A switching power supply with over-power protection

Abstract

The invention discloses a switching power supply with over-power protection, which comprises a control module, a voltage stabilizing module and an over-power protection module; the control module comprises a first chip; the first chip has a sampling end, a feedback end and an output end; the first chip is used to output PWM waves with different duty cycles to control a controllable switch by comparing the voltage values ​​of the sampling end and the feedback end; the duty cycle is increased when the voltage value of the feedback end decreases; the operation is stopped when the voltage value of the sampling end is greater than a first voltage threshold; the voltage stabilizing module is used to lower the voltage value of the feedback end of the first chip when the output power of the switching power supply increases; the over-power protection module is connected in series between the feedback end and the sampling end of the first chip, and is used to raise the voltage value of the sampling end of the first chip when the voltage value of the feedback end of the first chip is less than a second voltage threshold, so that the first chip stops working, thereby improving the accuracy of over-power protection.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and particularly to a switching power supply with over-power protection. Background Art

[0002] In the existing switching power supply system, an over-power protection module is often set up to improve the stability of the system. The common practice of the over-power protection module is to connect the sampling end of the control module to a sampling resistor; when current flows through the sampling resistor, a voltage drop will be generated at the sampling end of the control module. By comparing this voltage drop with the internal voltage threshold and making the main control chip stop working when the voltage at its sampling end exceeds its internal voltage threshold, the effect of over-power protection is achieved.

[0003] However, due to manufacturing process problems, there will be deviations between each sampling resistor and the internal voltage threshold of the control module; therefore, there will be problems such as insufficient accuracy, unfavorable power supply reliability, and easy power supply failure when comparing the internal voltage threshold of the control module with the voltage collected through the sampling resistor.

[0004] In summary, the switching power supply with over-power protection in the prior art still needs to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects or problems in the background art, and provide a switching power supply with over-power protection to improve the accuracy of over-power protection.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A switching power supply with over-power protection, which includes a control module, a voltage stabilizing module, and an over-power protection module; the control module includes a first chip; the first chip has a sampling end, a feedback end, and an output end; it is used to output PWM waves with different duty cycles by comparing the voltage values at the sampling end and the feedback end to control the controllable switch; when the voltage value at its feedback end decreases, the duty cycle is increased; when the voltage value at its sampling end is greater than the first voltage threshold, it stops working; the voltage stabilizing module is connected in series between the voltage output end of the switching power supply and the feedback end of the first chip, and is used to pull down the voltage value at the feedback end of the first chip when the output power of the switching power supply increases; the over-power protection module is connected in series between the feedback end and the sampling end of the first chip, and is used to pull up the voltage value at the sampling end of the first chip when the voltage value at the feedback end of the first chip is less than the second voltage threshold, so that the first chip stops working.

[0008] Further, it further includes an overvoltage protection module; the overvoltage protection module is connected in series between the voltage output terminal of the switching power supply and the sampling terminal of the first chip; it is used to raise the voltage value of the sampling terminal of the first chip when the output voltage of the switching module is greater than the third voltage threshold.

[0009] Further, the first chip further includes a reference voltage terminal; the over-power protection module includes a first resistor, a first diode, a second diode, a first capacitor, a second capacitor, a third capacitor, a second resistor, a first triode, a third resistor and a second triode; one end of the first resistor is connected to the feedback terminal of the first chip, and the other end is grounded through the first capacitor; the second capacitor and the third capacitor are connected in parallel with the first capacitor; the first diode is connected in parallel with the second diode; the second diode is connected in parallel with the first resistor, and its cathode is connected to the feedback terminal of the first chip; one end of the second resistor is connected to the anode of the second diode, and the other end is connected to the base of the first triode; the emitter of the first triode is connected to the reference voltage terminal of the first chip, and its collector is connected to the base of the second triode; the base of the second triode is grounded through the third resistor, its emitter is connected to the emitter of the first triode, and its collector is connected to the sampling terminal of the first chip.

[0010] Further, the overvoltage protection module includes a fourth resistor, a first four-terminal optocoupler, a third diode, a fourth diode, a fifth diode, a sixth diode and a fifth resistor; the first terminal of the first four-terminal optocoupler is used as the power input terminal of the overvoltage protection module, its second terminal is connected to the sampling terminal of the first chip through the fourth resistor, its third terminal is grounded, and its fourth terminal is connected to the anode of the third diode; the cathode of the third diode is connected to the anode of the fifth diode; the cathode of the fifth diode is connected to the voltage output terminal of the switching power supply through the fifth resistor; the fourth diode is connected in parallel with the third diode in the same direction; the sixth diode is connected in parallel with the fifth diode in the same direction.

[0011] Further, the control module further includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, a seventh diode, an eighth diode, a ninth diode, a twelfth diode, a first thermistor, and a third triode; the first pin of the first chip serves as its feedback terminal and is connected to the anode of the eighth diode; its second pin is grounded; its third pin serves as its sampling terminal and is grounded through the fourth capacitor, and is also grounded through the fifth capacitor and the sixth capacitor in sequence; its fourth pin is connected to the base of the third triode, and is also connected to the emitter of the first triode and the collector of the third triode through the sixth resistor; its fifth pin is grounded; its sixth pin serves as its output terminal; its seventh pin serves as the power input terminal and is grounded through the seventh capacitor, and is also grounded through the eighth resistor; its eighth pin serves as the reference voltage terminal and is grounded through the eighth capacitor; the sixth resistor is connected across the first pin and the eighth pin of the first chip; the cathode of the eighth diode is grounded through the ninth capacitor and the tenth capacitor respectively, and is also connected to the anode of the ninth diode; the cathode of the ninth diode is connected to the eighth pin of the first chip; the seventh diode is connected in parallel with the eighth diode; the twelfth diode is connected in parallel with the ninth diode; the emitter of the third triode is connected to the sampling terminal of the first chip through the seventh resistor; one end of the ninth resistor is connected to the power input terminal of the first four-terminal optocoupler, and the other end is connected to the seventh pin of the first chip; the first thermistor is connected in parallel with the ninth resistor.

[0012] Further, the voltage stabilizing module includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a first slide resistor, an eleventh capacitor, a twelfth capacitor, a thirteenth capacitor, an eleventh diode, a twelfth diode, a thirteenth diode, a fourteenth diode, a fifteenth diode, and a second four-terminal optocoupler; the first terminal of the second four-terminal optocoupler is connected to the feedback terminal of the first chip through the eleventh resistor, and is also grounded through the eleventh capacitor; its second terminal is grounded; its second terminal is grounded; its third terminal is connected to the cathode of the thirteenth diode, and is also connected to one end of the twelfth capacitor and the sixteenth resistor that are connected in parallel with each other through the fifteenth resistor and the thirteenth capacitor in sequence; its fourth terminal is connected to the cathode of the fifteenth diode through the fourteenth resistor, and is also connected to the voltage output terminal of the switching power supply through the thirteenth resistor and the twelfth resistor in sequence; the anode of the thirteenth diode is grounded; the fourteenth diode is connected in parallel with the thirteenth diode in the same direction; the other end of the sixteenth resistor is connected to the voltage output terminal of the switching power supply; the anode of the fifteenth diode is grounded, and is also grounded through the nineteenth resistor and the first slide resistor in sequence; the seventeenth resistor is connected in parallel with the nineteenth resistor; the eighteenth resistor is connected in parallel with the first slide resistor; the eleventh diode and the twenty-second diode are connected in parallel in the same direction, and the anode of the eleventh diode is connected to the fourth terminal of the second four-terminal optocoupler, and its cathode is connected between the twelfth resistor and the thirteenth resistor.

[0013] Furthermore, it further includes a filter rectification module, a DC-DC conversion module, and a switch drive module; the filter rectification module is used to connect to an AC input and output a DC voltage; the DC-DC conversion module includes a DC voltage input terminal, a first controllable switch, a second controllable switch, and a current sampling terminal; its DC voltage input terminal is connected to the output terminal of the filter rectification module; its current sampling terminal is connected to the sampling terminal of the first chip; the switch drive module includes an input terminal, a first pulse signal output terminal, and a second pulse signal output terminal; its input terminal is connected to the output terminal of the first chip; its first pulse signal output terminal and second pulse signal output terminal are respectively connected to the control terminals of the first controllable switch and the second controllable switch.

[0014] Further, the DC-DC converter module is a dual-switch forward circuit; the dual-switch forward circuit includes a DC voltage input terminal, a first controllable switch, a second controllable switch, a ninth triode, a first transformer, a nineteenth diode, a twenty-second diode, a twenty-first diode, a twenty-second diode, a twenty-third diode, a twenty-fourth diode, a twenty-fifth diode, a thirtieth resistor, a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, a thirty-sixth resistor, a thirty-seventh resistor, a sixteenth capacitor, a seventeenth capacitor, an eighteenth capacitor, a nineteenth capacitor, a twentieth capacitor, and a twenty-first capacitor; the gate of the first controllable switch serves as its control terminal and is connected to the first pulse signal output terminal, its drain is connected to the DC voltage input terminal, and its source is connected to the cathode of the nineteenth diode; the anode of the nineteenth diode is grounded; the seventeenth capacitor is connected in parallel across the source and drain of the first controllable switch; the thirtieth resistor is connected in series with the sixteenth capacitor and is jointly connected in parallel with the seventeenth resistor; the cathode of the twenty-second diode is connected to the DC voltage input terminal, and its anode is connected to the drain of the second controllable switch; the gate of the second controllable switch serves as its control terminal and is connected to the second pulse signal output terminal, its source is connected to the sampling terminal of the first chip through the thirty-second resistor and is also grounded through the thirty-third resistor; one end of the nineteenth capacitor is connected to the source of the second controllable switch, and the other end is connected to the non-homonymous end of the first primary winding of the first transformer and the drain of the second controllable switch; the positive electrode of the twentieth capacitor is connected to the homonymous end of the second primary winding of the first transformer through the twenty-first capacitor and the thirty-fifth resistor, and its negative electrode is grounded; one end of the thirty-seventh resistor is connected to the base of the ninth triode, and the other end is connected to the collector of the ninth triode; the collector of the ninth triode is connected between the twentieth capacitor and the twenty-first capacitor, and its emitter is connected to the anode of the twenty-fourth diode; the cathode of the twenty-fourth diode is connected to the auxiliary power supply terminal and is connected to the seventh pin of the first chip through the ninth resistor and is also connected to the first end of the first four-terminal optocoupler; the twenty-fifth diode is connected in parallel with the twenty-fourth diode in the same direction; the thirty-sixth resistor is connected in parallel across the collector and emitter of the ninth triode; the twenty-second diode is connected in parallel with the twenty-third diode in the same direction; the anode of the twenty-second diode is grounded, and its cathode is connected to the base of the ninth triode; the cathode of the twenty-first diode is connected to the positive electrode of the twentieth capacitor, and its anode is connected to the homonymous end of the second primary winding of the first transformer through the thirty-fourth resistor; the thirty-fourth resistor is connected in parallel with the thirty-fifth resistor; the first secondary winding of the first transformer is used to connect to the voltage output terminal of the switching power supply.

[0015] Furthermore, the filtering and rectifying module includes a fuse, a first varistor, a thirty-first capacitor, a sixty-fourth resistor, a sixty-fifth resistor, a sixty-sixth resistor, a thirty-second capacitor, a thirty-third capacitor, a first inductor, a thirty-fourth capacitor, a thirty-fifth capacitor, a sixty-third resistor, a sixty-second resistor, a thirty-sixth capacitor, a second inductor, a second thermistor, a thirty-second diode, a thirty-third diode, a thirty-fourth diode, a thirty-fifth diode, a thirty-seventh capacitor, a thirty-eighth capacitor, a sixty-seventh resistor, a sixty-eighth resistor, a sixty-ninth resistor, a seventieth resistor, a second varistor, a third varistor, a forty-third resistor, a forty-fourth resistor, a forty-fifth resistor, a twenty-sixth diode, a twenty-seventh diode, a thirty-ninth capacitor, a thirty-eighth resistor, a thirty-ninth resistor, a fortieth resistor, a forty-first resistor, a forty-second resistor, and a DC power output terminal; the first inductor includes a first coil and a second coil; the second inductor includes a third coil and a fourth coil; the same-name end of the first coil is connected to the live wire of the AC input through the fuse, and is also connected to the non-same-name end of the second inductor through the sixty-second resistor, and its non-same-name end is connected to the same-name end of the third coil; the same-name end of the second coil is connected to the neutral wire of the AC input, and is also connected to the non-same-name end of the fourth coil through the sixty-third resistor, and its non-same-name end is connected to the same-name end of the fourth coil; the first varistor is connected in parallel with the thirty-first capacitor, and is also connected in parallel with the sixty-fourth resistor, the sixty-fifth resistor, and the sixty-sixth resistor connected in series with each other, one end of which is connected to the same-name end of the first coil, and the other end is connected to the same-name end of the second coil; the thirty-second capacitor and the thirty-third capacitor are connected in series with each other and then connected in parallel with the first varistor, and the connection point between the two is grounded; the thirty-fourth capacitor and the thirty-fifth capacitor are connected in series with each other and then connected in parallel with the thirty-sixth capacitor, and the connection point between the two is grounded; the thirty-sixth capacitor is connected across the same-name ends of the third coil and the fourth coil; the non-same-name end of the third coil is connected to the cathode of the thirty-second diode through the second thermistor; the anode of the thirty-second diode is connected to the anode of the thirty-third diode, and is also connected to the DC power output terminal through the third varistor and the second varistor in sequence; the DC power output terminal is connected to the DC voltage input terminal; the cathode of the thirty-third diode is connected to the non-same-name end of the fourth coil, and is also connected to the anode of the thirty-fifth diode; the cathode of the thirty-fifth diode is connected to the cathode of the thirty-fourth diode, and is also connected to the DC power output terminal; the thirty-eighth capacitor is connected in series with the thirty-seventh capacitor and then connected across the anode of the thirty-third diode and the cathode of the thirty-fifth diode; the sixty-seventh resistor is connected in series with the sixty-eighth resistor and then connected in parallel with the thirty-eighth capacitor, and one end of the sixty-seventh resistor is connected to the cathode of the thirty-fifth diode, and one end of the sixty-eighth resistor is connected between the thirty-eighth capacitor and the thirty-seventh capacitor; the sixty-ninth resistor is connected in series with the seventieth resistor and then connected in parallel with the thirty-seventh capacitor, and one end of the seventieth resistor is connected to the anode of the thirty-third resistor;The second varistor and the third varistor are respectively connected in parallel with the thirty-eighth capacitor and the thirty-seventh capacitor; the output terminal of the DC power supply is grounded sequentially through the thirty-eighth resistor, the thirty-ninth resistor, the fortieth resistor, the forty-first resistor and the forty-second resistor; the forty-third resistor is connected in parallel with the thirty-ninth resistor; the forty-fourth resistor is connected in parallel with the fortieth resistor; the forty-fifth resistor is connected in parallel with the forty-first resistor; the thirty-ninth resistor is connected in parallel with the forty-second resistor; the twenty-sixth diode and the twenty-seventh diode are connected in parallel in the same direction, and the cathode of the twenty-sixth diode is connected between the forty-first resistor and the forty-second resistor, and its anode is grounded.;

[0016] Further, the switch driving module further includes a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a twenty-fifth resistor, a twenty-sixth resistor, a twenty-seventh resistor, a twenty-eighth resistor, a twenty-ninth resistor, a fourth triode, a fifth triode, a MOS transistor, a fourteenth capacitor, a fifteenth capacitor, a sixteenth diode, a seventeenth diode, an eighteenth diode and a second transformer; the same-name end of the third primary winding of the second transformer is sequentially connected to the base of the fourth triode through the twenty-second resistor and the twenty-third resistor; the collector of the fourth triode is connected to the non-same-name end of the third primary winding; the anode of the seventeenth diode is connected between the twenty-third resistor and the twenty-second resistor, and its cathode is connected to the emitter of the fourth triode and is connected to the first pulse signal output terminal through the twenty-fifth resistor; the twenty-fourth resistor is connected across the collector and emitter of the fourth triode; the same-name end of the fourth primary winding of the second transformer is sequentially connected to the second pulse signal output terminal through the twenty-eighth resistor and the twenty-ninth resistor; the emitter of the fifth triode is connected to the same-name end of the fourth primary winding, its base is sequentially connected to the non-same-name end of the fourth primary winding through the twenty-seventh resistor and the twenty-sixth resistor, and its collector is connected to the cathode of the eighteenth diode; the anode of the eighteenth diode is connected to the non-same-name end of the fourth primary winding through the twenty-sixth resistor; the same-name end of the second secondary winding of the second transformer is connected to the auxiliary power supply terminal and grounded through the fifteenth capacitor, its non-same-name end is connected to the drain of the MOS transistor and is connected to the same-name end of the third secondary winding of the second transformer through the fourteenth capacitor; the cathode of the sixteenth diode is connected to the same-name end of the second secondary winding, and its cathode is connected to the same-name end of the third secondary winding; the non-same-name end of the third secondary winding is grounded; the gate of the MOS transistor is connected to the output terminal of the first chip through the twentieth resistor and is also grounded through the twenty-first resistor, and its source is grounded.

[0017] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. By connecting an over-power protection module in series between the feedback terminal and the sampling terminal of the first chip, when the voltage value at the feedback terminal of the first chip is less than the second voltage threshold, the voltage value at the sampling terminal of the first chip can be pulled up, and when the voltage value at the sampling terminal of the first chip is greater than the first threshold, the first chip stops working. This setting can improve the accuracy of over-power protection, achieving the effect of multiple over-power protections, and avoiding the problem that when there are deviations between the preset voltage threshold inside the first chip and the resistance value of the sampling resistor and the actual values, it affects the accuracy of the over-power protection module and is not conducive to the reliability of the power supply. By setting a voltage stabilization module between the voltage output terminal of the switching power supply and the feedback terminal of the first chip, when the output power of the switching power supply increases, the voltage stabilization module can pull down the voltage value at the feedback terminal of the first chip, so that the first chip can increase the duty cycle of its output when the voltage value at its feedback terminal decreases to stabilize the output voltage of the switching power supply.

[0019] 2. By setting an over-voltage protection module between the voltage output terminal of the switching power supply and the sampling terminal of the first chip, when the output voltage of the switching power supply is too high, the over-voltage protection module can pull up the voltage value at the sampling terminal of the first chip, causing the first chip to stop working. This setting achieves the effect of multiple protections and is beneficial to improving the reliability of the product.

[0020] 3. By providing the specific circuit structure of the over-power protection module, when the voltage value at the feedback terminal of the first chip is less than the second voltage threshold, the voltage value at the sampling terminal of the first chip can be pulled up, and when the voltage value at the sampling terminal of the first chip is greater than the first threshold, the first chip stops working. Among them, when the voltage value at the feedback terminal of the first chip is less than the second voltage threshold, both the first triode and the second triode are turned on to pull up the voltage at the sampling terminal of the first chip, thereby achieving the effect of over-power protection.

[0021] 4. By providing the specific circuit structure of the over-voltage protection module, when the output voltage of the switching power supply is too high, the over-voltage protection module can pull up the voltage value at the sampling terminal of the first chip. Among them, when the output voltage of the switching power supply is too high, the third diode, the fourth diode, the fifth diode, and the sixth diode are turned on, and the first four-terminal optocoupler is turned on, so that the second terminal of the first four-terminal optocoupler can directly give a voltage exceeding the first voltage threshold to the sampling terminal of the first chip, causing the first chip to stop working, and thus achieving the effect of over-voltage protection.

[0022] 5. By providing the specific circuit structure of the control module, the first chip can output PWM waves with different duty cycles to control the controllable switch by comparing the voltage values at its sampling terminal and feedback terminal; and increase the duty cycle when the voltage value at its feedback terminal decreases, and stop working when the voltage value at its sampling terminal is greater than the first voltage threshold.

[0023] 6. By providing the specific circuit structure of the voltage stabilizing module, the voltage stabilizing module can lower the voltage value of the feedback terminal of the first chip when the output power of the switching power supply increases, so that the first chip can increase the duty cycle of its output when the voltage value of its feedback terminal decreases to stabilize the output voltage of the switching power supply.

[0024] 7. By setting up the filter rectification module, the DC-DC conversion module and the switch driving module, the interference signals existing in the power grid can be filtered out, and the AC power supply of the power grid can be directly rectified into relatively smooth direct current; the setting of the DC-DC conversion module is beneficial to expanding the output application range of the switching power supply, and is also convenient for realizing multiple outputs with different voltages or multiple outputs with the same voltage; the setting of the switch driving module enables the first chip to control the switching frequency of the controllable switch to achieve the effect of stable output.

[0025] 8. By setting the DC-DC conversion module as a double-switch forward circuit, it can be suitable for the use of high-power switching power supplies; this setting is beneficial to improving the utilization rate of the transformer; in addition, the second primary winding of the first transformer and the components connected to the second primary winding together form an auxiliary power supply module to supply power to the voltage stabilizing module, the control module, the switch driving module and the overvoltage protection module.

[0026] 9. By providing the specific circuit structure of the rectification and filtering module, the reliability and stability of the product can be improved; among them, the setting of the second thermistor can reduce the inrush current; the setting of the thirty-second diode, the thirty-third diode, the thirty-fourth diode and the thirty-fifth diode is used to output the DC voltage after rectification; the thirty-eighth capacitor and the thirty-seventh capacitor are connected in series, and each is connected in parallel with two resistors connected in series, which is used to prevent a single capacitor from overvoltage, and at the same time, discharge the thirty-eighth capacitor and the thirty-seventh capacitor when the power is off.

[0027] 10. By providing the specific circuit structure of the switch driving module, the first chip can control the simultaneous on and off of the first controllable switch and the second controllable switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is the circuit schematic diagram of an over-power protection module described in the embodiments of the present invention;

[0030] Figure 2Circuit schematic diagram of an overvoltage protection module according to an embodiment of the present invention;

[0031] Figure 3 Circuit schematic diagram of a control module according to an embodiment of the present invention;

[0032] Figure 4 Circuit schematic diagram of a voltage stabilizing module according to an embodiment of the present invention;

[0033] Figure 5 Circuit schematic diagram of a switch driving module according to an embodiment of the present invention;

[0034] Figure 6 Circuit schematic diagram of a DC-DC converter module according to an embodiment of the present invention;

[0035] Figure 7 Circuit schematic diagram of a filter rectifier module according to an embodiment of the present invention.

[0036] Main reference numeral description:

[0037] First resistor R1, first diode D1, second diode D2, first capacitor C1, second capacitor C2, third capacitor C3, second resistor R2, first triode Q1, third resistor R3, second triode Q2;

[0038] Fourth resistor R4, first four-terminal optocoupler P1, third diode D3, fourth diode D4, fifth diode D5, sixth diode D6, fifth resistor R5;

[0039] First chip U1, sixth resistor R6, seventh resistor R7, eighth resistor R8, ninth resistor R9, tenth resistor R10, fourth capacitor C4, fifth capacitor C5, sixth capacitor C6, seventh capacitor C7, eighth capacitor C8, ninth capacitor C9, tenth capacitor C10, seventh diode D7, eighth diode D8, ninth diode D9, twelfth diode D10, first thermistor RT1, third triode Q3;

[0040] Eleventh resistor R11, twelfth resistor R12, thirteenth resistor R13, fourteenth resistor R14, fifteenth resistor R15, sixteenth resistor R16, seventeenth resistor R17, eighteenth resistor R18, nineteenth resistor R19, first slide resistor RV1, eleventh capacitor C11, twelfth capacitor C12, thirteenth capacitor C13, eleventh diode D11, twelfth diode D12, thirteenth diode D13, fourteenth diode D14, fifteenth diode D15, second four-terminal optocoupler P2;

[0041] The twentieth resistor R20, the twenty - first resistor R21, the twenty - second resistor R22, the twenty - third resistor R23, the twenty - fourth resistor R24, the twenty - fifth resistor R25, the twenty - sixth resistor R26, the twenty - seventh resistor R27, the twenty - eighth resistor R28, the twenty - ninth resistor R29, the fourth triode Q4, the fifth triode Q5, the MOS transistor Q6, the fourteenth capacitor C14, the fifteenth capacitor C15, the sixteenth diode D16, the seventeenth diode D17, the eighteenth diode D18, the second transformer T2;

[0042] The DC voltage input terminal IN1, the first controllable switch Q7, the second controllable switch Q8, the ninth triode Q9, the first transformer T1, the nineteenth diode D19, the twentieth diode D20, the twenty - first diode D21, the twenty - second diode D22, the twenty - third diode D23, the twenty - fourth diode D24, the twenty - fifth diode D25, the thirtieth resistor R30, the thirty - first resistor R31, the thirty - second resistor R32, the thirty - third resistor R33, the thirty - fourth resistor R34, the thirty - fifth resistor R35, the thirty - sixth resistor R36, the thirty - seventh resistor R37, the sixteenth capacitor C16, the seventeenth capacitor C17, the eighteenth capacitor C18, the nineteenth capacitor C19, the twentieth capacitor C20, the twenty - first capacitor C21, the forty - sixth resistor R46, the forty - seventh resistor R47, the forty - eighth resistor R48, the forty - ninth resistor R49, the fiftieth resistor R50, the fifty - first resistor R51, the fifty - second resistor R52, the fifty - third resistor R53, the fifty - fourth resistor R54, the fifty - fifth resistor R55, the fifty - sixth resistor R56, the fifty - seventh resistor, the fifty - eighth resistor R58, the fifty - ninth resistor R59, the sixtieth resistor R60, the sixty - first resistor R61, the twenty - second capacitor C22, the twenty - third capacitor C23, the twenty - fourth capacitor C24, the twenty - fifth capacitor C25, the twenty - sixth capacitor C26, the twenty - seventh capacitor C27, the twenty - eighth capacitor C28, the twenty - ninth capacitor C29, the thirtieth capacitor C30, the first light - emitting diode, the twenty - eighth diode D28, the twenty - ninth diode D29, the thirtieth diode D30, the thirty - first diode D31, the third inductor L3;

[0043] Fuse F1, first varistor ZV1, thirty-first capacitor C31, sixty-fourth resistor R64, sixty-fifth resistor R65, sixty-sixth resistor R66, thirty-second capacitor C32, thirty-third capacitor C33, first inductor L1, thirty-fourth capacitor C34, thirty-fifth capacitor C35, sixty-third resistor R63, sixty-second resistor R62, thirty-sixth capacitor C36, second inductor L2, second thermistor RT2, thirty-second diode D32, thirty-third diode D33, thirty-fourth diode D34, thirty-fifth diode D35, thirty-seventh capacitor C37, thirty-eighth capacitor C38, sixty-seventh resistor R67, sixty-eighth resistor R68, sixty-ninth resistor R69, seventieth resistor R70, second varistor ZV2, third varistor ZV3, forty-third resistor R43, forty-fourth resistor R44, forty-fifth resistor R45, twenty-sixth diode D26, twenty-seventh diode D27, thirty-ninth capacitor C39, thirty-eighth resistor R38, thirty-ninth resistor R39, fortieth resistor R40, forty-first resistor R41, forty-second resistor R42, DC power output terminal O1. Detailed implementation

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are the preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] In the claims, the description, and the above-mentioned drawings of the present invention, unless otherwise clearly defined, when using terms such as "first", "second", or "third", etc., are used to distinguish different objects and not to describe a specific order.

[0046] In the claims, the description, and the above-mentioned drawings of the present invention, unless otherwise clearly defined, for orientation terms, when using terms such as "center", "horizontal", "vertical", "level", "vertical", "top", "bottom", "inner", "outer", "upper", "lower", "front", "rear", "left", "right", "clockwise", "counterclockwise", etc. to indicate the orientation or position relationship, it is based on the orientation and position relationship shown in the drawings, and 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 or be constructed and operated in a specific orientation, so it cannot be understood as limiting the specific protection scope of the present invention.

[0047] In the claims, the description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, when using the terms "fixed connection" or "fixedly connected", it should be understood in a broad sense, that is, any connection method without displacement relationship and relative rotation relationship between the two, that is to say, it includes non-removable fixed connection, removable fixed connection, being integrally formed, and being fixedly connected through other devices or elements.

[0048] In the claims, the description and the above-mentioned drawings of the present invention, when using the terms "comprising", "having" and their variants, are intended to mean "including but not limited to".

[0049] See Figures 1 to 7 , the present invention discloses a switching power supply with over-power protection, which includes a control module, a voltage stabilizing module, an over-power protection module, an over-voltage protection module, a filter rectification module, a DC-DC conversion module and a switch driving module.

[0050] The control module includes a first chip U1; the first chip U1 has a sampling terminal, a feedback terminal, a voltage reference terminal and an output terminal; it is used to output PWM waves with different duty cycles to control the controllable switch by comparing the voltage values of the sampling terminal and the feedback terminal; when the voltage value of its feedback terminal decreases, the duty cycle is increased; when the voltage value of its sampling terminal is greater than the first voltage threshold, it stops working; in the embodiment of the present invention, the first voltage threshold is 1V, and the model of the first chip U1 is UC2844BN. The control module also includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, a seventh diode D7, an eighth diode D8, a ninth diode D9, a twelfth diode D10, a first thermistor RT1 and a third triode Q3.

[0051] The first pin of the first chip U1 is connected to the anode of the eighth diode D8 as the feedback terminal; its second pin is grounded; its third pin is used as the sampling terminal and is grounded through the fourth capacitor C4, and is also grounded through the fifth capacitor C5 and the sixth capacitor C6 in sequence; its fourth pin is connected to the base of the third triode Q3, and is also connected to the emitter of the first triode Q1Q1 and the collector of the third triode Q3 through the sixth resistor R6; its fifth pin is grounded; its sixth pin is used as the output terminal; its seventh pin is used as the power input terminal and is grounded through the seventh capacitor C7, and is also grounded through the eighth resistor R8; its eighth pin is used as the reference voltage terminal and is grounded through the eighth capacitor C8; the sixth resistor R6 is connected between the first pin and the eighth pin of the first chip U1; the cathode of the eighth diode D8 is grounded through the ninth capacitor C9 and the tenth capacitor C10 respectively, and is also connected to the anode of the ninth diode D9; the cathode of the ninth diode D9 is connected to the eighth pin of the first chip U1; the seventh diode D7 is connected in parallel with the eighth diode D8; the twelfth diode D10 is connected in parallel with the ninth diode D9; the emitter of the third triode Q3 is connected to the sampling terminal of the first chip U1 through the seventh resistor R7; one end of the ninth resistor R9 is connected to the power input terminal of the first four-terminal optocoupler P1, and the other end is connected to the seventh pin of the first chip U1; the first thermistor RT1 is connected in parallel with the ninth resistor R9.

[0052] The voltage stabilizing module is connected in series between the voltage output terminal of the switching power supply and the feedback terminal of the first chip U1, and is used to pull down the voltage value of the feedback terminal of the first chip U1 when the output power of the switching power supply increases; in the embodiment of the present invention, the voltage stabilizing module includes the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor, the fifteenth resistor R15, the sixteenth resistor R16, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, the first sliding resistor RV1, the eleventh capacitor C11, the twelfth capacitor C12, the thirteenth capacitor C13, the eleventh diode D11, the twelfth diode D12, the thirteenth diode D13, the fourteenth diode D14, the fifteenth diode D15, and the second four-terminal optocoupler P2.

[0053] The first terminal of the second four-terminal optocoupler P2 is connected to the feedback terminal of the first chip U1 through the eleventh resistor R11 and is also grounded through the eleventh capacitor C11; its second terminal is grounded; its second terminal is grounded; its third terminal is connected to the cathode of the thirteenth diode D13 and is also sequentially connected to one end of the twelfth capacitor C12 and the sixteenth resistor R16 which are connected in parallel with each other through the fifteenth resistor R15 and the thirteenth capacitor C13; its fourth terminal is connected to the cathode of the fifteenth diode D15 through the fourteenth resistor R14 and is also sequentially connected to the voltage output terminal of the switching power supply through the thirteenth resistor R13 and the twelfth resistor R12; the anode of the thirteenth diode D13 is grounded; the fourteenth diode D14 is connected in parallel with the thirteenth diode D13 in the same direction; the other end of the sixteenth resistor R16 is connected to the voltage output terminal of the switching power supply; the anode of the fifteenth diode D15 is grounded and is also sequentially grounded through the nineteenth resistor R19 and the first slide resistor RV1; the seventeenth resistor R17 is connected in parallel with the nineteenth resistor R19; the eighteenth resistor R18 is connected in parallel with the first slide resistor RV1; the eleventh diode D11 and the twenty-second diode D22 are connected in parallel in the same direction, and the anode of the eleventh diode D11 is connected to the fourth terminal of the second four-terminal optocoupler P2, and its cathode is connected between the twelfth resistor R12 and the thirteenth resistor R13.

[0054] The over-power protection module is connected in series between the feedback terminal and the sampling terminal of the first chip U1 and is used to raise the voltage value of the sampling terminal of the first chip U1 when the voltage value at the feedback terminal is less than the second voltage threshold, so that the first chip U1 stops working; in the embodiment of the present invention, the second voltage threshold is 4.5V, and the over-power protection module includes the first resistor R1, the first diode D1, the second diode D2, the first capacitor C1, the second capacitor C2, the third capacitor C3, the second resistor R2, the first triode Q1Q1, the third resistor R3 and the second triode Q2.

[0055] One end of the first resistor R1 is connected to the feedback terminal of the first chip U1, and the other end is grounded through the first capacitor C1; the second capacitor C2 and the third capacitor C3 are connected in parallel with the first capacitor C1; the first diode D1 is connected in parallel with the second diode D2; the second diode D2 is connected in parallel with the first resistor R1, and its cathode is connected to the feedback terminal of the first chip U1; one end of the second resistor R2 is connected to the anode of the second diode D2, and the other end is connected to the base of the first triode Q1Q1; the emitter of the first triode Q1Q1 is connected to the reference voltage terminal of the first chip U1, and its collector is connected to the base of the second triode Q2; the base of the second triode Q2 is grounded through the third resistor R3, its emitter is connected to the emitter of the first triode Q1Q1, and its collector is connected to the sampling terminal of the first chip U1.

[0056] Among them, when the voltage value at the feedback terminal of the first chip U1 is less than the second voltage threshold, both the first triode Q1 and the second triode Q2 are turned on to raise the voltage at the sampling terminal of the first chip U1, thereby achieving the effect of over-power protection.

[0057] The over-voltage protection module is connected in series between the voltage output terminal of the switching power supply and the sampling terminal of the first chip U1; it is used to raise the voltage value at the sampling terminal of the first chip U1 when the output voltage of the switching module is greater than the third voltage threshold; in the embodiment of the present invention, the over-voltage protection module includes a fourth resistor R4, a first four-terminal optocoupler P1, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, and a fifth resistor R5.

[0058] The first end of the first four-terminal optocoupler P1 serves as the power input terminal of the over-voltage protection module, its second end is connected to the sampling terminal of the first chip U1 through the fourth resistor R4, its third end is grounded, and its fourth end is connected to the anode of the third diode D3; the cathode of the third diode D3 is connected to the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the voltage output terminal of the switching power supply through the fifth resistor R5; the fourth diode D4 is connected in parallel with the third diode D3 in the same direction; the sixth diode D6 is connected in parallel with the fifth diode D5 in the same direction.

[0059] Among them, when the output voltage of the switching power supply is too high, the third diode D3, the fourth diode D4, the fifth diode D5, and the sixth diode D6 are turned on and the first four-terminal optocoupler P1 is turned on, so that the second end of the first four-terminal optocoupler P1 can directly give a voltage exceeding the first voltage threshold to the sampling terminal of the first chip U1, causing the first chip U1 to stop working, and then achieving the effect of over-voltage protection.

[0060] The filtering and rectifying module is used to connect to an AC input and output a DC voltage; in an embodiment of the present invention, the filtering and rectifying module includes a fuse F1, a first varistor ZV1, a thirty-first capacitor C31, a sixty-fourth resistor R64, a sixty-fifth resistor R65, a sixty-sixth resistor R66, a thirty-second capacitor C32, a thirty-third capacitor C33, a first inductor L1, a thirty-fourth capacitor C34, a thirty-fifth capacitor C35, a sixty-third resistor R63, a sixty-second resistor R62, a thirty-sixth capacitor C36, a second inductor L2, a second thermistor RT2, a thirty-second diode D32, a thirty-third diode D33, a thirty-fourth diode D34, a thirty-fifth diode D35, a thirty-seventh capacitor C37, a thirty-eighth capacitor C38, a sixty-seventh resistor R67, a sixty-eighth resistor R68, a sixty-ninth resistor R69, a seventieth resistor R70, a second varistor ZV2, a third varistor ZV3, a forty-third resistor R43, a forty-fourth resistor R44, a forty-fifth resistor R45, a twenty-sixth diode D26, a twenty-seventh diode D27, a thirty-eighth-nine capacitor C39, a thirty-eighth resistor R38, a thirty-ninth resistor R39, a fortieth resistor R40, a forty-first resistor R41, a forty-second resistor R42, and a DC power output terminal O1.

[0061] The first inductor L1 includes a first coil and a second coil; the second inductor L2 includes a third coil and a fourth coil; the same-named end of the first coil is connected to the live wire of the AC input through a fuse F1, and is also connected to the non-same-named end of the second inductor L2 through a sixty-second resistor R62, and its non-same-named end is connected to the same-named end of the third coil; the same-named end of the second coil is connected to the neutral wire of the AC input, and is also connected to the non-same-named end of the fourth coil through a sixty-third resistor R63, and its non-same-named end is connected to the same-named end of the fourth coil; the first varistor ZV1 is connected in parallel with the thirty-first capacitor C31, and is also connected in parallel with the sixty-fourth resistor R64, the sixty-fifth resistor R65, and the sixty-sixth resistor R66 connected in series with each other. One end of it is connected to the same-named end of the first coil, and the other end is connected to the same-named end of the second coil; the thirty-second capacitor C32 and the thirty-third capacitor C33 are connected in series with each other and then connected in parallel with the first varistor ZV1, and the connection point between them is grounded; the thirty-fourth capacitor C34 and the thirty-fifth capacitor C35 are connected in series with each other and then connected in parallel with the thirty-sixth capacitor C36, and the connection point between them is grounded; the thirty-sixth capacitor C36 is connected across the same-named ends of the third coil and the fourth coil; the non-same-named end of the third coil is connected to the cathode of the thirty-second diode D32 through the second thermistor RT2; the anode of the thirty-second diode D32 is connected to the anode of the thirty-third diode D33, and is also connected to the DC power supply output terminal O1 through the third varistor ZV3 and the second varistor ZV2 in sequence; the DC power supply output terminal O1 is connected to the DC voltage input terminal IN1; the cathode of the thirty-third diode D33 is connected to the non-same-named end of the fourth coil, and is also connected to the anode of the thirty-fifth diode D35; the cathode of the thirty-fifth diode D35 is connected to the cathode of the thirty-fourth diode D34, and is also connected to the DC power supply output terminal O1; the thirty-eighth capacitor C38 and the thirty-seventh capacitor C37 are connected in series and then connected across the anode of the thirty-third diode D33 and the cathode of the thirty-fifth diode D35; the sixty-seventh resistor R67 and the sixty-eighth resistor R68 are connected in series and then connected in parallel with the thirty-eighth capacitor C38, and one end of the sixty-seventh resistor R67 is connected to the cathode of the thirty-fifth diode D35, and one end of the sixty-eighth resistor R68 is connected between the thirty-eighth capacitor C38 and the thirty-seventh capacitor C37; the sixty-ninth resistor R69 and the seventieth resistor R70 are connected in series and then connected in parallel with the thirty-seventh capacitor C37, and one end of the seventieth resistor R70 is connected to the anode of the thirty-third resistor R33; the second varistor ZV2 and the third varistor ZV3 are respectively connected in parallel with the thirty-eighth capacitor C38 and the thirty-seventh capacitor C37; the DC power supply output terminal O1 is grounded through the thirty-eighth resistor R38, the thirty-ninth resistor R39, the fortieth resistor R40, the forty-first resistor R41, and the forty-second resistor R42 in sequence; the forty-third resistor R43 is connected in parallel with the thirty-ninth resistor R39; the forty-fourth resistor R44 is connected in parallel with the fortieth resistor R40; the forty-fifth resistor R45 is connected in parallel with the forty-first resistor R41;The thirty-ninth resistor R39 is in parallel with the forty-second resistor R42; the twenty-sixth diode D26 and the twenty-seventh diode D27 are connected in parallel in the same direction, and the cathode of the twenty-sixth diode D26 is connected between the forty-first resistor R41 and the forty-second resistor R42, and its anode is grounded.

[0062] Among them, the setting of the second thermistor RT2 can reduce the surge current; the thirty-second diode D32, the thirty-third diode D33, the thirty-fourth diode D34, and the thirty-fifth diode D35 are used to rectify and output a DC voltage; the thirty-eighth capacitor C38 and the thirty-seventh capacitor C37 are connected in series and are each connected in parallel with two resistors in series to prevent overvoltage of a single capacitor; at the same time, when the power is off, the thirty-eighth capacitor C38 and the thirty-seventh capacitor C37 are discharged.

[0063] The DC-DC conversion module includes a DC voltage input terminal IN1, a first controllable switch Q7, a second controllable switch Q8, and a current sampling terminal; its DC voltage input terminal IN1 is connected to the output terminal of the filter rectification module; its current sampling terminal is connected to the sampling terminal of the first chip U1; in the embodiment of the present invention, the DC-DC conversion module is a double-switch forward circuit; the double-switch forward circuit includes a DC voltage input terminal IN1, a first controllable switch Q7, a second controllable switch Q8, a ninth triode, a first transformer T1, a nineteenth diode D19, a twentieth diode D20, a twenty-first diode D21, a twenty-second diode D22, a twenty-third diode D23, a twenty-fourth diode D24, a twenty-fifth diode D25, a thirtieth resistor R30, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35, a thirty-sixth resistor R36, a thirty-seventh resistor R37, a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, a twenty-first capacitor C21, a forty-sixth resistor R46, a forty-seventh resistor R47, a forty-eighth resistor R48, a forty-ninth resistor R49, a fiftieth resistor R50, a fifty-first resistor R51, a fifty-second resistor R52, a fifty-third resistor R53, a fifty-fourth resistor R54, a fifty-fifth resistor R55, a fifty-sixth resistor R56, a fifty-seventh resistor R57, a fifty-eighth resistor R58, a fifty-ninth resistor R59, a sixtieth resistor R60, a sixty-first resistor R61, a twenty-second capacitor C22, a twenty-third capacitor C23, a twenty-fourth capacitor C24, a twenty-fifth capacitor C25, a twenty-sixth capacitor C26, a twenty-seventh capacitor C27, a twenty-eighth capacitor C28, a twenty-ninth capacitor C29, a thirtieth capacitor C30, a first light-emitting diode, a twenty-eighth diode D28, a twenty-ninth diode D29, a thirtieth diode D30, a thirty-first diode D31, and a third inductor L3.

[0064] The gate of the first controllable switch Q7 is connected to the first pulse signal output terminal as its control terminal, its drain is connected to the DC voltage input terminal IN1, and its source is connected to the cathode of the nineteenth diode D19; the anode of the nineteenth diode D19 is grounded; the seventeenth capacitor C17 is connected across the source and drain of the first controllable switch Q7; the thirtieth resistor R30 is connected in series with the sixteenth capacitor C16 and is jointly connected in parallel with the seventeenth resistor R17; the cathode of the twenty-second diode D20 is connected to the DC voltage input terminal IN1, and its anode is connected to the drain of the second controllable switch Q8; the gate of the second controllable switch Q8 is connected to the second pulse signal output terminal as its control terminal, its source is connected to the sampling terminal of the first chip U1 through the thirty-second resistor R32 and is also grounded through the thirty-third resistor R33; one end of the nineteenth capacitor C19 is connected to the source of the second controllable switch Q8, and the other end is connected to the non-homonymous end of the first primary winding of the first transformer T1 and the drain of the second controllable switch Q8; the positive electrode of the twentieth capacitor C20 is connected to the homonymous end of the second primary winding of the first transformer T1 through the twenty-first capacitor C21 and the thirty-fifth resistor R35, and its negative electrode is grounded; one end of the thirty-seventh resistor R37 is connected to the base of the ninth triode, and the other end is connected to the collector of the ninth triode; the collector of the ninth triode is connected between the twentieth capacitor C20 and the twenty-first capacitor C21, and its emitter is connected to the anode of the twenty-fourth diode D24; the cathode of the twenty-fourth resistor R24 is connected to the auxiliary power supply terminal and is connected to the seventh pin of the first chip U1 through the ninth resistor R9 and is also connected to the first end of the first four-terminal optocoupler P1P1; the twenty-fifth diode D25 is connected in parallel with the twenty-fourth diode D24 in the same direction; the thirty-sixth resistor R36 is connected across the collector and emitter of the ninth triode; the twenty-second diode D22 is connected in parallel with the twenty-third diode D23 in the same direction; the anode of the twenty-second diode D22 is grounded, and its cathode is connected to the base of the ninth triode; the cathode of the twenty-first diode D21 is connected to the positive electrode of the twentieth capacitor C20, and its anode is connected to the homonymous end of the second primary winding of the first transformer T1 through the thirty-fourth resistor R34; the thirty-fourth resistor R34 is connected in parallel with the thirty-fifth resistor R35; the first secondary winding of the first transformer T1 is used to connect to the voltage output terminal of the switching power supply; the non-homonymous end of the first secondary winding of the first transformer T1 is connected to the anode of the twenty-eighth diode D28, and its homonymous end is connected to the anode of the thirty-first diode D31 and is also connected to the anode of the twenty-ninth diode D29; the cathode of the twenty-eighth diode D28 is used as the voltage output terminal of the switching power supply; the cathode of the twenty-ninth diode D29 is connected to the cathode of the twenty-eighth diode D28; the anode of the thirtieth diode D30 is connected to the anode of the twenty-eighth diode D28, and its cathode is connected to the cathode of the thirty-first diode D31;The forty-sixth resistor R46, the forty-seventh resistor R47, the forty-eighth resistor R48, and the forty-ninth resistor R49 are connected in parallel. One end of the forty-ninth resistor R49 is connected to the anode of the twenty-eighth diode D28, and the other end is connected to the cathode of the twenty-eighth diode D28 through the twenty-third capacitor C23 and is also connected to the cathode of the twenty-eighth diode D28 through the twenty-second capacitor C22. One end of the fiftieth resistor R50 is connected to the same-name end of the first secondary winding, and the other end is connected to the cathode of the thirtieth diode D30 through the twenty-fourth capacitor C24 and the twenty-fifth capacitor C25 connected in parallel with each other. One end of the third inductor L3 is connected to the same-name end of the first secondary winding, and the other end is connected to the cathode of the twenty-eighth diode D28 through the fifty-first resistor R51. The fifty-second resistor R52, the fifty-third resistor R53, the fifty-fourth resistor R54, the fifty-fifth resistor R55, the fifty-sixth resistor R56, the fifty-seventh resistor R57, the fifty-eighth resistor R58, the fifty-ninth resistor R59, the sixtieth resistor R60, the twenty-sixth capacitor C26, the twenty-seventh capacitor C27, and the twenty-eighth capacitor C28 are all connected in parallel with the fifty-first resistor R51. The sixty-first resistor R61 is connected in series with the first light-emitting diode and then connected in parallel with the fifty-first resistor R51. The twenty-ninth capacitor C29 and the thirtieth capacitor C30 are connected in series and then connected in parallel with the fifty-first resistor R51. One end of the twenty-ninth capacitor C29 is connected to the voltage output terminal of the switching power supply, and the other end is grounded. One end of the thirtieth capacitor C30 is common-grounded with the twenty-ninth capacitor C29, and the other end is grounded.

[0065] The switch driving module includes an input terminal, a first pulse signal output terminal, and a second pulse signal output terminal. Its input terminal is connected to the output terminal of the first chip U1. Its first pulse signal output terminal and second pulse signal output terminal are respectively connected to the control terminals of the first controllable switch Q7 and the second controllable switch Q8. In the embodiment of the present invention, the switch driving module further includes the twentieth resistor R20, the twenty-first resistor R21, the twenty-second resistor R22, the twenty-third resistor R23, the twenty-fourth resistor R24, the twenty-fifth resistor R25, the twenty-sixth resistor R26, the twenty-seventh resistor R27, the twenty-eighth resistor R28, the twenty-ninth resistor R29, the fourth triode Q4, the fifth triode Q5, the MOS transistor Q6, the fourteenth capacitor C14, the fifteenth capacitor C15, the sixteenth diode D16, the seventeenth diode D17, the eighteenth diode D18, and the second transformer T2.

[0066] The same-name end of the third primary winding of the second transformer T2 is sequentially connected to the base of the fourth triode Q4 through the twenty-second resistor R22 and the twenty-third resistor R23; the collector of the fourth triode Q4 is connected to the non-same-name end of the third primary winding; the anode of the seventeenth diode D17 is connected between the twenty-third resistor R23 and the twenty-second resistor R22, its cathode is connected to the emitter of the fourth triode Q4, and is connected to the first pulse signal output end through the twenty-fifth resistor R25; the twenty-fourth resistor R24 is connected across the collector and emitter of the fourth triode Q4; the same-name end of the fourth primary winding of the second transformer T2 is sequentially connected to the second pulse signal output end through the twenty-eighth resistor R28 and the twenty-ninth resistor R29; the emitter of the fifth triode Q5 is connected to the same-name end of the fourth primary winding, its base is sequentially connected to the non-same-name end of the fourth primary winding through the twenty-seventh resistor R27 and the twenty-sixth resistor R26, and its collector is connected to the cathode of the eighteenth diode D18; the anode of the eighteenth diode D18 is connected to the non-same-name end of the fourth primary winding through the twenty-sixth resistor R26; the same-name end of the second secondary winding of the second transformer T2 is connected to the auxiliary power supply end, and is grounded through the fifteenth capacitor C15, its non-same-name end is connected to the drain of the MOS transistor Q6, and is connected to the same-name end of the third secondary winding of the second transformer T2 through the fourteenth capacitor C14; the cathode of the sixteenth diode D16 is connected to the same-name end of the second secondary winding, its cathode is connected to the same-name end of the third secondary winding; the non-same-name end of the third secondary winding is grounded; the gate of the MOS transistor Q6 is connected to the output end of the first chip U1 through the twentieth resistor R20, and is also grounded through the twenty-first resistor R21, and its source is grounded.

[0067] In summary, a switching power supply with over-power protection provided by the present invention can effectively improve the accuracy of over-power protection, achieve the effect of multiple over-power protections, and is beneficial to improving the reliability and stability of the switching power supply.

[0068] The descriptions of the above specification and embodiments are used to explain the protection scope of the present invention, but do not constitute a limitation to the protection scope of the present invention. Through the inspiration of the present invention or the above embodiments, those of ordinary skill in the art, combined with common general knowledge, ordinary technical knowledge in the art and / or the prior art, through logical analysis, reasoning or limited experiments, can obtain modifications, equivalent replacements or other improvements to the embodiments of the present invention or some of its technical features, which should all be included within the protection scope of the present invention.

Claims

1. A switching power supply with over-power protection, characterized in that: It includes a control module, which includes a first chip; the first chip has a sampling terminal, a feedback terminal and an output terminal; It is used to output PWM waves with different duty cycles by comparing the voltage values of the sampling terminal and the feedback terminal to control the controllable switch; when the voltage value of its feedback terminal decreases, it increases the duty cycle; when the voltage value of its sampling terminal is greater than the first voltage threshold, it stops working; a voltage regulation module, which is connected in series between the voltage output terminal of the switching power supply and the feedback terminal of the first chip, and is used to pull down the voltage value of the feedback terminal of the first chip when the output power of the switching power supply increases; and an over-power protection module, which is connected in series between the feedback terminal and the sampling terminal of the first chip, and is used to pull up the voltage value of the sampling terminal of the first chip when the voltage value of the feedback terminal is less than the second voltage threshold, so that the first chip stops working; the first chip also includes a reference voltage terminal; the over-power protection module includes a first resistor, a first diode, a second diode, a first capacitor, a second capacitor, a third capacitor, a second resistor, a first triode, a third resistor and a second triode; One end of the first resistor is connected to the feedback terminal of the first chip, and the other end is grounded through the first capacitor; the second capacitor and the third capacitor are connected in parallel with the first capacitor; The first diode is connected in parallel with the second diode; the second diode is connected in parallel with the first resistor, and its cathode is connected to the feedback terminal of the first chip; one end of the second resistor is connected to the anode of the second diode, and the other end is connected to the base of the first triode; the emitter of the first triode is connected to the reference voltage terminal of the first chip, and its collector is connected to the base of the second triode; the base of the second triode is grounded through the third resistor, its emitter is connected to the emitter of the first triode, and its collector is connected to the sampling terminal of the first chip.

2. The switching power supply with over-power protection according to claim 1, characterized in that: It further includes an over-voltage protection module; The over-voltage protection module is connected in series between the voltage output terminal of the switching power supply and the sampling terminal of the first chip; it is used to pull up the voltage value of the sampling terminal of the first chip when the output voltage of the switching power supply is greater than the third voltage threshold.

3. The switching power supply with over-power protection according to claim 2, characterized in that: The over-voltage protection module includes a fourth resistor, a first four-terminal optocoupler, a third diode, a fourth diode, a fifth diode, a sixth diode and a fifth resistor; The first terminal of the first four-terminal optocoupler serves as the power input terminal of the overvoltage protection module. Its second terminal is connected to the sampling terminal of the first chip through the fourth resistor. Its third terminal is grounded. Its fourth terminal is connected to the anode of the third diode. The cathode of the third diode is connected to the anode of the fifth diode. The cathode of the fifth diode is connected to the voltage output terminal of the switching power supply through the fifth resistor. The fourth diode is connected in parallel with the third diode in the same direction. The sixth diode is connected in parallel with the fifth diode in the same direction.

4. A switching power supply with over-power protection as described in claim 3, characterized in that: the control module further includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, a seventh diode, an eighth diode, a ninth diode, a twelfth diode, a first thermistor, and a third triode; the first pin of the first chip serves as the feedback terminal and is connected to the anode of the eighth diode. Its second pin is grounded. Its third pin serves as the sampling terminal and is grounded through the fourth capacitor, and also grounded through the fifth capacitor and the sixth capacitor in sequence. Its fourth pin is connected to the base of the third triode, and also connected to the emitter of the first triode and the collector of the third triode through the sixth resistor; its fifth pin is grounded. Its sixth pin serves as the output terminal; its seventh pin serves as the power input terminal and is grounded through the seventh capacitor, and also grounded through the eighth resistor. Its eighth pin serves as the reference voltage terminal and is grounded through the eighth capacitor; the sixth resistor is connected across the first pin and the eighth pin of the first chip. The cathode of the eighth diode is grounded through the ninth capacitor and the tenth capacitor respectively, and is also connected to the anode of the ninth diode. The cathode of the ninth diode is connected to the eighth pin of the first chip. The seventh diode is connected in parallel with the eighth diode; the twelfth diode is connected in parallel with the ninth diode; the emitter of the third triode is connected to the sampling terminal of the first chip through the seventh resistor; one end of the ninth resistor is connected to the power input terminal of the first four-terminal optocoupler, and the other end is connected to the seventh pin of the first chip. The first thermistor is connected in parallel with the ninth resistor.

5. A switching power supply with over-power protection as described in claim 4, characterized in that: the voltage stabilization module includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a first slide resistor, an eleventh capacitor, a twelfth capacitor, a thirteenth capacitor, an eleventh diode, a twelfth diode, a thirteenth diode, a fourteenth diode, a fifteenth diode, and a second four-terminal optocoupler; the first terminal of the second four-terminal optocoupler is connected to the feedback terminal of the first chip through the eleventh resistor, and is also grounded through the eleventh capacitor. Its second terminal is grounded. Its second terminal is grounded; Its third terminal is connected to the cathode of the thirteenth diode, and also sequentially passes through the fifteenth resistor and the thirteenth capacitor and is connected to one end of the twelfth capacitor and the sixteenth resistor that are connected in parallel with each other; its fourth terminal is connected to the cathode of the fifteenth diode through the fourteenth resistor, and also sequentially passes through the thirteenth resistor and the twelfth resistor and is connected to the voltage output terminal of the switching power supply; The anode of the thirteenth diode is grounded; the fourteenth diode is connected in parallel with the thirteenth diode in the same direction; The other end of the sixteenth resistor is connected to the voltage output terminal of the switching power supply; The anode of the fifteenth diode is grounded, and also sequentially passes through the nineteenth resistor and the first sliding resistor and is grounded; The seventeenth resistor is connected in parallel with the nineteenth resistor; the eighteenth resistor is connected in parallel with the first sliding resistor; The eleventh diode and the twelfth diode are connected in parallel in the same direction, and the anode of the eleventh diode is connected to the fourth terminal of the second four-terminal optocoupler, and its cathode is connected between the twelfth resistor and the thirteenth resistor.

6. A switching power supply with over-power protection as described in claim 5, characterized in that: It further includes a filter rectification module, a DC-DC conversion module and a switching drive module; The filter rectification module is used to connect to an AC input and output a DC voltage; The DC-DC conversion module includes a DC voltage input terminal, a first controllable switch, a second controllable switch and a current sampling terminal; its DC voltage input terminal is connected to the output terminal of the filter rectification module; Its current sampling terminal is connected to the sampling terminal of the first chip; The switching drive module includes an input terminal, a first pulse signal output terminal and a second pulse signal output terminal; Its input terminal is connected to the output terminal of the first chip; Its first pulse signal output terminal and second pulse signal output terminal are respectively connected to the control terminals of the first controllable switch and the second controllable switch.

7. A switching power supply with over-power protection as described in claim 6, characterized in that: The DC-DC conversion module is a dual-switch forward circuit; the dual-switch forward circuit includes the DC voltage input terminal, the first controllable switch, the second controllable switch, the ninth triode, the first transformer, the nineteenth diode, the twenty-second diode, the twenty-first diode, the twenty-second diode, the twenty-third diode, the twenty-fourth diode, the twenty-fifth diode, the thirtieth resistor, the thirty-first resistor, the thirty-second resistor, the thirty-third resistor, the thirty-fourth resistor, the thirty-fifth resistor, the thirty-sixth resistor, the thirty-seventh resistor, the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor, the nineteenth capacitor, the twentieth capacitor and the twenty-first capacitor; The gate of the first controllable switch serves as its control terminal and is connected to the first pulse signal output terminal, its drain is connected to the DC voltage input terminal, and its source is connected to the cathode of the nineteenth diode; the anode of the nineteenth diode is grounded; The seventeenth capacitor is connected across the source and drain of the first controllable switch; the thirtieth resistor is connected in series with the sixteenth capacitor and they are jointly connected in parallel with the seventeenth resistor; the cathode of the twenty-second diode is connected to the DC voltage input terminal, and its anode is connected to the drain of the second controllable switch; The gate of the second controllable switch is connected to the second pulse signal output terminal as its control terminal. Its source is connected to the sampling terminal of the first chip through the thirty-second resistor and is also grounded through the thirty-third resistor; one end of the nineteenth capacitor is connected to the source of the second controllable switch, and the other end is connected to the drain of the second controllable switch and the non-homonymous end of the first primary winding of the first transformer; The positive electrode of the twentieth capacitor is connected to the homonymous end of the second primary winding of the first transformer through the twenty-first capacitor and the thirty-fifth resistor, and its negative electrode is grounded; one end of the thirty-seventh resistor is connected to the base of the ninth triode, and the other end is connected to the collector of the ninth triode; the collector of the ninth triode is connected between the twentieth capacitor and the twenty-first capacitor, and its emitter is connected to the anode of the twenty-fourth diode; the cathode of the twenty-fourth diode is connected to the seventh pin of the first chip through the ninth resistor as the auxiliary power supply terminal and is also connected to the first end of the first four-terminal optocoupler; the twenty-fifth diode is connected in parallel with the twenty-fourth diode in the same direction; the thirty-sixth resistor is connected across the collector and emitter of the ninth triode; the twenty-second diode is connected in parallel with the twenty-third diode in the same direction; the anode of the twenty-second diode is grounded, and its cathode is connected to the base of the ninth triode; The cathode of the twenty-first diode is connected to the positive electrode of the twentieth capacitor, and its anode is connected to the homonymous end of the second primary winding of the first transformer through the thirty-fourth resistor; the thirty-fourth resistor is connected in parallel with the thirty-fifth resistor; the first secondary winding of the first transformer is used to connect to the voltage output terminal of the switching power supply.

8. A switching power supply with over-power protection as described in claim 7, characterized in that: The filter rectification module includes a fuse, a first varistor, a thirty-first capacitor, a sixty-fourth resistor, a sixty-fifth resistor, a sixty-sixth resistor, a thirty-second capacitor, a thirty-third capacitor, a first inductor, a thirty-fourth capacitor, a thirty-fifth capacitor, a sixty-third resistor, a sixty-second resistor, a thirty-sixth capacitor, a second inductor, a second thermistor, a thirty-second diode, a thirty-third diode, a thirty-fourth diode, a thirty-fifth diode, a thirty-seventh capacitor, a thirty-eighth capacitor, a sixty-seventh resistor, a sixty-eighth resistor, a sixty-ninth resistor, a seventieth resistor, a second varistor, a third varistor, a forty-third resistor, a forty-fourth resistor, a forty-fifth resistor, a twenty-sixth diode, a twenty-seventh diode, a thirty-ninth capacitor, a thirty-eighth resistor, a thirty-ninth resistor, a fortieth resistor, a forty-first resistor, a forty-second resistor and a DC power output terminal; The first inductor includes a first coil and a second coil; the second inductor includes a third coil and a fourth coil; the same-named end of the first coil is connected to the live wire of the AC input through the fuse, and is also connected to the non-same-named end of the second inductor through the sixty-second resistor, and its non-same-named end is connected to the same-named end of the third coil; the same-named end of the second coil is connected to the neutral wire of the AC input, and is also connected to the non-same-named end of the fourth coil through the sixty-third resistor, and its non-same-named end is connected to the same-named end of the fourth coil; the first varistor is connected in parallel with the thirty-first capacitor, and is also connected in parallel with the sixty-fourth resistor, the sixty-fifth resistor, and the sixty-sixth resistor connected in series with each other, one end of which is connected to the same-named end of the first coil, and the other end of which is connected to the same-named end of the second coil; the thirty-second capacitor and the thirty-third capacitor are connected in series with each other and then connected in parallel with the first varistor, and the connection point between the two is grounded; The thirty-fourth capacitor and the thirty-fifth capacitor are connected in series with each other and then connected in parallel with the thirty-sixth capacitor, and the connection point between the two is grounded; the thirty-sixth capacitor is connected across the same-named end of the third coil and the same-named end of the fourth coil; The non-same-named end of the third coil is connected to the cathode of the thirty-second diode through the second thermistor; the anode of the thirty-second diode is connected to the anode of the thirty-third diode, and is also connected to the DC power supply output terminal through the third varistor and the second varistor in sequence; the DC power supply output terminal is connected to the DC voltage input terminal; the cathode of the thirty-third diode is connected to the non-same-named end of the fourth coil, and is also connected to the anode of the thirty-fifth diode; the cathode of the thirty-fifth diode is connected to the cathode of the thirty-fourth diode, and is also connected to the DC power supply output terminal; The thirty-eighth capacitor is connected in series with the thirty-seventh capacitor and then connected across the anode of the thirty-third diode and the cathode of the thirty-fifth diode; the sixty-seventh resistor and the sixty-eighth resistor are connected in series with each other and then connected in parallel with the thirty-eighth capacitor, and one end of the sixty-seventh resistor is connected to the cathode of the thirty-fifth diode, and one end of the sixty-eighth resistor is connected between the thirty-eighth capacitor and the thirty-seventh capacitor; the sixty-ninth resistor and the seventieth resistor are connected in series with each other and then connected in parallel with the thirty-seventh capacitor, and one end of the seventieth resistor is connected to the anode of the thirty-third resistor; the second varistor and the third varistor are respectively connected in parallel with the thirty-eighth capacitor and the thirty-seventh capacitor; The output terminal of the DC power supply is grounded sequentially through the 38th resistor, the 39th resistor, the 40th resistor, the 41st resistor, and the 42nd resistor; the 43rd resistor is connected in parallel with the 39th resistor; the 44th resistor is connected in parallel with the 40th resistor; the 45th resistor is connected in parallel with the 41st resistor; the 39th resistor is connected in parallel with the 42nd resistor; the 26th diode and the 27th diode are connected in parallel in the same direction, and the cathode of the 26th diode is connected between the 41st resistor and the 42nd resistor, and its anode is grounded.

9. A switching power supply with over-power protection as claimed in claim 8, characterized in that: the switching drive module further includes a 20th resistor, a 21st resistor, a 22nd resistor, a 23rd resistor, a 24th resistor, a 25th resistor, a 26th resistor, a 27th resistor, a 28th resistor, a 29th resistor, a 4th triode, a 5th triode, a MOS transistor, a 14th capacitor, a 15th capacitor, a 16th diode, a 17th diode, an 18th diode, and a 2nd transformer; The same-name end of the third primary winding of the second transformer is connected to the base of the fourth triode sequentially through the 22nd resistor and the 23rd resistor; the collector of the fourth triode is connected to the non-same-name end of the third primary winding; the anode of the 17th diode is connected between the 23rd resistor and the 22nd resistor, its cathode is connected to the emitter of the fourth triode, and is connected to the first pulse signal output terminal through the 25th resistor; the 24th resistor is connected across the collector and emitter of the fourth triode; The same-name end of the fourth primary winding of the second transformer is connected to the second pulse signal output terminal sequentially through the 28th resistor and the 29th resistor; the emitter of the fifth triode is connected to the same-name end of the fourth primary winding, its base is connected to the non-same-name end of the fourth primary winding sequentially through the 27th resistor and the 26th resistor, and its collector is connected to the cathode of the 18th diode; the anode of the 18th diode is connected to the non-same-name end of the fourth primary winding through the 26th resistor; The same-name end of the second secondary winding of the second transformer is connected to the auxiliary power supply terminal, and is grounded through the 15th capacitor, its non-same-name end is connected to the drain of the MOS transistor, and is connected to the same-name end of the third secondary winding of the second transformer through the 14th capacitor; the cathode of the 16th diode is connected to the same-name end of the second secondary winding, its cathode is connected to the same-name end of the third secondary winding; the non-same-name end of the third secondary winding is grounded; the gate of the MOS transistor is connected to the output terminal of the first chip through the 20th resistor, and is also grounded through the 21st resistor, and its source is grounded.

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