CN113071319B

CN113071319B - High-voltage switching control method for power battery of new energy automobile

Info

Publication number: CN113071319B
Application number: CN202110472744.3A
Authority: CN
Inventors: 万应兵; 李晓依; 李康; 张旭; 刘爽
Original assignee: Dongfeng Motor Corp
Current assignee: Dongfeng Motor Corp
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2022-12-23
Anticipated expiration: 2041-04-29
Also published as: CN113071319A

Abstract

The invention relates to the technical field of power batteries, in particular to a high-voltage switching control method for a power battery of a new energy automobile. After receiving a power-on instruction of the whole vehicle, sequentially judging whether the sum V0 of the cell voltages of the battery pack is equal to the inner side voltage V1, whether the sum V0 meets the conditions that Vprecision is more than or equal to 0 and less than or equal to (V0-V1), more than or equal to Vprecision and is more than or equal to 0 and less than or equal to V3 and less than or equal to Vprecision, and whether high-level faults do not exist, if yes, driving an accessory relay to be closed and driving a pre-charging relay to be closed; judging whether Vprecision is satisfied, wherein V1-V3 is more than or equal to 0 and less than or equal to Vprecision, and if yes, driving the main and negative relays to be closed; after the pre-charging is finished, driving the main positive relay to be closed and driving the pre-charging relay to be disconnected; and judging whether the absolute value of V1-V3 is less than or equal to Vprecision and continuously reaching a set period, and if so, sending a high-voltage connection signal to the whole vehicle. Based on each relay, a high-voltage power-on process with a reasonable time sequence is provided, and the dangers that the relay adhesion, the pre-charging failure, the pre-charging explosion, the pre-charging short circuit, the high-voltage component damage, the whole vehicle losing control, threatening safety and the like caused by unreasonable time sequence control are prevented.

Description

High-voltage switching control method for power battery of new energy automobile

Technical Field

The invention relates to the technical field of power batteries, in particular to a high-voltage switching control method for a power battery of a new energy automobile.

Background

A new energy automobile (NEV-new energy vehicle) power battery is a power source spring of a whole automobile, and has important significance for accurate energy control and safety protection of the power battery on the safety of the whole automobile. Due to complex working conditions and various uncertainties in the driving process of a new energy automobile, how to accurately control energy switching of the new energy automobile, guarantee that the whole automobile has high voltage up and down in normal and various abnormal states, control the cut-off of a high-voltage system, and protect high-voltage devices of a power battery (a power battery cell-prevents over-charge and over-discharge, a relay-prevents relay adhesion and other hazards caused by switching under large current) have important research value.

Accurate, safe, stable power switching can protect electric core (prevent that the overcharge is put the fire excessively), also can postpone electric core life-span, and whole car safety is protected (prevent that whole car is out of control), and accurate switching power under the abnormal condition, and the high pressure of safety and stability disconnection is the important difficult point of whole car high pressure safety, also is one of the important assurance that the driving in-process prevented the incident.

In the existing high-voltage process, the control time sequence of each relay is unreasonable, and certain safety risk exists. And the precharge state is not detected and controlled yet, a phenomenon in which a high-voltage load such as a motor is damaged due to a sudden high voltage may occur. Meanwhile, the time sequence for cutting off the high-voltage system loop in the abnormal state is not controlled, and the safety of the whole vehicle is low.

Disclosure of Invention

The invention aims to provide a high-voltage switching control method for a power battery of a new energy automobile, aiming at the defects of the prior art, and the method can realize the accurate switching control of a high-voltage system of the power battery of the new energy automobile, solve various abnormal pre-charging states in the high-voltage electrifying process and improve the safety of the whole automobile.

The invention discloses a high-voltage switching control method for a power battery of a new energy automobile, which adopts the technical scheme that: comprises that

After receiving a power-on instruction of the whole vehicle, sequentially judging whether the sum V0 of the cell voltages of the battery pack is equal to the inner side voltage V1, whether the sum V0 meets the conditions that Vprecision is more than or equal to 0 and less than or equal to (V0-V1), more than or equal to Vprecision and is more than or equal to 0 and less than or equal to V3 and less than or equal to Vprecision, and whether high-level faults do not exist, if yes, driving an accessory relay to be closed and driving a pre-charging relay to be closed;

judging whether Vprecision is satisfied, wherein V1-V3 is more than or equal to 0 and less than or equal to Vprecision, and if yes, driving the main and negative relays to be closed;

after the pre-charging is finished, driving the main positive relay to be closed and driving the pre-charging relay to be disconnected;

judging whether Vprecision is satisfied or not, and continuously reaching a set period, if yes, sending a high-voltage connection signal to the whole vehicle;

wherein Vprecision is the voltage precision, V3 is the outer side high voltage, specifically the sampling high voltage at the outer side of the battery pack relay.

Preferably, after the high-voltage connection is completed, if a high-voltage command sent by the whole vehicle is received, whether | I | is satisfied is judged _pack |≤i _{Threshold value} If yes, the relays are disconnected in sequence, wherein I _pack For a pre-charge current, i _{Threshold value} A safety current for opening the relay.

Preferably, after receiving the power-on command of the whole vehicle

If the accumulated sum V0 of the cell voltages of the battery pack is not equal to the inner side voltage V1, judging that the fuse is disconnected, and exiting the high-voltage process;

and if the high-level fault exists, judging that the battery system has high safety risk, and exiting the high-voltage process.

Preferably, after the power-on command of the whole vehicle is received, if the power-on command does not meet the requirement

And V3 is not less than V3 and not more than V0-V1, judging that the main positive relay or the pre-charging relay is adhered, and exiting the upper high-voltage process.

Preferably, after a high voltage command sent by the whole vehicle is received, if abnormal conditions exist, the operation of the relays under different working conditions is processed according to fault levels, after abnormal power failure is judged, the charging and discharging power limit value of the battery cell is 0, a high voltage request is sent, and after the current is smaller than a set threshold value and reaches T seconds, the high voltage is disconnected.

Preferably, before the main and negative relays are driven to be closed, if the charging module receives a power-on instruction, the quick charging relay is driven to be closed.

Preferably, after the main and negative relays are driven to be closed, the method further comprises the step of

Judging whether the requirements are met

If not, judging the pre-charging short circuit, and exiting the high-voltage process;

wherein, R is the pre-charging resistance, and count is the number of times that the above conditions are simultaneously satisfied.

Preferably, after the main and negative relays are driven to be closed, the relay circuit further comprises

Judging the pre-charging time T _Pre-charging Whether it is longer than the maximum time T required for precharging _max If not, judging that the pre-charging is overtime, and exiting the upper high-pressure process.

Preferably, the determination of whether the pre-charging is completed includes

Judging whether the requirements are met

If yes, judging that the pre-charging is finished;

wherein, I _pack For pre-charge flow, vprecision _2 is the safety threshold of the high differential pressure on the inner and outer sides after the pre-charge of the battery pack is completed.

Preferably, after the pre-charging relay is driven to be switched off, if the driving time does not satisfy | V1-V3| ≦ Vprecision or satisfies | V1-V3| ≦ Vprecision but the duration does not reach the set period, the main positive relay is determined to be open-circuited.

The beneficial effects of the invention are as follows:

1. based on each relay, a high-voltage power-on process with a reasonable time sequence is provided, and the dangers that the relay adhesion, the pre-charging failure, the pre-charging explosion, the pre-charging short circuit, the high-voltage component damage, the whole vehicle losing control, threatening safety and the like caused by unreasonable time sequence control are prevented.

2. After a power-on instruction of the whole vehicle is received, whether the accumulated sum V0 of the cell voltages of the battery pack is equal to the inner side voltage V1, whether the Vprecision & &0 & ltV 3 & gt & ltVprecision is met or not, and whether high-level faults do not exist or not are judged, so that the high-safety risk conditions of fuse disconnection, main positive relay or pre-charging relay adhesion and a battery system which are possibly generated in the pre-charging process are eliminated before the closing of an accessory relay and the closing of a pre-charging relay, the high-voltage safety is ensured, and the phenomenon that a voltage load such as a motor is damaged due to sudden high voltage is prevented.

3. In the power-on process, the states that the pre-charging relay cannot be closed or the main negative relay is adhered, the pre-charging overtime, the pre-charging short circuit, the pre-charging failure and the main positive relay are opened are detected, and the pre-charging explosion problem is avoided.

4. A normal power-off control method and an abnormal power-off control method in an abnormal situation are provided. When abnormal power is off, the power of the whole vehicle is controlled in a stepped mode according to the fault level, the load is controlled, high voltage is switched according to conditions, and the safety of high-voltage components of the whole vehicle in the lower-point process is protected.

Drawings

FIG. 1 is a schematic diagram of the circuit connection principle of a high voltage system;

FIG. 2 is a schematic flow diagram of the present invention;

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Fig. 1 is a circuit of a high-voltage system, which mainly comprises a main positive relay, a main negative relay, a quick charge relay and a pre-charge relay, and a high-voltage switching control method of a new energy automobile power battery provides a reasonable time sequence control method by detecting the relays and related parameters in the power-on and power-off processes.

Fig. 2 shows a flow chart of a new energy vehicle power battery high-voltage switching control method provided in a preferred embodiment of the present application (fig. 1 shows a first embodiment of the present application), and for convenience of description, only parts related to the present embodiment are shown, and the detailed description is as follows:

s1: receive the power-on instruction of the whole vehicle

S2: judging that 1, v0= = V1, where V0 is the accumulated sum of battery cell voltages of the battery pack, and V1 is the inner voltage (specifically, the sampled high voltage at the inner side of the battery pack relay), and if the voltages are unequal, detecting that the fuse is disconnected, and exiting the upper high-voltage process;

s3: judging that Vprecision is more than or equal to 0 and less than or equal to (V0-V1) and more than or equal to 0 and more than or equal to V3 and less than or equal to Vprecision, wherein Vprecision is voltage precision (voltage is adopted by ADC, certain sampling precision exists, the sampling precision is different according to the range, and the high-voltage sampling precision in 400V is generally within 10V), if not, detecting that the voltage is mainly positive or a pre-charging relay is adhered, and exiting from a high-voltage flow (at the moment, a fault needs to be reported to the whole vehicle, and the battery has high-voltage risk and needs professional maintenance);

s4: whether there is a high-level fault is judged by the BMS, and 3: if the faulthlevel = =0, if the battery system is not satisfied, detecting that a high safety risk exists in the battery system, and exiting the high-voltage process;

high-level faults such as overvoltage, undervoltage, overcurrent, communication loss, collision, thermal runaway and the like which can directly threaten personal safety are judged as the high-level faults; and low-level faults such as low SOC, overlarge temperature difference, overlarge pressure difference, SOC jump and the like which do not directly threaten personal safety temporarily are judged as the low-level faults.

S5: the BMS main control unit sends out an instruction to drive the accessory relay to be closed;

s6: the BMS main control unit sends out an instruction to drive the pre-charging relay to be closed;

s7: and 4, judgment: V1-V3 are more than or equal to 0 and less than or equal to Vprecision, if not, the pre-charging relay is judged to be unable to be closed or the main and negative relays are adhered, and the high-voltage process is exited;

s8: and 5, judgment: whether a charging module power-on instruction is received or not, if so, closing the quick charging relay, and if not, not closing the quick charging relay;

s9: a BMS (BMS-battery management system) main control unit sends out an instruction to drive a main and negative relay to be closed;

s10: and 6, judgment: if the following conditions are met, detecting the circuit to be a pre-charging short circuit, wherein R is a pre-charging resistor, counting when the first condition and the second condition of count occur simultaneously, detecting the circuit to be the pre-charging short circuit when the total number of times exceeds 3, and exiting the high-voltage process;

s11: and (7) judgment: pre-charging time T _Pre-charging ≤T _max And Tmax is the longest time required by pre-charging and is determined by a pre-charging resistor and a motor load capacitor. If the condition is not met, judging that the pre-charging is overtime, and exiting the upper high-pressure process;

s12: and 8, judgment: if the internal and external voltages reach the threshold value and the pre-charging flow is positive, judging that the pre-charging is finished, otherwise, judging that the pre-charging fails;

s13: the BMS main control unit sends out an instruction to drive the main positive relay to be closed;

s14: sending an instruction by the BMS main control unit to drive the pre-charging relay to be disconnected;

s15: and 9, judgment: V1-V3 is less than or equal to Vprecision and lasts for 2 periods, if the condition is not met, the open-circuit fault of the main positive relay is detected, and the upper high-voltage flow is exited;

s16: after the judgment is finished, sending a high-voltage connection CAN signal to the whole vehicle;

s17: under normal conditions, receiving a judgment 10: after the whole vehicle sends a high-pressure instruction, the detection and judgment are 11: i _pack |≤i _{Threshold value} If the conditions are met, the BMS main control unit sends out instructions and switches off the relays in sequence; wherein, I _pack For a pre-charge current, i _{Threshold value} A safe current for the relay to open (determined by the life curve of the relay).

S18: under the abnormal condition, adopt the electricity processing procedure under unusual, can specifically handle disconnected relay operation under the different work condition respectively according to the fault level, when guaranteeing the relay safe disconnection, guarantee the safety of whole car. After an abnormal power failure condition is judged (a more serious power failure fault, an emergency power-off instruction of the whole vehicle and the like), the charging and discharging power of the battery cell is limited to 0, a high-voltage request is sent, and after the current is judged to be less than or equal to a threshold value for T seconds, the high voltage is cut off.

Therefore, in the abnormal power-off process, the charging and discharging power of the battery core is controlled, the power-off request is sent, the non-load switching of the relay is ensured, and the out-of-control of the whole vehicle is avoided.

Simultaneously, because the relative BMS of relay, spare part cost itself is higher, and power battery carries the back in the whole car in addition, if change relay and other high-voltage components and parts, need whole package uninstallation to unpack worse relay apart, need longer cost of labor, time cost, and the maintenance have certain security, after this scheme of adoption, can save the maintenance cost of a large amount of battery packages, promote whole car safety, prevent risks such as unexpected outage.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only used for distinguishing one functional unit from another, and are not used for limiting the protection scope of the present application. For the specific working processes of the units and modules in the system, reference may be made to the corresponding processes in the foregoing method embodiments, which are not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one type of logical function division, and other division manners may be available in actual implementation, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit.

The integrated module/unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method of the embodiments described above can be realized by a computer program, which can be stored in a computer-readable storage medium and can realize the steps of the embodiments of the methods described above when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A high-voltage switching control method for a power battery of a new energy automobile is characterized by comprising the following steps: comprises that

After a power-on instruction of the whole vehicle is received, whether the accumulated sum V0 of the cell voltages of the battery pack is equal to the inner side voltage V1, whether Vprecision & &0 ≤ (V0-V1) ≤ and V3 ≤ and whether high-level faults do not exist or not is sequentially judged, and if yes, the accessory relay is driven to be closed, and the pre-charging relay is driven to be closed;

judging whether the absolute value of V1-V3 is less than or equal to Vprecision and continuously reaching a set period, if so, sending a high-voltage connection signal to the whole vehicle;

wherein Vprecision is the voltage precision, and V3 is the outer high voltage.

2. According to claim 1The high-voltage switching control method for the power battery of the new energy automobile is characterized by comprising the following steps: after the high-voltage connection is finished, if a high-voltage command sent by the whole vehicle is received, whether I is met or not is judged _pack |≤i _{Threshold value} If yes, the relays are disconnected in sequence, wherein I _pack For a pre-charge current, i _{Threshold value} A safety current for opening the relay.

3. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after receiving the power-on instruction of the whole vehicle

If the sum V0 of the cell voltages of the battery pack is not equal to the inner side voltage V1, judging that the fuse is disconnected, and exiting the high-voltage process;

4. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after receiving the power-on instruction of the whole vehicle, if the power-on instruction does not meet the requirement

And (V0-V1) is more than or equal to 0 and less than or equal to Vprecision & &0 and less than or equal to V3 and less than or equal to Vprecision, the main positive relay or the pre-charging relay is judged to be adhered, and the upper high-voltage flow is exited.

5. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after a high voltage descending instruction sent by the whole vehicle is received, if abnormal conditions exist, the operation of the relays under different working conditions is processed according to fault levels, after abnormal power failure is judged, the limit value of the charge-discharge power of the battery cell is 0, a high voltage descending request is sent, and after the current is smaller than a set threshold value and reaches T seconds, the high voltage is disconnected.

6. The new energy automobile power battery high-voltage switching control method according to claim 1, characterized in that: before the main and negative relays are driven to be closed, if the charging module receives a power-on instruction, the quick charging relay is driven to be closed.

7. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after the main and negative relays are driven to be closed, the method also comprises

Judging whether the requirements are met

wherein, I _pack For precharge current, R is precharge resistance, count is the number of times the above conditions are simultaneously met.

8. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after the main and negative relays are driven to be closed, the relay circuit also comprises

Judging the pre-charging time T _Pre-charging Whether it is longer than the maximum time length T required for pre-charging _max If not, judging that the pre-charging is overtime, and exiting the upper high-pressure process.

9. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: the determination of whether the pre-charging is completed includes

Judging whether the requirements are met

If yes, judging that the pre-charging is finished;

10. The high-voltage switching control method for the power battery of the new energy automobile according to claim 1, characterized by comprising the following steps: after the pre-charging relay is driven to be disconnected, if the Vprecision is not satisfied or the Vprecision is satisfied but the duration does not reach the set period, the main positive relay is judged to be open-circuited.