Comparator reference setting method and device, switching power supply and household appliance

Abstract

The embodiment of the present invention discloses a comparator reference setting method and device, a switching power supply and a household appliance, wherein the comparator includes a reference input terminal and a signal input terminal, and the method includes controlling the input value of the reference input terminal to gradually change from a first preset value to a second preset value within a first preset time. Through the above method, the operating voltage of the switch under abnormal working conditions can be effectively reduced, and the reliability of the switch tube can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a comparator reference setting method and device, a switching power supply and a household appliance. Background Art

[0002] In the switching power supply industry, a comparator is usually used to collect the working current of the switch tube. When the current of the switch tube exceeds the set value of the comparator, the switch tube stops working. The technical solution of the prior art is usually to give the comparator a fixed reference, and when the working current of the switch tube exceeds the set reference, the output of the switch tube is turned off.

[0003] However, when an abnormal condition occurs, such as a load short circuit, energy cannot be transferred to the load end, and the current rise rate of the switch tube increases sharply. At this time, according to the original fixed reference, a large voltage stress will be generated on the switch tube, which may cause damage to the switch tube. Summary of the invention

[0004] The embodiments of the present invention aim to provide a comparator reference setting method and device, a switching power supply and a household appliance, which can effectively reduce the operating voltage of the switching tube under abnormal conditions and improve the reliability of the switching tube.

[0005] To achieve the above object, in a first aspect, the present invention provides a reference setting method for a comparator, which is applied to a comparator, wherein the comparator includes a reference input terminal and a signal input terminal, and the method includes:

[0006] Controlling the input value of the reference input terminal to gradually change from a first preset value to a second preset value within a first preset time period, wherein the second preset value is less than the maximum preset input value of the signal input terminal;

[0007] The input value of the reference input terminal is controlled to maintain the second preset value.

[0008] In an optional manner, after the input value of the reference input terminal changes to the second preset value, the method further includes:

[0009] The input value of the reference input terminal is controlled to maintain the second preset value.

[0010] In an optional manner, if the first preset value is less than the second preset value, the step of controlling the input value of the reference input terminal to gradually change from the first preset value to the second preset value within a first preset time period includes:

[0011] The input value of the reference input terminal is controlled to gradually increase from the first preset value to the second preset value within the first preset time period.

[0012] In an optional manner, if the first preset value is greater than the second preset value, the step of controlling the input value of the reference input terminal to gradually change from the first preset value to the second preset value within a first preset time period includes:

[0013] The input value of the reference input terminal is controlled to gradually decrease from the first preset value to the second preset value within the first preset time period.

[0014] In an optional manner, the method further includes:

[0015] When the input value of the signal input terminal is zero, the input value of the reference input terminal is controlled to be the first preset value.

[0016] In a second aspect, the present invention provides a reference setting device for a comparator, which is applied to a comparator, wherein the comparator comprises a reference input terminal and a signal input terminal, and the device comprises:

[0017] The numerical value input unit is used to control the input numerical value of the reference input terminal to gradually change from a first preset numerical value to a second preset numerical value within a first preset time period.

[0018] In a third aspect, the present invention further provides a switching power supply, comprising:

[0019] Switching tube, comparator and control unit;

[0020] The control unit is connected to the switch tube and the comparator respectively, the reference input terminal of the comparator is used to input the reference value output by the control unit, and the signal input terminal of the comparator is used to input the detection value corresponding to the current flowing through the switch tube. The control unit includes:

[0021] At least one processor and a memory in communication with the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute:

[0022] Controlling the reference value to gradually change from the first preset value to the second preset value within the first preset time period;

[0023] Controlling the reference value to maintain the second preset value;

[0024] When the detection value is greater than or equal to the reference value, the switch tube is controlled to be turned off.

[0025] In an optional manner, the processor specifically performs:

[0026] The reference voltage value is controlled to gradually increase from a first preset value to a second preset value within a first preset time period.

[0027] In an optional manner, the processor specifically performs:

[0028] The reference voltage value is controlled to gradually decrease from a first preset value to a second preset value within a first preset time period.

[0029] In an optional manner, the processor is further capable of executing:

[0030] When the detection voltage value is zero, the input value of the reference input terminal is controlled to be a first preset value.

[0031] In a fourth aspect, the present invention further provides a household appliance, comprising a switching power supply as described in any one of the above.

[0032] The beneficial effect of the embodiments of the present invention is: the present invention provides a reference setting method for a comparator, wherein the comparator includes a reference input terminal and a signal input terminal, and the method includes: controlling the input value of the reference input terminal to gradually change from a first preset value to a second preset value within a first preset time period. Therefore, if the input value of the signal input terminal is a detection value corresponding to the current flowing through the switch tube, when an abnormal operating condition occurs during the conduction process of the switch tube, the input value of the signal input terminal will exceed the input value of the reference input terminal, thereby turning off the switch tube. At this time, the operating voltage of the switch tube is relatively low, that is, the operating voltage of the switch tube under abnormal conditions can be effectively reduced, thereby improving the reliability of the switch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0034] Figure 1 It is a circuit structure diagram of a variable frequency microwave power supply in the prior art;

[0035] Figure 2 It is a schematic diagram of the current waveform of the switch tube in the normal working state in the prior art;

[0036] Figure 3 It is a schematic diagram of the current waveform of the switch tube in the prior art under abnormal working conditions;

[0037] Figure 4 It is a schematic diagram of the voltage waveform on the switch tube under abnormal working conditions in the prior art;

[0038] Figure 5A schematic flow chart of a reference setting method for a comparator provided in an embodiment of the present invention.

[0039] Figure 6 A schematic diagram of a current waveform of a switch tube provided by an embodiment of the present invention under normal working conditions;

[0040] Figure 7 A schematic diagram of a current waveform of a switch tube under abnormal working conditions provided by an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of a voltage waveform on a switch tube under abnormal working conditions provided by an embodiment of the present invention;

[0042] Fig. 9 A schematic diagram of the structure of a reference setting device for a comparator provided by an embodiment of the present invention;

[0043] Fig.10 A schematic diagram of the structure of a switching power supply provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Please refer to Figure 1 , Figure 1 The circuit structure of the variable frequency microwave power supply in the field of switching power supply in the prior art. Figure 1 As shown, in this circuit structure, capacitor C1 is a bus filter capacitor, capacitor C2 is a resonant capacitor, Q1 is a switch tube, T1 is a transformer, and the output voltage V0 is supplied to the magnetron after rectification and filtering. Therefore, a comparator is required to collect the working current of the switch tube in real time, and when the current of the switch tube Q1 exceeds the reference setting value of the comparator, it means that the switch tube Q1 is working under abnormal conditions. At this time, the switch tube Q1 needs to be stopped to disconnect the output of the voltage V0, thereby protecting the subsequent circuits or components.

[0046] like Figure 2 As shown, it is assumed that the current reference corresponding to the reference setting value of the comparator is REF, which is a fixed reference value. When the switch tube Q1 works in a normal working state, the current I0 is the actual current value of the switch tube Q1, and the current I0 does not reach the reference setting value REF throughout the whole process. Therefore, the reason why the switch tube Q1 is turned off at t0 is that the conduction time of the switch tube Q1 reaches the set value.

[0047] As Figure 3 shown, the current I1 is the actual current value of the switching transistor Q1. Assume that an abnormal operating condition occurs at this time. For example, when a short circuit occurs at the output end, the energy of the transformer cannot be released, and the primary current rises rapidly. At this time, t1 < t0, that is, the conduction time of the switching transistor Q1 has not reached the set value. Instead, since the current of the switching transistor Q1 has risen to the reference setting value REF, the output signal of the comparator is output to control the switching transistor Q1 to turn off.

[0048] However, as Figure 4 shown, under this abnormal operating condition, because the transformer load is in a short - circuit state, the energy of the transformer cannot be released, and a very large peak voltage will be generated on the switching transistor Q1 (the voltage V1 is the voltage curve on the switching transistor Q1), and the voltage on the switching transistor Q1 will exceed 1400V. Usually, the switching transistor used in the variable - frequency microwave power supply has a rated operating voltage value of 1350V to reduce costs. Obviously, at this time, it exceeds the rated operating voltage of the switching transistor, and there is a risk of over - voltage failure of the switching transistor.

[0049] Based on this, the present application provides a method for setting the reference of a comparator to better prevent the switching transistor from being damaged and improve the reliability of the product. As Figure 5 shown, Figure 5 is a method for setting the reference of a comparator provided by an embodiment of the present application. Among them, the comparator includes a reference input terminal and a signal input terminal. The method includes:

[0050] 501: Control the input value of the reference input terminal to gradually change from a first preset value to a second preset value within a first preset time period.

[0051] Among them, the first preset time period can be set according to the actual application situation and is not limited here. For example, in an embodiment, if the input of the signal input terminal is the detection value corresponding to the current flowing through the switching transistor, at this time, the first preset time period can be set to be less than the conduction time of the switching transistor. Then, within the conduction time period of the switching transistor, when the switching transistor encounters an abnormal operating condition, it can be turned off in time.

[0052] It should be noted that the comparator can be a current comparator or a voltage comparator, which is not limited here.

[0053] Similarly, taking the input of the signal input terminal as the detection value corresponding to the current flowing through the switching transistor as an example. When the comparator selects a current comparator, the input of the reference input terminal of the current comparator is the current reference, and the input of the signal input terminal of the current comparator is the detection value corresponding to the current flowing through the switching transistor (at this time, this detection value can be the current value flowing through the switching transistor).

[0054] When the comparator uses a voltage comparator, the input of the reference input terminal of the voltage comparator is a voltage reference corresponding to the current reference, and the input of the signal input terminal of the voltage comparator is a detection value corresponding to the current flowing through the switch tube (in this case, the detection value is a voltage value corresponding to the current value flowing through the switch tube. For example, the current value flowing through the switch tube can be converted into a corresponding voltage value by setting a resistor)

[0055] At the same time, the first preset value and the second preset value can also be set according to the actual application situation, and there is no limitation here. Moreover, due to the size relationship between the first preset value and the second preset value, different curves in the two cases can be obtained at the reference input terminal. The following embodiments are all explained by taking the current comparator as an example.

[0056] The first situation is: when the first preset value is less than the second preset value, the input value of the reference input terminal is controlled to gradually increase from the first preset value to the second preset value within a first preset time period.

[0057] Furthermore, in one embodiment, when the input value of the reference input terminal has increased to a second preset value, the input value of the reference input terminal is controlled to maintain the second preset value.

[0058] The signal input terminal is used as the input Figure 1 The detection value corresponding to the current of the switch tube Q1 shown is used as an example for explanation.

[0059] like Figure 6 As shown, Figure 6 This is a current waveform diagram when the switch tube Q1 works in a normal working state. When the switch tube Q1 works in a normal working state, the current flowing through the switch tube Q1 is still the current I0, and the current reference corresponding to the input value of the reference input terminal of the comparator at this time is the reference curve REF1.

[0060] At this time, the first preset value corresponds to the current Imin in the reference curve REF1, the first preset time corresponds to the time period (0, t2), and the second preset value corresponds to the current Imax in the reference curve REF1 (the current Imax at this time is greater than the maximum current of the switch tube under normal working conditions). It can be seen that when the input value of the reference input terminal of the comparator gradually increases from the first preset value to the second preset value within the first preset time period, the corresponding reference curve REF1 increases from the current Imin to the current Imax within the time period (0, t2). Moreover, when the input value of the reference input terminal is the second preset value, the input value of the reference input terminal maintains the second preset value, that is, starting from time t2, the reference curve REF1 maintains the current Imax unchanged. Thus, the reference setting process is completed.

[0061] Specifically, when the switch tube is working in a normal working state, at any time during the entire conduction process of the switch tube, the current I0 of the switch tube is less than the reference curve REF1. In this case, the switch tube is turned off at time t0 based on the fact that the conduction time of the switch tube reaches its set value. It can be seen that in practical applications, by setting the current Imin and the current Imax accordingly, the reference curve REF1 will not affect the normal working process of the switch tube.

[0062] Furthermore, when the switch tube is turned off, the input value of the signal input terminal is zero, and the input value of the reference input terminal needs to be controlled to change to the first preset value to prepare for the next switch tube conduction. That is to say, at time t0, the conduction time of the switch tube reaches the preset value, the switch tube is turned off, and the current value flowing through the switch tube is reduced to 0, so that the input value of the signal input terminal of the comparator is zero. Therefore, the corresponding reference curve REF1 should also change to current Imin, that is, the input value of the reference input terminal of the comparator is current Imin, and before the next switch tube is turned on, the input value of the reference input terminal of the comparator remains at current Imin.

[0063] Of course, in another embodiment, the current of the reference curve REF1 can also be set to any value at time t0, such as maintaining the current Imax. However, it must be ensured that the current changes to the current Imin at the next time the switch tube is turned on, that is, the current of the reference curve REF1 corresponding to each time the switch tube is turned on should be the current Imin, that is, at each time the switch tube is turned on, the input value of the reference input terminal of the comparator is the current Imin.

[0064] like Figure 7 As shown, Figure 7 This is a current waveform diagram of the switch tube provided in the present application under abnormal working conditions. At this time, the current I1 is still the actual current value of the switch tube Q1, and the current reference corresponding to the input value of the reference input terminal of the comparator is the reference curve REF1.

[0065] When an abnormal condition occurs, the current of the switch tube rises rapidly, and at time t3, the current value of the switch tube is equal to the current value of the reference curve REF1 (which is less than the current value Imax). At time t3, the input value of the signal input terminal of the comparator reaches the input value of the reference input terminal, which triggers the comparator to output the corresponding control signal to control the switch tube to turn off. It should be understood that at this time, time t3 is less than Figure 3 At the time t1 shown, the comparator can turn off the switch tube in advance.

[0066] Similarly, after the switch tube is turned off, the current value flowing through the switch tube drops to 0, that is, the input value of the signal input terminal is zero, and the input value of the reference input terminal needs to be controlled to change to the first preset value (current Imin at this time) to prepare for the next switch tube to be turned on. Alternatively, as described above, at time t3, the current of the reference curve REF1 can be set to an arbitrary value, such as maintaining the current Imax. However, it must also be ensured that the current changes to the current Imin at the moment of the next switch tube turning on, that is, the current of the reference curve REF1 corresponding to each time the switch tube is turned on should be the current Imin, that is, at each time the switch tube is turned on, the input value of the reference input terminal of the comparator is the current Imin.

[0067] At this time, if Figure 8 As shown in the figure, the voltage that the switch tube withstands under abnormal conditions is also small, only 1200V, which is within the specification range of the switch tube and can prevent the switch tube from being damaged. In addition, this abnormal condition corresponds to Figure 3 It can be seen that, compared with the prior art, the present application can effectively reduce the operating voltage of the switch tube under abnormal conditions and improve the reliability of the switch tube.

[0068] The second situation is: when the first preset value is greater than the second preset value, the input value of the reference input terminal is controlled to gradually decrease from the first preset value to the second preset value within the first preset time period.

[0069] Further, in one embodiment, when the input value of the reference input terminal decreases to a second preset value, the input value of the reference input terminal is controlled to maintain the second preset value. The implementation process of this case is similar to that of the first case, which is within the scope that can be easily understood by those skilled in the art and will not be described in detail here.

[0070] In summary, the reference setting method for a comparator provided in the present application includes: controlling an input value of a reference input terminal to gradually change from a first preset value to a second preset value within a first preset time period.

[0071] Therefore, if the input value of the signal input terminal is the detection value corresponding to the current flowing through the switch tube, when an abnormal operating condition occurs during the conduction process of the switch tube, the input value of the signal input terminal will exceed the input value of the reference input terminal, thereby turning off the switch tube. At this time, the operating voltage of the switch tube is relatively low, which can effectively reduce the operating voltage of the switch tube under abnormal conditions and improve the reliability of the switch tube.

[0072] Fig. 9 1 is a schematic diagram of a reference setting device for a comparator according to an embodiment of the present invention, wherein the comparator includes a reference input terminal and a signal input terminal. Fig. 9As shown, the reference setting device 900 of the comparator includes a value input unit 901. The value input unit 901 is used to control the input value of the reference input terminal to gradually change from a first preset value to a second preset value within a first preset time period.

[0073] Since the device embodiment and the method embodiment are based on the same concept, the content of the device embodiment may refer to the method embodiment on the premise that the contents do not conflict with each other, and will not be repeated here.

[0074] Fig.10 The schematic diagram of the structure of the switching power supply provided by the embodiment of the present invention is shown in FIG. Fig.10 As shown, the switching power supply includes a control unit 1000, a switch tube 1100 and a comparator 1200. The control unit 1000 is connected to the switch tube 1100 and the comparator 1200 respectively. The reference input terminal of the comparator 1200 is used to input the reference value output by the control unit 1000, and the signal input terminal of the comparator 1200 is used to input the detection value corresponding to the current flowing through the switch tube 1100.

[0075] At the same time, the control unit 1000 can also control the switch tube 1100 according to the output result of the comparator 1200. That is, the comparator 1200 outputs a corresponding result according to the magnitude relationship between the reference value output by the control unit 1000 and the detection value corresponding to the current flowing through the switch tube 1100. If the detection value corresponding to the current flowing through the switch tube 1100 is greater than the reference value output by the control unit 1000, the control unit 1000 can control the switch tube 1100 to turn off according to the output result of the comparator.

[0076] If the comparator 1200 is a current comparator, the detection value corresponding to the current flowing through the switch tube 1100 input to the signal input terminal of the comparator 1200 is the current value flowing through the switch tube 1100. If the comparator 1200 is a voltage comparator, the detection value corresponding to the current flowing through the switch tube 1100 input to the signal input terminal of the comparator 1200 is the voltage value corresponding to the current flowing through the switch tube 1100.

[0077] The control unit 1000 may be a microcontroller unit (MCU) or a digital signal processing (DSP) controller.

[0078] The control unit 1000 includes at least one processor 1001 and a memory 1002, wherein the memory 1002 may be built in the control unit 1000 or external to the control unit 1000, and the memory 1002 may also be a remotely set memory connected to the control unit 1000 via a network.

[0079] The memory 1002, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 1002 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the terminal, etc. In addition, the memory 1002 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 1002 may optionally include a memory remotely arranged relative to the processor 1001, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0080] The processor 1001 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 1002, and calling data stored in the memory 1002, thereby monitoring the terminal as a whole, for example, implementing the benchmark setting method of the comparator described in any embodiment of the present invention.

[0081] The processor 1001 may be one or more, Fig.10 In the figure, a processor 1001 is taken as an example. The processor 1001 and the memory 1002 may be connected via a bus or other means. The processor 1001 may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, etc. The processor 205 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0082] An embodiment of the present invention further provides a non-volatile computer storage medium, wherein the computer storage medium stores computer executable instructions, and the computer executable instructions are executed by one or more processors, such as Fig.10 A processor 1001 in the embodiment may enable the one or more processors to execute the comparator benchmark setting method in any of the above method embodiments, for example, to execute the comparator benchmark setting method in any of the above method embodiments, for example, to execute the above described Figure 5 The steps shown in the figure can also be implemented in the attached Fig. 9 The functions of each unit described.

[0083] An embodiment of the present invention further provides a household appliance, which includes the switching power supply in any of the above embodiments.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A comparator reference setting method, characterized in that: The comparator comprises a reference input terminal and a signal input terminal, the signal input terminal inputs a detection value corresponding to a current flowing through the switch tube, and the method comprises: Each time the switch tube switches from off to on, controlling the input value of the reference input terminal to be a first preset value; Controlling the input value of the reference input terminal to gradually increase from the first preset value to the second preset value within a first preset time, wherein the first preset time is less than each turn-on time of the switch tube, the current reference corresponding to the input value of the reference input terminal of the comparator forms a reference curve, and when the switch tube works in a normal working state, at any time during the entire turn-on process of the switch tube, the current of the switch tube is less than the reference curve; When the detection value is greater than or equal to the input value of the reference input terminal, the switch tube is controlled to be turned off.

2. The method according to claim 1, characterized in that After the input value of the reference input terminal changes to the second preset value, the method further includes: The input value of the reference input terminal is controlled to maintain the second preset value.

3. The method according to claim 1, characterized in that The method further comprises: When the input value of the signal input terminal is zero, the input value of the reference input terminal is controlled to be the first preset value.

4. A switching power supply, characterized in that: include: Switching tube, comparator and control unit; The control unit is connected to the switch tube and the comparator respectively, the reference input terminal of the comparator is used to input the reference value output by the control unit, and the signal input terminal of the comparator is used to input the detection value corresponding to the current flowing through the switch tube. The control unit includes: At least one processor and a memory in communication with the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute: Each time the switch tube switches from off to on, controlling the input value of the reference input terminal to be a first preset value; Controlling the reference value to gradually increase from the first preset value to the second preset value within a first preset time, wherein the first preset time is less than each turn-on time of the switch tube, the current reference corresponding to the input value of the reference input terminal of the comparator forms a reference curve, and when the switch tube works in a normal working state, at any time during the entire turn-on process of the switch tube, the current of the switch tube is less than the reference curve; Controlling the reference value to maintain the second preset value; When the detection value is greater than or equal to the reference value, the switch tube is controlled to be turned off.

5. The switching power supply according to claim 4, characterized in that: The processor is also capable of: When the detection voltage value is zero, the input value of the reference input terminal is controlled to be a first preset value.

6. A household appliance, characterized in that: The household appliance comprises a switching power supply as described in any one of claims 4-5.

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