CN113098236A - Switching power supply and output voltage compensation circuit thereof - Google Patents
Switching power supply and output voltage compensation circuit thereof Download PDFInfo
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- CN113098236A CN113098236A CN202110410089.9A CN202110410089A CN113098236A CN 113098236 A CN113098236 A CN 113098236A CN 202110410089 A CN202110410089 A CN 202110410089A CN 113098236 A CN113098236 A CN 113098236A
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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
- 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
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
- H02J7/04—Regulation of charging current or voltage
- H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
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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
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
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Abstract
The application relates to a switching power supply and output voltage compensation circuit thereof, include: the voltage division module comprises a voltage division branch circuit formed by connecting a plurality of resistors in series and is used for dividing the output voltage of the switching power supply; the output voltage adjusting module is used for controlling and increasing an electric signal at an output voltage feedback end when the voltage on a first set voltage dividing branch of the voltage dividing module is greater than a preset reference voltage, and feeding the electric signal back to the switching power supply control chip to actively adjust and reduce the output voltage; and the linear compensation module is used for generating a pull-down current applied to a second set voltage division branch of the voltage division module according to the CS signal so as to generate an output line compensation voltage which linearly changes along with the change of the CS signal at an output voltage feedback end of the switching power supply. Due to the fact that the impedance of a connecting cable exists between the voltage output end of the switching power supply and the load in the prior art, when the load current changes, loss on the cable impedance is different, and the switching power supply output voltage is unstable when the load is different.
Description
Technical Field
The application relates to a switching power supply and an output voltage compensation circuit thereof, and belongs to the technical field of switching power supplies.
Background
In recent years, the application of lithium battery packs is more and more extensive, become the power supply of portable equipment such as mobile, handheld, etc., secondary side feedback type flyback switching power supply is used in the field of charging in a large number, through power chip, benchmark chip and specific peripheral circuit, obtain mains voltage output at the secondary side of transformer, sample output voltage and electric current simultaneously, pass the signal of telecommunication that changes back for the switching power supply chip of transformer primary side through the opto-coupler, power chip handles the signal of telecommunication received, thereby change the PWM switching signal of power, and finally obtain stable voltage output.
However, due to the existence of the load cable, especially when the load cable is long and the impedance of the cable is not negligible, the actual charging voltage under different load conditions may be different. Under the condition of light load, the output current is small, so that the cable impedance loss generated by the cable impedance after passing through the load cable is small; under the condition of heavy load, the output current is large, so that the loss generated after the output current passes through a load cable is large, and the actual charging voltage cannot be truly stable. In order to maintain accurate control of the output voltage, compensation needs to be performed on the output voltage under different loads, so that the actual charging voltage can be kept stable under different loads.
The most common compensation method is to draw a cable compensation current related to the output current at the sampling feedback pin. The compensation voltage is superimposed by generating an additional compensation voltage on the sampling feedback pin to affect the value of the output voltage. The method has certain disadvantages that after the circuit design is finished, the compensation parameters are all constant values, but the resistance values of the load cables are different in different application occasions, so that the compensation voltage cannot adapt to different application occasions, and the application environment is limited.
Disclosure of Invention
The application provides a switching power supply and output voltage compensating circuit thereof can solve the problem that the cable connected between the voltage output end of the switching power supply and the load is unstable under different loads and different impedances because of different output impedances in different occasions in the prior art.
The application provides the following technical scheme:
in a first aspect, an output voltage compensation circuit of a switching power supply is provided, where the output voltage compensation circuit is connected between a CS signal detection terminal of the switching power supply and an output voltage feedback terminal of the switching power supply, and the output voltage compensation circuit includes:
the voltage division module comprises a plurality of voltage division branches connected in series and is used for dividing the output voltage of the switching power supply;
the output voltage adjusting module is used for controlling and increasing a current signal of an output voltage feedback end when the voltage on a first set voltage dividing branch of the voltage dividing module is greater than a preset reference voltage, and feeding the current signal back to the switching power supply control chip to actively adjust and reduce the output voltage;
and the linear compensation module is used for generating a pull-down current applied to a second set voltage division branch of the voltage division module according to the CS signal so as to generate an output line compensation voltage which linearly changes along with the change of the CS signal at an output voltage feedback end of the switching power supply.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the voltage divider circuit includes a resistor R2, a resistor Rx, and a resistor R3, one end of the resistor R2 is connected to the voltage output terminal of the switching power supply, and the other end of the resistor R2 is grounded through the resistor Rx and the resistor R3 which are sequentially connected in series.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the output voltage adjustment module includes a second operational amplifier and a second adjustment tube, a non-inverting input terminal of the second operational amplifier is connected to a series voltage dividing point of a resistor R3 and a resistor Rx, an inverting input terminal of the second operational amplifier is connected to a preset reference voltage, an output terminal of the second operational amplifier is connected to a control terminal of the second adjustment tube, a high potential terminal of the second adjustment tube is connected to an output voltage feedback terminal, and a low potential terminal of the second adjustment tube is grounded.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the linearity compensation module includes a first operational amplifier, a first regulating tube and a resistor R4, a non-inverting input terminal of the first operational amplifier is connected to the CS voltage signal, an inverting input terminal of the first operational amplifier is connected to the first terminal of the resistor R4, an output terminal of the first operational amplifier is connected to the control terminal of the first regulating tube, a high potential terminal of the first regulating tube is connected to a series voltage dividing point of the resistor R2 and the resistor Rx, and a low potential terminal of the first regulating tube is connected to the first terminal of the resistor R4.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the linear compensation circuit is further connected to an external resistor R5, one end of the resistor R5 is connected to the second end of the resistor R4, the other end of the resistor R5 is grounded, and the resistance of the resistor R5 is selected according to different load cable resistances.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the linear compensation circuit further includes an N-fold amplifier, and the CS voltage signal passes through the N-fold amplifier and then is connected to the non-inverting input terminal of the first operational amplifier.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the first adjusting transistor or the second adjusting transistor is an MOS transistor, and a gate, a drain, and a source of the MOS transistor are a control terminal, a high potential terminal, and a low potential terminal of the switching transistor, respectively.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the first adjusting tube or the second adjusting tube is a triode, and a base, a collector, and an emitter of the triode are a control end, a high potential end, and a low potential end of the first adjusting tube or the second adjusting tube, respectively.
Further, according to the output voltage compensation circuit of the first aspect of the embodiment of the present application, the resistor Rx is an adjustable resistor, and the adjustment step of the adjustable resistor is in an equal proportion corresponding relationship with the number of nodes of the load lithium battery pack, so that when the number of nodes of the load lithium battery pack is changed, the corresponding voltage output is realized by adjusting the size of the resistor Rx.
In a second aspect, an output voltage compensation circuit is provided, where the output voltage compensation circuit is connected between a CS signal output end of the switching power supply and an output voltage feedback end of the switching power supply, and the output voltage compensation circuit is the output voltage compensation circuit according to any one of the first aspect.
The beneficial effect of this application lies in: the embodiment of the application controls the compensation value of the output voltage to linearly change along with the change of the CS signal through monitoring the CS signal, so that stable output voltage can be obtained under different loads and cable resistances, and the lithium battery pack is stably charged.
In addition, this application embodiment is provided with external resistor R5, and external resistor R5's resistance adjusts according to the cable resistance of difference, conveniently is applied to the occasion of different cable resistances, and application scope is wider.
The foregoing description is only an overview of the technical solutions of the present application, and in order to make the technical solutions of the present application more clear and clear, and to implement the technical solutions according to the content of the description, the following detailed description is made with reference to the preferred embodiments of the present application and the accompanying drawings.
Drawings
Fig. 1 is a block diagram of a circuit structure of a flyback switching power supply for charging a lithium battery pack according to an embodiment of the present disclosure;
fig. 2 is a schematic circuit diagram of an output voltage compensation circuit according to an embodiment of the present application.
Detailed Description
The following detailed description of embodiments of the present application will be described in conjunction with the accompanying drawings and examples. The following examples are intended to illustrate the present application but are not intended to limit the scope of the present application.
A switching power supply, namely a switching stabilized voltage supply, is a novel stabilized voltage supply circuit relative to a linear stabilized voltage supply, and stabilizes output voltage by monitoring the output voltage in real time and dynamically controlling the on-off time ratio of a switching tube in a switching power supply circuit.
The flyback switching power supply is a switching power supply which uses a flyback high-frequency transformer to isolate an input-output loop and is a buck-boost circuit. The primary side of the high-frequency transformer is used as input, the secondary side of the high-frequency transformer is used as output, and the power switch tube is connected to the primary side of the high-frequency transformer.
Fig. 1 is a block diagram of a circuit structure of a flyback switching power supply for charging a lithium battery pack according to an embodiment of the present application, as shown in fig. 1, a charging port of the lithium battery pack is connected to an output end of the flyback switching power supply, the lithium battery pack is charged by the flyback switching power supply, in a working process of the flyback switching power supply, by sampling a voltage and a current at an output end of the flyback switching power supply, an electrical signal changed at the output end of the switching power supply is transmitted back to a switching power supply chip at a primary side of a transformer through an output voltage feedback port FBO, the switching power supply chip processes the received electrical signal, and by adjusting a PWM switching signal of the switching power supply, a stable output voltage is finally obtained.
Because the output end of the flyback switching power supply is connected with the output end of the lithium battery pack through the cable, the cable resistor RLine exists, and voltage drop can be generated on the cable in the charging process of the lithium battery pack, so that the output voltage V of the flyback switching power supply is obtainedOUTWhen the charging voltage is fixed, the voltage value of the charged end can change significantly due to the voltage drop on the cable, so that the actual charging voltage of the lithium battery pack cannot be truly stable, and therefore, the voltage on the cable needs to be compensated.
As shown in fig. 1, an output voltage compensation circuit 1 is provided in the embodiment of the present application, and the output voltage compensation circuit 1 of the present embodiment is connected between a voltage output terminal of a load lithium battery pack and a voltage output terminal of a switching power supply. The output voltage compensation circuit 1 ensures that the charging voltage of the lithium battery pack is maintained in a constant range by detecting the charging current (CS signal) and controlling the linear change of the output line compensation voltage according to the change of the charging current.
Alternatively, the voltage compensation circuit 1 of the present embodiment includes a linear compensation circuit, a voltage division circuit, and an output voltage adjustment circuit.
In particular, the voltage dividing circuit is moreA voltage dividing branch circuit connected in series for outputting voltage V to the switching power supplyOUTPartial pressure is carried out.
Output voltage regulating circuit for output voltage V of switching power supplyOUTWhen the divided voltage on the first set voltage dividing branch of the voltage dividing module is greater than the preset reference voltage, the current signal fed back by the FBO (feedback node) of the pull-down output voltage is increased and fed back to the switching power supply control chip to actively adjust and reduce the output voltage.
The linear compensation circuit is used for generating output line compensation voltage which changes linearly along with the change of the charging current at the output voltage feedback end FBO according to the charging current of the lithium battery pack.
Fig. 2 shows a schematic circuit diagram of an output line compensation circuit according to an embodiment of the present application, and for convenience of explanation, only the portion related to the present embodiment is shown in fig. 2, as shown in fig. 2:
optionally, the voltage dividing circuit includes a resistor R2, a resistor Rx, and a resistor R3 connected in series in this order.
One end of the resistor R2 is connected with the output end of the flyback switching power supply, and the other end of the resistor R2 is grounded through a resistor Rx and a resistor R3 which are sequentially connected in series. Wherein R3 is the first set voltage dividing branch, R2 is the second set voltage dividing branch
In a preferred embodiment, Rx is an adjustable resistor, and the adjustment step of the resistor Rx is in an equal proportion corresponding relationship with the number of nodes of the load lithium battery pack, so that the output compensation effects of the load lithium battery packs with different numbers of nodes are consistent by adjusting the resistance of Rx, and after the number of nodes of the load lithium battery pack is determined, the resistance of Rx is correspondingly determined.
Optionally, the output voltage regulating circuit includes a second operational amplifier AMP2 and a second regulating tube Q2.
The non-inverting input terminal of the second operational amplifier AMP2 is connected to the resistor R3And a resistor RXThe inverting input end of the second operational amplifier AMP2 is connected to a preset reference voltage VREFThe output end of the second operational amplifier AMP2 is connected with the control end of a second adjusting tube Q2, and the high potential end of the second adjusting tube Q2 is connected with the output voltage feedback end of the switching power supplyFBO (the electric signal output by the optical coupler OC is the output voltage feedback signal), and the low potential end of the second adjusting tube Q2 is grounded.
In this embodiment, the second adjusting transistor Q2 is an enhancement NMOS transistor, the source of the second adjusting transistor Q2 is grounded, the drain of the Q2 is connected to the optical coupler, the gate of the Q2 is connected to the output terminal of the second operational amplifier AMP2, and when the second operational amplifier AMP2 outputs a high level, the second adjusting transistor Q2 is turned on.
The second adjusting tube Q2 may also be a triode, and the base, collector and emitter of the triode correspond to the control terminal, high potential terminal and low potential terminal of the second adjusting tube, respectively. In actual operation, a MOS transistor or a triode may be selected according to needs, and this embodiment is not limited herein.
During the working process of the flyback switching power supply, when the output voltage V isOUTOn the large side, the output voltage regulating circuit detects VOUTThe voltage division on the resistor R3 is greater than VREFDuring the process, the output end of the second operational amplifier AMP2 controls the second adjusting tube Q2 to increase the pull-down current, the optocoupler OC feeds back the pull-down electric signal to the switching power supply chip, the switching power supply chip adjusts the PWM switching signal of the switching power supply according to the received electric signal, the on-off time of the power supply switching tube is controlled, and the output voltage V is reducedOUT。
Optionally, the linearity compensation circuit includes a first operational amplifier AMP1, a first adjusting tube Q1, and a resistor R4.
The high potential end of the first adjusting tube Q1 is connected to the series voltage division point of the resistor R2 and the resistor RX, the low potential end of the first adjusting tube Q1 is connected to the first end of the resistor R4, the control end of the first adjusting tube Q1 is connected to the output end of the first operational amplifier AMP1, the non-inverting input end of the first operational amplifier AMP1 is connected to the CS voltage signal of the switching power supply, and the inverting input end of the first operational amplifier AMP1 is connected to the series point of the resistor R4 and the low potential end of the first adjusting tube Q1.
The first tuning transistor Q1 of the present embodiment may be an enhancement NMOS transistor. The source of the first adjusting transistor Q1 is connected to the first end of the resistor R4, the drain of the transistor Q1 is connected to the series point of the resistor R2 and RX, and the gate of the transistor Q1 is connected to the output terminal of the first operational amplifier AMP 1.
The first adjusting tube Q1 may also be a triode, and the base, collector and emitter of the triode correspond to the control terminal, high potential terminal and low potential terminal of the first adjusting tube, respectively. In actual operation, an NMOS transistor or a triode may be selected according to needs, and this embodiment is not limited herein.
As a further optimization, the linearity compensation circuit of the embodiment of the present application is further provided with an N-fold amplifier. The N-fold amplifier is used for receiving the CS voltage VCS(in the present embodiment, the charging current is detected by detecting the CS voltage, which is the voltage across the resistor R1) and amplified by a factor of N, and then the amplified charging current is coupled to the non-inverting input terminal of the first operational amplifier AMP 1. The resistance value of the resistor R1 is small, so that the corresponding CS voltage VCSIs also small, and the CS voltage V is multiplied by N times by the amplifierCSAfter N times of amplification is carried out, the influence of external factors on the CS voltage signal can be reduced, and subsequent processing is facilitated.
Further optionally, in order to realize adjustment of the output line compensation voltage in different application occasions, an external resistor R5 is further provided in this embodiment, one end of the external resistor R5 is connected to the second end of the resistor R4, and the other end of the external resistor R5 is grounded.
The resistor R5 may be sized according to the line resistance R generated by cables of different lengthsLineTo select, namely:
firstly, estimating the line resistance value R from the load lithium battery pack to the output end of the switching power supply under different application occasionsLineBased on the estimated line resistance value RLineThe corresponding line compensation voltage value is estimated and then the applicable resistance value of the resistor R5 is determined based on the line compensation voltage value.
In this embodiment, a resistance value selection table is created according to the resistors R5 with different resistance values applicable to different cable resistors RLine, so that in practical application, the resistors R5 with different resistance values can be selected from the resistance value selection table according to different application occasions and detected line resistances, so as to adapt to the adjustment of line compensation voltages under different cable resistors RLine.
When the output end of the flyback switching power supply is connected to a cable of the load lithium battery pack to generate certain impedance, the external resistor R5 corresponding to the resistance value is selected from the resistance value selection table through detection of the cable resistor RLine according to the detected size of the cable resistor RLine, and therefore the maximum line compensation voltage of the flyback switching power supply is determined. By determining the maximum line compensation voltage, the application range of the switching power supply can be known.
The first operational amplifier AMP1 of the line complement circuit detects N times of the CS voltage NxVCSThen the voltage value at R4 is also N × VCSTherefore, a pull-down current is generated in the resistor R4, and flows through the resistor R2, the first adjusting transistor Q1, the resistor R4, and the resistor R5 to ground. In the embodiment, for realizing the consistency of the output line compensation effect of the lithium battery packs with different numbers of nodes, the pull-down current generated by the line compensation circuit is added to the resistor R2 of the voltage division circuit, and when the load lithium battery packs with different numbers of nodes are charged, the corresponding voltage output can be obtained by adjusting the size of the resistor Rx.
The pull-down current generated by the line compensation circuit is regulated by a first regulating tube Q1, specifically:
when the first regulating transistor Q1 generates a pull-down current, the current flowing through the voltage dividing circuit is divided by the branch circuit where the resistor R4 and the resistor R5 are located, and thus the output voltage V of the switching power supply is obtainedOUTThe divided voltage on the resistor R3 will be reduced, so that the output voltage of the second operational amplifier AMP2 is reduced, the current flowing through the second adjusting tube Q2 is reduced, the pull-down current to the output terminal of the optical coupler OC through the second adjusting tube Q2 is reduced accordingly, and the output voltage of the power supply fed back by the optical coupler OC is correspondingly increased, and the increased voltage is the output line compensation voltage Δ V. The calculation formula of the output line compensation voltage delta V is as follows:
the amplification factor N can be set according to specific conditions, and is used for subsequent processing of the circuit, so that the design is more convenient, for example, the amplification factor N can be 20 times.
The line compensation voltage delta V is added to the output voltage V of the switching power supply as a compensation valueOUTIn (1),and the PWM switching signal of the switching power supply is adjusted by the switching power supply control chip according to the changed output voltage, and finally, stable output voltage is obtained, so that the lithium battery pack is charged stably. According to the above formula for calculating the line compensation voltage, when R5 is equal to 0, only the internal resistor R4 and the pin COMP of the compensation pin are grounded, the line compensation voltage at this time is the maximum line compensation voltage, and the maximum line compensation voltage follows VCSThe voltage decreases linearly.
The maximum output line compensation voltage can be adjusted randomly along with the change of the resistance value of R5, when a COMP pin of a compensation pin is suspended, a line compensation circuit does not work, and the switching power supply does not have an output line compensation function.
Meanwhile, the resistance value of the resistor R4 can be selected as required to determine the maximum output line compensation voltage, the smaller the R4 is, the larger the output line compensation voltage is, and the resistance value of the resistor R4 is matched with the resistance value of the resistor R2 to ensure the accuracy of the charging voltage.
In summary, the embodiment of the present application controls the linear variation of the line compensation voltage value along with the variation of the charging current by monitoring the charging current (i.e., the CS signal) of the lithium battery pack, so as to stably charge the lithium battery pack. And through adjusting external resistance R5's resistance, can adjust out the arbitrary output line compensation voltage that is less than the maximum output line compensation voltage, conveniently be applied to the occasion of different cable resistance, application scope is wider.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An output voltage compensation circuit of a switching power supply, the output voltage compensation circuit is connected between a CS signal detection end of the switching power supply and an output voltage feedback end of the switching power supply, and is characterized in that: the output voltage compensation circuit includes:
the voltage division module comprises a plurality of voltage division branches connected in series and is used for dividing the output voltage of the switching power supply;
the output voltage adjusting module is used for controlling and increasing a current signal of an output voltage feedback end when the voltage on a first set voltage dividing branch of the voltage dividing module is greater than a preset reference voltage, and feeding the current signal back to the switching power supply control chip to actively adjust and reduce the output voltage;
and the linear compensation module is used for generating a pull-down current applied to a second set voltage division branch of the voltage division module according to the CS signal so as to generate an output line compensation voltage which linearly changes along with the change of the CS signal at an output voltage feedback end of the switching power supply.
2. The output voltage compensation circuit of claim 1, wherein the voltage divider circuit comprises a resistor R2, a resistor Rx, and a resistor R3, one end of the resistor R2 is connected to the voltage output terminal of the switching power supply, and the other end of the resistor R2 is connected to ground through the resistor Rx and the resistor R3 which are connected in series in sequence.
3. The output voltage compensation circuit of claim 2, wherein the output voltage regulation module comprises a second operational amplifier and a second regulating transistor, a non-inverting input terminal of the second operational amplifier is connected to a voltage dividing point of a resistor R3 and a resistor Rx in series, an inverting input terminal of the second operational amplifier is connected to a predetermined reference voltage, an output terminal of the second operational amplifier is connected to a control terminal of the second regulating transistor, a high potential terminal of the second regulating transistor is connected to an output voltage feedback terminal, and a low potential terminal of the second regulating transistor is grounded.
4. The output voltage compensation circuit of claim 3, wherein the linearity compensation module comprises a first operational amplifier, a first regulating transistor and a resistor R4, wherein a non-inverting input terminal of the first operational amplifier is connected to the CS voltage signal, an inverting input terminal of the first operational amplifier is connected to a first terminal of a resistor R4, an output terminal of the first operational amplifier is connected to a control terminal of the first regulating transistor, a high potential terminal of the first regulating transistor is connected to a series voltage dividing point of the resistor R2 and the resistor Rx, and a low potential terminal of the first regulating transistor is connected to a first terminal of a resistor R4.
5. The output voltage compensation circuit of claim 4, wherein an external resistor R5 is further connected to the linear compensation circuit, one end of the resistor R5 is connected to the second end of the resistor R4, the other end of the resistor R5 is grounded, and the resistance of the resistor R5 is selected according to different load cable resistances.
6. The output voltage compensation circuit of claim 4 or 5, wherein the linearity compensation circuit further comprises an N-fold amplifier, and the CS voltage signal passes through the N-fold amplifier and then is connected to a non-inverting input terminal of the first operational amplifier.
7. The output voltage compensation circuit according to claim 4, wherein the first or second adjusting transistor is an MOS transistor, and the gate, the drain and the source of the MOS transistor are the control terminal, the high potential terminal and the low potential terminal of the switching transistor, respectively.
8. The output voltage compensation circuit of claim 4, wherein the first or second adjusting transistor is a triode, and a base, a collector and an emitter of the triode are a control terminal, a high potential terminal and a low potential terminal of the first or second adjusting transistor, respectively.
9. The output voltage compensation circuit of claim 4, wherein the resistor Rx is an adjustable resistor, and the adjustment step of the adjustable resistor corresponds to the number of nodes of the lithium battery pack in equal proportion, so as to achieve the corresponding voltage output by adjusting the magnitude of the resistor Rx when the number of nodes of the lithium battery pack changes.
10. A switching power supply having an output voltage compensation circuit provided between a transformer secondary voltage output terminal and a load voltage output terminal of the switching power supply, wherein the output voltage compensation circuit is the output voltage compensation circuit according to any one of claims 1 to 9.
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| CN113852274A (en) * | 2021-09-26 | 2021-12-28 | 石家庄通合电子科技股份有限公司 | Switching power supply far-end compensation circuit and switching power supply |
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| CN113098236B (en) | 2022-01-07 |
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