Insulation resistance detection circuit for mining high-voltage frequency converter

Abstract

The utility model discloses an insulation resistance detection circuit for a mining high-voltage frequency converter, and the circuit comprises a booster circuit which is connected with the mining high-voltage frequency converter and is used for injecting a fixed voltage signal to the mining high-voltage frequency converter; the attenuation unit is connected with the mining high-voltage frequency converter through a cable and used for attenuating the obtained first direct-current signal to obtain an attenuation signal; the acquisition unit is connected with the attenuation unit and is used for acquiring the attenuation signal; the first-order filtering unit is connected with the acquisition unit and is used for performing first-order filtering on the attenuation signal to obtain a first signal; the second-order filtering unit is connected with the first-order filtering unit and is used for performing second-order filtering on the first signal to obtain a second direct current signal; the analog-digital converter is connected with the second-order filtering unit and used for converting the second direct-current signal into a digital signal and inputting the digital signal into a control chip, and the circuit can rapidly and accurately detect the insulation resistance of the mining high-voltage frequency converter.

Description

Technical Field

[0001] This utility model belongs to the field of insulation resistance detection technology, specifically relating to an insulation resistance detection circuit for a mining high-voltage frequency converter. Background Technology

[0002] High-voltage (e.g., 1140V) frequency converters used in mines are typically applied in environments with high voltage, high electromagnetic interference, AC / DC interference, and motor rotation. These environments place high demands on the insulation of high-voltage frequency converters and require frequent insulation testing. However, current technology typically uses a megohmmeter to measure the insulation resistance of high-voltage frequency converters in mines, which requires multiple measurements. This process is time-consuming, labor-intensive, and yields inaccurate results.

[0003] Therefore, how to quickly and accurately test the insulation resistance of mining high-voltage frequency converters is a technical problem that needs to be solved by those skilled in the art. Utility Model Content

[0004] The purpose of this invention is to solve the technical problems of time-consuming, labor-intensive, and inaccurate measurement when testing the insulation resistance of mining high-voltage frequency converters. Therefore, this invention provides an insulation resistance testing circuit for mining high-voltage frequency converters, which includes:

[0005] A boost circuit, connected to a mining high-voltage frequency converter, is used to inject a fixed voltage signal into the mining high-voltage frequency converter;

[0006] An attenuation unit, connected to the cable of the mining high-voltage frequency converter, is used to attenuate the acquired first DC signal to obtain an attenuated signal.

[0007] A data acquisition unit, connected to the attenuation unit, is used to acquire the attenuation signal;

[0008] A first-order filtering unit, connected to the acquisition unit, is used to perform first-order filtering on the attenuated signal to obtain a first signal;

[0009] A second-order filtering unit is connected to the first-order filtering unit and is used to perform second-order filtering on the first signal to obtain a second DC signal.

[0010] An analog-to-digital converter, connected to the second-order filter unit, is used to convert the second DC signal into a digital signal and input it into the control chip.

[0011] Furthermore, the attenuation unit specifically includes resistors R1, R2, R3, R4 and R5 connected in sequence. Resistor R1 is also connected to the mining high-voltage frequency converter cable, and resistor R5 is also connected to the acquisition unit.

[0012] Furthermore, the acquisition unit specifically includes a resistor R6 and a capacitor C1. One end of the resistor R6 and one end of the capacitor C1 are both connected to the attenuation unit and the first-order filter unit, and the other end of the resistor R6 and the other end of the capacitor C1 are both grounded.

[0013] Furthermore, the first-order filtering unit specifically includes a first-order filtering circuit and an amplifier circuit. The first-order filtering circuit specifically includes a resistor R7 and a capacitor C2. One end of the resistor R7 is connected to the acquisition unit, and the other end of the resistor R7 is connected to one end of the capacitor C2 and the amplifier circuit. The other end of the capacitor C2 is grounded. The amplifier circuit specifically includes an operational amplifier U1, a resistor R8, and a resistor R9. The non-inverting input terminal of the operational amplifier U1 is connected to one end of the capacitor C2. The inverting input terminal of the operational amplifier U1 is connected to the other end of the resistor R8 and one end of the resistor R9. The other end of the resistor R9 is grounded. The output terminal of the operational amplifier U1 is connected to one end of the resistor R8 and the second-order filtering unit.

[0014] Furthermore, the second-order filtering unit includes a first filtering circuit, a second filtering circuit, and a third filtering circuit connected in sequence.

[0015] Furthermore, the first filter circuit specifically includes:

[0016] One end of resistor R10 is connected to the first-order filter unit. The other end of resistor R10 is connected to one end of resistor R11 and one end of capacitor C4. The other end of resistor R11 is connected to one end of capacitor C3 and the non-inverting input terminal of operational amplifier U2. The other end of capacitor C3 is grounded. The other end of capacitor C4 and the inverting input terminal of operational amplifier U2 are both connected to the output terminal of operational amplifier U2. The output terminal of operational amplifier U2 is also connected to the second filter circuit.

[0017] Furthermore, the second filter circuit specifically includes:

[0018] One end of resistor R12 is connected to the first filter circuit. The other end of resistor R12 is connected to one end of resistor R13 and one end of capacitor C6. The other end of resistor R13 is connected to one end of capacitor C5 and the non-inverting input terminal of operational amplifier U3. The other end of capacitor C5 is grounded. The other end of capacitor C6 and the inverting input terminal of operational amplifier U3 are both connected to the output terminal of operational amplifier U3. The output terminal of operational amplifier U3 is also connected to the third filter circuit.

[0019] Furthermore, the third filter circuit specifically includes:

[0020] One end of resistor R14 is connected to the second filter circuit. The other end of resistor R14 is connected to one end of resistor R15 and one end of capacitor C8. The other end of resistor R15 is connected to one end of capacitor C7 and the non-inverting input terminal of operational amplifier U4. The other end of capacitor C7 is grounded. The other end of capacitor C8 and the inverting input terminal of operational amplifier U4 are both connected to the output terminal of operational amplifier U4. The output terminal of operational amplifier U4 is also connected to the analog-to-digital converter.

[0021] Furthermore, pin 1 of the analog-to-digital converter is connected to the second-order filter unit, pin 2 of the analog-to-digital converter is grounded, and pins 5, 6 and 7 of the analog-to-digital converter communicate with the control chip via a serial bus.

[0022] Compared with the prior art, the beneficial effects of this utility model are:

[0023] This utility model provides a high-voltage frequency converter insulation resistance detection circuit. Compared with the prior art, this circuit includes a boost circuit connected to the mining high-voltage frequency converter to inject a fixed voltage signal into the mining high-voltage frequency converter; an attenuation unit connected to the mining high-voltage frequency converter cable to attenuate the acquired first DC signal to obtain an attenuated signal; an acquisition unit connected to the attenuation unit to acquire the attenuated signal; a first-order filtering unit connected to the acquisition unit to perform first-order filtering on the attenuated signal to obtain a first signal; a second-order filtering unit connected to the first-order filtering unit to perform second-order filtering on the first signal to obtain a second DC signal; and an analog-to-digital converter connected to the second-order filtering unit to convert the second DC signal into a digital signal for input to the control chip. This circuit can quickly and accurately detect the insulation resistance of the mining high-voltage frequency converter. Attached Figure Description

[0024] To more clearly illustrate the embodiments of this specification, the accompanying drawings used in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The diagram shown is a schematic diagram of the overall structure of the insulation resistance detection circuit for a mining high-voltage frequency converter provided in the embodiments of this specification.

[0026] Figure 2 The diagram shown is a structural schematic of the acquisition unit in an embodiment of this specification;

[0027] Figure 3 The diagram shown is a schematic diagram of the structure of a first-order filter unit in an embodiment of this specification;

[0028] Figure 4 The diagram shown is a schematic diagram of the structure of the first filter circuit in the embodiment of this specification;

[0029] Figure 5 The diagram shown is a schematic diagram of the second filter circuit in an embodiment of this specification.

[0030] Figure 6 The diagram shown is a schematic diagram of the third filter circuit in the embodiment of this specification;

[0031] Figure 7 The diagram shown is a connection diagram of the analog-to-digital converter in an embodiment of this specification. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0033] like Figure 1 The diagram shown is an overall structural schematic of the insulation resistance detection circuit for a mining high-voltage frequency converter provided in this embodiment. Although this specification provides the structure shown in the following embodiments or figures, based on conventional methods or without creative effort, the structure may include more or fewer structures after partial combination. These structures are not limited to those shown in the embodiments or figures of this specification. When the structure is applied in actual devices or end products, it can be executed sequentially or in parallel according to the embodiments or module structures.

[0034] The insulation resistance detection circuit for mining high-voltage frequency converters provided in the embodiments of this specification can be applied to various insulation resistance detection scenarios for mining high-voltage frequency converters. This circuit includes:

[0035] A boost circuit, connected to a mining high-voltage frequency converter, is used to inject a fixed voltage signal into the mining high-voltage frequency converter;

[0036] An attenuation unit, connected to the cable of the mining high-voltage frequency converter, is used to attenuate the acquired first DC signal to obtain an attenuated signal.

[0037] A data acquisition unit, connected to the attenuation unit, is used to acquire the attenuation signal;

[0038] A first-order filtering unit, connected to the acquisition unit, is used to perform first-order filtering on the attenuated signal to obtain a first signal;

[0039] A second-order filtering unit is connected to the first-order filtering unit and is used to perform second-order filtering on the first signal to obtain a second DC signal.

[0040] An analog-to-digital converter, connected to the second-order filter unit, is used to convert the second DC signal into a digital signal and input it into the control chip.

[0041] Specifically, the circuit of this application first injects a fixed voltage signal, such as a 48V DC signal source, into the mining high-voltage frequency converter through a boost circuit. At the same time, the attenuation unit is also connected to the cable of the mining high-voltage frequency converter to receive the DC signal, attenuate it, and then acquire it through the acquisition unit. Then, it is filtered sequentially through a first-order filter unit and a second-order filter unit. The second-order filter unit includes a first filter circuit, a second filter circuit, and a third filter circuit connected in sequence. The first, second, and third filter circuits are all second-order active filters. The first-order filter unit and the second-order filter unit together form a 7th-order filter, which can effectively filter out the high-order harmonics generated in the mining high-voltage frequency converter, retain the pure DC signal, and reduce the impact of large errors caused by the startup of the mining high-voltage frequency converter. The filtered DC signal is transmitted to the control chip via an analog-to-digital converter (ADC) chip. The ADC chip and the control chip communicate via a serial bus to collect and detect the insulation resistance value in real time. The control chip processes and calculates the collected signal and sends the calculation result to the main controller via a CAN signal. The main controller can set a protection insulation resistance value. When the collected value is lower than the set value, the main contactor is disconnected to protect personal and property safety.

[0042] In this embodiment, the attenuation unit specifically includes resistors R1, R2, R3, R4, and R5 connected in sequence. Resistor R1 is also connected to the mining high-voltage frequency converter cable, and resistor R5 is also connected to the acquisition unit. Figure 2 The diagram shows the structure of the acquisition unit, which specifically includes a resistor R6 and a capacitor C1. One end of the resistor R6 and one end of the capacitor C1 are connected to the attenuation unit and the first-order filter unit, respectively, and the other end of the resistor R6 and the other end of the capacitor C1 are grounded.

[0043] In the embodiments of this application, such as Figure 3The diagram shows the structure of a first-order filter unit. Specifically, the first-order filter unit includes a first-order filter circuit and an amplifier circuit. The first-order filter circuit specifically includes a resistor R7 and a capacitor C2. One end of the resistor R7 is connected to the acquisition unit, and the other end of the resistor R7 is connected to one end of the capacitor C2 and the amplifier circuit. The other end of the capacitor C2 is grounded. The amplifier circuit specifically includes an operational amplifier U1, resistors R8 and R9. The non-inverting input of the operational amplifier U1 is connected to one end of the capacitor C2. The inverting input of the operational amplifier U1 is connected to the other end of the resistor R8 and one end of the resistor R9. The other end of the resistor R9 is grounded. The output of the operational amplifier U1 is connected to one end of the resistor R8 and the second-order filter unit.

[0044] In the embodiments of this application, such as Figure 4 The diagram shown is a schematic of the first filter circuit, which specifically includes:

[0045] One end of resistor R10 is connected to the first-order filter unit. The other end of resistor R10 is connected to one end of resistor R11 and one end of capacitor C4. The other end of resistor R11 is connected to one end of capacitor C3 and the non-inverting input terminal of operational amplifier U2. The other end of capacitor C3 is grounded. The other end of capacitor C4 and the inverting input terminal of operational amplifier U2 are both connected to the output terminal of operational amplifier U2. The output terminal of operational amplifier U2 is also connected to the second filter circuit.

[0046] like Figure 5 The diagram shown illustrates the structure of the second filter circuit, which specifically includes:

[0047] One end of resistor R12 is connected to the first filter circuit. The other end of resistor R12 is connected to one end of resistor R13 and one end of capacitor C6. The other end of resistor R13 is connected to one end of capacitor C5 and the non-inverting input terminal of operational amplifier U3. The other end of capacitor C5 is grounded. The other end of capacitor C6 and the inverting input terminal of operational amplifier U3 are both connected to the output terminal of operational amplifier U3. The output terminal of operational amplifier U3 is also connected to the third filter circuit.

[0048] like Figure 6 The diagram shown is a schematic of the third filter circuit, which specifically includes:

[0049] One end of resistor R14 is connected to the second filter circuit. The other end of resistor R14 is connected to one end of resistor R15 and one end of capacitor C8. The other end of resistor R15 is connected to one end of capacitor C7 and the non-inverting input terminal of operational amplifier U4. The other end of capacitor C7 is grounded. The other end of capacitor C8 and the inverting input terminal of operational amplifier U4 are both connected to the output terminal of operational amplifier U4. The output terminal of operational amplifier U4 is also connected to the analog-to-digital converter.

[0050] like Figure 7 The diagram shown is a connection diagram of an analog-to-digital converter, which is also known as an analog-to-digital converter. Figure 7 The high-precision ADC in the high-precision ADC has pin 1 connected to the second-order filter unit, pin 2 grounded, pins 5, 6 and 7 of the analog-to-digital converter communicating with the control chip via a serial bus, the VCC1 pin of the high-precision ADC connected to the power supply, and the GND pin grounded.

[0051] The detection circuit provided in this application can filter out the high-order harmonics generated when the high-voltage frequency converter in the mine starts up, which is highly safe. At the same time, the response signal to be collected is clear, and the filter can accurately extract the required signal when the cutoff frequency is set. The method eliminates the influence of distributed capacitance on the measurement data by superimposing a positive DC voltage on the cable insulation layer and detecting the leakage current of the DC flowing through the insulation resistance. The device is easy to install and operate, requires less signal processing, and has a fast measurement response.

[0052] It should be understood that when an element is referred to as “fixed to” or “set on” another element, it may be directly on the other element or may be interposed with an intervening element; when an element is referred to as “connected to” another element, it may be directly connected to the other element or may be interposed with an intervening element. Furthermore, the term “connected” as used herein may include wireless connections; the word “and / or” as used includes any and all combinations of one or more of the associated listed items.

[0053] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0054] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0055] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0056] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

[0059] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. A circuit for detecting the insulation resistance of a mining high-voltage frequency converter, characterized in that, The detection circuit includes: A boost circuit, connected to a mining high-voltage frequency converter, is used to inject a fixed voltage signal into the mining high-voltage frequency converter; An attenuation unit, connected to the cable of the mining high-voltage frequency converter, is used to attenuate the acquired first DC signal to obtain an attenuated signal. A data acquisition unit, connected to the attenuation unit, is used to acquire the attenuation signal; A first-order filtering unit, connected to the acquisition unit, is used to perform first-order filtering on the attenuated signal to obtain a first signal; A second-order filtering unit is connected to the first-order filtering unit and is used to perform second-order filtering on the first signal to obtain a second DC signal. An analog-to-digital converter, connected to the second-order filter unit, is used to convert the second DC signal into a digital signal and input it into the control chip.

2. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 1, characterized in that, The attenuation unit specifically includes resistors R1, R2, R3, R4 and R5 connected in sequence. Resistor R1 is also connected to the mining high-voltage frequency converter cable, and resistor R5 is also connected to the acquisition unit.

3. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 1, characterized in that, The acquisition unit specifically includes a resistor R6 and a capacitor C1. One end of the resistor R6 and one end of the capacitor C1 are both connected to the attenuation unit and the first-order filter unit. The other end of the resistor R6 and the other end of the capacitor C1 are both grounded.

4. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 1, characterized in that, The first-order filtering unit specifically includes a first-order filtering circuit and an amplifier circuit. The first-order filtering circuit specifically includes a resistor R7 and a capacitor C2. One end of the resistor R7 is connected to the acquisition unit, and the other end of the resistor R7 is connected to one end of the capacitor C2 and the amplifier circuit. The other end of the capacitor C2 is grounded. The amplifier circuit specifically includes an operational amplifier U1, a resistor R8, and a resistor R9. The non-inverting input terminal of the operational amplifier U1 is connected to one end of the capacitor C2. The inverting input terminal of the operational amplifier U1 is connected to the other end of the resistor R8 and one end of the resistor R9. The other end of the resistor R9 is grounded. The output terminal of the operational amplifier U1 is connected to one end of the resistor R8 and the second-order filtering unit.

5. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 1, characterized in that, The second-order filtering unit includes a first filtering circuit, a second filtering circuit, and a third filtering circuit connected in sequence.

6. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 5, characterized in that, The first filter circuit specifically includes: One end of resistor R10 is connected to the first-order filter unit. The other end of resistor R10 is connected to one end of resistor R11 and one end of capacitor C4. The other end of resistor R11 is connected to one end of capacitor C3 and the non-inverting input terminal of operational amplifier U2. The other end of capacitor C3 is grounded. The other end of capacitor C4 and the inverting input terminal of operational amplifier U2 are both connected to the output terminal of operational amplifier U2. The output terminal of operational amplifier U2 is also connected to the second filter circuit.

7. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 5, characterized in that, The second filter circuit specifically includes: One end of resistor R12 is connected to the first filter circuit. The other end of resistor R12 is connected to one end of resistor R13 and one end of capacitor C6. The other end of resistor R13 is connected to one end of capacitor C5 and the non-inverting input terminal of operational amplifier U3. The other end of capacitor C5 is grounded. The other end of capacitor C6 and the inverting input terminal of operational amplifier U3 are both connected to the output terminal of operational amplifier U3. The output terminal of operational amplifier U3 is also connected to the third filter circuit.

8. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 5, characterized in that, The third filter circuit specifically includes: One end of resistor R14 is connected to the second filter circuit. The other end of resistor R14 is connected to one end of resistor R15 and one end of capacitor C8. The other end of resistor R15 is connected to one end of capacitor C7 and the non-inverting input terminal of operational amplifier U4. The other end of capacitor C7 is grounded. The other end of capacitor C8 and the inverting input terminal of operational amplifier U4 are both connected to the output terminal of operational amplifier U4. The output terminal of operational amplifier U4 is also connected to the analog-to-digital converter.

9. The insulation resistance detection circuit for a mining high-voltage frequency converter as described in claim 1, characterized in that, Pin 1 of the analog-to-digital converter is connected to the second-order filter unit, pin 2 of the analog-to-digital converter is grounded, and pins 5, 6 and 7 of the analog-to-digital converter communicate with the control chip via a serial bus.

Images