Battery detection circuit and BMS battery system

Abstract

The utility model relates to the field of BMS system detection, and more specifically relates to a battery detection circuit and a BMS battery system. The battery detection circuit comprises a voltage conversion circuit and a sampling hold circuit. The detection input end of the voltage conversion circuit is used for being connected with the positive electrode of a to-be-detected battery. The detection output end of the voltage conversion circuit is connected with the negative electrode of the battery to be detected; the signal output end of the voltage conversion circuit is connected with the signal input end of the sampling hold circuit; the first output end of the voltage conversion circuit is used for being connected with a control unit; the second output end of the voltage conversion circuit is grounded. The voltage conversion circuit is used for converting the high voltage of the battery into a low-voltage signal. The sampling hold circuit is used for stabilizing the voltage of the output end. The voltage conversion circuit is matched with the sampling and holding circuit, so that the complexity of a traditional differential circuit can be changed, the cost is reduced, the complexity of a detection circuit is greatly reduced, and voltage detection in multiple sections of series-connected battery cells is realized.

Description

Technical Field

[0001] The utility model relates to the field of BMS system detection, and more specifically, to a battery detection circuit and a BMS battery system. Background Art

[0002] With the development of new energy vehicles, the energy storage and energy distribution technologies of vehicles are particularly important. Therefore, the importance of equipping a large-capacity vehicle battery pack with a battery management system (BMS) has become increasingly prominent. As an important bridge connecting the battery pack and the vehicle control system, the BMS is not only responsible for monitoring the state parameters of the battery pack, such as voltage, current, temperature, and SOC (remaining power), etc., but also undertakes key tasks such as balancing the performance differences between battery cells, preventing thermal runaway, optimizing the charging strategy, and extending the battery service life. In the current battery pack design that uses a large number of series-connected batteries, it is very important for the BMS system to continuously detect the performance of each battery to ensure the safety of each battery.

[0003] However, in the process of BMS system design and implementation, the battery detection link faces the dual challenges of complexity and high cost. In order to increase the battery pack power, a large number of series-connected batteries are usually used in the prior art. In a series circuit, the failure of one battery easily affects the entire series battery branch. Therefore, it is necessary to detect the performance of each battery separately. In the prior art, the voltage measurement of each battery usually uses a differential circuit, but the detection using a differential circuit is relatively complex, resulting in a cumbersome overall circuit of the BMS system and high cost. Summary of the Utility Model

[0004] The utility model aims to overcome at least one defect (shortcoming) of the above prior art, and provides a battery detection circuit and a BMS battery system for solving the problems of complex battery detection circuit and high cost in existing series-connected batteries.

[0005] The technical solution adopted by the utility model is that a battery detection circuit includes: a voltage conversion circuit and a sample and hold circuit; the detection input end of the voltage conversion circuit is used to be connected to the positive electrode of the battery to be measured; the detection output end of the voltage conversion circuit is connected to the negative electrode of the battery to be measured; the signal output end of the voltage conversion circuit is connected to the signal input end of the sample and hold circuit; the first output end of the voltage conversion circuit is used to be connected to the control unit; the second output end of the voltage conversion circuit is grounded.

[0006] The voltage conversion includes a triode; the base of the triode is used to be connected to the negative electrode of the battery to be measured; the emitter of the triode is used to be connected to the positive electrode of the battery to be measured; the collector of the triode is respectively used to be connected to the control unit and the sample and hold circuit.

[0007] The triode is a PNP triode.

[0008] The sampling and holding circuit includes a first resistor. One end of the first resistor is respectively used to connect to the control unit and the voltage conversion circuit, and the other end is grounded.

[0009] The resistance value of the first resistor is 10 kΩ.

[0010] Furthermore, a BMS battery system is provided, including: a control unit and multiple serially connected batteries, and further including multiple such battery detection circuits. The battery detection circuits are connected in parallel to the batteries and are all communicatively connected to the control unit.

[0011] A second resistor is serially connected between the detection input terminal of the voltage conversion circuit and the positive electrode of the battery.

[0012] The BMS battery system further includes an auxiliary circuit for adjusting the battery power before detection.

[0013] The auxiliary circuit includes a first branch. The first branch includes: an auxiliary power supply, a first switch, and a third resistor connected in series; the positive electrode of the auxiliary power supply is connected to the first switch; the negative electrode of the auxiliary power supply is grounded; the third resistor is serially arranged with the battery and is connected to the positive electrode of the battery.

[0014] The auxiliary circuit includes a second branch. The second branch includes: a second switch and a fourth resistor connected in series; the fourth switch is connected to the negative electrode of the auxiliary power supply; the fourth resistor is connected to the negative electrode of the battery.

[0015] Each claim needs to be discussed in terms of its working principle and further technical problems to be solved.

[0016] Compared with the prior art, the beneficial effects of the present utility model are as follows: The voltage conversion circuit is used to convert the high voltage of the battery into a low-voltage signal. The sampling and holding circuit is used to stabilize the voltage at the output end. By cooperating the voltage conversion circuit with the sampling and holding circuit, it can change the complexity of the traditional use of differential circuits, reduce costs, and greatly reduce the complexity of the detection circuit, realizing voltage detection in multiple series-connected battery cells to adapt to a power battery pack formed by ten or even dozens of lithium batteries connected in series. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the schematic diagram of the detection circuit in the present utility model.

[0018] Figure 2 It is the circuit diagram of the detection circuit in the present utility model.

[0019] Figure 3 It is the circuit diagram of the BMS battery system in the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The attached drawings of the present utility model are only for illustrative purposes and should not be construed as a limitation to the present utility model. For better illustration of the following embodiments, some components in the drawings may be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0021] Embodiment 1

[0022] As Figure 1 shown, this embodiment is a battery detection circuit, including: a voltage conversion circuit and a sample and hold circuit; the detection input terminal of the voltage conversion circuit is used to connect to the positive electrode of the battery to be measured; the detection output terminal of the voltage conversion circuit is connected to the negative electrode of the battery to be measured; the signal output terminal of the voltage conversion circuit is connected to the signal input terminal of the sample and hold circuit; the first output terminal of the voltage conversion circuit is used to connect to the control unit; the second output terminal of the voltage conversion circuit is grounded.

[0023] The voltage conversion circuit is used to convert the high voltage of the battery into a low voltage signal. The sample and hold circuit is used to stabilize the voltage at the output terminal. By cooperating the voltage conversion circuit with the sample and hold circuit, the complexity of the traditional use of differential circuits can be changed, the cost can be reduced, and the complexity of the detection circuit can be greatly reduced, realizing voltage detection in multiple series-connected battery cells to adapt to a power battery pack formed by the series connection of a dozen or even dozens of lithium batteries.

[0024] As Figure 2 shown, the voltage conversion includes a triode Q1; the base B of the triode Q1 is used to connect to the negative electrode of the battery to be measured; the emitter E of the triode Q1 is used to connect to the positive electrode of the battery to be measured; the collector C of the triode Q1 is respectively used to connect to the control unit and the sample and hold circuit. The two-stage current of the triode Q1 has an approximate characteristic for sampling and measuring the voltage, so the cost can be lower and the circuit can be more concise. The triode Q1 is a PNP triode Q1.

[0025] The sample and hold circuit includes a first resistor R1, one end of the first resistor R1 is respectively used to connect to the control unit and the voltage conversion circuit, and the other end is grounded.

[0026] The resistance value of the first resistor R1 is 10 kΩ.

[0027] Embodiment 2

[0028] As Figure 3 shown, this embodiment is a BMS battery system, including: a control unit and multiple series-connected batteries, and further including multiple battery detection circuits, the battery detection circuits are connected in parallel to the batteries and are all communicatively connected to the control unit.

[0029] In this embodiment, the batteries connected in series are three, namely C1, C2, and C3, and each battery has a capacitance of 2 mF. The detection circuit includes a voltage conversion circuit and a sample-and-hold circuit. Specifically, the voltage conversion circuit is a PNP transistor Q1, and the model used is mmbt5401. The sample-and-hold circuit is a first resistor R1 with a resistance value of 10 kΩ. In this embodiment, battery detection circuits are provided for two adjacent batteries C1 and C2 among the batteries connected in series. Two voltage detection circuits are used. The collector C of the PNP transistor Q1 is connected to the control unit, and the control unit can be an MCU. The collector C of the PNP transistor Q1 is respectively connected to the MCU and one end of the first resistor R1. The other end of the first resistor R1 is grounded.

[0030] A second resistor R2 is connected in series between the detection input terminal of the voltage conversion circuit and the positive electrode of battery C1.

[0031] The emitter E of the PNP transistor Q1 is connected to the positive electrode of battery C1 through the second resistor R2. Specifically, the resistance value of the second resistor R2 is 10 kΩ. The base B of the PNP transistor Q1 is connected to the negative voltage of battery C1.

[0032] The BMS battery system further includes an auxiliary circuit for adjusting the battery power before detection. In this embodiment, the auxiliary circuit adjusts the power of the series-connected batteries C1 and C2.

[0033] The auxiliary circuit includes a first branch, and the first branch includes: an auxiliary power supply U1, a first switch, and a third resistor R3 connected in series; the positive electrode of the auxiliary power supply U1 is connected to the first switch; the negative electrode of the auxiliary power supply U1 is grounded; the third resistor R3 is connected in series with battery C1 and is connected to the positive electrode of battery C1.

[0034] The output voltage of the auxiliary power supply U1 is 12 V. The resistance value of the third resistor R3 is 20 mΩ. The positive electrode of the auxiliary power supply U1 is connected to the third resistor R3 through the first switch. One end of the third resistor R3 is connected to battery C1, and the other end is connected to the first switch.

[0035] The auxiliary circuit includes a second branch, and the second branch includes: a second switch and a fourth resistor R4 connected in series; the fourth switch is connected to the negative electrode of the auxiliary power supply U1; the fourth resistor R4 is connected to the negative electrode of battery C2.

[0036] The resistance value of the fourth resistor R4 is 20 mΩ. The negative electrode of the auxiliary power supply U1 is connected to the fourth resistor R4 through the second switch. One end of the fourth resistor R4 is connected to the negative electrode of battery C2, and the other end is connected to the second switch.

[0037] Obviously, the above embodiments of the present utility model are merely examples for clearly illustrating the technical solutions of the present utility model, rather than limitations on the specific implementation manners of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the claims of the present utility model shall be included within the protection scope of the claims of the present utility model.

Claims

1. A battery detection circuit, characterized in that, Comprising: A voltage conversion circuit and a sample and hold circuit; The detection input terminal of the voltage conversion circuit is used to be connected to the positive electrode of the battery to be measured; The detection output terminal of the voltage conversion circuit is connected to the negative electrode of the battery to be measured; The signal output terminal of the voltage conversion circuit is connected to the signal input terminal of the sample and hold circuit; The first output terminal of the voltage conversion circuit is used to be connected to the control unit; The second output terminal of the voltage conversion circuit is grounded.

2. The battery detection circuit according to claim 1, wherein The voltage conversion includes a triode; The base of the triode is used to be connected to the negative electrode of the battery to be measured; The emitter of the triode is used to be connected to the positive electrode of the battery to be measured; The collector of the triode is respectively used to be connected to the control unit and the sample and hold circuit.

3. A battery detection circuit according to claim 2, characterized in that, The triode is a PNP triode.

4. A battery detection circuit according to any one of claims 1-3, characterized in that, The sample and hold circuit includes a first resistor, one end of the first resistor is respectively used to be connected to the control unit and the voltage conversion circuit, and the other end is grounded.

5. The battery detection circuit according to claim 4, wherein The resistance value of the first resistor is 10 kΩ.

6. A BMS battery system, comprising: A control unit and a plurality of serially connected batteries, characterized in that it further includes a plurality of battery detection circuits according to any one of claims 1-5, the battery detection circuits are connected in parallel to the batteries and are all communicatively connected to the control unit.

7. A BMS battery system according to claim 6, characterized in that, A second resistor is connected in series between the detection input terminal of the voltage conversion circuit and the positive electrode of the battery.

8. A BMS battery system according to claim 6, characterized in that, It further includes an auxiliary circuit for adjusting the battery power before detection.

9. The BMS battery system according to claim 8, wherein The auxiliary circuit includes a first branch, and the first branch includes: an auxiliary power supply, a first switch and a third resistor connected in series; The positive electrode of the auxiliary power supply is connected to the first switch; The negative electrode of the auxiliary power supply is grounded; The third resistor is connected in series with the battery and is connected to the positive electrode of the battery.

10. A BMS battery system according to claim 9, characterized in that, The auxiliary circuit includes a second branch, and the second branch includes: a second switch and a fourth resistor connected in series; The fourth switch is connected to the negative electrode of the auxiliary power supply; The fourth resistor is connected to the negative electrode of the battery.

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