AC-DC circuit for power failure delay power supply redundancy protection

Abstract

The utility model discloses an AC-DC circuit for power failure delay power supply redundancy protection, and belongs to the field of circuit control. Aiming at the problems of single realization function and high cost of the existing AC-DC circuit, the utility model provides an AC-DC circuit for power failure delay power supply redundancy protection, which comprises a bridge rectifier module, a direct current conversion module, an overvoltage and undervoltage protection module and a power supply redundancy protection module which are connected in sequence, the input end of the bridge rectifier module is connected with an external alternating current power supply, and the output end of the power redundancy protection module is connected with a load; the energy storage capacitor and the bridge rectifier module are arranged in parallel, and a current-limiting resistor is arranged between the energy storage capacitor and the bridge rectifier module; and the bridge rectifier module, the energy storage capacitor and the current-limiting resistor form a power-down delay circuit. According to the utility model, the bridge rectifier module, the energy storage capacitor and the current-limiting resistor form a power-down time-delay circuit, so that the time-delay effect is more reliable and the circuit design is simplified; meanwhile, the overvoltage and undervoltage protection function and the power supply redundancy protection function are combined, so that the circuit has multiple functions, more importantly, the circuit achieves the multiple functions through few components, the implementation scheme is simple, the cost is low, and the effect is good.

Description

TECHNICAL FIELD

[0001] The utility model belongs to circuit control technical field, more specifically, relate to a kind of AC-DC circuit of power failure delay power redundancy protection. BACKGROUND

[0002] In the redundancy control system, the system includes two sets of configuration identical CPU modules, power modules and IO control modules. The two power modules configured completely the same, when the main power module fails, the system automatically switches to the standby power module, to ensure that the control system continues to run stably and reliably. The redundancy of power supply can provide protection for long-term stable operation of power supply in control system and high-reliability automation control. The existing power redundancy protection scheme uses a detection module to detect the state information of the voltage input end and outputs the state information to a monitoring module. The monitoring module controls the connection or disconnection of the power module according to the input state information, thereby realizing the power redundancy function. The existing power redundancy protection scheme has a complex implementation process, high implementation difficulty and high cost. At the same time, in many engineering applications in the measurement and control fields, in addition to the need for power redundancy, the system also needs to save some important data in time after AC power failure, so as to restore these important data after the next power-on and ensure the reliable operation of the system. Therefore, it is necessary for the power module to continue to provide power to the system for a period of time after AC power failure to ensure the reliable operation of the system.

[0003] Corresponding improvements have also been made for the above problems, such as Chinese patent application number CN202322513967.7, published on May 14, 2024, which discloses an AC power switching circuit, comprising: AC-DC circuit, switching circuit, delay circuit, trigger source circuit, DC-DC circuit, charging circuit, power input end, USB interface; the AC-DC circuit corresponding end is respectively connected with switching circuit, DC-DC circuit corresponding end electrically; the switching circuit corresponding end is connected with DC-DC circuit corresponding end electrically through trigger source circuit and delay circuit; the DC-DC circuit is connected with power input end through charging circuit. The disadvantages of this patent are: too many components, high cost.

[0004] For example, Chinese patent application number CN202211185257.X, published on December 9, 2022, discloses an ACDC circuit and a power supply device. The circuit includes a rectifier module, an overvoltage protection module, and a DC conversion module; the overvoltage protection module includes an overvoltage protection device and a charge-discharge unit connected in series; the rectifier module has an input end for connecting an external power supply, a first output end connected to a first end of the overvoltage protection module and a first input end of the DC conversion module, and a second output end connected to a second end of the overvoltage protection module and a second input end of the DC conversion module; the output end of the DC conversion module is used to connect a load; when the difference between the output voltage of the rectifier module and the voltage of the charge-discharge unit is greater than the operating voltage of the overvoltage protection device, the overvoltage protection device is turned on; when the difference is not greater than the operating voltage of the overvoltage protection device, the overvoltage protection device is turned off. The shortcomings of this patent are: although it can improve the applicability of the circuit, the overall reliability is poor. Utility model content

[0005] 1. Problem to be solved

[0006] In view of the problem that the existing AC-DC circuit has single function and high cost, the utility model provides an AC-DC circuit with power failure delay and power redundancy protection. The utility model forms a power failure delay circuit through a bridge rectifier module, an energy storage capacitor and a current limiting resistor, which is more reliable and simplifies the circuit design; at the same time, it combines overvoltage and undervoltage protection and power redundancy protection functions, so that the circuit has multiple functions, and more importantly, the circuit realizes the above-mentioned multiple functions through fewer components, the implementation scheme is simple, the cost is low and the effect is good.

[0007] 2. Technical scheme

[0008] To solve the above problems, the utility model adopts the following technical scheme.

[0009] An AC-DC circuit with power failure delay and power redundancy protection, comprising a bridge rectifier module, a DC conversion module, an overvoltage and undervoltage protection module and a power redundancy protection module connected in sequence, the input end of the bridge rectifier module is connected with an external power supply, and the output end of the power redundancy protection module is connected with a load; further comprising an energy storage capacitor, the energy storage capacitor is arranged in parallel with the bridge rectifier module, and a current limiting resistor is arranged between the energy storage capacitor and the bridge rectifier module; the bridge rectifier module, the energy storage capacitor and the current limiting resistor form a power failure delay circuit.

[0010] The technical scheme is adopted, the energy storage capacitor is connected in parallel on the bridge rectifier module, and the current limiting resistor is arranged between the two; the energy storage capacitor functions as energy storage when the power supply is normal, and the capacitor starts to discharge to provide power supply for the entire circuit when the power supply is powered off; the energy storage capacitor and the current limiting resistor are directly arranged after the bridge rectifier module, which can reduce the complexity of the subsequent circuit, avoid adding an additional delay circuit after the direct current output, simplify the overall circuit design, reduce the manufacturing cost, and improve the reliability and maintainability of the circuit; meanwhile, the bridge rectifier module can realize full-wave rectification, and compared with half-wave rectification, the efficiency is higher, the capacitor is directly connected in parallel after rectification to store energy, the rectified energy can be more efficiently utilized, and the energy loss in the subsequent circuit is reduced; and the charging and discharging process of the energy storage capacitor is directly affected by the output voltage of the rectifier circuit, so the delay effect is more reliable; the delay control is directly performed after rectification, which can reduce the interference of the subsequent circuit on the delay effect and ensure the stability of the delay effect.

[0011] The AC-DC circuit of the entire power failure delay power supply redundancy protection also combines overvoltage and undervoltage protection and power supply redundancy protection functions, so that the circuit has multiple functions, and more importantly, the circuit realizes the multiple functions by using fewer components, has a simple implementation scheme, low cost, and good effect.

[0012] Furthermore, the control module is connected with the direct current conversion module through the output feedback module, and the control module is used for adjusting the duty cycle according to the result of the output feedback module to realize stable voltage output.

[0013] The technical scheme is adopted, when the external alternating power supply is powered off, the power failure delay circuit composed of the energy storage capacitor, the current limiting resistor and the bridge rectifier module works, the energy storage capacitor starts to supply power, and considering that the voltage of the energy storage capacitor gradually decreases with the increase of the power supply time, the rated output voltage can still be realized by adjusting the duty cycle of the control module, and when the voltage of the energy storage capacitor decreases to the range that can be adjusted by the control module, the output voltage starts to decrease; the setting of the control module effectively ensures that the power failure delay circuit can still maintain high stability when the external alternating power supply is powered off.

[0014] Furthermore, the EMC filter module is arranged between the external power supply and the bridge rectifier module, and the voltage filter module is arranged between the bridge rectifier module and the direct current conversion module.

[0015] The technical scheme is adopted, high-frequency noise and electromagnetic radiation in the external power supply line are attenuated through the EMC filtering module, electromagnetic interference generated by the electronic device is effectively reduced, meanwhile, damage of the high-frequency noise and the electromagnetic radiation to the power supply module and internal components of the electronic device is reduced, the service life of the device is prolonged, the pulsed direct-current voltage output by the bridge rectifier module is filtered through the voltage filtering module, alternating current components are reduced, direct-current components are maintained, the output voltage waveform is smoother, the input voltage quality of the direct-current conversion module is improved, and the stability and reliability of the entire circuit are improved, and the filtering capacitor in the voltage filtering module can have the same effect as the energy storage capacitor, that is, the filtering capacitor stores electricity when the power supply is normally working, and the filtering capacitor and the energy storage capacitor supply power when the power supply is not working, thereby ensuring the efficiency of the entire power supply and increasing the holding time of the power failure delay circuit.

[0016] Further, a switch element is arranged between the overvoltage and undervoltage protection module and the power supply redundancy protection module, and the overvoltage and undervoltage protection module is configured to compare the real-time direct-current voltage with a set voltage threshold, so as to control the opening or closing of the switch element.

[0017] The technical scheme is adopted, the overvoltage and undervoltage protection module can monitor the direct-current voltage in real time and quickly respond to the operation through the switch element, so that the abnormality can be found in time to avoid a large impact, and the overvoltage and undervoltage protection module and the power supply redundancy protection module form a double protection mechanism, so that the system can continue to operate stably even if the main power supply fails or the voltage is abnormal, the voltage abnormality can be quickly responded to without manual intervention, and only the work efficiency is improved, but the risk of human operation error is reduced.

[0018] Further, the overvoltage and undervoltage protection module comprises a reference voltage generation circuit and a comparator, the reference voltage generation circuit comprises a voltage stabilizing tube, a current limiting resistor and a voltage dividing resistor, the current limiting resistor is connected in series with the voltage stabilizing tube, the output of the voltage stabilizing tube is connected with the input of the voltage dividing resistor, the output of the voltage dividing resistor is connected with the non-inverting terminal of the comparator, the inverting terminal of the comparator is connected with the output terminal of the direct-current conversion module, and the output terminal of the comparator is connected with the power supply redundancy protection module through the switch element.

[0019] Further, the comparator is a push-pull output comparator TP2012, and a hysteresis resistor is connected between the non-inverting terminal and the output terminal of the push-pull output comparator TP2012.

[0020] The technical scheme is adopted, the push-pull output comparator TP2012 has ultra-low power consumption and fast response time, and the efficiency of the entire judgment is improved, and the hysteresis resistor is arranged to make the comparator have a hysteresis function, so that the overvoltage and undervoltage protection module is prevented from malfunctioning due to voltage jitter when the input voltage of the comparator is near the reference voltage.

[0021] Further, the power supply redundancy protection module comprises a power supply redundancy circuit, a filter circuit connected with the power supply redundancy circuit; the power supply redundancy circuit comprises a control chip, the control chip is used for monitoring the working state of the power supply module; at least two power supply modules: used for power supply; filter elements: used for filtering noise and interference in the power supply; switching elements: used for being disconnected or conducting under the action of the control chip to realize power-off or wire.

[0022] Further, the control chip is an ideal diode control chip. The ideal diode control chip has the advantages of low power loss, high system reliability, enhanced functionality and flexibility, saved cost and space. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a whole structure schematic view of the utility model;

[0024] Figure 2 It is an AC power-off delay schematic view;

[0025] Figure 3 It is a connection circuit schematic view of the overvoltage and undervoltage protection module and the power supply redundancy protection module. DETAILED DESCRIPTION

[0026] The utility model is further described below in combination with specific embodiments and drawings.

[0027] As Figure 1 and Figure 2 shown, an AC-DC circuit of power-off delay power supply redundancy protection comprises a bridge rectifier module, a DC conversion module, an overvoltage and undervoltage protection module and a power supply redundancy protection module connected in sequence, the input end of the bridge rectifier module is connected with an external AC power supply, the output end of the bridge rectifier module is connected with the input end of the DC conversion module, the output end of the DC conversion module is connected with the input end of the overvoltage and undervoltage protection module, the output end of the overvoltage and undervoltage protection module is connected with the input end of the power supply redundancy protection module, and the output end of the power supply redundancy protection module is connected with a load; further comprising a control module, the control module is connected with the DC conversion module through an output feedback module, and the control module is used for adjusting the duty cycle according to the result of the output feedback module to realize stable voltage output. That is, the electric trend of the circuit is that the external AC power supply AC220V is changed into a direct current voltage (the direct current voltage has a certain ripple voltage) after passing through the bridge rectifier module, then the direct current voltage 5VDC is outputted by the DC conversion module to become the required direct current voltage 5VDC, and the direct current voltage 5VDC is used for power supply for the load after passing through the overvoltage and undervoltage protection module and the power supply redundancy protection module.

[0028] It is worth noting that: the bridge rectifier module in this embodiment includes a bridge rectifier circuit for converting alternating current (AC) to direct current (DC); the DC conversion module includes a DC-DC circuit for converting the input DC voltage to another required DC voltage in the circuit; the overvoltage and undervoltage protection module includes an overvoltage and undervoltage protection circuit for protecting the circuit and the device from abnormal voltage; the power supply redundancy protection module includes a power supply redundancy protection circuit, which configures multiple power supplies and backs up each other, so that when one of them fails, the others can immediately take over the work, thereby ensuring the continuous operation of the system; the control module includes a control circuit for receiving signals from the output feedback module, adjusting the duty cycle (i.e. the ratio of on and off time of the switch tube) in the DC conversion module according to the signals, and thus achieving stable voltage output; the output feedback module includes an output feedback circuit for feeding back the output voltage of the DC conversion module to the control module in real time, so that the control module can adjust the duty cycle according to the deviation between the current output voltage and the set value, thereby achieving closed-loop control. The bridge rectifier circuit, DC-DC circuit, overvoltage and undervoltage protection circuit, power supply redundancy protection circuit, control circuit and output feedback circuit can all use conventional existing circuits.

[0029] The AC-DC circuit of the power-down delay power supply redundancy protection of the present application also includes an energy storage capacitor, which is connected in parallel with the bridge rectifier module, and a current limiting resistor is arranged between the energy storage capacitor and the bridge rectifier module; the bridge rectifier module, the energy storage capacitor and the current limiting resistor form a power-down delay circuit; it is worth noting that the power-down delay circuit in the present application includes a charging phase and a discharging phase, the charging phase is that the bridge rectifier module charges the energy storage capacitor through the current limiting resistor, and the discharging phase is that the energy storage capacitor discharges the stored energy.

[0030] When the external AC power supply is normally powered, the bridge rectifier module in the power-down delay circuit rectifies the AC power into DC power, and the DC power is sequentially supplied to the load after passing through the DC conversion module, the overvoltage and undervoltage protection module and the power supply redundancy protection module; at the same time, the energy storage capacitor is charged after limiting the current size by the current limiting resistor;

[0031] When the external AC power supply is powered off, the energy storage capacitor in the power-down delay circuit discharges, and a discharge loop is formed through the current limiting resistor, and the DC power discharged by the energy storage capacitor is sequentially supplied to the load after passing through the DC conversion module, the overvoltage and undervoltage protection module and the power supply redundancy protection module, thereby realizing power-down delay; and the holding time of the power-down delay is greater than the load response time, which includes the load reaction time and the load action time.

[0032] The application creatively connects the energy storage capacitor and the current limiting resistor with the bridge rectifier module respectively, and the bridge rectifier module, the energy storage capacitor and the current limiting resistor form a power failure delay circuit; the position of the power failure delay circuit is designed before the DC conversion module and after the bridge rectifier module, which avoids adding an additional delay circuit after the DC output, thereby simplifying the overall circuit design; and the bridge rectifier module can realize full-wave rectification, compared with half-wave rectification, it more effectively utilizes each half cycle of alternating current, improves the rectification efficiency, that is, under the same power supply conditions, the bridge rectifier module can provide faster charging speed and more stable charging voltage for the energy storage capacitor, thereby possibly prolonging the power failure delay time or improving the stability of the delay; at the same time, the charging and discharging process of the energy storage capacitor is directly affected by the output voltage of the rectifier circuit, making the delay effect more reliable; if the power failure delay circuit is designed after the DC conversion module, the delay effect may be affected by changes in other elements or loads in the DC circuit. Therefore, the application designs the power failure delay circuit before the DC conversion module, which has obvious advantages such as simplified structure, improved efficiency, direct delay control, reduced cost, improved reliability and enhanced adaptability. More importantly, only the bridge rectifier module, the energy storage capacitor and the current limiting resistor can form a power failure delay circuit, which can realize this function using fewer components, the implementation scheme is simple and the cost is low, and the delay time of the circuit can be flexibly controlled by adjusting the capacity of the energy storage capacitor and the resistance value of the current limiting resistor, the design flexibility enables the circuit to adapt to the needs of different application scenarios, such as fast response systems requiring shorter delay time or systems requiring longer delay time and higher stability, which increases the flexibility of the entire design and has a wide range of applications.

[0033] And the application makes the holding time of the power-off delay time greater than the load response time, including load reaction time and load action time, by reasonable parameter setting of the energy storage capacitor and the current limiting resistor. The load reaction time refers to the time required from the start of system power-off to the load device (such as sensors, actuators, etc.) sensing the change and making a preliminary response. The load action time refers to the time required for the load device to perform necessary operations or state transitions after making a preliminary response, to ensure that the system or device can safely and orderly transition to a stable state after power-off or perform emergency measures. This design takes into account the importance of systems that require high reliability and safety, such as industrial automation control systems, medical devices, data centers, etc. In these systems, even a short power interruption requires ensuring that critical loads can continue to operate for a period of time to complete necessary operations or protect data from loss, and the time for critical loads to continue to operate must be less than the holding time of the power-off delay circuit to ensure that critical loads have enough time to complete the required operations. The current limiting resistor in the circuit is used to reduce the inrush current when the external AC power supply 220V is powered on due to the increase in the inrush current caused by the energy storage capacitor.

[0034] At the same time, it is also considered that when the external AC power supply is powered off, the power-off delay circuit composed of the bridge rectifier module, the energy storage capacitor and the current limiting resistor works, and since the energy storage capacitor starts to supply power, it is considered that the voltage of the energy storage capacitor gradually decreases as the power supply time increases. At this time, the control module can still achieve the rated output voltage by adjusting the duty cycle until the energy storage capacitor voltage drops outside the range that the control module can adjust, and the output voltage starts to drop. The setting of the control module effectively ensures that when the external AC power supply is powered off, the power-off delay circuit still maintains high stability.

[0035] In summary, the AC-DC circuit of the power-off delay power supply redundancy protection of the application forms a power-off delay circuit through the bridge rectifier module, the energy storage capacitor and the current limiting resistor, which is more reliable and simplifies the circuit design. At the same time, it combines overvoltage and undervoltage protection and power supply redundancy protection functions, so that the circuit has multiple functions, and more importantly, the circuit realizes the above-mentioned multiple functions with fewer components, the implementation scheme is simple, the cost is low and the effect is good.

[0036] In one embodiment, the holding time of the power-off delay circuit is obtained according to the following formula:

[0037] 0.5*C1*(Vin_nor 2 -Vin_min 2 )=⊿t*Po / η

[0038] Wherein: C1 is the rated capacity of the energy storage capacitor; Vin_nor is the DC voltage value of the external AC power after rectification by the bridge rectifier module; Vin_min is the minimum voltage value for normal operation of the DC conversion module; Δt is the hold time; Po is the output power of the AC-DC circuit; η is the output efficiency of the AC-DC circuit; it is explained that the voltage output Vo of the entire AC-DC circuit is 5V, the output power Po of the entire AC-DC circuit is 30W, and the output efficiency of the entire AC-DC circuit is η = 82%.

[0039] In an embodiment, an EMC filtering module is further arranged between the external power supply and the bridge rectifier module, and a voltage filtering module is further arranged between the bridge rectifier module and the DC conversion module.

[0040] Specifically, in this embodiment, the input end of the EMC filtering module is connected with the external AC power supply, and the output end of the EMC filtering module is connected with the input end of the bridge rectifier module. The EMC filtering module attenuates the high-frequency noise and electromagnetic radiation in the power supply line, effectively reduces the electromagnetic interference generated by the electronic device, prevents the electromagnetic interference from being transmitted to the power grid or other electronic devices through the power supply line, and avoids interfering with or affecting the normal operation of other devices. Thus, the damage of high-frequency noise and electromagnetic radiation to the power supply module and internal components of the electronic device is reduced, and the service life of the device is prolonged.

[0041] The input end of the voltage filtering module is connected with the output end of the bridge rectifier module, and the output end of the voltage filtering module is connected with the input end of the DC conversion module. The voltage filtering module filters the pulsating DC voltage output by the bridge rectifier module through filter capacitors and other components, reduces the AC component, maintains the DC component, and makes the output voltage waveform smoother. This helps to improve the input voltage quality of the DC conversion module, and thus improves the stability and reliability of the entire circuit. Moreover, the filter capacitor in the voltage filtering module can play the same role as the energy storage capacitor, i.e., when the external power supply is normally powered, the filter capacitor stores energy; when the external power supply is powered off, the filter capacitor and the energy storage capacitor jointly supply power to the entire circuit. In this embodiment, the following examples are given:

[0042] When the external AC 220V power is off, the energy stored in the energy storage capacitor C1 and the filter capacitor Cin is used to supply power to the output. In this process, the voltage of the energy storage capacitor C1 and the filter capacitor Cin gradually decreases, and the control module can still achieve the rated output voltage by adjusting the duty cycle. Until the capacitor voltage drops to the range that the control module can adjust, the output voltage starts to drop. According to the law of conservation of energy, the AC-DC power module power retention time ⊿t is proportional to the input capacitor, AC input voltage, power module efficiency, and inversely proportional to the output power and the minimum working voltage of the DC-DC part. The AC input voltage of the AC-DC power module is fixed, the minimum working voltage of the DC-DC part generally cannot be changed, and the efficiency of the power module is also difficult to improve, so the best way is to increase the input capacitor to prolong the power retention time of the AC-DC power module. The voltage output Vo of the AC-DC power module is 5V, the output power Po is 30W, the efficiency is η=82%, the minimum voltage Vin_min that the DC-DC part can normally work is 100V, the internal input filter capacitor Cin of the power supply is 47uF, and the energy storage capacitor C1 is 180uF. The voltage after AC 220V input rectification and filtering is a direct current voltage (actually with a certain ripple), and its value Vin_nor is 308V. According to the law of conservation of energy, the following formula is obtained:

[0043] 0.5*(Cin+C1)*(Vin_nor 2 -Vin_min 2 )=⊿t*Po / η

[0044] Substituting the numerical value can obtain: ⊿t=263.3ms. This power retention time ⊿t far satisfies the field application requirement, the power retention time ⊿t prolongs effectually, and is suitable for many application occasions.

[0045] In one embodiment, a switch element is arranged between the overvoltage and undervoltage protection module and the power supply redundancy protection module, and the overvoltage and undervoltage protection module is used to judge the real-time direct current voltage and the set voltage threshold, so as to control the opening or disconnection of the switch element.

[0046] The embodiment can timely discover the abnormality to avoid being greatly affected by monitoring the direct current voltage in real time through the overvoltage and undervoltage protection module and quickly responding to the operation through the switch piece; meanwhile, the overvoltage and undervoltage protection module and the power supply redundancy protection module form a double protection mechanism, so that even if the main power supply fails or the voltage is abnormal, the power supply can be timely cut off and the redundant power supply can be enabled to ensure the continuous and stable operation of the system; and the voltage abnormality can be quickly responded to without manual intervention, so that the working efficiency is improved and the risk of human operation failure is reduced. The switch piece is a PMOS tube, the overvoltage and undervoltage protection module compares the size relationship between the real-time direct current voltage 5VDC and the set voltage threshold, and outputs a high level or a low level to control the on-off of the PMOS tube. The PMOS tube has the advantages of low voltage difference, high stability, prevention of reverse current, improvement of circuit efficiency, simple manufacturing process, high input impedance, strong anti-radiation capability and wide application.

[0047] As shown in Figure 3 In one embodiment, the overvoltage and undervoltage protection module includes a reference voltage generation circuit and a comparator, the reference voltage generation circuit includes a voltage stabilizing tube, a current limiting resistor and a voltage dividing resistor, the current limiting resistor is connected in series with the voltage stabilizing tube, the output of the voltage stabilizing tube is connected with the input of the voltage dividing resistor, the output of the voltage dividing resistor is connected with the non-inverting terminal of the comparator, the inverting terminal of the comparator is connected with the output terminal of the direct current conversion module, and the output terminal of the comparator is connected with the power supply redundancy protection module through the switch piece.

[0048] Specifically, the overvoltage and undervoltage protection module includes an overvoltage and undervoltage protection circuit, which mainly includes U2, D1, D2, D3 and related resistors and capacitors. D1 is a 3V voltage stabilizing tube, R2 connected in series with the voltage stabilizing tube plays a current limiting role to protect the voltage stabilizing tube. The output 3V of the voltage stabilizing tube is divided by R3, R7 and R15 to obtain reference voltages VT1 (the voltage at pin 2 of U2A) and VT2 (the voltage at pin 5 of U2B), and U2 is a comparator.

[0049] The overvoltage protection circuit mainly includes U2A, R10, D2, R9, R13, R14, R3, R7 and R15 to form a hysteresis non-inverting comparator circuit, the reference voltage VT1 is 3V*(R7+R15) / (R3+R7+R15), the hysteresis voltage is 3V*R13 / R10, according to the characteristics of the comparator, VT1=VP*R10 / (R10+R13), and VP=Vin*R14 / (R9+R14), wherein Vin is the monitored input voltage. According to the above, the overvoltage threshold OVLO is calculated as 3V*(R7+R15)*(R9+R14)*(R10+R13) / ((R3+R7+R15)*R14*R10)±3V*R13 / R10.

[0050] The under-voltage protection circuit mainly consists of U2B, R16, D3, R9, R13, R14, R3, R7, R15, and has a hysteretic inverting comparator circuit, a reference voltage VT2=3V*R15 / (R3+R7+R15), and a hysteretic voltage ⊿V2=3V*((R3+R7)||R15) / ((R3+R7)||R15+R16). According to the comparator characteristics, VT2=VQ≈VP, and VP=Vin*R14 / (R9+R14), wherein Vin is the monitored input voltage. The under-voltage threshold UVLO=3V*R15*(R9+R14) / ((R3+R7+R15)*R14)±3V*((R3+R7)||R15) / ((R3+R7)||R15+R16) can be calculated according to the above.

[0051] When Vin is greater than the under-voltage threshold UVLO and less than the over-voltage threshold OVLO, i.e. Vin belongs to the normal working range, U2A outputs a low level, U2B outputs a low level, and after passing through diodes D2 and D3, a low level is input to the base of NPN transistor Q4, Q4 is cut off, Q3 is turned on, the G terminal of PMOS transistor Q1 is low, Q1 is turned on, and Vin continues to output voltage to the subsequent circuit, thereby normally supplying power to the load.

[0052] When Vin is greater than the over-voltage threshold OVLO, U2A outputs a high level, U2B outputs a low level, and after passing through diodes D2 and D3, a high level is input to the base of NPN transistor Q4, Q4 is turned on, Q3 is cut off, the G terminal and the S terminal of PMOS transistor Q1 are high, Q1 is cut off, i.e. Vin no longer outputs voltage, thereby playing an over-voltage protection role on the load.

[0053] When Vin is less than the under-voltage threshold UVLO, U2A outputs a low level, U2B outputs a high level, and after passing through diodes D2 and D3, a high level is input to the base of NPN transistor Q4, Q4 is turned on, Q3 is cut off, the G terminal and the S terminal of PMOS transistor Q1 are high, Q1 is cut off, i.e. Vin no longer outputs voltage, thereby playing an under-voltage protection role on the load.

[0054] The power supply redundancy protection module comprises a power supply redundancy circuit, a filter circuit connected with the power supply redundancy circuit, a control chip in the power supply redundancy circuit, the control chip being used for monitoring the working state of the power supply module, at least two power supply modules being used for power supply, filter elements being used for filtering noise and interference in the power supply, and switch elements being used for being disconnected or conducted under the action of the control chip to realize power-off or conduction.

[0055] Specifically, the power redundancy protection module includes a power redundancy protection circuit mainly composed of U3, Q2, R6, C6 and C7. C5, C4 and TVS1 form a filter circuit for filtering and suppressing transient voltage of VDD_5V, U3 is a control chip, which cooperates with the external NMOS tube Q2 to realize low-loss reverse protection circuit function by using extremely low forward voltage drop (20mV), U3 normally works when the EN of U3 is at high level, Q2 is turned on, and the power supply normally outputs power to the load. When the EN of U3 is at low level, U3 is closed, Q2 is cut off, and the power supply no longer supplies power. In the power redundancy protection circuit, generally two power supplies with the same configuration work at the same time, one of which is a main power supply and the other is a backup power supply. When the Vin of the main power supply is greater than OVLO or less than UVLO, Q1 is cut off, the EN of U3 is at low level, U3 is closed, and the abnormal power supply no longer supplies power, thereby protecting the load. At this time, the backup power supply replaces the main power supply module to continue to supply power to the load.

[0056] Preferably, the comparator in the overvoltage and undervoltage protection module is a push-pull output comparator TP2012, which has a fast response time, thereby improving the overall judgment efficiency, and a hysteresis resistor is connected between the non-inverting terminal and the output terminal of the push-pull output comparator TP2012. The setting of the hysteresis resistor enables the comparator to have a hysteresis function, preventing the comparator from malfunctioning due to voltage jitter when the input voltage is near the reference voltage, thereby affecting the normal power supply of the subsequent load and improving the stability of the entire circuit. The control chip in the power redundancy protection module is an ideal diode control chip, which is LM74700-Q1. The control chip (<0.75us) can quickly respond to reverse current blocking to avoid the risk of reverse current, and when the main power supply is replaced while being electrified, that is, during hot plug, the VDD_5V output by the main power supply will be distorted, which will cause a risk of reverse current to the backup power supply, thereby ensuring the normal work of the backup power supply and the continuous and stable power supply of the replaced main power supply to the load.

[0057] The examples described in the utility model are only used to describe the preferred embodiments of the utility model, and do not limit the utility model concept and scope, and various deformations and improvements of the technical scheme of the utility model made by the engineering and technical personnel in the field without departing from the design idea of the utility model shall fall within the protection scope of the utility model.

Claims

1. An AC-DC power supply redundancy protection with brown-out delay, characterized by: The application relates to a power supply device, which comprises a bridge rectifier module, a DC conversion module, an overvoltage and undervoltage protection module and a power supply redundancy protection module connected in sequence, the input end of the bridge rectifier module is connected with an external power supply, the output end of the power supply redundancy protection module is connected with a load; the power supply device further comprises an energy storage capacitor, the energy storage capacitor is arranged in parallel with the bridge rectifier module, and a current-limiting resistor is arranged between the energy storage capacitor and the bridge rectifier module; the bridge rectifier module, the energy storage capacitor and the current-limiting resistor form a power-off delay circuit.

2. An AC-DC power supply redundancy protection with power down delay circuit according to claim 1, wherein: The power supply device further comprises a control module, the control module is connected with the DC conversion module through an output feedback module, the control module is used for adjusting the duty cycle according to the result of the output feedback module, so as to realize stable voltage output.

3. An AC-DC power supply redundancy protection with brown-out delay circuit according to claim 1 or 2, characterized in that: An EMC filter module is further arranged between the external power supply and the bridge rectifier module, and a voltage filter module is further arranged between the bridge rectifier module and the DC conversion module.

4. An AC-DC power supply redundancy protection with power down delay circuit according to claim 1, wherein: A switch element is arranged between the overvoltage and undervoltage protection module and the power supply redundancy protection module, the overvoltage and undervoltage protection module is used for judging the real-time DC voltage and a set voltage threshold, so as to control the opening or closing of the switch element.

5. An AC-DC power supply redundancy protection with brown-out delay circuit according to claim 4, wherein: The overvoltage and undervoltage protection module comprises a reference voltage generating circuit and a comparator, the reference voltage generating circuit comprises a voltage stabilizing tube, a current-limiting resistor and a voltage dividing resistor, the current-limiting resistor and the voltage stabilizing tube are connected in series, the output end of the voltage stabilizing tube is connected with the input end of the voltage dividing resistor, the output end of the voltage dividing resistor is connected with the non-inverting end of the comparator, the inverting end of the comparator is connected with the output end of the DC conversion module, and the output end of the comparator is connected with the power supply redundancy protection module through the switch element.

6. An AC-DC power supply redundancy protection with brown-out delay circuit according to claim 5, wherein: The comparator is a push-pull output comparator TP2012, and a hysteresis resistor is connected between the non-inverting end and the output end of the push-pull output comparator TP2012.

7. An AC-DC power supply redundancy protection with power down delay circuit according to claim 1, wherein: The power supply redundancy protection module comprises a power supply redundancy circuit and a filter circuit connected with the power supply redundancy circuit; the power supply redundancy circuit comprises a control chip, the control chip is used for monitoring the working state of a power supply module; at least two power supply modules are used for power supply; A filter element is used for filtering noise and interference in the power supply; A switch element is used for being disconnected or conducted under the action of the control chip, so as to realize power-off or conduction.

8. An AC-DC power supply redundancy protection with brown-out delay circuit according to claim 7, wherein: The control chip is an ideal diode control chip.

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