阅读说明：本技术 一种新能源汽车行驶放电电流计算方法及装置 (New energy automobile running discharge current calculation method and device ) 是由 胡亮 王翰超 王云 尹坤 孙艳 刘欢 李�杰 于 2019-09-09 设计创作，主要内容包括：本发明提出了一种新能源汽车行驶放电电流计算方法,该方法包括,首先进行SOC和单体最低最高电压有效性识别,以决定当前的放电电流控制模式,对电流进行初步计算,以及特定故障处理后,采用初始值乘以增益以获得期望电流,参考当前实际电流获得电流差值,进行PID闭环控制,获得最终放电电流。本发明的有益效果：通过多因素控制,更精确的计算放电电流；有效提升电流计算的安全性,在SOC信号或者单体最高最低电压信号失效时依旧能够较为准确的计算出放电电流；特定故障下,通过增大放电电流达到加速故障消除的效果；放电电流在整个控制过程中闭环控制,防止了电流的阶跃和跳变。(The invention provides a new energy automobile running discharge current calculation method which comprises the steps of firstly identifying SOC and the lowest and highest voltage validity of a single body to determine the current discharge current control mode, carrying out preliminary calculation on current, multiplying the initial value by gain to obtain expected current after specific fault processing, obtaining a current difference value by referring to the current actual current, and carrying out PID closed-loop control to obtain the final discharge current. The invention has the beneficial effects that: through multi-factor control, the discharge current is calculated more accurately; the safety of current calculation is effectively improved, and the discharging current can be accurately calculated when the SOC signal or the single highest and lowest voltage signal fails; under a specific fault, the effect of accelerating fault elimination is achieved by increasing the discharge current; the discharging current is controlled in a closed loop mode in the whole control process, and the current is prevented from stepping and jumping.)

1. The new energy automobile running discharge current calculation method is characterized by comprising the steps of carrying out effectiveness identification on the SOC of a battery and the highest and lowest voltage of a single battery to determine a current discharge current control mode, and obtaining initial current values in different control modes through table lookup; and multiplying the initial current value by a gain coefficient under a specific fault to obtain an expected current, and performing PID closed-loop control based on the current actual current value, the current difference value of the expected current and the current actual current to obtain a final discharge current.

2. The new energy automobile driving discharge current calculation method according to claim 1, wherein the SOC validity value is obtained through an ampere-hour method, an open-circuit voltage method or a Kalman filtering algorithm, the single highest and lowest voltage validity value is obtained through detection of a voltage sensor, and the single highest and lowest temperature validity value is obtained through detection of a temperature sensor.

3. The new energy automobile running discharge current calculation method according to claim 1, wherein the current discharge current control mode is determined to be specifically a control mode of 0 when both the SOC and the single maximum and minimum voltage are valid, and the control mode is a default mode; when the SOC signal is invalid and the highest and lowest single voltage signals are valid, the control mode is 1; when the SOC signal is effective and the highest and lowest voltage signals of the single body are ineffective, the control mode is 2; when the SOC signal and the single highest and lowest voltage signal are invalid, the control mode is 3.

4. The new energy automobile running discharge current calculation method according to claim 3, wherein the obtaining of the initial current value in different control modes through table lookup specifically comprises obtaining through table lookup based on three factors when the control mode is 0, and obtaining through table lookup based on the single highest and lowest voltage and the single highest and lowest temperature when the control mode is 1; when the control mode is 2, the control mode is obtained by looking up a table based on the SOC and the highest and lowest temperature of the single body; when the control mode is 3, the maximum and minimum temperature of the single body is obtained, wherein the three factors are SOC, voltage and temperature.

5. The new energy automobile driving discharge current calculation method according to claim 1, wherein the specific fault is a cell overvoltage or a total voltage overvoltage.

6. The new energy automobile running discharge current calculation method according to claim 5, wherein the gain coefficient is calculated in a manner that: the method comprises the steps of charging a battery to total voltage overvoltage, then discharging at a set discharging current 90A under the environment of 25 ℃ until the total voltage of the battery is normal, recording process time, setting discharging target time based on four levels of faults, increasing the current if the discharging time of the set current is too large, and reducing the current otherwise, finally obtaining the discharging current for pulling the battery back to a normal working state within the target time, and dividing the current by 90A to obtain a discharging gain coefficient.

7. The new energy automobile running discharge current calculation method according to claim 6, wherein the gain coefficients corresponding to the four levels of faults are respectively that when the fault level is 0, the gain coefficient is 1; when the fault level is 1, the gain coefficient is 1.05; when the fault level is 2, the gain coefficient is 1.1; when the fault level is 3, the gain coefficient is 1.2; the gain factor is 1.3 for a fault level of 4.

8. The new energy automobile driving discharge current calculation method according to claim 1, wherein the actual current value is obtained by a hall current sensor.

9. The new energy automobile running discharge current calculation device is characterized by comprising an identification module, a storage module and a control module, wherein the identification module is used for identifying an SOC effective value, a single highest and lowest voltage effective value and a temperature effective value;

the processing module is used for determining the current discharge current control mode and obtaining the initial current value in different control modes by looking up a table;

and the calculation module is used for multiplying the initial current value by the gain coefficient under the specific fault to obtain the expected current, and performing PID closed-loop control on the basis of the current actual current value, the current difference value between the expected current and the current actual current to obtain the final discharge current.

10. The new energy automobile running discharge current calculation device according to claim 9, wherein the device further comprises,

the SOC calculation module is used for estimating an SOC validity value through an ampere-hour method, an open-circuit voltage method or a Kalman filtering algorithm;

the voltage sensor is used for detecting the highest and lowest voltage validity values of the single body;

the temperature sensor is used for detecting the highest and lowest temperature validity values of the monomers;

the fault detection module is used for detecting single overvoltage or total voltage overvoltage;

and the Hall current sensor is used for acquiring an actual current value.

Technical Field

The invention relates to the field of new energy automobile battery management, in particular to a new energy automobile running discharge current calculation method and device.

Background

In the existing product, the discharge current of the new energy automobile is calculated only based on SOC, and two of the highest and lowest voltages and the highest and lowest temperatures of the single body (wherein the temperature is optional) are controlled by adopting a current reduction mode when a battery management system (BMS for short) fails (the discharge current needs to be reduced when part of faults are defined, and some serious faults are directly powered off), and the change of the discharge current is not controlled or is controlled by adopting a fixed slope.

However, the prior art has the following disadvantages: 1. the correlation among SOC, the highest and lowest voltage of the single body and the temperature is not considered; 2. the discharging current cannot be normally calculated when SOC (system on chip) is abnormal or the highest and lowest voltages of the single body are abnormal; 3. the discharge current is improved due to the fact that the total voltage is too high and the voltage of the single battery is too high for special faults, and the battery pack cannot be quickly returned to a normal state; 4. the discharge current change is not subjected to closed-loop control, so that the judgment of discharge overcurrent is influenced by the possibility of overlarge current impact or overlong change time.

Disclosure of Invention

In order to solve the technical problems, the invention provides a new energy automobile running discharge current calculation method and a new energy automobile running discharge current calculation device.

According to an embodiment of the invention, the invention provides a new energy automobile running discharge current calculation method, which comprises the following steps,

carrying out effectiveness identification on the SOC of the battery and the highest and lowest voltage of the single battery to determine the current discharge current control mode, and obtaining initial current values in different control modes through table lookup; and multiplying the initial current value by a gain coefficient under a specific fault to obtain an expected current, and performing PID closed-loop control based on the current actual current value, the current difference value of the expected current and the current actual current to obtain a final discharge current.

Preferably, the SOC validity value is estimated by an ampere-hour method, an open-circuit voltage method, or a kalman filter algorithm, the single maximum and minimum voltage validity value is detected by a voltage sensor, and the single maximum and minimum temperature validity value is detected by a temperature sensor.

Preferably, the determining of the current discharging current control mode is specifically that when both the SOC and the highest and lowest voltages of the single body are valid, the control mode is 0, and the mode is a default mode; when the SOC signal is invalid and the highest and lowest single voltage signals are valid, the control mode is 1; when the SOC signal is effective and the highest and lowest voltage signals of the single body are ineffective, the control mode is 2; when the SOC signal and the single highest and lowest voltage signal are invalid, the control mode is 3.

Preferably, the step of looking up a table to obtain the initial current values in different control modes specifically comprises the steps of looking up a table based on three factors when the control mode is 0, and looking up a table based on the highest and lowest voltage and the highest and lowest temperature of the single body when the control mode is 1; when the control mode is 2, the control mode is obtained by looking up a table based on the SOC and the highest and lowest temperature of the single body; when the control mode is 3, the maximum and minimum temperature of the single body is obtained, wherein the three factors are SOC, voltage and temperature.

Preferably, the specific fault is a cell overvoltage or a total voltage overvoltage.

Preferably, the gain factor is calculated in the following manner: the method comprises the steps of charging a battery to total voltage overvoltage, then discharging at a set discharging current 90A under the environment of 25 ℃ until the total voltage of the battery is normal, recording process time, setting discharging target time based on four levels of faults, increasing the current if the discharging time of the set current is too large, and reducing the current otherwise, finally obtaining the discharging current for pulling the battery back to a normal working state within the target time, and dividing the current by 90A to obtain a discharging gain coefficient.

Preferably, the gain coefficients corresponding to the four levels of faults are respectively that when the fault level is 0, the gain coefficient is 1; when the fault level is 1, the gain coefficient is 1.05; when the fault level is 2, the gain coefficient is 1.1; when the fault level is 3, the gain coefficient is 1.2; the gain factor is 1.3 for a fault level of 4.

Preferably, the actual current value is obtained by a hall current sensor.

According to still another embodiment of the invention, the invention also provides a new energy automobile running discharge current calculation device, which comprises,

the identification module is used for identifying the SOC effective value, the single body highest and lowest voltage effective value and the temperature effective value;

the processing module is used for determining the current discharge current control mode and obtaining the initial current value in different control modes by looking up a table;

and the calculation module is used for multiplying the initial current value by the gain coefficient under the specific fault to obtain the expected current, and performing PID closed-loop control on the basis of the current actual current value, the current difference value between the expected current and the current actual current to obtain the final discharge current.

Preferably, the apparatus further comprises a control unit,

the SOC calculation module is used for estimating an SOC validity value through an ampere-hour method, an open-circuit voltage method or a Kalman filtering algorithm;

the voltage sensor is used for detecting the highest and lowest voltage validity values of the single body;

the temperature sensor is used for detecting the highest and lowest temperature validity values of the monomers;

the fault detection module is used for detecting single overvoltage or total voltage overvoltage;

and the Hall current sensor is used for acquiring an actual current value.

The invention has the beneficial effects that: through multi-factor control, the discharge current is calculated more accurately; the safety of current calculation is effectively improved, and the discharging current can be accurately calculated when the SOC signal or the single highest and lowest voltage signal fails; under a specific fault, the effect of accelerating fault elimination is achieved by increasing the discharge current; the discharging current is controlled in a closed loop mode in the whole control process, and the current is prevented from stepping and jumping.

Drawings

FIG. 1 is a flow chart of a discharge current calculation method according to the present invention;

fig. 2 is a schematic diagram of PID closed-loop control in the discharge current calculation method according to the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The following describes an electric vehicle discharge current calculation method and apparatus according to an embodiment of the present invention with reference to the drawings.

Fig. 1 is a schematic diagram of a method for calculating a discharge current of a new energy vehicle according to an embodiment of the present invention, as shown in fig. 1, the method mainly includes the following steps:

carrying out effectiveness identification on the SOC of the battery and the highest and lowest voltage of the single battery to determine the current discharge current control mode, and obtaining initial current values in different control modes through table lookup; and multiplying the initial current value by a gain coefficient under a specific fault to obtain an expected current, and performing PID closed-loop control based on the current actual current value, the current difference value of the expected current and the current actual current to obtain a final discharge current.

According to the embodiment of the invention, in the above steps, validity identification is performed on the state of charge SOC of the battery and the highest and lowest voltages of the single battery, and specifically includes that, as shown in fig. 1, a signal source performs input of various signals and acquisition of final discharge current, SOC validity comes from an SOC calculation module, an SOC value is estimated by the SOC calculation module, an estimation algorithm includes an ampere-hour method, an open-circuit voltage method, or a kalman filter algorithm, details and limitations of the specific estimation algorithm are not repeated herein, validity of the highest and lowest voltages of the single battery comes from a voltage sensor, the highest and lowest temperatures of the single battery come from a temperature sensor, overhigh voltages of the single battery and overhigh total voltages of the single battery come from a fault detection module, and actual current comes from a hall current sensor.

In the invention, a voltage sensor, a temperature sensor, a fault detection module and a Hall current sensor are correspondingly arranged, the voltage, the temperature and the current are collected, and the fault detection is carried out through the fault detection module, wherein the specific fault is monomer overvoltage or total voltage overvoltage. The specific detection mode is not limited in the invention, and the corresponding acquisition and detection functions can be realized.

Specifically, the step of obtaining the initial current values in different control modes through table lookup comprises the steps of obtaining the initial current values through table lookup based on three factors when the control mode is 0, and obtaining the initial current values through table lookup based on the highest and lowest voltage and the highest and lowest temperature of the single body when the control mode is 1; when the control mode is 2, the control mode is obtained by looking up a table based on the SOC and the highest and lowest temperature of the single body; when the control mode is 3, the maximum and minimum temperature of the single body is obtained, wherein the three factors are SOC, voltage and temperature. These lookup table values are obtained from bench tests, and in the present invention, PID closed loop control is used, wherein P, I, D coefficients are also obtained from bench tests as shown in fig. 2. The specific contents are shown in table 1:

TABLE 1 three-factor corresponding relation table

In this embodiment, the discharging current control mode of the present invention is specifically that when both the SOC and the highest and lowest voltages of the cell are valid, the control mode is 0, and the control mode is a default mode; when the SOC signal is invalid and the highest and lowest single voltage signals are valid, the control mode is 1; when the SOC signal is effective and the highest and lowest voltage signals of the single body are ineffective, the control mode is 2; when the SOC signal and the single highest and lowest voltage signal are invalid, the control mode is 3.

The gain coefficient is calculated in the following way: the method comprises the steps of charging a battery to total voltage overvoltage, then discharging at a set discharging current 90A under the environment of 25 ℃ until the total voltage of the battery is normal, recording process time, setting discharging target time based on four levels of faults, increasing the current if the discharging time of the set current is too large, and reducing the current otherwise, finally obtaining the discharging current for pulling the battery back to a normal working state within the target time, and dividing the current by 90A to obtain a discharging gain coefficient.

For example, the target time of the four-stage fault is 5 minutes, if the set current discharge time is too large, the current is increased, and otherwise, the current is decreased. Finally, a discharge current capable of pulling the battery back to a normal working state within 5 minutes can be obtained, and the discharge gain coefficient is obtained by dividing the current by 90. The target time of the third-level fault is 7 minutes, the target time of the second-level fault is 10 minutes, and the target time of the first-level fault is 15 minutes. The method is the same and is not repeated.

According to the above, in the embodiment of the present invention, the gain coefficients corresponding to the four levels of faults are respectively, and when the fault level is 0, the gain coefficient is 1; when the fault level is 1, the gain coefficient is 1.05; when the fault level is 2, the gain coefficient is 1.1; when the fault level is 3, the gain coefficient is 1.2; the gain factor is 1.3 for a fault level of 4.

According to still another embodiment of the invention, the invention also provides a new energy automobile running discharge current calculation device, which comprises,

the identification module is used for identifying the SOC effective value, the single body highest and lowest voltage effective value and the temperature effective value;

the processing module is used for determining the current discharge current control mode and obtaining the initial current value in different control modes by looking up a table;

and the calculation module is used for multiplying the initial current value by the gain coefficient under the specific fault to obtain the expected current, and performing PID closed-loop control on the basis of the current actual current value, the current difference value between the expected current and the current actual current to obtain the final discharge current.

Preferably, the apparatus further comprises a control unit,

the SOC calculation module is used for estimating an SOC validity value through an ampere-hour method, an open-circuit voltage method or a Kalman filtering algorithm;

the voltage sensor is used for detecting the highest and lowest voltage validity values of the single body;

the temperature sensor is used for detecting the highest and lowest temperature validity values of the monomers;

the fault detection module is used for detecting single overvoltage or total voltage overvoltage;

and the Hall current sensor is used for acquiring an actual current value.

The discharge current calculation method and the discharge current calculation device provided by the embodiment of the invention control the discharge current based on three factors (SOC, highest and lowest voltage of the single body and temperature), can eliminate interference and correctly control the discharge current when the highest and lowest voltage of the single body or the SOC is abnormal, carry out discharge current gain aiming at faults of overlarge total voltage and overhigh voltage of the single body, quickly reduce the total voltage and the single body voltage, enable the total voltage and the single body voltage to return to a normal working state, adopt closed-loop control on current change, and be controllable in the whole current change process.

It will be evident to those skilled in the art that the embodiments of the present invention are not limited to the details of the foregoing illustrative embodiments, and that the embodiments of the present invention are capable of being embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the embodiments being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. Several units, modules or means recited in the system, apparatus or terminal claims may also be implemented by one and the same unit, module or means in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the embodiments of the present invention and not for limiting, and although the embodiments of the present invention are described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the embodiments of the present invention without departing from the spirit and scope of the technical solutions of the embodiments of the present invention.