A current sampling resistor fault diagnosis circuit, device and diagnosis method

Abstract

The present invention relates to a current sampling resistor fault diagnosis circuit, device and diagnosis method. The diagnosis circuit comprises: a first contact end, the first contact end is connected to the first end of a first switch S1, the first end of a second switch S2, and an ADC; the second end of the first switch S1 is connected to a test power supply Iout; the second end of the second switch S2 is connected to a reverse end of an amplifier; the output end of the amplifier is connected to a reverse end of a unit gain differential amplifier circuit; a second contact end, the second contact end is connected to the first end of a third switch S3 and the first end of a fourth switch S4; the second end of the third switch S3 is connected to a unidirectional end of the unit gain differential amplifier circuit; the second end of the third switch S3 is also connected to the first end of a resistor RF; the second end of the resistor RF is connected to the output end of the amplifier; the output end of the unit gain differential amplifier circuit is connected to the ADC; the second end of the fourth switch S4 is connected to the input end of a voltage bias circuit; and the output end of the voltage bias circuit is connected to the ADC.

Description

Technical Field

[0001] The present invention relates to the field of automation control technology, and in particular to a current sampling resistor fault diagnosis circuit, device and diagnosis method. Background Art

[0002] The current sampling module at the industrial site is the most common supporting module for the input components of industrial control systems such as DCS and SIS. The current sampling module is mainly used to convert the current signal at the site into a voltage signal and input it into the voltage input component. Among them, current acquisition most often involves current sampling resistors. In the long-term use process, the sampling resistors will inevitably have accuracy drift, resistance open short circuit and other faults. These faults will reduce the reliability of the current conversion module and thus affect the safety of the control process. Therefore, it is necessary to diagnose the fault of the sampling resistor.

[0003] The prior art uses a bridge measurement method as follows Figure 7 As shown, Ra, Rb, and Rc are known high-precision and low-temperature drift reference resistors, Rd is the resistor to be measured, and Re, Rf, and Rg are auxiliary resistors that constitute the bridge measurement circuit. This solution connects three known high-precision and low-temperature drift resistors Ra, Rb, and Rc to the same branch of the bridge, respectively, and collects three sets of data through the DA1 differential amplifier to calculate the parameters of the current bridge measurement circuit. After the calculation of the bridge measurement circuit parameters is completed, the resistor to be measured is connected to the bridge measurement circuit. Finally, the accurate resistance value of the resistor to be measured is calculated through the known bridge measurement circuit parameters. In the process of calculating the resistor to be measured, there is no need to care about the parameters of the measurement circuit, and the final result is only related to Ra, Rb, and Rc.

[0004] The measurement accuracy of this method is completely dependent on three high-precision, low-temperature drift resistors. During the measurement of the resistance value to be measured, there must be no additional current on the resistor to be measured. In addition, this method cannot eliminate the error of the connection resistance between the measurement circuit and the resistor to be measured during the measurement process. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a current sampling resistor fault diagnosis circuit, device and diagnosis method, which solve the technical problems that the prior art cannot eliminate the connection resistance error between the measuring circuit and the resistor to be measured, and cannot perform measurement when there is an external current on the resistor to be measured.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] In a first aspect, an embodiment of the present invention provides a current sampling resistor fault diagnosis circuit, the diagnosis circuit is used to diagnose a circuit to be tested; the circuit to be tested includes a diagnosis resistor R1 and a sampling resistor R2, the first end of the diagnosis resistor R1 is connected to the sampling current signal input positive terminal, the second end of the diagnosis resistor R1 is connected to the first end of the sampling resistor R2, the second end of the sampling resistor R2 is connected to the sampling current signal input negative terminal, the diagnosis circuit includes:

[0010] A first contact end, wherein the first contact end is respectively connected to a first end of the first switch S1, a first end of the second switch S2 and an ADC;

[0011] The second end of the first switch S1 is connected to the inspection power supply Iout;

[0012] The second end of the second switch S2 is connected to the reverse end of the amplifier;

[0013] The output end of the amplifier is connected to the reverse end of the unit gain differential amplifier circuit;

[0014] a second contact end, the second contact end being connected to a first end of a third switch S3 and a first end of a fourth switch S4 respectively;

[0015] The second end of the third switch S3 is connected to the same direction end of the unit gain differential amplifier circuit;

[0016] The second end of the third switch S3 is also connected to the first end of the resistor RF;

[0017] The second end of the resistor RF is also connected to the output end of the amplifier;

[0018] The output end of the unit gain differential amplifier circuit is connected to the ADC;

[0019] The second end of the fourth switch S4 is connected to the input end of the voltage bias circuit;

[0020] The voltage bias circuit is used to superimpose a bias voltage V0 on the voltage passing through the voltage bias circuit;

[0021] The output end of the voltage bias circuit is connected to the ADC.

[0022] On the other hand, this embodiment also provides a current sampling resistor fault diagnosis device, including the above-mentioned diagnosis circuit and the circuit to be tested;

[0023] The circuit to be tested comprises a diagnostic resistor R1 and a sampling resistor R2, wherein a first end of the diagnostic resistor R1 is connected to a sampling current signal input positive end, a second end of the diagnostic resistor R1 is connected to a first end of the sampling resistor R2, and a second end of the sampling resistor R2 is connected to a sampling current signal input negative end;

[0024] The diagnostic circuit is connected to the circuit to be tested via a cable.

[0025] Preferably,

[0026] The first contact end of the diagnostic circuit is connected to the first end of the diagnostic resistor R1 in the circuit to be tested through a cable R3;

[0027] The second contact end of the diagnostic circuit is connected to the first end of the sampling resistor R2 in the circuit to be tested through a cable R4.

[0028] On the other hand, this embodiment provides a current sampling resistor fault diagnosis method based on any of the above current sampling resistor fault diagnosis devices, including:

[0029] A1, obtaining a first voltage value of a first end of the diagnostic resistor R1 in the current sampling resistor fault diagnosis device;

[0030] The first voltage value is a voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit through ADC when the first switch S1, the second switch S2, and the third switch S3 in the current sampling resistor fault diagnosis device are all disconnected;

[0031] A2. Determine whether the first voltage value is 0;

[0032] If it is 0, the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are closed to obtain the second voltage value V2 and the third voltage value V3;

[0033] The second voltage value V2 is the voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit ADC when the circuit to be tested is connected to the inspection power supply Iout;

[0034] The third voltage value V3 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC when the circuit to be tested is connected to the inspection power supply Iout;

[0035] Based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnosis resistor R1 and / or the sampling resistor R2 is determined.

[0036] Preferably,

[0037] If the second voltage value V2 is greater than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault;

[0038] If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is less than a preset threshold value, it is determined that the diagnostic resistor R1 is short-circuited;

[0039] The fourth voltage value is a difference between the third voltage value V3 and the bias voltage V0 of the voltage bias circuit;

[0040] If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is greater than 20V, it is determined that the sampling resistor R2 has an open circuit fault;

[0041] If the second voltage value V2 is less than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the sampling resistor R2 is short-circuited.

[0042] Preferably, after determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, the method further includes:

[0043] Obtain the resistance value of the sampling resistor R2 based on formula (1);

[0044] The formula (1) is:

[0045]

[0046] Wherein, V3 is the third voltage value;

[0047] V0 is the bias voltage of the voltage bias circuit;

[0048] Iout is the current emitted by the test power supply;

[0049] Obtaining a first resistance RA based on formula (2), and using the first resistance RA as the resistance of the diagnostic resistor R1;

[0050] The formula (2) is

[0051]

[0052] Wherein, V2 is the second voltage value.

[0053] Preferably, the method further comprises:

[0054] A3. If it is not 0, obtain the fifth voltage value V5 and the sixth voltage value V6;

[0055] The fifth voltage value V5 is the voltage value of the first end of the diagnostic resistor R1 when the diagnostic circuit in the current sampling resistor fault diagnosis device is in the condition that the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed;

[0056] The sixth voltage value V6 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC in the current sampling resistor fault diagnosis device when the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed;

[0057] According to the fifth voltage value V5 and the sixth voltage value V6, the K value is obtained by using formula (3);

[0058] The formula (3) is:

[0059]

[0060] Based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 is determined.

[0061] Preferably,

[0062] If the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault;

[0063] If the K value is equal to 1, and the sum of the fifth voltage value V5 and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has a short circuit fault;

[0064] If the K value is equal to 1, and the sum of the fifth voltage value V5 and the bias voltage V0 of the voltage bias circuit is equal to the sixth voltage value V6, it is determined that the sampling resistor R2 has an open circuit fault;

[0065] If the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that a short circuit fault occurs in the sampling resistor R2.

[0066] Preferably, A3 also includes:

[0067] After determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, the method further includes:

[0068] The first switch S1 and the fourth switch S4 of the current sampling resistor fault diagnosis circuit are opened, and the second switch S2 and the third switch S3 are closed, so as to obtain the seventh voltage value V7 and the eighth voltage value V8;

[0069] The seventh voltage value V7 is the voltage value of the output end of the voltage bias circuit collected by the diagnosis circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened, and the second switch S2 and the third switch S3 are closed;

[0070] The eighth voltage value V8 is the voltage value of the output end of the unit gain differential circuit collected by the diagnostic circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened, and the second switch S2 and the third switch S3 are closed;

[0071] Based on the K value, the seventh voltage value V7, the eighth voltage value V8, the bias voltage V0 of the voltage bias circuit, and the resistance value of the resistor RF, the resistance value of the diagnostic resistor R1 is obtained using formula (4);

[0072] The formula (4) is:

[0073]

[0074] Wherein, V8 is the eighth voltage value;

[0075] V7 is the seventh voltage value;

[0076] RF is the resistance value of resistor RF.

[0077] Preferably, A3 further comprises:

[0078] Based on the K value and the resistance value of the diagnostic resistor R1, the resistance value of the sampling resistor R2 is obtained using formula (5);

[0079] The formula (5) is:

[0080]

[0081] (III) Beneficial effects

[0082] The beneficial effects of the present invention are as follows: a current sampling resistor fault diagnosis circuit, device and diagnosis method of the present invention, when an external current exists in the circuit to be tested, a current sampling resistor fault diagnosis circuit of the present invention can obtain the accurate ratio of the sampling resistor to be diagnosed and the reference resistor without additional reference current, thereby obtaining the accurate sampling resistor accuracy in real time, and at the same time eliminating the error introduced by the wiring resistance between the circuit to be diagnosed and the diagnosis circuit, thereby realizing high-precision sampling resistor diagnosis.

[0083] A current sampling resistor fault diagnosis circuit of the present invention can be used when there is no external current in the circuit to be tested by switching a switch, and by controlling the current flow path, the error introduced by the wiring resistance between the circuit to be diagnosed and the diagnosis circuit is also eliminated, thereby achieving high-precision sampling resistor diagnosis, and the circuit is simple and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 A schematic diagram of a current sampling resistor fault diagnosis circuit of the present invention;

[0085] Figure 2 A schematic diagram of a current sampling resistor fault diagnosis device of the present invention;

[0086] Figure 3 A flow chart of a current sampling resistor fault diagnosis method of the present invention;

[0087] Figure 4 It is a schematic diagram of a current sampling resistor fault diagnosis device in which a first switch S1, a second switch S2, and a third switch S3 are all opened;

[0088] Figure 5 It is a schematic diagram of a current sampling resistor fault diagnosis device in which the first switch S1, the second switch S2, and the third switch S3 are all opened, and the fourth switch S4 is closed;

[0089] Figure 6 It is a schematic diagram of a current sampling resistor fault diagnosis device of the present invention in which the first switch S1 and the fourth switch S4 are opened, and the second switch S2 and the third switch S3 are closed;

[0090] Figure 7 It is a schematic diagram of a circuit based on bridge measurement in the prior art.

[0091] [Description of Reference Numerals]

[0092] 1: first contact end;

[0093] 2: second contact terminal;

[0094] M: Voltage bias circuit. DETAILED DESCRIPTION

[0095] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0096] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0097] See also Figure 1 This embodiment provides a current sampling resistor fault diagnosis circuit, the diagnosis circuit is used to diagnose the circuit to be tested; the circuit to be tested includes a diagnosis resistor R1 and a sampling resistor R2, the first end of the diagnosis resistor R1 is connected to the sampling current signal input positive terminal, the second end of the diagnosis resistor R1 is connected to the first end of the sampling resistor R2, and the second end of the sampling resistor R2 is connected to the sampling current signal input negative terminal, the diagnosis circuit includes:

[0098] A first contact end, wherein the first contact end is respectively connected to a first end of the first switch S1 , a first end of the second switch S2 , and the ADC.

[0099] A second end of the first switch S1 is connected to the inspection power source Iout.

[0100] The second end of the second switch S2 is connected to the inverting end of the amplifier.

[0101] The output end of the amplifier is connected to the reverse end of the unit gain differential amplifier circuit.

[0102] The second contact end is connected to the first end of the third switch S3 and the first end of the fourth switch S4 respectively.

[0103] The second end of the third switch S3 is connected to the same-direction end of the unit gain differential amplifier circuit.

[0104] The second end of the third switch S3 is also connected to the first end of the resistor RF.

[0105] The second end of the resistor RF is also connected to the output end of the amplifier.

[0106] The output end of the unit gain differential amplifier circuit is connected to the ADC.

[0107] The second end of the fourth switch S4 is connected to the input end of the voltage bias circuit.

[0108] The voltage bias circuit is used to superimpose a bias voltage V0 on the voltage passing through the voltage bias circuit.

[0109] The output end of the voltage bias circuit is connected to the ADC.

[0110] See also Figure 2 This embodiment also provides a current sampling resistor fault diagnosis device, including the above-mentioned diagnosis circuit and a circuit to be tested.

[0111] The circuit to be tested includes a diagnostic resistor R1 and a sampling resistor R2, wherein a first end of the diagnostic resistor R1 is connected to a sampling current signal input positive end, a second end of the diagnostic resistor R1 is connected to a first end of the sampling resistor R2, and a second end of the sampling resistor R2 is connected to a sampling current signal input negative end.

[0112] The diagnostic circuit is connected to the circuit to be tested via a cable.

[0113] In practical applications of this embodiment, the first contact end of the diagnostic circuit is connected to the first end of the diagnostic resistor R1 in the circuit to be tested through a cable R3.

[0114] The second contact end of the diagnostic circuit is connected to the first end of the sampling resistor R2 in the circuit to be tested through a cable R4.

[0115] See also Figure 3 This embodiment also provides a current sampling resistor fault diagnosis method based on any of the above current sampling resistor fault diagnosis devices, including:

[0116] A1. Obtain a first voltage value at a first end of the diagnostic resistor R1 in the current sampling resistor fault diagnosis device.

[0117] See also Figure 2 The first voltage value is the voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit through ADC when the first switch S1, the second switch S2, and the third switch S3 in the current sampling resistor fault diagnosis device are all disconnected.

[0118] A2. Determine whether the first voltage value is 0.

[0119] Specifically, before the diagnosis starts, the first switch S1, the second switch S2, and the third switch S3 are all turned on, and the diagnostic circuit directly collects the voltage value of the first end of the diagnostic resistor R1 through the ADC. When the voltage value of the first end of the diagnostic resistor R1 is greater than 0, the diagnostic circuit determines that there is an initial current in the circuit to be tested. When the voltage value of the first end of the diagnostic resistor R1 is equal to 0, there is no initial current in the circuit to be tested.

[0120] If it is 0, the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are closed. Figure 4 , obtain the second voltage value V2 and the third voltage value V3.

[0121] The second voltage value V2 is a voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit ADC when the circuit to be tested is connected to the inspection power supply Iout.

[0122] The third voltage value V3 is a voltage value at the output end of the voltage bias circuit collected by the diagnosis circuit ADC when the circuit to be tested is connected to the inspection power supply Iout.

[0123] Specifically, when only the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are closed, see Figure 4 , the diagnostic circuit outputs the test current Iout to the sampling circuit. At this time, the current flow path is Iout→R3→R1→R2. Iout generates diagnostic voltages VR1 and VR2 on R1 and R2, and generates an error voltage on R3. Therefore, the second voltage value V2 actually collected by the diagnostic circuit satisfies the following equation:

[0124] V2=(R1+R2+R3)×Iout.

[0125] The diagnostic voltage VR2 generated on R2 is increased to a third voltage value V3 after being superimposed with the bias voltage V0 by the voltage bias circuit in the diagnostic circuit, and then sent to the ADC for collection.

[0126] The diagnostic voltage VR2 and the third voltage value V3 generated on R2 satisfy the following equation:

[0127] VR2=Iout×R2.

[0128] V3=VR2+V0.

[0129] The third voltage value V3 is a voltage obtained by superimposing the bias voltage V0 on the voltage at the first end of the sampling resistor R2 through the voltage bias circuit in the diagnosis circuit.

[0130] The voltage at the first end of the sampling resistor R2 is the voltage at the first end of the sampling resistor R2 when the inspection circuit in the current sampling resistor fault diagnosis device is closed.

[0131] Based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnosis resistor R1 and / or the sampling resistor R2 is determined.

[0132] In practical applications of this embodiment, if the second voltage value V2 is greater than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault.

[0133] If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is less than a preset threshold, it is determined that the diagnostic resistor R1 is short-circuited.

[0134] The fourth voltage value is a difference between the third voltage value V3 and the bias voltage V0 of the voltage bias circuit.

[0135] If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is greater than 20V, it is determined that the sampling resistor R2 has an open circuit fault.

[0136] If the second voltage value V2 is less than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the sampling resistor R2 is short-circuited.

[0137] In practical applications of this embodiment, after determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, the following further comprises:

[0138] The resistance value of the sampling resistor R2 is obtained based on formula (1).

[0139] The formula (1) is:

[0140]

[0141] Wherein, V3 is the third voltage value.

[0142] V0 is the bias voltage of the voltage bias circuit.

[0143] Iout is the current emitted by the test power supply.

[0144] A first resistance RA is obtained based on formula (2), and the first resistance RA is used as the resistance of the diagnostic resistor R1.

[0145] The formula (2) is

[0146]

[0147] Wherein, V2 is the second voltage value.

[0148] R2 is a sampling resistor. It can be seen from the above formula that the error introduced by the cable R4 between the sampling circuit to be diagnosed and the diagnostic circuit is effectively eliminated by controlling the current flow path, thereby further improving the diagnostic accuracy.

[0149] The finally measured resistance value of R1 (ie, the first resistance value RA) includes the error introduced by the cable R3. In practical applications, R1 is a diagnostic resistor whose accuracy requirement is lower than that of the sampling resistor R2. Therefore, the error introduced by the cable R3 has little effect on R1.

[0150] In the practical application of this embodiment, the method further includes:

[0151] A3. If it is not 0, obtain the fifth voltage value V5 and the sixth voltage value V6;

[0152] Specifically, the first switch S1, the second switch S2, and the third switch S3 are all opened, and the fourth switch S4 is closed. At this time, the equivalent diagram of the circuit to be tested and the diagnostic circuit is as follows: Figure 5 As shown, at this time, the external current I1 to be sampled generates sampling voltages B1 and B2 on R1 and R2. Since the flow path of the external current I1 is Iin+→R1→R2→Iin- and does not flow through R3 and R4, there is no voltage difference between R3 and R4. Therefore, the voltage collected by the diagnostic circuit is B1 and B2. B1 is directly sampled by the ADC in the diagnostic circuit, which is the fifth voltage value V5. B2 is converted into the sixth voltage value V6 after being superimposed with the bias voltage V0 by the forward bias circuit inside the diagnostic circuit and then sampled by the ADC. At this time, the ratio K value of the sampling resistor R2 and the diagnostic resistor R1 can be obtained.

[0153] See also Figure 5 , the fifth voltage value V5 is the voltage value of the first end of the diagnostic resistor R1 when the diagnostic circuit in the current sampling resistor fault diagnosis device is in the condition that the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed;

[0154] See also Figure 5 , the sixth voltage value V6 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC in the current sampling resistor fault diagnosis device when the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed;

[0155] See also Figure 5 , the fifth voltage value V5 is directly collected by the ADC in the diagnosis circuit.

[0156] See also Figure 5 The sixth voltage value V6 is a voltage obtained by superimposing the bias voltage V0 on the voltage at the first end of the sampling resistor R2 through the voltage bias circuit in the diagnostic circuit.

[0157] See also Figure 5The voltage at the first end of the sampling resistor R2 is the voltage at the first end of the sampling resistor R2 when the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed in the inspection circuit in the current sampling resistor fault diagnosis device.

[0158] The K value is obtained by using formula (3) according to the fifth voltage value V5 and the sixth voltage value V6.

[0159] The formula (3) is:

[0160]

[0161] Based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 is determined.

[0162] In practical applications of this embodiment, if the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault.

[0163] If the K value is equal to 1, and the sum of the fifth voltage value V5 and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that a short circuit fault occurs in the diagnostic resistor R1.

[0164] If the K value is equal to 1, and the sum of the fifth voltage value V5 and the bias voltage V0 of the voltage bias circuit is equal to the sixth voltage value V6, it is determined that an open circuit fault occurs in the sampling resistor R2.

[0165] If the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that a short circuit fault occurs in the sampling resistor R2.

[0166] In the practical application of this embodiment, A3 also includes:

[0167] After determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, the method further includes:

[0168] See also Figure 6 , the first switch S1 and the fourth switch S4 of the diagnostic circuit of the current sampling resistor fault diagnosis device are opened, and the second switch S2 and the third switch S3 are closed, and the seventh voltage value V7 and the eighth voltage value V8 are obtained;

[0169] Specifically, the first switch S1 and the fourth switch S4 of the current sampling resistor fault diagnosis circuit are opened, and the second switch S2 and the third switch S3 are closed. At this time, the equivalent circuit diagram of the circuit to be tested and the diagnosis circuit is as follows: Figure 6 As shown, the current IRF on RF at this time is the sum of the current IR1 on R1 and the current IR2 on R2, that is:

[0170] IR1=I1

[0171] IR2=I1×R1 / R2

[0172] IRF=IR1+IR2.

[0173] At the same time, it also satisfies: IRF = II×(1+R1 / R2); VRF = (I1×RF) / (1+R1 / R2).

[0174] The voltage at the second terminal of the diagnostic resistor R1=-I1×R1.

[0175] After the switch S2 is closed, the voltage at the first end of the diagnostic resistor R1 is 0, and I1 flows from the diagnostic resistor R1 to the resistor RF. At this time, the voltage at the second end of the diagnostic resistor R1 is a negative voltage. Therefore, the voltage on the sampling resistor R2 is increased to a positive voltage seventh voltage value V7 by superimposing the bias voltage V0 through the voltage bias circuit, and is collected by the ADC. The voltage VRF at both ends of the resistor RF is output as an eighth voltage value V8 after passing through the unit gain differential amplifier circuit, and is collected by the ADC.

[0176] At this time, the diagnostic resistor R1 and the sampling resistor R2 satisfy the following equation:

[0177]

[0178] See also Figure 6 The seventh voltage value V7 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened and the second switch S2 and the third switch S3 are closed.

[0179] See also Figure 6 The eighth voltage value V8 is the voltage value at the output end of the unit gain differential circuit collected by the diagnostic circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened and the second switch S2 and the third switch S3 are closed.

[0180] The seventh voltage value V7 is a voltage obtained by superimposing the bias voltage V0 on the voltage at the first end of the sampling resistor R2 through the voltage bias circuit.

[0181] The eighth voltage value V8 is the voltage obtained by collecting the voltage across the resistor RF through a unit gain differential amplifier circuit and then by the ADC.

[0182] Based on the K value, the seventh voltage value V7, the eighth voltage value V8, the bias voltage V0 of the voltage bias circuit, and the resistance value of the resistor RF, the resistance value of the diagnostic resistor R1 is obtained using formula (4).

[0183] The formula (4) is:

[0184]

[0185] Among them, V8 is the eighth voltage value.

[0186] V7 is the seventh voltage value.

[0187] RF is the resistance value of resistor RF.

[0188] In the practical application of this embodiment, S3 also includes:

[0189] Based on the K value and the resistance value of the diagnostic resistor R1, the resistance value of the sampling resistor R2 is obtained using formula (5). The formula (5) is:

[0190] A current sampling resistor fault diagnosis circuit, device and diagnosis method of the present embodiment. When there is an external current in the circuit to be tested, the current sampling resistor fault diagnosis circuit of the present invention can obtain the accurate ratio of the sampling resistor to be diagnosed and the reference resistor without additional reference current, so that the accurate sampling resistor accuracy can be obtained in real time. At the same time, the error introduced by the wiring resistance between the circuit to be diagnosed and the diagnosis circuit is eliminated, thereby realizing high-precision sampling resistor diagnosis.

[0191] A current sampling resistor fault diagnosis circuit of the present embodiment can be used when there is no external current in the circuit to be tested by switching the switch, and the error introduced by the wiring resistance between the circuit to be diagnosed and the diagnosis circuit is also eliminated by controlling the current flow path, thereby realizing high-precision sampling resistor diagnosis, and the circuit is simple and reliable.

[0192] Since the device described in the above embodiment of the present invention is a device used to implement the method of the above embodiment of the present invention, based on the method described in the above embodiment of the present invention, a person skilled in the art can understand the specific structure and deformation of the device, so it is not described here. All devices used in the method of the above embodiment of the present invention belong to the scope of protection of the present invention.

[0193] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0194] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions.

[0195] It should be noted that in the claims, any reference numerals placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the claims enumerating several means, several of these means may be embodied by the same hardware. The use of the words first, second, third, etc., is for convenience of expression only and does not indicate any order. These words may be understood as part of the component name.

[0196] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0197] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments after knowing the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0198] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

Claims

1. A current sampling resistor fault diagnosis circuit, characterized in that: The diagnostic circuit is used to diagnose the circuit to be tested; the circuit to be tested includes a diagnostic resistor R1 and a sampling resistor R2, the first end of the diagnostic resistor R1 is connected to the positive end of the sampling current signal input, the second end of the diagnostic resistor R1 is connected to the first end of the sampling resistor R2, and the second end of the sampling resistor R2 is connected to the negative end of the sampling current signal input, and the diagnostic circuit includes: A first contact end, wherein the first contact end is respectively connected to a first end of the first switch S1, a first end of the second switch S2 and an ADC; The second end of the first switch S1 is connected to the inspection power supply Iout; The second end of the second switch S2 is connected to the reverse end of the amplifier; The output end of the amplifier is connected to the reverse end of the unit gain differential amplifier circuit; a second contact end, the second contact end being connected to a first end of a third switch S3 and a first end of a fourth switch S4 respectively; The second end of the third switch S3 is connected to the same direction end of the unit gain differential amplifier circuit; The second end of the third switch S3 is also connected to the first end of the resistor RF; The second end of the resistor RF is also connected to the output end of the amplifier; The output end of the unit gain differential amplifier circuit is connected to the ADC; The second end of the fourth switch S4 is connected to the input end of the voltage bias circuit; The voltage bias circuit is used to superimpose a bias voltage V0 on the voltage passing through the voltage bias circuit; The output end of the voltage bias circuit is connected to the ADC.

2. A current sampling resistor fault diagnosis device, characterized in that: comprising the diagnostic circuit and the circuit to be tested as claimed in claim 1; The circuit to be tested comprises a diagnostic resistor R1 and a sampling resistor R2, wherein a first end of the diagnostic resistor R1 is connected to a sampling current signal input positive end, a second end of the diagnostic resistor R1 is connected to a first end of the sampling resistor R2, and a second end of the sampling resistor R2 is connected to a sampling current signal input negative end; The diagnostic circuit is connected to the circuit to be tested via a cable.

3. The device according to claim 2, characterized in that The first contact end of the diagnostic circuit is connected to the first end of the diagnostic resistor R1 in the circuit to be tested through a cable R3; The second contact end of the diagnostic circuit is connected to the first end of the sampling resistor R2 in the circuit to be tested through a cable R4.

4. A current sampling resistor fault diagnosis method based on the current sampling resistor fault diagnosis device according to any one of claims 2 to 3, characterized in that: include: A1, obtaining a first voltage value of a first end of the diagnostic resistor R1 in the current sampling resistor fault diagnosis device; The first voltage value is a voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit through ADC when the first switch S1, the second switch S2, and the third switch S3 in the current sampling resistor fault diagnosis device are all disconnected; A2. Determine whether the first voltage value is 0; If it is 0, close the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device to obtain the second voltage value V2 and the third voltage value V3; The second voltage value V2 is the voltage value of the first end of the diagnostic resistor R1 collected by the diagnostic circuit ADC when the circuit to be tested is connected to the inspection power supply Iout; The third voltage value V3 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC when the circuit to be tested is connected to the inspection power supply Iout; Based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnosis resistor R1 and / or the sampling resistor R2 is determined.

5. The method according to claim 4, characterized in that If the second voltage value V2 is greater than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault; If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is less than a preset threshold value, it is determined that the diagnostic resistor R1 is short-circuited; The fourth voltage value is a difference between the third voltage value V3 and the bias voltage V0 of the voltage bias circuit; If the second voltage value V2 is equal to the fourth voltage value, and the fourth voltage value is greater than 20V, it is determined that the sampling resistor R2 has an open circuit fault; If the second voltage value V2 is less than a preset threshold value, and the third voltage value V3 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the sampling resistor R2 is short-circuited.

6. The method according to claim 5, characterized in that After determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the second voltage value V2, the third voltage value V3 and the bias voltage V0 of the voltage bias circuit, the method further includes: Obtain the resistance value of the sampling resistor R2 based on formula (1); The formula (1) is: Wherein, V3 is the third voltage value; V0 is the bias voltage of the voltage bias circuit; Iout is the current emitted by the test power supply; Obtaining a first resistance RA based on formula (2), and using the first resistance RA as the resistance of the diagnostic resistor R1; The formula (2) is Wherein, V2 is the second voltage value.

7. The diagnostic method according to claim 4, characterized in that: The method further comprises: A3. If it is not 0, obtain the fifth voltage value V5 and the sixth voltage value V6; The fifth voltage value V5 is the voltage value of the first end of the diagnostic resistor R1 when the diagnostic circuit in the current sampling resistor fault diagnosis device is in the condition that the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed; The sixth voltage value V6 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC in the current sampling resistor fault diagnosis device when the first switch S1, the second switch S2, and the third switch S3 are all disconnected and the fourth switch S4 is closed; According to the fifth voltage value V5 and the sixth voltage value V6, the K value is obtained by using formula (3); The formula (3) is: Based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, a fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 is determined.

8. The method according to claim 7, characterized in that If the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has an open circuit fault; If the K value is equal to 1, and the sum of the fifth voltage value V5 and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that the diagnostic resistor R1 has a short circuit fault; If the K value is equal to 1, and the sum of the fifth voltage value V5 and the bias voltage V0 of the voltage bias circuit is equal to the sixth voltage value V6, it is determined that the sampling resistor R2 has an open circuit fault; If the K value is equal to 0, and the sixth voltage value V6 is equal to the bias voltage V0 of the voltage bias circuit, it is determined that a short circuit fault occurs in the sampling resistor R2.

9. The method according to claim 8, characterized in that Said A3 also includes: After determining the fault condition of the diagnostic resistor R1 and / or the sampling resistor R2 based on the K value, the fifth voltage value V5, the sixth voltage value V6, and the bias voltage V0 of the voltage bias circuit, the method further includes: The first switch S1 and the fourth switch S4 of the current sampling resistor fault diagnosis circuit are opened, and the second switch S2 and the third switch S3 are closed, so as to obtain the seventh voltage value V7 and the eighth voltage value V8; The seventh voltage value V7 is the voltage value of the output end of the voltage bias circuit collected by the diagnostic circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened, and the second switch S2 and the third switch S3 are closed; The eighth voltage value V8 is the voltage value of the output end of the unit gain differential circuit collected by the diagnostic circuit ADC when the first switch S1 and the fourth switch S4 in the current sampling resistor fault diagnosis device are opened, and the second switch S2 and the third switch S3 are closed; Based on the K value, the seventh voltage value V7, the eighth voltage value V8, the bias voltage V0 of the voltage bias circuit, and the resistance value of the resistor RF, the resistance value of the diagnostic resistor R1 is obtained using formula (4); The formula (4) is: Wherein, V8 is the eighth voltage value; V7 is the seventh voltage value; RF is the resistance value of resistor RF.

10. The method according to claim 9, characterized in that The A3 also includes: Based on the K value and the resistance value of the diagnostic resistor R1, the resistance value of the sampling resistor R2 is obtained using formula (5); The formula (5) is:

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