CN101034138A - Battery capacity monitoring system - Google Patents

Abstract

A battery capacity monitoring system at least comprises an analog-digital converter ADC, the input end of which is coupled to a battery and used for converting the terminal voltage, the battery output current and the battery surface electromotive force of the battery into corresponding digital signals, a central processing unit CPU, a read-only memory ROM, a random access memory RAM and a clock pulse generator, wherein the clock pulse for the operation of the CPU and the real-time interrupt signal RTC are provided for the CPU, the CPU executes a preset program in the ROM after receiving the RTC interrupt signal, obtains the digital signals at the output end of the ADC for calculating the battery capacity and stores the result in the memory, an SMBus interface reads the battery capacity recorded by the RAM, and the battery capacity is represented by the bright, dark and flash numbers of an LED. Therefore, the purpose of monitoring the electric quantity of the battery can be achieved.

Description

Monitoring system of battery capacity

Technical field

The invention relates to a kind of capacity monitoring system of rechargeable battery, utilize the capacity monitoring system of this battery can bright, dark with light emitting diode in real time, scintillation response battery capacity.

Background technology

Battery can be described as the power resources of all portable electronic devices.Such as mobile phone, mobile computer, personal digital assistant, walkman or the like all depend on battery that electric power is provided.But battery is a kind of device of accumulating electric weight after all, when portable electronic devices uses with regard to the electric energy of consuming cells.When consume to a certain degree make remaining electric energy be not enough to drive the circuit of this device after, a kind of selection is to lose, another selection then recharges.Generally speaking, no matter consider from environmental protection, still from long-time overall average cost consideration, portable electronic devices can be taked the mode of battery recharge mostly, and the electric energy that consumes is originally replenished.

Certainly, battery can provide the consumed power of time that portable electronic product uses and this portable electronic devices closely bound up, also with battery electric power storage ability confidential relation is arranged.

And battery electric power storage ability is also relevant with the memory effect of accumulator material except relevant with the accumulator material of battery.The memory effect of so-called battery is meant battery in use, owing to can not get discharging completely for a long time, causes the phenomenon of the actual capacity of battery less than true capacity.The characteristic of some element in this phenomenon and the battery is relevant.For example early stage nickel-cadmium battery, recent Ni-MH battery or lithium battery all find to have memory effect in various degree.

Rechargeable battery also has a characteristic that must be noted that, promptly battery terminal voltage and battery capacity relation please refer to discharge curve shown in Figure 1.As shown in the figure, have two voltages to move in the discharge curve and fall a little, promptly when battery charge during to state of saturation and battery electric quantity when soon discharging totally, other situation lower curve is mild.In it and the user the most closely bound up be battery electric quantity when soon discharging totally, the battery terminal voltage sharp fall.At this moment, the electric energy that can emit is very limited, this voltage be commonly referred to as ending discharge voltage (Endof Discharge Voltage, EDV).Ending discharge voltage has two kinds, i.e. first kind low-voltage EDV2, and when battery terminal voltage equals EDV, 8% or 7% (this voltage is also referred to as EDV2 sometimes) that the remaining capacity value of battery may be when charging fully.In addition, also having another important parameters is no-voltage EDV, is called EDV0, and the residual electric energy that refers to battery is 0%.In fact, can not to be located at residual electric energy to ending discharge voltage usually be 0% place to the rechargeable battery of portable electronic devices.Because if a portable electronic devices comprises random access memory, battery is no longer power supply suddenly, will cause not storing data or setting loss of user.In addition, if when this device belongs to patient's medical care product, situation is just more serious, because that may cause sufferer to fall into precarious position at once.

Therefore, intelligent battery management system should possess to be had along with the ability of remaining capacity value for user's reference is provided, particularly the remaining capacity value may be when charging fully warned the user at 20%, 10% o'clock in advance.Perhaps at least in just no longer power supply of EDV2, in order to avoid the declaration ahead of time of this battery is died.

Other has any to must be noted that EDV2 is not is unalterable, and it is relevant with environment temperature, cell degradation degree and the cell load electric current (portable electronic devices discharge current) etc. that use.Refer again to discharge curve shown in Figure 1.Merely setting a fixedly EDV threshold monitoring, and ignore the influence of factors such as environment temperature and discharge current to it, is to can not get correct EDV2's.

Summary of the invention

In view of this, the present invention also further provides a kind of capacity monitoring system of rechargeable battery except the bearing calibration that EDV2 is provided, utilize the capacity monitoring system of this battery, can monitor up-to-date battery capacity.In addition, system of the present invention is further bright, dark with light emitting diode, flicker and improve the resolution of reaction cell capacity, and the present invention will consider the discharge current of environment temperature and battery simultaneously, to obtain battery ending discharge voltage more accurately.

A kind of monitoring system of battery capacity comprises an analog-digital converter (ADC) at least, and its input end is coupled to a battery, is converted to corresponding digital signal in order to terminal voltage, battery output current and battery surface electromotive force with this battery; One CPU (central processing unit) (CPU); Read-only access memory (ROM); A random-access memory (ram) and a time clock generator, the time clock of described CPU running is provided and produces real-time time look-at-me (RTC) and give this CPU, after CPU receives the RTC look-at-me, carry out pre-set programs in the ROM, and these digital signals that obtain the ADC output terminal are carried out the calculating of battery electric quantity, and the result is stored in the RAM storer, and the SMBus interface reads the battery electric quantity of RAM record, and bright, dark with LED again, flicker numerical table shows battery capacity.

The hardware interrupts of RTC is provided, and CPU just carries out the interior pre-set programs of ROM and obtains battery related data and calculating thereof.Therefore, monitoring system of battery capacity of the present invention can use minimum cpu resource to reach the remaining capacity that obtains battery under the condition of economizing electric energy most.In addition, LED shows battery capacity with bright, dark, flicker numerical table, therefore, can be under condition only with five LEDs, acquisition is the resolution of unit with 10%.This is beneficial effect of the present invention.

Description of drawings

In conjunction with appended graphic, can understand the plurality of advantages of foregoing and the present invention by following detailed description easily, wherein:

Fig. 1 is the discharge curve synoptic diagram of battery.

Fig. 2 is the block schematic diagram of monitoring system of battery capacity.

Fig. 3 interrupts synoptic diagram for RTC.

The figure number table of comparisons:

15ADC (analog-digital converter) 20CPU (CPU (central processing unit))

25 gate generator 30ROM (read-only access memory)

35SMBus interface 38 main frames

Embodiment

As previously mentioned, the ending discharge voltage of battery capacity 7% (7%-EDV or claim EDV2) is since relevant with battery temperature, lasting discharge current etc., so just be necessary to find out a formula, this formula is a variable with battery temperature and discharge current, to obtain EDV2 more accurately.

According to one embodiment of the invention, EDV2 can obtain according to discharge curve, please refer to Fig. 1, and horizontal ordinate is a battery capacity, and ordinate is the terminal voltage of whole string electric battery.Whole string electric battery is meant that battery connected by many batteries.The present invention summarizes discharge curve according to many experimental datas and satisfies following experimental formula (two linear equation in two unknowns formulas):

(I) EDV2=EMC* (256-(discharge current/64+Q_T) * EDV_gain/256)/256

(II) EDV0=EMC* (256-(discharge current/64+Q_T) * EDV_factor/256)/256

Wherein, have only discharge current and Q_TBe the variable relevant with temperature, the discharge current that note that (I) formula is to be unit with mA, and Q_TBe with formula (III) Q_T=[480-(T-5) * 10] * 8/256 calculates and obtains, and this formula is an experimental formula.Only pipe so, when at (I) and (II) calculating, just no longer tube discharge electric current and Q_TUnit, promptly be used as no unit dimension and calculate.

EMC, EDV_gain and EDV_factor then are the parameters of being correlated with, (I) formula all has an identical parameter EMC in reaching (II), and a different parameter is arranged respectively, parameter EDV_gain is in (I) formula, and parameter EDV_factor is in (II) formula, and these three parameters can be utilized default boundary condition and obtain.

Boundary condition (1) is set in 25 ℃ of environment temperatures; with the discharge rate of about 50% battery capacity per hour; recharge till be discharged to holding circuit in the battery management chip (figure do not show) and close discharge by complete, in the discharge process then whole process draw discharge curve.For instance; formed by three crosstalk ponds approximately such as the battery that mobile computer is used; typical volume is 4400mAHr, and then discharge rate is set in continuous discharge under the electric current of 2200mA, and every crosstalk pond was about 3V when the holding circuit in the battery management chip was closed discharge.Total series side voltage in three crosstalk ponds promptly is considered as the EDV0 under 25 ℃ at this moment.EDV2 then finds out (or calculate according to integration method) by discharge curve.Two other boundary condition (2) and (3) can be located at respectively under 45 ℃ and the 5 ℃ of environment temperatures, use the same terms to obtain.Certainly, temperature shown in the above-mentioned boundary condition and discharge rate are only for example convenient for explanation, because during practical operation, also can be the arbitrary temperature between the arbitrary temperature between 40 ℃ to 50 ℃ and 0 ℃ to 10 ℃.In addition, discharge rate also is, so long as rapid discharge gets final product, for example between 30% to 70% all can, be not in order to limit scope of the present invention.

According to the foregoing description, obtain three Q with (III) formula respectively with 5 ℃, 25 ℃ and 45 ℃_TValue, i.e. Q_T1, Q_T2, Q_T3Value, discharge current is the above-mentioned 2200mA of substitution then.According to above-mentioned (I) formula and (II) formula two unknown numbers are respectively arranged, promptly in (I) formula EMC and EDV_gain are arranged, and (II) in the formula EMC, EDV_factor are arranged, the boundary condition of gained can be put into and get final product, so, need only two boundary conditions.

Therefore, when the experimental formula of hypothesis above-mentioned EDV2 and EDV0 and discharge curve were in full accord, then two linear equation in two unknowns formulas should only get final product with two boundary conditions.But it should be noted that above-mentioned formula is an experimental formula after all, therefore, puts an intermediate value temperature (room temperature) more, measures discharge curve, in order to revise when the discharge curve of measuring departs from experimental formula.Show that according to experimental data of the present invention deviation value is many within the allowable error of experiment (being typically below 5%).

When EMC, EDV_gain, three parameters of EDV_factor, utilize after discharge curve under the above-mentioned boundary condition obtains, utilize again monitoring system of battery capacity of the present invention just can revise under discharge current and temperature arbitrarily by discharge temp.

Above-mentioned correction to EDV2 is the framework that depends on following system of the present invention, please refer to Fig. 2, comprise an ADC (analog-digital converter) 15, a CPU (CPU (central processing unit)) 20, atime clock generator 25, a ROM (read-only access memory) 30, oneSMBus interface 35 and LED 40.Gate generator 25 provides CPU the time clock of 20 runnings.According to system of the present invention,gate generator 25 provides one to interrupt toCPU 20, because this interruption is the pulse wave signal as shown in Figure 3 that is produced bygate generator 25 in a default set time.The cycle of these pulse wave signals is about 0.5 second (but must not be), at pulse wave signal when low, trigger CPU and produce the pin that interrupts (interrupt), interrupt to produce, therefore being called RTC (real time clock) interrupts,CPU 20 is when RTC interruption each time, output/input interface is with the battery related data of main frame (host), temperature such as battery, the magnitude of voltage of present load current (discharge current) and battery, afterADC 15 is converted to digital signal, read byCPU 20, with the residual electric energy of the program counting cell that prestores in the ROM, result of calculation is stored in working storage or the RAM storer again.As SMBus (smart batterymanagement; When the intelligent battery management)interface 35 moved, CPU can be shown in residual electric energy on the LED according to the content of working storage.Main frame also can be read residual electric energy viaSMBus interface 35.

In detail, when electric current flows through a known pull-up resistor value, as long as obtain the simulating signal of the cross-pressure of pull-up resistor, again throughADC 15 be converted to digital signal the time,CPU 20 is as long as just can learn load current value according to the size of this digital signal.The magnitude of voltage of battery then also can be learnt through the conversion ofADC 15 by the terminal voltage of battery, offerCPU 20 again.The temperature of battery then obtains electromotive force by for example small-sized thermopair of temperature sensor, and electromotive force offersCPU 20 via the conversion ofADC 15, just can learn the temperature of battery.The residual electric energy of the digital signal that 20 foundations of CPU obtain (being the signal of magnitude of voltage afterADC 15 conversions of battery temperature, load current and battery) counting cell.

Generally speaking, battery capacity is to be unit of account with Milliampere Hour (mAHr), even will reach the remaining capacity of certain monitoring battery, the time that each RTC interrupts, just must be proofreaied and correct.According to embodiments of the invention, interrupting as above-mentioned each RTC is regular length, be about 0.5 second, but the not necessarily real time, therefore, the calculation procedure in the ROM of the present invention is just done time adjustment earlier before dispatching from the factory, promptly in the RTC of the certain number of accumulation, have no progeny, for example 120 RTC interrupt, and utilize the pulse reference clock of main frame or known clock, the time of proofreading and correct each RTC.Therefore, according to embodiments of the invention, crystal oscillator can be very accurately but crystal oscillator at a low price get final product.After trying to achieve the real time, the battery remaining electric energy can utilize the coulometer algorithm to calculate the electric capacity that flows to and flow out battery.

Be exactly in more detail: the quantity of electric charge of the quantity of electric charge-battery self discharging that flows out during the quantity of electric charge that flows to during the quantity of electric charge when battery remaining power=battery is full of+battery charge-battery discharge.

The so-called quantity of electric charge is exactly an electric current to the integration of time, promptly utilizes the voltage by resistance to calculate electric current.If being negative value, voltage difference then is considered as discharge, discharge capacity is deposited among the discharge working storage DC (dischargecounter), if on the occasion of then being considered as charging, charging capacity is deposited among the charging working storage CC (chargecounter), under the condition of not considering the battery self discharging, the difference of CC and DC be exactly integral battery door residual capacity RM (remaining capacity, RM=CC-DC).

For making things convenient for the user to understand battery remaining capacity, be to show with fiveLEDs 40 to represent that the resolution of demonstration can reach 10% battery capacity according to a preferred embodiment of the present invention.When five LEDs lined up for 5 whens row, following formula can allow user's present residual capacity of interpretation battery at an easy rate.

When flicker wherein: capacity=(a bright number-1) * 20%+1 flicker * (0 to 10%)

When LED is not bright when being exactly dark: capacity=(a bright number-1) * 20%+ (10% to 20%)

Also can allow the user read the remaining capacity of battery at an easy rate according to the following form of above two formula:

Form one is when using five LEDs to represent remaining capacity.

1	2	3	4	5	Battery capacity %
						Bright	Bright	Bright	Bright	Bright	90-100
Bright	Bright	Bright	Bright	Flicker	80-90
						Bright	Bright	Bright	Bright		70-80
Bright	Bright	Bright	Flicker		60-70
						Bright	Bright	Bright			50-60
Bright	Bright	Flicker			40-50
						Bright	Bright				30-40
Bright	Flicker				20-30
						Bright					10-20
Flicker					0-10

Certainly, using five LEDs (resolution is 10%) only is a wherein preferred embodiment.Use four LEDs to represent that remaining capacity (resolution is 12.5%) or three (resolution is in 16%) even two (resolution is 25%) or one (resolution is 50%) are good.

For example, when using four LEDs to represent remaining capacity, please refer to form two.

Form two

1	2	3	4	Battery capacity %
					Bright	Bright	Bright	Bright	87.5-100
Bright	Bright	Bright	Flicker	75-87.5
					Bright	Bright	Bright		62,5-75
Bright	Bright	Flicker		50-62.5
					Bright	Bright			37.5-50
Bright	Flicker			25-37.5
					Bright				12.5-25
Flicker				0-12.5

When using three LEDs to represent remaining capacity, please refer to form three.

Form three

1	2	3	Battery capacity %
				Bright	Bright	Bright	83-100
Bright	Bright	Flicker	66-83
				Bright	Bright		50-66
Bright	Flicker		33-50
				Bright			16-33
Flicker			0-16

In sum, the present invention has following advantage:

(1) according to monitoring system of battery capacity of the present invention, crystal oscillator can be very accurately but crystal oscillator at a low price get final product.

(2) because interruption of the present invention is to be produced by the RTC hardware interrupts, CPU20 only goes to carry out the relevant data of battery when RTC interrupts, rather than the software interruption that just produces when carrying out a program of CPU20, therefore, according to monitoring system of battery capacity of the present invention, the monitoring of battery electric quantity can not take the resource of too many CPU20, can save the power consumption of CPU wholesale yet.CPU20 can do other data processing relevant with battery when the non-RTC of above-mentioned pulse wave interrupts.

(3) have only the LED of (five) on a small quantity, just resolution can be promoted be 10% battery capacity.

Though the present invention illustrates as above with preferred embodiment, so it is not that the modification of being done in not breaking away from spirit of the present invention and scope all should be included in the claim scope in order to qualification the present invention.

Claims (5)

Translated fromChinese

1.一种电池容量监测系统，其特征在于包含：1. A battery capacity monitoring system, characterized in that it comprises:一模拟数字转换器ADC，其输入端耦合至一电池，用以将该电池的端电压、电池输出电流及电池表面电动势转换为对应的数字信号；An analog-to-digital converter ADC, the input terminal of which is coupled to a battery for converting the terminal voltage of the battery, the battery output current and the battery surface electromotive force into corresponding digital signals;一中央处理单元CPU；a central processing unit CPU;只读存取存储器ROM；Read-only access memory ROM;随机存取存储器RAM；random access memory RAM;一时钟脉冲产生器，提供所述CPU运作的时钟脉冲及产生实时时间中断信号RTC给该CPU，该CPU在收到RTC中断信号后执行ROM内预设程序，并取得ADC输出端的数字信号进行电池电量的计算，并将结果储存于RAM存储器或暂存器；A clock pulse generator, which provides the clock pulse for the operation of the CPU and generates a real-time time interrupt signal RTC to the CPU. After receiving the RTC interrupt signal, the CPU executes the preset program in the ROM, and obtains the digital signal at the output of the ADC for battery processing. Calculation of power, and store the result in RAM memory or temporary register;多颗发光二极管LED；及a plurality of light emitting diodes LED; andSMBus接口，该SMBus接口动作时，CPU依据RAM存储器或暂存器记录的电池电量，以所述LED的亮、暗、闪烁数表示。SMBus interface, when the SMBus interface is in action, the CPU indicates the number of lights, darks, and flickers of the LED according to the battery power recorded by the RAM memory or the temporary register.2.如权利要求1所述的系统，其特征在于，所述的RTC中断每0.5秒中断一次，且在电池容量监测系统出厂前即先行校正，以求出1分钟真正时间下中断次数，藉以计算出电池的残余电量。2. The system according to claim 1, wherein the RTC interrupt is interrupted once every 0.5 seconds, and the battery capacity monitoring system is calibrated before leaving the factory, so as to obtain the number of interrupts in real time of 1 minute, thereby Calculate the remaining charge of the battery.3.如权利要求1所述的系统，其特征在于，所述的LED颗数为五颗并排成五排，并且以下列公式计算其容量：3. The system according to claim 1, wherein the number of said LEDs is five and arranged in five rows, and the capacity is calculated by the following formula:当其中一颗闪烁时：容量＝(亮的颗数-1)×20％+1颗闪烁×(0至10％)；When one of them flashes: capacity = (number of bright ones - 1) x 20% + 1 flashing x (0 to 10%);当LED不是亮就是暗时：容量＝(亮的颗数-1)×20％+(10％至20％)。When the LED is either bright or dark: capacity = (number of bright ones - 1) x 20% + (10% to 20%).4.如权利要求1所述的系统，其特征在于，所述的每一RTC的发生的时间以累积一定数额的RTC中断后中断，利用主机的参考时钟脉冲或已知的时钟校正，以得出平均发生一次RTC中断的时间。4. The system according to claim 1, characterized in that, the occurrence time of each RTC is interrupted after accumulating a certain amount of RTC interrupts, and the reference clock pulse or known clock correction of the host computer is used to obtain The average time for an RTC interrupt to occur.5.如权利要求1所述的系统，其特征在于，所述的LED颗数为四颗并排成4排，其分辨率为12.5％；所述LED颗数为三颗并排成三排，其分辨率为16％；所述LED颗数为二颗并排成二排，其分辨率为25％。5. The system according to claim 1, wherein the number of said LEDs is four and arranged in four rows, and its resolution is 12.5%; the number of said LEDs is three and arranged in three rows , the resolution is 16%; the number of LEDs is two and arranged in two rows, and the resolution is 25%.

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