System and method for bus insulation monitoring and voltage detection

Abstract

The present application relates to the field of vehicles, and more particularly, to a system and method for bus insulation monitoring and voltage detection for a vehicle. The system comprises a bus positive voltage detection circuit and a bus negative voltage detection circuit, each of which comprises an isolation resistor and a sensing resistor; and a processing module communicatively coupled to a controller of the vehicle. The processing module is configured to obtain a first voltage detected by the bus positive voltage detection circuit and a second voltage detected by the bus negative voltage detection circuit; calculating the ratio of the first voltage to the second voltage; sending an insulation fault alert to the controller in response to a difference between the ratio and 1 exceeding a threshold; calculating a bus voltage according to the first voltage and the second voltage based on the resistance values of the isolation resistor and the sensing resistor; and transmitting the calculated bus voltage to the controller.

Description

Technical Field

[0001] The present application relates to the field of vehicles, and more particularly, to a system and method for busbar insulation monitoring and voltage detection of a vehicle. Background Art

[0002] In new energy vehicles, the high-voltage system has the characteristics of high voltage and high current, and is isolated from the vehicle's low-voltage electrical system. When a fault occurs in the vehicle's high-voltage system, the insulation performance of the high-voltage bus to the ground may be reduced, resulting in the formation of a conductive loop, and in severe cases, even causing a fire. Therefore, it is necessary to monitor the insulation performance of the vehicle's bus in real time so that these insulation faults can be discovered at the first time. At the same time, the vehicle's controller also needs to detect the voltage of the bus in real time for energy management of the vehicle. Typically, an insulation monitoring device (IMD) is used to implement insulation monitoring of the bus, and a voltage sampling circuit is used to perform real-time voltage detection on the bus.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0004] In order to solve or at least alleviate one or more of the above problems, the following technical solutions are provided. An embodiment of the present application provides a system for busbar insulation monitoring and voltage detection, which can simultaneously implement the functions of busbar insulation monitoring and voltage detection with high real-time performance and accuracy through simple devices and circuits.

[0005] According to a first aspect of the present application, a system for busbar insulation monitoring and voltage detection is provided, the system comprising a busbar positive voltage detection circuit and a busbar negative voltage detection circuit, each comprising an isolation resistor and a sensing resistor; and a processing module communicatively coupled to a vehicle controller. The processing module is configured to: obtain a first voltage detected by the busbar positive voltage detection circuit and a second voltage detected by the busbar negative voltage detection circuit; calculate a ratio of the first voltage to the second voltage; transmit an insulation fault alarm to the controller in response to a difference between the ratio and 1 exceeding a threshold; calculate a busbar voltage from the first and second voltages based on the resistance values ​​of the isolation resistor and the sensing resistor; and transmit the calculated busbar voltage to the controller.

[0006] As an alternative or supplement to the above solution, in a system according to an embodiment of the present application, the bus positive voltage detection circuit and the bus negative voltage detection circuit further include a filter circuit and a voltage follower circuit.

[0007] As an alternative or supplement to the above solution, in a system according to an embodiment of the present application, the controller calculates the battery power of the vehicle based on the bus voltage.

[0008] As an alternative or supplement to the above solution, in a system according to an embodiment of the present application, the resistance of the isolation resistor is not less than 2 MΩ, and the resistance of the sensing resistor is not higher than 1% of the resistance of the isolation resistor.

[0009] As an alternative or supplement to the above solution, in a system according to an embodiment of the present application, the isolation resistor is composed of multiple resistors, and the sum of the resistance values ​​of the multiple resistors is not less than 2 MΩ.

[0010] As an alternative or supplement to the above solution, in a system according to an embodiment of the present application, the insulation fault alarm includes a positive pole insulation fault alarm and a negative pole insulation fault alarm.

[0011] As an alternative or supplement to the above scheme, in a system according to an embodiment of the present application, the processing module is configured to: in response to the difference between the ratio and 1 exceeding a threshold value and the ratio being less than 1, send a positive pole insulation fault alarm to the controller; in response to the difference between the ratio and 1 exceeding a threshold value and the ratio being greater than 1, send a negative pole insulation fault alarm to the controller.

[0012] According to a second aspect of the present application, a method for bus insulation monitoring and voltage detection is provided, the method comprising: detecting a first voltage by a bus positive voltage detection circuit, and detecting a second voltage by a bus negative voltage detection circuit, the bus positive voltage detection circuit and the bus negative voltage detection circuit each including an isolation resistor and a sensing resistor; calculating a ratio of the first voltage to the second voltage; sending an insulation fault alarm to a controller of a vehicle in response to a difference between the ratio and 1 exceeding a threshold; calculating the bus voltage according to the first voltage and the second voltage based on the resistance values ​​of the isolation resistor and the sensing resistor; and sending the calculated bus voltage to the controller.

[0013] As an alternative or supplement to the above solution, in a method according to an embodiment of the present application, the insulation fault alarm includes a positive pole insulation fault alarm and a negative pole insulation fault alarm.

[0014] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present application, in response to the difference between the ratio and 1 exceeding a threshold value and the ratio being less than 1, a positive pole insulation fault alarm is sent to the controller; in response to the difference between the ratio and 1 exceeding a threshold value and the ratio being greater than 1, a negative pole insulation fault alarm is sent to the controller.

[0015] The system according to one or more embodiments of the present application can simultaneously implement busbar insulation monitoring and voltage detection functions with high accuracy and real-time performance. Therefore, the number of functional modules used can be reduced, thereby saving circuit board size and reducing design costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or other aspects and advantages of the present application will become clearer and easier to understand through the following description of various aspects in conjunction with the accompanying drawings, in which the same or similar elements are represented by the same reference numerals. In the drawings:

[0017] Figure 1 is a schematic diagram of a system 10 for busbar insulation monitoring and voltage detection according to an embodiment of the present application;

[0018] Figure 2 is a flow chart of a method 20 for busbar insulation monitoring and voltage detection according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] The description of the following specific embodiments is merely exemplary in nature and is not intended to limit the disclosed technology or the application and use of the disclosed technology. In addition, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background technology or the following specific embodiments.

[0020] In the following detailed description of the embodiments, numerous specific details are set forth to provide a more thorough understanding of the disclosed technology. However, it will be apparent to one of ordinary skill in the art that the disclosed technology can be practiced without these specific details. In other instances, well-known features are not described in detail to avoid unnecessarily complicating the description.

[0021] Terms such as "having" and "including" indicate that in addition to the units (modules) and steps that are directly and clearly stated in the specification and claims, the technical solution of this application does not exclude the situation where it has other units (modules) and steps that are not directly or clearly stated. Terms such as "first" and "second" do not indicate the order of units in terms of time, space, size, etc., but are only used to distinguish between the units. Moreover, the steps in this article are not limited to being implemented in the order written, but the steps written later can also be implemented at the same time as the steps written earlier, or before the steps written earlier.

[0022] At present, in new energy vehicles, high-voltage bus insulation monitoring and bus voltage detection are respectively implemented through the insulation monitoring circuit and the voltage sampling circuit. Among them, bus insulation monitoring is usually completed by the signal injection method or the bridge method. However, the bridge method requires switching switches to change the incorporated resistor, which may affect the real-time and accuracy of the measurement. At the same time, in the signal injection method, the measurement of the response signal is easily interfered by internal and external noise, and there is also a real-time problem due to the cycle of signal injection and detection. In addition, bus voltage detection is usually completed by a voltage sampling circuit for system status (for example, state of charge SOC and state of health SOH) monitoring and energy management. For the voltage sampling circuit, it usually measures the voltage through a voltage divider circuit, then passes through an isolation device, and finally inputs the measured voltage into the controller in a suitable manner and range through analog-to-digital (AD) conversion.

[0023] The present application is described in further detail below with reference to the accompanying drawings.

[0024] Figure 1 FIG is a schematic diagram of a system 10 for busbar insulation monitoring and voltage detection according to an embodiment of the present application. Figure 1 As shown in FIG, the system 10 includes a bus positive voltage detection circuit and a bus negative voltage detection circuit, each of which includes an isolation resistor and a sensing resistor. The positive electrode of the high voltage bus passes through the isolation resistor (R 隔离 +) and the sensing resistor (R 感测 +) is connected to the ground (GND), and the negative electrode of the high-voltage bus passes through the isolation resistor (R 隔离 -) and the sensing resistor (R 感测 -) is connected to ground (GND), and the sensing resistor (R 感测 +) is input to the processing module via AD conversion (not shown in the figure); similarly, the sensing resistor (R 感测 -) is input to a processing module via an A / D converter (not shown). The processing module is communicatively coupled to a vehicle controller to transmit signals and data to the controller. The processing module is configured to obtain the first and second voltages and implement busbar insulation monitoring and voltage detection functions based on the first and second voltages.

[0025] In some embodiments, the bus positive voltage detection circuit and the bus negative voltage detection circuit further each include a filter circuit and a voltage follower circuit, wherein the filter circuit is used to prevent noise signal aliasing, and the follower circuit is used to avoid load effect.

[0026] In the system 10, the isolation resistors in the bus positive voltage detection circuit and the bus negative voltage detection circuit have the same resistance value, and the resistance value of the isolation resistor is not less than 2MΩ to ensure the insulation performance of the high-voltage bus. The sensing resistors in the bus positive voltage detection circuit and the bus negative voltage detection circuit also have the same resistance value, and the resistance value of the sensing resistor is not higher than one percent of the resistance value of the isolation resistor to ensure that the measured first voltage and second voltage are within the input voltage range suitable for the processing module and the AD converter (for example, 0 to 5V). The isolation resistor and the sensing resistor are both precision resistors (for example, with an error within ±0.1%). In some embodiments, each isolation resistor can be composed of multiple resistors, and the sum of the resistance values ​​of the multiple resistors is not less than 2MΩ, thereby reducing the use of expensive high-resistance precision resistors by using multiple low-resistance resistors in series.

[0027] Next, the process of implementing busbar insulation monitoring is first described.

[0028] When the busbar insulation is normal, the vehicle's positive busbar voltage and negative busbar voltage are symmetrical about GND. For example, when fully charged, for a vehicle with an 800V busbar voltage (e.g., a vehicle using an 800V high-voltage platform), the positive busbar voltage is 400V and the negative busbar voltage is -400V. Because the isolation resistors and the sensing resistors have the same resistance value, the ratio of the first voltage to the second voltage is close to 1.

[0029] When an insulation fault occurs at the positive or negative busbar, the positive and negative busbar voltages are no longer symmetrical about GND, and the ratio of the first voltage to the second voltage deviates from 1. Specifically, busbar insulation faults may include both positive and negative busbar insulation faults. When an insulation fault occurs at the positive busbar, the positive busbar voltage decreases (e.g., from 400V to 300V), causing the voltage from the positive busbar to GND to decrease, and the first voltage also decreases proportionally. Correspondingly, the negative busbar voltage decreases (e.g., from -400V to -500V), causing the voltage from GND to the negative busbar to increase, and the second voltage also increases proportionally. The decrease in the first voltage and the increase in the second voltage cause the ratio of the first voltage to the second voltage, which was originally approximately 1, to become smaller (less than 1 and exceeding a threshold range). The processing module of the system 10 can therefore determine that a positive electrode insulation fault has occurred based on the difference between the ratio of the first voltage to the second voltage and 1 exceeding a threshold and the ratio being less than 1. The processing module can then send a positive insulation fault alert to the vehicle's controller. When an insulation fault occurs at the negative busbar, the negative busbar voltage increases (e.g., from -400V to -300V), causing the voltage from GND to the negative busbar to decrease, with the second voltage also decreasing proportionally. Correspondingly, the positive busbar voltage increases (e.g., from 400V to 500V), causing the voltage from the positive busbar to GND to increase, with the first voltage also increasing proportionally. At this point, the increase in the first voltage and the decrease in the second voltage cause the ratio of the first voltage to the second voltage, which is approximately 1 on the primary side, to become larger (greater than 1 and exceeding a threshold range). The processing module of system 10 can therefore determine that a negative insulation fault has occurred based on the fact that the difference between the ratio of the first voltage to the second voltage and 1 exceeds a threshold and that the ratio is greater than 1. The processing module can then send a negative insulation fault alert to the vehicle's controller.

[0030] In this manner, the processing module does not need to separately calculate the resistance of the busbar's positive and negative poles to GND. Instead, it identifies insulation faults by monitoring changes in the ratio of the first voltage to the second voltage, thereby reducing computing resource consumption and providing a faster response. In some embodiments, the system 10 can cooperate with other monitoring systems (e.g., an overcurrent monitoring system, an overvoltage monitoring system) to provide monitoring for more types of faults (e.g., simultaneous insulation faults of the busbar's positive and negative poles to ground).

[0031] Then, based on this, bus voltage detection can also be realized.

[0032] As mentioned above, the isolation resistors in the bus positive voltage detection circuit and the bus negative voltage detection circuit have the same resistance value, and the resistance value of the sensing resistors therein are also the same. Therefore, in the absence of an insulation fault, the first voltage is equal to the second voltage. The processing module of the system 10 can calculate the bus positive voltage and the bus negative voltage based on the resistance value of the isolation resistor and the resistance value of the sensing resistor. Since the first voltage and the second voltage are the voltages across the two sensing resistors respectively, the bus voltage is the voltage across the entire bus voltage detection circuit. Therefore, the bus voltage (V bus ) to the sum of the first voltage and the second voltage (V1+V2) and the sum of the sensing resistance and the isolation resistance (R 感测 +R 隔离 ) and the sensing resistor (R 感测 The bus voltage can be calculated using the following formula:

[0033]

[0034] For example, in an embodiment where the resistance of the isolation resistor is 2MΩ and the resistance of the sensing resistor is 20kΩ, when the first voltage and the second voltage obtained by the processing module are both 3V, based on the resistance of the isolation resistor and the sensing resistor, the processing module of the system 10 can calculate the bus voltage according to the first voltage and the second voltage using formula (1). In this case, the calculated bus voltage is 606V. The processing module can send the calculated bus voltage to the vehicle controller, and then, based on the bus voltage, the controller can determine the current SOC of the vehicle in combination with the vehicle's open circuit voltage-state of charge (OCV-SOC) curve, thereby inferring the remaining battery power.

[0035] Since the busbar insulation monitoring by the system 10 is carried out continuously (at a certain period, depending on the setting of the processing module), the busbar voltage detection by the above method is also carried out continuously. The controller can continuously obtain the busbar voltage from the processing module of the system 10 to use it for the energy management of the vehicle. Therefore, the system 10 for busbar insulation monitoring and voltage detection according to one or more embodiments of the present application is able to realize the functions of busbar insulation monitoring and voltage detection, thereby saving the number of required functional modules and thus reducing the required circuit board size and hardware cost. Furthermore, since both the isolation resistor and the sensing resistor are precision resistors, the real-time performance of the insulation monitoring and the accuracy of the voltage detection can be guaranteed at the same time.

[0036] refer to Figure 2 , Figure 2This is a flow chart of a method 20 for busbar insulation monitoring and voltage detection according to an embodiment of the present application. The method includes: detecting a first voltage using a busbar positive voltage detection circuit and detecting a second voltage using a busbar negative voltage detection circuit, each of which includes an isolation resistor and a sensing resistor; calculating a ratio of the first voltage to the second voltage; transmitting an insulation fault alarm to a vehicle controller in response to a difference between the ratio and 1 exceeding a threshold; calculating a busbar positive voltage and a busbar negative voltage from the first and second voltages based on the resistances of the isolation resistor and the sensing resistor; and transmitting the calculated busbar positive voltage and busbar negative voltage to the controller. The method 20 determines whether to issue a busbar insulation fault alarm based on the difference between the ratio of the first voltage to the second voltage and 1, thereby implementing busbar insulation monitoring. The method 20 infers the busbar voltage from the first and second voltages, thereby implementing busbar voltage detection. By performing corresponding calculations on the first and second voltages, the method 20 can implement multiple functions using a single module.

[0037] In some embodiments, the insulation fault alarm includes a positive pole insulation fault alarm and a negative pole insulation fault alarm, and wherein, in response to the difference between the ratio and 1 exceeding a threshold value, sending the insulation fault alarm to the controller of the vehicle includes: in response to the difference between the ratio and 1 exceeding the threshold value, and the ratio is less than 1, sending the positive pole insulation fault alarm to the controller; in response to the difference between the ratio and 1 exceeding the threshold value, and the ratio is greater than 1, sending the negative pole insulation fault alarm to the controller.

[0038] Software according to the present application (such as program code and / or data) can be stored on one or more computer storage media. It is also contemplated that the software identified herein can be implemented using one or more general or special computers and / or computer systems, networked and / or otherwise. Where applicable, the order of the various steps described herein can be changed, combined into composite steps and / or divided into sub-steps to provide the features described herein.

[0039] The embodiments and examples set forth herein are provided to best illustrate embodiments according to the present application and its specific applications, and thereby enable those skilled in the art to make and use the present application. However, those skilled in the art will appreciate that the above description and examples are provided for ease of illustration and example only. The descriptions set forth are not intended to be exhaustive of all aspects of the present application or to limit the present application to the precise forms disclosed.

Claims

1. A system for busbar insulation monitoring and voltage detection, the system comprising: A bus positive voltage detection circuit and a bus negative voltage detection circuit, each of the bus positive voltage detection circuit and the bus negative voltage detection circuit comprising an isolation resistor and a sensing resistor; as well as a processing module communicatively coupled to a controller of the vehicle, and configured to: Acquire a first voltage detected by the bus positive voltage detection circuit and a second voltage detected by the bus negative voltage detection circuit; calculating a ratio of the first voltage to the second voltage; In response to a difference between the ratio and 1 exceeding a threshold, sending an insulation fault alarm to the controller; Calculating a bus voltage according to the first voltage and the second voltage based on the resistance values ​​of the isolation resistor and the sensing resistor; as well as The calculated bus voltage is sent to the controller.

2. The system of claim 1, wherein: The bus positive voltage detection circuit and the bus negative voltage detection circuit further include a filter circuit and a voltage follower circuit.

3. The system of claim 1, wherein: The controller calculates a battery charge of the vehicle based on the bus voltage.

4. The system of claim 1, wherein: The resistance of the isolation resistor is not less than 2 MΩ, and the resistance of the sensing resistor is not greater than 1% of the resistance of the isolation resistor.

5. The system of claim 4, wherein: The isolation resistor is composed of a plurality of resistors, and the sum of the resistance values ​​of the plurality of resistors is not less than 2 MΩ.

6. The system of claim 1, wherein: The insulation fault alarm includes a positive pole insulation fault alarm and a negative pole insulation fault alarm.

7. The system of claim 6, wherein the processing module is configured to: In response to a difference between the ratio and 1 exceeding a threshold value and the ratio being less than 1, sending a positive insulation fault alarm to the controller; In response to a difference between the ratio and 1 exceeding a threshold, and the ratio being greater than 1, a negative insulation fault alarm is sent to the controller.

8. A method for busbar insulation monitoring and voltage detection, the method comprising: detecting a first voltage by a bus positive voltage detection circuit and detecting a second voltage by a bus negative voltage detection circuit, wherein the bus positive voltage detection circuit and the bus negative voltage detection circuit each include an isolation resistor and a sensing resistor; calculating a ratio of the first voltage to the second voltage; In response to a difference between the ratio and 1 exceeding a threshold, sending an insulation fault alert to a controller of the vehicle; Calculating a bus voltage according to the first voltage and the second voltage based on the resistance values ​​of the isolation resistor and the sensing resistor; as well as The calculated bus voltage is sent to the controller.

9. The method of claim 8, wherein: The insulation fault alarm includes a positive pole insulation fault alarm and a negative pole insulation fault alarm.

10. The method of claim 9, wherein: In response to the difference between the ratio and 1 exceeding a threshold value and the ratio being less than 1, a positive pole insulation fault alarm is sent to the controller; in response to the difference between the ratio and 1 exceeding a threshold value and the ratio being greater than 1, a negative pole insulation fault alarm is sent to the controller.

Images