Voltage calibrating device of insulation resistance meter

Abstract

The invention discloses a voltage calibrating device of an insulation resistance meter, which comprises a measuring range switching module, an amplification module, a time delay module, an acquisition module and a control module, and is characterized in that the measuring range switching module is electrically connected with a to-be-calibrated insulation resistance meter, the control module and the amplification module, and the time delay module is electrically connected with the amplification module, the control module and the acquisition module; the acquisition module is electrically connected with the control module; the measuring range switching module is used for switching a measuring range according to a measuring range switching signal so as to output a divided voltage corresponding to the switched measuring range to the amplification module, and the time delay module is used for delaying the amplification signal for a preset time length according to a time delay control signal during measuring range switching and then transmitting the delayed amplification signal to the acquisition module; the control module is used for determining a to-be-calibrated measuring range matched with the collected voltage signal and outputting a corresponding measuring range switching signal and a corresponding delay control signal. According to the invention, the problem of voltage jump during range switching is effectively solved, the verification precision and stability are improved, and manual operation for range switching is not needed.

Description

Technical Field

[0001] The invention belongs to the technical field of insulation resistance meter verification, and in particular relates to a voltage verification device for an insulation resistance meter. Background Art

[0002] As a widely used testing tool in high-voltage electrical equipment, the core function of the 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 verify the accuracy of its voltage output.

[0003] The voltage verification of the insulation resistance meter is to use the voltage verification device of the insulation resistance meter to verify 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 verification device is the voltage error of the insulation resistance meter. Then, the insulation resistance meter is judged to be qualified according to the voltage error and the verification rules. When facing a wide range of high-voltage measurement requirements, the existing voltage verification device of the insulation resistance meter usually relies on manual selection of different ranges. This design not only increases the operating burden of the verification personnel, but also at the critical point of the range switching, it is easy to cause the measurement accuracy to decrease due to the voltage mutation, and even produce jump or unstable output, which seriously affects the credibility of the verification results. In addition to the measurement accuracy problem caused by the range switching, the existing insulation resistance meter also faces the problem of ambient temperature affecting the measurement accuracy during the verification process. When working at different ambient temperatures, the measurement error of the insulation resistance meter will be affected by temperature drift, resulting in data deviation. Traditional methods usually compensate for the temperature drift effect by adding hardware components, but this method is not only costly, but also fails to fundamentally solve the problem, and it is difficult to meet the wide range of needs in practical applications.

[0004] Therefore, a voltage verification device for an insulation resistance meter with high accuracy and stability is needed. Summary of the invention

[0005] In view of this, the present invention provides a voltage verification device for an insulation resistance meter, the main purpose of which is to solve the problems of low verification accuracy and poor stability of the existing voltage verification device for the insulation resistance meter.

[0006] In order to solve the above problems, the present application provides a voltage calibration device for an insulation resistance meter, including a range switching module, an amplification module, a delay module, a collection module and a control module, wherein:

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

[0008] The range switching module is used to divide the output voltage of the insulation resistance meter to be calibrated, and switch 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 to amplify the divided voltage to obtain an amplified signal. The delay module is used to delay the amplified signal for a preset time and transmit it to the acquisition module according to the delay control signal when the range is switched. The acquisition module is used to detect the voltage and obtain a voltage signal. The control module is used to determine the range to be calibrated that matches the voltage signal, and output the corresponding range switching signal and the corresponding delay control signal so as to perform voltage detection under the range to be calibrated and obtain a voltage detection result.

[0009] In one embodiment of the present invention, optionally, the delay module includes a multi-channel analog switch unit and a plurality of delay start branches, wherein:

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

[0011] In one embodiment of the present invention, optionally, each of the delayed start branches includes a first resistor and a first capacitor, and the resistance value of the first resistor in each of the delayed start branches corresponds to the measuring range, wherein,

[0012] In each of the delayed start branches, the first end of the first resistor is electrically connected to a channel output end of the multi-channel analog switch unit, the second end of the first resistor is electrically connected to the first end of the first capacitor and the input end of the acquisition module respectively, and the second end of the first capacitor is electrically connected to the negative electrode of the power supply.

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

[0014] Determine the current range according to the output range switching signal and delay control signal, judge 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, determine that the range to be detected is smaller than the current range, and output the first range switching signal and the first delay control signal corresponding to the adjacent range smaller than the current range;

[0015] After the first range switching signal and the first delay control signal are output, the voltage signal detected by the acquisition module is obtained, and the voltage signal is compared with a threshold voltage. If there is no situation where 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;

[0016] If the voltage signal does not match the voltage range of the current range, a first range switching signal and a 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. Then, the current range is determined to be the range to be detected, and voltage detection is performed under the range to be detected.

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

[0018] If the voltage signal is greater than or equal to the threshold voltage, it is determined that the range to be detected is larger than the current range, and a second range switching signal and a second delay control signal corresponding to an adjacent range larger 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 situation where the voltage signal is greater than or equal to the threshold voltage.

[0020] In one embodiment of the present invention, optionally, the voltage verification device of the insulation resistance meter further comprises: a temperature acquisition module, the temperature acquisition module is electrically connected to the temperature signal input terminal of the control module, the temperature acquisition module is used to collect real-time temperature and transmit it to the control module;

[0021] The controller is also used to obtain a temperature compensation error according to the real-time temperature and a temperature-error relationship model, and to 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.

[0022] In one embodiment of the present invention, optionally, the range switching module includes a voltage dividing unit and a switching control unit, wherein:

[0023] The input end of the voltage divider unit is electrically connected to the voltage output end of the insulation resistance meter to be calibrated, the output end of the voltage divider 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.

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

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

[0026] In one embodiment of the present invention, optionally, each of the switching control branches includes a relay, a transistor and a current limiting resistor, wherein:

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

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

[0029] The present invention provides a voltage calibration device for an insulation resistance meter. The control module compares the voltage signal detected by the acquisition module with the voltage threshold signal and the voltage division range of each range to determine the range to be detected, and outputs a range switching signal and a delay control signal corresponding to the range to be detected to achieve adaptive switching of the range. The delay module transmits the amplified voltage division signal to the acquisition module after a preset delay time when the range is switched according to the delay control signal. The delay module ensures that the voltage division voltage maintains a smooth transition within each range, effectively solving the problem of voltage jump during range switching, avoiding voltage mutation caused by instantaneous switching, improving calibration accuracy and stability, eliminating the need for manual operation to switch the range, improving calibration efficiency, and reducing the workload of operators.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0032] Figure 1 The present invention is a structural block diagram of a voltage verification device for an insulation resistance meter according to an exemplary embodiment of the present invention.

[0033] Figure 2 This is a circuit connection structure diagram of a delay module of a voltage testing device of an insulation resistance meter according to an exemplary embodiment of the present invention.

[0034] Figure 3 The present invention is another structural block diagram of a voltage verification device for an insulation resistance meter according to an exemplary embodiment of the present invention.

[0035] Figure 4 The present invention is a flowchart of a method executed by a control module of a voltage testing device for an insulation resistance meter according to an exemplary embodiment of the present invention.

[0036] Figure 5 A partial circuit connection structure diagram of a range switching module of a voltage verification device of an insulation resistance meter according to an exemplary embodiment of the present invention.

[0037] in,

[0038] The numbers 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 dividing 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-transistor; K1-relay. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0040] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0041] Combine the following Figures 1 to 5 The invention describes a voltage verification device for an insulation resistance meter according to some embodiments of the invention.

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

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

[0044] The range switching module 11 is used to divide the output voltage of the insulation resistance meter 20 to be calibrated, and switch 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 to amplify the divided voltage to obtain an amplified signal. The delay module 13 is used to delay the amplified signal for a preset time according to the delay control signal when the range is switched, and then transmit it to the acquisition module 14. The acquisition module 14 is used for voltage detection to obtain a voltage signal. The control module 15 is used to determine the range to be calibrated that matches the voltage signal, and output the corresponding range switching signal and the corresponding delay control signal, so as to perform voltage detection under the range to be calibrated and obtain a voltage detection result.

[0045] Specifically, the calibration device of the insulation resistance meter consists of two parts: resistance calibration and voltage calibration. Resistance calibration is to calibrate the resistance detection function of the insulation resistance meter, and 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, wherein there are two wiring ports in the range switching module, and these two wiring ports are connected to the output voltage of the insulation resistance meter to be calibrated. 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. A delay module is set between the amplification module and the acquisition module. When the device is just started and the range is switched, the delay module delays the amplified signal for a preset time before transmitting it to the acquisition module to avoid the impact of high voltage transient shock on the acquisition module. The acquisition module transmits the collected voltage signal to the control module. The control module determines whether the current range is the range to be detected, that is, whether the current range matches the input voltage range, based on the voltage signal and threshold signal collected by the acquisition module and the voltage division range corresponding to each range. If the current range is not the range to be detected, the control module outputs a range switching signal and a delay control signal, tentatively searches for a matching range to be detected, and continues to search until a matching range to be detected is found, and then performs voltage detection under the range to be detected.

[0046] Compared with the prior art, the voltage calibration device for an insulation resistance meter provided in the present application determines the range to be detected by comparing the voltage signal detected by the acquisition module with the voltage threshold signal and the voltage division range of each range through the control module, and outputs the range switching signal and the delay control signal corresponding to the range to be detected, so as to realize adaptive switching of the range. The delay module transmits the amplified voltage division signal to the acquisition module after a preset delay time when the range is switched according to the delay control signal. The delay module ensures that the voltage division voltage maintains a smooth transition within each range, effectively solving the problem of voltage jump during range switching, avoiding voltage mutation caused by instantaneous switching, improving calibration accuracy and stability, eliminating the need for manual operation to switch the range, improving calibration efficiency, and reducing the workload of operators.

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

[0048] Specifically, the core of the delay module is to use the capacitor charging time to smoothly control the rise or fall of the input signal, thereby alleviating the sudden change caused by the range switching. When the range is switched, the delay start branch corresponding to the range is started. The delay start branch will limit the rise / fall rate of the voltage to prevent the transient voltage from being directly input to the ADC acquisition module. When switching the range, the delay start branch can be used as a low-pass filter to limit the rise rate of the input voltage, so that the signal changes slowly and reduces the jump problem caused by transient voltage changes. The time constant τ = R × C in the delay start branch determines the speed of voltage change. Selecting the appropriate R and C values ​​can allow the signal to gradually transition when switching the range, effectively reducing the jump phenomenon and alleviating the problems caused by changes in the voltage divider ratio and inconsistent sampling time of the ADC sampling module.

[0049] In one embodiment, a control module is used to implement 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 suspended, and sampling is resumed after the delay start circuit completes charging / discharging. For example, a transition time (such as 50ms) is set in the software to ensure that data sampling is stable when the range is switched.

[0050] In one embodiment, Figure 2As shown, each delayed start branch 132 includes a first resistor R1 and a first capacitor C1, and the resistance value of the first resistor R1 in each delayed start branch 132 corresponds to the measuring range, wherein, in each delayed start branch 132, the first end of the first resistor R1 is electrically connected to a 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 relays to switch the range. Generally, the switch jitter time of the relay is less than 20ms, so the smoothing time of each delayed start branch should be longer than 20ms, and the smoothing time used for a large range should also be longer. For example, the smoothing time of 5000V is 50ms, and the smoothing time of 1000V is 30ms.

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

[0053] τ=R×C=10ms

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

[0055] C=τ / R=10ms / 10kΩ=1μF

[0056] Different ranges have different smoothing times and different selected time constants. Therefore, different ranges correspond to different resistance values ​​in the RC delay start branch. The capacitance value of the capacitor in each delay branch may be the same or different.

[0057] The resistor in each RC delay start branch is connected in series between a 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. 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 RC delay start branch is formed using an adjustable resistor and a capacitor, and the time constant of the RC can be adjusted according to the requirements of the range conversion.

[0059] In one embodiment, an operational amplifier buffer is added after the delay module to drive the ADC sampling module to reduce the influence of the delay module on the ADC input impedance. 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 used to:

[0061] According to the output range switching signal and 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 range to be detected is smaller than the current range, and a first range switching signal and a first delay control signal corresponding to an 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 situation where the voltage signal is greater than or equal to the threshold voltage, it is determined 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, a first range switching signal and a 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 14 matches the voltage range of the current range, then the current range is determined to be the range to be detected, and voltage detection under the range to be detected is performed;

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

[0066] Specifically, by real-time monitoring the voltage value detected by the acquisition module, the range is automatically determined and switched to achieve high-precision measurement in a wide voltage range. While switching the range, the RC delay start circuit is started to avoid jump errors caused by range conversion.

[0067] The system selects the highest range by default for preliminary measurement of input voltage to ensure that high voltage does not cause overload to the circuit. The control module reads the voltage value detected by the acquisition module and sets the safety threshold of the acquisition module. Compare the voltage collected by the acquisition module with the voltage divider 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 divider range of the highest range, it means that the range to be detected matches the current range, and the voltage detection under this range is performed.

[0068] When the voltage collected by the acquisition module does not match the voltage division range corresponding to the highest range, it means that the range to be detected is smaller than the highest range. A small range test is performed, and 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 larger than the current range, and the threshold voltage V is set. s To determine whether the range needs to be increased, when the voltage collected by the acquisition module is greater than the threshold voltage V s It means that the input voltage is larger than the current range. If the voltage rises to the maximum value of the sampled voltage, the acquisition module will enter the overload state. At this time, the control module will immediately disconnect the current range, adjust the range to a high position, adjust the RC delay start circuit to a high position, and resume high-range measurement.

[0069] When the voltage collected by the acquisition module is less than the threshold voltage V s , it means that the input voltage is not larger than the current range. It is determined whether the voltage collected by the acquisition module matches the voltage division range corresponding to the current range. If they match, it means that the current range is the range to be detected, and the voltage detection under this range is performed. If the voltage collected by the acquisition module does not match the voltage division range corresponding to the current range, it means that the range to be detected is smaller than the current range. A small range is tested, and the range is automatically switched to an adjacent range smaller than the current range, and the delay control signal corresponding to the adjacent range is output; repeat the above process, and continue to judge whether the input voltage is larger than the re-switched range, until it is determined that the input voltage is not larger than the re-switched range, and then judge whether the voltage collected by the acquisition module matches the voltage division range corresponding to the current range, until they match, and the voltage detection under this range is performed.

[0070] In one embodiment, Figure 3 As shown, the voltage verification device of the insulation resistance meter also includes: a temperature acquisition module 16, the temperature acquisition module 16 is electrically connected to the temperature signal input end of the control module 15, and the temperature acquisition module 16 is used to collect real-time temperature and transmit it to the control module 15;

[0071] The controller is also used to obtain the temperature compensation error according to the real-time temperature and the relationship model between temperature and error, and to obtain the actual detection voltage of the insulation resistance meter based on the voltage signal detected by the acquisition module 16 and the temperature compensation error.

[0072] Specifically, for the high voltage measuring device of the insulation resistance meter, the impact of temperature changes is mainly reflected in: (1) the resistance drift of the voltage divider resistor: the temperature drift of high-precision voltage divider resistors is usually in the range of 10ppm / ℃ to 100ppm / ℃; (2) ADC sampling error: the reference voltage and gain of the ADC will also be affected by temperature changes; (3) the temperature drift of other components: such as capacitors, operational amplifiers and other components.

[0073] The present application adopts a software temperature compensation method, adds a temperature sensor into the circuit, and transmits the data of the temperature sensor to the control module through the ADC or 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 the 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 the actual voltage detection value.

[0075] In a laboratory environment, measure the output voltage of the voltage divider circuit at different temperatures, and record the temperature and error data. Based on these data, use linear or polynomial fitting to establish a temperature-error relationship model:

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

[0077] Where T is temperature, Error(T) is the error caused by temperature change, and a0, a1, a2... are 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 errors under different temperature conditions, this application uses a temperature compensation algorithm based on a temperature sensor to monitor temperature changes in real time, and preset a temperature compensation model in the control module to dynamically adjust the measured value to compensate for the measurement error caused by ambient temperature changes. 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 occasions where the ambient temperature fluctuates greatly.

[0081] In one embodiment, Figure 4 As shown, the voltage test 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 starts and initializes the peripheral modules (such as ADC acquisition, temperature sensor, etc.). Initialize the range switching signal and delay control signal, that is, Figure 4The startup RC delay soft start circuit ensures that the system runs smoothly during high voltage startup and prevents transient shocks. The range switching signal and 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 for preliminary measurement of input voltage to ensure that high voltage will not cause overload to the circuit. The current range switching signal and delay control signal correspond to the range of 5000V, and the RC delay soft start circuit is started to slowly increase to the 5000V range, providing smooth signal input for subsequent accurate measurement.

[0086] (3) Input voltage division and voltage reduction

[0087] The high-voltage input signal passes through a multi-range voltage divider circuit, and the voltage after voltage division is limited to the input range of the ADC, thereby protecting the acquisition circuit from high-voltage shocks. The voltage-divided signal is input into the ADC module (i.e., 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 and sets the safety threshold of the ADC module. Usually, the input voltage of the ADC module is 0-5V. For example, 80% of the input voltage of the ADC module is selected as the safety threshold voltage, that is, the safety threshold V s =4V. Compare the voltage collected by the ADC module with the voltage division range corresponding to different ranges (5000V, 1000V, 100V): First, enter the highest 5000V range by default for voltage division. When the voltage collected by the ADC module is between 1000V and 5000 corresponding to the voltage division value, it means that the range to be detected is 5000V, and the voltage detection under this range is performed.

[0090] When the voltage collected by the ADC module is less than the voltage division value corresponding to 1000V, it means that the range to be detected is smaller than the range of 5000V. A small range test is performed, and the range is automatically switched to the 1000V range, and a delay control signal corresponding to 1000V is output. At this time, before the voltage is measured in the 1000V range, the system usually does not immediately reset to the highest 5000V range, and the threshold voltage V is set. s It is used to judge whether the range needs to be increased or decreased. When the voltage collected by the ADC module is greater than the threshold voltage V s, it means that the input voltage is larger than the current range. At this time, the voltage is rising smoothly under the action of the RC delay start circuit. 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 5000V, 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 voltage collected by the ADC module is between 1000V and 100 corresponding to the voltage division value, it means that the range to be detected is 1000V, and the voltage detection under this range is performed. If the voltage collected by the ADC module is less than the voltage division value corresponding to 100V, 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 adaptation 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 measurement instability caused by sudden voltage changes.

[0092] (5) Temperature acquisition and compensation

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

[0094] (6) Measurement results display

[0095] The current voltage and selected range are displayed in real time on the LCD screen. When the system detects a voltage change, it continuously monitors the range to ensure a smooth transition near the critical value and improve measurement stability.

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

[0097] Specifically, the voltage divider unit is a precision resistor network, which performs voltage reduction and voltage division processing on the output voltage of the insulation resistance meter to obtain the voltage range corresponding to each range. The switching control unit includes multiple switching control branches. When the switching control unit receives the range switching signal of the control module, the switching control branch matching the range switching signal is connected, and the remaining switching control branches are not connected. The voltage divider signal corresponding to the range is transmitted to the amplification unit through the connected switching control branch, realizing automatic switching of the range and improving the calibration efficiency of the insulation resistance meter.

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

[0099] Specifically, the voltage divider unit is composed of a plurality of high-precision, low-temperature drift voltage divider resistors, which divide the high-voltage signal into a low-voltage measurement range, and the resistance value of each third standard resistor corresponds to a range. High-voltage precision resistors have reached a relatively high performance level and can accurately divide voltages in different ranges (such as 100V, 1000V, 5000V, etc.). Selecting a suitable combination of voltage divider resistors and cooperating with the automatic range switching function of the control module can meet the multi-range measurement requirements and avoid manual switching operations, so as to achieve accurate voltage division of high-voltage signals in each range.

[0100] In one embodiment, Figure 5 As shown, each switching control branch includes a relay K1, a transistor Q1 and a current limiting resistor R5, wherein, 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 a 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 and the positive and negative poles of the power supply, the coil of the relay is energized, and the normally open contacts of the relay are closed. Therefore, the voltage signal across the third standard resistor connected to the normally open contacts of the relay is transmitted to the amplification module through the closed relay contacts.

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

[0103] Specifically, for a 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, and the voltage-divided signal corresponding to the range, that is, the voltage signal across the third standard resistor is transmitted to the two input terminals of the differential amplifier. The differential amplifier amplifies the difference between the two input terminal voltages with a fixed gain to obtain an amplified signal, and transmits the amplified signal to the common terminal of the delay module, so that the delay module delays the amplified signal for a preset time according to the delay control signal when the range is switched and then transmits it to the acquisition module.

[0104] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but only as an example of an embodiment. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

[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 present 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 a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0107] It should also be understood that although the present application has been described with reference to some specific examples, those skilled in the art will be able to readily implement many other equivalent forms of the present application.

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

[0109] Specific embodiments of the present application are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments applied for are merely examples of the present application, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that obscure the present application. Therefore, the specific structural and functional details applied for herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present application in a variety of ways with substantially any suitable detailed structure.

[0110] This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present application.

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

Claims

1. A voltage test device for an insulation resistance meter, characterized in that: include: Range switching module, amplification module, delay module, acquisition module and control module, among which, The input end of the range switching module is electrically connected to the voltage output end of the insulation resistance meter to be calibrated, the control end of the range switching module is electrically connected to the range output end of the control module, the output end of the range switching module is electrically connected to the input end of the amplification module, the output end of the amplification module is electrically connected to the common end of the delay module, the selection input end of the delay module is electrically connected to the delay output end of the control module, the output end of the delay module is electrically connected to the input end of the acquisition module, and the output end of the acquisition module is electrically connected to the input end of the control module; The range switching module is used to divide the output voltage of the insulation resistance meter to be calibrated, and switch 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 to amplify the divided voltage to obtain an amplified signal. The delay module is used to delay the amplified signal for a preset time and transmit it to the acquisition module according to the delay control signal when the range is switched. The acquisition module is used to detect the voltage and obtain a voltage signal. The control module is used to determine the range to be calibrated that matches the voltage signal, and output the corresponding range switching signal and the corresponding delay control signal so as to perform voltage detection under the range to be calibrated and obtain a voltage detection result.

2. The voltage testing device for an insulation resistance meter according to claim 1, characterized in that: The delay module includes a multi-channel analog switch unit and a plurality of delay start branches, wherein: The selection signal input end of the multi-channel analog switch unit is electrically connected to the delay output end of the control module, the common end of the multi-channel analog switch unit is electrically connected to the output end of the amplification module, each channel output end of the multi-channel analog switch unit is electrically connected to the input end of a delay start branch, and the output end of each delay start branch is electrically connected to the input end of the acquisition module.

3. The voltage testing device for an insulation resistance meter according to claim 2, characterized in that: Each of the delay start branches includes a first resistor and a first capacitor, and the resistance value of the first resistor in each of the delay start branches corresponds to the measuring range, wherein, In each of the delayed start branches, the first end of the first resistor is electrically connected to a channel output end of the multi-channel analog switch unit, the second end of the first resistor is electrically connected to the first end of the first capacitor and the input end of the acquisition module respectively, and the second end of the first capacitor is electrically connected to the negative electrode of the power supply.

4. The voltage testing device for an insulation resistance meter according to claim 1, characterized in that: The range switching signal and the delay control signal in the initial state correspond to the maximum range, and the control module is also used for: Determine the current range according to the output range switching signal and delay control signal, judge 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, determine that the range to be detected is smaller than the current range, and output the first range switching signal and the first delay control signal corresponding to the 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 obtained, and the voltage signal is compared with a threshold voltage. If there is no situation where 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, a first range switching signal and a 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. Then, the current range is determined to be the range to be detected, and voltage detection is performed under the range to be detected.

5. The voltage testing device for an insulation resistance meter according to claim 4, characterized in that: The control module is also used for: If the voltage signal is greater than or equal to the threshold voltage, it is determined that the range to be detected is larger than the current range, and a second range switching signal and a second delay control signal corresponding to an adjacent range larger 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 situation where the voltage signal is greater than or equal to the threshold voltage.

6. The voltage testing device for an insulation resistance meter according to claim 1, characterized in that: The voltage verification device of the insulation resistance meter further comprises: a temperature acquisition module, the temperature acquisition module is electrically connected to the temperature signal input terminal of the control module, the temperature acquisition module is used to collect real-time temperature and transmit it to the control module; The controller is also used to obtain a temperature compensation error according to the real-time temperature and a temperature-error relationship model, and to 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 testing device for an insulation resistance meter according to any one of claims 1 to 6, characterized in that: The range switching module includes a voltage dividing unit and a switching control unit, wherein: The input end of the voltage divider unit is electrically connected to the voltage output end of the insulation resistance meter to be calibrated, the output end of the voltage divider 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 testing device for an insulation resistance meter according to claim 7, characterized in that: The voltage verification device of the insulation resistance meter also includes a positive terminal and a negative terminal; the voltage dividing unit includes a first standard resistor, a second standard resistor and a plurality of third standard resistors with different resistance values; the switching control unit includes a plurality of switching control branches, wherein: The first standard resistor, the second standard resistor and multiple third standard resistors are connected in series and are connected in series between the positive electrode terminal and the negative electrode terminal. The positive electrode terminal and the negative electrode terminal are also electrically connected to the voltage output terminal of the insulation resistance meter to be tested; the two ends of each third standard resistor are respectively connected to the first input terminal and the second input terminal of a switching control branch in a one-to-one correspondence.

9. The voltage testing device for an insulation resistance meter according to claim 7, characterized in that: Each of the switching control branches includes a relay, a transistor and a current limiting resistor, wherein: In each of the switching control branches, the base of the transistor is electrically connected to the range output end of the control module through the current limiting resistor, the emitter of the transistor is electrically connected to the negative electrode of the power supply, the collector of the transistor is electrically connected to the first end of the coil of the relay, the second end of the coil of the relay is electrically connected to the positive electrode of the power supply, the first output end of the relay is electrically connected to the first end of the third standard resistor, the second output end of the relay is electrically connected to the first input end of the amplification module, the third output end of the relay is electrically connected to the second end of the third standard resistor, and the fourth output end of the relay is electrically connected to the second input end of the amplification module.

10. The voltage testing device for an insulation resistance meter according to claim 9, characterized in that: The amplification module is a differential amplifier, a first input terminal of the differential amplifier is electrically connected to a second output terminal of the relay, a second input terminal of the differential amplifier is electrically connected to a fourth output terminal of the relay, and an output terminal of the differential amplifier is electrically connected to a common terminal of the delay module.

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