Relay magnetic field control structure and photovoltaic inverter

Abstract

The utility model discloses a relay magnetic field control structure and a photovoltaic inverter, and relates to the technical field of photovoltaic grid-connected inverters. The relay magnetic field control structure comprises a first relay and a second relay, the second relay is arranged adjacent to the first relay along a preset direction and is arranged opposite to the first relay; the first relay and the second relay form a magnetic field counteracting unit; and a Hall sensor. The utility model solves the problems that the DCI current sampling in the current photovoltaic inverter generally has deviation, the main reason is that in the design indexes of the inverter, relays are required to be used for breaking at the output end and the power grid end of an inverter circuit respectively, and a DCI sampling hall is also arranged at the output end of the inverter, so that the hall is usually placed close to the relays to reduce the layout area; and meanwhile, the Hall is a magnetic device, and a magnetic field is generated when the relay works, so that the DCI sampling Hall is influenced by the magnetic field generated when the plurality of relays work.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic grid-connected inverters, in particular to a relay magnetic field control structure and a photovoltaic inverter. Background Art

[0002] DCI (Direct Current Injection) is direct current injection. In the national standard GBT30427-2013 Technical Requirements for Grid-connected Photovoltaic Power Generation Inverters, the DC component stipulates that during rated operation, the DC current component fed by the inverter to the grid should not exceed 0.5% of its output current rating or 5mA, whichever is greater. Reducing the DCI of the grid-connected current can make the photovoltaic power generation system safely and efficiently connected to the grid.

[0003] At present, there are common deviations in DCI current sampling in photovoltaic inverters. The main reason is that in the inverter design indicators, relays are required to be used for disconnection at the inverter circuit output end and the grid end respectively. In addition, the DCI sampling Hall is also at the inverter output end. Usually, in order to reduce the layout area, the Hall is placed close to the relay. At the same time, the Hall is a magnetic device. When the relay is working, it will generate a magnetic field, which will cause the DCI sampling Hall to be affected by the magnetic field generated by the operation of multiple relays. There is no effective solution to the above problems. Utility Model Content

[0004] Purpose of the utility model: to provide a relay magnetic field control structure and a photovoltaic inverter to solve the above-mentioned problems existing in the prior art.

[0005] Technical solution: A relay magnetic field control structure, comprising: a first relay; a second relay, arranged adjacent to the first relay along a preset direction and arranged opposite to the first relay; the first relay and the second relay form a magnetic field compensation unit; and a Hall sensor, arranged around the magnetic field compensation unit, and forming an inverter output unit with the magnetic field compensation unit; wherein the coil current direction of the first relay is opposite to the coil current direction of the second relay, so that the magnetic field formed by the first relay offsets or weakens the magnetic field formed by the second relay.

[0006] Preferably, the power polarity of the first relay is opposite to the power polarity of the second relay.

[0007] Preferably, when the Hall sensor and the first relay are arranged at a preset distance, a power supply current of the first relay close to the Hall sensor is smaller than a power supply current of the second relay far from the Hall sensor.

[0008] Preferably, the power supply current of the first relay is consistent with the power supply current of the second relay.

[0009] Preferably, the coil of the first relay is arranged opposite to the coil of the second relay.

[0010] Preferably, the Hall sensor, the first relay and the second relay are arranged in sequence from the output end of the inverter circuit to the input end of the power grid.

[0011] Preferably, the distance between the Hall sensor and the first relay is less than 20 mm.

[0012] Preferably, when the magnetic field compensation unit has a residual magnetic field, the direction of the magnetic field is opposite to that of the magnetic field formed by the Hall sensor.

[0013] Preferably, the number of the magnetic field compensation units is multiple groups, and the multiple groups of magnetic field compensation units are arranged in an orderly array between the inverter circuit and the power grid circuit in a direction perpendicular to the preset direction.

[0014] In order to achieve the above objective, according to another aspect of the present application, a photovoltaic inverter is also provided.

[0015] The photovoltaic inverter according to the present application includes the relay magnetic field control structure as described above;

[0016] It also includes: when the photovoltaic inverter is single-phase, the two groups of magnetic field compensation units are respectively electrically connected between the output end of the inverter circuit and the input end of the AC filter circuit, and the two groups of magnetic field compensation units are respectively arranged opposite to each other; a Hall sensor is arranged between the output end of the inverter circuit and any one of the magnetic field compensation units, the input end of the inverter circuit is electrically connected to the output end of the boost circuit, and the input end of the boost circuit is electrically connected to the output end of the DC filter circuit; the AC filter circuit is electrically connected to the grid side.

[0017] In order to achieve the above objective, according to another aspect of the present application, a photovoltaic inverter is also provided.

[0018] The photovoltaic inverter according to the present application includes the relay magnetic field control structure as described above;

[0019] It also includes: when the photovoltaic inverter is multi-phase, several groups of the magnetic field compensation units are respectively electrically connected between the output end of the inverter circuit and the input end of the AC filter circuit, and two groups of the magnetic field compensation units are respectively arranged opposite to each other; Hall sensors are respectively arranged between the output end of the inverter circuit and the several groups of the magnetic field compensation units, the input end of the inverter circuit is electrically connected to the output end of the boost circuit, and the input end of the boost circuit is electrically connected to the output end of the DC filter circuit; the AC filter circuit is electrically connected to the grid side;

[0020] The number of phases of the photovoltaic inverter matches the number of inverter output units formed by the Hall sensor and the magnetic field compensation unit.

[0021] Beneficial effect: In the embodiment of the present application, the direction of the relay current is controlled, and the direction of the coil current of the first relay is opposite to the direction of the coil current of the second relay, so that the magnetic field formed by the first relay and the magnetic field formed by the second relay offset or weaken each other, thereby achieving the purpose of reducing the influence of the relay magnetic field on the DCI sampling Hall by controlling the relay current direction, thereby achieving the technical effect of improving the detection accuracy of the Hall sensor, and further solving the current problem of widespread deviation in DCI current sampling in photovoltaic inverters. The main reason is that in the inverter design indicators, relays are required to be used for disconnection at the inverter circuit output end and the grid end respectively, and the DCI sampling Hall is also at the inverter output end. Usually, in order to reduce the layout area, the Hall is placed close to the relay; at the same time, the Hall is a magnetic device, and a magnetic field will be generated when the relay is working, which will lead to the technical problem that the DCI sampling Hall is affected by the magnetic field generated by the operation of multiple relays. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the conventional layout diagram of the existing inverter;

[0023] Figure 2 It is a schematic diagram of the relay magnetic field control structure of the utility model;

[0024] Figure 3 It is another schematic diagram of the relay magnetic field control structure of the utility model;

[0025] Figure 4 It is a schematic diagram of the relay magnetic field control structure of the utility model applied to a single-phase inverter circuit;

[0026] Figure 5 It is a schematic diagram of the relay magnetic field control structure of the utility model being applied to a multi-phase inverter circuit.

[0027] The figures are marked as follows: 1. first relay; 2. second relay; 3. magnetic field compensation unit; 4. Hall sensor; 5. inverter output unit; 6. AC filter circuit; 7. boost circuit; 8. DC filter circuit; 9. inverter circuit. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0031] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] like Figure 2 As shown, the present application relates to a relay magnetic field control structure and a photovoltaic inverter. The relay magnetic field control structure includes: a first relay 1; a relay is an electrically controlled switching device that can control the opening and closing of one or more circuits through electromagnetic principles. It consists of an electromagnetic coil, a fixed iron core and one or more movable contacts. When current passes through the electromagnetic coil of the relay, the generated magnetic field attracts or releases the movable contacts, causing the contacts to open or close the circuit. Therefore, the current or signal of one circuit can be controlled to another circuit.

[0033] The second relay 2 is arranged adjacent to the first relay 1 along a preset direction and is arranged opposite to the first relay 1; by connecting the first relay 1 and the second relay 2 to the circuit adjacent to each other in the preset direction and arranging them opposite to each other, it is possible to connect the two relays to the circuit according to preset requirements; wherein the preset direction can be the horizontal direction shown in the figure.

[0034] The first relay 1 and the second relay 2 form a magnetic field compensation unit 3; by setting the two relays as above, it is possible to form a unit in which the magnetic fields cancel each other out, thereby providing a basis and guarantee for the subsequent reduction or compensation of the magnetic field.

[0035] The Hall sensor 4 is arranged around the magnetic field compensation unit 3 and forms an inverter output unit 5 with the magnetic field compensation unit 3; the Hall sensor 4 is a sensor that uses the Hall effect to detect and measure the magnetic field; the Hall effect refers to the voltage difference caused by the electromagnetic field generated when the current flows through the semiconductor material with uneven carrier density. It can achieve a good sampling effect for DCI.

[0036] Specifically, the Hall sensor 4 includes a Hall element, which is a semiconductor device that is usually placed in a magnetic field to measure the strength of the magnetic field or detect changes in the magnetic field. When the magnetic field exerts an influence on the Hall element, it generates a voltage signal, and the magnitude of the signal is proportional to the strength of the magnetic field.

[0037] The coil current direction of the first relay 1 is opposite to the coil current direction of the second relay 2, so that the magnetic field formed by the first relay 1 offsets or weakens the magnetic field formed by the second relay 2. By presetting the coil current direction of the first relay 1 and the coil current direction of the second relay 2 to be opposite, the magnetic fields formed by the two relays can be offset or weakened, thereby reducing the effect of the relay magnetic field on the DCI sampling Hall, and further improving the detection accuracy of the Hall sensor 4.

[0038] The main current solutions are to directly calibrate the DCI sampling or adjust the layout of the relay and the Hall to reduce the impact of the relay magnetic field on the Hall; however, the former will result in a larger calibration compensation value, and the latter will result in a significant change in the existing component layout, affecting the product development cycle. This application reduces the impact of the magnetic field generated by the relay on the DCI Hall by optimizing the power supply direction of the relay without changing the PCB layout.

[0039] The present application changes the power supply direction of each relay, thereby changing the magnetic field direction of each relay, so that the magnetic fields flowing through the Hall of the relay cancel each other out, thereby reducing the influence of the relay magnetic field on the DCI sampling Hall.

[0040] Specifically, Figure 1 As shown in the figure, the conventional layout of the inverter (the Hall position can be placed in the four directions of the relay, top, bottom, left, and right, and the example only lists the scene where the Hall is on the left side of the relay), the current direction of multiple relay coils is consistent, and the DCI sampling Hall is near the relay. When the relay current direction is consistent, the magnetic field at the Hall is superimposed in the same direction, which has a greater impact on DCI sampling. Among them, the arrow is the direction of the relay coil current.

[0041] like Figure 2-3 As shown in the figure, by changing the direction of the relay coil current (the Hall position can be placed in the upper, lower, left, and right directions of the relay, and the example only lists the scene where the Hall is on the left side of the relay), the magnetic fields of different relays can be made to have opposite directions at the Hall position, thereby reducing the influence of the relay magnetic field on DCI sampling. Among them, the arrow is the direction of the relay coil current.

[0042] Since each relay has a different position relative to the Hall and is affected by the surrounding environment, the intensity of the influence of the magnetic field of each relay on the Hall is inconsistent; by adjusting the coil current of each relay, the influence of the magnetic field on the Hall can be further reduced.

[0043] From the above description, it can be seen that the present application achieves the following technical effects:

[0044] In the embodiment of the present application, the direction of the relay current is controlled so that the direction of the coil current of the first relay 1 is opposite to the direction of the coil current of the second relay 2, so that the magnetic field formed by the first relay 1 and the magnetic field formed by the second relay 2 offset or weaken each other, thereby achieving the purpose of reducing the influence of the relay magnetic field on the DCI sampling Hall by controlling the direction of the relay current, thereby achieving the technical effect of improving the detection accuracy of the Hall sensor 4, and further solving the problem that the DCI current sampling in the photovoltaic inverter is generally biased. The main reason is that in the inverter design indicators, relays are required to be used for disconnection at the inverter circuit output end and the grid end respectively, and the DCI sampling Hall is also at the inverter output end. Usually, in order to reduce the layout area, the Hall is placed close to the relay; at the same time, the Hall is a magnetic device, and a magnetic field will be generated when the relay is working, which will lead to the technical problem that the DCI sampling Hall is affected by the magnetic field generated by the operation of multiple relays.

[0045] Furthermore, the power polarity of the first relay 1 is opposite to the power polarity of the second relay 2. It is understandable that by adjusting the power polarity of the relay, the effect of changing the relay current can also be achieved, thereby obtaining a specified relay current flow direction, for example: connecting the positive and negative poles of the power supply to the other end of the coil, the current direction will be opposite.

[0046] Preferably, when the Hall sensor and the first relay are arranged at a preset distance, a power supply current of the first relay close to the Hall sensor is smaller than a power supply current of the second relay far from the Hall sensor.

[0047] Specifically, when the margin between the Hall sensor and the relay is within 20mm, the DCI will be interfered by 2mA to 150mA. Of course, the interference intensity will also vary due to different Hall sensors; for example: in the current test environment, the margin between the first relay 1 and the second relay 2 is 2.45mm, the margin between the first relay 1 and the Hall sensor 4 is 1.95mm, and the interference to the DCI is 87.8mA.

[0048] pass Figure 1 to Figure 2 By adjusting the current direction, the DCI impact can be optimized by about 55%, and other current direction adjustments can be optimized by 10% to 30%; for example: located above, below or to the right of the relay; for example: in the current test environment, the power supply of the second relay 2 is reversed, and the interference to DCI is reduced from 87.8mA to 40mA.

[0049] By appropriately reducing the current of the relay with greater impact or increasing the current of the relay with less impact, the DCI impact can be further optimized by about 20%. For example: when the current of the relay close to the Hall sensor is too large, it will have a greater impact on the Hall sensor detection, so the current of the relay can be reduced to reduce the impact of the magnetic field generated by the relay on the Hall sensor; at the same time, the current of the relay far away from the Hall sensor can also be increased. Because of its farther distance, the Hall sensor is less affected by its magnetic field. At this time, the current of the relay can be increased to generate a larger magnetic field, thereby offsetting or weakening the magnetic field generated by the other relay, so the DCI impact can be further optimized. For example: in the current test environment, after the power supply of the second relay 2 is reversed, the power supply current increases from 62.5mA to 71mA, and the interference to DCI is reduced from 40mA to 32mA.

[0050] Furthermore, the power supply current of the first relay 1 is consistent with the power supply current of the second relay 2. It can be understood that a good magnetic field weakening or offsetting effect can be ensured. Furthermore, on the basis of changing the power supply direction of the relay, the magnetic field strength of each relay is adjusted by adjusting the power supply current of different relays, and the magnetic field offset amount of the relay flowing through the Hall is further increased, thereby reducing the influence of the relay magnetic field on the DCI Hall.

[0051] Furthermore, the coil of the first relay 1 is arranged relative to the coil of the second relay 2. It can be understood that by arranging the coil of the first relay 1 relative to the coil of the second relay 2, it is possible to ensure that the magnetic fields formed by the two relays are also in a relative state, thereby providing a guarantee for the subsequent magnetic field reduction or offset.

[0052] Furthermore, the Hall sensor 4, the first relay 1 and the second relay 2 are sequentially arranged from the output end of the inverter circuit 9 to the input end of the power grid. It can be understood that a good optimization effect can be achieved, thereby improving the detection accuracy of the Hall sensor 4.

[0053] Furthermore, the distance between the Hall sensor 4 and the first relay 1 is less than 20 mm. It can be understood that a compact structure can be achieved, thereby reducing the layout area.

[0054] Further, when the magnetic field compensation unit 3 has a residual magnetic field, the direction of the magnetic field is opposite to that of the magnetic field formed by the Hall sensor 4. It can be understood that the effect of further reducing the influence of the magnetic field on the Hall sensor 4 can be achieved.

[0055] Furthermore, the number of the magnetic field compensation units 3 is multiple groups, and the multiple groups of magnetic field compensation units 3 are arranged in an orderly array between the inverter circuit 9 and the power grid circuit in a direction perpendicular to the preset direction. It can be understood that the effect of multi-phase magnetic field control can be achieved respectively, thereby achieving the effect of reducing the influence of the magnetic field on the Hall sensor 4.

[0056] like Figure 4 As shown, the present application also relates to a photovoltaic inverter, including the relay magnetic field control structure as described above; and further comprising: when the photovoltaic inverter is single-phase, the two groups of magnetic field compensation units 3 are respectively electrically connected between the output end of the inverter circuit 9 and the input end of the AC filter circuit 6, and the two groups of magnetic field compensation units 3 are respectively arranged opposite to each other; a Hall sensor 4 is arranged between the output end of the inverter circuit 9 and any one of the magnetic field compensation units 3, the input end of the inverter circuit 9 is electrically connected to the output end of the boost circuit 7, and the input end of the boost circuit 7 is electrically connected to the output end of the DC filter circuit 8; the AC filter circuit 6 is electrically connected to the grid side. It can be understood that when the structure of the present application is applied to a single-phase inverter, by connecting two groups of adjacently arranged relay groups to the output end of the inverter circuit 9 respectively, and setting the Hall sensor 4 at the front end of any one of the relay groups, and at the same time, applying opposite current directions to the relays of the same group, it is possible to reduce the problem of the magnetic field generated by the relay affecting the detection accuracy of the Hall sensor 4.

[0057] like Figure 5As shown, the present application also relates to a photovoltaic inverter, including the relay magnetic field control structure as described above; and further including: when the photovoltaic inverter is multi-phase, several groups of the magnetic field compensation units 3 are respectively electrically connected between the output end of the inverter circuit 9 and the input end of the AC filter circuit 6, and the two groups of the magnetic field compensation units 3 are respectively arranged opposite to each other; Hall sensors 4 are respectively arranged between the output end of the inverter circuit 9 and the several groups of the magnetic field compensation units 3, the input end of the inverter circuit 9 is electrically connected to the output end of the boost circuit 7, and the input end of the boost circuit 7 is electrically connected to the output end of the DC filter circuit 8; the AC filter circuit 6 is electrically connected to the grid side;

[0058] Among them, the number of phases of the photovoltaic inverter matches the number of inverter output units 5 formed by the Hall sensor 4 and the magnetic field compensation unit 3. It can be understood that when the structure of the present application is applied to a multi-phase inverter, by connecting several groups of adjacent relay groups to the output end of the inverter circuit 9, and setting the Hall sensors 4 at the front end of the relay groups, and at the same time, applying opposite current directions to the relays of the same group, it is possible to reduce the problem of the magnetic field generated by the relay affecting the detection accuracy of the Hall sensor 4. Among them, the number of phases of the photovoltaic inverter matches the number of inverter output units 5 formed by the Hall sensor 4 and the magnetic field compensation unit 3; a good matching effect can be achieved, so that the influence of the relay magnetic field on the DCI sampling Hall can be reduced.

[0059] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. Relay magnetic field control structure, characterized in that, include: First relay; a second relay, arranged adjacent to the first relay along a preset direction and arranged opposite to the first relay; The first relay and the second relay form a magnetic field compensation unit; and A Hall sensor is arranged around the magnetic field compensation unit and forms an inverter output unit with the magnetic field compensation unit; The direction of the coil current of the first relay is opposite to the direction of the coil current of the second relay, so that the magnetic field formed by the first relay and the magnetic field formed by the second relay offset or weaken each other.

2. The relay magnetic field control structure according to claim 1, characterized in that: The power polarity of the first relay is opposite to the power polarity of the second relay.

3. The relay magnetic field control structure according to claim 1, characterized in that: When the Hall sensor and the first relay are arranged at a preset distance, a power supply current of the first relay close to the Hall sensor is smaller than a power supply current of the second relay far from the Hall sensor.

4. The relay magnetic field control structure according to claim 1, characterized in that: The magnitude of the power supply current of the first relay is consistent with the magnitude of the power supply current of the second relay.

5. The relay magnetic field control structure according to claim 1, characterized in that: The coil of the first relay is arranged opposite to the coil of the second relay.

6. The relay magnetic field control structure according to claim 1, characterized in that: The Hall sensor, the first relay and the second relay are arranged in sequence from the output end of the inverter circuit to the input end of the power grid.

7. The relay magnetic field control structure according to claim 6, characterized in that: The distance between the Hall sensor and the first relay is less than 20 mm.

8. The relay magnetic field control structure according to claim 1, characterized in that: When the magnetic field cancellation unit has a residual magnetic field, the direction of the magnetic field is opposite to that of the magnetic field formed by the Hall sensor.

9. The relay magnetic field control structure according to claim 1, characterized in that: The number of the magnetic field compensation units is multiple groups, and the multiple groups of magnetic field compensation units are arranged in an orderly array between the inverter circuit and the power grid circuit in sequence along a direction perpendicular to the preset direction.

10. A photovoltaic inverter, characterized in that: comprising a relay magnetic field control structure as claimed in any one of claims 1 to 9; It also includes: when the photovoltaic inverter is single-phase, the two groups of magnetic field compensation units are respectively electrically connected between the output end of the inverter circuit and the input end of the AC filter circuit, and the two groups of magnetic field compensation units are respectively arranged opposite to each other; a Hall sensor is arranged between the output end of the inverter circuit and any one of the magnetic field compensation units, the input end of the inverter circuit is electrically connected to the output end of the boost circuit, and the input end of the boost circuit is electrically connected to the output end of the DC filter circuit; the AC filter circuit is electrically connected to the grid side.

11. A photovoltaic inverter, characterized in that: comprising a relay magnetic field control structure as claimed in any one of claims 1 to 9; It also includes: when the photovoltaic inverter is multi-phase, several groups of the magnetic field compensation units are respectively electrically connected between the output end of the inverter circuit and the input end of the AC filter circuit, and two groups of the magnetic field compensation units are respectively arranged opposite to each other; Hall sensors are respectively arranged between the output end of the inverter circuit and the several groups of the magnetic field compensation units, the input end of the inverter circuit is electrically connected to the output end of the boost circuit, and the input end of the boost circuit is electrically connected to the output end of the DC filter circuit; the AC filter circuit is electrically connected to the grid side; The number of phases of the photovoltaic inverter matches the number of inverter output units formed by the Hall sensor and the magnetic field compensation unit.

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