Type-II compensation anti-false-triggering self-recovery over-current protection circuit of switching power supply

Abstract

The invention discloses a type-II compensation anti-false-triggering self-recovery overcurrent protection circuit of a switching power supply, which belongs to the technical field of switching power supply safety and comprises a control switching power supply chip, an isolation optocoupler circuit, a current detection circuit, an operational amplifier unit and the like. The current detection circuit can indicate whether the output current is in an overcurrent state signal to the overcurrent protection control end based on the output end of the switching power supply, and the driving circuit can transmit an overcurrent protection signal to the first control output end of the switching power supply in time when the overcurrent indication signal indicates that the switching power supply is in an overcurrent state. And the purpose of over-current protection is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of switch power supply safety, and relates to a type II compensation anti-false triggering self-recovery overcurrent protection circuit of a switch power supply. Background Art

[0002] When the circuit system is running, accidents often occur due to the malfunction of the overcurrent protection in the system, which brings huge losses to the economy. This paper proposes measures to be taken for the malfunction of overcurrent protection and various situations, and puts forward the direction of improving overcurrent protection. my country is in an important period of economic development, and the demand for power supply in all walks of life is increasing. Therefore, preventing power accidents has become an urgent problem to be solved. When the circuit system is running, various faults and abnormal operating conditions may occur. The most common and most dangerous fault is various forms of short circuit. When a short circuit occurs, the short-circuit current flowing through the fault point is very large, which may destroy the stability of the parallel operation of the system. Therefore, it is necessary to configure overcurrent protection in the system. However, in some cases, even if the action value and time of the overcurrent protection device used are reasonably matched, it may malfunction due to the failure to cooperate well with other protections in the system, causing the entire system to fail. Therefore, as the circuit structure becomes increasingly compact, whether the overcurrent protection can operate correctly is very important for the safe and stable operation of the circuit system. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a type II compensation overcurrent protection circuit for a switching power supply with anti-false triggering and self-recovery.

[0004] The technical solution adopted by the present invention is: a type II compensation anti-false triggering self-recovery overcurrent protection circuit of a switching power supply, characterized in that: it includes a resistor R01, a capacitor C01, a resistor R01, a capacitor C02, a diode D01, and a power control chip U1; the HV pin of the power control chip U1 is connected to one end of the resistor R01 and the other end of the resistor R01 of the type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is connected to the non-polar capacitor C01, and the other end of the capacitor is connected to the ground; one end of the resistor R02 is connected to one end of the non-polar capacitor C02 and one end of the non-polar capacitor C02 is connected to pin 1 of the transformer T1, and the other end of the non-polar capacitor C02 is connected to the negative pole of the switching diode D01; the positive pole of the switching diode D01 is connected to one end of the DRAIN of the power control chip U1 and the positive pole of the switching diode D01 is connected to pin 2 of the transformer T1.

[0005] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized in that: the CS pin of the power control chip U1 is connected to one end of the non-polar capacitor C03, and the other end of the non-polar capacitor C03 is connected to the ground; the COMP pin of the power control chip U1 is connected to one end of the resistor R03, and the other end of the resistor R03 is connected to one end of R04; the other end of the resistor R04 is connected to one end of the non-polar capacitor C04 and one end of the non-polar capacitor C04 is connected to pin 4 of the photocoupler OC1, and the other end of the non-polar capacitor C04 is connected to pin 3 of the photocoupler OC1 and pin 3 of the photocoupler OC1 is connected to the ground.

[0006] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized in that: pin 2 of the photoelectric coupler OC1 is connected to one end of the resistor R05 and to the ground, and pin 1 of the photoelectric coupler OC1 is connected to the other end of the resistor R05; the other end of the resistor R05 is connected to the output end of the operational amplifier U2, the positive voltage input end of the operational amplifier U2 is connected to the external 5V voltage input, the positive voltage input end of the operational amplifier U2 is connected to one end of the non-polar capacitor C05, and the other end of the non-polar capacitor C05 is connected to the ground; the output end of the operational amplifier U2 is connected to one end of the resistor R06 and to the non-polar capacitor C07, and the other end of the resistor R06 is connected to one end of the non-polar capacitor C06; the inverting input terminal of the operational amplifier U2 is connected to the other end of the non-polar capacitor C07 and the other end of the non-polar capacitor C06, the inverting input terminal of the operational amplifier U2 is connected to one end of the non-polar capacitor C09, and the other end of the non-polar capacitor C09 is connected to the ground; the non-inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R08 and one end of the non-polar capacitor C08, the non-inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R07, the other end of the resistor R07 is connected to the ground, and the non-polar capacitor C08 is connected to the ground.

[0007] The second-type compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized by: the operational amplifier U2 loop compensation calculation formula is:

[0008]

[0009] Simplified:

[0010] in R06=R16G (G represents the gain required for the crossover frequency)

[0011] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized in that: the output end of the operational amplifier U3 is connected to one end of the non-polar capacitor C10 and to the resistor R09; the positive voltage input end of the operational amplifier U3 is connected to one end of the non-polar capacitor C11 and to one end of the resistor R10, one end of the non-polar capacitor C11 is connected to the ground, the other end of the resistor R09 is connected to the reverse input end of the operational amplifier U3, and the other end of the non-polar capacitor C11 is connected to the ground; the resistor R The other end of 10 is connected to the external 5V voltage; the negative voltage input terminal of the operational amplifier U3 is connected to the ground; the in-phase input terminal of the operational amplifier U3 is connected to one end of the resistor R13, to one end of the non-polar capacitor C12, to one end of the capacitor R12 and to one end of the non-polar capacitor C13; the inverting input terminal of the operational amplifier U3 is connected to the other end of the non-polar capacitor C13 and to one end of the resistor R11, and the other end of the resistor R11 is connected to the ground; the other end of the resistor R12 is connected to the external 5V voltage.

[0012] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized in that: the reference end of the voltage regulator U4 is connected to the positive electrode of the voltage regulator U4, the reference end of the voltage regulator U4 is connected to one end of the resistor R16, the reference end of the voltage regulator U4 is connected to one end of the resistor R15, the reference end of the voltage regulator U4 is connected to one end of the non-polar capacitor C14, and the reference end of the voltage regulator U4 is connected to one end of the resistor R14; the other end of the resistor R14 is connected to the ground, the other end of the non-polar capacitor C14 is connected to the ground, and the negative electrode of the voltage regulator U4 is connected to the ground; the resistor R16 is connected to the inverting input end of the operational amplifier U2, and the other end of the resistor R15 is connected to the positive output end of the circuit.

[0013] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized in that: pin 4 of the transformer T1 is connected to the positive electrode of the voltage regulator diode D02, and the negative electrode of the voltage regulator diode D02 is connected to the positive electrode of the power supply output terminal; one end of the non-polar capacitor C15 is connected to the negative electrode of the voltage regulator diode D02, and the other end of the non-polar capacitor C15 is connected to pin 3 of the transformer T1, and pin 3 of the transformer T1 is connected to the negative electrode of the power supply output terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate that the drawings in the embodiments of the present application are only some embodiments of the present application, for the common technical solutions in this field, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, for the technical personnel described below, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 is the circuit flow chart;

[0016] Figure 2 This is a circuit overview diagram;

[0017] Figure 3 is the circuit schematic; DETAILED DESCRIPTION

[0018] The present invention will now be further described in conjunction with the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0020] Example 1

[0021] Figure 1 and Figure 2 As shown, a type II compensation anti-false triggering self-recovery overcurrent protection circuit of a switching power supply includes an AC input 1, a control chip 2, an optical coupler 3, an operational amplifier 4, a 431 voltage regulator 5, a transformer 6 and a DC output 7. The AC input 1 is connected to the transformer 6 through a rectifier bridge and a capacitor filter, and the output of the transformer 6 is adjusted by the control of the control chip 2. The transformer 6 is connected to the DC output 7 through a diode and a capacitor filter to provide a DC output. The 431 voltage regulator 5 samples the current of the DC output 7, and outputs it to the optical coupler 3 through the conversion output of the operational amplifier 4 to achieve safe isolation. The optical coupler 3 feeds back to the control chip 2 to control the input duty cycle to achieve safe and stable overcurrent protection.

[0022] Specifically, after the AC input 1 is rectified by the rectifier bridge, the positive end is input to the HV pin of the control chip 2 through the resistor R01 to realize the collection of the input voltage. The DRAIN pin of the control chip 2 is connected to the 2nd pin of the transformer 6, and the 1st pin and the 2nd pin of the transformer 6 are connected in series through the voltage-stabilizing diode D01 and the non-polar capacitor C02 to realize the output feedback of the duty cycle to the transformer, thereby affecting the DC output.

[0023] like Figure 1 and Figure 3 As shown, the type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply, the CS pin of the power control chip U1 is connected to one end of the non-polar capacitor C03, and the other end of the non-polar capacitor C03 is connected to the ground; the GND pin of the power control chip U1 is connected to one end of the resistors R03 and R04 respectively, and the other ends of the resistors R03 and R04 are connected to the ground; the COMP pin of the power control chip U1 is connected to one end of the non-polar capacitor C04 and one end of the non-polar capacitor C04 is connected to the 4th pin of the photoelectric coupler OC1, and the other end of the non-polar capacitor C04 is connected to the 3rd pin of the photoelectric coupler OC1 and the 3rd pin of the photoelectric coupler OC1 is connected to the ground. The photoelectric coupler 3 receives the signal and feeds it back to the COMP pin of the control chip 2 to realize the information collection of the output current, and outputs the duty cycle through the DRAIN pin of the control chip 2, effectively realizing the isolation protection of the output and input, and improving the safety of the circuit.

[0024] The self-recovery unit is connected by a photocoupler 3 and an operational amplifier 4, and includes a voltage comparison circuit, a charge and discharge circuit, and a voltage clamping circuit; the reverse input terminal of the voltage comparison circuit is electrically connected to the output terminal of the operational amplifier circuit 4; the output terminal of the voltage comparison circuit is electrically connected to the reverse input terminal of the operational amplifier circuit; the voltage clamping circuit is electrically connected to the output terminal of the operational amplifier circuit and the reverse input terminal of the voltage comparison circuit, and is used to clamp the voltage of the reverse input terminal of the voltage comparison circuit to a value lower than the voltage of the same-direction input terminal of the voltage comparison circuit when the current is normal.

[0025] The current of DC output 7 is transmitted to operational amplifier 4 through the voltage division of 431 voltage regulator tube 5 to realize current detection. The reference end of 431 voltage regulator tube is connected to the positive electrode to obtain the reference voltage. The resistors R15 and R14 are adjusted to adjust the reference, and the voltage is transmitted to operational amplifier 4 for comparison. When the current fluctuates, it can be filtered through capacitor C14 and the capacitor in the operational amplifier circuit to avoid false triggering.

[0026] The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply of the present invention includes an overcurrent detection protection unit, a self-recovery unit and an anti-false triggering unit, and the overcurrent detection protection unit includes a current sensing resistor, a reference circuit, and an operational amplifier circuit. The power input end is connected to the transformer power output end through the current sensing resistor; the reference circuit is used to provide a reference voltage for the operational amplifier circuit; the reverse input end of the operational amplifier circuit is electrically connected to the first action end of the switching tube circuit; the output end of the operational amplifier circuit is electrically connected to the photoelectric coupler. The self-recovery unit includes a voltage comparison circuit and a voltage clamping circuit. The reverse input end of the voltage comparison circuit is electrically connected to the output end of the operational amplifier circuit; the output end of the voltage comparison circuit is electrically connected to the reverse input end of the operational amplifier circuit; the voltage clamping circuit is electrically connected to the output end of the operational amplifier circuit and the reverse input end of the voltage comparison circuit. In the normal current state, the operational amplifier circuit outputs a low-level signal, the photocoupler outputs a signal, and is connected to the control chip; in the overcurrent state, the operational amplifier circuit adjusts the output through the feedback loop so that the power input terminal outputs a constant current value, and the capacitor is charged through the charging loop. When the charging voltage value is greater than the voltage at the same-direction input terminal of the voltage comparison circuit, the voltage comparison circuit outputs a low-level level, the operational amplifier circuit outputs a high-level signal, and the photocoupler does not respond; then, the capacitor is discharged through the discharge loop. When the voltage at the reverse input terminal of the voltage comparison circuit is lower than the voltage at the same-direction input terminal, the voltage comparison circuit outputs a high-level level, the operational amplifier circuit outputs a low-level signal, the switch tube circuit is turned on again, and the circuit returns to normal. When the current fluctuates, the capacitor C14 and the capacitor in the operational amplifier circuit can be used for filtering to avoid false triggering.

[0027] The present invention adds a compensation structure of a photoelectric coupler and an operational amplifier, which is more stable and reliable, low-cost, high-efficiency and stable.

[0028] When overcurrent is detected, the power input terminal is made to output a constant current, which can prevent the power supply from being damaged by excessive current.

[0029] The present invention is a pure hardware circuit, which can automatically detect overcurrent and self-recover to prevent false triggering, and has high stability and reliability.

[0030] The above are only specific implementations of the present invention, which cannot be used to limit the scope of the present invention. Equivalent changes made by ordinary technicians in this technical field based on this creation, as well as changes known to technicians in this field, should still fall within the scope of the present invention.

[0031] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A type II compensation overcurrent protection circuit for switching power supply with anti-false triggering and self-recovery, characterized in that A switching power supply input terminal, a MOS drive circuit, a control unit, an operational amplifier unit, and a current detection unit. The current detection circuit can indicate to the overcurrent protection control terminal whether the output current is in an overcurrent state signal based on the input terminal of the switching power supply. The drive circuit can transmit an overcurrent protection signal to the first control input terminal of the switching power supply in a timely manner when the overcurrent indication signal indicates that the switching power supply is in an overcurrent state.

2. The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply according to claim 1, characterized in that: The switching power supply is connected to the control integrated chip through the RCD clamping circuit, and the collected current information is used to control the AC voltage input duty cycle.

3. The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply according to claim 1, characterized in that: The control integrated chip is connected to the isolation optocoupler, and noise is reduced through resistor and capacitor voltage division to receive the signal transmitted by the isolation optocoupler. When the natural frequency of the optocoupler is lower than the high-frequency pole, it can provide good noise resistance.

4. The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply according to claim 1, characterized in that: Pin 2 of the photoelectric coupler OC1 is connected to one end of the resistor R05 and to the ground, and pin 1 of the photoelectric coupler OC1 is connected to the other end of the resistor R05; the other end of the resistor R05 is connected to one end of the resistor R17; the other end of the resistor R17 is connected to the output end of the operational amplifier U2, the positive voltage input end of the operational amplifier U2 is connected to the external 5V voltage input, the positive voltage input end of the operational amplifier U2 is connected to one end of the non-polar capacitor C05, and the other end of the non-polar capacitor C05 is connected to the ground; the output end of the operational amplifier U2 is connected to one end of the resistor R06 and to one end of the non-polar capacitor C07. The inverting input terminal of the operational amplifier U2 is connected to the other end of the non-polar capacitor C07 and the other end of the non-polar capacitor C06, the inverting input terminal of the operational amplifier U2 is connected to one end of the non-polar capacitor C09, and the other end of the non-polar capacitor C09 is connected to the ground; the non-inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R08 and one end of the non-polar capacitor C08, the non-inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R07, the other end of the resistor R07 is connected to the ground, and the non-polar capacitor C08 is connected to the ground.

5. The second-type compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized by: The output end of the operational amplifier U3 is connected to one end of the non-polar capacitor C10 and to the resistor R09; the voltage positive input end of the operational amplifier U3 is connected to one end of the non-polar capacitor C11 and to one end of the resistor R10, one end of the non-polar capacitor C11 is connected to the ground, the other end of the resistor R09 is connected to the reverse input end of the operational amplifier U3, and the other end of the non-polar capacitor C11 is connected to the ground; the other end of the resistor R10 is connected to the external 5V voltage; The negative voltage input terminal of the operational amplifier U3 is connected to the ground; the non-inverting input terminal of the operational amplifier U3 is connected to one end of the resistor R13, to one end of the non-polar capacitor C12, to one end of the capacitor R12 and to one end of the non-polar capacitor C13; the inverting input terminal of the operational amplifier U2 is connected to the other end of the non-polar capacitor C13 and to one end of the resistor R11, and the other end of the resistor R11 is connected to the ground; the other end of the resistor R12 is connected to the external 5V voltage.

6. The type II compensation anti-false triggering self-recovery overcurrent protection circuit of the switching power supply is characterized by: The reference end of the voltage regulator U4 is connected to the positive electrode of the voltage regulator U4, the reference end of the voltage regulator U4 is connected to one end of the resistor R16, the reference end of the voltage regulator U4 is connected to one end of the resistor R15, the reference end of the voltage regulator U4 is connected to one end of the non-polar capacitor C14, and the reference end of the voltage regulator U4 is connected to one end of the resistor R14; the other end of the resistor R14 is connected to the ground, the other end of the non-polar capacitor C14 is connected to the ground, and the negative electrode of the voltage regulator U4 is connected to the ground; the resistor R16 is connected to the inverting input end of the operational amplifier U2, and the other end of the resistor R15 is connected to the positive output end of the circuit.

Images