CN114421764A - Battery charging circuit, DC-DC converter and battery charging method - Google Patents
Battery charging circuit, DC-DC converter and battery charging method Download PDFInfo
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- CN114421764A CN114421764A CN202111683291.5A CN202111683291A CN114421764A CN 114421764 A CN114421764 A CN 114421764A CN 202111683291 A CN202111683291 A CN 202111683291A CN 114421764 A CN114421764 A CN 114421764A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
Abstract
The invention discloses a battery charging circuit, a DC-DC converter and a battery charging method, wherein the battery charging circuit comprises a controlled current source, a first switch module, a second switch module and a control module; the first end of the first switch module is electrically connected with the output end of the controlled current source, and the second end of the first switch module is electrically connected with the positive electrode end of the battery; the first end of the second switch module is electrically connected with the negative pole end of the battery and the input end of the controlled current source respectively, and the second end of the second switch module is electrically connected with the output end of the controlled current source; the control module is used for collecting a first voltage between the second end of the first switch module and the first end of the second switch module and controlling the first switch module and the second switch module to be switched on and off according to the first voltage. The battery charging circuit has the advantages of high response speed, directly controlled charging current, easiness in adjustment, higher precision of the charging current and difficulty in occurrence of overcharge.
Description
Technical Field
The invention relates to the technical field of battery charging, in particular to a battery charging circuit, a DC-DC converter and a battery charging method.
Background
As shown in fig. 1, a constant-current and constant-voltage charging process of a lithium battery is performed, in the charging process, constant-current charging is performed with a constant current, and when a charging voltage reaches a predetermined value, constant-voltage charging is performed; during the constant voltage charging, the charging current is gradually reduced, and when the charging current drops to a predetermined value, the battery is fully charged. In the charging process of the lithium battery, in order to realize constant current and constant voltage charging, the charging and discharging current is generally regulated and controlled, and the constant current and the constant voltage are maintained by regulating the charging current.
In the prior art, DC-DC converters for charging batteries generally adopt topology circuits such as boost, buck, boost-buck, etc., and fig. 2 shows a common topology circuit of boost. These topologies generally use a voltage source to provide the charging current; however, in the charging process of the battery, no matter in the constant-current charging stage or the constant-voltage charging stage, the constant current and the constant voltage are realized by adjusting the charging current, and the voltage source is used as the input, so that the control of the charging current is not direct enough, and the adjusting speed is not fast enough.
In addition, the conventional topology circuit requires a certain recovery time when adjusting the charging voltage, and has a problem of insufficient response speed. In the boost topology circuit shown in fig. 2, when the output voltage is increased, the on time of the switching tube S3 needs to be increased, but in the first period, the on time of S3 is increased, the on time of S4 is decreased, the output voltage is decreased, and a certain time is needed to recover to the steady-state voltage. In order to avoid the influence of the non-minimum phase characteristic of the boost topology circuit on the system stability, the general method is to design the closed-loop bandwidth of the system to be far smaller than the turning frequency of the right half-plane zero point, but this is undoubtedly at the expense of the rapidity of the system dynamic response. During the charging process of the battery, the voltage of the battery is always changed, so that the system needs to have a relatively high response speed to maintain constant voltage charging.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a battery charging circuit which is high in response speed and capable of effectively realizing constant-current and constant-voltage charging of a battery.
The invention also provides a DC-DC converter with the battery charging circuit.
The invention also provides a battery charging method.
In a first aspect, a battery charging circuit according to an embodiment of the present invention includes a controlled current source, a first switch module, a second switch module, and a control module; the first end of the first switch module is electrically connected with the output end of the controlled current source, and the second end of the first switch module is electrically connected with the positive end of the battery; the first end of the second switch module is electrically connected with the negative pole end of the battery and the input end of the controlled current source respectively, and the second end of the second switch module is electrically connected with the output end of the controlled current source; the control module is used for collecting a first voltage between the second end of the first switch module and the first end of the second switch module, and controlling the connection and disconnection of the first switch module and the second switch module according to the first voltage, so that chopping control is performed on the output current of the controlled current source, and constant-voltage charging of the battery is achieved.
The battery charging circuit according to the embodiment of the invention has at least the following beneficial effects: the charging current is provided by adopting the controlled current source, and the conduction time of the first switch module and the second switch module is controlled by the control module, so that the constant-current and constant-voltage charging of the battery is realized; the whole circuit has the advantages of high response speed, directly controlled charging current, easy adjustment, higher precision of the charging current and difficult occurrence of overcharge.
According to some embodiments of the invention, the first switching module comprises a first switching tube and the second switching module comprises a second switching tube.
According to some embodiments of the invention, further comprising a filtering unit disposed between both the first and second switch modules and the battery.
According to some embodiments of the invention, the control module comprises a hysteresis comparator and a driving unit, wherein a positive input end of the hysteresis comparator is connected with the first voltage, and a negative input end of the hysteresis comparator is connected with a reference voltage; the input end of the driving unit is electrically connected with the output end of the hysteresis comparator, and the output end of the driving unit is electrically connected with the controlled end of the first switch module and the controlled end of the second switch module respectively.
According to some embodiments of the invention, further comprising a current source generation module for generating the controlled current source.
According to some embodiments of the invention, the current source generation module employs a three-level buck circuit or a full-bridge topology circuit.
In a second aspect, a DC-DC converter according to an embodiment of the invention includes a battery charging circuit according to an embodiment of the first aspect of the invention.
The DC-DC converter according to the embodiment of the invention has at least the following beneficial effects: by adopting the battery charging circuit, the response speed is high, the charging current is directly controlled and is easy to adjust, the precision of the charging current is higher, the overcharge condition is not easy to occur, and the constant-current and constant-voltage charging of the battery can be effectively realized.
In a third aspect, a battery charging method according to an embodiment of the present invention includes a constant voltage charging process including the steps of: presetting an upper limit voltage value and a lower limit voltage value; in the charging process, when the first voltage rises to the upper limit voltage value, the control module controls the first switch module to be switched off and the second switch module to be switched on so as to reduce the first voltage; when the first voltage drops to the lower limit voltage value, the control module controls the first switch module to be switched on and the second switch module to be switched off so as to enable the first voltage to rise to the upper limit voltage value; and repeating the process until the battery is charged. The battery charging method provided by the embodiment of the invention has at least the following beneficial effects: the constant-voltage charging of the battery can be effectively realized, the charging current is directly controlled and is easy to adjust, the precision of the charging current is higher, the overcharge condition is not easy to occur, and the whole control method is simpler and more reliable.
According to some embodiments of the invention, further comprising a constant current charging process, the constant current charging process comprising the steps of: presetting a first voltage value; and carrying out constant current charging on the battery until the charging voltage of the battery rises to the first voltage value, and then starting the constant voltage charging process.
According to some embodiments of the present invention, the constant-current charging of the battery is performed until the charging voltage of the battery rises to the first voltage value, and then the constant-voltage charging process is started, specifically: the control module controls the first switch module to be switched on and the second switch module to be switched off, the controlled current source provides constant current to charge the battery at constant current, and the constant voltage charging process is started until the charging voltage of the battery rises to the first voltage value.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of a lithium battery charging process;
FIG. 2 is a circuit schematic of a prior art boost topology circuit;
FIG. 3 is a schematic circuit diagram of a battery charging circuit according to an embodiment of the present invention;
FIG. 4 is a schematic circuit diagram of the battery charging circuit shown in FIG. 3 when the first switch module is turned on;
FIG. 5 is a schematic circuit diagram of the battery charging circuit shown in FIG. 3 when the second switch module is turned on;
FIG. 6 is a schematic circuit diagram of a battery charging circuit according to a first embodiment of the present invention;
FIG. 7 is a detailed circuit schematic diagram of a battery charging circuit according to a second embodiment of the present invention;
FIG. 8 is a schematic diagram illustrating the operation of the battery charging circuit of FIG. 7 during constant voltage charging;
fig. 9 is a schematic diagram showing the change of the charging voltage and charging current waveforms during the constant voltage charging process of the battery charging circuit shown in fig. 7;
FIG. 10 is a schematic circuit diagram of a three-level buck circuit according to an embodiment of the present invention;
FIG. 11 is a schematic circuit diagram of a full bridge topology circuit according to an embodiment of the present invention;
FIG. 12 is a flowchart illustrating steps of a constant voltage charging process according to an embodiment of the present invention;
fig. 13 is a flowchart illustrating steps of a constant current charging process according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
In a first aspect, referring to fig. 3 to 7, a battery charging circuit according to an embodiment of the present invention includes a controlled current source, a first switching module 100, a second switching module 200, and a control module 300; a first end of the first switch module 100 is electrically connected with an output end of the controlled current source, and a second end of the first switch module 100 is electrically connected with a positive terminal of the battery; a first end of the second switch module 200 is electrically connected with the negative electrode end of the battery and the input end of the controlled current source respectively, and a second end of the second switch module 200 is electrically connected with the output end of the controlled current source; the control module 300 is configured to collect a first voltage Uo between the second end of the first switch module 100 and the first end of the second switch module 200, and control the first switch module 100 and the second switch module 200 to be turned on and off according to the first voltage Uo, so as to perform chopping control on the output current of the controlled current source, thereby implementing constant-voltage charging on the battery.
Specifically, according to the battery charging circuit of the embodiment of the invention, a controlled current source is adopted to provide a charging current; as shown in fig. 3 to 5, in the constant current charging process, the controlled current source can provide a constant charging current for the battery by only turning on the first switch module 100 and turning off the second switch module 200, so as to implement constant current charging; in the constant-current charging process, the charging voltage continuously rises, and when the charging voltage reaches a preset value, the constant-voltage charging is converted; in the constant-voltage charging process, as shown in fig. 7 to 9, an upper limit voltage value Ua and a lower limit voltage value Ub are preset, the control module 300 collects the first voltage Uo, when the first voltage Uo rises to the upper limit voltage value Ua, the control module 300 controls the first switch module 100 to be switched off and the second switch module 200 to be switched on, at this time, the current provided by the controlled current source does not pass through the battery, the battery is not charged, and the first voltage Uo gradually falls; when the first voltage Uo decreases to the lower limit voltage value Ub, the control module 300 controls the first switch module 100 to be switched on and the second switch module 200 to be switched off, the controlled current source continues to charge the battery, so that the first voltage Uo gradually increases to Ua, and then the states of the first switch module 100 and the second switch module 200 are switched, so that the first voltage Uo decreases to Ub again; the above process is continuously repeated until the charging of the battery is completed. In the process of constant-voltage charging of the battery, the pulse of the charging current is controlled by continuously switching the conducting states of the first switch module 100 and the second switch module 200, so as to control the average charging current of the battery, and finally, the average charging voltage of the battery is kept unchanged; namely, the constant-voltage charging of the battery is realized by carrying out chopping control on the output current of the controlled current source. As shown in fig. 8 and 9, in the constant-voltage charging process, as the charging process proceeds, the battery is charged with more and more electric power, the voltage of the battery is higher and higher, the voltage difference with the charging voltage is smaller, and the chargeable current is smaller; the on-time of the first switch module 100 is gradually reduced, the on-time of the second switch module 200 is gradually increased, the average charging current is gradually reduced, and the battery charging current is also gradually reduced until the battery is fully charged; constant voltage charging of the lithium battery is maintained throughout the whole stage. Here, the charging voltage may fluctuate slightly during the constant voltage charging, but the waveform of the charging voltage is shown as a straight line in fig. 9.
Therefore, according to the battery charging circuit provided by the embodiment of the invention, the charging current is provided by adopting the controlled current source, and the on-time of the first switch module 100 and the second switch module 200 is controlled by the control module 300, so that the constant-current and constant-voltage charging of the battery is realized; the whole circuit has the advantages of high response speed, directly controlled charging current, easiness in adjustment, high charging current precision and low possibility of overcharge, and the structure and the control method of the whole circuit are simple and reliable.
As shown in fig. 6 and 7, in some embodiments of the present invention, the first switching module 100 includes a first switching tube S1, and the second switching module 200 includes a second switching tube S2. The first switch transistor S1 and the second switch transistor S2 may be MOS transistors, such as Si-based MOS transistors, GaN-based MOS transistors, and the like. It is understood that the first and second switch modules 100 and 200 may also employ other common switch elements, such as relays, etc., without being limited thereto.
As shown in fig. 6 and 7, in some embodiments of the present invention, a filtering unit 400 is further included, and the filtering unit 400 is disposed between both the first and second switching modules 100 and 200 and the battery.
Specifically, as shown in fig. 6, the filter unit 400 includes a first capacitor C1 and a first inductor L1, one end of the first capacitor C1 is electrically connected to the second end of the first switch module 100, and the other end of the first capacitor C1 is electrically connected to the negative terminal of the battery and the first end of the second switch module 200, respectively; one end of the first inductor L1 is electrically connected to one end of the first capacitor C1, and the other end of the first inductor L1 is electrically connected to the positive terminal of the battery. The first capacitor C1 and the first inductor L1 form a filtering unit 400, which filters the charging current to obtain a smooth current signal, and charges the battery.
Alternatively, as shown in fig. 7, the filtering unit 400 may also employ a pi-type filter. The pi-type filter comprises a capacitor C2, an inductor L2 and a capacitor C3, wherein one end of the capacitor C2 is electrically connected with the second end of the first switch module 100, and the other end of the capacitor C2 is electrically connected with the negative electrode end of the battery and the first end of the second switch module 200 respectively; one end of the inductor L2 is electrically connected to one end of the capacitor C2, the other end of the inductor L2 is electrically connected to the positive terminal of the battery and one end of the capacitor C3, respectively, and the other end of the capacitor C3 is electrically connected to the negative terminal of the battery and the other end of the capacitor C2, respectively. The capacitor C2, the inductor L2 and the capacitor C3 form a filtering unit 400, which filters the charging current to obtain a smooth current signal, and then charges the battery.
It is understood that the filtering unit 400 may also adopt other common filtering loops, and is not limited thereto.
As shown in fig. 7, in some embodiments of the present invention, the control module 300 includes a hysteresis comparator and a driving unit, a positive terminal of the hysteresis comparator is connected to the first voltage Uo, and a negative terminal of the hysteresis comparator is connected to the reference voltage Vref; the input end of the driving unit is electrically connected to the output end of the hysteresis comparator, and the output end of the driving unit is electrically connected to the controlled end of the first switch module 100 and the controlled end of the second switch module 200, respectively. The driving unit may adopt an existing IGBT module or a common driving chip, and is configured to control the on-time of the first switch module 100 and the second switch module 200.
As shown in fig. 8 and 9, in the constant voltage charging process, the first voltage Uo drops to Ub at time t0, at this time, the first voltage Uo connected to the positive input terminal of the hysteresis comparator is lower than the reference voltage Vref connected to the negative input terminal, the hysteresis comparator outputs a high level, the driving unit controls the first switch module 100 to be turned on, the second switch module 200 to be turned off, the controlled current source charges the battery, and the first voltage Uo rises. At time t1, the first voltage Uo at the inverting input of the hysteresis comparator has increased to be equal to the reference voltage Vref at the inverting input, but according to the characteristics of the hysteresis comparator, the hysteresis comparator will continue to maintain the original state; this state is maintained until Uo rises to Ua, that is, at time t2, when the hysteresis comparator flips and outputs low level, the driving unit controls the first switch module 100 to be turned off, the second switch module 200 is turned on, the battery is not charged by the controlled current source, the charging current drops, the first voltage Uo drops, and this state is maintained until time t 3. And then, the process is repeatedly circulated, and finally, the constant-voltage charging process of the lithium battery is completed. As shown in fig. 10 and 11, in some embodiments of the invention, a current source generation module is further included for generating a controlled current source. The current source generating module can adopt an existing three-level buck circuit, a full-bridge topology circuit or other switching power supply circuits.
As shown in fig. 10, which is a three-level buck circuit, the principle of generating the controlled current source is as follows: in the first stage, the switching tubes S5 and S7 are turned on, the switching tubes S6 and S8 are turned off, the voltage Vc across the capacitor C5 rises through the switching tube S5, the capacitor C5, the switching tube S7 and the inductor L4 by the voltage source, the current across the inductor L4 rises, and the output current rises; in the second stage, the switching tubes S5 and S6 are turned off, the switching tubes S7 and S8 are turned on, and the capacitor C5 cannot form a loop, so the voltage Vc remains unchanged, the current on the inductor L4 linearly decreases, and the output current decreases; in the third stage, the switching tubes S6 and S8 are turned on, the switching tubes S5 and S7 are turned off, the capacitor C5 supplies energy to the load through the switching tube S6, the voltage Vc drops, the current on the inductor L4 rises, and the output current rises; in the fourth stage, the switching tubes S5 and S6 are turned off, the switching tubes S7 and S8 are turned on, and the capacitor C5 cannot form a loop, so that the voltage Vc remains unchanged, the current on the inductor L4 linearly decreases, and the output current decreases. The current can be increased by increasing the conducting time of the switch tubes S5 and S6, and the current can be reduced by reducing the conducting time of the switch tubes S5 and S6, so that the controlled current source is charged and discharged.
As shown in fig. 11, which is a full-bridge topology circuit, the principle of generating the controlled current source is as follows: when the switching tubes S9 and S12 are turned on and the switching tubes S10 and S11 are turned off, the current on the primary side of the transformer T1 flows from top to bottom, the switching tubes S13 and S16 are turned on by the coupling of the transformer T1, and the switching tubes S14 and S15 are turned off, so that the rectification of energy is realized, the current of the inductor L5 rises, and the output current rises; when the switching tubes S9, S10, S11 and S12 are turned off, the switching tubes S13, S14, S15 and S16 are turned off, the current of the inductor L5 gradually drops, and the output current drops; when the switch tubes S9 and S12 are turned off and the switch tubes S10 and S11 are turned on, the primary current of the transformer T1 flows from bottom to top, the switch tubes S13 and S16 are turned off by the coupling of the transformer, the switch tubes S14 and S15 are turned on to realize the rectification of energy, the current of the inductor L5 rises, and the output current rises; when the switching tubes S9, S10, S11 and S12 are turned off, the switching tubes S13, S14, S15 and S16 are turned off, the current of the inductor L5 gradually drops, and the output current drops. The current can be increased by increasing the conducting time of the switch tubes S9 and S12 or the switch tubes S10 and S3, and the current can be reduced by reducing the conducting time of the switch tubes S9 and S12 or the switch tubes S10 and S11, so that the charging and discharging of the controlled current source are realized.
In a second aspect, according to the DC-DC converter of the embodiment of the present invention, by using the above battery charging circuit, the response speed is fast, the charging current is directly controlled and is easy to adjust, the accuracy of the charging current is higher, and the overcharge is not easy to occur.
In a third aspect, as shown in fig. 12, a battery charging method according to an embodiment of the present invention includes a constant voltage charging process including the steps of:
step S100: an upper limit voltage value Ua and a lower limit voltage value Ub are preset.
Step S200: in the charging process, when the first voltage Uo rises to the upper limit voltage value Ua, the control module 300 controls the first switch module 100 to be switched off and the second switch module 200 to be switched on, so that the first voltage Uo falls; when the first voltage Uo decreases to the lower limit voltage value Ub, the control module 300 controls the first switch module 100 to be turned on and the second switch module 200 to be turned off, so that the first voltage Uo increases to the upper limit voltage value Ua; and repeating the process until the battery is charged.
Specifically, as shown in fig. 7 to 9, when the battery is charged at a constant voltage, in an initial state, the first switch module 100 is turned on, the second switch module 200 is turned off, and at this time, the battery is charged by the controlled current source, and the first voltage Uo gradually rises; when the first voltage Uo rises to the upper limit voltage value Ua, the control module 300 controls the first switch module 100 to be switched off and the second switch module 200 to be switched on, and at the moment, the controlled current source does not charge the battery, so that the first voltage Uo falls; at time t0, the first voltage Uo drops to Ub, at this time, the first voltage Uo connected to the positive input terminal of the hysteresis comparator is lower than the reference voltage Vref connected to the negative input terminal, the hysteresis comparator outputs a high level, the driving unit controls the first switch module 100 to be turned on, the second switch module 200 is turned off, the controlled current source charges the battery, and the first voltage Uo rises. At time t1, the first voltage Uo at the inverting input of the hysteresis comparator has increased to be equal to the reference voltage Vref at the inverting input, but according to the characteristics of the hysteresis comparator, the hysteresis comparator will continue to maintain the original state; this state is maintained until Uo rises to Ua, that is, at time t2, when the hysteresis comparator flips and outputs low level, the driving unit controls the first switch module 100 to be turned off, the second switch module 200 is turned on, the battery is not charged by the controlled current source, the charging current drops, the first voltage Uo drops, and this state is maintained until time t 3. And then, the process is repeatedly circulated, and finally, the constant-voltage charging process of the lithium battery is completed.
In the process of constant-voltage charging of the battery, the pulse of the charging current is controlled by continuously switching the conducting states of the first switch module 100 and the second switch module 200, so as to control the average charging current of the battery, and finally, the average charging voltage of the battery is kept unchanged; namely, the constant-voltage charging of the battery is realized by carrying out chopping control on the output current of the controlled current source. As shown in fig. 8 and 9, in the constant-voltage charging process, as the charging process proceeds, the battery is charged with more and more electric power, the voltage of the battery is higher and higher, the voltage difference with the charging voltage is smaller, and the chargeable current is smaller; the on-time of the first switch module 100 is gradually reduced, the on-time of the second switch module 200 is gradually increased, the average charging current is gradually reduced, and the battery charging current is also gradually reduced until the battery is fully charged; constant voltage charging of the lithium battery is maintained throughout the whole stage.
It should be noted that, regarding the specific values of the upper limit voltage Ua and the lower limit voltage Ub, those skilled in the art can make reasonable selection according to the charging voltage of the battery. Assuming that the charging voltage required by the battery is 5V, Ua may be set to 5.05V, and Ub may be set to 4.95V, although Ua and Ub may be other reasonable values.
As shown in fig. 13, the battery charging method according to the embodiment of the present invention further includes, before the above-mentioned constant voltage charging process, a constant current charging process, the constant current charging process including the steps of:
step S300: the first voltage value is preset.
Step S400: and carrying out constant-current charging on the battery until the charging voltage of the battery rises to a first voltage value, and then starting the constant-voltage charging process.
Specifically, as shown in fig. 7, in order to implement constant current charging on the battery, the control module 300 controls the first switch module 100 to be turned on, and the second switch module 200 to be turned off, so that the controlled current source provides a constant current to perform constant current charging on the battery, so that the charging voltage gradually rises, and when the control module 300 detects that the charging voltage rises to the first voltage value, the above-mentioned constant voltage charging process is started.
According to the battery charging method provided by the embodiment of the invention, the constant-current and constant-voltage charging of the battery can be effectively realized, the charging current is directly controlled and is easy to adjust, the accuracy of the charging current is higher, the overcharge condition is not easy to occur, and the whole control method is simpler and more reliable.
In the description herein, references to the description of "one embodiment," "a further embodiment," "some specific embodiments," or "some examples," etc., mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A battery charging circuit, comprising:
a controlled current source;
the first end of the first switch module is electrically connected with the output end of the controlled current source, and the second end of the first switch module is electrically connected with the positive electrode end of the battery;
a first end of the second switch module is electrically connected with the negative electrode end of the battery and the input end of the controlled current source respectively, and a second end of the second switch module is electrically connected with the output end of the controlled current source;
the control module is used for collecting a first voltage between the second end of the first switch module and the first end of the second switch module, and controlling the first switch module and the second switch module to be switched on and off according to the first voltage, so that chopping control is performed on the output current of the controlled current source, and constant-voltage charging of the battery is realized.
2. The battery charging circuit of claim 1, wherein the first switching module comprises a first switching tube and the second switching module comprises a second switching tube.
3. The battery charging circuit of claim 1, further comprising a filtering unit disposed between both the first and second switch modules and the battery.
4. The battery charging circuit of claim 3, wherein the control module comprises:
a forward input end of the hysteresis comparator is connected with the first voltage, and a reverse input end of the hysteresis comparator is connected with a reference voltage;
and the input end of the driving unit is electrically connected with the output end of the hysteresis comparator, and the output end of the driving unit is respectively electrically connected with the controlled end of the first switch module and the controlled end of the second switch module.
5. The battery charging circuit of claim 1, further comprising a current source generation module configured to generate the controlled current source.
6. The battery charging circuit of claim 5, wherein the current source generation module employs a three-level buck circuit or a full-bridge topology circuit.
7. A DC-DC converter comprising a battery charging circuit according to any of claims 1 to 6.
8. A battery charging method based on the battery charging circuit as claimed in claim 3 or 4, characterized by comprising a constant voltage charging process, the constant voltage charging process comprising the steps of:
presetting an upper limit voltage value and a lower limit voltage value;
in the charging process, when the first voltage rises to the upper limit voltage value, the control module controls the first switch module to be switched off and the second switch module to be switched on so as to reduce the first voltage; when the first voltage drops to the lower limit voltage value, the control module controls the first switch module to be switched on and the second switch module to be switched off so as to enable the first voltage to rise to the upper limit voltage value; and repeating the process until the battery is charged.
9. The battery charging method according to claim 8, further comprising a constant current charging process, the constant current charging process comprising the steps of:
presetting a first voltage value;
and carrying out constant current charging on the battery until the charging voltage of the battery rises to the first voltage value, and then starting the constant voltage charging process.
10. The method of claim 9, wherein said constant-current charging said battery until said charging voltage of said battery rises to said first voltage value, and then starting said constant-voltage charging process comprises:
the control module controls the first switch module to be switched on and the second switch module to be switched off, the controlled current source provides constant current to charge the battery at constant current, and the constant voltage charging process is started until the charging voltage of the battery rises to the first voltage value.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111683291.5A CN114421764A (en) | 2021-12-31 | 2021-12-31 | Battery charging circuit, DC-DC converter and battery charging method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111683291.5A CN114421764A (en) | 2021-12-31 | 2021-12-31 | Battery charging circuit, DC-DC converter and battery charging method |
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| CN114421764A true CN114421764A (en) | 2022-04-29 |
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| CN202111683291.5A Pending CN114421764A (en) | 2021-12-31 | 2021-12-31 | Battery charging circuit, DC-DC converter and battery charging method |
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| CN (1) | CN114421764A (en) |
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