Voltage testing device for insulation resistance meter

Abstract

The application discloses a voltage calibrating device of an insulation resistance meter, comprising a range switching module, an amplification module, a delay module, an acquisition module and a control module, wherein the range switching module is electrically connected with the insulation resistance meter to be calibrated, the control module and the amplification module, the delay module is electrically connected with the amplification module, the control module and the acquisition module, and the acquisition module is electrically connected with the control module; the range switching module is used for switching the range according to a range switching signal, so that a divided voltage corresponding to the switched range is output to the amplification module; the delay module is used for transmitting the amplified signal to the acquisition module after delaying for a preset time length according to a delay control signal when the range is switched; and the control module is used for determining the range to be calibrated matched with the acquired voltage signal, and outputting the corresponding range switching signal and the corresponding delay control signal. The application effectively solves the voltage jump problem when the range is switched, improves the calibration accuracy and stability, and does not need to manually switch the range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of calibrating an insulation resistance meter, and particularly relates to a voltage calibration device for an insulation resistance meter. BACKGROUND

[0002] As a widely used detection tool in high-voltage electrical equipment, the core function of an insulation resistance meter is to measure the insulation performance of electrical equipment to ensure the safety and reliability of equipment operation. In order to ensure the accuracy and reliability of the insulation resistance meter, it needs to be calibrated regularly. The calibration process not only needs to verify the resistance measurement accuracy of the insulation resistance meter, but also needs to calibrate the accuracy of its voltage output.

[0003] The voltage calibration of the insulation resistance meter is to use the voltage calibration device of the insulation resistance meter to calibrate the output voltage of the insulation resistance meter. The difference between the actual output voltage of the insulation resistance meter and the voltage detected by the voltage calibration device is the voltage error of the insulation resistance meter. Then, according to the voltage error and the calibration rules, it is judged whether the insulation resistance meter is qualified. In the face of wide range of high-voltage measurement demand, the existing voltage calibration device of the insulation resistance meter usually relies on manual selection of different ranges. This design not only increases the operation burden of the calibrators, but also at the critical point of range switching, the measurement accuracy is easily reduced due to voltage mutation, and even jump or unstable output is generated, which seriously affects the credibility of the calibration results. In addition to the measurement accuracy problem caused by range switching, the existing insulation resistance meter also faces the problem of environmental temperature affecting the measurement accuracy during the calibration process. When working at different environmental temperatures, the measurement error of the insulation resistance meter will be affected by temperature drift, resulting in data deviation. The traditional method usually compensates the temperature drift effect by increasing hardware components, but this method not only has high cost, but also fails to fundamentally solve the problem, and is difficult to meet the wide demand in practical application.

[0004] Therefore, there is a need for a voltage calibration device for an insulation resistance meter with high precision and stability. SUMMARY

[0005] Therefore, the application provides a voltage calibration device for an insulation resistance meter, which mainly aims to solve the problems of low calibration accuracy and poor stability of the existing voltage calibration device for an insulation resistance meter.

[0006] To solve the above problems, the application provides a voltage calibration device for an insulation resistance meter, which comprises a range switching module, an amplification module, a delay module, an acquisition module and a control module, wherein,

[0007] The input end of the range switching module is electrically connected with the voltage output end of the insulation resistance meter to be tested, the control end of the range switching module is electrically connected with the range output end of the control module, the output end of the range switching module is electrically connected with the input end of the amplification module, the output end of the amplification module is electrically connected with the common end of the time delay module, the selection input end of the time delay module is electrically connected with the time delay output end of the control module, the output end of the time delay module is electrically connected with the input end of the acquisition module, and the output end of the acquisition module is electrically connected with the input end of the control module.

[0008] The range switching module is used for dividing the output voltage of the insulation resistance meter to be tested, and switching the range according to the range switching signal, so that the divided voltage corresponding to the switched range is output to the amplification module, the amplification module is used for amplifying the divided voltage to obtain an amplified signal, the time delay module is used for transmitting the amplified signal to the acquisition module after delaying for a preset time length according to the time delay control signal when the range is switched, the acquisition module is used for detecting the voltage to obtain a voltage signal, and the control module is used for determining the to-be-tested range matched with the voltage signal, and outputting the corresponding range switching signal and the corresponding time delay control signal, so as to perform the voltage detection under the to-be-tested range and obtain a voltage detection result.

[0009] In an embodiment of the present application, optionally, the time delay module comprises a multi-channel analog switch unit and a plurality of time delay starting branches, wherein,

[0010] The selection signal input end of the multi-channel analog switch unit is electrically connected with the time delay output end of the control module, the common end of the multi-channel analog switch unit is electrically connected with the output end of the amplification module, and each channel output end of the multi-channel analog switch unit is electrically connected with the input end of a time delay starting branch.

[0011] In an embodiment of the present application, optionally, each time delay starting branch comprises a first resistor and a first capacitor, and the resistance value of the first resistor in each time delay starting branch corresponds to a range.

[0012] In each time delay starting branch, the first end of the first resistor is electrically connected with a channel output end of the multi-channel analog switch unit, the second end of the first resistor is respectively electrically connected with the first end of the first capacitor and the input end of the acquisition module, and the second end of the first capacitor is electrically connected with the negative electrode of the power supply.

[0013] In an embodiment of the present application, optionally, the range switching signal and the time delay control signal in the initial state correspond to the maximum range, and the control module is further used for:

[0014] According to the range switching signal and the delay control signal output, the current range is determined, whether the voltage signal detected by the acquisition module matches the voltage range of the current range is judged, if the voltage signal does not match the voltage range of the current range, it is determined that the to-be-detected range is smaller than the current range, and the first range switching signal and the first delay control signal corresponding to the adjacent range smaller than the current range are output;

[0015] After the first range switching signal and the first delay control signal are output, the voltage signal detected by the acquisition module is acquired, and whether the voltage signal matches the voltage range of the current range is compared with the threshold voltage, if there is no case that the voltage signal is greater than or equal to the threshold voltage, whether the voltage signal detected by the acquisition module matches the voltage range of the current range is judged;

[0016] If the voltage signal does not match the voltage range of the current range, the first range switching signal and the first delay control signal corresponding to the adjacent range smaller than the current range are output until the voltage signal detected by the acquisition module matches the voltage range of the current range, and then it is determined that the current range is the to-be-detected range, and the voltage detection under the to-be-detected range is performed.

[0017] In an embodiment of the present application, optionally, the control module is further used for:

[0018] If there is a case that the voltage signal is greater than or equal to the threshold voltage, it is determined that the to-be-detected range is greater than the current range, and the second range switching signal and the second delay control signal corresponding to the adjacent range greater than the current range are output;

[0019] After the second range switching signal and the second delay control signal are output, the voltage signal detected by the acquisition module is compared with the threshold voltage again until there is no case that the voltage signal is greater than or equal to the threshold voltage.

[0020] In an embodiment of the present application, optionally, the voltage calibrating device of the insulation resistance meter further comprises a temperature acquisition module, the temperature acquisition module is electrically connected with the temperature signal input end of the control module, and the temperature acquisition module is used for acquiring real-time temperature and transmitting the real-time temperature to the control module;

[0021] The controller is further used for obtaining a temperature compensation error according to the real-time temperature and a temperature and error relationship model, and obtaining an actual detection voltage of the insulation resistance meter based on the voltage signal detected by the acquisition module and the temperature compensation error.

[0022] In an embodiment of the present application, optionally, the range switching module comprises a voltage dividing unit and a switching control unit, wherein,

[0023] The input end of the voltage dividing unit is electrically connected with the voltage output end of the insulation resistance meter to be tested, the output end of the voltage dividing unit is electrically connected with the input end of the switching control unit, the control end of the switching control unit is electrically connected with the range output end of the control module, and the output end of the switching control unit is electrically connected with the input end of the amplification module.

[0024] In one embodiment of the present application, optionally, the voltage testing device of the insulation resistance meter further comprises a positive terminal and a negative terminal; the voltage dividing unit comprises a first standard resistor, a second standard resistor and a plurality of third standard resistors with different resistance values, and the switching control unit comprises a plurality of switching control branches, wherein,

[0025] The first standard resistor, the second standard resistor and the plurality of third standard resistors are connected in series and connected in series between the positive terminal and the negative terminal, and the positive terminal and the negative terminal are also electrically connected with the voltage output end of the insulation resistance meter to be tested; the two ends of each third standard resistor are respectively connected with the first input end and the second input end of one switching control branch in one-to-one correspondence.

[0026] In one embodiment of the present application, optionally, each switching control branch comprises a relay, a transistor and a current limiting resistor, wherein,

[0027] In each switching control branch, the base of the transistor is electrically connected with the range output end of the control module through the current limiting resistor, the emitter of the transistor is electrically connected with the negative pole of the power supply, the collector of the transistor is electrically connected with the first end of the coil of the relay, the second end of the coil of the relay is electrically connected with the positive pole of the power supply, the first output end of the relay is electrically connected with the first end of the third standard resistor, the second output end of the relay is electrically connected with the first input end of the amplification module, the third output end of the relay is electrically connected with the second end of the third standard resistor, and the fourth output end of the relay is electrically connected with the second input end of the amplification module.

[0028] In one embodiment of the present application, optionally, the amplification module is a differential amplifier, the first input end of the differential amplifier is electrically connected with the second output end of the relay, the second input end of the differential amplifier is electrically connected with the fourth output end of the relay, and the output end of the differential amplifier is electrically connected with the common end of the delay module.

[0029] The voltage detection device of the insulation resistance meter provided by the application comprises a control module, a delay module, a range switching module and a collection module.

[0030] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0031] Various other advantages and benefits will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments, and are not meant to limit the present application. Furthermore, the same reference numerals are used throughout the several drawings to denote the same or similar parts. In the drawings:

[0032] Figure 1 The structure block diagram of the voltage detection device of the insulation resistance meter for an exemplary embodiment of the application.

[0033] Figure 2 The circuit connection structure diagram of the delay module of the voltage detection device of the insulation resistance meter for an exemplary embodiment of the application.

[0034] Figure 3 The structure block diagram of the voltage detection device of the insulation resistance meter for another exemplary embodiment of the application.

[0035] Figure 4 The method flow chart executed by the control module of the voltage detection device of the insulation resistance meter for an exemplary embodiment of the application.

[0036] Figure 5 The partial circuit connection structure diagram of the range switching module of the voltage detection device of the insulation resistance meter for an exemplary embodiment of the application.

[0037] Among them,

[0038] The labels are as follows: 11-range switching module; 12-amplification module; 13-delay module; 14-acquisition module; 15-control module; 20-insulation resistance meter to be tested; 111-voltage division unit; 112-switching control unit; 131-multi-channel analog switch unit; 132-delay start branch; 16-temperature acquisition module; R1-first resistor; C1-first capacitor; R2-first standard resistor; R3-second standard resistor; R4-third standard resistor; R5-current limiting resistor; Q1-triode; K1-relay. DETAILED DESCRIPTION

[0039] Hereinafter, the present application will be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0041] The following will be described in conjunction with Figures 1 to 5 A voltage testing device for insulation resistance meter according to some embodiments of the present application is described.

[0042] In one embodiment, as Figure 1 shown, a voltage testing device for insulation resistance meter includes a range switching module 11, an amplification module 12, a delay module 13, an acquisition module 14 and a control module 15, wherein,

[0043] The input end of the range switching module 11 is electrically connected with the voltage output end of the insulation resistance meter 20 to be tested, the control end of the range switching module 11 is electrically connected with the range output end of the control module 15, the output end of the range switching module 11 is electrically connected with the input end of the amplification module 12, the output end of the amplification module 12 is electrically connected with the common end of the delay module 13, the selection input end of the delay module 13 is electrically connected with the delay output end of the control module 15, the output end of the delay module 13 is electrically connected with the input end of the acquisition module 14, and the output end of the acquisition module 14 is electrically connected with the input end of the control module 15;

[0044] The range switching module 11 is used for dividing the output voltage of the insulation resistance meter 20 to be tested, switching the range according to the range switching signal, so that the divided voltage corresponding to the switched range is output to the amplification module 12. The amplification module 12 is used for amplifying the divided voltage to obtain an amplified signal. The delay module 13 is used for transmitting the amplified signal to the acquisition module 14 after delaying for a preset time according to the delay control signal when the range is switched. The acquisition module 14 is used for detecting the voltage to obtain a voltage signal. The control module 15 is used for determining the range to be tested matched with the voltage signal, and outputting the corresponding range switching signal and the corresponding delay control signal, so as to perform the voltage detection under the range to be tested, and obtain the voltage detection result.

[0045] Specifically, the calibrating device of the insulation resistance meter is composed of two parts of resistance calibration and voltage calibration. The resistance calibration is to calibrate the resistance detection function of the insulation resistance meter, and the voltage calibration is to calibrate the voltage output function of the insulation resistance meter. The voltage calibration part is composed of a range switching module, an amplification module, a delay module, an acquisition module and a control module. The range switching module has two wiring ports connected to the output voltage of the insulation resistance meter to be tested. The input voltage is stepped down by the range switching module to obtain a divided voltage corresponding to each range. The range switching module switches the range according to the range switching signal output by the control module, so that the divided voltage corresponding to the switched range is transmitted to the amplification module. The delay module is arranged between the amplification module and the acquisition module. The delay module delays the amplified signal for a preset time before transmitting it to the acquisition module when the device is just started and the range is switched, so as to avoid the influence of high voltage transient impact on the acquisition module. The acquisition module transmits the acquired voltage signal to the control module. The control module determines whether the current range is the range to be tested according to the voltage signal acquired by the acquisition module, the threshold signal and the divided voltage range corresponding to each range, i.e. whether the current range matches the input voltage range. If the current range is not the range to be tested, the range switching signal and the delay control signal are output to find the matched range to be tested, and the voltage detection under the range to be tested is performed.

[0046] Compared with the prior art, the voltage detection device of the insulation resistance meter provided by the application determines the to-be-detected range by comparing the voltage signal detected by the acquisition module with the voltage threshold signal and the voltage range of each range through the control module, and outputs the range switching signal and the delay control signal corresponding to the to-be-detected range, so that the adaptive switching of the range is realized. The amplified voltage signal is transmitted to the acquisition module after being delayed for a preset time length by the delay module according to the delay control signal, so that the voltage signal is smoothly transitioned in each range range through the delay module, effectively solving the voltage jump problem during range switching, avoiding the voltage mutation caused by instantaneous switching, improving the detection accuracy and stability, eliminating the need for manual operation to switch the range, improving the detection efficiency, and reducing the work burden of the operator.

[0047] In one embodiment, as shown in Figure 2 The delay module 13 includes a multi-channel analog switch unit 131 and a plurality of delay start branches 132. The selection signal input end of the multi-channel analog switch unit 131 is electrically connected with the delay output end of the control module 15, the common end of the multi-channel analog switch unit 131 is electrically connected with the output end of the amplification module 12, and each channel output end of the multi-channel analog switch unit 131 is electrically connected with the input end of one delay start branch 132. The output end of each delay start branch 132 is electrically connected with the input end of the acquisition module 14.

[0048] Specifically, the core of the delay module is to use the charging time of the capacitor to smooth the rising or falling of the input signal, so as to alleviate the mutation caused by range switching. When the range is switched, the delay start branch corresponding to the range is started, and the delay start branch limits the rising / falling rate of the voltage, avoiding the instantaneous voltage directly input to the ADC acquisition module. When the range is switched, the delay start branch can be used as a low-pass filter to limit the rising rate of the input voltage, so that the signal changes slowly and the jump problem caused by the transient voltage change is reduced. The time constant τ=RxC in the delay start branch determines the speed of voltage change, and appropriate R and C values can make the signal gradually transition when the range is switched, effectively reducing the jump phenomenon and alleviating the problem caused by the inconsistency of the sampling time of the ADC sampling module.

[0049] In one embodiment, the control module is used to realize the soft start control on the software. When the range is switched from a small range to a large range, the sampling of the ADC sampling module is paused, and the sampling is resumed after the delay start circuit completes the charging / discharging. For example, a transition time (such as 50 ms) is set in the software to ensure that the data sampling is stable when the range is switched.

[0050] In one embodiment, as shown in Figure 2As shown, each delay start branch 132 includes a first resistor R1 and a first capacitor C1, and the resistance value of the first resistor R1 in each delay start branch 132 corresponds to the range, wherein in each delay start branch 132, the first end of the first resistor R1 is electrically connected to one channel output end of the multi-channel analog switch unit 131, the second end of the first resistor R1 is electrically connected to the first end of the first capacitor C1 and the input end of the acquisition module 14 respectively, and the second end of the first capacitor is electrically connected to the negative electrode of the power supply.

[0051] Specifically, the range switching module uses a relay to switch the range. The switching jitter time of a general relay is below 20 ms, so the smoothing time of each delay start branch is longer than 20 ms, and the smoothing time of a large range is also larger, for example, the smoothing time of 5000 V is 50 ms, the smoothing time of 1000 V is 30 ms, and the like.

[0052] Taking the smoothing transition time of 30 ms as an example when switching the range, the time constant τ can be selected as 10 ms (because generally 3τ is selected to be approximately equal to the transition time).

[0053] τ = R x C = 10 ms

[0054] If R = 10 kΩ is selected, the capacitor C is:

[0055] C = τ / R = 10 ms / 10 kΩ = 1 μF

[0056] The smoothing time of different ranges is different, and the time constant selected is also different, so the resistance value of the resistor in the RC delay start branch corresponding to different ranges is different, and the capacity value of the capacitor in each delay branch can be the same or different.

[0057] In the RC delay start branch, the resistor is connected in series between the one channel output end of the multi-channel analog switch unit and the input end of the ADC acquisition module, and a capacitor is connected to the ground at the input end of the ADC acquisition module, and when any channel of the multi-channel analog switch is connected, the RC delay start branch connected to the channel is started.

[0058] In one embodiment, an adjustable resistor and a capacitor are used to form an RC delay start branch, and the time constant of the RC can be adjusted according to the requirement of range conversion.

[0059] In one embodiment, an operational amplifier buffer is added after the delay module to drive the ADC sampling module, reducing the influence of the delay module on the input impedance of the ADC. The buffer provides low output impedance to ensure that the sampling accuracy of the ADC acquisition module is not affected by the RC delay circuit.

[0060] In one embodiment, the range switching signal and the delay control signal in the initial state correspond to the maximum range, and the control module 15 is further configured to:

[0061] According to the output range switching signal and the delay control signal, the current range is determined, and it is judged whether the voltage signal detected by the acquisition module 14 matches the voltage range of the current range. If the voltage signal does not match the voltage range of the current range, it is determined that the to-be-detected range is smaller than the current range, and the first range switching signal and the first delay control signal corresponding to the adjacent range smaller than the current range are output.

[0062] After the first range switching signal and the first delay control signal are output, the voltage signal detected by the acquisition module 14 is obtained, and the voltage signal is compared with the threshold voltage. If there is no case that the voltage signal is greater than or equal to the threshold voltage, it is judged whether the voltage signal detected by the acquisition module 14 matches the voltage range of the current range.

[0063] If the voltage signal does not match the voltage range of the current range, the first range switching signal and the first delay control signal corresponding to the adjacent range smaller than the current range are output until the voltage signal detected by the acquisition module 14 matches the voltage range of the current range, and then it is determined that the current range is the to-be-detected range, and the voltage detection in the to-be-detected range is performed.

[0064] If there is a case that the voltage signal is greater than or equal to the threshold voltage, it is determined that the to-be-detected range is greater than the current range, and the second range switching signal and the second delay control signal corresponding to the adjacent range greater than the current range are output.

[0065] After the second range switching signal and the second delay control signal are output, the voltage signal detected by the acquisition module 14 is compared with the threshold voltage again until there is no case that the voltage signal is greater than or equal to the threshold voltage.

[0066] Specifically, by monitoring the voltage value detected by the acquisition module in real time, the range is automatically judged and switched to realize high-precision measurement in a wide voltage range. At the same time of switching the range, the RC delay start circuit is started to avoid the jump error caused by the range conversion.

[0067] The system selects the highest range by default, which is used for preliminary measurement of the input voltage to ensure that the high voltage does not cause an overload effect on the circuit. The control module reads the voltage value detected by the acquisition module and sets the safety threshold of the acquisition module. The voltage collected by the acquisition module is compared with the voltage range corresponding to different ranges: taking the default highest range as an example, when the voltage collected by the acquisition module corresponds to the voltage range of the highest range, it is indicated that the to-be-detected range matches the current range, and the voltage detection in the range is performed.

[0068] When the voltage collected by the collection module does not match the voltage division range corresponding to the highest range, it indicates that the to-be-detected range is smaller than the highest range, a small-range trial is performed, the range is automatically switched to an adjacent range smaller than the highest range, and a delay control signal corresponding to the adjacent range is output; after the range is switched, it is determined whether the input voltage is greater than the current range, and the threshold voltage V s is set to determine whether the range needs to be raised. s When the voltage collected by the collection module is greater than the threshold voltage V s , it indicates that the input voltage is greater than the current range. If the voltage rises to the maximum value collected by the sampling voltage, the collection module will enter an overload state. At this time, the current range is immediately disconnected by the control module, the range is adjusted to the high gear, the RC delay start circuit is also adjusted to the high gear, and the high gear measurement is continued.

[0069] When the voltage collected by the collection module is less than the threshold voltage V s , it indicates that the input voltage is not greater than the current range. It is determined whether the voltage collected by the collection module matches the voltage division range corresponding to the current range. If it matches, it indicates that the current range is the to-be-detected range, and voltage detection under the range is performed. If the voltage collected by the collection module does not match the voltage division range corresponding to the current range, it indicates that the to-be-detected range is smaller than the current range, a small-range trial is performed, the range is automatically switched to an adjacent range smaller than the current range, and a delay control signal corresponding to the adjacent range is output; the above process is repeated to determine whether the input voltage is greater than the range after the switching, until it is determined that the input voltage is not greater than the range after the switching, and then it is determined whether the voltage collected by the collection module matches the voltage division range corresponding to the current range, until it matches, and voltage detection under the range is performed.

[0070] In one embodiment, as shown in Figure 3 , the voltage verification device of the insulation resistance meter further comprises a temperature collection module 16 electrically connected to a temperature signal input end of the control module 15, the temperature collection module 16 being configured to collect real-time temperature and transmit the real-time temperature to the control module 15.

[0071] The controller is further configured to obtain a temperature compensation error according to the real-time temperature and a temperature-error relationship model, and obtain an actual detection voltage of the insulation resistance meter based on the voltage signal detected by the collection module 16 and the temperature compensation error.

[0072] Specifically, for the high-voltage measurement device of the insulation resistance meter, the temperature change mainly affects: (1) resistance drift of the voltage dividing resistor: the temperature drift of the high-precision voltage dividing resistor is usually within 10ppm / ℃ to 100ppm / ℃; (2) ADC sampling error: the reference voltage and gain of the ADC are also affected by temperature change; (3) temperature drift of other components: such as capacitors, operational amplifiers, etc.

[0073] The application adopts a software temperature compensation method, adds a temperature sensor in the circuit, and transmits data of the temperature sensor to a control module through an ADC or a digital interface. The control module performs temperature compensation calculation based on the collected temperature.

[0074] The control module first establishes a temperature correction model, calculates a voltage error according to the temperature correction model, and then performs compensation calculation based on the voltage error and the collected voltage value to obtain an actual voltage detection value.

[0075] In a laboratory environment, the output voltage of the voltage divider circuit at different temperatures is measured, and the temperature and error data are recorded. Based on these data, a linear or polynomial fitting is used to establish a temperature and error relationship model:

[0076] Error(T)=a0+a1*T+a2*T 2 +........+a n *T n

[0077] Wherein, T is the temperature, Error(T) is the error caused by the temperature change, and a0, a1, a2,..., are the fitting coefficients.

[0078] In actual measurement, the current temperature T is read, the error value is calculated according to the temperature compensation model, and then the actual detection voltage value after compensation is calculated:

[0079] V(comp)=V(measured)-Error(T).

[0080] Since the insulation resistance meter will produce temperature drift error under different temperature conditions, the application adopts a temperature compensation algorithm based on a temperature sensor, which can monitor the temperature change in real time and preset a temperature compensation model in the control module to dynamically adjust the measurement value and compensate for the measurement error caused by the change of the environmental temperature. This function significantly improves the measurement reliability and accuracy of the voltage verification device under different temperature conditions, and is particularly suitable for use in environments with large temperature fluctuations.

[0081] In one embodiment, as shown in Figure 4 The voltage verification device has a range of 100V, 1000V and 5000V, and the control module performs the following steps:

[0082] (1) System initialization

[0083] The control module is started, and each peripheral module (such as ADC acquisition, temperature sensor, etc.) is initialized. The range switching signal and the delay control signal are initialized, i.e. Figure 4The start-up RC delay soft start circuit in the control module ensures smooth operation of the system during high-voltage start-up and prevents transient impact. The range switching signal and the delay control signal correspond to the highest range in the initial state.

[0084] (2) Initial range setting

[0085] The system defaults to the highest range of 5000V, which is used for preliminary measurement of the input voltage to ensure that high voltage does not cause an overload impact on the circuit. Both the current range switching signal and the delay control signal correspond to the range of 5000V, and the start-up RC delay soft start circuit is started to slowly rise to the 5000V range, providing smooth signal input for subsequent accurate measurement.

[0086] (3) Input voltage division and reduction

[0087] The high-voltage input signal passes through the multi-range division circuit, and the divided voltage is limited within the input range of the ADC, thereby protecting the acquisition circuit from high-voltage impact. The divided signal is input into the ADC module (i.e., the sampling module) for high-precision voltage sampling.

[0088] (4) Range determination and switching

[0089] The control module obtains the voltage value detected by the acquisition module, sets the safety threshold of the ADC module, and the ADC module can input a voltage of 0-5V, for example, 80% of the input voltage of the ADC module is selected as the safety threshold voltage, i.e., the safety threshold V s = 4V. The voltage collected by the ADC module is compared with the voltage range corresponding to different ranges (5000V, 1000V, 100V): first, the highest 5000V range is entered by default for voltage division, and when the voltage collected by the ADC module is between 1000V and 5000V, it is determined that the range to be detected is 5000V, and voltage detection is performed in this range.

[0090] When the voltage collected by the ADC module is less than 1000V, it is determined that the range to be detected is smaller than the 5000V range, and a small-range trial is performed to automatically switch the range to the 1000V range and output the delay control signal corresponding to 1000V. At this time, the system does not immediately reset to the highest 5000V range before completing the measurement in the 1000V range, and the threshold voltage V s is set to determine whether the range needs to be raised or lowered. When the voltage collected by the ADC module is greater than the threshold voltage V sWhen the input voltage is greater than the current range, the circuit is under the action of the RC delay start circuit, and the voltage rises smoothly. If the voltage rises to 5V, the ADC module will enter an overload state. At this time, the control module immediately disconnects the 1000V range, adjusts the range to the 5000V gear, adjusts the RC delay start circuit to 5000V, and continues to measure 5000V. When the voltage collected by the ADC module is less than the threshold voltage V s When the input voltage is not greater than the current range, and the voltage collected by the ADC module is between 1000V and 100V corresponding to the voltage division value, it indicates that the to-be-detected range is 1000V, and voltage detection is performed in this range. If the voltage collected by the ADC module is less than 100V corresponding to the voltage division value, the range is further switched to 100V, and the RC delay start circuit is also adjusted to 100V.

[0091] Similarly, in the 100V range, the threshold voltage V s The collected voltage is judged, and the range self-adaptive flow chart is as follows Figure 4 Each time the range is switched, the RC delay soft start circuit is restarted to ensure smooth switching and avoid unstable measurement caused by sudden voltage changes.

[0092] (5) Temperature acquisition and compensation

[0093] The control module obtains the current environmental temperature through the temperature sensor. According to the collected temperature data, the control module applies a temperature compensation algorithm to correct the measurement results, so as to eliminate the influence of temperature changes on the voltage measurement accuracy.

[0094] (6) Measurement result display

[0095] The current voltage and selected range are displayed in real time through the LCD screen. The system continuously monitors the range when detecting voltage changes to ensure smooth transition near the critical value and improve measurement stability.

[0096] In one embodiment, the range switching module 11 includes a voltage division unit 111 and a switching control unit 112, wherein the input end of the voltage division unit 111 is electrically connected with the voltage output end of the to-be-tested insulation resistance meter 20, the output end of the voltage division unit 111 is electrically connected with the input end of the switching control unit 112, the control end of the switching control unit 112 is electrically connected with the range output end of the control module 15, and the output end of the switching control unit 112 is electrically connected with the input end of the amplification module 12.

[0097] Specifically, the voltage dividing unit is a precision resistance network, which performs voltage reduction and voltage division on the output voltage of the insulation resistance meter to obtain a voltage range corresponding to each range. The switching control unit includes multiple switching control branches. When the switching control unit receives a range switching signal from the control module, the switching control branch matched with the range switching signal is connected, and the remaining switching control branches are not connected. The voltage signal corresponding to the range is transmitted to the amplification unit through the connected switching control branch to realize automatic switching of the range and improve the efficiency of the insulation resistance meter.

[0098] In one embodiment, as shown in Figure 5 the voltage calibration device of the insulation resistance meter further includes a positive terminal post and a negative terminal post; the voltage dividing unit 111 includes a first standard resistor R2, a second standard resistor R3, and multiple third standard resistors R4 with different resistance values, and the switching control unit 112 includes multiple switching control branches. The first standard resistor R2, the second standard resistor R3, and the multiple third standard resistors R4 are connected in series and connected between the positive terminal post and the negative terminal post. The positive terminal post and the negative terminal post are also electrically connected to the voltage output end of the insulation resistance meter 20 to be calibrated. The two ends of each third standard resistor R4 are respectively connected to the first input end and the second input end of one switching control branch in a one-to-one correspondence.

[0099] Specifically, the voltage dividing unit is composed of multiple high-precision and low-temperature-drift voltage dividing resistors. The multiple high-precision and low-temperature-drift voltage dividing resistors divide the high-voltage signal into a low-voltage measurement range, and the resistance value of each third standard resistor corresponds to one range. The high-voltage precision resistor has reached a high performance level and can accurately divide the voltage in different ranges (such as 100V, 1000V, 5000V, etc.). By selecting appropriate combinations of voltage dividing resistors and the automatic range switching function of the control module, the multi-range measurement requirement can be met, and manual switching operation is avoided, realizing accurate voltage division of the high-voltage signal in each range.

[0100] In one embodiment, as shown in Figure 5 each switching control branch includes a relay K1, a transistor Q1, and a current-limiting resistor R5. In each switching control branch, the base of the transistor Q1 is electrically connected to the range output end of the control module 15 through the current-limiting resistor R5, the emitter of the transistor Q1 is electrically connected to the negative electrode of the power supply, the collector of the transistor Q1 is electrically connected to the first end of the coil of the relay K1, the second end of the coil of the relay K1 is electrically connected to the positive electrode of the power supply, the first output end of the relay K1 is electrically connected to the first end of the third standard resistor R4, the second output end of the relay K1 is electrically connected to the first input end of the amplification module 12, the third output end of the relay K1 is electrically connected to the second end of the third standard resistor R4, and the fourth output end of the relay K1 is electrically connected to the second input end of the amplification module 12.

[0101] Specifically, for one range, the control module sends the range switching signal corresponding to the range to the base of the transistor, the transistor is turned on, the coil of the relay forms a loop with the transistor, the positive and negative poles of the power supply, the coil of the relay is powered, and the normally open contact of the relay is closed, so that the voltage signal between the two ends of the third standard resistor connected with the normally open contact of the relay is transmitted to the amplification module through the closed relay contact.

[0102] In one embodiment, the amplification module 12 is a differential amplifier, the first input end of the differential amplifier is electrically connected with the second output end of the relay K1, the second input end of the differential amplifier is electrically connected with the fourth output end of the relay K1, and the output end of the differential amplifier is electrically connected with the common end of the delay module 13.

[0103] Specifically, for one range, the range switching signal corresponding to the range is transmitted to the relay of the switching control branch corresponding to the range, the normally open contact of the relay is closed, the voltage signal between the two ends of the third standard resistor, i.e. the voltage signal of the voltage divider corresponding to the range, is transmitted to the two input ends of the differential amplifier, the differential amplifier amplifies the difference between the voltages of the two input ends with a fixed gain to obtain an amplified signal, and transmits the amplified signal to the common end of the delay module, so that the delay module transmits the amplified signal to the acquisition module after delaying for a preset time length according to the delay control signal during range switching.

[0104] It should be understood that various modifications can be made to the embodiments disclosed herein. Therefore, the foregoing description should not be taken as limiting, but merely as exemplification of the embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the application.

[0105] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the application given above, and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0106] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting example only, with reference to the attached drawings.

[0107] It should also be understood that, while the present application has been described above with reference to particular embodiments, many alternatives, modifications, and equivalents will be apparent to those of ordinary skill in the art.

[0108] The above and other aspects, features, and advantages of the present application will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, when properly considered together.

[0109] Specific embodiments of the application are described herein with reference to the drawings; however, it will be understood that the application is merely an example of the application and can be embodied in many ways. Well-known and / or redundant functions and structures are not described in detail to avoid obscuring the application unnecessarily. Therefore, specific structural and functional details disclosed herein are not to be interpreted in defining the scope of the claims but merely as illustrative bases for the claims and representative bases for teaching one skilled in the art to use the application in virtually any appropriate detailed structure.

[0110] The specification can use phrases such as "in one embodiment", "in another embodiment", "in yet another embodiment", or "in other embodiments", which can refer to one or more of the same or different embodiments of the application.

[0111] The above embodiments are only exemplary embodiments of the application, not intended to limit the application, and the protection scope of the application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the application within the spirit and protection scope of the application, and such modifications or equivalent replacements shall also be considered to fall within the protection scope of the application.

Claims

1. A voltage verification device for an insulation resistance meter, characterized by comprising: The application relates to an insulation resistance table detection device. The device comprises a range switching module, an amplification module, a delay module, a collection module and a control module, wherein, The input end of the range switching module is electrically connected with the voltage output end of an insulation resistance table to be detected, the control end of the range switching module is electrically connected with the range output end of the control module, the output end of the range switching module is electrically connected with the input end of the amplification module, the output end of the amplification module is electrically connected with the common end of the delay module, the selection input end of the delay module is electrically connected with the delay output end of the control module, the output end of the delay module is electrically connected with the input end of the collection module, and the output end of the collection module is electrically connected with the input end of the control module. The range switching module is used for carrying out voltage division on the output voltage of the insulation resistance table to be detected, and the range switching module is used for switching the range according to a range switching signal, so that the divided voltage corresponding to the switched range is output to the amplification module; the amplification module is used for amplifying the divided voltage to obtain an amplified signal; the delay module is used for transmitting the amplified signal to the collection module after the amplified signal is delayed for a preset time length according to a delay control signal when the range is switched; the collection module is used for detecting the voltage to obtain a voltage signal; and the control module is used for determining a to-be-detected range matched with the voltage signal, and outputting a corresponding range switching signal and a corresponding delay control signal, so that the voltage detection under the to-be-detected range is carried out to obtain a voltage detection result.

2. The voltage verification device for an insulation resistance meter according to claim 1, characterized by The delay module comprises a multi-channel analog switch unit and a plurality of delay starting branches. The selection signal input end of the multi-channel analog switch unit is electrically connected with the delay output end of the control module, the common end of the multi-channel analog switch unit is electrically connected with the output end of the amplification module, each channel output end of the multi-channel analog switch unit is electrically connected with the input end of one delay starting branch, and the output end of each delay starting branch is electrically connected with the input end of the collection module.

3. The voltage verification device for an insulation resistance meter according to claim 2, characterized by Each delay starting branch comprises a first resistor and a first capacitor, and the resistance value of the first resistor in each delay starting branch corresponds to a range. In each delay starting branch, the first end of the first resistor is electrically connected with one channel output end of the multi-channel analog switch unit, the second end of the first resistor is respectively electrically connected with the first end of the first capacitor and the input end of the collection module, and the second end of the first capacitor is electrically connected with the negative electrode of a power supply.

4. The voltage verification device for an insulation resistance meter according to claim 1, wherein The range switching signal and the delay control signal in an initial state correspond to a maximum range, and the control module is further used for: determining a current range according to the output range switching signal and the delay control signal, judging whether the voltage signal detected by the collection module matches the voltage range of the current range, determining that the to-be-detected range is smaller than the current range if the voltage signal does not match the voltage range of the current range, and outputting a first range switching signal and a first delay control signal corresponding to an adjacent range smaller than the current range. After the first range switching signal and the first delay control signal are output, the voltage signal detected by the acquisition module is acquired, and the voltage signal is compared with a threshold voltage; if there is no case that the voltage signal is greater than or equal to the threshold voltage, it is determined whether the voltage signal detected by the acquisition module matches the voltage range of the current range; If the voltage signal does not match the voltage range of the current range, the first range switching signal and the first delay control signal corresponding to an adjacent range smaller than the current range are output until the voltage signal detected by the acquisition module matches the voltage range of the current range, and then it is determined that the current range is the to-be-detected range, and voltage detection under the to-be-detected range is performed.

5. The voltage verification device for an insulation resistance meter according to claim 4, wherein The control module is further configured to: If there is a case that the voltage signal is greater than or equal to the threshold voltage, it is determined that the to-be-detected range is greater than the current range, and the second range switching signal and the second delay control signal corresponding to an adjacent range greater than the current range are output; After the second range switching signal and the second delay control signal are output, the voltage signal detected by the acquisition module is compared with the threshold voltage again until there is no case that the voltage signal is greater than or equal to the threshold voltage.

6. The voltage verification device for an insulation resistance meter according to claim 1, wherein The voltage verification device of the insulation resistance meter further comprises a temperature acquisition module, which is electrically connected to a temperature signal input end of the control module, and is configured to acquire real-time temperature and transmit the real-time temperature to the control module; The control module is further configured to obtain a temperature compensation error according to the real-time temperature and a temperature-error relationship model, and obtain an actual detection voltage of the insulation resistance meter based on the voltage signal detected by the acquisition module and the temperature compensation error.

7. The voltage verification device for insulation resistance meters according to any one of claims 1 to 6, characterized in that The range switching module comprises a voltage dividing unit and a switching control unit, wherein The input end of the voltage dividing unit is electrically connected to the voltage output end of the to-be-verified insulation resistance meter, the output end of the voltage dividing unit is electrically connected to the input end of the switching control unit, the control end of the switching control unit is electrically connected to the range output end of the control module, and the output end of the switching control unit is electrically connected to the input end of the amplification module.

8. The voltage verification device for an insulation resistance meter according to claim 7, wherein The voltage verification device of the insulation resistance meter further comprises a positive terminal post and a negative terminal post; the voltage dividing unit comprises a first standard resistor, a second standard resistor, and a plurality of third standard resistors with different resistances, and the switching control unit comprises a plurality of switching control branches, wherein The first standard resistor, the second standard resistor, and the plurality of third standard resistors are connected in series and connected in series between the positive terminal post and the negative terminal post, and the positive terminal post and the negative terminal post are also electrically connected to the voltage output end of the to-be-verified insulation resistance meter; the two ends of each third standard resistor are respectively connected to the first input end and the second input end of one switching control branch in one-to-one correspondence.

9. The voltage verification device for an insulation resistance meter according to claim 8, wherein Each switching control branch comprises a relay, a triode, and a current-limiting resistor, wherein In each of the switching control branches, the base of the transistor is electrically connected with the range output end of the control module through the current limiting resistor, the emitter of the transistor is electrically connected with the negative pole of the power supply, the collector of the transistor is electrically connected with the first end of the coil of the relay, the second end of the coil of the relay is electrically connected with the positive pole of the power supply, the first output end of the relay is electrically connected with the first end of the third standard resistor, the second output end of the relay is electrically connected with the first input end of the amplification module, the third output end of the relay is electrically connected with the second end of the third standard resistor, and the fourth output end of the relay is electrically connected with the second input end of the amplification module.

10. The voltage verification device for an insulation resistance meter according to claim 9, wherein The amplification module is a differential amplifier, the first input end of the differential amplifier is electrically connected with the second output end of the relay, the second input end of the differential amplifier is electrically connected with the fourth output end of the relay, and the output end of the differential amplifier is electrically connected with the common end of the delay module.

Images