CN111092268A

CN111092268A - Maintenance method for lead-acid storage battery

Info

Publication number: CN111092268A
Application number: CN201911265062.4A
Authority: CN
Inventors: 孙燕; 朱诗顺; 张丽杰; 马超
Original assignee: Army Military Transportation University
Current assignee: Army Military Transportation University
Priority date: 2019-12-11
Filing date: 2019-12-11
Publication date: 2020-05-01
Anticipated expiration: 2039-12-11
Also published as: CN111092268B

Abstract

The invention discloses a self-maintenance method of a lead-acid storage battery, which applies charge-discharge pulses with certain frequency to the storage battery, and the charge-discharge pulses enable active substances in the storage battery to be always in an activated state. The method has the advantages that the method can break the condition of PbSO4 crystallization, prevent the lead-acid storage battery from vulcanization failure and prolong the service life of the storage battery.

Description

Maintenance method for lead-acid storage battery

Technical Field

The invention relates to the technical field of maintenance of lead-acid storage batteries, in particular to a maintenance method of a lead-acid storage battery.

Background

The main reason for the sulfuration failure of the lead-acid storage battery is that the storage battery is in a standing state for a long time, and particularly after the storage battery is discharged and placed in an untimely supplementary charging mode, active substances on a polar plate of the storage battery are quickly subjected to sulfuration crystallization to generate coarse PbSO₄Crystals, leading to failure of the active. In order to prolong the service life of the storage battery, the vulcanized negative plate is mainly repaired by adopting the following technology at present:

1. the action mechanism of the method is that the sulfate formed by slight sulfuration on the surface of the overcharged polar plate is washed by the gas precipitated from the polar plate, so that the sulfate is desorbed, dissolved and converted into active substances. The method has the advantages that the sulfate is acted by the storage battery overcharge and gassing, the action effect is not large, the method can only be used for repairing the slightly vulcanized storage battery, the waste battery with high vulcanization degree does not act, the active substances of the positive plate are strongly washed while the precipitated gas washes the sulfate, the active substances are softened and even fall off, and the service life of the storage battery is seriously influenced.

2. The hydrotherapy has the action mechanism that the solubility product of sulfate is improved by reducing the acid liquid density, ohmic polarization is reduced by adopting small-current long-time charging to delay the early occurrence of water decomposition voltage, and finally the vulcanization phenomenon is gradually reduced or eliminated in the process of dissolving and converting into active substances. The method is mainly used for vulcanizing and repairing the non-sealed lead-acid storage battery, but the process is very complicated, a large amount of manpower is wasted, and the used large amount of sulfuric acid can cause serious environmental pollution.

3. Chemical remediation, the mechanism of action of which is the addition of a sulfate coordination dopant to a sulfurized lead acid battery solution, to form a coordination compound with many metal ions, including sulfide salts. The formed coordination compound is unstable in an acid medium, and the non-conductive vulcanized layer is gradually dissolved back to the solution, so that the polar plate is vulcanized, desorbed and dissolved. The repair efficiency and the efficacy of the chemical additive method are high, but the operation is too complicated.

4. High voltage and high current breakdown method, the mechanism of action of which is due to PbSO₄The crystals being non-conducting substances, with PbSO₄The crystal grains grow and the resistance thereof increases. When a high voltage source is applied to the two poles of the storage battery, the large PbSO is applied under the action of the high voltage₄The crystals will break down into small particles, which have a higher solubility, PbSO₄The crystals gradually become smaller and dissolve into the solution. The elimination of vulcanization by this method only produces a temporary effect because the high voltage and high current exacerbate the loss of water and softening of the positive plate of the battery during the elimination of vulcanization, causing irreparable damage to the battery and resulting in the end of the battery life.

5. Pulse sulfurThe chemical repair method and the pulse vulcanization repair method have the action mechanism that: if an instantaneous high voltage is applied to the sulfate layer having a large difference in electrical conductivity, large PbSO can be applied₄Breakdown of the crystal to make PbSO₄The crystal grains become small and the activity is restored again. However, although this method can recover the capacity of the battery during use, the service life of the recovered battery is short. The large current and high voltage used in the pulse repairing process damage the polar plates of the storage battery, so that the polar plates deform, and the insulating partition plates between the polar plates also generate unrecoverable damage, so that the insulating property is reduced, and the service life of the storage battery is directly shortened.

Although the repairing technology can repair the vulcanized lead-acid storage battery to a certain degree, the repairing technology has certain defects and seriously influences the service life of the storage battery, so that a new scheme is urgently needed to be designed so as to effectively prevent the lead-acid storage battery from being vulcanized, and the service life of the storage battery is prolonged.

Disclosure of Invention

The application aims to provide a self-maintenance method of a lead-acid storage battery, so that the lead-acid storage battery is effectively prevented from being vulcanized, and the service life of the storage battery is prolonged.

In order to achieve the purpose of the invention, the scheme provided by the invention is as follows: a self-maintenance method for lead-acid accumulator features that the charge-discharge pulse with a certain frequency is applied to the accumulator to make the active substance in accumulator always in activated state.

Compared with the prior art, the method has the beneficial effect that the PbSO can be broken through by using the method₄The condition of crystallization prevents the lead-acid storage battery from vulcanization failure, and prolongs the service life of the storage battery.

Drawings

FIG. 1 is a schematic diagram illustrating the steps of the method of the present application;

FIG. 2 is a schematic view of the maintenance device of the present application;

FIG. 3 is a schematic circuit diagram of a main circuit of the maintenance device of the present application;

FIG. 4 is a schematic diagram of an equivalent circuit of the main circuit when the maintenance device of the present application is connected to both ends of the battery;

FIG. 5 is a schematic diagram of an equivalent circuit of the MOS transistor of the maintenance device of the present application when the MOS transistor is turned on;

FIG. 6 is a schematic diagram of an equivalent circuit of the MOS transistor of the maintenance device of the present application when the MOS transistor is turned off;

FIG. 7 is a pin diagram of the ATtiny24 single chip microcomputer of the present application;

FIG. 8 is a basic circuit diagram of the ATtiny24 single chip microcomputer;

FIG. 9 is a schematic diagram of a power supply voltage conversion circuit of the maintenance device of the present application;

FIG. 10 is a schematic diagram of a driving circuit of a MOS transistor of the maintenance device of the present application;

FIG. 11 is a flow chart illustrating system control of the maintenance device of the present application;

fig. 12 is a schematic structural view of the maintenance device externally arranged on the upper end cover of the storage battery.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Examples

As shown in fig. 1, in the self-maintenance method for a lead-acid battery of this embodiment, a charge-discharge pulse with a certain frequency is applied to the battery, and the charge-discharge pulse keeps the active material inside the battery in an activated state, so as to break PbSO₄The condition of crystallization prevents the lead-acid storage battery from vulcanization failure, and prolongs the service life of the storage battery.

The principle of self-maintenance of lead-acid storage batteries is as follows: the sulfur ions have 5 different energy level states, and ions in metastable energy level states tend to exist by migrating to stable covalent bond energy level states. Sulfur in a stable covalent bond energy level state as a ring-shaped molecule comprising 8 atomsThe 8-atom ring molecular pattern is a relatively stable combination, and is difficult to jump and break. PbSO₄The sulfur atom in the crystal is in this stable energy state. To break the structure of these sulfide layers, a certain amount of energy needs to be provided to the ring-shaped molecules to promote the electrons charged by the outer atoms to be activated to the next high-energy band, so as to release the binding between the atoms. Because each specific energy level has a unique resonant frequency, the transition atoms are in an unstable state due to the fact that energy beyond the resonant frequency is too high, and the atoms are not bound by the atomic groups due to the fact that energy beyond the resonant frequency is too low, so that the pulse maintenance device generates pulses with a certain frequency and resonates with sulfur atoms, the sulfur atoms can be converted into free ions dissolved in electrolyte, participate in electrochemical reaction again, and are converted into active substances again, and self-maintenance of the lead-acid storage battery is achieved.

1. Test research shows that the service life of the lead-acid storage battery is obviously prolonged compared with the common lead-acid storage battery after the lead-acid storage battery is additionally provided with the maintenance device;

2. the circuit design simulation research, the storage battery structure design and the feasibility test research of the storage battery maintenance device show that the development technical route of the self-maintenance type lead-acid storage battery is feasible.

Specifically, the storage battery is self-maintained by the storage battery maintenance device.

Integral structure design of storage battery

The battery maintenance device is a set of circuit system, and the inside strong acid environment of lead acid battery corrodes very seriously to circuit system, and simultaneously, in order not to influence the normal use of battery, the size of battery can not increase too much, consequently, will carry out the structural design of automatic maintenance type lead acid battery upper end cover, need arrange a installation space for the maintenance device on the battery upper end cover. Fig. 12 is a schematic view of the maintenance device being disposed outside the battery.

When the maintenance device was arranged the battery outside, lower the requirement of the acid liquid corrosion prevention function of maintenance device, when being nearer apart from utmost point post moreover, realized maintenance device and be connected of utmost point post easily. And through customization maintenance device shell, it has dustproof, waterproof function to integrate with the battery case, can bear certain degree of mechanical shock.

In order to realize the integration of the storage battery maintenance device and the storage battery, the maintenance device needs to be reliably fixed on the storage battery shell, and the adhesion mode of epoxy resin glue and a heat sealing method is determined to be adopted through deep research on the production and processing technology of the storage battery.

The epoxy resin adhesive is an adhesive used for sealing the end cover and the shell of the lead-acid storage battery, is prepared from epoxy resin and an accelerator (or a curing agent), and is hardened in about half an hour. It has the performances of sealing, acid liquid corrosion resistance and certain mechanical strength impact resistance. Therefore, the epoxy glue can be used for fixing the maintenance device and the end cover of the storage battery. And the adhesive can also be bonded by adopting a heat sealing method. For the battery jar and the casing of the maintenance device made of polypropylene or polyethylene material, a heat sealing method can be adopted, namely a controllable electric heater is used for heating to just reach the plastic softening temperature, and then the battery jar and the casing are compacted and cooled to achieve the purposes of installation and fixation.

When the outgoing line of the maintenance device is connected with the pole column, a wire groove for arranging wires can be reserved in the device shell mold. When the lead is connected with the pole, a through hole with a smaller diameter can be formed in the pole, and the lead is introduced and then is firmly welded by lead. And then injecting mark paint into the connecting part of the pole and the lead for sealing. The wire groove is lower than the plane of the upper end cover of the storage battery. After the sealing, the lead of the maintenance device is completely protected in the shell of the maintenance device.

In addition, the current collector is one of the important components of the lead-acid battery, and the plate grid of the current lead-acid battery still takes lead-calcium alloy as the basis and can be reinforced by adding bismuth.

In addition, the lead-acid battery has the electrode surface passivation caused by the sulfation of the electrode plate, which seriously influences the discharge capacity and the cycle life of the battery during heavy-current discharge. The selection of proper electrolyte additive can improve the large-current discharge capacity and the cycle life, and on one hand, the requirement of improving the electrochemical performance of the battery is improved; on the other hand, the market application needs of vehicles such as mopeds and the like are expanded.

The lead-acid storage battery active material comprises positive and negative plate active materials and an electrolyte active material. Proved and researched, the additive suitable for the military lead-acid storage battery mainly comprises a positive plate: graphite, SnO, Bi₂O₃And RSO₃H; negative plate: lignin, humic acid, lignocellulose and BaSO₄(ii) a Electrolyte solution: alkali metal and NH⁴⁺。

The lead-acid accumulator has a general service life of 2-3 years, and because the active substances on the surface of the plate do not recrystallize in the initial stage of use of the new lead-acid accumulator, the sulfuration of the plate is gradually accumulated in the use of the accumulator. Therefore, if the self-maintenance storage battery is used for inspection, the period of the inspection and maintenance effect test is long, the effect is obvious only after the storage battery is recycled for several months or even longer, and meanwhile, the influence of other factors in the test process is difficult to eliminate due to the overlong test period.

Aiming at the above, a rapid test method for the vulcanization of the lead-acid storage battery is adopted, and the impact method utilizing the alternate change of the environmental temperature is provided to shorten the test period. According to the crystal crystallization law, if the temperature changes in the recrystallization process, the crystallization of the crystals can be accelerated, and the storage battery pack using the lead-acid storage battery self-maintenance method is placed in the environment of 40 ℃ and-20 ℃ respectively for standing for a long time according to a certain test method. The recrystallization speed of the lead sulfate on the surface of the polar plate can be accelerated by the cyclic impact of two environments with larger temperature difference.

The specific principle is as follows: the frequent low-current deep discharge of the storage battery can lead to the generation of more lead sulfate in the deep layer of the plate, and the lead sulfate is agglutinated and attached to the deep part of the micropore of the active substance, so that the lead sulfate is not easy to fully act on the inner layer of the plate to reduce the lead sulfate in normal charging. Meanwhile, the two opposite processes of dissolution and crystallization of the lead sulfate in the electrolyte can be alternately carried out by the alternate change of the environmental temperature, the formation of large-grain lead sulfate is promoted and promoted, and the lead sulfate grains are deeply formed and cannot be recovered due to overhigh temperature, so that the recrystallization process of the crystals is accelerated. The specific method of low-current deep discharge comprises the following steps: charging a storage battery for 3 hours at 25 +/-2 ℃ by using a current of 10A, then placing the storage battery in a high-temperature box at the temperature of 40 ℃ for 12 hours to ensure that the internal temperature of the storage battery reaches 40 ℃, adjusting a storage battery testing system to ensure that the storage battery discharges by using the current of 3A until the voltage reaches a cut-off voltage of 10.50V +/-0.05V, placing the storage battery for 12 hours at normal temperature, then charging the storage battery for 3 hours by using the current of 10A, then placing the storage battery in low-temperature equipment at the temperature of-20 ℃ for 12 hours to ensure that the temperature of the storage battery reaches-20 ℃, adjusting the storage battery testing system to ensure that the storage battery discharges by using the current of 3A until the voltage reaches the cut-off voltage of 10.50V +/-0.05V, and taking the discharge as a cycle. The battery plates were observed after 30 cycles each.

In order to eliminate the influence of environmental changes on the self-maintenance verification test results, a plurality of groups of storage batteries are put into the same environment for testing, and the formulated test rules are shown in the following table 1.

TABLE 1

In the experiment, in order to obtain ideal effect, the following technical measures are adopted:

(1) when the device performs low-voltage alarm, the storage battery is charged in time, and the ambient temperature of the storage battery cannot be changed in the charging process;

(2) distilled water is supplemented to the electrolyte of the storage battery in time, and particularly, the checking and supplementing frequency is properly increased at the ambient temperature of 40 ℃;

(3) and periodically removing frost in the refrigerator so as to avoid short circuit of the storage battery in the test process.

The service life of the automatic maintenance lead-acid storage battery and the service life of the common lead-acid storage battery can be checked by a traditional method of directly detecting the capacity. However, the method has a long period and is greatly influenced by other factors in the test process.

Therefore, in the embodiment, the service life of the storage battery is detected by adopting an observation method, and the maintenance effect is indirectly represented by observing the crystallized crystals by using instrument equipment.

And (3) determining lattice parameters by using an X-ray powder diffractometer, and performing qualitative and quantitative analysis on the phase. The test adopts a standard sample-free quantitative method to carry out quantitative analysis on the substances and determine the content of the substances. In order to ensure the accuracy of the test result, a mode of collecting the polar plate powder at multiple points, namely collecting the powder at two ends of the diagonal line and at three middle points of the polar plate, is adopted for observation, and the powder images are recorded as the powder images of the polar plates from 1# to 3# of the storage battery respectively.

After the image is obtained, MDI (diphenylmethane diisocyanate) jade6.5 software is adopted to analyze the image, and the functions of background subtraction, peak area calculation and smooth curve calculation of the software are mainly applied. During image processing, a standard library is required to be used for fitting the wave crest of the substance, then the area of the wave crest of the substance is divided by the total area of the curve to obtain the content of the substance, and the content is compared and researched through test results on different polar plates, so that quantitative analysis is carried out.

In order to facilitate experimental observation, the storage battery polar plate adopts a movable polar plate so as to be taken out at any time and sample the powder of the storage battery polar plate. Therefore, the movable plate type non-sealed lead-acid storage battery for the test is manufactured by self, and the purchased storage battery adopts an assembly mode of three positive plates and four negative plates. For manufacturing the movable polar plate, the self-made storage battery unit cell adopts an assembly mode of two positive plates and three negative plates, and an upper end cover is changed into a corrosion-resistant film, so that the non-sealing of the storage battery is ensured, and the water evaporation of electrolyte is reduced.

In order to determine the influence of the automatic maintenance type lead-acid storage battery on the storage battery pole plate, a comparison test of the automatic maintenance type lead-acid storage battery and a common storage battery is carried out.

After 30 times of cycle test, the polar plates of the two groups of storage batteries are taken out for observation. And performing a 10-90-degree diffraction test on the negative plate of the storage battery to obtain powder contrast images of the positions of the polar plates from 1# to 3# of the storage battery.

And (3) analyzing the test result curve by using MDI jade6.5 software, determining the diffraction peak of the PbSO4 crystal phase by using the peak-to-height ratio, calculating the area of the diffraction peak, and if the highest peak is influenced by other elements, selecting the proportion of the secondary peak to the secondary peak of the PbSO4 crystal phase diffraction in a PDF card library, converting the proportion into the highest peak, calculating the area of the peak, and then calculating the content of the peak in the polar plate.

The crystal parameters of PbSO4 in the self-maintenance lead-acid battery and the conventional battery are analyzed as shown in Table 2. The data in the table 2 show that the crystal content of PbSO4 in the storage battery embedded in the maintenance device after deep discharge of high-low temperature small current is reduced by 44.46% compared with that of the storage battery after deep discharge, so that the vulcanization of the storage battery plate is effectively reduced, and the maintenance effect is obvious. When only the factor of the sulfation of the plate of the storage battery is considered, the service life of the storage battery embedded with the maintenance device can be effectively prolonged, and the automatic maintenance type lead-acid storage battery has obvious advantages in the aspect of preventing the sulfation of the plate.

TABLE 2

In accordance with the battery maintenance method, there is provided a battery maintenance device,

as shown in fig. 2, the battery maintenance device comprises a power module, a detection module, a signal indication module, a control module, a boost energy storage module and an electronic switch module,

the device is a self-source device taking a storage battery as energy. Firstly, sampling the voltage of a storage battery for judgment, boosting the voltage of the storage battery through boosting transformation when the voltage is normal, adding the boosted voltage to two ends of an energy storage capacitor to charge the capacitor, and after waiting for a certain time, enabling the energy in the capacitor to flow through a discharge loop and be recharged into the storage battery to finish a charge-discharge pulse. The control module controls an MOS tube on the charge-discharge loop to realize the adjustment of the charge-discharge pulse frequency, and simultaneously, the purpose of controlling the charge-discharge pulse amplitude can be achieved by adjusting the resistance value of a potentiometer on a voltage feedback circuit of the boosting energy storage module. When the storage battery voltage is too low, the electric quantity of the storage battery is insufficient, the device can generate sound and light alarm, and prompt personnel to charge the storage battery in time.

The main circuit of the storage battery maintenance device adopts a Boost topological circuit to realize the Boost function of the circuit, and the frequency and amplitude of charge and discharge pulses are mainly controlled by the conduction and the disconnection of an MOS (metal oxide semiconductor) tube.

The switch MOS tube of the storage battery maintenance device is controlled by the pulse with the duty ratio of D and is alternatively switched on or switched off, so that an oscillating circuit consisting of an inductor and a capacitor is controlled to complete the rising and the lowering of the 12V voltage of the storage battery, a charge-discharge pulse is formed, and simultaneously, the charge-discharge process of voltage pulse on two ends of the storage battery is completed, and a main circuit is shown in fig. 3. The fuse GP60 is mainly used for protecting the circuit when the circuit is short-circuited and overcurrent; d2 is a fast recovery diode, which mainly has the function of preventing the reverse connection of the maintenance device; d3 is also a fast recovery diode and has the primary function of blocking the inductor L3 path while charging the capacitor.

The working process of the circuit is as follows:

when the maintenance device is connected with two ends of the storage battery, the MOS tube is in a turn-off state, and an equivalent circuit of the MOS tube is shown in fig. 4.

When the circuit starts to work, the MOS tube is in a normally-off state, and the two ends of the storage battery are connected with L2 and C1. The battery charges C1 through L2. Because the inductor has the effect of inhibiting the current change, when the circuit is conducted, the current passing through the inductor is still 0A, at the moment, according to the kirchhoff voltage law, the voltage of the two ends of the capacitor is 0V due to no storage of electric charges, the voltage of the two ends of the inductor is 12V, and the direction is positive left and negative right.

When the current in the circuit gradually increases, the capacitor stores the charge flowing through the inductor, the voltage of the capacitor gradually increases, and the voltage of the capacitor gradually decreases. When the voltage drop at the two ends of the inductor is 0, the voltage at the two ends of the capacitor is 12V, at the moment, the current direction cannot be changed due to the effect of the inductor, the capacitor is continuously charged, meanwhile, the voltage at the two ends of the inductor is reversely increased, and the forward voltage at the two ends of the capacitor is also increased. When the current in the circuit is reduced to 0A, the voltage at the two ends of the capacitor reaches the maximum value, and the voltage at the two ends of the inductor reaches the reverse maximum value. At the moment, because the voltage at the two ends of the capacitor is greater than the voltage at the two ends of the storage battery, the storage battery is charged by the capacitor, and also because of the action of the inductor, the voltage drop at the two ends of the capacitor can exceed 12V in the charging process, and when the current is reversed again, the next cycle is started. Further analyzing the steady state process of the circuit, the voltage at two ends of the capacitor reaches 12V after the circuit is subjected to a plurality of cyclic oscillations, the current flowing through the inductor after the circuit is in a steady state is 0A, and the battery is in a discharging state.

When the voltage of the storage battery is detected to be equal to or higher than a program set value in the single chip microcomputer, the single chip microcomputer provides voltage square wave pulses for the MOS tube driving circuit in an instant conduction state of the MOS tube. Fig. 5 shows an equivalent circuit diagram of the MOS transistor when it is instantaneously turned on. Since only the inductors L2 and L3 are in the main loop of the circuit across the battery, the time for the MOS transistors to conduct must be short enough, otherwise it is equivalent to short-circuiting the battery.

At the moment of the conduction of the MOS tube, due to the effect of the inductor, left positive and right negative induced electromotive forces can appear at two ends of the inductor. The induced electromotive force at the two ends of the inductor can inhibit the change of the current flowing through the inductor, and the current flowing through the L2 and the L3 is zero when the inductor is instantly conducted, but the current can increase along with the increase of time. At this time, the battery is in a discharging state, and the current flows back to the battery through L2 and L3 under the blocking action of the inductor. At the same time, due to the circuit path, the charge stored in the capacitor C1 will be released, but the current across the inductor L2 will not change direction immediately, and it can be determined from the inductance values of L2 and L3 that the rate of change of the current flowing through L3 is greater than the rate of change of the current flowing through L2, so the charge discharged by the capacitor C1 will flow back to the battery through the inductor L2, and the direction of the current flowing through is shown in fig. 6. During this phase, the battery is always in a discharged state, and its terminal voltage will drop to some extent, which will generate a discharge pulse of the battery.

When the MOS tube is instantly turned off, the storage battery discharges for a period of time, and the MOS tube driving circuit provides a low-voltage pulse turn-off MOS tube for the MOS tube. When the MOS transistor is turned off, the loop of the main circuit changes, and the equivalent circuit diagram is shown in fig. 6. Since the current flowing through the two ends of the inductor does not change immediately, the current still flows through the diode D1 through the inductor L2 and flows back to the positive electrode of the storage battery, and in order to prevent the rapid disappearance of the current when the MOS transistor is turned off, the two ends of the inductor L3 generate a high-value induction.

The method for selecting the key components of the circuit comprises the following steps:

1) inductance and capacitance model selection calculation

The maintenance device mainly realizes a boosting function by an inductor in a Boost topological circuit and then recharges high voltage to two ends of the storage battery. Input voltage V of main circuit_INIs 12V, the boost voltage V_OAt 22V, a duty cycle of 1/12, and an average charging current of about 0.7A, i.e., I, through L2_O20.7A; the average charging current through L3 is about 3.2A, i.e., I_O3＝3.2A。

Therefore, inductance L2 is calculated as follows:

in the formula:

V_O-the output voltage of the Boost topology circuit,

V_IN-the input voltage of the Boost topology circuit,

d is the duty ratio of the pulse width modulation signal,

I_L2-the current through the inductance L2.

Taking the current ripple rate r as 0.6 and the oscillator frequency as 8.3kHz, then:

in the above formula V_ONIs the voltage across the inductor during the MOSFET conduction period. For Boost topology circuit V_ON＝V_IN. In consideration of loss, the design selects the parameters of the inductor L2 as rated current 2A and inductance of 270 muH.

Similarly, the inductance L3 can be calculated by the formula:

in the formula:

V_O-the output voltage of the Boost topology circuit,

V_IN-the input voltage of the Boost topology circuit,

d is the duty ratio of the pulse width modulation signal,

I_L3-the current through the inductance L3.

in the above formula, the first and second carbon atoms are,

V_ONis the voltage across the inductor during the MOSFET conduction period. For Boost circuit V_ON＝V_IN. In consideration of loss, the inductor L3 parameter is designed and selected to be rated current 4A, and the inductance is 60 muH. The capacitor C1 is used as a filter capacitor, and because the main circuit boost voltage reaches 22V, in order to avoid the instantaneous flyback electromotive force breakdown of the capacitor, the parameter of the capacitor C1 is designed and selected to be 35V in voltage level and 220 muF in capacitance standard.

2) MOS transistor model selection calculation

In research, the higher the frequency of the maintenance device is, the better the maintenance effect on the lead-acid storage battery is, the pulse frequency of the existing lead-acid storage battery protector product is comprehensively analyzed, and the pulse frequency of the maintenance device is preferably set to be about 8 kHz. Meanwhile, the pulse frequency of the protector is mainly influenced by the switching frequency of the MOS tube, so the switching frequency of the MOS tube is about 8 kHz. Because the turn-on voltage of the MOS tube is about 4.3V, the maximum grid voltage of the selected power tube should be less than 4.3V. The main circuit can raise the voltage to 22V, and considering that the flyback electromotive force generated by the inductor can reach 90V, the voltage-resistant grade of the selected power switch tube should exceed 117V. Meanwhile, the peak current of the selected power switch tube is more than 4.6A considering that the current flowing through the inductor L2 reaches 3.5A instantaneously.

According to the conditions and combining the junction temperature and the shell temperature of the MOS tube, the model of the power switching tube selected by the main circuit design is IRF630, the starting voltage of the switching tube is 4V, the withstand voltage value is 200V, the on-resistance of the drain electrode and the source electrode is 400m omega, the pulse current which can be borne under the condition of 25 ℃ reaches 9A, and the power consumption is very low.

NI Multisim software is an EDA tool software that is specialized for electronic circuit simulation and design. And (4) completing the construction of a main circuit simulation model of the maintenance device by utilizing Multisim software.

The control circuit of the storage battery maintenance device adopts a digital circuit.

The digital circuit scheme adopts a microprocessor technology on hardware and realizes the functions of the circuit through software program control. The hardware system of the designed device comprises a DC/DC module, a detection module, a signal indication module, a control module, a boosting module, a power MOSEFT electronic switch and other modules.

1) Control chip type selection and control circuit design

The control unit is used for controlling the storage battery online maintenance device, and in order to meet the requirements of low power consumption and miniaturization in the overall design, the microcontroller selects an ATtiny24 singlechip of ATmel company. The pin diagram is shown in fig. 7. The ATtiny24 singlechip is a peripheral circuit of basic operation, as shown in FIG. 8.

The 4-pin of ATtiny24 single chip has reset function, if a lower value continuously appears in the time of its minimum pulse width, the reset is generated. The 6-pin transmits the square wave with certain frequency to a drive circuit of the MOS tube to control the time and frequency of the on-off of the MOS tube. The 12 pins are voltage sampling pins, one end of each voltage sampling pin is connected with a main circuit fuse and then samples the battery voltage, then the numerical value is provided for the ATtiny singlechip, the light emitting diodes are controlled through the 10 pins and the 11 pins and the buzzer is controlled through the 2 pins after program analysis in the chip, namely if the battery voltage is lower than 11.8V, the buzzer of the protector gives an alarm, and the light emitting diodes of the 10 pins and the 11 pins are alternatively lightened. The 13-pin obtains a determined voltage through the accurate voltage stabilization chip 431, and meanwhile, the C4 and the C5 are connected in parallel to filter noise waves and serve as a reference voltage of A/D conversion. The 14 pins are grounded, and the 5, 8 and 9 pins are in air connection. The 1 pin of the ATtiny24 single chip provides the working voltage of the single chip, because the voltage at the two ends of the storage battery is 12V and the working voltage of the single chip is 5V, a voltage stabilizing regulator is needed to convert the voltage.

The principle of the maintenance device power voltage conversion circuit is shown in fig. 9.

The 7805 chip is a three-terminal positive regulator that can provide a fixed 5V output voltage. When the input voltage is higher than the output voltage by 4V-7V, the output voltage is relatively stable. The output current can reach 500mA, and the over-temperature protection and short-circuit protection functions are realized. The input end of the chip is connected with the ground and the output end of the power supply module, the output end of the chip provides 5V output voltage, the input end of the chip is connected with the capacitor C1 in parallel, and the output end of the chip is connected with the capacitor C2 in parallel, so that noise waves on a circuit are filtered.

The principle of the MOS transistor driving circuit of the maintenance device is shown in FIG. 10.

The MOS tube of the maintenance device is connected with a 6-pin of an ATtiny24 singlechip through a switch end, a square wave pulse with a certain frequency is obtained from the 6-pin, and the square wave pulse passes through R10 and C9 and then is subjected to current limiting filtering. When the square wave high level appears at the common base electrode of the PNP type triode Q1 and the NPN type triode Q2, the Q2 is conducted, the MOS tube control end is connected with the ground, and the low level is provided for the MOS tube; when the low level of the square wave appears at the common base of the two triodes, Q1 is conducted, the control end of the MOS tube is connected with +5V, and then the high level of +5V is supplied to the MOS tube. Through the alternate conduction of Q1 and Q2, a voltage pulse can be provided for the MOS transistor to control the conduction and the disconnection of the MOS transistor, wherein the high level of the voltage pulse is 5V, and the low level of the voltage pulse is 0V.

The storage battery maintenance device adopts an AVR ATtiny24 singlechip as a control chip, combines the design of a peripheral circuit, uses C language to compile, and develops a set of software program for realizing the function of the maintenance device.

1) System control flow design

Fig. 11 shows a flow of system control of the maintenance device.

Firstly, initializing a program in a single chip microcomputer, including the initialization value of each register, the zero setting of a timer/counter and an AD acquisition register, the selection of interrupt control and the starting of an interrupt function. After the initialization is completed, the whole program enters the while (1) loop. The method comprises the steps of collecting terminal voltages at two ends of a storage battery in a first step in a cycle, comparing the terminal voltages with parameters set by a system, when the voltage of the storage battery is smaller than a program set value by 11.5V, judging that the voltage of the storage battery is too low and is in a power-deficient or semi-power-deficient state by a program, turning on a buzzer and a flash diode by a maintenance device, and giving warning sounds and alternately flashing a traffic light to a worker to warn the worker to prompt the worker to charge the storage battery. If the value is larger than or equal to the set parameter, the voltage of the storage battery is normal, the maintenance device starts an online maintenance function, the indicator lamp is turned on, the buzzer is turned off, and the maintenance device is displayed to work normally. At this time, the single chip outputs a voltage square wave with a certain frequency to the MOS tube driving circuit to drive the MOS tube in the charge-discharge loop. And the voltage pulse frequency and amplitude formed by the charge-discharge loop are controlled by switching off and switching on the MOS tube.

2) Programming

When the storage battery is in a static state, the terminal voltage of the storage battery is relatively stable, and the change amplitude is very small. However, when the storage battery is in a use state, the maintenance device is still connected in parallel to the two ends of the storage battery to work, the terminal voltage changes along with the charging and discharging of the storage battery, and when the current is very large, the terminal voltage changes very obviously, once the maintenance device collects the changed voltage, the real state of the storage battery cannot be reflected, and therefore the module makes a misjudgment and gives an alarm wrongly. Therefore, when a hardware circuit is designed, a capacitor is adopted for power supply filtering, and certain noise waves can be filtered. Meanwhile, a certain software filtering technology is adopted, so that the reliability of the sampling value is improved. When writing the program, a clipping average filtering algorithm is used.

Firstly, the device collects the voltage value at two ends of the storage battery, the value is required to be within a normal range of the voltage of the storage battery, if the value is beyond the normal range, the value is invalid, and the storage battery is discarded. If the value is within this range, the value is added to a variable. And then waiting for a certain time interval, sampling again, still judging the value, accumulating the value into the variable or discarding the value, and recording the accumulation times. After accumulating for a certain number of times, stopping sampling, taking the average value of the variable as the normal value of the voltage of the storage battery at the moment, and judging and executing the program.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A maintenance method of a lead-acid storage battery is characterized in that,

by applying a charge-discharge pulse with a certain frequency to the storage battery, the charge-discharge pulse enables the active substances in the storage battery to be in an activated state all the time.