Low short-circuit power consumption power supply with under-voltage protection

Abstract

The embodiment of the present application provides a low short-circuit power consumption power supply with under-voltage protection, comprising: an input filter rectifier module, one end of which is connected to AC power, and the other end is connected to a flyback control module, which is used for filtering and rectifying AC power to obtain DC power; the flyback control module is used for detecting the current and output voltage of a transformer by using a control chip, feeding back and adjusting the PWM duty cycle, and driving a triode Q1 and temperature detection; an output rectifier filter module is connected to the flyback control module through a transformer, and is used for rectifying and filtering the pulsating wave output by the transformer; an output under-voltage protection module is connected to the flyback control module through a diode, and is used for enabling the control chip to enter a working state when the VCC voltage reaches the starting voltage of the control chip; when the output voltage is greater than a preset voltage threshold, the power supply enters a constant power state; when the VCC1 voltage is low, the power supply enters an under-voltage protection state; and when the output is short-circuited, the control chip is triggered to enter the under-voltage protection state. The power supply reduces short-circuit power consumption.

Description

Technical Field

[0001] This invention relates to the field of power supply circuit technology, and more specifically to a low short-circuit power supply with undervoltage protection. Background Technology

[0002] In related technologies, the undervoltage protection function of the power supply relies on the VCC undervoltage protection of the chip. Adjusting the output voltage protection threshold can only change the number of turns of the transformer VCC winding, which is relatively troublesome. Different main control chips have different VCC undervoltage points. When the undervoltage point is too low, the voltage driving the MOSFET is also relatively low. If the MOSFET is not fully turned on, there is a risk of the device exploding. Another method is to add an MCU to collect the output voltage to achieve output undervoltage protection, which is more expensive. Summary of the Invention

[0003] The purpose of this invention is to provide a low short-circuit power supply with undervoltage protection, and the specific technical solution adopted is as follows: In a first aspect, embodiments of the present invention provide a low short-circuit power supply with undervoltage protection, the power supply comprising: The system includes an input filtering and rectification module, a flyback control module, an output undervoltage protection module, and an output filtering and rectification module; among which, One end of the input filter and rectifier module is connected to AC power, and the other end is connected to the flyback control module. It is used to filter and rectify the input AC power to obtain DC power and output it to the flyback control module. The flyback control module is used to detect the current and output voltage of transformer T2 using control chip IC1, adjust the PWM duty cycle based on feedback, drive transistor Q1 through drive resistor and transistor Q2, and detect temperature through the thermistor so that control chip IC1 controls the on / off state of transistor Q1 based on the detected temperature. The output rectifier and filter module is connected to the flyback control module through transformer T2. The output rectifier and filter module is used to rectify and filter the pulsating wave output by transformer T2 and feed it back to the flyback control module. The output undervoltage protection module is connected to the flyback control module via diode D7. During startup, the input AC power charges the startup capacitor through the startup resistor. When the VCC voltage reaches the control chip's turn-on voltage, the control chip enters the operating state. The VCC auxiliary winding of the transformer is filtered and rectified to obtain the VCC1 voltage. When the output voltage exceeds a preset voltage threshold, it enters a constant power state. When the output voltage decreases, the VCC1 voltage decreases. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter-junction voltage drop of the transistor Q1, the VCC voltage decreases, and the control chip enters the undervoltage protection state. When the output is short-circuited, the VCC1 voltage drops, triggering the control chip to enter the undervoltage protection state.

[0004] In some possible implementations, the output undervoltage protection module includes: The starting resistors R3 and R3a are connected in series. The other end of the starting resistor R3a is connected to one end of capacitors C9 and C10 and one end of starting capacitor CD2a. One end of starting capacitor CD2a is connected to VCC voltage and undervoltage detection circuit. The other ends of capacitors C9 and C10 and the other end of starting capacitor CD2a are connected to undervoltage detection circuit, one end of capacitor CD2, and grounded. The undervoltage detection circuit is used to detect the VCC1 voltage provided by the auxiliary winding of the transformer. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter junction voltage drop of the transistor Q1, the control chip is triggered to enter the undervoltage protection state. The undervoltage detection circuit is connected to one end of resistor R11A; the other end of resistor R11A is connected to the other end of resistor R11; the other end of capacitor CD2 is connected to one end of resistor R12, one end of resistor R12a and the VCC1 voltage terminal respectively; the other end of resistor R12 is connected to the other end of resistor R12a and the negative terminal of diode D7 respectively; the positive terminal of diode D7 is connected to the flyback control module.

[0005] In some possible implementations, the undervoltage detection circuit includes: The positive terminal of the Zener diode ZD2 is connected to one end of the capacitor CD2 and grounded; The positive terminal of diode D8 is connected to one end of resistor R11A and the collector of transistor Q3; the base of transistor Q3 is connected to one end of resistor R11 and one end of resistor R16; the emitter of transistor Q3 is connected to the other end of resistor R11A; the negative terminal of diode D8 is connected to VCC voltage. The other end of resistor R16 is connected to the negative terminal of Zener diode ZD2.

[0006] In some possible implementations, the flyback control module includes: a flyback circuit and a spike absorption loop; wherein: The flyback circuit includes: the current detection pin CS of the control chip IC1 is connected to the gate of transistor Q1 through resistors R8 and R6; the source of transistor Q1 is grounded through resistor R5; the drain of transistor Q1 is connected to the first terminal of transformer T2; and a spike absorption circuit. The spike absorption circuit includes: a first end of a resistor network connected to capacitor C2 and the second end of transformer T2; The second end of the resistor network is connected to the negative terminal of diode D1, and the positive terminal of diode D1 is connected to the drain of transistor Q1. The third terminal of transformer T2 is connected to the output filter and rectifier module, and the fourth terminal of transformer T2 is grounded.

[0007] In some possible implementations, the flyback control module also includes: The feedback pin FB of the control chip IC1 is connected to one end of capacitor C6 and one end of resistor R22, and the other end of capacitor C6 is grounded; the other end of resistor R22 is connected to one end of resistor R24 ​​and R24a and the first end of optocoupler PH1B, and the other end of resistor R24 ​​and R24a is connected to the second end of optocoupler PH1B, and is connected to the output filter and rectification module through capacitors CY1 and CY2; the two ends of capacitors CY1 and CY2 are respectively connected to the ground terminal; The current detection pin CS of the control chip IC1 is connected to multiple series resistors through capacitor C5 and then connected to the output filter and rectification module. The over-temperature protection pin of the control chip IC1 is connected to one end of resistor R25 and one end of resistor R10. The other end of resistor R10 is connected to the positive terminal of diode D6. The negative terminal of diode D6 is connected to the thermistor RT1. The other end of resistor R25 is connected to transformer T2. The drive output pin of the control chip IC1 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R9 and the base of transistor Q2. The other end of resistor R9 is connected to the emitter of transistor Q2, one end of resistor R6 and the gate of transistor Q1. The collector of transistor Q2 is connected to resistor R30.

[0008] In some possible implementations, the current detection pin of control chip IC1 detects the transformer current through capacitor C5, resistors R8, R5a and R5; the feedback pin of control chip IC1 detects the output voltage through capacitor C6, resistors R22, R24, R24a and optocoupler PH1B; the PWM duty cycle output by the drive output pin of control chip IC1 is adjusted by the feedback voltage of the current detection pin and the feedback pin; the drive output pin drives transistor Q1 through resistors R7, R9, R30, transistor Q2 and resistor R6; the over-temperature protection pin detects the temperature through resistor R10, diode D6 and thermistor RT1.

[0009] In some possible implementations, the output filtering and rectification module includes: The third terminal of transformer T2 is connected to one end of parallel resistors R20a and R20b. The other end of parallel resistors R20a and R20b is connected to one end of capacitor C7. The other end of capacitor C7 is connected to the positive terminal of LED D5 through parallel resistors R20c, R20d, and R20E. The negative terminal of LED D5 is connected to the negative terminal of Zener diode ZD1 and one end of an RC circuit. The other end of the RC circuit is connected to a status indicator circuit. The two ends of the status indicator circuit are connected across common-mode inductor LF2. The two ends of common-mode inductor LF2 are respectively connected to the two ends of capacitor C12. The negative terminal of Zener diode ZD1 is connected to the flyback control module through a series resistor. The positive terminal of the Zener diode ZD1 is connected to the feedback control circuit; The feedback control circuit is used to monitor the change signal of the power supply's output voltage and transmit the change signal to the control chip through an optocoupler to adjust the PWM duty cycle.

[0010] In some possible implementations, the feedback control circuit includes: The positive terminal of Zener diode ZD1 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R13 and the first terminal of optocoupler PH1A. The second terminal of optocoupler PH1B is connected to the other end of resistor R13, one end of capacitor C8, and the second terminal of three-terminal regulator IC2. The other end of capacitor C8 is connected to one end of resistor R18. The other end of resistor R18 is connected to one end of resistor R15 and one end of R17b. The other end of resistor R15 is connected to the negative terminal of Zener diode ZD1. The first terminal of the three-terminal regulator IC2 is connected to one end of resistor R17a and one end of resistor R17b, and the third terminal of the three-terminal regulator IC2 is connected to the other end of resistor R17a and the other end of resistor R17b.

[0011] In some possible implementations, the input filter and rectifier module is also used to clamp the AC input voltage through the fuse Fu1, varistor VDR1 and NTC1; then the input AC is filtered by capacitor CX1 and common mode inductor LF1, and the bridge rectifier BD1 converts the AC into DC output to the flyback control module.

[0012] This invention offers the following advantages: In a low-short-circuit power supply with undervoltage protection, one end of the input filtering and rectifying module is connected to AC power, and the other end is connected to the flyback control module. This module filters and rectifies the input AC power to obtain DC power, which is then output to the flyback control module. This ensures that in the event of lightning strikes or high-voltage surges in the power grid, the short circuit is instantly broken down, clamping the voltage and protecting the subsequent rectifier and power devices. The flyback control module uses a control chip IC1 to detect the current and output voltage of transformer T2, and adjusts the PWM duty cycle accordingly to stabilize the output voltage. Temperature protection is achieved by driving transistor Q1 through a drive resistor and transistor Q2, and by using a thermistor for temperature detection, allowing the control chip IC1 to control the on / off state of transistor Q1 based on the detected temperature. The output rectifier and filter module is connected to the flyback control module via transformer T2. This module rectifies and filters the pulsating wave output from transformer T2 and feeds it back to the flyback control module. The output undervoltage protection module is connected to the flyback control module via diode D7. During startup, the input AC power charges the startup capacitor through the startup resistor. When the VCC voltage reaches the turn-on voltage of the control chip, the control chip enters the working state. The VCC auxiliary winding of the transformer is filtered and rectified to obtain the VCC1 voltage. When the output voltage is greater than the preset voltage threshold, it enters a constant power state. When the output voltage decreases, the VCC1 voltage decreases. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter junction voltage drop of the transistor Q1, the VCC voltage decreases, and the control chip enters the undervoltage protection state. When the output is short-circuited, the VCC1 voltage drops to trigger the control chip to enter the undervoltage protection state. Thus, when the power supply operates in a constant power state, it cuts off the power supply to the control chip when the voltage of the VCC winding is lower than the set value, thereby achieving DC output undervoltage protection; the two-stage VCC startup achieves lower standby power consumption and faster startup time, triggers undervoltage protection in advance, and reduces short-circuit power consumption. Attached Figure Description

[0013] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the composition structure of a low short-circuit power supply with undervoltage protection provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another component structure of a low short-circuit power supply with undervoltage protection provided in an embodiment of the present invention; Figure 3This is a schematic diagram of another component structure of a low short-circuit power supply with undervoltage protection provided in an embodiment of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a low short-circuit power supply with undervoltage protection proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments may be combined from any suitable form.

[0016] In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more.

[0017] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] The following description, in conjunction with the accompanying drawings, details a specific solution for a low short-circuit power consumption power supply with undervoltage protection provided by this invention. Please refer to the accompanying drawings. Figure 1 This diagram illustrates the structural composition of a low short-circuit power supply with undervoltage protection according to an embodiment of the present invention. The circuit includes: an input filtering and rectification module 101, a flyback control module 102, an output undervoltage protection module 103, and an output filtering and rectification module 104; wherein... One end of the input filter and rectifier module is connected to AC power, and the other end is connected to the flyback control module. It is used to filter and rectify the input AC power to obtain DC power and output it to the flyback control module.

[0020] Here, the input filter and rectifier module is also used to clamp the AC input voltage through the fuse Fu1, varistor VDR1 and NTC1; then the input AC is filtered by capacitor CX1 and common mode inductor LF1, and the bridge rectifier BD1 converts the AC into DC output to the flyback control module.

[0021] Input filtering and rectification module, such as Figure 2 As shown, it includes: fuse Fu1, common mode inductor LF1, ground terminals G3 and G4, bridge rectifier circuit DB1 (or DB2), capacitor CD1, capacitor C1, resistors R1a, R1b, R2a, R2b, varistor VDR1, thermistor NTC1, and safety capacitor CX1.

[0022] In some possible implementations, after the AC input, Fu1, VDR1, and NTC1 provide lightning and surge protection, instantly breaking down short circuits and clamping voltages when encountering lightning strikes or high voltage surges in the power grid, thus protecting the subsequent rectifier and power devices. Then, CX1 and LF1 filter the AC to improve electromagnetic interference (EMI) performance, suppress common-mode interference from the mains live and neutral wires, block grid noise from entering the power supply, and prevent the power supply's own switching noise from flowing back into the grid. Finally, the bridge rectifier circuit BD1 converts the mains frequency AC into pulsating DC output.

[0023] The flyback control module is used to detect the current and output voltage of transformer T2 using control chip IC1, adjust the PWM duty cycle based on feedback, drive transistor Q1 through drive resistor and transistor Q2, and detect temperature through the thermistor so that control chip IC1 controls the on / off state of transistor Q1 based on the detected temperature.

[0024] Here, the flyback control module includes: a flyback circuit and a spike absorption loop; wherein: The flyback circuit includes: the current detection pin CS of the control chip IC1 is connected to the gate of transistor Q1 through resistors R8 and R6; the source of transistor Q1 is grounded through resistor R5; the drain of transistor Q1 is connected to the first terminal of transformer T2; and a spike absorption circuit. The spike absorption circuit includes: a first terminal of a resistor network (including resistors: R4, R4a, R4b, R4d, R27, R28 and R29) connected to capacitor C2 and the second terminal of transformer T2; The second end of the resistor network is connected to the negative terminal of diode D1, and the positive terminal of diode D1 is connected to the drain of transistor Q1. The third terminal of transformer T2 is connected to the output filter and rectifier module, and the fourth terminal of transformer T2 is grounded.

[0025] like Figure 2 As shown, the flyback control module also includes: the feedback pin FB of the control chip IC1 is connected to one end of capacitor C6 and one end of resistor R22, and the other end of capacitor C6 is grounded; the other end of resistor R22 is connected to one end of resistors R24 and R24a and the first end of optocoupler PH1B, and the other end of resistors R24 and R24a is connected to the second end of optocoupler PH1B, and is connected to the output filter and rectification module through capacitors CY1 and CY2; the two ends of capacitors CY1 and CY2 are respectively connected across the ground terminal; The current detection pin (CS pin) of the control chip IC1 is connected to multiple series resistors through capacitor C5 and then connected to the output filter and rectification module. The over-temperature protection pin (PRT pin) of the control chip IC1 is connected to one end of resistor R25 and one end of resistor R10. The other end of resistor R10 is connected to the positive terminal of diode D6. The negative terminal of diode D6 is connected to the thermistor RT1. The other end of resistor R25 is connected to transformer T2. The drive output pin (GATE pin) of the control chip IC1 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R9 and the base of transistor Q2. The other end of resistor R9 is connected to the emitter of transistor Q2, one end of resistor R6 and the gate of transistor Q1. The collector of transistor Q2 is connected to resistor R30.

[0026] Specifically, the current detection pin of control chip IC1 detects the transformer current through capacitor C5, resistors R8, R5a and R5; the feedback pin of control chip IC1 detects the output voltage through capacitor C6, resistors R22, R24, R24a and optocoupler PH1B; the PWM duty cycle output by the drive output pin of control chip IC1 is adjusted by the feedback voltage of the current detection pin and the feedback pin; the drive output pin drives transistor Q1 through resistors R7, R9, R30, transistor Q2 and resistor R6; the over-temperature protection pin detects the temperature through resistor R10, diode D6 and thermistor RT1.

[0027] like Figure 2As shown, in the flyback control module, the control chip IC1 (OB2362), MOSFET Q1 (i.e., transistor Q1), and transformer T2 constitute the flyback circuit. C2, R4, R4a, R4b, R4d, R27, R28, R29, and D1 form the spike absorption loop for MOSFET Q1. The CS pin of the control chip IC1 detects the transformer current through C5, R8, R5a, and R5, while the FB pin detects the output voltage through C6, R22, R24, R24a, and PH1B. The feedback from the FB and CS pins adjusts the PWM duty cycle of the GATE pin, thereby stabilizing the output voltage. The GATE pin drives MOSFET Q1 through R7, R9, R30, Q2, and R6. The PRT pin detects the temperature through R10, D6, and RT1 to achieve over-temperature protection.

[0028] The output rectifier and filter module is connected to the flyback control module through transformer T2. The output rectifier and filter module is used to rectify and filter the pulsating wave output by transformer T2 and feed it back to the flyback control module.

[0029] Here, the output filtering and rectification module, such as Figure 2 As shown, the system includes: the third terminal of transformer T2 is connected to one end of parallel resistors R20a and R20b; the other end of parallel resistors R20a and R20b is connected to one end of capacitor C7; the other end of capacitor C7 is connected to the positive terminal of LED D5 via parallel resistors R20c, R20d, and R20E; the negative terminal of LED D5 is connected to the negative terminal of Zener diode ZD1 and one end of an RC circuit; the other end of the RC circuit is connected to a status indicator circuit; the two ends of the status indicator circuit are connected across a common-mode inductor LF2; the two ends of the common-mode inductor LF2 are respectively connected to the two ends of capacitor C12; the negative terminal of Zener diode ZD1 is connected to the flyback control module via a series resistor; the positive terminal of Zener diode ZD1 is connected to a feedback control circuit; the feedback control circuit is used to monitor the change signal of the power supply's output voltage and transmit the change signal to the control chip through an optocoupler to adjust the PWM duty cycle.

[0030] The feedback control circuit includes: the positive terminal of Zener diode ZD1 is connected to one end of resistor R14; the other end of resistor R14 is connected to one end of resistor R13 and the first terminal of optocoupler PH1A; the second terminal of optocoupler PH1B is connected to the other end of resistor R13, one end of capacitor C8, and the second terminal of three-terminal regulator IC2; the other end of capacitor C8 is connected to one end of resistor R18; the other end of resistor R18 is connected to one end of resistor R15 and one end of R17b; the other end of resistor R15 is connected to the negative terminal of Zener diode ZD1. The first terminal of the three-terminal regulator IC2 is connected to one end of resistor R17a and one end of resistor R17b, and the third terminal of the three-terminal regulator IC2 is connected to the other end of resistor R17a and the other end of resistor R17b.

[0031] like Figure 2 As shown, in the output rectification and filtering module, the pulsating wave output by transformer T2 is rectified by diode D5 and then filtered by electrolytic capacitor CD4 to output DC power; common mode inductor LF2 filters out output interference and improves EMC; the output voltage regulation feedback loop is formed by ZD1, R14, PH1A, R13, C8, R18, R15, R17a, R17b, and IC2. When the output voltage is too high, the voltage after voltage division by R15, R17a, and R17b is higher than the 2.5V (V) reference of IC2 (TL431). Pin 2 of TL431 is pulled low, and current flows through optocoupler PH1A, thereby transmitting the signal to PH1B and feeding it back to the primary.

[0032] The output undervoltage protection module is connected to the flyback control module via diode D7. During startup, the input AC power charges the startup capacitor (CD2a) through the startup resistors (including resistors R3 and R3a). When the VCC voltage reaches the control chip's turn-on voltage, the control chip enters the operating state. The transformer's VCC auxiliary winding is filtered and rectified to obtain the VCC1 voltage. When the output voltage exceeds a preset voltage threshold, it enters a constant power state. When the output voltage decreases, the VCC1 voltage decreases. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter-junction voltage drop of the transistor Q1, the VCC voltage decreases, and the control chip enters the undervoltage protection state. When the output is short-circuited, the VCC1 voltage drops, triggering the control chip to enter the undervoltage protection state.

[0033] Here, the output undervoltage protection module, such as Figure 3 As shown, it includes: starting resistors R3 and R3a connected in series, the other end of starting resistor R3a is connected to one end of capacitor C9, one end of capacitor C10 and one end of starting capacitor CD2a respectively, one end of starting capacitor CD2a is connected to VCC voltage and undervoltage detection circuit, the other ends of capacitors C9, C10 and CD2a are connected to undervoltage detection circuit, one end of capacitor CD2, and grounded; The undervoltage detection circuit is used to detect the VCC1 voltage provided by the auxiliary winding of the transformer. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter junction voltage drop of the transistor Q1, the control chip is triggered to enter the undervoltage protection state. The undervoltage detection circuit is connected to one end of resistor R11A; the other end of resistor R11A is connected to the other end of resistor R11; the other end of capacitor CD2 is connected to one end of resistor R12, one end of resistor R12a and the VCC1 voltage terminal respectively; the other end of resistor R12 is connected to the other end of resistor R12a and the negative terminal of diode D7 respectively; the positive terminal of diode D7 is connected to the flyback control module.

[0034] The undervoltage detection circuit includes: The positive terminal of the Zener diode ZD2 is connected to one end of the capacitor CD2 and grounded; The positive terminal of diode D8 is connected to one end of resistor R11A and the collector of transistor Q3; the base of transistor Q3 is connected to one end of resistor R11 and one end of resistor R16; the emitter of transistor Q3 is connected to the other end of resistor R11A; the negative terminal of diode D8 is connected to VCC voltage. The other end of resistor R16 is connected to the negative terminal of Zener diode ZD2.

[0035] In the output undervoltage protection module, during startup, the AC input charges CD2a through R3 and R3a. When the VCC voltage reaches the turn-on voltage of the main control chip, the chip starts working. D8 prevents charging CD2a during startup, thus achieving lower no-load power consumption and shorter startup time. The VCC auxiliary winding of the transformer is filtered and rectified by D7, R12, R12a, and CD2 to obtain the VCC1 voltage. The undervoltage detection circuit is composed of ZD2, R11, R16, Q3, and D8. When the power supply output current exceeds a certain value, it operates in constant power mode, the output voltage decreases, and the VCC1 voltage also decreases. When VCC1 is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter junction voltage drop of the transistor Q1 (approximately 0.7V), Q3 turns off, the VCC voltage decreases, and the main control chip performs undervoltage protection, thus achieving output undervoltage protection. When the output is short-circuited, the VCC1 voltage also drops, triggering undervoltage protection in advance and reducing short-circuit power consumption.

[0036] In this embodiment of the invention, output undervoltage protection is achieved by detecting the VCC voltage. The output overvoltage protection point can be quickly adjusted by replacing the Zener diode. Two-stage VCC startup achieves low no-load power consumption and a short startup time, triggering undervoltage protection earlier and reducing short-circuit power consumption. When the power supply operates in constant power mode, power to the main control chip is cut off when the voltage of the VCC winding is detected to be lower than a set value, thereby achieving DC output undervoltage protection. Two-stage VCC startup achieves low standby power consumption and a fast startup time; early triggering of undervoltage protection reduces short-circuit power consumption. The DC output undervoltage protection also protects the output motor load.

[0037] Optionally, the transmission medium can be a wired link (e.g., but not limited to, coaxial cable, optical fiber, and Digital Subscriber Line (DSL)) or a wireless link (e.g., but not limited to, Wireless Fidelity (WIFI), Bluetooth, and mobile device networks). It should be noted that the control device provided in the above embodiments is only an example illustrating the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the computer device can be divided into different functional modules to complete all or some of the functions described above. Furthermore, the method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process is detailed in the method embodiments, and will not be repeated here.

[0038] This invention provides a computer device. Exemplarily, the computer device includes: a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the computer device is able to execute any of the aforementioned low short-circuit power supplies with undervoltage protection.

[0039] This invention also protects a control device, which may include a memory and a processor. The memory stores executable program code, and the processor is used to call and execute the executable program code to execute a low short-circuit power supply with undervoltage protection provided by this invention. This invention can divide the control device into functional modules according to the above method examples. For example, each function can be assigned to a separate module, or two or more functions can be integrated into a processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this invention is illustrative and only represents a logical functional division; other division methods may exist in actual implementation. It should also be noted that all relevant content of each step involved in the above method embodiments can be referenced to the functional description of the corresponding functional module, and will not be repeated here. It should be understood that the control device provided by this invention is used to execute the aforementioned low short-circuit power supply with undervoltage protection, and therefore can achieve the same effect as the above implementation method. When using integrated units, the control device may include a processing module and a storage module. When the control device is applied to a device, the processing module can be used to control and manage the device's actions. The storage module can be used to support the execution of mutual program code by the device. The processing module can be a processor or controller, which can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. The processor can also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and microprocessors, etc., and the storage module can be a memory.

[0040] Furthermore, the control device provided in the embodiments of the present invention may specifically be a chip, component, or module. The chip may include a connected processor and a memory. The memory stores instructions, and when the processor calls and executes the instructions, the chip can execute a low-short-circuit power supply with undervoltage protection provided in the above embodiments. The embodiments of the present invention also provide a computer-readable storage medium storing computer program code. When the computer program code is executed on a computer, the computer performs the aforementioned method steps to implement a low-short-circuit power supply with undervoltage protection provided in the above embodiments.

[0041] This invention also provides a computer program product. When the computer program product is run on a computer, it causes the computer to execute the aforementioned related steps to achieve a low short-circuit power consumption power supply with undervoltage protection provided in the above embodiments. The control device, computer-readable storage medium, computer program product, or chip provided in this invention are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here. Through the description of the above embodiments, those skilled in the art can understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the control device can be divided into different functional modules to complete all or some of the functions described above. In the embodiments provided by this invention, it should be understood that the disclosed control device and method can be implemented in other ways. For example, the control device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another control device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, control device or unit, and can be electrical, mechanical or other forms.

[0042] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multiple task processing and parallel processing are possible or may be advantageous. The various embodiments in this specification are described in a progressive manner, and similar modules between different embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The above content is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A low short-circuit power consumption power supply with undervoltage protection, characterized in that, include: The system includes an input filtering and rectification module, a flyback control module, an output undervoltage protection module, and an output filtering and rectification module; among which, One end of the input filter and rectifier module is connected to AC power, and the other end is connected to the flyback control module. It is used to filter and rectify the input AC power to obtain DC power and output it to the flyback control module. The flyback control module is used to detect the current and output voltage of transformer T2 using control chip IC1, adjust the PWM duty cycle based on feedback, drive transistor Q1 through drive resistor and transistor Q2, and detect temperature through the thermistor so that control chip IC1 controls the on / off state of transistor Q1 based on the detected temperature. The output rectifier and filter module is connected to the flyback control module through transformer T2. The output rectifier and filter module is used to rectify and filter the pulsating wave output by transformer T2 and feed it back to the flyback control module. The output undervoltage protection module is connected to the flyback control module via diode D7. During startup, the input AC power charges the startup capacitor through the startup resistor. When the VCC voltage reaches the control chip's turn-on voltage, the control chip enters the operating state. The VCC auxiliary winding of the transformer is filtered and rectified to obtain the VCC1 voltage. When the output voltage exceeds a preset voltage threshold, it enters a constant power state. When the output voltage decreases, the VCC1 voltage decreases. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter-junction voltage drop of the transistor Q1, the VCC voltage decreases, and the control chip enters the undervoltage protection state. When the output is short-circuited, the VCC1 voltage drops, triggering the control chip to enter the undervoltage protection state.

2. The power supply according to claim 1, characterized in that, Output undervoltage protection module, including: The starting resistors R3 and R3a are connected in series. The other end of the starting resistor R3a is connected to one end of capacitors C9 and C10 and one end of starting capacitor CD2a. One end of starting capacitor CD2a is connected to VCC voltage and undervoltage detection circuit. The other ends of capacitors C9 and C10 and the other end of starting capacitor CD2a are connected to undervoltage detection circuit, one end of capacitor CD2, and grounded. The undervoltage detection circuit is used to detect the VCC1 voltage provided by the auxiliary winding of the transformer. When the VCC1 voltage is lower than the sum of the breakdown voltage of the Zener diode ZD2 and the emitter junction voltage drop of the transistor Q1, the control chip is triggered to enter the undervoltage protection state. The undervoltage detection circuit is connected to one end of resistor R11A; the other end of resistor R11A is connected to the other end of resistor R11; the other end of capacitor CD2 is connected to one end of resistor R12, one end of resistor R12a and the VCC1 voltage terminal respectively; the other end of resistor R12 is connected to the other end of resistor R12a and the negative terminal of diode D7 respectively; the positive terminal of diode D7 is connected to the flyback control module.

3. The power supply according to claim 2, characterized in that, The undervoltage detection circuit includes: The positive terminal of the Zener diode ZD2 is connected to one end of the capacitor CD2 and grounded; The positive terminal of diode D8 is connected to one end of resistor R11A and the collector of transistor Q3; the base of transistor Q3 is connected to one end of resistor R11 and one end of resistor R16; the emitter of transistor Q3 is connected to the other end of resistor R11A; the negative terminal of diode D8 is connected to VCC voltage. The other end of resistor R16 is connected to the negative terminal of Zener diode ZD2.

4. The power supply according to claim 1, characterized in that, The flyback control module includes: a flyback circuit and a spike absorption loop; wherein: The flyback circuit includes: the current detection pin of the control chip IC1 is connected to the gate of transistor Q1 through resistors R8 and R6; the source of transistor Q1 is grounded through resistor R5; the drain of transistor Q1 is connected to the first terminal of transformer T2; and a spike absorption circuit. The spike absorption circuit includes: a first end of a resistor network connected to capacitor C2 and the second end of transformer T2; The second end of the resistor network is connected to the negative terminal of diode D1, and the positive terminal of diode D1 is connected to the drain of transistor Q1. The third terminal of transformer T2 is connected to the output filter and rectifier module, and the fourth terminal of transformer T2 is grounded.

5. The power supply according to claim 4, characterized in that, The flyback control module also includes: The feedback pin of the control chip IC1 is connected to one end of capacitor C6 and one end of resistor R22, and the other end of capacitor C6 is grounded; the other end of resistor R22 is connected to one end of resistors R24 and R24a and the first end of optocoupler PH1B, and the other end of resistors R24 and R24a is connected to the second end of optocoupler PH1B, and is connected to the output filter and rectification module through capacitors CY1 and CY2; the two ends of capacitors CY1 and CY2 are respectively connected to the ground terminal; The current detection pin of the control chip IC1 is connected to multiple series resistors through capacitor C5 and then connected to the output filter and rectification module. The over-temperature protection pin of the control chip IC1 is connected to one end of resistor R25 and one end of resistor R10. The other end of resistor R10 is connected to the positive terminal of diode D6. The negative terminal of diode D6 is connected to the thermistor RT1. The other end of resistor R25 is connected to transformer T2. The drive output pin of the control chip IC1 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R9 and the base of transistor Q2. The other end of resistor R9 is connected to the emitter of transistor Q2, one end of resistor R6 and the gate of transistor Q1. The collector of transistor Q2 is connected to resistor R30.

6. The power supply according to claim 5, characterized in that, The current detection pin of control chip IC1 detects the transformer current through capacitor C5, resistors R8, R5a and R5. The feedback pin of control chip IC1 detects the output voltage through capacitor C6, resistors R22, R24, R24a and optocoupler PH1B. The PWM duty cycle output by the drive output pin of control chip IC1 is adjusted by the feedback voltage of the current detection pin and the feedback pin. The drive output pin drives transistor Q1 through resistors R7, R9, R30, transistor Q2, and resistor R6; the over-temperature protection pin detects temperature through resistor R10, diode D6, and thermistor RT1.

7. The power supply according to claim 1, characterized in that, The output filtering and rectification module includes: The third terminal of transformer T2 is connected to one end of parallel resistors R20a and R20b. The other end of parallel resistors R20a and R20b is connected to one end of capacitor C7. The other end of capacitor C7 is connected to the positive terminal of LED D5 through parallel resistors R20c, R20d, and R20E. The negative terminal of LED D5 is connected to the negative terminal of Zener diode ZD1 and one end of an RC circuit. The other end of the RC circuit is connected to a status indicator circuit. The two ends of the status indicator circuit are connected across common-mode inductor LF2. The two ends of common-mode inductor LF2 are respectively connected to the two ends of capacitor C12. The negative terminal of Zener diode ZD1 is connected to the flyback control module through a series resistor. The positive terminal of the Zener diode ZD1 is connected to the feedback control circuit; The feedback control circuit is used to monitor the change signal of the power supply's output voltage and transmit the change signal to the control chip through an optocoupler to adjust the PWM duty cycle.

8. The power supply according to claim 7, characterized in that, Feedback control circuit, including: The positive terminal of Zener diode ZD1 is connected to one end of resistor R14. The other end of resistor R14 is connected to one end of resistor R13 and the first terminal of optocoupler PH1A. The second terminal of optocoupler PH1B is connected to the other end of resistor R13, one end of capacitor C8, and the second terminal of three-terminal regulator IC2. The other end of capacitor C8 is connected to one end of resistor R18. The other end of resistor R18 is connected to one end of resistor R15 and one end of R17b. The other end of resistor R15 is connected to the negative terminal of Zener diode ZD1. The first terminal of the three-terminal regulator IC2 is connected to one end of resistor R17a and one end of resistor R17b, and the third terminal of the three-terminal regulator IC2 is connected to the other end of resistor R17a and the other end of resistor R17b.

9. The power supply according to claim 1, characterized in that, The input filter and rectifier module is also used to clamp the AC input voltage through the fuse Fu1, varistor VDR1 and NTC1; then the input AC is filtered by capacitor CX1 and common mode inductor LF1, and the bridge rectifier BD1 converts the AC into DC output to the flyback control module.

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