System for detecting pre-charging voltage by using LINK-

Abstract

The utility model belongs to the technical field of voltage acquisition, and particularly relates to a system for detecting pre-charging voltage by using LINK-, which comprises a high-low voltage isolation circuit, an ADC chip sampling circuit and a digital isolation chip circuit, the ADC chip sampling circuit comprises an ADC sampling chip U1, the digital isolation chip circuit comprises a digital isolation chip U2, and the digital isolation chip U2 is connected with the ADC sampling chip U1. And an SPI communication line of the ADC sampling chip U1 communicates with the master control MCU chip U3 through the digital isolation chip U2. The pre-charging voltage detection circuit is reasonable in design, simple in structure and convenient to process, can directly detect the pre-charging voltage of the BMS system, reduces the system cost, improves the system stability, can adapt to different relay controllers, is wider in application range, and effectively meets the use requirements.

Description

Technical Field

[0001] This utility model belongs to the field of voltage acquisition technology, and in particular relates to a LINK-detection precharge voltage system. Background Technology

[0002] The power battery is a crucial component of new energy vehicles, and its performance and lifespan directly affect the vehicle's performance and range. The power battery supplies power to the entire vehicle through main discharge positive and negative relays. With the rapid development of my country's new energy industry, the demand for a Battery Management System (BMS) necessitates real-time monitoring of power battery voltage data. Furthermore, for functional safety considerations and BMS system software redundancy design, the BMS system needs to collect pre-charge voltage data.

[0003] The traditional approach uses high and low voltage isolation circuits, low voltage subtraction amplifier circuits, low voltage follower circuits, and AD port acquisition circuits. This approach has several drawbacks: it is slow to detect, the BMS system needs to wait for the motor controller to fully start before it can make a judgment, which affects the vehicle's power-on time, and because the conditions of each motor controller are different, the system design needs to be customized according to the project, which increases the complexity of the project. To address these issues, we provide a LINK-detection precharge voltage system that can solve the above problems. Utility Model Content

[0004] This invention addresses the technical problems existing in the aforementioned precharge voltage acquisition process by proposing a LINK-based precharge voltage detection system. This system is rationally designed, simple in structure, easy to manufacture, and enables direct detection of precharge voltage by the BMS system, reducing system costs, improving system stability, and adapting to different relay controllers, thus broadening its application range and effectively meeting usage requirements.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is a LINK-detection precharge voltage system, including a high-low voltage isolation circuit, an ADC chip sampling circuit, and a digital isolation chip circuit. The ADC chip sampling circuit includes an ADC sampling chip U1, and the digital isolation chip circuit includes a digital isolation chip U2. The SPI communication line of the ADC sampling chip U1 communicates with the main control MCU chip U3 through the digital isolation chip U2. The high-low voltage isolation circuit includes a solid-state relay K1. The high-voltage side of the solid-state relay K1 includes a voltage divider resistor R1, a sampling resistor R2, a pull-up resistor R3, and a diode D1. The high-voltage side pin of the solid-state relay K1 is connected to the voltage divider resistor R1. One side of the voltage divider resistor R1 is connected to one LINK- pin of the power battery through the diode D1, and the other side is connected to the precharge resistor R. The other side of the precharge resistor R is connected to the precharge... Relay K2 is connected in parallel to the LINK- of one power battery circuit. The other side of the precharge relay K2 is connected to the main negative terminal of the power battery. The other pin of the high-voltage side of solid-state relay K1 is connected to sampling resistor R2 and pull-up resistor R3. The other side of sampling resistor R2 is connected to the reference voltage of ADC sampling chip U1. The other side of pull-up resistor R3 is connected to the AD detection interface of ADC sampling chip U1. The low-voltage side of solid-state relay K1 includes resistors R4, R5, and R6 and MOSFET Q1. One pin of the low-voltage side of solid-state relay K1 is connected to resistor R6. The other end of R6 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is connected to the GND of the BMS system. The gate of MOSFET Q1 is connected to resistors R4 and R5. The other end of resistor R4 is connected to the BMS system. The other end of resistor R5 is connected to the GND of the BMS system.

[0006] Preferably, a main negative relay is also connected to LINK- on one of the power battery circuits and is connected to the negative terminal of the power battery. A main positive relay and a LINK+ circuit are provided on the positive terminal circuit of the power battery, and a main load is provided between LINK+ and LINK-.

[0007] Preferably, the solid-state relay K1 has an isolation voltage of up to 2500V, which completely isolates the negative terminal of the battery pack from the negative terminal of the BMS system to ensure the safety of the BMS system.

[0008] As a preferred option, the digital isolation chip U2 achieves communication between the high-voltage side and the low-voltage side through magnetic isolation technology.

[0009] Preferably, both the voltage divider resistors R1 and R2 are selected from the KΩ level.

[0010] Preferably, the reference voltage of the ADC sampling chip U1 is 5V.

[0011] As a preferred option, this system is used in 0-1000V power battery systems.

[0012] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0013] 1. This utility model provides a LINK-detection precharge voltage system, which can effectively solve the problem of motor controller system matching by directly acquiring the precharge voltage using the BMS system. Compared with traditional acquisition methods, it can realize the BMS system to directly detect the precharge voltage through LINK-detection. It adopts a high-low voltage isolation design, which can greatly reduce the system cost without affecting the acquisition. Moreover, based on a series of safety designs, it ensures the safety of detecting the precharge voltage through LINK-detection without the need for corresponding software logic design using the BMS. It can adapt to different motor controllers, making its application range wider. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the existing external voltage acquisition system;

[0016] Figure 2 This is a schematic diagram of the circuit for acquiring the precharge voltage via LINK provided by this utility model;

[0017] Figure 3 This is a circuit diagram illustrating the application of this utility model;

[0018] Figure 4 This is a circuit diagram of the ADC chip sampling circuit and the digital isolation chip circuit provided by this utility model. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed in the following specification.

[0021] Examples, such as Figure 1 The diagram shows a circuit diagram of a high-voltage external acquisition system for electric vehicles in the prior art. It generally includes a high-low voltage isolation zone circuit, a low-voltage subtraction amplifier circuit, a low-voltage follower circuit, and an AD port acquisition circuit. The high-low voltage isolation zone circuit contains a first amplifier, a first branch, and a second branch. The first branch includes a detection switch K1, resistors R1 and R3. One end of detection switch K1 is connected to the positive terminal of the external voltage of the power battery, and the other end is electrically connected to resistor R1. Resistor R1 is also connected to the third pin of the first amplifier and resistor R3. Resistor R3 is connected to the ground terminal. The second branch includes a detection switch K2, resistors R2 and R4. One end of detection switch K2 is connected to the negative terminal of the external voltage of the power battery. The other end is electrically connected to resistor R2. Resistor R2 is also connected to the second pin of the first amplifier and resistor R4. Resistor R4 is also electrically connected to the first pin of the first operational amplifier and the fifth pin of the second operational amplifier. The eighth pin of the first operational amplifier is connected to the VCC terminal. The fourth pin of the first operational amplifier is connected to the VEE terminal. The sixth pin and the seventh pin of the second operational amplifier are electrically connected and input to the AD port acquisition circuit. In the above traditional precharge voltage acquisition system, although resistors R1 and R2 have large resistance values, they cannot achieve full isolation between the high voltage side and the low voltage side, which poses a safety hazard. Moreover, the sampled data will have errors after being amplified twice, resulting in inaccurate sampling values ​​of the total voltage of the battery pack.

[0022] Based on the above, in order to solve the technical problems existing in the current precharge voltage acquisition process, such as Figures 2-4As shown, a LINK-based precharge voltage detection system is provided, comprising a high-low voltage isolation circuit, an ADC chip sampling circuit, and a digital isolation chip circuit. The ADC chip sampling circuit includes an ADC sampling chip U1, with a reference voltage of 5V. The digital isolation chip circuit includes a digital isolation chip U2. The SPI communication line of the ADC sampling chip U1 communicates with the main control MCU chip U3 through the digital isolation chip U2. The high-low voltage isolation circuit includes a solid-state relay K1. The high-voltage side of the solid-state relay K1 includes a voltage divider resistor R1, a sampling resistor R2, a pull-up resistor R3, and a diode D1. Pin 4 of the high-voltage side of the solid-state relay K1 is connected to the voltage divider resistor R1. The other side of the voltage divider resistor R1 is connected to the power battery via diode D1, and to LINK- via another path. The other path is connected to the precharge resistor R, and the other side of the precharge resistor R is connected to the precharge relay K2. Connected in parallel to the LINK- of the power battery, the other side of the precharge relay K2 is connected to the main negative of the power battery. The other pin of the high-voltage side of the solid-state relay K1 is connected to the sampling resistor R2 and the pull-up resistor R3. The other side of the sampling resistor R2 is connected to the reference voltage of the ADC sampling chip U1. The other side of the pull-up resistor R3 is connected to the AD detection interface of the ADC sampling chip U1. The low-voltage side of the solid-state relay K1 includes resistors R4, R5, R6 and MOSFET Q1. The second pin of the low-voltage side of the solid-state relay K1 is connected to resistor R6. The other end of R6 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is connected to the GND of the BMS system. The gate of MOSFET Q1 is connected to resistors R4 and R5. The other end of resistor R4 is connected to the BMS system. The other end of resistor R5 is connected to the GND of the BMS system.

[0023] In the above process: The LINK-detection precharge voltage system provided by this utility model can effectively solve the problem of motor controller system matching by directly acquiring the precharge voltage through the BMS system. Compared with the traditional acquisition method, this utility model can realize the BMS system to directly detect the precharge voltage through LINK. It adopts a high-low voltage isolation design, which can greatly reduce the system cost without affecting the acquisition. Moreover, based on a series of safety designs, it can detect the precharge voltage through LINK while ensuring safety, without the need for corresponding software logic design using BMS. It can adapt to different motor controllers, making its application range wider.

[0024] To ensure the integrity of the system, a main negative relay is connected to the LINK- of the power battery circuit and is connected to the negative terminal of the power battery. A main positive relay and a LINK+ circuit are set on the positive terminal of the power battery circuit. A main load is set between LINK+ and LINK-. In other words, the isolation voltage of the solid-state relay K1 can reach 2500V, which completely isolates the negative terminal of the battery pack from the negative terminal of the BMS system to ensure the safety of the BMS system.

[0025] To further improve the accuracy of monitoring, the digital isolation chip U2 realizes communication between the high-voltage side and the low-voltage side through magnetic isolation technology. In other words, the SPI + digital isolation solution can quickly detect the change in total voltage, making the monitoring of the battery pack more precise and rapid. At the same time, it can also detect the status of the main relay, preventing the relay from sticking due to overcharging, over-discharging, etc.

[0026] To further improve system safety, both voltage divider resistors R1 and R2 are selected from the kΩ level. The current passing through the sampling system during operation is approximately 0.2mA, which greatly reduces the losses of the BMS system. At the same time, for electric vehicle systems (0-1000V), the leakage current of the kΩ-level isolation resistor is far less than 0.2mA, ensuring the safety of the entire vehicle system. Furthermore, this system can be used in 0-1000V power battery systems and can adapt to different relay controllers, thus having a wider range of applications.

[0027] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the technical solution of the present utility model.

Claims

1. A system for detecting precharge voltage using LINK, characterized in that, The high-low voltage isolation circuit, the ADC chip sampling circuit and the digital isolation chip circuit are included, the ADC chip sampling circuit includes an ADC sampling chip U1, the digital isolation chip circuit includes a digital isolation chip U2, the SPI communication line of the ADC sampling chip U1 communicates with a master control MCU chip U3 through the digital isolation chip U2, the high-low voltage isolation circuit includes a solid state relay K1, the high voltage side of the solid state relay K1 includes a voltage dividing resistor R1, a sampling resistor R2, a pull-up resistor R3 and a diode D1, the high voltage side pin of the solid state relay K1 is connected with the voltage dividing resistor R1, the other side of the voltage dividing resistor R1 is connected with a power battery one-way LINK- through a diode D1 and another way is connected with a pre-charge resistor R, the other side of the pre-charge resistor R is connected with a pre-charge relay K2, and is connected in parallel on the power battery one-way LINK-, the other side of the pre-charge relay K2 is connected with a power battery main negative, the other pin of the high voltage side of the solid state relay K1 is connected with the sampling resistor R2 and the pull-up resistor R3, the other side of the sampling resistor R2 is connected with the reference voltage of the ADC sampling chip U1, the other side of the pull-up resistor R3 is connected with the AD detection interface of the ADC sampling chip U1, the low voltage side of the solid state relay K1 includes a resistor R4, a resistor R5, a resistor R6 and a MOS tube Q1, one pin of the low voltage side of the solid state relay K1 is connected with the resistor R6, the other end of R6 is connected with the D pole of the MOS tube Q1, the S pole of the MOS tube Q1 is connected with the GND of the BMS system, the G pole of the MOS tube Q1 is connected with the resistor R4 and the resistor R5, the other end of the resistor R4 is connected with the BMS system, and the other end of the resistor R5 is connected with the GND of the BMS system.

2. The LINK-detect pre-charge voltage system of claim 1, wherein, The main negative relay is further connected on the LINK- of the power battery one-way and is connected with the negative pole of the power battery, and the main positive relay and the LINK+ one-way are arranged on the positive pole one-way of the power battery, and the main load is arranged between the LINK+ and the LINK-.

3. The LINK-detect pre-charge voltage system of claim 1, wherein, The isolation voltage of the solid state relay K1 is up to 2500V, so that the negative pole of the battery pack and the negative pole of the BMS system are completely isolated, so as to guarantee the safety of the BMS system.

4. The LINK-detect pre-charge voltage system of claim 1, wherein, The digital isolation chip U2 realizes the communication between the high voltage side and the low voltage side through the magnetic isolation technology.

5. The LINK-detect pre-charge voltage system of claim 1, wherein, The voltage dividing resistors R1 and R2 are selected from the KΩ level resistors.

6. The LINK-detect pre-charge voltage system of claim 1, wherein, The reference voltage of the ADC sampling chip U1 is 5V.

7. A system for detecting pre-charge voltage using LINK- according to any one of claims 1-6, wherein, The system is applied in the 0-1000V power battery system.

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