Switching power supply circuit control method and system and electronic equipment

Abstract

The invention discloses a switching power supply circuit control method and system and electronic equipment, and relates to the technical field of switching power supply driving. The control method comprises the steps of collecting current output by a ZCD pin of the switching power supply circuit, and generating reduction voltage of drain voltage of a primary power tube in the switching power supply circuit; comparing the reduction voltage with a switching threshold voltage to obtain strong and weak driving switching signals; and generating a current source control signal according to the strong and weak driving switching signal and the PWM control signal. According to the invention, accurate monitoring of strong and weak driving switching points in each period is realized by detecting the current of the ZCD pin of the switching power supply circuit, so that the current source control signal is generated to switch and control the magnitude of the charging current of the grid electrode of the power tube, and segmented driving of the switching power supply circuit is realized.

Description

Technical Field

[0001] The present application relates to the field of switching power supply driving technology, and in particular to a switching power supply circuit control method, system and electronic equipment. Background Art

[0002] In the switching power supply circuit, the power tube is a key device for energy transmission, and its switch control method has a great impact on the performance and reliability of the switching power supply circuit. If the charging current of the power tube is too large and the opening speed is too fast, it will cause a large voltage spike of the power tube; if the charging current is too small, the opening speed of the power controllable switch will slow down, which will cause large switching losses and conduction losses, resulting in reduced system efficiency. Usually, the switching power supply circuit will adopt a segmented drive method to optimize the voltage spike and system efficiency at the same time. That is, when the power tube is turned on, a weak drive with a small current is used before the end of the Miller platform, and a strong drive with a large current is used after the end of the Miller platform. For the flyback topology in the switching power supply circuit, the drain of the primary power tube is a high-voltage node of about 600V, and the threshold voltage of different power tubes will vary between 1.5V and 4V, which brings challenges to the detection of the power tube opening state and the strong and weak drive switching points. Summary of the invention

[0003] The purpose of the present application is to provide a switching power supply circuit control method, system and electronic device to achieve accurate monitoring of the strong and weak drive switching points, and then generate a current source control signal to switch and control the size of the power tube gate charging current to achieve segmented driving of the switching power supply circuit.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] In a first aspect, the present application provides a switching power supply circuit control method, the switching power supply circuit control method comprising:

[0006] The current outputted from the ZCD pin of the switching power supply circuit is collected to generate a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit;

[0007] Comparing the restoration voltage with the switching threshold voltage to obtain a strong or weak driving switching signal;

[0008] A current source control signal is generated according to the strong and weak drive switching signal and the PWM control signal; the current source control signal is used to control the gate charging current of the primary power tube in the switching power supply circuit.

[0009] In a second aspect, the present application provides a switching power supply circuit control system, wherein the switching power supply circuit control system applies the above-mentioned switching power supply circuit control method, and the power tube gate control system includes: a segmented drive detection circuit, a segmented drive logic control circuit and a drive signal generation circuit;

[0010] The segmented drive detection circuit is connected to the ZCD pin of the switching power supply circuit, and the segmented drive detection circuit is used to collect the current output by the ZCD pin of the switching power supply circuit, generate a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit, and compare the restoration voltage with the switching threshold voltage to obtain a strong or weak drive switching signal;

[0011] The segmented drive logic control circuit is used to generate a current source control signal according to the strong and weak drive switching signal and the PWM control signal;

[0012] The drive signal generating circuit is used to generate a gate charging current according to the current source control signal and the PWM control signal; the gate charging current is used to control the primary power tube in the switching power supply circuit.

[0013] In a third aspect, the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned switching power supply circuit control method when executing the program.

[0014] According to the specific embodiments provided in this application, this application has the following technical effects.

[0015] The present application provides a switching power supply circuit control method, system and electronic device. The present application detects the ZCD pin current of the switching power supply circuit to accurately monitor the strong and weak drive switching points in each cycle, and then generates a current source control signal to switch and control the size of the power tube gate charging current, thereby realizing segmented driving of the switching power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A circuit schematic diagram of ZCD pin current detection provided in an embodiment of the present application.

[0018] Figure 2 A circuit schematic diagram of a switching power supply circuit control system provided in one embodiment of the present application.

[0019] Figure 3 A circuit schematic diagram of ZCD pin current detection provided in an embodiment of the present application.

[0020] Figure 4 A circuit schematic diagram of a segmented drive detection circuit provided in one embodiment of the present application.

[0021] Figure 5 A fixed Vset segmented driving waveform diagram provided in an embodiment of the present application.

[0022] Figure 6 A circuit schematic diagram of a first VSET generating circuit provided in an embodiment of the present application.

[0023] Figure 7 A segmented driving waveform of AC high voltage input and AC low voltage input provided by an embodiment of the present application.

[0024] Figure 8 A schematic diagram of a second VSET generating circuit provided in an embodiment of the present application

[0025] Fig. 9 A sample-and-hold Vset waveform diagram provided in one embodiment of the present application.

[0026] Fig.10 This is a waveform diagram of the voltage and current changes during the power tube startup process provided by an embodiment of the present application.

[0027] Fig.11 A circuit schematic diagram of a segmented drive logic control circuit provided in one embodiment of the present application.

[0028] Fig.12 A circuit schematic diagram of another segmented drive logic control circuit provided in an embodiment of the present application.

[0029] Fig.13 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0032] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0033] The switching power supply circuit control method, switching power supply circuit control system and electronic device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings through specific embodiments and their application scenarios.

[0034] The switching power supply circuit control method may be applied to a terminal, and may be specifically executed by hardware or software in the terminal.

[0035] The terminal includes, but is not limited to, a portable communication device such as a mobile phone or tablet computer with a touch-sensitive surface (e.g., a touch screen display and / or a touch pad). It should also be understood that in some embodiments, the terminal may not be a portable communication device, but a desktop computer with a touch-sensitive surface (e.g., a touch screen display and / or a touch pad).

[0036] In the following various embodiments, a terminal including a display and a touch-sensitive surface is described. However, it should be understood that the terminal may include one or more other physical user interface devices such as a physical keyboard, a mouse and a joystick.

[0037] The embodiment of the present application proposes a switching power supply circuit control method, system and electronic device, which determines the drain voltage information of the power tube by detecting the current of the ZCD pin, and then adjusts the magnitude of the gate charging current of the power tube to achieve the effect of strong drive and weak drive segmented drive in each cycle. It effectively reduces the voltage spike stress, ensures the safety and reliability of the system, and improves the overall work efficiency.

[0038] In an exemplary embodiment, a switching power supply circuit control method is provided. The executor of the switching power supply circuit control method may be a switching power supply circuit, or may be an electronic device electrically connected to the switching power supply circuit, or may be a functional module or functional entity in the electronic device that can implement the switching power supply circuit control method, or may also be a user terminal communicatively connected to the switching power supply circuit, including but not limited to a mobile terminal and a non-mobile terminal.

[0039] like Figure 1As shown, the switching power supply circuit control method includes the following steps 101 to 103.

[0040] It should be noted that the switching power supply circuit control method can be applied to the switching power supply circuit. The switching power supply circuit can be a flyback switching power supply. The switching power supply is a high-frequency electric energy conversion device and a type of power supply. The switching power supply can be applied to fields such as fast charging, adapters and chargers. In practical applications, in order to reduce switching losses and improve conversion efficiency, the switching power supply circuit can adopt a quasi-resonant (QR) control method.

[0041] Step 101, collecting the current outputted by the ZCD pin of the switching power supply circuit, and generating a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit.

[0042] In this step, the switching power supply circuit includes a primary power tube. The working state of the primary power tube may include being on or off. The primary power tube includes a gate, a source, and a drain. When the primary power tube is on, the working parameters of the switching power supply circuit are obtained, and the working parameters at least include the drain voltage of the primary power tube.

[0043] In the embodiment of the present application, by collecting the current output by the ZCD pin of the switching power supply circuit, and then indirectly obtaining the drain voltage of the primary power tube in the switching power supply circuit, it is possible to accurately monitor the strong and weak drive switching points, thereby improving the control accuracy.

[0044] Step 102: Compare the restoration voltage with the switching threshold voltage to obtain a strong or weak driving switching signal.

[0045] The switching threshold voltage in this step can be obtained in different ways, mainly divided into the following three methods:

[0046] The first type: the switching threshold voltage is a fixed voltage value.

[0047] The second type: the switching threshold voltage is determined based on the voltage of the input power supply of the transformer in the switching power supply circuit: when the voltage of the input power supply is large, a larger switching threshold voltage is generated, otherwise a smaller switching threshold voltage is generated.

[0048] The third type: the switching threshold voltage is determined based on the restoration voltage: when the restoration voltage is larger, a larger switching threshold voltage is generated, otherwise a smaller switching threshold voltage is generated.

[0049] The embodiments of the present application do not limit any specific acquisition method, and those skilled in the art recognize that the method can be selected according to the needs.

[0050] Step 103: Generate a current source control signal according to the strong and weak drive switching signal and the PWM control signal.

[0051] The current source control signal in this step is mainly used to control the gate charging current of the primary power tube in the switching power supply circuit. Any driving signal generating circuit can be controlled, and the driving signal generating circuit signal can output different currents under the control of the current source control signal. Specifically, when the strong and weak driving switching signal indicates that the switching power supply circuit needs to be strongly driven, and the PWM control signal is at a high level, a first current source control signal is generated; the first current source control signal is used to charge the primary power tube in the control switching power supply circuit in the form of strong driving; when the strong and weak driving switching signal indicates that the switching power supply circuit needs to be weakly driven, and the PWM control signal is at a high level, a second current source control signal is generated; the second current source control signal is used to charge the primary power tube in the control switching power supply circuit in the form of weak driving; when the PWM control signal is at a low level, a third current source control signal is generated; the third current source control signal is used to draw power from the primary power tube in the control switching power supply circuit.

[0052] In the method embodiments of the present application, there is no limitation on the circuit structure, and any circuit structure or controller that can implement the above steps is within the protection scope of the present application.

[0053] In an exemplary embodiment, in order to implement the above method embodiment, a switching power supply circuit control system is provided, such as Figure 2 As shown, the switching power supply circuit control system includes: a segmented drive detection circuit, a segmented drive logic control circuit and a drive signal generating circuit; the segmented drive detection circuit is connected to the ZCD pin of the switching power supply circuit and the segmented drive logic control circuit respectively, the segmented drive detection circuit is used to collect the current output by the ZCD pin of the switching power supply circuit, generate a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit, and compare the restoration voltage with the switching threshold voltage to obtain a strong or weak drive switching signal; the segmented drive logic control circuit is connected to the drive signal generating circuit, the segmented drive logic control circuit is used to generate a current source control signal according to the strong or weak drive switching signal and the PWM control signal; the drive signal generating circuit is used to generate a gate charging current according to the current source control signal; the gate charging current is used to control the primary power tube in the switching power supply circuit.

[0054] like Figure 3 As shown, a schematic diagram of a segmented drive detection circuit and a primary power tube gate control circuit is set up in a switching power supply circuit using a flyback converter.

[0055] The switching power supply circuit includes an EMI (Electro Magnetic Interference) filter, a rectifier bridge u4, a capacitor C3, a resistor Rs, a capacitor C2, a transformer T1, a diode D2, a primary power tube Q1, an inductor current detection resistor R2, a resistor Rzh, a resistor Rzl, a primary PWM controller U1, a secondary synchronous rectifier U2, a secondary synchronous rectifier power tube Q2, a TL431, an optical coupler U3, a voltage divider resistor R6 and a voltage divider resistor R7, a resistor R5, a capacitor C4, and a capacitor C5. Among them, the TL431, the optical coupler U3, the voltage divider resistor R6, and the voltage divider resistor R7 form a feedback loop.

[0056] Among them, the transformer T1 includes a primary winding Np, a secondary winding Ns, and an auxiliary winding Na. p 、N s 、N a are the turns of the primary winding, secondary winding and auxiliary winding of the transformer respectively. The relationship between the voltage and current between the windings of transformer T1 is as follows:

[0057] When the primary power tube is turned on, the voltage difference of the primary winding Np is V bulk -V dp (When Q1 is fully turned on, V dp is approximately equal to 0V), where V bulk is the voltage of the input power supply of the transformer in the switching power supply circuit, V dp It is the drain voltage of the primary power tube in the switching power supply circuit.

[0058] Furthermore, when the primary power tube is turned on, the voltage difference V across the auxiliary winding Na aux for: The minimum voltage of the ZCD pin will be clamped at 0V, so the current of the resistor Rzh (i.e. flowing from the ZCD pin to the transformer auxiliary winding Na) can represent the voltage difference V of the transformer primary winding. bulk -V dp , which can be equivalent to representing V dp The voltage value is: V dp =V bulk -ΔV Np , where ΔV Np is the voltage drop of the primary winding.

[0059] When the power tube is turned off, the drain voltage of the primary power tube is:

[0060] When the primary power tube is turned on, the current I CLP for: R zhis the resistance value of the resistor between the ZCD pin and the auxiliary winding of the transformer in the switching power supply circuit, that is, Figure 1 The resistance value of the middle resistor Rzh.

[0061] When the primary power tube Q1 is turned on and driven too strongly, the advantages are: the drain voltage V dp The drop speed is fast, the time when the current and voltage of Q1 coexist is short, and the switching loss is low; at the same time, after the Miller platform ends, DRV will quickly pull to the set maximum drive voltage, the conduction loss will also be reduced, and the system efficiency is better. The disadvantage is: the drain voltage V dp The drop speed is fast, and the corresponding primary power path dV / dt is large. Due to the existence of leakage inductance, the positive voltage V sec A large undershoot burr will be generated, causing a large voltage spike in the drain-source voltage of the secondary-side synchronous rectifier power tube Q2, affecting the reliability and safety of the entire system. In extreme cases, the drain-source voltage of the secondary-side power tube Q2 may exceed the withstand voltage value and burn out.

[0062] The advantages and disadvantages of driving too slowly are exactly the opposite of driving too strongly.

[0063] The current mainstream solution is segmented driving. dp Before it drops to 0V, a small current weak drive is used, and the system will not produce a large voltage spike; when V dp After reaching 0V, it switches to a high-current strong drive, quickly pulling DRV up to the set value, reducing conduction losses.

[0064] The above solution exists V dp Detection problem: If the V dp Switching between strong and weak drive, because V dp The highest voltage is about 600V, and the controller needs to use a process that integrates 600V devices. If the strong and weak drives are switched by detecting the Miller platform, since different application systems use different primary power tubes and different threshold voltages (varying from 1.5V to 4V), the Miller platform voltage is related to the threshold and a good detection effect cannot be achieved.

[0065] Based on the above problems, the embodiment of the present application proposes a method based on ZCD pin equivalent detection V dp The solution is compatible with the current mainstream application solutions and process design platforms. By controlling the switching between strong and weak drives, it effectively solves the problems of voltage spikes caused by excessive drive and low efficiency caused by too slow drive.

[0066] In an exemplary embodiment, Figure 4As shown, the above-mentioned segmented drive detection circuit includes: a ZCD pin detection circuit and a comparator U21; the ZCD pin detection circuit includes: a negative voltage clamping module, a mirror MOS tube Q25 and a clamping resistor Rset; the negative voltage clamping module is connected to the ZCD pin of the switching power supply circuit, the negative voltage clamping module is connected to the gate of the mirror MOS tube Q25, the drain of the mirror MOS tube Q25 is connected to the first power supply VP, the source of the mirror MOS tube Q25 is connected to one end of the clamping resistor Rset, the other end of the clamping resistor Rset is grounded, one end of the clamping resistor Rset is also connected to the non-inverting input end of the comparator U21, and the inverting input end of the comparator U21 is used to input the switching threshold voltage V SET The negative voltage clamping module is used to output the current I CLP The image is mirrored to the mirror MOS tube Q25 to form a clamping current I ZCD , the clamping current I ZCD The restoration voltage V of the drain voltage of the primary power tube in the switching power supply circuit formed at one end of the embedded resistor Rset DET The inverting input terminal of the comparator U21 is used to input the switching threshold voltage, and the comparator U21 is used to compare the restoration voltage with the switching threshold voltage to generate a strong or weak drive switching signal CTR.

[0067] Further, such as Figure 4 As shown, the negative voltage clamping module includes a first MOS tube Q21, a second MOS tube Q22, a third MOS tube Q23 and a fourth MOS tube Q24; the source of the first MOS tube Q21 is connected to the ZCD pin, the gate of the first MOS tube Q21 is connected to the gate of the second MOS tube Q22, the source of the second MOS tube Q22 is grounded, and the drain of the second MOS tube Q22 is connected to the gate of the second MOS tube Q22; the drain of the first MOS tube Q21 is connected to the source of the fourth MOS tube Q24, the drain of the fourth MOS tube Q24 is connected to the positive electrode of the power supply, the gate of the fourth MOS tube Q24 is connected to the gate of the third MOS tube Q23, the source of the third MOS tube Q23 is connected to the drain of the second MOS tube Q22, and the drain of the third MOS tube Q23 is connected to the first power supply VP; the gate of the third MOS tube Q23 and the gate of the fourth MOS tube Q24 are also connected to the gate of the mirror MOS tube Q25. The first MOS transistor Q21 and the second MOS transistor Q22 are N-type MOS transistors, and the third MOS transistor Q23, the fourth MOS transistor Q24 and the mirror MOS transistor Q25 are P-type MOS transistors.

[0068] Among them, Q21~Q24 form the negative voltage clamp module of the ZCD pin, and the current I CLP Flows through Q21 and Q24, is mirrored to Q25 through Q24 and flows into Rset, generating V aux The reduction voltage V DET . V DET and V SET The comparator U21 generates a strong or weak driving switching signal CTR. DET and V SET You can also set the V corresponding to the segment drive switching point dp .

[0069] The applicant needs to explain that the present application needs to include the conversion of the ZCD clamping current into an equivalent V aux Voltage V DET Method, other circuits that can achieve this function are also within the protection scope of this application, V DET and V SET Set the switching point of the power tube strong and weak drive (segment drive switching point) together.

[0070] The working principle of a switching power supply circuit control system provided in the above embodiment is:

[0071] Q21~Q24 form the negative voltage clamp module of the ZCD pin: that is, when the voltage of the ZCD pin is greater than 0V, the negative voltage clamp module has no effect on the voltage of the ZCD pin; when the voltage of the ZCD pin is less than 0V, it can be seen from the structure of Q21 and Q22 that V GS_Q21 >V GS_Q22 , V GS_Q21 and V GS_Q22 These are the gate voltages of Q21 and Q22, respectively. At this time, Q21 generates a clamping current. The clamping current is mirrored to Q23 via Q24, and then flows into Q22. The gate voltages of Q21 and Q22 are adjusted according to the size of the clamping current, thereby stabilizing the voltage of the ZCD pin at 0V. That is, Q23, Q24, Q21, and Q22 together form a negative feedback system to stabilize the voltage of the ZCD pin at 0V.

[0072] When the voltage of the ZCD pin is greater than 0V: the voltage of Q21 and Q22 is approximately the threshold value V of the N-type MOS tube. THN , at this time, the gate voltage of Q11 is less than V THN According to the working principle of N-type MOS tube, the negative voltage clamp module does not work and no current passes through Q21.

[0073] When the voltage of the ZCD pin is less than 0V: the voltage of the gate of Q21 is greater than V THN , Q21 generates a current that flows through the ZCD pin, Rzh to the auxiliary winding, and the entire I CLPThe path is VP→Q24→Q21→Rzh→secondary winding Ns. The voltage of the auxiliary winding V aux The lower the voltage, the greater the current of Rzh, and the greater the current of Q21 and Q24. Rzh =-V aux , V Rzh is the voltage across the resistor Rzh.

[0074] Q24 embedded I CLP Through the current mirror with the ratio N mir Mirror to Q25, generate I ZCD , and finally flows to the resistor Rset, generating V DET , V DET With V dp The relationship is as follows:

[0075]

[0076] In the above formula, V DET is the reduction voltage, V bulk is the voltage of the input power supply of the transformer in the switching power supply circuit, V dp is the drain voltage of the primary power tube in the switching power supply circuit, R zh N is the resistance value of the resistor between the ZCD pin and the auxiliary winding of the transformer in the switching power supply circuit. ap N is the turns ratio of the auxiliary winding to the primary winding of the transformer in the switching power supply circuit, mir is the mirror current ratio, R set is the resistance value of the clamp resistor.

[0077] In the above formula, V DET The higher the V dp The lower. When V DET Exceed V SET When V dp When the value is lower than the value set by the formula, the CTR signal changes from logic 0 to logic 1, and the drive changes from weak drive to strong drive.

[0078] V SET The voltage is the set comparison threshold, that is, the switching threshold voltage, which corresponds to V dp With V bulk The present application embodiment proposes three types of V SET Generation method: the first is a fixed voltage value, the second is based on V bulk Select different voltage values. The third one is based on V DET The highest voltage sample generates the voltage value.

[0079] Based on the first V SET The segmented driving waveform diagram of the generation method is as follows: Figure 5As shown, the waveform describes the segmented drive in valley-locked working mode, as follows:

[0080] At t2, it starts to be pulled down and enters the Miller platform of DRV; at t3, V DET To reach a fixed V SET , the drive switches from a small current to a large current (weak drive switches to a strong drive); at t4, DRV reaches the maximum value, the power tube start-up process ends, and the drive circuit is reduced to 0.

[0081] V dp is the drain voltage of the primary power tube, which starts to be pulled down at t2; at t3a, V DET Reach V SET Voltage, at this time V dp There is still some distance from 0V; t3b is pulled down to 0V.

[0082] V aux 、V ZCD ,I CLP 、V DET To restore the equivalent V dp Waveform diagram of V DET Reach V SET When the corresponding V dp , that is, V dp When is the value, switch from weak drive to strong drive. Figure 3 It can be seen that when V SET The closer to V DET Peak voltage, corresponding to V dp The lower the voltage.

[0083] I DRV is the driving current waveform, where the current at the turn-off time is Figure 8 Isink controlled by S3.

[0084] DRV is the gate voltage waveform of the primary power tube. It can be seen that the fixed V SET When the drive current is switched, the Miller platform of the power tube does not end, V dp It does not drop to 0V.

[0085] PWM is a pulse width modulation signal that controls the opening and closing of the power tube in the loop.

[0086] Figure 5 The coordinate parameter N in ps 、N as 、N ap as follows:

[0087]

[0088] The above three formulas represent the turns ratio between the three windings of the transformer and are used to calculate the mapping voltage. ps N is the turns ratio of the primary winding to the secondary winding of the transformer in the switching power supply circuit. as N is the turns ratio of the secondary winding to the auxiliary winding of the transformer in the switching power supply circuit. ap It is the turns ratio of the auxiliary winding to the primary winding of the transformer in the switching power supply circuit.

[0089]

[0090] The voltage of the ZCD pin is V ZCD The voltage is clamped to 0V. aux When the voltage is negative, the voltage of the ZCD pin is 0V; when V aux When the voltage is high, the voltage of the ZCD pin is V aux The resistor divider (Rzh and Rzl divider).

[0091]

[0092]

[0093] Formula (5) is derived from the steady state V DET and V bulk The relationship is derived.

[0094] It can be seen that V SET Distance V DET The peak voltage difference ΔV is proportional to K. Z After conversion, it is the corresponding V when the drive switches. dp Voltage, which is:

[0095]

[0096] In another exemplary embodiment of the present application, when switching between strong and weak driving, the corresponding V dp Lower (V dp The closer to 0V), the better the voltage spike suppression effect is. bulk detection, select different V SET , namely Vset_1 and Vset_h. When the AC input voltage is 110V, Vset_1 is selected; when the AC input voltage is 220V, Vset_h is selected. Based on this, the embodiment of the present application provides a first VSET generating circuit, such as Figure 4As shown, the first VSET generating circuit includes a NOT gate U41, a first transmission gate tg41 and a second transmission gate tg42; the input end of the NOT gate U41 is connected to the determination signal LINE_CTR of the voltage of the input power supply of the transformer in the switching power supply circuit; the input end of the NOT gate U41 is respectively connected to the inverting control end of the first transmission gate tg41 and the positive phase control end of the second transmission gate tg42, and the output end of the NOT gate U41 is respectively connected to the positive phase control end of the first transmission gate tg41 and the inverting control end of the second transmission gate tg42;

[0097] The input end of the first transmission gate tg41 is used to input a first preset voltage, the input end of the second transmission gate tg42 is used to input a second preset voltage, the output end of the first transmission gate tg41 is connected to the output end of the second transmission gate tg42, and the output end of the first transmission gate tg41 and the output end tg42 of the second transmission gate are both used to output the switching threshold voltage. The first preset voltage is less than the second preset voltage.

[0098] Figure 6 It is a typical two-choice circuit. LINE_CTR (AC input voltage determination signal) controls whether tg41 or tg42 is turned on. V SET Select the corresponding voltage so that when the segment drive switches, V dp Closer to 0V, its waveform is as follows Figure 7 shown.

[0099] Figure 7 To select different V according to different AC input SET , to achieve the drive switching V dp The voltage is closer to 0V. Figure 7 The left side in the middle corresponds to the low voltage 110VAC input situation. Figure 7 The middle right side corresponds to the high voltage 220VAC input situation. Figure 7 Only the enlarged waveforms of the important nodes when the primary power tube is turned on are given in the figure. For other parts, please refer to Figure 3 .

[0100] Figure 7 For low voltage input, the voltage after bridge rectification is V bulk_l , the driving switching point corresponds to V dp The voltage is V bulk_l -V set_l / K z , the right side is high voltage V bulk_h , the corresponding switching point is V bulk_h -V set_h / K z At t1 and t3, the strong and weak drive switches, V dp The pull-down speed also changes.

[0101] V DET and V SET Select, low voltage AC input select V set_l , high voltage AC input select V set_h LINE_CTR is the high and low voltage AC input judgment signal, which controls V SET Select the corresponding reference voltage value.

[0102] In another exemplary embodiment, based on V DET The size of the switching threshold voltage is generated when V DET When V DET When it is smaller, a smaller switching threshold voltage is generated. As a preferred implementation, according to V DET The highest voltage generates the switching threshold voltage.

[0103] For example, in order to achieve the use of V DET The switching threshold voltage circuit is obtained by sampling the highest voltage to generate a voltage value, and a second VSET generating circuit is set, such as Figure 8 As shown, the second VSET generating circuit includes a peak sampling and holding subcircuit and a VSET generating subcircuit; the peak sampling and holding subcircuit is used to collect and hold the peak voltage of the restoration voltage; the VSET generating subcircuit is used to generate the switching threshold voltage according to the peak voltage.

[0104] Among them, Figure 8As shown, the peak sampling and holding subcircuit includes: a first operational amplifier U61, a diode D61, a first capacitor C61, a second capacitor C32, a controllable switch Q61, a second NOT gate U62 and a third transmission gate tg61. The positive phase input terminal of the first operational amplifier U61 is used to input the restoration voltage, the output terminal of the first operational amplifier U61 is connected to the anode of the diode D61, the reverse input terminal of the first operational amplifier U61 is respectively connected to the cathode of the diode D61, one end of the first capacitor C61, the input terminal of the controllable switch Q61 and the input terminal of the third transmission gate tg61, the other end of the first capacitor C61 and the output terminal of the controllable switch Q61 are both grounded, and the control terminal of the controllable switch Q61 is used to input a reset signal; the positive phase control terminal of the third transmission gate tg61 The control terminal of the third transmission gate tg61 and the input terminal of the second NOT gate U62 are both used to input a holding signal; the inverting control terminal of the third transmission gate tg61 is connected to the output terminal of the second NOT gate U62, the output terminal of the third transmission gate tg61 is connected to one terminal of the second capacitor C62, and the other terminal of the second capacitor C62 is grounded; the holding signal is used to maintain the collected peak voltage on the second capacitor C62 through the third transmission gate tg61 and the second NOT gate U62; the clearing signal is used to clear the voltage on the first capacitor C61 to zero through the controllable switch after the peak voltage is maintained on the second capacitor C62.

[0105] like Figure 8 As shown, the VSET generating subcircuit includes a second operational amplifier U63, a first current source Id and a voltage dividing resistor Rd; the non-inverting input terminal of the second operational amplifier U63 is used to input the peak voltage; the inverting input terminal of the second operational amplifier U63 is respectively connected to the output terminal of the second operational amplifier U63 and one end of the voltage dividing resistor Rd, the other end of the voltage dividing resistor Rd is connected to the positive electrode of the first current source Id, and the negative electrode of the first current source Id is grounded; the other end of the voltage dividing resistor Rd is used to output the switching threshold voltage.

[0106] The second VSET generating circuit is divided into two parts: a peak sampling and holding subcircuit composed of U61, C61, C62, and tg61, whose output signal is the peak voltage Vdet_pk of the restored voltage; and a VSET generating subcircuit composed of U63, Rd, and Id.

[0107] Among them, tg61 and the hold signal sam_ctr are used to hold the peak sampling voltage Vdet_pk_sam on C2 to generate Vdet_pk. After the sampling voltage is sent to Vdet_pk, the clear signal clear at the control end of Q61 clears the peak sampling signal on C61 to prepare for the peak sampling of the next cycle. Rd and Id set a V that is ΔV away from the peak voltage Vdet_pk. SET , its waveform is as follows Fig. 9 shown. Fig. 9 The main node waveforms when the VBULK voltage slowly increases are shown in Figure 1. Point A is the working waveform in steady state, and the driving switching point is ΔV / Kz; Point B is V bulk The waveform after it becomes high, at this time the driver switches the corresponding V dp The voltage is too high; Point C is the waveform after Vset sampling and refreshing, and the drive switching point returns to ΔV / Kz.

[0108] V DET 、Vdet_pk、V SET Indicates V bulk After going high, V DET The generated waveform, at V bulk The second wave after becoming high, V SET Refresh and return to steady state operation. CTR is the control signal for strong and weak driving.

[0109] Among them, V SET Vdet_pk maintains a fixed voltage difference ΔV, and Vset can also be a fixed ratio of Vdet_pk (such as 85%). In short, the V generated in this solution SET Related to Vdet_pk, the set voltage is then generated.

[0110] In another exemplary embodiment, Figure 1 As shown, the driving signal generating circuit in the above-mentioned switching power supply circuit control system includes: a first controllable switch S1, a second controllable switch S2, a third controllable switch S3, a second current source Iw, a third current source Is and a fourth current source Isink;

[0111] The input ends of the second current source Iw and the third current source Is are both connected to the second power supply VDD, the output end of the second current source Iw is connected to the input end of the first controllable switch S1, the output end of the third current source Is is connected to the input end of the second controllable switch S2, the output end of the first controllable switch S1 and the output end of the second controllable switch S2 are both connected to the input end of the third controllable switch S3, the output end of the third controllable switch S3 is connected to the input end of the fourth current source Isink, and the output end of the fourth current source Isink is grounded; the output end of the first controllable switch S1 and the output end of the second controllable switch S2 are also used to output the drive signal; the control end of the first controllable switch S1, the control end of the second controllable switch S2 and the control end of the third controllable switch S3 are all connected to the segmented drive logic control circuit.

[0112] In the above embodiment, the second power source VDD is obtained by performing voltage stabilization conversion on the first power source VP.

[0113] The specific control logic of the above segmented drive logic control circuit is:

[0114] When the strong-weak drive switching signal indicates that the switching power supply circuit needs to be strongly driven, and the PWM control signal is at a high level, a first current source control signal is generated; the first current source control signal is used to charge the primary power tube in the control switching power supply circuit in the form of strong drive; when the strong-weak drive switching signal indicates that the switching power supply circuit needs to be weakly driven, and the PWM control signal is at a high level, a second current source control signal is generated; the second current source control signal is used to charge the primary power tube in the control switching power supply circuit in the form of weak drive; when the PWM control signal is at a low level, a third current source control signal is generated; the third current source control signal is used to draw power from the primary power tube in the control switching power supply circuit.

[0115] In combination with the above-mentioned drive signal generating circuit, the first current source control signal is used to control the first controllable switch and the second controllable switch to close, and control the third controllable switch to open; the second current source control signal is used to control the first controllable switch to close, and control the second controllable switch and the third controllable switch to open, and the third control signal is used to control the first controllable switch and the second controllable switch to open, and control the third controllable switch to close.

[0116] The working principle of the above switching power supply circuit control system is:

[0117] Segment drive detection: When PWM is logic 1, the primary power tube Q1 is turned on and the detection I ZCD current, generating an equivalent V aux voltage, and obtain the equivalent V dp , and the set voltage VSET The segmented drive control signal CTR is obtained by comparison and sent to the segmented drive control logic to generate the control signal P S1 and P S2 , used to change the gate charging current of the primary power tube. Weak drive is a small current Iw, and strong drive is a large current Iw+Is. When PWM is logic 0, the primary power tube is turned off, S3 is closed, and the gate voltage of the power tube is pulled down through Isink. Its waveform is as follows Fig.10 shown.

[0118] Fig.10 In the figure, VDRV is the gate voltage of the power tube, Vth is the threshold of the power tube Q1, and Vmp is the gate voltage corresponding to the Miller platform.

[0119] V dp The drain voltage of the primary power tube Q1 is usually segmented driving, which means charging the gate of Q1 with a small current before the end of the Miller platform, and charging the gate of Q1 with a large current after the Miller platform ends. Idrv is the control signal of the corresponding charging current. When V dp After it drops to 0V, the DRV output current switches from small to large, which can be achieved when V dp After it is reduced to a relatively low setting value, the strength of the drive is switched. CTR, S1, S2 and PWM are the start-up waveforms of the primary power tube.

[0120] In another exemplary embodiment, a specific structural diagram of a segmented drive logic control circuit is provided, such as Fig.11 As shown, the segmented drive logic control circuit includes: an AND gate U101, a first inverter U102 and a second inverter U103;

[0121] The first input end of the AND gate U101 is used to input a strong or weak drive switching signal; the second input end of the AND gate U101 is used to input a PWM control signal; the output end of the AND gate U101 is connected to the control end of the second controllable switch S2; the second input end of the AND gate U101 is also connected to the input end of the first inverter U102, the output end of the first inverter U102 is respectively connected to the input end of the second inverter U103 and the control end of the third controllable switch S3, and the output end of the second inverter U103 is connected to the control end of the first controllable switch S1.

[0122] In another exemplary embodiment, a specific structural diagram of another segmented drive logic control circuit is provided, such as Fig.12As shown, the segmented drive logic control circuit includes: a D flip-flop DFF, a third inverter U111 and a fourth inverter U112; the data input end of the D flip-flop DFF is connected to the positive electrode of the power supply, the reset end of the D flip-flop DFF is used to input a PWM control signal, and the clock input end of the D flip-flop DFF is used to input a strong or weak drive switching signal; the output end of the D flip-flop DFF is connected to the control end of the second controllable switch S2; the reset end of the D flip-flop DFF is also connected to the input end of the third inverter U111, the output end of the third inverter U111 is respectively connected to the input end of the fourth inverter U112 and the control end of the third controllable switch S3, and the output end of the fourth inverter U112 is connected to the control end of the first controllable switch S1.

[0123] Fig.11 and Fig.12 In the figure, PWM is the primary power tube on / off signal. When PWM=1, DRV=1; when PWM=0, DRV=0. CTR is the strong / weak drive switching signal when the primary power tube is turned on. It changes from low level to high level, indicating that the segmented drive changes from weak drive to strong drive. The charging current of DRV on the power tube gate changes from small to large. S1 represents the weak drive control switch, S2 represents the strong drive control switch, S3 represents the power tube off, P S1 ~P S3 is the control signal of the three switches, P S1 ~P S3 A high level "1" means that the current branch is turned on. VP Represents the power signal, corresponding to logic 1.

[0124] Fig.11 The working principle of the segmented drive logic control circuit shown is:

[0125] When PWM is high, after two inverters, P S1 High level, weak drive is turned on;

[0126] When the segment drive needs to switch from weak drive to strong drive, CTR changes from low level to high level;

[0127] When PWM and CTR are both high, the AND gate gets P S2 High level, switch to strong drive;

[0128] When PWM is low, P S1 and P S2 High level, P S3 It is low level and turns off the primary power tube.

[0129] Fig.12 The working principle of the segmented drive logic control circuit shown is:

[0130] D flip-flop DFF: Reset low level clear is effective, the rising edge of the clock signal is effective, and the signal of the data input terminal D is sent to the output terminal Q;

[0131] When PWM is high, after two inverters, P S1 High level, weak drive is turned on, and DFF is no longer cleared;

[0132] When the segment drive needs to switch from weak drive to strong drive, CTR changes from low level to high level);

[0133] When CTR changes from low level to high level, PWM is high at the same time, DFF is no longer cleared, and the output signals Q, D, P of DFF are S2 , P VP All are high level, switched to strong drive;

[0134] When PWM is high, P S3 High level, P S1 is low level; DFF is cleared, P S2 When DRV is at a low level, power is drawn from DRV. When DRV is at a low level, the primary power tube is turned off.

[0135] The control logic circuit is only an example. The specific implementation method may be different, but the control scheme is the same, that is:

[0136] When PWM is logic 1, the primary power tube is turned on; when the control signal CTR is logic 0, S1 is closed, S2 and S3 are disconnected, and the system adopts weak drive, that is, small current I W Charge the power tube; when the control signal CTR is logic 1, S1 and S2 are closed, S3 is open, and the system adopts strong drive, that is, large current I W +I S When PWM is logic 0, S1 and S2 are disconnected, S3 is closed, and the system uses I SINK The current draws power from the gate of the power tube, controlling the primary power tube to shut down.

[0137] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Fig.13As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a switching power supply circuit control method is implemented.

[0138] Those skilled in the art will understand that Fig.13 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components. In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0139] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A switching power supply circuit control method, characterized in that: The switching power supply circuit control method comprises: The current outputted from the ZCD pin of the switching power supply circuit is collected to generate a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit; Comparing the restoration voltage with the switching threshold voltage to obtain a strong or weak driving switching signal; A current source control signal is generated according to the strong and weak drive switching signal and the PWM control signal; the current source control signal is used to control the gate charging current of the primary power tube in the switching power supply circuit.

2. The switching power supply circuit control method according to claim 1, characterized in that: The switching threshold voltage is a fixed voltage value; Or, the switching threshold voltage is determined based on the voltage of the input power supply of the transformer in the switching power supply circuit; Alternatively, the switching threshold voltage is determined based on the restoration voltage.

3. The switching power supply circuit control method according to claim 1, characterized in that: The generating of the current source control signal according to the strong and weak drive switching signal and the PWM control signal specifically includes: When the strong-weak drive switching signal indicates that the switch power supply circuit needs to be strongly driven, and the PWM control signal is at a high level, a first current source control signal is generated; the first current source control signal is used to charge the primary power tube in the control switch power supply circuit in the form of strong drive; When the strong-weak drive switching signal indicates that the switch power supply circuit needs to be weakly driven, and the PWM control signal is at a high level, a second current source control signal is generated; the second current source control signal is used to charge the primary power tube in the control switch power supply circuit in the form of weak drive; When the PWM control signal is at a low level, a third current source control signal is generated; the third current source control signal is used to control the primary power tube in the switch power supply circuit to draw power.

4. A switching power supply circuit control system, characterized in that: The switching power supply circuit control system applies the switching power supply circuit control method according to any one of claims 1 to 3, and the switching power supply circuit control system comprises: a segmented drive detection circuit, a segmented drive logic control circuit and a drive signal generation circuit; The segmented drive detection circuit is connected to the ZCD pin of the switching power supply circuit and the segmented drive logic control circuit respectively, and the segmented drive detection circuit is used to collect the current output by the ZCD pin of the switching power supply circuit, generate a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit, and compare the restoration voltage with the switching threshold voltage to obtain a strong or weak drive switching signal; The segmented drive logic control circuit is connected to the drive signal generating circuit, and the segmented drive logic control circuit is used to generate a current source control signal according to the strong and weak drive switching signal and the PWM control signal; The driving signal generating circuit is used to generate a gate charging current according to the current source control signal; the gate charging current is used to control the primary power tube in the switching power supply circuit.

5. The switching power supply circuit control system according to claim 4, characterized in that: The segmented drive detection circuit comprises: a ZCD pin detection circuit and a comparator; The ZCD pin detection circuit comprises: a negative voltage clamping module, a mirror MOS tube and a clamping resistor; The negative voltage clamping module is connected to the ZCD pin of the switching power supply circuit, the negative voltage clamping module is also connected to the gate of the mirror MOS tube, the drain of the mirror MOS tube is connected to the positive electrode of the power supply, the source of the mirror MOS tube is connected to one end of the clamping resistor, the other end of the clamping resistor is grounded, and one end of the clamping resistor is also connected to the non-inverting input end of the comparator; The negative voltage clamping module is used to mirror the current output by the ZCD pin to the mirror MOS tube to form a clamping current, and the clamping current is a restoration voltage of the drain voltage of the primary power tube in the switching power supply circuit formed at one end of the clamping resistor; The inverting input terminal of the comparator is used to input a switching threshold voltage; The comparator is used to compare the restoration voltage with the switching threshold voltage to generate a strong or weak driving switching signal.

6. The switching power supply circuit control system according to claim 5, characterized in that: The relationship between the restoration voltage and the drain voltage of the primary power tube in the switching power supply circuit is: Among them, V DET is the reduction voltage, V bulk is the voltage of the input power supply of the transformer in the switching power supply circuit, V dp is the drain voltage of the primary power tube in the switching power supply circuit, R zh N is the resistance value of the resistor between the ZCD pin and the auxiliary winding of the transformer in the switching power supply circuit. ap N is the turns ratio of the auxiliary winding to the primary winding of the transformer in the switching power supply circuit, mir is the mirror current ratio, R set is the resistance value of the clamp resistor.

7. The switching power supply circuit control system according to claim 4, characterized in that: The switching threshold voltage is a fixed voltage value; Or, the switching threshold voltage is determined based on the voltage of the input power supply of the transformer in the switching power supply circuit; Alternatively, the switching threshold voltage is determined based on the restoration voltage.

8. The switching power supply circuit control system according to claim 7, characterized in that: When the switching threshold voltage is determined based on the voltage of the input power supply of the transformer in the switching power supply circuit, the switching power supply circuit control system further includes a first VSET generating circuit; The first VSET generating circuit is used to output a first preset voltage as the switching threshold voltage when the voltage of the input power supply is 220V, and to output a second preset voltage as the switching threshold voltage when the voltage of the input power supply is 110V; The first preset voltage is: the restoration voltage when the voltage of the input power supply of the transformer in the switching power supply circuit is 110V and the absolute value of the drain voltage of the primary power tube in the switching power supply circuit is less than the preset threshold; The second preset voltage is: the restoration voltage when the voltage of the input power supply of the transformer in the switching power supply circuit is 220V and the absolute value of the drain voltage of the primary power tube in the switching power supply circuit is less than the preset threshold.

9. The switching power supply circuit control system according to claim 7, characterized in that: When the switching threshold voltage is determined based on the restoration voltage, the segmented drive detection circuit further includes a second VSET generating circuit; The second VSET generating circuit is used to output a voltage smaller than a preset difference of a peak voltage of the restoration voltage as the switching threshold voltage.

10. The switching power supply circuit control system according to claim 4, characterized in that: The driving signal generating circuit comprises: a first controllable switch, a second controllable switch, a third controllable switch, a second current source, a third current source and a fourth current source; The input ends of the second current source and the third current source are both connected to the positive electrode of the power supply, the output end of the second current source is connected to the input end of the first controllable switch, the output end of the third current source is connected to the input end of the second controllable switch, the output end of the first controllable switch and the output end of the second controllable switch are both connected to the input end of the third controllable switch, the output end of the third controllable switch is connected to the input end of the fourth current source, and the output end of the fourth current source is grounded; The output end of the first controllable switch and the output end of the second controllable switch are also used to output the driving signal; The control end of the first controllable switch, the control end of the second controllable switch and the control end of the third controllable switch are all connected to the segmented drive logic control circuit.

11. The switching power supply circuit control system according to claim 10, characterized in that: In terms of generating a current source control signal according to a strong or weak drive switching signal and a PWM control signal, the segmented drive logic control circuit is specifically used for: When the strong-weak drive switching signal indicates that the switch power supply circuit needs to be strongly driven, and the PWM control signal is at a high level, a first current source control signal is generated; the first current source control signal is used to charge the primary power tube in the control switch power supply circuit in the form of strong drive; When the strong-weak drive switching signal indicates that the switch power supply circuit needs to be weakly driven, and the PWM control signal is at a high level, a second current source control signal is generated; the second current source control signal is used to charge the primary power tube in the control switch power supply circuit in the form of weak drive; When the PWM control signal is at a low level, a third current source control signal is generated; the third current source control signal is used to control the primary power tube in the switch power supply circuit to draw power.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the switching power supply circuit control method according to any one of claims 1 to 3 is implemented.

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