Switching power supply pole locking prevention circuit

Abstract

The utility model discloses a kind of prevent pole lock dead circuit, belong to switching power supply technical field, specifically related to a kind of switching power supply prevent pole lock dead circuit, including pole input interface, bridge rectifier network, filter capacitor, power supply network, sampling network, comparator and shutdown network. Real-time detection pole voltage by sampling network, when voltage is lower than set threshold value, triggers shutdown network to force to close switching power supply chip, realizes automatic restart. The present application solves the problem of pole power supply under low voltage lock, improves system reliability and operation efficiency, applicable to FTU and other scenarios in distribution network industry.

Description

Technical Field

[0001] This utility model discloses an anti-terminal lock-up circuit, belonging to the field of switching power supply technology, specifically relating to an anti-terminal lock-up circuit for switching power supplies, used to solve the problem of terminal power supply locking up under low voltage. Background Technology

[0002] In the power distribution network industry, FTUs typically use pole-mounted power supply (capacitive power supply). However, the output power of the poles is limited (usually a few watts to tens of watts). When the instantaneous power demand of the load (such as hundreds of watts from the operating mechanism of a switching power supply) exceeds the output capacity of the pole, the pole voltage will collapse and lock in a low-voltage state, making the system unrecoverable. Existing technologies require power-off restarts to solve this problem, but power outages on the primary side of the power grid are costly and complex. Therefore, there is an urgent need for a solution that can automatically restore pole-mounted power supply without power interruption. Utility Model Content

[0003] Purpose of this utility model: To provide a circuit for preventing terminal block lock-up in a switching power supply, thereby solving the aforementioned problems.

[0004] Technical solution: A switching power supply anti-terminal lock-up circuit, the anti-terminal lock-up circuit comprising: a power input module and a PWM module; the power input module is connected to the PWM module;

[0005] The PWM module includes: a switching power supply chip U1;

[0006] The power input module includes:

[0007] The pole input interface includes: LI and N1, for receiving AC voltage supplied by the pole;

[0008] A bridge rectifier network, including diodes D2, D4, D5, and D6, is connected to the terminal input interface for converting AC voltage to DC voltage.

[0009] The filter capacitor C2 is connected to the output terminal of the bridge rectifier network and is used to filter the rectified DC voltage.

[0010] The power supply network includes: diode D3, resistor R1, Zener diode ZD1, transistor Q1 and capacitor C5, which are used to convert the filtered DC voltage into a low-voltage power supply.

[0011] The sampling network includes resistor R9, capacitor C9, and resistor R11, which are connected to the output terminal of the filter capacitor and are used to detect the voltage across the filter capacitor.

[0012] Comparator A1 has its input terminals connected to the output terminal of the sampling network and the reference voltage, respectively, and is used to compare the sampled voltage with the reference voltage.

[0013] The shutdown network, including resistor R13 and MOSFET Q3, is controlled by the output signal of the comparator. When the sampled voltage is lower than the reference voltage, the shutdown network is turned on to short-circuit the power supply network, forcibly shutting off the power supply to the switching power supply chip U1, thereby achieving power restart.

[0014] In a further embodiment, the rated input voltage on the grid power supply side is 5774Vac, which is converted by a transformer to output 27Vac AC voltage.

[0015] In a further embodiment, the reference voltage is set by a resistor divider network to characterize the conventional voltage threshold for the operation of the pole, the resistor divider network including resistors R5 and R7.

[0016] In a further embodiment, the shutdown network short-circuits the power supply pin of the switching power supply chip U1 to ground by turning on the MOSFET Q3.

[0017] In a further embodiment, the switching power supply chip U1 is a flyback PWM controller.

[0018] In a further embodiment, the PWM module further includes:

[0019] The power supply network, including resistor R3, resistor R6, diode D8, capacitor C8 and transformer T1Y, is used to convert DC voltage to low voltage power supply.

[0020] The working unit, including resistors R8, R17, R10, MOSFET Q2, R15, R14, R16, and transformer T1B, is the smallest unit for the switching power supply chip U1 to operate.

[0021] This invention utilizes a sampling network to monitor the voltage of the filter capacitor in real time. When the voltage falls below a reference value, a comparator triggers the shutdown network to short-circuit the power supply to the switching power chip, forcibly shutting down the power supply and restarting it, thus breaking the low-voltage lock-up state of the terminals. This invention has the following beneficial effects:

[0022] 1. Prevents terminal block lock-up due to low voltage, improving system reliability;

[0023] 2. No manual power outage or restart is required, reducing maintenance costs;

[0024] 3. It features fast response speed thanks to automatic hardware control. Attached Figure Description

[0025] Figure 1 This is the circuit diagram of the power input module of this utility model.

[0026] Figure 2This is the circuit diagram of the PWM module of this utility model. Detailed Implementation

[0027] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0028] In the power distribution network industry, FTUs need to achieve deep integration of primary and secondary power supplies. They are usually powered by capacitor banks, also known as pole power supplies. The characteristics of poles determine that, as the input source of a switching power supply, the output energy is non-linear and the output power is insufficient. In actual use, if the backup power is insufficient and the mechanism is forcibly operated or a large load is forcibly applied, exceeding the maximum output power of the pole, the pole voltage will collapse. The lower the pole voltage, the lower the output power. Ultimately, it will be limited to a low voltage by the standby power consumption of the power supply. Even after the operation or load is removed, the pole will not recover, causing the pole to be permanently locked in this state. This patent solves this problem very well.

[0029] A switching power supply anti-terminal lock-up circuit includes: a power input module and a PWM module; the power input module is connected to the PWM module.

[0030] Example 1:

[0031] like Figure 1 As shown, the power input module includes:

[0032] The pole input interface includes: LI and N1, for receiving AC voltage supplied by the pole;

[0033] A bridge rectifier network, including diodes D2, D4, D5, and D6, is connected to the terminal input interface for converting AC voltage to DC voltage.

[0034] The filter capacitor C2 is connected to the output terminal of the bridge rectifier network and is used to filter the rectified DC voltage.

[0035] The power supply network includes: diode D3, resistor R1, Zener diode ZD1, transistor Q1 and capacitor C5, which are used to convert the filtered DC voltage into a low-voltage power supply.

[0036] The sampling network includes resistor R9, capacitor C9, and resistor R11, which are connected to the output terminal of the filter capacitor and are used to detect the voltage across the filter capacitor.

[0037] Comparator A1 has its input terminals connected to the output terminal of the sampling network and the reference voltage, respectively, and is used to compare the sampled voltage with the reference voltage.

[0038] The shutdown network, including resistor R13 and MOSFET Q3, is controlled by the output signal of the comparator. When the sampled voltage is lower than the reference voltage, the shutdown network is turned on to short-circuit the power supply network, forcibly shutting off the power supply to the switching power supply chip U1, thereby achieving power restart.

[0039] In one embodiment, the rated input voltage on the grid power supply side is 5774Vac, which is converted by a transformer to output 27Vac AC voltage.

[0040] In one embodiment, the reference voltage is set by a resistor divider network to characterize the conventional voltage threshold for the operation of the pole, the resistor divider network including resistors R5 and R7.

[0041] In one embodiment, the shutdown network short-circuits the power supply pin of the switching power supply chip U1 to ground by turning on the MOSFET Q3.

[0042] Specifically, such as Figure 1 As shown, the anode of diode D2 and the cathode of diode D4 are connected to the live wire interface L1; the anode of diode D6 and the cathode of diode D5 are connected to the neutral wire interface N1; the anodes of diode D4 and D5 are connected to the reference voltage G1; the anode of diode D3 outputs voltage VINDC-1+ to the PWM module and is simultaneously connected to the cathodes of diode D2 and D6, pin 1 of filter capacitor C2, and pin 2 of resistor R9; pin 3 of transistor Q1 is simultaneously connected to the cathode of diode D3 and pin 2 of resistor R1; pin 1 of transistor Q1 is simultaneously connected to pin 1 of resistor R1 and the cathode of Zener diode ZD1; pin 2 of transistor Q1 is connected to pin 1 of capacitor C5 and input voltage VCC; the anode of Zener diode ZD1 is simultaneously connected to pin 2 of filter capacitor C2 and pin 5 of capacitor C9. Pin 2 of the circuit is connected to the reference voltage G1. Pin 4 of the inverting input of comparator A1 is simultaneously connected to pin 2 of resistor R11, pin 1 of resistor R9, and pin 2 of capacitor C9. Pin 1 of capacitor C9 and pin 1 of resistor R11 are connected to the reference voltage G1. Pin 5 of comparator A1 receives the input voltage VCC. Pin 3 of comparator A1 is simultaneously connected to pin 1 of resistor R7 and pin 2 of resistor R5. Pin 1 of resistor R5 receives the input voltage VCC. Pin 2 of resistor R7 receives the input voltage G1. Pin 2 of comparator A1 receives the input voltage G1. Pin 1 of comparator A1 is connected to pin 2 of resistor R13. The gate (G) of MOSFET Q3 is connected to pin 1 of resistor R13, the drain (D) is connected to pin 6 of switching power supply chip U1, and the source (S) receives the reference voltage G1.

[0043] More specifically, in combination Figure 1 The input voltage (LIN1) is converted to 27Vac AC by a transformer, and then used to generate DC voltage through a bridge rectifier network (D2, D4, D5, D6) and a filter capacitor (C2). The power supply network (D3, R1, ZD1, Q1, C5) provides low-voltage power to the switching power supply chip (U1). The sampling network (R9, C9, R11) detects the voltage across the filter capacitor and compares it with a reference voltage (R5, R7). When the voltage is below a threshold, the comparator (A1) outputs a high level, driving the shutdown network (Q3) to conduct, short-circuiting the power supply pin of U1, and forcibly restarting the power supply.

[0044] Example 2:

[0045] like Figure 2 As shown, the PWM module includes: a switching power supply chip U1; the switching power supply chip U1 is a flyback PWM controller;

[0046] The power supply network, including resistor R3, resistor R6, diode D8, capacitor C8 and transformer T1Y, is used to convert DC voltage to low voltage power supply.

[0047] The working unit, including resistors R8, R17, R10, MOSFET Q2, R15, R14, R16, and transformer T1B, is the smallest unit for the switching power supply chip U1 to operate.

[0048] In one embodiment, such as Figure 2As shown, pin 1 of the switching power supply chip U1 receives the reference voltage G1. Pin 2 of the switching power supply chip U1 is connected to pin 2 of resistor R10. Pin 3 of the switching power supply chip U1 is connected to pin 2 of resistor R14. Pin 4 of the switching power supply chip U1 is connected to pin 2 of resistor R17 and pin 1 of resistor R8. Pin 5 of the switching power supply chip U1 is connected to pin 1 of resistor R17, pin 2 of capacitor C8, pin 4 of transformer T1Y, and pin 1 of resistor R16, and is also connected to the reference voltage G1. Pin 6 of the switching power supply chip U1 is connected to pin 1 of resistor R6, pin 1 of capacitor C8, and diode... The negative terminal of diode D8 is connected to the drain terminal of MOSFET Q3. Pin 2 of resistor R8 is connected to pin 5 of transformer T1Y and the positive terminal of diode D8. Pin 2 of resistor R6 is connected to pin 1 of resistor R3. Pin 2 of resistor R3 is connected to pin 1 of transformer T1B to input voltage VINDC-1+. Pin 1 of resistor R15 is connected to pin 1 of resistor R10 and pin 1 of MOSFET Q2. Pin 2 of resistor R15 is connected to pin 1 of resistor R14, pin 3 of MOSFET Q2, and pin 2 of resistor R16. Pin 3 of MOSFET Q2 is connected to pin 3 of transformer T1B.

[0049] Working principle: The power output of the terminal block is usually only a few watts to ten watts, while the instantaneous power of the switching power supply operating mechanism usually requires several hundred watts. During normal operation, part of the energy of the terminal block is used to work the FTU controller, and the remaining energy is used to charge the backup power supply to make up for the lack of input energy during the operation. According to the characteristics of the terminal block, it can output a few watts to more than ten watts under rated input conditions. However, under certain specific conditions, such as the terminal block voltage collapse or extremely low input voltage after the operation, the output power of the terminal block is only about 1 watt, but it can support the power required for the standby of the switching power supply. The switching power supply will not shut down due to insufficient input energy, and the voltage of the terminal block will not collapse further. Eventually, it will remain in this state, causing the FTU and the terminal block to be unable to work normally. At this time, a power outage and restart are required to break this balance and reactivate the FTU and the terminal block. However, the cost of power outage and restart on the primary side of the power grid is very high and the process is very cumbersome, which cannot support frequent power outage operations.

[0050] This utility model patent uses the KP212LGA manufactured by Biyi Microelectronics as an example to design a flyback power supply for a PWM chip. L1N1 is the input terminal; diodes D2, D4, D5, and D6 form a bridge rectifier network; filter capacitor C2, diode D3, resistor R1, Zener diode ZD1, transistor Q1, and capacitor C5 form the power supply network; resistor R9, capacitor C9, and resistor R11 form the sampling network; resistors R5 and R7 form the reference; comparator A1, resistor R13, and MOSFET Q3 form the shutdown network; resistors R3 and R6, diode D8, capacitor C8, and transformer T1Y form the power supply network; and resistors R8, R17, R10, MOSFET Q2, resistors R15, R14, R16, and transformer T1B form the switching power supply chip U1 or a flyback converter. The smallest unit of the flyback power supply operates by dividing the voltage between the high and low voltage capacitors on the primary side and converting it to a low-voltage AC power of approximately 27Vac through a transformer. This AC power is then converted to DC voltage by the rectifier and filter network shown in the diagram to power the flyback power supply. The power supply network further reduces the converted DC voltage to power the comparator. The sampling network samples the input voltage and compares it with a reference voltage. When the sampling network detects that the voltage on the filter capacitor is lower than the normal operating voltage of the flyback power supply, it controls the shutdown network through the comparator to shut down the power supply. The shutdown network short-circuits the power supply network of the switching power supply chip U1 to ground by turning on the MOSFET Q3, thus shutting down the switching power supply and achieving the purpose of power restart, preventing the flyback power supply from locking in a low-power state.

[0051] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A switching power supply anti-terminal lock-up circuit, characterized in that, The anti-terminal lock-up circuit includes: a power input module and a PWM module; the power input module is connected to the PWM module. The PWM module includes: a switching power supply chip U1; The power input module includes: The pole input interface includes: LI and N1, for receiving AC voltage supplied by the pole; A bridge rectifier network, including diodes D2, D4, D5, and D6, is connected to the terminal input interface for converting AC voltage to DC voltage. The filter capacitor C2 is connected to the output terminal of the bridge rectifier network and is used to filter the rectified DC voltage. The power supply network includes: diode D3, resistor R1, Zener diode ZD1, transistor Q1 and capacitor C5, which are used to convert the filtered DC voltage into a low-voltage power supply. The sampling network includes resistor R9, capacitor C9, and resistor R11, which are connected to the output terminal of the filter capacitor and are used to detect the voltage across the filter capacitor. Comparator A1 has its input terminals connected to the output terminal of the sampling network and the reference voltage, respectively, and is used to compare the sampled voltage with the reference voltage. The shutdown network, including resistor R13 and MOSFET Q3, is controlled by the output signal of the comparator. When the sampled voltage is lower than the reference voltage, the shutdown network is turned on to short-circuit the power supply network, forcibly shutting off the power supply to the switching power supply chip U1, thereby achieving power restart.

2. The switching power supply anti-terminal lock-up circuit according to claim 1, characterized in that, The rated input voltage on the grid power supply side is 5774Vac, and after being converted by the transformer, the output voltage is 27Vac AC.

3. The switching power supply anti-terminal lock-up circuit according to claim 1, characterized in that, The reference voltage is set through a resistor divider network and is used to characterize the normal voltage threshold for the operation of the electrode. The resistor divider network includes resistors R5 and R7.

4. The switching power supply anti-terminal lock-up circuit according to claim 1, characterized in that, The shutdown network short-circuits the power supply pin of the switching power supply chip U1 to ground by turning on the MOSFET Q3.

5. The switching power supply anti-terminal lock-up circuit according to claim 1, characterized in that, The switching power supply chip U1 is a flyback PWM controller.

6. The switching power supply anti-terminal lock-up circuit according to claim 1, characterized in that, The PWM module also includes: The power supply network, including resistor R3, resistor R6, diode D8, capacitor C8 and transformer T1Y, is used to convert DC voltage to low voltage power supply. The working unit, including resistors R8, R17, R10, MOSFET Q2, R15, R14, R16, and transformer T1B, is the smallest unit for the switching power supply chip U1 to operate.

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