An automatic switching circuit for hot redundant to cold redundant backup power supply

Abstract

The present invention discloses an automatic switching circuit for hot-redundant to cold-redundant backup power supplies. The circuit is characterized by comprising a power input circuit A, a 12V redundant circuit B, a first controllable switch circuit C, a first voltage comparator circuit D, a second voltage comparator circuit E, a second controllable switch circuit F, and an automatic relay switching circuit G, all connected in sequence. The power input circuit A is further connected to the first voltage comparator circuit D and the second voltage comparator circuit E; the first controllable switch circuit C is further connected to the second voltage comparator circuit E, the second controllable switch circuit F, and the automatic relay switching circuit G; and the first voltage comparator circuit D is further connected to the second controllable switch circuit F. This circuit can achieve cold standby operation of two power outputs, accelerate power switching, and has low circuit cost. It can also effectively avoid the problem of mutual interference between the two power supplies when the power module is used in a hot-redundant state.

Description

Technical Field

[0001] The invention relates to the field of electronic technology, in particular to an automatic switching circuit for hot redundant to cold redundant standby power supplies. Background Art

[0002] With the continuous development of electronic circuits, electronic products are becoming increasingly intelligent. To ensure reliable operation, the power supply for important circuits within these electronic products generally uses dual power supplies for redundancy. If one power supply fails, it can seamlessly switch to the other power supply. If one power supply fails, it can also seamlessly switch to the other power supply if one power supply fails.

[0003] Currently, when designing the internal circuits of electronic products, dual power supply circuits typically use Schottky diodes or dedicated chips to achieve parallel output power. Circuits using Schottky diodes have current limitations on the output circuit, resulting in inability to dissipate heat from the device under high current conditions, thus affecting power supply conversion efficiency. Circuits using dedicated chips are expensive and require numerous peripheral circuits. Therefore, a solution is needed that can meet the requirements of dual power supply redundancy while simplifying the circuit and reducing the cost of redundant power supply output circuits. Summary of the Invention

[0004] The present invention addresses the shortcomings of existing technologies by providing a circuit for automatically switching power supplies from hot-redundant to cold-redundant. This circuit enables cold standby operation of two power outputs, speeds up power switching, is low-cost, and effectively prevents interference between the two power supplies when the power module is operating in hot-redundant mode.

[0005] The technical solution for achieving the purpose of the present invention is:

[0006] A hot redundant to cold redundant standby power supply automatic switching circuit comprises a power input circuit A, a 12V redundant circuit B, a first controllable switch circuit C, a first voltage comparator circuit D, a second voltage comparator circuit E, a second controllable switch circuit F and a relay automatic switching circuit G connected in sequence, wherein the power input circuit A is also connected to the first voltage comparator circuit D and the second voltage comparator circuit E; the first controllable switch circuit C is also connected to the second voltage comparator circuit E, the second controllable switch circuit F and the relay automatic switching circuit G; and the first voltage comparator circuit D is also connected to the second controllable switch circuit F.

[0007] The power input circuit A includes a first power supply and a second power supply of the same structure connected in parallel. The first power supply and the second power supply are both provided with 4 pin terminals, wherein the 1-pin terminal of the first power supply is connected to 48VA+, the 1-pin terminal of the second power supply is connected to 48VB+, the 3-pin terminal of the first power supply is connected to 12VA+, the 3-pin terminal of the second power supply is connected to 12VB+, and the 4-pin terminals of the first power supply and the second power supply are both connected to the common ground GND.

[0008] The 12V redundant circuit B includes four parallel-connected first chip resistors R1, second chip resistors R2, eleventh chip resistors R12, and twelfth chip resistors R13 and a first diode D1 and a second diode D2, wherein the positive electrode of the first diode D1 is connected to the 3-pin terminal of the first power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13; the positive electrode of the second diode D2 is connected to the 3-pin terminal of the second power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13; the cathodes of the first diode D1 and the second diode D2 are connected and connected to the first controllable switch circuit C. When the 12V of one power supply is short-circuited to GND, it will not affect the normal working power supply of the other power supply, thereby avoiding the short circuit of the 12V of one power supply affecting the 12V of the other power supply. At the same time, the faulty power supply can operate normally with a 12V voltage when there is no short circuit.

[0009] The first controllable switch circuit C is provided with a bidirectional TVS tube ZD1, a first chip capacitor C1, a first controllable switch transistor Q2 and a fourth diode D4. Among them, one end of the bidirectional TVS tube ZD1 is connected to the self-recovery fuse FS1 and the other end is connected to GND. The other end of the self-recovery fuse FS1 is connected to the cathode of the first diode D1 and the second diode D2. The two pins of the first chip capacitor C1 are respectively connected to the two pins of the bidirectional TVS tube ZD1 to play a filtering role. Finally, 12V is output to the subsequent circuit to provide the working voltage, which can provide To ensure high circuit stability and reliability, the first chip capacitor C1 and the bidirectional TVS tube ZD1 are connected to the common end, which is then connected in series with the ninth chip resistor R10 and then connected to the base pin 1 of the first controllable switch transistor Q2. The emitter pin 2 of the first controllable switch transistor Q2 is connected to the second controllable switch circuit F. The collector pin 3 of the first controllable switch transistor Q2 is connected to the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the first voltage comparator circuit D. The ninth chip resistor R10 is connected to 12V to provide a driving voltage for the first controllable switch transistor Q2.

[0010] The first voltage comparator circuit D is provided with a first voltage comparator U1A. The third chip resistor R3 is connected in series to the non-inverting input terminal 3 of the first voltage comparator U1A. The other end of the third chip resistor R3 is connected to the 12V of the first controllable switch circuit C. The common connection terminal 3 of the third chip resistor R3 and the first voltage comparator U1A serves as the reference voltage V of the voltage comparator. ref The two ends of the third chip capacitor C3 are connected to the common connection terminal 3 of the first voltage comparator U1A and GND respectively. The function is to ensure that the response time of the 12V voltage is slower than that of the 48V voltage. The logic level output of the first voltage comparator U1A is normal. The common connection terminal of the reverse input terminal 2 of the first voltage comparator U1A and the positive electrode of the fourth diode D4 is connected to one end of the fourth chip resistor R4 and one end of the fifth chip resistor R5, and the voltage of this common connection terminal is the voltage to be compared V of the voltage comparator. f The other end of the fourth chip resistor R4 is connected to pin 1 48VA+ of the first power supply, the other end of the fifth chip resistor R5 is connected in series with the eighth chip resistor R8 and then connected to GND, the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A is connected to the 12V of the first controllable switch circuit C to power the first voltage comparator U1A, the two pins of the second chip capacitor C2 are respectively connected to the Vcc power supply voltage terminal pin 8 and the GND ground terminal pin 4 of the first voltage comparator U1A, the GND ground terminal pin 4 of the first voltage comparator U1A is connected to GND, the two ends of the tenth chip resistor R11 are respectively connected to the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A and the output terminal pin 1 of the first voltage comparator U1A, the output terminal pin 1 of the first voltage comparator U1A and the common connection end of the tenth chip resistor R11 are connected to the second controllable switch circuit F.

[0011] The second voltage comparator circuit E is provided with a second voltage comparator U1B, and the non-inverting input terminal 5 pin of the second voltage comparator U1B is connected in series with the sixth chip resistor R6, and the other end of the sixth chip resistor R6 is connected to the 12V of the first controllable switch circuit C. The Vcc power supply voltage terminal 8 pin of the second voltage comparator U1B is connected to the 12V of the first controllable switch circuit C to power the second voltage comparator U1B, and the two ends of the fourth chip capacitor C4 are respectively connected to the non-inverting input terminal 5 pin of the second voltage comparator U1B and GND, which is used to ensure that the response time of the 12V voltage is slower than that of 48V and the comparator logic level output is normal. The reverse input terminal 6 pin of the second voltage comparator U1B is connected to one end of the seventh chip resistor R7, and the other end of the seventh chip resistor R7 is connected to the 1 pin 48VB+ of the second power supply. The common connection end of the seventh chip resistor R7 and the reverse input terminal 6 pin of the second voltage comparator U1B is connected to the 2 pin of the first voltage comparator U1A, and the output terminal 7 pin of the second voltage comparator U1B is connected to the second controllable switch circuit F.

[0012] The second controllable switch circuit F is provided with a second controllable switch transistor Q3, the base pin 1 of the second controllable switch transistor Q3 is connected to the output pin 1 of the first voltage comparator U1A in the first voltage comparator circuit D, the common connection end of the tenth chip resistor R11, and the output pin 7 of the second voltage comparator U1B, the emitter pin 2 of the second controllable switch transistor Q3 is grounded, and the collector pin 3 of the second controllable switch transistor Q3 is connected to the emitter pin 2 of the first controllable switch transistor Q2 of the first controllable switch circuit C.

[0013] The relay automatic switching circuit G is provided with a double relay K1 and a third diode D3 as an automatic switching switch for converting hot redundancy into cold redundancy. Pin 1 of the inductor coil inside the double relay K1 is connected to the 12V of the first controllable switch circuit C and the negative electrode of the third diode D3. Pin 2 of the inductor coil inside the double relay K1 is connected to the positive electrode of the third diode D3 and the collector pin 3 of the second controllable switch transistor Q3. The third diode D3 is used to form a loop discharge for the inductor coil between pin 1 and pin 2 inside K1 to prevent the instantaneous high-voltage discharge of the inductor from causing the second controllable switch transistor Q 3. Cause damage. Pin 5 of the inductor coil inside the double relay K1 is connected to pin 1 (48VA+) of the first power supply. Pin 6 of the inductor coil inside the double relay K1 is connected to the disposable fuse FS2 and then to pin 1 (48VB+) of the second power supply. When the 48V of one of the power supplies is short-circuited, the large current will melt the disposable fuse FS2, separating the short-circuited power supply from the other normally working power supply, thereby avoiding affecting the other normally working power supply. Pins 7 and 8 of the inductor coil inside the double relay K1 are normally open contacts and are short-circuited, and pins 3 and 4 are normally closed contacts and are left floating.

[0014] The inverting input terminal 2 of the first voltage comparator U1A is connected to the inverting input terminal 6 of the second voltage comparator U1B and a fourth diode D4 is connected in series. The fourth diode D4 has unidirectional conductivity and can prevent the 12V input voltage from passing through the first controllable switch transistor Q2 to the comparison voltage V f have an impact.

[0015] According to the output level characteristics of the voltage comparator, the first control switch transistor Q2 and the second control switch transistor Q3 are turned on. When one of the power supplies fails and there is no 48V output, the comparator outputs a high level, and the 12V voltage signal is given to pin 1 of the second controllable switch transistor Q3 through the tenth chip resistor R11. The second controllable switch transistor Q3 is then actuated, so that pins 3 and 2 of the second controllable switch transistor Q3 are turned on and grounded. Then, the inductor coil inside the dual-group relay K1 forms a loop and current flows through it, causing the relay to actuate and switch to the normally open contact, that is, pins 5 and 7 of the dual-group relay K1 are connected, and pins 6 and 8 are connected, automatically connecting the 48V output load end of the faulty power supply to the 48V output load end of the normal power supply, thereby realizing hot redundancy to cold redundancy switching.

[0016] Furthermore, the inverting input pin 2 of the first voltage comparator U1A is connected to the inverting input pin 6 of the second voltage comparator U1B, and then connected to pin 3 of the first controllable switch transistor Q2 through a fourth diode D4. Pin 2 of the first controllable switch transistor Q2 is connected to pin 3 of the second controllable switch transistor Q3, and pin 2 of the second controllable switch transistor Q3 is grounded. When one of the power supplies fails and there is no 48V output or the power supply voltage output is abnormally low, the second controllable switch transistor Q3 is activated, causing pins 3 and 2 to be connected to ground. At this time, pin 2 of the first controllable switch transistor Q2 is connected to ground through the second controllable switch transistor Q3, and the inverting input terminals of the two comparators are grounded. This causes the voltage at the non-inverting input terminal of the comparator to be always greater than the voltage at the inverting input terminal, and the comparator to be always in a high-level output state. The relay will be always in a normally open contact state. At this time, the circuit is in a latched state, and the comparator will not re-compare the voltage until the power supply is turned off and then powered on again.

[0017] Furthermore, to ensure that the 12V voltage response time is slower than that of 48V and the comparator logic level output is normal, a third chip capacitor C3 and a fourth chip capacitor C4 with large capacitance are added to the 12V non-inverting input terminal of the two voltage comparator units relative to the ground, and a third chip resistor R3 and a sixth chip resistor R6 with large resistance are connected in series between the non-inverting input terminal of the comparator and the 12V input terminal, respectively. It will be more reliable to obtain the 12V voltage through a 48V to 12V DC-DC power supply module.

[0018] Pin 2 of the inverting input of the first voltage comparator U1A is connected to pin 6 of the inverting input of the second voltage comparator U1B, and then connected to pin 3 of the first controllable switch transistor Q2 through a fourth diode D4. Pin 2 of the first controllable switch transistor Q2 is connected to pin 3 of the second controllable switch transistor Q3, and pin 2 of the second controllable switch transistor Q3 is grounded. When one of the power supplies fails and there is no 48V output or the power supply voltage output is abnormally low, the second controllable switch transistor Q3 is activated, causing pins 3 and 2 to be connected to ground. At this time, pin 2 of the first controllable switch transistor Q2 is connected to ground through the second controllable switch transistor Q3, and the inverting inputs of the two comparators are grounded, so that the voltage at the non-inverting input of the comparator is always greater than the voltage at the inverting input, and the comparator is always in a high-level output state. The relay will always be in a normally open contact state. At this time, the circuit is in a latched state, and the comparator will not re-compare the voltage until the power supply is turned off and then powered on again.

[0019] The chip resistors R1, R2, R12, and R13 are 510Ω, 2010Ω, and 3 / 4W.

[0020] The ZD1 specification model is a 13V bidirectional TVS tube.

[0021] The specifications of the C1 chip capacitor are 6.8uF-10uF, 25V.

[0022] The specifications of the chip resistors R10 and R11 are 10KΩ, 0805, 1 / 8W.

[0023] The specification of the resettable fuse FS1 is 0.1A, 30V-60V.

[0024] The specification of the disposable fuse FS2 is 8A, ≥48V.

[0025] The specifications of the R3 and R6 chip resistors are 100K-510KΩ, 0805, and 1 / 8W.

[0026] The specifications of the chip capacitors C3 and C4 are 4.7uF-10uF, 25V.

[0027] The specifications of the chip resistors R4 and R7 are 56KΩ±1%, 0805, and 1 / 8W.

[0028] The specifications of the R5 chip resistor are 9.1KΩ±1%, 0805, 1 / 8W.

[0029] The specifications of the R8 chip resistor are 300Ω±1%, 0805, and 1 / 8W.

[0030] The controllable switch tube is an NPN type transistor.

[0031] The voltage comparator adopts a dual voltage comparator chip of model LM393, which integrates two comparators and has a DC power supply positive input pin. The power input to this pin is used to power the two comparator units simultaneously through the internal circuit of the chip.

[0032] This technical solution realizes the automatic switching of the comparative redundancy of the power supply output voltage through the combination of a comparator, a controllable switch tube and a relay, and can realize the cold standby of the two outputs with a small output switching delay. It is particularly suitable for converting the hot redundant circuit of two power supplies in parallel output into a cold redundant circuit, especially in the field of rail transit passenger compartment lighting applications. It can realize the technical solution of dual power redundant power supply required in electronic circuit systems. The modular circuit structure is simple, the cost is low and the reliability is high.

[0033] This circuit can achieve cold standby of two power outputs, speed up power switching, and has low circuit cost. It can also effectively avoid the mutual interference problem between the two power supplies when the power module is used in hot redundancy state. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of an embodiment;

[0035] Figure 2 for Figure 1 Schematic diagram of the principle;

[0036] Figure 3 The schematic diagram of the embodiment circuit is applied to the redundant output lines of two power supplies in hot redundant state. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0038] Example:

[0039] Reference Figure 1 、 Figure 2 ,

[0040] A hot redundant to cold redundant standby power supply automatic switching circuit comprises a power input circuit A, a 12V redundant circuit B, a first controllable switch circuit C, a first voltage comparator circuit D, a second voltage comparator circuit E, a second controllable switch circuit F and a relay automatic switching circuit G connected in sequence, wherein the power input circuit A is also connected to the first voltage comparator circuit D and the second voltage comparator circuit E; the first controllable switch circuit C is also connected to the second voltage comparator circuit E, the second controllable switch circuit F and the relay automatic switching circuit G; and the first voltage comparator circuit D is also connected to the second controllable switch circuit F.

[0041] The power input circuit A includes a first power supply and a second power supply of the same structure connected in parallel. The first power supply and the second power supply are both provided with 4 pin terminals, wherein the 1-pin terminal of the first power supply is connected to 48VA+, the 1-pin terminal of the second power supply is connected to 48VB+, the 3-pin terminal of the first power supply is connected to 12VA+, the 3-pin terminal of the second power supply is connected to 12VB+, and the 4-pin terminals of the first power supply and the second power supply are both connected to the common ground GND.

[0042] The 12V redundant circuit B includes four parallel resistors, a first chip resistor R1, a second chip resistor R2, an eleventh chip resistor R12, and a twelfth chip resistor R13, and a first diode D1 and a second diode D2 in parallel. The positive electrode of the first diode D1 is connected to the 3-pin terminal of the first power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13; the positive electrode of the second diode D2 is connected to the 3-pin terminal of the second power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13. The cathodes of the first diode D1 and the second diode D2 are connected and connected to the first controllable switch circuit C. When the 12V of one power supply is short-circuited to GND, it will not affect the normal working power supply of the other power supply, thereby avoiding the short circuit of the 12V of one power supply affecting the 12V of the other power supply. At the same time, the faulty power supply can operate normally with a 12V voltage when there is no short circuit.

[0043] The first controllable switch circuit C is provided with a bidirectional TVS tube ZD1, a first chip capacitor C1, a first controllable switch transistor Q2 and a fourth diode D4. Among them, one end of the bidirectional TVS tube ZD1 is connected to the self-recovery fuse FS1 and the other end is connected to GND. The other end of the self-recovery fuse FS1 is connected to the cathode of the first diode D1 and the second diode D2. The two pins of the first chip capacitor C1 are respectively connected to the two pins of the bidirectional TVS tube ZD1 to play a filtering role. Finally, 12V is output to the subsequent circuit to provide working voltage, which can improve the stability and reliability of the circuit. The first chip capacitor C1 and the bidirectional TVS tube ZD1 are connected to the common end, which is then connected in series with the ninth chip resistor R10 and then connected to the base pin 1 of the first controllable switch transistor Q2. The emitter pin 2 of the first controllable switch transistor Q2 is connected to the second controllable switch circuit F. The collector pin 3 of the first controllable switch transistor Q2 is connected to the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the first voltage comparator circuit D. The ninth chip resistor R10 is connected to 12V to provide a driving voltage to the first controllable switch transistor Q2.

[0044] The first voltage comparator circuit D is provided with a first voltage comparator U1A. The third chip resistor R3 is connected in series to the non-inverting input terminal 3 of the first voltage comparator U1A. The other end of the third chip resistor R3 is connected to the 12V of the first controllable switch circuit C. The common connection terminal 3 of the third chip resistor R3 and the first voltage comparator U1A serves as the reference voltage V of the voltage comparator. ref The two ends of the third chip capacitor C3 are connected to the common connection terminal 3 of the first voltage comparator U1A and GND respectively. The function is to ensure that the response time of the 12V voltage is slower than that of the 48V voltage. The logic level output of the first voltage comparator U1A is normal. The common connection terminal of the reverse input terminal 2 of the first voltage comparator U1A and the positive electrode of the fourth diode D4 is connected to one end of the fourth chip resistor R4 and one end of the fifth chip resistor R5, and the voltage of this common connection terminal is the voltage to be compared V of the voltage comparator. f The other end of the fourth chip resistor R4 is connected to pin 1 48VA+ of the first power supply, the other end of the fifth chip resistor R5 is connected in series with the eighth chip resistor R8 and then connected to GND, the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A is connected to the 12V of the first controllable switch circuit C to power the first voltage comparator U1A, the two pins of the second chip capacitor C2 are respectively connected to the Vcc power supply voltage terminal pin 8 and the GND ground terminal pin 4 of the first voltage comparator U1A, the GND ground terminal pin 4 of the first voltage comparator U1A is connected to GND, the two ends of the tenth resistor R11 are respectively connected to the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A and the output terminal pin 1 of the first voltage comparator U1A, the output terminal pin 1 of the first voltage comparator U1A and the common connection end of the tenth chip resistor R11 are connected to the second controllable switch circuit F.

[0045] The second voltage comparator circuit E is provided with a second voltage comparator U1B, and the non-inverting input terminal 5 pin of the second voltage comparator U1B is connected in series with the sixth chip resistor R6, and the other end of the sixth chip resistor R6 is connected to the 12V of the first controllable switch circuit C. The Vcc power supply voltage terminal 8 pin of the second voltage comparator U1B is connected to the 12V of the first controllable switch circuit C to power the second voltage comparator U1B, and the two ends of the fourth chip capacitor C4 are respectively connected to the non-inverting input terminal 5 pin of the second voltage comparator U1B and GND, which is used to ensure that the response time of the 12V voltage is slower than that of 48V and the comparator logic level output is normal. The reverse input terminal 6 pin of the second voltage comparator U1B is connected to one end of the seventh chip resistor R7, and the other end of the seventh chip resistor R7 is connected to the 1 pin 48VB+ of the second power supply. The common connection end of the seventh chip resistor R7 and the reverse input terminal 6 pin of the second voltage comparator U1B is connected to the 2 pin of the first voltage comparator U1A, and the output terminal 7 pin of the second voltage comparator U1B is connected to the second controllable switch circuit F.

[0046] The second controllable switch circuit F is provided with a second controllable switch transistor Q3, the base pin 1 of the second controllable switch transistor Q3 is connected to the output pin 1 of the first voltage comparator U1A in the first voltage comparator circuit D, the common connection end of the tenth chip resistor R11, and the output pin 7 of the second voltage comparator U1B, the emitter pin 2 of the second controllable switch transistor Q3 is grounded, and the collector pin 3 of the second controllable switch transistor Q3 is connected to the emitter pin 2 of the first controllable switch transistor Q2 of the first controllable switch circuit C.

[0047] The relay automatic switching circuit G is provided with a double relay K1 and a third diode D3 as an automatic switching switch for converting hot redundancy into cold redundancy. Pin 1 of the inductor coil inside the double relay K1 is connected to the 12V of the first controllable switch circuit C and the negative electrode of the third diode D3. Pin 2 of the inductor coil inside the double relay K1 is connected to the positive electrode of the third diode D3 and the collector pin 3 of the second controllable switch transistor Q3. The third diode D3 is used to form a loop discharge for the inductor coil between pin 1 and pin 2 inside K1 to prevent the instantaneous high-voltage discharge of the inductor from causing the second controllable switch transistor Q 3. Cause damage. Pin 5 of the inductor coil inside the double relay K1 is connected to pin 1 (48VA+) of the first power supply. Pin 6 of the inductor coil inside the double relay K1 is connected to the disposable fuse FS2 and then to pin 1 (48VB+) of the second power supply. When the 48V of one of the power supplies is short-circuited, the large current will melt the disposable fuse FS2, separating the short-circuited power supply from the other normally working power supply, thereby avoiding affecting the other normally working power supply. Pins 7 and 8 of the inductor coil inside the double relay K1 are normally open contacts and are short-circuited, and pins 3 and 4 are normally closed contacts and are left floating.

[0048] The inverting input terminal 2 of the first voltage comparator U1A is connected to the inverting input terminal 6 of the second voltage comparator U1B and a fourth diode D4 is connected in series. The fourth diode D4 has unidirectional conductivity and can prevent the 12V input voltage from passing through the first controllable switch transistor Q2 to the comparison voltage V f have an impact.

[0049] According to the output level characteristics of the voltage comparator, the first control switch transistor Q2 and the second control switch transistor Q3 are turned on. When one of the power supplies fails and there is no 48V output, the comparator outputs a high level, and the 12V voltage signal is given to pin 1 of the second controllable switch transistor Q3 through the tenth chip resistor R11. The second controllable switch transistor Q3 is then actuated, so that pins 3 and 2 of the second controllable switch transistor Q3 are turned on and grounded. Then, the inductor coil inside the dual-group relay K1 forms a loop and current flows through it, causing the relay to actuate and switch to the normally open contact, that is, pins 5 and 7 of the dual-group relay K1 are connected, and pins 6 and 8 are connected, automatically connecting the 48V output load end of the faulty power supply to the 48V output load end of the normal power supply, thereby realizing hot redundancy to cold redundancy switching.

[0050] Furthermore, the inverting input pin 2 of the first voltage comparator U1A is connected to the inverting input pin 6 of the second voltage comparator U1B, and then connected to pin 3 of the first controllable switch transistor Q2 through a fourth diode D4. Pin 2 of the first controllable switch transistor Q2 is connected to pin 3 of the second controllable switch transistor Q3, and pin 2 of the second controllable switch transistor Q3 is grounded. When one of the power supplies fails and there is no 48V output or the power supply voltage output is abnormally low, the second controllable switch transistor Q3 is activated, causing pins 3 and 2 to be connected to ground. At this time, pin 2 of the first controllable switch transistor Q2 is connected to ground through the second controllable switch transistor Q3, and the inverting input terminals of the two comparators are grounded. This causes the voltage at the non-inverting input terminal of the comparator to be always greater than the voltage at the inverting input terminal, and the comparator to be always in a high-level output state. The relay will be always in a normally open contact state. At this time, the circuit is in a latched state, and the comparator will not re-compare the voltage until the power supply is turned off and then powered on again.

[0051] Furthermore, to ensure that the 12V voltage response time is slower than that of 48V and the comparator logic level output is normal, a third chip capacitor C3 and a fourth chip capacitor C4 with large capacitance are added to the 12V non-inverting input terminal of the two voltage comparator units relative to the ground, and a third chip resistor R3 and a sixth chip resistor R6 with large resistance are connected in series between the non-inverting input terminal of the comparator and the 12V input terminal, respectively. It will be more reliable to obtain the 12V voltage through a 48V to 12V DC-DC power supply module.

[0052] In this example, the chip resistors R1, R2, R12, and R13 are 510Ω, 2010Ω, and 3 / 4W.

[0053] In this example, the ZD1 specification model is a 13V bidirectional TVS diode.

[0054] In this example, the specifications of the C1 chip capacitor are 6.8uF-10uF, 25V.

[0055] In this example, the chip resistors R10 and R11 are 10KΩ, 0805, and 1 / 8W.

[0056] In this example, the specification of the resettable fuse FS1 is 0.1A, 30V-60V.

[0057] In this example, the specifications of the disposable fuse FS2 are 8A and ≥48V.

[0058] In this example, the chip resistors R3 and R6 are 100K-510KΩ, 0805, and 1 / 8W.

[0059] In this example, the specifications of the chip capacitors C3 and C4 are 4.7uF-10uF, 25V.

[0060] In this example, the chip resistors R4 and R7 are 56KΩ±1%, 0805, and 1 / 8W.

[0061] In this example, the specifications of the R5 chip resistor are 9.1KΩ±1%, 0805, 1 / 8W.

[0062] In this example, the specifications of the R8 chip resistor are 300Ω±1%, 0805, and 1 / 8W.

[0063] In this example, the controllable switch tube is an NPN transistor.

[0064] In this example, the voltage comparator uses a dual voltage comparator chip model LM393. The chip integrates two comparators and has a DC power supply positive input pin. The power input to this pin is used to power the two comparator units simultaneously through the internal circuit of the chip.

[0065] like Figure 2 As shown in the figure, when the two power supplies are normal, the comparator outputs a low level, the switch tube Q3 1 pin has no voltage and does not operate, then the internal inductor coil of relay K1 has no current and does not operate, and is in a normally closed contact, that is, K1's 5th and 3rd pins are short-circuited, and K1's 6th and 4th pins are short-circuited, separating the two power supply output ends and carrying loads separately, thereby switching hot redundancy to cold redundancy and putting the two power supplies in cold standby state.

[0066] According to the formula or V f The voltage should be adjusted to about 12V and should be greater than 12V, which is equal to the reference voltage V ref Perform comparison to ensure the sensitivity and reliability of the comparator action.

[0067] When one of the power supplies fails and no 48V voltage is output, according to the formula or The voltage at the inverting input of the comparator will be lower than the voltage at the non-inverting input, and the comparator will output a high level. Pins 3 and 2 of the switch tube Q3 will be connected to ground, and the relay will switch to the normally open contact, switching the load carried by the faulty power supply to the output load end of the normal power supply, thereby realizing the redundancy function.

[0068] like Figure 3 As shown, the embodiment circuit is applied to the redundant output lines of two power supplies in hot redundant state, that is, the black frame in the figure. The input voltages of the two power supplies need to be connected to the same power supply to ensure simultaneous power-on, so that the 48V output voltages of the two power supplies can be output basically synchronously to avoid the problem of comparator malfunction caused by long delay, and the automatic switching function of hot redundant to cold redundant backup power supply can be realized.

Claims

1. A hot redundant to cold redundant backup power supply automatic switching circuit, characterized in that: The invention comprises a power input circuit A, a 12V redundant circuit B, a first controllable switch circuit C, a first voltage comparator circuit D, a second voltage comparator circuit E, a second controllable switch circuit F and a relay automatic switching circuit G connected in sequence, wherein the power input circuit A is further connected to the first voltage comparator circuit D and the second voltage comparator circuit E; the first controllable switch circuit C is further connected to the second voltage comparator circuit E, the second controllable switch circuit F and the relay automatic switching circuit G; the first voltage comparator circuit D is further connected to the second controllable switch circuit F; The first controllable switch circuit C is provided with a bidirectional TVS tube ZD1, a first chip capacitor C1, a first controllable switch transistor Q2 and a fourth diode D4. Among them, one end of the bidirectional TVS tube ZD1 is connected to the self-recovery fuse FS1 and the other end is connected to GND. The other end of the self-recovery fuse FS1 is connected to the cathode of the first diode D1 and the second diode D2. The two pins of the first chip capacitor C1 are respectively connected to the two pins of the bidirectional TVS tube ZD1 to play a filtering role. Finally, 12V is output to the subsequent circuit to provide working power. voltage, the first chip capacitor C1 and the bidirectional TVS tube ZD1 are connected to the common end, which is then connected in series with the ninth chip resistor R10 and then to the base pin 1 of the first controllable switch transistor Q2. The emitter pin 2 of the first controllable switch transistor Q2 is connected to the second controllable switch circuit F. The collector pin 3 of the first controllable switch transistor Q2 is connected to the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the first voltage comparator circuit D. The ninth chip resistor R10 is connected to 12V to provide a driving voltage to the first controllable switch transistor Q2. The first voltage comparator circuit D is provided with a first voltage comparator U1A. The third chip resistor R3 is connected in series to the non-inverting input terminal 3 of the first voltage comparator U1A. The other end of the third chip resistor R3 is connected to the 12V of the first controllable switch circuit C. The common connection terminal 3 of the third chip resistor R3 and the first voltage comparator U1A serves as the reference voltage V of the voltage comparator. ref The two ends of the third chip capacitor C3 are connected to the common connection terminal 3 of the first voltage comparator U1A and GND respectively. The common connection terminal of the reverse input terminal 2 of the first voltage comparator U1A and the positive electrode of the fourth diode D4 is connected to one end of the fourth chip resistor R4 and one end of the fifth chip resistor R5, and the voltage of this common connection terminal is the voltage to be compared V f , the other end of the fourth chip resistor R4 is connected to pin 1 of the first power supply 48VA+, the other end of the fifth chip resistor R5 is connected in series with the eighth chip resistor R8 and then connected to GND, the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A is connected to the 12V of the first controllable switch circuit C to power the first voltage comparator U1A, the two pins of the second chip capacitor C2 are respectively connected to the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A and the GND ground terminal pin 4, the GND ground terminal pin 4 of the first voltage comparator U1A is connected to GND, the two ends of the tenth resistor R11 are respectively connected to the Vcc power supply voltage terminal pin 8 of the first voltage comparator U1A and the output terminal pin 1 of the first voltage comparator U1A, the output terminal pin 1 of the first voltage comparator U1A and the common connection end of the tenth chip resistor R11 are connected to the second controllable switch circuit F; The second voltage comparator circuit E is provided with a second voltage comparator U1B, and the non-inverting input terminal 5 pin of the second voltage comparator U1B is connected in series with the sixth chip resistor R6, and the other end of the sixth chip resistor R6 is connected to the 12V of the first controllable switch circuit C, and the Vcc power supply voltage terminal 8 pin of the second voltage comparator U1B is connected to the 12V of the first controllable switch circuit C to power the second voltage comparator U1B, and the two ends of the fourth chip capacitor C4 are respectively connected to the non-inverting input terminal 5 pin of the second voltage comparator U1B and GND, which is used to ensure that the 12V voltage response time is slower than 48V and the comparator logic level output is normal, the reverse input terminal 6 pin of the second voltage comparator U1B is connected to one end of the seventh chip resistor R7, and the other end of the seventh chip resistor R7 is connected to the 1 pin 48VB+ of the second power supply, and the common connection end of the seventh chip resistor R7 and the reverse input terminal 6 pin of the second voltage comparator U1B is connected to the 2 pin of the first voltage comparator U1A, and the output terminal 7 pin of the second voltage comparator U1B is connected to the second controllable switch circuit F; The second controllable switch circuit F is provided with a second controllable switch transistor Q3, and the base pin 1 of the second controllable switch transistor Q3 is connected to the output pin 1 of the first voltage comparator U1A in the first voltage comparator circuit D, the common connection terminal of the tenth chip resistor R11, and the output pin 7 of the second voltage comparator U1B, the emitter pin 2 of the second controllable switch transistor Q3 is grounded, and the collector pin 3 of the second controllable switch transistor Q3 is connected to the emitter pin 2 of the first controllable switch transistor Q2 of the first controllable switch circuit C; The relay automatic switching circuit G is provided with a double relay K1 and a third diode D3 as an automatic switching switch for converting hot redundancy into cold redundancy. Pin 1 of the inductor coil inside the double relay K1 is connected to the 12V of the first controllable switch circuit C and the negative electrode of the third diode D3. Pin 2 of the inductor coil inside the double relay K1 is connected to the positive electrode of the third diode D3 and the collector pin 3 of the second controllable switch transistor Q3. The third diode D3 is used to form a loop discharge for the inductor coil between pin 1 and pin 2 inside K1 to prevent the instantaneous high-voltage discharge of the inductor from causing the second controllable switch transistor Q 3. Cause damage. Pin 5 of the inductor coil inside the dual relay K1 is connected to pin 1 of the first power supply (48VA+). Pin 6 of the inductor coil inside the dual relay K1 is connected to the disposable fuse FS2 and then to pin 1 of the second power supply (48VB+). When the 48V of one power supply is short-circuited, the large current will melt the second fuse FS2, separating the short-circuited power supply from the other normally working power supply, thereby avoiding affecting the other normally working power supply. Pins 7 and 8 of the inductor coil inside the dual relay K1 are normally open contacts and are short-circuited, and pins 3 and 4 are normally closed contacts and are left floating. When both power supplies are normal, the comparator outputs a low level, and the switch tube Q3 pin 1 has no voltage and does not operate. Then, the inductor coil inside the relay K1 has no current and does not operate. It is in the normally closed contact state, that is, the 5th and 3rd pins of K1 are short-circuited, and the 6th and 4th pins are short-circuited. The two power supply output ends are separated and loaded separately, thereby switching the hot redundancy to cold redundancy and putting the two power supplies in cold standby state. When one of the power supplies fails and no 48V voltage is output, the voltage at the inverting input terminal of the comparator will be lower than the voltage at the same-direction input terminal. The comparator will then output a high level, and pins 3 and 2 of the switch tube Q3 will be connected to ground. The relay will then switch to the normally open contact, switching the load of the faulty power supply to the output load terminal of the normal power supply, thereby achieving redundancy.

2. The automatic switching circuit for hot redundant to cold redundant backup power supply according to claim 1, characterized in that: The power input circuit A includes a first power supply and a second power supply of the same structure connected in parallel. The first power supply and the second power supply are both provided with 4 pin terminals, wherein the 1-pin terminal of the first power supply is connected to 48VA+, the 1-pin terminal of the second power supply is connected to 48VB+, the 3-pin terminal of the first power supply is connected to 12VA+, the 3-pin terminal of the second power supply is connected to 12VB+, and the 4-pin terminals of the first power supply and the second power supply are both connected to the common ground GND.

3. The automatic switching circuit for hot redundant to cold redundant backup power supply according to claim 1, characterized in that: The 12V redundancy circuit B includes four parallel resistors, a first chip resistor R1, a second chip resistor R2, an eleventh chip resistor R12, and a twelfth chip resistor R13, and a first diode D1 and a second diode D2. The positive electrode of the first diode D1 is connected to the 3-pin terminal of the first power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13; the positive electrode of the second diode D2 is connected to the 3-pin terminal of the second power supply and then connected in parallel with the first chip resistor R1, the second chip resistor R2, the eleventh chip resistor R12, and the twelfth chip resistor R13. The cathodes of the first diode D1 and the second diode D2 are connected and connected to the first controllable switch circuit C. When the 12V of one power supply is short-circuited to GND, it will not affect the normal working power supply of the other power supply, thereby avoiding the short circuit of the 12V of one power supply affecting the 12V of the other power supply. At the same time, the faulty power supply can operate normally with a 12V voltage when there is no short circuit.

4. The automatic switching circuit for hot redundant to cold redundant backup power supply according to claim 1, characterized in that: Pin 2 of the inverting input of the first voltage comparator U1A is connected to pin 6 of the inverting input of the second voltage comparator U1B, and then connected to pin 3 of the first controllable switch transistor Q2 through a fourth diode D4. Pin 2 of the first controllable switch transistor Q2 is connected to pin 3 of the second controllable switch transistor Q3, and pin 2 of the second controllable switch transistor Q3 is grounded. When one of the power supplies fails and there is no 48V output or the power supply voltage output is abnormally low, the second controllable switch transistor Q3 is activated, causing pins 3 and 2 to be connected to ground. At this time, pin 2 of the first controllable switch transistor Q2 is connected to ground through the second controllable switch transistor Q3, and the inverting inputs of the two comparators are grounded, so that the voltage at the non-inverting input of the comparator is always greater than the voltage at the inverting input, and the comparator is always in a high-level output state. The relay will always be in a normally open contact state. At this time, the circuit is in a latched state, and the comparator will not re-compare the voltage until the power supply is turned off and then powered on again.

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