New energy automobile high-voltage bus current sampling system

Abstract

The invention discloses a new energy automobile high-voltage bus current sampling system, and belongs to the field of current sampling. The system comprises a high-voltage bus connecting bar, a voltage acquisition circuit, a temperature acquisition circuit, an analog-to-digital converter and a controller, and the high-voltage bus connecting bar is provided with a voltage sampling point and a temperature sampling point; the voltage sampling point is connected with the input end of the analog-to-digital converter through the voltage acquisition circuit; the temperature sampling point is connected with the input end of the analog-to-digital converter through the temperature acquisition circuit; and the output end of the analog-to-digital converter is connected with the controller. According to the invention, real-time acquisition and temperature correction of the high-voltage bus current are realized, so that high precision of current sampling is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of current sampling, and in particular, relates to a new energy vehicle high-voltage bus current sampling system. Background Art

[0002] With the rapid development of the new energy vehicle industry, the need to reduce vehicle costs has become an important indicator for major vehicle manufacturers and parts companies. At present, new energy vehicle current measurement devices have problems such as high cost and susceptibility to temperature, which makes it difficult to meet the new energy vehicle's needs for low cost and acquisition accuracy at the same time. A low-cost, high-precision current measurement solution is urgently needed.

[0003] The comparative document (CN202420987517.3) provides a current detection device and a load current detection system, wherein the current detection device includes: a current acquisition unit, a signal processing unit, and an overcurrent indication unit. The current acquisition unit is connected to both ends of the load to form a current loop with the load. The current acquisition unit is used to collect the current signal flowing through the load according to the configured current detection range, and convert the collected current signal into a voltage signal. The signal processing unit is connected to the current acquisition unit for filtering and outputting the voltage signal. The overcurrent indication unit is connected to the current loop formed by the current acquisition unit and the load. When the current flowing through the overcurrent indication unit exceeds the preset current threshold, the overcurrent indication unit causes the current acquisition unit to stop collecting the current of the load and issue an overcurrent indication. The above-mentioned current detection device can issue an overcurrent indication and stop current detection when the current is too large to avoid being damaged by large current.

[0004] However, the purpose of the above-mentioned reference documents is to realize overcurrent prompting, and no solutions are proposed for improving the current sampling accuracy, reducing the cost, etc. Therefore, the present application proposes a new energy vehicle high-voltage bus current sampling system. Summary of the invention

[0005] The present invention aims to overcome the deficiencies of the prior art and proposes a new energy vehicle high-voltage bus current sampling system to achieve the following objectives: to achieve real-time acquisition and temperature correction of the high-voltage bus current, thereby ensuring high accuracy of current sampling.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a new energy vehicle high-voltage bus current sampling system, the system includes a high-voltage bus connection bar, a voltage acquisition circuit, a temperature acquisition circuit, an analog-to-digital converter, and a controller, wherein the high-voltage bus connection bar is provided with a voltage sampling point and a temperature sampling point; the voltage sampling point is connected to the input end of the analog-to-digital converter through the voltage acquisition circuit; the temperature sampling point is connected to the input end of the analog-to-digital converter through the temperature acquisition circuit; the output end of the analog-to-digital converter is connected to the controller.

[0007] Preferably, the voltage acquisition circuit includes a current limiting resistor R3, a current limiting resistor R4, a power supply u5, a feedback resistor R6, a filter capacitor C1, an operational amplifier, and a pull-down resistor R5; wherein, the first end of the current limiting resistor R3 is connected to the first voltage sampling point, and the second end of the current limiting resistor R3 is connected to the reverse end of the operational amplifier; the first end of the current limiting resistor R4 is connected to the second voltage sampling point, and the second end of the current limiting resistor R4 is connected to the same direction end of the operational amplifier; the first end of the pull-down resistor R5 is grounded, and the second end of the pull-down resistor R5 is connected to the same direction end of the operational amplifier; the feedback resistor R6 is connected between the reverse end and the output end of the operational amplifier; the output end of the operational amplifier is connected to the input end of the analog-to-digital converter; the positive power supply end of the operational amplifier is connected to the power supply u5, and the positive power supply end is also grounded through the filter capacitor C1; the negative power supply end of the operational amplifier is grounded.

[0008] Preferably, the current limiting resistor R3, the current limiting resistor R4, the feedback resistor R6, the filter capacitor C1, and the pull-down resistor R5 are configured as R3=R4, and R5=R6.

[0009] Preferably, the voltage acquisition circuit includes an RC filter circuit, which is connected between the output end of the operational amplifier and the input end of the analog-to-digital converter. The RC filter circuit includes a current limiting resistor R7 and a filter capacitor C2, wherein a first end of the current limiting resistor R7 is connected to the output end of the operational amplifier, a second end of the current limiting resistor R7 is connected to the input end of the analog-to-digital converter, and the second end of the current limiting resistor R7 is also grounded through the filter capacitor C2.

[0010] Preferably, the temperature acquisition circuit includes a pull-up resistor R1, a reference power supply u3, and a temperature sensor R2, wherein the temperature sensor R2 is arranged at the temperature sampling point; the reference power supply u3, the pull-up resistor R1, and the temperature sensor R2 are connected in series in sequence and then grounded, and at the same time, the lead terminal between the pull-up resistor R1 and the temperature sensor R2 is connected to the input end of the analog-to-digital converter.

[0011] Preferably, the temperature sampling point is arranged at the center of the high-voltage busbar connecting bar.

[0012] Preferably, the voltage acquisition circuit is used to collect the analog voltage signal between the voltage sampling points and send it to the analog-to-digital converter after amplification; the temperature acquisition circuit is used to collect the analog temperature signal at the temperature sampling point and send it to the analog-to-digital converter; the analog-to-digital converter is used to convert the analog voltage signal and the analog temperature signal into corresponding digital signals and send them to the controller; the controller is used to calculate the current flowing through the high-voltage busbar connection bar based on the voltage and temperature data converted by the analog-to-digital converter.

[0013] Preferably, a curve of the changing relationship between the internal resistance of the high-voltage busbar connecting bar and the temperature is pre-stored in the controller; based on the temperature data collected by the temperature acquisition circuit, the controller obtains the internal resistance of the high-voltage busbar connecting bar at the corresponding temperature from the changing relationship curve; finally, combined with the voltage data collected by the voltage acquisition circuit, the controller uses Ohm's law to calculate the current value flowing through the high-voltage busbar connecting bar.

[0014] Preferably, the system further comprises a display, which is connected to the controller and is used to display the temperature data collected by the temperature acquisition circuit, the voltage data collected by the voltage acquisition circuit, and the current value flowing through the high-voltage busbar connecting bar.

[0015] Preferably, the controller adopts a microcontroller MCU.

[0016] The technical effects of the present invention are:

[0017] (1) Low cost: By using the existing connection row structure of the high-voltage system and arranging sampling points for sampling, the production cost is greatly reduced, which is conducive to large-scale promotion and application.

[0018] (2) High precision: Through the use of operational amplifiers and analog-to-digital converters, and by overcoming the influence of temperature on current measurement, high-precision measurement of high-voltage bus current is achieved.

[0019] (3) Real-time performance: The voltage acquisition circuit and temperature acquisition circuit can collect the voltage and temperature data of the connection row in real time. The controller chip can calculate and correct the current value according to the temperature in real time based on its efficient data processing capability, thus ensuring the real-time performance of the current measurement.

[0020] (4) Reliability: The system has a simple structure, is easy to implement and maintain, and all components are mature products with high reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a simplified structural diagram of a high-voltage bus current sampling system for a new energy vehicle according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of temperature and voltage sampling principle of an embodiment of the present invention.

[0023] Figure 1 In the figure, 1 is the temperature sampling point, 2 is the connection bar, 3 is the temperature acquisition circuit, 4 is the voltage acquisition circuit, 5 is the analog-to-digital converter, and 6 is the controller chip;

[0024] Figure 2 Among them, 31 is a pull-up resistor R1, 32 is a reference power supply u3, 33 is a temperature sensor R2, 41 is a current limiting resistor R3, 42 is a current limiting resistor R4, 43 is a power supply u5, 44 is a feedback resistor R6, 45 is a filter capacitor C1, 46 is a filter capacitor C2, 47 is a current limiting resistor R7, 48 is an operational amplifier, and 49 is a pull-down resistor R5. DETAILED DESCRIPTION

[0025] The following is a further detailed description of the specific implementation of the present invention through the description of the embodiments with reference to the accompanying drawings, the purpose of which is to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation. It should be noted that the words "first", "second" and the like described in this application are only for the convenience of describing the technical solution to distinguish different components, and are not used to limit this application. In order to make the technical solution of the present invention clearer, the present invention is explained through the following embodiments.

[0026] With the development of new energy vehicle technology, there are more and more high-voltage components inside new energy vehicles, which are often connected by high-voltage busbars. Therefore, measuring the current on the high-voltage busbar is very important for all aspects of new energy vehicles from production to after-sales. At present, the current measurement devices of new energy vehicles have problems such as high cost and susceptibility to temperature, which makes it difficult to meet the requirements of new energy vehicles for low cost and acquisition accuracy at the same time.

[0027] To solve the above problems, this embodiment proposes a new energy vehicle high voltage bus current sampling system, such as Figure 1 As shown, the system includes a high-voltage busbar connection bar 2, a voltage acquisition circuit 4, a temperature acquisition circuit 3, an analog-to-digital converter 5 (AD), and a controller 6 (IC), wherein the high-voltage busbar connection bar is provided with voltage sampling points (a first voltage sampling point A, a second voltage sampling point B) and a temperature sampling point 1; the voltage sampling points A and B are both connected to the input end of the analog-to-digital converter 5 through the voltage acquisition circuit 4; the temperature sampling point 1 is connected to the input end of the analog-to-digital converter 5 through the temperature acquisition circuit 3; and the output end of the analog-to-digital converter 5 is connected to the controller 6.

[0028] The high-voltage busbar connecting bar is an important component in the power system, and is usually used to connect multiple electrical devices (such as transformers, switchgear, etc.) to the high-voltage busbar to achieve power distribution and transmission. When the current on the high-voltage busbar flows through the connecting bar, the internal resistance r of the connecting bar will cause a voltage drop proportional to the current between the two voltage sampling points (A and B), that is, the voltage is equal to the current on the high-voltage busbar multiplied by the internal resistance r of the connecting bar. At the same time, when the current on the high-voltage busbar passes through the connecting bar, the connecting bar will inevitably generate heat due to the existence of the internal resistance r, thereby causing the temperature of the connecting bar to rise and thus affect the current measurement. Therefore, the system of this embodiment sets a temperature sampling point on the connecting bar to collect the temperature of the connecting bar.

[0029] Since the connecting bars are mostly made of copper bars, and the internal resistance of the copper bars is very small, generally below the milliohm level, it is necessary to amplify the voltage between the voltage sampling points A and B before sending it to the analog-to-digital converter for conversion. Specifically, Figure 2 As shown, the voltage acquisition circuit of this embodiment includes a current limiting resistor R3, a current limiting resistor R4, a power supply u5, a feedback resistor R6, a filter capacitor C1, an operational amplifier, and a pull-down resistor R5. Among them, the first end of the current limiting resistor R3 is connected to the first voltage sampling point A, the voltage at point A is represented by u1, and the second end of the current limiting resistor R3 is connected to the reverse end of the operational amplifier; the first end of the current limiting resistor R4 is connected to the second voltage sampling point B, the voltage at point B is represented by u2, and the second end of the current limiting resistor R4 is connected to the same direction end of the operational amplifier; the first end of the pull-down resistor R5 is grounded, and the second end of the pull-down resistor R5 is connected to the same direction end of the operational amplifier; the feedback resistor R6 is connected between the reverse end and the output end of the operational amplifier; the output end of the operational amplifier is connected to the input end of the analog-to-digital converter; the positive power supply end of the operational amplifier is connected to the power supply u5, and the positive power supply end is also grounded through the filter capacitor C1; the negative power supply end of the operational amplifier is grounded.

[0030] The current limiting resistor R3, the current limiting resistor R4, the pull-down resistor R5, the feedback resistor R6 and the operational amplifier form a differential amplifier circuit, which is used to amplify the voltage difference u2-u1 between the voltage sampling points A and B, and can improve the signal-to-noise ratio of the signal. At the same time, in order to improve the sampling accuracy to ensure the accuracy of the subsequent current calculation, in this embodiment, the current limiting resistor R3, the current limiting resistor R4, the feedback resistor R6, the filter capacitor C1, and the pull-down resistor R5 are configured as R3=R4, R5=R6, and the output voltage of the operational amplifier is

[0031] At the same time, in order to improve the signal-to-noise ratio of the operational amplifier output signal and improve the reliability of the voltage sampling data, the voltage acquisition circuit of this embodiment also includes an RC filter circuit for filtering the operational amplifier output signal to remove noise. Specifically, the RC filter circuit is connected between the output end of the operational amplifier and the input end of the analog-to-digital converter, and the RC filter circuit includes a current limiting resistor R7 and a filter capacitor C2, wherein the first end of the current limiting resistor R7 is connected to the output end of the operational amplifier, and the second end of the current limiting resistor R7 is connected to the input end of the analog-to-digital converter, and the second end of the current limiting resistor R7 is also grounded through the filter capacitor C2.

[0032] like Figure 2 As shown, the temperature acquisition circuit of this embodiment includes a pull-up resistor R1, a reference power supply u3, and a temperature sensor R2, wherein the temperature sensor R2 is arranged at the temperature sampling point; the reference power supply u3, the pull-up resistor R1, and the temperature sensor R2 are connected in series and then grounded, and at the same time, the lead terminal between the pull-up resistor R1 and the temperature sensor R2 (the terminal voltage is represented as u4) is connected to the input end of the analog-to-digital converter. Based on the temperature acquisition circuit, the resistance value of the temperature sensor R2 is Then, the temperature of the connection row can be obtained according to the resistance value table of the temperature sensor at different temperatures and converted into a voltage signal to be sent to the analog-to-digital converter. The temperature sensor R2 of this embodiment adopts a thermistor.

[0033] Due to the design and material properties of the high-voltage busbar connecting bar, the temperature at its center is often closer to the average temperature of the surrounding area, and is less susceptible to external environmental interference than the peripheral area of ​​the connecting bar. Therefore, this embodiment sets the temperature sampling point at the center of the high-voltage busbar connecting bar to provide more accurate temperature data.

[0034] The sampling principle of the high-voltage bus current sampling system of this embodiment is as follows: the voltage acquisition circuit is used to collect the analog voltage signal between the voltage sampling points and send it to the analog-to-digital converter after amplification; the temperature acquisition circuit is used to collect the analog temperature signal at the temperature sampling point and send it to the analog-to-digital converter; the analog-to-digital converter is used to convert the analog voltage signal and the analog temperature signal into corresponding digital signals and send them to the controller; the controller is used to calculate the current flowing through the high-voltage bus connecting bar based on the voltage and temperature data converted by the analog-to-digital converter.

[0035] Among them, the controller pre-stores a curve of the change relationship between the internal resistance of the high-voltage bus connection bar and the temperature; according to the temperature data collected by the temperature acquisition circuit, the controller obtains the internal resistance of the high-voltage bus connection bar at the corresponding temperature from the change relationship curve to perform internal resistance correction; finally, combined with the voltage data collected by the voltage acquisition circuit, the controller uses Ohm's law to calculate and correct the current value flowing through the high-voltage bus connection bar.

[0036] As the core processor of the present invention, the controller needs to have efficient data processing capabilities to ensure the accuracy and real-time performance of current sampling. At the same time, in order to reduce costs and reduce PCB layout space, the size of the controller should not be too large. Therefore, in this embodiment, the controller adopts a microcontroller MCU, which fully meets the above requirements.

[0037] The system of this embodiment also includes a display, which is connected to the controller and is used to display the temperature data collected by the temperature collection circuit, the voltage data collected by the voltage collection circuit, and the current value flowing through the high-voltage bus connection bar. The setting of the display facilitates the user to observe the current on the high-voltage bus intuitively and in real time, and provides convenience for the user in product testing, fault diagnosis, etc.

[0038] In summary, the advantages of this embodiment are as follows:

[0039] (1) Low cost: By using the existing connection row structure of the high-voltage system and arranging sampling points for sampling, the production cost is greatly reduced, which is conducive to large-scale promotion and application.

[0040] (2) High precision: Through the use of operational amplifiers and analog-to-digital converters, and by overcoming the influence of temperature on current measurement, high-precision measurement of high-voltage bus current is achieved.

[0041] (3) Real-time performance: The voltage acquisition circuit and temperature acquisition circuit can collect the voltage and temperature data of the connection row in real time. The controller chip can calculate and correct the current value according to the temperature in real time based on its efficient data processing capability, thus ensuring the real-time performance of the current measurement.

[0042] (4) Reliability: The system structure of the present application is simple, easy to implement and maintain, and all components are mature products with high reliability and stability.

[0043] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A new energy vehicle high voltage bus current sampling system, characterized by: The system includes a high-voltage busbar connection bar, a voltage acquisition circuit, a temperature acquisition circuit, an analog-to-digital converter, and a controller, wherein the high-voltage busbar connection bar is provided with a voltage sampling point and a temperature sampling point; the voltage sampling point is connected to the input end of the analog-to-digital converter through the voltage acquisition circuit; the temperature sampling point is connected to the input end of the analog-to-digital converter through the temperature acquisition circuit; and the output end of the analog-to-digital converter is connected to the controller.

2. A new energy vehicle high voltage bus current sampling system according to claim 1, characterized in that: The voltage acquisition circuit includes a current limiting resistor R3, a current limiting resistor R4, a power supply u5, a feedback resistor R6, a filter capacitor C1, an operational amplifier, and a pull-down resistor R5; wherein, the first end of the current limiting resistor R3 is connected to the first voltage sampling point, and the second end of the current limiting resistor R3 is connected to the reverse end of the operational amplifier; the first end of the current limiting resistor R4 is connected to the second voltage sampling point, and the second end of the current limiting resistor R4 is connected to the same direction end of the operational amplifier; the first end of the pull-down resistor R5 is grounded, and the second end of the pull-down resistor R5 is connected to the same direction end of the operational amplifier; the feedback resistor R6 is connected between the reverse end and the output end of the operational amplifier; the output end of the operational amplifier is connected to the input end of the analog-to-digital converter; the positive power supply end of the operational amplifier is connected to the power supply u5, and the positive power supply end is also grounded through the filter capacitor C1; the negative power supply end of the operational amplifier is grounded.

3. A new energy vehicle high voltage bus current sampling system according to claim 2, characterized in that: The current limiting resistor R3, the current limiting resistor R4, the feedback resistor R6, the filter capacitor C1, and the pull-down resistor R5 are configured as R3=R4, and R5=R6.

4. A new energy vehicle high voltage bus current sampling system according to claim 2 or 3, characterized in that: The voltage acquisition circuit includes an RC filter circuit, which is connected between the output end of the operational amplifier and the input end of the analog-to-digital converter. The RC filter circuit includes a current limiting resistor R7 and a filter capacitor C2, wherein a first end of the current limiting resistor R7 is connected to the output end of the operational amplifier, a second end of the current limiting resistor R7 is connected to the input end of the analog-to-digital converter, and the second end of the current limiting resistor R7 is also grounded through the filter capacitor C2.

5. A new energy vehicle high voltage bus current sampling system according to claim 1, characterized in that: The temperature acquisition circuit includes a pull-up resistor R1, a reference power supply u3, and a temperature sensor R2, wherein the temperature sensor R2 is arranged at the temperature sampling point; the reference power supply u3, the pull-up resistor R1, and the temperature sensor R2 are connected in series in sequence and then grounded, and at the same time, the lead terminal between the pull-up resistor R1 and the temperature sensor R2 is connected to the input end of the analog-to-digital converter.

6. A new energy vehicle high voltage bus current sampling system according to claim 1 or 5, characterized in that: The temperature sampling point is arranged at the center of the high-voltage busbar connecting bar.

7. A new energy vehicle high voltage bus current sampling system according to claim 1, characterized in that: The voltage acquisition circuit is used to collect the analog voltage signal between the voltage sampling points and send it to the analog-to-digital converter after amplification; The temperature acquisition circuit is used to acquire the analog temperature signal at the temperature sampling point and send it to the analog-to-digital converter; The analog-to-digital converter is used to convert the analog voltage signal and the analog temperature signal into corresponding digital signals and send them to the controller; the controller is used to calculate the current flowing through the high-voltage busbar connection bar based on the voltage and temperature data converted by the analog-to-digital converter.

8. A new energy vehicle high voltage bus current sampling system according to claim 7, characterized in that: The controller pre-stores a curve of the relationship between the internal resistance of the high-voltage busbar connection bar and the temperature; based on the temperature data collected by the temperature acquisition circuit, the controller obtains the internal resistance of the high-voltage busbar connection bar at the corresponding temperature from the change relationship curve; finally, combined with the voltage data collected by the voltage acquisition circuit, the controller uses Ohm's law to calculate the current value flowing through the high-voltage busbar connection bar.

9. A new energy vehicle high voltage bus current sampling system according to claim 1, characterized in that: The system also includes a display, which is connected to the controller and is used to display the temperature data collected by the temperature collection circuit, the voltage data collected by the voltage collection circuit, and the current value flowing through the high-voltage busbar connecting bar.

10. A new energy vehicle high voltage bus current sampling system according to claim 1, characterized in that: The controller adopts a microcontroller MCU.

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