Lightning protection circuit for variable frequency driver of water pump

Abstract

The utility model discloses a lightning protection circuit for a variable frequency driver of a water pump, and belongs to the technical field of water pump control circuits. The technical problem that a variable frequency driver is damaged when working in a thunder and lightning weather environment is solved. The main points of the technical scheme are that the inverter comprises a rectification current and an inverter circuit, the rectification circuit is provided with input ends R, S and T, the inverter circuit is provided with output ends U, V and W, the output ends of the inverter circuit are connected with a lightning protection circuit, and the lightning protection circuit comprises a plurality of lightning protection groups, three access ends and a grounding end. Each lightning protection group comprises a piezoresistor and a safety capacitor which are mutually connected in parallel, one lightning protection group is connected between every two of the three access ends, one lightning protection group is arranged between each of the three access ends and the grounding point, and the three access ends are respectively connected with the U end, the V end and the W end. The lightning protection device has the effects of remarkable lightning protection effect and safe and reliable work.

Description

Technical Field

[0001] The present application relates to the technical field of variable frequency drive protection circuits, and in particular to a variable frequency drive lightning protection circuit for a water pump. Background Art

[0002] In actual applications, the variable frequency drive of the water pump is often damaged by lightning strikes or surges. The reason for the damage is that the lightning protection measures are not in place. Usually, there are no lightning protection measures at the output end of the variable frequency drive, so many lightning damages to the variable frequency drive are caused by the output end being affected by lightning. In addition, the lightning protection measures at the input end of the variable frequency drive are also insufficient, which will also cause damage to the variable frequency drive when lightning strikes and surges are severe.

[0003] When the variable frequency drive of the water pump is far away from the underground water pump motor and other equipment, lightning strikes are more likely to directly act on the cable between the variable frequency drive and the water pump. If lightning strikes nearby, a high induced voltage will also be generated on ordinary cables, and the overvoltage will act on the inverter circuit of the variable frequency drive, causing damage to the inverter circuit and related components.

[0004] like Figure 1 As shown in the figure, the main circuit topology of a conventional variable frequency drive has R, S, and T terminals as the input side, which are rectified by the rectifier circuit, and then converted into AC power by the inverter circuit. The output of the inverter circuit is U, V, and W terminals, and the output terminal is connected to the water pump motor. The inverter circuit is controlled by the main control circuit.

[0005] The problem that needs to be solved is how to avoid the impact of lightning on their work. Utility Model Content

[0006] In view of the above-mentioned shortcomings (problems) of the prior art, in order to effectively avoid the destructive effects of lightning weather on circuit operation, the present application provides a variable frequency drive lightning protection circuit for a water pump.

[0007] To achieve the above-mentioned purpose and other related purposes, the present application adopts the following technical solutions: a variable frequency drive lightning protection circuit for a water pump, including a rectifier current and an inverter circuit, the rectifier circuit having input terminals R, S, and T, the inverter circuit having output terminals U, V, and W, and a lightning protection circuit is connected to the output terminal of the inverter circuit, the lightning protection circuit including multiple lightning protection groups, three access terminals and a ground terminal, each lightning protection group is a varistor and a safety capacitor connected in parallel with each other, a lightning protection group is connected between two of the three access terminals, a lightning protection group is arranged between each of the three access terminals and the grounding point, and the three access terminals are respectively connected to the U, V, and W terminals.

[0008] Optionally, the input end of the rectifier circuit is connected to a second lightning protection circuit.

[0009] Optionally, three access terminals of the second lightning protection circuit are connected to R, S, and T terminals respectively.

[0010] In summary, the present application includes at least one of the following beneficial technical effects:

[0011] 1. The surge current and lightning impact are absorbed by varistors and safety capacitors, thereby improving the working reliability and safety of the variable frequency drive;

[0012] 2. Lightning protection circuits are set at both the input and output ends to maximize the safety and reliability of circuit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a circuit diagram of a variable frequency drive applied in an embodiment of the present application;

[0014] Figure 2 is a schematic diagram of a lightning protection circuit on the input side of an embodiment of the present application;

[0015] Figure 3 It is a schematic diagram of a lightning protection circuit on the output side of an embodiment of the present application.

[0016] Description of main reference numerals:

[0017] 100, rectifier current; 200, inverter circuit; 3, lightning protection circuit; 31, lightning protection group; 311, varistor; 312, safety capacitor. DETAILED DESCRIPTION

[0018] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0019] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0020] The specific implementation methods of the present application will be further described below in conjunction with the accompanying drawings.

[0021] Example:

[0022] The present application embodiment discloses a lightning protection circuit for a variable frequency drive of a water pump. In the known circuit of the variable frequency drive of the water pump, the circuit includes a rectifier circuit 100 and an inverter circuit 200. The rectifier circuit has input terminals R, S, and T, and the inverter circuit 200 has output terminals U, V, and W. Figure 1 As shown, the above part is existing, and further explained, the output of the rectifier circuit part has a P+ terminal and a DC- terminal, and the P+ terminal can be connected to the DC+ terminal on the inverter circuit 200. The inverter circuit 200 is also connected to the control circuit. The output of the inverter circuit 200 is connected to the motor M, that is, the variable frequency speed regulation of the motor is realized.

[0023] The advantages of this solution are: a lightning protection circuit 3 is connected to the output end of the inverter circuit 200, and the lightning protection circuit 3 includes multiple lightning protection groups 31, three access terminals and a ground terminal. Each lightning protection group 31 is a varistor 311 and a safety capacitor 312 connected in parallel with each other. A lightning protection group 31 is connected between two of the three access terminals, and a lightning protection group 31 is set between each of the three access terminals and the grounding point. The three access terminals are respectively connected to the U, V, and W terminals.

[0024] For the varistor 311 and the safety capacitor 312, refer to Figure 2 As shown, resistors RV7 - R12 are all varistors 311 , and capacitors C7 - C12 are all safety capacitors 312 .

[0025] refer to Figure 3 As shown, the input end of the rectifier circuit is connected to the second lightning protection circuit 3. The three access ends of the second lightning protection circuit 3 are connected to the R, S, and T ends respectively.

[0026] As can be seen from the above, the capacitors C1 - C6 are safety capacitors 312 , and the resistors RV1 - RV7 are varistors 311 .

[0027] In summary, the surge current and lightning impact are absorbed by the varistor 311 and the safety capacitor 312, thereby improving the working reliability and safety of the variable frequency drive; the lightning protection circuit 3 is set at both the input and output ends to maximize the circuit working safety and reliability.

[0028] The above embodiments are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A variable frequency drive lightning protection circuit for a water pump, comprising a rectifier circuit and an inverter circuit, wherein the rectifier circuit has input terminals R, S, and T, and the inverter circuit has output terminals U, V, and W, and is characterized in that: A lightning protection circuit is connected to the output end of the inverter circuit, and the lightning protection circuit includes multiple lightning protection groups, three access terminals and a ground terminal. Each lightning protection group is a varistor and a safety capacitor connected in parallel with each other. A lightning protection group is connected between two of the three access terminals, and a lightning protection group is set between each of the three access terminals and the grounding point. The three access terminals are respectively connected to the U, V, and W terminals.

2. The variable frequency drive lightning protection circuit for a water pump according to claim 1, characterized in that: The input end of the rectifier circuit is connected to a second lightning protection circuit.

3. The variable frequency drive lightning protection circuit of a water pump according to claim 2, characterized in that: The three access terminals of the second lightning protection circuit are connected to the R, S, and T terminals respectively.

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