CN108445365B - Automatic insulation impedance monitoring device - Google Patents
Automatic insulation impedance monitoring device Download PDFInfo
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- CN108445365B CN108445365B CN201810388281.0A CN201810388281A CN108445365B CN 108445365 B CN108445365 B CN 108445365B CN 201810388281 A CN201810388281 A CN 201810388281A CN 108445365 B CN108445365 B CN 108445365B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
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Abstract
The invention discloses an automatic insulation impedance monitoring device, which comprises a microcontroller, a driving circuit, an impedance switching circuit and a voltage conditioning circuit, wherein the driving circuit is connected with the microcontroller; the microcontroller generates control signals according to a preset switching sequence; the driving circuit amplifies the control signal to generate a driving signal; the impedance switching circuit comprises a first virtual insulation resistor, a second virtual insulation resistor, a first electronic switch, a second electronic switch and a third electronic switch; the first electronic switch, the second electronic switch and the third electronic switch are switched off or on according to a switching sequence under the control of the driving signal, so that the impedance switching circuit generates a first measurement voltage, a second measurement voltage and a third measurement voltage respectively; the microprocessor calculates impedance values of a first virtual insulation resistor and a second virtual insulation resistor of the equipment to be tested according to the first measurement voltage, the second measurement voltage and the third measurement voltage; the invention can realize the automatic real-time monitoring of the positive terminal to ground impedance and the negative terminal to ground impedance of the equipment to be tested.
Description
Technical Field
The invention belongs to the technical field of computer measurement and control, and particularly relates to an automatic insulation impedance monitoring device.
Background
In a large-scale complex power equipment power supply and distribution system, in order to ensure the safe operation of equipment and the personal safety of operators, the insulation impedance of a shell of the power supply and distribution system with positive voltage and negative voltage needs to be monitored, when the insulation impedance is smaller than a set threshold value, the power supply and distribution system is likely to discharge to the ground, and when the insulation impedance is serious, the problems of damage of a power generation system device, transformer failure and the like are likely to be caused, and at the moment, the power supply and distribution system should stop operating and be overhauled.
At present, the insulation resistance of an equipment system is regularly monitored by professional personnel, the method is not strong in real-time performance, emergency cannot be dealt with, and the labor cost required by monitoring is high.
Disclosure of Invention
Aiming at least one defect or improvement requirement in the prior art, the invention provides an automatic insulation impedance monitoring device, which is connected between a power supply positive electrode and a power supply negative electrode of equipment to be detected when in use, and the monitoring device carries out automatic real-time monitoring after being started, so that the problems of low real-time performance and labor consumption of the conventional method are solved.
In order to achieve the above object, according to one aspect of the present invention, there is provided an automatic insulation impedance monitoring device, including a microcontroller, a driving circuit, an impedance switching circuit, and a voltage conditioning circuit;
the microcontroller is used for generating a control signal according to a preset switching sequence, and a first output end of the microcontroller is connected with an input end of the driving circuit;
the drive circuit is used for amplifying the control signal and generating a drive signal;
the impedance switching circuit comprises a first virtual insulation resistor Rx, a second virtual insulation resistor Ry, a first divider resistor R1, a second divider resistor R2, a first electronic switch K1, a second electronic switch K2 and a third electronic switch K3; the first virtual insulation resistor Rx and the second virtual insulation resistor Ry are connected in series and then are arranged between the positive electrode end and the negative electrode end of the equipment to be tested, and the connecting point of the first virtual insulation resistor Rx and the second virtual insulation resistor Ry is connected with the ground wire; the second electronic switch K2 and the first virtual insulation resistor Rx are connected in parallel between the positive terminal of the equipment to be tested and the ground wire, and the first divider resistor R1 and the first electronic switch K1 are connected in series and then connected in parallel with the first virtual insulation resistor Rx between the positive terminal of the equipment to be tested and the ground wire; the second voltage-dividing resistor R2 and the second virtual insulation resistor Ry are connected in parallel between the negative end of the device to be tested and the ground wire; one end of the third electronic switch K3 is connected with the ground wire, and the other end of the third electronic switch K3 is connected with the first input end of the voltage conditioning circuit;
the control ends of the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are connected with the output end of the driving circuit; the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are opened or closed according to the switching sequence under the control of the driving signal, so that the impedance switching circuit respectively generates a first measuring voltage V0A second measurement voltage V1And a third measurement voltage V2；
The output end of the voltage conditioning circuit is connected with the sampling end of the microprocessor and is used for respectively collecting the first measurement voltage V0A second measurement voltage V1And a third measurement voltage V2And respectively converting the voltage signals into voltage signals which can be read by a microprocessor;
the microprocessor measures the voltage V according to the first measurement voltage0A second measurement voltage V1And a third measurement voltage V2And calculating the impedance values of the first virtual insulation resistor Rx and the second virtual insulation resistor Ry of the equipment to be tested according to the corresponding voltage signals.
Preferably, the automatic insulation resistance monitoring device has a switching sequence of:
s1: the first electronic switch K1 and the third electronic switch K3 are switched off, the second electronic switch K2 is switched on, and a first measurement voltage V is obtained0；
The first measurement voltage V0The voltage of the voltage Vin between the positive terminal V + and the negative terminal V-of the device to be tested is divided by a second voltage dividing resistor R2:
V0＝Vin
s2: the first electronic switch K1 and the second electronic switch K2 are disconnected, the third electronic switch K3 is closed, and a second measurement voltage V is obtained1；
The second virtual insulation resistor Ry and the second voltage-dividing resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, and the second measurement voltage V1Dividing the voltage Vin between the positive terminal V + and the negative terminal V-of the device to be tested on a third virtual insulation resistor R2 y:
s3: the second electronic switch K2 is opened, the first electronic switch K1 is closed and the third electronic switch K3 is closed, and a second measurement voltage V is obtained2；
The second virtual insulation resistor Ry and the second voltage-dividing resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, the first virtual insulation resistor Rx and the first voltage-dividing resistor R1 are connected in parallel to form a fourth virtual insulation resistor R1x, and the third measurement voltage V is measured2Dividing the voltage Vin between the positive terminal V + and the negative terminal V-of the device to be tested on a third virtual insulation resistor R2 y:
preferably, in the automatic insulation resistance monitoring device, an impedance calculation formula of the first virtual insulation resistance Rx is as follows:
the impedance calculation formula of the second virtual insulation resistance Ry is as follows:
wherein R is1Is the value of a first divider resistor R1, R2Is the resistance of the second divider resistor R2.
Preferably, the microprocessor of the automatic insulation impedance monitoring device includes a first output terminal, a second output terminal, a third output terminal, a power supply terminal and an a/D sampling terminal; the first control signal generated by the microprocessor and used for controlling the first electronic switch K1 is sent to the driving circuit through the first output end, the second control signal generated by the microprocessor and used for controlling the second electronic switch K2 is sent to the driving circuit through the second output end, and the third control signal generated by the microprocessor and used for controlling the third electronic switch K3 is sent to the driving circuit through the third output end.
Preferably, the driving circuit of the automatic insulation impedance monitoring device includes a driving buffer, a first input end of the driving buffer is connected to a first output end of the microprocessor, a second input end of the driving buffer is connected to a second output end of the microprocessor, and a third input end of the driving buffer is connected to a third output end of the microprocessor; the first output end of the driving buffer is connected with the control end of the first electronic switch K1; the second output end of the driving buffer is connected with the control end of the second electronic switch K2; the third output of the drive buffer is connected to the control terminal of the third electronic switch K3.
Preferably, the voltage conditioning circuit of the automatic insulation resistance monitoring device includes an operational amplifier, a third voltage dividing resistor R3, a fourth voltage dividing resistor R4, a fifth voltage dividing resistor R5, and a sixth voltage dividing resistor R6;
the non-inverting input end of the operational amplifier is connected with the common end of the first electronic switch K1, the second electronic switch K2, the third electronic switch K3 and the second voltage-dividing resistor R2 through a third voltage-dividing resistor R3, and is connected with the reference ground GND through a fifth voltage-dividing resistor R5; the inverting input end of the operational amplifier is connected with the negative electrode end of the device to be tested through a fourth voltage-dividing resistor R4, and the output end of the operational amplifier is connected with the A/D sampling end of the microprocessor.
Preferably, in the automatic insulation resistance monitoring device, the first electronic switch K1, the second electronic switch K2, and the third electronic switch K3 are selected from transistors or relays.
Preferably, the automatic insulation impedance monitoring device further comprises a power supply circuit, wherein an input end of the power supply circuit is electrically connected with an external input bus, and an output end of the power supply circuit is connected with a power supply end of the microcontroller and used for supplying power to the microprocessor.
Preferably, the automatic insulation resistance monitoring device further includes a communication circuit, an input end of the communication circuit is connected to a fourth output end of the microprocessor, and an output end of the communication circuit is connected to the external test machine, and the communication circuit is configured to transmit the impedance values of the first virtual insulation resistance and the second virtual insulation resistance calculated by the microprocessor to the external test machine.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
according to the automatic insulation impedance monitoring device provided by the invention, a processor generates a control signal based on a preset switching sequence, and a first electronic switch, a second electronic switch and a third electronic switch execute opening or closing actions according to the switching sequence under the control of the control signal to change the circuit state of an impedance switching circuit; the voltage conditioning circuit collects voltage values of the impedance switching circuit in different circuit states and converts the voltage values into voltage signal values which can be read by the microprocessor, and the microprocessor calculates according to the collected voltage signals to obtain the positive electrode end to ground impedance and the negative electrode end to ground impedance values of the equipment to be tested; the microcontroller, the driving circuit, the impedance switching circuit and the voltage conditioning circuit realize the automatic and real-time monitoring function of the monitoring device through closed-loop control.
Drawings
Fig. 1 is a circuit diagram of an automatic insulation resistance monitoring device according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a power supply circuit provided by an embodiment of the invention;
fig. 3 is a test flowchart based on an insulation resistance monitoring algorithm according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides an automatic insulation impedance monitoring device, which comprises a microcontroller, a driving circuit, an impedance switching circuit and a voltage conditioning circuit, wherein the driving circuit is connected with the microcontroller;
the impedance switching circuit comprises a first virtual insulation resistor, a second virtual insulation resistor, a first divider resistor, a second divider resistor, a first electronic switch, a second electronic switch and a third electronic switch; the first virtual insulation resistor and the second virtual insulation resistor are connected in series and then are arranged between the positive end and the negative end of the equipment to be tested, and the connection point of the first virtual insulation resistor and the second virtual insulation resistor is connected with the ground wire; the second electronic switch and the first virtual insulation resistor are connected in parallel between the positive terminal of the equipment to be tested and the ground wire, and the first divider resistor and the first electronic switch are connected in series and then connected in parallel between the positive terminal of the equipment to be tested and the ground wire with the first virtual insulation resistor; the second voltage dividing resistor and the second virtual insulation resistor are connected in parallel between the negative end of the equipment to be tested and the ground wire; one end of the third electronic switch is connected with the ground wire, and the other end of the third electronic switch is connected with the non-inverting input end of the voltage conditioning circuit.
The microcontroller is used for generating a control signal according to a preset switching sequence, and a first output end of the microcontroller is connected with an input end of the relay switching drive circuit;
the driving circuit is used for amplifying the control signal output by the microcontroller to generate a driving signal;
the control ends of the first electronic switch, the second electronic switch and the third electronic switch are connected with the output end of the driving circuit; the first electronic switch, the second electronic switch and the third electronic switch are closed according to a switching sequence under the control of the driving signal, so that the impedance switching circuit respectively generates a first measuring voltage, a second measuring voltage and a third measuring voltage;
the voltage conditioning circuit is used for acquiring the first measurement voltage, the second measurement voltage and the third measurement voltage generated by the impedance switching circuit, respectively converting the first measurement voltage, the second measurement voltage and the third measurement voltage into a first voltage signal, a second voltage signal and a third voltage signal which can be read by the microprocessor, and the output end of the voltage conditioning circuit is connected with the sampling end of the microprocessor;
and the microprocessor calculates the impedance values of the first virtual insulation resistor and the second virtual insulation resistor of the equipment to be tested according to the first voltage signal, the second voltage signal and the third voltage signal generated by the voltage conditioning circuit.
The microprocessor comprises a power supply end, a sampling end, a first output end, a second output end and a third output end; the microprocessor is loaded with impedance switching control software and is used for respectively generating a first control signal, a second control signal and a third control signal for controlling the electronic switch to be closed according to an insulation impedance monitoring algorithm; a first control signal generated by the microprocessor is transmitted to the driving circuit through a first output end, a second control signal is transmitted to the driving circuit through a second output end, and a third control signal is transmitted to the driving circuit through a third output end;
the driving circuit comprises a driving buffer, a first input end of the driving buffer is connected with a first output end of the microprocessor, and a first control signal enters the driving circuit through the first input end; the second input end of the driving buffer is connected with the second output end of the microprocessor, and a second control signal enters the driving circuit through the second input end; the third input end of the driving buffer is connected with the third output end of the microprocessor, and a third control signal enters the driving circuit through the third input end; the driving buffer amplifies the received first control signal, second control signal and third control signal to generate a first driving signal, a second driving signal and a third driving signal;
the first output end of the driving buffer is connected with the control end of the first electronic switch, and the first electronic switch executes opening or closing action under the control of a first driving signal output by the first output end; the second output end of the driving buffer is connected with the control end of a second electronic switch, and the second electronic switch executes opening or closing action under the control of a second driving signal output by the second output end; the third output end of the driving buffer is connected with the control end of a third electronic switch, and the third electronic switch executes opening or closing action under the control of a third driving signal output by the third output end;
the voltage conditioning circuit comprises an operational amplifier, a third voltage dividing resistor and a fourth voltage dividing resistor; the first electronic switch, the second electronic switch, the third electronic switch, the second voltage-dividing resistor and the public end are connected with the non-inverting input end of the operational amplifier through a third voltage-dividing resistor; the inverting input end of the operational amplifier is connected with the negative electrode end of the equipment to be tested through a fourth voltage-dividing resistor, and the output end of the operational amplifier is connected with the sampling end of the microcontroller; the operational amplifier converts the first measuring voltage, the second measuring voltage and the third measuring voltage generated by the impedance switching circuit into voltage signals which can be read by the microprocessor respectively.
And the microprocessor is loaded with impedance calculation software and is used for calculating impedance values of the first virtual insulation resistor and the second virtual insulation resistor according to voltage signals corresponding to the first measurement voltage, the second measurement voltage and the third measurement voltage generated by the operational amplifier.
In a preferred embodiment, the first electronic switch, the second electronic switch and the third electronic switch can be transistors or relays.
In a preferred embodiment, the automatic insulation resistance monitoring device further comprises a power supply circuit, wherein an input end of the power supply circuit is electrically connected with an external input bus, and an output end of the power supply circuit is connected with a power supply end of the microcontroller and used for supplying power to the microprocessor.
In a preferred embodiment, the automatic insulation resistance monitoring device further includes a communication circuit, an input end of the communication circuit is connected to the fourth output end of the microprocessor, and an output end of the communication circuit is connected to the external testing machine, and the communication circuit is configured to transmit the impedance values of the first virtual insulation resistance and the second virtual insulation resistance calculated by the microprocessor to the external testing machine, and display the impedance values by the external testing machine.
The structure and operation of the protection circuit provided by the present invention will be described in detail with reference to the following embodiments and accompanying drawings.
Fig. 1 is a circuit diagram of the automatic insulation resistance monitoring device provided in this embodiment, and as shown in fig. 1, the automatic insulation resistance monitoring device provided in this embodiment includes a microprocessor U1, a power supply circuit U2, a driving circuit, an impedance switching circuit, and a voltage conditioning circuit;
FIG. 2 is a circuit diagram of a power supply circuit provided by an embodiment of the invention; the input ends 1 and 2 of the power supply circuit U2 are connected with the total power of an external system, and the output end 2 is connected with a power supply end VDD of the microprocessor U1 and used for providing 5V power for the microprocessor U1.
The microprocessor U1 comprises a first output terminal I/O1, a second output terminal I/O2, a third output terminal I/O3 and an A/D sampling terminal; impedance switching control software loaded in the microprocessor U1 generates a first control signal, a second control signal, and a third control signal according to a certain switching sequence according to an insulation impedance switching algorithm; the first control signal is transmitted to the driving circuit through the first output terminal I/O1, the second control signal is transmitted to the driving circuit through the second output terminal I/O2, and the third control signal is transmitted to the driving circuit through the third output terminal I/O3.
The driving circuit comprises a driving buffer N1, a first input pin 2A1 of the driving buffer N1 is connected with a first output end I/O1 of a microprocessor U1, a second input pin 2A2 is connected with a second output end I/O2 of the microprocessor U1, and a third input pin 2A3 is connected with a third output end I/O3 of a microprocessor U1; the driving buffer N1 receives and amplifies the first control signal through the first input pin 2a1 to generate a first driving signal; receiving and amplifying the second control signal through the second input pin 2a2 to generate a second driving signal; receiving and amplifying the third control signal through the third input pin 2a3 to generate a third driving signal;
the impedance switching circuit comprises a first virtual insulation resistor Rx, a second virtual insulation resistor Ry, a first divider resistor R1, a second divider resistor R2, a first relay K1, a second relay K2 and a third relay K3; the first virtual insulation resistor Rx and the second virtual insulation resistor Ry are resistance values between a positive terminal and a negative terminal of the virtual device to be detected and the shell (ground), namely insulation impedance to be monitored; the first virtual insulation resistor Rx and the second virtual insulation resistor Ry are connected in series and then are arranged between the positive terminal V + and the negative terminal V-of the equipment to be tested, and the connection point of the first virtual insulation resistor Rx and the second virtual insulation resistor Ry is connected with the EARTH wire EARTH; the second relay K2 and the first virtual insulation resistor Rx are connected in parallel between the positive end V + of the equipment to be tested and the ground wire EARTH, and the first divider resistor R1 and the first relay K1 are connected in series and then connected in parallel with the first virtual insulation resistor Rx between the positive end V + of the equipment to be tested and the ground wire EARTH; the second voltage-dividing resistor R2 and the second virtual insulation resistor Ry are connected in parallel between the negative end V-of the equipment to be tested and the ground wire; one end of the third relay K3 is connected with the EARTH wire EARTH, and the other end is connected with the non-inverting input end of the voltage conditioning circuit.
The control end of the first relay K1 is connected with the first output end 2Y1 of the driving buffer N1, the first driving signal is transmitted to the first relay K1 through the first output end 2Y1, and the first relay K1 performs opening or closing action under the control of the first driving signal; the control end of the second relay K2 is connected with the second output end 2Y2 of the driving buffer N1, the second driving signal is transmitted to the second relay K2 through the second output end 2Y2, and the second relay K2 performs an opening or closing action under the control of the second driving signal; the control end of the third relay K3 is connected to the third output end 2Y3 of the driving buffer N1, the third driving signal is transmitted to the third relay K3 through the third output end 2Y3, and the third relay K3 performs an opening or closing action under the control of the third driving signal.
The voltage conditioning circuit comprises an operational amplifier U1A, a third voltage-dividing resistor R3, a fourth voltage-dividing resistor R4, a fifth voltage-dividing resistor R5 and a sixth voltage-dividing resistor R6; the non-inverting input end 3 of the operational amplifier U1A is connected with the common end of the first relay K1, the second relay K2, the third relay K3 and the second voltage-dividing resistor R2 through a third voltage-dividing resistor R3, and is connected with the ground GND through a fifth voltage-dividing resistor R5; the inverting input end 2 of the operational amplifier U1A is connected with the negative electrode end V-of the device to be tested through a fourth voltage-dividing resistor R4, and the output end 1 is connected with the A/D sampling end of the microprocessor U1.
The operational amplifier U1A, the third voltage-dividing resistor R3, the fourth voltage-dividing resistor R4, the fifth voltage-dividing resistor R5 and the sixth voltage-dividing resistor R6 form a differential operational circuit, and the first measurement voltage, the second measurement voltage and the third measurement voltage output by the impedance switching circuit are respectively converted into voltage signals which can be directly sampled by the microprocessor.
The following explains the working principle of the automatic insulation resistance monitoring device:
fig. 3 is a test flowchart based on the insulation resistance monitoring algorithm provided in this embodiment, which includes the following steps:
s1: the microprocessor U1 generates a second control signal, the driving buffer amplifies the second control signal, and a second driving signal is generated and sent to the second relay K2; the second relay K2 is closed under the control of the second drive signal; the microprocessor collects the output voltage V0 of the impedance switching circuit through the voltage conditioning circuit;
when the second relay K2 is closed, the input voltage of the positive terminal V + and the input voltage Vin of the negative terminal V-of the device to be tested are directly added to the second voltage dividing resistor R2, and the sampling voltage V of the microprocessor U10Namely, the voltage Vin between the positive terminal V + and the negative terminal V-is divided by the second voltage dividing resistor R2;
wherein, V0＝Vin(1)
S2: the microprocessor U1 generates a third control signal, the driving buffer amplifies the third control signal, and generates a third driving signal and sends the third driving signal to the third relay K3; the third relay K3 is closed under the control of the third drive signal; the microprocessor U1 generates a second control signal, the driving buffer amplifies the second control signal, and a second driving signal is generated and sent to the second relay K2; the second relay K2 is turned off under the control of the second drive signal; the microprocessor collects the output voltage V of the impedance switching circuit through the voltage conditioning circuit1；
When the third relay K3 is closed and the second relay K2 is opened, the second virtual insulation resistor Ry and the second voltage division resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, the input voltage of the positive terminal V + and the input voltage Vin of the negative terminal V-are divided through the first virtual insulation resistor Rx and the second virtual insulation resistor R2y which are connected in series, and the sampling voltage V of the microprocessor U11Between the positive terminal V + and the negative terminal V-)The voltage Vin across the third virtual insulation resistor R2 y;
according to the formulae (1), (2) and (3), the result is
S3: the microprocessor U1 generates a first control signal, the driving buffer amplifies the first control signal, and generates a first driving signal and sends the first driving signal to the first relay K1; the first relay K1 is closed under the control of the first drive signal; the microprocessor U1 collects the output voltage V of the impedance switching circuit through the voltage conditioning circuit2；
When the first relay K1 and the third relay K3 are closed, the second virtual insulation resistor Ry and the second voltage dividing resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, the first virtual insulation resistor Rx and the first voltage dividing resistor R1 are connected in parallel to form a fourth virtual insulation resistor R1x, the input voltage of the positive terminal V + and the input voltage Vin of the negative terminal V-are divided by the fourth virtual insulation resistor R1x and the third virtual insulation resistor R2y which are connected in series, and the sampling voltage V of the microprocessor U1 is divided2Namely, the voltage Vin between the positive terminal V + and the negative terminal V-is divided by the third virtual insulation resistor R2 y;
according to the formulae (1), (4) and (5), the result is
S4: the microprocessor U1 is used for collecting the voltage V0、V1、V2And a resistance value R of the first divider resistor1And resistance value R of the second divider resistor2Respectively calculating impedance values of a first virtual insulation resistor Rx and a second virtual insulation resistor Ry;
simultaneous equations (4), (7) yield:
according to the automatic insulation impedance monitoring device provided by the invention, a processor generates a control signal based on a preset switching sequence, and a first electronic switch, a second electronic switch and a third electronic switch execute opening or closing actions according to the switching sequence under the control of the control signal to change the circuit state of an impedance switching circuit; the voltage conditioning circuit collects voltage values of the impedance switching circuit in different circuit states and converts the voltage values into voltage signal values which can be read by the microprocessor, and the microprocessor calculates according to the collected voltage signals to obtain the positive electrode end to ground impedance and the negative electrode end to ground impedance values of the equipment to be tested; the microcontroller, the driving circuit, the impedance switching circuit and the voltage conditioning circuit realize the automatic and real-time monitoring functions of the monitoring device through closed-loop control, and save human resources.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. An automatic insulation impedance monitoring device is characterized by comprising a microprocessor, a driving circuit, an impedance switching circuit and a voltage conditioning circuit;
the first output end of the microprocessor is connected with the input end of the driving circuit and used for generating a control signal according to a preset switching sequence;
the drive circuit is used for amplifying the control signal and generating a drive signal;
the impedance switching circuit comprises a first virtual insulation resistor Rx, a second virtual insulation resistor Ry, a first divider resistor R1, a second divider resistor R2, a first electronic switch K1, a second electronic switch K2 and a third electronic switch K3; the first virtual insulation resistor Rx and the second virtual insulation resistor Ry are connected in series and then are arranged between the positive electrode end and the negative electrode end of the equipment to be tested, and the connecting point of the first virtual insulation resistor Rx and the second virtual insulation resistor Ry is connected with the ground wire; the second electronic switch K2 and the first virtual insulation resistor Rx are connected in parallel between the positive terminal of the equipment to be tested and the ground wire, and the first divider resistor R1 and the first electronic switch K1 are connected in series and then connected in parallel with the first virtual insulation resistor Rx between the positive terminal of the equipment to be tested and the ground wire; the second voltage-dividing resistor R2 and the second virtual insulation resistor Ry are connected in parallel between the negative end of the device to be tested and the ground wire; one end of the third electronic switch K3 is connected with the ground wire, and the other end of the third electronic switch K3 is connected with the first input end of the voltage conditioning circuit;
the control ends of the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are connected with the output end of the driving circuit, and are switched off or switched on according to the switching sequence under the control of the driving signal, so that the impedance switching circuit respectively generates a first measuring voltage V0A second measurement voltage V1And a third measurement voltage V2(ii) a The first electronic switch K1 and the third electronic switch K3 are turned off, and the second electronic switch K2 generates a first measurement voltage V when turned on0(ii) a The first electronic switch K1, the second electronic switch K2 are opened, and the third electronic switch K3 generates a second measuring voltage V when closed1(ii) a The first electronic switch K1 and the third electronic switch K3 are closed, and the second electronic switch K2 generates a third measuring voltage V when being opened2；
The output end of the voltage conditioning circuit is connected with the sampling end of the microprocessor and is used for respectively collecting the first measuring electricityPressure V0A second measurement voltage V1And a third measurement voltage V2And respectively converting the voltage signals into voltage signals which can be read by a microprocessor;
the microprocessor measures the voltage V according to the first measurement voltage0A second measurement voltage V1And a third measurement voltage V2And calculating the impedance values of the first virtual insulation resistor Rx and the second virtual insulation resistor Ry of the equipment to be tested according to the corresponding voltage signals.
2. The automatic insulation resistance monitoring device according to claim 1,
the first measurement voltage V0The voltage of the voltage Vin between the positive terminal V + and the negative terminal V-of the device to be tested is divided by a second voltage dividing resistor R2:
V0＝Vin
when the third electronic switch K3 is closed, the second virtual insulation resistor Ry and the second voltage-dividing resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, and the second measurement voltage V is1Dividing the voltage Vin between the positive terminal V + and the negative terminal V-of the device to be tested on a third virtual insulation resistor R2 y:
wherein R is2Is the resistance value of the second divider resistor R2;
when the first electronic switch K1 and the third electronic switch K3 are closed, the second virtual insulation resistor Ry and the second voltage-dividing resistor R2 are connected in parallel to form a third virtual insulation resistor R2y, the first virtual insulation resistor Rx and the first voltage-dividing resistor R1 are connected in parallel to form a fourth virtual insulation resistor R1x, and the third measurement voltage V is measured2Is to be treatedAnd the voltage Vin between the positive terminal V + and the negative terminal V-of the device is divided by a third virtual insulation resistor R2 y:
wherein R is1Is the resistance of the first divider resistor R1.
3. The automatic insulation resistance monitoring device according to claim 2, wherein the impedance calculation formula of the first virtual insulation resistance Rx is:
the impedance calculation formula of the second virtual insulation resistance Ry is as follows:
4. the automatic insulation resistance monitoring device according to claim 1, wherein the microprocessor comprises a first output terminal, a second output terminal, a third output terminal, a power supply terminal and an a/D sampling terminal; the first control signal generated by the microprocessor and used for controlling the first electronic switch K1 is sent to the driving circuit through the first output end, the second control signal generated by the microprocessor and used for controlling the second electronic switch K2 is sent to the driving circuit through the second output end, and the third control signal generated by the microprocessor and used for controlling the third electronic switch K3 is sent to the driving circuit through the third output end.
5. The automatic insulation resistance monitoring device according to claim 4, wherein the driving circuit comprises a driving buffer, a first input terminal of the driving buffer is connected with a first output terminal of the microprocessor, a second input terminal of the driving buffer is connected with a second output terminal of the microprocessor, and a third input terminal of the driving buffer is connected with a third output terminal of the microprocessor; the first output end of the driving buffer is connected with the control end of the first electronic switch K1; the second output end of the driving buffer is connected with the control end of the second electronic switch K2; the third output of the drive buffer is connected to the control terminal of the third electronic switch K3.
6. The automatic insulation resistance monitoring device according to claim 4 or 5, wherein the voltage conditioning circuit comprises an operational amplifier, a third voltage dividing resistor R3, a fourth voltage dividing resistor R4, a fifth voltage dividing resistor R5 and a sixth voltage dividing resistor R6;
the non-inverting input end of the operational amplifier is connected with the common end of the first electronic switch K1, the second electronic switch K2, the third electronic switch K3 and the second voltage-dividing resistor R2 through the third voltage-dividing resistor R3, and is connected with the ground GND through the fifth voltage-dividing resistor R5; the inverting input end of the operational amplifier is connected with the negative electrode end of the equipment to be tested through the fourth voltage-dividing resistor R4, and the output end of the operational amplifier is connected with the A/D sampling end of the microprocessor.
7. The automatic insulation resistance monitoring device according to claim 1, wherein the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are selected from transistors or relays.
8. The automatic insulation resistance monitoring device according to claim 1, further comprising a power supply circuit having an input terminal electrically connected to the external input bus and an output terminal connected to a power supply terminal of the microprocessor for supplying power to the microprocessor.
9. The automatic insulation resistance monitoring device according to claim 1, further comprising a communication circuit, wherein an input terminal of the communication circuit is connected to a fourth output terminal of the microprocessor, and an output terminal of the communication circuit is connected to the external testing machine, for transmitting the impedance values of the first virtual insulation resistance and the second virtual insulation resistance calculated by the microprocessor to the external testing machine.
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