Power transmission system and power generation system

Abstract

Embodiments of the present application provide a power transmission system and a power generation system. The power transmission system comprises: a power conversion circuit for performing power conversion on an inputted electrical signal; a filter circuit comprising a first filter circuit and a second filter circuit, the first filter circuit being coupled between an input end of the power transmission system and an input end of the power conversion circuit, and the second filter circuit being coupled between an output end of the power conversion circuit and an output end of the power transmission system; and at least one shunt capacitor bank, one end of the shunt capacitor bank being coupled to the input end of the power transmission system, and the other end of the shunt capacitor bank being coupled to the output end of the power transmission system to form a loop, allowing an interference signal in an electrical signal outputted by the output end of the power conversion circuit to flow back to the input end of the power conversion circuit. According to the embodiments of the present application, the interference signal is allowed to flow back, which reduces the common-mode interference current at the input end and / or the output end without using a safety Y capacitor, making it possible to reduce the volume of a filter inductor, and reducing costs.

Description

Power transmission system and power generation system

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on December 19, 2023, with application number 202311760323.6 and application name “A Power Transmission System and Power Generation System”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of filtering technology, and in particular to a power transmission system and a power generation system. Background Art

[0003] Due to the large number of strings used in power optimizer products, the voltage to ground of the cables connecting the strings after multiple series connections can reach over 500V. Common-mode filtering requires the use of safety-compliant Y-capacitors on the chassis for filtering. Furthermore, current electromagnetic compatibility (EMC) standards require all ports of power supply equipment to be connected to a line impedance stabilization network (LISN), which can cause interference backflow at the input and output. Based on noise analysis of floating-ground devices with non-isolated architectures, the test results of dual-port LINS connections degrade by over 20dB compared to single-port LISN connections. Furthermore, conventional EMC filtering is limited by safety regulations, requiring very small Y-capacitor values. Consequently, the common-mode inductor must have a large inductance, resulting in a larger size. However, due to the small size of the optimizer, this level of common-mode inductance has a significant impact on the product architecture and cost. Summary of the Invention

[0004] The embodiments of the present application provide a power transmission system and a power generation system. By connecting a capacitor group across the input and output ends of the power transmission system, an interference return path is formed. This can reduce the interference current flowing through the input and output ends when the external impedance is small, such as when performing CE testing. There is no need to use Y capacitors. The capacitors in the cross-capacitor group have low withstand voltage and large capacitance, which can significantly reduce the volume of the filter inductor and thus reduce costs.

[0005] To this end, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a power transmission system, which includes: a power conversion circuit for performing power conversion on an input electrical signal; a filter circuit, including a first filter circuit and / or a second filter circuit, wherein the input end of the first filter circuit is coupled to the input end of the power transmission system, the first filter circuit is used to filter the electrical signal generated by the power conversion at the input end, and the output end of the first filter circuit is coupled to the input end of the power conversion circuit; the input end of the second filter circuit is coupled to the output end of the power conversion circuit, the second filter circuit is used to filter the electrical signal output by the power conversion circuit, and the second filter circuit is used to filter the electrical signal output by the power conversion circuit. The output end of the wave circuit is coupled to the output end of the power transmission system; at least one cross-capacitor group is used to make the interference signal generated by the power conversion circuit flow back from the output end of the power transmission system to the input end of the power transmission system, wherein: when the filter circuit only includes the second filter circuit, the input end of the power conversion circuit is coupled to the input end of the power transmission system, one end of each cross-capacitor group is coupled to the input end of the power transmission system, and the other end is coupled to the second filter circuit; when the filter circuit includes the first filter circuit and the second filter circuit, one end of each cross-capacitor group is coupled to the first filter circuit, and the other end is coupled to the second filter circuit.

[0007] In the power transmission system of the embodiment of the present application, one end of the jumper capacitor bank is coupled to the input end of the power transmission system, and the other end is coupled to the output end of the power transmission system, thereby forming a return path. This allows the interference signal output by the output end of the power conversion circuit to flow back to the input end of the power conversion circuit, thereby reducing the interference current flowing through the input end and / or output end of the power transmission system. In this way, when the external impedance is very small, there will not be a large common-mode current. For example, when performing CE testing, the interference current received by the LISN at the input and output ends is small, and the test results will not exceed the standard, which can meet the test requirements. In addition, there is no need to add safety Y capacitors to the housing. The capacitors of the jumper capacitor bank have low withstand voltage and large capacitance, which can significantly reduce the size of the filter inductor and reduce costs.

[0008] In one possible implementation, the at least one cross-capacitor group includes a first cross-capacitor group, one end of which is coupled to the input end of the power transmission system, and the other end of which is coupled to the output end of the power transmission system. That is, in this implementation, the two ends of the first cross-capacitor group can be coupled to the input end and the output end of the input end of the power transmission system, respectively, thereby forming a path for the interference signal to flow back. If the filter circuit includes a first filter circuit, the input end of the first filter circuit is coupled to the input end of the power transmission system, and in this case, one end of the first cross-capacitor group is coupled to the input end of the first filter circuit; if the filter circuit includes a second filter circuit, the output end of the second filter circuit is coupled to the output end of the power transmission system, and in this case, the other end of the first cross-capacitor group is coupled to the output end of the second filter circuit.

[0009] In a possible implementation, the first filter circuit includes a first filter capacitor and one or more first filter inductors connected in series, the input end of the one or more first filter inductors connected in series is the input end of the first filter circuit, the output end of the one or more first filter inductors connected in series is the output end of the first filter circuit, the first filter capacitor is provided at at least one of the input end of the first filter circuit, the output end of the first filter circuit and at least two adjacent first filter inductors, and one end of the first filter capacitor is coupled to the positive electrode of the input end of the power transmission system, and the other end is coupled to the negative electrode of the input end of the power transmission system. The first filter circuit includes a second filter capacitor and one or more second filter inductors connected in series, the input end of the one or more second filter inductors connected in series is the input end of the second filter circuit, the output end of the one or more second filter inductors connected in series is the output end of the second filter circuit, and the second filter capacitor is provided at least one of the input end of the second filter circuit, the output end of the second filter circuit, and at least two adjacent second filter inductors. One end of the second filter capacitor is coupled to the positive pole of the output end of the power transmission system, and the other end is coupled to the negative pole of the output end of the power transmission system. That is, in this implementation, the first filter circuit may include at least one first filter inductor and at least one first filter capacitor; the second filter circuit may include at least one second filter inductor and at least one second filter capacitor.

[0010] In a possible implementation, the filter circuit includes a first filter circuit and a second filter circuit, the first filter inductor includes a first common-mode inductor or includes a first differential-mode inductor and a second differential-mode inductor, and the second filter inductor includes a second common-mode inductor or includes a third differential-mode inductor and / or a fourth differential-mode inductor; or, the first filter inductor includes a first differential-mode inductor or a second differential-mode inductor, and the second filter inductor includes a second common-mode inductor or includes a third differential-mode inductor and four differential-mode inductors; or, the filter circuit includes only the second filter circuit, and the second filter inductor includes a second common-mode inductor or includes a third differential-mode inductor and a fourth differential-mode inductor; wherein: a first input end of the first common-mode inductor is coupled to a positive electrode of an input end of the power transmission system, a first output end of the first common-mode inductor is coupled to a positive electrode of an input end of the power conversion circuit, a second input end of the first common-mode inductor is coupled to a negative electrode of an input end of the power transmission system, and a second output end of the first common-mode inductor is coupled to a negative electrode of an input end of the power conversion circuit; one end of the first differential-mode inductor is coupled to the positive electrode of the input end of the power transmission system, and the second output end of the first common-mode inductor is coupled to the negative electrode of the input end of the power conversion circuit. The first differential-mode inductor is coupled to the positive electrode of the input terminal of the power transmission system, the other end of the first differential-mode inductor is coupled to the positive electrode of the input terminal of the power conversion circuit, one end of the second differential-mode inductor is coupled to the negative electrode of the input terminal of the power transmission system, and the other end of the second differential-mode inductor is coupled to the negative electrode of the input terminal of the power conversion circuit; the first input end of the second common-mode inductor is coupled to the positive electrode of the output terminal of the power conversion circuit, the first output end of the second common-mode inductor is coupled to the positive electrode of the output terminal of the power transmission system, the second input end of the second common-mode inductor is coupled to the negative electrode of the output terminal of the power conversion circuit, and the second output end of the second common-mode inductor is coupled to the negative electrode of the output terminal of the power transmission system; one end of the third differential-mode inductor is coupled to the positive electrode of the output terminal of the power conversion circuit, and the other end of the third differential-mode inductor is coupled to the positive electrode of the output terminal of the power transmission system; one end of the fourth differential-mode inductor is coupled to the negative electrode of the output terminal of the power conversion circuit, and the other end of the fourth differential-mode inductor is coupled to the negative electrode of the output terminal of the power transmission system. That is, in this implementation, the first filter inductor may include a common-mode inductor or at least one differential-mode inductor, and the second filter inductor may include a common-mode inductor or at least one differential-mode inductor. Generally, at least one inductor must be connected in series with the positive and negative wirings of the interference return path. Furthermore, if necessary, the first filter inductor may include both a common-mode inductor and a differential-mode inductor, and the second filter circuit may also include both a common-mode inductor and a differential-mode inductor.

[0011] In one possible implementation, the at least one cross-over capacitor group includes a second cross-over capacitor group, one end of the second cross-over capacitor group is coupled to a first node between two adjacent first filter inductors of the filter circuit, and the other end of the second cross-over capacitor group is coupled to an output of the power transmission system or an output of the power conversion circuit. That is, in this implementation, the filter circuit includes a first filter circuit, and the first filter circuit includes two adjacent first filter inductors. One end of the second cross-over capacitor group is coupled to a first node between the two adjacent first filter inductors. If the filter circuit includes a second filter circuit, the other end of the second cross-over capacitor group, when coupled to the output of the power transmission system, is also coupled to the output of the second filter circuit. If the filter circuit does not include a second filter circuit, the other end of the second cross-over capacitor group, when coupled to the output of the power transmission system, is also coupled to the output of the power conversion circuit (because when the filter circuit does not include a second filter circuit, the output of the power conversion circuit is coupled to the output of the power transmission system), thereby forming a path for interference signals to flow back.

[0012] In one possible implementation, the at least one cross-capacitor group includes a third cross-capacitor group, one end of the third cross-capacitor group is coupled to the input end of the power transmission system or the input end of the power conversion circuit, and the other end of the third cross-capacitor group is coupled to the second node between two adjacent second filter inductors of the filter circuit. That is to say, in this implementation, the filtering circuit includes a second filtering circuit, the second filtering circuit includes two adjacent second filtering inductors, and the other end of the third cross-capacitor group is coupled to the second node between the two adjacent second filtering inductors. If the filtering circuit includes the first filtering circuit, when one end of the third cross-capacitor group is coupled to the input end of the power transmission system, it is also coupled to the input end of the first filtering circuit, and when one end of the third cross-capacitor group is coupled to the input end of the power conversion circuit, it is also coupled to the output end of the first filtering circuit; if the filtering circuit does not include the first filtering circuit, when the other end of the second cross-capacitor group is coupled to the input end of the power transmission system, it is also coupled to the input end of the power conversion circuit (because the filtering circuit does not include the first filtering circuit, the input end of the power conversion circuit is coupled to the input end of the power transmission system), thereby forming a path for the interference signal to flow back.

[0013] In one possible implementation, the at least one cross-capacitor group includes a fourth cross-capacitor group, one end of the fourth cross-capacitor group is coupled to a first node between two adjacent first filter inductors of the filter circuit, and the other end of the fourth cross-capacitor group is coupled to a second node between two adjacent second filter inductors of the filter circuit. That is, in this implementation, the filter circuit includes a first filter circuit and a second filter circuit, the first filter circuit includes two adjacent first filter inductors, and the second filter circuit includes two adjacent second filter inductors. The two ends of the fourth cross-capacitor group are respectively coupled to the first node between the two adjacent first filter inductors and the second node between the two adjacent second filter inductors, thereby forming a path for the interference signal to flow back.

[0014] In one possible implementation, the at least one cross-capacitor group includes a fifth cross-capacitor group, one end of which is coupled to the input end of the first filter circuit and the other end is coupled to the output end of the power conversion circuit; and / or the at least one cross-capacitor group includes a sixth cross-capacitor group, one end of which is coupled to the input end of the power conversion circuit and the other end is coupled to the output end of the second filter circuit. That is, in this implementation, when the at least one cross-capacitor group includes the fifth cross-capacitor group, the filter circuit may include only the first filter circuit, or may include both the first filter circuit and the second filter circuit; when the at least one cross-capacitor group includes the sixth cross-capacitor group, the filter circuit may include only the second filter circuit, or may include both the first filter circuit and the second filter circuit.

[0015] In one possible implementation, the at least one cross-capacitor group includes a seventh cross-capacitor group, one end of which is coupled to the input of the power conversion circuit, and the other end of which is coupled to the output of the power conversion circuit. That is, in this implementation, the filter circuit may include a first filter circuit and / or a second filter circuit, and the two ends of the seventh cross-capacitor group are respectively coupled to the input and output of the power conversion circuit, thereby forming a path for the interference signal to flow back.

[0016] In one possible implementation, the cross-capacitor group includes: a first capacitor group, one end of the first capacitor group is coupled to the positive pole of the input end of the power transmission system and one of the negative pole of the input end of the power transmission system, and the other end of the first capacitor group is coupled to the positive pole of the output end of the power transmission system and one of the negative pole of the output end of the power transmission system; and / or, a second capacitor group, one end of the second capacitor group is coupled to the positive pole of the input end of the power transmission system and the other of the negative pole of the input end of the power transmission system, and the other end of the second capacitor group is coupled to the positive pole of the output end of the power transmission system and the other of the negative pole of the output end of the power transmission system; wherein, the first capacitor group and the second capacitor group each include one capacitor or more than two capacitors, and the two or more capacitors are connected in series or in parallel. That is, in this implementation, the cross-capacitor group may include a first capacitor group and a second capacitor group, or only include the first capacitor group, or only include the second capacitor group; the number of capacitor groups included in different cross-capacitor groups may be different or the same, for example, one of the two cross-capacitor groups may include the first capacitor group and the second capacitor group, or only include the first capacitor group, or only include the second capacitor group, and the other of the two cross-capacitor groups may also include the first capacitor group and the second capacitor group, or only include the first capacitor group, or only include the second capacitor group. In addition, a first connection method for the two ends of the cross-capacitor group is: the first ends of the two capacitor groups of the cross-capacitor group can be respectively coupled to the positive and negative poles of the input end of the power transmission system, and the second ends of the two capacitor groups of the cross-capacitor group can be respectively coupled to the positive and negative poles of the output end of the power transmission system.

[0017] In one possible implementation, the cross-capacitor group includes a third capacitor group and a fourth capacitor group, the third capacitor group including a first capacitor and a second capacitor connected in series between the positive electrode of the input terminal of the power transmission system and the negative electrode of the input terminal of the power transmission system; the fourth capacitor group including a third capacitor and a fourth capacitor connected in series between the positive electrode of the output terminal of the power transmission system and the negative electrode of the output terminal of the power transmission system, and the intermediate node between the first capacitor and the second capacitor is coupled to the intermediate node between the third capacitor and the fourth capacitor. In other words, in this implementation, the second connection method for the two ends of the cross-capacitor group is to couple the intermediate node of the two series capacitors located between the positive and negative electrodes of the input terminal of the power transmission system, namely, the first capacitor and the second capacitor, to the intermediate node of the two series capacitors located between the positive and negative electrodes of the output terminal of the power transmission system, namely, the third capacitor and the fourth capacitor. That is, one end of the cross-capacitor group can be coupled to the input terminal of the power transmission system via the first and second capacitors, and the other end of the cross-capacitor group can be coupled to the output terminal of the power transmission system via the third and fourth capacitors.

[0018] In one possible implementation, the electrical signal received at the input end of the power transmission system is a DC signal, and the power conversion circuit is used to convert the DC signal into another DC signal or into an AC signal; or, the electrical signal received at the input end of the power transmission system is an AC signal, and the power conversion circuit is used to convert the AC signal into a DC signal. That is, in this implementation, the power conversion circuit can have three conversion modes: Mode 1 - converting the DC signal into another DC signal, such as a DC signal with the highest output power; Mode 2 - converting the DC signal into an AC signal; Mode 3 - converting the AC signal into a DC signal.

[0019] Based on the first aspect and various implementation methods of the first aspect, in the second aspect, an embodiment of the present application provides a power generation system, which includes: a power supply device for providing an electrical signal, which is a direct current signal or an alternating current signal; the power transmission system provided by the above-mentioned first aspect, wherein the input end of the power transmission system can receive the electrical signal output by the power supply device.

[0020] In one possible implementation, the power supply device is a photovoltaic panel, which is used to convert the received sunlight into electrical energy to provide a DC signal. The power conversion circuit includes: a power optimizer, which is used to perform power optimization to convert the DC signal provided by the photovoltaic panel into a DC signal that outputs maximum power.

[0021] Based on the above aspects and various implementation methods, in a third aspect, the present application provides a power transmission system, including: a power conversion circuit for performing power conversion on an input electrical signal; a filter circuit, including a first filter circuit and a second filter circuit; and at least one cross-capacitor group; wherein the filter circuit includes the first filter circuit and the second filter circuit, the input end of the first filter circuit is coupled to the input end of the power transmission system, the output end of the first filter circuit is coupled to the input end of the power conversion circuit, and the first filter circuit is used to filter the electrical signal generated after power conversion of the power conversion circuit at the input end of the power transmission system. ; The input end of the second filter circuit is coupled to the output end of the power conversion circuit, and the output end of the second filter circuit is coupled to the output end of the power transmission system. The second filter circuit is used to filter the electrical signal generated after the power conversion of the power conversion circuit at the output end of the power transmission system; one end of each cross-capacitor group is coupled to the first filter circuit, and the other end is coupled to the second filter circuit; the first filter circuit includes a first filter inductor, and the second filter circuit includes a second filter inductor. The first filter inductor is a first differential mode inductor (such as L1 in Figure 10), and the second filter inductor is a second differential mode inductor (such as L3 in Figure 10). By setting up the jumper capacitor bank in the above manner, a return path can be formed, allowing the interference signal output from the output end of the power conversion circuit to flow back to the input end of the power conversion circuit, thereby reducing the interference current flowing through the input end and / or output end of the power transmission system. In this way, when the external impedance is very small, there will not be a large common-mode current. For example, when performing CE testing, the interference current received by the LISN at the input and output ends is small, and the test results will not exceed the standard, which can meet the test requirements. In addition, there is no need to add safety Y capacitors to the casing. The capacitors of the jumper capacitor bank have low withstand voltage and large capacitance, which can significantly reduce the size of the filter inductor and reduce costs. At the same time, because the second filter inductor uses a differential mode inductor, it can meet the filtering performance requirements while also reducing costs.

[0022] In one implementation of the third aspect, each cross-capacitor group is not grounded. This can reduce leakage current and improve product safety, while also increasing capacitance compared to grounding, thereby achieving better filtering performance.

[0023] In another implementation, each cross-capacitor group includes a third capacitor group and a fourth capacitor group, the third capacitor group includes a first capacitor and a second capacitor connected in series between the positive pole of the input end of the power transmission system and the negative pole of the input end of the power transmission system; the fourth capacitor group includes a third capacitor and a fourth capacitor connected in series between the positive pole of the output end of the power transmission system and the negative pole of the output end of the power transmission system, and the intermediate node between the first capacitor and the second capacitor is coupled to the intermediate node between the third capacitor and the fourth capacitor. The coupling of the intermediate nodes can reduce the voltage on the cross-capacitor, firstly, to increase the capacitance value and optimize the filtering effect, and secondly, to reduce the noise coupling between the input and output, and improve the EMC performance.

[0024] In another implementation, the at least one cross-over capacitor group includes a first cross-over capacitor group, one end of the first cross-over capacitor group is coupled to the input end of the power transmission system, and the other end of the first cross-over capacitor group is coupled to the output end of the power transmission system; the cross-over capacitor group includes: a first capacitor group, one end of the first capacitor group is coupled to the positive pole of the input end of the power transmission system and one of the negative pole of the input end of the power transmission system, and the other end of the first capacitor group is coupled to the positive pole of the output end of the power transmission system and one of the negative pole of the output end of the power transmission system; and / or, a second capacitor group, one end of the second capacitor group is coupled to the positive pole of the input end of the power transmission system and the other of the negative pole of the input end of the power transmission system, and the other end of the second capacitor group is coupled to the positive pole of the output end of the power transmission system and the other of the negative pole of the output end of the power transmission system; wherein, the first capacitor group and the second capacitor group each include one capacitor or more than two capacitors, and the two or more capacitors are connected in series or in parallel.

[0025] In another implementation, the first filter circuit includes a first filter capacitor and one or more first filter inductors connected in series, the input end of the one or more first filter inductors connected in series is the input end of the first filter circuit, the output end of the one or more first filter inductors connected in series is the output end of the first filter circuit, the first filter capacitor is provided at at least one of the input end of the first filter circuit, the output end of the first filter circuit and at least two adjacent first filter inductors, and one end of the first filter capacitor is coupled to the positive pole of the input end of the power transmission system, and the other end is coupled to the negative pole of the input end of the power transmission system. coupling; and / or, the second filtering circuit includes a second filtering capacitor and one or more second filtering inductors connected in series, the input end of the one or more second filtering inductors connected in series is the input end of the second filtering circuit, the output end of the one or more second filtering inductors connected in series is the output end of the second filtering circuit, and the second filtering capacitor is provided at at least one of the input end of the second filtering circuit, the output end of the second filtering circuit and at least two adjacent second filtering inductors, and one end of the second filtering capacitor is coupled to the positive pole of the output end of the power transmission system, and the other end is coupled to the negative pole of the output end of the power transmission system.

[0026] In another implementation, the electrical signal received at the input end of the power transmission system is a DC signal, and the power conversion circuit is used to convert the DC signal into another DC signal or into an AC signal; or, the electrical signal received at the input end of the power transmission system is an AC signal, and the power conversion circuit is used to convert the AC signal into a DC signal.

[0027] Based on the above aspects and various implementation methods in each aspect, the fourth aspect of the present application provides a power generation system, which is characterized in that it includes: a power supply device for providing an electrical signal, wherein the electrical signal is a direct current signal or an alternating current signal; and a power transmission system according to the above aspects and various implementation methods in each aspect, wherein the input end of the power transmission system is capable of receiving the electrical signal output by the power supply device.

[0028] In one implementation, the power supply device is a photovoltaic panel, which is used to convert the received sunlight into electrical energy to provide a DC signal. The power conversion circuit includes: a power optimizer, which is used to perform power optimization to convert the DC signal provided by the photovoltaic panel into a DC signal that outputs maximum power.

[0029] In one implementation, the power supply device is an AC power grid, the AC power grid is used to provide an AC power signal, and the power conversion circuit is used to convert the AC power signal into a DC power signal.

[0030] Other features and advantages of the present invention will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The following is a brief introduction to the drawings required for describing the embodiments or prior art.

[0032] FIG1A is a schematic diagram of a circuit structure of a buck / boost device;

[0033] FIG1B is a schematic diagram of the circuit structure of an ultra-wideband EMC power filter;

[0034] FIG2A is a schematic diagram showing a CE test of a power conversion device in a photovoltaic power generation system without a filter circuit;

[0035] FIG2B is a schematic diagram of a common-mode return path of the power conversion device undergoing CE testing shown in FIG2A ;

[0036] FIG3 is a schematic diagram showing the CE test of the power conversion equipment of the photovoltaic power generation system after the filter circuit is provided;

[0037] FIG4 is a schematic structural diagram of a power transmission system provided in the first embodiment of the present application;

[0038] FIG5 is a schematic diagram of a CE test performed on the power transmission system shown in FIG4 ;

[0039] FIG6 is a schematic structural diagram of a variation of the power transmission system shown in FIG4 ;

[0040] FIG7 is a schematic structural diagram of another variant of the power transmission system shown in FIG4 ;

[0041] FIG8 is a schematic structural diagram of a power transmission system provided in a second embodiment of the present application;

[0042] FIG9 is a schematic structural diagram of a power transmission system provided in a third embodiment of the present application;

[0043] FIG10 is another structural schematic diagram of the power transmission system provided in this application. DETAILED DESCRIPTION

[0044] The following will describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments.

[0045] In the description of this specification, "one embodiment" or "some embodiments" means that one or more embodiments of this specification include a particular feature, structure, or characteristic described in conjunction with the embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized.

[0046] In the description of this specification, unless otherwise specified, " / " means or. For example, A / B can mean A or B. "And / or" in this document is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of this application, "plurality" means two or more than two.

[0047] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. The terms "including," "comprising," "having," and their variations all mean "including but not limited to," unless otherwise specifically emphasized.

[0048] It should be noted that the term "coupled" as used herein encompasses both direct connections between two or more circuit objects without any intervening circuit objects, and indirect connections between two or more circuit objects via one or more intervening circuit objects. For example, two circuit objects that are directly connected to each other are said to be "coupled" to each other. Similarly, two circuit objects that have one or more intervening circuit objects connected between them are also said to be "coupled" to each other. In other words, "coupling" can mean a direct electrical connection or an indirect electrical connection. The latter refers to the presence of other components, such as resistors and capacitors, in between.

[0049] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0050] The following is a detailed introduction to the abbreviations and key terms used in the embodiments of this application:

[0051] A power optimizer is a module-level power electronic device with a DC input and output. Each or two PV panels are connected to a power optimizer with maximum power point tracking (MPPT). The optimizer converts the current required by the series circuit, for example, converting low current to high current. Finally, the outputs of the power optimizers are connected in series and connected to a combiner box or inverter, enabling module-level control.

[0052] Safety capacitors are designed to prevent electric shock and personal injury after failure. They include two types: X capacitors and Y capacitors. X capacitors are connected between two power lines (L and N) and are typically made of metal film. Y capacitors are connected between two power lines and ground (LE and NE) and are typically used in pairs. Due to leakage current limitations, Y capacitor values ​​cannot be too large. X capacitors suppress differential-mode interference, while Y capacitors suppress common-mode interference.

[0053] Conducted emission (CE) testing, often also referred to as interference voltage testing, is required for any product with a power cord, including many DC-powered products. In addition, many standards also have conducted emission requirements for signal / control lines, usually expressed as interference voltage (dBuV) or interference current (dBuA) limits (the two are convertible).

[0054] Insertion loss is the loss of energy or gain when certain devices or branch circuits (filters, impedance matching devices, etc.) are added to a circuit.

[0055] The Line Impedance Stabilization Network (LISN) is an important auxiliary device for electromagnetic compatibility testing in power systems. It can isolate grid interference, provide stable test impedance, and act as a filter.

[0056] Figure 1A is a schematic diagram of the circuit structure of a buck / boost device. As shown in Figure 1A , the buck / boost device includes a buck / boost circuit 501, a first EMC filter circuit 502, and a second EMC filter circuit 503. Buck / boost circuit 501 includes a first port 5011, a buck / boost module 5012, and a second port 5013. First port 5011 is connected to the input of an oscillating current suppression module 101 in the first EMC filter circuit 502, while second port 5013 is connected to the input of an oscillating current suppression module 101 in the second EMC filter circuit 503. Oscillation current suppression module 101 includes a common-mode inductor.

[0057] By adding an additional common-mode inductor to the standard electromagnetic compatibility filter circuit, the resonance problem caused by the Y capacitor and the differential-mode inductor is effectively avoided when the EMC filter circuit is connected to the buck / boost circuit, greatly improving the EMC characteristics. The measure is simple and practical.

[0058] Figure 1B is a schematic diagram of the circuit structure of an ultra-wideband EMC power filter. As shown in Figure 1B, the ultra-wideband EMC power filter includes a live wire L, a neutral wire N, and a ground wire GND. The input ends of the live wire L, neutral wire N, and ground wire GND are all connected to an EMC high-frequency magnetic ring L1. The output ends of the EMC high-frequency magnetic ring L1 on the live wire L and neutral wire N are connected in series with common-mode inductors L3 and L4, respectively. A low-frequency differential-mode inductor L2 is connected between the output end of the EMC high-frequency magnetic ring L1 on the live wire L and the input end of the common-mode inductor L3. The output end of the EMC high-frequency magnetic ring L1 on the live wire L is connected to the resistor R1 and the resistor R3, and the output end of the EMC high-frequency magnetic ring L1 on the neutral wire N is connected to the resistor R2 and the resistor R4 in parallel. The output end of the resistor R1 is connected to the input end of the resistor R4, and the ends of the resistor R2 and the resistor R4 are connected to the capacitor C1 in parallel; the output end of the low-frequency differential mode inductor L2 is connected to the capacitor C2 and the input end of the common mode inductor L3 on the neutral wire N, and the output end of the common mode inductor L3 on the live wire L is connected to the capacitor Y1 and capacitor Y2 are connected to the output end of the common-mode inductor L3 on the neutral line N, the two ends of capacitor Y1 and capacitor Y2 are connected in parallel to capacitor C3, and the output end of capacitor Y1 is connected to the output end of the EMC high-frequency magnetic ring L1 on the ground line GND; the output end of the common-mode inductor L4 on the live line L is connected to capacitor Y3 and capacitor Y4 is connected to the output end of the common-mode inductor L4 on the neutral line N, the two ends of capacitor Y3 and capacitor Y4 are connected in parallel to capacitor C4, and the output end of capacitor Y3 is connected to the output end of the EMC high-frequency magnetic ring L1 on the ground line GND.

[0059] By adding the EMC high-frequency magnetic ring L1, a very good EMC filtering effect can be achieved for frequencies above 50MHz. Adding a low-frequency differential mode inductor L2 made of a low-frequency magnetic core material to the live wire L can effectively remove EMC interference signals in the range of 9 to 150kHz. This ultra-wideband EMC power supply filter has a wider range and can replace all current filters, expanding its applicable field and effectively reducing the number of other EMC components in the product.

[0060] Both of the above solutions use safety Y capacitors, which are only suitable for grounded equipment. The first solution has poor filtering effect on the loop formed by the coupling of the input and output ends. The second solution achieves broadband, high-impedance filtering effects through single-channel filtering enhancement. It is for single-port scenarios and has limited applicability. It also requires multi-stage common-mode inductors, which is not conducive to reducing volume and cost.

[0061] In view of this, embodiments of the present application provide a power transmission system and a power generation system. The power generation system includes a power supply device and a power transmission system. The power supply device is configured to provide an electrical signal, which may be a direct current (DC) or alternating current (AC) signal. The input end of the power transmission system is capable of receiving the electrical signal output by the power supply device. By providing at least one cross-capacitor bank between the input and output ends of the power transmission system to form an interference return path, the common-mode current flowing through the input and output ends of the power transmission system can be reduced. This prevents significant common-mode current when the external impedance is very low. For example, during CE testing (i.e., both the input and output ends of the power transmission system are connected to a LISN, with the two LISNs at the input and output ends of the power transmission system connected in series), the interference current received by the LISNs at the input and output ends is relatively small, and the CE test results at the input and output ends do not exceed the standard, thus meeting the test requirements. Furthermore, this filtering solution does not require the addition of Y capacitors to the housing. The capacitors in the cross-capacitor bank have a low withstand voltage and a large capacitance, which can significantly reduce the size of the filter inductor, thereby reducing costs.

[0062] In other words, the power transmission system of the embodiment of the present application is suitable for multi-port non-isolated architecture scenarios, such as existing power optimizer projects. It can solve the interference backflow problem caused by multiple power ports being terminated with low common-mode impedance such as LISN, and can solve the problem of insufficient common-mode filtering insertion loss due to the inability to increase the safety Y capacitor of the product, while minimizing the impact on product performance.

[0063] Among them, the power supply device may be a photovoltaic panel, which is used to convert the received sunlight into electrical energy to provide a DC signal. The power conversion circuit of the power transmission system may include an inverter, which is used to invert the DC signal into an AC signal. Alternatively, the power conversion circuit of the power transmission system may include a power optimizer, which is used to perform power optimization to convert the DC signal provided by the photovoltaic panel into a DC signal that outputs maximum power. In addition, other power supply devices may be selected as needed. For example, the power supply device may be an AC power grid, which is used to provide an AC signal. The power conversion circuit of the power transmission system is used to convert the AC signal into a DC signal. In the embodiment of the present application, the power supply device is mainly described as a photovoltaic panel and the power conversion circuit is a power optimizer. That is, in this case, the power conversion circuit can convert the DC signal provided by the photovoltaic panel into a DC signal that outputs maximum power.

[0064] Figure 2A is a schematic diagram of a CE test for power conversion equipment in a photovoltaic power generation system without a filter circuit. As shown in Figure 2A, the test system can include a DC power supply simulating a photovoltaic (PV) panel, the equipment under test (EUT), namely the power conversion equipment (PCE), a resistive load such as a PV inverter, and an EMI (electromagnetic interference) receiver. The EUT (PCE) can be a power optimizer. During CE testing, the input and output of the EUT (PCE) are each connected to a LISN, namely a DC-AN. Both LISNs are grounded, forming a loop between the LISN at the input, the (PCE) EUT, and the LISN at the output. The input and output impedances are the series impedances of the two LISNs, and the input and output currents flow back through the LISNs, forming a common-mode current.

[0065] Figure 2B is a schematic diagram of the common-mode return current path of the power conversion device shown in Figure 2A undergoing CE testing. As shown in Figure 2B, the power conversion circuit of a power conversion device, such as a power optimizer, may include switches Q1-Q2, an inductor L1, capacitors C1-C2, and a diode. The input of the power conversion circuit is connected to a first LISN, and the output is connected to a second LISN. The noise mechanism of the non-isolated architecture of this power optimizer is analyzed as follows: When the internal switch Q1 or Q2 of the power optimizer is activated, the current path follows: ① Switching noise excitation of the switch within the optimizer → ② The output of the optimizer → ③ The second LISN at the output → ④ The first LISN at the input → ⑤ The switch within the power optimizer. Because the external impedance, i.e., the LISN, is very small, a large common-mode current will flow. When the current exceeds a certain value, the EMI receiver coupled to the output LISN will receive a large interference signal, causing CE test results, such as the interference voltage dBuV or interference current dBuA, to seriously exceed the specified value.

[0066] Figure 3 is a schematic diagram illustrating CE testing of power conversion equipment in a photovoltaic power generation system equipped with a filter circuit. As shown in Figure 3, the photovoltaic power generation system includes a power transmission system, a first LISN, and a second LISN. The power transmission system includes a power conversion circuit, a first filter circuit, and a second filter circuit. The first LISN is coupled to the input of the first filter circuit. The second LISN is coupled to the output of the second filter circuit.

[0067] The first filter circuit includes a first common-mode inductor T1 and Y-capacitors Cy1 and Cy2, while the second filter circuit includes a second common-mode inductor T2 and Y-capacitors Cy3 and Cy4. The input and output of the power conversion circuit are each filtered through the common-mode inductor and Y-capacitor ground connections. After the modules are connected in series, the voltage of the post-optimizer module to ground rises to 200-500V. Safety regulations require that the Y-capacitors must be safety-certified capacitors of Y2 or higher. Furthermore, the capacitance Cy of the Y-capacitors is limited, requiring pF-level capacitors. To achieve optimal filtering or meet the required common-mode filtering requirements, a common-mode inductor with a larger inductance, such as 5-10mH, is required. This results in a large size and high cost.

[0068] FIG4 is a schematic structural diagram of a power transmission system provided in the first embodiment of the present application. As shown in FIG4 , the power transmission system includes a power conversion circuit 10 and a filter circuit. The filter circuit includes a first filter circuit LC1 and a second filter circuit LC2. The input end of the first filter circuit LC1 is coupled to the input end of the power transmission system, and the first filter circuit LC1 is used to filter the electrical signal received at the input end of the power transmission system. The output end of the first filter circuit LC1 is coupled to the input end of the power conversion circuit 10. The power conversion circuit 10 is used to perform power conversion on the filtered electrical signal output from the output end of the first filter circuit LC1. The input end of the second filter circuit LC2 is coupled to the output end of the power conversion circuit 10, and the second filter circuit LC2 is used to filter the electrical signal output from the power conversion circuit 10. The output end of the second filter circuit LC2 is coupled to the output end of the power transmission system.

[0069] The power conversion circuit 10 may have at least one of the following functions: step-up, step-down, rectification, and inversion, and may convert power inputted at its input into power required by a load coupled to its output. Specifically, the magnitude and type of current may be varied. For example, the electrical signal received at the input of the power transmission system may be a DC signal. In this case, the power conversion circuit 10 is configured to convert the DC signal into another DC signal or into an AC signal. Another example is that the electrical signal received at the input of the power transmission system may be an AC signal. In this case, the power conversion circuit 10 is configured to convert the AC signal into a DC signal. Specifically, the power conversion circuit 10 may have three conversion modes: Mode 1—converting the DC signal into another DC signal, such as a DC signal with the highest output power. In this case, the power conversion circuit 10 may function as a power optimizer; Mode 2—converting the DC signal into an AC signal. In this case, the power conversion circuit 10 may function as an inverter; and Mode 3—converting the AC signal into a DC signal. It is understood that the power conversion circuit 10 may also have other conversion modes if necessary.

[0070] Furthermore, the power transmission system may further include at least one cross-capacitor bank Cf, each cross-capacitor bank Cf having one end coupled to the first filter circuit LC1 and the other end coupled to the second filter circuit LC2. The at least one cross-capacitor bank Cf is configured to allow interference signals in the electrical signal output from the output end of the power conversion circuit 10 to flow back to the input end of the power conversion circuit 10. Since the interference signal is generally an AC signal, when the target signal in the electrical signal is a DC signal, the DC signal cannot pass through the cross-capacitor bank Cf, while the AC signal can pass through the cross-capacitor bank Cf. Therefore, the interference signal in the electrical signal can flow back. When the target signal in the electrical signal is an AC signal, since the frequency of the target signal differs from the frequency of the interference signal, by properly setting the inductance value of the filter inductor, the capacitance value of the filter capacitor, and the capacitance value of the cross-capacitor bank Cf in the filter circuit, it is possible to ensure that only the interference signal flows back through the cross-capacitor bank Cf, while the target signal does not pass through the cross-capacitor bank Cf.

[0071] In the power transmission system of the embodiment of the present application, one end of the cross-capacitor group is coupled to the input end of the power transmission system, and the other end is coupled to the output end of the power transmission system. For example, one end of the cross-capacitor group Cf is coupled to the first filter circuit LC1, and the other end is coupled to the second filter circuit LC2. This forms a path for interference signals to flow back, allowing interference signals in the electrical signal output from the output end of the power conversion circuit 10 to flow back to the input end of the power conversion circuit 10, thereby reducing interference current flowing through the input and / or output ends of the power transmission system. In this way, when the external impedance is very low, there will not be a large common-mode current. For example, during CE testing, the interference current received by the LISN coupled to the input and output ends of the power conversion circuit 10 is relatively small, and the test results will not exceed the standard, thus meeting the test requirements. Furthermore, there is no need to add safety Y capacitors to the chassis. The capacitors of the cross-capacitor group Cf have a low withstand voltage and a large capacitance value, which can significantly reduce the size and cost of the inductor.

[0072] In Figure 4, at least one cross-over capacitor group Cf includes a first cross-over capacitor group Cf1, which may include at least one of a first capacitor group Cf1' and a second capacitor group Cf1". One end of the first cross-over capacitor group Cf1 (i.e., capacitor group Cf1' and / or capacitor group Cf1") is coupled to the input end of the first filter circuit LC1, and the other end of the first cross-over capacitor group Cf1 (i.e., capacitor group Cf1' and / or capacitor group Cf1") is coupled to the output end of the second filter circuit LC2. The two ends of the first cross-over capacitor group Cf1 may be located outside the first filter circuit LC1 and the second filter circuit LC2, respectively. That is, the two ends of the first cross-over capacitor group Cf1 may be coupled to the input end and the output end of the power transmission system, respectively. In this case, the filter circuit may also include only the first filter circuit LC1, or only the second filter circuit LC2.

[0073] Figure 5 is a schematic diagram of a CE test for the power transmission system shown in Figure 4 . As shown in Figure 5 , power conversion circuit 10 can be a power optimizer and may include switches Q1-Q2, an inductor L', capacitors C' and C", and diodes. By providing a first filter circuit LC1 at the input of power conversion circuit 10 and a second filter circuit LC2 at the output of power conversion circuit 10, and coupling the first filter circuit LC1 and the second filter circuit LC2 via a cross-over capacitor bank, such as first cross-over capacitor bank Cf1, interference current can flow through the following two paths:

[0074] Main path (see the thicker dotted arrow in FIG5 ): ① switching noise excitation (interference signal) of the switch tube of the power conversion circuit 10 → ② output end of the power conversion circuit 10 → ③ second filter circuit LC2 → ④ first cross-connected capacitor group Cf1 (which may include a first capacitor group Cf1′ and a second capacitor group Cf1″) → ⑤ first filter circuit LC1 → ⑥ switch tube of the power conversion circuit 10;

[0075] Secondary path (see the thinner dotted arrow in Figure 5): ① switching noise excitation of the switching tube → ② output end of the optimizer → ③ second filter circuit LC2 → ④ second LISN at the output end → ⑤ first LISN at the input end → ⑥ first filter circuit LC1 → ⑦ switching tube of the power conversion circuit 10.

[0076] In other words, the solution of the embodiments of the present application allows common-mode interference current to flow internally during filtering, thereby preventing most noise from flowing through the LISN. This significantly reduces the inductance of the filter inductor without affecting the product's technical performance, effectively reducing the volume of the port filter circuit (inductor, capacitor) of dual-port or multi-port devices, which helps reduce costs. Furthermore, common-mode filtering can be achieved without grounding the product housing, as interference current flows internally. The capacitance of the filter jumper capacitor is not limited by safety regulations and can be adjusted over a wide range.

[0077] In one example, under the premise of meeting CE testing, compared with conventional filtering solutions, the solution of the embodiment of the present application can reduce the volume of the filtering circuit by at least 30% and the cost by 50%; and can avoid the generation of leakage current. The actual installation does not require the entire product to be grounded, avoiding the high voltage resistance requirements of the device due to grounding.

[0078] In addition, the positions of the cross-capacitor groups can be selected in a variety of ways, which is highly flexible. Specifically, the positions of the other cross-capacitor groups other than the first cross-capacitor group Cf1 can be completely different from the positions of the two ends of the first cross-capacitor group Cf1. Alternatively, the other cross-capacitor groups can be obtained by adjusting the position of one end of the first cross-capacitor group Cf1. For example, at least one cross-capacitor group Cf may include a fifth cross-capacitor group (not shown in the figure), one end of the fifth cross-capacitor group is coupled to the input end of the first filter circuit LC1, and the other end is coupled to the output end of the power conversion circuit. If the filter circuit includes a second filter circuit LC2, the other end of the fifth cross-capacitor group is coupled to the input end of the second filter circuit LC2 (because the input end of the second filter circuit LC2 is coupled to the output end of the power conversion circuit). For another example, at least one cross-capacitor group Cf may include a sixth cross-capacitor group (not shown in the figure), one end of the sixth cross-capacitor group is coupled to the input end of the power conversion circuit, and the other end is coupled to the output end of the second filter circuit LC2. If the filtering circuit includes a filtering circuit LC1 , one end of the sixth cross-capacitor group is coupled to the output end of the first filtering circuit LC1 (because the output end of the first filtering circuit LC1 is coupled to the input end of the power conversion circuit).

[0079] Furthermore, there are multiple options for the specific connection method across the cross-over capacitor group Cf. Figure 6 is a schematic diagram of the structure of a variant of the power transmission system shown in Figure 4. Figure 7 is a schematic diagram of the structure of another variant of the power transmission system shown in Figure 4. The specific connection method across the cross-over capacitor group Cf will be described below with reference to Figures 4, 6, and 7, primarily using the first cross-over capacitor group Cf1 as an example.

[0080] 1. The first connection method

[0081] As shown in Figures 4 and 6, a cross-over capacitor group Cf, such as the first cross-over capacitor group Cf1, may include a first capacitor group such as Cf1' and / or a second capacitor group such as Cf1", wherein the first capacitor group Cf1' and the second capacitor group Cf1" each include one capacitor or two or more capacitors, and the two or more capacitors may be connected in series or in parallel. In Figures 4 and 6, each capacitor group includes one capacitor. One end of the first capacitor group Cf1' is coupled to the positive pole of the input end of the power transmission system and one of the negative pole of the input end of the power transmission system, and the other end of the first capacitor group Cf1' is coupled to the positive pole of the output end of the power transmission system and one of the negative pole of the output end of the power transmission system. One end of the second capacitor group Cf1" is coupled to the other of the positive pole of the input end of the power transmission system and the negative pole of the input end of the power transmission system, and the other end of the second capacitor group Cf1" is coupled to the other of the positive pole of the output end of the power transmission system and the negative pole of the output end of the power transmission system. Specifically, the following four situations may be included:

[0082] In the first case, as shown in FIG4 , one end of the first capacitor group Cf1 ′ is coupled to the positive electrode of the input terminal, and the other end is coupled to the positive electrode of the output terminal; one end of the second capacitor group Cf1 ″ is coupled to the negative electrode of the input terminal, and the other end is coupled to the negative electrode of the output terminal.

[0083] The second case: one end of the first capacitor group Cf1' is coupled to the negative electrode of the input terminal, and the other end is coupled to the negative electrode of the output terminal; one end of the second capacitor group Cf1" is coupled to the positive electrode of the input terminal, and the other end is coupled to the positive electrode of the output terminal.

[0084] The third case: one end of the first capacitor group Cf1' is coupled to the positive electrode of the input terminal, and the other end is coupled to the negative electrode of the output terminal; one end of the second capacitor group Cf1" is coupled to the negative electrode of the input terminal, and the other end is coupled to the positive electrode of the output terminal.

[0085] The fourth case - as shown in FIG6 , one end of the first capacitor group Cf1 ′ is coupled to the negative electrode of the input terminal, and the other end is coupled to the positive electrode of the output terminal; one end of the second capacitor group Cf1 ″ is coupled to the positive electrode of the input terminal, and the other end is coupled to the negative electrode of the output terminal.

[0086] 2. The second connection method

[0087] As shown in Figure 7, the cross-connected capacitor group Cf, such as the first cross-connected capacitor group Cf1, may include a third capacitor group Cf1'" and a fourth capacitor group Cf1", the third capacitor group Cf1'" includes a first capacitor Cs1 and a second capacitor Cs2 connected in series between the positive pole of the input end of the power transmission system and the negative pole of the input end of the power transmission system; the fourth capacitor group Cf1'" includes a third capacitor Cs3 and a fourth capacitor Cs4 connected in series between the positive pole of the output end of the power transmission system and the negative pole of the output end of the power transmission system, and the intermediate node between the first capacitor Cs1 and the second capacitor Cs2 is coupled to the intermediate node between the third capacitor Cs3 and the fourth capacitor Cs4.

[0088] FIG8 is a schematic structural diagram of a power transmission system provided in the second embodiment of the present application. The difference from the power transmission system of the first embodiment shown in FIG4 is that, in FIG8 , at least one cross-capacitor group Cf may further include a seventh cross-capacitor group Cf7, wherein the first capacitor group of the seventh cross-capacitor group Cf7 is Cf7', and the second capacitor group of the seventh cross-capacitor group Cf7 is Cf7". One end of the seventh cross-capacitor group Cf7 (which may include at least one of Cf7' and Cf7") is coupled to the input end of the power conversion circuit, and the other end of the seventh cross-capacitor group Cf7 is coupled to the output end of the power conversion circuit. When the filter circuit includes the first filter circuit LC1, one end of the seventh cross-capacitor group Cf7 is coupled to the output end of the first filter circuit LC1; when the filter circuit includes the second filter circuit LC2, the other end of the seventh cross-capacitor group Cf7 is coupled to the input end of the second filter circuit LC2.

[0089] That is, in Figure 8, the power transmission system includes two cross-over capacitor banks Cf: a first cross-over capacitor bank Cf1 and a seventh cross-over capacitor bank Cf7. It will be appreciated that, if necessary, the power transmission system may include more cross-over capacitor banks Cf. Furthermore, the specific connection method for the ends of the seventh cross-over capacitor bank Cf7 can refer to the two methods described above for the first cross-over capacitor bank Cf1.

[0090] Furthermore, in the power transmission system of the above embodiment, the first filter circuit LC1 may include a first filter capacitor C1 and one or more first filter inductors LT1 connected in series. The input end of the one or more first filter inductors LT1 connected in series serves as the input end of the first filter circuit LC1, and the output end of the one or more first filter inductors LT1 connected in series serves as the output end of the first filter circuit LC1. The first filter capacitor C1 is disposed at at least one of the input end of the first filter circuit LC1, the output end of the first filter circuit LC1, and between at least two adjacent first filter inductors LT1. Specifically, the first filter capacitor C1 may be disposed at at least one of three locations: the input end of the first filter circuit LC1, the output end of the first filter circuit LC1, and between at least two adjacent first filter inductors LT1. Furthermore, one end of the first filter capacitor C1 is coupled to the positive terminal of the input end of the power transmission system, and the other end is coupled to the negative terminal of the input end of the power transmission system. For example, in Figures 4 and 6, the first filter circuit LC1 includes a first filter capacitor C1 and a first filter inductor LT1, with the first filter capacitor C1 located at the input end of the first filter circuit LC1. In FIG. 9 to be described below, the first filter circuit LC1 includes a first filter capacitor C1 and two first filter inductors LT1 , and the first filter capacitor C1 is located between two adjacent first filter inductors LT1 .

[0091] The second filter circuit LC2 may include a second filter capacitor C2 and one or more second filter inductors LT2 connected in series. The input end of the one or more second filter inductors LT2 connected in series serves as the input end of the second filter circuit LC2, and the output end of the one or more second filter inductors LT2 connected in series serves as the output end of the second filter circuit LC2. The second filter capacitor C2 is disposed at at least one of the input end of the second filter circuit LC2, the output end of the second filter circuit LC2, and between at least two adjacent second filter inductors LT2. That is, the second filter capacitor C2 may be disposed at at least one of three locations: the input end of the second filter circuit LC2, the output end of the second filter circuit LC2, and between at least two adjacent second filter inductors LT2. Furthermore, one end of the second filter capacitor C2 is coupled to the positive electrode of the output end of the power transmission system, and the other end is coupled to the negative electrode of the output end of the power transmission system. For example, in Figures 4 and 6, the second filter circuit LC2 includes one second filter capacitor C2 and one second filter inductor LT2, and the second filter capacitor C2 is located at the output end of the second filter circuit LC2. In FIG. 9 to be described below, the second filtering circuit LC2 includes a second filtering capacitor C2 and two second filtering inductors LT2 , and the second filtering capacitor C2 is located between two adjacent second filtering inductors LT2 .

[0092] The filter circuit includes a first filter circuit LC1 and a second filter circuit LC2. The first filter inductor LT1 and the second filter inductor LT2 may have but are not limited to the following two situations:

[0093] Case 1: The first filter inductor LT1 includes the first common-mode inductor T1 or the first differential-mode inductor L1 and the second differential-mode inductor L2, and the second filter inductor LT2 includes the second common-mode inductor T2 or the third differential-mode inductor L3 and / or the fourth differential-mode inductor L4. For example, in Figure 4 , the first filter inductor LT1 includes the first common-mode inductor T1, and the second filter inductor LT2 includes the second common-mode inductor T2. In Figure 6 , the first filter inductor LT1 includes the first differential-mode inductor L1 and the second differential-mode inductor L2, and the second filter inductor LT2 includes the third differential-mode inductor L3 and the fourth differential-mode inductor L4.

[0094] The second scenario involves the first filter inductor LT1 including the first differential-mode inductor L1 or the second differential-mode inductor L2, and the second filter inductor LT2 including the second common-mode inductor T2 or including the third differential-mode inductor L3 and / or the fourth differential-mode inductor L4. For example, the first differential-mode inductor L1 or the second differential-mode inductor L2 in Figure 6 can be removed, and the second filter inductor LT2 can include the third differential-mode inductor L3 and the fourth differential-mode inductor L4. Alternatively, the third differential-mode inductor L3 and the fourth differential-mode inductor L4 can be replaced with the second common-mode inductor T2. Alternatively, only the first differential-mode inductor L1 of the first filter circuit and the third differential-mode inductor L3 of the second filter circuit can be retained, and they can be directly connected via a common point in a crossover configuration, resulting in the connection shown in Figure 10. The first filter circuit can have only one differential-mode inductor L1, and the second filter circuit can have only one differential-mode inductor L3. This achieves both satisfactory filtering performance and reduced costs.

[0095] As shown in FIG4 , the first input terminal of the first common-mode inductor T1 is coupled to the positive electrode of the input terminal of the power transmission system, the first output terminal of the first common-mode inductor T1 is coupled to the positive electrode of the input terminal of the power conversion circuit 10, the second input terminal of the first common-mode inductor T1 is coupled to the negative electrode of the input terminal of the power transmission system, and the second output terminal of the first common-mode inductor T1 is coupled to the negative electrode of the input terminal of the power conversion circuit 10. The first input terminal of the second common-mode inductor T2 is coupled to the positive electrode of the output terminal of the power transmission system, the first output terminal of the second common-mode inductor T2 is coupled to the positive electrode of the output terminal of the power transmission system, the second input terminal of the second common-mode inductor T2 is coupled to the negative electrode of the output terminal of the power conversion circuit 10, and the second output terminal of the second common-mode inductor T2 is coupled to the negative electrode of the output terminal of the power transmission system.

[0096] As shown in FIG6 , one end of the first differential-mode inductor L1 is coupled to the positive electrode of the input terminal of the power transmission system, and the other end of the first differential-mode inductor L1 is coupled to the positive electrode of the input terminal of the power conversion circuit 10. One end of the second differential-mode inductor L2 is coupled to the negative electrode of the input terminal of the power transmission system, and the other end of the second differential-mode inductor L2 is coupled to the negative electrode of the input terminal of the power conversion circuit 10. One end of the third differential-mode inductor L3 is coupled to the positive electrode of the output terminal of the power conversion circuit 10, and the other end of the third differential-mode inductor L3 is coupled to the positive electrode of the output terminal of the power transmission system. One end of the fourth differential-mode inductor L4 is coupled to the negative electrode of the output terminal of the power conversion circuit 10, and the other end of the fourth differential-mode inductor L4 is coupled to the negative electrode of the output terminal of the power transmission system.

[0097] That is, the filter inductors at the input and output of the power conversion circuit may both be common-mode inductors or differential-mode inductors; optionally, the filter inductor at the output of the power conversion circuit is a common-mode inductor and the filter inductor at the input is a differential-mode inductor; or, the filter inductor at the output of the power conversion circuit is a differential-mode inductor and the filter inductor at the input is a common-mode inductor. Furthermore, if necessary, the filter inductors at the input and / or output of the power transmission system may include at least one differential-mode inductor and at least one common-mode inductor, and these inductors may be connected in series or in parallel as needed.

[0098] FIG9 is a schematic structural diagram of a power transmission system provided in the third embodiment of the present application. As shown in FIG9 , in the power transmission system, at least one cross-capacitor group Cf includes a fourth cross-capacitor group Cf4, wherein the first capacitor group of the fourth cross-capacitor group Cf4 is Cf4', and the second capacitor group of the fourth cross-capacitor group Cf4 is Cf4". One end of the fourth cross-capacitor group Cf4 (which may include at least one of Cf4' and Cf4") is coupled to a first node between two adjacent first filter inductors LT1 of the first filter circuit LC1, and the other end of the fourth cross-capacitor group Cf is coupled to a second node between two adjacent second filter inductors LT2 in the second filter circuit LC2.

[0099] Furthermore, the positions of the other cross-capacitor groups except the fourth cross-capacitor group Cf4 may be completely different from the positions of both ends of the fourth cross-capacitor group Cf4. Alternatively, the other cross-capacitor groups may be obtained by adjusting the position of one end of the fourth cross-capacitor group Cf4.

[0100] In one example, the at least one cross-capacitor group Cf may include a second cross-capacitor group (not shown). One end of the second cross-capacitor group is coupled to a first node between two adjacent first filter inductors LT1 of the first filter circuit LC1, and the other end of the second cross-capacitor group Cf is coupled to the output of the power transmission system or the output of the power conversion circuit 10. If the filter circuit includes the second filter circuit LC2, the other end of the second cross-capacitor group Cf is also coupled to the output of the second filter circuit LC2 when coupled to the output of the power transmission system. The other end of the second cross-capacitor group is also coupled to the input of the second filter circuit LC2 when coupled to the output of the power conversion circuit 10. If the filter circuit does not include the second filter circuit LC2, the other end of the second cross-capacitor group is also coupled to the output of the power conversion circuit 10 when coupled to the output of the power transmission system. Because the filter circuit does not include the second filter circuit LC2, the output of the power conversion circuit 10 is coupled to the output of the power transmission system.

[0101] In another example, the at least one cross-capacitor group Cf may include a third cross-capacitor group (not shown), one end of the third cross-capacitor group coupled to the input of the power transmission system or the input of the power conversion circuit 10, and the other end of the third cross-capacitor group coupled to the second node between two adjacent second filter inductors LT2 in the second filter circuit LC2. If the filter circuit includes the first filter circuit LC1, when one end of the third cross-capacitor group is coupled to the input of the power transmission system, it is also coupled to the input of the first filter circuit LC1. When one end of the third cross-capacitor group is coupled to the input of the power conversion circuit 10, it is also coupled to the output of the first filter circuit LC1. If the filter circuit does not include the first filter circuit LC1, when the other end of the second cross-capacitor group is coupled to the input of the power transmission system, it is also coupled to the input of the power conversion circuit 10 (because the filter circuit does not include the first filter circuit LC1, the input of the power conversion circuit 10 is coupled to the input of the power transmission system).

[0102] It should be noted that the power transmission system of the present embodiment may include one, two, or more cross-capacitor groups described in the above embodiment. Furthermore, in addition to the first through seventh cross-capacitor groups, the locations of the ends of the cross-capacitor groups may also be selected. Furthermore, the specific connection methods for the ends of each of the first through seventh cross-capacitor groups are applicable to the two connection methods described in the power transmission system of the first embodiment.

[0103] 4 to 9 , the circuit transmission system's filter circuit includes a first filter circuit LC1 and a second filter circuit LC2. It is understood that the circuit transmission system's filter circuit may also include only the first filter circuit LC1 or only the second filter circuit LC2.

[0104] When the filter circuit includes only the first filter circuit LC1, the first filter inductor LT1 includes a first common-mode inductor T1 or includes a first differential-mode inductor L1 and a second differential-mode inductor L2. The output of the power conversion circuit 10 is coupled to the output of the power transmission system. One end of each cross-capacitor group is coupled to the first filter circuit LC1, and the other end of the cross-capacitor group is coupled to the output of the power transmission system or the output of the power conversion circuit 10. For example, one end of the cross-capacitor group is coupled to the input of the first filter circuit LC1 (i.e., the input of the power transmission system). When the first filter circuit LC1 includes two adjacent first filter inductors LT1, one end of the cross-capacitor group may also be coupled to the first node between the two adjacent first filter inductors LT1. Furthermore, if necessary, one end of the cross-capacitor group may also be coupled to the output of the first filter circuit LC1 (i.e., the input of the power conversion circuit 10).

[0105] When the filter circuit includes only the second filter circuit LC2, the second filter inductor LT2 includes the second common-mode inductor T2 or includes the third differential-mode inductor L3 and the fourth differential-mode inductor L4. The input of the power conversion circuit 10 is coupled to the input of the power transmission system. One end of each cross-capacitor group is coupled to the input of the power transmission system and the other end is coupled to the second filter circuit LC2. For example, the other end of the cross-capacitor group is coupled to the output of the second filter circuit LC2 (i.e., the output of the power transmission system). When the second filter circuit LC2 includes two adjacent second filter inductors LT2, the other end of the cross-capacitor group may also be coupled to the second node between the two adjacent second filter inductors LT2. Furthermore, if necessary, the other end of the cross-capacitor group may also be coupled to the input of the second filter circuit LC2 (i.e., the output of the power conversion circuit 10).

[0106] In summary, the use of Y capacitors for filtering requires grounding, and the accumulation of multiple modules in the power transmission system increases the voltage. The Y capacitor needs to use a capacitor larger than Y2, which is large in size, small in capacity, and has limited filtering capability. In addition, a filter inductor with a larger inductance value needs to be selected. The inductor is large in size, resulting in a higher overall circuit cost and an impact on the architecture and thermal efficiency indicators. In the embodiment of the present application, an interference return path is formed by connecting a capacitor group across the input and output filter circuits. Most of the interference returns to the interference source (i.e., the power conversion circuit) through the return capacitor. In this way, when the external impedance is very small, there will not be a large common-mode current. For example, when performing CE testing, the common-mode current flowing through the LISN can be reduced.

[0107] In other words, for products with multiple power ports based on a non-isolated architecture, in EMC testing scenarios, namely dual / multi-LISN testing, a jumper capacitor is added between the filter circuits at the input and output ends of the power conversion circuit for filtering, forming an internal interference return path, reducing the interference current in the external loop, and thus reducing the inductance of the filter inductor, which helps to reduce the overall volume and cost of the circuit. In addition, this filtering solution does not require the addition of Y capacitors to the chassis. The capacitors in the jumper capacitor group have low withstand voltage and large capacitance, which can significantly reduce the volume and cost of the inductor. For example, in one example, the inductance of the external filter inductor can be 100-200uH, which can be reduced by 25-100 times, resulting in a significant reduction in volume and cost.

[0108] The positions of the cross-over capacitor group Cf may include, but are not limited to, the following options: Taking the filtering circuit including the first filtering circuit LC1 and the second filtering circuit LC2 as an example, as shown in FIG4 , the two ends of the first cross-over capacitor group Cf1 may be located outside the first filtering inductor LT1 and the second filtering inductor LT2, respectively; as shown in FIG8 , the two ends of the seventh cross-over capacitor group Cf9 may be located inside the first filtering inductor LT1 and the second filtering inductor LT2, respectively; as shown in FIG9 , the two ends of the fourth cross-over capacitor group Cf4 may be located between two adjacent first filtering inductors LT1 and between two adjacent second filtering inductors LT2, respectively. If necessary, the positions of the cross-over capacitor groups may also be any of the above combinations, for example, one end of the cross-over capacitor group may be located at the input or output of the first filtering circuit LC1, and the other end may be located between two adjacent second filtering inductors LT2; or one end of the cross-over capacitor group may be located at the input or output of the second filtering circuit LC2, and the other end may be located between two adjacent first filtering inductors LT1.

[0109] In addition, the specific connection methods of the two ends of the cross-capacitor group Cf can be but are not limited to the following two connection methods: the first connection method - as shown in Figures 4, 6, 8 and 9, one end of the first capacitor group in the cross-capacitor group is coupled to one of the positive and negative poles of the input end of the power transmission system, and the other end of the first capacitor group in the cross-capacitor group is coupled to one of the positive and negative poles of the output end of the power transmission system; one end of the second capacitor group in the cross-capacitor group is coupled to the other of the positive and negative poles of the input end of the power transmission system, and the other end of the second capacitor group in the cross-capacitor group is coupled to the positive and negative poles of the output end of the power transmission system. Alternatively, the first capacitor group and / or the second capacitor group of the cross-capacitor group may each include one capacitor or more than two capacitors, and the more than two capacitors may be connected in series or in parallel; the second connection method - as shown in Figure 7, the cross-capacitor group includes a third capacitor group Cf1'" arranged at the input end of the power transmission system and a fourth capacitor group Cf1"" arranged at the output end of the power transmission system, and the third capacitor group Cf1'" and the fourth capacitor group Cf1"" are coupled through a common point (not the ground); in addition, if necessary, the connection method of the two ends of the cross-capacitor group Cf can also be a combination of the above-mentioned connection methods.

[0110] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A power transmission system, characterized in that: include: A power conversion circuit, used for performing power conversion on an input electrical signal; A filter circuit, comprising a first filter circuit and a second filter circuit; at least one cross-capacitor bank; in, The filter circuit includes the first filter circuit and the second filter circuit, the input end of the first filter circuit is coupled to the input end of the power transmission system, the output end of the first filter circuit is coupled to the input end of the power conversion circuit, and the first filter circuit is used to filter the electrical signal generated after the power conversion circuit performs power conversion at the input end of the power transmission system; the input end of the second filter circuit is coupled to the output end of the power conversion circuit, the output end of the second filter circuit is coupled to the output end of the power transmission system, and the second filter circuit is used to filter the electrical signal generated after the power conversion circuit performs power conversion at the output end of the power transmission system; One end of each cross-capacitor group is coupled to the first filter circuit, and the other end is coupled to the second filter circuit; The first filter circuit includes a first filter inductor, and the second filter circuit includes a second filter inductor. The first filter inductor is a first differential mode inductor, and the second filter inductor is a second differential mode inductor.

2. The power transmission system according to claim 1, wherein: Each cross-capacitor bank is not grounded.

3. The power transmission system according to claim 1 or 2, characterized in that: Each cross-connected capacitor group includes a third capacitor group and a fourth capacitor group, the third capacitor group includes a first capacitor and a second capacitor connected in series between the positive electrode of the input end of the power transmission system and the negative electrode of the input end of the power transmission system; the fourth capacitor group includes a third capacitor and a fourth capacitor connected in series between the positive electrode of the output end of the power transmission system and the negative electrode of the output end of the power transmission system, and the intermediate node between the first capacitor and the second capacitor is coupled to the intermediate node between the third capacitor and the fourth capacitor.

4. The power transmission system according to claim 1 or 2, characterized in that: The at least one cross-over capacitor group includes a first cross-over capacitor group, one end of the first cross-over capacitor group is coupled to the input end of the power transmission system, and the other end of the first cross-over capacitor group is coupled to the output end of the power transmission system; The cross-capacitor group includes: a first capacitor group, one end of which is coupled to the positive electrode of the input end of the power transmission system and one of the negative electrode of the input end of the power transmission system, and the other end of which is coupled to the positive electrode of the output end of the power transmission system and one of the negative electrode of the output end of the power transmission system; and / or, a second capacitor group, one end of the second capacitor group is coupled to the other of the positive electrode of the input end of the power transmission system and the negative electrode of the input end of the power transmission system, and the other end of the second capacitor group is coupled to the other of the positive electrode of the output end of the power transmission system and the negative electrode of the output end of the power transmission system; The first capacitor group and the second capacitor group each include one capacitor or more than two capacitors, and the more than two capacitors are connected in series or in parallel.

5. The power transmission system according to any one of claims 1 to 4, characterized in that: The first filter circuit includes a first filter capacitor and one or more first filter inductors connected in series, the input end of the one or more first filter inductors connected in series is the input end of the first filter circuit, the output end of the one or more first filter inductors connected in series is the output end of the first filter circuit, the first filter capacitor is arranged at at least one of the input end of the first filter circuit, the output end of the first filter circuit and at least two adjacent first filter inductors, and one end of the first filter capacitor is coupled to the positive electrode of the input end of the power transmission system, and the other end is coupled to the negative electrode of the input end of the power transmission system; and / or, The second filtering circuit includes a second filtering capacitor and one or more second filtering inductors connected in series, the input end of the one or more second filtering inductors connected in series is the input end of the second filtering circuit, the output end of the one or more second filtering inductors connected in series is the output end of the second filtering circuit, the second filtering capacitor is arranged at at least one of the input end of the second filtering circuit, the output end of the second filtering circuit and at least two adjacent second filtering inductors, and one end of the second filtering capacitor is coupled to the positive pole of the output end of the power transmission system, and the other end is coupled to the negative pole of the output end of the power transmission system.

6. The power transmission system according to any one of claims 1 to 5, characterized in that: The electric signal received by the input end of the power transmission system is a direct current signal, and the power conversion circuit is used to convert the direct current signal into another direct current signal or into an alternating current signal; or, The electric signal received by the input end of the power transmission system is an alternating current signal, and the power conversion circuit is used to convert the alternating current signal into a direct current signal.

7. A power generation system, characterized in that: include: A power supply device, used for providing an electrical signal, wherein the electrical signal is a direct current signal or an alternating current signal; According to any one of claims 1 to 6, the input end of the power transmission system is capable of receiving the electrical signal output by the power supply device.

8. The power generation system according to claim 7, characterized in that: The power supply device is a photovoltaic panel, which is used to convert received sunlight into electrical energy to provide a direct current signal. The power conversion circuit includes: A power optimizer is used to perform power optimization to convert the direct current signal provided by the photovoltaic panel into a direct current signal that outputs maximum power.

9. The power generation system according to claim 7, characterized in that: The power supply device is an AC power grid, the AC power grid is used to provide an AC power signal, and the power conversion circuit is used to convert the AC power signal into a DC power signal.

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