Switching power supply sampling circuit, switching power supply and household appliances

Abstract

The present invention discloses a switching power supply sampling circuit, a switching power supply, and a household appliance. The switching power supply sampling circuit includes: a voltage-stabilizing sampling circuit connected to the output of a power supply circuit and triggered to output a current sampling signal when the output voltage of the power supply circuit exceeds a preset voltage; and a switching amplifier circuit, the input of which is connected to the output of the voltage-stabilizing sampling circuit, the output of which is connected to a voltage feedback terminal of a control circuit. The switching amplifier circuit amplifies and converts the current sampling signal into a voltage, and then outputs a voltage feedback signal corresponding to the current to the control circuit, so that the control circuit can adjust the output voltage of the power supply circuit based on the received voltage feedback signal. The technical solution of the present invention can reduce the design cost of the sampling circuit in the switching power supply and the area occupied on the printed circuit board (PCB).

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supply sampling, and in particular to a switching power supply sampling circuit, a switching power supply and a household appliance. Background Art

[0002] Currently, most household appliances use switching power supplies. Existing switching power supplies achieve a stable output voltage (Vout) by enabling the control circuit to adjust the output voltage of the power circuit based on a voltage sampling signal output by a voltage sampling circuit. However, the voltage sampling circuit's ability to redirect the feedback current in existing technologies results in excessive PCB area being occupied by the circuit. Summary of the Invention

[0003] The main purpose of the present invention is to provide a switching power supply sampling circuit, aiming to solve the problem that the voltage sampling circuit in the switching power supply occupies too large a PCB area.

[0004] To achieve the above-mentioned object, the present invention proposes a switching power supply sampling circuit, which is applied to a switching power supply. The switching power supply includes a power supply circuit and a control circuit for controlling the output voltage of the power supply circuit. The switching power supply sampling circuit includes:

[0005] a voltage-stabilized sampling circuit, connected to the output end of the power supply circuit and triggered to output a current sampling signal when the output voltage of the power supply circuit is greater than a preset voltage; and

[0006] a switching amplifier circuit, wherein the input end of the switching amplifier circuit is connected to the output end of the voltage stabilization sampling circuit, and the output end of the switching amplifier circuit is used to connect to the voltage feedback end of the control circuit;

[0007] The switching amplifier circuit is used to amplify and convert the current sampling signal into a voltage, and then output a voltage feedback signal corresponding to the current magnitude 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.

[0008] Optionally, the switching amplifier circuit includes: a power input terminal, a first switching device, a first capacitor, and a first resistor; the controlled terminal of the first switching device is connected to the input terminal of the switching amplifier circuit, the input terminal of the first switching device is connected to the power input terminal to receive a preset power signal received by the power input terminal, and the output terminal of the first switching device is connected to the same ground as the ground terminal of the control circuit; the first end of the first resistor is connected to the input terminal of the first switching device, and the second end of the first resistor is connected to the output terminal of the switching amplifier circuit; one end of the first capacitor is connected to the second end of the first resistor, and the other end of the first capacitor is grounded.

[0009] Optionally, the first switching device is a transistor or a MOS transistor or a combination thereof.

[0010] Optionally, the switching amplifier circuit further includes:

[0011] a switch driving circuit, connected in series between the input terminal of the first switch device and the input terminal of the switch amplifier circuit;

[0012] a false trigger protection circuit, wherein a first terminal of the false trigger protection circuit is connected to the input terminal of the switching amplifier circuit, and a second terminal of the false trigger protection circuit is grounded or connected to a preset voltage value; and

[0013] The filter circuit is arranged in parallel with the false trigger protection circuit.

[0014] Optionally, the voltage-stabilized sampling circuit includes: a second resistor and a first diode; the cathode of the first diode is connected to the output end of the power supply circuit via the second resistor, and the anode of the first diode is the output end of the voltage-stabilized sampling circuit.

[0015] Optionally, the switching power supply sampling circuit further includes:

[0016] The working current sampling circuit is used to sample the working current of the power tube and output a working current sampling signal to the current feedback terminal of the control circuit, so that when the control circuit determines that the working current of the power tube is overcurrent based on the received working current sampling signal, it can control the power supply circuit to stop working.

[0017] Optionally, the switching power supply sampling circuit further includes:

[0018] An input voltage sampling circuit is used to sample the input voltage of the power supply circuit and output an input voltage sampling signal to the input voltage feedback terminal of the control circuit, so that the control circuit can control the power supply circuit to stop working when it determines that the input voltage of the power supply circuit is overvoltage or undervoltage based on the received input voltage sampling signal.

[0019] The present invention further provides a switching power supply, comprising:

[0020] Power supply circuit;

[0021] a control circuit, configured to control the output voltage of the power supply circuit; and

[0022] The switching power supply sampling circuit as described above is connected to the power supply circuit and the control circuit respectively.

[0023] Optionally, the power output terminal of the control circuit is connected to the switching power sampling circuit, and is used to output a preset power signal to the switching power sampling circuit.

[0024] The present invention also provides a household appliance, which includes the switching power supply described above.

[0025] The switching power supply sampling circuit of the present invention utilizes a voltage-stabilizing sampling circuit and a switching amplifier circuit. When the output voltage of the power supply circuit exceeds a preset voltage, the voltage-stabilizing sampling circuit triggers the output of a current sampling signal to the switching amplifier circuit. This allows the switching amplifier circuit to amplify and convert the received current sampling signal, then output a voltage feedback signal corresponding to the current to a control circuit, allowing the control circuit to adjust the output voltage of the power supply circuit based on the received voltage feedback signal. By utilizing a switching device with an amplification range to construct and implement the switching amplifier circuit, the present invention reduces the design cost of the switching power supply sampling circuit and its footprint on the printed circuit board (PCB). This facilitates the layout of electronic control components on the PCB and eliminates the need for a feedback loop, thereby reducing circuit design complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0027] Figure 1 This is a schematic diagram of a circuit module of an embodiment of a switching power supply sampling circuit of the present invention;

[0028] Figure 2 This is a schematic diagram of a circuit module of another embodiment of a switching power supply sampling circuit of the present invention;

[0029] Figure 3 This is a circuit structure diagram of another embodiment of the switching power supply sampling circuit of the present invention;

[0030] Figure 4 The figure is a circuit structure diagram of an embodiment of a sampling circuit in a switching power supply in the prior art.

[0031] Description of Figure Numbers:

[0032]

[0033] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0036] The present invention provides a switching power supply sampling circuit, which is applied to the switching power supply.

[0037] The switching power supply may include a power supply circuit 50, a control circuit 60, and an output voltage sampling circuit. Under the control of the control circuit, the power supply circuit may perform corresponding power processing on the connected AC or DC power supply, so that the connected AC or DC power supply is converted into the power supply required by the device and then powers the device. In other words, the output voltage of the power supply circuit is the output voltage Vout of the switching power supply.

[0038] exist Figure 4 The embodiment shown, Figure 4It is a voltage sampling circuit of an existing switching power supply. In this embodiment, the control circuit of the switching power supply is the main control chip U1, U2 is a photocoupler, and U3 is a voltage regulator U3; for the convenience of description, the following embodiments use "photocoupler" instead of "photocoupler". The voltage regulator U3 can be connected to the output voltage Vout of the switching power supply divided by a preset voltage divider ratio through the voltage divider circuit composed of the sixth resistor R6 and the seventh resistor R7, and can adjust its own impedance value according to the connected voltage, thereby adjusting the current flowing through itself. The eighth resistor R8 and the ninth resistor R9 are current conversion resistors, and their resistance values ​​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 to cooperate with the ninth resistor and the voltage regulator U3 to convert the output voltage Vout of the switching power supply into the driving current of the primary of the optocoupler U2. In this way, when the output voltage Vout of the switching power supply fluctuates, the voltage regulator U3 can adjust the driving current of the primary of the optocoupler U2 according to the fluctuation, so that the secondary of the optocoupler U2 can sense and generate an induced current corresponding to the regulated driving current and in the opposite direction. This induced current can be converted into a voltage signal by the current-voltage conversion circuit and output as a voltage sampling signal to the voltage feedback pin FB of the main control chip U1. Figure 4 In the illustrated embodiment, the current-voltage conversion circuit is integrated into 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 voltage regulator U3 and the sixth resistor. The main control chip U1 can control the power supply circuit to eliminate its output voltage fluctuations based on the received voltage sampling signal, thereby achieving a stable output voltage Vout of the switching power supply. It is understandable that when the optocoupler U2 is working, it can convert the feedback current flowing into the ground into a voltage sampling signal flowing into the main control chip U1, thereby changing the direction of the feedback current. However, due to the large size of the optocoupler U2, the PCB area occupied by the voltage sampling circuit is too large, which is not conducive to the layout of the electronic control components on the PCB. In addition, the voltage sampling circuit constructed based on the optocoupler U2 also has the problems of high cost and the need to consider the feedback loop, which makes the design difficult.

[0039] Regarding the above issues, refer to Figures 1 to 3 In one embodiment of the present invention, the switching power supply sampling circuit includes:

[0040] The voltage stabilization sampling circuit 10 is connected to the output terminal of the power supply circuit 50 and is triggered to output a current sampling signal when the output voltage Vout of the power supply circuit is greater than a preset voltage; and

[0041] The switching amplifier circuit 20 has an input terminal connected to the output terminal of the voltage stabilization sampling circuit 10 , and an output terminal of the switching amplifier circuit 20 is used to connect to the voltage feedback terminal of the control circuit 60 ;

[0042] The switching amplifier circuit 20 is used to amplify and convert the current sampling signal into a voltage, and then output a voltage feedback signal corresponding to the current to the control circuit 60, so that the control circuit 60 can adjust the output voltage Vout of the power supply circuit according to the received voltage feedback signal.

[0043] In this embodiment, the voltage-stabilized sampling circuit 10 can be implemented using discrete components such as capacitors, resistors, voltage-stabilizing diodes, or a voltage-stabilizing source U3; alternatively, it can be implemented using a dedicated voltage chip. The sampling terminal of the voltage-stabilized sampling circuit 10 can be connected to the output terminal of the power supply circuit 50 to sample the output voltage Vout of the power supply circuit in real time and obtain an output voltage sampling signal. The voltage-stabilized sampling circuit 10 can be integrated with preset voltage parameters and a hardware circuit or software algorithm for comparison. When the output voltage sampling signal is obtained, the output voltage sampling signal can be compared with the preset voltage parameters. When the comparison result shows that the voltage value corresponding to the voltage sampling signal is greater than the preset voltage threshold corresponding to the preset voltage parameter, the current sampling signal generation unit or generation program can be driven to output a current sampling signal corresponding to the voltage sampling signal, that is, a current signal corresponding to the output voltage Vout of the power supply circuit. Of course, the preset voltage parameters can also be stored in other functional circuits in the switching power supply, and the voltage-stabilized sampling circuit 10 can be called from other functional circuits during operation. In another embodiment, when the comparison result shows 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-stabilized sampling circuit 10 may further, by operating the corresponding hardware circuit, receive an output current corresponding to the voltage sampling signal from the output terminal of the power supply circuit 50 and output the current sampling signal as the current sampling signal. It is understood that by setting the preset voltage threshold to a relatively low value, the voltage-stabilized sampling circuit 10 may be kept in a triggered state, thereby outputting the current sampling signal in real time.

[0044] The switching amplifier circuit 20 may include a current amplifier circuit and a current-to-voltage conversion circuit. The current amplifier circuit may be implemented based on a switching device having an amplification range, and the current-to-voltage conversion circuit may be implemented using discrete devices such as resistors. The switching amplifier circuit 20 may output the connected current sampling signal to the current amplifier circuit to trigger the switching device in the current amplifier circuit to enter the amplification range, so that the current sampling signal can be amplified and then output to the current-to-voltage conversion circuit for voltage conversion. The current-to-voltage conversion circuit may convert the amplified current sampling signal into a voltage feedback signal corresponding to the voltage signal and output it to the voltage feedback terminal of the control circuit 60. This allows the control circuit 60 to control the operation of the power supply circuit 50 based on the received voltage feedback signal, thereby achieving the effect of stabilizing the output voltage Vout of the power supply circuit. It can also be understood that the control circuit 60 can determine the target value of the output voltage Vout of the power supply circuit at this time, that is, the target output voltage, based on the power supply demand signal output by the device or the voltage output instruction set by the user, and can determine the actual value of the output voltage Vout of the power supply circuit at this time, that is, the 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, and can control the working condition of the power supply circuit 50 according to the voltage difference, so that its output voltage can increase / decrease accordingly by the voltage difference, thereby achieving the dynamic stability of the output voltage Vout of the switching power supply.

[0045] In this way, when the switching power supply sampling circuit of the present invention is working, the switching amplifier circuit 20 replaces the optocoupler U2 to achieve the function of changing the direction of the current. The switching amplifier circuit 20 constructed based on the switching device with an amplification range has its main volume and cost coming from the switching device therein, and the volume and cost of the switching device are much smaller than the optocoupler U2 device. Therefore, the design cost of the switching power supply sampling circuit and its occupied area on the PCB can be reduced, which is beneficial to the layout of the electronic control components thereon and does not require the design of a feedback loop, thereby reducing the difficulty of circuit design.

[0046] Reference Figures 1 to 3In one embodiment of the present invention, the switching amplifier circuit 20 includes: a power input terminal 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 the input terminal of the switching amplifier 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 by the power input terminal Vin, an output terminal of the first switching device T1 and a ground terminal of the control circuit 60 are connected to the same ground; 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 amplifier circuit 20; one terminal of the first capacitor C1 is connected to the second terminal of the first resistor R1, and the other terminal of the first capacitor C1 is grounded.

[0047] In this embodiment, the controlled terminal of the first switch device T1 can be connected to the current sampling signal output by the voltage-stabilizing sampling circuit 10 and can be driven by the current sampling signal to operate in the amplification range. When operating in the amplification range, the first switch device T1 can control the preset power signal of the current signal flowing from its input terminal to its output terminal, and can make the current value of the preset power signal flowing in reach a preset amplification factor compared to the current value of the current sampling signal, thereby amplifying the current sampling signal. The first resistor R1 is a voltage conversion resistor, which is used to convert the preset power signal, which has a preset amplification factor with the current sampling signal, into a corresponding voltage feedback signal, which is then output to the voltage feedback terminal of the control circuit 60. Of course, the power signal can also be a voltage signal. In this case, the input terminal of the first switch device T1 can be connected to the preset power signal of the voltage signal through a voltage-current conversion resistor. The first capacitor C1 is a filter capacitor, which is used to filter the voltage sampling signal output by the first resistor R1 to remove the AC component therein, which is beneficial to improving the signal accuracy of the output voltage sampling signal. It should be noted that the technical solution of the present invention sets the first switch device T1 and the control circuit 60 to be on the same ground, so that the power signal connected to the input end of the first switch device T1 can be output after voltage conversion by the first resistor R1, thereby achieving the effect of current reversal.

[0048] In existing voltage sampling circuits based on optocoupler U2, the design concept is usually to connect the primary and secondary of optocoupler U2 to different grounds to achieve AC isolation. However, in actual applications, it is found that the power supply circuit 50 itself is equipped with isolation circuits such as transformers to reduce the AC noise in its output voltage and prevent the AC noise from being superimposed on its output voltage again through the feedback loop, the sampling loop, and the control circuit 60. In other words, the AC noise in the power supply circuit output voltage Vout is low, and there is no need for further isolation in the sampling loop. The technical solution of the invention overcomes the above design bias. By setting the first switching device T1 and the control circuit 60 to a common ground and providing a first capacitor C1 to filter the AC noise in the voltage feedback signal, a simpler circuit structure can be used to replace the optocoupler U2, which is beneficial for simplifying the circuit structure of the switching amplifier circuit 20 and reducing the PCB area occupied by the switching amplifier circuit 20 and its cost.

[0049] Reference Figures 1 to 3 In one embodiment of the present invention, the first switching device T1 is a transistor or a MOS transistor or a combination thereof.

[0050] In this embodiment, the first switching device T1 can be one or more combinations 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 can be a collector, its controlled terminal can be a base, and its output terminal can be an emitter. In this case, the first switching device T1 and the control circuit 60 can be configured as a common emitter. When the first switching device T1 is a MOS transistor, its input terminal can be a source, its controlled terminal can be a gate, and its output terminal can be a drain. In this case, the first switching device T1 and the control circuit 60 can be configured as a common drain. In another embodiment, the switching amplifier circuit 20 of the present application can 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 configured as a common collector, a common base, a common source, or a common gate. In this way, the first switch device T1 can be implemented with a common power tube, which is beneficial to further reduce the design difficulty and cost of the switching amplifier circuit 20 and is also beneficial to the application of the switching power supply sampling circuit of the present invention in the mass production of switching power supplies.

[0051] Reference Figures 1 to 3 In one embodiment of the present invention, the switching amplifier circuit 20 further includes:

[0052] A switch driving circuit 21 is connected in series between the input terminal of the first switch device T1 and the input terminal of the switch amplifier circuit 20;

[0053] a false trigger protection circuit 22 , one end of which is connected to the input end of the switching amplifier circuit 20 , and the other end of which is grounded; and

[0054] The filter circuit 23 is connected in parallel with the false trigger protection circuit 22 .

[0055] Because the first switching device T1 requires a certain driving voltage, also known as a bias voltage, to operate in the amplification range, the present application provides a switch driving circuit 21, which can be implemented using a fixed-resistance resistor and a programmable logic control relay. The switch driving circuit 21 is used to convert the current sampling signal of the current signal into a voltage signal and then load it to the controlled end of the first switching device T1, thereby driving the first switching device T1 to operate in the amplification range at all times, which is beneficial to improving the operating stability of the switching power supply sampling circuit of the present invention.

[0056] In this embodiment, when the first switch device T1 uses a high-level driven power tube, such as an N-MOS tube and an NPN transistor, the second end of the false trigger protection circuit 22 can be grounded. In this case, the false trigger protection circuit 22 is a pull-down circuit. When the switching power sampling circuit is not working, the voltage level at the controlled end of the first switch device T1 is pulled down to the ground potential, thereby completely shutting off the high-level driven power tube. When the first switch device T1 uses a low-level driven power tube, such as a P-MOS tube and a PNP transistor, the second end of the false trigger protection circuit 22 can be connected to a preset voltage value. In this case, the false trigger protection circuit 22 is a pull-up circuit. When the switching power sampling circuit is not working, the voltage level at the controlled end of the first switch device T1 is pulled up to the preset voltage value, thereby completely shutting off the low-level driven power tube. The filter circuit 23 is used to filter the current sampling signal connected to the input end of the switching amplifier circuit 20 to reduce the AC noise component in the current sampling signal. Figure 4 In the illustrated embodiment, the switch drive circuit 21 and the false trigger protection circuit 22 are implemented using a third resistor R3 and a fourth resistor R4, respectively, and the filter circuit 23 is implemented using a second capacitor C2, further simplifying the circuit structure and reducing costs. This reduces the probability of the first switch device T1 malfunctioning and triggering the voltage regulation of the control circuit 60, thereby further improving the operating stability of the switching power supply sampling circuit of the present invention.

[0057] Reference Figures 1 to 3 In one embodiment of the present invention, the voltage-stabilized 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 end of the power supply circuit 50 via the second resistor R2, and the anode of the first diode D1 is the output end of the voltage-stabilized sampling circuit 10.

[0058] In practical applications, the voltage regulator U3, such as TL431, usually needs to be connected to a reference voltage value so that when the output voltage of the switching power supply after voltage division is connected, the output voltage value is compared with the reference voltage value. When the comparison result shows that the output voltage value after voltage division is greater than the reference voltage value, the impedance value of the voltage regulator U3 is reduced. Therefore, a dedicated circuit needs to be designed in the switching power supply, and even an integrated circuit can be used to provide a reference voltage value for the voltage regulator U3. The technical solution of the present invention constructs a voltage stabilization sampling circuit 10 by using a second resistor R2 and a first diode D1; wherein, the first diode D1 is a voltage regulator diode, and by setting the first diode D1 in reverse, the first diode D1 can be in a reverse conduction state under the action of the power supply circuit output voltage Vout, that is, the preset voltage value at this time is the reverse breakdown voltage of the first diode D1. The technical solution of the present invention utilizes the characteristics that the voltage across the diode is constant in the reverse conduction state, while the current can vary within a large range, so that the dynamic resistance of the second resistor R2 and the first diode D1 constitutes a current sampling circuit to sample the output current of the power supply circuit 50 and output a current sampling signal. In this way, there is no need to use a voltage regulator U3 and design a dedicated circuit or integrated circuit to provide a reference voltage value, which is beneficial to further reduce the circuit cost and simplify the circuit structure.

[0059] Reference Figures 1 to 3 In one embodiment of the present invention, the power supply circuit 50 includes a power tube, and the switching power supply sampling circuit further includes:

[0060] The working current sampling circuit 30 is used to sample the working current of the power tube and output a working current sampling signal to the current feedback terminal of the control circuit 60, so that when the control circuit 60 determines that the working current of the power tube is overcurrent based on the received working current sampling signal, it can control the power supply circuit 50 to stop working.

[0061] In this embodiment, the working current sampling circuit 30 can be implemented by a shunt circuit composed of discrete components such as resistors and capacitors; or it can be implemented by a dedicated current sensor. The detection end of the working current sampling circuit 30 can be connected to the input end of the power tube to sample the current connected to the input end when the power tube is turned on, and output the corresponding working current sampling signal to the current feedback end of the control circuit 60 (i.e. Figure 3 The S / OCP pin of the main control chip U1 is Figure 3In the illustrated embodiment, this terminal is grounded via a fifth resistor. After converting the received operating current sampling signal into a digital signal, the control circuit 60 compares it with a corresponding operating current threshold. When the current value corresponding to the operating current sampling signal exceeds the current value corresponding to the operating current threshold, the control circuit 60 determines that the operating current of the power transistor is overcurrent. The control circuit 60 then controls each power transistor to shut down, causing the power supply circuit 50 to cease operation, thereby providing overcurrent protection, also known as short-circuit protection, for the power transistor. This prevents excessive operating current from causing power transistor failure, thereby improving the functional integration of the switching power supply sampling circuit of the present invention, the operating stability of the power supply circuit 50, and the service life of the switching power supply.

[0062] Reference Figures 1 to 3 In one embodiment of the present invention, the switching power supply sampling circuit further includes:

[0063] The input voltage sampling circuit 40 is used to sample the input voltage of the power supply circuit 50 and output an input voltage sampling signal to the input voltage feedback terminal of the control circuit 60, so that the control circuit 60 can control the power supply circuit 50 to stop working when it determines that the input voltage of the power supply circuit 50 is overvoltage or undervoltage based on the received input voltage sampling signal.

[0064] In this embodiment, the input voltage sampling circuit 40 can be implemented by a voltage divider circuit composed of discrete components such as resistors and capacitors; or it can be implemented by a dedicated voltage sensor. The detection terminal of the input voltage sampling circuit 40 can be connected to the positive and negative input terminals of the power supply circuit 50 to sample the input voltage of the power supply circuit 50 and output the corresponding input voltage sampling signal to the input voltage feedback terminal (i.e., Figure 3 The BR pin of the main control chip U1 is Figure 3In the illustrated embodiment, this terminal is also grounded. After converting the received input voltage sampling signal into a digital signal, the control circuit 60 compares it with the corresponding input voltage threshold. If the voltage value corresponding to the input voltage sampling signal is greater than the voltage value corresponding to the input voltage threshold, the control circuit 60 determines that the input voltage of the power supply circuit 50 is overcurrent. If the voltage value corresponding to the input voltage sampling signal is less than the voltage value corresponding to the input voltage threshold, the control circuit 60 determines that the input voltage of the power supply circuit 50 is undervoltage. When either overvoltage or undervoltage is determined, the control circuit 60 controls the power supply circuit 50 to stop operating, thereby implementing overvoltage and undervoltage protection for the power supply circuit 50. This prevents excessively high or low input voltages from causing damage to components in the power supply circuit 50 due to voltage and current stresses exceeding their normal operating ranges, and also prevents electrical performance indicators from failing to meet requirements. This helps further improve the functional integration of the switching power supply sampling circuit of the present invention, the operating stability of the power supply circuit 50, and further increases the service life of the switching power supply.

[0065] The present invention further provides a switching power supply, which includes a power supply circuit 50, a control circuit 60 and a switching power supply sampling circuit.

[0066] Among them, the power circuit 50 can be constructed with discrete electronic devices such as inductors, power tubes, diodes, etc.; the power tubes can be one or more combinations of IGBTs or MOSFETs. The power circuit 50 may include a rectifier circuit and a voltage conversion circuit, and the power tube can be arranged in the voltage conversion circuit; the input end of the power circuit 50 can be connected to an AC power source such as a mains power grid or a DC power source such as a battery, and can be output to the rectifier circuit for rectification and conversion, so that the connected power signal is rectified and then output to the voltage conversion circuit for corresponding step-up or step-down conversion and then output to the power supply interface of the device. The control circuit 60 can be a microprocessor such as MCU, DSP or FPGA; or, it can also be a dedicated main control chip U1. The control circuit 60 can control the power circuit 50 to convert the connected power signal into the corresponding output voltage and then output it by controlling the on or off logic of each power tube in the power circuit 50. In Figure 3 In the embodiment shown, the two D / ST pins of the main control chip U1 can output control signals for controlling the on / off of corresponding power transistors.

[0067] The specific structure of the switching power supply sampling circuit refers to the above embodiments. Since the present switching power supply adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described in detail here.

[0068] Reference Figures 1 to 3In one embodiment of the present invention, the power output terminal of the control circuit 60 is connected to the switching power sampling circuit for outputting a preset power signal to the switching power sampling circuit.

[0069] In this embodiment, the control circuit 60 may be provided with a voltage conversion circuit for converting the voltage connected to the power supply end into a preset voltage value and then outputting the voltage to the power supply output pin ( Figure 3 The pin of the main control chip U1 (not shown) is output to the input of the first switching device T1, providing a preset power signal for current amplification of the first switching device T1 in the switching power sampling circuit. Of course, in another optional embodiment, the voltage conversion circuit can be provided separately from the control circuit 60 to provide the preset power signal to the switching power sampling circuit under the control of the control circuit 60. In this way, by having the control circuit 60 provide the preset power signal to the switching power sampling circuit, the functional integration of the control circuit 60 is improved, and the PCB area used for the voltage conversion circuit can be reduced, thereby optimizing the layout of the various functional circuits on the PCB.

[0070] The present invention further provides a household appliance including a switching power supply. The specific structure of the switching power supply is as described above. Since the present household appliance adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here. The household appliance may be an air conditioner.

[0071] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A switching power supply sampling circuit, used in a switching power supply, wherein the switching power supply comprises a power supply circuit and a control circuit for controlling the output voltage of the power supply circuit, characterized in that: The switching power supply sampling circuit comprises: a voltage-stabilized sampling circuit, connected to the output terminal of the power supply circuit and triggered to output a current sampling signal when the output voltage of the power supply circuit is greater than a preset voltage; and A switching amplifier circuit, wherein the input end of the switching amplifier circuit is connected to the output end of the voltage stabilization sampling circuit, and the output end of the switching amplifier circuit is used to connect to the voltage feedback end of the control circuit; The switching amplifier circuit is used to amplify and convert the current sampling signal into a voltage, and then output a voltage feedback signal corresponding to the current magnitude 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; The switching amplifier circuit includes a power input terminal and a first switching device. The first switching device has an amplification range. The controlled terminal of the first switching device is connected to the input terminal of the switching amplifier circuit. The input terminal of the first switching device is connected to the power input terminal to receive a preset power signal received by the power input terminal. The output terminal of the first switching device is connected to the same ground as the ground terminal of the control circuit.

2. The switching power supply sampling circuit according to claim 1, wherein: The switching amplifier circuit includes: a first capacitor and a first resistor; the first end of the first resistor is connected to the input end of the first switching device, and the second end of the first resistor is connected to the output end of the switching amplifier circuit; one end of the first capacitor is connected to the second end of the first resistor, and the other end of the first capacitor is grounded.

3. The switching power supply sampling circuit according to claim 2, wherein: The first switching device is a transistor or a MOS transistor or a combination thereof.

4. The switching power supply sampling circuit according to claim 2, wherein: The switching amplifier circuit further includes: a switch driving circuit, connected in series between the input terminal of the first switch device and the input terminal of the switch amplifier circuit; a false trigger protection circuit, one end of which is connected to the input end of the switching amplifier circuit, and the other end of which is grounded; and The filter circuit is arranged in parallel with the false trigger protection circuit.

5. The switching power supply sampling circuit according to claim 1, wherein: The voltage-stabilized sampling circuit includes: a second resistor and a first diode; the cathode of the first diode is connected to the output end of the power supply circuit via the second resistor, and the anode of the first diode is the output end of the voltage-stabilized sampling circuit.

6. The switching power supply sampling circuit according to claim 1, wherein: The power supply circuit includes a power tube, and the switching power supply sampling circuit also includes: The working current sampling circuit is used to sample the working current of the power tube and output a working current sampling signal to the current feedback terminal of the control circuit, so that when the control circuit determines that the working current of the power tube is overcurrent based on the received working current sampling signal, it can control the power supply circuit to stop working.

7. The switching power supply sampling circuit according to claim 1, wherein: The switching power supply sampling circuit further includes: An input voltage sampling circuit is used to sample the input voltage of the power supply circuit and output an input voltage sampling signal to the input voltage feedback terminal of the control circuit, so that the control circuit can control the power supply circuit to stop working when it determines that the input voltage of the power supply circuit is overvoltage or undervoltage based on the received input voltage sampling signal.

8. A switching power supply, characterized in that: The switching power supply comprises: Power supply circuit; a control circuit, configured to control the output voltage of the power supply circuit; and The switching power supply sampling circuit according to any one of claims 1 to 7, wherein the switching power supply sampling circuit is connected to the power supply circuit and the control circuit respectively.

9. The switching power supply according to claim 8, wherein: The power output terminal of the control circuit is connected to the switching power sampling circuit and is used to output a preset power signal to the switching power sampling circuit.

10. A household appliance, characterized in that: The household appliance comprises the switching power supply according to any one of claims 8 to 9.

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