Resistance-string-based precision compensation insulation detection circuit

Abstract

The invention relates to the technical field of insulation resistor fault detection, and provides a resistor string-based precision compensation insulation detection circuit, which is characterized in that a relay input end of a relay control circuit is respectively and externally connected with a direct current voltage positive end, a direct current voltage negative end and the ground, and an output end of a relay is respectively connected with an input end of a voltage division and precision compensation circuit; the input end of the voltage division and precision compensation circuit is connected with the output end of the relay control circuit, and the output end is connected with the input end of the active differential amplification filter circuit; the input end of the active differential amplification filter circuit is connected with the output end of the voltage division and precision compensation circuit, and the output end of the active differential amplification filter circuit is connected with the input end of the DSP internal sampling circuit; parts of resistors in the voltage division and precision compensation circuit adopt the same resistance value model, and parts of resistors are the same and adopt the minimum insulation resistance which is 10-20 times that required by the system. The problems that traditional insulation detection precision is low, bilateral insulation faults need to be detected at the same time, and insulation detection conflicts occur under cooperative work of multiple systems can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of insulation resistance fault detection technology, and in particular to a precision compensation insulation detection circuit based on a resistor series. Background Technology

[0002] The insulation detection circuit is a general solution for protecting energy storage devices based on the field of energy storage technology. It can be widely used in electrical equipment such as battery systems, photovoltaic inverters and energy storage converters to protect the electrical safety of energy storage devices and avoid personal injury caused by insulation failure. However, traditional insulation detection circuits are typically used to detect the insulation safety of the DC positive terminal to ground or the negative terminal to ground, and mostly operate in a single-system environment. Traditional insulation testing schemes are usually single-sided insulation testing schemes, which do not consider double-sided insulation faults where both the positive and negative terminals of the DC side are simultaneously grounded. Furthermore, in the case of multi-system collaborative operation, they cannot solve the problem of conflicts between the insulation testing circuit of this system and the insulation testing circuit of other systems. Summary of the Invention

[0003] The purpose of this invention is to solve at least one technical problem in the background art and to provide a precision compensation insulation detection circuit based on a resistor series.

[0004] To achieve the above objectives, the present invention provides a precision compensation insulation detection circuit based on a resistor series connection, comprising: Relay control circuit, voltage divider and accuracy compensation circuit, and active differential amplifier and filter circuit; The relay input terminals of the relay control circuit are connected to the positive and negative terminals of a DC voltage and ground, respectively, and the relay output terminals are connected to the input terminals of the voltage divider and accuracy compensation circuit. The input terminal of the voltage divider and precision compensation circuit is connected to the output terminal of the relay control circuit, and the output terminal is connected to the input terminal of the active differential amplifier and filter circuit. The input terminal of the active differential amplifier and filter circuit is connected to the output terminal of the voltage divider and precision compensation circuit, and the output terminal of the active differential amplifier and filter circuit is connected to the input terminal of the internal sampling circuit of the DSP. Some resistors in the voltage divider and accuracy compensation circuit have the same resistance value, and some resistors are identical and have an insulation resistance that is 10 to 20 times the minimum insulation resistance required by the system.

[0005] According to one aspect of the present invention, the relay control circuit includes a relay KM1 and its control circuit, a relay KM2 and its control circuit, and a relay KM3 and its control circuit.

[0006] According to one aspect of the invention, the voltage divider and accuracy compensation circuit includes resistors R+, Re1, Re2, R-, Ru, and Rd connected in alternating series and parallel connections. The two ends of the resistor Ru are respectively connected to the output terminal of the relay KM1 and the output terminal of the relay KM2; The two ends of the resistor Rd are respectively the output terminals of relay KM2 and relay KM3; One end of the resistor R+ is connected to the output terminal of the relay KM1; One end of the resistor R- is connected to the output terminal of the relay KM3; One end of resistor Re1 and one end of resistor Re2 are connected to the output terminal of relay KM2.

[0007] According to one aspect of the invention, the resistors R+, Re1, Re2, and R- are of the same resistance value type; The resistor Ru and the resistor Rd are the same and use 10 to 20 times the minimum insulation resistance required by the system.

[0008] According to one aspect of the present invention, the active differential amplifier filter circuit includes: a first differential amplifier filter circuit and a second differential amplifier filter circuit; The input terminals of the first differential amplifier and filter circuit are respectively connected to the other end of the resistor R+ and the other end of the resistor Re1; The input terminals of the second differential amplifier and filter circuit are respectively connected to the other end of the resistor R- and the other end of the resistor Re2.

[0009] According to the solution of the present invention, the present invention can solve the problems of low accuracy of traditional insulation detection, the need for simultaneous detection of bilateral insulation faults, and insulation detection conflicts under the collaborative operation of multiple systems.

[0010] This invention utilizes a voltage divider and precision compensation circuit and an active differential amplifier and filter circuit to achieve precise resistance compensation for insulation faults; it achieves detection of bilateral insulation resistance through multiple opening and closing of the relay control circuit; it reduces the influence of the precision compensation resistor on other insulation detection systems by adjusting the resistance value range of the precision compensation resistor in hardware, and further reduces the influence of the precision compensation resistor by optimizing the opening and closing sequence of multiple system relays, thus solving the insulation detection conflict problem under multi-system collaborative operation.

[0011] The precision compensation insulation detection circuit based on the resistor series provided by this invention can effectively detect single / double-sided insulation faults at the input end within a wide voltage range of the system operating voltage. It realizes high-precision single-sided or double-sided insulation fault detection, optimizes the relay operating position and the resistance value of the precision compensation resistor, and solves the problem of the insulation detection circuit of this system conflicting with the insulation detection circuit of other systems under the collaborative operation of multiple systems, effectively avoiding system damage caused by insulation faults. Attached Figure Description

[0012] Figure 1 The diagram illustrates the circuit structure of a precision compensation insulation detection circuit based on a series resistor according to an embodiment of the present invention. Detailed Implementation

[0013] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0014] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0015] Figure 1 This schematic diagram illustrates the circuit structure of a precision compensation insulation detection circuit based on a resistor-string type according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the precision compensation insulation detection circuit based on the resistor series method includes: Relay control circuit 1, voltage divider and accuracy compensation circuit 2, and active differential amplifier and filter circuit 3; The relay input terminals of the relay control circuit 1 are respectively connected to the positive terminal V_Bat+ (positive terminal of the battery), the negative terminal V_Bat- (negative terminal of the battery), and the ground EARTH. The output terminals of the relay are respectively connected to the input terminals of the voltage divider and accuracy compensation circuit 2. The input terminal of the voltage divider and precision compensation circuit 2 is connected to the output terminal of the relay control circuit 1, and the output terminal is connected to the input terminal of the active differential amplifier and filter circuit 3. The input terminal of the active differential amplifier filter circuit 3 is connected to the output terminal 2 of the voltage divider and precision compensation circuit, and the output terminal of the active differential amplifier filter circuit 3 is connected to the input terminal of the internal sampling circuit of the DSP. In voltage divider and accuracy compensation circuit 2, some resistors use the same resistance value, and some resistors are identical and use 10 to 20 times the minimum insulation resistance required by the system.

[0016] In this embodiment, the location of the relay simplifies the calculation of the insulation resistance of a single system and improves the insulation conflict in the coordinated operation of multiple systems. In voltage divider and precision compensation circuit 2, some resistors use the same resistance value, and some resistors are the same and use 10 to 20 times the minimum insulation resistance required by the system (maximum system voltage / maximum system leakage current), which reduces the impact of precision compensation resistors on other insulation detection systems and further improves insulation conflict when multiple systems work together. The input terminal of the active differential amplifier filter circuit 3 is connected to the output terminal 2 of the voltage divider and precision compensation circuit. The output terminal of the active differential amplifier filter circuit 3 is connected to the input terminal of the internal sampling circuit of the DSP. Differential amplification reduces the interference of common-mode signals on the system, and the filter circuit weakens the ripple of the sampled signal, further enhancing the anti-interference capability of the signal.

[0017] Furthermore, such as Figure 1 As shown, in this embodiment, the relay control circuit 1 includes a relay KM1 and its control circuit, a relay KM2 and its control circuit, and a relay KM3 and its control circuit.

[0018] Furthermore, such as Figure 1 As shown, in this embodiment, the voltage divider and accuracy compensation circuit 2 includes resistors R+, Re1, Re2, R-, Ru and Rd connected in alternating series and parallel connections. The two ends of resistor Ru are connected to the output terminals of relay KM1 and relay KM2, respectively; The two ends of resistor Rd are the output terminals of relay KM2 and relay KM3, respectively; One end of resistor R+ is connected to the output terminal of relay KM1; One end of resistor R- is connected to the output terminal of relay KM3; One end of resistors Re1 and Re2 is connected to the output terminal of relay KM2.

[0019] Furthermore, such as Figure 1 As shown, in this embodiment, resistors R+, Re1, Re2 and R- use the same resistance value. The resistor Ru is the same as the resistor Rd and uses 10 to 20 times the minimum insulation resistance required by the system (maximum system voltage / maximum system leakage current). This setting can reduce the impact of the accuracy compensation resistor on other insulation detection systems and further improve insulation conflicts when multiple systems work together.

[0020] Furthermore, such as Figure 1 As shown, in this embodiment, the active differential amplifier filter circuit 3 includes: a first differential amplifier filter circuit and a second differential amplifier filter circuit. The input terminals of the first differential amplifier and filter circuit are connected to the other end of resistor R+ and the other end of resistor Re1, respectively. The input terminals of the second differential amplifier and filter circuit are connected to the other ends of resistor R- and resistor Re2, respectively.

[0021] According to the above-described solution of the present invention, the present invention can solve the problems of low accuracy of traditional insulation detection, the need for simultaneous detection of bilateral insulation faults, and insulation detection conflicts under the collaborative operation of multiple systems.

[0022] This invention utilizes a voltage divider and precision compensation circuit and an active differential amplifier and filter circuit to achieve precise resistance compensation for insulation faults; it achieves detection of bilateral insulation resistance through multiple opening and closing of the relay control circuit; it reduces the influence of the precision compensation resistor on other insulation detection systems by adjusting the resistance value range of the precision compensation resistor in hardware, and further reduces the influence of the precision compensation resistor by optimizing the opening and closing sequence of multiple system relays, thus solving the insulation detection conflict problem under multi-system collaborative operation.

[0023] The precision compensation insulation detection circuit based on the resistor series provided by this invention can effectively detect single / double-sided insulation faults at the input end within a wide voltage range of the system operating voltage. It realizes high-precision single-sided or double-sided insulation fault detection, optimizes the relay operating position and the resistance value of the precision compensation resistor, and solves the problem of the insulation detection circuit of this system conflicting with the insulation detection circuit of other systems under the collaborative operation of multiple systems, effectively avoiding system damage caused by insulation faults.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely one preferred embodiment of the invention and are only used to explain the invention. They do not limit the scope of protection of the invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] Example 1 This embodiment provides a method for calculating insulation impedance based on the above-mentioned precision compensation insulation detection circuit based on the resistor series, specifically including: Step 1: Control relays KM1, KM2, and KM3 to all engage; The values ​​of IS_AD1 and IS_AD2 at the output terminals of the active differential amplifier filter circuit 3 are measured, and the voltage Z across the battery is calculated from the circuit amplification factor. Step 2: Disconnect relay KM3 based on step 1; The output value IS_AD1 is measured, and the positive half bus voltage X1 is calculated from the circuit amplification factor. Then, the negative half bus voltage X2 is obtained from X2=Z-X1. Step 3: Based on Step 2, disconnect relay KM1 and engage relay KM3; The output value IS_AD2 is measured, the negative half bus voltage Y1 is calculated from the circuit amplification factor, and the positive half bus voltage Y2 is obtained from Y2=Z-Y1. Step 4: Based on Step 3, disconnect relays KM2 and KM3; Based on the results of steps 2 and 3 and Kirchhoff's laws, a system of two linear equations can be constructed to calculate the insulation resistance values ​​of V_Bat+ to EARTH and EARTH to V_Bat-.

[0026] The above description is merely a preferred embodiment of the present invention. Although adjusting the resistance range of the precision compensation resistor weakens its influence on other insulation detection systems from a hardware perspective, further weakening of the precision compensation resistor's influence can be achieved by optimizing the switching sequence of multi-system relays and the final operating state of the relays, thus resolving the insulation detection conflict problem under multi-system collaborative operation. It should be noted that those skilled in the art can make various improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0027] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0028] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A precision compensation insulation detection circuit based on resistor series, characterized in that, include: Relay control circuit, voltage divider and accuracy compensation circuit, and active differential amplifier and filter circuit; The relay input terminals of the relay control circuit are connected to the positive and negative terminals of a DC voltage and ground, respectively, and the relay output terminals are connected to the input terminals of the voltage divider and accuracy compensation circuit. The input terminal of the voltage divider and precision compensation circuit is connected to the output terminal of the relay control circuit, and the output terminal is connected to the input terminal of the active differential amplifier and filter circuit. The input terminal of the active differential amplifier and filter circuit is connected to the output terminal of the voltage divider and precision compensation circuit, and the output terminal of the active differential amplifier and filter circuit is connected to the input terminal of the internal sampling circuit of the DSP. Some resistors in the voltage divider and accuracy compensation circuit have the same resistance value, and some resistors are identical and have an insulation resistance that is 10 to 20 times the minimum insulation resistance required by the system.

2. The precision compensation insulation detection circuit based on resistor series as described in claim 1, characterized in that, The relay control circuit includes relay KM1 and its control circuit, relay KM2 and its control circuit, and relay KM3 and its control circuit.

3. The precision compensation insulation detection circuit based on resistor series as described in claim 2, characterized in that, The voltage divider and accuracy compensation circuit includes resistors R+, Re1, Re2, R-, Ru, and Rd connected in alternating series and parallel connections. The two ends of the resistor Ru are respectively connected to the output terminal of the relay KM1 and the output terminal of the relay KM2; The two ends of the resistor Rd are respectively the output terminals of relay KM2 and relay KM3; One end of the resistor R+ is connected to the output terminal of the relay KM1; One end of the resistor R- is connected to the output terminal of the relay KM3; One end of resistor Re1 and one end of resistor Re2 are connected to the output terminal of relay KM2.

4. The precision compensation insulation detection circuit based on resistor series as described in claim 3, characterized in that, The resistors R+, Re1, Re2, and R- are of the same resistance value type; The resistor Ru and the resistor Rd are the same and use 10 to 20 times the minimum insulation resistance required by the system.

5. The precision compensation insulation detection circuit based on resistor series as described in claim 4, characterized in that, The active differential amplifier and filter circuit includes: a first differential amplifier and filter circuit and a second differential amplifier and filter circuit; The input terminals of the first differential amplifier and filter circuit are respectively connected to the other end of the resistor R+ and the other end of the resistor Re1; The input terminals of the second differential amplifier and filter circuit are respectively connected to the other end of the resistor R- and the other end of the resistor Re2.

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