A low-loss redundant operation circuit for switching power supply

Abstract

The invention discloses a low-loss redundant operation circuit for a switching power supply, wherein one of the two switching power supply modules is used as a main power supply and the other is used as a redundant power supply; the positive terminals of the output terminals of the two switching power supply modules are directly connected in parallel; the negative terminals of the output terminals of the two switching power supply modules are isolated from each other by N-type MOSFETs and then connected in parallel; the negative terminal of the power input terminal of the standby redundant switching power supply module is controlled by an N-type MOSFET; the output terminal and the input terminal of the standby redundant switching power supply module are isolated by an optical coupler. The redundant operation design of the switching power supply module suitable for DC input and DC output does not require the internal circuit structure of the switching power supply module to be changed, the trouble-free operation time of the switching power supply is doubled, and the reliability of the power supply is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of redundant operation of switching power supplies, mainly a low-loss redundant operation circuit of a switching power supply, which is applied to a certain type of system power distribution equipment. The redundant design of the DC power supply board inside the power distribution cabinet can greatly improve the reliability of the power supply, and at the same time greatly improve the working reliability index of the equipment, thus ensuring the reliable and stable operation of the power distribution equipment. Background Art

[0002] Switching power supply is the basis of electronic equipment. If the power supply is abnormal, the electronic equipment will not work. In key areas, power supply abnormality is not allowed. However, electronic components cannot avoid abnormalities. In order to improve the reliability of the power supply, under the premise of using high-reliability electronic components inside the power supply, power supply redundancy operation backup is adopted, which can greatly increase the trouble-free operation time of the entire power supply.

[0003] At the same time, there is a possibility of reverse connection when operating the DC power supply input. In order to improve the reliability of the power supply, an input reverse connection protection design is added. When reverse connection occurs, no power supply components are damaged and the power supply does not work.

[0004] In the existing redundant operation design, the output end is isolated by diodes, and then the output is connected in parallel. When the current is large, the diode has a large loss. When the load of the power module increases, the output voltage drops, which can easily cause the backup power module to be mistakenly triggered and repeatedly switched.

[0005] Therefore, in view of the defects of the current existing technology, it is necessary to conduct research to provide a solution that can effectively and reliably improve the reliability of power supply redundancy operation, reduce output loss, and provide anti-reverse connection protection. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a low-loss redundant operation circuit for a switching power supply. The innovation lies in the two power modules used in the power supply. The input end adopts a non-destructive anti-reverse design, and the output end is controlled by low-loss control before being connected in parallel. When the output of the main power module is normal, the output of the backup power module is controlled to be shut off. When the main power supply has no output, the backup power module automatically starts and supplies power normally. It is suitable for the redundant operation design of the switching power supply module with DC input and DC output. There is no need to change the internal circuit structure of the switching power supply module. The trouble-free operation time of the switching power supply is doubled, which greatly improves the reliability of the power supply.

[0007] The object of the present invention is achieved through the following technical solutions: A switching power supply low-loss redundant operation circuit, comprising two negative logic control switching power supply modules U1 and U2, U1 as the main power supply, U2 as the redundant backup power supply, enabling the termination low-level module to work, and the DC 4V to DC 50V high-level or suspended module to shut down;

[0008] The negative end of the input of U1 and U2 adopts the switch tube Q1 to prevent reverse connection without damage; the positive end of the output power of U1 and U2 is directly connected in parallel and connected to the positive end of the power output. The negative end of the output of the two switching power modules is isolated from each other by N-type MOSFET and then connected in parallel. The negative end of the power input of the standby redundant switching power module is controlled by N-type MOSFET;

[0009] U1 is used as the main power supply. The power supply output controls the output of switch tube Q1 after voltage division. The output of U1 controls the output of switch tube Q2 of U2 to shut down. When U1 outputs normally, the output and input of the standby redundant switching power supply module are isolated by an optocoupler. The negative output of U2 is shut down by switch tube Q4. Switch tube Q3 is also shut down by optocoupler U3 to isolate and control the output of U2.

[0010] When U1 is outputting, it controls the U2 power enable terminal ENA; when U1 has no output, it automatically switches to U2; when U1 returns to normal, U1 continues to serve as the main power output and shuts down the power module U2;

[0011] When the power supply is just turned on, U1 and U2 work at the same time. When U1 works normally, U2 is turned off.

[0012] When the power module U1 has no output, the switch tube Q2 is in the off state;

[0013] When the power module U2 has no output, the switch tube Q3 is in the off state.

[0014] Furthermore, the power modules U1 and U2 are of the same model, the input DC voltage is lower than 800V, and the power module outputs a DC voltage; the power module is a negative logic N type or a positive logic P type. For the negative logic N type power module, the power module works when the enable terminal is connected to a low level, and the power module is turned off when the enable terminal is left floating or connected to a high level; for the P type power module, the module works when the enable terminal is left floating or connected to a high level, and the power is turned off when the enable terminal is grounded.

[0015] Furthermore, the switch tubes Q1, Q2 and Q3 are N-channel MOSFETs, and Q4 is an NPN transistor.

[0016] Furthermore, the negative-end reverse connection protection switch Q1 at the input end of the power module, its drain-source voltage withstand voltage Vds, gate voltage-dividing resistors R1 and R2, and voltage-stabilizing diode D1 vary according to the DC input voltage.

[0017] Furthermore, the negative end of the output terminal of the power module U1 is reverse-connected to prevent the switch tube Q2, its drain-source voltage withstand voltage Vds and the gate voltage-dividing resistors R4 and R5 and the voltage-stabilizing diode D3 change according to the DC output voltage.

[0018] Furthermore, the negative end of the output terminal of the power module U2 is reverse connected to the switch tube Q3, and its drain-source voltage withstand voltage Vds and gate voltage-dividing resistors R10 and R11 and the voltage-stabilizing diode D6 change according to the DC output voltage.

[0019] Furthermore, the output end of the power module U1 controls the enable end of U2 to shut down the power module by controlling the optocoupler U3, and the resistance value of the resistor R8 is not fixed according to the control requirements; the current transfer ratio CTR of the isolated controlled optocoupler is greater than 50%.

[0020] Compared with the prior art, the beneficial results of the present invention are:

[0021] 1. Using N-channel MOSFET, the conduction loss and switching loss are low, reducing the loss;

[0022] 2. The negative end of the power supply is controlled to improve the control stability and cost-effectiveness;

[0023] 3. The source and drain of the switch tube are isolated by diodes, which ensures the isolation switching effect of the switch tubes Q2 and Q3;

[0024] 4. The backup power module U2 is turned off, and the switch tube Q4 uses a common NPN transistor, which has low cost and low power consumption;

[0025] 5. The backup power input terminal is turned off and optical coupling isolation is used to ensure the isolation of input and output power supplies;

[0026] 6. When the main power supply is abnormal, the backup power supply can automatically switch to ensure the overall reliability of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit diagram of the main power supply and redundant power supply connection of the present invention.

[0028] Figure 2 This is a schematic diagram of shutting down the redundant power supply when the main power supply is working normally. The black bold line is the wiring diagram of the power supply circuit.

[0029] Figure 3 This is a schematic diagram of the redundant power supply starting and output when the main power supply has no output. The black bold line is the wiring diagram of the power supply circuit. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Meanwhile, the following embodiments are further explanations and supplements of the present invention and do not constitute any limitation to the present invention.

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

[0032] The present invention adopts the following technical scheme: a low-loss redundant operation circuit of a switching power supply, the power supply adopts two power modules of the same model, the negative end of the input end adopts an N-channel MOSFET device to prevent reverse connection without damage; the power module U1 is used as the main power supply and supplies power normally, the power module U2 is used as a redundant backup power supply, the positive end of the output end is directly connected in parallel and connected to the positive end of the power supply output; the power module U1 is used as the main power supply, and the negative end of the output is controlled by an N-channel MOSFET switch tube and then connected to the output; the power module U1 is used as the main power supply, and the power output is controlled by the switch tube Q1 after voltage division; the power module Block U1 is used as the main power supply, and the power output is controlled to shut down the output of the power supply module U2 switch tube Q2 after voltage division; the power supply module U1 is used as the main power supply, and the power output is controlled to shut down the enable end of the power supply module U2 after voltage division, and shut down the output of the backup power supply module U2; the power supply module U1 is used as the main power supply, and the resistance value and quantity of the power output switch tube Q2 voltage divider resistors R4 and R5 can be increased; the power supply module U2 is used as the backup power supply, when the input power supply is normal and the main power supply U1 has no output, the power enable terminal is connected to a low level, the power supply U2 is output, the switch tube Q3 is turned on, and the power output is powered.

[0033] When the power is first turned on, power modules U1 and U2 work at the same time. When power module U1 is stable, the output of power module U2 is turned off. When power module U1 has no output abnormality, U2 automatically turns on. Only one of U1 and U2 works.

[0034] See attached Figure 1 , schematic diagram of the circuit of the present invention. At the input end R1, R2, and D1, an input voltage-dividing and stabilizing circuit is formed to supply power to the gate of the N-channel MOSFET switch tube. The switch tube is first supplied with power by a small current through the internal body diode. When the switch tube is turned on, the internal body diode is bypassed, and the drain and source of the N-channel MOSFET are normally supplied with power. When the positive and negative terminals of the DC power input are reversed, the switch tube Q1 is not turned on, the power modules U1 and U2 have no input voltage, and the power supply does not work;

[0035] When the DC power supply is input normally, the main power module U1 and the backup power module U2 are powered on at the same time, and there is output. The main power indicator D2 and the backup power indicator D5 are lit at the same time. When the main power module is normal, the main power corresponding circuit turns off the output of the power module 2 switch Q3 through the NPN transistor Q4, and at the same time turns off the backup power module U2 through the optical coupler U3, turning off the module and reducing the standby power consumption;

[0036] When the DC power supply is input normally and the main power supply module U1 has no output, the switch tube Q2 that controls the power output is turned off, the signal to shut down the backup power supply U2 output becomes invalid, the backup power supply U2 is turned on, the switch tube Q3 is turned on, and the backup power supply module provides power.

[0037] When the main power module U2 is repaired and returns to normal, the backup power module U2 is automatically shut down and the main power module continues to supply power.

[0038] The above embodiments are only for the purpose of illustrating the present invention, rather than limiting the present invention. Any inventions and creations that do not exceed the essential spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A low-loss redundant operation circuit for a switching power supply, characterized in that: It includes two negative logic control switch power supply modules U1 and U2, U1 is used as the main power supply, and U2 is used as the redundant backup power supply, which enables the low-level module to work, and the DC 4V~DC 50V high level or floating module to shut down; The negative end of the input of U1 and U2 uses the switch tube Q1 to prevent reverse connection without damage; the positive end of the output power supply of U1 and U2 is directly connected in parallel and connected to the positive end of the power supply output; U1 is the main power supply. The power supply output controls the output of switch tube Q1 after voltage division. The output of U1 controls the output of switch tube Q2 of U2. When U1 outputs normally, the negative output of U2 is turned off through switch tube Q4. At the same time, the output of U2 is turned off through the isolation control of optocoupler U3. When U1 is outputting, it controls the U2 power enable terminal ENA; when U1 has no output, it automatically switches to U2; when U1 returns to normal, U1 continues to serve as the main power output and shuts down the power module U2; When the power supply is just turned on, U1 and U2 work at the same time. When U1 works normally, U2 is turned off. When the power module U1 has no output, the switch tube Q2 is in the off state; When the power module U2 has no output, the switch tube Q3 is in the off state; The D terminal of the switch tube Q1 is connected to the input terminal -Vi, the G terminal of the switch tube Q1 is connected to one end of R2, and the S terminal of the switch tube Q1 is connected to the -Vin terminal and the ENA terminal of U1; the D terminal of the switch tube Q2 is connected to the output terminal -Vo, the G terminal of the switch tube Q2 is connected to one end of the voltage-stabilizing diode D3, and the S terminal of the switch tube Q2 is connected to the -Vo terminal of U1; the D terminal of the switch tube Q3 is connected to the output terminal -Vo, the G terminal of the switch tube Q3 is connected to one end of the voltage-stabilizing diode D6, and the S terminal of the switch tube Q3 is connected to the -Vo terminal of U2; the switch tube Q4 is connected to one end of R6; The power modules U1 and U2 are of the same model, the input DC voltage is lower than 800V, and the power modules output DC voltage; the power modules are negative logic N-type or positive logic P-type. For the negative logic N-type power module, the power module works when the enable terminal is connected to a low level, and the power module is turned off when the enable terminal is left unconnected or connected to a high level; for the P-type power module, the module works when the enable terminal is left unconnected or connected to a high level, and the power is turned off when the enable terminal is grounded; The switch tubes Q1, Q2 and Q3 are N-channel MOSFETs, and Q4 is an NPN transistor.

2. The switching power supply low-loss redundant operation circuit according to claim 1, characterized in that: The negative terminal anti-reverse connection switch Q1 at the input end of the power module, its drain-source voltage withstand voltage Vds, gate voltage-dividing resistors R1 and R2, and voltage-stabilizing diode D1 adjust parameters according to changes in the DC input voltage.

3. The switching power supply low-loss redundant operation circuit according to claim 1, characterized in that: The negative end of the output terminal of the power module U1 has an anti-reverse connection switch tube Q2, whose drain-source voltage withstand voltage Vds, gate voltage divider resistors R4 and R5, and voltage regulator diode D3 adjust parameters according to the change of DC output voltage.

4. The switching power supply low-loss redundant operation circuit according to claim 1, characterized in that: The negative end of the output terminal of the power module U2 is an anti-reverse connection switch tube Q3, whose drain-source voltage withstand voltage Vds, gate voltage divider resistors R10 and R11, and voltage regulator diode D6 adjust parameters according to the changes in the DC output voltage.

5. The switching power supply low-loss redundant operation circuit according to claim 1, characterized in that: The output end of the power module U1 controls the enable end of U2 by controlling the optocoupler U3 to shut down the power module, and the current transfer ratio CTR of the isolated controlled optocoupler is greater than 50%.

Images