Battery pack high-voltage electrical system capable of adjusting current

Abstract

The invention provides a battery pack high-voltage electrical system capable of adjusting current magnitude, which belongs to the technical field of power supplies, and comprises a power battery pack used for storing or releasing electric energy; the integrated BDU is used for communicating an external power supply with the power battery pack in the charging process of the power battery pack; or in the discharging process of the power battery pack, the power battery pack is communicated with the load; the execution unit is used for adjusting the multiplying power of the input current and the output current of the integrated BDU; the monitoring unit is arranged on the execution unit and the integrated BDU and is used for acquiring current temperature and current signals of the execution unit and the integrated BDU; and the control unit is electrically connected with the monitoring unit and the integrated BDU, acquires the current temperature and current signals acquired by the monitoring unit, judges whether the surface temperature rise of the integrated BDU under the current current condition is higher than a set value or not, and adjusts the multiplying power of the input current and the output current of the current integrated BDU, or adjusts the current state of the execution unit.

Description

Technical Field

[0001] The present invention relates to the field of power supply technology, and in particular to a battery pack high-voltage electrical system capable of adjusting current. Background Art

[0002] At present, the battery packs designed and manufactured by battery pack manufacturers on the market are divided into two major areas: the cell arrangement area and the electrical layout area. With the increasing number of new energy vehicles, the requirements for battery packs are also getting higher and higher, which are mainly reflected in the following aspects: 1. Under the condition of the fixed boundary area where the battery pack is installed in the whole vehicle, the battery pack is required to have enough power to maximize the vehicle's range; 2. Under the condition of the fixed boundary area where the battery pack is installed in the whole vehicle, the battery pack space utilization rate is required to be large enough to maximize the battery pack mass energy density and cell grouping efficiency; 3. Under the condition of the fixed boundary area where the battery pack is installed in the whole vehicle, the battery pack is required to have a higher rate fast charging capability to shorten the fast charging time as much as possible, reduce the waiting time for charging, and improve the end-user experience.

[0003] Under such requirements, the following problems will arise when designing the battery pack: 1. Impact on the reliability of high-voltage electrical components: When the battery pack requires a larger charging rate, the current passing through the high-voltage electrical components is large. Excessive current frequently passes through the high-voltage electrical components, causing the high-voltage electrical components to heat up, which will affect the reliability and life of the high-voltage electrical components; 2. Impact on the layout inside the battery pack: When the battery pack requires a larger charging rate, the current passing through the high-voltage electrical components is large. Due to the characteristics of the electrical components, the size of the electrical components is large and requires a corresponding electrical layout area to be placed, which causes the battery cell arrangement area to be compressed, reducing the energy density and total power of the battery pack.

[0004] Therefore, it is necessary to provide a high-voltage electrical system for a battery pack with adjustable current. When the battery pack requires a higher charge / discharge rate, it is necessary to reduce the current passing through the high-voltage electrical components, reduce the heat generation, and extend the service life of the high-voltage electrical components. At the same time, it is necessary to select smaller high-voltage electrical components so that the internal space of the battery pack can be effectively used for battery cell arrangement, thereby increasing the total power and energy density of the battery pack. Summary of the invention

[0005] In view of this, the present invention proposes a battery pack high-voltage electrical system that can adjust the real-time working current of the integrated BDU, reduce the heat dissipation volume and occupied space of the high-voltage devices, and thus increase the energy density of the battery pack and the number of battery cells arranged.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a battery pack high voltage electrical system with adjustable current, comprising:

[0007] Power battery pack, used to store or release electrical energy;

[0008] The integrated BDU is used to connect the external power source to the power battery pack during the charging process of the power battery pack; or to connect the power battery pack to the load during the discharging process of the power battery pack;

[0009] An execution unit is arranged between the integrated BDU and the external power supply, between the integrated BDU and the power battery pack, and between the integrated BDU and the load, and is electrically connected to the integrated BDU, the power battery pack, the load or the external power supply, respectively, and is used to adjust the multiple of the input current and the output current of the integrated BDU;

[0010] A monitoring unit, which is arranged on the execution unit and the integrated BDU, and is used to obtain current temperature and current signals of the execution unit and the integrated BDU;

[0011] The control unit is electrically connected to the monitoring unit and the integrated BDU, obtains the current temperature and current signals collected by the monitoring unit, determines whether the surface temperature rise of the integrated BDU under the current current conditions is higher than the set value, adjusts the input current and output current multipliers of the current integrated BDU, or adjusts the current working state of the execution unit.

[0012] On the basis of the above technical solution, preferably, the execution unit includes a first converter module, a second converter module and a third converter module, the first converter module is arranged between the power battery pack and the first connection end of the integrated BDU, and is electrically connected to the power battery pack and the integrated BDU respectively; the second converter module is arranged between the integrated BDU and the external power supply, and is electrically connected to the integrated BDU and the external power supply respectively; the third converter module is arranged between the integrated BDU and the load, and is electrically connected to the integrated BDU and the load respectively;

[0013] During the charging phase of the power battery pack, the third converter module is disconnected, and the external power source is electrically connected to the second converter module, the integrated BDU, the first converter module and the power battery pack in sequence;

[0014] During the discharge phase of the power battery pack, the second converter module is disconnected, and the power battery pack is electrically connected to the first converter module, the integrated BDU, the third converter module and the load in sequence.

[0015] Preferably, the integrated BDU includes a main positive relay, a pre-charge relay, a main negative relay, a charging interface and a discharging interface; one end of the coil of the main positive relay, one end of the coil of the pre-charge relay and the positive electrode of the power battery pack are electrically connected to one end of the first converter module, and one end of the coil of the main negative relay and the negative electrode of the power battery pack are electrically connected to the other end of the first converter module; the first converter module is electrically connected to the positive electrode or the negative electrode of the power battery pack through a connecting bar;

[0016] The other end of the coil of the pre-charging relay and one end of the charging interface are electrically connected to one end of the second converter module respectively, and the other end of the second converter module is electrically connected to the other end of the charging interface and the other end of the coil of the main negative relay respectively;

[0017] The other end of the coil of the main positive relay and one end of the discharge interface are both electrically connected to one end of the third converter module, and the other end of the discharge interface and the other end of the coil of the main negative relay are both electrically connected to the other end of the third converter module; the third converter module is electrically connected to the discharge interface through a connecting bar;

[0018] During the power battery pack charging phase, the charging interface, the second converter module, the pre-charging relay, the first converter module, the power battery pack and the main negative relay form a circuit;

[0019] During the discharging stage of the power battery pack, the power battery pack, the first converter module, the main positive relay, the third converter module, the discharge interface and the main negative relay form a loop.

[0020] Further preferably, a main positive fuse is provided between one end of the coil of the main positive relay close to the power battery pack and the first converter module, and a charging fuse is provided between one end of the coil of the main negative relay away from the power battery pack and the second converter module.

[0021] Further preferably, the monitoring unit includes a chip temperature sensor and a Hall current sensor. The chip temperature sensor is arranged at the input and output ends of the first converter module, the second converter module and the third converter module, and at each relay of the integrated BDU, for obtaining the current temperature signal; the Hall current sensor is arranged in the loop of the charging stage or the loop of the discharging stage of the power battery pack, for obtaining the input and output ends of the first converter module, the second converter module and the third converter module, and the current current signal inside the integrated BDU; the current temperature signal and the current current signal are both fed back to the control unit.

[0022] Further preferably, the control unit imports the charging MAP diagram and the discharging MAP diagram of the power battery pack, and the control unit also records the position of the execution unit and the integrated BDU generating the maximum current during the charging stage or the discharging stage of the power battery pack; the control unit compares the current carrying capacity of each device in the integrated BDU, and takes the maximum overcurrent capacity of the device with the lowest current carrying capacity in the integrated BDU and the execution unit as the safe current carrying value Imax, determines the relationship between the current current and the temperature rise of each device in the loop, and gives the scaling ratio of the current before it is sent to the integrated BDU, and the current amplification ratio after passing through the integrated BDU, and the control unit monitors the temperature change of each device in the loop: 1) If the temperature change of each device in the integrated BDU under the current current scaling ratio does not exceed the limit value, the current scaling ratio is maintained; 2) If the temperature change of any device in the integrated BDU under the current current scaling ratio exceeds the limit value, the control unit further lowers the current scaling ratio; 3) In the current amplification recovery link, if the current of any converter module reaches a certain multiple of the safe current carrying value Imax, the converter module is disconnected to form an open circuit.

[0023] More preferably, the temperature change of each device in the integrated BDU under the current current scaling ratio satisfies the following relationship: 2 Rt=h×S×ΔT, where I represents the current flowing through each component of the integrated BDU, R represents the equivalent resistance of each component of the integrated BDU, t represents the current working time, h represents the heat dissipation coefficient, S represents the heat dissipation area, and ΔT represents the temperature difference between the surface temperature of each component of the integrated BDU and the ambient temperature; let the area of ​​the electrical layout area in the battery pack be A, satisfying A=S+λL T +C, where λ represents the space volume coefficient, L T represents the sum of the surface areas of the connected rows, C is a constant, and the combined formulas give That is, when the area of ​​the electrical layout area and the size of the connection bar are known, the current current I flowing through each device of the integrated BDU is correspondingly adjusted according to the area A of the current electrical layout area to obtain the scaling ratio range of the current current.

[0024] Still further preferably, the control unit monitors the temperature change of each device in the loop, including calculating the temperature change rate of any device in the integrated BDU according to the following formula: Where m is the mass of any device in the integrated BDU, and c is the specific heat capacity of any device in the integrated BDU. The control unit also makes judgments based on the following rules: 1) The temperature change rate of any device in the integrated BDU If the current temperature of any device in the integrated BDU is lower than 70% of the maximum allowable operating temperature, the control unit maintains the current current scaling ratio of the execution unit unchanged; 2) The temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 70% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit and continue to observe whether the temperature change rate of any device in the integrated BDU decreases. If the temperature change rate of the device decreases to If the current scaling ratio is maintained, the current scaling ratio is further reduced until the device temperature change rate drops to 3) Temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 85% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit to the minimum and shorten the sampling interval of the monitoring unit. If the temperature change rate of the device or the current temperature does not drop within a period of time, the relay of the integrated BDU will be immediately turned off.

[0025] More preferably, when the control unit reduces the current scaling ratio of the execution unit, the reduction amplitude each time is 5%-10% of the rated operating current of the integrated BDU.

[0026] Further preferably, in the current amplification and recovery link, if the current of any converter module reaches a certain multiple of the safe current-carrying value Imax, the converter module is disconnected to form an open circuit, which means that in the current amplification and recovery link, when the current of the converter module in use reaches more than 1.1 times the safe current-carrying value Imax, the normally closed relay built into the converter module is disconnected to prevent overcurrent in the circuit.

[0027] The invention provides a battery pack high-voltage electrical system with adjustable current, which has the following beneficial effects compared with the prior art:

[0028] (1) By rationally utilizing the internal space of the battery pack, selecting the appropriate operating current of the high-voltage electrical components and the installation space with matching heat dissipation capacity, the heat generation of the high-voltage electrical components can be reduced, and the service life and reliability of the high-voltage electrical components can be improved. By changing the selection of high-voltage components, the volume of the electrical layout area can be optimized, freeing up more space for installing battery cells, thereby improving the energy density and competitiveness of the battery pack;

[0029] (2) By real-time monitoring of the temperature rise degree and actual temperature after the integrated BDU reduces the current rate, as well as the current current of the execution unit after the current rate is restored, the temperature change rate of each component in the electrical circuit is kept low within the allowable safety range, thereby achieving long-term reliable operation of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is an electrical structure block diagram of a high-voltage electrical system of a battery pack capable of adjusting current size according to the present invention;

[0032] Figure 2 A schematic diagram of a variable current adjustment strategy for a high-voltage electrical system of a battery pack capable of adjusting current size according to the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] When the battery pack requires a higher charging rate, the current passing through the high-voltage electrical components is relatively large. Due to the characteristics of electrical components, the size of the electrical components is large and requires a corresponding electrical layout area to be placed, which results in the cell arrangement area being compressed and reduces the energy density of the battery pack. Figure 1 As shown, the present invention provides a battery pack high voltage electrical system with adjustable current, comprising:

[0035] Power battery pack, used to store or release electrical energy;

[0036] The integrated BDU is used to connect the external power source to the power battery pack during the charging process of the power battery pack; or to connect the power battery pack to the load during the discharging process of the power battery pack;

[0037] The execution unit is arranged between the integrated BDU and the external power supply, between the integrated BDU and the power battery pack, and between the integrated BDU and the load, and is electrically connected to the integrated BDU, the power battery pack, the load or the external power supply, respectively, and is used to adjust the multiples of the input current and output current of the integrated BDU. In this embodiment, the execution unit includes a first converter module, a second converter module and a third converter module. The first converter module is arranged between the power battery pack and the first connection end of the integrated BDU, and is electrically connected to the power battery pack and the integrated BDU respectively; the second converter module is arranged between the integrated BDU and the external power supply, and is electrically connected to the integrated BDU and the external power supply respectively; the third converter module is arranged between the integrated BDU and the load, and is electrically connected to the integrated BDU and the load respectively. In actual use, two identical converters can be configured at the first converter module, the second converter module and the third converter module, respectively, to realize one use and one standby, or to perform current diversion when used simultaneously.

[0038] During the charging phase of the power battery pack, the third converter module is disconnected, and the external power source is electrically connected to the second converter module, the integrated BDU, the first converter module and the power battery pack in sequence;

[0039] During the discharge phase of the power battery pack, the second converter module is disconnected, and the power battery pack is electrically connected to the first converter module, the integrated BDU, the third converter module and the load in sequence.

[0040] A monitoring unit, which is arranged on the execution unit and the integrated BDU, and is used to obtain current temperature and current signals of the execution unit and the integrated BDU;

[0041] The control unit is electrically connected to the monitoring unit and the integrated BDU, obtains the current temperature and current signals collected by the monitoring unit, determines whether the surface temperature rise of the integrated BDU under the current current conditions is higher than the set value, adjusts the input current and output current multipliers of the current integrated BDU, or adjusts the current working state of the execution unit.

[0042] Because the operating current can be adjusted, the high-voltage components inside the integrated BDU can be selected according to smaller sizes or specifications, thereby optimizing the volume of the electrical layout area and freeing up more space for installing battery cells. It is only necessary to fully consider the overcurrent capacity of the execution unit.

[0043] like Figure 1As shown, in the present invention, the integrated BDU includes a main positive relay, a pre-charge relay, a main negative relay, a charging interface and a discharging interface; one end of the coil of the main positive relay, one end of the coil of the pre-charge relay and the positive electrode of the power battery pack are electrically connected to one end of the first converter module, and one end of the coil of the main negative relay and the negative electrode of the power battery pack are electrically connected to the other end of the first converter module; the first converter module is electrically connected to the positive electrode or the negative electrode of the power battery pack through a connecting bar;

[0044] The other end of the coil of the pre-charging relay and one end of the charging interface are electrically connected to one end of the second converter module respectively, and the other end of the second converter module is electrically connected to the other end of the charging interface and the other end of the coil of the main negative relay respectively;

[0045] The other end of the coil of the main positive relay and one end of the discharge interface are both electrically connected to one end of the third converter module, and the other end of the discharge interface and the other end of the coil of the main negative relay are both electrically connected to the other end of the third converter module; the third converter module is electrically connected to the discharge interface through a connecting bar;

[0046] During the power battery pack charging phase, the charging interface, the second converter module, the pre-charging relay, the first converter module, the power battery pack and the main negative relay form a circuit;

[0047] During the discharging stage of the power battery pack, the power battery pack, the first converter module, the main positive relay, the third converter module, the discharge interface and the main negative relay form a loop.

[0048] In order to prevent overcurrent and protect the circuit, a main positive fuse is arranged between one end of the coil of the main positive relay close to the power battery pack and the first converter module, and a charging fuse is arranged between one end of the coil of the main negative relay away from the power battery pack and the second converter module.

[0049] In the present invention, the monitoring unit includes a chip temperature sensor and a Hall current sensor. The chip temperature sensor is arranged at the input and output ends of the first converter module, the second converter module and the third converter module, and at each relay of the integrated BDU, so as to obtain the current temperature signal; the Hall current sensor is arranged in the circuit of the charging stage or the circuit of the discharging stage of the power battery pack, so as to obtain the input and output ends of the first converter module, the second converter module and the third converter module, and the current current signal inside the integrated BDU; the current temperature signal and the current current signal are both fed back to the control unit.

[0050] When the current is about to flow into the integrated BDU, the execution unit will reduce the current sent to the integrated BDU by a certain proportion. Under the premise of ensuring the normal and reliable operation of the integrated BDU, the current current flows smoothly through the integrated BDU. The heat generated by the integrated BDU at the current current is also small, and the required heat dissipation space is also small. After the current current flows out of the integrated BDU, in order to meet the needs of high-current fast charging or load carrying, the execution unit needs to restore the current current again by the reverse operation of the reduction ratio. This realizes the complete process of proportional reduction or amplification of the current.

[0051] like Figure 2 As shown, Figure 2 The control unit variable current adjustment strategy is demonstrated. The control unit imports the charging MAP diagram and the discharging MAP diagram of the power battery pack. The control unit also records the location of the maximum current generated by the execution unit and the integrated BDU during the charging or discharging stage of the power battery pack; the control unit compares the current carrying capacity of each device in the integrated BDU, and takes the maximum overcurrent capacity of the device with the lowest current carrying capacity in the integrated BDU and the execution unit as the safe current carrying value Imax, determines the relationship between the current and the temperature rise of each device in the loop, and gives the current scaling ratio before entering the integrated BDU, and the current amplification ratio after passing through the integrated BDU. At the same time, the control unit monitors the temperature changes of each device in the loop: 1) If the temperature change of each device in the integrated BDU does not exceed the limit value at the current current scaling ratio, the current current scaling ratio is maintained; 2) If the temperature change of any device in the integrated BDU exceeds the limit value at the current current scaling ratio, the control unit further lowers the current scaling ratio; 3) In the current amplification recovery link, if the current of any converter module reaches a certain multiple of the safe current carrying value Imax, the converter module is disconnected to form an open circuit.

[0052] The temperature change of each device in the integrated BDU under the current scaling ratio satisfies the following relationship: I 2 Rt=h×S×ΔT, where I represents the current flowing through each component of the integrated BDU, R represents the equivalent resistance of each component of the integrated BDU, t represents the current working time, h represents the heat dissipation coefficient, S represents the heat dissipation area, and ΔT represents the temperature difference between the surface temperature of each component of the integrated BDU and the ambient temperature; let the area of ​​the electrical layout area in the battery pack be A, satisfying A=S+λL T +C, where λ represents the space volume coefficient, L T represents the sum of the surface areas of the connected rows, C is a constant, and the combined formulas give That is, when the area of ​​the electrical layout area and the size of the connection row are known, the current current I flowing through each device of the integrated BDU is correspondingly adjusted according to the area A of the current electrical layout area to obtain the scaling range of the current current I.

[0053] From the perspective of electromagnetics, the electromagnetic attraction of the integrated BDU relay is proportional to the square of the current, and the electromagnetic attraction is related to the cross-sectional area of ​​magnetic conductive materials such as the iron core. Generally speaking, the larger the volume, the more magnetic conductive materials and coils can be accommodated. Under the same material and structure, it has a greater electromagnetic attraction and can carry a larger current. The volume of each relay of the integrated BDU is also proportional to the electromagnetic attraction. It can be deduced that the volume of each relay is proportional to the square of the current current; according to the heat dissipation principle, the current passing through the conductor will generate heat. The larger the volume of the relay, the larger the heat dissipation area S. It can be seen that the heat dissipation area is also proportional to the volume of the relay. According to the relationship between the heat dissipation capacity matching, that is, the volume of the relay matches the heat generated by the working current, it can be deduced that the formula I 2 Rt=h×S×ΔT. The scaling ratio range of the current current can be obtained based on the change of the area A0 of the electrical layout area under the initial design conditions and the area A of the current electrical layout area.

[0054] The control unit monitors the temperature change of each device in the loop, including calculating the temperature change rate of any device in the integrated BDU according to the following formula: Where m is the mass of any device in the integrated BDU, and c is the specific heat capacity of any device in the integrated BDU. The control unit also makes judgments based on the following rules: 1) The temperature change rate of any device in the integrated BDU If the current temperature of any device in the integrated BDU is lower than 70% of the maximum allowable operating temperature, the control unit maintains the current current scaling ratio of the execution unit unchanged; 2) The temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 70% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit. Here, when the control unit reduces the current scaling ratio of the execution unit, the reduction amplitude is 5%-10% of the rated operating current of the integrated BDU each time; the control unit continues to observe whether the temperature change rate of any device in the integrated BDU decreases. If the temperature change rate of the device decreases to If the current scaling ratio is maintained, the current scaling ratio is further reduced until the device temperature change rate drops to 3) Temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 85% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit to the minimum and shorten the sampling interval of the monitoring unit. If the temperature change rate of the device or the current temperature has not dropped within a period of time, the relay of the integrated BDU will be immediately turned off. From the above content, it can be seen that the control unit obtains the change of the surface temperature of any device in the integrated BDU under the current working current in real time. If the surface temperature of any device rises abnormally, it is necessary to adjust the current working current to suppress the temperature rise rate, or stop the integrated BDU from working, so as not to exceed the reliable working temperature and bring safety hazards.

[0055] Among them, in the current amplification and recovery link, if the current of any converter module reaches a certain multiple of the safe current-carrying value Imax, the converter module is disconnected to form an open circuit. This means that in the current amplification and recovery link, when the current of the converter module put into use reaches more than 1.1 times the safe current-carrying value Imax, the normally closed relay built into the converter module is disconnected to prevent overcurrent in the circuit.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery pack high voltage electrical system with adjustable current, characterized in that: include: Power battery pack, used to store or release electrical energy; The integrated BDU is used to connect the external power source to the power battery pack during the charging process of the power battery pack; or to connect the power battery pack to the load during the discharging process of the power battery pack; An execution unit is arranged between the integrated BDU and the external power supply, between the integrated BDU and the power battery pack, and between the integrated BDU and the load, and is electrically connected to the integrated BDU, the power battery pack, the load or the external power supply, respectively, and is used to adjust the multiple of the input current and the output current of the integrated BDU; A monitoring unit, which is arranged on the execution unit and the integrated BDU, and is used to obtain current temperature and current signals of the execution unit and the integrated BDU; The control unit is electrically connected to the monitoring unit and the integrated BDU, obtains the current temperature and current signals collected by the monitoring unit, determines whether the surface temperature rise of the integrated BDU under the current current conditions is higher than the set value, adjusts the input current and output current multipliers of the current integrated BDU, or adjusts the current working state of the execution unit.

2. A battery pack high voltage electrical system with adjustable current according to claim 1, characterized in that: The execution unit includes a first converter module, a second converter module and a third converter module, wherein the first converter module is arranged between the power battery pack and the first connection end of the integrated BDU, and is electrically connected to the power battery pack and the integrated BDU respectively; the second converter module is arranged between the integrated BDU and the external power supply, and is electrically connected to the integrated BDU and the external power supply respectively; the third converter module is arranged between the integrated BDU and the load, and is electrically connected to the integrated BDU and the load respectively; During the charging phase of the power battery pack, the third converter module is disconnected, and the external power source is electrically connected to the second converter module, the integrated BDU, the first converter module and the power battery pack in sequence; During the discharge phase of the power battery pack, the second converter module is disconnected, and the power battery pack is electrically connected to the first converter module, the integrated BDU, the third converter module and the load in sequence.

3. A battery pack high voltage electrical system with adjustable current according to claim 2, characterized in that: The integrated BDU includes a main positive relay, a pre-charge relay, a main negative relay, a charging interface and a discharging interface; one end of the coil of the main positive relay, one end of the coil of the pre-charge relay and the positive electrode of the power battery pack are electrically connected to one end of the first converter module, and one end of the coil of the main negative relay and the negative electrode of the power battery pack are electrically connected to the other end of the first converter module; the first converter module is electrically connected to the positive electrode or the negative electrode of the power battery pack through a connecting bar; The other end of the coil of the pre-charging relay and one end of the charging interface are electrically connected to one end of the second converter module respectively, and the other end of the second converter module is electrically connected to the other end of the charging interface and the other end of the coil of the main negative relay respectively; The other end of the coil of the main positive relay and one end of the discharge interface are both electrically connected to one end of the third converter module, and the other end of the discharge interface and the other end of the coil of the main negative relay are both electrically connected to the other end of the third converter module; the third converter module is electrically connected to the discharge interface through a connecting bar; During the power battery pack charging phase, the charging interface, the second converter module, the pre-charging relay, the first converter module, the power battery pack and the main negative relay form a circuit; During the discharging stage of the power battery pack, the power battery pack, the first converter module, the main positive relay, the third converter module, the discharge interface and the main negative relay form a loop.

4. A battery pack high voltage electrical system with adjustable current according to claim 3, characterized in that: A main positive fuse is also provided between one end of the coil of the main positive relay close to the power battery pack and the first converter module, and a charging fuse is provided between one end of the coil of the main negative relay away from the power battery pack and the second converter module.

5. A battery pack high voltage electrical system with adjustable current according to claim 3, characterized in that: The monitoring unit includes a chip temperature sensor and a Hall current sensor. The chip temperature sensor is arranged at the input and output ends of the first converter module, the second converter module and the third converter module, and at each relay of the integrated BDU, and is used to obtain the current temperature signal; the Hall current sensor is arranged in the circuit of the charging stage or the circuit of the discharging stage of the power battery pack, and is used to obtain the input and output ends of the first converter module, the second converter module and the third converter module, and the current current signal inside the integrated BDU; the current temperature signal and the current current signal are both fed back to the control unit.

6. A battery pack high voltage electrical system with adjustable current according to claim 3, characterized in that: The control unit imports the charging MAP diagram and the discharging MAP diagram of the power battery pack. The control unit also records the location of the maximum current generated by the execution unit and the integrated BDU during the charging stage or the discharging stage of the power battery pack; the control unit compares the current carrying capacity of each device in the integrated BDU, and takes the maximum overcurrent capacity of the device with the lowest current carrying capacity in the integrated BDU and the execution unit as the safe current carrying value Imax, determines the relationship between the current and the temperature rise of each device in the loop, and gives the current scaling ratio before being sent to the integrated BDU, and the current amplification ratio after passing through the integrated BDU. At the same time, the control unit monitors the temperature changes of each device in the loop: 1) If the temperature change of each device in the integrated BDU under the current current scaling ratio does not exceed the limit value, the current scaling ratio is maintained; 2) If the temperature change of any device in the integrated BDU exceeds the limit value under the current scaling ratio, the control unit will further lower the current scaling ratio; 3) In the current amplification and recovery link, if the current of any converter module reaches a certain multiple of the safe current carrying value Imax, the converter module is disconnected to form an open circuit.

7. A battery pack high voltage electrical system with adjustable current according to claim 6, characterized in that: The temperature change of each device in the integrated BDU under the current scaling ratio satisfies the following relationship: I 2 Rt=h×S×ΔT, where I represents the current flowing through each component of the integrated BDU, R represents the equivalent resistance of each component of the integrated BDU, t represents the current working time, h represents the heat dissipation coefficient, S represents the heat dissipation area, and ΔT represents the temperature difference between the surface temperature of each component of the integrated BDU and the ambient temperature; let the area of ​​the electrical layout area in the battery pack be A, satisfying A=S+λL T +C, where λ represents the space volume coefficient, L T represents the sum of the surface areas of the connected rows, C is a constant, and the combined formulas give That is, when the area of ​​the electrical layout area and the size of the connection bar are known, the current current I flowing through each device of the integrated BDU is correspondingly adjusted according to the area A of the current electrical layout area to obtain the scaling ratio range of the current current.

8. A battery pack high voltage electrical system with adjustable current according to claim 7, characterized in that: The control unit monitors the temperature change of each device in the loop, including calculating the temperature change rate of any device in the integrated BDU according to the following formula: Where m is the mass of any device in the integrated BDU, and c is the specific heat capacity of any device in the integrated BDU. The control unit also makes judgments based on the following rules: 1) The temperature change rate of any device in the integrated BDU If the current temperature of any device in the integrated BDU is lower than 70% of the maximum allowable operating temperature, the control unit maintains the current current scaling ratio of the execution unit unchanged; 2) Temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 70% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit and continue to observe whether the temperature change rate of any device in the integrated BDU decreases. If the temperature change rate of the device decreases to If the current scaling ratio is maintained, the current scaling ratio is further reduced until the device temperature change rate drops to 3) Temperature change rate of any device in the integrated BDU Or if the current temperature of any device in the integrated BDU is not lower than 85% of the maximum allowable operating temperature, the control unit will reduce the current scaling ratio of the execution unit to the minimum and shorten the sampling interval of the monitoring unit. If the temperature change rate of the device or the current temperature does not drop within a period of time, the relay of the integrated BDU will be immediately turned off.

9. A battery pack high voltage electrical system with adjustable current according to claim 8, characterized in that: When the control unit reduces the current scaling ratio of the execution unit, the reduction range each time is 5%-10% of the rated working current of the integrated BDU.

10. A battery pack high voltage electrical system with adjustable current according to claim 6, characterized in that: In the current amplification and recovery link, if the current of any converter module reaches a certain multiple of the safe current-carrying value Imax, the converter module is disconnected to form an open circuit. This means that in the current amplification and recovery link, when the current of the converter module put into use reaches more than 1.1 times the safe current-carrying value Imax, the normally closed relay built into the converter module is disconnected to prevent overcurrent in the circuit.

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