An AC overvoltage and undervoltage multiple protection circuit

Abstract

The present invention provides a multi - protection circuit for AC over - voltage and under - voltage, which can ensure that during the switching process between two power sources, namely 220V AC power and 24V battery, functions such as over - voltage protection and under - voltage protection can be achieved, ensuring that the AC power supply can be quickly switched to the DC power supply of the battery to guarantee the normal power supply effect. It includes a power supply circuit, an AC over - voltage / under - voltage protection circuit, a DC over - voltage / under - voltage protection circuit, a self - locking circuit, a timing reset self - locking circuit and a signal control circuit. After the AC over - voltage / under - voltage protection circuit and the DC over - voltage / under - voltage protection circuit are connected, they are respectively connected to the self - locking circuit and the timing reset self - locking circuit, and the self - locking circuit and the timing reset self - locking circuit are then connected to the signal control circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply protection circuits, and particularly to an AC overvoltage and undervoltage multiple protection circuit. Background Art

[0002] At present, network devices, monitoring devices, etc. are all powered by 220V AC power supply. Since if the 220V AC power supply stops, the devices connected thereto will all stop working. To solve this problem, a dual power supply design is generally adopted, that is, one is powered by 220V AC power supply, and the other is powered by a 24V battery. During the process of adopting the dual power supply design, the following situations will occur: when 220V AC power supply and 24V battery are connected at the same time, the 220V AC power supply is given priority to supply power, and at this time, the 24V battery power supply is cut off to reduce the standby loss of the battery; when the 220V AC power supply has abnormal conditions such as overvoltage, undervoltage or power failure during operation, the power supply can quickly switch to the 24V battery power supply to achieve secondary continuous DC power supply output; when the 220V AC power supply resumes normal power supply, the 24V battery works for a few seconds with a delay, and after ensuring that the 220V AC power supply works normally, the 24V battery stops working. Since there will be the above different situations during the use of the dual power supply, it is urgent to provide a protection circuit to ensure that during the switching process of the two power supplies, functions such as overvoltage protection and undervoltage protection can be realized, and it is ensured that the AC power supply can be quickly switched to the battery DC power supply to ensure the normal power supply effect. Summary of the Invention

[0003] Aiming at the problem that a protection circuit needs to be provided during the existing dual power supply process to prevent abnormal power supply, the present invention provides an AC overvoltage and undervoltage multiple protection circuit, which can ensure that during the switching process of the two power supplies of 220V AC power supply and 24V battery, functions such as overvoltage protection and undervoltage protection can be realized, and it is ensured that the AC power supply can be quickly switched to the battery DC power supply to ensure the normal power supply effect.

[0004] Its technical solution is as follows: an AC overvoltage and undervoltage multiple protection circuit, characterized in that: it includes a power supply circuit, an AC overvoltage / undervoltage protection circuit, a DC overvoltage / undervoltage protection circuit, a self-locking circuit, a timing reset self-locking circuit and a signal control circuit, the AC overvoltage / undervoltage protection circuit is connected to the DC overvoltage / undervoltage protection circuit and then respectively connected to the self-locking circuit and the timing reset self-locking circuit, and the self-locking circuit and the timing reset self-locking circuit are further connected to the signal control circuit;

[0005] The input end of the power supply circuit is connected to the AC 220V input voltage and is converted into 5V and 2.5V voltage sources through a voltage regulator;

[0006] The AC overvoltage / undervoltage protection circuit is used to detect whether the AC 220V input voltage is abnormal;

[0007] The DC overvoltage / undervoltage protection circuit is used to detect whether the input voltage of the DC high voltage of 400V is abnormal;

[0008] The self-locking circuit is used to lock the state of the overvoltage and undervoltage protection circuits. The protection circuit is the AC overvoltage / undervoltage protection circuit or the DC overvoltage / undervoltage protection circuit, which facilitates subsequent signal processing by the timing reset self-locking circuit;

[0009] The timing reset self-locking circuit is used to make the self-locking circuit reset at a fixed time during overvoltage and undervoltage;

[0010] The signal control circuit sends a control signal to the external 24V battery power supply circuit according to the conditions of the foregoing respective circuits to control the operation of the 24V battery power supply circuit.

[0011] It is further characterized in that: the power supply circuit includes a voltage regulator U1. The 5th to 8th pins of the voltage regulator U1 are connected and then connected to one end of a resistor R1. The other end of the resistor R1 is connected to the negative electrodes of a diode D1 and a diode D2. The positive electrode of the diode D1 is connected to the negative electrode of a diode D4 and the live wire L1 of the AC 220V input voltage. The positive electrode of the diode D2 is connected to the negative electrode of a diode D5 and the neutral wire N1 of the AC 220V input voltage. The positive electrodes of the diode D4 and the diode D5 are connected and then grounded. The 3rd pin of the voltage regulator U1 is connected to one end of a capacitor C2, one end of a capacitor C3, and one end of a resistor R2 and outputs a 5V voltage source. The other end of the resistor R2 is connected to the 1st and 2nd pins of a zener diode U2 and one end of a capacitor C4 and outputs a 2.5V voltage source. The 4th pin of the voltage regulator U1 is connected to one end of a capacitor C1 and outputs a 7.5V voltage source. The other end of the capacitor C1 is connected to the 2nd pin of the voltage regulator U1, the other end of the capacitor C2, the other end of the capacitor C3, the 3rd pin of the zener diode U2, and the other end of the capacitor C4 and is grounded;

[0012] The AC overvoltage / undervoltage protection circuit includes operational amplifiers U6, U4A, U4B, U5A, and U5B. The non-inverting input terminal 1 of the operational amplifier U6 is connected to one end of the resistor R10, the negative electrode of the voltage regulator diode D7, one end of the resistor R15, and one end of the capacitor C7. The other end of the resistor R10 is sequentially connected to the power supply circuit through the resistor R6 and the resistor 7. The positive electrode of the voltage regulator diode D7, the other end of the resistor R15, and the other end of the capacitor C7 are connected to the 2nd pin of the operational amplifier U6 and then grounded. The inverting input terminal 3 of the operational amplifier U6 is connected to the output terminal 4 and then respectively connected to the inverting input terminal 6 of the operational amplifier U4B and the inverting input terminal 2 of the operational amplifier U4A. The output terminal 7 of the operational amplifier U4B is connected to the non-inverting input terminal 5 of the operational amplifier U5B and one end of the resistor R11. The other end of the resistor R11 is connected to one end of the capacitor C6, the collector of the triode U7B, and the DC overvoltage / undervoltage protection circuit. The emitter of the triode U7B is connected to one end of the resistor R13 and the base of the triode U7A. The other end of the resistor R13 is connected to the negative electrode of the diode D6. The positive electrode of the diode D6 is connected to the emitter of the triode U7A and the 5V voltage source. The collector of the triode U7A is connected to the base of the triode U7B and one end of the resistor R14. The other end of the resistor R14 is connected to the other end of the capacitor C6, the 4th pin of the operational amplifier U4A, and grounded. The 7th pin of the operational amplifier U5B is connected to one end of the resistor R8. The 1st pin of the operational amplifier U5A is connected to one end of the resistor R35 and one end of the resistor R17. The other end of the resistor R35 is connected to the 8th pin of the operational amplifier U5A and then connected to the 5V voltage source. The other end of the resistor R17 is connected to the other end of the resistor R8 and then connected to the self-locking circuit. The non-inverting input terminal 3 of the operational amplifier U4B is connected to one end of the resistor R20, one end of the resistor R23, and one end of the capacitor C8. The other end of the resistor R20 is connected to the 2.5V voltage source. The output terminal 1 of the operational amplifier U4A is connected to the non-inverting input terminal 2 of the operational amplifier U5A and one end of the resistor R21. The other end of the resistor R21 is connected to one end of the capacitor C9 and the collector of the triode U9B. The emitter of the triode U9B is connected to one end of the resistor R22 and the base of the triode U9A. The other end of the resistor R22 is connected to the negative electrode of the diode D10. The positive electrode of the diode D10 is connected to the emitter of the triode U9A and then connected to the 5V voltage source. The collector of the triode U9A is connected to the base of the triode U9B and one end of the resistor R27. The other end of the resistor R27 is connected to the other end of the capacitor C9, the other end of the capacitor C8, and the other end of the resistor R23 and grounded. The non-inverting input terminal 5 of the operational amplifier U4B, the inverting input terminal 6 of the operational amplifier U5B, and the non-inverting input terminal 3 of the operational amplifier U5A are respectively connected to the 2.5V voltage source;

[0013] The DC overvoltage / undervoltage protection circuit includes operational amplifiers U12, U10A, and U10B. The non-inverting input terminal 1 of operational amplifier U12 is connected to one end of capacitor C13, one end of resistor R37, the cathode of diode D12, and one end of resistor R30. The other end of resistor R30 is connected to the 400V voltage source through resistors R28 and R26. The inverting input terminal 3 of operational amplifier U12 is connected to the output terminal 4 and then connected to the inverting input terminal 6 of operational amplifier U10B and the inverting input terminal 3 of operational amplifier U10A. The 2 terminal of operational amplifier U10A is connected to one end of resistor R31, one end of resistor R34, one end of capacitor C12, and the 2.13V voltage source. The other end of resistor R31 is connected to the 2.5V voltage source. The anode of diode D12 is connected to the other end of resistor R37, the other end of capacitor C13, the 2 terminal of operational amplifier U12, the other end of resistor R34, the other end of capacitor C12, and the 4 terminal of operational amplifier U10A and is grounded. The output terminal 7 of operational amplifier U10B is connected to one end of resistor R24. The other end of resistor R24 is connected to the AC overvoltage / undervoltage protection circuit. The output terminal 1 of operational amplifier U10A is connected to one end of resistor R35 and one end of resistor R38. The other end of resistor R35 is connected to the 8 terminal of operational amplifier U10A and the 5V voltage source. The other end of resistor R38 is connected to the self-locking circuit and the timing reset self-locking circuit;

[0014] The self-locking circuit includes transistors Q2 and Q4. The collector of transistor Q4 is connected to one end of resistor R16 and the anode of diode D9B. The cathode of diode D9B is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the timing reset self-locking circuit. The emitter of transistor Q4 is connected to one end of resistor R25 and is grounded. The base of transistor Q4 is connected to one end of resistor R19, the other end of resistor R25, and the timing reset self-locking circuit. The other end of resistor R19 is connected to the collector of transistor Q2 and the signal control circuit. The base of transistor Q2 is connected to one end of capacitor C5, one end of resistor R12, and the other end of resistor R16. The emitter of transistor Q2 is connected to the other end of capacitor C5, the other end of resistor R12, and the 5V voltage source;

[0015] The timing reset self-locking circuit includes an operational amplifier U8A. The non-inverting input terminal 3 of the operational amplifier U8A is connected to a 2.5V voltage source. The inverting input terminal 2 of the operational amplifier U8A is connected to the positive electrode of a diode D9A, the positive electrode of a diode D8, and one end of a resistor R29. The negative electrode of the diode D9A is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the self-locking circuit. The negative electrode of the diode D8 is connected to the signal control circuit. The output terminal 1 of the operational amplifier U8A is connected to the self-locking circuit. The other end of the resistor R29 is connected to one end of a resistor R33, one end of a capacitor C10, and one end of a capacitor C11. The other end of the resistor R33 is connected to the collector of a triode U11B. The other end of the capacitor C10 is connected to the other end of the capacitor C11, one end of a resistor R36, and grounded. The base of the triode U11B is connected to the other end of the resistor R36 and the collector of a triode U11A. The emitter of the triode U11B is connected to the base of the triode U11A and one end of a resistor R32. The other end of the resistor R32 is connected to the negative electrode of a diode D11. The positive electrode of the diode D11 is connected to the emitter of the triode U11A and connected to a 5V voltage source;

[0016] The signal control circuit includes an operational amplifier U8B. The non-inverting input terminal 5 of the operational amplifier U8B is connected to the self-locking circuit. The inverting input terminal 6 of the operational amplifier U8B is connected to a 2.5V voltage source. The output terminal 7 of the operational amplifier U8B is connected to one end of a resistor R9, the base of a triode Q3, and one end of a resistor R18. The other end of the resistor R18 is connected to the emitter of the triode Q3 and then grounded. The collector of the triode Q3 is connected to the 2 pin of an optocoupler U3. The other end of the resistor R9 is connected to one end of a resistor R3 and a 5V voltage source. The other end of the resistor R3 is connected to the 1 pin of the optocoupler U3. The 3 pin of the optocoupler U3 is connected to the emitter of a triode Q1. The 4 pin of the optocoupler U3 is connected to the negative electrode of a diode D3 and one end of a resistor R5. The positive electrode of the diode D3 is connected to the base of the triode Q1. The other end of the resistor R5 is grounded.

[0017] After adopting the above structure, through the setting of the AC overvoltage / undervoltage protection circuit and the DC overvoltage / undervoltage protection circuit, when the AC 220V input voltage and the DC high-voltage 400V input voltage have overvoltage or undervoltage abnormalities, the abnormal signal can be sent to the self-locking circuit for locking. The timing reset self-locking circuit is used to make the self-locking circuit reset regularly during overvoltage and undervoltage. Finally, according to the power supply abnormal conditions of the foregoing circuits including the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, the self-locking circuit, and the timing reset self-locking circuit, the signal control circuit will send a control signal to the external 24V battery power supply circuit to control the operation of the 24V battery power supply circuit. Thus, when the 220V AC power supply has overvoltage or undervoltage abnormalities, the AC power supply can be quickly switched to the battery DC power supply to ensure the normal power supply effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the overall circuit schematic diagram of the present invention;

[0019] Figure 2 is the circuit schematic diagram of the power supply circuit of the present invention;

[0020] Figure 3 is the circuit schematic diagram of the AC overvoltage / undervoltage protection circuit of the present invention;

[0021] Figure 4 is the circuit schematic diagram of the DC overvoltage / undervoltage protection circuit of the present invention;

[0022] Figure 5 is the circuit schematic diagram of the self-locking circuit of the present invention;

[0023] Figure 6 is the circuit schematic diagram of the timing reset self-locking circuit of the present invention;

[0024] Figure 7 is the circuit schematic diagram of the signal control circuit of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] As Figure 1 shown, a multiple protection circuit for AC overvoltage and undervoltage includes a power supply circuit, an AC overvoltage / undervoltage protection circuit, a DC overvoltage / undervoltage protection circuit, a self-locking circuit, a timing reset self-locking circuit, and a signal control circuit. The AC overvoltage / undervoltage protection circuit and the DC overvoltage / undervoltage protection circuit are connected and then respectively connected to the self-locking circuit and the timing reset self-locking circuit. The self-locking circuit and the timing reset self-locking circuit are further connected to the signal control circuit;

[0026] Among them, the input end of the power supply circuit is connected to the AC 220V input voltage and is converted into 5V and 2.5V voltage sources through a voltage regulator. The 5V and 2.5V voltage sources output by this power supply module are used to provide internal power supply for other circuits of the present invention, improving the portability of use;

[0027] The AC overvoltage / undervoltage protection circuit is used to detect whether there are abnormalities of overvoltage and undervoltage in the AC 220V input voltage;

[0028] The DC overvoltage / undervoltage protection circuit is used to detect whether there are abnormalities of overvoltage and undervoltage in the DC high-voltage 400V input voltage, where the DC high-voltage 400V is the DC high voltage output by the AC 220V input voltage through the PFC power factor compensation circuit;

[0029] The self-locking circuit is used to lock the state of the overvoltage and undervoltage protection circuits. The protection circuit is the AC overvoltage / undervoltage protection circuit or the DC overvoltage / undervoltage protection circuit, which facilitates subsequent timing to reset the self-locking circuit for signal processing;

[0030] The timing reset self-locking circuit is used to make the self-locking circuit reset at a fixed time during overvoltage and undervoltage;

[0031] According to the situations of the foregoing other circuits, the signal control circuit sends a control signal to the external 24V battery power supply circuit, so that when there is a power supply abnormality in the AC 220V input voltage or the DC high-voltage 400V input voltage, the 24V battery power supply circuit is controlled to work to ensure normal power supply.

[0032] As Figure 2 shown, the power supply circuit includes a voltage regulator U1. The voltage regulator U1 can choose to use the SSP7786A-5.0V chip, and the input AC voltage range of this chip is 80Vac~305Vac. The specific circuit is as follows: Pins 5 to 8 of the voltage regulator U1 are connected and then connected to one end of the resistor R1. The other end of the resistor R1 is connected to the negative electrodes of the diodes D1 and D2. The positive electrode of the diode D1 is connected to the negative electrode of the diode D4 and the live wire L1 of the AC 220V input voltage. The positive electrode of the diode D2 is connected to the negative electrode of the diode D5 and the neutral wire N1 of the AC 220V input voltage. The positive electrodes of the diodes D4 and D5 are connected and then grounded. Pin 3 of the voltage regulator U1 is connected to one end of the capacitor C2, one end of the capacitor C3, and one end of the resistor R2 and outputs a 5V voltage source. The other end of the resistor R2 is connected to pins 1 and 2 of the voltage regulator diode U2 and one end of the capacitor C4 and outputs a 2.5V voltage source. Pin 4 of the voltage regulator U1 is connected to one end of the capacitor C1 and outputs a 7.5V voltage source. The other end of the capacitor C1 is connected to pin 2 of the voltage regulator U1, the other ends of the capacitors C2 and C3, pin 3 of the voltage regulator diode U2, and the other end of the capacitor C4 and grounded. The working principle of this power supply circuit is as follows: The alternating current is rectified into "M"-waveform direct current by the diodes D1, D2, D4, and D5, and a stable +5V power supply is obtained through the resistor R1, the voltage regulator U1, and the capacitors C1, C2, and C3. The +5V obtains a reference voltage of +2.5V through the resistor R2, the capacitor C4, and the diode U2 (model: TL431B).

[0033] The AC voltage over / under-voltage detection circuit is used to detect the working condition of the AC 220V input voltage. When an abnormality occurs, it can generate an abnormal signal to control other circuits. For example Figure 3 As shown, the AC over-voltage / under-voltage protection circuit includes operational amplifiers U6, U4A, U4B, U5A, and U5B. The non-inverting input terminal 1 of operational amplifier U6 is connected to one end of resistor R10, the negative electrode of zener diode D7, one end of resistor R15, and one end of capacitor C7. The other end of resistor R10 is sequentially connected to the power supply circuit through resistor R6 and resistor 7. The positive electrode of zener diode D7, the other end of resistor R15, and the other end of capacitor C7 are connected to the 2nd pin of operational amplifier U6 and then grounded. The inverting input terminal 3 of operational amplifier U6 is connected to the output terminal 4 and then respectively connected to the inverting input terminal 6 of operational amplifier U4B and the inverting input terminal 2 of operational amplifier U4A. The output terminal 7 of operational amplifier U4B is connected to the non-inverting input terminal 5 of operational amplifier U5B and one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C6, the collector of triode U7B, and the DC over-voltage / under-voltage protection circuit. The emitter of triode U7B is connected to one end of resistor R13 and the base of triode U7A. The other end of resistor R13 is connected to the negative electrode of diode D6. The positive electrode of diode D6 is connected to the emitter of triode U7A and the 5V voltage source. The collector of triode U7A is connected to the base of triode U7B and one end of resistor R14. The other end of resistor R14 is connected to the other end of capacitor C6, the 4th pin of operational amplifier U4A and grounded. The 7th pin of operational amplifier U5B is connected to one end of resistor R8. The 1st pin of operational amplifier U5A is connected to one end of resistor R35 and one end of resistor R17. The other end of resistor R35 is connected to the 8th pin of operational amplifier U5A and then connected to the 5V voltage source. The other end of resistor R17 is connected to the other end of resistor R8 and then connected to the self-locking circuit. The non-inverting input terminal 3 of operational amplifier U4B is connected to one end of resistor R20, one end of resistor R23, and one end of capacitor C8. The other end of resistor R20 is connected to the 2.5V voltage source. The output terminal 1 of operational amplifier U4A is connected to the non-inverting input terminal 2 of operational amplifier U5A and one end of resistor R21. The other end of resistor R21 is connected to one end of capacitor C9, the collector of triode U9B. The emitter of triode U9B is connected to one end of resistor R22 and the base of triode U9A. The other end of resistor R22 is connected to the negative electrode of diode D10. The positive electrode of diode D10 is connected to the emitter of triode U9A and then connected to the 5V voltage source. The collector of triode U9A is connected to the base of triode U9B and one end of resistor R27. The other end of resistor R27 is connected to the other end of capacitor C9, the other end of capacitor C8, the other end of resistor R23 and grounded. The non-inverting input terminal 5 of operational amplifier U4B, the inverting input terminal 6 of operational amplifier U5B, and the non-inverting input terminal 3 of operational amplifier U5A are respectively connected to the 2.5V voltage source.

[0034] The working principle of the AC voltage over / under-voltage detection circuit is as follows:

[0035] The alternating current is rectified by the power supply module into a DC waveform in the shape of "M". This DC voltage waveform is divided by resistors R6, R7, R10, and R15 to obtain a low-voltage signal "AC_DET". The zener diode D7 is used to prevent overvoltage input, and the capacitor C7 is a filter capacitor. The low-voltage signal "AC_DET" passes through the operational amplifier U6 (model: LM321) for voltage following to obtain the signal "AC_Follow". Among them, the operational amplifiers U4A, U5A and their peripheral circuits form an undervoltage detection circuit. In the undervoltage detection circuit, the signal "AC_Follow" is compared with +1.34V through the operational amplifier U4A (model: LMV393). When the voltage of the signal "AC_Follow" is lower than +1.34V, the diode D10, the triodes U9A and U9B, the resistors R22 and R27, and the capacitor C9 form a current source to charge the capacitor C9. The charging duration is related to the value of the capacitor C9. The charging duration is generally set to be greater than 15mS (greater than the rectified frequency 47*2Hz). The longer the setting time, the longer the undervoltage detection time. The charging voltage "AC_UV_DET" of the capacitor C9 is compared with the reference voltage +2.5V through the operational amplifier U5A (model: LMV393): when the maximum voltage of the signal "AC_Follow" is lower than +1.34V and the undervoltage detection time exceeds the set value, the signal "AC_UVP" becomes low level, and the common terminal signal "UV_OV_COM" is low level; if the maximum voltage of the signal "AC_Follow" is greater than +1.34V and the detection time does not exceed the set value, the signal "AC_UV_DET" will have the opportunity to become high level, and the charge of the capacitor C9 will quickly discharge through the resistor R21. The discharge speed of the capacitor C9 is much greater than the charging speed, and the charge of the capacitor C19 is basically discharged, and the signal "AC_UVP" becomes high level, and the common terminal signal "UV_OV_COM" is high level;

[0036] Among them, operational amplifiers U4B, U5B and their peripheral circuits form an overvoltage detection circuit. In the overvoltage detection circuit, when the voltage of the signal "AC_Follow" enters, since the current source composed of diode D6, transistors U7A and U7B, resistors R13 and R14, and capacitor C6 has charged capacitor C6. The voltage of the signal "AC_Follow" is compared with the reference voltage +2.5V through comparator U4B (model: LMV393). When the voltage of the signal "AC_Follow" is higher than +2.5V, the signal "AC_OV_DET" becomes low level, and capacitor C6 starts to discharge. The discharge duration of capacitor C6 is related to the capacitance value of capacitor C6 and the resistance value of resistor R11. The discharge duration is generally set to be greater than 30mS (greater than the rectified frequency 47*2Hz, and considering lightning overvoltage at the same time). The longer the set time, the longer the overvoltage detection time. When the maximum value of the voltage of the signal "AC_Follow" is higher than +2.5V and the discharge duration exceeds the set value, the voltage of capacitor C6 after discharge is compared with the reference voltage +2.5V through comparator U5B (model: LMV393), and the signal "AC_OVP" becomes low level, and the common terminal signal "UV_OV_COM" is low level. If the maximum value of the voltage of the signal "AC_Follow" is less than +2.5V and the detection time does not exceed the set value, the signal "AC_OV_DET" becomes high level, capacitor C6 stops discharging and remains in the charging state all the time. When the charging voltage of capacitor C6 is higher than +2.5V, the signal "AC_OVP" becomes high level, and the common terminal signal "UV_OV_COM" is high level.

[0037] The DC overvoltage / undervoltage protection circuit is used to detect whether the input voltage of the DC high voltage 400V is abnormal. Specifically, such as Figure 4As shown in the figure, the operational amplifiers U12, U10A, and U10B of the DC overvoltage / undervoltage protection circuit are used. The non-inverting input terminal 1 of operational amplifier U12 is connected to one end of capacitor C13, one end of resistor R37, the cathode of diode D12, and one end of resistor R30. The other end of resistor R30 is connected to the 400V voltage source through resistors R28 and R26. The inverting input terminal 3 of operational amplifier U12 is connected to the output terminal 4 and then to the inverting input terminal 6 of operational amplifier U10B and the inverting input terminal 3 of operational amplifier U10A. The 2nd pin of operational amplifier U10A is connected to one end of resistor R31, one end of resistor R34, one end of capacitor C12, and the 2.13V voltage source. The other end of resistor R31 is connected to the 2.5V voltage source. The anode of diode D12 is connected to the other end of resistor R37, the other end of capacitor C13, the 2nd pin of operational amplifier U12, the other end of resistor R34, the other end of capacitor C12, the 4th pin of operational amplifier U10A, and is grounded. The output terminal 7 of operational amplifier U10B is connected to one end of resistor R24, and the other end of resistor R24 is connected to the AC overvoltage / undervoltage protection circuit. The output terminal 1 of operational amplifier U10A is connected to one end of resistor R35 and one end of resistor R38. The other end of resistor R35 is connected to the 8th pin of operational amplifier U10A and the 5V voltage source. The other end of resistor R38 is connected to the self-locking circuit and the timing reset self-locking circuit.

[0038] The working principle of the DC high-voltage over / under-voltage detection circuit is as follows:

[0039] When the input voltage of the DC high voltage of 400V is abnormal, an abnormal signal can be generated to control other circuits, namely the DC high-voltage over / under-voltage detection circuit. As Figure 4 shown, the input voltage of the DC high voltage of 400V is divided by resistors R26, R28, R30, and R37 to obtain a low-voltage signal "HV_DET". The zener diode D12 is used to prevent overvoltage input, and the capacitor C13 is a filter capacitor. The low-voltage signal "HV_DET" passes through the operational amplifier (model: LM321) U12 for voltage following to obtain the signal "HV_Follow", and the signal "HV_Follow" is sent to the overvoltage and undervoltage comparison circuit for processing;

[0040] When the voltage of the signal "HV_Follow" enters the undervoltage detection circuit, the voltage of the signal "HV_Follow" is compared with the voltage +2.13V obtained by dividing the voltages of resistors R31 and R34 through the comparator U10A (model: LMV393). When the voltage of the signal "HV_Follow" is lower than +2.13V, the signal "HV_UVP" becomes low level, and the common terminal signal "UV_OV_COM" is low level. If the voltage value of "HV_Follow" is greater than +2.13V, the signal "HV_UVP" becomes high level, and the common terminal signal "UV_OV_COM" is high level;

[0041] When the "HV_Follow" voltage enters the overvoltage detection circuit, the capacitor C6 has been fully charged by the current source composed of the diode D6, transistors U7A and U7B, resistors R13 and R14, and capacitor C6. The "HV_Follow" voltage signal is compared with the reference voltage of +2.5V by the comparator U10B (model: LMV393). When the "HV_Follow" voltage is higher than +2.5V, the discharge duration is related to the values of capacitor C6 and resistor R24. The discharge duration is generally set to be greater than 1mS. The longer the set time, the longer the overvoltage detection time. When the maximum value of the "HV_Follow" voltage is higher than +2.5V and the discharge duration exceeds the set value, the voltage after the capacitor C6 discharges is compared with the reference voltage of +2.5V by the comparator U5B (model: LMV393), and the signal "AC_OVP" becomes low level, and the common terminal signal "UV_OV_COM" is low level. If the maximum value of the "HV_Follow" voltage is less than +2.5V, the signal "HV_OVP" becomes high level, the capacitor C9 stops discharging and remains in the charging state. When the charging voltage of the capacitor C6 is higher than +2.5V, the signal "AC_OVP" becomes high level, and the common terminal signal "UV_OV_COM" is high level.

[0042] Specifically, as Figure 5 shown, the self-locking circuit includes transistors Q2 and Q4. The collector of the transistor Q4 is connected to one end of the resistor R16 and the positive electrode of the diode D9B. The negative electrode of the diode D9B is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the timing reset self-locking circuit. The emitter of the transistor Q4 is connected to one end of the resistor R25 and grounded. The base of the transistor Q4 is connected to one end of the resistor R19, the other end of the resistor R25, and the timing reset self-locking circuit. The other end of the resistor R19 is connected to the collector of the transistor Q2 and the signal control circuit. The base of the transistor Q2 is connected to one end of the capacitor C5, one end of the resistor R12, and the other end of the resistor R16. The emitter of the transistor Q2 is connected to the other end of the capacitor C5, the other end of the resistor R12, and the 5V voltage source.

[0043] The specific working principle of this self-locking circuit is as follows:

[0044] When the "UV_OV_COM" signal is at a high level, the diode D9B is in the off state, the triodes Q2 and Q4 are in the off state, and the "Lock_Self" signal is at a low level. When the "UV_OV_COM" signal changes from a high level to a low level, the diode D9B changes from off to instantaneously on and then back to the off state, the triodes Q2 and Q4 change from the off state to the on state, and the "Lock_Self" signal changes from a low level to a high level. After the "UV_OV_COM" signal changes from a low level to a high level, the diode D9B is in the off state, the triodes Q2 and Q4 remain in the on state, and the "Lock_Self" signal remains at a high level. This realizes low-level trigger locking, and the "Lock_Self" signal is used for subsequent signal processing.

[0045] The timing reset self-locking circuit is used for the timing reset of the overvoltage and undervoltage self-locking circuits. Specifically, as Figure 6 shown, the timing reset self-locking circuit includes an operational amplifier U8A. The non-inverting input terminal 3 of the operational amplifier U8A is connected to a 2.5V voltage source. The inverting input terminal 2 of the operational amplifier U8A is connected to the positive electrode of the diode D9A, the positive electrode of the diode D8, and one end of the resistor R29. The negative electrode of the diode D9A is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the self-locking circuit. The negative electrode of the diode D8 is connected to the signal control circuit. The output terminal 1 of the operational amplifier U8A is connected to the self-locking circuit. The other end of the resistor R29 is connected to one end of the resistor R33, one end of the capacitor C10, and one end of the capacitor C11. The other end of the resistor R33 is connected to the collector of the triode U11B. The other end of the capacitor C10 is connected to the other end of the capacitor C11, one end of the resistor R36, and grounded. The base of the triode U11B is connected to the other end of the resistor R36 and the collector of the triode U11A. The emitter of the triode U11B is connected to the base of the triode U11A and one end of the resistor R32. The other end of the resistor R32 is connected to the negative electrode of the diode D11. The positive electrode of the diode D11 is connected to the emitter of the triode U11A and connected to a 5V voltage source;

[0046] The working principle of the timing reset self-locking circuit is as follows:

[0047] The timing reset self-locking circuit is used for the timing reset of the overvoltage and undervoltage self-locking circuits. The timing reset self-locking circuit is as Figure 6As shown. Diode D11, resistors R32, R33 and R36, triodes U11A / U11B, capacitors C10 and C11 form a current source to charge capacitors C10 and C11, and the charging duration is determined by the capacitance values of capacitors C10 and C11. When the AC voltage and the DC high-voltage change from the normal working state to overvoltage or undervoltage, the "UV_OV_COM" signal changes from high level to low level, and capacitors C10 and C11 discharge through resistor R29 and diode D8 and then discharge through resistor R29 and diode D9A, and the two discharge speeds are much greater than the charging speed. The voltage across capacitor C10 is always less than +2.5V, and the self-locking circuit cannot be reset. At this time, since triode Q3 in the signal control circuit is turned off, diode D8 is also turned off. When the AC voltage or DC changes from abnormal to normal, the "UV_OV_COM" signal changes from low level to high level. At this time, both diodes D8 and D9A are turned off. At this time, capacitors C10 and C11 are in the charging state. The charging voltage of capacitor C10 is compared with the reference voltage +2.5V through comparator U8A (model: LMV393). When the voltage of the charging capacitor C10 exceeds +2.5V, the "UV_OV_RST" signal is at low level. At this time, triode Q4 in the self-locking circuit is in the off state, the "UV_OV_COM" signal is at high level, diode D9B is turned off, triode Q2 is in the off state, and the "Lock_Self" signal changes from high level to low level, realizing the reset of the self-locking circuit.

[0048] According to the abnormal conditions of the foregoing various circuits, the signal control circuit sends a control signal to the external 24V battery circuit to control whether it works, where the foregoing circuit includes an AC overvoltage / undervoltage protection circuit, a DC overvoltage / undervoltage protection circuit, a self-locking circuit, and a timing reset self-locking circuit. Specifically, as Figure 7 shown, the signal control circuit includes operational amplifier U8B. The non-inverting input terminal 5 of the operational amplifier U8B is connected to the self-locking circuit. The inverting input terminal 6 of the operational amplifier U8B is connected to a 2.5V voltage source. The output terminal 7 of the operational amplifier U8B is connected to one end of resistor R9, the base of triode Q3, and one end of resistor R18. The other end of resistor R18 is connected to the emitter of triode Q3 and then grounded. The collector of triode Q3 is connected to pin 2 of optocoupler U3. The other end of resistor R9 is connected to one end of resistor R3 and a 5V voltage source. The other end of resistor R3 is connected to pin 1 of optocoupler U3. The emitter of triode Q1 is connected to pin 3 of optocoupler U3. The cathode of diode D3 and one end of resistor R5 are connected to pin 4 of optocoupler U3. The anode of diode D3 is connected to the base of triode Q1. The other end of resistor R5 is grounded.

[0049] The working principle of the signal control circuit is as follows:

[0050] The signal "Lock_Self" of the self-locking circuit is compared with the reference voltage +2.5V through the comparator U8B (model: LMV393). When the signal "Lock_Self" is at a low level, the signal "UV_OV_CTRL" is at a low level, the triode Q3 is turned off, the signal "OPT_CTRL" is at a high level, the optocoupler U3 does not work, the triode Q1 is turned on, and the signal "DC_CTRL" has a voltage output. When the signal "Lock_Self" is at a high level, the signal "UV_OV_CTRL" is at a high level, the triode Q3 is turned on, the signal "OPT_CTRL" is at a low level, the optocoupler U3 works normally, the triode Q1 is turned off, and the signal "DC_CTRL" has no voltage output.

[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those familiar with the technology within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An AC overvoltage and undervoltage multiple protection circuit, characterized in that: It includes a power supply circuit, an AC overvoltage / undervoltage protection circuit, a DC overvoltage / undervoltage protection circuit, a self-locking circuit, a timing reset self-locking circuit, and a signal control circuit. The AC overvoltage / undervoltage protection circuit and the DC overvoltage / undervoltage protection circuit are connected and then respectively connected to the self-locking circuit and the timing reset self-locking circuit. The self-locking circuit and the timing reset self-locking circuit are then connected to the signal control circuit; The input end of the power supply circuit is connected to the AC 220V input voltage and is converted into 5V and 2.5V voltage sources through a voltage regulator; The AC overvoltage / undervoltage protection circuit is used to detect whether the AC 220V input voltage is abnormal; The DC overvoltage / undervoltage protection circuit is used to detect whether the DC high voltage 400V input voltage is abnormal; The self-locking circuit is used to lock the state of the overvoltage and undervoltage protection circuits. The protection circuit is the AC overvoltage / undervoltage protection circuit or the DC overvoltage / undervoltage protection circuit, which facilitates subsequent signal processing by the timing reset self-locking circuit; The timing reset self-locking circuit is used to make the self-locking circuit reset periodically during overvoltage and undervoltage; The signal control circuit, according to the situations of the foregoing various circuits, including the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, the self-locking circuit, and the timing reset self-locking circuit, sends a control signal to the external 24V battery power supply circuit to control the operation of the 24V battery power supply circuit; The AC overvoltage / undervoltage protection circuit includes operational amplifiers U6, U4A, U4B, U5A, and U5B. The non-inverting input terminal 1 of operational amplifier U6 is connected to one end of resistor R10, the negative electrode of zener diode D7, one end of resistor R15, and one end of capacitor C7. The other end of resistor R10 is sequentially connected to the power supply circuit through resistor R6 and resistor R7. The positive electrode of zener diode D7, the other end of resistor R15, and the other end of capacitor C7 are connected to the 2nd pin of operational amplifier U6 and then grounded. The inverting input terminal 3 of operational amplifier U6 is connected to the output terminal 4, and then respectively connected to the inverting input terminal 6 of operational amplifier U4B and the inverting input terminal 2 of operational amplifier U4A. The output terminal 7 of operational amplifier U4B is connected to the non-inverting input terminal 5 of operational amplifier U5B and one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C6, the collector of triode U7B, and the DC overvoltage / undervoltage protection circuit. The emitter of triode U7B is connected to one end of resistor R13 and the base of triode U7A. The other end of resistor R13 is connected to the negative electrode of diode D6. The positive electrode of diode D6 is connected to the emitter of triode U7A and the 5V voltage source. The collector of triode U7A is connected to the base of triode U7B and one end of resistor R14. The other end of resistor R14 is connected to the other end of capacitor C6, the 4th pin of operational amplifier U4A, and grounded. The 7th pin of operational amplifier U5B is connected to one end of resistor R8. The 1st pin of operational amplifier U5A is connected to one end of resistor R35 and one end of resistor R17. The other end of resistor R35 is connected to the 8th pin of operational amplifier U5A and then connected to the 5V voltage source. The other end of resistor R17 is connected to the other end of resistor R8 and then connected to the self-locking circuit. The non-inverting input terminal 3 of operational amplifier U4B is connected to one end of resistor R20, one end of resistor R23, and one end of capacitor C8. The other end of resistor R20 is connected to the 2.5V voltage source. The output terminal 1 of operational amplifier U4A is connected to the non-inverting input terminal 2 of operational amplifier U5A and one end of resistor R21. The other end of resistor R21 is connected to one end of capacitor C9 and the collector of triode U9B. The emitter of triode U9B is connected to one end of resistor R22 and the base of triode U9A. The other end of resistor R22 is connected to the negative electrode of diode D10. The positive electrode of diode D10 is connected to the emitter of triode U9A and then connected to the 5V voltage source. The collector of triode U9A is connected to the base of triode U9B and one end of resistor R27. The other end of resistor R27 is connected to the other end of capacitor C9, the other end of capacitor C8, the other end of resistor R23, and grounded. The non-inverting input terminal 5 of operational amplifier U4B, the inverting input terminal 6 of operational amplifier U5B, and the non-inverting input terminal 3 of operational amplifier U5A are respectively connected to the 2.5V voltage source.

2. The AC overvoltage and undervoltage multiple protection circuit according to claim 1, characterized in that: The power supply circuit includes a voltage regulator U1. Pins 5 to 8 of the voltage regulator U1 are connected together and then connected to one end of a resistor R1. The other end of the resistor R1 is connected to the negative electrodes of a diode D1 and a diode D2. The positive electrode of the diode D1 is connected to the negative electrode of a diode D4 and the live wire L1 of the AC 220V input voltage. The positive electrode of the diode D2 is connected to the negative electrode of a diode D5 and the neutral wire N1 of the AC 220V input voltage. The positive electrodes of the diode D4 and the diode D5 are connected together and then grounded. Pin 3 of the voltage regulator U1 is connected to one end of a capacitor C2, one end of a capacitor C3, and one end of a resistor R2 and outputs a 5V voltage source. The other end of the resistor R2 is connected to pins 1 and 2 of a zener diode U2 and one end of a capacitor C4 and outputs a 2.5V voltage source. Pin 4 of the voltage regulator U1 is connected to one end of a capacitor C1 and outputs a 7.5V voltage source. The other end of the capacitor C1 is connected to pin 2 of the voltage regulator U1, the other end of the capacitor C2, the other end of the capacitor C3, pin 3 of the zener diode U2, and the other end of the capacitor C4 and is grounded.

3. The AC overvoltage and undervoltage multiple protection circuit according to claim 1, wherein: The DC overvoltage / undervoltage protection circuit includes operational amplifiers U12, U10A, and U10B. The non-inverting input terminal (pin 1) of the operational amplifier U12 is connected to one end of a capacitor C13, one end of a resistor R37, the negative electrode of a diode D12, and one end of a resistor R30. The other end of the resistor R30 is connected to a 400V voltage source through resistors R28 and R26. The inverting input terminal (pin 3) of the operational amplifier U12 is connected to the output terminal (pin 4) and then connected to the inverting input terminal (pin 6) of the operational amplifier U10B and the inverting input terminal (pin 3) of the operational amplifier U10A. Pin 2 of the operational amplifier U10A is connected to one end of a resistor R31, one end of a resistor R34, one end of a capacitor C12, and a 2.13V voltage source. The other end of the resistor R31 is connected to a 2.5V voltage source. The positive electrode of the diode D12 is connected to the other end of the resistor R37, the other end of the capacitor C13, pin 2 of the operational amplifier U12, the other end of the resistor R34, the other end of the capacitor C12, and pin 4 of the operational amplifier U10A and is grounded. The output terminal (pin 7) of the operational amplifier U10B is connected to one end of a resistor R24. The other end of the resistor R24 is connected to the AC overvoltage / undervoltage protection circuit. The output terminal (pin 1) of the operational amplifier U10A is connected to one end of a resistor R35 and one end of a resistor R38. The other end of the resistor R35 is connected to pin 8 of the operational amplifier U10A and a 5V voltage source. The other end of the resistor R38 is connected to the self-locking circuit and the timing reset self-locking circuit.

4. An AC overvoltage and undervoltage multiple protection circuit according to claim 1, characterized in that: The self-locking circuit includes transistors Q2 and Q4. The collector of transistor Q4 is connected to one end of resistor R16 and the positive electrode of diode D9B. The negative electrode of diode D9B is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the timing reset self-locking circuit. The emitter of transistor Q4 is connected to one end of resistor R25 and grounded. The base of transistor Q4 is connected to one end of resistor R19, the other end of resistor R25, and the timing reset self-locking circuit. The other end of resistor R19 is connected to the collector of transistor Q2 and the signal control circuit. The base of transistor Q2 is connected to one end of capacitor C5, one end of resistor R12, and the other end of resistor R16. The emitter of transistor Q2 is connected to the other end of capacitor C5, the other end of resistor R12, and the 5V voltage source.

5. A multi - protection circuit for AC over - voltage and under - voltage, according to claim 1, characterized in that: The timing reset self-locking circuit includes operational amplifier U8A. The non-inverting input terminal 3 of operational amplifier U8A is connected to the 2.5V voltage source. The inverting input terminal 2 of operational amplifier U8A is connected to the positive electrode of diode D9A, the positive electrode of diode D8, and one end of resistor R29. The negative electrode of diode D9A is connected to the AC overvoltage / undervoltage protection circuit, the DC overvoltage / undervoltage protection circuit, and the self-locking circuit. The negative electrode of diode D8 is connected to the signal control circuit. The output terminal 1 of operational amplifier U8A is connected to the self-locking circuit. The other end of resistor R29 is connected to one end of resistor R33, one end of capacitor C10, and one end of capacitor C11. The other end of resistor R33 is connected to the collector of transistor U11B. The other end of capacitor C10 is connected to the other end of capacitor C11, one end of resistor R36, and grounded. The base of transistor U11B is connected to the other end of resistor R36 and the collector of transistor U11A. The emitter of transistor U11B is connected to the base of transistor U11A and one end of resistor R32. The other end of resistor R32 is connected to the negative electrode of diode D11. The positive electrode of diode D11 is connected to the emitter of transistor U11A and connected to the 5V voltage source.

6. A multi - protection circuit for AC over - voltage and under - voltage according to claim 1, characterized in that: The signal control circuit includes operational amplifier U8B. The non-inverting input terminal 5 of operational amplifier U8B is connected to the self-locking circuit. The inverting input terminal 6 of operational amplifier U8B is connected to the 2.5V voltage source. The output terminal 7 of operational amplifier U8B is connected to one end of resistor R9, the base of transistor Q3, and one end of resistor R18. The other end of resistor R18 is connected to the emitter of transistor Q3 and grounded. The collector of transistor Q3 is connected to pin 2 of optocoupler U3. The other end of resistor R9 is connected to one end of resistor R3 and the 5V voltage source. The other end of resistor R3 is connected to pin 1 of optocoupler U3. Pin 3 of optocoupler U3 is connected to the emitter of transistor Q1. Pin 4 of optocoupler U3 is connected to the negative electrode of diode D3 and one end of resistor R5. The positive electrode of diode D3 is connected to the base of transistor Q1. The other end of resistor R5 is grounded.

Images