CN109143076B

CN109143076B - Method for regulating the discharge power of a battery

Info

Publication number: CN109143076B
Application number: CN201810860261.9A
Authority: CN
Inventors: 曾国建; 余铿; 许海丽; 蔡华娟; 杨彦辉; 程晓伟; 吉祥; 项文
Original assignee: Anhui Rntec Technology Co ltd
Current assignee: Anhui Rntec Technology Co ltd
Priority date: 2018-08-01
Filing date: 2018-08-01
Publication date: 2021-06-29
Anticipated expiration: 2038-08-01
Also published as: CN109143076A

Abstract

The invention provides a method for adjusting discharge power of a battery pack, and belongs to the technical field of battery maintenance. The method comprises the following steps: acquiring the temperature of the battery pack; acquiring an SOC value of the battery pack and acquiring first discharge power from the corresponding relation table; acquiring second discharge power of the battery pack from the corresponding relation table; detecting a discharge current and a discharge voltage of the battery pack; calculating the current actual power; recording the first duration time under the condition that the current actual power is greater than or equal to the second discharge power; in the case that the first duration is greater than or equal to the first threshold, adjusting the current actual power according to the second discharge power and executing the method; recording a second duration time under the condition that the current actual power is judged to be smaller than the second discharging power; under the condition that the second duration is greater than or equal to a second threshold, acquiring third discharge power of the battery pack from the corresponding relation table according to the first discharge power; the current actual power is adjusted according to the third discharge power, and the method is executed.

Description

Method for regulating the discharge power of a battery

Technical Field

The invention relates to the technical field of battery maintenance, in particular to a method for adjusting discharge power of a battery pack.

Background

In recent years, electric vehicles have been receiving attention from various countries due to the influence of energy crisis and environmental crisis. Lithium batteries have also been rapidly developed as a mainstream power source for electric vehicles. The peak power of the lithium battery pack is an important parameter of the lithium battery, and when the electric automobile starts or accelerates, whether the vehicle-mounted battery pack can meet the power requirement at the moment can be estimated through the peak power; during braking, the maximum energy that can be recovered without damaging the battery pack can be estimated; in addition, the estimation of the peak power of the battery also has important theoretical significance and practical value for the optimal matching of the power performance of the whole vehicle and the optimization of a control strategy.

Currently, there are a composite pulse method, a method based on SOC (State Of Charge), a neural network method, and the like for estimating the peak power Of the battery. The neural network method is suitable for online estimation of the power state of the lithium battery, has high estimation accuracy, needs a large amount of training data and a proper training method as supports, and has a complex algorithm, so that the practicability is low. According to the SOC-based method, the limit current value in the current state is obtained through the limitation of the maximum SOC and the minimum SOC, so that the power state of the lithium battery in a period of time delta t is obtained through calculation, and the estimated peak power is too large because delta t can not be determined frequently. The composite pulse method utilizes the ratio of the difference between the open-circuit voltage and the discharge cut-off voltage of the battery to the internal resistance of the battery to obtain the maximum discharge current of the battery so as to estimate the peak power of the battery, but the commonly used composite pulse method does not consider the influence of temperature. If the temperature is directly substituted into each calculation parameter of the composite pulse method, the variation is more and the estimation is more complicated.

Disclosure of Invention

The invention aims to provide a method for adjusting the discharge power of a battery pack, which estimates the maximum discharge power of the battery pack in real time when the battery pack is discharged and adjusts the current actual discharge power of the battery pack according to the maximum discharge power, thereby realizing smooth change of the discharge power of the battery pack, protecting the battery pack and improving the recovery rate of energy.

In order to achieve the above object, the present invention provides a method for adjusting discharge power of a battery pack, which may include:

acquiring the temperature of the battery pack;

acquiring the SOC value of the battery pack;

acquiring first discharge power of the battery pack in a preset corresponding relation table under the conditions of the temperature and the SOC value according to the temperature and the SOC value;

acquiring second discharge power of the battery pack from the corresponding relation table according to the first discharge power;

detecting a discharge current and a discharge voltage of the battery pack;

calculating the current actual power of the battery pack according to the discharge current and the discharge voltage;

judging whether the current actual power is greater than or equal to the second discharging power;

recording a first duration time that the current actual power is greater than or equal to the second discharge power under the condition that the current actual power is greater than or equal to the second discharge power;

judging whether the first duration is greater than or equal to a preset first threshold value or not;

under the condition that the first duration time is judged to be greater than or equal to the first threshold value, adjusting the current actual power according to the second discharging power, and executing the method again;

recording a second duration time that the current actual power is smaller than the second discharging power under the condition that the current actual power is judged to be smaller than the second discharging power;

judging whether the second duration is greater than or equal to a preset second threshold value or not;

under the condition that the second duration time is judged to be greater than or equal to the second threshold value, acquiring third discharging power of the battery pack from the corresponding relation table according to the first discharging power

And adjusting the current actual power according to the third discharge power, and executing the method again.

Optionally, the acquiring the temperature of the battery pack includes:

respectively detecting the monomer temperature of each monomer battery of the battery pack;

calculating an average value from the cell temperatures to generate a temperature of the battery pack.

Optionally, the correspondence table includes a plurality of levels of correspondence, each level of correspondence includes maximum discharge power of the plurality of battery packs having an SOC value of 10% to 90% and an incremental gradient of 10% at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃ and 45 ℃.

Optionally, the multiple-order correspondence includes a 6-order correspondence, and the 1 st to 6 th order correspondences include maximum discharge powers at which the plurality of battery packs having the SOC values of 10% to 90% and the incremental gradients of 10% are discharged for 10s, 20s, 30s, 40s, 50s, and 60s at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃, and 45 ℃, respectively.

Optionally, the obtaining, according to the temperature and the SOC value, the first discharge power of the battery pack in a preset correspondence table under the condition of the temperature and the SOC value includes:

and acquiring the maximum discharge power of the battery pack in the corresponding relation table under the conditions of the temperature and the SOC value from an ith-order corresponding relation table according to the temperature and the SOC value, wherein i is any integer in an interval [1,6], and the maximum discharge power is used as a first discharge power.

Optionally, the obtaining the second discharge power of the battery pack from the correspondence table according to the first discharge power includes:

and acquiring the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value from the i-1 st order correspondence table as the second discharge power.

Optionally, in a case where the value of i-1 is less than 1, the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value is acquired from a 1 st order correspondence table as the second discharge power.

Optionally, the obtaining of the third discharge power of the battery pack from the correspondence table according to the first discharge power includes:

acquiring the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value from the (i + 1) th order correspondence table as the third discharge power.

Optionally, in a case where the value of i +1 is greater than 6, the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value is acquired from a 6 th-order correspondence table as the third discharge power.

Optionally, both the first threshold and the second threshold are 10 s.

Through the technical scheme, the method for adjusting the discharge power of the battery pack provided by the invention estimates the maximum discharge power of the battery pack in real time when the battery pack is discharged, and adjusts the current actual discharge power of the battery pack according to the maximum discharge power, so that the discharge power of the battery pack is smoothly changed, the battery pack is protected, and the recovery rate of energy is improved.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a flow chart of a method for regulating discharge power of a battery pack according to an embodiment of the present invention;

fig. 2 is a block diagram of a system for adjusting discharge power of a battery pack according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Fig. 1 is a flowchart illustrating a method for adjusting discharge power of a battery pack according to an embodiment of the present invention. In fig. 1, the method may include:

in step S10, the temperature of the battery pack is acquired. Considering that the battery pack includes a plurality of unit cells, each unit cell may store a local temperature difference during the discharge. Therefore, in detecting the temperature of the battery pack, at least one temperature sensor may be provided on each unit cell of the battery pack to detect the cell temperature of each unit cell, respectively. A controller is provided to receive the temperatures of the individual cells and further calculate an average of all of the cell temperatures as the detected temperature of the battery pack.

In step S11, the SOC value of the battery pack is acquired. In the embodiment of the present invention, the SOC value may be acquired by, for example, setting a BMS (Battery Management System) to detect the SOC value of the Battery pack. For the BMS, the BMS may calculate the SOC value of the battery pack by a calculation method such as an open circuit voltage method, an ampere-hour integration method, or the like.

In step S12, the first discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value is acquired from the preset correspondence table according to the temperature and the SOC value of the battery pack. In one example of the invention, the correspondence table may, for example, include a multi-level correspondence. Each order of correspondence includes maximum discharge power of a plurality of battery packs having an SOC value of 10% to 90% and an incremental gradient of 10% at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃ and 45 ℃, respectively. Further, the multi-step correspondence relationship may include a 6-step correspondence relationship, the 1 st to 6 th step correspondence relationships include maximum discharge powers at which the plurality of battery packs having SOC values of 10% to 90%, respectively, and increasing gradients of 10% are discharged for 10s, 20s, 30s, 40s, 50s, and 60s at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃, and 45 ℃, respectively, as shown in tables 1 to 6 (taking the case where the battery pack includes only one unit cell as an example),

TABLE 1

TABLE 2

	90％	80％	70％	60％	50％	40％	30％	20％	10％
										-10℃	57.90	54.43	51.28	48.02	43.48	38.28	32.03	26.85	24.20
0℃	72.33	68.75	65.33	62.50	57.77	50.74	40.79	31.16	24.55
										10℃	81.39	73.52	69.81	66.11	65.17	58.66	53.21	45.66	31.11
25℃	126.31	117.22	110.14	106.02	105.36	97.63	88.85	77.44	54.88
										45℃	111.67	102.94	96.09	100.05	97.05	88.68	84.06	73.89	46.86

TABLE 3

	90％	80％	70％	60％	50％	40％	30％	20％	10％
										-10℃	54.81	51.17	47.75	43.92	38.55	32.18	25.18	20.61	19.66
0℃	67.75	63.99	60.39	57.06	51.39	42.88	32.23	22.77	19.30
										10℃	74.76	67.14	63.77	59.82	59.02	52.08	45.66	35.75	22.14
25℃	116.34	107.09	100.11	96.33	95.42	87.11	77.60	63.97	37.32
										45℃	105.14	95.31	88.63	93.23	89.70	80.42	75.99	64.89	32.78

TABLE 4

	90％	80％	70％	60％	50％	40％	30％	20％	10％
										-10℃	52.42	48.66	44.98	40.71	34.92	28.19	21.20	19.08	11.91
0℃	64.37	60.44	56.60	52.67	46.15	37.03	26.82	21.22	13.79
										10℃	69.61	62.32	59.11	55.05	54.12	46.81	38.95	28.53	16.81
25℃	108.44	99.41	92.66	88.88	87.48	78.86	68.53	48.91	23.78
										45℃	99.70	89.56	83.26	87.82	83.82	74.32	69.47	57.80	22.10

TABLE 5

TABLE 6

	90％	80％	70％	60％	50％	40％	30％	20％	10％
										-10℃	48.70	44.71	40.54	35.61	29.45	22.81	17.90	17.89	8.94
0℃	59.29	55.06	50.49	45.31	37.68	28.59	20.16	17.30	13.79
										10℃	61.42	54.74	51.65	47.52	45.46	37.10	27.99	18.84	12.33
25℃	95.10	86.85	80.48	76.70	74.25	64.99	51.94	29.62	15.98
										45℃	85.36	76.66	71.23	74.73	70.41	61.41	55.63	42.42	9.09

In tables 1 to 6, the unit of the maximum discharge power is watt (W). Further, since the maximum discharge power (peak power) of the battery pack included in tables 1 to 6 is the maximum discharge power of a single unit cell. Therefore, when calculating a battery pack including a plurality of unit cells, the maximum discharge power in tables 1 to 6 may be multiplied by the number of unit cells connected in series in the battery pack according to the basic principle of the series circuit, thereby obtaining the maximum discharge power of the battery pack.

Then, the first discharge power may be a maximum discharge power of the battery pack under the conditions of the detected temperature and the SOC value in the ith order correspondence, where i is any integer in the interval [1,6 ].

In step S13, the second discharge power of the battery pack is acquired from the correspondence table based on the first discharge power. In one example of the present invention, this step may be to acquire the maximum discharge power of the battery pack under the conditions of the detected temperature and the SOC value, for example, from the i-1 th order correspondence. Further, since the correspondence table includes only 1 st to 6 th-order correspondences in this example, in the case where the value of i-1 is less than 1, the maximum discharge power of the battery pack under the conditions of the detected temperature and the SOC value is acquired in the 1 st-order correspondence.

In step S14, the discharge current and the discharge voltage of the battery pack are detected. In this example, a current sensor may be provided between the battery pack and the electrical appliance to detect the discharge current of the battery pack, and a voltage sensor may be provided at both ends of the positive and negative electrodes of the battery pack to detect the discharge voltage of the battery pack.

In step S15, the present actual power of the battery pack is calculated from the detected discharge current and discharge voltage. According to ohm's law, the current actual power of the battery pack is the product of the discharge current and the discharge voltage.

In step S16, it is determined whether the current actual power is greater than or equal to the second discharge power.

In step S17, in the case where it is judged that the present actual power is greater than or equal to the second discharge power, a first duration in which the present actual power is greater than or equal to the second discharge power is recorded. In this embodiment, the controller may be adapted to determine whether the current actual power is greater than or equal to the second discharge power. And starting a timer connected with the controller to record the first duration under the condition that the controller judges that the current actual power is greater than the second discharge power.

In step S18, it is determined whether the first duration is greater than or equal to a preset first threshold.

In step S19, in the case where it is determined that the first duration is greater than or equal to the first threshold, the current actual power is reduced according to the second discharge power, and the method for adjusting the discharge power of the battery pack is performed again. Taking the above example as an example, in tables 1 to 6, the discharge time of the battery packs of each adjacent two-step correspondence relationship differs by 10s (seconds). Therefore, in this example, the first threshold may be 10 s. In the case where it is determined that the first duration is greater than or equal to the preset first threshold, this indicates that the battery pack has been continuously discharged for 10s on the condition that the calculated current actual power (greater than the second discharge power) is present. Then, it is obvious that continuing to use the ith order correspondence as a reference for adjusting the discharge power of the battery pack has not been applicable. Therefore, the discharge power of the battery pack can be adjusted using the correspondence of the i-1 order.

In step S20, in the case where it is determined that the present actual power is less than the second discharge power, a second duration in which the present actual power is less than the second discharge power is recorded. This step S20 is similar to step S17 and will not be described here.

In step S21, it is determined whether the second duration is greater than or equal to a preset second threshold. In the above example, the second threshold may be, for example, 10 s. Since step S21 is similar to step S19, it is not described here.

In step S22, in a case where it is determined that the second duration is greater than or equal to the second threshold, the third discharge power of the battery pack is acquired from the correspondence table based on the first discharge power. Since the battery pack is discharged for 10s under the condition of being lower than the second discharge power at this time. Therefore, it is obvious that continuing to use the ith order correspondence relationship as a reference for adjusting the discharge power of the battery pack has not been applicable. Therefore, the discharge power of the battery pack can be adjusted using the correspondence of the i +1 order. Since the correspondence table includes only 1 st to 6 th-order correspondences in this example, in the case where the value of i +1 is greater than 6, the maximum discharge power of the battery pack under the conditions of the detected temperature and SOC value is acquired in the 6 th-order correspondence.

In step S23, the current actual power of the battery pack is increased according to the third discharge power, and the method for adjusting the discharge power of the battery pack is performed again. In this example, the step S23 can be realized by, for example, providing a current controller between the battery pack and the electrical appliance for adjusting the magnitude of the discharging current.

Another aspect of the present invention also provides a system for regulating discharge power of a battery pack. As shown in fig. 2, the system may include a temperature sensor 01, a battery SOC detection module 02, a current sensor 03, a voltage sensor 04, a timer 05, a current controller 06, and a controller 07.

The temperature sensor 01 may be used to detect the temperature of the battery pack; the battery SOC detection module 02 may be for detecting the SOC value of the battery pack; the current sensor 03 may be, for example, for detecting a discharge current of the battery pack; the voltage sensor 04 may be, for example, a sensor that detects the discharge voltage of the battery pack; the current controller 06 may be, for example, disposed between the battery pack and the consumer for controlling the magnitude of the discharge current. The controller 07 may be connected with the temperature sensor 01, the battery SOC detection module 02, the current sensor 03, the voltage sensor 04, the timer 05, and the current controller 06, respectively, for performing the method for adjusting the discharge power of the battery pack as shown in fig. 1 based on the above-described devices.

In one embodiment of the invention, the controller 07 may be a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any other type of Integrated Circuit (IC), a state machine, or the like. In addition, in order to make the design of the system simple, a program may also be written in the BMS in a software programming manner to cause the BMS to perform the above-described method for adjusting the discharge power of the battery pack.

Through the technical scheme, the method and the system for adjusting the discharge power of the battery pack can estimate the maximum discharge power of the battery pack in real time when the battery pack discharges, and adjust the current actual discharge power of the battery pack according to the maximum discharge power, so that the discharge power of the battery pack smoothly changes, the battery pack is protected, and the recovery rate of energy is improved.

While the invention has been described in detail with reference to the drawings, the invention is not limited to the details of the above-described alternative embodiments, and various simple modifications can be made to the technical solution of the invention within the technical idea of the invention, and the simple modifications are within the protective scope of the invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations.

Those skilled in the art will understand that all or part of the steps in the foregoing embodiments may be implemented by a program instructing related hardware to complete, where the program is stored in a storage medium and includes several instructions to enable a (which may be a single chip, a chip, etc.) or a processor (processor) to execute all or part of the steps of the method according to the various embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as disclosed in the embodiments of the present invention as long as it does not depart from the spirit of the embodiments of the present invention.

Claims

1. A method for regulating discharge power of a battery pack, the method comprising:

acquiring the temperature of the battery pack;

acquiring the SOC value of the battery pack;

detecting a discharge current and a discharge voltage of the battery pack;

under the condition that the second duration time is judged to be greater than or equal to the second threshold value, acquiring third discharging power of the battery pack from the corresponding relation table according to the first discharging power;

adjusting the current actual power according to the third discharge power, and executing the method again;

the acquiring, from a preset correspondence table according to the temperature and the SOC value, a first discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value includes:

acquiring the maximum discharge power of the battery pack in an ith order corresponding relation table under the conditions of the temperature and the SOC value from the ith order corresponding relation table according to the temperature and the SOC value, wherein i is any integer in an interval [1,6 ];

the obtaining of the second discharge power of the battery pack from the correspondence table according to the first discharge power includes:

acquiring the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value from the i-1 th order correspondence table as the second discharge power;

the obtaining of the third discharge power of the battery pack from the correspondence table according to the first discharge power includes:

2. The method of claim 1, wherein said obtaining the temperature of the battery pack comprises:

3. The method of claim 1, wherein the mapping table comprises a plurality of levels of mapping relationships, each level of mapping relationship comprising maximum discharge power of the plurality of battery packs with SOC values of 10% to 90% and an incremental gradient of 10% at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃ and 45 ℃, respectively.

4. The method of claim 3, wherein the multiple-step mapping relationship comprises a 6-step mapping relationship, and the 1 st to 6 th step mapping relationships respectively comprise maximum discharge powers at which the plurality of battery packs with SOC values of 10% to 90% and an incremental gradient of 10% are discharged for 10s, 20s, 30s, 40s, 50s, and 60s at ambient temperatures of-10 ℃, 0 ℃, 10 ℃, 25 ℃, and 45 ℃, respectively.

5. The method according to claim 4, wherein in a case where the value of i-1 is less than 1, the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value is acquired from the 1 st order correspondence table as the second discharge power.

6. The method according to claim 5, characterized in that, in a case where the value of i +1 is greater than 6, the maximum discharge power of the battery pack in the correspondence table under the conditions of the temperature and the SOC value is acquired from a 6 th-order correspondence table as the third discharge power.

7. The method of any one of claims 1 to 6, wherein the first threshold and the second threshold are both 10 s.