A power battery system state detection device and method

Abstract

This invention provides a power battery system state detection device and method, including a first sampling circuit, a second sampling circuit, a first arithmetic unit, and a control unit (MCU). The first sampling circuit samples the potential V1 of the positive terminal of the battery module; the second sampling circuit samples the potential V2 of the load circuit input terminal; the first arithmetic unit performs calculations based on the sampled values ​​of potential V1 and potential V2 to obtain the ratio N of the sampled values ​​of potential V2 and potential V1; the control unit (MCU) determines whether the contacts of the switching devices in the main power supply circuit and / or the pre-charge circuit are stuck together based on the ratio N of the sampled values ​​of potential V2 and potential V1 when the main power supply circuit and the pre-charge circuit are disconnected. This invention can detect whether the switching devices in the main power supply circuit and the pre-charge circuit are stuck together using simple logic circuits, and the detection results are accurate, the detection process is simple, and the solution is easy to implement.

Description

Technical Field

[0001] This invention relates to the field of automotive power battery system technology, and more specifically, to a power battery system state detection device and method. Background Technology

[0002] Electric vehicle battery systems are connected to numerous capacitive load circuits. These capacitive loads are approximately short-circuited when momentarily switched on. To control this and reduce damage from transient overcurrents, pre-charge protection is needed for these capacitive load circuits. For example... Figure 1 The diagram illustrates the principle of pre-charging capacitive loads in a current electric vehicle power battery system. A main positive relay S1 and a main auxiliary relay S3 are installed at the positive and negative terminals of the main power supply circuit of the power battery system, respectively. The on / off state of the main positive relay S1 and the main auxiliary relay S3 is controlled by an MCU to achieve on / off control of the main power supply circuit. A pre-charging circuit is connected in parallel to the main positive relay S1. The pre-charging circuit includes a pre-charge relay S2 connected in series and a charging resistor R. When the main positive relay S1 is open, the MCU controls the pre-charge relay S2 to turn on in advance, thus pre-charging the capacitive load circuit before the main positive relay S1 is turned on. After pre-charging is complete, the main positive relay S1 is then turned on, preventing overcurrent at the moment of connection and thus protecting the power battery system.

[0003] Currently, the industry cannot fully distinguish between the sticking of the main positive relay S1 and the pre-charge relay S2 before high voltage is applied. This necessitates disassembling the battery pack and the BDU (Battery Energy Distribution Unit) containing both the main positive relay S1 and the pre-charge relay S2 for troubleshooting, significantly hindering problem diagnosis. Failure to detect the sticking of the main positive relay S1 and / or the pre-charge relay S2 in a timely manner may damage the power battery system. For example, if the main positive relay S1 cannot effectively disconnect, the high-voltage load circuit cannot be effectively de-energized; if the pre-charge relay S2 cannot effectively disconnect, after the main power supply circuit is connected, the pre-charge circuit will be under constant high current flow under normal load circuit conditions, causing the pre-charge resistor R to overheat, resulting in excessively high power battery system temperature and potentially a dangerous situation.

[0004] Therefore, it is necessary to design a scheme that can quickly distinguish whether the main positive relay and / or precharge relay are stuck together. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing a power battery system state detection device and method. It can detect whether the switching devices in the main power supply circuit and the pre-charging circuit are stuck together through a simple logic circuit. Moreover, the detection results are accurate, the detection process is simple, and the solution is easy to implement.

[0006] According to a first aspect of the present invention, a power battery system state detection device is provided, comprising a first sampling circuit, a second sampling circuit, a first arithmetic unit, and a control unit (MCU).

[0007] The sampling point of the first sampling circuit is set at the common node of the main power supply circuit, the pre-charging circuit and the positive terminal of the battery module. The output terminal of the first sampling circuit is connected to the first input terminal of the first arithmetic unit and is used to sample the potential V1 of the positive terminal of the battery module.

[0008] The sampling point of the second sampling circuit is set at the common node of the input terminals of the main power supply circuit, the pre-charge circuit and the load circuit. The output terminal of the second sampling circuit is connected to the second input terminal of the first arithmetic unit and is used to sample the potential V2 of the input terminal of the load circuit.

[0009] The output of the first arithmetic unit is connected to the first input of the control unit MCU, and is used to perform calculations based on the sampled values ​​of potential V1 and potential V2 to obtain the ratio N of the sampled values ​​of potential V2 and potential V1.

[0010] The control unit MCU is used to determine whether the contacts of the switching devices in the main power supply circuit and / or pre-charge circuit are stuck together based on the ratio N of the sampled values ​​of potential V2 and potential V1 when the main power supply circuit and pre-charge circuit are disconnected.

[0011] Based on the above technical solution, the present invention can also be improved as follows.

[0012] Optionally, a first switching unit U2 is connected in series in the second sampling circuit. The control terminal of the first switching unit U2 is connected to the first output terminal of the control unit MCU, and is used to control the on / off state of the second sampling circuit through the control unit MCU.

[0013] Optionally, the first sampling circuit includes voltage divider resistors R1 and R3, which are connected in series. One end of voltage divider resistor R1 away from voltage divider resistor R3 is connected to the common node of the main power supply circuit, the pre-charge circuit and the positive terminal of the battery module. The other end of voltage divider resistor R3 away from voltage divider resistor R1 is grounded. The common terminal of voltage divider resistors R1 and R3 serves as the output terminal of the first sampling circuit, outputting the potential sampling value V5 obtained after converting potential V1.

[0014] The second sampling circuit includes voltage divider resistors R2 and R4, which are connected in series. One end of voltage divider resistor R2 away from voltage divider resistor R4 is connected to the common node of the input terminals of the main power supply circuit, the pre-charge circuit, and the load circuit. The other end of voltage divider resistor R4 away from voltage divider resistor R2 is grounded. The common terminal of voltage divider resistors R2 and R4 serves as the output terminal of the second sampling circuit, outputting the potential sampling value V6 obtained after converting potential V2.

[0015] Optionally, the first arithmetic unit is a divider U1. The first input terminal of the divider U1 is connected to the common terminal of voltage divider resistors R1 and R3. The second input terminal of the divider U1 is connected to the common terminal of voltage divider resistors R2 and R4. The output terminal of the divider U1 is connected to the first input terminal of the control unit MCU. It is used to divide the potential sample value V6 and the potential sample value V5 to obtain and output the ratio N of the potential sample value V6 and the potential sample value V5.

[0016] Optionally, the control unit MCU is used to classify and determine the ratio N of the potential sample value V6 and the potential sample value V5:

[0017] When the ratio N is 0, it is determined that the contacts of the switching devices in the main power supply circuit and the pre-charge circuit have not stuck together.

[0018] When the ratio N is 1, it is determined that the contacts of the switching devices in the main power supply circuit are stuck together.

[0019] When the ratio N is between 0 and 1, it is determined that the switching device contacts in the pre-charge circuit are stuck together.

[0020] Optionally, the detection device further includes a second arithmetic unit and a second switching unit U4;

[0021] The first input terminal of the second arithmetic unit is connected to the output terminal of the first arithmetic unit, the second input terminal of the second arithmetic unit is connected to the control unit MCU, and the output terminal of the second arithmetic unit is connected to the control terminal of the second switching unit U4. It is used to compare the ratio N of the sampled values ​​of potential V2 and potential V1 with the reference value when the main power supply circuit is off and the pre-charging circuit is on, and control the on / off state of the second switching unit U4 according to the comparison result.

[0022] The input terminal of the second switching unit U4 is connected to the operating power supply, and the output terminal of the second switching unit U4 is connected to the second input terminal of the control unit MCU, which is used to feed the comparison result back to the control unit MCU;

[0023] The control unit (MCU) is used to output the reference value and also to determine whether precharging is complete based on the comparison result.

[0024] Optionally, the second arithmetic unit is a comparator U3, which is used to compare the ratio N with the reference value. When the ratio N is greater than the reference value, the comparator U3 outputs a high level to control the second switching unit U4 to turn on.

[0025] Optionally, a main negative switch device is connected in series between the negative terminal of the battery module and the output terminal of the load circuit. The detection device also includes a third switch unit U5 and a third arithmetic unit.

[0026] One end of the third switching unit U5 is connected to the common node of the main negative switching device and the output terminal of the load circuit, the other end of the third switching unit U5 is connected to the first input terminal of the first arithmetic unit, and the control terminal of the third switching unit U5 is connected to the control unit MCU.

[0027] The first input terminal of the third arithmetic unit is connected to the common node of the main negative switch device and the output terminal of the load circuit. The second input terminal of the third arithmetic unit is connected to the common node of the main negative switch device and the negative terminal of the battery module. The output terminal of the third arithmetic unit is connected to the third input terminal of the control unit MCU. The third arithmetic unit is used to sample the potentials V3 and V4 at both ends of the contacts when the main negative switch device is open, and compare the potentials V3 and V4.

[0028] The control unit MCU is used to determine whether the contacts of the main negative switching device are stuck together based on the comparison result of potential V3 and potential V4.

[0029] When potential V3 is equal to potential V4, it is determined that the contacts of the main negative switch device are stuck together.

[0030] When potentials V3 and V4 are not equal, it is determined that the contacts of the main negative switch device are not stuck together.

[0031] Optionally, the first switching unit U2, the second switching unit U4, and / or the third switching unit U5 are opto-isolating switches.

[0032] According to a second aspect of the present invention, a method for detecting the state of a power battery system is provided, comprising:

[0033] The system controls the connection between the main power supply circuit and the load circuit input terminal to be disconnected, the connection between the pre-charge circuit and the load circuit input terminal to be disconnected, and the connection between the load circuit output terminal and the negative terminal of the battery module to be connected. It samples the potential V1 of the positive terminal of the battery module, obtains a potential sampling value V5 after current limiting, samples the potential V2 of the load circuit input terminal, obtains a potential sampling value V6 after current limiting, and calculates the ratio N of the potential sampling value V6 to the potential sampling value V5. When the ratio N is 0, it is determined that the switching device contacts in both the main power supply circuit and the pre-charge circuit are not stuck; when the ratio N is 1, it is determined that the switching device contacts in the main power supply circuit are stuck; when the ratio N is between 0 and 1, it is determined that the switching device contacts in the pre-charge circuit are stuck.

[0034] If it is determined that the contacts of the switching devices in the main power supply circuit and the pre-charging circuit are not stuck, the connection between the pre-charging circuit and the input terminal of the load circuit is turned on; the real-time ratio N is compared with the reference value, and the pre-charging is determined to be completed based on the comparison result.

[0035] Optionally, the method further includes detecting whether the switching devices between the load circuit output terminal and the negative terminal of the battery module are stuck together, including:

[0036] Disconnect the main power supply circuit from the load circuit input terminal, disconnect the pre-charge circuit from the load circuit input terminal, disconnect the load circuit output terminal from the battery module negative terminal, and apply the potential sampling value V5 of the battery module positive terminal to the load circuit output terminal;

[0037] The potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are detected and compared. When the potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are equal, it is determined that the switching device between the output terminal of the load circuit and the negative terminal of the battery module is stuck. When the potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are not equal, it is determined that the switching device between the output terminal of the load circuit and the negative terminal of the battery module is not stuck.

[0038] This invention provides a power battery system state detection device, method, electronic device, and storage medium. Before the load circuit is powered on, a simple hardware logic circuit can be used to detect whether the contacts of the switching devices in the main power supply circuit and the pre-charging circuit are stuck. It can also detect the completion of pre-charging. The detection results are accurate, the detection process is simple, the solution is easy to implement, and the cost is low, thus maintaining the safety of the power battery system. Attached Figure Description

[0039] Figure 1 A schematic diagram of the composition of a power battery system in the prior art;

[0040] Figure 2A schematic diagram of the circuit composition of a power battery system state detection device provided by the present invention;

[0041] Figure 3 The present invention provides a flowchart of a power battery system state detection method. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] Figure 2 The circuit schematic diagram of the power battery system state detection device provided by the present invention is as follows: Figure 2 As shown, the detection device provided by the present invention includes a first sampling circuit, a second sampling circuit, a first arithmetic unit, and a control unit (MCU).

[0044] The sampling point of the first sampling circuit is set at the common node of the main power supply circuit, the pre-charging circuit and the positive terminal of the battery module. The output terminal of the first sampling circuit is connected to the first input terminal of the first arithmetic unit and is used to sample the potential V1 of the positive terminal of the battery module.

[0045] The sampling point of the second sampling circuit is set at the common node of the input terminals of the main power supply circuit, the pre-charge circuit and the load circuit. The output terminal of the second sampling circuit is connected to the second input terminal of the first arithmetic unit and is used to sample the potential V2 of the input terminal of the load circuit.

[0046] The output of the first arithmetic unit is connected to the first input of the control unit MCU, and is used to perform calculations based on the sampled values ​​of potential V1 and potential V2 to obtain the ratio N of the sampled values ​​of potential V2 and potential V1.

[0047] The control unit MCU is used to determine whether the contacts of the switching devices in the main power supply circuit and / or pre-charge circuit are stuck together based on the ratio N of the sampled values ​​of potential V2 and potential V1 when the main power supply circuit and pre-charge circuit are disconnected.

[0048] It is understood that the main power supply circuit and the pre-charge circuit are connected in parallel, both connected to the positive terminal of the battery module and the input terminal of the high-voltage load circuit. Both the main power supply circuit and the pre-charge circuit are equipped with controllable switching devices. For example, the main power supply circuit includes a main positive relay K1, which is controlled by the control unit MCU to control the on / off state of the main power supply circuit. The pre-charge circuit includes a pre-charge relay K2 and a pre-charge resistor R connected in series. The pre-charge relay K2 is controlled by the control unit MCU to control the on / off state of the pre-charge circuit, while the pre-charge resistor R limits the pre-charge voltage. A main negative relay K3 is also connected in series at the negative terminal of the battery module. By controlling the on / off state of the main negative relay K3, the connection between the output terminal of the load circuit and the negative terminal of the battery module can be controlled. Based on this power battery system structure, the power battery system state detection device provided in this embodiment can directly determine whether the main positive relay K1 and / or the pre-charge relay K2 are stuck together, and specifically which one is stuck, by using the ratio N before the load circuit is powered on, i.e., when the main positive relay K1 and the pre-charge relay K2 are disconnected. This embodiment can detect whether the switching devices in the main power supply circuit and the pre-charge circuit are stuck together using a simple hardware logic circuit. The detection results are accurate, the detection process is simple, and the solution is easy to implement, thus maintaining the safety of the power battery system.

[0049] In one possible embodiment, a first switching unit U2 is connected in series in the second sampling circuit. The control terminal of the first switching unit U2 is connected to the first output terminal of the control unit MCU, and is used to control the on / off state of the second sampling circuit through the control unit MCU.

[0050] It is understood that the first switching unit U2 can preferably use a high-low voltage isolated switch. For example, in this embodiment, an optocoupler is preferably used as the first switching unit U2. The control unit MCU sends a control signal to the primary of the optocoupler through the port GPIO1 to control the channel between the second sampling circuit and the second input terminal of the first arithmetic unit, thereby controlling the on and off of the second sampling circuit.

[0051] In one possible embodiment, the first sampling circuit includes voltage divider resistors R1 and R3 connected in series. One end of voltage divider resistor R1 away from voltage divider resistor R3 is connected to the common node of the main power supply circuit, the pre-charge circuit and the positive terminal of the battery module. The other end of voltage divider resistor R3 away from voltage divider resistor R1 is grounded. The common terminal of voltage divider resistors R1 and R3 serves as the output terminal of the first sampling circuit, outputting the potential sampling value V5 obtained after converting potential V1.

[0052] It is understandable that the voltage divider resistors R1 and R3, connected in series, reduce the voltage of the sampling point V1 at the positive terminal of the battery module. After current limiting and voltage reduction by the voltage divider resistor R1, the potential sample value V5 is output from the common node of the voltage divider resistors R1 and R3. By setting the parameters of the voltage divider resistors R1 and R3, the expected voltage reduction amplitude of the potential sample value V5 can be obtained. The output voltage of the positive terminal of the battery module is usually high, for example, the commonly used high voltage output of the vehicle power battery module is 400V, while the input voltage amplitude range of the arithmetic unit is generally a few volts to tens of volts. The potential sample value V5, as the input value of the first arithmetic unit in the subsequent circuit, cannot have too high a voltage and current. Therefore, by using the cooperation of the voltage divider resistors R1 and R3, the sampled output voltage (i.e., potential V1) of the positive terminal of the battery module is reduced and sampled to obtain a lower amplitude potential sample value V5, which is then input to the first arithmetic unit for calculation.

[0053] like Figure 2 As shown, similarly, the second sampling circuit includes voltage divider resistors R2 and R4, which are connected in series. One end of voltage divider resistor R2 away from voltage divider resistor R4 is connected to the common node of the input terminals of the main power supply circuit, the pre-charge circuit, and the load circuit. The other end of voltage divider resistor R4 away from voltage divider resistor R2 is grounded. The common terminal of voltage divider resistors R2 and R4 serves as the output terminal of the second sampling circuit, outputting the potential sampling value V6 obtained after converting potential V2.

[0054] As can be understood, similar to the principle of the first sampling circuit, the voltage (i.e., potential V2) at the input terminal of the sampled load circuit is stepped down and sampled using the cooperation of voltage divider resistors R2 and R4 to obtain a lower amplitude potential sample value V6, which is then input to the first arithmetic unit for calculation. In this embodiment, the voltage divider resistors R1 to R4 are pre-designed resistors. The main purpose of voltage divider resistors R1 and R2 is current-limiting sampling, while the main purpose of voltage divider resistors R3 and R4 is to output a stable voltage. In a specific application scenario, the resistance values ​​of voltage divider resistors R1 and R2 can be 36KΩ, and the resistance values ​​of R3 and R4 can be 4.7KΩ (system voltage 400V). The voltages at potential sample values ​​V5 and V6 can be stabilized within the range specified by the first arithmetic unit due to the resistor voltage division.

[0055] In one possible embodiment, the first arithmetic unit is a divider U1. The first input terminal of the divider U1 is connected to the common terminal of voltage divider resistors R1 and R3, the second input terminal of the divider U1 is connected to the common terminal of voltage divider resistors R2 and R4, and the output terminal of the divider U1 is connected to the first input terminal of the control unit MCU. The divider U1 is used to divide the potential sample value V6 and the potential sample value V5 to obtain and output the ratio N of the potential sample value V6 and the potential sample value V5.

[0056] It is understandable that by dividing the potential sample value V6 and the potential sample value V5 by the divider U1, a ratio N with a range of [0,1] can be obtained. Based on the magnitude of the ratio N, the real-time on / off status of the main positive relay K1 and the precharge relay K2 can be determined.

[0057] In one possible embodiment, the control unit MCU is used to classify and determine the ratio N of the potential sample value V6 and the potential sample value V5:

[0058] When the ratio N is 0, it is determined that the contacts of the switching devices in the main power supply circuit and the pre-charge circuit have not stuck together.

[0059] When the ratio N is 1, it is determined that the contacts of the switching devices in the main power supply circuit are stuck together.

[0060] When the ratio N is between 0 and 1, it is determined that the switching device contacts in the pre-charge circuit are stuck together.

[0061] It is understandable that, such as Figure 2 As shown in the circuit diagram, due to the presence of the pre-charging resistor R in the pre-charging circuit, when the main power supply circuit is disconnected and the pre-charging circuit is connected, the voltage drop effect of the pre-charging resistor R will ensure that the potential V2 is less than the potential V1, and the potential V2 is not zero. Therefore, dividing the proportionally reduced potential sample value V6 sampled in this state by the potential sample value V5, the resulting ratio N should be between 0 and 1. When both the main power supply circuit and the pre-charging circuit are disconnected, the potential V2 can be considered zero (or equal to the negative terminal voltage of the battery module). Therefore, dividing the proportionally reduced potential sample value V6 sampled in this state by the potential sample value V5, the resulting ratio N is 0. When the main power supply circuit is connected, regardless of whether the pre-charging circuit is on or off, the potential V2 is equal to the potential V1, and the ratio in this case is 1. Based on the above principle, when both the main positive relay K1 and the precharge relay K2 are disconnected by the control logic, the magnitude of the ratio N obtained by the divider U1 can be used to determine whether the main positive relay K1 and the precharge relay K2 are stuck together, and which one is stuck together.

[0062] In one possible embodiment, the detection device further includes a second arithmetic unit and a second switching unit U4.

[0063] The first input terminal of the second arithmetic unit is connected to the output terminal of the first arithmetic unit, the second input terminal of the second arithmetic unit is connected to the control unit MCU, and the output terminal of the second arithmetic unit is connected to the control terminal of the second switching unit U4. It is used to compare the ratio N of the sampled values ​​of potential V2 and potential V1 with the reference value when the main power supply circuit is disconnected and the pre-charging circuit is on, and control the on / off state of the second switching unit U4 according to the comparison result.

[0064] Understandably, the second processing unit compares the ratio N with a reference value and determines whether pre-charging is complete based on the comparison result. This applies to scenarios where the main positive relay K1 and the pre-charge relay K2 are not stuck together, and pre-charging of the load circuit is required before system power-on. The ratio N reflects the change in potential V2; therefore, by setting a reference value corresponding to the potential V2 in the pre-charging complete state, it can be determined that the pre-charging of the load circuit is complete when the ratio N matches the set reference value.

[0065] In a preferred embodiment, the second arithmetic unit employs a comparator U3, which is used to compare the ratio N with the reference value. When the ratio N is greater than the reference value, the comparator U3 outputs a high level, thereby controlling the second switching unit U4 to turn on.

[0066] The input terminal of the second switching unit U4 is connected to the operating power supply, and the output terminal of the second switching unit U4 is connected to the second input terminal of the control unit MCU, which is used to feed back the comparison result to the control unit MCU.

[0067] The second switching unit U4 can employ a switching element that isolates the input signal from the output signal, thereby isolating the second arithmetic unit from the control unit MCU. For example... Figure 2 As shown, the second switching unit U4 in this embodiment is implemented using an optocoupler. The output signal of the second operational unit is input to the primary side of this optocoupler. When this output signal is high, the secondary side of the optocoupler is turned on, and the voltage of the operating power supply is input to the second input terminal of the control unit MCU to realize the signal feedback that the pre-charging is complete.

[0068] The control unit MCU can set a reference value representing the pre-charging completion status. The control unit MCU outputs the reference value to the second arithmetic unit (i.e., comparator U3) through port GPIO3. It is also used to determine whether pre-charging is complete based on the comparison result. For example, when comparator U3 outputs a high level, the control unit MCU determines that pre-charging is complete; otherwise, it determines that pre-charging is not complete.

[0069] In one possible embodiment, a main negative switching device is connected in series between the negative terminal of the battery module and the output terminal of the load circuit. In this embodiment, for example... Figure 2 As shown, the main negative switching device uses a main negative relay K3. Before judging the status of the main positive relay K1 and the precharge relay K2, the status of the main negative relay K3 can be judged first to determine whether the main negative relay K3 is stuck. Therefore, the detection device also includes a third switching unit U5 and a third arithmetic unit.

[0070] One end of the third switching unit U5 is connected to the common node of the main negative relay K3 and the output of the load circuit, the other end of the third switching unit U5 is connected to the first input terminal of the first arithmetic unit (i.e., the divider U1), and the control terminal of the third switching unit U5 is connected to the port GPIO2 of the control unit MCU.

[0071] It is understandable that the potential at the first input terminal of the first arithmetic unit (i.e., divider U1) is equivalent to the potential of the common node of voltage divider resistors R1 and R3, i.e., the potential sampling value V5. Here, the potential sampling value V5 is applied to the common node of the main negative relay K3 and the load circuit output terminal through the third switching unit U5. After the control unit MCU controls the third switching unit U5 to turn on, as... Figure 2 As shown, potential V3 can be obtained here, which is equal to the potential sampling value V5. In order to achieve electrical isolation between the control unit MCU and this sampling point (i.e., the common node of the main negative relay K3 and the output of the load circuit), the third switching unit U5 preferably adopts an optocoupler.

[0072] The third arithmetic unit can preferably use comparator U6. The first input terminal of comparator U6 is connected to the common node of the main negative relay K3 and the output terminal of the load circuit. The second input terminal of comparator U6 is connected to the common node of the main negative relay K3 and the negative terminal of the battery module. The output terminal of comparator U6 is connected to the third input terminal of the control unit MCU. The third arithmetic unit is used to sample the potentials V3 (corresponding to the common node of the main negative relay K3 and the output terminal of the load circuit) and V4 (corresponding to the common node of the main negative relay K3 and the negative terminal of the battery module) at both ends of its contacts when the main negative relay K3 is open, and compare potentials V3 and V4.

[0073] The control unit MCU is used to determine whether the contacts of the main negative relay K3 are stuck based on the comparison result of potential V3 and potential V4. The specific judgment logic is as follows:

[0074] When potential V3 is equal to potential V4, it is determined that the contacts of the main negative relay K3 are stuck.

[0075] When potential V3 and potential V4 are not equal, it is determined that the contacts of the main negative relay K3 are not stuck.

[0076] like Figure 3 As shown, based on the circuit structures of the above embodiments, this embodiment also provides a method for detecting the state of a power battery system, including the following steps:

[0077] Detection of contact adhesion between main positive relay K1 and / or precharge relay K2: The connection between the main power supply circuit and the load circuit input terminal (i.e., main positive relay K1) is disconnected; the connection between the precharge circuit and the load circuit input terminal (i.e., precharge relay K2) is disconnected; the connection between the load circuit output terminal and the battery module negative terminal (i.e., main negative relay K3) is connected; the potential V1 of the battery module positive terminal is sampled, and the potential sampling value V5 is obtained after current limiting and voltage reduction; the potential V2 of the load circuit input terminal is sampled, and the potential sampling value V5 is obtained after current limiting and voltage reduction. Obtain the potential sampling value V6, and calculate the ratio N of the potential sampling value V6 to the potential sampling value V5. When the ratio N is 0, it is determined that the contacts of the switching devices (main positive relay K1 and precharge relay K2) in the main power supply circuit and the precharge circuit are not stuck. When the ratio N is 1, it is determined that the contacts of the switching device (i.e., the main positive relay K1) in the main power supply circuit are stuck. When the ratio N is between 0 and 1, it is determined that the contacts of the switching device (i.e., the precharge relay K2) in the precharge circuit are stuck.

[0078] Pre-charge completion detection: If it is determined that the contacts of the switching devices (main positive relay K1 and pre-charge relay K2) in the main power supply circuit and the pre-charge circuit are not stuck, the connection between the pre-charge circuit and the load circuit input terminal (i.e., pre-charge relay K2) is turned on; the real-time ratio N is compared with the reference value indicating that pre-charge is complete, and the pre-charge is determined to be complete based on the comparison result. When the ratio N is greater than the reference value, the pre-charge is determined to be complete.

[0079] Once it is determined that the contacts of both the main positive relay K1 and the precharge relay K2 are not stuck together and the precharge is complete, the main positive relay K1 can be turned on. After the main power supply circuit is running stably, the precharge relay K2 can be turned off, and the main power supply circuit will supply power to the load circuit.

[0080] In one possible embodiment, before performing the adhesion detection of the main positive relay K1 and / or the precharge relay K2, it is also possible to first detect whether the contacts of the switching devices between the load circuit output terminal and the negative terminal of the battery module are stuck, that is, to perform the contact adhesion detection of the main negative relay K3, specifically including:

[0081] Disconnect the connection between the main power supply circuit and the load circuit input terminal (i.e., the main positive relay K1), disconnect the connection between the pre-charge circuit and the load circuit input terminal (i.e., the pre-charge relay K2), disconnect the connection between the load circuit output terminal and the negative terminal of the battery module (i.e., the main negative relay K3), and apply the potential sampling value V5 of the positive terminal of the battery module to the output terminal of the load circuit.

[0082] The potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are detected and compared. When the potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are equal, that is, the potentials at both ends of the main negative relay K3 contact are equal, it is determined that the main negative relay K3 contact, the switching device between the output terminal of the load circuit and the negative terminal of the battery module, is stuck. When the potential V3 at the output terminal of the load circuit and the potential V4 at the negative terminal of the battery module are not equal, it is determined that the main negative relay K3 contact, the switching device between the output terminal of the load circuit and the negative terminal of the battery module, is not stuck.

[0083] This invention provides a power battery system state detection device and method. Before the load circuit is powered on, a simple hardware logic circuit can detect whether the switching devices in the main power supply circuit and pre-charge circuit are stuck together, as well as whether the main negative relay is stuck together. The detection results are accurate, the detection process is simple, and the solution is easy to implement, thus maintaining the safety of the power battery system. The logical operations of the hardware circuit can measure whether the contacts of the switching devices (e.g., main positive relay K1, pre-charge relay K2) in the main power supply circuit and / or pre-charge circuit are stuck together. It can also detect whether the contacts of the main negative relay K3 at the negative terminal of the battery module are stuck together, and can also detect the pre-charge completion rate.

[0084] It should be noted that the current industry strategy for determining pre-charge completion involves collecting the voltage value across the main positive relay K1, converting it via an analog-to-digital converter (A / D converter), and then communicating it to the MCU via isolated communication for confirmation. This method is complex; furthermore, the BMS (Battery Management System) hardware requires dedicated A / D converter and isolated communication chips, which, due to the influence of globalization, limits BMS cost and manufacturing cycle. This invention replaces software computation with hardware logic, achieving the originally complex software calculations through simplified hardware circuitry, thus avoiding the complex steps of software voltage measurement, calculation, comparison, A / D conversion, and isolated communication. Compared to ADC chips and isolated communication chips, this solution is lower in cost, uses more readily available components, and has wider applicability.

[0085] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0086] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0087] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A power battery system state detection device, characterized in that, The first sampling circuit, the second sampling circuit, the first operation unit and the control unit MCU, The sampling point of the first sampling circuit is arranged at the common node of the main power supply circuit, the pre-charging circuit and the positive electrode of the battery module, the first sampling circuit comprises series-connected voltage dividing resistor R1 and voltage dividing resistor R3, the first end of the voltage dividing resistor R1 is connected to the common node, the first end of the voltage dividing resistor R3 is grounded, and the common end of the voltage dividing resistor R1 and the voltage dividing resistor R3 serves as the output end of the first sampling circuit, for outputting the potential sampling value V5 obtained by converting the potential V1 of the positive electrode of the battery module; The sampling point of the second sampling circuit is arranged at the common node of the main power supply circuit, the pre-charging circuit and the input end of the load circuit, the second sampling circuit comprises voltage dividing resistor R2 and voltage dividing resistor R4, the voltage dividing resistor R2 and the voltage dividing resistor R4 are connected in series, the end of the voltage dividing resistor R2 away from the voltage dividing resistor R4 is connected to the common node of the main power supply circuit, the pre-charging circuit and the input end of the load circuit, the end of the voltage dividing resistor R4 away from the voltage dividing resistor R2 is grounded, and the common end of the voltage dividing resistor R2 and the voltage dividing resistor R4 serves as the output end of the second sampling circuit, for outputting the potential sampling value V6 obtained by converting the potential V2 of the input end of the load circuit; The first operation unit is a divider U1, the first input end of the divider U1 is connected to the output end of the first sampling circuit, the second input end of the divider U1 is connected to the output end of the second sampling circuit, and the output end of the divider U1 is connected to the first input end of the control unit MCU, for performing division operation on the potential sampling value V6 and the potential sampling value V5 to obtain the ratio N of the potential sampling value V6 to the potential sampling value V5; The control unit MCU is used for judging whether the contact of the switching device is stuck according to the ratio N under the disconnection state of the main power supply circuit and the pre-charging circuit, wherein: When the ratio N is 0, it is determined that the contacts of the switching devices in the main power supply circuit and the pre-charging circuit are not stuck; When the ratio N is 1, it is determined that the contact of the switching device in the main power supply circuit is stuck; When the ratio N is between 0 and 1, it is determined that the contact of the switching device in the pre-charging circuit is stuck.

2. The power battery system state detection device according to claim 1, wherein The first switching unit U2 is arranged in series in the second sampling circuit, the control end of the first switching unit U2 is connected to the first output end of the control unit MCU, for controlling the on-off of the second sampling circuit through the control unit MCU.

3. The power battery system state detection device according to claim 1 or 2, characterized in that, Further comprising a second operation unit and a second switching unit U4; The first input end of the second operation unit is connected to the output end of the first operation unit, the second input end of the second operation unit is connected to the control unit MCU, the output end of the second operation unit is connected to the control end of the second switching unit U4, for comparing the ratio N of the sampling values of the potential V2 and the potential V1 with a reference value under the disconnection state of the main power supply circuit and the conduction state of the pre-charging circuit, and controlling the on-off of the second switching unit U4 according to the obtained comparison result; An input end of the second switch unit U4 is connected with a working power supply, and an output end of the second switch unit U4 is connected with a second input end of the control unit MCU, for feeding back the comparison result to the control unit MCU; The control unit MCU is used for outputting the reference value, and judging whether the pre-charging is completed according to the comparison result.

4. The power battery system state detection device according to claim 3, characterized in that, The second operation unit is a comparator U3, which is used for comparing the ratio N with the reference value, and outputting a high level to control the second switch unit U4 to be turned on when the ratio N is greater than the reference value.

5. The power battery system state detection device according to claim 3, wherein a main negative switching device is connected in series between the negative electrode of the battery module and the output end of the load circuit. The detection device further comprises a third switch unit U5 and a third operation unit, One end of the third switch unit U5 is connected with a common node of a main negative switch device and an output end of a load circuit, another end of the third switch unit U5 is connected with a first input end of the first operation unit, and a control end of the third switch unit U5 is connected with the control unit MCU; The first input end of the third operation unit is connected with the common node of the main negative switch device and the output end of the load circuit, the second input end of the third operation unit is connected with a common node of the main negative switch device and a negative electrode of a battery module, and an output end of the third operation unit is connected with a third input end of the control unit MCU, and the third operation unit is used for sampling potentials V3 and V4 at both ends of the contact of the main negative switch device when the main negative switch device is turned off, and comparing the potentials V3 and V4; The control unit MCU is used for judging whether the contact of the main negative switch device is stuck according to the comparison result of the potentials V3 and V4: When the potentials V3 and V4 are equal, it is determined that the contact of the main negative switch device is stuck. When the potentials V3 and V4 are not equal, it is determined that the contact of the main negative switch device is not stuck.

6. A method of detecting a state of a power battery system, characterized by, The device is applied to any one of claims 1-5, comprising: controlling the connection between the main power supply circuit and the input end of the load circuit to be disconnected, the connection between the pre-charging circuit and the input end of the load circuit to be disconnected, and the connection between the output end of the load circuit and the negative electrode of the battery module to be connected; sampling the potential V1 of the positive electrode of the battery module through the first sampling circuit, and obtaining a potential sampling value V5 after current limiting through the voltage dividing resistor R1 and the voltage dividing resistor R3; sampling the potential V2 of the input end of the load circuit through the second sampling circuit, and obtaining a potential sampling value V6 after current limiting through the voltage dividing resistor R2 and the voltage dividing resistor R4; calculating a ratio N of the potential sampling value V6 and the potential sampling value V5 through the divider U1, and judging the state of the contact of the switch device according to the ratio N: when the ratio N is 0, it is determined that the contacts of the switch devices in the main power supply circuit and the pre-charging circuit are not stuck; when the ratio N is 1, it is determined that the contact of the switch device in the main power supply circuit is stuck; when the ratio N is between 0 and 1, it is determined that the contact of the switch device in the pre-charging circuit is stuck; if it is determined that the contacts of the switch devices in the main power supply circuit and the pre-charging circuit are not stuck, the connection between the pre-charging circuit and the input end of the load circuit is controlled to be connected; the real-time ratio N is compared with a reference value, and it is judged whether the pre-charging is completed according to the comparison result.

7. The method of claim 6, wherein Also included is detecting whether the switch device between the load circuit output end and the negative pole of the battery module is stuck, including: controlling the disconnection between the main power supply circuit and the input end of the load circuit, the disconnection between the pre-charge circuit and the input end of the load circuit, and the disconnection between the output end of the load circuit and the negative pole of the battery module, and applying the potential sampling value V5 of the positive pole of the battery module to the output end of the load circuit through the third switch unit U5; detecting and comparing the output end potential V3 of the load circuit and the negative pole potential V4 of the battery module through the third operation unit: when the output end potential V3 of the load circuit is equal to the negative pole potential V4 of the battery module, it is determined that the switch device between the load circuit output end and the negative pole of the battery module is stuck; when the output end potential V3 of the load circuit is not equal to the negative pole potential V4 of the battery module, it is determined that the switch device between the load circuit output end and the negative pole of the battery module is not stuck.

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