Voltage conversion circuit applicable to wide input voltage range and voltage converter

Abstract

The invention discloses a voltage conversion circuit applicable to a wide input voltage range and a voltage converter. The voltage conversion circuit comprises a self-oscillation module, a control module and a transformer T1, wherein the output end of the control module is connected with the self-oscillation module, and the self-oscillation module is connected with the input end of the transformer T1; the output end of the transformer T1 is connected with the load and the power end of the control module. When input voltage VIN is input to the input end of the transformer T1, the self-oscillation module and the transformer T1 form an oscillation circuit, so that the output end of the transformer T1 generates voltage. The control module is powered on to operate based on the voltage of the output end of the transformer T1 and takes over control over the voltage of the output end of the transformer T1, so that the voltage of the output end of the transformer T1 is the voltage required by the load and supplies power to the load. The problem that when the input voltage is low, the voltage conversion circuit cannot be normally started and operated is solved.

Description

Technical Field

[0001] The present application relates to the technical field of voltage conversion control, and in particular, to a voltage conversion circuit and a voltage converter applicable to a wide input voltage range. Background Art

[0002] Voltage converters can be used for voltage conversion in various scenarios, mainly including types such as DC-DC converters, AC-DC converters, and DC-AC converters. Different types of voltage converters have different functions and are widely used in fields such as industrial control, household appliances, communication equipment, automotive electronics, and renewable energy systems.

[0003] The working process of a voltage converter is generally as follows: First, a control chip (MCU or MOS drive chip) is started according to the input voltage of the voltage converter. After the control chip is powered on and operates, the corresponding components in the voltage converter are then controlled to achieve the voltage conversion function of the voltage converter. However, if the input voltage of the voltage converter is too low during the power-on startup stage, the control chip cannot be normally started, and the voltage converter cannot be normally started and operated.

[0004] Taking the DC-DC converter in the voltage converter as an example, it mainly includes three basic topology types: BUCK, BOOST, and BUCK-BOOST, as well as a traditional self-excited oscillation boost structure. For example, Figure 1 As shown, it is a schematic diagram of a BUCK-BOOST topology structure with step-up and step-down functions. Its working process is to start the control chip based on the input voltage. After the control chip is powered on and operates, the on / off of the switch tube S is controlled to adjust the output power of the converter. When the DC-DC converter is applied in the new energy energy storage field, its input voltage is provided by a photovoltaic power generation system. Since the photovoltaic power generation system is a photovoltaic array formed by connecting multiple photovoltaic modules in series, the difference in power generation capabilities between each photovoltaic module and the occlusion of some photovoltaic modules will cause the output voltage of the photovoltaic power generation system to fluctuate continuously. When some photovoltaic modules are severely occluded, the output voltage of the photovoltaic power generation system can even reach only 1V. In this case, the output voltage of the photovoltaic power generation system is lower than the startup voltage of the control chip, and the control chip cannot be normally started, which will even lead to incorrect control of the switch tube S and communication interruption of the subsequent electrical load (such as a disconnector, an optimizer).

[0005] Therefore, during the use of a voltage converter, there are still the following problems: If the input voltage of the voltage converter is lower than the startup voltage of the control chip during the power-on startup stage, the control chip cannot be normally started, and the voltage converter cannot be normally started and operated. Summary of the Invention

[0006] To solve the problem that the existing voltage converters cannot start and operate normally when the input voltage is low, the present application provides a voltage conversion circuit and a voltage converter applicable to a wide input voltage range.

[0007] In a first aspect, the present application provides a voltage conversion circuit applicable to a wide input voltage range. The voltage conversion circuit includes: a self-oscillation module, a control module, and a transformer T1; wherein, the output end of the control module is connected to the self-oscillation module, and the self-oscillation module is connected to the input end of the transformer T1; the output end of the transformer T1 is respectively connected to a load and the power supply end of the control module; When an input voltage VIN is applied to the input end of the transformer T1, the self-oscillation module and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; the control module powers on and operates based on the voltage at the output end of the transformer T1, and takes over the control of the voltage at the output end of the transformer T1, so that the voltage at the output end of the transformer T1 is the voltage required by the load, and powers the load.

[0008] By adopting the above technical solution, a combination of two methods, namely oscillation output and control module control output, is adopted. When the circuit has a power input, first, the self-oscillation module and the transformer T1 form an oscillation circuit to self-start. At this time, no chip control is required, and only the magnetic coupling of the transformer T1 is used to generate oscillation to power the control module, so that the control module can start and operate normally when the input voltage VIN is high or low. Then, it takes over the control of the voltage at the output end of the transformer T1 and powers the load, which well solves the problem that the circuit cannot start and operate normally when the input voltage is low, and enables the voltage conversion circuit to be used in a wide input voltage range.

[0009] In a specific feasible embodiment, the self-oscillation module includes an oscillation driving module and an oscillation enabling module; When an input voltage VIN is applied to the input end of the transformer T1, the oscillation driving module and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; The control module is used to, when taking over the control of the voltage at the output end of the transformer T1, control the transformer T1 to stop oscillating through the oscillation enabling module, and also control the voltage at the output end of the transformer T1 through the oscillation driving module, so that the voltage at the output end of the transformer T1 is the voltage required by the load.

[0010] In a specific feasible embodiment, the voltage conversion circuit further includes a first output voltage control module; The first output voltage control module is connected between the output terminal of the transformer T1 and the power supply terminal of the control module, and is used to convert the voltage at the output terminal of the transformer T1 into the voltage required for the control module to operate after being powered on.

[0011] In a specific feasible implementation, the voltage conversion circuit further includes a second output voltage control module; The second output voltage control module is connected between the output terminal of the transformer T1 and the load, and is used to stabilize the voltage at the output terminal of the transformer T1 to the voltage required by the load.

[0012] By adopting the above technical solution, by adding a second output voltage control module, the stability of the output voltage of the transformer T1 is further ensured, and voltage fluctuations are avoided.

[0013] In a specific feasible implementation, the oscillation driving module includes a resistor R1, a resistor R2, a switching transistor Q1, and a switching transistor Q2; Among them, the same-named end of the first primary winding of the transformer T1 and the different-named end of the second primary winding are both connected to the input voltage VIN; the different-named end of the first primary winding of the transformer T1 is connected to the driving end of the switching transistor Q1 through the resistor R1 and the resistor R2; the first end of the switching transistor Q1 is connected to the intermediate node of the resistor R1 and the resistor R2; the second end of the switching transistor Q1 is connected to the driving end of the switching transistor Q2; the first end of the switching transistor Q2 is connected to the same-named end of the second primary winding of the transformer T1, and the second end of the switching transistor Q2 is grounded.

[0014] In a specific feasible implementation, the oscillation enabling module includes a switching transistor Q3; Among them, the driving end of the switching transistor Q3 is connected to the control module, the first end of the switching transistor Q3 is connected to the driving end of the switching transistor Q1, and the second end of the switching transistor Q3 is grounded.

[0015] In a specific feasible implementation, the first output voltage control module includes a series-connected resistor R4 and a voltage stabilizing diode ZD1; Among them, the power supply terminal of the control module is connected to the intermediate node of the resistor R4 and the voltage stabilizing diode ZD1, the end of the resistor R4 that is not connected to the voltage stabilizing diode ZD1 is connected to an output terminal of the transformer T1, and the end of the voltage stabilizing diode ZD1 that is not connected to the resistor R4 is connected to the other output terminal of the transformer T1.

[0016] By adopting the above technical solution, by using the voltage stabilizing effect of the voltage stabilizing diode ZD1 and the voltage dividing effect of the resistor R4, the voltage input to the power supply terminal of the control module is the voltage required for the normal operation of the control module.

[0017] In a specific feasible implementation, the output end of the control module is connected to the driving end of the switching transistor Q2; The control module is configured to adjust the voltage at the output end of the transformer T1 by controlling the on-off time of the switching transistor Q2.

[0018] In a specific feasible implementation, the second output voltage control module includes a voltage stabilizing diode ZD2; One end of the voltage stabilizing diode ZD2 is connected to one output end of the transformer T1, and the other end of the voltage stabilizing diode ZD2 is connected to the other output end of the transformer T1.

[0019] In a second aspect, the present application provides a voltage converter, adopting the following technical solution: The voltage converter includes the voltage conversion circuit applicable to a wide input voltage range in the above first aspect or any feasible implementation of the first aspect.

[0020] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1. By combining the two methods of oscillating output and control module control output, when the circuit has a power input, first, the self-oscillation module and the transformer T1 form an oscillation circuit to start self-starting. At this time, no chip control is required, and only the magnetic coupling of the transformer T1 is used to generate oscillation to supply power to the control module, so that the control module can start and operate normally when the input voltage VIN is high or low, and then take over the control of the voltage at the output end of the transformer T1 to supply power to the load, which well solves the problem that the circuit cannot start and operate normally when the input voltage is low, and enables the voltage conversion circuit to be used in a wider input voltage range; 2. After the control module is powered on and runs, on the one hand, it controls the oscillation output of the stop circuit, and on the other hand, based on the input voltage VIN, it directly controls the output of the transformer T1 through the self-oscillation module. The control module takes over the output control of the voltage conversion circuit, and can also flexibly adjust the voltage at the output end of the transformer T1 according to the actual needs of the load to achieve step-up or step-down output, ensuring the stable operation of the circuit and improving the reliability of the circuit. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the BUCK-BOOST topology structure in the prior art; Figure 2 is a schematic diagram of the traditional self-excited oscillation boost topology structure in the prior art; Figure 3 is a connection schematic diagram of the voltage conversion circuit in the embodiment of the present application; Figure 4 is another connection schematic diagram of the voltage conversion circuit in the embodiment of the present application; Figure 5 This is a schematic diagram of a specific implementation circuit of the voltage conversion circuit in an embodiment of the present application.

[0022] Description of the reference numerals: 1. Self-oscillation module; 101. Oscillation driving module; 102. Oscillation enabling module; 2. Control module; 3. First output voltage control module; 4. Second output voltage control module; 5. Signal amplification module; 6. Rectification module; 7. Overvoltage protection module; 8. Anti-backflow protection module; 9. First filtering module; 10. Second filtering module. Detailed implementation manners

[0023] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0024] In the description of the embodiments of the present application, words such as "for example" or "for illustration" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "for example" or "for illustration" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Specifically, the use of words such as "for example" or "for illustration" is intended to present relevant concepts in a specific manner.

[0025] In the description of the embodiments of the present application, the term "a plurality of" means two or more. For example, a plurality of systems means two or more systems, and a plurality of screen terminals means two or more screen terminals. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the technical features indicated. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The terms "include", "comprise", "have" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0026] Referring to Figure 2 , it is a traditional self-excited oscillation boost topology structure. In this topology structure, self-excited oscillation is formed through the coil windings of the transformer and the cut-off, amplification, and saturation of the triode. This self-excited oscillation structure is simple and can raise the input low voltage and output it. However, there are problems such as inability to step down, the output voltage cannot be adjusted according to the actual situation, and the oscillation frequency is easily affected by temperature, resulting in a low conversion efficiency or stopping oscillation and no output. The conversion efficiency and stability are relatively low.

[0027] The embodiments of the present application provide a voltage conversion circuit applicable to a wide input voltage range, such asFigure 3 As shown, the voltage conversion circuit includes: a self-oscillation module 1, a control module 2, and a transformer T1; Among them, the output end of the control module 2 is connected to the self-oscillation module 1, and the self-oscillation module 1 is connected to the input end of the transformer T1; the output end of the transformer T1 is respectively connected to the load and the power supply end of the control module 2; When an input voltage VIN is applied to the input end of the transformer T1, the self-oscillation module 1 and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; the control module 2 powers on and operates based on the voltage at the output end of the transformer T1, and takes over the control of the voltage at the output end of the transformer T1, so that the voltage at the output end of the transformer T1 is the voltage required by the load and supplies power to the load.

[0028] Preferably, the control module 2 is an MCU.

[0029] In a possible implementation manner, referring to Figures 4 - 5 , the self-oscillation module 1 includes an oscillation driving module 101 and an oscillation enabling module 102; When an input voltage VIN is applied to the input end of the transformer T1, the oscillation driving module 101 and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; The control module 2 is used to control the transformer T1 to stop oscillating through the oscillation enabling module 102 when taking over the control of the voltage at the output end of the transformer T1, and control the voltage at the output end of the transformer T1 through the oscillation driving module 101, so that the voltage at the output end of the transformer T1 is the voltage required by the load.

[0030] Specifically, the oscillation driving module 101 and the transformer T1 form a self-excited oscillation circuit.

[0031] Preferably, when the oscillation driving module 101 and the transformer T1 form an oscillation circuit and a voltage is generated at the output end of the transformer T1, at this time the control module 2 powers on and enables the load not to work temporarily, the oscillation circuit starts with a light load, waits for the control module 2 to adjust the voltage at the output end of the transformer T1, and then enables the load to work, so as to ensure stable power supply to the load.

[0032] In a possible implementation manner, as Figure 5 shown, the oscillation driving module 101 includes a resistor R1, a resistor R2, a switching transistor Q1, and a switching transistor Q2; Among them, the same-named end of the first primary winding of the transformer T1 and the different-named end of the second primary winding are both connected to the input voltage VIN; the different-named end of the first primary winding of the transformer T1 is connected to the driving end of the switching transistor Q1 through the resistor R1 and the resistor R2; the first end of the switching transistor Q1 is connected to the intermediate node of the resistor R1 and the resistor R2; the second end of the switching transistor Q1 is connected to the driving end of the switching transistor Q2; the first end of the switching transistor Q2 is connected to the same-named end of the second primary winding of the transformer T1, and the second end of the switching transistor Q2 is grounded.

[0033] Exemplarily, the switching transistors Q1 and Q2 are triodes.

[0034] The following explains the process of the module and the transformer T1 forming an oscillation circuit: The input voltage VIN sequentially passes through the first primary winding of the transformer T1, the resistor R1, and the resistor R2 to drive the switching transistor Q1 to conduct, then the switching transistor Q2 also conducts, and the transformer T1, the resistor R1, the resistor R2, the switching transistor Q1, and the switching transistor Q2 form a self-excited oscillation circuit, so that a corresponding voltage is output at the output end of the transformer T1.

[0035] Therefore, the oscillation circuit formed by the oscillation driving module 101 and the transformer T1 has better stability compared with the traditional self-excited oscillation boost circuit, and its oscillation frequency is not easily affected by temperature and does not show frequency shift or stop oscillating.

[0036] In a possible implementation manner, continue to refer to Figure 5 , the oscillation enabling module 102 includes a switching transistor Q3; Among them, the driving end of the switching transistor Q3 is connected to the control module 2, the first end of the switching transistor Q3 is connected to the driving end of the switching transistor Q1, and the second end of the switching transistor Q3 is grounded.

[0037] Exemplarily, the switching transistor Q3 is a MOS transistor.

[0038] Furthermore, the oscillation enabling module 102 further includes a resistor R3, and both ends of the resistor R3 are respectively connected to the driving end and the second end of the switching transistor Q3.

[0039] The following explains the process of the control module 2 controlling the transformer T1 to stop oscillating through the oscillation enabling module 102: The control module 2 outputs a high level to the driving end of the switching transistor Q3 to drive the switching transistor Q3 to conduct, pulls down the voltage of the driving end of the switching transistor Q1, then the switching transistor Q1 disconnects, and the transformer T1 stops oscillating.

[0040] In a possible implementation manner, continue to refer toFigure 5 The output end of the control module 2 is connected to the driving end of the switching transistor Q2; The control module 2 is configured to adjust the voltage at the output end of the transformer T1 by controlling the on-off time of the switching transistor Q2.

[0041] The control module 2 can adjust the voltage at the output end of the transformer T1 by collecting the voltage at the output end of the transformer T1 in real time and then through the oscillation driving module 101.

[0042] In a possible implementation manner, referring to Figures 4 - 5 , the voltage conversion circuit further includes a first output voltage control module 3; The first output voltage control module 3 is connected between the output end of the transformer T1 and the power supply end of the control module 2, and is configured to convert the voltage at the output end of the transformer T1 into the voltage required for the control module 2 to operate powered on.

[0043] In a possible implementation manner, referring to Figure 5 , the first output voltage control module 3 includes a resistor R4 and a voltage stabilizing diode ZD1 connected in series; Wherein, the power supply end of the control module 2 is connected to the middle node of the resistor R4 and the voltage stabilizing diode ZD1, the end of the resistor R4 that is not connected to the voltage stabilizing diode ZD1 is connected to one output end of the transformer T1, and the end of the voltage stabilizing diode ZD1 that is not connected to the resistor R4 is connected to the other output end of the transformer T1.

[0044] Therefore, by utilizing the voltage stabilizing effect of the voltage stabilizing diode ZD1 and the voltage dividing effect of the resistor R4, the voltage input to the power supply end of the control module 2 is the voltage required for the normal operation of the control module 2, such as 3.3V.

[0045] It should be noted that the resistor R4 can represent a single resistor or a series-parallel combination of multiple resistors, and those skilled in the art can adjust the resistor R4 and select the specifications of the voltage stabilizing diode ZD1 according to requirements.

[0046] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes a second output voltage control module 4; The second output voltage control module 4 is connected between the output end of the transformer T1 and the load, and is configured to stabilize the voltage at the output end of the transformer T1 to the voltage required by the load.

[0047] Therefore, by adding the second output voltage control module 4, the stability of the output voltage of the transformer T1 is further ensured, and voltage fluctuations are avoided.

[0048] Exemplarily, asFigure 5 As shown, the second output voltage control module 4 includes a voltage stabilizing diode ZD2; One end of the voltage stabilizing diode ZD2 is connected to one output end of the transformer T1, and the other end of the voltage stabilizing diode ZD2 is connected to the other output end of the transformer T1.

[0049] As Figure 4 shown, for ease of understanding, the voltage supplied by the first output voltage control module 3 to the control module 2 is denoted as the first voltage, and the voltage supplied by the transformer T1 to the load is denoted as the second voltage. Among them, the load can be a low-voltage load or a high-voltage load. The low-voltage load is, for example, a Bluetooth or WIFI module, and its required voltage is, for example, 3.3V or 5V. The high-voltage load is, for example, a relay or a MOS drive module, and its required voltage is, for example, 12V or 24V.

[0050] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes a signal amplification module 5; the signal amplification module 5 is connected between the output end of the control module 2 and the driving end of the switching transistor Q2; The control module 2 is configured to output a PWM signal to control the on and off time of the switching transistor Q2; the signal amplification module 5 is configured to amplify the PWM signal.

[0051] Preferably, the signal amplification module 5 may adopt a push-pull output.

[0052] Exemplarily, when adopting a push-pull output, the signal amplification module 5 includes a resistor R5, a resistor R6, a switching transistor Q4, and a switching transistor Q5. The connection of each component in the signal amplification module 5 can refer to Figure 5 shown, and will not be elaborated here.

[0053] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes a rectification module 6; The rectification module 6 is connected to the output end of the transformer T1 and is configured to rectify the voltage output by the transformer T1.

[0054] Preferably, the rectification module 6 adopts a bridge rectification, including four diodes D1, D2, D3, and D4. The specific connection in the rectification module 6 can refer to Figure 5 , and will not be elaborated here.

[0055] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes an overvoltage protection module 7; the overvoltage protection module 7 is configured to control the transformer T1 to stop voltage output when the output voltage of the transformer T1 exceeds the voltage threshold.

[0056] Exemplarily, as Figure 5 shown, the overvoltage protection module 7 includes a voltage stabilizing diode ZD3; one end of the voltage stabilizing diode ZD3 is connected to the output end of the transformer T1, and the other end is connected to the driving end of the switching transistor Q3; when the output voltage of the transformer T1 exceeds the voltage threshold, the voltage stabilizing diode ZD3 breaks down reversely, and the transformer T1 stops voltage output to ensure circuit safety.

[0057] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes an anti-backflow protection module 8; the anti-backflow protection module 8 is connected between the output end of the control module 2 and the self-oscillation module 1, and is used to prevent current backflow.

[0058] Exemplarily, as Figure 5 shown, the anti-backflow protection module 8 includes a diode D3.

[0059] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes a first filtering module 9; the first filtering module 9 is connected to the output end of the first output voltage control module 3 and is used for filtering processing.

[0060] Exemplarily, as Figure 5 shown, the first filtering module 9 includes a capacitor C1; the capacitor C1 is connected in parallel at both ends of the voltage stabilizing diode ZD1.

[0061] In a possible implementation manner, as Figures 4 - 5 shown, the voltage conversion circuit further includes a second filtering module 10; the second filtering module 10 is connected to the output end of the second output voltage control module 4 and is used for filtering processing.

[0062] Exemplarily, as Figure 5 shown, the second filtering module 10 includes a capacitor C2; the capacitor C2 is connected in parallel at both ends of the voltage stabilizing diode ZD2.

[0063] Therefore, the voltage conversion circuit of the present application combines two methods of oscillation output and control module control output. When the circuit has a power input, first, the self-oscillation module 1 and the transformer T1 form an oscillation circuit to start self-starting. At this time, no chip control is required, and only the magnetic coupling of the transformer T1 can be used to generate oscillation to supply power to the control module 2, so that the control module 2 can start and operate normally when the input voltage VIN is high or low, and then take over the control of the voltage at the output end of the transformer T1 to supply power to the load, which well solves the problem that the circuit cannot start and operate normally when the input voltage is low, and enables the voltage conversion circuit to be used in a wide input voltage range.

[0064] In addition, after the control module 2 is powered on, on the one hand, the control module 2 controls the oscillating output of the stop circuit. On the other hand, based on the input voltage VIN, it directly controls the output of the transformer T1 through the oscillation driving module 101. The control module 2 takes over the output control of the voltage conversion circuit, and flexibly adjusts the voltage at the output end of the transformer T1. It can perform boost output when there is a load demand and perform buck output when there is no load connection to save electrical energy, ensuring the stable operation of the circuit and improving the reliability of the circuit.

[0065] After the control module 2 of the voltage conversion circuit in this application is powered on, the control module 2 takes over the output control of the transformer T1, and Figure 2 compared with the traditional self-excited oscillation boost topology shown, it can avoid the problem that the oscillation frequency is affected by temperature. The output of the transformer T1 is more stable, and the magnitude of the output voltage can also be flexibly adjusted.

[0066] The embodiment of this application provides a voltage converter, including the voltage conversion circuit applicable to a wide input voltage range described in the above embodiment or any of its implementable manners.

[0067] The above are all the preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A voltage conversion circuit suitable for a wide input voltage range, characterized in that: The voltage conversion circuit comprises: a self-oscillation module (1), a control module (2) and a transformer T1; wherein the output end of the control module (2) is connected to the self-oscillation module (1), and the self-oscillation module (1) is connected to the input end of the transformer T1; the output end of the transformer T1 is respectively connected to a load and a power supply end of the control module (2); When an input voltage VIN is applied to the input end of the transformer T1, the self-oscillation module (1) and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; the control module (2) is powered on and operates based on the voltage at the output end of the transformer T1, and takes over the control of the voltage at the output end of the transformer T1, so that the voltage at the output end of the transformer T1 is the voltage required by the load, and supplies power to the load.

2. The voltage conversion circuit applicable to a wide input voltage range according to claim 1, characterized in that: The self-oscillation module (1) comprises an oscillation driving module (101) and an oscillation enabling module (102); When an input voltage VIN is applied to the input end of the transformer T1, the oscillation driving module (101) and the transformer T1 form an oscillation circuit, so that a voltage is generated at the output end of the transformer T1; The control module (2) is used to control the transformer T1 to stop oscillating through the oscillation enabling module (102) when taking over the control of the voltage at the output end of the transformer T1, and to control the voltage at the output end of the transformer T1 through the oscillation driving module (101) so that the voltage at the output end of the transformer T1 is the load demand voltage.

3. The voltage conversion circuit applicable to a wide input voltage range according to claim 1, characterized in that: The voltage conversion circuit also includes a first output voltage control module (3); The first output voltage control module (3) is connected between the output end of the transformer T1 and the power supply end of the control module (2), and is used to convert the voltage at the output end of the transformer T1 into the voltage required for the control module (2) to power on and operate.

4. The voltage conversion circuit applicable to a wide input voltage range according to claim 1, characterized in that: The voltage conversion circuit also includes a second output voltage control module (4); The second output voltage control module (4) is connected between the output end of the transformer T1 and the load, and is used to stabilize the voltage at the output end of the transformer T1 to be the voltage required by the load.

5. The voltage conversion circuit applicable to a wide input voltage range according to claim 2, characterized in that: The oscillation driving module (101) comprises a resistor R1, a resistor R2, a switch tube Q1 and a switch tube Q2; Among them, the same-name end of the first primary winding of the transformer T1 and the opposite-name end of the second primary winding are both connected to the input voltage VIN; the opposite-name end of the first primary winding of the transformer T1 is connected to the driving end of the switch tube Q1 through the resistor R1 and the resistor R2; the first end of the switch tube Q1 is connected to the middle node of the resistor R1 and the resistor R2; the second end of the switch tube Q1 is connected to the driving end of the switch tube Q2; the first end of the switch tube Q2 is connected to the same-name end of the second primary winding of the transformer T1, and the second end of the switch tube Q2 is grounded.

6. The voltage conversion circuit applicable to a wide input voltage range according to claim 2, characterized in that: The oscillation enabling module (102) comprises a switch tube Q3; The driving end of the switch tube Q3 is connected to the control module (2), the first end of the switch tube Q3 is connected to the driving end of the switch tube Q1, and the second end of the switch tube Q3 is grounded.

7. The voltage conversion circuit applicable to a wide input voltage range according to claim 3, characterized in that: The first output voltage control module (3) comprises a resistor R4 and a voltage regulator diode ZD1 connected in series; The power supply end of the control module (2) is connected to the middle node between the resistor R4 and the voltage regulator ZD1, the end of the resistor R4 not connected to the voltage regulator ZD1 is connected to an output end of the transformer T1, and the end of the voltage regulator ZD1 not connected to the resistor R4 is connected to the other output end of the transformer T1.

8. The voltage conversion circuit applicable to a wide input voltage range according to claim 5, characterized in that: The output end of the control module (2) is connected to the driving end of the switch tube Q2; The control module (2) is used to adjust the voltage at the output end of the transformer T1 by controlling the on-off time of the switch tube Q2.

9. The voltage conversion circuit applicable to a wide input voltage range according to claim 4, characterized in that: The second output voltage control module (4) comprises a voltage regulator tube ZD2; One end of the voltage regulator tube ZD2 is connected to one output end of the transformer T1 , and the other end of the voltage regulator tube ZD2 is connected to the other output end of the transformer T1 .

10. A voltage converter, characterized in that: A voltage conversion circuit suitable for a wide input voltage range comprising the voltage conversion circuit described in any one of claims 1 to 9.

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