An auxiliary power supply protection circuit and auxiliary power supply

Abstract

The utility model relates to circuit protection technical field discloses a kind of auxiliary power supply protection circuit and auxiliary power supply, auxiliary power supply protection circuit includes bypass circuit and bypass control circuit, the first end of bypass circuit and the first end of the charging capacitor of auxiliary power supply are connected, the second end of bypass circuit is grounded, the input end of bypass control circuit and the error amplifier output end of the power supply chip of auxiliary power supply are connected, the output end of bypass control circuit and the control end of bypass circuit are connected, bypass control circuit is used to when the voltage of error amplifier output end rises, the first end of control bypass circuit and the second end of bypass circuit are communicated, the utility model can bypass charging capacitor when detecting circuit short circuit again, power supply end no longer continuously charges charging capacitor, and then make power supply chip no longer repeat emission wave, and then protect metal oxide semiconductor field effect transistor in auxiliary power supply, improve auxiliary power supply life.

Description

Technical Field

[0001] This utility model relates to the field of circuit protection technology, and in particular to an auxiliary power supply protection circuit and an auxiliary power supply. Background Technology

[0002] The auxiliary power supply connected to the inverter of a generator set is generally a flyback power supply, which outputs a stable 12V, 24V, or other voltage to provide a stable DC power supply to various loads on the machine, such as fans, protection circuits, control circuits, display modules, drive circuits, and communication circuits, to ensure that the equipment can operate normally. When the load suddenly fails or the external line is short-circuited, a large current will be drawn from the front-end power supply. At this time, the auxiliary power supply needs to protect itself first, and the machine can only be used after the fault is cleared. If protection is not provided in time, the primary side of the auxiliary power supply will be damaged due to excessive current, which may damage the metal-oxide-semiconductor field-effect transistor (MOSFET) in the auxiliary power supply.

[0003] The relevant technologies often work by detecting a load fault or short circuit. The auxiliary power supply stops transmitting signals, and the power supply chip detects a drop in the voltage of the charging capacitor and stops operating. However, because the generator set at the front end continues to output voltage, it continues to charge the charging capacitor. When the voltage of the charging capacitor rises to a certain level, the auxiliary power supply chip starts transmitting signals again, until it determines that the short circuit is ongoing, at which point it stops transmitting signals again. This process of transmitting and stopping signals repeats. In practical applications, after a machine malfunctions and short circuits, on-site personnel cannot immediately arrive for repairs. During this repeated transmitting and receiving process, the auxiliary power supply chip draws a large current due to the short circuit at the back end, which can easily damage the metal-oxide-semiconductor field-effect transistors in the auxiliary power supply, reducing its lifespan. Utility Model Content

[0004] In view of this, the present invention provides an auxiliary power supply protection circuit and an auxiliary power supply to solve or partially solve the technical problem in the related art that the metal oxide semiconductor field-effect transistor in the auxiliary power supply is easily damaged and the power supply life is reduced when the load is short-circuited.

[0005] The technical solution proposed by this utility model is as follows:

[0006] In the first aspect, this utility model proposes an auxiliary power supply protection circuit, including a bypass circuit and a bypass control circuit;

[0007] The first terminal of the bypass circuit is connected to the first terminal of the charging capacitor of the auxiliary power supply, and the second terminal of the bypass circuit is grounded.

[0008] The input terminal of the bypass control circuit is connected to the error amplifier output terminal of the power chip of the auxiliary power supply, and the output terminal of the bypass control circuit is connected to the control terminal of the bypass circuit. The bypass control circuit is used to control the connection between the first terminal and the second terminal of the bypass circuit when the voltage at the error amplifier output terminal increases.

[0009] In some alternative implementations, the bypass control circuit includes a first control circuit and a second control circuit;

[0010] The input terminal of the first control circuit is connected to the output terminal of the error amplifier, and the output terminal of the first control circuit is connected to the control terminal of the second control circuit. The first control circuit is used to output a low-level signal when the voltage at the output terminal of the error amplifier increases.

[0011] The input terminal of the second control circuit is connected to the first terminal of the charging capacitor, and the output terminal of the second control circuit is connected to the control terminal of the bypass circuit. The second control circuit is used to control the first terminal and the second terminal of the bypass circuit to connect when a low-level signal is received.

[0012] In some optional embodiments, the first control circuit includes a first resistor, a second resistor, a third resistor, and a controllable precision voltage regulator. The first end of the first resistor is connected to the error amplifier output terminal. The second end of the first resistor is connected to the first end of the second resistor and the reference electrode of the controllable precision voltage regulator. The anode of the controllable precision voltage regulator is connected to the first end of the third resistor and the control terminal of the second control circuit. The cathode of the controllable precision voltage regulator is connected to the second end of the second resistor and grounded. The second end of the third resistor is connected to the first end of the charging capacitor.

[0013] In some alternative implementations, the first control circuit further includes a first capacitor, and the first capacitor and the second resistor are connected in parallel.

[0014] In some alternative embodiments, the second control circuit includes a fourth resistor, a fifth resistor, and a first active switch. The first end of the fourth resistor is connected to the anode of the controllable precision voltage regulator, the second end of the fourth resistor is connected to the control terminal of the first active switch, the input terminal of the first active switch is connected to the first end of the fifth resistor, the second end of the fifth resistor is connected to the first end of the charging capacitor, and the output terminal of the first active switch is connected to the control terminal of the bypass circuit.

[0015] In some alternative implementations, the first active switch is a transistor, with the base of the transistor being the control terminal of the first active switch, the emitter of the transistor being the input terminal of the first active switch, and the collector of the transistor being the output terminal of the first active switch.

[0016] In some alternative implementations, the bypass circuit includes a sixth resistor and a second active switch. The control terminal of the second active switch is connected to the output terminal of the bypass control circuit and the first terminal of the sixth resistor, respectively. The input terminal of the second active switch is connected to the first terminal of the charging capacitor, and the output terminal of the second active switch is connected to the second terminal of the sixth resistor and grounded.

[0017] In some alternative embodiments, the second active switch is a silicon controlled rectifier (SCR), the controller of the SCR is the control terminal of the second active switch, the anode of the SCR is the input terminal of the second active switch, and the cathode of the SCR is the output terminal of the second active switch.

[0018] Secondly, this utility model proposes an auxiliary power supply, including an auxiliary power supply protection circuit as described in any of the first aspects of this utility model.

[0019] In some alternative implementations, the auxiliary power supply also includes a power chip, a charging capacitor, a transformer, a third active switch, and a feedback circuit. The transformer includes a first primary winding, a second primary winding, and several secondary windings.

[0020] The error amplifier output of the power chip is connected to the input of the bypass control circuit and the output of the feedback circuit, respectively. The power supply terminal of the power chip is connected to the first terminal of the charging capacitor, the first terminal of the first primary winding, and the auxiliary power input terminal, respectively. The second terminal of the charging capacitor is connected to the second terminal of the first primary winding and grounded. The output terminal of the power chip is connected to the control terminal of the third active switch. The first terminal of the second primary winding is grounded through the third active switch. The second terminal of the second primary winding is connected to the auxiliary power input terminal. The secondary winding is used to output the working voltage to the load.

[0021] The auxiliary power supply protection circuit and auxiliary power supply of this utility model have the following beneficial effects:

[0022] The auxiliary power supply protection circuit of this invention utilizes the characteristic that the voltage at the amplification output terminal of the auxiliary power supply chip increases when a load fault or a short circuit in a related line is detected. Based on this voltage change, the bypass control circuit controls the first and second terminals of the bypass circuit to connect when the voltage at the error amplification output terminal increases, bypassing the charging capacitor. The power supply terminal no longer continuously charges the charging capacitor, thereby preventing the power chip from repeatedly generating waves, thus protecting the metal-oxide-semiconductor field-effect transistor in the auxiliary power supply and improving the lifespan of the auxiliary power supply. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a circuit diagram of an auxiliary power supply in related technologies;

[0025] Figure 2 for Figure 1 Output waveform diagram of the power supply chip of the auxiliary power supply when it is working normally;

[0026] Figure 3 for Figure 1 Output waveform diagram of the power chip of the auxiliary power supply when a short circuit is detected;

[0027] Figure 4 This is a circuit diagram of the auxiliary power supply protection circuit in an embodiment of this utility model;

[0028] Figure 5 This is a circuit diagram of the auxiliary power supply in an embodiment of the present invention.

[0029] Figure 6 This is the output waveform diagram of the power chip of the auxiliary power supply in this embodiment of the present invention when a short circuit is detected.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Bypass control circuit; 2. Bypass circuit; U1, power supply chip; U2, optocoupler; U3, controllable precision voltage regulator; R15, first resistor; R16, second resistor; R17, third resistor; R18, fourth resistor; R19, fifth resistor; R20, sixth resistor; C2, charging capacitor; Q1, metal-oxide-semiconductor field-effect transistor; Q4, transistor; SCR, silicon controlled rectifier; COMP, error amplifier output terminal; VCC, power supply terminal. Detailed Implementation

[0032] 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.

[0033] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0036] Figure 1 This is a circuit diagram of an auxiliary power supply in related technologies. The auxiliary power supply generally includes a flyback topology and a power chip U1. The power chip U1 is a pulse width modulation (PWM) chip. When the auxiliary power supply is working normally, the waveform output by the power chip U1 is as follows: Figure 2 As shown. The hiccup mode of power chip U1 refers to the following: In the auxiliary power supply of the generator inverter, after an output short circuit, power chip U1 will stop emitting waveforms until the voltage output of transformer T1 drops and power chip U1 stops working. However, at this time, there will be a continuous input voltage at the front end, which continues to charge the charging capacitor C2 through current-limiting resistors R1 and R2. The power supply terminal VCC of power chip U1 detects the capacitor voltage of charging capacitor C2. When the capacitor voltage reaches the operating voltage of power chip U1, power chip U1 starts emitting waveforms again until it determines that the short circuit is continuous, and then stops emitting waveforms. This process of emitting and stopping waveforms is repeated. At this time, the waveform output by power chip U1 is as follows. Figure 3 As shown.

[0037] In practical applications, if the machine is short-circuited, the on-site personnel cannot arrive at the site immediately for repair. In this case, the power chip U1 will repeatedly generate waves during the hiccuping process. Because the back end is in a short-circuited state, the current is very large during this repeated wave generation process, which can easily damage the third active switch of the auxiliary power supply, namely the metal oxide semiconductor field-effect transistor Q1.

[0038] In view of this, the present invention provides an auxiliary power supply protection circuit, such as... Figure 4 As shown, the auxiliary power supply protection circuit includes:

[0039] Bypass circuit 2 and bypass control circuit 1; the first terminal of bypass circuit 2 is connected to the first terminal of the charging capacitor C2 of the auxiliary power supply, and the second terminal of bypass circuit 2 is grounded; the input terminal of bypass control circuit 1 is connected to the error amplifier output terminal COMP of the power chip U1 of the auxiliary power supply, and the output terminal of bypass control circuit 1 is connected to the control terminal of bypass circuit 2. Bypass control circuit 1 is used to control the first terminal and the second terminal of bypass circuit 2 to connect when the voltage of the error amplifier output terminal COMP increases.

[0040] Specifically, the auxiliary power protection circuit is applied to the auxiliary power supply of the generator set inverter, such as a photovoltaic generator set, a thermal power generator set, or a wind power generator set.

[0041] The power chip U1 in the auxiliary power supply is a PWM chip. In the auxiliary power supply, the error amplifier output terminal COMP is connected to a feedback circuit. This feedback circuit detects whether there is a fault or short circuit in the downstream circuit. When a short circuit is present, the voltage at the error amplifier output terminal COMP increases. The power supply terminal VCC of the power chip U1 is connected to the first end of the charging capacitor C2.

[0042] The bypass control circuit 1 is mainly used to connect the first terminal and the second terminal of the bypass circuit 2 when the voltage of the error amplifier output terminal COMP is detected to rise.

[0043] Bypass circuit 2 is mainly used to bypass the charging capacitor C2. Specifically, when the first terminal of bypass circuit 2 and the second terminal of bypass circuit 2 are connected, the charging capacitor C2 is bypassed, and the voltage input to the power supply terminal VCC no longer charges the charging capacitor C2.

[0044] Therefore, in the event of a load fault or short circuit, through bypass control circuit 1 and bypass circuit 2, the power supply terminal VCC no longer continuously charges the charging capacitor C2, the voltage of the charging capacitor C2 no longer continuously increases, the capacitor voltage detected by the power supply terminal VCC of the power chip U1 will not reach the operating voltage of the power chip U1, the power chip U1 will not repeatedly start emitting waveforms, the auxiliary power supply is completely turned off, and the power chip U1 will not enter the repeated hiccup mode. At this time, the waveform output by the power chip U1 is as follows: Figure 6 As shown, the auxiliary power supply can be powered on again after the fault is cleared.

[0045] The auxiliary power supply protection circuit of this embodiment utilizes the characteristic that the voltage at the amplification output terminal of the auxiliary power supply chip U1 increases when a load fault or a short circuit in a related line is detected. Based on this voltage change, the bypass control circuit 1 controls the first and second terminals of the bypass circuit 2 to connect when the voltage at the error amplification output terminal COMP increases, bypassing the charging capacitor C2. The power supply terminal VCC no longer continuously charges the charging capacitor C2, thereby preventing the power supply chip U1 from repeatedly generating waves, thus protecting the metal-oxide-semiconductor field-effect transistor Q1 in the auxiliary power supply and improving the lifespan of the auxiliary power supply.

[0046] In some alternative implementations, the bypass control circuit 1 includes a first control circuit and a second control circuit;

[0047] The input terminal of the first control circuit is connected to the error amplifier output terminal COMP, and the output terminal of the first control circuit is connected to the control terminal of the second control circuit. The first control circuit is used to output a low-level signal when the voltage of the error amplifier output terminal COMP increases.

[0048] The input terminal of the second control circuit is connected to the first terminal of the charging capacitor C2, and the output terminal of the second control circuit is connected to the control terminal of the bypass circuit 2. The second control circuit is used to control the first terminal and the second terminal of the bypass circuit 2 to connect when a low-level signal is received.

[0049] The input terminal of the first control circuit is the input terminal of the bypass control circuit 1, and the output terminal of the second control circuit is the output terminal of the bypass control circuit 1.

[0050] The bypass control circuit 1 is split into a first control circuit and a second control circuit, which makes the circuit logic clearer, facilitates logic control, and provides a certain degree of electrical isolation.

[0051] In some embodiments, the first control circuit includes a first resistor R15, a second resistor R16, a third resistor R17, and a controllable precision voltage regulator U3. The first end of the first resistor R15 is connected to the error amplifier output terminal COMP. The second end of the first resistor R15 is connected to the first end of the second resistor R16 and the reference terminal (REF terminal) of the controllable precision voltage regulator U3. The anode (A terminal) of the controllable precision voltage regulator U3 is connected to the first end of the third resistor R17 and the control terminal of the second control circuit. The cathode (K terminal) of the controllable precision voltage regulator U3 is connected to the second end of the second resistor R16 and grounded. The second end of the third resistor R17 is connected to the first end of the charging capacitor C2.

[0052] Among them, the first end of the first resistor R15 is the input end of the first control circuit, and the anode of the controllable precision voltage regulator U3 is the output end of the first control circuit.

[0053] The controllable precision voltage regulator U3 is a three-terminal adjustable parallel voltage regulator. It integrates a precision reference voltage source, an error amplifier, and an output transistor, and is functionally equivalent to a programmable, low-temperature-coefficient Zener diode.

[0054] Specifically, when the auxiliary power supply is working normally, the level of the error amplifier output terminal COMP is around 2.5V. After the voltage is divided by the first resistor R15 and the second resistor R16, the voltage at the second end of the first resistor R15 is less than 2.5V. At this time, the controllable precision voltage regulator U3 does not operate, and the anode of the controllable precision voltage regulator U3 is maintained at a high potential. When the auxiliary power supply detects a short circuit, the level of the error amplifier output terminal COMP increases, and the voltage at the second end of the first resistor R15 is greater than or equal to 2.5V. The anode and cathode of the controllable precision voltage regulator U3 are connected, and the anode of the controllable precision voltage regulator U3 outputs a low-level signal.

[0055] Furthermore, the first control circuit also includes a first capacitor C7, which is connected in parallel with a second resistor R16. The first capacitor C7 can effectively filter out high-frequency noise or glitches on the COMP voltage at the error amplifier output terminal, preventing the protection circuit from malfunctioning and improving anti-interference capability and reliability.

[0056] In some embodiments, the second control circuit includes a fourth resistor R18, a fifth resistor R19, and a first active switch. The first end of the fourth resistor R18 is connected to the anode of the controllable precision voltage regulator U3, the second end of the fourth resistor R18 is connected to the control terminal of the first active switch, the input terminal of the first active switch is connected to the first end of the fifth resistor R19, the second end of the fifth resistor R19 is connected to the first end of the charging capacitor C2, and the output terminal of the first active switch is connected to the control terminal of the bypass circuit 2.

[0057] Among them, the first end of the fourth resistor R18 is the control terminal of the second control circuit, the second end of the fifth resistor R19 is the input terminal of the second control circuit, and the output terminal of the first active switch is the output terminal of the second control circuit.

[0058] Specifically, the first active switch is transistor Q4, the base of transistor Q4 is the control terminal of the first active switch, the emitter of transistor Q4 is the input terminal of the first active switch, and the collector of transistor Q4 is the output terminal of the first active switch.

[0059] By comparing the stable reference voltage of the controllable precision voltage regulator U3 with the voltage at the voltage divider point between the resistor and the second resistor R16, the error amplification output terminal COMP voltage threshold required to trigger the protection action can be set very precisely. When the voltage at the voltage divider point exceeds its internal reference voltage, the cathode and anode of the controllable precision voltage regulator U3 conduct, pulling down the anode voltage of the controllable precision voltage regulator U3, thereby driving the first active switch. The detected high voltage signal can be effectively converted into a low-level signal that controls the first active switch to conduct through a simple circuit.

[0060] Using transistor Q4 as the first active switch, with the base voltage provided by the fourth resistor R18, it can provide sufficient current drive capability to control the bypass circuit 2.

[0061] In some embodiments, the bypass circuit 2 includes a sixth resistor R20 and a second active switch. The control terminal of the second active switch is connected to the output terminal of the bypass control circuit 1 and the first terminal of the sixth resistor R20, respectively. The input terminal of the second active switch is connected to the first terminal of the charging capacitor C2, and the output terminal of the second active switch is connected to the second terminal of the sixth resistor R20 and grounded.

[0062] Specifically, the second active switch is a silicon controlled rectifier (SCR), the control electrode (G electrode) of the SCR is the control terminal of the second active switch, the anode of the SCR is the input terminal of the second active switch, and the cathode of the SCR is the output terminal of the second active switch.

[0063] Once triggered, a SCR (Silicon Controlled Rectifier) ​​automatically latches on and continues to discharge even after the control signal disappears, ensuring that the capacitor voltage quickly drops to a safe value. SCRs can withstand surge currents of tens of amperes without requiring a high-power MOSFET in parallel, offering advantages such as small size and low cost.

[0064] The auxiliary power supply protection circuit of this embodiment utilizes the characteristics of the power chip U1 for protection. When there is a short circuit at the rear end of the auxiliary power chip U1, the level of COMP at the error amplifier output terminal of the power chip U1 will continuously rise, and the power chip U1 will enter the short circuit protection mode. This rising level will be used to turn on the SCR driver. After the SCR operates, it will bypass the charging circuit of the charging capacitor C2. The voltage input to the front-end circuit can no longer continuously charge the charging circuit, and the auxiliary power supply will be completely turned off. The power chip U1 will not enter the repeated hiccup startup mode, and it can be powered on again after the fault is resolved.

[0065] This utility model also proposes an auxiliary power supply, including an auxiliary power supply protection circuit as described in any of the above embodiments of this utility model.

[0066] like Figure 5As shown, the auxiliary power supply also includes a power chip U1, a charging capacitor C2, a transformer, a third active switch, and a feedback circuit. The transformer T1 includes a first primary winding, a second primary winding, and several secondary windings.

[0067] The error amplifier output terminal COMP of the power chip U1 is connected to the input terminal of the bypass control circuit 1 and the output terminal of the feedback circuit, respectively. The power supply terminal VCC of the power chip U1 is connected to the first terminal of the charging capacitor C2, the first terminal of the first primary winding, and the auxiliary power input terminal, respectively. The second terminal of the charging capacitor C2 is connected to the second terminal of the first primary winding and grounded. The output terminal of the power chip U1 is connected to the control terminal of the third active switch. The first terminal of the second primary winding is grounded through the third active switch. The second terminal of the second primary winding is connected to the auxiliary power input terminal. The secondary winding is used to output the working voltage to the load.

[0068] Specifically, the third active switch is a metal-oxide-semiconductor field-effect transistor Q1.

[0069] The feedback circuit is used to detect whether a short circuit has occurred in the load. When a short circuit is detected, the optocoupler U2 is turned on, and the voltage at the error amplifier output terminal COMP of the power chip U1 rises.

[0070] A Zener diode, resistor R2, and resistor R1 are connected in series between the second terminal of the charging capacitor C2 and the auxiliary power input terminal. The anode of the Zener diode is grounded.

[0071] The first terminal of the charging capacitor C2 is connected to the first terminal of the first primary winding through the first diode D1. The anode of the first diode D1 is connected to the first terminal of the first primary winding, and the cathode of the first diode D1 is connected to both the first terminal of the charging capacitor C2 and the cathode of the Zener diode. The first diode D1 prevents reverse current flow.

[0072] The auxiliary power supply of this invention is applicable to the output side of the inverter of a generator set, including photovoltaic generator sets, thermal power generator sets, or wind power generator sets, etc.

[0073] The specific working process of the auxiliary power supply of this utility model is as follows:

[0074] When the auxiliary power supply is working normally, the level of the error amplifier output terminal COMP is around 2.5V. After voltage division by the first resistor R15 and the second resistor R16, the voltage at the second terminal of the first resistor R15 is less than 2.5V. At this time, the controllable precision voltage regulator U3 does not operate, and the anode of the controllable precision voltage regulator U3 remains at a high potential. The first active switch, i.e., transistor Q4, is not conducting, and the second active switch, i.e., the control electrode of the thyristor SCR, has no driving voltage, so the thyristor SCR does not work. When the auxiliary power supply detects a short circuit, the level of the error amplifier output terminal COMP increases, and the voltage at the second terminal of the first resistor R15 is greater than or equal to 2.5V. The anode and cathode of the controllable precision voltage regulator U3 conduct, and the anode of the controllable precision voltage regulator U3 outputs a low-level signal, causing the transistor to conduct. When transistor Q4 is turned on, the voltage across charging capacitor C2 is limited by resistor R19 and then supplied to the control electrode of the SCR via transistor Q4. Simultaneously, the SCR discharges charging capacitor C2, and the voltage input to the auxiliary power supply also flows through the SCR, limited by resistors R1 and R2. The SCR remains on, bypassing charging capacitor C2. The voltage on C2 cannot recover to power the power chip U1, thus stopping waveform generation. This prevents a large current surge after a short circuit at the auxiliary power supply's output, protecting the auxiliary power supply until the fault is resolved, the input is disconnected, and the system restarts. The voltage at the auxiliary power supply input is then applied to capacitor C1. After discharge, no current flows through the SCR, and it stops working. Upon restarting, the auxiliary power supply enters normal operating mode.

[0075] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions and modifications to these embodiments without departing from the spirit and scope of protection of this utility model, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. An auxiliary power supply protection circuit, characterized in that, Includes bypass circuits and bypass control circuits; The first terminal of the bypass circuit is connected to the first terminal of the charging capacitor of the auxiliary power supply, and the second terminal of the bypass circuit is grounded. The input terminal of the bypass control circuit is connected to the error amplification output terminal of the power chip of the auxiliary power supply, and the output terminal of the bypass control circuit is connected to the control terminal of the bypass circuit. The bypass control circuit is used to control the first terminal and the second terminal of the bypass circuit to connect when the voltage at the error amplification output terminal increases.

2. The auxiliary power supply protection circuit according to claim 1, characterized in that, The bypass control circuit includes a first control circuit and a second control circuit. The input terminal of the first control circuit is connected to the output terminal of the error amplifier, and the output terminal of the first control circuit is connected to the control terminal of the second control circuit. The first control circuit is used to output a low-level signal when the voltage at the output terminal of the error amplifier increases. The input terminal of the second control circuit is connected to the first terminal of the charging capacitor, and the output terminal of the second control circuit is connected to the control terminal of the bypass circuit. The second control circuit is used to control the first terminal and the second terminal of the bypass circuit to connect when a low-level signal is received.

3. The auxiliary power supply protection circuit according to claim 2, characterized in that, The first control circuit includes a first resistor, a second resistor, a third resistor, and a controllable precision voltage regulator. The first end of the first resistor is connected to the error amplifier output terminal. The second end of the first resistor is connected to the first end of the second resistor and the reference electrode of the controllable precision voltage regulator. The anode of the controllable precision voltage regulator is connected to the first end of the third resistor and the control terminal of the second control circuit. The cathode of the controllable precision voltage regulator is connected to the second end of the second resistor and grounded. The second end of the third resistor is connected to the first end of the charging capacitor.

4. The auxiliary power supply protection circuit according to claim 3, characterized in that, The first control circuit also includes a first capacitor, which is connected in parallel with the second resistor.

5. The auxiliary power supply protection circuit according to claim 3, characterized in that, The second control circuit includes a fourth resistor, a fifth resistor, and a first active switch. The first end of the fourth resistor is connected to the anode of the controllable precision voltage regulator, the second end of the fourth resistor is connected to the control terminal of the first active switch, the input terminal of the first active switch is connected to the first end of the fifth resistor, the second end of the fifth resistor is connected to the first end of the charging capacitor, and the output terminal of the first active switch is connected to the control terminal of the bypass circuit.

6. The auxiliary power supply protection circuit according to claim 5, characterized in that, The first active switch is a transistor, the base of the transistor is the control terminal of the first active switch, the emitter of the transistor is the input terminal of the first active switch, and the collector of the transistor is the output terminal of the first active switch.

7. The auxiliary power supply protection circuit according to claim 1, characterized in that, The bypass circuit includes a sixth resistor and a second active switch. The control terminal of the second active switch is connected to the output terminal of the bypass control circuit and the first terminal of the sixth resistor, respectively. The input terminal of the second active switch is connected to the first terminal of the charging capacitor, and the output terminal of the second active switch is connected to the second terminal of the sixth resistor and grounded.

8. The auxiliary power supply protection circuit according to claim 7, characterized in that, The second active switch is a silicon controlled rectifier (SCR), the controller of the SCR is the control terminal of the second active switch, the anode of the SCR is the input terminal of the second active switch, and the cathode of the SCR is the output terminal of the second active switch.

9. An auxiliary power supply, characterized in that, Includes the auxiliary power supply protection circuit as described in any one of claims 1 to 8.

10. The auxiliary power supply according to claim 9, characterized in that, It also includes a power chip, a charging capacitor, a transformer, a third active switch, and a feedback circuit. The transformer includes a first primary winding, a second primary winding, and several secondary windings. The error amplification output terminal of the power chip is connected to the input terminal of the bypass control circuit and the output terminal of the feedback circuit, respectively. The power supply terminal of the power chip is connected to the first terminal of the charging capacitor, the first terminal of the first primary winding, and the auxiliary power input terminal, respectively. The second terminal of the charging capacitor is connected to the second terminal of the first primary winding and grounded. The output terminal of the power chip is connected to the control terminal of the third active switch. The first terminal of the second primary winding is grounded through the third active switch. The second terminal of the second primary winding is connected to the auxiliary power input terminal. The secondary winding is used to output the working voltage to the load.

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