A cooling fan monitoring circuit for wire feeding power supply

Abstract

The utility model discloses a cooling fan monitoring circuit for a wire feeding power supply, comprising a current sampling circuit, an amplifying buffer circuit and a voltage-current conversion output circuit connected in sequence; wherein the current sampling circuit is configured to sense the high-voltage AC working current when the cooling fan is running to generate an AC current signal, and the AC current signal is rectified and converted into a low-voltage DC voltage signal and output to the amplifying buffer circuit; the amplifying buffer circuit is configured to amplify and buffer the low-voltage DC voltage signal and eliminate errors to obtain an amplified DC voltage signal; the voltage-current conversion output circuit is configured to convert the amplified DC voltage signal into a standard DC current signal and output it to a host computer. The host computer can analyze the change in the working current of the cooling fan to determine whether the cooling fan is operating normally.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic protection, in particular to a cooling fan monitoring circuit for a wire feeding power supply. Background Art

[0002] In vacuum evaporation equipment, a high-power wire feeding power supply is required. When the wire feeding power supply is in operation, a large amount of work heat is generated, and the heat needs to be promptly extracted and discharged through multiple large-displacement fans. In actual applications, after multiple large-displacement fans have been running synchronously for a long time, some of them may be blocked or stopped. If the faulty large-displacement fan is not discovered and repaired in time, the wire feeding power supply will be shut down due to poor heat dissipation or more induced faults will be caused, affecting normal production. Utility Model Content

[0003] In view of the defects in the prior art, the utility model provides a cooling fan monitoring circuit for a wire feeding power supply, so as to realize real-time monitoring and sampling of each fan, and send the fan operating conditions to a peripheral monitoring circuit or a host computer in real time in the form of electrical signals.

[0004] A cooling fan monitoring circuit for a wire feeding power supply comprises a current sampling circuit, an amplifying buffer circuit and a voltage-current conversion output circuit connected in sequence;

[0005] The current sampling circuit is configured to sense the high-voltage AC working current when the cooling fan is running to generate an AC current signal, and then rectify the AC current signal and transform it into a low-voltage DC voltage signal to output to the amplification buffer circuit;

[0006] The amplifying and buffering circuit is configured to amplify and buffer the low-voltage DC voltage signal and eliminate errors to obtain an amplified DC voltage signal;

[0007] The voltage-current conversion output circuit is configured to convert the amplified DC voltage signal into a standard DC current signal and output it to the host computer.

[0008] Furthermore, the current sampling circuit includes a current sensor, a full-bridge rectifier circuit and a sampling resistor; the current sensor is connected to the input of the full-bridge rectifier circuit, and the sampling resistor is connected in parallel to the output of the full-bridge rectifier circuit;

[0009] The current sensor senses the high voltage AC working current when the cooling fan is running to generate an AC current signal;

[0010] The full-bridge rectifier circuit rectifies the AC current signal and converts it into a DC current signal;

[0011] The sampling resistor linearly converts the DC current signal into a DC voltage signal for output.

[0012] Furthermore, the amplifying and buffering circuit includes a DC signal amplifying circuit and a voltage follower connected in series in sequence, the DC signal amplifying circuit is connected to the output of the current sampling circuit; the voltage follower is connected to the voltage-current conversion output circuit.

[0013] Furthermore, the DC signal amplification circuit includes a first operational amplifier U1A, a negative voltage bias circuit and a proportional amplification loop, wherein:

[0014] The non-inverting terminal of the first operational amplifier U1A is connected to the output of the current sampling circuit, the negative voltage bias circuit is connected to the non-inverting terminal of the first operational amplifier U1A, and the proportional amplification loop is connected between the inverting terminal and the output terminal of the first operational amplifier U1A;

[0015] The negative voltage bias circuit is configured to adjust the negative bias voltage amplitude to increase the reference power ground GND value;

[0016] The proportional amplification loop is configured to amplify the low voltage DC voltage signal input to the non-inverting terminal of the first operational amplifier U1A.

[0017] Furthermore, the negative voltage bias circuit includes a second resistor R2, a third resistor R3, a fourth resistor R4 and a second potentiometer VR2, wherein:

[0018] The fourth resistor R4 is connected in series between the in-phase terminal of the first operational amplifier U1A and the output of the current sampling circuit;

[0019] The second resistor R2 and the fixed end of the second potentiometer VR2 are connected in series between the positive electrode of the power supply and the ground;

[0020] One end of the third resistor R3 is connected in parallel with the fourth resistor R4 to the in-phase terminal of the first operational amplifier U1A, and the other end of the third resistor R3 is connected to the variable end of the second potentiometer VR2.

[0021] Furthermore, the proportional amplification loop includes a first potentiometer VR1, a fifth resistor R5 and a sixth resistor R6, wherein:

[0022] The inverting end of the first operational amplifier U1A is connected in parallel with one end of the fifth resistor R5 and the sixth resistor R6, the other end of the fifth resistor R5 is connected to the power ground, the other end of the sixth resistor R6 is connected in series with the fixed end of the first potentiometer VR1 and the output end of the first operational amplifier U1A; the variable end of the first potentiometer VR1 is also connected to the output end of the first operational amplifier U1A.

[0023] Further, the voltage follower includes a second operational amplifier U1B, a non-inverting terminal of the second operational amplifier U1B is connected to the output of the DC signal amplifying circuit, and an inverting terminal of the second operational amplifier U1B is connected to the output terminal;

[0024] The output terminal of the second operational amplifier U1B is connected to the voltage-current conversion output circuit.

[0025] Furthermore, a seventh resistor R7 is connected in series between the in-phase terminal of the second operational amplifier U1B and the output of the DC signal amplifying circuit;

[0026] An eighth resistor R8 is connected in series between the output end of the second operational amplifier U1B and the voltage-current conversion output circuit; and a limiting protection diode DW1 is connected between the output end of the eighth resistor R8 and the ground.

[0027] Furthermore, the voltage-current conversion output circuit includes a 0-5V / 4-20mA conversion module.

[0028] The beneficial effects of the utility model are embodied in:

[0029] 1. In the present invention, the host computer can determine whether the cooling fan is operating normally by analyzing the change of the cooling fan working current. In practical applications, the normal operating current range of the cooling fan can be set to A±20%, where A is the rated current of the cooling fan. If this limit is exceeded, it is determined that the cooling fan is abnormal.

[0030] 2. The high-voltage AC working current of the cooling fan is converted into a DC4-20mA low-voltage DC standard signal output to achieve uninterrupted monitoring of the cooling fan operation. Compared with the traditional manual intermittent regular inspection method, the monitoring reliability is improved from a technical principle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation of the utility model or the technical solution in the prior art, the following is a brief introduction to the drawings required for the specific implementation or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0032] Figure 1 This is a structural block diagram of a cooling fan monitoring circuit for a wire feeding power supply provided by the utility model;

[0033] Figure 2 The utility model provides a circuit structure diagram of a cooling fan monitoring circuit for a wire feeding power supply.

[0034] In the figure: 100 is a current sampling circuit, 101 is an amplifier buffer circuit, and 102 is a voltage-current conversion output circuit. DETAILED DESCRIPTION

[0035] The following is a further detailed description of the implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0036] In the description of the present invention, unless otherwise specified, "multiple" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] like Figure 1 As shown, the utility model provides a cooling fan monitoring circuit for a wire feeding power supply, comprising a current sampling circuit 100, an amplifying buffer circuit 101 and a voltage-current conversion output circuit 102 connected in sequence. Among them, the current sampling circuit 100 is configured to sense the high-voltage AC working current when the cooling fan is running to generate an AC current signal, and rectifies the AC current signal and converts it into a low-voltage DC voltage signal and outputs it to the amplifying buffer circuit 101.

[0039] The amplifying and buffering circuit 101 is configured to amplify and buffer the low-voltage DC voltage signal and eliminate errors to obtain an amplified DC voltage signal, wherein the voltage range of the amplified DC voltage signal is 0-5V.

[0040] The voltage-current conversion output circuit 102 is configured to convert the amplified DC voltage signal into a standard DC current signal and output it to the host computer. The voltage-current conversion output circuit 102 includes a 0-5V / 4-20mA conversion module, which converts the 0-5V DC voltage signal of the previous stage into a 4-20mA standard DC current signal.

[0041] In this embodiment, the host computer can be a control device such as a PLC, a single-chip microcomputer, a DSP or a server host. The host computer can analyze the change in the working current of the cooling fan to determine whether the cooling fan is operating normally. In actual applications, the normal operating current range of the cooling fan can be set to A±20%, where A is the rated current of the cooling fan. If this limit is exceeded, it is determined that the cooling fan is abnormal.

[0042] Specifically, Figure 2 As shown, the current sampling circuit 100 includes a current sensor CS1, a full-bridge rectifier circuit composed of four diodes D1-D4 and a sampling resistor R1; the current sensor CS1 is connected to the input of the full-bridge rectifier circuit, and the sampling resistor R1 is connected in parallel to the output of the full-bridge rectifier circuit.

[0043] When the cooling fan is working, the current sensor CS1 isolates and senses the high-voltage AC working current of the cooling fan to generate a 0-10mA AC current signal. The full-bridge rectifier circuit rectifies the AC current signal and converts it into a DC current signal, that is, converts the 0-10mA AC current into a DC current. The sampling resistor R1 linearly converts the DC current signal into a DC voltage signal and outputs it to the next level circuit. In this embodiment, the current sensor CS1 adopts a current transformer.

[0044] Specifically, Figure 2 As shown, the amplifying buffer circuit 101 includes a DC signal amplifying circuit and a voltage follower connected in series in sequence. The DC signal amplifying circuit is connected to the output of the current sampling circuit 100 ; the voltage follower is connected to the voltage-current conversion output circuit 102 .

[0045] The DC signal amplification circuit includes a first operational amplifier U1A, a negative voltage bias circuit, and a proportional amplification loop. The in-phase terminal of the first operational amplifier U1A is connected to the output of the current sampling circuit 100, the negative voltage bias circuit is connected to the in-phase terminal of the first operational amplifier U1A, and the proportional amplification loop is connected between the inverting terminal and the output terminal of the first operational amplifier U1A. The negative voltage bias circuit is configured to adjust the negative bias amplitude to increase the reference power supply ground GND value and eliminate the background interference voltage signal from the current sampling circuit 100.

[0046] The proportional amplification loop is configured to moderately amplify the low voltage DC voltage signal input to the non-inverting terminal of the first operational amplifier U1A.

[0047] Specifically, Figure 2As shown, the negative voltage bias circuit includes a second resistor R2, a third resistor R3, a fourth resistor R4 and a second potentiometer VR2. The fourth resistor R4 is connected in series between the in-phase terminal of the first operational amplifier U1A and the output of the current sampling circuit 100; the second resistor R2 and the fixed end of the second potentiometer VR2 are connected in series between the positive electrode of the power supply and the ground; one end of the third resistor R3 is connected in parallel with the fourth resistor R4 at the in-phase terminal of the first operational amplifier U1A, and the other end of the third resistor R3 is connected to the variable end of the second potentiometer VR2.

[0048] The third resistor R3 and the fourth resistor R4 form an input and error elimination loop. The fourth resistor R4 is the input DC signal voltage. The third resistor R3, the second resistor R2 and the second potentiometer VR2 form a negative voltage bias circuit. The second potentiometer VR2 adjusts the negative bias voltage amplitude. The bias negative voltage can increase the reference power ground GND value and eliminate the background interference voltage signal from the current sampling circuit 100. The bias negative voltage is ANDed with the DC voltage signal from the fourth resistor R4 and then reaches the non-inverting input terminal of the first operational amplifier U1A.

[0049] The proportional amplification loop includes a first potentiometer VR1, a fifth resistor R5 and a sixth resistor R6. The inverting end of the first operational amplifier U1A is connected in parallel with one end of the fifth resistor R5 and the sixth resistor R6, the other end of the fifth resistor R5 is connected to the power ground, the other end of the sixth resistor R6 is connected in series with the fixed end of the first potentiometer VR1 and the output end of the first operational amplifier U1A; the variable end of the first potentiometer VR1 is also connected to the output end of the first operational amplifier U1A.

[0050] The sixth resistor R6 and the fifth resistor R5 form a proportional amplification loop to appropriately amplify the DC voltage signal at the in-phase end. The first potentiometer VR1 can adjust the amplification factor.

[0051] Furthermore, the voltage follower includes a second operational amplifier U1B, the in-phase terminal of the second operational amplifier U1B is connected to the output of the DC signal amplifier circuit, the inverting terminal of the second operational amplifier U1B is connected to the output terminal, and the output terminal of the second operational amplifier U1B is connected to the voltage-current conversion output circuit 102 .

[0052] The second op amp U1B is connected as a voltage emitter follower, specifically, the inverting terminal of the second op amp U1B is connected to the output terminal, and the non-inverting terminal of the second op amp U1B serves as the input terminal of the voltage follower. In practical applications, two isolation resistors R7 and R8 are provided at the input and output terminals of the voltage follower, as well as an output limiting protection diode DW1.

[0053] The above description is for a single fan monitoring circuit. When actually monitoring N cooling fans, it is necessary to calibrate the VR1 and VR2 potentiometers of each monitoring circuit and simulate the linearity of multiple currents to ensure that the accuracy and linearity of the output signal are within 2% error.

[0054] In summary, the technical solution of this application converts the high-voltage AC working current of the cooling fan into a DC4-20mA low-voltage DC standard signal output, thereby realizing uninterrupted monitoring of the operation of the cooling fan. Compared with the traditional manual intermittent regular inspection method, the monitoring reliability is improved from a technical principle perspective.

[0055] The products provided in the embodiments of the present invention are briefly described. For matters not mentioned in the embodiments, reference may be made to the corresponding contents in the aforementioned embodiments.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model, and they should all be included in the scope of the claims and specification of the utility model.

Claims

1. A cooling fan monitoring circuit for a wire feeding power supply, characterized in that: It comprises a current sampling circuit (100), an amplifying buffer circuit (101) and a voltage-current conversion output circuit (102) which are connected in sequence; The current sampling circuit (100) is configured to sense the high-voltage AC working current of the cooling fan when it is running to generate an AC current signal, and to rectify the AC current signal and convert it into a low-voltage DC voltage signal to output to the amplifying buffer circuit (101); The amplifying and buffering circuit (101) is configured to amplify and buffer the low-voltage DC voltage signal and eliminate errors to obtain an amplified DC voltage signal; The voltage-current conversion output circuit (102) is configured to convert the amplified DC voltage signal into a standard DC current signal and output it to a host computer.

2. A cooling fan monitoring circuit for a wire feeding power supply according to claim 1, characterized in that: The current sampling circuit (100) comprises a current sensor, a full-bridge rectifier circuit and a sampling resistor; the current sensor is connected to the input of the full-bridge rectifier circuit, and the sampling resistor is connected in parallel to the output of the full-bridge rectifier circuit; The current sensor senses the high voltage AC working current when the cooling fan is running to generate an AC current signal; The full-bridge rectifier circuit rectifies the AC current signal and converts it into a DC current signal; The sampling resistor linearly converts the DC current signal into a DC voltage signal for output.

3. A cooling fan monitoring circuit for a wire feeding power supply according to claim 1, characterized in that: The amplifying buffer circuit (101) comprises a DC signal amplifying circuit and a voltage follower connected in series in sequence, the DC signal amplifying circuit being connected to the output of the current sampling circuit (100); and the voltage follower being connected to the voltage-current conversion output circuit (102).

4. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 3, characterized in that: The DC signal amplification circuit includes a first operational amplifier U1A, a negative voltage bias circuit and a proportional amplification loop, wherein: The non-inverting terminal of the first operational amplifier U1A is connected to the output of the current sampling circuit (100), the negative voltage bias circuit is connected to the non-inverting terminal of the first operational amplifier U1A, and the proportional amplification loop is connected between the inverting terminal and the output terminal of the first operational amplifier U1A; The negative voltage bias circuit is configured to adjust the negative bias voltage amplitude to increase the reference power ground GND value; The proportional amplification loop is configured to amplify the low voltage DC voltage signal input to the non-inverting terminal of the first operational amplifier U1A.

5. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 4, characterized in that: The negative voltage bias circuit includes a second resistor R2, a third resistor R3, a fourth resistor R4 and a second potentiometer VR2, wherein: The fourth resistor R4 is connected in series between the non-inverting terminal of the first operational amplifier U1A and the output of the current sampling circuit (100); The second resistor R2 and the fixed end of the second potentiometer VR2 are connected in series between the positive electrode of the power supply and the ground; One end of the third resistor R3 is connected in parallel with the fourth resistor R4 to the in-phase terminal of the first operational amplifier U1A, and the other end of the third resistor R3 is connected to the variable end of the second potentiometer VR2.

6. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 4, characterized in that: The proportional amplification loop includes a first potentiometer VR1, a fifth resistor R5 and a sixth resistor R6, wherein: The inverting end of the first operational amplifier U1A is connected in parallel with one end of the fifth resistor R5 and the sixth resistor R6, the other end of the fifth resistor R5 is connected to the power ground, the other end of the sixth resistor R6 is connected in series with the fixed end of the first potentiometer VR1 and the output end of the first operational amplifier U1A; the variable end of the first potentiometer VR1 is also connected to the output end of the first operational amplifier U1A.

7. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 3, characterized in that: The voltage follower includes a second operational amplifier U1B, a non-inverting terminal of the second operational amplifier U1B is connected to the output of the DC signal amplifying circuit, and an inverting terminal of the second operational amplifier U1B is connected to the output terminal; The output end of the second operational amplifier U1B is connected to the voltage-current conversion output circuit (102).

8. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 7, characterized in that: A seventh resistor R7 is connected in series between the in-phase terminal of the second operational amplifier U1B and the output of the DC signal amplifying circuit; An eighth resistor R8 is connected in series between the output end of the second operational amplifier U1B and the voltage-current conversion output circuit (102); and a limiting protection diode DW1 is connected between the output end of the eighth resistor R8 and the ground.

9. A cooling fan monitoring circuit for a wire feeding power supply as claimed in claim 1, characterized in that: The voltage-current conversion output circuit (102) comprises a 0-5V / 4-20mA conversion module.

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