Current-limiting unit selection method, device, equipment and computer readable storage medium

Abstract

The application discloses a current-limiting unit selection method, device and equipment and a computer readable storage medium, relates to the technical field of power batteries, and discloses a current-limiting unit selection method, device and equipment and a computer readable storage medium, which comprises the following steps: detecting a pre-charging loop voltage, and determining capacitor unit characteristic information, pre-charging characteristic information and pulse characteristic information according to the pre-charging loop voltage; determining a current-limiting unit resistance target value and a rated power target value according to the pre-charging loop voltage, the capacitor unit characteristic information, the pre-charging characteristic information and the pulse characteristic information; and selecting a target current-limiting unit to control a power battery to pre-charge based on the current-limiting unit resistance target value and the rated power target value. The application calculates the current-limiting unit resistance target value and the rated power target value, and selects the target current-limiting unit, so that the high-voltage electrical components are prevented from being impacted by instantaneous large current, and the safe operation and stability of the power battery are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a current-limiting unit selection method, device, equipment and computer readable storage medium. BACKGROUND

[0002] In the field of power batteries, the power battery system is an important energy source system of hybrid electric vehicles and electric vehicles, which provides electric energy for the vehicle during driving. However, the voltage of the power battery system is relatively high compared with the whole vehicle. In order to avoid the generation of instantaneous large current during the high-voltage power-on process of the whole vehicle, the impact on high-voltage electrical components, and the occurrence of faults such as the adhesion of the contacts of the related relays or contactors in the high-voltage system loop and the damage of high-voltage devices, a pre-charge circuit needs to be designed to pre-charge the capacitor unit, and the current-limiting effect of the pre-charge resistor is used to realize the safe connection of the high-voltage loop. Therefore, it is necessary to select a suitable current-limiting unit.

[0003] At present, the existing technology adds a pre-charge resistor to the power supply system of an electric vehicle. The design of the pre-charge circuit is usually based on a simplified RC equivalent circuit model, which at least includes a power battery, a relay, a pre-charge resistor and a capacitor unit. At the initial power-on stage, the capacitor unit needs to be pre-charged to reduce the impact current during power-on, protect the motor control machine, relay and other devices, and thus ensure the safe operation of the power battery system.

[0004] However, the existing technology often relies on experience when selecting a current-limiting unit, lacks accurate calculation methods, and the selection of the current-limiting unit is not accurate enough. Due to the lack of comprehensive evaluation of the performance of the current-limiting unit under actual working conditions, including its instantaneous power carrying capacity, pulse bearing capacity and thermal stability at different environmental temperatures, it is impossible to ensure that the current-limiting unit can work safely and effectively in all cases. In addition, the existing technology does not fully consider the heat capacity and temperature rise of the current-limiting unit, which may cause the current-limiting unit to overheat or even be damaged under continuous pulse or extreme environmental conditions, thereby affecting the safe operation and reliability of the entire power battery system. Therefore, how to accurately select the current-limiting unit is a technical problem to be solved.

[0005] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0006] The main purpose of the present application is to provide a current-limiting unit selection method, device, equipment and computer readable storage medium, which aims to solve the technical problem of how to accurately select the current-limiting unit.

[0007] To achieve the above objectives, this application proposes a current limiting unit selection method. This method is applied to a pre-charge circuit, which includes a power battery, a main positive relay, a main negative relay, a pre-charge relay, a current limiting unit, a capacitor unit, and a load unit. The positive terminal of the power battery is connected to the first terminal of both the main positive relay and the pre-charge relay. The second terminal of the pre-charge relay is connected to the first terminal of the current limiting unit. The second terminal of the main positive relay is connected to the second terminal of the current limiting unit, the first terminal of the capacitor unit, and the first terminal of the load unit. The second terminals of both the capacitor unit and the load unit are connected to the first terminal of the main negative relay. The second terminal of the main negative relay is connected to the negative terminal of the power battery. The method includes:

[0008] The pre-charge circuit voltage is detected, and the characteristic information of the capacitor unit, the pre-charge characteristic information, and the pulse characteristic information are determined based on the pre-charge circuit voltage.

[0009] The target values ​​of the current limiting unit resistance and rated power are determined based on the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information.

[0010] Based on the target value of the current limiting unit resistance and the target value of the rated power, the target current limiting unit is selected to control the power battery for pre-charging.

[0011] In one embodiment, the step of determining capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information based on the pre-charge circuit voltage includes:

[0012] The following parameters are determined based on the pre-charge circuit voltage: capacitor cell terminal voltage, capacitor cell initial voltage, capacitor cell capacitance value, power battery system terminal voltage, pre-charge relay rated current, pre-charge circuit current, resistor operating condition information, pre-charge time, pulse frequency, and pulse interval time.

[0013] The characteristic information of the capacitor unit is determined based on the terminal voltage of the capacitor unit, the initial voltage of the capacitor unit, and the capacitance value of the capacitor unit.

[0014] Precharge characteristic information is determined based on the power battery system terminal voltage, precharge relay rated current, precharge circuit current, resistance operating condition information, and precharge time.

[0015] Pulse characteristic information is determined based on pulse frequency and pulse interval time.

[0016] In one embodiment, the steps of determining the target value of the current limiting unit resistor and the target value of the rated power based on the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information include:

[0017] The starting safety resistance value and the current balance resistance value are determined based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor unit characteristic information.

[0018] The pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value are determined based on the pre-charge circuit voltage, pre-charge characteristic information, and pulse characteristic information.

[0019] Based on the pre-charge circuit voltage, start-up safety resistance value, current balance resistance value, pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value, the target values ​​of the current limiting unit resistance and rated power are obtained.

[0020] In one embodiment, the steps of determining the start-up safety resistance value and the current balance resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor cell characteristic information include:

[0021] The first circuit model is constructed based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor unit characteristic information.

[0022] A second circuit model is constructed based on the pre-charge circuit voltage and pre-charge characteristic information;

[0023] The starting safety resistance value is calculated based on the resistance condition information in the pre-charge characteristic information and the capacitor unit terminal voltage, capacitor unit initial voltage, capacitor unit capacitance value, and the first circuit model in the power battery system terminal voltage and capacitor unit characteristic information.

[0024] The current balance resistance value is calculated based on the resistance condition information in the precharge characteristic information, the power battery system terminal voltage, the rated current of the precharge relay, and the second circuit model.

[0025] In one embodiment, the steps of determining the pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and pulse characteristic information include:

[0026] The instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the material of the current limiting unit, the power safety factor, the power overload factor, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit are obtained.

[0027] The characteristic information of the current limiting unit is determined based on the instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the power safety factor, and the power overload factor.

[0028] The temperature characteristic information of the current limiting unit is determined based on the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit.

[0029] The third loop model, the fourth loop model, and the fifth loop model are constructed based on the pre-charge characteristic information, pulse characteristic information, current limiting unit characteristic information, and current limiting unit temperature characteristic information.

[0030] The pulse energy resistance value is calculated based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time, capacitor unit terminal voltage, capacitor unit capacitance value, pulse frequency, pulse interval time, current limiting unit instantaneous terminal voltage, current limiting unit peak energy, and third circuit model from the pre-charge characteristic information;

[0031] Based on the resistance condition information in the pre-charge characteristic information, the power safety factor and power overload factor in the power battery system terminal voltage and current limiting unit characteristic information, and the fourth circuit model, the rated power characteristic value and power overload resistance value are calculated.

[0032] The thermal stability resistance value is calculated based on the power battery system terminal voltage and pre-charge time from the pre-charge characteristic information, the instantaneous terminal voltage of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material from the current limiting unit characteristic information, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, the operating temperature limit of the current limiting unit from the current limiting unit temperature characteristic information, and the fifth loop model.

[0033] In one embodiment, the method further includes:

[0034] Energy information is calculated based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time in the pre-charge characteristic information, the capacitor unit terminal voltage, capacitor unit capacitance value in the capacitor unit characteristic information, and the pulse frequency and pulse interval time in the pulse characteristic information. The energy information includes the energy supplied by the power battery and the energy stored in the capacitor unit.

[0035] Calculate the precharge circuit pulse energy based on the energy supplied by the power battery and the energy stored in the capacitor unit;

[0036] The energy absorption state is determined based on the pulse energy of the pre-charge circuit and the peak energy of the current limiting unit in the characteristic information of the current limiting unit, and the determination result is obtained.

[0037] The pulse energy resistance value is selected based on the judgment result.

[0038] In one embodiment, the method further includes:

[0039] The peak power of the current limiting unit is determined based on the terminal voltage and resistance information of the power battery system in the pre-charge characteristic information.

[0040] The rated power characteristic value is determined based on the power safety factor, power overload factor, and peak power of the current limiting unit in the characteristic information of the current limiting unit.

[0041] The power overload state is determined based on the power safety factor and power overload factor in the rated power characteristic value and the current limiting unit characteristic information, and the determination result is obtained.

[0042] Based on the judgment results, the power overload resistor value is selected and determined.

[0043] Furthermore, to achieve the above objectives, this application also proposes a current limiting unit selection device, which includes:

[0044] The acquisition module is used to detect the pre-charge circuit voltage and determine the capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information based on the pre-charge circuit voltage;

[0045] The processing module is used to determine the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information and pulse characteristic information;

[0046] The execution module is used to select the target current limiting unit to control the power battery for pre-charging based on the target value of the current limiting unit resistance and the target value of the rated power.

[0047] In addition, to achieve the above objectives, this application also proposes a current limiting unit selection device, the device including: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the current limiting unit selection method described above.

[0048] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the current limiting unit selection method described above.

[0049] One or more technical solutions proposed in this application have at least the following technical effects:

[0050] This application proposes a method for selecting a current-limiting unit. The method involves detecting the pre-charge circuit voltage and determining capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information based on this voltage. The method then determines the target resistance value and rated power value of the current-limiting unit based on these parameters. Finally, based on these target resistance and rated power values, a target current-limiting unit is selected to control the power battery during pre-charging. By detecting the pre-charge circuit voltage of the power battery system and combining this with the capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information, this application calculates the target resistance value and rated power value of the current-limiting unit and selects the target current-limiting unit. This ensures the safety of the current during pre-charging, avoids the impact of instantaneous large currents on high-voltage electrical components, optimizes the energy conversion and storage process, reduces energy loss, and thus guarantees the safe operation and long-term stability of the power battery. Attached Figure Description

[0051] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart illustrating the method for selecting a current limiting unit in this application, as shown in Embodiment 1.

[0054] Figure 2 The RC equivalent circuit model diagram of the pre-charging circuit in the current limiting unit selection method of this application is shown.

[0055] Figure 3 This is a graph showing the voltage and current changes during the pre-charging process in the first embodiment of the current limiting unit selection method of this application;

[0056] Figure 4 This is a schematic diagram of pulse characteristic information in the first embodiment of the current limiting unit selection method of this application;

[0057] Figure 5 This is a flowchart illustrating Embodiment 2 of the current limiting unit selection method in this application.

[0058] Figure 6 This is a schematic diagram of the module structure of the current limiting unit selection device in an embodiment of this application;

[0059] Figure 7This is a schematic diagram of the hardware operating environment involved in the current limiting unit selection method in this application embodiment.

[0060] Explanation of icon numbers:

[0061] 10. Power battery; 20. Capacitor unit; 30. Load unit; K1. Main positive relay; K2. Main negative relay; K3. Precharge relay; R. Current limiting unit.

[0062] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0063] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0064] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0065] The main solution of this application embodiment is: to detect the pre-charge circuit voltage and determine the capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information based on the pre-charge circuit voltage; to determine the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information; and to select the target current limiting unit to control the power battery to perform pre-charge based on the target value of the current limiting unit resistance and the target value of the rated power.

[0066] In this embodiment, for ease of description, the following description will focus on the power battery control module as the execution subject.

[0067] Because existing technologies often rely on experience when selecting current-limiting units and lack precise calculation methods, the selection of current-limiting units is not accurate enough. Furthermore, the lack of a comprehensive evaluation of the performance of current-limiting units under actual operating conditions, including their instantaneous power handling capacity, pulse withstand capability, and thermal stability under different ambient temperatures, makes it impossible to ensure that the current-limiting units can operate safely and effectively in all situations. In addition, existing technologies fail to adequately consider the heat capacity and temperature rise of the current-limiting units, which can lead to overheating or even damage under continuous pulse or extreme environmental conditions, thereby affecting the reliability of the entire power battery system.

[0068] This application provides a solution that detects the pre-charge circuit voltage and determines capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information based on the pre-charge circuit voltage; determines the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information; and selects a target current limiting unit to control the power battery for pre-charging based on the target value of the current limiting unit resistance and the target value of the rated power.

[0069] As can be seen from the above embodiments, this application calculates the target value of the current limiting unit resistance and the target value of the rated power by detecting the pre-charging circuit voltage of the power battery system and combining the characteristic information of the capacitor unit, the pre-charging characteristic information and the pulse characteristic information, and selects the target current limiting unit, thereby ensuring the safety of the current during the pre-charging process, avoiding the impact of instantaneous large current on high voltage electrical components, optimizing the energy conversion and storage process, reducing energy loss, and thus ensuring the safe operation and long-term stability of the power battery.

[0070] Based on this, embodiments of this application provide a method for selecting a current limiting unit, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the method for selecting a current limiting unit in this application.

[0071] In this embodiment, the current limiting unit selection method includes steps S10 to S30:

[0072] Step S10: Detect the pre-charge circuit voltage, and determine the capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information based on the pre-charge circuit voltage;

[0073] It should be noted that the high-voltage pre-charge circuit of the power battery can be simplified to an RC equivalent circuit model, such as... Figure 2 As shown, Figure 2 The diagram shows the RC equivalent circuit model of the pre-charging circuit in the current limiting unit selection method of this application. The pre-charging circuit includes a power battery 10, a main positive relay K1, a main negative relay K2, a pre-charging relay K3, a current limiting unit R, a capacitor unit 20, and a load unit 30. The positive terminal of the power battery 10 is connected to the first terminal of the main positive relay K1 and the first terminal of the pre-charging relay K3. The second terminal of the pre-charging relay K3 is connected to the first terminal of the current limiting unit R. The second terminal of the main positive relay K1 is connected to the second terminal of the current limiting unit R, the first terminal of the capacitor unit 20, and the first terminal of the load unit 30. The second terminals of the capacitor unit 20 and the load unit 30 are both connected to the first terminal of the main negative relay K2. The second terminal of the main negative relay K2 is connected to the negative terminal of the power battery 10.

[0074] Understandably, the power battery system is closely connected to the motor controller, which is equipped with a bus capacitor. Based on the pre-charge circuit, the current limiting unit pre-charges the bus capacitor, ensuring that the pre-charge circuit current is controlled within a safe range when the main circuit is connected, thus ensuring the normal operation of the power battery system. Power battery 10 is the power battery, capacitor unit 20 is the motor controller bus capacitor, main positive relay K1, main negative relay K2, and pre-charge relay K3 are automatic switches for the pre-charge circuit, and load unit 20 is the motor. When the power battery circuit enters the pre-charge process, main negative relay K2 and pre-charge relay K3 are closed, and main positive relay K1 is opened. At this time, power battery 10, main negative relay K2, pre-charge relay K3, current limiting unit R, and capacitor unit 20 constitute the pre-charge circuit. Utilizing the current limiting effect of the current limiting unit, capacitor unit 20 is pre-charged, and the voltage U at the capacitor unit terminal... C Gradually increase, when the voltage U at the capacitor unit terminals... C With the power battery system terminal voltage U B When they are close, it is usually necessary to ensure that U C ≥90% U B For example, U C =98%U B At this point, the main positive relay K1 and the main negative relay K2 are closed, and the pre-charge relay K3 is opened, completing the high-voltage pre-charge process. Figure 3 As shown, Figure 3 This is a graph showing the voltage and current changes during the pre-charging process in the first embodiment of the current limiting unit selection method of this application.

[0075] For ease of understanding, we will take the determination of capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information as examples, where the information acquisition device is the information acquisition module and the storage device is the memory.

[0076] The information acquisition module obtains the pre-charge circuit voltage and determines the capacitor unit terminal voltage U based on the pre-charge circuit voltage. C Initial voltage U0 of capacitor unit, capacitance value C of capacitor unit, and terminal voltage U of power battery system. B , Rated current I of precharge relay k Precharge circuit current I t The precharge time t, pulse frequency f, pulse interval time Δt, and resistance condition information are used to determine the capacitor unit characteristic information based on the capacitor unit terminal voltage, capacitor unit initial voltage, and capacitor unit capacitance value. The precharge characteristic information is determined based on the power battery system terminal voltage, precharge relay rated current, precharge circuit current, resistance condition information, and precharge time. The pulse characteristic information is determined based on the pulse frequency and pulse interval time. Subsequent processing is performed based on the capacitor unit characteristic information, precharge characteristic information, and pulse characteristic information.

[0077] In one feasible implementation, step S10 may include steps A11 to A13:

[0078] Step A11: Determine the capacitor cell terminal voltage, capacitor cell initial voltage, capacitor cell capacitance value, power battery system terminal voltage, precharge relay rated current, precharge circuit current, resistor operating condition information, precharge time, pulse frequency, and pulse interval time based on the precharge circuit voltage.

[0079] It should be noted that the capacitor cell terminal voltage is the voltage difference across the capacitor, determining the starting point of capacitor charging. The initial voltage of the capacitor cell is the voltage level of the capacitor cell when the power battery system begins pre-charging. The capacitor cell capacitance value is the bus capacitance value of the motor controller, representing the ability to store charge. The power battery system terminal voltage is the voltage output by the battery, directly affecting the voltage level during the pre-charging process. The pre-charging circuit current is the magnitude of the current flowing through the pre-charging circuit. The resistor condition information reflects the thermal stability, energy dissipation capacity, and power carrying capacity of the resistor under different operating conditions. The pre-charging time is the time required for the capacitor cell to reach the preset voltage level, thus determining the duration of the pre-charging process. The pulse frequency f is the number of consecutive pulses, i.e., the number of consecutive pre-charging cycles. The pulse interval time Δt includes the pre-charging small gap time Δt1 and the pre-charging large gap time Δt2. The pre-charging small gap time refers to the time interval between two consecutive pulses, i.e., the interval between the previous pre-charging and the next pre-charging, such as Δt1 = 2s. The pre-charging large gap time refers to the gap time after f consecutive pre-charging cycles, such as Δt2 = 15s. Figure 4 As shown, Figure 4 This is a schematic diagram of pulse characteristic information in the first embodiment of the current limiting unit selection method of this application.

[0080] Step A12: Determine the characteristic information of the capacitor unit based on the terminal voltage of the capacitor unit, the initial voltage of the capacitor unit, and the capacitance value of the capacitor unit;

[0081] It should be noted that the capacitor cell characteristic information reflects the state characteristics of the capacitor cell during the pre-charging process, including the capacitor cell terminal voltage, the capacitor cell initial voltage, and the capacitor cell capacitance value.

[0082] Step A13: Determine the pre-charge characteristic information based on the power battery system terminal voltage, pre-charge relay rated current, pre-charge circuit current, resistance condition information, and pre-charge time;

[0083] It should be noted that the pre-charge characteristic information reflects the characteristics of the operating conditions during the pre-charge process, including the power battery system terminal voltage, the rated current of the pre-charge relay, the pre-charge circuit current, resistance operating conditions, and the pre-charge time.

[0084] Step A14: Determine pulse characteristic information based on pulse frequency and pulse interval time.

[0085] It should be noted that the pulse characteristic information reflects the characteristics of the pulse state during the pre-charging process, including the pulse frequency and pulse interval time.

[0086] Step S20: Determine the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information;

[0087] It should be noted that the target value of the current limiting unit resistor is the target value of the current limiting unit resistor calculated during the pre-charging process. It reflects the characteristics of the target resistor value selected to meet the charging requirements, including but not limited to the starting safety resistor value, current balance resistor value, pulse energy resistor value, power overload resistor value, and thermal stability resistor value. The target value of the rated power is the target value of the rated power of the current limiting unit calculated during the pre-charging process. It reflects the characteristics of the target rated power value selected to meet the charging requirements, including but not limited to the rated power characteristic value.

[0088] Understandably, during pre-charging, the capacitor cell needs to be charged to a certain voltage level within a specific time. On one hand, the resistance value of the current-limiting unit directly affects the magnitude of the pre-charging circuit current, thus affecting the charging rate of the capacitor cell and directly determining the pre-charging time. Therefore, the target resistance value of the current-limiting unit reflects the efficiency characteristics of pre-charging to ensure that the pre-charging process is both fast and safe. On the other hand, the magnitude of the pre-charging circuit current also affects the operational safety of the pre-charging relay. Therefore, the target resistance value of the current-limiting unit also reflects the pulse current withstand capability to prevent damage to the battery system. During pre-charging, the current-limiting unit needs to withstand pulse energy. If the heat cannot be effectively dissipated, it may cause the current-limiting unit to overheat, affecting its performance or even causing damage. The resistance value of the current-limiting unit affects the energy dissipation capability and power carrying capacity. Therefore, the target resistance value of the current-limiting unit also reflects the characteristics of pulse energy dissipation, power carrying capacity, and resistor thermal stability, ensuring that the resistor temperature remains within a safe range during long-term operation or continuous pulse occurrences, preventing burnout or failure due to thermal issues, and ensuring that the current-limiting unit can operate safely and stably during pre-charging.

[0089] Furthermore, it should be noted that in practical applications, it is necessary to minimize the pre-charge time while also minimizing the pulse energy in the pre-charge circuit. Conversely, a larger resistance value in the current-limiting unit results in a longer pre-charge time and lower pulse energy in the pre-charge circuit, while a smaller resistance value results in a shorter pre-charge time and higher pulse energy in the pre-charge circuit. Therefore, the selection of the current-limiting unit requires consideration not only of its resistance value but also of its rated power. Thus, it is necessary to comprehensively consider the starting safety resistance value, current balance resistance value, pulse energy resistance value, power overload resistance value, thermal stability resistance value, and rated power characteristic value to determine the target resistance and rated power values ​​of the current-limiting unit. This allows for the selection of a suitable current-limiting unit, ensuring that the pre-charge circuit current is controlled within a safe range during the pre-charge phase. This protects the battery system from current surges, reduces energy loss, improves overall energy efficiency, maintains system stability, and extends service life.

[0090] For ease of understanding, we will take the determination of the target value of the current limiting unit resistor as an example. The information acquisition device is the information acquisition module, the storage device is the memory, and the processing device is the processing module.

[0091] After acquiring the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information, the information acquisition module determines the target value of the current-limiting unit resistance based on these information. It also acquires the current-limiting unit characteristic information and its temperature characteristic information. This information includes, but is not limited to, the instantaneous terminal voltage, peak energy, mass, specific heat capacity of the material, power safety factor, and power overload factor. The temperature characteristic information includes, but is not limited to, the target temperature, initial temperature, and operating temperature limit. Based on these information, a current-limiting unit circuit model is constructed, comprising a first circuit model, a second circuit model, a third circuit model, a fourth circuit model, and a fifth circuit model. Subsequent processing is then performed based on this circuit model.

[0092] Step S30: Based on the target value of the current limiting unit resistance and the target value of the rated power, select the target current limiting unit to control the power battery for pre-charging.

[0093] It should be noted that the target current limiting unit reflects the characteristics of the current limiting unit selected to meet the expected requirements during the pre-charging process.

[0094] Understandably, based on the calculated target resistance and rated power values, the closest current limiting unit that meets the technical specifications is selected to ensure precise current control during pre-charging, avoid damage to the battery system from current surges, and optimize pre-charging parameter settings, such as pre-charging time and pulse frequency, to achieve more efficient energy conversion and storage. When an abnormal situation is detected, such as abnormal current or excessive temperature, protection measures are immediately activated, such as power off or starting the cooling system, to protect system safety.

[0095] In one embodiment, in order to facilitate the selection of a target current limiting unit to control the power battery for pre-charging based on the target value of the current limiting unit resistance and the target value of the rated power, a corresponding execution device, such as a control module or an execution module, can be pre-set to select the corresponding target current limiting unit to control the power battery for pre-charging.

[0096] For ease of understanding, we will take the acquisition of the target value of the current limiting unit resistor and the target value of the rated power as an example. The information acquisition device is the information acquisition module, the storage device is the memory, and the execution device is the execution module.

[0097] After acquiring the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information, the information acquisition module determines the target value of the current-limiting unit resistance and the target value of the rated power based on these information. It also acquires the current-limiting unit characteristic information and the current-limiting unit temperature characteristic information. Based on these information, a current-limiting unit circuit model is constructed. The module then calculates the starting safety resistance value, current balance resistance value, pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value. Finally, based on these values, the target value of the current-limiting unit resistance and the target value of the rated power are determined, allowing for the selection of a suitable target current-limiting unit to control the power battery for pre-charging.

[0098] The current-limiting unit selection method proposed in this embodiment detects the pre-charge circuit voltage and determines the capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information based on the pre-charge circuit voltage. It then determines the target resistance value and rated power target value of the current-limiting unit based on these information. Based on the target resistance and rated power values, a target current-limiting unit is selected to control the power battery for pre-charging. This solves the technical problem of instantaneous high currents during the high-voltage power-on process of the vehicle, which can cause malfunctions in high-voltage electrical components. Compared to existing technologies, this application, by detecting the pre-charge circuit voltage of the power battery system and combining it with the capacitor unit characteristic information, pre-charge characteristic information, and pulse characteristic information, calculates the target resistance and rated power values ​​of the current-limiting unit and selects the target current-limiting unit. This ensures the safety of the current during pre-charging, avoids the impact of instantaneous high currents on high-voltage electrical components, optimizes the energy conversion and storage process, reduces energy loss, and thus guarantees the safe operation and long-term stability of the power battery.

[0099] Based on the first embodiment of this application, in the second embodiment of this application, the same or similar content as the first embodiment described above can be referred to the above description, and will not be repeated hereafter.

[0100] In this embodiment, refer to Figure 5 , Figure 5 This is a flowchart illustrating the second embodiment of the current limiting unit selection method of this application. Step S20 specifically includes steps S201 to S203:

[0101] Step S201: Determine the start-up safety resistance value and the current balance resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor unit characteristic information;

[0102] It should be noted that the starting safety resistance value reflects the characteristics of the current limiting unit calculated during the pre-charging process of the capacitor unit, while the current balance resistance value reflects the characteristics of the current limiting unit calculated when the capacitor unit is short-circuited at the instant the pre-charge relay closes during the pre-charging process.

[0103] For ease of understanding, we will take the acquisition of the start-up safety resistance value and the current balance resistance value as an example. The information acquisition device is the information acquisition module, the storage device is the memory, and the processing device is the processing module.

[0104] The information acquisition module obtains the pre-charge time t and the capacitor cell terminal voltage. The capacitor cell terminal voltage is the capacitor cell terminal voltage U corresponding to time t during the pre-charge process. CThe process involves: obtaining the initial voltage of the capacitor cell (U0), which is the voltage level of the capacitor cell when the power battery system begins pre-charging; obtaining the capacitance value of the capacitor cell (C), which is the bus capacitance value of the motor controller; and obtaining the terminal voltage of the power battery system (U0). B The pre-charge time, capacitor cell terminal voltage, capacitor cell initial voltage, capacitor cell capacitance value, and power battery system terminal voltage are stored in the memory. The processing module constructs a first circuit model based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor cell characteristic information. Based on the resistance condition information in the pre-charge characteristic information and the power battery system terminal voltage, the capacitor cell terminal voltage, capacitor cell initial voltage, capacitor cell capacitance value, and the first circuit model, the starting safety resistance value R1 is calculated.

[0105] At this time, the voltage across the capacitor unit satisfies the following relationship:

[0106]

[0107] Among them, U C U is the voltage across the capacitor cell, U0 is the initial voltage of the capacitor cell, and U B R1 is the starting safety resistance value, and C is the capacitance value of the capacitor unit.

[0108] Therefore, the starting safety resistance value R1 can be obtained:

[0109]

[0110] Where ln is a logarithmic function with the natural constant e as the base, R1 is the starting safety resistance value, and C is the capacitance value of the capacitor unit.

[0111] According to the preset precharge time threshold t limit The first loop model formula that can be determined to satisfy the starting safety resistance value of the current limiting unit is:

[0112]

[0113] For example, according to electrochemical principles, U0 = 0, and typically, U is required to be... C ≥90% U B U is commonly used. C =98%U B Substituting into the formula, we get:

[0114]

[0115] Typically, the precharge time t is required to be ≤ 500ms. For example, if the precharge time t = 200ms, the first loop model formula that satisfies the starting safety resistance value of the current limiting unit can be determined as follows:

[0116] 4·R1·C·≤200

[0117] During the pre-charging process, based on the characteristic of the capacitor unit that "passes AC and blocks DC", at the instant that the main negative relay K2 and the pre-charging relay K3 are closed, the capacitor unit is equivalent to a short circuit. Based on the electrochemical principle, the second circuit model formula is constructed.

[0118] In the second loop model formula, the pre-charge loop current I(t) during the pre-charge process is:

[0119]

[0120] Where I(t) is the pre-charge circuit current during the pre-charge process, I k R1 represents the rated current of the pre-charge relay, and R2 represents the current balancing resistor value.

[0121] Therefore, the current balancing resistance value R2 can be obtained as:

[0122]

[0123] In one feasible implementation, step S201 may include steps B21 to B24:

[0124] Step B21: Construct the first circuit model based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor unit characteristic information;

[0125] It should be noted that by constructing the first loop model, the starting safety resistance value can be calculated to prevent the generation of instantaneous large current during precharging, ensuring that circuit components are not damaged by current surges. In order to ensure that the precharging loop current is controlled within a safe and stable range, and to avoid the current being too large or too small, which would affect the precharging efficiency and safety.

[0126] Step B22: Construct a second circuit model based on the pre-charge circuit voltage and pre-charge characteristic information;

[0127] It should be noted that by constructing the second loop model and combining the pre-charge characteristic information and the capacitor unit characteristic information, the current balancing resistance value can be determined to maintain the current balance during the pre-charge process.

[0128] Step B23: Calculate the start-up safety resistance value based on the resistance condition information in the pre-charge characteristic information and the capacitor unit terminal voltage, capacitor unit initial voltage, capacitor unit capacitance value in the power battery system terminal voltage and capacitor unit characteristic information, as well as the first circuit model.

[0129] It should be noted that the starting safety resistor value is directly proportional to the precharge time. The larger the starting safety resistor value, the longer the precharge time. The precharge time must be less than the preset time threshold to ensure precharge efficiency. At the same time, the starting safety resistor value can ensure that the loop current is controlled within a safe range at the beginning of precharge to prevent current surges from damaging the circuit.

[0130] Step B24: Calculate the current balance resistance value based on the resistance condition information, power battery system terminal voltage, precharge relay rated current, and second circuit model in the precharge characteristic information.

[0131] It should be noted that by calculating the starting safety resistance value and the current balance resistance value, the current can be effectively limited at the beginning of pre-charging, reducing the impact on circuit components and lowering the risk of damage. At the same time, it ensures the uniform distribution of current during pre-charging, avoids local overheating, improves charging efficiency, and also helps to extend the service life of the power battery and circuit components.

[0132] Step S202: Determine the pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and pulse characteristic information;

[0133] It should be noted that the pulse energy resistance value reflects the characteristic of the current limiting unit safely absorbing pulse energy during the pulse process, the rated power characteristic value reflects the characteristic of the current limiting unit meeting the maximum power requirement for safe operation, the power overload resistance value reflects the characteristic of the current limiting unit expected to resist instantaneous pulse energy, and the thermal stability resistance value reflects the characteristic of the current limiting unit meeting the expected temperature rise when absorbing pulse energy.

[0134] Understandably, the peak power of the current limiting unit is determined based on the voltage and resistance information of the power battery system in the pre-charge characteristic information. The peak power of the current limiting unit reflects the maximum value of the pre-charge power during the pre-charge process. If the current limiting unit withstands high power in a short period of time, it will quickly generate a large amount of heat. The level of the peak power determines the thermal stability of the current limiting unit, that is, its ability to operate safely without exceeding the operating temperature limit. The peak power of the current limiting unit can ensure that the current limiting unit will not be damaged due to excessive power during the pre-charge process, thus avoiding safety risks to the entire power battery system. The rated power characteristic value of the current limiting unit is determined based on the power safety factor, power overload factor, and peak power of the current limiting unit in the current limiting unit characteristic information. The rated power characteristic value of the current limiting unit reflects the characteristics of the continuous power level that it can safely bear during the pre-charge process, and also reflects the thermal stability and reliability of the current limiting unit during long-term operation. This ensures that the current limiting unit will not degrade in performance or be damaged due to overheating under the expected workload, thereby ensuring the safe and stable operation of the entire system.

[0135] Additionally, it should be noted that the power overload state is determined based on the rated power characteristic value and the power safety factor and power overload factor in the current limiting unit characteristic information. The judgment result is obtained, and the power overload resistance value is selected based on the judgment result. The judgment result reflects the characteristics of the target current limiting unit selected under different operating conditions. The power overload resistance value is selected based on the judgment result, thereby selecting the appropriate current limiting unit type and specifications. In the case of continuous pulse charging, the current limiting unit needs to withstand periodic power surges. The calculated power overload resistance value reflects the current limiting unit's ability to withstand pulse current, ensuring that the selected current limiting unit will not be damaged due to excessive instantaneous power during pulse charging.

[0136] For ease of understanding, we will take the acquisition of pulse energy resistance value, rated power characteristic value, power overload resistance value and thermal stability resistance value as an example. The information acquisition device is the information acquisition module, the storage device is the memory, and the processing device is the processing module.

[0137] The information acquisition module obtains the characteristic information and temperature characteristic information of the current limiting unit, acquires the pulse frequency f (the number of consecutive pulses), and acquires the pulse interval time Δt. The pulse interval time Δt includes the pre-charge small gap time Δt1 and the pre-charge large gap time Δt2. The pre-charge small gap time refers to the time interval between two consecutive pulses, i.e., the interval between the previous pre-charge and the next pre-charge, such as Δt1 = 2s. The pre-charge large gap time refers to the gap time after f consecutive pre-charges. The module also integrates the current limiting unit characteristic information, current limiting unit temperature characteristic information, pulse frequency, and pulse... The charging interval time is stored in the memory. The processing module constructs the third loop model, the fourth loop model, and the fifth loop model based on the pre-charge characteristic information, pulse characteristic information, current limiting unit characteristic information, and current limiting unit temperature characteristic information. Based on the power battery system terminal voltage, pre-charge loop current, and pre-charge time in the pre-charge characteristic information, the capacitor unit terminal voltage and capacitor unit capacitance value in the capacitor unit characteristic information, the pulse frequency and pulse interval time in the pulse characteristic information, the instantaneous terminal voltage and peak energy of the current limiting unit in the current limiting unit characteristic information, and the third loop model, the pulse energy resistance value is calculated.

[0138] The formula for power battery energy supply is determined based on the third-loop model:

[0139]

[0140] Formula for storing energy in a capacitor cell:

[0141]

[0142] Therefore, the formula for the pre-charge circuit pulse energy is: W R =f·(W t-W C )

[0143] Among them, U C U is the voltage across the capacitor unit. B I(t) is the terminal voltage of the power battery system, I(t) is the pre-charge circuit current during the pre-charge process, t is the pre-charge time, C is the capacitance value of the capacitor unit, and f is the pulse frequency.

[0144] It is understandable that if it is a single pulse, then f = 1; if it is a continuous pulse, when the precharge gap time Δt1 is less than the preset interval time, the pulse energy of the precharge circuit can generally be calculated by linear accumulation.

[0145] It should be noted that the peak energy of the current limiting unit refers to the maximum energy that the current limiting unit can withstand during the pre-charging process. It reflects the energy dissipation and load-bearing capacity of the current limiting unit and affects whether the current limiting unit can safely absorb the pulse energy of the pre-charging circuit. Therefore, calculating the pulse energy of the pre-charging circuit helps determine the maximum energy that the current limiting unit needs to withstand, thereby selecting the appropriate resistor type and specifications to prevent resistor damage or system failure due to overheating.

[0146] Based on the third-loop model, the formula for calculating the peak energy of the current-limiting unit is as follows:

[0147] Q(t)≥W R

[0148] Where Q(t) is the peak energy of the current-limiting unit.

[0149] According to electrochemical principles, the peak energy of the current-limiting unit satisfies the following formula:

[0150]

[0151] Among them, U R U is the instantaneous terminal voltage of the current limiting unit. R,max This refers to the maximum instantaneous terminal voltage of the current limiting unit during the pre-charging process.

[0152] It can be understood that at the instant the main negative relay K2 and the pre-charge relay K3 close, the capacitor unit is essentially short-circuited, and the voltage across the current limiting unit is at its maximum. Therefore, the maximum instantaneous terminal voltage of the current limiting unit is equal to the terminal voltage of the power battery, i.e., U. R,max =U B ,but

[0153]

[0154] Therefore, the pulse energy resistance value R3 can be obtained as:

[0155]

[0156] Among them, U B U is the terminal voltage of the power battery system. C denoted as the voltage across the capacitor cell, C is the capacitance of the capacitor cell, I(t) is the pre-charge circuit current during the pre-charge process, t is the pre-charge time, and f is the pulse frequency.

[0157] As can be seen from the formula for pulse energy resistance value, based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time in the pre-charge characteristic information, the capacitor unit terminal voltage and capacitor unit capacitance value in the capacitor unit characteristic information, and the pulse frequency and pulse interval time in the pulse characteristic information, a suitable resistor type and specification can be selected to determine the pulse energy resistance value of the current limiting unit.

[0158] The processing module calculates the power overload resistance value based on the resistance condition information in the precharge feature information, the power safety factor and power overload factor in the power battery system terminal voltage and current limiting unit feature information, and the fourth circuit model.

[0159] The peak power of the current limiting unit is determined based on the fourth loop model and resistor operating condition information.

[0160]

[0161] Among them, P R U represents the peak power of the current limiting unit. R,max R4 represents the maximum instantaneous terminal voltage of the current limiting unit during the pre-charging process, and R4 represents the power overload resistance value.

[0162] It can be understood that at the instant the main negative relay K2 and the pre-charge relay K3 close, the capacitor unit is essentially short-circuited, and the voltage across the current limiting unit is at its maximum. Therefore, the maximum instantaneous terminal voltage of the current limiting unit is equal to the terminal voltage of the power battery, i.e., U. R,max =U B Then the peak power of the current limiting unit is:

[0163]

[0164] The rated power characteristic value is determined based on the power safety factor, power overload factor, and peak power of the current limiting unit in the characteristic information of the current limiting unit:

[0165]

[0166] Among them, P reted γ is the rated power characteristic value, ε is the power safety factor, ε is the power overload factor, and R4 is the power overload resistance value.

[0167] It is understood that the rated power characteristic value is the continuous operating power at which the current limiting unit can operate safely; the power overload factor refers to the ability of the current limiting unit to withstand power exceeding its rated power for a short period of time, as defined in the manufacturer's product specification; the power safety factor is determined by the safety level and usage requirements, and can be flexibly adjusted according to actual conditions, without being specifically limited in this patent.

[0168] In addition, it is understandable that the rated power target value of the current limiting unit should be greater than or equal to the rated power characteristic value.

[0169] Therefore, the formula for the power overload resistance value R4 is:

[0170]

[0171] As can be seen from the formula for power overload resistance value, based on the rated power characteristic value and the power safety factor and power overload factor in the current limiting unit characteristic information, a suitable resistor type and specification can be selected to determine the rated power target value and power overload resistance value of the current limiting unit.

[0172] It should be noted that the power overload factor is related to the duration of the overload, T. over According to the empirical formula, the power overload factor decreases as the duration of overload increases, which can be expressed by an exponential decay model:

[0173]

[0174] Where ε is the power overload factor, b is the decay rate, which represents the rate at which the power overload factor decays with time and is a key parameter affecting the speed of curve descent, a is the initial overload capacity, which represents the initial power overload factor of the resistor when time is zero, i.e., the peak overload capacity before time decay, and c is the steady-state overload capacity, which represents the stable value of the power overload factor of the resistor as time approaches infinity. It is usually related to the long-term thermal stability of the resistor. Based on the rated power characteristic value and the power safety factor and power overload factor in the current limiting unit characteristic information, the power overload state is judged and the judgment result is obtained. It is required that the continuous overload time is greater than or equal to the pulse duration so as to flexibly adjust the pulse process and thus reasonably select the power overload resistor value.

[0175] The processing module calculates the thermal stability resistance value based on the power battery system terminal voltage and pre-charge time in the pre-charge characteristic information, the instantaneous terminal voltage of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material in the current limiting unit characteristic information, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, the operating temperature limit of the current limiting unit in the current limiting unit temperature characteristic information, and the fifth loop model.

[0176] Based on electrochemical principles, during the pre-charging process, the thermal stability resistor generates heat by absorbing pulse energy, causing its temperature to rise. However, it is crucial to ensure that the resistor's temperature remains within a safe range during prolonged operation or continuous pulse occurrences, preventing burnout or failure due to thermal issues. This ensures the current-limiting unit operates safely and stably during the pre-charging process. The temperature calculation formula for determining the thermal stability resistor value at the end of the pre-charging process, based on the fifth-loop model, is as follows:

[0177]

[0178] Among them, U R The instantaneous terminal voltage of the current limiting unit is given by t, where t is the pre-charge time and m is the instantaneous terminal voltage. R For the quality of thermal stability resistance value, c p The specific heat capacity of a material is its thermal stability resistivity, which is the energy required to raise or lower the temperature of a unit mass of material by 1 degree Celsius. (T) R T0 is the temperature at which the thermal stability resistance value is measured at the end of the pre-charging process, and T0 is the initial temperature at which the thermal stability resistance value is measured at the beginning of the pre-charging process. MAX R5 represents the operating temperature limit of the thermal stability resistance value.

[0179] This can be understood as the maximum instantaneous terminal voltage of the current limiting unit being equal to the terminal voltage of the power battery, i.e., U. R,max =U B .

[0180] Therefore, the formula for the thermal stability resistance value R5 is:

[0181]

[0182] The thermal stability resistance value can be calculated based on the power battery system terminal voltage in the pre-charge characteristic information, the instantaneous terminal voltage of the current limiting unit in the current limiting unit characteristic information, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit in the current limiting unit temperature characteristic information. This allows for the selection of appropriate resistance type and specifications, and the determination of the thermal stability resistance value of the current limiting unit.

[0183] In one feasible implementation, step S202 may include steps C21 to C27:

[0184] Step C21: Obtain the instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the power safety factor, the power overload factor, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit.

[0185] It should be noted that the instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the power safety factor, the power overload factor, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit can be obtained by the information acquisition equipment.

[0186] Step C22: Determine the characteristic information of the current limiting unit based on the instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the power safety factor, and the power overload factor;

[0187] It should be noted that the current limiting unit characteristic information reflects the characteristics of the current limiting unit state during the pre-charging process.

[0188] Step C23: Determine the temperature characteristic information of the current limiting unit based on the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit;

[0189] It should be noted that the temperature characteristic information of the current limiting unit reflects the temperature characteristics of the current limiting unit during the pre-charging process.

[0190] Step C24: Construct the third loop model, the fourth loop model, and the fifth loop model based on the pre-charge characteristic information, pulse characteristic information, current limiting unit characteristic information, and current limiting unit temperature characteristic information;

[0191] It should be noted that the constructed third-loop model can calculate the pulse energy resistance value, which can assess the thermal stability and safety of the resistance under the worst conditions, such as reaching the battery voltage peak and the maximum number of pulses, to prevent resistor damage or system failure due to overheating. To ensure that the current limiting unit can still work normally under overload conditions and not be damaged by overheating, the constructed fourth-loop model can calculate the power overload resistance value, ensuring the thermal stability of the current limiting unit under power overload conditions and avoiding system failure due to overheating. For the current limiting unit actually used in the battery management system, it will absorb a large amount of energy in a short time during the pre-charging process, causing the temperature to rise rapidly. To ensure that the current limiting unit does not fail after 2-3 consecutive power-on pre-charging cycles, it is necessary to consider the instantaneous thermal response and thermal conduction characteristics of the resistance. To ensure that the current limiting unit can remain stable under continuous operation or high-temperature environment, the constructed fifth-loop model can calculate the thermal stability resistance value, thereby maintaining the performance of the current limiting unit under continuous operation or high-temperature environment and reducing the risk of failure due to thermal problems.

[0192] Step C25: Calculate the pulse energy resistance value based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time in the pre-charge characteristic information, the capacitor unit terminal voltage and capacitor unit capacitance value in the capacitor unit characteristic information, the pulse frequency and pulse interval time in the pulse characteristic information, the instantaneous terminal voltage and peak energy of the current limiting unit in the current limiting unit characteristic information, and the third circuit model.

[0193] It should be noted that calculating the pulse energy resistance value helps determine the maximum energy that the current limiting unit needs to withstand, thereby selecting the appropriate resistor type and specifications to ensure that the resistor can safely dissipate this energy during the pre-charging process.

[0194] Step C26: Calculate the rated power characteristic value and power overload resistance value based on the resistance condition information in the pre-charge characteristic information, the power safety factor and power overload factor in the power battery system terminal voltage and current limiting unit characteristic information, and the fourth circuit model.

[0195] It should be noted that calculating the power overload resistance value ensures the thermal stability of the current limiting unit under overload conditions, thus avoiding system failures caused by overheating.

[0196] Step C27: Calculate the thermal stability resistance value based on the power battery system terminal voltage, pre-charge time, instantaneous terminal voltage of the current limiting unit, mass of the current limiting unit, specific heat capacity of the current limiting unit material, target temperature of the current limiting unit, initial temperature of the current limiting unit, operating temperature limit of the current limiting unit, and the fifth loop model in the pre-charge characteristic information, and the current limiting unit temperature characteristic information.

[0197] It should be noted that the thermal stability resistance value is calculated to maintain the performance of the current limiting unit under continuous pulse or high temperature environments, thereby reducing the risk of failure due to thermal problems.

[0198] In another feasible implementation, step S202 may include steps D21 to D24:

[0199] Step D21: Calculate energy information based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time in the pre-charge characteristic information, the capacitor unit terminal voltage, capacitor unit capacitance value in the capacitor unit characteristic information, and the pulse frequency and pulse interval time in the pulse characteristic information. The energy information includes the energy supplied by the power battery and the energy stored in the capacitor unit.

[0200] It should be noted that the energy information reflects the characteristics of the energy generated by the pulse in the pre-charging circuit, including the energy supplied by the power battery and the energy stored in the capacitor unit.

[0201] Step D22: Calculate the pre-charge circuit pulse energy based on the energy supplied by the power battery and the energy stored in the capacitor unit;

[0202] It should be noted that calculating the pulse energy resistance value of the precharge circuit helps determine the maximum energy that the current limiting unit needs to withstand, thereby selecting the appropriate resistor type and specifications to ensure that the resistor can safely dissipate this energy during the precharge process.

[0203] Step D23: Determine the energy absorption state based on the pulse energy of the pre-charge circuit and the peak energy of the current limiting unit in the characteristic information of the current limiting unit, and obtain the determination result;

[0204] It should be noted that the judgment result reflects the characteristics of judging the energy absorption state during the pre-charging process.

[0205] Step D24: Select and determine the pulse energy resistance value based on the judgment result.

[0206] It should be noted that the judgment results reflect the characteristics of the target current limiting unit selected under different operating conditions.

[0207] Step S203: Based on the pre-charge circuit voltage, start-up safety resistor value, current balance resistor value, pulse energy resistor value, rated power characteristic value, power overload resistor value, and thermal stability resistor value, the target value of the current limiting unit resistor and the target value of the rated power are obtained.

[0208] It should be noted that the target values ​​of the current limiting unit resistance and rated power are determined based on the pre-charge circuit voltage, the start-up safety resistance value, the current balance resistance value, the pulse energy resistance value, the rated power characteristic value, the power overload resistance value, and the thermal stability resistance value, thereby accurately selecting the appropriate current limiting unit.

[0209] Understandably, since the pre-charging time is in the millisecond range (t≤200ms), it is necessary to pay attention to the instantaneous energy tolerance limit of the current limiting unit, i.e., the peak energy of the current limiting unit. The peak energy of the current limiting unit reflects the thermal response characteristics of the current limiting unit and can affect whether the current limiting unit can safely absorb the pulse energy of the pre-charging circuit. Based on the pre-charging circuit voltage, the starting safety resistance value, the current balance resistance value, the pulse energy resistance value, the rated power characteristic value, the power overload resistance value, and the thermal stability resistance value, the target resistance value and the target rated power value of the current limiting unit are determined. However, the actual working environment may vary, such as temperature fluctuations. Due to factors such as dynamics and load changes, the target current limiting unit may need to be dynamically selected based on the calculated target resistance value of the current limiting unit to adapt to different operating conditions. A safety threshold is set to select a target current limiting protection unit that fully meets the expected requirements, ensuring that the current limiting unit can operate safely even under the most unfavorable conditions and avoiding system failures caused by calculation errors or environmental changes. Environmental factors such as humidity, corrosive gases, and other factors that affect the performance and lifespan of resistor materials are considered. Under the premise of ensuring safety and performance, appropriate resistor materials and specifications are selected, and cost-effectiveness is considered to achieve the best balance between economy and reliability.

[0210] The current limiting unit selection method proposed in this embodiment determines the start-up safety resistance value and current balance resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and capacitor unit characteristic information; it determines the pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value based on the pre-charge circuit voltage, pre-charge characteristic information, and pulse characteristic information; and it determines the target resistance value and rated power value of the current limiting unit based on the pre-charge circuit voltage, start-up safety resistance value, current balance resistance value, pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value. This solves the technical problem of dynamically selecting the target resistance value of the current limiting unit when the pre-charge circuit operating conditions change. Compared with the prior art, this application can effectively avoid current surges and overheating problems by reasonably selecting the target resistance value of the current limiting unit, thereby improving the safety of the power battery system, adapting to different operating conditions and requirements, and improving the system's adaptability and flexibility.

[0211] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the current limiting unit selection method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0212] This application also provides a current limiting unit selection device; please refer to... Figure 6 , Figure 6 This is a schematic diagram of the module structure of the current limiting unit selection device according to an embodiment of this application. The current limiting unit selection device includes:

[0213] The acquisition module 10 is used to detect the pre-charge circuit voltage and determine the capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information based on the pre-charge circuit voltage.

[0214] Processing module 20 is used to determine the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, capacitor unit characteristic information, pre-charge characteristic information and pulse characteristic information;

[0215] The execution module 30 is used to select a target current limiting unit to control the power battery for pre-charging based on the target value of the current limiting unit resistance and the target value of the rated power.

[0216] The current limiting unit selection device provided in this application, employing the current limiting unit selection method in the above embodiments, can solve the technical problem of how to accurately select current limiting units. Compared with the prior art, the beneficial effects of the current limiting unit selection device provided in this application are the same as those of the current limiting unit selection method provided in the above embodiments, and other technical features in the current limiting unit selection device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0217] This application provides a current limiting unit selection device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the current limiting unit selection method in the above embodiment 1.

[0218] The following is for reference. Figure 7 The diagram illustrates a structural schematic suitable for implementing the current limiting unit selection device in the embodiments of this application. The current limiting unit selection device in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 7 The current limiting unit selection device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0219] like Figure 7As shown, the current limiting unit selection device may include a processing device 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1002 or a program loaded from storage device 1003 into random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the current limiting unit selection device. The processing device 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. The communication device 1009 allows the current limiting unit selection device to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows current limiting unit selection devices with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0220] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0221] The current limiting unit selection device provided in this application, employing the current limiting unit selection method described in the above embodiments, can solve the technical problem of how to accurately select current limiting units. Compared with the prior art, the beneficial effects of the current limiting unit selection device provided in this application are the same as those of the current limiting unit selection method provided in the above embodiments, and other technical features of this current limiting unit selection device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0222] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0223] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0224] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the current limiting unit selection method in the above embodiments.

[0225] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0226] The aforementioned computer-readable storage medium may be included in the current limiting unit selection device; or it may exist independently and not be assembled into the current limiting unit selection device.

[0227] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by the current limiting unit selection device, the current limiting unit selection device: detects the pre-charge circuit voltage and determines capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information based on the pre-charge circuit voltage; determines the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, the capacitor cell characteristic information, the pre-charge characteristic information, and the pulse characteristic information; and selects a target current limiting unit to control the power battery for pre-charging based on the target value of the current limiting unit resistance and the target value of the rated power.

[0228] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0229] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0230] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0231] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described current limiting unit selection method, thereby solving the technical problem of how to accurately select a current limiting unit. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the current limiting unit selection method provided in the above embodiments, and will not be repeated here.

[0232] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for selecting a current limiting unit, characterized in that, The current limiting unit selection method is applied to a pre-charging circuit, which includes a power battery, a main positive relay, a main negative relay, a pre-charging relay, a current limiting unit, a capacitor unit, and a load unit. The positive terminal of the power battery is connected to the first terminal of the main positive relay and the first terminal of the pre-charging relay. The second terminal of the pre-charging relay is connected to the first terminal of the current limiting unit. The second terminal of the main positive relay is connected to the second terminal of the current limiting unit, the first terminal of the capacitor unit, and the first terminal of the load unit. The second terminals of the capacitor unit and the load unit are both connected to the first terminal of the main negative relay. The second terminal of the main negative relay is connected to the negative terminal of the power battery. The method includes: The pre-charge circuit voltage is detected, and the capacitor cell characteristic information, pre-charge characteristic information, and pulse characteristic information are determined based on the pre-charge circuit voltage. The target value of the current limiting unit resistance and the target value of the rated power are determined based on the pre-charge circuit voltage, the capacitor unit characteristic information, the pre-charge characteristic information, and the pulse characteristic information. Based on the target value of the current limiting unit resistance and the target value of the rated power, a target current limiting unit is selected to control the power battery for pre-charging. The step of determining the capacitor cell characteristic information, precharge characteristic information, and pulse characteristic information based on the precharge circuit voltage includes: The following parameters are determined based on the pre-charge circuit voltage: capacitor unit terminal voltage, capacitor unit initial voltage, capacitor unit capacitance value, power battery system terminal voltage, pre-charge relay rated current, pre-charge circuit current, resistor operating condition information, pre-charge time, pulse frequency, and pulse interval time. The characteristic information of the capacitor unit is determined based on the terminal voltage of the capacitor unit, the initial voltage of the capacitor unit, and the capacitance value of the capacitor unit. Precharge characteristic information is determined based on the power battery system terminal voltage, the precharge relay rated current, the precharge circuit current, the resistor operating condition information, and the precharge time. Pulse characteristic information is determined based on the pulse frequency and the pulse interval time.

2. The method as described in claim 1, characterized in that, The step of determining the target value of the current limiting unit resistor and the target value of the rated power based on the pre-charge circuit voltage, the capacitor unit characteristic information, the pre-charge characteristic information, and the pulse characteristic information includes: The starting safety resistance value and the current balance resistance value are determined based on the pre-charge circuit voltage, the pre-charge characteristic information, and the capacitor unit characteristic information. The pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value are determined based on the pre-charge circuit voltage, the pre-charge characteristic information, and the pulse characteristic information. Based on the pre-charge circuit voltage, the start-up safety resistor value, the current balance resistor value, the pulse energy resistor value, the rated power characteristic value, the power overload resistor value, and the thermal stability resistor value, the target value of the current limiting unit resistor and the target value of the rated power are obtained.

3. The method as described in claim 2, characterized in that, The steps of determining the start-up safety resistance value and the current balance resistance value based on the pre-charge circuit voltage, the pre-charge characteristic information, and the capacitor unit characteristic information include: A first circuit model is constructed based on the pre-charge circuit voltage, the pre-charge characteristic information, and the capacitor unit characteristic information. A second circuit model is constructed based on the pre-charge circuit voltage and the pre-charge characteristic information; The starting safety resistance value is calculated based on the resistance condition information and the power battery system terminal voltage in the pre-charge feature information, the capacitor unit terminal voltage, the capacitor unit initial voltage, the capacitor unit capacitance value in the capacitor unit feature information, and the first circuit model. The current balance resistance value is calculated based on the resistance condition information, power battery system terminal voltage, precharge relay rated current, and the second circuit model in the precharge feature information.

4. The method as described in claim 2, characterized in that, The steps for determining the pulse energy resistance value, rated power characteristic value, power overload resistance value, and thermal stability resistance value based on the pre-charge circuit voltage, the pre-charge characteristic information, and the pulse characteristic information include: The instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the material of the current limiting unit, the power safety factor, the power overload factor, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit are obtained. The characteristic information of the current limiting unit is determined based on the instantaneous terminal voltage of the current limiting unit, the peak energy of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material, the power safety factor, and the power overload factor. The temperature characteristic information of the current limiting unit is determined based on the target temperature of the current limiting unit, the initial temperature of the current limiting unit, and the operating temperature limit of the current limiting unit. Based on the pre-charge characteristic information, the pulse characteristic information, the current limiting unit characteristic information, and the current limiting unit temperature characteristic information, a third loop model, a fourth loop model, and a fifth loop model are constructed. The pulse energy resistance value is calculated based on the power battery system terminal voltage, pre-charge circuit current, pre-charge time in the pre-charge feature information, the capacitor unit terminal voltage and capacitor unit capacitance value in the capacitor unit feature information, the pulse frequency and pulse interval time in the pulse feature information, the instantaneous terminal voltage and peak energy of the current limiting unit in the current limiting unit feature information, and the third circuit model. Based on the resistance condition information in the pre-charge characteristic information, the terminal voltage of the power battery system, the power safety factor and power overload factor in the current limiting unit characteristic information, and the fourth circuit model, the rated power characteristic value and the power overload resistance value are calculated. The thermal stability resistance value is calculated based on the power battery system terminal voltage and pre-charge time in the pre-charge characteristic information, the instantaneous terminal voltage of the current limiting unit, the mass of the current limiting unit, the specific heat capacity of the current limiting unit material in the current limiting unit characteristic information, the target temperature of the current limiting unit, the initial temperature of the current limiting unit, the operating temperature limit of the current limiting unit in the current limiting unit temperature characteristic information, and the fifth loop model.

5. The method as described in claim 4, characterized in that, The method further includes: Energy information is calculated based on the power battery system terminal voltage, pre-charge circuit current, and pre-charge time in the pre-charge feature information, the capacitor unit terminal voltage and capacitor unit capacitance value in the capacitor unit feature information, and the pulse frequency and pulse interval time in the pulse feature information. The energy information includes the energy supplied by the power battery and the energy stored by the capacitor unit. The precharge circuit pulse energy is calculated based on the energy supplied by the power battery and the energy stored in the capacitor unit. The energy absorption state is determined based on the pulse energy of the pre-charge circuit and the peak energy of the current limiting unit in the characteristic information of the current limiting unit, and the determination result is obtained. Based on the judgment result, the pulse energy resistance value is selected and determined.

6. The method as described in claim 4, characterized in that, The method further includes: The peak power of the current limiting unit is determined based on the power battery system terminal voltage and resistance operating condition information in the pre-charge feature information. The rated power characteristic value is determined based on the power safety factor, power overload factor, and peak power of the current limiting unit in the characteristic information of the current limiting unit. Based on the rated power characteristic value and the power safety factor and power overload factor in the current limiting unit characteristic information, the power overload state is determined and the determination result is obtained. Based on the judgment result, the power overload resistor value is selected and determined.

7. The method as described in claim 1, characterized in that, The method is applied to a current limiting unit selection device, the device comprising: The acquisition module is used to detect the pre-charge circuit voltage and determine the capacitor cell characteristic information, pre-charge characteristic information and pulse characteristic information based on the pre-charge circuit voltage; The processing module is used to determine the target value of the current limiting unit resistance and the target value of the rated power based on the pre-charge circuit voltage, the capacitor unit characteristic information, the pre-charge characteristic information and the pulse characteristic information; The execution module is used to select a target current limiting unit to control the power battery to precharge based on the target value of the current limiting unit resistance and the target value of the rated power. The acquisition module is also used to determine the capacitor unit terminal voltage, capacitor unit initial voltage, capacitor unit capacitance value, power battery system terminal voltage, precharge relay rated current, precharge circuit current, resistor operating condition information, precharge time, pulse frequency, and pulse interval time based on the precharge circuit voltage. The characteristic information of the capacitor unit is determined based on the terminal voltage of the capacitor unit, the initial voltage of the capacitor unit, and the capacitance value of the capacitor unit. Precharge characteristic information is determined based on the power battery system terminal voltage, the precharge relay rated current, the precharge circuit current, the resistor operating condition information, and the precharge time. Pulse characteristic information is determined based on the pulse frequency and the pulse interval time.

8. A current limiting unit selection device, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the current limiting unit selection method as described in any one of claims 1 to 6.

9. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the current limiting unit selection method as described in any one of claims 1 to 6.

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