Resonant push-pull converter control method and device and medium

Abstract

The invention discloses a resonant push-pull converter control method and device and a medium, relates to the field of resonant push-pull circuit topology, is used for reducing the no-load loss of a resonant push-pull converter, and aims to solve the problem that the overall loss of the resonant push-pull converter is relatively large when the resonant push-pull converter works under the no-load working condition in a soft switching technology. According to the control method of the resonant push-pull converter, an uncontrolled rectifying circuit is formed by body diodes in an MOS (Metal Oxide Semiconductor) tube to replace triodes in the MOS tube to transmit energy so as to ensure the realization of basic functions of the resonant push-pull converter. In addition, in the method, the low-voltage MOS tube works in a forward mode, so that the switching loss of the resonant push-pull converter is greatly reduced. And as the influence of the switching loss of the switching device on the overall loss is greater under the no-load working condition of the resonant push-pull converter, the no-load loss of the resonant push-pull converter can be greatly reduced, and the battery energy is saved.

Description

Technical Field

[0001] The present application relates to the field of resonant push-pull circuit topology, and in particular to a resonant push-pull converter control method, device and medium. Background Art

[0002] In a resonant push-pull converter, magnetic components (such as iron core inductors, transformers, etc.) are usually used to achieve AC / DC side filtering, energy storage and transmission. These magnetic components account for a large proportion of the volume, weight and cost of the converter. The higher the operating frequency of the switching device in the converter, the smaller the size of the magnetic component can be. Therefore, in order to achieve a small, light and low-cost converter, increasing the switching frequency of the switching device is an effective measure to increase the power density of the converter.

[0003] The increase in switching frequency also means that the switching loss of the converter cannot be ignored. At present, the problem of switching loss is mainly solved by a soft switching technology, which makes it possible to increase the power density of the converter by increasing the switching frequency of the converter. However, this soft switching solution is not effective in reducing switching losses when the converter is working under no-load conditions, resulting in still large no-load losses of the converter. Especially when the converter works in an inverter application scenario, excessive no-load losses will consume a large amount of battery energy, causing unnecessary losses to users.

[0004] Therefore, technicians in this field are in urgent need of a resonant push-pull converter control method to solve the current problem of large switching losses in a no-load state. Summary of the invention

[0005] The purpose of the present application is to provide a resonant push-pull converter control method, device and medium to solve the current problem of large switching losses in a no-load state.

[0006] In order to solve the above technical problems, the present application provides a resonant push-pull converter control method, which is applied to a resonant push-pull converter, wherein the primary side of the resonant push-pull converter comprises: a first MOS tube and a second MOS tube; the drain of the first MOS tube is connected to the opposite end of the first primary winding of the resonant push-pull converter, and the drain of the second MOS tube is connected to the same end of the second primary winding of the resonant push-pull converter;

[0007] The secondary side of the resonant push-pull converter includes: a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; the source of the third MOS tube and the drain of the fourth MOS tube are connected to the same-name end of the secondary winding of the resonant push-pull converter, and the source of the fifth MOS tube and the drain of the sixth MOS tube are connected to the opposite-name end of the secondary winding of the resonant push-pull converter; including:

[0008] Acquiring load information on the output side of the resonant push-pull converter;

[0009] According to the load information, determining whether the resonant push-pull converter is operating in a no-load condition;

[0010] If yes, controlling the resonant push-pull converter to operate in a no-load switching mode;

[0011] Wherein, the no-load switching mode includes: a first mode and a second mode in one switching cycle;

[0012] The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off;

[0013] The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0014] In a possible embodiment, the duration of the first mode in a switching cycle is shorter than the duration of the second mode in a switching cycle;

[0015] Furthermore, a ratio of a duration occupied by the first mode in a switching cycle to a duration occupied by the second mode in a switching cycle is greater than a preset minimum duty cycle limit value.

[0016] In a possible embodiment, acquiring load information on the output side of the resonant push-pull converter includes:

[0017] Obtaining a load current value and a load voltage value on an output load of the resonant push-pull converter;

[0018] Correspondingly, judging whether the resonant push-pull converter is operating in a no-load condition according to the load information includes:

[0019] Determine a load power value according to the load current value and the load voltage value;

[0020] If the load power value is lower than a preset power threshold, it is determined that the resonant push-pull converter is operating in a no-load condition.

[0021] In a possible embodiment, after judging whether the resonant push-pull converter is operating in a no-load condition according to the load information, the method further includes:

[0022] If not, the resonant push-pull converter is controlled to operate in a soft switching mode.

[0023] In a possible embodiment, the soft switching mode includes: a third mode, a fourth mode, a fifth mode and a sixth mode in one switching cycle;

[0024] The third mode is: controlling the first MOS tube, the third MOS tube and the sixth MOS tube to be turned on, and the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned off;

[0025] The fourth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off;

[0026] The fifth mode is: controlling the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned on, and the first MOS tube, the third MOS tube and the sixth MOS tube to be turned off;

[0027] The sixth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0028] In a possible embodiment, the ratio of the duration of the third mode in a switching cycle to the total duration of the switching cycle is close to 50%; the ratio of the duration of the fifth mode in a switching cycle to the total duration of the switching cycle is close to 50%.

[0029] In a possible embodiment, when the resonant push-pull converter operates in the soft switching mode, the circuit operating frequency of the resonant push-pull converter is greater than the natural frequency of the resonant circuit in the resonant push-pull converter.

[0030] In order to solve the above technical problems, the present application also provides a resonant push-pull converter control device, which is applied to a resonant push-pull converter, wherein the primary side of the resonant push-pull converter comprises: a first MOS tube and a second MOS tube; the drain of the first MOS tube is connected to the opposite end of the first primary winding of the resonant push-pull converter, and the drain of the second MOS tube is connected to the same end of the second primary winding of the resonant push-pull converter;

[0031] The secondary side of the resonant push-pull converter includes: a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; the source of the third MOS tube and the drain of the fourth MOS tube are connected to the same-name end of the secondary winding of the resonant push-pull converter, and the source of the fifth MOS tube and the drain of the sixth MOS tube are connected to the opposite-name end of the secondary winding of the resonant push-pull converter; including:

[0032] A load acquisition module, used to acquire load information on the output side of the resonant push-pull converter;

[0033] A working condition judgment module, used for judging whether the resonant push-pull converter is working in a no-load working condition according to the load information;

[0034] a no-load control module, configured to control the resonant push-pull converter to operate in a no-load switching mode;

[0035] Wherein, the no-load switching mode includes: a first mode and a second mode in one switching cycle;

[0036] The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off;

[0037] The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0038] In order to solve the above technical problems, the present application also provides a resonant push-pull converter control device, comprising:

[0039] Memory for storing computer programs;

[0040] A processor is used to implement the steps of the resonant push-pull converter control method as described above when executing the computer program.

[0041] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the resonant push-pull converter control method as described above are implemented.

[0042] A control method for a resonant push-pull converter provided in the present application provides a control strategy for a resonant push-pull converter operating under no-load conditions, namely, a no-load switching mode. Specifically, the no-load switching mode includes two switching modes in one switching cycle. Among them, in the first mode, the first MOS tube on the primary side is turned on, the second MOS tube is turned off, and all MOS tubes on the secondary side are turned off; at this time, the body diodes in the third MOS tube and the sixth MOS tube on the secondary side are turned on; in this process, due to the effect of the forward voltage, a forward current flows, the secondary network resonates, and energy is transferred from the battery side to the output side. In the second mode, all MOS tubes on the primary side and the secondary side are turned off, and the body diode in the second MOS tube is turned on, which is responsible for releasing the energy stored in the main transformer.

[0043] Based on the above-mentioned no-load switch mode control strategy, the low-voltage MOS tube on the primary side works in the forward mode, that is, only the first MOS tube is turned on, the second MOS tube is normally turned off, and the high-voltage MOS tubes on the secondary side are all in a normally closed state. At this time, the body diodes in each MOS tube on the secondary side constitute an uncontrolled rectifier circuit, which is responsible for transferring energy to the output side. Since the MOS tube can be regarded as consisting of a triode and a body diode, and the body diode does not have switching losses compared to the triode. When the resonant push-pull converter works under no-load conditions, the switching loss has a greater impact on the overall loss of the resonant push-pull converter. That is, in this method, the energy transfer is realized by replacing the triode with the body diode in the MOS tube on the secondary side. While ensuring the function of the resonant push-pull converter, low no-load loss can be achieved, thereby greatly reducing the loss of battery energy.

[0044] The resonant push-pull converter control device and computer-readable storage medium provided in the present application correspond to the above method and have the same effects as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 any creative work.

[0046] FIG1 is a circuit diagram of a common resonant push-pull converter;

[0047] FIG2 is a flow chart of a resonant push-pull converter control method provided by the present invention;

[0048] FIG3 is a structural diagram of a resonant push-pull converter control device provided by the present invention;

[0049] FIG. 4 is a structural diagram of another resonant push-pull converter control device provided by the present invention. DETAILED DESCRIPTION

[0050] 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.

[0051] The core of this application is to provide a resonant push-pull converter control method, device and medium.

[0052] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0053] As shown in FIG1 , a circuit structure of a common resonant push-pull converter is shown. The primary side of the resonant push-pull converter includes: a power supply Vin (generally realized by a battery) for providing energy to the resonant push-pull converter, a first MOS tube (including a transistor Q1, a body diode D1 and a parasitic capacitor Cs1), a second MOS tube Q2 (including a transistor Q2, a body diode D2 and a parasitic capacitor Cs2), a first primary winding and a second primary winding.

[0054] MOS: MOSFET, the full name is metal-oxide semiconductor field effect transistor, abbreviated as field effect tube or MOS tube.

[0055] Among them, the positive electrode of the power supply Vin is connected to the drain of the first MOS tube through the first primary winding, the source of the first MOS tube is grounded, and the same-name end of the first primary winding is correspondingly connected to the positive electrode of the power supply Vin; the positive electrode of the power supply Vin is also connected to the drain of the second MOS tube through the second primary winding, the source of the second MOS tube is grounded, and the same-name end of the second primary winding is correspondingly connected to the drain of the second MOS tube.

[0056] The secondary side of the resonant push-pull converter includes: a secondary winding, a resonant inductor Lr, a resonant capacitor Cr, a third MOS tube (including a transistor Q3 and a body diode D3), a fourth MOS tube (including a transistor Q4 and a body diode D4), a fifth MOS tube (including a transistor Q5 and a body diode D5), a sixth MOS tube (including a transistor Q6 and a body diode D6), an output filter capacitor Co and an output load RL.

[0057] Among them, the same-name end of the secondary winding is connected to the source of the third MOS tube and the drain of the fourth MOS tube through the series-connected resonant inductor Lr and the resonant capacitor Cr; the opposite-name end of the secondary winding is connected to the source of the fifth MOS tube and the drain of the sixth MOS tube; the drain of the third MOS tube and the source of the fourth MOS tube are connected to the first end of the output load RL, and the drain of the fifth MOS tube and the source of the sixth MOS tube are connected to the second end of the output load RL; the output filter capacitor Co is connected in parallel to both ends of the output load RL.

[0058] For the above-mentioned resonant push-pull converter, since it realizes AC / DC side filtering, energy storage and transmission through magnetic components (such as iron core inductors, transformers, etc.), these magnetic components account for a large proportion of the volume, weight and cost of the converter. The higher the operating frequency of the switching device in the converter, the smaller the size of the magnetic component can be. Therefore, in order to achieve a small, light and low-cost converter, increasing the switching frequency of the switching device is an effective measure to increase the power density of the converter.

[0059] At present, the problem of switching loss is mainly solved by a soft switching solution. The soft switching solution can achieve zero voltage and zero current switching of the resonant push-pull converter, thereby increasing the operating frequency of the resonant push-pull converter, thereby reducing the volume and improving efficiency. However, this soft switching solution is not effective in reducing switching losses when the converter is working under no-load conditions, resulting in still large no-load losses of the converter. Especially when the converter works in an inverter application scenario, excessive no-load losses will consume a large amount of battery energy, causing unnecessary losses to users.

[0060] To solve this problem, the present application provides a resonant push-pull converter control method, which is applied to a common resonant push-pull converter as shown in FIG1 . The method is shown in FIG2 , and includes:

[0061] S10: Obtaining load information on the output side of the resonant push-pull converter.

[0062] S20: judging whether the resonant push-pull converter is operating in a no-load condition according to the load information; if so, proceeding to step S30.

[0063] S30: Control the resonant push-pull converter to operate in a no-load switching mode.

[0064] The no-load switching mode includes: a first mode and a second mode in one switching cycle.

[0065] The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0066] The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0067] Among them, step S10 and step S20 are the working condition judgment process before the resonant push-pull converter is formally controlled to work, which is used to judge whether the resonant push-pull converter is working in the no-load mode, so as to decide whether to adopt the no-load switching mode in step S30 of this method as the control strategy of the resonant push-pull converter. It is easy to know that the judgment of whether the resonant push-pull converter is working in the no-load mode mainly depends on the load size on the output side of the resonant push-pull converter, and there are currently many mature technical solutions for the detection and judgment of the load size on the output side of devices such as transformers, which are not limited in this embodiment.

[0068] Step S30 is a control strategy provided by the method for the application scenario of the resonant push-pull converter working in no-load condition. Since the switching loss accounts for a large proportion of the overall loss when the resonant push-pull converter works in no-load condition, the purpose of providing the no-load switching mode in the method is to reduce the switching loss while ensuring the normal function of the resonant push-pull converter.

[0069] Specifically, in order to reduce the switching loss when no-load, when the load of the resonant push-pull converter is light, the low-voltage MOS tube on the primary side works in the forward mode; that is, only the first MOS tube is turned on, the second MOS tube is normally turned off, and the high-voltage MOS tubes (the third, fourth, fifth, and sixth MOS tubes) on the secondary side are all in a normally closed state; at this time, the body diodes D3~D6 in the third, fourth, fifth, and sixth MOS tubes constitute an uncontrolled rectifier circuit, which is responsible for transferring energy to the output side to ensure the realization of the basic functions of the resonant push-pull converter.

[0070] It is particularly important to note that, as can be seen from the above, the MOS tube can be regarded as a combination of a triode and a body diode, and the conduction control of the MOS tube is mainly the conduction control of the triode, and the conduction of the body diode is only related to the potential difference between its two ends. Therefore, the conduction and shutdown control of each MOS tube in the above no-load switching mode is actually to control the conduction and shutdown of the triode in each MOS tube. And the conduction of the diode in the MOS tube is not controlled, and is only related to the potential difference between its two ends.

[0071] Based on this, the no-load switch mode in step S30 is specifically:

[0072] First mode: Q1 is on, Q2~Q6 are off, and D3 and D6 are on.

[0073] At this time, due to the effect of the forward voltage, the forward current flows, the secondary network resonates, and energy is transferred from the battery side to the output side.

[0074] Second mode: Q1~Q6 are turned off, and D2 is turned on.

[0075] At this time, D2 is responsible for releasing the energy stored in the main transformer.

[0076] Based on the alternation of the first mode and the second mode, the energy output of the resonant push-pull converter to the load is achieved.

[0077] It can be seen that the no-load switching mode of the present method transmits energy by replacing the conduction of the MOS transistor with the conduction of the body diode in the MOS tube to ensure the realization of the basic functions of the resonant push-pull converter. In addition, in the no-load switching mode provided by the present method, only the transistor Q1 in the first MOS tube needs to be controlled to be turned on, and the transistors Q2~Q5 in the remaining MOS tubes are all in a normally off state. That is, only the transistor Q1 will have switching losses. Compared with the control scheme that the soft switching scheme needs to rely on the complementary conduction of the first MOS tube and the second MOS tube on the low-voltage side and the complementary conduction of the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube on the high-voltage side, the switching loss caused by the switching state of the transistor in the MOS tube is greatly reduced, so that the no-load loss of the resonant push-pull converter can be reduced to more than half of the original, greatly reducing the energy loss of the battery as a power source.

[0078] Further, it can be seen from the above that the key to reducing the energy loss of the resonant push-pull converter under no-load conditions is to reduce the switching loss of the switching device in the resonant push-pull converter. Based on this, this embodiment also provides a further implementation scheme:

[0079] The duration of the first mode in a switching cycle is shorter than the duration of the second mode in a switching cycle, and the ratio of the duration of the first mode in a switching cycle to the duration of the second mode in a switching cycle is greater than a preset minimum duty cycle limit value.

[0080] It should be noted that in the no-load switching mode provided by the present method, only the transistor Q1 in the first MOS tube needs to be controlled to be turned on, and the transistors Q2 to Q5 in the other MOS tubes are all in a normally off state, that is, only the transistor Q1 will have switching losses. Therefore, reducing the switching losses of the transistor Q1 can further reduce the no-load losses of the resonant push-pull converter.

[0081] In the above embodiment, the present application does not limit the proportion of the duration of the first mode and the second mode in the entire switching cycle. A possible implementation is that the first mode and the second mode each occupy 50% of the entire switching cycle. However, this embodiment provides a small duty cycle solution, which controls the conduction time of the transistor Q1 in the first MOS tube to be less than 50% of the entire switching cycle, that is, the conduction time of the transistor Q1 is reduced, thereby achieving the purpose of reducing the conduction loss of the transistor Q1.

[0082] Generally speaking, the shorter the conduction time of transistor Q1, the smaller the no-load loss of the resonant push-pull converter. However, it should be noted that the conduction time of transistor Q1 cannot be too short, otherwise the energy output function of the resonant push-pull converter cannot be normally realized, so the proportion of the conduction time of transistor Q1 in the entire switching cycle must be at least greater than the preset minimum duty cycle limit value. It should be noted that the above-mentioned minimum duty cycle limit value is a preset value, which can be obtained based on the experience of the designer or experimental simulation, and this embodiment does not limit this.

[0083] In summary, this embodiment controls the transistor Q1 in the first MOS tube to operate in a small duty cycle mode to reduce the switching loss caused by the conduction of the transistor Q1, thereby achieving the purpose of further reducing the no-load loss of the resonant push-pull converter.

[0084] On the other hand, the above embodiment illustrates that the present application does not limit the specific scheme for determining whether the resonant push-pull converter operates in a no-load condition, but this embodiment provides a possible implementation scheme, and step S10 specifically includes:

[0085] Obtain the load current value and load voltage value on the output load of the resonant push-pull converter.

[0086] Correspondingly, step S20: judging whether the resonant push-pull converter is operating in a no-load condition according to the load information specifically includes:

[0087] S21: Determine a load power value according to a load current value and a load voltage value.

[0088] S22: If the load power value is lower than the preset power threshold, it is determined that the resonant push-pull converter is operating in a no-load condition.

[0089] Among them, the specific value of the power threshold in step S22 is not limited in this embodiment, and a suitable value can be taken according to different actual working conditions. That is, when the power of the output load exceeds the power threshold, it can be considered that the resonant push-pull converter is working in a heavy-load condition; when the power of the output load is less than or equal to the power threshold, it is considered that the resonant push-pull converter is working in a no-load condition (or light-load condition); at this time, the power threshold can be set according to the conditions for distinguishing between heavy-load conditions and no-load conditions in actual application scenarios.

[0090] Or in another possible embodiment, the no-load condition and the heavy-load condition are distinguished based on whether the conduction loss of the switching device in the resonant push-pull converter has a greater impact on the overall loss or the switching loss has a greater impact on the overall loss. When the resonant push-pull converter is in a no-load condition, the switching loss of the switching device in the resonant push-pull converter has a greater impact on the overall loss, and when the resonant push-pull converter is in a heavy-load condition, the conduction loss of the switching device in the resonant push-pull converter has a greater impact on the overall loss. In other words, the switching loss of the switching device has a greater impact on the no-load loss, and the conduction loss has a greater impact on the heavy-load loss. Based on this working condition distinction standard, it can be judged through simulation or actual measurement that at a certain load power limit value, there is a difference in whether the overall loss is greatly affected by the conduction loss or the switching loss of the switching device, and then the power threshold is determined based on the load power limit value. Exemplarily, in a possible application scenario, the power threshold can be 500W.

[0091] It should also be noted that, from the above, it can be seen that the key factors affecting the overall energy loss of the resonant push-pull converter under different load conditions are different. The switching loss of the switching device has a greater impact on the no-load loss, and the conduction loss has a greater impact on the heavy-load loss. The no-load switching mode provided in the present application is to transmit energy by the conduction of the body diode in the MOS tube instead of the conduction of the transistor, and the conduction loss of the body diode is greater than the conduction loss of the transistor. Therefore, under heavy load conditions, the no-load switching mode is not as good as the soft switching mode in terms of overall energy loss. Therefore, before implementing the no-load switching mode, this embodiment first judges the load condition of the resonant push-pull converter, and only implements the no-load switching mode under no-load conditions to achieve the purpose of reducing no-load power consumption.

[0092] As can be seen from the above, this embodiment determines whether the resonant push-pull converter is operating in a no-load condition by obtaining the power on the output load of the resonant push-pull converter. This enables accurate judgment of the load condition of the resonant push-pull converter, and ensures that only in the no-load condition where the switching loss has a greater impact on the overall loss of the resonant push-pull converter, the no-load loss is reduced by reducing the switching loss of the switching device through the no-load switching mode.

[0093] It can be seen from the above embodiments that the no-load switching mode provided by the present application can reduce the overall loss of the resonant push-pull converter under no-load conditions, but under heavy-load conditions, the effect is not as good as the soft switching mode. Based on this, this embodiment also provides a possible implementation scheme. After the above step S20, if the no branch is entered, that is, the resonant push-pull converter is operating under heavy-load conditions, as shown in Figure 2, the method further includes:

[0094] S40: Control the resonant push-pull converter to operate in soft switching mode.

[0095] It should be noted that since soft switching technology is a mature technology and is used in various fields, based on the main idea of ​​achieving zero voltage and zero current switching through soft opening, there may be many variant schemes in the specific implementation details. This embodiment does not limit this, and a suitable implementation scheme can be selected according to actual needs.

[0096] However, this embodiment also provides a specific control strategy for a resonant push-pull converter operating in a soft switching mode. The soft switching mode includes: a third mode, a fourth mode, a fifth mode and a sixth mode in one switching cycle.

[0097] The third mode is: controlling the first MOS tube, the third MOS tube and the sixth MOS tube to be turned on, and the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned off.

[0098] The fourth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0099] The fifth mode is: controlling the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned on, and the first MOS tube, the third MOS tube and the sixth MOS tube to be turned off.

[0100] The sixth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0101] It should be noted that, as can be seen from the above, the MOS tube can be regarded as a combination of a triode and a body diode, and the conduction state of the body diode is only related to the voltage across it, so the control of the MOS tube generally refers to the control of the triode in the MOS tube. Therefore, the conduction control of the MOS tube in each mode in the above soft switching mode is also the conduction control of the triode in the corresponding MOS tube. However, because the soft switching mode does not adopt the method of transmitting energy by replacing the conduction of the triode with the conduction of the body diode, the conduction control of the MOS tube and the conduction control of the triode can be regarded as an equivalent relationship in the soft switching mode. That is:

[0102] The third mode: the primary side Q1 is turned on, Q2 is turned off, the secondary side Q3 and Q6 are turned on, and Q4 and Q5 are turned off.

[0103] In this process, due to the action of the forward voltage, the forward current flows, the secondary network resonates, and the energy is transferred from the battery side to the output side.

[0104] Fourth mode: Q1~Q6 are turned off.

[0105] At this time, the current flowing through the power tube is relatively large, but because the power tube is connected in parallel with a large capacitor, Q1 is turned off at zero voltage. Since the time when the two tubes are turned off at the same time is relatively short, it can be considered that during this period, the resonant current remains unchanged, and the resonant current linearly charges the parasitic capacitance Cs1 of the first MOS tube to 2 times the power supply voltage, and the parasitic capacitance Cs2 of the second MOS tube is linearly discharged to zero.

[0106] The fifth mode: the primary side Q2 is turned on, Q1 is turned off, the secondary side Q4 and Q5 are turned on, and Q3 and Q6 are turned off.

[0107] This process is the same as the third mode, and can also achieve zero voltage turn-on of Q2.

[0108] Sixth mode: Q1~Q6 are turned off.

[0109] This process is the same as the fourth mode, and can also achieve zero voltage shutdown of Q2. The resonant current linearly charges the parasitic capacitance Cs2 of the second MOS tube to twice the power supply voltage, and the parasitic capacitance Cs1 of the first MOS tube linearly discharges to zero.

[0110] Furthermore, for the duration of the above modes in the working cycle, this embodiment also provides a possible implementation scheme:

[0111] The ratio of the duration of the third mode in a switching cycle to the total duration of the switching cycle is close to 50%. The ratio of the duration of the fifth mode in a switching cycle to the total duration of the switching cycle is close to 50%.

[0112] That is, the duty cycles of the first MOS tube to the sixth MOS tube are all close to 50%, but cannot reach 50% to achieve the optimal power output effect.

[0113] In addition, this embodiment provides another preferred implementation scheme: when the resonant push-pull converter operates in the soft switching mode, the circuit operating frequency of the resonant push-pull converter is greater than the natural frequency of the resonant circuit in the resonant push-pull converter.

[0114] As shown in FIG1 , the resonant push-pull converter has a resonant network composed of a resonant inductor Lr and a resonant capacitor Cr, so it is called a resonant push-pull converter. This embodiment realizes the soft switching operation mode of the circuit and ensures that the transformer will not be saturated when working, so the circuit is operated at (i.e., circuit operating frequency Greater than the natural frequency of the resonant circuit ) conditions. Since the circuit operating frequency is higher than the resonant frequency, the resonant circuit composed of inductance and capacitance is inductive, which can achieve soft switching mode, improve efficiency, and reduce electromagnetic interference (EMI) and noise generation.

[0115] It can be seen that the soft switching mode provided in this embodiment reduces the switching loss of the switching device by realizing the zero voltage turn-on and zero voltage turn-off of the MOS tube. Although the effect of reducing the switching loss is not as good as the no-load switching mode provided in the above embodiment, it is better than the traditional hard switching mode. In addition, since the soft switching mode provided in this embodiment does not need to replace the conduction of the triode to transmit energy through the conduction of the body diode in the MOS tube, and the conduction loss of the triode is lower than the conduction loss of the body diode, the conduction loss of the soft switching mode is significantly lower than the no-load switching mode. When the resonant push-pull converter operates under heavy load conditions, the conduction loss has a greater impact on the overall loss of the resonant push-pull converter, so that the soft switching mode has better performance in reducing the overall power consumption of the resonant push-pull converter than the no-load switching mode. That is, this embodiment, combined with the solution provided in the above embodiment, provides a load condition based on the resonant push-pull converter to make the resonant push-pull converter work in the no-load switching mode and the soft switching mode respectively, so that in each load condition, it can bring the minimum energy loss and save battery energy.

[0116] In the above embodiment, a resonant push-pull converter control method is described in detail, and the present application also provides a corresponding embodiment of a resonant push-pull converter control device. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is based on the functional module perspective, and the other is based on the hardware perspective.

[0117] From the perspective of functional modules, as shown in FIG3 , this embodiment provides a resonant push-pull converter control device, including:

[0118] A load acquisition module 11, used to acquire load information on the output side of the resonant push-pull converter;

[0119] The working condition judgment module 12 is used to judge whether the resonant push-pull converter is working in a no-load working condition according to the load information;

[0120] A no-load control module 13, for controlling the resonant push-pull converter to operate in a no-load switching mode if yes;

[0121] Wherein, the no-load switching mode includes: a first mode and a second mode in one switching cycle;

[0122] The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off;

[0123] The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

[0124] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0125] FIG4 is a structural diagram of a resonant push-pull converter control device provided by another embodiment of the present application. As shown in FIG4 , a resonant push-pull converter control device includes: a memory 20 for storing a computer program;

[0126] The processor 21 is used to implement the steps of a resonant push-pull converter control method as described in the above embodiment when executing a computer program.

[0127] The resonant push-pull converter control device provided in this embodiment may include but is not limited to a mobile terminal, a personal computer, a workstation, etc.

[0128] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0129] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, it can implement the relevant steps of a resonant push-pull converter control method disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. Data 203 may include, but is not limited to, a resonant push-pull converter control method, etc.

[0130] In some embodiments, a resonant push-pull converter control device may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power supply 25 , and a communication bus 26 .

[0131] Those skilled in the art will appreciate that the structure shown in FIG. 4 does not constitute a limitation on a control device for a resonant push-pull converter, and may include more or fewer components than those shown in the figure.

[0132] A resonant push-pull converter control device provided in an embodiment of the present application includes a memory and a processor. When the processor executes a program stored in the memory, it can implement the following method: a resonant push-pull converter control method.

[0133] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the above method embodiment are implemented.

[0134] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0135] The above is a detailed introduction to a resonant push-pull converter control method, device and medium provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can refer to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the present application.

[0136] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A resonant push-pull converter control method, applied to a resonant push-pull converter, wherein the primary side of the resonant push-pull converter comprises: A first MOS transistor and a second MOS transistor; the drain of the first MOS transistor is connected to the opposite end of the first primary winding of the resonant push-pull converter, and the drain of the second MOS transistor is connected to the same end of the second primary winding of the resonant push-pull converter; The secondary side of the resonant push-pull converter comprises: a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; the source of the third MOS tube and the drain of the fourth MOS tube are connected to the same-name end of the secondary winding of the resonant push-pull converter, and the source of the fifth MOS tube and the drain of the sixth MOS tube are connected to the opposite-name end of the secondary winding of the resonant push-pull converter; it is characterized in that it comprises: Acquiring load information on the output side of the resonant push-pull converter; According to the load information, determining whether the resonant push-pull converter is operating in a no-load condition; If yes, controlling the resonant push-pull converter to operate in a no-load switching mode; Wherein, the no-load switching mode includes: a first mode and a second mode in one switching cycle; The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off; The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

2. The resonant push-pull converter control method according to claim 1, characterized in that: The duration of the first mode in a switching cycle is shorter than the duration of the second mode in a switching cycle; Furthermore, a ratio of a duration occupied by the first mode in a switching cycle to a duration occupied by the second mode in a switching cycle is greater than a preset minimum duty cycle limit value.

3. The resonant push-pull converter control method according to claim 2, characterized in that: Acquiring load information on the output side of the resonant push-pull converter includes: Obtaining a load current value and a load voltage value on an output load of the resonant push-pull converter; Correspondingly, judging whether the resonant push-pull converter is operating in a no-load condition according to the load information includes: Determine a load power value according to the load current value and the load voltage value; If the load power value is lower than a preset power threshold, it is determined that the resonant push-pull converter is operating in a no-load condition.

4. The resonant push-pull converter control method according to any one of claims 1 to 3, characterized in that: After determining whether the resonant push-pull converter is operating in a no-load condition according to the load information, the method further includes: If not, the resonant push-pull converter is controlled to operate in a soft switching mode.

5. The resonant push-pull converter control method according to claim 4, characterized in that: The soft switching mode includes: a third mode, a fourth mode, a fifth mode and a sixth mode in one switching cycle; The third mode is: controlling the first MOS tube, the third MOS tube and the sixth MOS tube to be turned on, and the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned off; The fourth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off; The fifth mode is: controlling the second MOS tube, the fourth MOS tube and the fifth MOS tube to be turned on, and the first MOS tube, the third MOS tube and the sixth MOS tube to be turned off; The sixth mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

6. The resonant push-pull converter control method according to claim 5, characterized in that: The ratio of the duration of the third mode in one switching cycle to the total duration of the switching cycle is close to 50%; the ratio of the duration of the fifth mode in one switching cycle to the total duration of the switching cycle is close to 50%.

7. The resonant push-pull converter control method according to claim 4, characterized in that: When the resonant push-pull converter operates in the soft switching mode, the circuit operating frequency of the resonant push-pull converter is greater than the natural frequency of the resonant circuit in the resonant push-pull converter.

8. A resonant push-pull converter control device, applied to a resonant push-pull converter, wherein the primary side of the resonant push-pull converter comprises: A first MOS transistor and a second MOS transistor; the drain of the first MOS transistor is connected to the opposite end of the first primary winding of the resonant push-pull converter, and the drain of the second MOS transistor is connected to the same end of the second primary winding of the resonant push-pull converter; The secondary side of the resonant push-pull converter comprises: a third MOS tube, a fourth MOS tube, a fifth MOS tube and a sixth MOS tube; the source of the third MOS tube and the drain of the fourth MOS tube are connected to the same-name end of the secondary winding of the resonant push-pull converter, and the source of the fifth MOS tube and the drain of the sixth MOS tube are connected to the opposite-name end of the secondary winding of the resonant push-pull converter; it is characterized in that it comprises: A load acquisition module, used to acquire load information on the output side of the resonant push-pull converter; A working condition judgment module, used for judging whether the resonant push-pull converter is working in a no-load working condition according to the load information; a no-load control module, configured to control the resonant push-pull converter to operate in a no-load switching mode; Wherein, the no-load switching mode includes: a first mode and a second mode in one switching cycle; The first mode is: controlling the first MOS tube to be turned on, and the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off; The second mode is: controlling the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube to be turned off.

9. A resonant push-pull converter control device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the resonant push-pull converter control method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the resonant push-pull converter control method according to any one of claims 1 to 7 are implemented.

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