuit, ensuring the large current output capability of the energy storage conversion circuit, and further improving the performance of the energy storage conversion circuit.

[0054] In this embodiment, the DC input port 1 includes a bus positive voltage terminal +, a bus negative voltage terminal -, and a first capacitor 101, and the first capacitor 101 is connected between the bus positive voltage terminal + and the bus negative voltage terminal -.

[0055] In this embodiment, the AC output port 3 includes three filter modules 301 connected in parallel, and each of the filter modules 301 is connected to an output end of the phase conversion circuit 2 .

[0056] In the above scheme, the first switch module 201 includes a first switch unit 2011 and a second switch unit 2012, and the second switch module 202 includes a third switch unit 2021 and a fourth switch unit 2022. By controlling the complementary conduction of the first switch unit 2011 and the second switch unit 2012 and the complementary conduction of the third switch unit 2021 and the fourth switch unit 2022, flexible adjustment of the third output current I3 of the energy storage conversion circuit is achieved, thereby improving the accuracy of the third output current I3 of the energy storage conversion circuit.

[0057] Figure 4 The structure of a phase conversion circuit in an energy storage conversion circuit in an embodiment of the present invention is shown in FIG. Figure 2 .

[0058] Please refer to Figure 4 The first switch unit 2011 includes a plurality of first switch tubes T1 connected in parallel, the second switch unit 2012 includes a plurality of second switch tubes T2 connected in parallel; the third switch unit 2021 includes a third switch tube T3, and the fourth switch unit 2022 includes a fourth switch tube T4.

[0059] The number of the first switch tubes T1 is the same as the number of the second switch tubes T2.

[0060] The filtering module 301 includes a second inductor 3011 and a second capacitor 3012 connected in parallel.

[0061] The on-times of the first switch tube T1 and the second switch tube T2 are complementary, and the on-times of the third switch tube T3 and the fourth switch tube T4 are complementary.

[0062] The first switch tube T1 is used to increase the first output current I1, and the second switch tube T2 is used to reduce the first output current I1.

[0063] In this embodiment, the first switch tube T1 and the second switch tube T2 include IGBTs, and the third switch tube T3 and the fourth switch tube T4 include MOS tubes.

[0064] Of course, the present invention is not limited to this. Different types of switch tubes are selected according to the actual needs of the energy storage conversion circuit to give full play to the large current characteristics and high frequency characteristics of different switch tubes.

[0065] In this embodiment, the first switch module 201 further includes a first inductor 2013 , a first end of the first inductor 2013 is connected to an output end of the first switch module 201 , and a second end of the first inductor 2013 is connected to an output end of the second switch module 202 .

[0066] Among them, I1=K*I, I3=I1+I2, wherein I1 is the first output current I1, I2 is the second output current I2, I3 is the third output current I3, K is a fixed ratio, and I is a second preset threshold.

[0067] In a specific embodiment, when the first output current I1 is less than K*I, the first switch tube T1 is turned on and the third switch tube T3 is turned off, then the current of the second output current I2 will flow through the freewheeling diode of the fourth switch tube T4. At this time, regardless of whether the fourth switch tube T4 is turned on or not, the voltage across the first inductor 2013 is the bus voltage, and the first output current I1 increases; when the first output current I1 is equal to K*I, the first switch tube T1 and the third switch tube T3 are turned on or the second switch tube T2 and the fourth switch tube T4 are turned on, then the output end of the third output current I3 will automatically extract a current of about K*I from a position lower than the first output current I1, and the remaining current (i.e., the second output current I2) flows out from the third switch tube T3. At this time, since the voltage across the first switch tube T1 is 0V, the magnitude of the first output current I1 remains unchanged; when the first output current I1 is greater than K*I, the second switch tube T2 and the third switch tube T3 are turned on, and the first output current I1 decreases.

[0068] In this embodiment, K is 0.9 or 0.95.

[0069] In the above scheme, the control target of the first switch module 201 is the first output current I1, and the first output current I1 is controlled to be slightly smaller than the third output current I3, for example, I1=K*I (K=0.95). Since the control frequency of the power tube is relatively low, the current waveform of the first output current I1 will be a sinusoidal quantity with obvious upper and lower waveforms, containing a large number of harmonics, which cannot meet the grid connection requirements; the control target of the second switch module 202 is the voltage of the AC output port 3, and the third switch tube T3 and the fourth switch tube T4 are designed based on the area equivalence principle, that is, the two switch tubes of the second switch module 202 control the output characteristics of the phase conversion circuit 2 to be voltage-controlled.

[0070] In addition, the first inductor 2013 is connected to the first switch module 201, and the characteristic that the current on the inductor cannot change suddenly is utilized, so that the first output current I1 output by the first switch module 201 is continuous and the stability of the output current is guaranteed.

[0071] The energy storage conversion circuit includes: a control module 4, which is used to: apply a first switching frequency to the first switching module 201 so that the first output current I1 at the output end of the conversion circuit reaches a first preset threshold; apply a second switching frequency to the second switching module 202 so that the third output current I3 at the output end of the conversion circuit reaches a second preset threshold.

[0072] The first preset threshold is K*I, the second preset threshold is I, and the value of K includes 0.9 or 0.95. The control module 4 is also used to: adjust the duty cycle of the first switch module 201 according to the first output current I1 and the first preset threshold K*I; adjust the duty cycle of the second switch module 202 according to the third output current I3 and the second preset threshold I.

[0073] The control module 4 is also used for: when the first output current I1 is less than a first preset threshold value K*I, applying a first level to the first switch unit 2011 so that the first switch unit 2011 is turned on; when the third output current I3 is less than a second preset threshold value I, applying a second level to the third switch unit 2021 so that the third switch unit 2021 is turned off.

[0074] The control module 4 is also used for: when the first output current I1 is greater than the first preset threshold value K*I, applying the first level to the second switch unit 2012 so that the second switch unit 2012 is turned on; when the third output current I3 is greater than the second preset threshold value I, applying the first level to the third switch unit 2021 so that the third switch unit 2021 is turned on.

[0075] The control module 4 is also used for: when the first output current I1 is equal to the first preset threshold value K*I, applying the first level to the first switch unit 2011 so that the first switch unit 2011 is turned on; when the third output current I3 is equal to the second preset threshold value I, applying the first level to the third switch unit 2021 so that the third switch unit 2021 is turned on.

[0076] The control module 4 is also used for: when the first output current I1 is equal to the first preset threshold value K*I, applying the first level to the second switch unit 2012 so that the second switch unit 2012 is turned on; when the third output current I3 is equal to the second preset threshold value I, applying the first level to the fourth switch unit 2022 so that the fourth switch unit 2022 is turned on.

[0077] Please continue to refer to Figure 4 The technical solution of the present invention also provides a working method of an energy storage conversion circuit, including: applying a first switching frequency to the first switching module 201, so that the first output current I1 at the output end of the conversion circuit reaches a first preset threshold; applying a second switching frequency to the second switching module 202, so that the third output current I3 at the output end of the conversion circuit reaches a second preset threshold.

[0078] The first preset threshold is K*I, the second preset threshold is I, and the value of K includes 0.9 or 0.95.

[0079] In this embodiment, the working method of the energy storage conversion circuit also includes: adjusting the duty cycle of the first switch module 201 according to the first output current I1 and the first preset threshold K*I; adjusting the duty cycle of the second switch module 202 according to the third output current I3 and the second preset threshold I.

[0080] In this embodiment, adjusting the duty cycle of the first switch module 201 and the second switch module 202 includes: when the first output current I1 is less than the first preset threshold value K*I, applying a first level to the first switch unit 2011 so that the first switch unit 2011 is turned on; when the third output current I3 is less than the second preset threshold value I, applying a second level to the third switch unit 2021 so that the third switch unit 2021 is turned off.

[0081] In this embodiment, adjusting the duty cycle of the first switch module 201 and the second switch module 202 also includes: when the first output current I1 is greater than the first preset threshold value K*I, applying a first level to the second switch unit 2012 so that the second switch unit 2012 is turned on; when the third output current I3 is greater than the second preset threshold value I, applying a first level to the third switch unit 2021 so that the third switch unit 2021 is turned on.

[0082] In this embodiment, adjusting the duty cycle of the first switch module 201 and the second switch module 202 also includes: when the first output current I1 is equal to the first preset threshold value K*I, applying a first level to the first switch unit 2011 so that the first switch unit 2011 is turned on; when the third output current I3 is equal to the second preset threshold value I, applying a first level to the third switch unit 2021 so that the third switch unit 2021 is turned on.

[0083] In this embodiment, adjusting the duty cycle of the first switch module 201 and the second switch module 202 also includes: when the first output current I1 is equal to the first preset threshold value K*I, applying a first level to the second switch unit 2012 so that the second switch unit 2012 is turned on; when the third output current I3 is equal to the second preset threshold value I, applying a first level to the fourth switch unit 2022 so that the fourth switch unit 2022 is turned on.

[0084] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An energy storage conversion circuit, characterized in that: include: Three phase conversion circuits, each phase conversion circuit comprises a first input terminal, a second input terminal and an output terminal, the first input terminals of each phase conversion circuit are connected, the second input terminals of each phase conversion circuit are connected, each of the conversion circuits further comprises a first switch module and a second switch module, the first switch module is used to output a first output current according to a first switching frequency, the second switch module is used to output a second output current according to a second switching frequency, the first switching frequency is less than the second switching frequency, the output terminal of the conversion circuit is used to output a third output current, and the third output current is the sum of the first output current and the second output current; A DC input port, the DC input port being connected to the first input terminal and the second input terminal of each phase conversion circuit; An AC output port, the AC output port being connected to an output end of each phase conversion circuit; Wherein, the first switch module includes a first switch unit and a second switch unit, each of the first switch unit and the second switch unit includes a first end, a second end and a control end, the first end of the first switch unit is connected to the DC input port, the second end of the first switch unit is respectively connected to the first end of the second switch unit and the second switch module, and the second end of the second switch unit is connected to the DC input port; The second switch module includes a third switch unit and a fourth switch unit, each of which includes a first end, a second end and a control end, the first end of the third switch unit is connected to the first end of the first switch unit, the second end of the third switch unit is respectively connected to the first end of the fourth switch unit and the AC output port, and the second end of the fourth switch unit is connected to the second end of the second switch unit.

2. The energy storage conversion circuit according to claim 1, characterized in that: The first switch unit and the second switch unit are used to be turned on or off according to the first switch frequency, and the turn-on time of the first switch unit and the turn-on time of the second switch unit are complementary.

3. The energy storage conversion circuit according to claim 2, characterized in that: The first switch unit includes a plurality of first switch tubes connected in parallel, and the second switch unit includes a plurality of second switch tubes connected in parallel. The number of the first switch tubes is the same as the number of the second switch tubes.

4. The energy storage conversion circuit according to claim 2, characterized in that: The first switch module further includes a first inductor, a first end of the first inductor is connected to an output end of the first switch module, and a second end of the first inductor is connected to an output end of the second switch module.

5. The energy storage conversion circuit according to claim 4, characterized in that: The third switch unit and the fourth switch unit are used to be turned on or off according to the second switching frequency, and the turn-on time of the third switch unit and the turn-on time of the fourth switch unit are complementary.

6. The energy storage conversion circuit according to claim 5, characterized in that: The third switch unit includes a third switch tube, and the fourth switch unit includes a fourth switch tube.

7. The energy storage conversion circuit according to claim 1, characterized in that: The DC input port includes a bus positive voltage terminal, a bus negative voltage terminal and a first capacitor, and the first capacitor is connected between the bus positive voltage terminal and the bus negative voltage terminal.

8. The energy storage conversion circuit according to claim 1, characterized in that: The AC output port includes three filter modules connected in parallel, and each of the filter modules is connected to an output end of the phase conversion circuit.

9. The energy storage conversion circuit according to claim 8, characterized in that: The three filter modules all include a second inductor and a second capacitor connected in parallel.

10. The energy storage conversion circuit according to claim 6, characterized in that: Also includes: A control module, the control module is connected to the control ends of the first switch unit, the second switch unit, the third switch unit and the fourth switch unit respectively, and the control module is used to: apply a first switching frequency to the first switch module so that a first output current at the output end of the conversion circuit reaches a first preset threshold; A second switching frequency is applied to the second switching module so that a third output current at the output end of the conversion circuit reaches a second preset threshold.

11. The energy storage conversion circuit according to claim 10, characterized in that: The control module is further used to: adjust the duty cycle of the first switch module according to the first output current and the first preset threshold; and adjust the duty cycle of the second switch module according to the third output current and the second preset threshold.

12. The energy storage conversion circuit according to claim 11, characterized in that: The control module is also used to: when the first output current is less than a first preset threshold, apply a first level to the first switch unit so that the first switch unit is turned on; when the third output current is less than a second preset threshold, apply a second level to the third switch unit so that the third switch unit is turned off.

13. The energy storage conversion circuit according to claim 12, characterized in that: The control module is also used to: when the first output current is greater than a first preset threshold, apply a first level to the second switch unit so that the second switch unit is turned on; when the third output current is greater than a second preset threshold, apply a first level to the third switch unit so that the third switch unit is turned on.

14. The energy storage conversion circuit according to claim 13, characterized in that: The control module is also used to: when the first output current is equal to a first preset threshold, apply a first level to the first switch unit so that the first switch unit is turned on; when the third output current is equal to a second preset threshold, apply a first level to the third switch unit so that the third switch unit is turned on.

15. The energy storage conversion circuit according to claim 14, characterized in that: The control module is also used to: when the first output current is equal to a first preset threshold, apply a first level to the second switch unit so that the second switch unit is turned on; when the third output current is equal to a second preset threshold, apply a first level to the fourth switch unit so that the fourth switch unit is turned on.

16. A working method of the energy storage conversion circuit according to any one of claims 10 to 15, characterized in that: include: Applying a first switching frequency to the first switching module so that a first output current at an output end of the conversion circuit reaches a first preset threshold; A second switching frequency is applied to the second switching module so that a third output current at the output end of the conversion circuit reaches a second preset threshold.

17. The working method of the energy storage conversion circuit according to claim 16, characterized in that: Also includes: adjusting a duty cycle of the first switch module according to the first output current and the first preset threshold; The duty cycle of the second switch module is adjusted according to the third output current and the second preset threshold.

18. The working method of the energy storage conversion circuit according to claim 17, characterized in that: Adjusting the duty cycle of the first switch module and the second switch module includes: when the first output current is less than a first preset threshold, applying a first level to the first switch unit so that the first switch unit is turned on; when the third output current is less than a second preset threshold, applying a second level to the third switch unit so that the third switch unit is turned off.

19. The working method of the energy storage conversion circuit according to claim 17, characterized in that: Adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is greater than a first preset threshold, applying a first level to the second switch unit so that the second switch unit is turned on; when the third output current is greater than a second preset threshold, applying a first level to the third switch unit so that the third switch unit is turned on.

20. The working method of the energy storage conversion circuit according to claim 17, characterized in that: Adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is equal to a first preset threshold, applying a first level to the first switch unit so that the first switch unit is turned on; when the third output current is equal to a second preset threshold, applying a first level to the third switch unit so that the third switch unit is turned on.

21. The working method of the energy storage conversion circuit according to claim 17, characterized in that: Adjusting the duty cycle of the first switch module and the second switch module also includes: when the first output current is equal to a first preset threshold, applying a first level to the second switch unit so that the second switch unit is turned on; when the third output current is equal to a second preset threshold, applying a first level to the fourth switch unit so that the fourth switch unit is turned on.

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