Lightning protection module state feedback circuit suitable for direct current stacked light system

Abstract

The invention relates to the technical field of power electronics and new energy power generation, discloses a lightning protection module state feedback circuit suitable for a direct-current stacked light system, and provides a unique and ingenious high-capacity lightning protection module state feedback scheme, and a lightning protection device which is low in design cost and small in size is built by using a piezoresistor and a fuse. The circuit can be applied to a scene of parallel connection of lightning protection devices and a scene of a single lightning protection device, is flexible and variable in application scene, can be compatible with a set of feedback receiving circuit in a conventional common scheme, achieves the same series isolation feedback effect, and provides a new choice for the design of a surge module.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics and new energy power generation, and in particular to a lightning protection module state feedback circuit suitable for a DC stacked light system. Background Art

[0002] As an important part of the DC stacking system, the photovoltaic combiner box is a current collection device that can collect photovoltaic power generation for use in base station equipment. Since photovoltaic combiner boxes are usually installed outdoors and mostly installed in exposed places such as roofs, there is a very high risk of lightning strikes, so it is necessary to design a lightning protection module for the combiner box to provide surge protection. When the combiner box is struck by lightning, the lightning protection module may be damaged by overcurrent. At this time, the lightning protection module needs to feedback the fault information to the main control device. After the main control device reports, the maintenance personnel will repair and replace the lightning protection module. Since the flow rate of a single lightning protection device is limited, in order to enhance the protection capability of the lightning protection module, the lightning protection devices are usually used in parallel. For example, the flow rate of a single lightning protection device is 10kA, and after two are connected in parallel, it is 20kA. Although the protection capability is enhanced, the corresponding state feedback solution needs to be additionally designed.

[0003] The most common state feedback solution for large-capacity lightning protection modules on the market is to connect two lightning protection devices in parallel and use an integrated lightning protection device with built-in isolated fault feedback (such as Figure 1 As shown in the figure, the manufacturer of this type of lightning protection device has designed two isolated feedback pins in the mechanical structure. When the lightning protection device is normal, the two isolated feedback pins are directly connected. When the lightning protection device is damaged, the two isolated feedback pins will be disconnected. This solution only needs to connect the feedback pins in series and then lead out two wires to the feedback receiving circuit. The feedback receiving circuit forms a loop with the two pins in series. When any lightning protection device is damaged, the loop is disconnected to form a feedback signal.

[0004] Although the above-mentioned lightning protection module solution is simple in design, the lightning protection device used has a high cost and a large size due to the use of a mechanical structure to isolate the feedback pin. When used in parallel, the cost and size of the lightning protection module will be greatly increased. Summary of the invention

[0005] In view of the shortcomings and defects of the prior art, the present invention provides a lightning protection module status feedback circuit suitable for a DC stacked light system. A low-cost and small-volume lightning protection device is constructed using a varistor and a fuse. The circuit can be used in scenarios where lightning protection devices are connected in parallel as well as in scenarios where a single lightning protection device is used. The circuit can be compatible with a set of feedback receiving circuits commonly used today.

[0006] The purpose of the present invention can be achieved through the following technical solutions.

[0007] A lightning protection module state feedback circuit applicable to a DC stacked light system, the circuit is applied to a photovoltaic combiner box lightning protection module, and includes a first lightning protection device, a second lightning protection device, a reverse voltage protection module, a resistance module, an optocoupler protection diode, and an optocoupler;

[0008] The reverse voltage protection module includes at least one diode; the resistance module includes at least one resistor; a first lightning protection device is constructed by using a first varistor and a first fuse; a second lightning protection device is constructed by using a second varistor and a second fuse;

[0009] One end of the first fuse is connected to one end of the second varistor, the load device and the positive power supply voltage, and the other end is connected in series with the reverse voltage protection module and one end of the first varistor; the other end of the first varistor is connected to the load device and one end of the second fuse and grounded; the other end of the second varistor is connected to the other end of the second fuse, one end of the optocoupler protection diode and one end of the optocoupler light-emitting diode; the reverse voltage protection module is connected in series with the other end of the optocoupler protection diode and the other end of the optocoupler light-emitting diode through the resistor module; the collector and emitter of the optocoupler phototransistor are connected to the feedback receiving circuit.

[0010] The beneficial technical effects of the present invention are as follows: a unique and ingenious large-capacity lightning protection module status feedback solution is provided, and a low-cost and small-volume lightning protection device is constructed using varistors and fuses. The solution can be used in scenarios where lightning protection devices are connected in parallel, as well as in scenarios where a single lightning protection device is used. The application scenarios are flexible and varied, and the solution can be compatible with a set of feedback receiving circuits in common use today to achieve the same series isolation feedback effect, providing a new option for surge module design. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The invention relates to an integrated lightning protection device with self-isolated fault feedback as described in the background technology of the invention.

[0012] Figure 2 This is a circuit topology diagram described in an embodiment of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0014] Embodiment: A state feedback scheme based on a lightning protection device with low cost, small size and simple structure. The lightning protection device is built by using a varistor and a fuse. It does not need to use an integrated lightning protection device. It can also achieve the effect of isolated feedback. It is also a series feedback and can be connected with Figure 1 The solution is compatible with the same set of feedback receiving circuits.

[0015] The lightning protection device in the embodiment of the present invention only leads to a non-isolated feedback pin, has a simple structure, and is much smaller in cost and volume than conventional lightning protection devices. Figure 1 The lightning protection device shown. When the lightning protection device fails, the fuse will blow.

[0016] The lightning protection module design provided by the embodiment of the present invention is as follows Figure 2 As shown in the figure, under normal operating conditions, the current flows as follows: positive power supply voltage VCC → first fuse FU1 → diode VD1 of the reverse voltage protection module → resistor R1 of the resistor module → optocoupler O1 → second fuse FU2 → ground GND. Since current flows through the optocoupler light-emitting diode, the other end will be turned on to form a loop with the feedback receiving circuit. When the varistor is damaged, the fuse will be damaged, the current loop will be interrupted, the other end of the optocoupler will be cut off, and the loop will be disconnected to form a feedback signal.

[0017] In this embodiment, there is only one R1 in the resistor module, but because the withstand voltage of a single resistor is limited, multiple resistors are often used in series in the actual application scenario of a large-capacity lightning protection module to more effectively withstand the residual voltage of a lightning surge. Flexible matching can be performed according to actual conditions. Similarly, multiple diodes are used in series in the reverse voltage protection module to more effectively withstand the reverse surge residual voltage. The diode VD3 connected in parallel at both ends of the optocoupler O1 is used to protect the optocoupler.

[0018] The above embodiments are descriptions of specific implementation methods of the present invention rather than limitations of the present invention. Technical personnel in the relevant technical field may make various changes and modifications to obtain corresponding equivalent technical solutions without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A lightning protection module state feedback circuit suitable for a DC stacked light system, characterized in that: The circuit is applied in a photovoltaic combiner box lightning protection module, and includes a first lightning protection device, a second lightning protection device, a reverse voltage protection module, a resistance module, an optocoupler protection diode, and an optocoupler; The reverse voltage protection module includes at least one diode; the resistance module includes at least one resistor; a first lightning protection device is constructed by using a first varistor and a first fuse; a second lightning protection device is constructed by using a second varistor and a second fuse; One end of the first fuse is connected to one end of the second varistor, the load device and the positive power supply voltage, and the other end is connected in series with the reverse voltage protection module and one end of the first varistor; the other end of the first varistor is connected to the load device and one end of the second fuse and grounded; the other end of the second varistor is connected to the other end of the second fuse, one end of the optocoupler protection diode and one end of the optocoupler light-emitting diode; the reverse voltage protection module is connected in series with the other end of the optocoupler protection diode and the other end of the optocoupler light-emitting diode through the resistor module; the collector and emitter of the optocoupler phototransistor are connected to the feedback receiving circuit.

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