Control device, control method and switching power supply applying control device and control method
By using a control device in the switching power supply, the voltages of the busbar and the transformer primary coil are collected, the voltage between the drain and source of the MOS tube is indirectly measured, and the protection signal is output when the voltage exceeds the threshold, the problem of overvoltage protection of the MOS tube is solved, and the safety and stability of the switching power supply are improved.
Patent Information
- Application Number
- CN202411700032.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-02-28
AI Technical Summary
In the prior art, the voltage measurement accuracy between the drain and source of the MOS tube is insufficient, which affects the effectiveness of overvoltage protection of the MOS tube and may lead to overvoltage breakdown of the MOS tube.
A control device is provided, including a voltage acquisition module, a voltage calculation module and a protection module. By collecting the bus voltage of the switching power supply and the primary coil output voltage of the transformer, the voltage between the drain and source of the field effect tube is indirectly measured, and a protection signal is output when the voltage exceeds the set threshold.
It improves the measurement accuracy of voltage between the drain and source of the MOS tube, achieves more effective overvoltage protection, and enhances the safety and stability of the switching power supply.
Smart Images
Figure CN119543665A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field, and in particular to a control device, a control method and a switching power supply using the same. Background Art
[0002] The switching power supply is an important component of the driver board in the field of power electronics technology. The field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, referred to as MOS tube) is an important component of the switching power supply. Its overcurrent or overvoltage is likely to cause its own explosion and damage, thereby destroying the entire circuit and causing irreversible losses. Therefore, how to detect the current and voltage of the MOS tube and perform overcurrent and overvoltage protection on the MOS tube based on the detection results has become a problem that technicians in this field need to study in depth.
[0003] The voltage between the drain and source of a MOS tube is a key parameter, which is very important for the overvoltage protection of the MOS tube. In the related art, the voltage acquisition circuit is directly connected to the drain and source of the MOS tube to collect the voltage between the drain and source of the MOS tube. Since the ground of the voltage acquisition circuit is connected in parallel with the ground of the MOS tube, when there is a voltage difference between the two grounds, current will flow through the parallel path, affecting the accuracy of the collected voltage value. In turn, the effectiveness of the overvoltage protection of the MOS tube is affected, and the MOS tube may experience overvoltage breakdown. Summary of the invention
[0004] The present disclosure provides a control device, a control method and a switching power supply using the same.
[0005] According to a first aspect of the present disclosure, a control device is provided, which is applied to a switching power supply, wherein the switching power supply includes a transformer and a field effect transistor, and the control device includes: a voltage acquisition module, which is used to acquire the voltage of the bus of the switching power supply and the output voltage of the primary coil of the transformer; a voltage calculation module, which is used to determine the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer; and a protection module, which is used to output a control signal for protecting the field effect transistor when the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold.
[0006] In some embodiments, the voltage acquisition module includes: a first voltage acquisition circuit, connected to the bus through a first resistor, for acquiring the voltage of the bus; a second voltage acquisition circuit, connected to the primary coil of the transformer through a second resistor, for acquiring the output voltage of the primary coil.
[0007] In some embodiments, the first voltage acquisition circuit is connected to the busbar via a first resistor and a first diode.
[0008] In some embodiments, the primary coil of the transformer includes a first winding and a second winding, and the first end of the first winding is connected to the bus, the second end of the first winding is connected to the field effect transistor, the second voltage acquisition circuit is connected to the first end of the second winding through a second resistor and a second diode, and the second end of the second winding is grounded.
[0009] In some embodiments, the voltage operation module includes: a first operation circuit unit, used to calculate the reflected voltage of the field effect tube according to the output voltage of the primary coil of the transformer and the conduction voltage of the second diode; a second operation circuit unit, used to calculate the clamping capacitor voltage of the field effect tube according to the reflected voltage of the field effect tube; and a third operation circuit unit, used to calculate the voltage between the drain and source of the field effect tube according to the clamping capacitor voltage of the field effect tube and the voltage of the bus.
[0010] In some embodiments, the first operation circuit unit is an adder, the second operation circuit unit is a multiplier, and the third operation circuit unit is an adder.
[0011] In some embodiments, the control device also includes a change rate detection module; the change rate detection module is used to detect the current change rate when the field effect tube is turned on; the protection module is also used to output a control signal for protecting the field effect tube when the current change rate is greater than the change rate threshold.
[0012] In some embodiments, the change rate detection module includes: a differential sampling circuit, connected to the source of the field effect tube, for sampling the current change rate when the field effect tube is turned on to obtain a sampling signal; a change rate determination circuit, for detecting the sampling signal and determining the current change rate when the field effect tube is turned on based on the detection result.
[0013] In some embodiments, the differential sampling circuit includes a third resistor, a first capacitor, a fourth resistor, a fifth resistor and an operational amplifier, the negative input terminal of the operational amplifier is connected to the first end of the third resistor and the first end of the capacitor, the second end of the capacitor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded; the positive input terminal of the operational amplifier is connected to the first end of the fifth resistor, and the second end of the fifth resistor is grounded; the output terminal of the operational amplifier is connected to the second end of the third resistor and the input terminal of the change rate determination circuit.
[0014] In some embodiments, the control device also includes a current detection module; the current detection module is used to detect the current when the field effect transistor is turned on; the protection module is also used to output a control signal for protecting the field effect transistor when the current is greater than a current threshold.
[0015] In some embodiments, the control signal for protecting the field effect transistor is a control signal for disconnecting the field effect transistor.
[0016] According to a second aspect of the present disclosure, a switching power supply is provided, comprising: the control device as described above.
[0017] According to a third aspect of the present disclosure, a control method for a switching power supply is provided, comprising: collecting the voltage of a bus of the switching power supply and the output voltage of a primary coil of the transformer; determining the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer; and outputting a control signal for protecting the field effect transistor when the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold.
[0018] In some embodiments, the control method of the switching power supply further includes: detecting the current change rate when the field effect tube is turned on; when the current change rate is greater than a change rate threshold, outputting a control signal for protecting the field effect tube.
[0019] In some embodiments, the control method of the switching power supply further includes: detecting the current when the field effect tube is turned on; and when the current is greater than a current threshold, outputting a control signal for protecting the field effect tube.
[0020] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0022] Figure 1 is a schematic diagram of the structure of a control device according to some embodiments of the present disclosure;
[0023] Figure 2 is a schematic structural diagram of a control device according to other embodiments of the present disclosure;
[0024] Figure 3 is the U during the FET shutdown and cutoff periods according to some embodiments of the present disclosure. DS Schematic diagram of
[0025] Figure 4 is a schematic diagram of a voltage operation circuit according to some embodiments of the present disclosure;
[0026] Figure 5 is a schematic structural diagram of a control device according to some further embodiments of the present disclosure;
[0027] Figure 6 is a schematic structural diagram of a control device according to some other embodiments of the present disclosure;
[0028] Figure 7 is a structural schematic diagram of a differential sampling circuit according to some embodiments of the present disclosure;
[0029] Figure 8 is a schematic diagram of the structure of a protection module according to some embodiments of the present disclosure;
[0030] Fig. 9 is a schematic diagram of the structure of a switching power supply according to some embodiments of the present disclosure;
[0031] Fig.10 It is a flowchart of a control method according to some embodiments of the present disclosure.
[0032] The present disclosure can be more clearly understood from the following detailed description with reference to the accompanying drawings. DETAILED DESCRIPTION
[0033] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.
[0034] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.
[0035] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.
[0036] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.
[0037] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.
[0038] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.
[0039] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.
[0040] In the related art, insufficient voltage measurement accuracy between the drain and source of the MOS tube affects the effectiveness of the MOS tube overvoltage protection, which may cause the MOS tube to experience overvoltage breakdown, thereby affecting the life of the switching power supply.
[0041] In order to solve the above problems, the present disclosure proposes a control device, a control method and a switching power supply using the same, which can improve the measurement accuracy of the voltage between the drain and the source of the MOS tube in the switching power supply, thereby more effectively protecting the MOS tube from overvoltage, making the switching power supply circuit safer and more stable.
[0042] Figure 1 is a schematic diagram of the structure of a control device according to some embodiments of the present disclosure. Figure 1 As shown, the control device 1 is applied to a switching power supply 2. The control device includes a voltage acquisition module 11, a voltage calculation module 12 and a protection module 13, and the switching power supply 2 includes a transformer and a field effect transistor.
[0043] The voltage acquisition module 11 is used to acquire the voltage of the busbar of the switching power supply and the output voltage of the primary coil of the transformer.
[0044] In some examples, the switching power supply may be a flyback switching power supply (or a flyback converter). In addition, the switching power supply may also be other types of power supplies, such as a forward switching power supply (or a forward converter).
[0045] In some examples, the voltage acquisition module 11 includes a first voltage acquisition circuit and a second voltage acquisition circuit. The first voltage acquisition circuit is used to acquire the voltage of the bus connected to the switching power supply. The second voltage acquisition circuit is used to acquire the output voltage of the primary coil of the transformer.
[0046] The voltage calculation module 12 is used to determine the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer.
[0047] In a switching power supply, the field effect tube is connected to the power supply bus of the switching power supply and the primary coil of the transformer. Therefore, the inventor of the present disclosure has come up with the idea that the voltage between the drain and source of the field effect tube can be indirectly measured by collecting the voltage of the bus and the output voltage of the primary coil of the transformer. This indirect measurement method can improve the measurement accuracy of the voltage between the drain and source of the field effect tube compared to the related art of directly measuring the voltage between the drain and source of the field effect tube.
[0048] The protection module 13 is used to output a control signal for protecting the field effect transistor when the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold.
[0049] In some examples, the control signal for protecting the field effect tube includes a control signal for disconnecting the field effect tube. In these examples, the protection module 13 compares the voltage between the drain and source of the field effect tube with the set voltage threshold; if the comparison result is that the voltage between the drain and source of the field effect tube is greater than the set voltage threshold, then the control signal for turning off the field effect tube is output; otherwise, the control signal is not output. In a specific implementation, the protection module 13 can also combine the overvoltage protection logic with other protection logics (such as overcurrent protection logic). For example, when the triggering conditions of the overvoltage protection or the triggering conditions of the overcurrent protection are met, the control signal for protecting the field effect tube is output; otherwise, the control signal is not output.
[0050] In addition, in a specific implementation, the control signal used to protect the field effect transistor may also be other signals used to alleviate or prompt abnormal situations.
[0051] In the embodiments of the present disclosure, the above device can improve the measurement accuracy of the voltage between the drain and source of the MOS tube in the switching power supply, thereby more effectively protecting the MOS tube from overvoltage, making the switching power supply circuit safer and more stable.
[0052] Figure 2 Schematic diagram of the structure of the control device according to some other embodiments of the present disclosure. Figure 2 As shown, in these embodiments, the switching power supply is a flyback switching power supply, and the control device 1 is Figure 1 Further refinements and improvements have been made based on the structure shown. Figure 2 The control device 1 will be described in detail.
[0053] Specifically, the voltage acquisition module 11 of the control device 1 includes a first voltage acquisition circuit 111 and a second voltage acquisition circuit 112 .
[0054] In some examples, the first voltage acquisition circuit 111 includes a first resistor R 1The first voltage acquisition circuit 111 is connected to the first resistor R 1 The second voltage collection circuit 112 is connected to the bus and is used to collect the voltage of the bus. Further, in the above example, the second voltage collection circuit 112 includes a second resistor R 2 The second voltage acquisition circuit 112 is connected to the primary coil of the transformer through the second resistor, and is used to acquire the output voltage of the primary coil. By setting the first resistor in the first voltage acquisition circuit and the second resistor in the second voltage acquisition circuit, it is helpful to adjust the voltage measurement range of the control device and improve the measurement flexibility and safety of the control device.
[0055] In other examples, such as Figure 2 As shown, the first voltage acquisition circuit 111 includes a first resistor R 1 and the first diode VD 1 The first voltage acquisition circuit 111 is connected to the first resistor R 1 And the first diode VD 1 The second voltage acquisition circuit 112 is connected to the bus and is used to collect the voltage of the bus. Further, in the above example, the second voltage acquisition circuit 112 includes a second resistor R 2 and the second diode VD 2 The second voltage collection circuit 112 is connected to the second resistor R 2 And the second diode VD 2 Connected to the primary coil of the transformer 21. Specifically, the primary coil includes a first winding and a second winding. Among them, the first end of the first winding is connected to the bus, and the second end of the first winding is connected to the field effect tube. The second voltage acquisition circuit is connected to the first end of the second winding through the second resistor and the second diode, and the second end of the second winding is grounded. By setting the first resistor and the first diode in the first voltage acquisition circuit, and setting the second resistor and the second diode in the second voltage acquisition circuit, it is not only convenient to adjust the voltage measurement range of the control device, but also can further improve the measurement safety with the help of the unidirectional conduction performance of the diode. Further, by connecting the second voltage acquisition circuit to the second winding of the primary coil, it is convenient to accurately measure the output voltage of the primary coil.
[0056] The voltage operation module 12 includes a first operation circuit unit, a second operation circuit unit and a third operation circuit unit. The first operation circuit unit is used to calculate the reflected voltage of the field effect tube according to the output voltage of the primary coil of the transformer and the conduction voltage of the second diode; the second operation circuit unit is used to calculate the clamping capacitor voltage of the field effect tube according to the reflected voltage of the field effect tube; the third operation circuit unit is used to calculate the voltage between the drain and the source of the field effect tube according to the clamping capacitor voltage of the field effect tube and the voltage of the bus.
[0057] In the embodiment of the present disclosure, by calculating the voltage between the drain and source of the field effect transistor based on the above method by the first to third operation circuit units, the calculation accuracy of the voltage between the drain and source of the field effect transistor can be further improved, which in turn helps to further improve the effectiveness of overvoltage protection.
[0058] In some examples, the voltage calculation module 12 calculates the voltage between the drain and the source of the effect tube according to the following formula:
[0059] U DSMAX =U IN +U Clamp =U IN +1.5n(U O +U D )
[0060] Among them, U DSMAX is the voltage between the drain and source of the field effect tube, U IN is the bus voltage read at the HV pin, U Clamp is the clamping capacitor voltage of the field effect tube, n is the turns ratio of the first winding to the second winding in the primary coil, Uo is the output voltage of the primary coil read at the VCC pin, U D The second diode VD 2 The on-state voltage, n(Uo+U D ) is the reflected voltage of the field effect tube.
[0061] The following is an explanation of the derivation process of the above formula. First, the turns ratio of the primary coil is N P :N A =n:1, and
[0062]
[0063] Among them, U OR is the reflected voltage, Uo is the voltage read from the VCC pin, and U D The second diode VD 2 The on-state voltage.
[0064] In engineering design, the U of the switching power supply Clamp with U OR satisfy:
[0065] U Clamp =1.5×U OR
[0066] During the period when the field effect tube is turned off and cut off, the voltage between the drain and the source satisfies the following Figure 3 The relationships shown are:
[0067] U DSMAX =UIN +U Clamp
[0068] Furthermore, we can conclude that U DSMAX =U IN +1.5n(U O +U D ).
[0069] Figure 4 A structural diagram of an exemplary voltage operation circuit is given. Figure 4 As shown, the first operation circuit unit 121 is an adder, the second operation circuit unit 122 is a multiplier, and the third operation circuit unit 123 is an adder.
[0070] The first operation circuit unit 121 includes a resistor R 11 , resistor R 12 , resistor R 13 , resistor R 14 , and a comparator. Among them, the resistor R 11 With resistor R 12 The resistance value is equal, the resistance R 13 With resistor R 14 The resistance values are equal.
[0071] The second operation circuit unit 122 is a multiplier, and a coefficient k thereof is set to 1.5.
[0072] The third operation circuit unit 123 includes a resistor R 15 , resistor R 16 , resistor R 17 , resistor R 18 , and a comparator. Among them, the resistor R 15 With resistor R 16 The resistance value is equal, the resistance R 17 With resistor R 18 The resistance values are equal.
[0073] In the embodiment of the present disclosure, by Figure 4 The voltage operation circuit in can realize the above formula U DSMAX =U IN +1.5n(U O +U D ) operation, and then the voltage between the drain and source of the field effect tube can be obtained. In this way, the voltage between the drain and source of the field effect tube can be determined more accurately.
[0074] Figure 5 is a schematic diagram of the structure of a control device according to some further embodiments of the present disclosure. Figure 5 As shown, the control device 1 includes Figure 1In addition to the voltage acquisition module 11, the voltage calculation module 12 and the protection module 13, the voltage acquisition module 11 also includes a change rate detection module 14 and a current detection module 15. Figure 5 and Figure 1 The differences are explained below.
[0075] The change rate detection module 14 is used to detect the current change rate when the field effect tube is turned on.
[0076] The current detection module 15 is used to detect the current when the field effect tube is turned on.
[0077] The protection module 13 is also used to output a control signal for protecting the field effect transistor when the current change rate is greater than the change rate threshold. Further, the protection module 13 can also be used to output a control signal for protecting the field effect transistor when the current when the field effect transistor is turned on is greater than the current threshold. The control signal for protecting the field effect transistor can be a control signal for disconnecting the field effect transistor, or other control signals for alleviating or indicating abnormal change rate.
[0078] It should be noted that the embodiment of the present disclosure is described by taking the control device including the change rate detection module 14 and the current detection module 15 as an example. In specific implementation, the control device may also include one of the change rate detection module 14 and the current detection module 15.
[0079] In the embodiment of the present disclosure, by detecting the current change rate when the field effect tube is turned on and outputting a protection signal when the change rate is abnormal, the probability of the field effect tube being damaged due to excessive current change rate can be reduced, and the safety and reliability of the switching power supply can be improved. Further, by detecting the current when the field effect tube is turned on and outputting a protection signal when the current is abnormal, the probability of the field effect tube being damaged due to excessive current can be reduced, and the safety and reliability of the switching power supply can be further improved.
[0080] Figure 6 is a schematic diagram of the structure of a control device according to some other embodiments of the present disclosure. Figure 6 As shown, in these embodiments, the switching power supply is a flyback switching power supply, and the control device 1 is Figure 2 , Figure 5 The structure shown in the figure is further refined and improved. Figure 6 and Figure 2 , Figure 5 The differences are explained in detail.
[0081] The rate of change detection module 14 of the control device 1 includes a differential sampling circuit 141 and a rate of change determination unit. Among them, the differential sampling circuit 141 is connected to the source of the field effect tube, and is used to sample the current change rate when the field effect tube is turned on to obtain a sampling signal; the rate of change determination circuit 142 is used to detect the sampling signal and determine the current change rate when the field effect tube is turned on according to the detection result. In the embodiment of the present disclosure, by adopting a differential sampling circuit, not only can the change of current be detected with higher accuracy and better common mode rejection ratio, the current change rate can be collected, the sensitivity of current change rate detection can be improved, and then the effectiveness of overcurrent protection can be improved, but also by changing variable components, adjusting gain and other characteristics, the detection circuit can be adapted to various processing requirements.
[0082] In some embodiments, the differential sampling circuit adopts Figure 7 The structure shown. Figure 7 As shown, the differential sampling circuit 141 includes a third resistor R 3 , the first capacitor C 1 , the fourth resistor R 4 , the fifth resistor R 5 And operational amplifier A. The negative input terminal (i.e., the inverting input terminal) of the operational amplifier A is connected to the third resistor R 3 The first end of the capacitor C 1 The first end of the capacitor C 1 The second end of the fourth resistor R 4 The first end of the fourth resistor R 4 The second end of the operational amplifier A is grounded; the positive input end (i.e., the non-inverting input end) of the operational amplifier A is connected to the fifth resistor R 5 The first end of the fifth resistor R 5 The second end of the operational amplifier A is grounded; the output end of the operational amplifier A is connected to the third resistor R 3 The second end of the circuit 140 is connected to the input end of the change rate determination circuit 142.
[0083] The principle of the differential sampling circuit is explained below. Figure 7 In the circuit shown, the virtual short circuit gives:
[0084] U + =U - =OV
[0085] Among them, ΔU + With ΔU - is the point position of the two input terminals of the comparator. Also know:
[0086] U IN =i·R 4
[0087] Among them, R 4is the sampling resistor of the differential sampling circuit. Then, according to the virtual circuit, we have:
[0088]
[0089] Then there are:
[0090]
[0091] Finally, the relationship between the voltage signal collected by the chip and the current change rate is:
[0092]
[0093] It can be seen that the voltage signal corresponding to the current change rate when the field effect tube is turned on can be collected through the differential sampling circuit. Furthermore, it can be used for overcurrent protection.
[0094] In the embodiment of the present disclosure, by adopting Figure 7 The differential sampling circuit of the structure shown can accurately measure the current change rate when the field effect tube is turned on with a relatively simple structure.
[0095] The protection module 13 is used to protect the field effect tube from overvoltage and overcurrent. In some examples, the protection module 13 adopts Figure 8 The structure shown. Figure 8 As shown, the protection module includes 3 comparators and 1 AND gate. Among them, the 3 comparators are used to compare whether the voltage between the drain and source of the field effect tube is greater than the voltage threshold Vref1, whether the current change rate when the field effect tube is turned on is greater than the change rate threshold Vref2, and whether the current when the field effect tube is turned on is greater than the current threshold Iref1. The above 3 comparators are connected to an AND gate. When any input signal is greater than the corresponding set threshold, the corresponding comparator outputs a low-level signal, and then the AND gate outputs a low level, and then a control instruction is issued to turn off the MOS tube, so as to achieve the effect of overvoltage protection and overcurrent protection for the MOS tube.
[0096] It should be noted that in these embodiments of the present disclosure, the control device is implemented by a driver chip and a portion of the circuit outside the driver chip (such as a differential sampling circuit). In specific implementation, the driver chip and these portion of the circuit outside the driver chip can also be integrated into one chip.
[0097] In the disclosed embodiment, the above control device can more effectively perform overcurrent and overvoltage protection on the field effect transistor in the switching power supply, thereby improving the safety and reliability of the switching power supply.
[0098] Fig. 9 is a schematic diagram of the structure of a switching power supply according to some embodiments of the present disclosure. Fig. 9As shown, the switching power supply 90 includes the control device 1 as described above.
[0099] In the embodiment of the present disclosure, by providing the above control device in the switching power supply, the safety and reliability of the switching power supply can be improved.
[0100] Fig.10 FIG. 1 is a flow chart of a control method according to some embodiments of the present disclosure. Fig.10 As shown, the control method is applied to the switching power supply as mentioned above, including steps S101 to S103.
[0101] Step S101: collecting the voltage of the busbar of the switching power supply and the output voltage of the primary coil of the transformer.
[0102] Regarding how to specifically collect the voltage of the busbar of the switching power supply and the output voltage of the primary coil of the transformer, reference may be made to the relevant description of the aforementioned embodiment.
[0103] Step S102: Determine the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer.
[0104] Regarding how to determine the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer, reference may be made to the relevant description of the above-mentioned embodiment.
[0105] Step S103: when the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold, output a control signal for protecting the field effect transistor.
[0106] In the embodiment of the present disclosure, through steps S101 to S103, the measurement accuracy of the voltage between the drain and the source of the MOS tube in the switching power supply can be improved, thereby more effectively protecting the MOS tube from overvoltage, making the switching power supply circuit safer and more stable.
[0107] In some embodiments, the control method further includes: detecting the current change rate when the field effect tube is turned on; and outputting a control signal for protecting the field effect tube when the current change rate is greater than a change rate threshold. By detecting the current change rate when the field effect tube is turned on and outputting a protection signal when the change rate is abnormal, the probability of the field effect tube being damaged due to an excessively large current change rate can be reduced, thereby improving the safety and reliability of the switching power supply.
[0108] In some embodiments, the control method further includes: detecting the current when the field effect tube is turned on; when the current is greater than the current threshold, outputting a control signal for protecting the field effect tube. By detecting the current when the field effect tube is turned on and outputting a protection signal when the current is abnormal, the probability of the field effect tube being damaged due to excessive current can be reduced, further improving the safety and reliability of the switching power supply.
[0109] In the embodiments of the present disclosure, through the above control method, the field effect transistor in the switching power supply can be more effectively protected from overcurrent and overvoltage, thereby improving the safety and reliability of the switching power supply. Here, various aspects of the present disclosure are described with reference to the flowcharts and / or block diagrams of the methods, devices, and computer program products according to the embodiments of the present disclosure. It should be understood that each frame of the flowchart and / or block diagram and the combination of frames can be implemented by computer-readable program instructions.
[0110] These computer-readable program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer or other programmable device to produce a machine, so that the processor executes the instructions to produce means for implementing the functions specified in one or more blocks in the flowchart and / or block diagram.
[0111] These computer-readable program instructions may also be stored in a computer-readable memory, which cause the computer to work in a specific manner to produce an article of manufacture, including instructions for implementing the functions specified in one or more blocks in the flowchart and / or block diagram.
[0112] The present disclosure can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects.
[0113] So far, the control device, control method and switching power supply using the same according to the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed herein.
Claims
1. A control device, applied to a switching power supply, the switching power supply comprising a transformer and a field effect transistor, the control device comprising: A voltage acquisition module, used to acquire the voltage of the busbar of the switching power supply and the output voltage of the primary coil of the transformer; A voltage calculation module, used to determine the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer; The protection module is used to output a control signal for protecting the field effect transistor when the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold.
2. The control device according to claim 1, wherein: The voltage acquisition module comprises: A first voltage collection circuit is connected to the bus through a first resistor and is used to collect the voltage of the bus; The second voltage collection circuit is connected to the primary coil of the transformer through a second resistor and is used for collecting the output voltage of the primary coil.
3. The control device according to claim 2, wherein: The first voltage collection circuit is connected to the busbar via a first resistor and a first diode.
4. The control device according to claim 2, wherein: The primary coil of the transformer includes a first winding and a second winding, and the first end of the first winding is connected to the bus, and the second end of the first winding is connected to the field effect transistor. The second voltage acquisition circuit is connected to the first end of the second winding through a second resistor and a second diode, and the second end of the second winding is grounded.
5. The control device according to claim 4, wherein: The voltage operation module comprises: A first operation circuit unit, used for calculating the reflected voltage of the field effect tube according to the output voltage of the primary coil of the transformer and the conduction voltage of the second diode; A second operation circuit unit, used for calculating the clamping capacitor voltage of the field effect tube according to the reflected voltage of the field effect tube; The third operation circuit unit is used to calculate the voltage between the drain and the source of the field effect tube according to the clamping capacitor voltage of the field effect tube and the voltage of the bus.
6. The control device according to claim 5, wherein: The first operation circuit unit is an adder, the second operation circuit unit is a multiplier, and the third operation circuit unit is an adder.
7. The control device according to any one of claims 1 to 6, wherein: The control device also includes a rate of change detection module; A change rate detection module, used to detect the current change rate when the field effect tube is turned on; The protection module is further configured to output a control signal for protecting the field effect transistor when the current change rate is greater than a change rate threshold.
8. The control device according to claim 7, wherein: The change rate detection module comprises: A differential sampling circuit is connected to the source of the field effect tube and is used to sample the current change rate when the field effect tube is turned on to obtain a sampling signal; The change rate determination circuit is used to detect the sampling signal and determine the current change rate when the field effect tube is turned on according to the detection result.
9. The control device according to claim 8, wherein: The differential sampling circuit includes a third resistor, a first capacitor, a fourth resistor, a fifth resistor and an operational amplifier, wherein the negative input terminal of the operational amplifier is connected to the first end of the third resistor and the first end of the capacitor, the second end of the capacitor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded; the positive input terminal of the operational amplifier is connected to the first end of the fifth resistor, and the second end of the fifth resistor is grounded; the output terminal of the operational amplifier is connected to the second end of the third resistor and the input terminal of the change rate determination circuit.
10. The control device according to claim 7, wherein: The control device also includes a current detection module; The current detection module is used to detect the current when the field effect tube is turned on; The protection module is further configured to output a control signal for protecting the field effect transistor when the current is greater than a current threshold.
11. The control device according to claim 10, wherein: The control signal for protecting the field effect tube is a control signal for disconnecting the field effect tube.
12. A switching power supply comprising: A control device as claimed in any one of claims 1 to 11.
13. A method for controlling a switching power supply, comprising: Collecting the voltage of the busbar of the switching power supply and the output voltage of the primary coil of the transformer; Determining the voltage between the drain and the source of the field effect transistor according to the voltage of the bus and the output voltage of the primary coil of the transformer; When the voltage between the drain and the source of the field effect transistor is greater than a set voltage threshold, a control signal for protecting the field effect transistor is output.
14. The control method of the switching power supply according to claim 13, further comprising: Detecting the current change rate when the field effect tube is turned on; When the current change rate is greater than the change rate threshold, a control signal for protecting the field effect transistor is output.
15. The control method of the switching power supply according to claim 13, further comprising: Detecting the current when the field effect tube is turned on; When the current is greater than a current threshold, a control signal for protecting the field effect transistor is output.