Disclosure of Invention
In order to solve the problems, the invention provides a method, a device and a system for testing the power characteristics of a lithium power battery excited by sawtooth waves, which are applied to the power characteristic test evaluation in the echelon utilization process of various batteries, provide effective basis for the sorting of the power batteries, prolong the service life of the batteries and ensure the good consistency of the batteries.
The invention provides a method for testing the power characteristics of a lithium power battery excited by sawtooth waves, which specifically comprises the following steps:
a discharging step, discharging the battery to be tested by continuously reduced pulse current, wherein each discharging pulse current lasts for a certain discharging time;
a standing step, in which the battery to be tested is allowed to stand;
a charging step, in which the battery to be tested is charged by continuously increased pulse current, each discharging pulse current lasts for a certain discharging time, and the pulse current in the charging step is the reverse order of the pulse current in the discharging step;
and a power characteristic calculation step of calculating the variation of the terminal voltage difference between the discharging condition and the charging condition of the same current, and calculating the sum of squares of all the variations, and squaring the sum of the squares to obtain a value of the power characteristic, wherein the value is closer to zero to indicate that the power characteristic is better, and conversely, the value is worse.
Further, the discharge time for each pulse current in the discharge step is the same.
Further, the charging time for which each pulse current lasts in the charging step is the same as the discharging time for which the same pulse current lasts in the discharging step.
Further, the duration of the standing step is the same as the discharge time for which each pulse current in the discharging step lasts.
Further, before the discharging step is carried out, the SOC value of the battery to be tested is not lower than 10%.
Furthermore, the battery to be tested is a single battery or a battery module formed by connecting batteries in series and parallel, and the type of the battery to be tested is a lead-acid battery, a cadmium-nickel battery, a nickel-hydrogen battery, a lithium ion battery, a fuel cell, a solar battery or other batteries based on a chemical power supply technology.
Further, in the discharging step, the difference between two adjacent pulse currents is the same.
Further, the terminal voltage difference is a difference between a terminal voltage at a time after the pulse current changes and a terminal voltage at a time before the pulse current changes in the discharging step or the charging step.
The invention provides a device for testing the power characteristics of a lithium power battery excited by sawtooth waves, which comprises:
a discharging module that discharges the battery to be tested with a continuously decreasing pulse current, each of which lasts for a certain discharge time;
a standing step, in which the battery to be tested is allowed to stand;
the charging module is used for charging the battery to be tested by continuously increasing pulse current, each discharging pulse current lasts for a certain discharging time, and the pulse current in the charging step is the reverse sequence of the pulse current in the discharging step;
and the power calculation module calculates the variation of the end voltage difference when the discharging condition and the charging condition of the same current are carried out, calculates the sum of squares of all the variations, and obtains the value of the power characteristic by opening and squaring the sum of the squares, wherein the closer the value is to zero, the better the power characteristic is, and otherwise, the worse the power characteristic is.
The invention provides a power characteristic test system of a lithium power battery excited by adopting sawtooth waves, which comprises a battery pack, a processor and a memory, wherein the processor is configured to execute a power characteristic test method of the lithium power battery excited by adopting sawtooth waves through executing executable instructions;
the memory is to store the executable instructions of the processor.
Furthermore, the power characteristic test system for the lithium power battery excited by the sawtooth wave further comprises a charge and discharge source, a voltage acquisition device and a display device.
As described above, the present invention has the following effects:
the invention is technically characterized in that sawtooth wave excitation is adopted to test the power characteristics of a power battery module, a battery charging and discharging source is adopted to discharge and charge the battery module with instant heavy current, the end voltage difference of the battery module is collected at high speed, and the variation of the end voltage difference of the power battery is obtained through analysis and calculation, so that the power characteristics of the power battery are reflected.
1. The power battery module is subjected to power characteristic test by adopting sawtooth wave excitation, so that the result deviation caused by single current is avoided, the voltage response characteristics under the charging or discharging current of medium and low multiplying power and high multiplying power are considered, and the accuracy of the power characteristic test is improved;
2. compared with the traditional battery power characteristic test method, the test method is flexible, the test time can be set at any time according to the requirement, and the high-precision power characteristic test can be completed within several minutes.
3. The power testing device and the system have low energy consumption, do not need to adopt a high-power constant current source to carry out charging and discharging operation on the power battery, save a large amount of electric energy and achieve the effects of energy conservation and emission reduction.
4. The test system can comprehensively reflect the internal parameters and the characteristics of the battery and ensure the accuracy of power performance test and evaluation of the power battery.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
As shown in fig. 1, the method for testing the power characteristics of the lithium-ion power battery excited by a sawtooth wave in this embodiment specifically includes the following steps:
and S1, a discharging step, discharging the battery to be tested by continuously reduced pulse currents, wherein the duration time of each pulse current is the same, and the difference between two adjacent pulse currents is the same. In this embodiment, the discharge pulse currents in the discharge step are sequentially set to 8C, 7C, 6C, 5C, 4C, 3C, 2C, and 1C multiplying current according to the test power specified in the HPPC composite pulse experimental standard manual, that is, the currents in the discharge step are sequentially 8800mA, 7700mA, 6600mA, 5500mA, 4400mA, 3300mA, 2200mA, and 1100mA, and the discharge time of each discharge pulse current is 10 s.
Before the discharging step is carried out, the SOC value of the battery is not lower than 10%, so that the discharging process can be fully carried out, and when the SOC value of the battery is between 10% and 100%, the discharging step and the charging step can be normally carried out in the experimental process.
S2, standing, namely standing the battery to be tested; the duration of the rest step is the same as the duration of each pulse current in the discharge step, and is also 10 s.
S3, a charging step, wherein the battery to be tested is charged by continuously increased pulse current, the pulse current of the charging step is the reverse order of the pulse current in the discharging step, namely the total charging pulse current of the charging step is multiplying current of 1C, 2C, 3C, 4C, 5C, 6C, 7C and 8C in sequence, namely the current in the charging step is 1100mA, 2200mA, 3300mA, 4400mA, 5500mA, 6600mA, 7700mA and 8800mA in sequence, and the duration time of each pulse current in the charging step is the same as the duration time of each pulse current in the discharging step and is 10S.
According to the power characteristics of the existing battery, the capacity of receiving charge of the battery is slightly smaller than the capacity of discharging, the determining factor of the capacity of receiving charge and the capacity of discharging is the SOC value of the battery, when the SOC value of the battery is lower, the capacity of receiving charge of the battery is stronger, the SOC value is higher, and the battery is stronger in the capacity of receiving discharge, the test process of the embodiment adopts a mode of discharging and recharging firstly, in the discharging process, the maximum current is used for discharging, then the discharging pulse current is gradually reduced to enable the battery to continuously discharge, in the charging process, the small current is used for charging, then the charging pulse current is gradually increased to enable the battery to be charged gradually, and on one hand, the problem that the battery is dangerous due to sudden large-current charging can be avoided; on the other hand, when the battery is charged by a large current, the battery cannot completely absorb energy, but the battery can normally release energy in the discharging process, so that not only is the energy wasted due to incomplete absorption, but also the inconsistent values of energy absorption and energy release in the charging and discharging process are larger, and the measurement error of the measurement method is increased. The current in the charging process is gradually increased, so that sudden high-current charging can be prevented, and the safety of the battery is facilitated.
The pulse current that adopts in the discharge process and the charging process of this embodiment is set for according to HPPC composite pulse experiment standard manual, and in the actual measurement process, can design according to different battery characteristics, but the prerequisite is in the course of guaranteeing the battery charging, under the circumstances of guaranteeing battery security and energy absorption efficiency, the charging current will be increased by undercurrent gradually.
In the present embodiment, according to steps S1 to S3, the charging and discharging current characteristic curve and the charging and discharging voltage characteristic curve shown in fig. 3 and 4 are obtained, and as can be seen from fig. 3, the specific charging process of the present embodiment is as follows: discharging the battery to be tested at t1 with current of 8C for 10 s; discharging the battery to be tested with a current of 7C at a time t2 for 10s, discharging the battery to be tested with a current of 6C at a time t3 for 10s, discharging the battery to be tested with a current of 5C at a time t4 for 10s, discharging the battery to be tested with a current of 4C at a time t5 for 10s, discharging the battery to be tested with a current of 3C at a time t6 for 10s, discharging the battery to be tested with a current of 2C at a time t7 for 10s, discharging the battery to be tested with a current of 1C at a time t8 for 10 s.
And (4) standing the battery to be tested at the time t9 for 10s, and then entering a charging process.
The charging process comprises:
charging the battery to be tested with a current of 1C at a time t10 for a charging time of 10S, charging the battery to be tested with a current of 2C at a time t11, charging the battery to be tested with a current of 3C at a time t12 for a charging time of 10S, charging the battery to be tested with a current of 4C at a time t13, charging the battery to be tested with a current of 5C at a time t14 for a charging time of 10S, charging the battery to be tested with a current of 6C at a time t15 for a charging time of 10S, charging the battery to be tested with a current of 7C at a time t16 for a charging time of 10S, charging the battery to be tested with a current of 8C at a time t17, and ending the charging process at the time t4 at the charging time of 10.
S4, a power characteristic calculating step of calculating the variation of the terminal voltage difference between the discharging condition and the charging condition of the same current, and summing the squares of all the variations, and squaring the sum of the squares to obtain a power characteristic value, wherein the power characteristic value is better as the value is closer to zero, and conversely, the power characteristic value is worse, and with reference to fig. 4, the specific power characteristic calculating process includes:
s41, calculating a terminal voltage difference at each discharge current change time, specifically:
discharging the battery to be tested at t1 with current of 8C for 10 s; and switching to discharge of the battery to be tested at the current of 7C at the time t2, and recording the voltage sampling value of the battery to be tested at the time t2 as U1, and the voltage sampling value of the battery to be tested at the time t2 as U2, so that the terminal voltage difference delta U1 of the battery to be tested when the battery to be tested is discharged from 8C times to 7C times of the current is U2-U1.
In a specific measurement process, during the discharge duration 10S, voltage acquisition is usually performed for multiple times, so that multiple voltage values may be obtained within the time period, and in order to make the calculation result more accurate, the "previous time" in this embodiment refers to a last group of voltage sampling values without current, and if the voltage is acquired and the current is also acquired, it indicates that the time t2 has passed, and the previous group of data only acquiring the voltage without the current is valid voltage data, that is, U1.
Discharging the battery to be tested at the current of 6C at the time t3, recording the voltage sampling value of the battery to be tested at the previous time of t3 as U3, and recording the voltage sampling value of the battery to be tested at the time t3 as U4, so that the terminal voltage difference delta U2 of the battery to be tested when the battery to be tested is discharged from 7C times to 6C times of the current is U4-U3.
Discharging the battery to be tested at the current of 5C at the time t4, recording the voltage sampling value of the battery to be tested at the previous time of t4 as U5, and recording the voltage sampling value of the battery to be tested at the time t4 as U6, so that the terminal voltage difference delta U3 of the battery to be tested when the battery to be tested is discharged from 6C times to 5C times of the current is U6-U5.
Discharging the battery to be tested at the current of 4C at the time t5, recording the voltage sampling value of the battery to be tested at the previous time of t5 as U7, and recording the voltage sampling value of the battery to be tested at the time t5 as U8, so that the terminal voltage difference delta U4 of the battery to be tested when the battery to be tested is discharged from 5C times to 4C times of the current is U8-U7.
Discharging the battery to be tested at the time t6 by using the current of 3C, recording the voltage sampling value of the battery to be tested at the time t6 as U9, and recording the voltage sampling value of the battery to be tested at the time t6 as U10, so that the terminal voltage difference delta U5 of the battery to be tested when the battery to be tested is discharged from 4C times to 3C times of the current is U10-U9.
Discharging the battery to be tested at the time t7 by using the current of 2C, recording the voltage sampling value of the battery to be tested at the time t7 as U11, and recording the voltage sampling value of the battery to be tested at the time t7 as U12, so that the terminal voltage difference delta U6 of the battery to be tested when the battery to be tested is discharged from 3C times to 2C times of the current is U12-U11.
Discharging the battery to be tested at the time t8 by using the current of 1C, recording the voltage sampling value of the battery to be tested at the time t8 as U13, and recording the voltage sampling value of the battery to be tested at the time t8 as U14, so that the terminal voltage difference delta U7 of the battery to be tested when the battery to be tested is discharged from 2C times to 1C times of the current is U14-U13.
And (4) standing the battery to be tested at the time t9 for 10s, and then entering a charging process. And (3) setting the voltage sampling value of the battery to be tested at the previous time at the time t9 as U15, and the voltage sampling value of the battery to be tested at the time t9 as U16, and obtaining the terminal voltage difference delta U8 from 1C time of discharging to standing of the battery to be tested as U16-U15.
S43, calculating the terminal voltage difference of the charging current change moment in the charging process;
and charging the battery to be tested at the time t10 by using the current of 1C, recording the voltage sampling value of the battery to be tested at the time t10 as U17, and recording the voltage sampling value of the battery to be tested at the time t10 as U18, so that the terminal voltage difference delta U9 of the battery to be tested from standing to charging by using the current of 1C times is U18-U17.
And charging the battery to be tested at the time t11 by using the current of 2C, recording the voltage sampling value of the battery to be tested at the time t11 as U19, and recording the voltage sampling value of the battery to be tested at the time t11 as U20, so that the terminal voltage difference delta U10 of the battery to be tested during charging from the current of 1C times to the current of 2C times is U20-U19.
And charging the battery to be tested at the time t12 by using the current of 3C, recording the voltage sampling value of the battery to be tested at the time t12 as U21, and recording the voltage sampling value of the battery to be tested at the time t12 as U22, so that the terminal voltage difference delta U11 of the battery to be tested when the battery to be tested is charged from the current of 2C times to the current of 3C times is U22-U21.
And charging the battery to be tested at the time t13 by using the current of 4C, recording the voltage sampling value of the battery to be tested at the time t13 as U23, and recording the voltage sampling value of the battery to be tested at the time t13 as U24, so that the terminal voltage difference delta U12 of the battery to be tested when the battery to be tested is charged from the current of 3C times to the current of 4C times is U24-U23.
And charging the battery to be tested at the time t14 by using the current of 5C, recording the voltage sampling value of the battery to be tested at the time t14 as U25, and recording the voltage sampling value of the battery to be tested at the time t14 as U26, so that the terminal voltage difference delta U13 of the battery to be tested when the battery to be tested is charged from 4C times of current to 5C times of current is U26-U25.
And charging the battery to be tested at the time t15 by using the current of 6C, recording the voltage sampling value of the battery to be tested at the time t15 as U27, and recording the voltage sampling value of the battery to be tested at the time t15 as U28, so that the terminal voltage difference delta U14 of the battery to be tested when the battery to be tested is charged from the current of 5C times to the current of 6C times is U28-U27.
And charging the battery to be tested at the time t16 by using the current of 7C, recording the voltage sampling value of the battery to be tested at the time t16 as U29, and recording the voltage sampling value of the battery to be tested at the time t16 as U30, so that the terminal voltage difference delta U15 of the battery to be tested when the battery to be tested is charged from the current of 6C times to the current of 7C times is U30-U29.
And charging the battery to be tested at 8C at the time t17, and recording the voltage sampling value of the battery to be tested at the previous time of t17 as U31 and the voltage sampling value of the battery to be tested at the time t17 as U32 to obtain the terminal voltage difference delta U16 of the battery to be tested when the battery to be tested is charged from 7C times of current to 8C times of current as U32-U31.
S44, calculating power characteristics P according to the following equation;
P=[(△U1-△U16)2+(△U2-△U15)2+(△U3-△U14)2+(△U4-△U13)2+(△U5-△U12)2+(△U6-△U11)2+(△U7-△U10)2+(△U8-△U9)2]1/2。
a power characteristic testing device for a lithium power battery excited by sawtooth waves comprises:
a discharging module that discharges the battery to be tested with a continuously reduced pulse current;
a standing step, in which the battery to be tested is allowed to stand;
the charging module charges the battery to be tested by continuously increased pulse current; the pulse current of the charging step is the reverse order of the pulse current of the discharging step;
and the power calculation module calculates the variation of the end voltage difference when the discharging condition and the charging condition of the same current are carried out, and calculates the sum of the squares of all the variations to obtain the value of the power characteristic, wherein the closer the value is to zero, the better the power characteristic is, and otherwise, the worse the power characteristic is.
As shown in fig. 2, a power characteristic testing system for a lithium power battery excited by a sawtooth wave according to the present embodiment includes a battery pack 100, a charge and discharge source 200, a voltage acquisition device, a display device 500, a processor 300 and a memory 400, where the processor is configured to execute a power characteristic testing method for a lithium power battery excited by a sawtooth wave according to the present embodiment through executing executable instructions; the memory is used for storing the executable instructions of the processor, and in the test process, the battery pack 100, the charging and discharging source 200, the single chip microcomputer 300, the memory 400 and the display system 500 are formed. The battery to be tested is the power battery module 100, and the singlechip 300 controls the battery charging and discharging source 200 to control the realization of all power characteristic test functions
In the testing process, the single chip microcomputer 300 sends out a control signal to enable the battery charging and discharging source 200 to discharge large current of the power battery module, the power battery module is discharged by discharging currents I with different multiplying powers, and meanwhile the battery charging and discharging source 200 collects terminal voltage U of the power battery module 100. After standing for a certain time, the single chip microcomputer 300 sends out a control signal to enable the battery charging and discharging source 200 to charge the power battery module with large current, and the power battery module is charged with charging currents I with different multiplying powers respectively. Meanwhile, the battery charging and discharging source 200 collects the terminal voltage U of the power battery module 100.
In the embodiment, the battery charging and discharging source is adopted to discharge and charge the battery module with large current instantly, the terminal voltage change of the battery module is collected at a high speed, and the terminal voltage change of the power battery is obtained through analysis and calculation, so that the power characteristic of the power battery is reflected. The specific battery pack 100 is an 1865032V/1100 mAh lithium iron phosphate battery module, the charging and discharging source 200 can be a DC/DC circuit, a linear power supply, a switching power supply and the like for charging and discharging the battery module, and the embodiment adopts a domestic CT2001B universal battery charging and discharging tester;
the processor 300 can be an MSP430 single chip microcomputer, a 51 single chip microcomputer, a DSP, a TMS single chip microcomputer, an STM32 single chip microcomputer, a PIC single chip microcomputer, an AVR single chip microcomputer, an STC single chip microcomputer, a Freescale series single chip microcomputer and the like for controlling charging and discharging of a battery charging and discharging source. The single chip microcomputer can be connected with a charging and discharging source in a serial port or bus mode, and the embodiment adopts a 430 single chip microcomputer;
the memory 400 may be SD, USB, E2Data storage devices such as ROM, etc., in the embodiment, devices adopting a USB storage mode are adopted;
the display device 500 may be a desktop computer, a notebook computer, an LED liquid crystal display, an UM12864 liquid crystal display, etc., and is used to display the voltage, current, alarm signal, discharge time, and capacity of the battery module;
the display device 500 is connected with the processor 300 by adopting RS232, RS485 and RS422 serial communication interfaces or Ethernet transmission or CAN bus transmission. The output of the processor 300 is respectively connected with the charging and discharging power supply 200, the memory 400 and the display system 500; the charging and discharging power supply 200 is connected with the battery pack 100; an input of the processor 300 is connected to an output of the battery module 100.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.