Power supply circuit

Abstract

The invention discloses a power supply circuit, which comprises a power supply module, at least one starting power supply module and a control circuit, and is characterized in that the power supply module comprises a power supply and an input capacitor, and the power supply is configured to be started under the condition that the voltage drop at the two ends of the input capacitor is greater than the minimum working voltage of the power supply circuit; the starting power supply module comprises a starting power supply and a starting transformer, the starting power supply is connected with the primary side of the starting transformer, the secondary side of the starting transformer is connected with the input capacitor, and the starting transformer is used for boosting the output voltage of the starting power supply module and charging the input capacitor; the control circuit is configured to start the starting power supply module when the voltage drop at the two ends of the input capacitor is smaller than the minimum working voltage of the power supply circuit, and close the starting power supply module when the voltage drop at the two ends of the input capacitor is larger than or equal to the minimum working voltage of the power supply circuit. According to the power supply circuit provided by the invention, the power supply circuit can operate by adopting the starting power supply with relatively low output voltage, and the reliability of the power supply circuit is ensured.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and more specifically, to a power supply circuit. Background Art

[0002] The multi-input multi-output power supply circuit includes multiple power supplies. In order to improve the reliability of the power supply circuit, it is necessary to ensure that the entire power supply circuit can operate when any one of the power supplies is powered. Therefore, the output voltage of each power supply is required to be greater than the operating voltage of the power supply circuit. When the power supply circuit is fully operational, some of the power supplies need to be turned off to reduce energy consumption, but the turned-off power supplies still have standby power consumption. Since the output voltage of each power supply is large, the power is also large, the standby power consumption is also large, and the energy consumption is still large. In addition, since the output voltage of the power supply is large, in order to ensure the reliability of the power supply circuit, the electrical components of the standby power supply also have higher withstand voltage requirements, safety distances and heat dissipation requirements, which makes the cost of the electrical components of the power supply circuit higher. In addition, in order to meet the safety distance and heat dissipation requirements, the power supply needs to occupy a larger space, which increases the volume of the power supply circuit. Summary of the invention

[0003] The embodiments of the present application provide a power supply circuit to solve at least one of the above-mentioned technical problems.

[0004] The power supply circuit of the embodiment of the present application includes:

[0005] A power supply module, the power supply module comprising a power supply and an input capacitor, the power supply being configured to start when a voltage drop across the input capacitor is greater than a minimum operating voltage of the power supply circuit;

[0006] At least one starting power supply module, the starting power supply module comprising a starting power supply and a starting transformer, the starting power supply is connected to the primary side of the starting transformer, the secondary side of the starting transformer is connected to the input capacitor, and the starting transformer is used to boost the output voltage of the starting power supply module and charge the input capacitor;

[0007] A control circuit, wherein the control circuit is configured to turn on the startup power supply module when the voltage drop across the input capacitor is less than the minimum operating voltage of the power supply circuit, and to turn off the startup power supply module when the voltage drop across the input capacitor is greater than or equal to the minimum operating voltage of the power supply circuit.

[0008] The power supply circuit provided by the present application uses a starting transformer to boost the output voltage of the starting power supply module, so that the starting power supply module only needs a relatively small output voltage to charge the input capacitor, so that the voltage drop across the input capacitor is greater than the minimum operating voltage of the power supply. In this way, a starting power supply with a relatively small output voltage can enable the power supply circuit to operate when any power supply has power, thereby ensuring the reliability of the power supply circuit. The starting power supply with a relatively small output voltage has a relatively small power, thereby reducing the standby power consumption. On the other hand, since the voltage and power of the starting power supply module are relatively small, the electrical components of the starting power supply module can adopt a relatively low withstand voltage level, which is conducive to reducing the volume of the power supply circuit and reducing production costs.

[0009] In some embodiments, the power supply module includes a power supply diode, and the power supply is connected to the secondary side of the starting transformer through the power supply diode.

[0010] In this way, the power supply diode can block the voltage from the startup power supply module to avoid impact on the power supply module.

[0011] In some embodiments, the control circuit includes a first pulse width modulation chip, the power supply module includes a power supply transformer and a power supply switch tube, the primary side of the power supply transformer is connected in parallel with the input capacitor, one end of the primary side of the power supply transformer is connected to the drain of the power supply switch tube, the primary pole of the power supply switch tube is grounded, one end of the first pulse width modulation chip is connected to the secondary side of the power supply transformer, and the first pulse width modulation chip is configured to obtain a first output signal based on the output voltage of the secondary side of the power supply transformer and a first preset reference value to control the on and off time of the power supply switch tube.

[0012] In this way, using the first pulse width modulation chip to control the opening and closing of the power switch tube is conducive to simplifying the control logic of the power switch tube. In addition, the first pulse width modulation chip has functions such as overvoltage protection, overcurrent protection and short circuit protection, which is conducive to ensuring the safety of the system.

[0013] In some embodiments, the power supply module further includes an output circuit, the secondary side of the power supply transformer is connected to the output circuit, and the output circuit is connected to the first pulse width modulation chip.

[0014] In this way, the output circuit provides a voltage signal to the first pulse width modulation chip, and can also supply power to the first pulse width modulation chip, without the need to provide additional power to the first pulse width modulation chip, which is conducive to simplifying the circuit and saving costs.

[0015] In some embodiments, the startup power module further includes a startup diode, and the startup power module is connected to the input capacitor through the startup diode.

[0016] In this way, the starting diode can block the voltage from the power supply module to avoid impact on the starting power supply module. At the same time, since multiple starting power supply modules are connected to the input capacitor at the same time, if a starting power supply module charges the input capacitor, the voltage of the starting diode of other starting power supply modules will be raised, so that there is always only one starting power supply module charging the input capacitor, which is beneficial to reduce losses.

[0017] In some embodiments, the number of the startup diodes is two, and the two startup diodes are connected in series.

[0018] Thus, two starting diodes connected in series can increase the withstand voltage. Compared with using a diode with a higher withstand voltage, selecting two diodes with a lower withstand voltage connected in series helps to reduce costs.

[0019] In some embodiments, the control circuit includes a second pulse width modulation chip, which is connected to the startup power supply module. The second pulse width modulation chip is used to turn on the startup power supply module when the voltage of the input capacitor is less than the minimum operating voltage of the power supply, and turn off the startup power supply module when the voltage of the input capacitor is greater than or equal to the minimum operating voltage of the power supply.

[0020] In this way, using the second pulse width modulation chip to control the startup of the power supply module is beneficial to simplifying the control logic and improving reliability.

[0021] In some embodiments, the control circuit further includes an isolation sampling circuit, one end of the isolation sampling circuit is connected to the input capacitor, and the other end of the isolation sampling circuit is connected to the second pulse width modulation chip, and the isolation sampling circuit is used to collect the voltage of the input capacitor.

[0022] In this way, the isolated sampling circuit has an electrical isolation function. Using the isolated sampling circuit to collect the voltage of the input capacitor is beneficial to improving the reliability and stability of the circuit and avoiding interference with the power supply module.

[0023] In some embodiments, the isolation sampling circuit includes an optical coupler, one end of the optical coupler is connected to the input capacitor, and the other end of the optical coupler is connected to the second pulse width modulation chip.

[0024] In this way, the isolated sampling circuit sends the collected voltage difference of the input capacitor to the second pulse width modulation chip through the optical coupler, thereby achieving isolation between the input capacitor and the second pulse width modulation chip, thereby improving the safety of the entire circuit.

[0025] In some embodiments, the startup power supply module includes a startup switch tube, the primary side of the startup transformer is connected in parallel with the startup power supply, one end of the primary side of the startup transformer is connected to the startup power supply through the startup switch tube, and the second pulse width modulation chip is configured to obtain a second output signal based on the voltage difference of the input capacitor and a second preset reference value to control the on-off time of the startup switch tube.

[0026] In this way, using the second pulse width modulation chip to control the opening and closing of the startup switch tube is conducive to simplifying the control logic of the startup switch tube. In addition, the second pulse width modulation chip has functions such as overvoltage protection, overcurrent protection and short circuit protection, which is conducive to ensuring the safety of the system.

[0027] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 It is a circuit diagram of a power supply circuit in the prior art;

[0030] Figure 2 is a circuit diagram of a power supply circuit according to an embodiment of the present application;

[0031] Figure 3 is a module schematic diagram of a power supply circuit according to an embodiment of the present application;

[0032] Figure 4 is a circuit diagram of an isolated sampling circuit according to an embodiment of the present application.

[0033] Description of main component symbols: power supply circuit 100, power supply module 10, power supply 11, input capacitor 12, power supply capacitor 13, power supply diode 14, power supply transformer 15, power supply switch tube 16, output circuit 17, output diode 171, output buffer capacitor 172, starting power supply module 20, starting power supply 21, starting transformer 22, starting diode 23, starting switch tube 24, starting capacitor 25, control circuit 30, first pulse width modulation chip 31, second pulse width modulation chip 32, isolation sampling circuit 33, optical coupler 331, first resistor 332, first capacitor 333, second resistor 334, third resistor 335, voltage regulator diode 336, second capacitor 337, fourth resistor 338, fifth resistor 339. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention. In the description of the present invention, it is necessary to understand that the orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0037] The disclosure herein provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described herein. Of course, they are merely examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art may appreciate the application of other processes and / or the use of other materials.

[0038] A multiple-input multiple-output power supply circuit includes multiple power supplies, such as Figure 1 As shown, in order to improve the reliability of the power supply circuit, it is necessary that the entire power supply circuit can be operated when any power supply has electricity, so the output voltage of each power supply is required to be greater than the working voltage of the power supply circuit. When the power supply circuit is fully operational, it is necessary to turn off some of the power supplies to reduce energy consumption, but the turned-off power supplies still have standby power consumption. Since the output voltage of each power supply is large, the power is also large, the standby power consumption is also large, and the energy consumption is still large. In addition, since the output voltage of the power supply is large, in order to ensure the reliability of the power supply circuit, the electrical components of the standby power supply also have higher withstand voltage requirements, safety distances and heat dissipation requirements, which makes the cost of the electrical components of the power supply circuit higher. In addition, in order to meet the safety distance and heat dissipation requirements, the power supply needs to occupy a larger space, which increases the volume of the power supply circuit.

[0039] See also Figure 2 The power supply circuit 100 of the embodiment of the present application includes a power supply module 10, at least one starting power supply module 20 and a control circuit 30. The power supply module 10 includes a power supply 11 and an input capacitor 12. The power supply 11 is configured to start when the voltage drop across the input capacitor 12 is greater than the minimum operating voltage of the power supply circuit 100; the starting power supply module 20 includes a starting power supply 21 and a starting transformer 22. The starting power supply 21 is connected to the primary side of the starting transformer 22, and the secondary side of the starting transformer 22 is connected to the input capacitor 12. The starting transformer 22 is used to boost the output voltage of the starting power supply module 20 and charge the input capacitor 12; the control circuit 30 is configured to turn on the starting power supply module 20 when the voltage drop across the input capacitor 12 is less than the minimum operating voltage of the power supply circuit 100, and turn off the starting power supply module 20 when the voltage drop across the input capacitor 12 is greater than or equal to the minimum operating voltage of the power supply circuit 100.

[0040] The power supply circuit 100 provided in the present application uses a starting transformer 22 to boost the output voltage of the starting power supply module 20, so that the starting power supply module 20 only needs a relatively small output voltage to charge the input capacitor 12, so that the voltage drop across the input capacitor 12 is greater than the minimum operating voltage of the power supply 11. In this way, the starting power supply 21 with a relatively small output voltage can enable the power supply circuit 100 to operate when any power supply has power, thereby ensuring the reliability of the power supply circuit 100. The starting power supply 21 with a relatively small output voltage has a relatively small power, thereby reducing the standby power consumption. On the other hand, since the starting power supply module 20 has a relatively small voltage and power, the electrical components of the starting power supply module 20 can adopt a relatively low withstand voltage level, which is conducive to reducing the volume of the power supply circuit 100 and reducing production costs.

[0041] For details, please refer to Figure 2 and Figure 3 In the embodiment of the present application, the power supply 11 is the power supply for normal operation, and a power supply capacitor 13 is also connected in parallel at both ends of the power supply 11. The input capacitor 12 is connected in parallel at both ends of the power supply 11, and its main functions are to absorb high-frequency pulse peaks, cache energy, filter circuit differential mode interference, etc. Energy from the startup power supply 11 is stored during startup.

[0042] In the embodiment of the present application, the startup power module 20 mainly assists the power supply module 10 in supplying power when the voltage of the power supply 11 is zero. The output of the startup power module 20 is directly connected to the input of the power supply module 10. When there is voltage in the power supply 11, the startup power module 20 stops working. The startup power 21 mainly supplies power to the startup power 21.

[0043] In some embodiments, the power supply module 10 includes a power supply diode 14 , and the power supply 11 is connected to the secondary side of the starting transformer 22 via the power supply diode 14 .

[0044] In this way, the power supply diode 14 can block the voltage from the startup power module 20 to avoid impact on the power supply module 10 .

[0045] Specifically, in the embodiment of the present application, the positive electrode of the power supply 11 and one end of the power supply capacitor 13 are connected to the anode of the power supply diode 14, and the cathode of the power supply diode 14 is connected to the input capacitor 12 and the secondary side of the starting transformer 22, thereby separating the power supply capacitor 13 from the input capacitor 12 to avoid the starting power supply module 20 charging the power supply capacitor 13 and generating an impact current.

[0046] In some embodiments, the control circuit 30 includes a first pulse width modulation chip 31, the power supply module 10 includes a power supply transformer 15 and a power supply switch tube 16, one end of the primary side of the power supply transformer 15 is connected to the drain of the power supply switch tube 16, the primary pole of the power supply switch tube 16 is grounded, one end of the primary side of the power supply transformer 15 is connected to the input capacitor 12 through the power supply switch tube 16, one end of the first pulse width modulation chip 31 is connected to the secondary side of the power supply transformer 15, and the first pulse width modulation chip 31 is configured to obtain a first output signal based on the output voltage of the secondary side of the power supply transformer 15 and a first preset reference value to control the on and off time of the power supply switch tube 16.

[0047] In this way, using the first pulse width modulation chip 31 to control the opening and closing of the power switch tube 16 is conducive to simplifying the control logic of the power switch tube 16. In addition, the first pulse width modulation chip 31 has functions such as overvoltage protection, overcurrent protection and short circuit protection, which is conducive to ensuring the safety of the system.

[0048] Specifically, in the embodiment of the present application, the power transformer 15 can reduce the high voltage input by the power supply 11 to a low voltage suitable for electronic equipment to ensure the normal operation of the electronic equipment. At the same time, the power transformer 15 can also electrically isolate the power supply 11 from the electronic equipment to avoid short circuit or other dangerous situations of the equipment, which helps to protect the safety of the equipment and operators.

[0049] The main function of the power switch tube 16 is to convert direct current into pulse current and output two sets of alternating current voltages through the power transformer 15 .

[0050] The first pulse width modulation chip 31 is the control center of the entire power supply circuit 100, and performs closed-loop control on the power supply module 10. The output voltage of the secondary side of the receiving power supply transformer 15 is compared with the first preset reference value, and after loop compensation, the first output signal is provided to the power supply switch tube 16 to control the on-off time of the power supply switch tube 16. This control method can output a stable switching frequency and precise output voltage control, and the output frequency of the first output signal can also be adjusted and compensated by peripheral devices.

[0051] In the embodiment of the present application, the first preset reference value is 3.3V, which is a widely used voltage standard. Selecting 3.3V as the first preset reference value helps to ensure the compatibility and interoperability between the first pulse width modulation chip 31 and other digital circuit components. At the same time, a lower first preset reference value (such as 3.3V) can reduce power consumption while ensuring the performance of the power supply circuit 100, compared with a higher voltage, and can also more efficiently control the power switch tube 16, thereby reducing energy loss and improving power conversion efficiency.

[0052] Furthermore, the first pulse width modulation chip 31 has an overvoltage, overcurrent and short circuit protection function to ensure the safety and reliability of the power supply circuit 100 .

[0053] See also Figure 2 and Figure 3 In some embodiments, the power supply module 10 further includes an output circuit 17 , the secondary side of the power supply transformer 15 is connected to the output circuit 17 , and the output circuit 17 is connected to the first pulse width modulation chip 31 .

[0054] In this way, the output circuit 17 provides a voltage signal to the first pulse width modulation chip 31 and can also supply power to the first pulse width modulation chip 31 at the same time. There is no need to provide additional power to the first pulse width modulation chip 31, which is conducive to simplifying the circuit and saving costs.

[0055] Specifically, in an embodiment of the present application, the output circuit 17 includes an output diode 171 and an output buffer capacitor 172, one end of the secondary side of the power supply transformer 15 is connected to the anode of the output diode 171, the cathode of the output diode 171 is connected to the output buffer capacitor 172, and the other end of the output buffer capacitor 172 is connected to the other end of the secondary side of the power supply transformer 15.

[0056] In the embodiment of the present application, the output diode 171 has the function of high-frequency rectification, which converts the high-frequency pulse outputted by the winding of the power supply transformer 15 into direct current. The output buffer capacitor 172 has the function of storing energy and filtering high-frequency ripples, thereby providing a stable direct current power supply to the load.

[0057] Furthermore, the number of output circuits 17 can be multiple. In the embodiment of the present application, the number of output circuits 17 is three. One of the output circuits 17 supplies power to the first pulse width modulation chip 31 and provides a voltage signal to the first pulse width modulation chip 31.

[0058] See also Figure 2 In some embodiments, the startup power module 20 further includes a startup diode 23 , and the startup power module 20 is connected to the input capacitor 12 via the startup diode 23 .

[0059] In this way, the starting diode 23 can block the voltage from the power supply module 10 to avoid impact on the starting power supply module 20. At the same time, since multiple starting power supply modules 20 are connected to the input capacitor 12 at the same time, if a starting power supply module 20 charges the input capacitor 12, the voltage of the starting diode 23 of other starting power supply modules 20 will be raised, so that there is always only one starting power supply module 20 charging the input capacitor 12, which is beneficial to reduce losses.

[0060] Specifically, in the embodiment of the present application, the negative electrode of the secondary side of the start transformer 22 is grounded, the positive electrode is connected to the anode of the start diode 23, and the cathode of the start diode 23 is connected to the input capacitor 12. The start diode 23 performs high-frequency rectification and charges the input capacitor 12, while blocking the voltage from the power supply 11.

[0061] In some embodiments, the number of the start-up diodes 23 is two, and the two start-up diodes 23 are connected in series.

[0062] Thus, the two starting diodes 23 connected in series can increase the withstand voltage. Compared with using a diode with a higher withstand voltage, selecting two diodes with a lower withstand voltage to be connected in series is beneficial to reducing costs.

[0063] Specifically, in the embodiment of the present application, each starting power supply module 20 is provided with two starting diodes 23 connected in series to increase the withstand voltage. In other embodiments, the starting diodes 23 can also be designed to be other numbers. The number and model of the starting diodes 23 can be selected according to actual needs.

[0064] It should be noted that the fewer the number of start-up diodes 23, the higher the required withstand voltage, but the number of start-up diodes 23 should not be too large. When the number of start-up diodes 23 connected in series is greater than two, a parasitic Darlington transistor will be formed inside the diode string. The parasitic Darlington transistor will in turn reduce the trigger voltage of the diode string, and as the number of diodes connected in series increases, the leakage current will also increase, resulting in increased energy consumption, reduced service life, and even a negative impact on the stability of the circuit.

[0065] See also Figure 2 and Figure 3 In some embodiments, the control circuit 30 includes a second pulse width modulation chip 32, which is connected to the startup power module 20. The second pulse width modulation chip 32 is used to turn on the startup power module 20 when the voltage of the input capacitor 12 is less than the minimum operating voltage of the power supply 11, and turn off the startup power module 20 when the voltage of the input capacitor 12 is greater than or equal to the minimum operating voltage of the power supply 11.

[0066] In this way, using the second pulse width modulation chip 32 to control the startup power module 20 is beneficial to simplify the control logic and improve reliability.

[0067] Specifically, in the embodiment of the present application, the starting power supply module 20 includes a starting switch tube 24, and the second pulse width modulation chip 32 is connected to the starting switch tube 24. When the voltage of the power supply module 10 is 0, the starting power supply module 20 is controlled by controlling the switch tube to start working, thereby charging the input capacitor 12. When the voltage of the input capacitor 12 is equal to the minimum operating voltage of the power supply 11, the starting power supply module 20 is controlled by controlling the switch tube to stop working.

[0068] In the embodiment of the present application, there are multiple startup power modules 20 . For each additional startup power module 20 , the control circuit 30 adds a pulse width modulation chip to control the startup power module 20 .

[0069] In some embodiments, the control circuit 30 further includes an isolation sampling circuit 33 , one end of the isolation sampling circuit 33 is connected to the input capacitor 12 , and the other end is connected to the second pulse width modulation chip 32 . The isolation sampling circuit 33 is used to collect the voltage of the input capacitor 12 .

[0070] In this way, the isolated sampling circuit 33 has an electrical isolation function. Using the isolated sampling circuit 33 to collect the voltage of the input capacitor 12 is beneficial to improving the reliability and stability of the circuit, while avoiding interference with the power supply module 10.

[0071] Specifically, in the embodiment of the present application, the second pulse width modulation chip 32 obtains the voltage of the input capacitor 12 through the isolation sampling circuit 33 .

[0072] In the embodiment of the present application, since there are multiple startup power modules 20, multiple pulse width modulation chips need to be set accordingly. Therefore, the number of isolation sampling circuits 33 should also be multiple so that the isolation sampling circuits 33 and the pulse width modulation chips are set one by one.

[0073] Please refer to Figure 4 In some embodiments, the isolation sampling circuit 33 includes an optical coupler 331 , one end of the optical coupler 331 is connected to the input capacitor 12 , and the other end of the optical coupler 331 is connected to the second pulse width modulation chip 32 .

[0074] In this way, the isolated sampling circuit 33 sends the collected voltage difference of the input capacitor 12 to the second pulse width modulation chip 32 through the optical coupler 331, thereby achieving isolation between the input capacitor 12 and the second pulse width modulation chip 32, thereby improving the safety of the entire circuit.

[0075] Specifically, in the embodiment of the present application, the isolation sampling circuit 33 includes an optical coupler 331, a first resistor 332, a first capacitor 333, a second resistor 334, a third resistor 335, a voltage regulator diode 336, a second capacitor 337, a fourth resistor 338 and a fifth resistor 339, and the first pin of the optical coupler 331 is connected to the second pulse width modulation chip 32 through the first resistor 332, and the second pin of the optical coupler 331 is connected to one end of the first capacitor 333, and the other end of the first capacitor 333 is connected to the second pulse width modulation chip 32 through the second resistor 334. The second pulse width modulation chip 32 is connected, the other end of the first capacitor 333 is also grounded through the third resistor 335, the 2nd pin of the optical coupler 331 is also connected to the output end of the voltage regulator diode 336, the input end of the voltage regulator diode 336 is grounded, and the ground end of the voltage regulator diode 336 is grounded through the third resistor 335, the second capacitor 337 and the fourth resistor 338 are connected in series and then in parallel at both ends of the first capacitor 333, the 3rd pin of the optical coupler 331 is grounded, and the 4th pin of the optical coupler 331 is connected to the input capacitor 12 through the fifth resistor 339.

[0076] In some embodiments, the starting power supply module 20 includes a starting switch tube 24, the primary side of the starting transformer 22 is connected in parallel with the starting power supply 21, one end of the primary side of the starting transformer 22 is connected to the starting power supply 21 through the starting switch tube 24, and the second pulse width modulation chip 32 is configured to obtain a second output signal based on the voltage difference of the input capacitor 12 and the second preset reference value to control the on and off time of the starting switch tube 24.

[0077] In this way, using the second pulse width modulation chip 32 to control the opening and closing of the start switch tube 24 is beneficial to simplifying the control logic of the start switch tube 24. In addition, the second pulse width modulation chip 32 has functions such as overvoltage protection, overcurrent protection and short circuit protection, which is beneficial to ensure the safety of the system.

[0078] Specifically, the second pulse width modulation chip 32 performs closed-loop control on the startup power supply module 20. The output voltage of the secondary side of the received startup transformer 22 is compared with the first preset reference value, and after loop compensation, a second output signal is provided to the startup switch tube 24 to control the on-off time of the startup switch tube 24. This control method can output a stable switching frequency and precise output voltage control, and the output frequency of the second output signal can also be adjusted and compensated by peripheral devices.

[0079] See also Figure 2 In some embodiments, the starting power supply module 20 further includes a starting capacitor 25 , and the starting capacitor 25 is connected in parallel with the starting power supply 21 .

[0080] Thus, setting the startup capacitor 25 can absorb pulse spikes, buffer energy, and filter out differential mode interference in the circuit.

[0081] Specifically, in the embodiment of the present application, one end of the starting capacitor 25 is connected to the primary side of the starting transformer 22, and the other end is grounded.

[0082] In summary, in the embodiment of the present application, the principle of the power supply circuit 100 is:

[0083] The power supply 11 and the power supply capacitor 13 charge the input capacitor 12 through the power supply diode 14. The power supply diode 14 separates the capacitor power supply capacitor 13 and the input capacitor 12 to prevent the startup power module 20 from charging the power supply capacitor 13 and causing an impact current. The input capacitor 12 supplies power to the power supply 11. When the power supply switch tube 16 is turned on, the power supply transformer 15 stores energy, the output diode 171 is turned off, and the output buffer capacitor 172 supplies power to the load. When the power supply switch tube 16 is turned off, the power supply transformer 15 releases energy, the output diode 171 is turned on, the output buffer capacitor 172 stores energy, and supplies power to the load at the same time. The first pulse width modulation chip 31 outputs the circuit 17 voltage and compares it with the first preset reference value. After loop compensation, a first output signal is generated internally to drive the power supply switch tube 16.

[0084] The start diode 23 charges the input capacitor 12 through high-frequency rectification, while blocking the voltage of the input capacitor 12. The two start diodes 23 are connected in series to increase the withstand voltage. The second pulse width modulation chip 32 sends a second output signal to drive the start switch tube 24. When the start switch tube 24 is turned on, the start transformer 22 stores energy. The start power supply 21 and the start capacitor 25 supply power to the start transformer 22. When the start switch tube 24 is turned off, the start transformer 22 releases energy, and the start diode 23 charges the capacitor input capacitor 12. The isolation sampling circuit 33 samples the voltage across the input capacitor 12, sends it to the second pulse width modulation chip 32 through optocoupler isolation, and compares it with the reference signal inside the chip. Loop compensation is performed inside the chip, and the parameters of the loop compensation can be set externally. When the voltage of the input capacitor 12 is 0, the startup transformer 22 receives the startup signal from the second pulse width modulation chip 32 and starts the output until the voltage of the input capacitor 12 is charged to the minimum operating voltage of the power supply 11. When the system runs stably, the startup power supply circuit 100 receives the shutdown signal from the second pulse width modulation chip 32 and stops the output and enters the standby state.

[0085] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0086] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, unless otherwise clearly and specifically defined.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A power supply circuit (100), characterized in that: include: A power supply module (10), the power supply module (10) comprising a power supply (11) and an input capacitor (12), the power supply (11) being configured to start when a voltage drop across the input capacitor (12) is greater than a minimum operating voltage of the power supply circuit (100); At least one starting power supply module (20), the starting power supply module (20) comprising a starting power supply (21) and a starting transformer (22), the starting power supply (21) being connected to the primary side of the starting transformer (22), the secondary side of the starting transformer (22) being connected to the input capacitor (12), and the starting transformer (22) being used to boost the output voltage of the starting power supply module (20) and charge the input capacitor (12); A control circuit (30) is configured to turn on the startup power module (20) when the voltage drop across the input capacitor (12) is less than the minimum operating voltage of the power circuit (100), and to turn off the startup power module (20) when the voltage drop across the input capacitor (12) is greater than or equal to the minimum operating voltage of the power circuit (100).

2. The power supply circuit (100) according to claim 1, characterized in that: The power supply module (10) comprises a power supply diode (14), and the power supply (11) is connected to the secondary side of the starting transformer (22) via the power supply diode (14).

3. The power supply circuit (100) according to claim 1, characterized in that: The control circuit (30) comprises a first pulse width modulation chip (31); the power supply module (10) comprises a power supply transformer (15) and a power supply switch tube (16); the primary side of the power supply transformer (15) is connected in parallel with the input capacitor (12); one end of the primary side of the power supply transformer (15) is connected to the drain of the power supply switch tube (16); the primary electrode of the power supply switch tube (16) is grounded; one end of the first pulse width modulation chip (31) is connected to the secondary side of the power supply transformer (15); the first pulse width modulation chip (31) is configured to obtain a first output signal according to an output voltage of the secondary side of the power supply transformer (15) and a first preset reference value, so as to control the on-off time of the power supply switch tube (16).

4. The power supply circuit (100) according to claim 3, characterized in that: The power supply module (10) further comprises an output circuit (17), the secondary side of the power supply transformer (15) is connected to the output circuit (17), and the output circuit (17) is connected to the first pulse width modulation chip (31).

5. The power supply circuit (100) according to claim 1, characterized in that: The starting power supply module (20) further comprises a starting diode (23), and the starting power supply module (20) is connected to the input capacitor (12) via the starting diode (23).

6. The power supply circuit (100) according to claim 5, characterized in that: The number of the starting diodes (23) is two, and the two starting diodes (23) are connected in series.

7. The power supply circuit (100) according to claim 1, characterized in that: The control circuit (30) comprises a second pulse width modulation chip (32), the second pulse width modulation chip (32) being connected to the startup power supply module (20), the second pulse width modulation chip (32) being used to turn on the startup power supply module (20) when the voltage of the input capacitor (12) is less than the minimum working voltage of the power supply (11), and to turn off the startup power supply module (20) when the voltage of the input capacitor (12) is greater than or equal to the minimum working voltage of the power supply (11).

8. The power supply circuit (100) according to claim 7, characterized in that: The control circuit (30) further comprises an isolation sampling circuit (33), one end of the isolation sampling circuit (33) being connected to the input capacitor (12) and the other end being connected to the second pulse width modulation chip (32), and the isolation sampling circuit (33) being used to collect the voltage of the input capacitor (12).

9. The power supply circuit (100) according to claim 8, characterized in that: The isolation sampling circuit (33) comprises an optical coupler (331), one end of the optical coupler (331) is connected to the input capacitor (12), and the other end of the optical coupler (331) is connected to the second pulse width modulation chip (32).

10. The power supply circuit (100) according to claim 7, characterized in that: The starting power supply module (20) comprises a starting switch tube (24), the primary side of the starting transformer (22) is connected in parallel with the starting power supply (21), one end of the primary side of the starting transformer (22) is connected to the starting power supply (21) through the starting switch tube (24), and the second pulse width modulation chip (32) is configured to obtain a second output signal according to the voltage difference of the input capacitor (12) and a second preset reference value, so as to control the on-off time of the starting switch tube (24).

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