Alternating current and direct current dual power supply automatic switching circuit

Abstract

The utility model discloses an AC / DC dual power supply automatic switching circuit comprising an AC input circuit, a DC input circuit, an input detection circuit, a multipath silicon controlled rectifier switching circuit, a control circuit, and a power supply output circuit. The alternating current input circuit and the direct current input circuit are connected with the power output circuit through the multi-channel silicon controlled rectifier switching circuit; the multi-channel silicon controlled rectifier switching circuit controls whether the alternating current input circuit and the direct current input circuit are connected with the power output circuit or not; the control circuit is connected with the AC input circuit through the input detection circuit. The input detection circuit is used for detecting whether AC input exists in the AC input circuit. The control circuit is further connected with the multi-channel silicon controlled rectifier switching circuit and controls the on-off state of the multi-channel silicon controlled rectifier switching circuit. The switch has the advantages of being small in size, fast in switching and free of sparks during switching.

Description

Technical Field

[0001] The utility model relates to the field of emergency lighting, in particular to an AC / DC dual power automatic switching circuit. Background Art

[0002] With the development of society, people have higher and higher requirements for the reliability of lighting equipment power supply; therefore, in many occasions (such as hospitals, shopping malls, banks, civil air defense, chemical industry, metallurgy, high-rise buildings and military facilities), two power supplies, mains power and emergency power supply, are used to ensure the reliability of lighting equipment power supply; when the mains power is normal, the mains power supplies the lighting equipment; and when the mains power is cut off unexpectedly or due to maintenance, the emergency power supply supplies the lighting equipment. The existing emergency power supply is generally a DC power supply, so the current AC / DC dual power supply switching circuit is used to realize the switching between the mains power supply and the emergency power supply.

[0003] Existing AC / DC dual power switching circuits basically use relays as switching devices, but relays have the disadvantages of large size, slow switching speed, and arcing during switching; and many existing AC / DC dual power switching circuits cannot automatically switch to AC power supply when the AC power returns to normal.

[0004] In view of the existence of the above problems, it is necessary to study an AC / DC dual power automatic switching circuit, which has the advantages of small size, fast switching and no sparks during switching. Utility Model Content

[0005] The utility model aims to provide an AC / DC dual power automatic switching circuit, which has the advantages of small size, fast switching and no sparks during switching.

[0006] In order to achieve the above purpose, the solution of the utility model is:

[0007] An AC / DC dual power automatic switching circuit comprises an AC input circuit, a DC input circuit, an input detection circuit, a multi-channel thyristor switching circuit, a control circuit, and a power output circuit; the AC input circuit and the DC input circuit are connected to the power output circuit via the multi-channel thyristor switching circuit, and the multi-channel thyristor switching circuit controls whether the AC input circuit and the DC input circuit are connected to the power output circuit; the control circuit is connected to the AC input circuit via the input detection circuit, and the input detection circuit is used to detect whether the AC input circuit has AC input; the control circuit is also connected to the multi-channel thyristor switching circuit, and the control circuit controls the switch state of the multi-channel thyristor switching circuit.

[0008] The multi-channel thyristor switching circuit includes a first thyristor switch circuit, a second thyristor switch circuit, a third thyristor switch circuit and a fourth thyristor switch circuit, wherein the input end of the first thyristor switch circuit is connected to the live wire end of the AC input circuit, and the output end of the first thyristor switch circuit is connected to the first power supply end of the power output circuit; the input end of the second thyristor switch circuit is connected to the neutral wire end of the AC input circuit, and the output end of the second thyristor switch circuit is connected to the second power supply end of the power output circuit; the input end of the third thyristor switch circuit is connected to the positive terminal of the DC input circuit, and the output end of the third thyristor switch circuit is connected to the first power supply end of the power output circuit; the input end of the fourth thyristor switch circuit is connected to the negative terminal of the DC input circuit, and the output end of the fourth thyristor switch circuit is connected to the second power supply end of the power output circuit; the control end of the first thyristor switch circuit, the control end of the second thyristor switch circuit, the control end of the third thyristor switch circuit and the control end of the fourth thyristor switch circuit are respectively connected to the control circuit.

[0009] The input end of the fourth thyristor switch circuit is connected to the negative terminal of the DC input circuit through an overcurrent protection circuit.

[0010] The overcurrent protection circuit includes a voltage comparison circuit, a current sampling circuit, a threshold voltage circuit, and an overcurrent electronic switch circuit; the first input end of the voltage comparison circuit is connected to the threshold voltage circuit, the second input end of the voltage comparison circuit is connected to the positive end of the DC input circuit through the current sampling circuit, the output end of the voltage comparison circuit is connected to the control end of the overcurrent electronic switch circuit, the input end of the overcurrent electronic switch circuit is connected to the negative end of the DC input circuit, and the output end of the overcurrent electronic switch circuit is connected to the input end of the fourth thyristor switch circuit.

[0011] The overcurrent electronic switch circuit includes a resistor R22, a resistor R23, a resistor R24, a MOS tube Q3, a transistor Q4 and an optical coupler U6; the first end of the resistor R22 and the source of the MOS tube Q3 are connected to the input end of the overcurrent electronic switch circuit, the drain of the MOS tube Q3 is connected to the output end of the overcurrent electronic switch circuit, the gate of the MOS tube Q3 is connected to the second end of the resistor R22, the first end of the resistor R23 and the collector of the transistor Q4, the emitter of the transistor Q4 is grounded, the base of the transistor Q4 is connected to the control end of the overcurrent electronic switch circuit, the second end of the resistor R23 is connected to the 2nd pin of the optical coupler U6, the 1st pin of the optical coupler U6 is connected to the power supply VDD, the 4th pin of the optical coupler U6 is connected to the power supply VCC through the resistor R24, and the 3rd pin of the optical coupler U6 is connected to the control circuit.

[0012] The first thyristor switch circuit includes a resistor R4, a resistor R5, a thyristor SCR1 and a thyristor optocoupler U7, wherein pin 1 of the thyristor optocoupler U7 is connected to a power source VCC via the resistor R4, pin 2 of the thyristor optocoupler U7 is connected to a control end of the first thyristor switch circuit, pin 6 of the thyristor optocoupler U7 and a T2 pole of the thyristor SCR1 are connected to an input end of the first thyristor switch circuit, pin 4 of the thyristor optocoupler U7 is connected to a G pole of the thyristor SCR1 via the resistor R5, and a T1 pole of the thyristor SCR1 is connected to an output end of the first thyristor switch circuit; The second thyristor switch circuit includes a resistor R10, a resistor R11, a thyristor SCR3 and a thyristor optocoupler U10, wherein the pin 1 of the thyristor optocoupler U10 is connected to the power supply VCC through the resistor R11, the pin 2 of the thyristor optocoupler U10 is connected to the control end of the second thyristor switch circuit, the pin 6 of the thyristor optocoupler U10 and the T1 pole of the thyristor SCR3 are connected to the input end of the second thyristor switch circuit, the pin 4 of the thyristor optocoupler U10 is connected to the G pole of the thyristor SCR3 through the resistor R10, and the T2 pole of the thyristor SCR3 is connected to the second thyristor switch circuit The output end of the third thyristor switch circuit includes a resistor R6, a resistor R7, a thyristor SCR2 and a thyristor optocoupler U8, wherein the pin 1 of the thyristor optocoupler U8 is connected to the power supply VCC through the resistor R6, the pin 2 of the thyristor optocoupler U8 is connected to the control end of the third thyristor switch circuit, the pin 6 of the thyristor optocoupler U8 and the T2 pole of the thyristor SCR2 are connected to the input end of the third thyristor switch circuit, the pin 4 of the thyristor optocoupler U8 is connected to the G pole of the thyristor SCR2 through the resistor R7, and the T1 pole of the thyristor SCR2 is connected to the output end of the third thyristor switch circuit. Output end; the fourth thyristor switch circuit includes a resistor R9, a resistor R8, a thyristor SCR4 and a thyristor optocoupler U9, pin 1 of the thyristor optocoupler U9 is connected to the power supply VCC through the resistor R9, pin 2 of the thyristor optocoupler U9 is connected to the control end of the fourth thyristor switch circuit, pin 6 of the thyristor optocoupler U9 and the T1 pole of the thyristor SCR4 are connected to the input end of the fourth thyristor switch circuit, pin 4 of the thyristor optocoupler U9 is connected to the G pole of the thyristor SCR4 through the resistor R8, and the T2 pole of the thyristor SCR4 is connected to the output end of the fourth thyristor switch circuit.

[0013] The control circuit includes a first electronic switch circuit, a second electronic switch circuit and an MCU processor U3, a VDD pin of the MCU processor U3 is connected to a power supply VCC, a GND pin of the MCU processor U3 is grounded, a PA2 pin and a PA3 pin of the MCU processor U3 are respectively connected to a control end of the first electronic switch circuit and a control end of the second electronic switch circuit, an input end of the first electronic switch circuit is connected to a control end of the first thyristor switch circuit and a control end of the second thyristor switch circuit, an input end of the second electronic switch circuit is connected to a control end of the third thyristor switch circuit and a control end of the fourth thyristor switch circuit, and an output end of the first electronic switch circuit and an output end of the second electronic switch circuit are grounded.

[0014] The PA4 pin and the PA1 pin of the MCU processor U3 are connected to the input end of the first electronic switch circuit and the input end of the second electronic switch circuit respectively.

[0015] The input detection circuit includes resistors R1, R2, R3 and optocoupler U4, wherein pin 1 of the optocoupler U4 is connected to the live wire end of the AC input circuit through resistors R1 and R2, pin 2 of the optocoupler U4 is connected to the neutral wire end of the AC input circuit, pin 3 of the optocoupler U4 is grounded, pin 4 of the optocoupler U4 is connected to the power supply VCC through resistor R3, and pin 4 of the optocoupler U4 is also connected to the control circuit.

[0016] The AC / DC dual power automatic switching circuit also includes an output detection circuit, and the control circuit is connected to the power output circuit through the output detection circuit; the output detection circuit includes a resistor R14, a resistor R15, a resistor R16 and an optical coupler U5, and pin 1 of the optical coupler U5 is connected to the first power supply end of the power output circuit through the resistor R14 and the resistor R15, and pin 2 of the optical coupler U5 is connected to the second power supply end of the power output circuit, and pin 3 of the optical coupler U5 is grounded, and pin 4 of the optical coupler U5 is connected to the power supply VCC through the resistor R16, and pin 4 of the optical coupler U5 is also connected to the control circuit.

[0017] After adopting the above scheme, the utility model has the following characteristics:

[0018] 1. When the AC / DC dual power automatic switching circuit of the utility model is in use, the AC input circuit is connected to the mains (i.e., AC power), the DC input circuit is connected to the emergency power supply (i.e., DC power), and the power output circuit is connected to the lighting equipment; wherein, when the control circuit detects that the AC input circuit has AC input through the input detection circuit (i.e., when the mains power supply is normal), the control circuit controls the AC input circuit to be connected to the power output circuit and the DC input circuit to be disconnected from the power output circuit through the multi-way thyristor switching circuit, and the lighting equipment is powered by the mains; and when the control circuit detects that the AC input circuit has no AC input through the input detection circuit (i.e., when the mains power supply is abnormal), the control circuit controls the DC input circuit to be connected to the power output circuit and the AC input circuit to be disconnected from the power output circuit through the multi-way thyristor switching circuit, and the lighting equipment is powered by the emergency power supply. wherein, the utility model adopts a multi-way thyristor switching circuit to replace the existing relay to control whether the AC input circuit and the DC input circuit are connected to the power output circuit, and the multi-way thyristor switching circuit has the advantages of smaller size, faster switching speed, and no sparks during switching compared to the existing relays;

[0019] 2. The utility model can cut off the connection between the power output circuit and the DC input circuit through the overcurrent protection circuit when an overcurrent problem occurs in the emergency power supply connected to the DC input circuit, thereby playing an overcurrent protection role. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a circuit schematic diagram of the utility model. DETAILED DESCRIPTION

[0021] In order to further explain the technical solution of the present utility model, the present utility model is described in detail below through specific embodiments.

[0022] like Figure 1 As shown, the utility model discloses an AC / DC dual power automatic switching circuit, which includes an AC input circuit, a DC input circuit, an input detection circuit, a multi-way thyristor switching circuit, a control circuit, and a power output circuit; wherein the AC input circuit and the DC input circuit are connected to the power output circuit through the multi-way thyristor switching circuit, and the multi-way thyristor switching circuit controls whether the AC input circuit and the DC input circuit are connected to the power output circuit; the control circuit is connected to the AC input circuit through the input detection circuit, and the input detection circuit is used to detect whether the AC input circuit has AC input; the control circuit is also connected to the multi-way thyristor switching circuit, and the control circuit controls the switching state of the multi-way thyristor switching circuit.

[0023] The utility model is an AC / DC dual power automatic switching circuit. When in use, the AC input circuit is connected to the mains (i.e., AC power), the DC input circuit is connected to the emergency power supply (i.e., DC power), and the power output circuit is connected to the lighting device; wherein, when the control circuit detects that the AC input circuit has AC input through the input detection circuit (i.e., when the mains power supply is normal), the control circuit controls the AC input circuit to be connected to the power output circuit and the DC input circuit to be disconnected from the power output circuit through the multi-way thyristor switching circuit, and the lighting device is powered by the mains; and when the control circuit detects that the AC input circuit has no AC input through the input detection circuit (i.e., when the mains power supply is abnormal), the control circuit controls the DC input circuit to be connected to the power output circuit and the AC input circuit to be disconnected from the power output circuit through the multi-way thyristor switching circuit, and the lighting device is powered by the emergency power supply. wherein, the utility model adopts a multi-way thyristor switching circuit to replace the existing relay to control whether the AC input circuit and the DC input circuit are connected to the power output circuit, and the multi-way thyristor switching circuit has the advantages of smaller size, faster switching speed, and no sparks when switching compared to the existing relay.

[0024] In an embodiment of the utility model, the AC input circuit includes a live wire terminal J1 and a neutral wire terminal J2; the DC input circuit includes a positive terminal J5 and a negative terminal J6; the power output circuit includes a first output terminal J3 and a second output terminal J4, and the multi-channel thyristor switching circuit includes a first thyristor switch circuit, a second thyristor switch circuit, a third thyristor switch circuit and a fourth thyristor switch circuit, the input end of the first thyristor switch circuit is connected to the live wire end of the AC input circuit (i.e., the live wire terminal J1), the output end of the first thyristor switch circuit is connected to the first power supply end of the power output circuit (i.e., the first output terminal J3), the input end of the second thyristor switch circuit is connected to the neutral wire end of the AC input circuit (i.e., the neutral wire terminal J2), and the output end of the second thyristor switch circuit is connected to the power output circuit. The input end of the third thyristor switch circuit is connected to the positive end of the DC input circuit (i.e., the positive terminal J5), the output end of the third thyristor switch circuit is connected to the first power end of the power output circuit (i.e., the first output terminal J3), the input end of the fourth thyristor switch circuit is connected to the negative end of the DC input circuit (i.e., the negative terminal J6), the output end of the fourth thyristor switch circuit is connected to the second power end of the power output circuit (i.e., the second output terminal J4), the control end of the first thyristor switch circuit, the control end of the second thyristor switch circuit, the control end of the third thyristor switch circuit and the control end of the fourth thyristor switch circuit are respectively connected to the control circuit, and the control circuit controls the on and off of the first thyristor switch circuit, the second thyristor switch circuit, the third thyristor switch circuit and the fourth thyristor switch circuit.

[0025] In an embodiment of the utility model, the first thyristor switch circuit includes a resistor R4, a resistor R5, a thyristor SCR1 and a thyristor optocoupler U7, wherein the pin 1 of the thyristor optocoupler U7 is connected to the power supply VCC through the resistor R4, the pin 2 of the thyristor optocoupler U7 is connected to the control end of the first thyristor switch circuit, the pin 6 of the thyristor optocoupler U7 and the T2 pole of the thyristor SCR1 are connected to the input end of the first thyristor switch circuit, the pin 4 of the thyristor optocoupler U7 is connected to the G pole of the thyristor SCR1 through the resistor R5, and the T1 pole of the thyristor SCR1 is connected to the first thyristor switch The output end of the circuit; the second thyristor switch circuit includes a resistor R10, a resistor R11, a thyristor SCR3 and a thyristor optocoupler U10, pin 1 of the thyristor optocoupler U10 is connected to the power supply VCC through the resistor R11, pin 2 of the thyristor optocoupler U10 is connected to the control end of the second thyristor switch circuit, pin 6 of the thyristor optocoupler U10 and the T1 pole of the thyristor SCR3 are connected to the input end of the second thyristor switch circuit, pin 4 of the thyristor optocoupler U10 is connected to the G pole of the thyristor SCR3 through the resistor R10, and the T2 pole of the thyristor SCR3 is connected to the second thyristor The output end of the thyristor switch circuit; the third thyristor switch circuit includes a resistor R6, a resistor R7, a thyristor SCR2 and a thyristor optocoupler U8, wherein the pin 1 of the thyristor optocoupler U8 is connected to the power supply VCC through the resistor R6, the pin 2 of the thyristor optocoupler U8 is connected to the control end of the third thyristor switch circuit, the pin 6 of the thyristor optocoupler U8 and the T2 pole of the thyristor SCR2 are connected to the input end of the third thyristor switch circuit, the pin 4 of the thyristor optocoupler U8 is connected to the G pole of the thyristor SCR2 through the resistor R7, and the T1 pole of the thyristor SCR2 is connected to the third thyristor switch circuit The output end of the fourth thyristor switch circuit includes a resistor R9, a resistor R8, a thyristor SCR4 and a thyristor optocoupler U9, pin 1 of the thyristor optocoupler U9 is connected to the power supply VCC through the resistor R9, pin 2 of the thyristor optocoupler U9 is connected to the control end of the fourth thyristor switch circuit, pin 6 of the thyristor optocoupler U9 and the T1 pole of the thyristor SCR4 are connected to the input end of the fourth thyristor switch circuit, pin 4 of the thyristor optocoupler U9 is connected to the G pole of the thyristor SCR4 through the resistor R8, and the T2 pole of the thyristor SCR4 is connected to the output end of the fourth thyristor switch circuit.

[0026] In an embodiment of the utility model, the control circuit may include a first electronic switch circuit, a second electronic switch circuit and an MCU processor U3, a VDD pin of the MCU processor U3 is connected to a power supply VCC, a GND pin of the MCU processor U3 is grounded, a PA2 pin and a PA3 pin of the MCU processor U3 are respectively connected to a control end of the first electronic switch circuit and a control end of the second electronic switch circuit, an input end of the first electronic switch circuit is connected to a control end of a first thyristor switch circuit and a control end of a second thyristor switch circuit, an input end of the second electronic switch circuit is connected to a control end of a third thyristor switch circuit and a control end of a fourth thyristor switch circuit, and an output end of the first electronic switch circuit and an output end of the second electronic switch circuit are grounded; When the MCU processor U3 controls the first electronic switch to turn on, the optocoupler thyristor U7 and the optocoupler thyristor U10 are turned on accordingly, so that the thyristor SCR1 and the thyristor SCR3 are turned on accordingly, thereby turning on the first thyristor switch circuit and the second thyristor switch circuit, so that the AC input circuit is connected to the power output circuit; when the MCU processor U3 controls the second electronic switch to turn on, the optocoupler thyristor U8 and the optocoupler thyristor U9 are turned on accordingly, so that the thyristor SCR2 and the thyristor SCR4 are turned on accordingly, thereby turning on the third thyristor switch circuit and the fourth thyristor switch circuit, so that the DC input circuit is connected to the power output circuit; the first electronic switch circuit and the second electronic switch circuit can adopt transistor switch circuits. In addition, the PA4 pin and the PA1 pin of the MCU processor U3 can be connected to the input end of the first electronic switch circuit and the input end of the second electronic switch circuit respectively, so that the MCU processor U3 can obtain the input end level of the first electronic switch circuit and the input end level of the second electronic switch circuit, and then judge the switching state of the first thyristor switch circuit, the second thyristor switch circuit, the third thyristor switch circuit and the fourth thyristor switch circuit, so as to judge the connection state of the AC input circuit and the DC input circuit with the power output circuit. In this way, the utility model can control the DC input circuit to be connected with the power output circuit only after the AC input circuit is disconnected from the power output circuit, and control the AC input circuit to be connected with the power output circuit only after the DC input circuit is disconnected from the power output circuit, so as to ensure the safety of power switching.

[0027] In an embodiment of the utility model, the input end of the fourth thyristor switch circuit can be connected to the negative end of the DC input circuit through an overcurrent protection circuit. The overcurrent protection circuit can cut off the connection between the fourth thyristor switch circuit and the DC input circuit (i.e., cut off the connection between the power supply output circuit and the DC input circuit) when an overcurrent problem occurs in the emergency power supply connected to the DC input circuit, thereby playing an overcurrent protection role. Specifically, the overcurrent protection circuit includes a voltage comparison circuit, a current sampling circuit, a threshold voltage circuit and an overcurrent electronic switch circuit. The first input end of the voltage comparison circuit is connected to the threshold voltage circuit, the second input end of the voltage comparison circuit is connected to the positive end of the DC input circuit through the current sampling circuit, the output end of the voltage comparison circuit is connected to the control end of the overcurrent electronic switch circuit, the input end of the overcurrent electronic switch circuit is connected to the negative end of the DC input circuit, and the output end of the overcurrent electronic switch circuit is connected to the input end of the fourth thyristor switch circuit; when the emergency power supply connected to the DC input circuit has an overcurrent problem, the output voltage of the current sampling circuit will be greater than the output voltage of the threshold voltage circuit, so that the output level of the voltage comparison circuit controls the overcurrent electronic switch circuit to disconnect, thereby cutting off the connection between the fourth thyristor switch circuit and the DC input circuit, thereby playing an overcurrent protection role. The overcurrent electronic switch circuit may include a resistor R22, a resistor R23, a resistor R24, a MOS tube Q3, a transistor Q4 and an optical coupler U6, wherein a first end of the resistor R22 and a source of the MOS tube Q3 are connected to an input end of the overcurrent electronic switch circuit, and the input end of the overcurrent electronic switch circuit may be connected to a negative end of a DC input circuit through a resistor R21, a drain of the MOS tube Q3 is connected to an output end of the overcurrent electronic switch circuit, a gate of the MOS tube Q3 is connected to a second end of the resistor R22, a first end of the resistor R23 and a collector of the transistor Q4, an emitter of the transistor Q4 is grounded, a base of the transistor Q4 is connected to a control end of the overcurrent electronic switch circuit, and a second end of the resistor R23 is connected to a Pin 2 of the optocoupler U6 is connected, Pin 1 of the optocoupler U6 is connected to the power supply VDD, Pin 4 of the optocoupler U6 is connected to the power supply VCC through the resistor R24, and Pin 3 of the optocoupler U6 is connected to the control circuit (i.e., Pin PA1 of the MCU processor U3); when the emergency power supply connected to the DC input circuit has an overcurrent problem, the voltage comparison circuit outputs a high level to the transistor Q4 to control the transistor Q4 to turn on, the transistor Q4 turns on and the MOS tube Q3 turns off and cuts off the connection between the fourth thyristor switch circuit and the DC input circuit, the transistor Q4 turns on and the pin 3 of the optocoupler U6 outputs a high level signal to the control circuit, so that the control circuit knows that the emergency power supply connected to the DC input circuit has an overcurrent problem. The power supplies VCC and VDD can be provided by the control power circuit.

[0028] In an embodiment of the utility model, the input detection circuit includes a resistor R1, a resistor R2, a resistor R3 and an optocoupler U4, wherein pin 1 of the optocoupler U4 is connected to the live wire end of the AC input circuit through the resistors R1 and R2, pin 2 of the optocoupler U4 is connected to the neutral wire end of the AC input circuit, pin 3 of the optocoupler U4 is grounded, pin 4 of the optocoupler U4 is connected to the power supply VCC through the resistor R3, and pin 4 of the optocoupler U4 is also connected to the control circuit (i.e., pin PA0 of the MCU processor U3); when the AC input circuit has AC input (i.e., when the mains power supply is normal), pins 3 and 4 of the optocoupler U4 are turned on, so that pin 4 of the optocoupler U4 outputs a low-level signal to the control circuit, so that the control circuit knows that the AC input circuit has AC input; when the AC input circuit has no AC input (i.e., when the mains power supply is abnormal), pins 3 and 4 of the optocoupler U4 are disconnected, so that pin 4 of the optocoupler U4 outputs a high-level signal to the control circuit, so that the control circuit knows that the AC input circuit has no AC input.

[0029] In an embodiment of the utility model, an AC / DC dual power automatic switching circuit of the utility model further includes an output detection circuit, and the control circuit is connected to the power output circuit through the output detection circuit, and the control circuit can detect whether the power output circuit has power output through the output detection circuit. Specifically, the output detection circuit includes a resistor R14, a resistor R15, a resistor R16 and an optocoupler U5, and pin 1 of the optocoupler U5 is connected to the first power supply end of the power output circuit through resistors R14 and R15, and pin 2 of the optocoupler U5 is connected to the second power supply end of the power output circuit, and pin 3 of the optocoupler U5 is grounded, and pin 4 of the optocoupler U5 is connected to the power supply VCC through resistor R16, and pin 4 of the optocoupler U5 is also connected to the control circuit (i.e., pin PA5 of the MCU processor U3). When the power output circuit has power output, pins 3 and 4 of the optocoupler U5 are turned on, causing pin 4 of the optocoupler U5 to output a low-level signal to the control circuit, so that the control circuit knows that the power output circuit has power output; when the power output circuit has power output, pins 3 and 4 of the optocoupler U5 are turned off, causing pin 4 of the optocoupler U5 to output a high-level signal to the control circuit, so that the control circuit knows that the power output circuit has no power output.

[0030] The above embodiments and drawings do not limit the product form and style of the present utility model. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present utility model.

Claims

1. An AC / DC dual power automatic switching circuit, characterized in that: It includes an AC input circuit, a DC input circuit, an input detection circuit, a multi-channel thyristor switching circuit, a control circuit, and a power output circuit; The AC input circuit and the DC input circuit are connected to the power output circuit through a multi-way thyristor switching circuit, and the multi-way thyristor switching circuit controls whether the AC input circuit and the DC input circuit are connected to the power output circuit; The control circuit is connected to the AC input circuit through an input detection circuit, and the input detection circuit is used to detect whether the AC input circuit has AC input; the control circuit is also connected to a multi-channel thyristor switching circuit, and the control circuit controls the switching state of the multi-channel thyristor switching circuit.

2. The AC / DC dual power automatic switching circuit according to claim 1, characterized in that: The multi-channel thyristor switching circuit includes a first thyristor switch circuit, a second thyristor switch circuit, a third thyristor switch circuit and a fourth thyristor switch circuit. The input end of the first thyristor switch circuit is connected to the live wire end of the AC input circuit, and the output end of the first thyristor switch circuit is connected to the first power supply end of the power output circuit; the input end of the second thyristor switch circuit is connected to the neutral wire end of the AC input circuit, and the output end of the second thyristor switch circuit is connected to the second power supply end of the power output circuit; the input end of the third thyristor switch circuit is connected to the positive terminal of the DC input circuit, and the output end of the third thyristor switch circuit is connected to the first power supply end of the power output circuit; the input end of the fourth thyristor switch circuit is connected to the negative terminal of the DC input circuit, and the output end of the fourth thyristor switch circuit is connected to the second power supply end of the power output circuit; the control end of the first thyristor switch circuit, the control end of the second thyristor switch circuit, the control end of the third thyristor switch circuit and the control end of the fourth thyristor switch circuit are respectively connected to the control circuit.

3. The AC / DC dual power automatic switching circuit as claimed in claim 2, characterized in that: The input end of the fourth thyristor switch circuit is connected to the negative terminal of the DC input circuit through an overcurrent protection circuit.

4. The AC / DC dual power automatic switching circuit as claimed in claim 3, characterized in that: The overcurrent protection circuit includes a voltage comparison circuit, a current sampling circuit, a threshold voltage circuit, and an overcurrent electronic switch circuit; The first input end of the voltage comparison circuit is connected to the threshold voltage circuit, the second input end of the voltage comparison circuit is connected to the positive end of the DC input circuit through the current sampling circuit, the output end of the voltage comparison circuit is connected to the control end of the overcurrent electronic switch circuit, the input end of the overcurrent electronic switch circuit is connected to the negative end of the DC input circuit, and the output end of the overcurrent electronic switch circuit is connected to the input end of the fourth thyristor switch circuit.

5. The AC / DC dual power automatic switching circuit as claimed in claim 4, characterized in that: The overcurrent electronic switch circuit includes a resistor R22, a resistor R23, a resistor R24, a MOS tube Q3, a transistor Q4 and an optical coupler U6; the first end of the resistor R22 and the source of the MOS tube Q3 are connected to the input end of the overcurrent electronic switch circuit, the drain of the MOS tube Q3 is connected to the output end of the overcurrent electronic switch circuit, the gate of the MOS tube Q3 is connected to the second end of the resistor R22, the first end of the resistor R23 and the collector of the transistor Q4, the emitter of the transistor Q4 is grounded, the base of the transistor Q4 is connected to the control end of the overcurrent electronic switch circuit, the second end of the resistor R23 is connected to the 2nd pin of the optical coupler U6, the 1st pin of the optical coupler U6 is connected to the power supply VDD, the 4th pin of the optical coupler U6 is connected to the power supply VCC through the resistor R24, and the 3rd pin of the optical coupler U6 is connected to the control circuit.

6. The AC / DC dual power automatic switching circuit as claimed in claim 2, characterized in that: The first thyristor switch circuit includes a resistor R4, a resistor R5, a thyristor SCR1 and a thyristor optocoupler U7, wherein pin 1 of the thyristor optocoupler U7 is connected to a power source VCC via the resistor R4, pin 2 of the thyristor optocoupler U7 is connected to a control end of the first thyristor switch circuit, pin 6 of the thyristor optocoupler U7 and a T2 pole of the thyristor SCR1 are connected to an input end of the first thyristor switch circuit, pin 4 of the thyristor optocoupler U7 is connected to a G pole of the thyristor SCR1 via the resistor R5, and a T1 pole of the thyristor SCR1 is connected to an output end of the first thyristor switch circuit; The second thyristor switch circuit includes a resistor R10, a resistor R11, a thyristor SCR3 and a thyristor optocoupler U10, wherein the pin 1 of the thyristor optocoupler U10 is connected to the power supply VCC through the resistor R11, the pin 2 of the thyristor optocoupler U10 is connected to the control end of the second thyristor switch circuit, the pin 6 of the thyristor optocoupler U10 and the T1 pole of the thyristor SCR3 are connected to the input end of the second thyristor switch circuit, the pin 4 of the thyristor optocoupler U10 is connected to the G pole of the thyristor SCR3 through the resistor R10, and the T2 pole of the thyristor SCR3 is connected to the second thyristor switch circuit The output end of the third thyristor switch circuit includes a resistor R6, a resistor R7, a thyristor SCR2 and a thyristor optocoupler U8, wherein the pin 1 of the thyristor optocoupler U8 is connected to the power supply VCC through the resistor R6, the pin 2 of the thyristor optocoupler U8 is connected to the control end of the third thyristor switch circuit, the pin 6 of the thyristor optocoupler U8 and the T2 pole of the thyristor SCR2 are connected to the input end of the third thyristor switch circuit, the pin 4 of the thyristor optocoupler U8 is connected to the G pole of the thyristor SCR2 through the resistor R7, and the T1 pole of the thyristor SCR2 is connected to the output end of the third thyristor switch circuit. Output end; the fourth thyristor switch circuit includes a resistor R9, a resistor R8, a thyristor SCR4 and a thyristor optocoupler U9, pin 1 of the thyristor optocoupler U9 is connected to the power supply VCC through the resistor R9, pin 2 of the thyristor optocoupler U9 is connected to the control end of the fourth thyristor switch circuit, pin 6 of the thyristor optocoupler U9 and the T1 pole of the thyristor SCR4 are connected to the input end of the fourth thyristor switch circuit, pin 4 of the thyristor optocoupler U9 is connected to the G pole of the thyristor SCR4 through the resistor R8, and the T2 pole of the thyristor SCR4 is connected to the output end of the fourth thyristor switch circuit.

7. The AC / DC dual power automatic switching circuit according to claim 6, characterized in that: The control circuit includes a first electronic switch circuit, a second electronic switch circuit and an MCU processor U3, a VDD pin of the MCU processor U3 is connected to a power supply VCC, a GND pin of the MCU processor U3 is grounded, a PA2 pin and a PA3 pin of the MCU processor U3 are respectively connected to a control end of the first electronic switch circuit and a control end of the second electronic switch circuit, an input end of the first electronic switch circuit is connected to a control end of the first thyristor switch circuit and a control end of the second thyristor switch circuit, an input end of the second electronic switch circuit is connected to a control end of the third thyristor switch circuit and a control end of the fourth thyristor switch circuit, and an output end of the first electronic switch circuit and an output end of the second electronic switch circuit are grounded.

8. The AC / DC dual power automatic switching circuit as claimed in claim 7, characterized in that: The PA4 pin and the PA1 pin of the MCU processor U3 are connected to the input end of the first electronic switch circuit and the input end of the second electronic switch circuit respectively.

9. The AC / DC dual power automatic switching circuit according to claim 1, characterized in that: The input detection circuit includes resistors R1, R2, R3 and optocoupler U4, wherein pin 1 of the optocoupler U4 is connected to the live wire end of the AC input circuit through resistors R1 and R2, pin 2 of the optocoupler U4 is connected to the neutral wire end of the AC input circuit, pin 3 of the optocoupler U4 is grounded, pin 4 of the optocoupler U4 is connected to the power supply VCC through resistor R3, and pin 4 of the optocoupler U4 is also connected to the control circuit.

10. The AC / DC dual power automatic switching circuit according to claim 1, characterized in that: It also includes an output detection circuit, and the control circuit is connected to the power output circuit through the output detection circuit; the output detection circuit includes resistor R14, resistor R15, resistor R16 and optocoupler U5, pin 1 of the optocoupler U5 is connected to the first power supply end of the power output circuit through resistor R14 and resistor R15, pin 2 of the optocoupler U5 is connected to the second power supply end of the power output circuit, pin 3 of the optocoupler U5 is grounded, pin 4 of the optocoupler U5 is connected to the power supply VCC through resistor R16, and pin 4 of the optocoupler U5 is also connected to the control circuit.

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