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

Abstract

The invention discloses an AC-DC circuit for power failure delay power supply redundancy protection, and belongs to the field of circuit control. In order to solve the problems that an existing AC-DC circuit is single in function and high in cost, the AC-DC circuit with the power failure delay power supply redundancy protection function 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 sequentially connected, the input end of the bridge rectifier module is connected with an external alternating current power supply, and the output end of the bridge rectifier module is connected with the direct current conversion module. The output end of the power supply 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; the bridge rectifier module, the energy storage capacitor and the current-limiting resistor form a power-down delay circuit; the system further comprises a control module, the control module is connected with the direct current conversion module through an output feedback module, and the control module is used for adjusting the duty ratio according to the result of the output feedback module to achieve stable voltage output. According to the invention, 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 invention belongs to the technical field of circuit control, and more specifically, relates to an AC-DC circuit with power failure delay power supply redundancy protection. Background Art

[0002] In a redundant control system, the system includes two sets of CPU modules, power modules and their IO control modules with exactly the same configuration. When the main power module fails, the system automatically switches to the backup power module to ensure that the control system continues to operate stably and reliably. The redundancy of the power supply can provide a guarantee for the long-term stable operation of the power supply in the control system and high-reliability automatic control. The existing power redundancy protection scheme uses the detection module to detect the status information of the voltage input terminal and output the status information to the monitoring module. The monitoring module controls the connection or disconnection of the power module according to the input status information to achieve 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 such as measurement and control, in addition to the need for power redundancy, the system also needs to save some important data in time after the AC power is off, so that these important data can be restored after the next power-on to ensure that the system continues to operate reliably. Therefore, after the AC power is off, it is necessary for the power module to continue to provide power to the system for a period of time to ensure the reliable operation of the system.

[0003] Corresponding improvements have also been made to the above problems, such as China's patent application number CN202322513967.7, published on May 14, 2024. The patent discloses a circuit for AC alternating current power switching, including: AC-DC circuit, switch circuit, delay circuit, trigger source circuit, DC-DC circuit, charging circuit, power input terminal, USB interface; the corresponding ends of the AC-DC circuit are electrically connected to the corresponding ends of the switch circuit and DC-DC circuit respectively; the corresponding ends of the switch circuit are electrically connected to the corresponding ends of the DC-DC circuit after the trigger source circuit and the delay circuit; the DC-DC circuit is connected to the power input terminal after the charging circuit. The shortcomings of this patent are: there are many components and the cost is high.

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

[0005] 1. Problems to be solved

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

[0007] 2. Technical solution

[0008] To solve the above problems, the present invention adopts the following technical solutions.

[0009] An AC-DC circuit with 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, wherein the input end of the bridge rectifier module is connected to an external AC power supply, and the output end of the power supply redundancy protection module is connected to a load; further comprising an energy storage capacitor, wherein 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;

[0010] When the external AC power supply is normally supplied, the bridge rectifier module in the power-off delay circuit rectifies the DC power, and the DC power is then supplied to the load through the DC conversion module, the overvoltage and undervoltage protection module, and the power redundancy protection module in sequence; at the same time, the energy storage capacitor is charged after the current is limited by the current limiting resistor;

[0011] When the external AC power supply is powered off, the energy storage capacitor in the power-off delay circuit is discharged, and the DC power discharged by the energy storage capacitor passes through the DC conversion module, the overvoltage and undervoltage protection module and the power redundancy protection module in sequence to supply power to the load, thereby realizing power-off delay; and the holding time of the power-off delay is greater than the load response time, and the load response time includes the load reaction time and the load action time;

[0012] It also includes a control module, which is connected to the DC conversion module through an output feedback module. The control module is used to adjust the duty cycle according to the result of the output feedback module to achieve stable voltage output.

[0013] The above technical scheme is adopted, by connecting an energy storage capacitor in parallel to the bridge rectifier module, and setting a current limiting resistor between the two; the energy storage capacitor acts as energy storage when the power is normally supplied, and when the power is cut off, the capacitor starts to discharge to provide power for the entire circuit; the energy storage capacitor and the current limiting resistor are directly set after the bridge rectifier module, which can reduce the complexity of the subsequent circuit, avoid adding an additional delay circuit after the DC output, simplify the overall circuit design, not only reduce the manufacturing cost, but also improve the reliability and maintainability of the circuit; at the same time, the bridge rectifier module can realize full-wave rectification, which is more efficient than half-wave rectification. After rectification, the capacitor is directly connected in parallel to store energy, which can more efficiently utilize the rectified electric energy and reduce the energy loss in the subsequent circuit; 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; directly performing delay control after rectification can reduce the interference of the subsequent circuit on the delay effect and ensure the stability of the delay effect;

[0014] The entire AC-DC circuit of power-off delay power redundancy protection also combines overvoltage and undervoltage protection and power redundancy protection functions, so that the circuit has multiple functions. More importantly, the circuit realizes the above multiple functions with fewer components, and the implementation plan is simple, low-cost and effective.

[0015] Furthermore, the holding time of the power-off delay circuit is obtained according to the following formula:

[0016] 0.5*C1*(Vin_nor 2 -Vin_min 2 )=⊿t*Po / η

[0017] Wherein: C1 is the rated capacity of the energy storage capacitor; Vin_nor is the DC voltage value after the external AC power supply is rectified by the bridge rectifier module; Vin_min is the minimum voltage value for the normal operation of the DC conversion module; ⊿t is the holding time; Po is the output power of the AC-DC circuit; η is the output efficiency of the AC-DC circuit.

[0018] By adopting the above technical solution, the holding time of the power-off delay circuit is increased by increasing the rated capacity of the energy storage capacitor, so that 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; this design flexibility enables the circuit to adapt to the needs of different application scenarios, such as a fast response system that requires a shorter delay time or a system that requires a longer delay time and has higher stability requirements, further improving the applicability of the present application;

[0019] Furthermore, an EMC filter module is provided between the external power supply and the bridge rectifier module, and a voltage filter module is provided between the bridge rectifier module and the DC conversion module.

[0020] By adopting the above technical solution, the high-frequency noise and electromagnetic radiation in the external power supply line are attenuated through the EMC filter module, thereby effectively reducing the electromagnetic interference generated by the electronic equipment; at the same time, the damage of the high-frequency noise and electromagnetic radiation to the power module and the internal components of the electronic equipment is reduced, thereby extending the service life of the equipment; the pulsating DC voltage output by the bridge rectifier module is filtered through the voltage filter module to reduce the AC component and maintain the DC component, so that the output voltage waveform is smoother, which helps to improve the input voltage quality of the DC conversion module, thereby improving the stability and reliability of the entire circuit; and the filter capacitor in the voltage filter module can play the same role as the energy storage capacitor, that is, it stores electricity when the power supply is working normally, and supplies power together with the energy storage capacitor when the power supply is not working, thereby ensuring the efficiency of the entire power supply and increasing the holding time of the power-off delay circuit.

[0021] Furthermore, a switch element is provided 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 DC voltage with a set voltage threshold, thereby controlling the opening or disconnection of the switch element.

[0022] By adopting the above technical solution, the DC voltage is monitored in real time through the overvoltage and undervoltage protection module and the switch component responds quickly to the operation, so that anomalies can be discovered in time to avoid major impacts; at the same time, the overvoltage and undervoltage protection module and the power supply redundancy protection module form a dual protection mechanism. Even if the main power supply fails or the voltage is abnormal, the power supply can be cut off in time and the redundant power supply can be enabled to ensure continuous and stable operation of the system; and the voltage abnormality can be responded to quickly without human intervention, which not only improves work efficiency but also reduces the risk of human operational errors.

[0023] Furthermore, the overvoltage and undervoltage protection module includes a reference voltage generating circuit and a comparator. The reference voltage generating circuit includes a voltage regulator, a current limiting resistor and a voltage dividing resistor. The current limiting resistor is connected in series with the voltage regulator, and the output of the voltage regulator is connected to the input of the voltage dividing resistor. The output of the voltage dividing resistor is connected to the in-phase end of the comparator, the inverting end of the comparator is connected to the output end of the DC conversion module, and the output end of the comparator is connected to the power redundancy protection module through a switch.

[0024] Furthermore, the comparator is a push-pull output comparator TP2012, and a hysteresis resistor is connected between the in-phase terminal and the output terminal of the push-pull output comparator TP2012.

[0025] By adopting the above technical solution, the push-pull output comparator TP2012 has ultra-low power consumption and fast response time, thereby improving the overall judgment efficiency; and the setting of the hysteresis resistor enables the comparator to have a hysteresis function, thereby preventing the overvoltage or undervoltage protection from malfunctioning due to voltage jitter when the comparator input voltage is near the reference voltage.

[0026] Furthermore, the power redundancy protection module includes a power redundancy circuit and a filtering circuit connected to the power redundancy circuit; the power redundancy circuit includes a control chip, and the control chip is used to monitor the working status of the power module; at least two power modules: used for power supply; filtering elements: used to filter out noise and interference in the power supply; switching elements: used to disconnect or conduct under the action of the control chip to achieve power off or conduction.

[0027] Furthermore, 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, and saved cost and space. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is a schematic diagram of AC power-off delay;

[0030] Figure 3 It is a schematic diagram of the connection circuit between the overvoltage and undervoltage protection module and the power supply redundancy protection module. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific embodiments and drawings.

[0032] like Figure 1 and Figure 2As shown, an AC-DC circuit with power-off delay power supply redundant protection includes a bridge rectifier module, a DC conversion module, an overvoltage and undervoltage protection module and a power supply redundant protection module connected in sequence, the input end of the bridge rectifier module is connected to an external AC power supply, the output end of the bridge rectifier module is connected to the input end of the DC conversion module, the output end of the DC conversion module is connected to the input end of the overvoltage and undervoltage protection module, the output end of the overvoltage and undervoltage protection module is connected to the input end of the power supply redundant protection module, and the output end of the power supply redundant protection module is connected to a load; and also includes a control module, the control module is connected to the DC conversion module through an output feedback module, the control module is used to adjust the duty cycle according to the result of the output feedback module to achieve stable voltage output. That is, the electrical flow of the circuit is as follows: the external AC power supply AC220V is converted into a DC voltage after passing through the bridge rectifier module (the DC voltage has a certain ripple voltage, that is, it can be the ripple voltage of the positive half cycle), and then passes through the energy storage capacitor and then through the DC conversion module output rectifier to become the required DC voltage 5VDC. The DC voltage 5VDC passes through the overvoltage and undervoltage protection module and the power redundancy protection module to supply power to the load, where the control circuit of the 5VDC output adjusts the duty cycle (PWM mode) according to the output feedback circuit to achieve stable voltage output.

[0033] It should be noted that: the bridge rectifier module in this embodiment includes a bridge rectifier circuit for converting alternating current (AC) into direct current (DC); the DC conversion module includes a DC-DC circuit for converting an input DC voltage into another DC voltage required in the circuit; the overvoltage and undervoltage protection module includes an overvoltage and undervoltage protection circuit for protecting the circuit and the equipment from damage caused by abnormal voltage; the power supply redundancy protection module includes a power supply redundancy protection circuit, which is configured with multiple power supplies and backs up each other. When one of the power supplies fails, the other power supplies can immediately take over the work, thereby ensuring the continuous operation of the system; the control module includes a control circuit for receiving a signal from the output feedback module and adjusting the duty cycle (i.e., the time ratio of the switch tube to be turned on and off) in the DC conversion module according to the signal, thereby achieving a 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, and 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, the DC-DC circuit, the overvoltage and undervoltage protection circuit, the power supply redundancy protection circuit, the control circuit and the output feedback circuit can all adopt conventional existing circuits.

[0034] The AC-DC circuit of power-off delay power supply redundant protection of the present application also includes an energy storage capacitor, which 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; it is worth noting that the power-off delay circuit in the present application includes a charging stage and a discharging stage. In the charging stage, the bridge rectifier module charges the energy storage capacitor after limiting the current size through the limiting resistor, and in the discharging stage, the energy stored in the energy storage capacitor continues to work and discharges.

[0035] When the external AC power supply is normally supplied, the bridge rectifier module in the power-off delay circuit rectifies the DC power, and the DC power is then supplied to the load through the DC conversion module, the overvoltage and undervoltage protection module, and the power redundancy protection module in sequence; at the same time, the energy storage capacitor is charged after the current is limited by the current limiting resistor;

[0036] When the external AC power supply is cut off, the energy storage capacitor in the power-off delay circuit is discharged, and the DC power discharged by the energy storage capacitor passes through the DC conversion module, the overvoltage and undervoltage protection module and the power redundancy protection module in sequence to supply power to the load, thereby realizing power-off delay; and the holding time of the power-off delay is greater than the load response time, and the load response time includes the load reaction time and the load action time.

[0037] The present application creatively connects the energy storage capacitor and the current limiting resistor to the bridge rectifier module respectively, and the bridge rectifier module, the energy storage capacitor and the current limiting resistor form a power-off delay circuit; the position of the power-off delay circuit is designed to be before the DC conversion module and after the bridge rectifier module, avoiding the addition of 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 the alternating current and improves the rectification efficiency, that is, under the same power supply conditions, the bridge rectifier module can provide the energy storage capacitor with a faster charging speed and a more stable charging voltage, thereby possibly extending the power-off 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 its delay effect more reliable; if the power-off delay circuit is designed after the DC conversion module, the delay effect may be affected by other components or load changes in the DC circuit. Therefore, the present application designs the power-off 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, a power-off delay circuit can be formed by only using a bridge rectifier module, an energy storage capacitor and a current limiting resistor. This function can be realized using fewer components, the implementation scheme is simple and low-cost, 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. This design flexibility enables the circuit to adapt to the needs of different application scenarios, such as a fast response system that requires a shorter delay time or a system with higher stability requirements that requires a longer delay time, which increases the flexibility of the entire design and has a wide range of applications.

[0038] And the present application sets reasonable parameters for the energy storage capacitor and the current limiting resistor so that the holding time of the power-off delay is greater than the load response time. The load response time includes the load reaction time and the load action time. The load reaction time refers to the time from the system power failure to the load device (such as a sensor, an actuator, etc.) sensing the change and making a preliminary response. The load action time refers to the time required for the load device (such as a sensor, an actuator, etc.) to sense the change and make a preliminary response after the initial response. The load action time refers to the time required after the load device makes a preliminary response to perform the necessary operations or switch states to ensure that the system or device can safely and orderly transition to a stable state after power failure or perform emergency measures. This design is particularly important for systems that require high reliability and safety, such as industrial automation control systems, medical equipment, data centers, etc. In these systems, even if there is a short power interruption, it is necessary to ensure that the critical load can continue to run for a period of time to complete the necessary operations or protect data from loss, and the time for the critical load to continue to run must be less than the holding time of the power-off delay circuit to ensure that the critical load has enough time to complete the required operation. The role of the current limiting resistor in the circuit is that due to the addition of the energy storage capacitor, the impact current will increase when the external AC power supply 220V is just powered on, and the current limiting resistor is used to reduce the impact current. It should be noted that the resistance value of the current limiting resistor is selected to ensure that during the capacitor discharge process, the current will not be too large to damage the load or circuit.

[0039] At the same time, it is also taken into consideration that when the external AC power supply is cut off, the power-off delay circuit composed of the bridge rectifier module, the energy storage capacitor and the current limiting resistor starts to work. Since the energy storage capacitor starts to supply power, and considering that the voltage of the energy storage capacitor gradually decreases with the gradual increase of the power supply time, the rated output voltage can still be achieved by adjusting the duty cycle through the control module. Until the voltage of the energy storage capacitor drops beyond the range that the control module can adjust, the output voltage begins to decrease. The setting of the control module effectively ensures that when the external AC power supply is cut off, the power-off delay circuit can still maintain a high degree of stability.

[0040] To sum up, the AC-DC circuit with power-off delay and power supply redundant protection of the present application forms a power-off delay circuit through a bridge rectifier module, a storage capacitor and a current limiting resistor, and the delay effect is more reliable and the circuit design is simplified; at the same time, it combines overvoltage and undervoltage protection and power supply redundant protection functions, so that the circuit has multiple functions. More importantly, the circuit realizes the above-mentioned multiple functions through fewer components, the implementation plan is simple, the cost is low and the effect is good.

[0041] In one embodiment, the holding time of the power-off delay circuit is obtained according to the following formula:

[0042] 0.5*C1*(Vin_nor 2 -Vin_min 2 )=⊿t*Po / η

[0043] Wherein: C1 is the rated capacity of the energy storage capacitor; Vin_nor is the DC voltage value after the external AC power supply is rectified by the bridge rectifier module; Vin_min is the minimum voltage value for the normal operation of the DC conversion module; ⊿t is the holding time; Po is the output power of the AC-DC circuit; η is the output efficiency of the AC-DC circuit; It is explained here 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%.

[0044] In one embodiment, an EMC filter module is further provided between the external power supply and the bridge rectifier module, and a voltage filter module is further provided between the bridge rectifier module and the DC conversion module.

[0045] Specifically, in this embodiment, the input end of the EMC filter module is connected to the external AC power supply, and the output end of the EMC filter module is connected to the input end of the bridge rectifier module. The high-frequency noise and electromagnetic radiation in the power line are attenuated by the EMC filter module, thereby effectively reducing the electromagnetic interference generated by the electronic equipment, preventing these electromagnetic interferences from propagating through the power line to the power grid or other electronic equipment, avoiding interference with other equipment or affecting their normal operation; thereby achieving the purpose of reducing the damage of high-frequency noise and electromagnetic radiation to the power module and internal components of the electronic equipment, and extending the service life of the equipment.

[0046] The input end of the voltage filter module is connected to the output end of the bridge rectifier module, and the output end of the voltage filter module is connected to the input end of the DC conversion module. The voltage filter module filters the pulsating DC voltage output by the bridge rectifier module through components such as filter capacitors, reduces the AC component, maintains the DC component, and makes the output voltage waveform smoother; it helps to improve the input voltage quality of the DC conversion module, thereby improving the stability and reliability of the entire circuit. And the filter capacitor in the voltage filter module can play the same role as the energy storage capacitor, that is, 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 power the entire circuit. And in this embodiment, the following examples are given:

[0047] When the external AC220V power is cut off, the energy stored in the energy storage capacitor C1 and the filter capacitor Cin is used to supply power to the output. During this process, the voltage of the energy storage capacitor C1 and the filter capacitor Cin gradually decreases. The control module can still achieve the rated output voltage by adjusting the duty cycle until the capacitor voltage drops beyond the range that the control module can adjust. The output voltage begins to decrease. According to the law of conservation of energy, the power-off holding time ⊿t of the AC-DC power module is proportional to the input capacitance, AC input voltage, and power module efficiency, and inversely proportional to the output power and the minimum operating voltage of the DC-DC part. The AC input voltage of the AC-DC power module is fixed, the minimum operating voltage of the DC-DC part generally cannot be changed, and the efficiency of the power module is difficult to improve. Therefore, the best way is to extend the power-off holding time of the AC-DC power module by increasing the input capacitance. The voltage output of the AC-DC power module is Vo = 5V, the output power is Po = 30W, the efficiency is η = 82%, the minimum voltage Vin_min for the DC-DC part to work normally 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 the AC220V input rectification and filtering is a DC voltage (actually with a certain ripple), and its value Vin_nor = 308V. According to the law of energy conservation, the following formula is obtained:

[0048] 0.5*(Cin+C1)*(Vin_nor 2 -Vin_min 2 )=⊿t*Po / η

[0049] Substituting the values ​​into the equation, we get: ⊿t = 263.3ms. This power-off holding time ⊿t far exceeds the requirements of field applications, and the effect of extending the power-off holding time ⊿t is significant, which is suitable for many applications.

[0050] In one embodiment, a switch is provided 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 DC voltage with a set voltage threshold, thereby controlling the opening or disconnection of the switch.

[0051] This implementation method monitors the DC voltage in real time through the overvoltage and undervoltage protection module and responds quickly to the operation through the switch component, so that abnormalities can be discovered in time to avoid being greatly affected; at the same time, the overvoltage and undervoltage protection module and the power supply redundancy protection module form a dual protection mechanism. Even if the main power supply fails or the voltage is abnormal, the power supply can be cut off in time 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, which not only improves the work efficiency, but also reduces the risk of human operation errors. In addition, the switch component adopts a PMOS tube, and the overvoltage and undervoltage protection module outputs a high level or a low level by comparing the real-time DC voltage 5VDC with the set voltage threshold value, so as to control the on and off of the PMOS tube. The PMOS tube has the advantages of low voltage difference, high stability, prevention of reverse current, improved circuit efficiency, simple manufacturing process, high input impedance, strong radiation resistance and wide application.

[0052] like Figure 3 As shown, in one embodiment, the overvoltage and undervoltage protection module includes a reference voltage generating circuit and a comparator, the reference voltage generating circuit includes a voltage regulator, a current limiting resistor and a voltage dividing resistor, the current limiting resistor is connected in series with the voltage regulator, and the output of the voltage regulator is connected to the input of the voltage dividing resistor, the output of the voltage dividing resistor is connected to the in-phase end of the comparator, the inverting end of the comparator is connected to the output end of the DC conversion module, and the output end of the comparator is connected to the power redundancy protection module through a switch.

[0053] Specifically, the overvoltage and undervoltage protection module includes an overvoltage and undervoltage protection circuit, which is mainly composed of U2, D1, D2, D3 and related resistors and capacitors. Among them, D1 is a 3V voltage regulator, and R2 connected in series with the voltage regulator plays a current limiting role to protect the voltage regulator. The 3V output of the voltage regulator is divided by R3, R7, and R15 to obtain the reference voltage VT1 (the voltage of pin 2 of U2A) and the reference voltage VT2 (the voltage of pin 5 of U2B), and U2 is a comparator.

[0054] The overvoltage protection circuit is mainly composed of U2A, R10, D2, R9, R13, R14, R3, R7, and R15 to form a common-phase comparison circuit with hysteresis. The reference voltage VT1 = 3V*(R7+R15) / (R3+R7+R15), the hysteresis voltage ⊿V1 = 3V*R13 / R10, according to the comparator characteristics, VT1 = VP*R10 / (R10+R13), and VP = Vin*R14 / (R9+R14), where Vin is the monitored input voltage. From the above, the overvoltage threshold OVLO = 3V*(R7+R15)*(R9+R14)*(R10+R13) / ((R3+R7+R15)*R14*R10)±3V*R13 / R10 can be calculated.

[0055] The undervoltage protection circuit is mainly composed of U2B, R16, D3, R9, R13, R14, R3, R7, and R15 to form an inverting comparison circuit with hysteresis. The reference voltage VT2 = 3V*R15 / (R3+R7+R15), the hysteresis voltage ⊿V2 = 3V*((R3+R7)||R15) / ((R3+R7)||R15+R16), according to the comparator characteristics, VT2 = VQ≈VP, and VP = Vin*R14 / (R9+R14), where Vin is the monitored input voltage. From the above, the undervoltage threshold UVLO = 3V*R15*(R9+R14) / ((R3+R7+R15)*R14)±3V*((R3+R7)||R15) / ((R3+R7)||R15+R16).

[0056] When Vin is greater than the undervoltage threshold UVLO and less than the overvoltage threshold OVLO, that is, Vin is within the normal working range, U2A outputs a low level, U2B outputs a low level, and after passing through diodes D2 and D3, the low level is input to the base of the NPN transistor Q4, and Q4 is cut off. At this time, Q3 is turned on, the G pole of the PMOS tube Q1 is at a low level, Q1 is turned on, and Vin continues to output voltage to the subsequent circuit to supply power to the load normally.

[0057] When Vin is greater than the overvoltage threshold OVLO, U2A outputs a high level and U2B outputs a low level. After passing through diodes D2 and D3, the high level is input to the base of the NPN transistor Q4, and Q4 is turned on. At this time, Q3 is cut off, and the G and S poles of the PMOS tube Q1 are both high levels, and Q1 is cut off, that is, Vin no longer outputs voltage to the outside, which provides overvoltage protection for the load.

[0058] When Vin is less than the under-voltage threshold UVLO, U2A outputs a low level and U2B outputs a high level. After passing through diodes D2 and D3, the high level is input to the base of the NPN transistor Q4, and Q4 is turned on. At this time, Q3 is cut off, and the G and S poles of the PMOS tube Q1 are both high levels, so Q1 is cut off, that is, Vin no longer outputs voltage to the outside, which provides under-voltage protection for the load.

[0059] The power redundancy protection module includes a power redundancy circuit and a filtering circuit connected to the power redundancy circuit; the power redundancy circuit includes a control chip, and the control chip is used to monitor the working status of the power module; at least two power modules: used for power supply; filtering elements: used to filter out noise and interference in the power supply; switching elements: used to disconnect or conduct under the action of the control chip to achieve power off or conduction.

[0060] Specifically, the power supply redundancy protection module includes a power supply redundancy protection circuit, which is mainly composed of U3, Q2, R6, C6, and C7. C5, C4, and TVS1 form a filter circuit to filter VDD_5V and suppress transient voltage. U3 is a control chip, which works with the external NMOS tube Q2 to achieve a low-loss reverse protection circuit function using an extremely low forward voltage drop (20mV). When U3's EN is high, U3 works normally, Q2 is turned on, and the power supply is normally output to the load. When U3's EN is low, U3 is turned off, Q2 is turned off, and the power supply no longer supplies power to the outside. In this power supply redundancy protection circuit, generally two power supplies with the same configuration work together at the same time, one of which is the main power supply and the other is the backup power supply. When the Vin of the main power supply is greater than OVLO or less than UVLO, Q1 is turned off, U3's EN is low, and U3 is turned off, that is, the abnormal power supply no longer supplies power to the outside to protect the load. At this time, the backup power supply takes over the main power supply module and continues to supply power to the load.

[0061] And 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 in-phase end and the output end of the push-pull output comparator TP2012, and the setting of the hysteresis resistor makes the comparator have a hysteresis function, which prevents the comparator input voltage from causing overvoltage or undervoltage protection malfunction due to voltage jitter when the comparator input voltage is near the reference voltage, affecting the normal power supply of the subsequent load, and then improving the stability of the entire circuit. The control chip in the power redundancy protection module is an ideal diode control chip, and its model is LM74700-Q1. The control chip (<0.75us) can quickly respond to reverse current blocking and avoid the risk of backflow current. When the main power supply that is broken is replaced with power, that is, at the moment of hot plugging, the VDD_5V output by the main power supply will be distorted, and there will be a risk of backflow current to the backup power supply, ensuring the normal operation of the backup power supply, and the main power supply after the replacement is continuously and stably and reliably powered to the load.

[0062] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. An AC-DC circuit with power failure delay power supply redundant protection, characterized in that: It includes a bridge rectifier module, a DC conversion module, an overvoltage and undervoltage protection module and a power redundancy protection module which are connected in sequence, the input end of the bridge rectifier module is connected to an external AC power supply, and the output end of the power redundancy protection module is connected to a load; it also includes 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; When the external AC power supply is normally supplied, the bridge rectifier module in the power-off delay circuit rectifies the DC power, and the DC power is then supplied to the load through the DC conversion module, the overvoltage and undervoltage protection module, and the power redundancy protection module in sequence; at the same time, the energy storage capacitor is charged after the current is limited by the current limiting resistor; When the external AC power supply is powered off, the energy storage capacitor in the power-off delay circuit is discharged, and the DC power discharged by the energy storage capacitor passes through the DC conversion module, the overvoltage and undervoltage protection module and the power redundancy protection module in sequence to supply power to the load, thereby realizing power-off delay; and the holding time of the power-off delay is greater than the load response time, and the load response time includes the load reaction time and the load action time; It also includes a control module, which is connected to the DC conversion module through an output feedback module. The control module is used to adjust the duty cycle according to the result of the output feedback module to achieve stable voltage output.

2. The AC-DC circuit with power failure delay power supply redundant protection according to claim 1, characterized in that: The holding time of the power-off delay circuit is obtained according to the following formula: 0.5*C1*(Wine_nor 2 -Vin_min 2 )=⊿t*Po / η Wherein: C1 is the rated capacity of the energy storage capacitor; Vin_nor is the DC voltage value after the external AC power supply is rectified by the bridge rectifier module; Vin_min is the minimum voltage value for the normal operation of the DC conversion module; ⊿t is the holding time; Po is the output power of the AC-DC circuit; η is the output efficiency of the AC-DC circuit.

3. The AC-DC circuit with power failure delay power supply redundant protection according to claim 1, characterized in that: An EMC filter module is further provided between the external power supply and the bridge rectifier module, and a voltage filter module is further provided between the bridge rectifier module and the DC conversion module.

4. The AC-DC circuit with power failure delay power supply redundant protection according to claim 1, characterized in that: A switch is provided between the overvoltage and undervoltage protection module and the power supply redundancy protection module. The overvoltage and undervoltage protection module is used to judge the real-time DC voltage with a set voltage threshold, thereby controlling the opening or disconnection of the switch.

5. The AC-DC circuit with power failure delay power supply redundant protection according to claim 4, characterized in that: The overvoltage and undervoltage protection module includes a reference voltage generating circuit and a comparator. The reference voltage generating circuit includes a voltage regulator, a current limiting resistor and a voltage dividing resistor. The current limiting resistor is connected in series with the voltage regulator, and the output of the voltage regulator is connected to the input of the voltage dividing resistor. The output of the voltage dividing resistor is connected to the in-phase end of the comparator, the inverting end of the comparator is connected to the output end of the DC conversion module, and the output end of the comparator is connected to the power supply redundancy protection module through a switch.

6. The AC-DC circuit with power failure delay power supply redundancy protection according to claim 5, characterized in that: The comparator is a push-pull output comparator TP2012, and a hysteresis resistor is connected between the in-phase terminal and the output terminal of the push-pull output comparator TP2012.

7. The AC-DC circuit with power failure delay power supply redundancy protection according to claim 1, characterized in that: The power redundancy protection module includes a power redundancy circuit and a filter circuit connected to the power redundancy circuit; the power redundancy circuit includes a control chip, and the control chip is used to monitor the working state of the power module; at least two power modules: used for power supply; Filter elements: used to filter out noise and interference in the power supply; Switching element: used to disconnect or conduct power or conduction under the action of the control chip.

8. The AC-DC circuit with power failure delay power supply redundancy protection according to claim 7, characterized in that: The control chip is an ideal diode control chip.

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