Dual detection circuit, battery system, and vehicle

Abstract

The application discloses a double detection circuit, a battery system and a vehicle, and relates to the technical field of battery systems. The double detection circuit comprises a first detection circuit for first detection, and a second detection circuit comprising at least two sampling resistors, a voltage sampling circuit and the first detection circuit. The voltage sampling circuit is used for acquiring the voltage of the sampling resistor, and the first detection circuit is optionally connected with at least one sampling resistor to change the voltage of the sampling resistor for second detection. According to the double detection circuit, the battery system and the vehicle provided by the application, the leakage detection circuit is multiplexed, so that the leakage detection circuit is used not only for leakage detection, but also for changing the voltage of the sampling resistor in the sintering detection circuit. Whether the contactor is sintered or not can be accurately judged according to the voltage change of the sampling resistor.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a dual detection circuit, a battery system, and a vehicle. Background Technology

[0002] In electric vehicles, contactors are used to control the on / off state of high-voltage circuits. Taking a DC charging circuit as an example, if all contactors from the power battery output terminal to the charging connector are closed, the high-voltage terminals in the charging connector will be in a high-voltage energized state, posing a safety risk when not charging. Therefore, national standards require that electric vehicles in DC charging mode should have contactor adhesion monitoring (i.e., sintering detection) and alarm functions in the charging circuit.

[0003] Currently, leakage current detection and sintering detection in electric vehicles use different circuits, thus requiring the design of two voltage detection circuits, which are complex and costly. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] This invention provides a dual detection circuit, comprising:

[0006] The first detection circuit is used to perform the first detection;

[0007] The second detection circuit includes at least two sampling resistors, a voltage sampling circuit, and the first detection circuit. The voltage sampling circuit is used to acquire the voltage of the sampling resistors. The first detection circuit is optionally connected to at least one of the sampling resistors to change the voltage of the sampling resistors for the second detection.

[0008] For example, the first detection circuit is used for leakage current detection, and the second detection circuit is used for sintering detection.

[0009] For example, the first detection circuit is connected to the sampling resistor via a leakage current detection switch. When the leakage current detection switch is closed, the first detection circuit and the sampling resistor form a parallel circuit to change the voltage of the sampling resistor.

[0010] For example, at least two of the sampling resistors are connected in series, and the second detection circuit further includes two contactors. Based on the opening and closing of the two contactors, the voltage sampling circuit acquires the voltage of the at least two sampling resistors respectively to detect whether the two contactors have sintered.

[0011] For example, the two contactors include a positive contactor directly connected to the positive terminal of the power battery and a negative contactor directly connected to the negative terminal of the power battery. The second detection circuit is used to detect whether the positive contactor or the negative contactor has sintered.

[0012] When the positive contactor is tested for sintering, the negative contactor closes and the positive contactor opens.

[0013] When the detection of whether the negative contactor has sintered occurs, the positive contactor closes and the negative contactor opens.

[0014] For example, when detecting whether the positive contactor or the negative contactor has sintered, the leakage current detection switch closes and remains closed for a first predetermined time, then the leakage current detection switch opens and remains open for a second predetermined time, and the voltage sampling circuit is used to obtain the minimum value of the sampled voltage during the first predetermined time and the second predetermined time.

[0015] For example, the voltage sampling circuit is further configured to obtain the battery voltage sampling value before the leakage detection switch closes and remains closed for a first predetermined time, and to obtain the difference between the minimum sampling voltage and the battery voltage sampling value. When the difference is less than a predetermined threshold, the positive contactor or the negative contactor undergoes sintering.

[0016] For example, leakage detection is performed based on the opening and closing of the positive contactor, the negative contactor, and the leakage detection switch: when leakage detection is performed, the positive contactor and the negative contactor are disconnected, and the leakage detection switch is closed.

[0017] For example, the first detection circuit includes at least two resistors connected in series, and the first detection circuit also includes a current sampling circuit for acquiring the current of the at least two resistors connected in series.

[0018] For example, the first detection circuit is grounded.

[0019] The present invention also provides a battery system including the dual detection circuit described in any of the above claims.

[0020] The present invention also provides a vehicle including the battery system described above.

[0021] According to the dual detection circuit, battery system, and vehicle provided by the present invention, by reusing the leakage detection circuit, the leakage detection circuit is used not only for leakage detection, but also for changing the voltage of the sampling resistor in the sintering detection circuit, so as to accurately determine whether the contactor has sintered by the voltage change of the sampling resistor. Attached Figure Description

[0022] The following drawings, which are incorporated herein by reference as part of this invention, are provided for understanding the invention. The drawings illustrate embodiments of the invention and their descriptions, serving to explain the principles of the invention.

[0023] In the attached image:

[0024] Figure 1 This is a schematic diagram of a dual detection circuit according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a circuit for detecting whether a positive contactor has sintered according to an embodiment of the present invention;

[0026] Figure 3 This is a flowchart illustrating the process of detecting whether a positive electrode contactor has undergone sintering according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of a circuit for detecting whether a negative contactor has sintered according to an embodiment of the present invention.

[0028] Figure 5 This is a flowchart illustrating the process of detecting whether a negative electrode contactor has sintered according to an embodiment of the present invention.

[0029] Figure 6 This is a circuit diagram for leakage current detection according to an embodiment of the present invention;

[0030] Figure 7 This is a circuit diagram for leakage current detection according to an embodiment of the present invention.

[0031] Figure Labels

[0032] 100, power battery 200, first detection circuit

[0033] 210. Current sampling circuit; 300. Voltage sampling circuit Detailed Implementation

[0034] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0035] To fully understand the present invention, a detailed description will be set forth in the following description to illustrate the dual detection circuit, battery system, and vehicle of the present invention. It is obvious that the implementation of the present invention is not limited to the specific details familiar to those skilled in the art of battery technology. Preferred embodiments of the present invention are described in detail below; however, in addition to these detailed descriptions, the present invention may have other embodiments.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0037] Exemplary embodiments according to the present invention will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of the invention is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions is exaggerated, and the same reference numerals are used to denote the same elements, and therefore their description will be omitted.

[0038] To address the issue that current electric vehicle leakage current detection and sintering detection use different circuits, requiring the design of two voltage detection circuits, which is complex and costly, this invention provides a dual detection circuit, such as... Figure 1 As shown, it includes:

[0039] The first detection circuit 200 is used to perform the first detection;

[0040] The second detection circuit includes at least two sampling resistors, a voltage sampling circuit 300, and the first detection circuit 200. The voltage sampling circuit is used to acquire the voltage of the sampling resistors. The first detection circuit can optionally be connected to at least one of the sampling resistors to change the voltage of the sampling resistors for the second detection.

[0041] In one embodiment, the first detection circuit 200 is used for leakage current detection, and the second detection circuit is used for sintering detection.

[0042] For example, at least two of the sampling resistors are connected in series, and the second detection circuit further includes two contactors. Based on the opening and closing of the two contactors, the voltage sampling circuit acquires the voltage of the at least two sampling resistors respectively to detect whether the two contactors have sintered.

[0043] In one embodiment, the sampling resistor includes a first sampling resistor Rx+ and a second sampling resistor Rx- connected in series. The first sampling resistor Rx+ is directly connected to the positive terminal of the power battery 100, and the second sampling resistor Rx- is directly connected to the negative terminal of the power battery 100. The first sampling resistor Rx+ and the second sampling resistor Rx- have the same resistance value. Therefore, when the voltage of the power battery 100 is V... batt At that time, the voltage division of the first sampling resistor Rx+ is obtained as V through the voltage sampling circuit 300. batt / 2, the voltage division of the second sampling resistor Rx- is obtained as V through the voltage sampling circuit 300. batt / 2.

[0044] For example, the first detection circuit 200 is connected to the sampling resistor via a leakage current detection switch S0. When the leakage current detection switch is closed, the first detection circuit and the sampling resistor form a parallel circuit to change the voltage of the sampling resistor.

[0045] In one embodiment, such as Figure 1 As shown, the first detection circuit 200 includes at least two resistors R1 and R2 connected in series, and the resistance of the first detection circuit 200 is much smaller than the resistance value of the sampling resistor; for example, the resistance values ​​of resistors R1 and R2 are only 1 / 10 of the first sampling resistor Rx+. The first detection circuit 200 also includes a current sampling circuit 210 for acquiring the sampling current flowing through resistors R1 and R2, and determining whether leakage current has occurred based on the sampling current. In one embodiment, as... Figure 1 As shown, one end of the first detection circuit 200 is connected to the positive terminal of the power battery 100 via a leakage current detection switch S0, and the other end of the first detection circuit 200 is grounded (GND). Since both the first detection circuit 200 and the first sampling resistor Rx+ are connected to the positive terminal of the power battery 100, the opening and closing of the leakage current detection switch S0 can control whether the first detection circuit 200 and the first sampling resistor Rx+ form a parallel circuit: when the leakage current detection switch S0 is closed, the first detection circuit 200 and the first sampling resistor Rx+ form a parallel circuit; when the leakage current detection switch S0 is open, the first detection circuit 200 does not form a parallel circuit with the first sampling resistor Rx+.

[0046] In one embodiment, since the second detection circuit (sintering detection circuit) shares a common ground with the vehicle, false sintering may occur during sintering detection. By reusing the first detection circuit (leakage detection circuit), the false sintering situation can be avoided because the first detection circuit's GND is connected during the sintering detection process.

[0047] For example, the two contactors include a positive contactor S1 directly connected to the positive terminal of the power battery and a negative contactor S2 directly connected to the negative terminal of the power battery. The second detection circuit is used to detect whether the positive contactor S1 or the negative contactor S2 has sintered: when the positive contactor S1 is detected to have sintered, the negative contactor S2 is closed and the positive contactor S1 is open; when the negative contactor S2 is detected to have sintered, the positive contactor S1 is closed and the negative contactor S2 is open.

[0048] Furthermore, when detecting whether the positive contactor S1 or the negative contactor S2 has sintered, the leakage current detection switch S0 closes and remains closed for a first predetermined time, and then the leakage current detection switch S0 opens and remains open for a second predetermined time. The voltage sampling circuit 300 is used to obtain the minimum value of the sampled voltage during the first predetermined time and the second predetermined time.

[0049] Furthermore, the difference between the minimum value of the sampled voltage and the voltage value of the power battery is obtained. When the difference is less than a predetermined threshold, the positive contactor S1 or the negative contactor S2 undergoes sintering.

[0050] In one embodiment, refer to Figure 2 and Figure 3 When the positive contactor S1 is detected to be sintered, the negative contactor S2 closes and the positive contactor S1 opens. Next, the leakage detection switch S0 is activated and remains closed for a first predetermined time (e.g., 500ms), continuously sampling the voltage of the second sampling resistor Rx- during this time. When the positive contactor S1 is not sintered, the first detection circuit 200 and the first sampling resistor Rx+ form a parallel circuit. Since the resistance of the first detection circuit 200 is much smaller than the resistance of the first sampling resistor Rx+, the total resistance of the parallel circuit will be much smaller than the resistance of the second sampling resistor Rx-. Therefore, the voltage value obtained by sampling the second sampling resistor Rx- will be close to the voltage value V of the power battery. batt When the positive contactor S1 undergoes sintering, it short-circuits the first sampling resistor Rx+ and the first detection circuit 200. At this time, the voltage value obtained by sampling the second sampling resistor Rx- is the voltage value V of the power battery. battNext, the leakage current detection switch S0 is disconnected, and voltage sampling of the second sampling resistor Rx- continues. The leakage current detection switch S0 remains disconnected for a second predetermined time (e.g., 1000ms), and voltage sampling of the second sampling resistor Rx- continues during this second predetermined time. When the positive contactor S1 has not sintered, the first sampling resistor Rx+ and the second sampling resistor Rx- form a voltage divider circuit. At this time, the voltage value obtained by sampling the second sampling resistor Rx- will be half the voltage value of the power battery (V). batt / 2); When the positive contactor S1 undergoes sintering, the positive contactor S1 short-circuits the first sampling resistor Rx+. At this time, the voltage value obtained by sampling the voltage of the second sampling resistor Rx- is the voltage value V of the power battery. batt Since the voltage sampling circuit 300 is used to obtain the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min Therefore, when the positive contactor S1 has not sintered, the minimum value of the sampled voltage V during the first predetermined time and the second predetermined time is... min It should be half the voltage value of the power battery (V). batt / 2); When the positive contactor S1 undergoes sintering, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min It should be the voltage value V of the power battery. batt .

[0051] In one embodiment, the minimum value V of the above-mentioned sampling voltage is obtained. min With power battery voltage value V batt The difference. Since the positive contactor S1 has not undergone sintering, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time. min It should be half the voltage value of the power battery (V). batt / 2), therefore the minimum sampling voltage V min With power battery voltage value V batt The absolute value of the difference is also V. batt / 2. Due to the sintering of the positive contactor S1, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min It should be the voltage value V of the power battery. batt Therefore, the minimum sampling voltage V min With power battery voltage value V batt The difference is 0. Therefore, when the minimum sampled voltage V... min With power battery voltage value V batt When the difference is less than a predetermined threshold (e.g., 30V), it can be determined that the positive contactor S1 has sintered.

[0052] In one embodiment, refer to Figure 4 and Figure 5 When the negative contactor S2 is detected to be sintered, the positive contactor S1 closes and the negative contactor S2 opens. Next, the leakage detection switch S0 is activated and remains closed for a first predetermined time (e.g., 500ms), continuously sampling the voltage of the first sampling resistor Rx+ during this time. When the negative contactor S2 is not sintered, the first detection circuit 200 and the first sampling resistor Rx+ form a parallel circuit. Since the resistance of the first detection circuit 200 is much smaller than the resistance of the first sampling resistor Rx+, the total resistance of the parallel circuit will be much smaller than the resistance of the second sampling resistor Rx-. Therefore, the voltage value obtained by sampling the first sampling resistor Rx+ will be close to 0. When the negative contactor S2 is sintered, it short-circuits the second sampling resistor Rx-. The voltage value obtained by sampling the first sampling resistor Rx+ is then the voltage value V of the power battery. batt Next, the leakage current detection switch S0 is disconnected, and the voltage of the first sampling resistor Rx+ is continuously sampled. The leakage current detection switch S0 remains disconnected for a second predetermined time (e.g., 1000ms), and the voltage of the first sampling resistor Rx+ is continuously sampled during this second predetermined time. When the negative contactor S2 has not sintered, the first sampling resistor Rx+ and the second sampling resistor Rx- form a voltage divider circuit. At this time, the voltage value obtained by sampling the second sampling resistor Rx- will be half the voltage value of the power battery (V). batt / 2); When the negative contactor S2 sinters, it short-circuits the second sampling resistor Rx-. At this time, the voltage value obtained by sampling the first sampling resistor Rx+ is the voltage value V of the power battery. batt Since the voltage sampling circuit 300 is used to obtain the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min Therefore, when the negative contactor S2 has not sintered, the minimum value of the sampled voltage V during the first predetermined time and the second predetermined time is... min It should be close to 0; when the negative contactor S2 undergoes sintering, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min It should be the voltage value V of the power battery. batt .

[0053] In one embodiment, the minimum value V of the above-mentioned sampling voltage is obtained. min With power battery voltage value V batt The difference. Since the negative contactor S2 has not undergone sintering, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time. min The sampled voltage is close to 0, therefore the minimum value V is... min With power battery voltage value V battThe absolute value of the difference is close to V batt Because the negative contactor S2 undergoes sintering, the minimum value V of the sampled voltage during the first predetermined time and the second predetermined time period. min It should be the voltage value V of the power battery. batt Therefore, the minimum sampling voltage V min With power battery voltage value V batt The difference is 0. Therefore, when the minimum sampled voltage V... min With power battery voltage value V batt When the difference is less than a predetermined threshold (e.g., 30V), it can be determined that the negative contactor S2 has sintered.

[0054] In one embodiment, leakage detection is performed when the leakage detection switch S0 is closed and both the positive contactor S1 and the negative contactor S2 are open. The leakage detection method of this invention measures the insulation resistance between the vehicle's high voltage and ground. The detection point is connected to the high voltage positive or negative terminal or the middle of the battery pack, and the principle employed is the DC signal injection method.

[0055] Reference Figure 6 and Figure 7 As shown, the ground resistance Rx is the parallel connection of the high-voltage positive and negative resistances Rx+ and Rx-, and HV is the vehicle high voltage. Voltmeter V1 is used to collect the circuit power supply voltage (terminal voltage), and voltmeter V2 is used to collect the circuit current (calculated by sampling the voltage value across the fourth resistor R4). Given resistors R3 and R4, the insulation impedance Rx (Rx+ / / Rx-) can be calculated. To eliminate the influence of the battery pack voltage on the circuit, the external circuit switches CS1 and CS2 to switch the power chip back and forth, thus changing the direction of the circuit current between I1 and I2.

[0056] In the forward direction: (U1+HV) / I1-(R1+R2)=Rx ①

[0057] In the reverse direction: (U2-HV) / I2-(R1+R2)=Rx ②

[0058] From ① + ②, we can conclude:

[0059] U1+U2 / (I1+I2) - (R1+R2)= 2Rx ③

[0060] After sampling the loop, when calculating the resistance, since the loop currents I1 and I2 are directional, the calculation formula is:

[0061] (U1+U2) / |I1-I2| - (R1+R2) = Rx ④

[0062] U1 and U2 are the voltage values ​​collected by V1 when switching power supplies.

[0063] The present invention also provides a battery system including the dual detection circuit described above.

[0064] The present invention also provides a vehicle including the battery system described above.

[0065] According to the dual detection circuit, battery system, and vehicle provided by the present invention, by reusing the leakage detection circuit, the leakage detection circuit is used not only for leakage detection, but also for changing the voltage of the sampling resistor in the sintering detection circuit, so as to accurately determine whether the contactor has sintered by the voltage change of the sampling resistor.

[0066] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual detection circuit, characterized in that, include: The first detection circuit is used for leakage current detection; The second detection circuit, used for sintering detection, includes at least two sampling resistors, a voltage sampling circuit, and the first detection circuit. The voltage sampling circuit is used to acquire the voltage of the sampling resistors. The first detection circuit is selectively connected to at least one of the sampling resistors via a leakage current detection switch. When the leakage current detection switch is closed, the first detection circuit and the sampling resistors form a parallel circuit to change the voltage of the sampling resistors for sintering detection.

2. The dual detection circuit as described in claim 1, characterized in that, At least two of the sampling resistors are connected in series, and the second detection circuit further includes two contactors. Based on the opening and closing of the two contactors, the voltage sampling circuit acquires the voltage of the at least two sampling resistors respectively to detect whether the two contactors have sintered.

3. The dual detection circuit as described in claim 2, characterized in that, The two contactors include a positive contactor directly connected to the positive terminal of the power battery and a negative contactor directly connected to the negative terminal of the power battery. The second detection circuit is used to detect whether the positive contactor or the negative contactor has sintered. When the positive contactor is tested for sintering, the negative contactor closes and the positive contactor opens. When the detection of whether the negative contactor has sintered occurs, the positive contactor closes and the negative contactor opens.

4. The dual detection circuit as described in claim 3, characterized in that, When detecting whether the positive or negative contactor has sintered, the leakage current detection switch closes and remains closed for a first predetermined time, then the leakage current detection switch opens and remains open for a second predetermined time. The voltage sampling circuit is used to obtain the minimum value of the sampled voltage during the first and second predetermined times.

5. The dual detection circuit as described in claim 4, characterized in that, The difference between the minimum value of the sampled voltage and the voltage value of the power battery is obtained. When the difference is less than a predetermined threshold, the positive contactor or the negative contactor undergoes sintering.

6. The dual detection circuit as described in claim 3, characterized in that, Leakage detection is performed based on the opening and closing of the positive contactor, the negative contactor, and the leakage detection switch: when leakage detection is performed, the positive contactor and the negative contactor are disconnected, and the leakage detection switch is closed.

7. The dual detection circuit as described in claim 1, characterized in that, The first detection circuit includes at least two resistors connected in series, and the first detection circuit also includes a current sampling circuit for acquiring the current of the at least two resistors connected in series.

8. The dual detection circuit as described in claim 1, characterized in that, The first detection circuit is grounded.

9. A battery system, characterized in that, Includes the dual detection circuit according to any one of claims 1 to 8.

10. A vehicle, characterized in that, Includes the battery system as described in claim 9.

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