CN220510996U - Voltage conversion circuit, power conversion equipment and energy storage system - Google Patents
Voltage conversion circuit, power conversion equipment and energy storage system Download PDFInfo
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- CN220510996U CN220510996U CN202320146921.3U CN202320146921U CN220510996U CN 220510996 U CN220510996 U CN 220510996U CN 202320146921 U CN202320146921 U CN 202320146921U CN 220510996 U CN220510996 U CN 220510996U
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- 238000004146 energy storage Methods 0.000 title claims abstract description 185
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 63
- 239000003990 capacitor Substances 0.000 claims abstract description 138
- 238000001514 detection method Methods 0.000 claims description 12
- 238000004804 winding Methods 0.000 claims description 12
- 238000007599 discharging Methods 0.000 claims description 9
- 230000007935 neutral effect Effects 0.000 claims description 7
- 230000002457 bidirectional effect Effects 0.000 abstract description 12
- 230000001502 supplementing effect Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000004044 response Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Abstract
The application is applicable to the technical field of electronic circuits and provides a voltage conversion circuit, power conversion equipment and an energy storage system. The voltage conversion circuit is used for setting two energy storage converters on the bus capacitor of the AC/DC converter to charge and discharge the two bus capacitors respectively, the two energy storage converters have a bidirectional voltage conversion function, and can directly utilize the existing energy storage power supply to serve as energy supplementing equipment or energy absorbing equipment required by voltage equalization on the bus capacitor.
Description
Technical Field
The application belongs to the technical field of electronic circuits, and particularly relates to a voltage conversion circuit, power conversion equipment and an energy storage system.
Background
In a three-phase non-isolated photovoltaic grid-connected inverter system, a three-level boost direct current converter is generally adopted as a front-stage boost circuit, and maximum power point tracking (Maximum Power Point Tracking, MPPT) of Photovoltaic (PV) cells is realized. In the three-level Boost direct current converter, the voltages of two capacitors at the direct current output side are required to be balanced, namely, the neutral point potential balance is realized, so that the reliability of the system is improved.
In general, the voltages of the two capacitors at the dc output side of the three-level Boost dc converter are usually large to balance the high voltages at the upper and lower ends, but because the capacitor batches and parameters cannot be completely consistent, and the grid voltages are not completely positive and negative symmetrical, the upper and lower capacitor voltages cannot be completely consistent in practice. It is therefore necessary to add a separate balancing bridge circuit consisting of at least two semiconductor switches and an inductance for balancing, but this way at a slower speed.
Disclosure of Invention
The embodiment of the application provides a voltage conversion circuit, power conversion equipment and an energy storage system, which can solve the problem that the voltage balance speed of two bus capacitors of the voltage conversion circuit in the related technology is low.
A first aspect of an embodiment of the present application provides a voltage conversion circuit, including:
the AC/DC converter is used for performing AC/DC conversion; the DC side of the AC/DC converter is connected with a bus capacitor in parallel to support and balance the voltage of the DC side; the bus capacitor comprises a first capacitor and a second capacitor which are mutually connected in series, and a series node of the first capacitor and the second capacitor is connected with a neutral point of the AC/DC converter;
one end of the first energy storage converter is connected with the first capacitor, and the other end of the first energy storage converter is connected with a first energy storage power supply; the first energy storage converter is used for charging the first capacitor through the first energy storage power supply or charging the first energy storage power supply through electric energy on the first capacitor so as to adjust the voltage on the first capacitor;
one end of the second energy storage converter is connected with the second capacitor, and the other end of the second energy storage converter is connected with a second energy storage power supply; the second energy storage converter is used for charging the second capacitor through the second energy storage power supply or charging the second energy storage power supply through electric energy on the second capacitor so as to adjust the voltage on the second capacitor.
In one embodiment, the method further comprises:
the detection circuit is respectively connected with the first capacitor and the second capacitor and is used for detecting the voltage at two ends of the first capacitor and the voltage at two ends of the second capacitor;
and the control circuit is connected with the detection circuit, the first energy storage converter and the second energy storage converter and is used for adjusting the charging power or the discharging power of at least one of the first energy storage converter and the second energy storage converter according to the voltage difference between the voltage at two ends of the first capacitor and the voltage at two ends of the second capacitor so as to reduce the voltage difference.
In one embodiment, the control circuit is configured to:
when the pressure difference is positive and the first energy storage power supply and the second energy storage power supply are both in a discharge state, controlling the discharge power of the first energy storage converter to be smaller than the discharge power of the second energy storage converter;
and when the differential pressure is positive and the first energy storage power supply and the second energy storage power supply are in a charging state, controlling the charging power of the first energy storage converter to be larger than that of the second energy storage converter.
In one embodiment, the control circuit is further configured to: determining a power difference between the charging power of the first energy storage converter and the charging power of the second energy storage converter according to the differential pressure; or determining a power difference between the discharge power of the first energy storage converter and the discharge power of the second energy storage converter according to the pressure difference; the power difference is in positive correlation with the voltage difference.
In one embodiment, the DC/DC converter further comprises a DC converter connected to the DC side of the AC/DC converter for DC/DC conversion.
In one embodiment, at least one of the first energy storage converter and the second energy storage converter comprises a bi-directional dc conversion circuit.
In one embodiment, the first energy storage converter includes a first power switch, a second power switch, a third power switch, a fourth power switch, a third capacitor, an inductor, a transformer, a fifth power switch, a sixth power switch, a seventh power switch, and an eighth power switch;
the first power switch and the second power switch are connected in series and then connected in parallel with the first capacitor, the third power switch and the fourth power switch are connected in series and then connected in parallel with the first capacitor, the fifth power switch and the sixth power switch are connected in series and then connected in parallel with the first energy storage power supply, and the seventh power switch and the eighth power switch are connected in series and then connected with the first energy storage power supply;
one end of the third capacitor is connected to a series node of the first power switch and the second power switch, the inductor is connected between the other end of the third capacitor and one end of a primary winding of the transformer, and the other end of the primary winding is connected to a series node of the third power switch and the fourth power switch which are connected in series;
one end of a secondary winding of the transformer is connected to a series node of the fifth power switch and the sixth power switch, and the other end of the secondary winding of the transformer is connected to a series node of the seventh power switch and the eighth power switch.
In one embodiment, the AC/DC converter comprises a three-level T-type inverter.
A second aspect of the embodiments of the present application provides a power conversion apparatus, including:
the alternating current interface is used for being connected with an alternating current power supply or an alternating current load; and
a voltage conversion circuit according to any one of claims, wherein an AC side of a three-level AC/DC converter in the voltage conversion circuit is connected to the AC interface; the direct current side of the three-level AC/DC converter is used for being connected with a direct current bus.
A third aspect of the embodiments of the present application provides an energy storage system, including a first energy storage power source and a second energy storage power source, where the energy storage system further includes the voltage conversion circuit described above.
Through the scheme, the two energy storage converters are arranged on the bus capacitor of the AC/DC converter to charge and discharge the two capacitors respectively, and have a bidirectional voltage conversion function, so that the existing energy storage power supply can be directly utilized to serve as energy supplementing equipment or energy absorbing equipment required by voltage equalization on the bus capacitor.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly introduce the drawings that are needed in the embodiments or the description of the prior art, it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a voltage conversion circuit according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a voltage conversion circuit according to an embodiment of the present disclosure;
FIG. 3 is a schematic circuit diagram of a voltage conversion circuit according to an embodiment of the present disclosure;
FIG. 4 is a schematic circuit diagram of an energy storage converter in the voltage conversion circuit shown in FIG. 1;
fig. 5 is a circuit schematic of the energy storage converter in the voltage conversion circuit shown in fig. 1.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As used in this specification and the appended claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
In addition, in the description of the present application and the appended claims, the terms "fifth," "sixth," "seventh," and the like are used merely to distinguish between descriptions and are not to be construed as indicating or implying relative importance.
Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.
Referring to fig. 1, one embodiment of the present application provides a voltage conversion circuit including an AC/DC converter 100, a first energy storage converter 200, and a second energy storage converter 300.
The AC/DC converter 100 is used for performing AC/DC conversion; the DC side of the AC/DC converter 100 is connected in parallel with a bus capacitor to support and equalize the DC side voltage. The bus capacitor comprises a first capacitor C1 and a second capacitor C2 which are connected in series, and a series node of the first capacitor C1 and the second capacitor C2 is connected to a neutral point of the AC/DC converter.
One end of the first energy storage converter 200 is connected to the first capacitor C1, and the other end of the first energy storage converter 200 is connected to the first energy storage power source 10. The first energy storage converter 200 is configured to charge the first capacitor C1 through the first energy storage power supply 10 or charge the first energy storage power supply 10 through the electric energy on the first capacitor C1 to adjust the voltage on the first capacitor C1.
One end of the second energy storage converter 300 is connected to the second capacitor C2, and the other end of the second energy storage converter 300 is connected to the second energy storage power source 20. The second energy storage converter 300 is configured to charge the second capacitor C2 through the second energy storage power supply 20 or charge the second energy storage power supply 20 through the electric energy on the second capacitor C2 to adjust the voltage on the second capacitor C2.
The first energy storage power source 10 and the second energy storage power source 20 on the direct current side of the bidirectional AC/DC converter 100 are both discharged or charged simultaneously. Therefore, for example, the voltage across the first capacitor C1 is higher than the voltage across the second capacitor C2, and if the first energy storage power source 10 and the second energy storage power source 20 are in the discharge state, the discharge power of the first energy storage converter 200 is controlled to be smaller than that of the second energy storage converter 300, so that the voltage balance between the first capacitor C1 and the second capacitor C2 can be quickly achieved. If the first and second energy storage power sources 10 and 20 are in a charged state, the first and second energy storage converters 200 and 300 are controlled to have larger charging power, and the voltage balance between the first and second capacitors C1 and C2 can be rapidly achieved.
Compared with the existing energy storage power supply which is used as energy supplementing equipment or energy absorbing equipment required by voltage equalization on a bus capacitor, compared with the existing energy storage power supply which is independently provided with a balance bridge circuit, the two energy storage converters have the advantages that the voltage balance speed of the first capacitor C1 and the second capacitor C2 is higher due to the arrangement of the first energy storage converter 200 and the second energy storage converter 300, and no extra special energy storage components or power consumption paths are needed, so that the energy utilization rate is improved.
In one embodiment of the present application, the voltage conversion circuit further includes a detection circuit and a control circuit.
The detection circuit is connected with the first capacitor C1 and the second capacitor C2 respectively and is used for detecting the voltage at two ends of the first capacitor C1 and the voltage at two ends of the second capacitor C2. The control circuit is connected to the detection circuit, the first energy storage converter 200 and the second energy storage converter 300, and the control circuit is configured to adjust the charging power or the discharging power of at least one of the first energy storage converter 200 and the second energy storage converter 300 according to the voltage difference between the voltage across the first capacitor C1 and the voltage across the second capacitor C2 so as to reduce the voltage difference.
The detection circuit mainly adopts a comparator for example, and samples and compares voltages at two ends of the first capacitor C1 and the second capacitor C2 respectively to obtain a comparison result, wherein the comparison result represents a voltage difference between the voltages at two ends of the first capacitor C1 and the voltages at two ends of the second capacitor C2. Or the voltage at the two ends of the first capacitor C1 and the second capacitor C2 is sampled by an analog-digital converter and is directly converted to obtain the voltage value of the first capacitor C1 and the voltage value of the second capacitor C2. The control circuit is a microprocessor, such as a singlechip, and performs simple difference operation on the voltage value of the first capacitor C1 and the voltage value of the second capacitor C2 to obtain a differential pressure. The voltage difference may be a simple high or low level, e.g. the voltage across the first capacitor C1 is higher than the voltage across the second capacitor C2, and vice versa. Of course, the actual voltage difference may also be used.
In the operation process of the bidirectional AC/DC converter 100, the process of converting AC into DC (i.e., rectifying) may include a process in which the bidirectional AC/DC converter 100 converts AC input into DC and outputs the DC via a DC bus, and the first energy storage converter 200 and the second energy storage converter 300 charge the first energy storage power source 10 and the second energy storage power source 20 respectively by using electric energy on the DC bus. In the process of converting direct current into alternating current (i.e., inversion), the process of discharging the first energy storage power supply 10 and the second energy storage power supply 20 through the first energy storage converter 200 and the second energy storage converter 300 respectively may be included, so that the voltage on the direct current bus is raised by using the discharge of the first energy storage power supply 10 and the second energy storage power supply 20, and the bidirectional AC/DC converter 100 outputs the target alternating current after performing AC/DC conversion by using the voltage on the direct current bus. In addition, the control circuit can control the difference of the charge and discharge powers of the first energy storage converter 200 and the second energy storage converter 300 according to the voltage difference to realize the voltage balance adjustment of the first capacitor C1 and the second capacitor C2, and the first energy storage converter 200, the second energy storage converter 300, the first energy storage power supply 10 and the second energy storage power supply 20 can all be realized by adopting the existing equipment without independently setting a balance bridge circuit to realize the voltage balance adjustment of the first capacitor C1 and the second capacitor C2, and the voltage balance scheme provided by the embodiment of the application has a higher voltage balance adjustment speed. In this case, the energy storage power supply can be directly controlled to charge or discharge the capacitor, so that the capacitor has a faster adjustment speed compared with the capacitor with a high voltage which needs to be discharged for energy storage in the related technical field and then the energy storage is converted to the capacitor with a low voltage.
It should be noted that, for those skilled in the art, the control of the charge and discharge power (i.e. the rectification and inversion processes) by using a control circuit (such as a microprocessor) to control the energy storage converter is a conventional technical means, and the adjustment of the charge and discharge power is also a relatively conventional means. Specifically, in one of the embodiments, the control circuit is configured to:
when the voltage difference is positive, that is, the voltage at two ends of the first capacitor C1 is greater than the voltage at two ends of the second capacitor C2, and the first energy storage power supply 10 and the second energy storage power supply 20 are both in a discharging state, the discharging power of the first energy storage converter 200 is controlled to be smaller than the discharging power of the second energy storage converter 300, so that the charging rate of the first energy storage converter 200 to the first capacitor C1 is smaller than the charging rate of the second energy storage converter 300 to the second capacitor C2, and the voltage at two ends of the first capacitor C1 and the voltage at two ends of the second capacitor C2 gradually reduce the voltage difference, thereby achieving voltage balance.
When the voltage difference is positive and the first energy storage power supply 10 and the second energy storage power supply 20 are in a charging state, the charging power of the first energy storage converter 200 is controlled to be greater than the charging power of the second energy storage converter 300, so that the discharging rate of the first energy storage converter 200 to the first capacitor C1 is faster than the discharging rate of the second energy storage converter 300 to the second capacitor C2, and the voltage at two ends of the first capacitor C1 and the voltage at two ends of the second capacitor C2 gradually reduce the voltage difference, thereby achieving voltage balance.
Otherwise, when the voltage difference is negative, that is, the voltage across the first capacitor C1 is lower than the voltage across the second capacitor C2, as in the control scheme described above, a person skilled in the art can implement control with reference to the above description, and will not be described herein again.
Optionally, if the detection circuit is capable of detecting a specific difference between the voltage across the first capacitor C1 and the voltage across the second capacitor C2, the control circuit is further configured to: determining a power difference between the charging power of the first energy storage converter 200 and the charging power of the second energy storage converter 300 according to the differential pressure; or determining a power difference between the discharge power of the first energy storage converter 200 and the discharge power of the second energy storage converter 300 according to the pressure difference; the power difference is in positive correlation with the voltage difference, for example, the larger the voltage difference is, the larger the power difference is, so that accurate control of voltage balance is realized quickly.
Referring to fig. 2, in one embodiment, the voltage conversion circuit provided in the present application further includes a DC converter 600 connected to the DC side of the AC/DC converter 100 for DC/DC conversion. The dc converter 600 may be externally connected to a power supply device, such as a photovoltaic panel. The DC converter 600 is, for example, a boost (boost) circuit, boosts the voltage supplied from the photovoltaic panel PV, and supplies the boosted voltage to the AC/DC converter 100.
Referring to fig. 3, the DC converter 600 is a typical boost circuit, which includes a filter capacitor C3, an inductor L1, a power switch S1 and a diode D1, wherein the filter capacitor C3 is connected between the input positive pole and the input negative pole of the DC converter 600, the input positive pole of the DC converter 600 is connected to the first end of the inductor L1, the anode of the diode D1 is connected to the second end of the inductor L1, the cathode of the diode D1 is connected to the DC side of the AC/DC converter 100, and the power switch S1 is connected between the inductor L1 and the input negative pole.
In one embodiment, at least one of the first energy storage converter 200 and the second energy storage converter 300 includes a bi-directional dc conversion circuit. The bidirectional dc conversion circuit may charge and discharge the first energy storage power supply 10 and the second energy storage power supply 20.
Referring to fig. 3, in one embodiment, the AC/DC converter 100 includes a three-level T-type inverter, which includes a three-phase rectifier bridge, inductors L2a, L2b, L2C, inductors L3a, L3b, L3C, capacitors C4, C5, C6, three switching modules Q1C, Q2C, Q3C, and three AC connection terminals e, f, g; the three-phase rectifier bridge comprises power switches Q1a, Q1b, Q2a, Q2b, Q3a and Q3b, wherein the power switches Q1a and Q1b, the power switches Q2a and Q2b and the power switches Q3a and Q3b are respectively connected in series between a positive direct current bus and a negative direct current bus, a series node a of the power switches Q1a and Q1b, a series node b of the power switches Q2a and Q2b and a series node c of the power switches Q3a and Q3b form three alternating current terminals.
The three alternating current terminals a, b and C are respectively connected to an output neutral point o through three switch modules Q1C, Q2C and Q3C, one ends of the inductors L2a, L2b and L2C are respectively connected with the three alternating current terminals a, b and C, the other end of the inductor L2a is connected with one end of the inductor L3a and one end of the capacitor C4, the other end of the inductor L2b is connected with one end of the inductor L3b and one end of the capacitor C5, the other end of the inductor L2C is connected with one end of the inductor L3C and one end of the capacitor C6, the other ends of the inductors L3a, L3b and L3C are respectively connected with three alternating current connecting ends e, f and g, and the capacitors C4, C5 and C6 are respectively connected to the neutral point o. The three ac connection terminals e, f, g are respectively adapted to be connected to one end of an ac power source or an ac load PhA, phB, phC, and the other end of the ac power source or the ac load PhA, phB, phC is respectively connected to the neutral point O.
In one embodiment, the first energy storage converter 200 and the second energy storage converter 300 may be bidirectional dc conversion circuits, as shown in fig. 4. The first energy storage converter 200 is exemplified as a bidirectional dc conversion circuit. The bidirectional direct current conversion circuit comprises a first power switch M1, a second power switch M2, a third power switch M3, a fourth power switch M4, a third capacitor C7, an inductor L4, a transformer T1, a fifth power switch M5, a sixth power switch M6, a seventh power switch M7 and an eighth power switch M8. The first power switch M1 and the second power switch M2 are connected in series and then connected in parallel with the first capacitor C1, the third power switch M3 and the fourth power switch M4 are connected in series and then connected in parallel with the first capacitor C1, the fifth power switch M5 and the sixth power switch M6 are connected in series and then connected in parallel with the first energy storage power supply 10, and the seventh power switch M7 and the eighth power switch M8 are connected in series and then connected in parallel with the first energy storage power supply 10. One end of the third capacitor C7 is connected to a series node of the first power switch M1 and the second power switch M2, the inductor L4 is connected between the other end of the third capacitor C7 and one end of a primary winding of the transformer T1, and the other end of the primary winding is connected to a series node of the third power switch M3 and the fourth power switch M4 which are connected in series; one end of the secondary winding of the transformer T1 is connected to the series node of the fifth power switch M5 and the sixth power switch M6, and the other end of the secondary winding of the transformer T1 is connected to the series node of the seventh power switch M7 and the eighth power switch M8.
Referring to fig. 5, in another embodiment, the bidirectional dc conversion circuit included in the first energy storage converter 200 may be a non-isolated buck-boost converter. The bidirectional direct current conversion circuit comprises power switches M9, M10, M11 and M12 and an inductor L5, wherein the power switches M9 and M10 are connected in series and then connected with a first capacitor C1 in parallel, the power switches M11 and M12 are connected in series and then connected with a first energy storage power supply 10 in parallel, one end of the inductor L5 is connected with a series node of the power switches M9 and M10, and the other end of the inductor L5 is connected with a series node of the power switches M9, M10, M11 and M12.
Referring to fig. 1 to 5, a second aspect of the embodiments of the present application provides a power conversion apparatus, including an ac interface and a voltage conversion circuit:
and the alternating current interface is used for being connected with an alternating current power supply or an alternating current load. The voltage conversion circuit is the voltage conversion circuit provided in any one of the foregoing embodiments, and an AC side of an AC/DC converter in the voltage conversion circuit is connected to an AC interface. The DC side of the AC/DC conversion circuit is used for connection to a DC bus. The direct current bus can be connected with a direct current load or a direct current power supply.
A third aspect of the present embodiment provides an energy storage system, where the energy storage system includes a first energy storage power source 10 and a second energy storage power source 20, and the energy storage system further includes the voltage conversion circuit described above. The first energy storage power source 10 and the second energy storage power source 20 are, for example, two sets of energy storage battery packs, or two independent mobile energy storage devices. The first energy storage power source 10 and the second energy storage power source 20 may be battery packs having only an energy storage function, or may be energy storage devices having a voltage conversion circuit.
In another embodiment, the first energy storage power source 10 may also be integrated with the first energy storage converter 200 in one energy storage device, and the second energy storage power source 20 may also be integrated with the second energy storage converter 300 in one energy storage device. Namely, two energy storage devices with charge and discharge functions are directly connected to the corresponding bus capacitors respectively, so that the balance of voltages on the bus capacitors is realized.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (10)
1. A voltage conversion circuit, comprising:
the AC/DC converter is used for performing AC/DC conversion; a bus capacitor is connected in parallel with the direct current side of the AC/DC converter; the bus capacitor comprises a first capacitor and a second capacitor which are mutually connected in series, and a series node of the first capacitor and the second capacitor is connected with a neutral point of the AC/DC converter;
one end of the first energy storage converter is connected with the first capacitor, and the other end of the first energy storage converter is connected with a first energy storage power supply; the first energy storage converter is used for charging the first capacitor through the first energy storage power supply or charging the first energy storage power supply through electric energy on the first capacitor so as to adjust the voltage on the first capacitor;
one end of the second energy storage converter is connected with the second capacitor, and the other end of the second energy storage converter is connected with a second energy storage power supply; the second energy storage converter is used for charging the second capacitor through the second energy storage power supply or charging the second energy storage power supply through electric energy on the second capacitor so as to adjust the voltage on the second capacitor.
2. The voltage conversion circuit of claim 1, further comprising:
the detection circuit is respectively connected with the first capacitor and the second capacitor and is used for detecting the voltage at two ends of the first capacitor and the voltage at two ends of the second capacitor;
and the control circuit is connected with the detection circuit, the first energy storage converter and the second energy storage converter and is used for adjusting the charging power or the discharging power of at least one of the first energy storage converter and the second energy storage converter according to the voltage difference between the voltage at two ends of the first capacitor and the voltage at two ends of the second capacitor so as to reduce the voltage difference.
3. The voltage conversion circuit according to claim 2, wherein the control circuit is configured to:
when the pressure difference is positive and the first energy storage power supply and the second energy storage power supply are both in a discharge state, controlling the discharge power of the first energy storage converter to be smaller than the discharge power of the second energy storage converter;
and when the differential pressure is positive and the first energy storage power supply and the second energy storage power supply are in a charging state, controlling the charging power of the first energy storage converter to be larger than that of the second energy storage converter.
4. A voltage conversion circuit according to claim 3, wherein the control circuit is further configured to: determining a power difference between the charging power of the first energy storage converter and the charging power of the second energy storage converter according to the differential pressure; or determining a power difference between the discharge power of the first energy storage converter and the discharge power of the second energy storage converter according to the pressure difference; the power difference is in positive correlation with the voltage difference.
5. The voltage conversion circuit according to claim 1, further comprising a DC converter connected to a DC side of the AC/DC converter for DC/DC conversion.
6. The voltage conversion circuit of claim 1, wherein at least one of the first energy storage converter and the second energy storage converter comprises a bi-directional dc conversion circuit.
7. The voltage conversion circuit of claim 6, wherein the first energy storage converter comprises a first power switch, a second power switch, a third power switch, a fourth power switch, a third capacitor, an inductor, a transformer, a fifth power switch, a sixth power switch, a seventh power switch, and an eighth power switch;
the first power switch and the second power switch are connected in series and then connected in parallel with the first capacitor, the third power switch and the fourth power switch are connected in series and then connected in parallel with the first capacitor, the fifth power switch and the sixth power switch are connected in series and then connected in parallel with the first energy storage power supply, and the seventh power switch and the eighth power switch are connected in series and then connected in parallel with the first energy storage power supply;
one end of the third capacitor is connected to a series node of the first power switch and the second power switch, the inductor is connected between the other end of the third capacitor and one end of a primary winding of the transformer, and the other end of the primary winding is connected to a series node of the third power switch and the fourth power switch which are connected in series;
one end of a secondary winding of the transformer is connected to a series node of the fifth power switch and the sixth power switch, and the other end of the secondary winding of the transformer is connected to a series node of the seventh power switch and the eighth power switch.
8. The voltage conversion circuit according to any one of claims 1 to 5, wherein the AC/DC converter includes a three-level T-type inverter.
9. A power conversion apparatus, comprising:
the alternating current interface is used for being connected with an alternating current power supply or an alternating current load; and
a voltage conversion circuit as claimed in any one of claims 1 to 8, an AC side of an AC/DC converter in the voltage conversion circuit being connected to the AC interface; the DC side of the AC/DC converter is used for being connected with a DC bus.
10. An energy storage system comprising a first energy storage power source and a second energy storage power source, wherein the energy storage system further comprises a voltage conversion circuit according to any one of claims 1-8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320146921.3U CN220510996U (en) | 2023-01-12 | 2023-01-12 | Voltage conversion circuit, power conversion equipment and energy storage system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320146921.3U CN220510996U (en) | 2023-01-12 | 2023-01-12 | Voltage conversion circuit, power conversion equipment and energy storage system |
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