CN112491260A - Charging protection circuit and method and switching power supply - Google Patents
Charging protection circuit and method and switching power supply Download PDFInfo
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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
- H02M1/00—Details of apparatus for conversion
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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
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Abstract
The invention discloses a charging protection circuit, a charging protection method and a switching power supply. Wherein, this charge protection circuit includes: the first sampling module is used for detecting the voltage of the bus capacitor; the bus capacitor is arranged between a first line at the input end and a second line at the input end of the switching power supply; the adjustable resistance module is arranged on the second line of the input end and used for keeping the charging current of the bus capacitor stable through the resistance value change of the adjustable resistance module; and the input end of the controller is connected with the first sampling module, and the output end of the controller is connected with the adjustable resistance module and used for adjusting the resistance value of the adjustable resistance module according to the voltage of the bus capacitor. According to the invention, when the voltage of the bus capacitor rises, the reduction of the charging resistor can be correspondingly controlled, so that the charging current is kept stable, and the charging efficiency is ensured.
Description
Technical Field
The invention relates to the technical field of electronic power, in particular to a charging protection circuit, a charging protection method and a switching power supply.
Background
With the call and investment of national 'energy conservation and emission reduction and low-carbon life', the switching power supply is used as an important component in a power supply family, has the characteristics of efficient energy conversion, very low energy loss and capability of saving a large amount of copper materials, steel materials and occupied area, and is rapidly developed in China in recent years. In order to further improve the efficiency of energy conversion and improve the stability of the switching power supply, a suitable charging protection circuit is beneficial to the stability and high conversion efficiency of the switching power supply.
Due to the existence of the bus capacitor of the switching power supply, a charging resistor is often required to be arranged at an input end to reduce surge current, the current charging resistor is generally a fixed value, the charging current is reduced along with the increase of the voltage of the bus capacitor, and the charging efficiency is reduced.
Aiming at the problem that the charging efficiency is reduced because the charging current is reduced along with the increase of the voltage of a bus capacitor in the prior art, an effective solution is not provided at present.
Disclosure of Invention
The embodiment of the invention provides a charging protection circuit, a charging protection method and a switching power supply, and aims to solve the problem that charging efficiency is reduced due to the fact that charging current is reduced along with the increase of bus capacitor voltage in the prior art.
In order to solve the above technical problem, the present invention provides a charging protection circuit, which is applied to a switching power supply, and comprises:
the first sampling module is used for detecting the voltage of the bus capacitor; the bus capacitor is arranged between a first line at the input end and a second line at the input end of the switching power supply;
the adjustable resistance module is arranged on the second line of the input end and used for keeping the charging current of the bus capacitor stable through the resistance value change of the adjustable resistance module;
and the input end of the controller is connected with the first sampling module, and the output end of the controller is connected with the adjustable resistance module and is used for adjusting the resistance value of the adjustable resistance module according to the bus capacitor voltage.
Further, the adjustable resistance module comprises:
the charging circuit comprises at least two charging resistors and at least two first switches, wherein the charging resistors are connected in series, and the first switches are connected in parallel at two ends of the charging resistors in a one-to-one correspondence mode.
Further, the controller includes:
the resistance value determining unit is used for determining the target resistance value of the adjustable resistance module according to the voltage regulation of the bus capacitor;
the number determining unit is used for determining the number of the first switches needing to be conducted according to the target resistance value; the larger the voltage of the bus capacitor is, the more the number of the first switches is switched on;
and the control unit is used for controlling the conduction of the first switches in corresponding quantity.
Further, the adjustable resistance module further comprises:
and the input end of the shift register is connected with the controller, the output end of the shift register is respectively connected with each first switch, and the shift register is used for controlling at least one first switch at a preset position to be conducted according to a control signal output by the controller.
Further, the charge protection circuit further includes:
and the second switch is connected with the adjustable resistance module in series, the first end and the second end of the second switch are connected to the second line of the input end, and the third end of the second switch is connected with the controller.
Further, the circuit further comprises:
the second sampling module is arranged between the input end first line and the input end first line in parallel and used for detecting the voltage of the input end;
the controller is further used for controlling the conduction of a second switch when the voltage of the input end meets a preset condition so as to control the conduction of a second line of the input end; and when the voltage of the input end does not meet the preset condition, controlling the second switch to be switched off so as to control the second line of the input end to be switched off.
The invention also provides a switching power supply, and the charging protection circuit of the switching power supply.
The invention also provides a charging protection method, which applies the charging protection circuit and comprises the following steps:
acquiring bus capacitor voltage of a switching power supply;
and adjusting the resistance value of the adjustable resistance module according to the bus capacitor voltage.
Further, adjusting the resistance of the adjustable resistance module according to the bus capacitor voltage includes:
determining a target resistance value of the adjustable resistance module according to the bus capacitor voltage regulation;
determining the number of first switches needing to be conducted according to the target resistance value; the first switches are connected in parallel to two ends of the charging resistor in the adjustable resistor module in a one-to-one correspondence manner, and the larger the voltage of the bus capacitor is, the more the number of the first switches are switched on;
and controlling the conduction of a corresponding number of first switches.
Further, after acquiring the bus capacitor voltage of the switching power supply, the method further includes:
judging whether the voltage of the bus capacitor reaches the saturation voltage of the bus capacitor;
if yes, controlling all the first switches to be conducted;
if not, the resistance value of the adjustable resistance module is adjusted according to the bus capacitor voltage through triggering.
Further, the method further comprises:
acquiring the voltage of the input end of the switching power supply;
when the voltage of the input end meets a preset condition, controlling the second switch to be conducted;
when the voltage of the input end does not meet a preset condition, controlling a second switch to be switched off; wherein the second switch is connected in series with the adjustable resistance module.
Further, the preset condition is that the first threshold is less than or equal to the input end voltage and less than or equal to the second threshold.
The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the program is executed by a processor to implement the above-mentioned charge protection method.
By applying the technical scheme of the invention, the bus capacitor voltage is detected through the first sampling module; setting an adjustable resistance module; the controller controls and adjusts the resistance value of the adjustable resistance module according to the line capacitance voltage. When the voltage of the bus capacitor rises, the charging resistor can be correspondingly controlled to be reduced, so that the charging current is kept stable, and the charging efficiency is ensured.
Drawings
Fig. 1 is a connection diagram of a charging protection circuit and a circuit of a switching power supply according to an embodiment of the invention;
FIG. 2 is a block diagram of an adjustable resistance module according to an embodiment of the present invention;
FIG. 3 is a block diagram of a controller according to an embodiment of the present invention;
fig. 4 is a block diagram of a charge protection circuit according to another embodiment of the present invention;
FIG. 5 is a flow chart of a charge protection method according to an embodiment of the invention;
fig. 6 is a flowchart of a charge protection method according to another embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, etc. may be used to describe the switches in embodiments of the present invention, the switches should not be limited to these terms. These terms are only used to distinguish between switches disposed in different positions. For example, a first switch may also be referred to as a second switch, and similarly, a second switch may also be referred to as a first switch, without departing from the scope of embodiments of the present invention.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.
Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Example 1
The present embodiment provides a charging protection circuit, which is applied to a switching power supply, and the structure of the switching power supply may be a topology having a dc-to-dc function, such as BUCK, BOOST, flyback, forward, half bridge, full bridge, or a variation of a corresponding topology circuit. Since a flyback topology or a derivative topology thereof is generally used for a wide range of input voltages, the flyback topology is taken as an example in the design, fig. 1 is a connection relationship diagram of a charging protection circuit and a circuit of a switching power supply according to an embodiment of the present invention, as shown in fig. 1, the switching power supply includes: a rectifier 1, an inverter 2 and a transformer 3, wherein the rectifier and the inverter are connected by an input end first line 11 and an input end second line 12;
the charge protection circuit 4 includes: a first sampling module 41, configured to detect a bus capacitor voltage; the bus capacitor C is arranged between the input end first line 11 and the input end second line 12 of the switching power supply; in a specific implementation, the first sampling module 41 may include at least two voltage dividing resistors, an operational amplifier, and an analog-to-digital conversion unit, where the at least two voltage dividing resistors are connected in series between the first line 11 at the input end and the second line 12 at the input end, a sampling end is led out between any two voltage dividing resistors, the sampling end is connected to the operational amplifier, the operational amplifier processes a sampling signal and outputs the signal to an analog-to-digital conversion circuit, performs analog-to-digital conversion on the signal, and then transmits the signal to the controller.
And the adjustable resistance module 42 is arranged on the second line 12 at the input end and used for keeping the charging current of the bus capacitor C stable through the resistance value change of the adjustable resistance module.
And the input end of the controller 43 is connected to the first sampling module 41, and the output end of the controller is connected to the adjustable resistance module 42, so as to adjust the resistance value of the adjustable resistance module 42 according to the bus capacitor voltage.
In the charging protection circuit of the present embodiment, the bus capacitor voltage is detected by the first sampling module 41; setting an adjustable resistance module 42; the controller 43 adjusts the resistance of the adjustable resistance module 42 according to the bus capacitor voltage control. When the voltage of the bus capacitor rises, the charging resistor can be correspondingly controlled to be reduced, so that the charging current is kept stable, and the charging efficiency is ensured.
Example 2
In this embodiment, another charging protection circuit is provided, and fig. 2 is a structural diagram of an adjustable resistor module according to an embodiment of the present invention, and in order to implement adjustment of a charging resistance, as shown in fig. 2, an adjustable resistor module 42 includes: the charging circuit comprises at least two charging resistors R and at least two first switches, wherein the charging resistors R are mutually connected in series, and the first switches K are connected in parallel at two ends of the charging resistors R in a one-to-one correspondence mode. When a certain first switch K is turned on, the charging resistor R connected in parallel with the certain first switch K is short-circuited, and therefore the first switch K cannot be connected into a circuit, as can be seen, the more the number of the first switches K that are turned on is, the more the charging resistor R that is short-circuited is, because the adjustable resistor module 42 is a series circuit, the total resistance value of the adjustable resistor module 42 is the sum of the resistance values of the charging resistors R connected into the circuit, and therefore, the smaller the total resistance value of the adjustable resistor module 42 is, that is, if the resistance value of the adjustable resistor module 42 needs to be controlled to be reduced, the more the first switches K can be turned on to realize the control.
After determining the number of the first switches K that are turned on, it is further determined which switches are turned on and which switches are turned off, and for this purpose, as shown in fig. 2, the adjustable resistance module 42 further includes: the shift register 421 has an input end connected to the controller 43, and an output end connected to each first switch K, and is configured to control at least one first switch K in a preset position to be turned on according to a control signal output by the controller 43.
In this embodiment, the shift register may be a shift register with a model 74LS164, and a certain number of charging resistors R are controlled to be connected to the circuit according to the resistance information output by the controller 43, so as to adjust the resistance value of the adjustable resistance module 42. For example, assuming that there are four charging resistors R in the circuit, four first switches K are correspondingly arranged, and the charging resistors R are sequentially numbered, in the process of adjusting the resistors for the first time, according to the current bus capacitor voltage and the target current, it is determined that three charging resistors R are required to be connected into the circuit, the first switch K at the first position is controlled to be connected, the first switches K at the second position, the third position and the fourth position are controlled to be disconnected, the first charging resistor R is short-circuited, and the remaining three charging resistors R are connected into the circuit, so that the actual charging current is consistent with the target current value; in the process of adjusting the resistance for the second time, the voltage of the bus capacitor further rises, two charging resistors R are determined to be needed to be connected into the circuit according to the voltage value of the capacitor and the target current value, the first switches K at the first position and the second position are controlled to be connected, the first switches K at the third position and the fourth position are controlled to be disconnected, the first charging resistor R and the second charging resistor R are short-circuited, and the rest two charging resistors R are connected into the circuit, so that the actual charging current is consistent with the target current value. During the adjustment, the target current value remains unchanged.
The function of the shift register is to convert serial signals into parallel signals. After the DSA pin and the DSB pin of the shift register chip are connected together, the DSA pin and the DSB pin are connected to the IO port of the controller 43, and the DSA pin and the DSB pin are used for transmitting switching signals of the first switch at the first position, the first switch at the second position, the first switch at the third position, and the first switch at the fourth position. The clock pin CP of the shift register chip is connected to the IO port of the controller 43. The output pins Q0-Q3 are respectively connected with the first switch at the first position, the first switch at the second position, the first switch at the third position and the first switch at the fourth position. Each time the signal at clock pin CP goes from low to high, the data is shifted to the right by one bit. In application, the clear pin MR/CLR may be connected to the controller 43, or may be connected to a high level; all the first switches are in an off stage in an initial state, when the capacitor voltage gradually rises, the charging current gradually falls, in order to ensure the charging speed, a part of the first switches are turned on, the data pin of the controller 43 keeps outputting a turn-on signal and gives a rising edge signal to the clock pin CP, at this time, the first switch at the first position connected with the output pin Q0 is turned on, and the charging current is recovered to a target current value; when the capacitor voltage continues to rise and the charging current drops by a certain value, a rising edge signal is provided to the clock pin CP, and at this time, the data pin still inputs the conducting signal, and on the basis that the first switch at the first position is conducted, the first switch at the second position connected with the output pin Q1 is conducted, and so on.
Similarly, when the charging current is too large, the data pin of the controller 43 may be kept outputting a non-conducting signal, for example: in the initial state, the output pins Q0-Q3 are all turned on, a rising edge signal is provided to the clock pin CP, the output pin Q0 is turned off, and the output pins Q1-Q3 are turned on.
When the number of the first switches needs to be increased, if the current shift register chip has empty signal pins, the increased first switches are directly connected to the empty signal pins, and if the current shift register chip does not have empty signal pins, only a new shift register chip needs to be added. The connection mode is as follows: the DSA pin and the DSB pin of the newly added shift register chip are connected together and then connected to the output highest pin of the original shift register chip (if the highest pin of the original shift register chip is the output pin Q3, the output pin Q3 is connected), the clock pin CP of the newly added shift register chip is connected to the clock pin CP of the original shift register chip, and the clear pin MR/CLR of the newly added shift register chip is connected to the clear pin MR/CLR of the original shift register chip and then connected to the controller 43, or directly connected to a high level.
Fig. 3 is a structural diagram of a controller 43 according to an embodiment of the present invention, and according to the circuit structure in the above embodiment, it can be known that the sum of the bus capacitor voltage and the voltage across the adjustable resistor module 42 is equal to the input terminal voltage of the switching power supply, the input terminal voltage is relatively stable, and as the charging process continues, the voltage across the bus capacitor voltage gradually increases, so that the voltage across the adjustable resistor module 42 gradually decreases, and further the charging current decreases, at this time, in order to ensure that the charging current is stable, the resistance value of the adjustable resistor module 42 needs to be adjusted according to the actual value of the bus capacitor voltage, and therefore, as shown in fig. 3, the controller 43 includes: a resistance value determining unit 431, configured to determine a target resistance value of the adjustable resistance module 42 according to the bus capacitor voltage adjustment; the number determining unit 432 is configured to determine the number of the first switches K that need to be turned on according to the target resistance value of the adjustable resistance module 42; the larger the bus capacitor voltage is, the smaller the voltage of the adjustable resistance module 42 is adjusted to be, and the smaller the resistance value of the adjustable resistance module 42 needs to be, that is, the more the number of the first switches K that are turned on is, the more the charging current can be ensured to be stable. Under the condition that the charging current is kept stable, the corresponding relation between the bus capacitor voltage and the charging resistance value can be obtained through data fitting in experiments or theoretical reasoning in modeling. Finally, the control unit 433 controls the corresponding number of first switches K to be turned on.
Fig. 4 is a structural diagram of a charging protection circuit according to another embodiment of the present invention, in which since the value of the input voltage of the switching power supply is not always kept unchanged, in order to avoid the situation that the input voltage of the switching power supply fluctuates too much and an overvoltage or an undervoltage occurs, as shown in fig. 4, the charging protection circuit further includes: and a second switch Q, which is connected in series with the adjustable resistance module 42, and has a first end and a second end connected to the input end second line 12, and a third end serving as a control end and connected to the controller 43.
As shown in fig. 4, the charge protection circuit further includes: the second sampling module 44 is arranged between the input end first line 11 of the switching power supply and the input end first line 11 in parallel, and is used for detecting the voltage of the input end; the controller 43 is further configured to control the second switch Q to be turned on when the input voltage meets a preset condition, so as to control the input second line 12 to be turned on, and control the second switch Q to be turned off when the input voltage does not meet the preset condition, so as to control the input second line 12 to be turned off, so as to protect the circuit connected to the adjustable resistance module 42 and the rear end of the transformer 3.
Example 3
Fig. 5 is a flowchart of a charging protection method according to an embodiment of the present invention, and as shown in fig. 5, the method includes:
and S101, acquiring the bus capacitor voltage of the switching power supply.
According to the circuit structure in the above embodiment, the sum of the bus capacitor voltage and the voltage at the two ends of the adjustable resistor module is equal to the input end voltage of the switching power supply, the input end voltage is relatively stable, and the voltage at the two ends of the bus capacitor voltage gradually increases along with the continuation of the charging process, so that the voltage at the two ends of the adjustable resistor module gradually decreases, and further the charging current decreases.
And S102, adjusting the resistance value of the adjustable resistance module according to the voltage of the bus capacitor.
Along with the duration of the charging time, the bus capacitor voltage gradually rises, and in order to ensure that the current is stabilized within a certain value or a certain range, and meanwhile, the resistance value of the adjustable resistance module is prevented from being frequently adjusted, the bus capacitor voltage is required to be adjusted at intervals of a certain time.
In the charge protection method of the embodiment, firstly, the bus capacitor voltage of the switching power supply is obtained; and then the resistance value of the adjustable resistance module is controlled and adjusted according to the voltage of the bus capacitor. When the voltage of the bus capacitor rises, the charging resistor can be correspondingly controlled to be reduced, so that the charging current is kept stable, and the charging efficiency is ensured.
Example 4
In this embodiment, another charging protection method is provided, in order to ensure that the charging current is stable, the resistance value of the adjustable resistance module needs to be adjusted according to the actual value of the voltage of the bus capacitor, where the step S102 specifically includes: determining a target resistance value of the adjustable resistance module according to the bus capacitor voltage regulation; determining the number of first switches to be conducted according to the target resistance value of the adjustable resistance module; the first switches are connected in parallel at two ends of the charging resistor in the adjustable resistor module in a one-to-one correspondence manner, and the larger the voltage of the bus capacitor is, the more the number of the first switches are conducted; and controlling the conduction of a corresponding number of first switches.
After the bus capacitor is fully charged, if a charging resistor is connected into the circuit, the electric energy is consumed, and the energy is wasted, so that after the bus capacitor voltage of the switching power supply is obtained, the method further comprises the following steps:
judging whether the voltage of the bus capacitor reaches the saturation voltage of the bus capacitor; if yes, indicating that the battery is fully charged, controlling all the first switches to be conducted at the moment, enabling all the charging resistors to be in short circuit, and avoiding the charging resistors from consuming electric energy; if not, the resistance value of the adjustable resistance module is adjusted according to the voltage of the bus capacitor.
Because the value of the input voltage of the switching power supply is not always kept unchanged, in order to avoid the situation that the input voltage of the switching power supply fluctuates too much and an overvoltage or an undervoltage occurs, the charging protection method further comprises the following steps:
acquiring the voltage of an input end of a switching power supply; when the voltage of the input end meets a preset condition, controlling the second switch to be conducted; when the voltage of the input end does not meet the preset condition, controlling the second switch to be switched off; the second switch is connected in series with the adjustable resistance module; the preset condition is that the first threshold value is less than or equal to the input end voltage and less than or equal to the second threshold value. Through the steps, the situation that the circuit is over-voltage or under-voltage is avoided, and elements in the circuit are protected.
Example 5
The embodiment provides a charging protection circuit, which is applied to a switching power supply, and the structure of the switching power supply can be a topology with a direct current-to-direct current function such as BUCK, BOOST, flyback, forward, half bridge, full bridge, or the like, or a deformation of a corresponding topology circuit. Since a wide range of input voltages generally uses a flyback topology or a derivative topology thereof, the present design takes the flyback topology as an example, and in the present embodiment, the circuit structure of the switching power supply is as shown in fig. 1 mentioned above, and includes: rectifier, inverter and transformer, wherein, connect through input first line 11 and input second line 12 between rectifier and the inverter, the bus capacitance sets up between input first line 11 and input second line 12, and the adjustable resistance module sets up on input second line 12, and the charge protection circuit of this embodiment is as shown in fig. 2 that above-mentioned includes: a first sampling module 41, an adjustable resistance module 42, and a controller 43. The first sampling module 41 may include at least two voltage dividing resistors, an operational amplifier, and an analog-to-digital conversion unit (not shown in the figure), wherein the at least two voltage dividing resistors are connected in series between the first line 11 at the input end and the second line 12 at the input end, a sampling end is led out between any two voltage dividing resistors, the operational amplifier is connected to the operational amplifier, the operational amplifier processes a sampling signal and outputs the signal to an analog-to-digital conversion circuit, performs analog-to-digital conversion on the signal, and then transmits the signal to the controller 43. The controller 43 controls the resistance value of the adjustable resistance module according to the bus capacitor voltage detected by the first sampling module 41. In this embodiment, the controller 43 may be a digital signal processing chip DSP, STM32, or other type of controller 43.
The structure diagram of the adjustable resistor module of the present embodiment, as shown in fig. 3 mentioned above, includes: the shift register comprises at least two charging resistors R, at least two first switches K and a shift register 421, wherein the charging resistors R are mutually connected in series, and the first switches K are connected in parallel at two ends of the charging resistors R in a one-to-one correspondence manner; when the voltage of the bus capacitor rises, the controller 43 controls the number of the turned-on first switches K to increase, and then controls the resistance value of the adjustable resistance module to decrease.
In this embodiment, the shift register may be a shift register with a model 74LS164, and a certain number of charging resistors R are controlled to be connected to the circuit according to the resistance information output by the controller 43, so as to adjust the resistance value of the adjustable resistance module 42. For example, assuming that there are four charging resistors R in the circuit, four first switches K are correspondingly arranged, and the charging resistors R are sequentially numbered, in the process of adjusting the resistors for the first time, according to the current capacitor voltage value and the target current value, it is determined that three charging resistors R are required to be connected into the circuit, the first switch K at the first position is controlled to be connected, the first switches K at the second position, the third position and the fourth position are controlled to be disconnected, the first charging resistor R is short-circuited, and the remaining three charging resistors R are connected into the circuit, so that the actual charging current is consistent with the target current value; in the process of adjusting the resistor for the second time, the capacitor voltage further rises, two charging resistors R are determined to be needed to be connected into the circuit according to the capacitor voltage value and the target current value, the first switches K at the first position and the second position are controlled to be connected, the first switches K at the third position and the fourth position are controlled to be disconnected, the first charging resistor R and the second charging resistor R are short-circuited, and the rest two charging resistors R are connected into the circuit, so that the actual charging current is consistent with the target current value. During the adjustment, the target current value remains unchanged.
The charging protection circuit further includes a second sampling module 44, the second sampling module 44 has the same structure as the first sampling module 41, and also includes at least two voltage dividing resistors, an operational amplifier and an analog-to-digital conversion unit, the controller 43 is further configured to control whether the adjustable resistor module is turned on according to the detected input terminal voltage of the second sampling module 44, where the input terminal voltage may be a direct current voltage or an alternating current voltage. Specifically, a second switch Q is disposed between the adjustable resistance module and the controller 43, the second switch Q may be a mos transistor, a gate of the mos transistor is connected to the controller 43, a source and a drain of the mos transistor are connected to the second line 12, when the input voltage is less than a first threshold, or the input voltage is greater than a second threshold, the controller 43 controls the mos transistor to turn off, and when the first threshold is less than or equal to the input voltage and less than or equal to the second threshold, the controller 43 controls the mos transistor to turn on, wherein the first threshold is an under-voltage critical value, for example, 180V, and the second threshold is an over-voltage critical value, for example, 230V. The protection of the back-end circuit is realized, and the conditions of overvoltage and undervoltage are prevented.
Fig. 6 is a flowchart of a charging protection method according to another embodiment of the present invention, and as shown in fig. 6, the method includes:
and S1, controlling the second switch to keep off, and detecting the voltage of the input end.
In this embodiment, the input end voltage may be a direct current voltage or an alternating current voltage, and in specific implementation, the input end voltage is collected and transmitted to the controller by accessing the second sampling module between the first line of the input end and the second line of the input end.
S2, judging whether the voltage of the input end is in a preset range; if so, step S3 is executed, if not, the process returns to step S1.
The preset range is [ a first threshold value, a second threshold value ], after the input voltage value is obtained through the second sampling module, whether the input voltage value falls into the preset range is judged, and if the input voltage value does not fall into the preset range, two conditions exist: the voltage at the input end is less than a first threshold value, indicating that the circuit is under-voltage; if the voltage of the input end is larger than a second threshold value, the circuit is over-voltage, under the two conditions, the controller controls the second switch to be switched off, further controls the adjustable resistance module and the subsequent load circuit of the adjustable resistance module to be switched off, and controls the adjustable resistance module and the subsequent load circuit of the adjustable resistance module to be switched off if the voltage of the input end falls into a preset range.
And S3, adjusting the number of the first switches according to the voltage of the bus capacitor.
To increase the charging speed, the time for system preparation is reduced. The bus capacitor is charged by adopting the maximum bearable current value of the front and rear stages of the bus capacitor. As the voltage across the bus capacitor increases during charging, the charging current decreases. In order to increase the charging speed, the charging current should be as large as possible. Therefore, after the voltage value at the two ends of the bus capacitor rises, the charging resistance value is reduced, the charging current is kept stable, under the condition that the charging current is kept stable, the corresponding relation between the bus capacitor voltage and the charging resistor can be obtained by data fitting through experiments or reasoning by using other modeling theories, the required charging resistance value can be calculated according to the bus capacitor voltage and based on the corresponding relation between the bus capacitor voltage and the charging resistance value, namely the target resistance value of the adjustable resistance module, determining the number of the conducting charging resistors according to the target resistance value of the adjustable resistance module, subtracting the number of the conducting charging resistors from the total number of the charging resistors, the number of the short-circuited charging resistors, that is, the number of the first switches to be turned on can be determined, and the corresponding number of the first switches to be turned on is controlled according to the number of the first switches to be turned on.
And S4, controlling the second switch to be conducted to charge the bus capacitor.
S5, judging whether the bus capacitor is fully charged, if yes, executing the step S6; if not, return is made to step S1. If the detected voltage of the bus capacitor reaches the saturation voltage of the bus capacitor, the bus capacitor is fully charged, and otherwise, the bus capacitor is not fully charged.
And S6, controlling all the first switches to be conducted and short-circuiting all the charging resistors.
When the bus capacitor is fully charged, all the first switches are conducted to short out all the charging resistors, so that the charging resistors can not continuously consume energy in the circuit.
By adopting the charging protection circuit of the embodiment, the charging current can be kept stable according to the charging resistance value of the capacitor voltage, and the charging speed is further ensured. The charging efficiency of the switching power supply is improved, so that the switching power supply can be put into use as soon as possible, and the charging quality is ensured; after the charging resistor is fully charged, the charging resistance value is adjusted to be zero, so that the charging resistor is prevented from consuming energy in a circuit, and the waste of energy is avoided; when overvoltage or undervoltage occurs, the safety of the input side and the output side of the voltage input protection circuit can be cut off. The safety and stability are improved.
Example 6
The embodiment provides a switching power supply, which includes the charging protection circuit in the above embodiments, and is used to keep the charging current stable, ensure the charging efficiency, and further enable the switching power supply to be put into formal use as soon as possible.
Example 7
The present embodiment provides a computer-readable storage medium on which a computer program is stored, which when executed by a processor implements the charge protection method of the above-described embodiment.
The above-described circuit embodiments are only illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (13)
1. A charging protection circuit is applied to a switching power supply, and is characterized by comprising:
the first sampling module is used for detecting the voltage of the bus capacitor; the bus capacitor is arranged between a first line at the input end and a second line at the input end of the switching power supply;
the adjustable resistance module is arranged on the second line of the input end and used for keeping the charging current of the bus capacitor stable through the resistance value change of the adjustable resistance module;
and the input end of the controller is connected with the first sampling module, and the output end of the controller is connected with the adjustable resistance module and is used for adjusting the resistance value of the adjustable resistance module according to the bus capacitor voltage.
2. The circuit of claim 1, wherein the adjustable resistance module comprises:
the charging circuit comprises at least two charging resistors and at least two first switches, wherein the charging resistors are connected in series, and the first switches are connected in parallel at two ends of the charging resistors in a one-to-one correspondence mode.
3. The circuit of claim 2, wherein the controller comprises:
the resistance value determining unit is used for determining the target resistance value of the adjustable resistance module according to the voltage regulation of the bus capacitor;
the number determining unit is used for determining the number of the first switches needing to be conducted according to the target resistance value; the larger the voltage of the bus capacitor is, the more the number of the first switches is switched on;
and the control unit is used for controlling the conduction of the first switches in corresponding quantity.
4. The circuit of claim 2, wherein the adjustable resistance module further comprises:
and the input end of the shift register is connected with the controller, the output end of the shift register is respectively connected with each first switch, and the shift register is used for controlling at least one first switch at a preset position to be conducted according to a control signal output by the controller.
5. The circuit of claim 1, wherein the charge protection circuit further comprises:
and the second switch is connected with the adjustable resistance module in series, the first end and the second end of the second switch are connected to the second line of the input end, and the third end of the second switch is connected with the controller.
6. The circuit of claim 5, further comprising:
the second sampling module is arranged between the input end first line and the input end first line in parallel and used for detecting the voltage of the input end;
the controller is further used for controlling the conduction of a second switch when the voltage of the input end meets a preset condition so as to control the conduction of a second line of the input end; and when the voltage of the input end does not meet the preset condition, controlling the second switch to be switched off so as to control the second line of the input end to be switched off.
7. A switching power supply characterized by comprising the charge protection circuit according to any one of claims 1 to 6.
8. A charge protection method applied to the charge protection circuit according to any one of claims 1 to 6, the method comprising:
acquiring bus capacitor voltage of a switching power supply;
and adjusting the resistance value of the adjustable resistance module according to the bus capacitor voltage.
9. The method of claim 8, wherein adjusting the resistance of the adjustable resistance module based on the bus capacitor voltage comprises:
determining a target resistance value of the adjustable resistance module according to the bus capacitor voltage regulation;
determining the number of first switches needing to be conducted according to the target resistance value; the first switches are connected in parallel to two ends of the charging resistor in the adjustable resistor module in a one-to-one correspondence manner, and the larger the voltage of the bus capacitor is, the more the number of the first switches are switched on;
and controlling the conduction of a corresponding number of first switches.
10. The method of claim 8, wherein after obtaining the bus capacitor voltage of the switching power supply, the method further comprises:
judging whether the voltage of the bus capacitor reaches the saturation voltage of the bus capacitor;
if yes, controlling all the first switches to be conducted;
if not, the resistance value of the adjustable resistance module is adjusted according to the bus capacitor voltage through triggering.
11. The method of claim 8, further comprising:
acquiring the voltage of the input end of the switching power supply;
when the voltage of the input end meets a preset condition, controlling the second switch to be conducted;
when the voltage of the input end does not meet a preset condition, controlling a second switch to be switched off; wherein the second switch is connected in series with the adjustable resistance module.
12. The method of claim 11, wherein the predetermined condition is that the first threshold value is less than or equal to the input terminal voltage is less than or equal to the second threshold value.
13. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, carries out the method according to any one of claims 8 to 12.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011340171.0A CN112491260A (en) | 2020-11-25 | 2020-11-25 | Charging protection circuit and method and switching power supply |
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| CN202011340171.0A CN112491260A (en) | 2020-11-25 | 2020-11-25 | Charging protection circuit and method and switching power supply |
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Application publication date: 20210312 |