Switching transistor control method, converter and power adapter

Abstract

The application discloses a switch tube control method, a controller, a converter and a power adapter. The switch tube control method is used for controlling a first switch tube in a hybrid flyback topology converter. The switch tube control method comprises the following steps: generating a first feedback voltage based on a current flowing through a photocoupler, and determining an operation mode based on the first feedback voltage; outputting a second feedback voltage based on a first difference value between a voltage of an input power supply and a first voltage and the first feedback voltage, so that the same first feedback voltage can be obtained under different input power supplies and output voltages of the hybrid flyback topology converter, wherein the first voltage is a product of a turn ratio of a primary winding and a secondary winding and the output voltage; and controlling the first switch tube to be turned off based on the operation mode and the second feedback voltage. In the foregoing manner, the stability of the corresponding relationship between the first feedback voltage and an output current can be improved, so that debugging and power optimization can be facilitated.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of switch control, in particular to a switch control method, a converter and a power adapter. BACKGROUND

[0002] The hybrid flyback converter or asymmetrical half-bridge fly-back converter combines the traditional simplified flyback topology structure and the performance of the resonant converter. By controlling the high-voltage side switch and the low-voltage side switch in the asymmetrical half-bridge flyback topology, and adjusting the positive and negative magnetization currents, zero voltage switching can be achieved on the primary side of the transformer, and zero current switching can be achieved on the secondary side, thereby improving the efficiency. In addition, the transformer leakage energy is recycled, further improving the efficiency. The hybrid flyback converter has been widely used in USB PD power adapters due to its wide operating range, ultra-high conversion efficiency and low standby power. SUMMARY

[0003] Embodiments of the present application provide a switch control method, a converter and a power adapter, which can improve the stability of the corresponding relationship between the first feedback voltage and the output current, so as to facilitate debugging and power optimization.

[0004] In a first aspect, embodiments of the present application provide a switch control method for controlling a first switch in a hybrid flyback converter, the hybrid flyback converter further comprising a controller, a second switch, a primary winding, a secondary winding, a capacitor and an optocoupler, the first switch and the second switch being connected in series between an input power supply and ground, a connection point between the first switch and the second switch being connected to a same-named end of the primary winding, the optocoupler being connected to a different-named end of the secondary winding, the controller being connected to the first switch, the second switch and the optocoupler respectively, and the capacitor being connected between the same-named end of the primary winding and ground or the capacitor being connected between the input power supply and the different-named end of the primary winding; the switch control method comprising:

[0005] generating a first feedback voltage based on a current flowing through the optocoupler, and determining an operating mode based on the first feedback voltage;

[0006] outputting a second feedback voltage based on a first difference between a voltage of the input power supply and a first voltage and the first feedback voltage, so that the same first feedback voltage can be obtained under different input power supply and output voltage of the hybrid flyback converter, wherein the first voltage is a product of a turns ratio of the primary winding and the secondary winding and the output voltage;

[0007] control the first switch to be off based on the operation mode and the second feedback voltage.

[0008] In one or more embodiments, the outputting the second feedback voltage based on the first difference between the voltage of the input power supply and the first voltage and the first feedback voltage comprises:

[0009] The second feedback voltage is determined and outputted by the following formula:

[0010] V FB1 = V FB -K1×V FB ×(V IN -N1×V OUT )-K2×(V IN -N1×V OUT );

[0011] wherein, V FB1 is the second feedback voltage, V FB is the first feedback voltage, K1 is a first preset coefficient, V IN is the voltage of the input power supply, V OUT is the output voltage, N1 is a turns ratio of the primary winding and the secondary winding, and K2 is a second preset coefficient.

[0012] In one or more embodiments, the switch control method further comprises:

[0013] adjusting the first preset coefficient to obtain the same first feedback voltage under different voltages of the input power supply and the output voltage when the output current of the hybrid flyback topology converter is a first current, wherein the first current is an average current when the operation mode is configured to be a discontinuous conduction mode;

[0014] adjusting the second preset coefficient to obtain the same first feedback voltage under different voltages of the input power supply and the output voltage when the output current of the hybrid flyback topology converter is a second current, wherein the second current is an average current when the operation mode is configured to be a burst mode.

[0015] In one or more embodiments, the determining the operation mode based on the first feedback voltage comprises:

[0016] determining an output power of the hybrid flyback topology converter based on the first feedback voltage;

[0017] determine the operation mode as the critical conduction mode when the output power is greater than or equal to a first preset power, determine the operation mode as the discontinuous conduction mode when the output power is less than the first preset power and greater than or equal to a second preset power, and determine the operation mode as the burst mode when the output power is less than the second preset power, wherein the first preset power is greater than the second preset power.

[0018] In one or more embodiments, the controlling the first switch to be turned off based on the operation mode and the second feedback voltage comprises:

[0019] determining a reference voltage based on the second feedback voltage in the operation mode;

[0020] controlling the first switch to be turned off when a second voltage is greater than the reference voltage, wherein the second voltage is generated based on a current flowing through the primary winding.

[0021] In one or more embodiments, the determining the reference voltage based on the second feedback voltage in the operation mode comprises:

[0022] determining the reference voltage based on the following formula when the operation mode is the critical conduction mode:

[0023] V COMP = K3 x V FB .

[0024] wherein V COMP is the reference voltage, and K3 is a third preset coefficient.

[0025] In one or more embodiments, the determining the reference voltage based on the second feedback voltage in the operation mode comprises:

[0026] determining the reference voltage based on the following formula when the operation mode is the discontinuous conduction mode or the burst mode:

[0027] V COMP = K3 x V FB x (T SW / (T SW - T WAIT )).

[0028] wherein T SW is a period of a pulse width modulation signal for controlling the first switch, and T WAIT is a time duration from when the second switch is turned off to when the first switch is turned on.

[0029] In a second aspect, the embodiments of the present application provide a hybrid flyback topology converter, comprising a controller, a first switch tube, a second switch tube, a primary winding, a secondary winding, a capacitor and an optocoupler.

[0030] The first switch tube and the second switch tube are connected in series between an input power supply and the ground, a connection point between the first switch tube and the second switch tube is connected to a same-named end of the primary winding, the optocoupler is connected to a different-named end of the secondary winding, the controller is connected to the first switch tube, the second switch tube and the optocoupler respectively, and the capacitor is connected between the same-named end of the primary winding and the ground or the capacitor is connected between the input power supply and the different-named end of the primary winding, wherein the controller is configured to execute the method as described above.

[0031] In a third aspect, the embodiments of the present application provide a power adapter, comprising the hybrid flyback topology converter as described above.

[0032] The switch tube control method of the embodiments of the present application is used to control the first switch tube in the hybrid flyback topology converter, the hybrid flyback topology converter further comprises a controller, a second switch tube, a primary winding, a secondary winding, a capacitor and an optocoupler, the first switch tube and the second switch tube are connected in series between an input power supply and the ground, a connection point between the first switch tube and the second switch tube is connected to a same-named end of the primary winding, the optocoupler is connected to a different-named end of the secondary winding, the controller is connected to the first switch tube, the second switch tube and the optocoupler respectively, and the capacitor is connected in series with the primary winding and is connected in parallel with the second switch tube. The switch tube control method comprises: generating a first feedback voltage based on a current flowing through the optocoupler, and determining an operation mode based on the first feedback voltage; outputting a second feedback voltage based on a first difference between a voltage of the input power supply and a first voltage and the first feedback voltage, so that the same first feedback voltage can be obtained under different input power supplies and output voltages of the hybrid flyback topology converter, wherein the first voltage is a product of a turns ratio of the primary winding and the secondary winding and the output voltage; and controlling the first switch tube to be turned off based on the operation mode and the second feedback voltage. Through the above process, on the one hand, the control of the first switch tube can be realized, and on the other hand, the control of the first switch tube is realized based on the same first feedback voltage obtained under different input power supplies and output voltages of the hybrid flyback topology converter, so that the stability of the corresponding relationship between the first feedback voltage and the output current can be improved, thereby facilitating debugging and power optimization. BRIEF DESCRIPTION OF DRAWINGS

[0033] One or more embodiments are illustrated by way of example in the figures that are attached to this description, these illustrative examples do not configure a limitation to the embodiments, and the elements with the same reference numerals in the figures represent similar elements.

[0034] Figure 1is a flow chart of the switch control method provided by the embodiment of the present application;

[0035] Figure 2 is a structure diagram of the hybrid flyback topology converter provided by the embodiment of the present application Figure 1 ;

[0036] Figure 3 is a structure diagram of the hybrid flyback topology converter provided by the embodiment of the present application Figure 2 ;

[0037] Figure 4 is a control block for controlling the first switch provided by the embodiment of the present application Figure 1 ;

[0038] Figure 1 is a schematic diagram of the step 101 shown in the method for controlling the switch provided by the embodiment of the present application Figure 6 ;

[0039] Figure 7 is a corresponding relationship between the first feedback voltage and the output current provided by the embodiment of the present application

[0040] Figure 2 is a control block for controlling the first switch provided by the embodiment of the present application Figure 8 ;

[0041] Figure 1 is a schematic diagram of the first feedback voltage and the output current provided by the embodiment of the present application Figure 9 ;

[0042] Figure 2 is a schematic diagram of the first feedback voltage and the output current provided by the embodiment of the present application Figure 10 ;

[0043] Figure 3 is a schematic diagram of the first feedback voltage and the output current provided by the embodiment of the present application Figure 11 ;

[0044] Figure 4 is a schematic diagram of the first feedback voltage and the output current provided by the embodiment of the present application Figure 12 ;

[0045] Figure 1 is a schematic diagram of the step 103 shown in the method for controlling the switch provided by the embodiment of the present application Figure 13 ;

[0046] Figure 1 is a structure diagram of the controller for controlling the first switch provided by the embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for clear and detailed description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0048] It should be noted that when an element is described as "connected to" another element, it can be directly connected to the other element, or one or more intervening elements can be present between them.

[0049] In addition, the technical features involved in each of the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0050] Please refer to Figure 2 and Figure 1 , Figure 2 the flowchart of the switch control method provided by the embodiments of the present application, Figure 2 two structure diagrams of the hybrid flyback topology converter provided by the embodiments of the present application, wherein Figure 2 (A1) part of (A1) shows the first structure diagram; Figure 2 (A2) part of (A2) shows the second structure diagram. The switch control method is used to control the first switch Q1 in the hybrid flyback topology converter 10, and the hybrid flyback topology converter 10 further includes a controller U1, a second switch Q2, a primary winding LA1, a secondary winding LA2, a capacitor CA2 and an optical coupler U2. The first switch Q1 and the second switch Q2 are connected in series between the input power VIN and the ground. The connection point between the first switch Q1 and the second switch Q2 is connected to the same end of the primary winding LA1. The optical coupler U2 is connected to the different end of the secondary winding LA2. The controller U1 is connected to the first switch Q1, the second switch Q2 and the optical coupler U2 respectively. The capacitor CA2 is connected in series with the primary winding LA1 and then connected in parallel with the second switch Q2. Wherein, as shown in (A1) part of (A1), the first switch Q1 and the second switch Q2 are connected in series from top to bottom between the input power VIN and the ground. The capacitor CA2 is connected between the different end of the primary winding LA1 and the ground; as shown in (A2) part of (A2), the second switch Q2 and the first switch Q1 are connected in series from top to bottom between the input power VIN and the ground. The capacitor CA2 is connected between the same end of the primary winding LA1 and the input power. Figure 2 Figure 3

[0051] ​​In the embodiments of this application, each switch (including the first switch Q1, the second switch Q2, and the subsequent third switch Q3 and fourth switch Q4) is an NMOS transistor. The gate of the NMOS transistor is the first terminal of each switch, the source of the NMOS transistor is the second terminal of each switch, and the drain of the NMOS transistor is the third terminal of each switch.

[0052] In addition, each switching transistor can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate commutated thyristor (IGCT) device, a gate turn-off thyristor (GTO) device, a silicon controlled rectifier (SCR) device, a junction gate field-effect transistor (JFET) device, a MOS controlled thyristor (MCT) device, etc.

[0053] Please refer to Figure 3 , Figure 3 An exemplary circuit structure of a hybrid flyback topology converter 10 is shown. Wherein, Figure 2 In order to be in Figure 2 Based on the (A1) section, add the circuit structure of the device, while Figure 3 Based on part (A2) in the above, add the specific implementation process of the device and Figure 3 Similarly, this will not be repeated here. The hybrid flyback topology converter 10 also includes an auxiliary winding LA3, capacitors CA1, CA2, CA3, CA4, CA5, CA6, and CA7, resistors RA1, RA2, RA3, RA4, RA5, and RA6, a third switch Q3, a fourth switch Q4, diodes DA1 and DA2, a controller U3, a controller U4, and a driver U51. The first switch Q1, the second switch Q2, and the driver U51 form a driver chip. This driver chip receives two pulse-width modulation (PWM) signals output by the controller U1, enabling the driver U51 to control the first switch Q1 and the second switch Q2 respectively based on the two PWM signals, thereby driving the first switch Q1 and the second switch Q2 to alternately turn on and off. Figure 3 The connection relationships between the devices in the hybrid flyback topology converter 10 shown are as follows: Figure 3 As shown, and Figure 1 The specific working principle of the hybrid flyback topology converter 10 shown is common knowledge in the field and will not be described in detail here.

[0054] Please return to the reference. Figure 4 The switching transistor control method includes the following steps:

[0055] Step 101: Generate a first feedback voltage based on the current flowing through the optocoupler, and determine the operating mode based on the first feedback voltage.

[0056] Specifically, please collect together Figure 4 , Figure 4 The control block diagram of the first switch Q1 is exemplarily shown, i.e. the software implementation block diagram of the controller U1 for controlling the first switch Q1. As shown in Figure 5 , a voltage is generated on the resistor RB1 by the current I U2 flowing through the optocoupler U2, and the difference between the voltage of the power supply VDD and the voltage on the resistor RB1 is taken as the first feedback voltage V FB . The first feedback voltage V FB Through mode detection, the operating mode can be determined, wherein the operating mode is one of the critical conduction mode, the discontinuous conduction mode and the burst mode.

[0057] In some embodiments, as shown in Figure 4 , the specific implementation process of determining the operating mode based on the first feedback voltage in step 101 includes the following steps:

[0058] Step 501: Determine the output power of the hybrid flyback topology converter based on the first feedback voltage.

[0059] Step 502: Determine the operating mode as the critical conduction mode when the output power is greater than or equal to the first preset power, determine the operating mode as the discontinuous conduction mode when the output power is less than the first preset power and greater than or equal to the second preset power, and determine the operating mode as the burst mode when the output power is less than the second preset power, wherein the first preset power is greater than the second preset power.

[0060] Specifically, according to the first feedback voltage V FB , the current I U2 flowing through the optocoupler U2 can be determined, and then the output current of the hybrid flyback topology converter 10 can be determined, so that the output power of the hybrid flyback topology converter 10 can be determined.

[0061] It can be understood that when the hybrid flyback topology converter is applied in a power adapter, according to the size of the output power of the hybrid flyback topology converter, multiple mode operation is generally supported. Then, when the output power is greater than or equal to a first preset power (i.e., at high power), it is determined that the operation mode is a critical conduction mode (CrM), when the output power is less than the first preset power and greater than or equal to a second preset power (i.e., at medium power), it is determined that the operation mode is a discontinuous conduction mode (DCM), and when the output power is less than the second preset power (i.e., at low power), it is determined that the operation mode is a burst mode (Burst). The first preset power and the second preset power are preset powers, which can be set based on actual application scenarios. The specific implementation of the critical conduction mode, the discontinuous conduction mode and the burst mode is well known in the art, and will not be described here.

[0062] Step 102: outputting a second feedback voltage based on a first difference between the voltage of the input power supply and a first voltage and the first feedback voltage, so that the same first feedback voltage can be obtained under different input power supplies and output voltages of the hybrid flyback topology converter, wherein the first voltage is the product of the turns ratio of the primary winding and the secondary winding and the output voltage.

[0063] Step 103: controlling the first switch tube to be turned off based on the operation mode and the second feedback voltage.

[0064] By executing steps 102 and 103, on the one hand, the control of the first switch tube Q1 (i.e., the control of the first switch tube Q1 to be turned off) can be realized, and on the other hand, by outputting the same first feedback voltage V FB The control of the first switch tube Q1 can improve the stability of the corresponding relationship between the first feedback voltage V FB and the output current I OUT .

[0065] When the control block diagram as shown in Figure 6 is in static operation and the closed-loop control is in a steady state, the corresponding relationship between the first feedback voltage V FB and the output current I OUT is as shown in Figure 6 . As shown in Figure 6 , the abscissa is the output current I OUT(Here represents the average current); the current I MAX is the maximum allowable current, beyond which the hybrid flyback topology converter will automatically protect, exit the closed-loop mode; the current IDCM is the output current when entering the discontinuous conduction mode; the current IBST is the output current when entering the burst mode. It can be seen that the first feedback voltage V FB and the output current I OUT is a linear relationship. Although, in the transient state of the closed-loop control, for example, the starting transient state, the output voltage is in the fast-changing moment, the first feedback voltage V FB needs to be temporarily increased or reduced to adjust the output voltage, and cannot maintain the linear relationship with the output current I OUT , but does not affect the efficiency, because the efficiency is mainly in the steady state of the closed-loop control.

[0066] In actual applications, since the circuit for detecting the output current I OUT is usually not set, the correspondence between the first feedback voltage V FB and the output current I OUT is a linear relationship, so that the size of the output current I FB is determined by the first feedback voltage V OUT , that is, the size of the output current I FB can be determined by determining the size of the first feedback voltage V OUT . Based on this, maintaining the stability of the correspondence between the first feedback voltage V FB and the output current I OUT is particularly important for accurately determining the size of the output current I OUT . In the embodiments of the present application, since the stability of the correspondence between the first feedback voltage V FB and the output current I OUT is improved, the accuracy of determining the size of the output current I OUT is improved, thereby facilitating the convenience of subsequent debugging and power optimization of the hybrid flyback topology converter 10. For example, based on the stability of the correspondence between the first feedback voltage V FB and the output current I OUT , the moment of switching each operation mode can be accurately judged based on the first feedback voltage V FB . For example, as shown in FIG. 3, the voltage V BST, the voltage V DCM and the voltage V MAX correspond to the current I BST, the current I DCM and the current I MAX respectively, so that when the first feedback voltage V FB is less than or equal to the voltage V BST, the burst mode is entered; when the first feedback voltage V FB is less than or equal to the voltage V DCM and greater than the voltage V BST, the discontinuous conduction mode is entered; when the first feedback voltage V FB is greater than the voltage V DCM, the closed-loop mode is entered.FB entering critical conduction mode when less than or equal to voltage VMAX and greater than voltage VDCM; exiting closed loop mode when greater than voltage VMAX, thereby accurately switching between operation modes, greatly facilitating debugging and power optimization of the hybrid flyback topology converter 10. FB entering critical conduction mode when less than or equal to voltage VMAX and greater than voltage VDCM; exiting closed loop mode when greater than voltage VMAX, thereby accurately switching between operation modes, greatly facilitating debugging and power optimization of the hybrid flyback topology converter 10.

[0067] In some embodiments, the specific implementation process of outputting the second feedback voltage based on the first difference between the voltage of the input power supply and the first voltage and the first feedback voltage in step 502 includes the following steps: determining the second feedback voltage by the following formula and outputting:

[0068] V FB1 = V FB -K1x V FB x (V IN -N1x V OUT )-K2x (V IN -N1x V OUT ).

[0069] Wherein, V FB1 is the second feedback voltage, V FB is the first feedback voltage, K1 is the first preset coefficient, V IN is the voltage of the input power supply, V OUT is the output voltage, N1 is the turns ratio of the primary winding to the secondary winding, and K2 is the second preset coefficient.

[0070] The specific implementation process is shown in part of the control block diagram 20 in the control block diagram as shown in Figure 4 . Specifically, the difference between V IN and N1x V OUT is multiplied by K1 and the first feedback voltage V FB in turn on one hand, to obtain a first product; on the other hand, multiplied by K2 to obtain a second product, and then calculate the difference between the first feedback voltage V FB and the first and second products, thereby obtaining the second feedback voltage V FB1 .

[0071] It should be noted that if Figure 7 part of the control block diagram 20 is not set in the control block diagram as shown, but directly after determining the operation mode, the first feedback voltage V FB controls the first switch Q1 to be off, and the specific implementation is shown in Figure 8 . Then, in actual application, due to the fact that the devices in the circuit cannot work in an ideal state, such as the inconsistency of the on time and off time of the switch tube or the existence of the delay of the comparator, etc., all of which may cause the first feedback voltage V FB and the output current I OUTThe stability of the correspondence between them is poor, and therefore based on the first feedback voltage V FB The output current I cannot be accurately determined. OUT The accuracy of the value is not conducive to the subsequent debugging and power optimization of the hybrid flyback topology converter 10.

[0072] for example, Figure 4 An example is shown in Figure 8 When part of the control block diagram 20 is not set in the control block diagram shown, the output voltage V OUT Maintain 5V, while the input power supply V IN The first feedback voltage V is when the voltages are 150V, 200V and 400V respectively. FB With output current I OUT A schematic diagram. In which, in Figure 4 In the diagram, the horizontal axis represents the output current I. OUT The unit is amperes (A); the vertical axis represents the first feedback voltage V. FB The unit is V (volt); each straight line represents one input power supply V. IN The voltage corresponding to the first feedback voltage V FB With output current I OUT Based on the fact that the three lines do not overlap, it can be seen that... Figure 9 In the case where part of the control block diagram 20 is not set in the control block diagram shown, the first feedback voltage V FB With output current I OUT The correspondence between them will change with the input power supply V IN It changes with the voltage and is unstable, unable to adapt to different input power supplies V. IN Under the voltage, a fixed first feedback voltage V is used directly. FB To represent the output current I OUT Therefore, it is impossible to base the first feedback voltage V FB Accurately determine the timing for switching between different operating modes.

[0073] For example, Figure 4 An example is shown in Figure 9 When part of the control block diagram 20 is not set in the control block diagram shown, the input power V IN The voltage is maintained at 400V, while the output voltage V OUT The first feedback voltage V at 5V, 9V, 15V and 28V respectively FB With output current I OUT A schematic diagram. In which, in Figure 4 In the diagram, the horizontal axis represents the output current I. OUT The unit is amperes (A); the vertical axis represents the first feedback voltage V. FB The unit is V (volt); each straight line represents one output voltage V. OUTThe corresponding first feedback voltage V FB corresponds to the output current I OUT . Based on the fact that the three straight lines do not overlap, it can be seen that, in the case where the partial control block diagram 20 is not set in the control block diagram shown in FIG. 2, the correspondence between the first feedback voltage V Figure 10 corresponds to the output current I FB . OUT changes with the change of the output voltage V OUT , is unstable, and cannot be directly represented by the fixed first feedback voltage V FB corresponds to the output current I OUT under different output voltages V OUT . FB , the time for switching between the operation modes cannot be accurately determined based on the first feedback voltage V

[0074] In summary, the correspondence between the first feedback voltage V FB corresponds to the output current I OUT is not fixed, and is affected by the voltage of the input power supply V IN and the output voltage V OUT . In this case, the time for switching between the operation modes cannot be accurately determined based on the first feedback voltage V FB , which is not conducive to subsequent debugging and power optimization of the hybrid flyback topology converter 10.

[0075] However, by setting the partial control block diagram 20, the above problems can be solved to improve the stability of the correspondence between the first feedback voltage V FB corresponds to the output current I OUT . The specific description is as follows:

[0076] First of all, it is well known that, based on the structure of the hybrid flyback topology converter 10, according to the rising process of the current flowing through the primary winding LA1, the following formula can be theoretically obtained:

[0077] V COMP = T ON_HS ×(V IN -N1×V OUT ) / (L M +L R ).

[0078] Where T ON_HS is the on-time of the first switch Q1 in one period, L M is the inductance value of the primary winding LA1, and L Rthe leakage inductance of the transformer. In actual operation, due to the delay of the comparator and the turn-on delay / turn-off delay of the switch tube, etc., the above formula will be inaccurate. The influence caused by these time errors is proportional to the rising slope of the current, that is, proportional to (V IN -N1×V OUT ). Based on this, the embodiment of the present application provides a feedforward mode, by introducing (V IN -N1×V OUT ) into the control loop, and introducing two configurable parameters (i.e. the first preset coefficient K1 and the second preset coefficient K2), to adjust the corresponding relationship between the first feedback voltage V FB and the output current I OUT , and further improve the stability of the corresponding relationship between the first feedback voltage V FB and the output current I OUT .

[0079] Specifically, in some embodiments, the switch tube control method further includes the following steps: when the output current of the hybrid flyback topology converter 10 is a first current, adjusting the first preset coefficient K1 to obtain the same first feedback voltage V IN under different input power supply V OUT voltage and output voltage V FB (then the corresponding relationship between the first feedback voltage V FB and the output current I OUT can remain stable), wherein the first current is the average current when the operating mode is configured as the discontinuous conduction mode (i.e. the first current corresponds to the current IDCM in the above embodiment); when the output current of the hybrid flyback topology converter 10 is a second current, adjusting the second preset coefficient K2 to obtain the same first feedback voltage V IN under different input power supply V OUT voltage and output voltage V FB , wherein the second current is the average current when the operating mode is configured as the burst mode (i.e. the second current corresponds to the current IBST in the above embodiment).

[0080] In this embodiment, by introducing the feedforward control related to (V IN -N1×V OUT ), which is equivalent to an active reverse operation, the influence of different input power supply V IN voltage and output voltage V OUT on the corresponding relationship between the first feedback voltage V FB and the output current I OUT can be eliminated.

[0081] Figure 4 is shown inFigure 10 In the control block diagram shown, the output voltage V OUT Maintain 5V, while the input power supply V IN The first feedback voltage V when the voltages are 150V, 200V, 250V, 300V, 350V and 400V respectively. FB With output current I OUT A schematic diagram. In which, in Figure 4 In the diagram, the horizontal axis represents the output current I. OUT The unit is amperes (A); the vertical axis represents the first feedback voltage V. FB The unit is V (volt); each straight line represents one input power supply V. IN The voltage corresponds to the first feedback voltage and the output current. Based on the near overlap of the six straight lines, it can be seen that... Figure 11 In the control block diagram shown, the first feedback voltage V FB With output current I OUT The correspondence between them is relatively consistent, that is, relatively stable, and is affected by the input power supply V. IN The voltage has a relatively small impact.

[0082] Figure 4 An example is shown in Figure 11 In the control block diagram shown, the input power supply V IN The voltage is maintained at 400V, while the output voltage V OUT The first feedback voltage V at 5V, 9V, 12V, 15V, 20V and 28V respectively. FB With output current I OUT A schematic diagram. In which, in Figure 4 In the diagram, the horizontal axis represents the output current I. OUT The unit is amperes (A); the vertical axis represents the first feedback voltage V. FB The unit is V (volt); each straight line represents one output voltage V. OUT The corresponding first feedback voltage V FB With output current I OUT Based on the near overlap of the six straight lines, it can be seen that... Figure 12 In the control block diagram shown, the first feedback voltage V FB With output current I OUT The correspondence between them is relatively consistent, that is, relatively stable, and is affected by the input power supply V. IN The voltage has a relatively small impact.

[0083] In summary, the first feedback voltage V FB With output current I OUT The correspondence between them is relatively fixed and is not affected by the input power supply V. IN voltage and output voltage V OUTThe impact. In this case, it can be based on the first feedback voltage V. FB Accurately determining the timing of switching between different operating modes facilitates subsequent debugging and power optimization of the hybrid flyback topology converter 10.

[0084] In some embodiments, such as Figure 4 As shown, the specific implementation process of controlling the first switch to turn off based on the operating mode and the second feedback voltage in step 103 includes the following steps:

[0085] Step 1201: In operating mode, determine the reference voltage based on the second feedback voltage.

[0086] Specifically, in one of the following operating modes—critical conduction mode, discontinuous conduction mode, or burst mode—based on the second feedback voltage V FB1 Determine the reference voltage V COMP .

[0087] In some implementations, the specific process of determining the reference voltage based on the second feedback voltage in step 1201 under operating mode includes the following steps: when the operating mode is the critical conduction mode, the reference voltage is determined based on the following formula: V COMP =K3×V FB Among them, V COMP K is the reference voltage, and K3 is the third preset coefficient.

[0088] In some implementations, the specific process of determining the reference voltage based on the second feedback voltage in step 1201 under operating mode includes the following steps: when the operating mode is discontinuous conduction mode or burst mode, the reference voltage is determined based on the following formula: V COMP =K3×V FB ×(T SW / (T SW -T WAIT )); where T SW To control the period of the pulse width modulation signal of the first switching transistor, T WAIT The duration from the second switch being turned off to the first switch being turned on.

[0089] Step 1202: When the second voltage is greater than the reference voltage, control the first switch to turn off, wherein the second voltage is based on the voltage generated by the current flowing through the primary winding.

[0090] like Figure 13 As shown, the current flowing through the primary winding is ILA1. The current ILA1 flowing through resistor RB2 generates a second voltage. Comparator U6 converts the reference voltage VLA1 into a voltage. COMP Compare the second voltage with the reference voltage V. COMPIf VFB1> VREF1, the signal outputted to control the first switch tube Q1 is to turn off the first switch tube Q1. In addition, after the first switch tube Q1 is turned off, the first switch tube Q1 will be turned on at a specified valley of the resonant voltage in the next cycle. The specific implementation process is well known in the art, and thus is not described here. In some embodiments, the signal outputted to control the first switch tube Q1 to turn on and turn off is inputted to a module for generating a pulse width modulation signal, so as to generate a pulse width modulation signal for controlling the first switch tube Q1.

[0091] In some embodiments, the switch tube control method provided by the embodiments of the present application can also be implemented by using a digital circuit or an analog circuit. For example, a high-frequency analog-to-digital converter ADC can be used to sample the voltage of the first feedback voltage V FB ; then, the functions of the feedforward, the mode detection, and the calculation of the reference voltage V COMP in different modes can be implemented by using a digital logic circuit; then, a high-speed digital-to-analog converter DAC can be used to convert the reference voltage V COMP into an analog signal; finally, the current flowing through the primary winding LA1 is converted into an analog voltage signal, and the analog voltage signal is compared with the analog signal converted based on the reference voltage V COMP , so as to generate a signal for controlling the first switch tube Q1.

[0092] Please refer to Figure 13 , Figure 13 the schematic diagram of the composition block diagram of the controller provided by the embodiments of the present application. As shown in Figure 10 , the controller 1300 includes one or more processors 1301 and a memory 1302. In the following description, Figure 13 the processor 1301 is taken as an example.

[0093] The processor 1301 and the memory 1302 can be connected by a bus or other means, Figure 1 in which the connection by the bus is taken as an example.

[0094] The memory 1302 is a non-volatile computer readable storage medium, which can be used to store non-volatile software programs, non-volatile computer executable programs, and modules. The processor 1301 executes various function applications and data processing of the terminal interactive device by running the non-volatile software programs, instructions, and modules stored in the memory 1302, that is, implements the switch tube control method in the above method embodiments.

[0095] The memory 1302 can include high-speed random access memory and can also include nonvolatile memory, such as at least one magnetic disk storage device, flash memory device, or other nonvolatile solid-state storage device. In some embodiments, the memory 1302 can optionally include memory that is remotely located from the processor 1301, such as in a networked environment, and can be connected to the processor 1301 via a network. Examples of such networks include, but are not limited to, the Internet, intranet, local area network, mobile communications network, and combinations thereof.

[0096] The program instructions / modules are stored in the memory 1302, and when executed by the one or more processors 1301, perform the switch tube control method in any of the method embodiments described above, for example, perform the various steps described above in connection with the controller U1. Figure 5 、 Figure 12 With Figure 2 the controller U1 is implemented as the structure of the controller 1300 shown in

[0097] In some embodiments, the controller U1 is implemented as the structure of the controller 1300 shown in Figure 3 With Figure 13 the controller U1 is implemented as the structure of the controller 1300 shown in ​

[0098] The embodiments of the present application also provide a non-volatile computer readable storage medium, which stores computer executable instructions, when the computer executable instructions are executed, the switch tube control method in any of the embodiments of the present application is implemented.

[0099] The embodiments of the present application also provide a computer program product, which includes a computer program stored on a computer readable storage medium, and the computer program includes program instructions, when the program instructions are executed by a computer, the computer executes the switch tube control method in any of the embodiments of the present application.

[0100] The embodiments of the present application also provide a power adapter, which includes the hybrid flyback topology converter 10 in any of the embodiments of the present application.

[0101] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0102] ​The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; under the idea of the present application, the technical features in the above examples or different examples can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the examples of the present application.

Claims

1. A switching tube control method characterized by, The application discloses a switch control method for a hybrid flyback topology converter, and relates to the technical field of converters. The switch control method comprises the following steps: generating a first feedback voltage based on a current flowing through the optocoupler, and determining an operation mode based on the first feedback voltage; outputting a second feedback voltage based on a first difference between a voltage of the input power supply and a first voltage and the first feedback voltage, so that the same first feedback voltage can be obtained under different output voltages of the hybrid flyback topology converter and the input power supply, wherein the first voltage is a product of a turns ratio of the primary winding and the secondary winding and the output voltage; controlling the first switch to be turned off based on the operation mode and the second feedback voltage.

2. The switching tube control method according to claim 1, characterized by, The outputting of the second feedback voltage based on the first difference between the voltage of the input power supply and the first voltage and the first feedback voltage comprises the following steps: determining the second feedback voltage by the following formula and outputting the second feedback voltage: ; Wherein, V FB1 is the second feedback voltage, V FB is the first feedback voltage, K1 is a first preset coefficient, V IN is the voltage of the input power supply, V OUT is the output voltage, N1 is the turns ratio of the primary winding and the secondary winding, and K2 is a second preset coefficient.

3. The switching tube control method according to claim 2, characterized by, The switch control method further comprises the following steps: when the output current of the hybrid flyback topology converter is a first current, adjusting the first preset coefficient, so that the same first feedback voltage can be obtained under different output voltages of the hybrid flyback topology converter and the input power supply, wherein the first current is an average current when the operation mode is configured to be a discontinuous conduction mode; when the output current of the hybrid flyback topology converter is a second current, adjusting the second preset coefficient, so that the same first feedback voltage can be obtained under different output voltages of the hybrid flyback topology converter and the input power supply, wherein the second current is an average current when the operation mode is configured to be a burst mode.

4. The switching tube control method according to claim 1, characterized by, The determination of the operation mode based on the first feedback voltage comprises the following steps: determining an output power of the hybrid flyback topology converter based on the first feedback voltage; when the output power is greater than or equal to a first preset power, determining that the operation mode is a critical conduction mode, when the output power is less than the first preset power and greater than or equal to a second preset power, determining that the operation mode is a discontinuous conduction mode, and when the output power is less than the second preset power, determining that the operation mode is a burst mode, wherein the first preset power is greater than the second preset power.

5. The switching tube control method according to any one of claims 1 to 4, characterized by, The control of the first switch to be turned off based on the operation mode and the second feedback voltage comprises the following steps: determining a reference voltage based on the second feedback voltage under the operation mode; controlling the first switch to be turned off when a second voltage is greater than the reference voltage, wherein the second voltage is a voltage generated based on a current flowing through the primary winding.

6. The switching tube control method according to claim 5, characterized by, The determining, in the operation mode, the reference voltage based on the second feedback voltage comprises: The determining, in the critical conduction mode, the reference voltage based on the following formula: ； Wherein, V COMP is the reference voltage, K3 is a third preset coefficient, V FB is the first feedback voltage.

7. The switching tube control method according to claim 5, wherein The determining, in the operation mode, the reference voltage based on the second feedback voltage comprises: The determining, in the discontinuous conduction mode or the burst mode, the reference voltage based on the following formula: ； Wherein, T SW is the period of the pulse width modulation signal for controlling the first switch tube, T WAIT is the time length from the second switch tube being turned off to the first switch tube being turned on, K3 is a third preset coefficient, V FB is the first feedback voltage.

8. A hybrid flyback topology converter, characterized in that, The controller, the first switch, the second switch, the primary winding, the secondary winding, the capacitor and the optocoupler are included. The first switch and the second switch are connected in series between an input power supply and a ground, a connection point between the first switch and the second switch is connected with a same name terminal of the primary winding, the optocoupler is connected with a different name terminal of the secondary winding, the controller is connected with the first switch, the second switch and the optocoupler respectively, and the capacitor is connected in series with the primary winding and then connected in parallel with the second switch.

9. A power adapter, characterized by The hybrid flyback topology converter includes the hybrid flyback topology converter of claim 8.

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