CN113311216A - Switching power supply sampling circuit, switching power supply and household appliance - Google Patents
Switching power supply sampling circuit, switching power supply and household appliance Download PDFInfo
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- CN113311216A CN113311216A CN202110747341.5A CN202110747341A CN113311216A CN 113311216 A CN113311216 A CN 113311216A CN 202110747341 A CN202110747341 A CN 202110747341A CN 113311216 A CN113311216 A CN 113311216A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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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
Abstract
The invention discloses a switching power supply sampling circuit, a switching power supply and a household appliance, wherein the switching power supply sampling circuit comprises: the voltage stabilizing sampling circuit is used for connecting the output end of the power supply circuit, triggering when the output voltage of the power supply circuit is greater than the preset voltage and outputting a current sampling signal; the input end of the switch amplifying circuit is connected with the output end of the voltage stabilizing sampling circuit, and the output end of the switch amplifying circuit is used for being connected with the voltage feedback end of the control circuit; and the switch amplifying circuit is used for outputting a voltage feedback signal corresponding to the current magnitude to the control circuit after current amplification and voltage conversion are carried out on the current sampling signal so that the control circuit can adjust the output voltage of the power supply circuit according to the received voltage feedback signal. The technical scheme of the invention can reduce the design cost of the sampling circuit in the switching power supply and the occupied area of the sampling circuit on the PCB.
Description
Technical Field
The invention relates to the technical field of switching power supply sampling, in particular to a switching power supply sampling circuit, a switching power supply and a household appliance.
Background
At present, most household appliances adopt a switching power supply as a power supply. The existing switching power supply adjusts the output voltage value of the power supply circuit by enabling the control circuit to sample the output voltage sampling signal according to the voltage sampling circuit, thereby realizing the stabilization of the output voltage Vout of the switching power supply. However, in the prior art, the voltage sampling circuit changes the direction of the feedback current, so that the area of the PCB occupied by the voltage sampling circuit is too large.
Disclosure of Invention
The invention mainly aims to provide a switching power supply sampling circuit, and aims to solve the problem that a voltage sampling circuit in a switching power supply occupies too large area of a PCB (printed circuit board)
In order to achieve the above object, the sampling circuit of a switching power supply provided by the present invention is applied to a switching power supply, where the switching power supply includes a power supply circuit and a control circuit for controlling an output voltage of the power supply circuit, and the sampling circuit of the switching power supply includes:
the voltage-stabilizing sampling circuit is used for connecting the output end of the power supply circuit, triggering when the output voltage of the power supply circuit is greater than the preset voltage, and outputting a current sampling signal; and
the input end of the switch amplifying circuit is connected with the output end of the voltage-stabilizing sampling circuit, and the output end of the switch amplifying circuit is used for being connected with the voltage feedback end of the control circuit;
the switch amplifying circuit is used for outputting a voltage feedback signal corresponding to the current after the current sampling signal is subjected to current amplification and voltage conversion to the control circuit, so that the control circuit can adjust the output voltage of the power supply circuit according to the received voltage feedback signal.
Optionally, the switching amplification circuit comprises: the circuit comprises a power supply input end, a first switching device, a first capacitor and a first resistor; the controlled end of the first switching device is connected with the input end of the switching amplification circuit, the input end of the first switching device is connected with the power supply input end so as to access a preset power supply signal accessed by the power supply input end, and the output end of the first switching device and the grounding end of the control circuit are connected to the same ground; the first end of the first resistor is connected with the input end of the first switching device, and the second end of the first resistor is connected with the output end of the switching amplification circuit; one end of the first capacitor is connected with the second end of the first resistor, and the other end of the first capacitor is grounded.
Optionally, the first switching device is one or a combination of a triode and a MOS transistor.
Optionally, the switching amplification circuit further comprises:
the switch driving circuit is connected between the input end of the first switching device and the input end of the switch amplifying circuit in series;
the first end of the false triggering protection circuit is connected with the input end of the switch amplification circuit, and the second end of the false triggering protection circuit is grounded or connected with a preset voltage value; and the number of the first and second groups,
and the filter circuit is connected with the false triggering protection circuit in parallel.
Optionally, the voltage regulation sampling circuit includes: a second resistor and a first diode; the cathode of the first diode is connected with the output end of the power supply circuit through the first resistor, and the anode of the first diode is the output end of the voltage stabilizing sampling circuit.
Optionally, the switching power supply sampling circuit further includes:
and the working current sampling circuit is used for sampling the working current of the power tube and outputting a working current sampling signal to the current feedback end of the control circuit, so that the control circuit controls the power circuit to stop working when the control circuit determines that the working current of the power tube is overcurrent according to the received working current sampling signal.
Optionally, the switching power supply sampling circuit further includes:
the input voltage sampling circuit is used for sampling the input voltage of the power circuit and outputting an input voltage sampling signal to the input voltage feedback end of the control circuit so that the control circuit can control the power circuit to stop working when determining that the input voltage of the power circuit is overvoltage or undervoltage according to the received input voltage sampling signal.
The present invention also provides a switching power supply, including:
a power supply circuit;
the control circuit is used for controlling the output voltage of the power supply circuit; and the number of the first and second groups,
the switching power supply sampling circuit is connected with the power supply circuit and the control circuit respectively.
Optionally, a power output end of the control circuit is connected to the switching power supply sampling circuit, and is configured to output a preset power signal to the switching power supply sampling circuit.
The invention also provides a household appliance comprising the switching power supply.
The switching power supply sampling circuit adopts the voltage-stabilizing sampling circuit and the switching amplifying circuit, and triggers the output current sampling signal to the switching amplifying circuit when the output voltage of the power supply circuit is greater than the preset voltage, so that the switching amplifying circuit can output a voltage feedback signal corresponding to the current to the control circuit after carrying out current amplification and voltage conversion on the received current sampling signal, and the control circuit can adjust the output voltage of the power supply circuit according to the received voltage feedback signal. According to the technical scheme, the switch amplifying circuit is constructed and realized by adopting the switch device with the amplifying interval, the design cost of the switch power supply sampling circuit and the occupied area of the switch power supply sampling circuit on the PCB can be reduced, the layout of an electric control assembly on the PCB is facilitated, a feedback loop does not need to be designed, and the design difficulty of the circuit is further facilitated to be reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of a circuit block of a switching power supply sampling circuit according to an embodiment of the present invention;
FIG. 2 is a schematic circuit block diagram of a switching power supply sampling circuit according to another embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of a switching power supply sampling circuit according to another embodiment of the present invention;
fig. 4 is a schematic circuit diagram of an embodiment of a sampling circuit in a switching power supply of the prior art.
The reference numbers illustrate:
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and 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.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides a switching power supply sampling circuit which is applied to a switching power supply.
The switching power supply may include a power supply circuit 50, a control circuit 60, and an output voltage sampling circuit. The power supply circuit can perform corresponding power supply processing on the accessed alternating current or direct current power supply under the control of the control circuit, so that the accessed alternating current or direct current power supply can supply power to the equipment after being converted into a power supply required by the equipment, namely the output voltage of the power supply circuit is the output voltage Vout of the switching power supply.
In the embodiment shown in fig. 4, fig. 4 is a voltage sampling circuit of a conventional switching power supply, in this embodiment, a control circuit of the switching power supply is a main control chip U1, U2 is a photocoupler, and U3 is a voltage regulator U3; for convenience of description, the following embodiments replace the expression "photocoupler" with "photocoupler". The voltage regulator U3 is connected to the output voltage Vout of the switching power supply divided by a preset voltage division ratio through a voltage division circuit composed of a sixth resistor R6 and a seventh resistor R7, and the impedance of the voltage regulator U3 can be adjusted according to the connected voltage, thereby adjusting the current flowing through the voltage regulator U. The eighth resistor R8 and the ninth resistor R9 are current conversion resistors, the resistance values of the current conversion resistors are matched with the driving current of the optocoupler U2, one end of the eighth resistor R8 is also connected to the output voltage Vout of the switching power supply and is used for being matched with the ninth resistor and the voltage stabilizing source U3 to convert the output voltage Vout of the switching power supply into the primary driving current of the optocoupler U2. Therefore, when the output voltage Vout of the switching power supply fluctuates, the voltage stabilizing source U3 can adjust the primary driving current of the optocoupler U2 according to the fluctuation, so that the secondary side of the optocoupler U2 can induce and generate an induced current which corresponds to the adjusted driving current and has an opposite direction, and the induced current can be converted into a voltage signal by the current-voltage conversion circuit and then used as a voltage sampling signal to be output to the voltage feedback pin FB of the main control chip U1. In the embodiment shown in fig. 4, the current-voltage conversion circuit is integrated in the main control chip U1, and a third capacitor C3 and a tenth resistor R10 are further connected in series between the cathode of the regulator U3 and the sixth resistor. The main control chip U1 can control the power supply circuit to eliminate its output voltage fluctuation according to the received voltage sampling signal, thereby realizing the output voltage Vout stability of the switching power supply. It can be understood that, can be with the feedback current that flows into to ground at opto-coupler U2 during operation, convert the voltage sampling signal that flows into to main control chip U1 into, thereby played the effect that changes the feedback current direction, and because opto-coupler U2 is bulky, make the PCB area that voltage sampling circuit occupy too big, be unfavorable for the overall arrangement of automatically controlled subassembly on PCB, and the voltage sampling circuit based on opto-coupler U2 founds still exists with too high costs, need consider the problem that feedback loop makes the design degree of difficulty big.
In view of the above problem, referring to fig. 1 to 3, in an embodiment of the present invention, the switching power supply sampling circuit includes:
the voltage-stabilizing sampling circuit 10 is used for connecting the output end of the power circuit 50, triggering when the output voltage Vout of the power circuit is greater than the preset voltage, and outputting a current sampling signal; and
the input end of the switch amplifying circuit 20 is connected with the output end of the voltage stabilizing sampling circuit 10, and the output end of the switch amplifying circuit 20 is used for connecting the voltage feedback end of the control circuit 60;
the switch amplifying circuit 20 is configured to output a voltage feedback signal corresponding to the magnitude of the current to the control circuit 60 after performing current amplification and voltage conversion on the current sampling signal, so that the control circuit 60 adjusts the output voltage Vout of the power circuit according to the received voltage feedback signal.
In this embodiment, the voltage-stabilizing sampling circuit 10 may be implemented by using discrete devices such as a capacitor, a resistor, a voltage-stabilizing diode, or a voltage-stabilizing source U3; alternatively, a dedicated voltage chip may be used. The sampling terminal of the regulated sampling circuit 10 may be connected to the output terminal of the power circuit 50 to sample the output voltage Vout of the power circuit in real time and obtain an output voltage sampling signal. The voltage-stabilizing sampling circuit 10 may be integrated with a preset voltage parameter and a hardware circuit or a software algorithm for comparison, so that when the output voltage sampling signal is obtained, the output voltage sampling signal may be compared with the preset voltage parameter, and when the comparison result indicates that the voltage value corresponding to the voltage sampling signal is greater than the preset voltage threshold value corresponding to the preset voltage parameter, the current sampling signal generation unit or the generation program may be driven to output the current sampling signal corresponding to the voltage sampling signal, that is, corresponding to the output voltage Vout of the power circuit, and being the current signal. Certainly, the preset voltage parameter may also be stored in other functional circuits in the switching power supply, and the voltage stabilizing sampling circuit 10 may be called from other functional circuits when in operation. In another embodiment, when the comparison result is that the voltage value corresponding to the voltage sampling signal is greater than the preset voltage threshold corresponding to the preset voltage parameter, the voltage stabilizing sampling circuit 10 may further access an output current having a magnitude corresponding to the voltage sampling signal from the output terminal of the power circuit 50 as the current sampling signal by operating a corresponding hardware circuit, and output the current sampling signal. It is understood that the regulated voltage sampling circuit 10 can be always in the trigger state by setting the preset voltage threshold to a small value, so as to output the current sampling signal in real time.
The switch amplifying circuit 20 may be provided with a current amplifying circuit and a current-voltage converting circuit; the current amplifying circuit can be constructed and realized based on a switching device with an amplifying section, and the current-voltage conversion circuit can be constructed and realized by adopting discrete devices such as resistors and the like. The switch amplifier circuit 20 may output the accessed current sampling signal to the current amplifier circuit to trigger a switch device in the current amplifier circuit to be in an amplification interval, so that the current sampling signal may be output to the current-voltage conversion circuit for voltage conversion after current amplification. The current-voltage conversion circuit can convert the amplified current sampling signal into a voltage feedback signal corresponding to the voltage signal and output the voltage feedback signal to the voltage feedback end of the control circuit 60, so that the control circuit 60 can control the power circuit 50 to work according to the received voltage feedback signal, thereby achieving the effect of stabilizing the output voltage Vout of the power circuit. It will also be appreciated that the control circuit 60 may determine a target value of the output voltage Vout of the power supply circuit at that time, i.e., a target output voltage, based on the power supply demand signal output by the device or a voltage output instruction set by the user, and may determine an actual value of the output voltage Vout of the power supply circuit at that time, i.e., an actual output voltage, based on the received voltage feedback signal; the main controller can also calculate the voltage difference between the determined target output voltage and the actual output voltage according to the determined target output voltage and the actual output voltage, and can control the working condition of the power circuit 50 according to the voltage difference so that the output voltage of the power circuit can correspondingly increase/decrease the voltage difference, thereby realizing the purpose of maintaining the dynamic stability of the output voltage Vout of the switching power supply.
Therefore, when the switching power supply sampling circuit works, the switching amplifying circuit 20 replaces the optical coupler U2 to realize the effect of changing the current direction, and the switching amplifying circuit 20 constructed based on the switching device with the amplifying interval has the main volume and cost from the switching device, and the volume and cost of the switching device are far smaller than those of the optical coupler U2 device, so that the design cost and the occupied area of the switching power supply sampling circuit on a PCB (printed circuit board) can be reduced, the layout of an electric control assembly on the PCB is facilitated, a feedback loop does not need to be designed, and the design difficulty of the circuit is further facilitated to be reduced.
Referring to fig. 1 to 3, in an embodiment of the present invention, the switching amplifier circuit 20 includes: the circuit comprises a power input end Vin, a first switching device T1, a first capacitor C1 and a first resistor R1; a controlled terminal of the first switching device T1 is connected to an input terminal of the switching amplifying circuit 20, an input terminal of the first switching device T1 is connected to the power input terminal Vin to receive a preset power signal received at the power input terminal Vin, and an output terminal of the first switching device T1 is connected to the same ground as a ground terminal of the control circuit 60; a first terminal of the first resistor R1 is connected to the input terminal of the first switching device T1, and a second terminal of the first resistor R1 is connected to the output terminal of the switching amplification circuit 20; one end of the first capacitor C1 is connected to the second end of the first resistor R1, and the other end of the first capacitor C1 is grounded.
In this embodiment, the controlled terminal of the first switching device T1 may access the current sampling signal output by the regulated sampling circuit 10, and may operate itself in the amplification region under the driving of the current sampling signal. When the first switching device T1 works in the amplification region, it can control the preset power signal of the current signal flowing from its input end to its output end, and make the current value of the flowing preset power signal and the current value of the current sampling signal form a preset amplification factor, thereby realizing the amplification of the current sampling signal. The first resistor R1 is a voltage converting resistor, and is used to convert a predetermined power signal with a predetermined amplification factor corresponding to the current sampling signal into a corresponding voltage feedback signal, and output the voltage feedback signal to the voltage feedback terminal of the control circuit 60. Of course, the power signal may also be a voltage signal, and the input terminal of the first switching device T1 may be connected to the predetermined power signal of the voltage signal through a voltage-current converting resistor. The first capacitor C1 is a filter capacitor, and is used for filtering the voltage sampling signal output by the first resistor R1 to filter out an alternating current component therein, which is beneficial to improving the signal accuracy of the output voltage sampling signal. It should be noted that, in the technical solution of the present invention, the first switching device T1 and the control circuit 60 are commonly disposed, so that the power signal connected to the input terminal of the first switching device T1 can be output after voltage conversion by the first resistor R1, thereby implementing the function of current reversal.
In the existing voltage sampling circuit constructed based on the optocoupler U2, the design concept is usually to connect the primary side and the secondary side of the optocoupler U2 to different places to achieve an ac isolation function, but in practical applications, it is found that an isolation circuit such as a transformer is provided in the power circuit 50 itself to reduce ac noise in the output voltage thereof and to prevent the ac noise from being superimposed on the output voltage thereof again through the sampling loop and the control circuit 60 again through the feedback loop, that is, the ac noise in the output voltage Vout of the power circuit is low, and it is not necessary to perform isolation again in the sampling loop. The technical scheme of the invention overcomes the design bias, and the first switching device T1 and the control circuit 60 are arranged in common, and the first capacitor C1 is arranged to filter the alternating current noise in the voltage feedback signal, so that the optocoupler U2 can be replaced by a simpler circuit structure, the circuit structure of the switching amplifying circuit 20 is favorably simplified, and the PCB area occupied by the switching amplifying circuit 20 and the cost thereof are favorably reduced.
Referring to fig. 1 to 3, in an embodiment of the present invention, the first switching device T1 is one or more combinations of a triode or a MOS transistor.
In this embodiment, the first switching device T1 may be one or more of an NPN transistor, a PNP transistor, an N-MOS transistor, or a P-MOS transistor. When the first switching device T1 is a transistor, its input terminal may be a collector, its controlled terminal may be a base, and its output terminal may be an emitter, and the first switching device T1 and the control circuit 60 may be in a common emitter configuration. When the first switching device T1 is a MOS transistor, its input terminal may be a source, its controlled terminal may be a gate, and its output terminal may be a drain, and the first switching device T1 and the control circuit 60 may be configured as a common drain. In another embodiment, the switching amplifying circuit 20 of the present disclosure can also be implemented by connecting the input terminal or the controlled terminal of the first switching device T1 and the ground terminal of the control circuit 60 to the same ground, so that the first switching device T1 and the control circuit 60 are in a common collector configuration, or in a common base configuration, or in a common source configuration, or in a common gate configuration, which is not limited. Therefore, the first switching device T1 can be realized by a common power transistor, which is beneficial to further reducing the design difficulty and cost of the switching amplifying circuit 20, and is also beneficial to the application of the switching power supply sampling circuit in the mass production of the switching power supply.
Referring to fig. 1 to 3, in an embodiment of the present invention, the switching amplification circuit 20 further includes:
a switch driving circuit 21 connected in series between an input terminal of the first switching device T1 and an input terminal of the switching amplifying circuit 20;
a false triggering protection circuit 22, wherein one end of the false triggering protection circuit 22 is connected with the input end of the switch amplification circuit 20, and the other end of the false triggering protection circuit 22 is grounded; and the number of the first and second groups,
and a filter circuit 23 provided in parallel with the false triggering protection circuit 22.
The first switching device T1 needs a certain driving voltage, also called bias voltage, to operate in the amplification region. In this regard, the present application is provided with a switch driving circuit 21, and the switch driving circuit 21 can be implemented by using a resistance-fixed resistor and a programmable logic control relay. The switch driving circuit 21 is configured to convert a current sampling signal of the current signal into a voltage signal and load the voltage signal on the controlled terminal of the first switching device T1, so as to drive the first switching device T1 to work in an amplification region all the time, which is beneficial to improving the working stability of the switching power supply sampling circuit of the present invention.
In this embodiment, when the first switching device T1 employs a high-level-driven power transistor such as an N-MOS transistor and an NPN-type transistor, the second end of the false trigger protection circuit 22 may be grounded, and at this time, the false trigger protection circuit 22 is a pull-down circuit, so that when the switching power supply sampling circuit does not operate, the level at the controlled end of the first switching device T1 is pulled down to the ground potential, so that the high-level-driven power transistor is completely turned off. When the first switching device T1 adopts a low-level driving power transistor such as a P-MOS transistor and a PNP transistor, the second end of the false triggering protection circuit 22 may be connected to a preset voltage value, and the false triggering protection circuit 22 is a pull-up circuit, so that when the switching power supply sampling circuit does not work, the level at the controlled end of the first switching device T1 is pulled up to the preset voltage value, so that the low-level driving power transistor is completely turned off. The filter circuit 23 is configured to perform filtering processing on the current sampling signal accessed by the input terminal of the switching amplifier circuit 20, so as to reduce an alternating current noise component in the current sampling signal. In the embodiment shown in fig. 4, the switch driving circuit 21 and the false triggering protection circuit 22 are respectively implemented by using a third resistor R3 and a fourth resistor R4, and the filter circuit 23 is implemented by using a second capacitor C2, so as to further simplify the circuit structure and reduce the cost. Therefore, the probability that the first switching device T1 triggers the control circuit 60 to regulate the voltage due to misoperation can be reduced, and the working stability of the switching power supply sampling circuit is further improved.
Referring to fig. 1 to 3, in an embodiment of the present invention, the regulated sampling circuit 10 includes: a second resistor R2 and a first diode D1; the cathode of the first diode D1 is connected to the output terminal of the power circuit 50 via the first resistor R1, and the anode of the first diode D1 is the output terminal of the regulated sampling circuit 10.
In practical applications, the voltage regulator U3, for example, the TL431, generally needs to access a reference voltage value, so that when the output voltage of the divided switching power supply is accessed, the output voltage value is compared with the reference voltage value, and when the output voltage value after the divided voltage is greater than the reference voltage value as a comparison result, the impedance value of the switching power supply itself is reduced, so that a dedicated circuit needs to be designed in the switching power supply, and even an integrated circuit is used to provide the reference voltage value for the voltage regulator U3. According to the technical scheme, the voltage-stabilizing sampling circuit 10 is constructed by adopting a second resistor R2 and a first diode D1; the first diode D1 is a voltage regulator, and the first diode D1 is reversely arranged, so that the first diode D1 can be in a reverse conducting state under the action of the output voltage Vout of the power circuit, that is, the preset voltage value is the reverse breakdown voltage of the first diode D1. According to the technical scheme, the characteristic that the voltages at two ends of the diode are constant and the current can be changed in a large range under the reverse conduction state is utilized, so that the second resistor R2 and the dynamic resistor of the first diode D1 form a current sampling circuit, the output current of the power circuit 50 is sampled, and a current sampling signal is output. Therefore, the voltage regulator U3 and a special designed circuit or an integrated circuit are not needed to provide the reference voltage value, which is beneficial to further reducing the cost of the circuit and simplifying the circuit structure.
Referring to fig. 1 to 3, in an embodiment of the present invention, the power circuit 50 includes a power transistor, and the switching power sampling circuit further includes:
the working current sampling circuit 30 is configured to sample the working current of the power tube, and output a working current sampling signal to the current feedback end of the control circuit 60, so that the control circuit 60 controls the power circuit 50 to stop working when determining that the working current of the power tube is overcurrent according to the received working current sampling signal.
In this embodiment, the working current sampling circuit 30 may be implemented by a shunt circuit composed of discrete devices such as a resistor and a capacitor; alternatively, a dedicated current sensor may be used. The detection terminal of the working current sampling circuit 30 may be connected to the input terminal of the power transistor to sample the current accessed by the input terminal when the power transistor is turned on, and output a corresponding working current sampling signal to the current feedback terminal of the control circuit 60 (i.e., the S/OCP pin of the main control chip U1 in fig. 3, which is grounded via a fifth resistor in the embodiment shown in fig. 3). The control circuit 60 may compare the received working current sampling signal with a corresponding working current threshold after converting the working current sampling signal into a digital signal, and may determine that the working current of the power tube is over-current when the current value corresponding to the working current sampling signal is greater than the current value corresponding to the working current threshold, and may control each power tube to be turned off to stop the power circuit 50 from working, thereby implementing over-current protection, also called short-circuit protection, on the power tube. Therefore, the power tube can be prevented from losing efficacy due to overhigh working current, the functional integration level of the sampling circuit of the switching power supply and the working stability of the power supply circuit 50 are favorably improved, and the service life of the switching power supply is favorably prolonged.
Referring to fig. 1 to 3, in an embodiment of the present invention, the switching power supply sampling circuit further includes:
the input voltage sampling circuit 40 is configured to sample an input voltage of the power circuit 50, and output an input voltage sampling signal to an input voltage feedback end of the control circuit 60, so that the control circuit 60 controls the power circuit 50 to stop working when determining that the input voltage of the power circuit 50 is overvoltage or undervoltage according to the received input voltage sampling signal.
In this embodiment, the input voltage sampling circuit 40 may be implemented by a voltage dividing circuit composed of discrete devices such as a resistor and a capacitor; alternatively, a dedicated voltage sensor may be used. The detection terminal of the input voltage sampling circuit 40 can be connected to the positive and negative input terminals of the power circuit 50 to sample the input voltage of the power circuit 50 and output a corresponding input voltage sampling signal to the input voltage feedback terminal of the control circuit 60 (i.e. the BR pin of the main control chip U1 in fig. 3, which is also grounded in the embodiment shown in fig. 3). The control circuit 60 may compare the received input voltage sampling signal with the corresponding input voltage threshold after converting the input voltage sampling signal into a digital signal, and may determine that the input voltage of the power circuit 50 is over-current when the voltage value corresponding to the input voltage sampling signal is greater than the voltage value corresponding to the input voltage threshold; when the voltage value corresponding to the input voltage sampling signal is smaller than the voltage value corresponding to the input voltage threshold, it is determined that the input voltage of the power circuit 50 is under-voltage at this time. The control circuit 60 may control the power circuit 50 to stop working when either of the overvoltage or the undervoltage is determined to occur, so as to implement overvoltage protection and undervoltage protection for the power circuit 50. Therefore, the device in the power supply circuit 50 can be prevented from being damaged due to the fact that the voltage and current stress borne by the device exceeds the normal use range due to too high or too low input voltage, meanwhile, the requirement cannot be met due to the fact that the electrical performance index is damaged, the functional integration level of the sampling circuit of the switching power supply and the working stability of the power supply circuit 50 are favorably improved, and the service life of the switching power supply is favorably prolonged.
The invention also proposes a switching power supply comprising a power supply circuit 50, a control circuit 60 and a switching power supply sampling circuit.
The power circuit 50 may be constructed by discrete electronic devices such as an inductance element, a power tube, and a diode; the power tube can be one or more combinations of IGBT or MOSFET. The power circuit 50 may include a rectifying circuit and a voltage converting circuit, and the power tube may be disposed in the voltage converting circuit; the input end of the power circuit 50 can be connected to a power signal output by an ac power supply such as a commercial power grid or a dc power supply such as a battery, and can output the power signal to the rectifying circuit for rectification and conversion, so that the connected power signal is rectified and then output to the voltage converting circuit for corresponding voltage boosting or voltage reducing conversion and then output to the power supply interface of the device. The control circuit 60 may be a microprocessor such as an MCU, DSP or FPGA; alternatively, a dedicated master control chip U1 may be used. The control circuit 60 may control the power circuit 50 to convert the accessed power signal into a corresponding output voltage and output the corresponding output voltage by controlling the on/off logic of each power transistor in the power circuit 50. In the embodiment shown in fig. 3, two D/ST pins of the main control chip U1 may output control signals for controlling the on/off of corresponding power transistors.
The specific structure of the sampling circuit of the switching power supply refers to the above embodiments, and since the switching power supply adopts all the technical solutions of all the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are achieved, and no further description is given here.
Referring to fig. 1 to 3, in an embodiment of the present invention, a power output terminal of the control circuit 60 is connected to the switching power supply sampling circuit, and is configured to output a predetermined power signal to the switching power supply sampling circuit.
In this embodiment, the control circuit 60 may be provided with a voltage converting circuit, configured to convert a voltage of the power supply terminal into a preset voltage value, and output the voltage to the input terminal of the first switching device T1 through a power output pin (the pin is not shown in the main control chip U1 in fig. 3), so as to provide a preset power signal for current amplification of the first switching device T1 in the switching power supply sampling circuit. Of course, in another alternative embodiment, the voltage converting circuit may be further disposed separately from the control circuit 60 to provide the preset power signal for the switching power sampling circuit under the control of the control circuit 60. Thus, by enabling the control circuit 60 to provide the preset power signal for the switching power sampling circuit, the functional integration level of the control circuit 60 is improved, and the area of the PCB for arranging the voltage conversion circuit can be saved, thereby facilitating the optimization of the layout of each functional circuit on the PCB.
The invention further provides a household appliance, which comprises a switching power supply, the specific structure of the switching power supply refers to the above embodiments, and the household appliance adopts all the technical schemes of all the above embodiments, so that the household appliance at least has all the beneficial effects brought by the technical schemes of the above embodiments, and the details are not repeated herein. Wherein the household appliance may be an air conditioner.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. The utility model provides a switching power supply sampling circuit, is applied to among the switching power supply, switching power supply includes power supply circuit and control the control circuit of power supply circuit output voltage size, its characterized in that, switching power supply sampling circuit includes:
the voltage stabilizing sampling circuit is used for connecting the output end of the power supply circuit, triggering when the output voltage of the power supply circuit is greater than the preset voltage and outputting a current sampling signal; and
the input end of the switch amplifying circuit is connected with the output end of the voltage-stabilizing sampling circuit, and the output end of the switch amplifying circuit is used for being connected with the voltage feedback end of the control circuit;
and the switch amplifying circuit is used for outputting a voltage feedback signal corresponding to the current magnitude to the control circuit after current amplification and voltage conversion are carried out on the current sampling signal so that the control circuit can adjust the output voltage of the power supply circuit according to the received voltage feedback signal.
2. The switching power supply sampling circuit of claim 1, wherein the switching amplification circuit comprises: the circuit comprises a power supply input end, a first switching device, a first capacitor and a first resistor; the controlled end of the first switching device is connected with the input end of the switching amplification circuit, the input end of the first switching device is connected with the power supply input end so as to access a preset power supply signal accessed by the power supply input end, and the output end of the first switching device and the grounding end of the control circuit are connected to the same ground; the first end of the first resistor is connected with the input end of the first switching device, and the second end of the first resistor is connected with the output end of the switching amplification circuit; one end of the first capacitor is connected with the second end of the first resistor, and the other end of the first capacitor is grounded.
3. The switching power supply sampling circuit of claim 2, wherein the first switching device is one or more of a triode or a MOS transistor.
4. The switching power supply sampling circuit of claim 2, wherein the switching amplification circuit further comprises:
the switch driving circuit is connected between the input end of the first switching device and the input end of the switch amplifying circuit in series;
the protection circuit is triggered by mistake, one end of the protection circuit is connected with the input end of the switch amplification circuit, and the other end of the protection circuit is grounded; and the number of the first and second groups,
and the filter circuit is connected with the false triggering protection circuit in parallel.
5. The switching power supply sampling circuit of claim 1, wherein the regulated sampling circuit comprises: a second resistor and a first diode; the cathode of the first diode is connected with the output end of the power supply circuit through the first resistor, and the anode of the first diode is the output end of the voltage stabilizing sampling circuit.
6. The switching power supply sampling circuit of claim 1, wherein the power supply circuit comprises a power transistor, the switching power supply sampling circuit further comprising:
and the working current sampling circuit is used for sampling the working current of the power tube and outputting a working current sampling signal to the current feedback end of the control circuit, so that the control circuit controls the power circuit to stop working when the control circuit determines that the working current of the power tube is overcurrent according to the received working current sampling signal.
7. The switching power supply sampling circuit of claim 1, further comprising:
the input voltage sampling circuit is used for sampling the input voltage of the power circuit and outputting an input voltage sampling signal to the input voltage feedback end of the control circuit so that the control circuit can control the power circuit to stop working when determining that the input voltage of the power circuit is overvoltage or undervoltage according to the received input voltage sampling signal.
8. A switching power supply, characterized in that the switching power supply comprises:
a power supply circuit;
the control circuit is used for controlling the output voltage of the power supply circuit; and the number of the first and second groups,
the switching power supply sampling circuit according to any one of claims 1 to 7, connected to the power supply circuit and the control circuit, respectively.
9. The switching power supply according to claim 8, wherein the power supply output terminal of the control circuit is connected to the switching power supply sampling circuit for outputting a predetermined power supply signal to the switching power supply sampling circuit.
10. A household appliance, characterized in that it comprises a switching power supply according to any one of claims 8-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110747341.5A CN113311216A (en) | 2021-06-30 | 2021-06-30 | Switching power supply sampling circuit, switching power supply and household appliance |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110747341.5A CN113311216A (en) | 2021-06-30 | 2021-06-30 | Switching power supply sampling circuit, switching power supply and household appliance |
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| CN113311216A true CN113311216A (en) | 2021-08-27 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116865225A (en) * | 2023-09-04 | 2023-10-10 | 深圳莱福德科技股份有限公司 | Input overvoltage protection circuit |
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2021
- 2021-06-30 CN CN202110747341.5A patent/CN113311216A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116865225A (en) * | 2023-09-04 | 2023-10-10 | 深圳莱福德科技股份有限公司 | Input overvoltage protection circuit |
| CN116865225B (en) * | 2023-09-04 | 2024-01-05 | 深圳莱福德科技股份有限公司 | Input overvoltage protection circuit |
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