Insulation resistance detection system

Abstract

The utility model discloses an insulation resistance detection system. The insulation resistance detection system comprises an unbalanced bridge circuit and a sampling circuit. The unbalanced bridge circuit comprises four resistors and two relays; the first end of the first resistor is connected with the positive electrode end of an object to be measured and the positive electrode end of a bus, the second end of the first resistor is connected with the first end of the second resistor, the second end of the second resistor and the first end of the third resistor are connected with a grounding protection line, and the second end of the third resistor is connected with the first end of the fourth resistor. The second end of the fourth resistor is connected with the negative electrode end of the to-be-measured object and the negative electrode end of the bus. The first relay is connected to two ends of the second resistor in parallel, the second relay is connected to two ends of the fourth resistor in parallel, the sampling circuit is connected with a second end of the second resistor and a second end of the fourth resistor, and an output end of the sampling circuit is connected with a far-end upper computer. According to the scheme, the hardware cost for carrying out insulation impedance detection on the to-be-detected object can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to energy system detection technical field especially is related to an insulation impedance detection system. BACKGROUND

[0002] With the substantial growth of the demand for electricity in the whole society, energy storage devices are more and more applied to the power system. Energy storage devices play an important role in improving the operation safety of the power system, smoothing the distribution of power demand, and improving the power output efficiency of the power system, and become the key to support the development of renewable energy.

[0003] In order to ensure the stable operation of the energy storage device, the insulation impedance of the battery cluster in the energy storage device needs to be detected. When the insulation impedance of the battery cluster is detected, the insulation impedance between the positive terminal of the battery cluster and the protective earthing conductor (PE) and the insulation impedance between the negative terminal of the battery cluster and the protective earthing conductor need to be detected by the insulation impedance detection device. The existing insulation impedance detection device adopts an unbalanced bridge unit and a sampling unit to collect the differential voltage signal between the negative terminal of the battery cluster and the protective earthing conductor, and sends the differential voltage signal to the remote host computer, so that the host computer determines the above two kinds of insulation impedance of the battery cluster through the differential voltage signal.

[0004] At present, the unbalanced bridge unit of the existing insulation impedance detection device is connected in series with the positive terminal resistor and the positive terminal relay between the positive terminal of the battery cluster and the protective earthing conductor, and is connected in series with the negative terminal resistor and the negative terminal relay between the negative terminal of the battery cluster and the protective earthing conductor. By alternately turning on and off the positive terminal relay and the negative terminal relay, the sampling unit collects the differential voltage signal when the positive terminal relay is turned on and the negative terminal relay is turned off, and the differential voltage signal when the positive terminal relay is turned off and the negative terminal relay is turned on from the unbalanced bridge unit, and then sends the above two kinds of differential voltage signals to the host computer, so as to complete the detection of the insulation impedance of the battery cluster.

[0005] However, when the positive terminal relay and the negative terminal relay are turned on or turned off, a large transient voltage will appear in the unbalanced bridge unit, which will cause the relay to be subjected to strong switching stress, and the insulation impedance detection device must use a relay with strong voltage resistance. The price of the relay with strong voltage resistance is generally higher, resulting in high hardware cost for insulation impedance detection of the battery cluster. UTILITY MODEL CONTENTS

[0006] Therefore, the utility model provides an insulation impedance detection system, which mainly aims to solve the technical problem of high hardware cost for insulation impedance detection of the measured object.

[0007] To achieve the above object, the utility model provides a kind of insulation impedance detection system first, and the insulation impedance detection system includes unbalanced bridge circuit and sampling circuit;The unbalanced bridge circuit includes first resistance, second resistance, third resistance, fourth resistance, first relay and second relay;

[0008] The first end of the first resistance is connected with the positive terminal of the object to be measured and the positive terminal of the bus connected with the object to be measured respectively, the second end of the first resistance is connected with the first end of the second resistance, the second end of the second resistance and the first end of the third resistance are connected with the protective grounding wire respectively, the second end of the third resistance is connected with the first end of the fourth resistance, and the second end of the fourth resistance is connected with the negative terminal of the object to be measured and the negative terminal of the bus respectively.

[0009] The first relay is connected in parallel across the second resistance, and the second relay is connected in parallel across the fourth resistance, the first collection end of the sampling circuit is connected with the second end of the second resistance, the second collection end of the sampling circuit is connected with the second end of the fourth resistance, and the signal output end of the sampling circuit is connected with the upper computer at a remote end.

[0010] The resistance value of the first resistance and the third resistance is greater than 40 megaohm.

[0011] The resistance value of the second resistance and the fourth resistance is greater than 600 megaohm.

[0012] In an embodiment of the utility model, the unbalanced bridge circuit further includes a first capacitor and a second capacitor, the first end of the first capacitor is connected with the first end of the first resistance, the second end of the first capacitor is connected with the first end of the second capacitor and the neutral point of the bus respectively, and the second end of the second capacitor is connected with the second end of the fourth resistance.

[0013] In an embodiment of the utility model, the sampling circuit is a differential amplification circuit, the first input end of the differential amplification circuit is connected with the second end of the second resistance, the second input end of the differential amplification circuit is connected with the second end of the fourth resistance, and the output end of the differential amplification circuit is connected with the upper computer.

[0014] In an embodiment of the utility model, the differential amplifier circuit includes operational amplifier, first input resistance, second input resistance, feedback resistance and balance resistance, the first end of first input resistance is connected with the second end of second resistance, the second end of first input resistance is connected with the opposite phase input end of operational amplifier, the first end of second input resistance is connected with the second end of fourth resistance, the second end of second input resistance is connected with the same phase input end of operational amplifier, the output end of operational amplifier is connected with host computer, the first end of feedback resistance is connected with the opposite phase input end of operational amplifier, the second end of feedback resistance is connected with the output end of operational amplifier, the first end of balance resistance is connected with the same phase input end of operational amplifier, the second end of balance resistance is grounded.

[0015] In an embodiment of the utility model, the differential amplifier circuit further includes first high resistance input resistance and second high resistance input resistance, the first end of first high resistance input resistance is connected with the second end of second resistance, the second end of first high resistance input resistance is connected with the first end of first input resistance, the first end of second high resistance input resistance is connected with the second end of fourth resistance, the second end of second high resistance input resistance is connected with the first end of second input resistance.

[0016] In an embodiment of the utility model, the first resistance, the second resistance, the third resistance, the fourth resistance, the first input resistance, the second input resistance, the first high resistance input resistance, the second high resistance input resistance, the feedback resistance and the balance resistance are variable resistance respectively.

[0017] In an embodiment of the utility model, the resistance value of first high resistance input resistance and second high resistance input resistance is greater than 81.6 megaohm.

[0018] In an embodiment of the utility model, the insulation impedance detection system further includes detection controller, the signal receiving end of detection controller is connected with the signal output end of sampling circuit.

[0019] In an embodiment of the utility model, the first end of the first relay contact of the first relay is connected with the first end of the second resistance, the second end of the first relay contact is connected with the second end of the second resistance, the first end of the second relay contact of the second relay is connected with the first end of the fourth resistance, the second end of the second relay contact is connected with the second end of the fourth resistance, the first signal output end of the detection controller is connected with the first relay coil of the first relay, the second signal output end of the detection controller is connected with the second relay coil of the second relay, be used for controlling the first relay and the second relay are in the on or off state.

[0020] In an embodiment of the utility model, the insulation impedance detection system further includes an alarm device, the control end of the detection controller is connected with the control end of the alarm device, and the alarm device is used for sending sound and light alarm information.

[0021] In an embodiment of the utility model, the insulation impedance detection system further includes a voltage sensor, the voltage sensor is arranged at the bus, and is used for collecting the bus voltage of the bus, the voltage sampling end of the detection controller is connected with the signal output end of the voltage sensor, and the bus voltage is obtained from the voltage sensor.

[0022] The insulation impedance detection system provided by the utility model has the second resistance in parallel at the side of the first relay as the positive terminal relay, has the fourth resistance in parallel at the side of the second relay as the negative terminal relay, when the first relay and the second relay are in the on or off action, because the resistance value of the second resistance and the fourth resistance is large, the rising speed of transient voltage in the unbalanced bridge circuit can be limited to a great extent, the transient impact of transient voltage on the relay is reduced, and then the switching stress of the first relay and the second relay in the on or off action is reduced, so that the insulation impedance detection system does not need to set the relay with strong voltage resistance to complete the insulation impedance detection work of the measured object, and the hardware cost of the insulation impedance detection of the measured object is reduced.

[0023] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A structure schematic diagram of an existing insulation impedance detection device is shown;

[0026] Figure 2 A structure schematic diagram of an insulation impedance detection system provided by an embodiment of the present application is shown;

[0027] Figure 3 A structure schematic diagram of an insulation impedance detection system provided by an embodiment of the present application is shown;

[0028] Figure 4 A structure schematic diagram of an insulation impedance detection system provided by an embodiment of the present application is shown;

[0029] Figure 5 A structure schematic diagram of an insulation impedance detection system provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0030] Hereinafter, the present application will be described in detail with reference to the drawings and embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0031] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application will be described in detail below with reference to the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0032] The insulation impedance detection system provided by the present application is applicable to any battery system, such as a battery cluster in an energy storage device, a vehicle power battery system, etc. The battery cluster in an electrochemical energy storage system will be taken as an example for specific description.

[0033] At present, as shown in Figure 1 The existing insulation impedance detection device includes an unbalanced bridge unit 10 and a sampling unit 20, the differential voltage signal between the negative terminal DC- of the battery cluster in the energy storage device and the ground protection line PE is collected, and the differential voltage signal is sent to a remote host computer (not shown in the figure), so that the host computer determines the insulation impedance between the positive terminal DC+ of the battery cluster and the ground protection line PE and the insulation impedance between the negative terminal DC- of the battery cluster and the ground protection line PE through the differential voltage signal.

[0034] Here, the unbalanced bridge unit 10 of the existing insulation impedance detection device is connected in series between the positive terminal DC+ of the battery cluster and the ground protection line PE by setting the positive terminal resistor Rp and the positive terminal relay Relayp, and is connected in series between the negative terminal DC- of the battery cluster and the ground protection line PE by setting the negative terminal resistor Rn and the negative terminal relay Relayn, and the sampling unit 20 collects the differential voltage signal between the negative terminal DC- of the battery cluster and the ground protection line PE from the unbalanced bridge unit 10 by alternately turning on and off the positive terminal relay Relayp and the negative terminal relay Relayn, and then sends the differential voltage signal to the host computer, so as to complete the detection of the insulation impedance of the battery cluster.

[0035] However, when the positive terminal relay Relayp and the negative terminal relay Relayn are turned on or turned off, the relay will be impacted by strong switching stress, so that the insulation impedance detection device must use a relay with strong voltage resistance capability, and the price of the relay with strong voltage resistance capability is generally higher, resulting in higher hardware cost for detecting the insulation impedance of the battery cluster.

[0036] In view of the above problems, the following Figures 2 to 5 A kind of insulation impedance detection system according to some embodiments of the utility model is described to solve the current insulation impedance detection hardware cost higher for battery cluster The problem of.

[0037] As shown in Figure 2 An embodiment of the utility model provides an insulation impedance detection system for detecting the insulation impedance of the battery cluster (not shown in the figure) in the energy storage device, wherein the energy storage device can be an electrochemical energy storage device, and the battery cluster in the energy storage device is connected to the bus to connect the energy storage device to the power system.

[0038] Specifically, the insulation impedance detection system comprises an unbalanced bridge circuit 100 and a sampling circuit 200; wherein the unbalanced bridge circuit 100 comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first relay Relay1 and a second relay Relay2. Here, the resistance values of the first resistor R1 and the third resistor R3 can be above 40 megaohms, and the resistance values of the second resistor R2 and the fourth resistor R4 are much higher than the insulation impedance of the measured battery cluster, for example, at least 10 times the measured insulation impedance, and the resistance values of the second resistor R2 and the fourth resistor R4 can be above 600 megaohms respectively, and the resistance values of the second resistor R2 and the fourth resistor R4 can be determined according to actual conditions.

[0039] Wherein the first end of the first resistor R1 is connected with the positive terminal DC+ of the battery cluster and the positive terminal BUS+ of the bus connected with the battery cluster respectively, the second end of the first resistor R1 is connected with the first end of the second resistor R2, the second end of the second resistor R2 and the first end of the third resistor R3 are connected with the protective grounding line PE respectively, and here, the connection end after the second end of the second resistor R2 and the first end of the third resistor R3 are connected can be connected to the protective grounding line PE.

[0040] Further, the second end of the third resistor R3 is connected with the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected with the negative terminal DC- of the battery cluster and the negative terminal BUS- of the bus respectively.

[0041] Further, the first relay Relay1 is connected in parallel across the second resistor R2, and here, the first end of the first relay contact of the first relay Relay1 is connected with the first end of the second resistor R2, and the second end of the first relay contact is connected with the second end of the second resistor R2, so as to control the first relay contact of the first relay Relay1 to be turned on or turned off by controlling the signal level delivered to the relay coil of the first relay Relay1, and then to control the turn-on and turn-off of the first relay Relay1.

[0042] Further, the second relay Relay2 is connected in parallel across the fourth resistor R4, and here, the first end of the second relay contact of the second relay Relay2 is connected with the first end of the fourth resistor R4, and the second end of the second relay contact is connected with the second end of the fourth resistor R4, so as to control the second relay contact of the second relay Relay2 to be turned on or turned off by controlling the signal level delivered to the relay coil of the second relay Relay2, and then to control the turn-on and turn-off of the second relay Relay2.

[0043] Further, the first collection end of the sampling circuit 200 is connected with the second end of the second resistor R2, the second collection end of the sampling circuit 200 is connected with the second end of the fourth resistor R4, and the signal output end of the sampling circuit 200 is connected with the upper computer 300 at the far end.

[0044] In actual working process, when the first relay Relay1 is turned on, the positive end DC+ of the battery cluster and the ground protection line PE are normally turned on, when the first relay Relay1 is turned off, because the resistance value of the second resistor R2 is large, the effect of breaking the circuit is achieved, so that the positive end DC+ of the battery cluster and the ground protection line PE can be regarded as breaking the circuit; similarly, when the second relay Relay2 is turned on, the negative end DC- of the battery cluster and the ground protection line PE are normally turned on, when the second relay Relay2 is turned off, because the resistance value of the fourth resistor R4 is large, the effect of breaking the circuit is achieved, so that the negative end DC- of the battery cluster and the ground protection line PE can be regarded as breaking the circuit. Based on this, when the first relay Relay1 is turned on and the second relay Relay2 is turned off, the sampling circuit 200 can collect the differential voltage signal of the positive end, when the first relay Relay1 is turned off and the second relay Relay2 is turned on, the sampling circuit 200 can collect the differential voltage signal of the negative end; further, the sampling circuit 200 sends the above two kinds of differential voltage signals to the upper computer 300, so that the upper computer 300 can determine the insulation impedance between the positive end DC+ of the battery cluster and the ground protection line PE and the insulation impedance between the negative end DC- of the battery cluster and the ground protection line PE based on the differential voltage signal.

[0045] The insulation impedance detection system provided by the embodiment of the utility model, parallel connection of second resistor on the side of first relay as positive end relay, parallel connection of fourth resistor on the side of second relay as negative end relay, when the first relay and the second relay are turned on or turned off, because the resistance value of second resistor and fourth resistor is large, the rising speed of transient voltage in unbalanced bridge circuit can be limited to a great extent, the transient impact of transient voltage on relay is reduced, and then the switching stress of the first relay and the second relay when turned on or turned off is reduced, so that the insulation impedance detection system does not need to set the relay with strong voltage resistance to complete the insulation impedance detection work of battery cluster, and the hardware cost of insulation impedance detection of battery cluster is reduced. In addition, when the resistance value of second resistor and fourth resistor is much larger than the insulation impedance of the measured battery cluster, the circuit between the positive end of battery cluster and the ground protection line can be regarded as breaking the circuit when the first relay is turned off, and the circuit between the negative end of battery cluster and the ground protection line can be regarded as breaking the circuit when the second relay is turned off, so that the influence of second resistor and fourth resistor on detection work is prevented, and the detection precision of the insulation impedance detection system is improved.

[0046] In one embodiment, as shown in Figure 3 The unbalanced bridge circuit further comprises a first capacitor Cp and a second capacitor Cn; specifically, a first end of the first capacitor Cp is connected with a first end of the first resistor R1, a second end of the first capacitor Cp is connected with a first end of the second capacitor Cn and a neutral point BUS-N of the busbar respectively, and a second end of the second capacitor Cn is connected with a second end of the fourth resistor R4. The first capacitor Cp and the second capacitor Cn can serve as support capacitors, which can support the voltage of the DC busbar and prevent abnormal fluctuation of the voltage of the busbar. The embodiments provided in the present application can support the voltage of the DC busbar connected with the battery cluster by arranging support capacitors in the unbalanced bridge circuit. When the voltage of the DC busbar suddenly decreases, the support capacitors can quickly release the stored energy, so as to ensure that the voltage of the DC busbar does not decrease sharply, thereby maintaining the normal operation of the system and improving the operation stability of the insulation impedance detection system.

[0047] In one embodiment, as shown in Figure 4 The sampling circuit is a differential amplifier circuit 210; wherein the differential amplifier circuit 210 (Differential Amplifier Circuit) is an electronic circuit capable of amplifying the difference between two input signals, and can suppress any common-mode signal, which can effectively eliminate unwanted noise or interference.

[0048] Specifically, a first input end of the differential amplifier circuit 210 is connected with a second end of the second resistor R2, a second input end of the differential amplifier circuit 210 is connected with a second end of the fourth resistor R4, and an output end of the differential amplifier circuit 210 is connected with the host computer 300. The technical solution provided in the present application can collect the differential voltage signal through the differential amplifier circuit, which can improve the voltage signal collection accuracy of the unbalanced bridge circuit and improve the detection capability of the insulation impedance detection system.

[0049] In one embodiment, as shown in Figure 4 The differential amplifier circuit 210 comprises an operational amplifier U1, a feedback resistor Rf1, a balance resistor Rf2, a first input resistor Ri1 and a second input resistor Ri2. Here, the operational amplifier U1 is a precision operational amplifier, which can improve the sampling accuracy of the circuit.

[0050] Specifically, a first end of the first input resistor Ri1 is connected with a second end of the second resistor R2, a second end of the first input resistor Ri1 is connected with an inverting input terminal of the operational amplifier U1, a first end of the second input resistor Ri2 is connected with a second end of the fourth resistor R4, a second end of the second input resistor Ri2 is connected with a non-inverting input terminal of the operational amplifier U1, and an output terminal of the operational amplifier U1 is connected with the host computer 300.

[0051] Further, a first end of the feedback resistor Rf1 is connected with the inverting input terminal of the operational amplifier U1, a second end of the feedback resistor Rf1 is connected with the output terminal of the operational amplifier U1, and a first end of the balance resistor Rf2 is connected with the non-inverting input terminal of the operational amplifier U1, and a second end of the balance resistor Rf2 is grounded.

[0052] Here, in the differential amplification circuit 210 constructed using the operational amplifier U1, the feedback resistor Rf1, the first input resistor Ri1, and the second input resistor Ri2 jointly determine the differential mode gain of the differential amplification circuit 210, and by adjusting the proportional relationship of these resistors, different gain settings can be obtained. At the same time, the feedback resistor Rf1 helps to improve the stability of the differential amplification circuit 210, reduces nonlinear distortion, so that the operational amplifier can maintain good linear characteristics in a wider operating range, and reduces the influence of temperature changes and other parameter drifts. Further, a suitable feedback resistor Rf1 can help control the bandwidth of the circuit, ensuring stable gain within the required frequency range. Further, the balance resistor Rf2 can ensure that the differential amplification circuit 210 has good common mode rejection ratio, improving the signal acquisition quality of the differential amplification circuit 210.

[0053] The embodiments provided in the present application constitute a differential amplification circuit with an operational amplifier, a feedback resistor, a balance resistor, a first input resistor, and a second input resistor, which can set the gain of the differential amplification circuit and improve the voltage signal acquisition accuracy of the differential amplification circuit, thereby improving the signal acquisition capability of the insulation impedance detection system.

[0054] In one embodiment, as shown in Figure 5 The differential amplification circuit 210 further includes a first high-resistance input resistor R5 and a second high-resistance input resistor R6, and the resistance values of the first high-resistance input resistor R5 and the second high-resistance input resistor R6 can be greater than 81.6 megaohms, and the specific resistance values can be determined according to actual conditions.

[0055] Specifically, a first end of the first high input resistance R5 is connected with a second end of the second resistance R2, a second end of the first high input resistance R5 is connected with a first end of the first input resistance Ri1, a first end of the second high input resistance R6 is connected with a second end of the fourth resistance R4, and a second end of the second high input resistance R6 is connected with a first end of the second input resistance Ri2.

[0056] Here, the differential mode gain of the differential amplification circuit 210 can be determined by the first high input resistance R5, the second high input resistance R6, the feedback resistance Rf1, the first input resistance Ri1 and the second input resistance Ri2. By adjusting the proportional relationship of the above resistances, different gain settings can be obtained.

[0057] In the embodiments provided in the present application, the first high input resistance and the second high input resistance with large resistance values are arranged in the differential amplification circuit, so that the first high input resistance and the second high input resistance can serve as high-isolation resistances, which can significantly reduce the influence of the sampling circuit on the unbalanced bridge circuit and improve the sampling accuracy of the insulation impedance detection system.

[0058] In one embodiment, the first resistance, the second resistance, the third resistance, the fourth resistance, the first input resistance, the second input resistance, the first high input resistance, the second high input resistance, the feedback resistance and the balancing resistance are variable resistances. In actual use, the resistance values of the first resistance, the second resistance, the third resistance, the fourth resistance, the first input resistance, the second input resistance, the first high input resistance, the second high input resistance, the feedback resistance and the balancing resistance can be adjusted to set the gain of the differential amplification circuit and other operations, so that the insulation impedance detection system can adapt to different energy storage devices and improve the adaptability and operability of the insulation impedance detection system.

[0059] In one embodiment, the insulation impedance detection system further comprises a detection controller. Here, the detection controller can be a single-chip microcomputer, a digital signal processor or other computer equipment. Specifically, a signal receiving end of the detection controller is connected with a signal output end of the sampling circuit to receive the voltage signal output by the sampling circuit. The detection controller can be pre-set with relevant control programs and insulation impedance detection programs to receive various parameters output by the sampling circuit and detect the insulation impedance of the battery cluster in the energy storage device.

[0060] Further, a first signal output end of the detection controller is connected with a first relay coil of the first relay, and a second signal output end of the detection controller is connected with a second relay coil of the second relay, so as to control the first relay and the second relay to be in the on or off state by sending a high level signal or a low level signal to the first relay coil and the second relay coil.

[0061] Further, the insulation impedance detection system further comprises a voltage sensor; specifically, the voltage sensor is arranged at the busbar, and is used to collect a busbar voltage of the busbar; further, a voltage sampling end of the detection controller is connected with a signal output end of the voltage sensor, so as to obtain the busbar voltage from the voltage sensor.

[0062] In the actual detection process, first, the detection controller can detect whether the busbar voltage of the busbar to which the battery cluster of the energy storage device is connected is normal, and here, the busbar voltage of the busbar can be obtained from the voltage sensor arranged at the busbar. Further, in the case that the busbar voltage is normal, the busbar voltage is recorded for use in the subsequent calculation of the insulation impedance; on the contrary, if the busbar voltage is abnormal, the busbar voltage is confirmed again or the detection work is terminated.

[0063] Then, the detection controller can control the first relay to be on, control the second relay to be off, and obtain the differential voltage signal between the negative electrode of the battery cluster and the ground protection line in the current state from the sampling circuit.

[0064] Further, the detection controller can control the first relay to be off, control the second relay to be on, and obtain the differential voltage signal between the negative electrode of the battery cluster and the ground protection line in the current state from the sampling circuit.

[0065] Finally, the insulation impedance between the positive electrode of the battery cluster and the ground protection line and the insulation impedance between the negative electrode of the battery cluster and the ground protection line are calculated based on the differential voltage signals in the above two states, so as to realize the detection of the insulation impedance of the battery cluster.

[0066] Here, if the energy storage device is an electrochemical energy storage system, due to the coupling capacitor between the positive electrode of the battery cluster and the ground protection line and between the negative electrode of the battery cluster and the ground protection line, the port voltage cannot reach a steady state in a long time under the open circuit impedance working condition, and needs to be fitted and optimized to improve the measurement accuracy. When detecting, the characteristic parameters of the measured electrochemical energy storage system can be obtained by multiple tests, the parameter relationship of the batch of electrochemical energy storage systems is fitted, and the above parameter relationship is introduced when solving the insulation impedance to compensate for the calculation error.

[0067] The embodiment provided in the application can control the detection work of the insulation impedance by the detection controller, and improve the automation level of the insulation impedance detection work of the energy storage device.

[0068] In one embodiment, the insulation impedance detection system further comprises an alarm device, wherein the alarm device can be an audible and visual alarm device such as a flashlight or a buzzer; specifically, the control end of the detection controller is connected with the control end of the alarm device, for controlling the alarm device to send audible and visual alarm information. Here, the detection controller can send alarm prompt information in time when the insulation impedance of the energy storage device is detected to be abnormal, so as to remind the relevant staff to make corresponding treatment for the abnormal situation.

[0069] The embodiment provided in the application provides a hardware basis for the insulation impedance detection system to realize the abnormal alarm function, so that the insulation impedance detection system can alarm in time when the insulation impedance of the energy storage device is detected to be abnormal, and the functionality of the insulation impedance detection system is enriched.

[0070] It should be noted that the selection of the unbalanced bridge circuit, the sampling circuit, the detection controller and the internal circuit connection mode can be determined according to the actual situation, and the embodiment is not limited specifically, and in addition, the connection mode of each device can be determined according to the specific selection of the device, and the embodiment is not limited specifically. The function of the insulation impedance detection system provided in the embodiment is mainly realized through the circuit connection relationship between each circuit module, and does not depend on the program module in a certain circuit module. In addition, each circuit module in the insulation impedance detection system can be realized by an analog circuit or a digital circuit, and for the detection controller which can implant a program module, the realization of the module function can be realized by the program module provided by the prior art.

[0071] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the utility model patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the utility model patent should be subject to the appended claims.

Claims

1. An insulation impedance detection system characterized by, The insulation impedance detection system comprises an unbalanced bridge circuit and a sampling circuit; the unbalanced bridge circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first relay and a second relay; a first end of the first resistor is connected with a positive terminal of a to-be-tested object and a positive terminal of a bus to which the to-be-tested object is connected, a second end of the first resistor is connected with a first end of the second resistor, a second end of the second resistor and a first end of the third resistor are connected with a protective grounding wire, a second end of the third resistor is connected with a first end of the fourth resistor, and a second end of the fourth resistor is connected with a negative terminal of the to-be-tested object and a negative terminal of the bus; the first relay is connected in parallel with the second resistor, the second relay is connected in parallel with the fourth resistor, a first collection end of the sampling circuit is connected with the second end of the second resistor, a second collection end of the sampling circuit is connected with the second end of the fourth resistor, and a signal output end of the sampling circuit is connected with a host computer at a remote end; resistance values of the first resistor and the third resistor are greater than 40 megaohms; resistance values of the second resistor and the fourth resistor are greater than 600 megaohms.

2. The isolation impedance detection system of claim 1, wherein, The unbalanced bridge circuit further comprises a first capacitor and a second capacitor; a first end of the first capacitor is connected with the first end of the first resistor, a second end of the first capacitor is connected with a first end of the second capacitor and a neutral point of the bus, and a second end of the second capacitor is connected with the second end of the fourth resistor.

3. The isolation impedance detection system of claim 1, wherein, The sampling circuit is a differential amplification circuit; a first input end of the differential amplification circuit is connected with the second end of the second resistor, a second input end of the differential amplification circuit is connected with the second end of the fourth resistor, and an output end of the differential amplification circuit is connected with the host computer.

4. The isolation impedance detection system of claim 3, wherein, The differential amplification circuit comprises an operational amplifier, a first input resistor, a second input resistor, a feedback resistor and a balance resistor; a first end of the first input resistor is connected with the second end of the second resistor, a second end of the first input resistor is connected with an inverting input end of the operational amplifier, a first end of the second input resistor is connected with the second end of the fourth resistor, a second end of the second input resistor is connected with a non-inverting input end of the operational amplifier, and an output end of the operational amplifier is connected with the host computer; a first end of the feedback resistor is connected with the inverting input end of the operational amplifier, a second end of the feedback resistor is connected with the output end of the operational amplifier, a first end of the balance resistor is connected with the non-inverting input end of the operational amplifier, and a second end of the balance resistor is grounded.

5. The isolation impedance detection system of claim 4, wherein, The differential amplification circuit further comprises a first high-resistance input resistor and a second high-resistance input resistor; a first end of the first high-resistance input resistor is connected with the second end of the second resistor, a second end of the first high-resistance input resistor is connected with the first end of the first input resistor, a first end of the second high-resistance input resistor is connected with the second end of the fourth resistor, and a second end of the second high-resistance input resistor is connected with the first end of the second input resistor.

6. The isolation impedance detection system of claim 5, wherein, The first resistance, the second resistance, the third resistance, the fourth resistance, the first input resistance, the second input resistance, the first high-resistance input resistance, the second high-resistance input resistance, the feedback resistance and the balance resistance are variable resistances respectively. And / or, the resistance values of the first high-resistance input resistance and the second high-resistance input resistance are greater than 81.6 megaohms.

7. The isolation impedance detection system of claim 1, wherein, The insulation impedance detection system further comprises a detection controller, a signal receiving end of the detection controller being connected with a signal output end of the sampling circuit.

8. The isolation impedance detection system of claim 7, wherein, A first end of a first relay contact of the first relay is connected with a first end of the second resistance, a second end of the first relay contact is connected with a second end of the second resistance, a first end of a second relay contact of the second relay is connected with a first end of the fourth resistance, and a second end of the second relay contact is connected with a second end of the fourth resistance. A first signal output end of the detection controller is connected with a first relay coil of the first relay, and a second signal output end of the detection controller is connected with a second relay coil of the second relay, for controlling the first relay and the second relay to be in a conducting or non-conducting state.

9. The isolation impedance detection system of claim 7, wherein, The insulation impedance detection system further comprises an alarm device. A control end of the detection controller is connected with a control end of the alarm device, for controlling the alarm device to send out sound and light alarm information.

10. The isolation impedance detection system of claim 7, wherein, The insulation impedance detection system further comprises a voltage sensor. The voltage sensor is arranged at the bus, for collecting a bus voltage of the bus. A voltage sampling end of the detection controller is connected with a signal output end of the voltage sensor, for obtaining the bus voltage from the voltage sensor.

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