Magnetic saturation overcurrent protection system and protection method of bridge type power circuit for power supply

Abstract

According to the magnetic saturation overcurrent protection system and protection method of the bridge type power circuit for the power supply, an output module is used for obtaining electric energy from two output ends of the bridge type power circuit and outputting the electric energy outwards, the output module comprises a capacitor C3, a winding L1, a winding L2 and a winding L3, the capacitor C3 is electrically connected with the winding L1, and the winding L2 is electrically connected with the winding L3. The capacitor C3 and the winding L1 are connected in series between two output ends of the bridge type power circuit, and the winding L1 is matched with the winding L2; the acquisition module is used for outputting a protection signal and comprises a winding L4, a diode D3 and a capacitor C2 which are electrically connected, the winding L4 is matched with the winding L3, and a protection signal output end is formed between the diode D3 and the capacitor C2; the protection module is used for receiving the protection signal and blocking or opening the bridge type power circuit according to the protection signal; according to the invention, the voltage stress of the switching tube is reduced when the bridge type power circuit is in an output short circuit state and in primary side overcurrent protection, the response speed is high, the sensitivity is high, the reliability of a system is improved, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of power supply overcurrent protection circuits, in particular to a magnetic saturation overcurrent protection system and a protection method for a bridge power circuit used in a power supply. Background Art

[0002] The bridge power circuit is a basic electronic circuit topology that mainly realizes functions such as isolated power conversion. The bridge power circuit can be composed of four switching tubes to form an "H-bridge" structure. Bridge power circuits are used in many power supplies, such as server power supplies or module power supplies. Traditional overcurrent protection for bridge power circuits often uses two methods: primary current transformer to detect primary current or detect the voltage on the resonant capacitor. The primary current transformer detects the primary current because the current transformer CT is added separately, which increases the design cost; the signal with a voltage of about 1V lower at the signal output end is easily interfered, and the delay and sensitivity are affected by the process and parameter errors of the current transformer, and there is a certain degree of uncertainty; detect the voltage on the resonant capacitor. This protection method requires the capacitor reference point to be grounded. In terms of detection mechanism, it is the same as the current transformer, and passive detection is performed from the primary side. If a secondary side fault occurs, there is a certain hysteresis. Summary of the invention

[0003] In order to solve the problem of poor overcurrent protection of bridge power circuits in the prior art, the present invention provides a magnetic saturation overcurrent protection system and a protection method for a bridge power circuit for a power supply, which improves the effect of overcurrent protection of the bridge power circuit.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: a magnetic saturation overcurrent protection system for a bridge power circuit for a power supply, comprising: an output module, a collection module and a protection module; The output module is used to obtain electric energy from the two output ends of the bridge power circuit and output it externally. The output module includes a capacitor C3, a winding L1, a winding L2 and a winding L3. The capacitor C3 is electrically connected to the winding L1, the winding L2 is electrically connected to the winding L3, the capacitor C3 and the winding L1 are connected in series between the two output ends of the bridge power circuit, and the winding L1 and the winding L2 cooperate with each other; The acquisition module is used to output the protection signal. The acquisition module includes an electrically connected winding L4, a diode D3 and a capacitor C2. The winding L4 and the winding L3 cooperate with each other, and a protection signal output terminal is formed between the diode D3 and the capacitor C2. The protection module is used to receive the protection signal and block or open the bridge power circuit according to the protection signal.

[0005] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the acquisition module includes a winding L5, a rectifier unit and a discharge unit. The head end of the winding L5 is electrically connected to the tail end of the winding L4. The rectifier unit includes an electrically connected diode D4 and a capacitor C4. The discharge unit includes an electrically connected resistor R1 and a transistor Q1. The positive electrode of the diode D4 is connected to the tail end of the winding L5, the negative electrode of the diode D4 is connected to the positive electrode of the capacitor C4, the pin 1 of R1 is connected to the positive electrode of the capacitor C2, the pin 2 of R1 is connected to the collector of the transistor Q1, and the base of the transistor Q1 is connected to the positive electrode of the capacitor C4.

[0006] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, a resistor R5, a voltage regulator X1 and a resistor R4 are electrically connected between the positive electrode of the capacitor C4 and the base of the transistor Q1, pin 1 of the resistor R5 is connected to the base of the transistor Q1, pin 2 of the resistor R5 is connected to the positive electrode of the voltage regulator X1, the negative electrode of the voltage regulator X1 is connected to pin 1 of the resistor R4, and pin 2 of the resistor R4 is connected to the positive electrode of the capacitor C4.

[0007] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the output module includes a diode D1, a capacitor C1, a resistor R3 and a diode D2, the positive electrode of the diode D1 is connected to the head end of the winding L2, the negative electrode of the diode D1 is connected to the positive electrode of the capacitor C1 and pin 1 of the resistor R3, the positive electrode of the diode D2 is connected to the tail end of the winding L3, and the negative electrode of the diode D2 is connected to the positive electrode of the capacitor C1 and pin 1 of the resistor R3.

[0008] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the output module includes an electrically connected capacitor C5 and a capacitor C6, and the capacitor C5 and the capacitor C6 are both electrically connected to the bridge power circuit.

[0009] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the overcurrent protection system includes a driving module, the protection module includes a resistor R52, a capacitor C50, a resistor C55, a transistor Q50, a transistor Q52, a resistor R49 and a resistor R50, pin 1 of the resistor R52 is connected to the protection signal output end, pin 2 of the resistor R52 is respectively connected to the positive electrode of the capacitor C50, pin 1 of the resistor R55, the collector of the transistor Q50 and the base of the transistor Q52, the negative electrode of the capacitor C50, pin 2 of the resistor R55 and the emitter of the transistor Q52 are all connected to GND, pin 1 of the resistor R49 is connected to the voltage signal +12V, pin 2 of the resistor R49 is respectively connected to the driving module, pin 1 of the resistor R50 and the emitter of the transistor Q50, and pin 2 of the resistor R50 is respectively connected to the base of the transistor Q50 and the collector of the transistor Q52.

[0010] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the driving module includes two driving sub-units, the driving sub-units include a driving chip, an isolation pulse transformer and a driving signal input circuit connected to the input end of the driving chip, and the driving chip enable end is connected to pin 2 of the resistor R49.

[0011] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the drive signal input circuit includes a first drive resistor, a second drive resistor, a drive capacitor and a third drive resistor, and an upper control signal input terminal is formed between pin 1 of the first drive resistor and pin 1 of the second drive resistor, pin 2 of the first drive resistor is respectively connected to the positive electrode of the drive capacitor, pin 1 of the third resistor and the input terminal of the drive chip, and pin 2 of the second drive resistor, the negative electrode of the drive capacitor and pin 2 of the third drive resistor are all connected to the ground terminal of the drive chip.

[0012] As a further optimization of the magnetic saturation overcurrent protection system of a bridge power circuit for a power supply, the isolation pulse transformer includes an electrically connected primary winding and a secondary winding, the primary winding is connected to the output end of the driving chip, and the secondary winding is connected to the bridge power circuit.

[0013] The technical solution adopted by the present invention to solve the above technical problems is: a protection method, based on the above magnetic saturation overcurrent protection system, comprising: When the bridge power circuit is short-circuited, the current through winding L1 increases instantaneously, the current through winding L3 increases, and the currents of windings L4 and L5 increase accordingly, and the acquisition module outputs a protection signal; The protection module receives the protection signal and blocks the bridge power circuit according to the protection signal.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an output module, a collection module and a protection module. The output module is used to obtain electric energy from two output ends of a bridge power circuit and output it to the outside. The output module includes a capacitor C3, a winding L1, a winding L2 and a winding L3. The capacitor C3 is electrically connected to the winding L1, the winding L2 is electrically connected to the winding L3, the capacitor C3 and the winding L1 are connected in series between the two output ends of the bridge power circuit, and the winding L1 and the winding L2 cooperate with each other. The collection module is used to output a protection signal. The collection module includes an electrically connected winding L4, a diode D3 and a capacitor C2. The winding L4 and the winding L3 cooperate with each other, and a protection signal output end is formed between the diode D3 and the capacitor C2. The protection module is used to receive the protection signal and block or open the bridge power circuit according to the protection signal. The voltage stress of the switch tube U1, the switch tube U2, the switch tube U3 and the switch tube U4 is reduced when the bridge power circuit is in an output short-circuit state and a primary side overcurrent protection is performed, the response speed is fast and the sensitivity is high, the reliability of the system is improved, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the circuit diagram of bridge power circuit, output module and acquisition module; Figure 2 It is the circuit diagram of protection module and driving module; Figure 3 It is the circuit diagram of the isolation pulse transformer; Figure 4 It is a block diagram of the circuit protection method; Figure 5 It is the block diagram of the driver module; Figure 6 This is the transformer magnetic coupling schematic; Figure 7 It is the waveform diagram of the experimental results. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. The parts that are not described and disclosed in detail in the following embodiments of the present invention should be understood as existing technologies known or should be known to those skilled in the art, such as the structure of a bridge power circuit.

[0017] A magnetic saturation overcurrent protection system for a bridge power circuit for a power supply, such as Figure 1-Figure 6As shown, it includes: an output module, a collection module and a protection module; the output module is used to obtain electric energy from the two output ends of the bridge power circuit and output it to the outside, and the bridge power circuit includes switch tubes U1, U2, U3 and U4. The output module includes a capacitor C3, a winding L1, a winding L2 and a winding L3, the capacitor C3 and the winding L1 are electrically connected, the winding L2 and the winding L3 are electrically connected, the capacitor C3 and the winding L1 are connected in series between the two output ends of the bridge power circuit, and the winding L1 and the winding L2 cooperate with each other; the output module includes a diode D1, a capacitor C1, a resistor R3 and a diode D2, the positive electrode of the diode D1 is connected to the head end of the winding L2, the negative electrode of the diode D1 is connected to the positive electrode of the capacitor C1 and the pin 1 of the resistor R3, the positive electrode of the diode D2 is connected to the tail end of the winding L3, the negative electrode of the diode D2 is connected to the positive electrode of the capacitor C1 and the pin 1 of the resistor R3, and the diode D1, the capacitor C1, the resistor R3 and the diode D2 form a full-wave rectifier circuit; the output module includes an electrically connected capacitor C5 and a capacitor C6, and the capacitor C5 and the capacitor C6 are both electrically connected to the bridge power circuit.

[0018] The acquisition module is used to output a protection signal. The acquisition module includes an electrically connected winding L4, a diode D3 and a capacitor C2. The winding L4 and the winding L3 cooperate with each other, and a protection signal output end is formed between the diode D3 and the capacitor C2; the acquisition module includes a winding L5, a rectifier unit and a discharge unit. The head end of the winding L5 is electrically connected to the tail end of the winding L4. The rectifier unit includes an electrically connected diode D4 and a capacitor C4. The discharge unit includes an electrically connected resistor R1 and a transistor Q1. The positive electrode of the diode D4 is connected to the tail end of the winding L5, the negative electrode of the diode D4 is connected to the positive electrode of the capacitor C4, the pin 1 of R1 is connected to the positive electrode of the capacitor C2, the pin 2 of R1 is connected to the collector of the transistor Q1, and the base of the transistor Q1 is connected to the positive electrode of the capacitor C4.

[0019] A resistor R5, a voltage regulator X1 and a resistor R4 are electrically connected between the positive electrode of the capacitor C4 and the base of the transistor Q1, pin 1 of the resistor R5 is connected to the base of the transistor Q1, pin 2 of the resistor R5 is connected to the positive electrode of the voltage regulator X1, the negative electrode of the voltage regulator X1 is connected to pin 1 of the resistor R4, and pin 2 of the resistor R4 is connected to the positive electrode of the capacitor C4.

[0020] Winding L1, winding L2, winding L3, winding L4 and winding L5 together form transformer T1, and the transformer plays the role of isolation and voltage reduction in the circuit. Winding L4 and winding L5 are magnetic transfer overcurrent protection windings. The number of winding turns is designed to meet the maximum rectified voltage not exceeding 12V, and the rectifier circuit adopts half-wave rectification. Winding L4 is connected to diode D3 and capacitor C2, and the voltage after rectification is a DC detection voltage. Winding L5 is connected to diode D4, capacitor C4, resistor R4, voltage regulator X1, resistor R5, transistor Q1, and resistor R1. Among them, diode D4 and capacitor C4 constitute a rectifier circuit. When the output end of transformer T1 is short-circuited, the transformer magnetic field is short-circuited by the secondary, and the iron core loses its magnetism at this time, and the voltage of transformer windings L4 and L5 disappears; after rectification, the voltage at the signal output end decreases accordingly, and the speed is reduced by 10ns, blocking the drive signal output.

[0021] The protection module is used to receive the protection signal and block or open the bridge power circuit according to the protection signal. The overcurrent protection system includes a driving module, and the protection module includes a resistor R52, a capacitor C50, a resistor C55, a transistor Q50, a transistor Q52, a resistor R49 and a resistor R50, wherein the pin 1 of the resistor R52 is connected to the protection signal output end, the pin 2 of the resistor R52 is respectively connected to the positive electrode of the capacitor C50, the pin 1 of the resistor R55, the collector of the transistor Q50 and the base of the transistor Q52, the negative electrode of the capacitor C50, the pin 2 of the resistor R55 and the emitter of the transistor Q52 are all connected to GND, the pin 1 of the resistor R49 is connected to the voltage signal +12V, the pin 2 of the resistor R49 is respectively connected to the driving module, the pin 1 of the resistor R50 and the emitter of the transistor Q50, and the pin 2 of the resistor R50 is respectively connected to the base of the transistor Q50 and the collector of the transistor Q52. The driving module includes two driving sub-units, each of which controls two switch tubes in the bridge power circuit. In this scheme, the first driving sub-unit controls the switch tubes U1 and U3, and the second driving sub-unit controls the switch tubes U2 and U4. The driving sub-unit includes a driving chip, an isolation pulse transformer, and a driving signal input circuit connected to the input end of the driving chip, and the driving chip enable end is connected to the 2nd pin of the resistor R49. When the protection module receives the protection signal output by the protection signal output end, the driving transistor Q52 is turned on, and the emitter of the transistor Q50 is pulled down, so that the driving chip enable end of the driving module is pulled down, so as to achieve the purpose of blocking the driving module. At this time, the bridge power circuit cannot be driven and the output is turned off. The trigger signal is represented by Triger in the figure, and the trigger signal comes from the input end of the protection circuit or the block diagram of the driving SHUT DOWN pin. The transistors Q50, Q52 and their resistors of the present invention constitute a latch peripheral circuit, and the latch peripheral circuit and the UCC27524 enable pins PIN1, PIN8, Q50 and Q52 constitute a latch. When the short-circuit trigger signal arrives, the signal is transmitted to the network corresponding to the EN label, triggering the two latch devices, causing the enable pin of UCC27524 to be pulled low for a long time until the power is cut off and restarted, or the power supply equipment is manually restarted to eliminate the fault.

[0022] The driving signal input circuit includes a first driving resistor, a second driving resistor, a driving capacitor and a third driving resistor. A high-level control signal input terminal is formed between pin 1 of the first driving resistor and pin 1 of the second driving resistor. Pin 2 of the first driving resistor is respectively connected to the positive electrode of the driving capacitor, pin 1 of the third resistor and the input terminal of the driving chip. Pin 2 of the second driving resistor, the negative electrode of the driving capacitor and pin 2 of the third driving resistor are all connected to the ground terminal of the driving chip. Since the driving module includes two driving sub-units, the driving signal input circuit of one of the driving sub-units includes a first A circuit and a first B circuit with the same structure. The first driving resistor in the first A circuit is connected to the ground terminal of the driving chip. Figure 2The first driving resistor in the first B circuit is represented by a resistor R58, the second driving resistor is represented by a resistor R60, the third driving resistor is represented by a resistor R62, and the driving capacitor is represented by a capacitor C57; Figure 2 The upper control signal in the first A circuit is represented by EPWM1A, the upper control signal in the first B circuit is represented by EPWM1B, and the drive signal input circuit of another drive subunit includes a second A circuit and a second B circuit with the same structure. The upper control signal in the second A circuit is represented by EPWM2A, and the upper control signal in the second B circuit is represented by EPWM2B. The structure of the second A circuit is the same as that of the first A circuit, and the structure of the second B circuit is the same as that of the second B circuit, which will not be described in detail here.

[0023] There are RCs around the driver chip to play a decoupling role, and the driver chip plays a role in current amplification. In the first A circuit, the upper control signal EPWM1A from the DSP is input and processed into the lower control signal PWM1A output. In the first B circuit, the upper control signal EPWM1B from the DSP is input and processed into the lower control signal PWM1B output; in the second A circuit, the upper control signal EPWM2A from the DSP is input and processed into the lower control signal PWM2A output; in the second B circuit, the upper control signal EPWM2B from the DSP is input and processed into the lower control signal PWM2B output.

[0024] The first output terminal of the driver chip in the first driver subunit outputs a lower control signal PWM1A, and the second output terminal outputs a lower control signal PWM1B; the first output terminal of the driver chip in the second driver subunit outputs a lower control signal PWM2A, and the second output terminal outputs a lower control signal PWM2B. The isolation pulse transformer includes an electrically connected primary winding and a secondary winding, the primary winding is connected to the output terminal of the driver chip, and the secondary winding is connected to the bridge power circuit, respectively driving two power switch tubes connected in series on the same side.

[0025] Figure 3The capacitor C101, resistor R105, resistor R106, diode D101 and transformer T100 are the primary windings, and their main function is magnetic isolation, which transmits the PWM pulse square wave to the secondary side. The capacitor C101 plays the role of isolating the DC. When the circuit starts working, the pulse square wave signal is transmitted to the secondary winding through the isolation pulse transformer. Since the transformer has three windings, the "*" in the figure is the same-name end of the winding. According to the principle of electromagnetic induction, that is, the current flows into the * of the primary side, and must flow out from the * of the secondary side. When the lower control signal PWM1A is a pulse high voltage The current flows into the port 6 on the primary side and flows out from the port 5, so that the current is induced in the secondary winding, the current flows out from the end with the same name, and the current flows out from the corresponding port 1, and the induced potential is high; a driving voltage of about 12V is generated, and the K3 signal is output to the driving gate of the switch tube U3 through resistor R108, capacitor C103 and resistor R107, and returns to the 2nd foot of the winding through DZ103, and repeats the cycle; D102 in the circuit plays the role of negative voltage clamping; resistor R109, transistor Q101, and resistor R111 play the role of rapid shutdown. Similarly, the port 3 of the other winding is also a current output, the induced voltage is positive, and the port 4 is negative; since the port 4 is connected to the gate of the switch tube U1, there is no positive voltage at this time, so the drive is turned off, and finally the K1 signal disappears; in order to lower the control signal PWM1B is a pulse high level, the lower control signal PWM1A is a low level, the driving signal direction is opposite, the port 4 is a high level to drive the K1 end to open, the port 2 is high and the port 1 is low, and there is no drive; in order to avoid direct damage, the MOSFET switch tube on the resonant converter H-bridge circuit is also considered To provide conditions for achieving zero voltage switching, the two-way drive K1 signal and K3 signal, as well as the K2 signal and K4 signal, which are staggered, are designed with a dead time of about 1us; the drive circuit drives the two switch tubes in the same bridge arm; the K1 signal and the K4 signal have the same phase; the K2 signal and the K3 signal have the same phase; after the drive is turned on, the switch tube U1 and the switch tube U4 are turned on at the same time, or the switch tube U2 and the switch tube U3 are turned on at the same time, and high-voltage positive and negative pulse signals are generated on the primary side of the power transformer, which are coupled to the secondary side winding through the power transformer, and transfer energy to the output of the power supply through the rectifier and filter circuit.

[0026] By adding a third check winding in the bridge converter; when the output is short-circuited, according to the principle of electromagnetic induction, the excitation inductance of the primary side winding L1 becomes zero, the excitation inductance of the overcurrent detection winding L4 and the winding L5 is also zero, and only the transformer leakage inductance that does not participate in the coupling remains on the primary side. The current of the transformer main winding can reach several times that of the stable state. If no protection device is added, the MOSFET switch tube may be easily burned out if the protection is not timely.

[0027] The present invention uses the secondary transformer winding coupling relationship. When the output of the bridge converter is short-circuited, windings L4 and L5 are also short-circuited, and the voltages of windings L4 and L5 decrease rapidly. During the voltage drop, due to the superposition of the reverse bias voltage of the voltage regulator X1, it cannot be turned on in advance, the transistor Q1 is turned off, the capacitor C2 is quickly charged, and the network voltage of the VC connection is raised. According to the signal jump on the capacitor C2, a trigger protection signal is generated, the signal end is connected to the protection pin of the drive chip, and the drive switch is blocked to prevent the switch tube from being burned by a large current. A delayed start circuit can also be added according to the circuit requirements to make a repeated hiccup start mode and a locked shutdown mode.

[0028] In order to verify the present invention, simulation experiments were carried out. Figure 7 As shown in the figure, the output voltage V(vout) becomes zero volts when the output voltage is short-circuited at 20ms. After the output voltage drops to zero, the voltage of the magnetic feedback input winding after rectification also drops to zero volts after a 10ns delay; I(L1) is the primary main winding current waveform, and the primary current increases rapidly after the short circuit.

[0029] The protection method, based on the above magnetic saturation overcurrent protection system, comprises: When the bridge power circuit is short-circuited, the current through winding L1 increases instantaneously, the current through winding L3 increases, and the currents of windings L4 and L5 increase accordingly, and the acquisition module outputs a protection signal; The protection module receives the protection signal and blocks the bridge power circuit according to the protection signal.

[0030] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetic saturation overcurrent protection system for a bridge power circuit for a power supply, characterized in that: include: Output module, acquisition module and protection module; The output module is used to obtain electric energy from the two output ends of the bridge power circuit and output it externally. The output module includes a capacitor C3, a winding L1, a winding L2 and a winding L3. The capacitor C3 is electrically connected to the winding L1, the winding L2 is electrically connected to the winding L3, the capacitor C3 and the winding L1 are connected in series between the two output ends of the bridge power circuit, and the winding L1 and the winding L2 cooperate with each other; The acquisition module is used to output the protection signal. The acquisition module includes an electrically connected winding L4, a diode D3 and a capacitor C2. The winding L4 and the winding L3 cooperate with each other, and a protection signal output terminal is formed between the diode D3 and the capacitor C2. The protection module is used to receive the protection signal and block or open the bridge power circuit according to the protection signal.

2. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 1, characterized in that: The acquisition module includes a winding L5, a rectifier unit and a discharge unit. The head end of the winding L5 is electrically connected to the tail end of the winding L4. The rectifier unit includes an electrically connected diode D4 and a capacitor C4. The discharge unit includes an electrically connected resistor R1 and a transistor Q1. The positive electrode of the diode D4 is connected to the tail end of the winding L5, the negative electrode of the diode D4 is connected to the positive electrode of the capacitor C4, the pin 1 of R1 is connected to the positive electrode of the capacitor C2, the pin 2 of R1 is connected to the collector of the transistor Q1, and the base of the transistor Q1 is connected to the positive electrode of the capacitor C4.

3. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 2, characterized in that: A resistor R5, a voltage regulator X1 and a resistor R4 are electrically connected between the positive electrode of the capacitor C4 and the base of the transistor Q1, pin 1 of the resistor R5 is connected to the base of the transistor Q1, pin 2 of the resistor R5 is connected to the positive electrode of the voltage regulator X1, the negative electrode of the voltage regulator X1 is connected to pin 1 of the resistor R4, and pin 2 of the resistor R4 is connected to the positive electrode of the capacitor C4.

4. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 1, characterized in that: The output module includes a diode D1, a capacitor C1, a resistor R3 and a diode D2, the anode of the diode D1 is connected to the head end of the winding L2, the cathode of the diode D1 is connected to the anode of the capacitor C1 and pin 1 of the resistor R3, the anode of the diode D2 is connected to the tail end of the winding L3, and the cathode of the diode D2 is connected to the anode of the capacitor C1 and pin 1 of the resistor R3.

5. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 1, characterized in that: The output module includes a capacitor C5 and a capacitor C6 which are electrically connected, and the capacitor C5 and the capacitor C6 are both electrically connected to the bridge power circuit.

6. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 1, characterized in that: The overcurrent protection system includes a driving module, and the protection module includes a resistor R52, a capacitor C50, a resistor C55, a transistor Q50, a transistor Q52, a resistor R49 and a resistor R50. Pin 1 of the resistor R52 is connected to the protection signal output end, and pin 2 of the resistor R52 is respectively connected to the positive electrode of the capacitor C50, pin 1 of the resistor R55, the collector of the transistor Q50 and the base of the transistor Q52. The negative electrode of the capacitor C50, pin 2 of the resistor R55 and the emitter of the transistor Q52 are all connected to GND. Pin 1 of the resistor R49 is connected to the voltage signal +12V, and pin 2 of the resistor R49 is respectively connected to the driving module, pin 1 of the resistor R50 and the emitter of the transistor Q50, and pin 2 of the resistor R50 is respectively connected to the base of the transistor Q50 and the collector of the transistor Q52.

7. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 6, characterized in that: The driving module includes two driving sub-units, which include a driving chip, an isolation pulse transformer and a signal driving circuit connected to the input end of the driving chip. The enabling end of the driving chip is connected to the 2nd pin of the resistor R49.

8. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 7, characterized in that: The drive signal input circuit includes a first drive resistor, a second drive resistor, a drive capacitor and a third drive resistor. A higher-level control signal input terminal is formed between pin 1 of the first drive resistor and pin 1 of the second drive resistor. Pin 2 of the first drive resistor is respectively connected to the positive electrode of the drive capacitor, pin 1 of the third resistor and the input terminal of the drive chip. Pin 2 of the second drive resistor, the negative electrode of the drive capacitor and pin 2 of the third drive resistor are all connected to the ground terminal of the drive chip.

9. The magnetic saturation overcurrent protection system for a bridge power circuit for a power supply as claimed in claim 7, characterized in that: The isolation pulse transformer includes a primary winding and a secondary winding which are electrically connected, wherein the primary winding is connected to the output end of the driving chip, and the secondary winding is connected to the bridge power circuit.

10. A protection method, based on the magnetic saturation overcurrent protection system according to any one of claims 1 to 9, characterized in that: include: When the bridge power circuit is short-circuited, the current through winding L1 increases instantaneously, the current through winding L3 increases, and the currents of windings L4 and L5 increase accordingly, and the acquisition module outputs a protection signal; The protection module receives the protection signal and blocks the bridge power circuit according to the protection signal.

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