A power supply seamless switching circuit, system and method

Abstract

The present invention relates to a power supply seamless switching circuit and system, including a power supply seamless switching circuit, and further including a surge protection circuit electrically connected to an external power supply terminal V+, an anti-reverse connection circuit electrically connected to the surge protection circuit, a voltage detection circuit and an overvoltage / undervoltage protection circuit both electrically connected to the anti-reverse connection circuit, a DC-DC circuit electrically connected to the overvoltage / undervoltage protection circuit, a battery charging circuit electrically connected to the DC-DC circuit, a backup battery electrically connected to the battery charging circuit, a boost circuit electrically connected to the backup battery, a voltage stabilizing circuit electrically connected to the boost circuit, and an MCU chip electrically connected to the boost circuit, the voltage stabilizing circuit and the voltage detection circuit respectively. This solution seamlessly switches the backup power supply, and when the MCU chip detects that the external power supply is lower than 6V, it will automatically perform a shutdown countdown. If the voltage recovers during the countdown, the shutdown will stop and the original working mode will be continued; if the voltage does not recover during the countdown, the MCU chip will enter the shutdown mode to cut off the power supply of the whole machine.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic products, and particularly relates to a power seamless switching circuit, system and method. Background Art

[0002] Users' requirements for electrical equipment are getting higher and higher. Especially when the external power is unstable, the equipment should keep working stably. The existing power switching circuits have the following defects:

[0003] (1) When the external power is unstable, it can only switch to the backup power supply and cannot automatically turn off the backup power supply;

[0004] (2) If you want to automatically turn off the backup power supply, the implemented circuit is relatively complex;

[0005] (3) The power switching circuit mainly relies on a switching IC or a comparator IC, resulting in a high cost.

[0006] To solve the above problems, we have invented a power seamless switching circuit, system and method. Summary of the Invention

[0007] The object of the present invention is to solve the problems of the existing power switching circuit, which can only switch to the backup power supply and cannot automatically turn off the backup power supply. If you want to automatically turn off the backup power supply, the implemented circuit is relatively complex. The power switching circuit mainly relies on a switching IC or a comparator IC, resulting in a high cost. The specific solutions are as follows:

[0008] A power seamless switching circuit includes the positive electrode of a diode D9, the drain D of MOS transistors Q4 and Q3, which are simultaneously electrically connected to a voltage terminal 5V0. The negative electrode of the diode D9, the source S of the MOS transistors Q4 and Q3, one ends of resistors R23 and R30 are simultaneously electrically connected to a +5V terminal. The other end of the resistor R30 is electrically connected to the voltage terminal BAT_+4V8 after the backup battery is boosted. The gates G of the MOS transistors Q4 and Q3, the other end of the resistor R23 are simultaneously electrically connected to the collector of a transistor Q5. The base of the transistor Q5 is electrically connected to one end of a resistor R25. The other end of the resistor R25 is simultaneously electrically connected to one ends of resistors R24 and R26 and the collector of a transistor Q6. The other end of the resistor R24 is electrically connected to the positive electrode of a voltage stabilizing diode D11. The base of the transistor Q6 is electrically connected to one end of a resistor R34. The other end of the resistor R34 is simultaneously electrically connected to one ends of resistors R33 and R35. The other end of the resistor R33 is electrically connected to the positive electrode of a voltage stabilizing diode D12. The negative electrodes of the voltage stabilizing diodes D11 and D12 are simultaneously electrically connected to an external power supply terminal V+. The emitters of the transistors Q5 and Q6, the other ends of the resistors R26 and R35 are simultaneously grounded.

[0009] A power seamless switching system includes the above-mentioned power seamless switching circuit, and also includes a surge protection circuit electrically connected to an external power supply terminal V+, a reverse connection protection circuit electrically connected to the surge protection circuit, a voltage detection circuit, an overvoltage / undervoltage protection circuit that are both electrically connected to the reverse connection protection circuit, a DC-DC circuit electrically connected to the overvoltage / undervoltage protection circuit, a battery charging circuit electrically connected to the DC-DC circuit, a backup battery electrically connected to the battery charging circuit, a boost circuit electrically connected to the backup battery, a voltage stabilizing circuit electrically connected to the boost circuit, and an MCU chip electrically connected to the boost circuit, the voltage stabilizing circuit, and the voltage detection circuit respectively.

[0010] Further, the surge protection circuit is a transient diode D4, whose pin 1 is electrically connected to both the external power supply terminal V- and the ground, and pin 2 is electrically connected to the external power supply terminal V+; the reverse connection protection circuit includes a reverse connection protection IC U3, pins 5-9 of U3 are simultaneously connected to the external power supply terminal V-, pins 1-3 of U3 are electrically connected to the ground of the system and the positive electrode of a voltage stabilizing diode D5 simultaneously, the negative electrode of the voltage stabilizing diode D5 is electrically connected to pin 4 of U3 and one end of a resistor R1 simultaneously, and the other end of the resistor R1 is electrically connected to the external power supply terminal V+.

[0011] Further, the voltage detection circuit includes one end of a resistor R31 electrically connected to the external power supply terminal V+, the other end of the resistor R31 is electrically connected to one end of a resistor R32, a capacitor C33, and the PWR_DET pin of the MCU chip simultaneously, and the other ends of the resistor R32 and the capacitor C33 are connected to the ground of the system simultaneously.

[0012] Further, the overvoltage / undervoltage protection circuit includes the negative electrodes of voltage stabilizing diodes D1, D2, D3, one end of a resistor R2, and the source electrode of a MOS transistor U1 that are all electrically connected to the external power supply terminal V+ simultaneously, the drain electrode of the MOS transistor U1 is electrically connected to the positive electrode of an electrolytic capacitor C1, one end of a capacitor C2, and a voltage terminal POWER_IN simultaneously, the gate electrode of the MOS transistor U1 is electrically connected to the other end of the resistor R2, the positive electrode of the voltage stabilizing diode D3, and one end of a resistor R6 simultaneously, the other end of the resistor R6 is electrically connected to the collector of a triode Q1, the base electrode of the triode Q1 is electrically connected to one end of a resistor R4 and the collector of a triode Q2 simultaneously, the other end of the resistor R4 is electrically connected to the positive electrode of the voltage stabilizing diode D2, the base electrode of the triode Q2 is electrically connected to one end of a resistor R3, the other end of the resistor R3 is electrically connected to the positive electrode of the voltage stabilizing diode D1, and the emitter electrodes of the triodes Q2 and Q1, the negative electrode of the electrolytic capacitor C1, and the other end of the capacitor C2 are all electrically connected to the ground of the system simultaneously.

[0013] Further, the DC-DC circuit includes a DC-DC IC U4 and an external circuit electrically connected to U4, the input pin 2 of U4 is electrically connected to the voltage terminal POWER_IN, and the output pin 8 of U4 is electrically connected to the voltage terminal 5V0 through an inductor L1.

[0014] Further, the battery charging circuit includes a battery charging IC U2 and a peripheral circuit electrically connected to U2. The input terminal 4 of U2 is electrically connected to the voltage terminal 5V0 through a resistor R5, and the output terminal 3 of U2 is electrically connected to the positive electrode BATT+ of the backup battery.

[0015] Further, the boost circuit includes a boost IC U5 and a peripheral circuit electrically connected to U5. The input terminal 13 of U5 is electrically connected to the positive electrode BATT+ of the backup battery through a resistor R10. The output terminals 1 and 9 of U5 are electrically connected to the voltage terminal BAT_+4V8, and the switch terminal 11 of U5 is electrically connected to the control terminal BAT_PWR_CRL of the MCU chip.

[0016] Further, the voltage stabilizing circuit includes a voltage stabilizing IC U6 and a peripheral circuit electrically connected to U6. The input terminal 1 of U6 is electrically connected to the +5V terminal through an isolation diode D10, and the output terminal 5 of U6 is electrically connected to the ARM_3V3 terminal of the MCU chip. The model of the MCU chip is: GD32F205ZET6, the model of the reverse connection protection IC is: MCAC53N06Y, the model of the DC-DC IC is: RT6365, the model of the battery charging IC is: TP4067, the model of the boost IC is: SY7215A, and the model of the voltage stabilizing IC is: SCJ6230B.

[0017] A power seamless switching method based on the above power seamless switching system is carried out according to the following steps:

[0018] Step 1, when the external input voltage is lower than 6V or higher than 36V, through the overvoltage / undervoltage protection circuit, the voltage terminal POWER_IN has no voltage output, and at the same time, the voltage detection circuit provides the PWR_DET voltage to the MCU chip for detection;

[0019] Step 2, when the input voltage is between 6V and 36V, the voltage of the voltage terminal POWER_IN is supplied to the DC-DC circuit to make it normally output 5V0 voltage;

[0020] Step 3, the 5V0 voltage is supplied to the battery charging circuit to charge the backup battery;

[0021] Step 4, the 5V0 voltage supplies current to the +5V terminal through the diode D9. When the external input voltage is greater than or equal to 6V, the MOS transistors Q4 and Q3 are normally turned on to reduce the voltage drop across the diode D9;

[0022] Step 5, the +5V terminal supplies power to the voltage stabilizing circuit through the diode D10, and after voltage reduction, the ARM_3V3 voltage is obtained to supply power to the MCU chip;

[0023] Step 6, after the MCU chip is started, the boost circuit is turned on by the high level of the BAT_PWR_CRL pin, raising the backup battery voltage to BAT_4V8, creating a voltage difference with the 5V0 voltage, and connecting it to the +5V terminal through resistor R30;

[0024] Step 7, when the electrical device is operating normally, if the external input voltage suddenly exceeds 36V or drops below 6V, there is no voltage output at the POWER_IN voltage terminal, and there is also no voltage output from the DC-DC circuit;

[0025] Step 8, the power seamless switching circuit turns off Q3 and Q4, seamlessly switching to BAT_4V8 to continue supplying power to the +5V terminal;

[0026] Step 9, when the MCU chip detects that the external voltage is not within the range of 6 - 36V, it enters the shutdown countdown program;

[0027] Step 10, within the countdown time, when the external input voltage can return to the normal range of 6 - 36V, the shutdown program is stopped and the device enters the normal operating mode;

[0028] Step 11, when the external input voltage does not return to the normal range of 6 - 36V during the shutdown countdown, the MCU chip turns the BAT_PWR_CRL pin to low level, turning off the boost circuit and automatically powering off the entire electrical device;

[0029] The shutdown countdown program described in Step 9 enables the electrical device to not lose data due to abnormal external voltage or power outage within the countdown time, and will not exhaust the backup battery voltage.

[0030] In summary, adopting the technical solution of the present invention has the following beneficial effects:

[0031] This solution solves the problems of the existing power switching circuit, which can only switch to the backup power supply, cannot automatically turn off the backup power supply, and if it is to automatically turn off the backup power supply, the implemented circuit is relatively complex. The power switching circuit mainly relies on switching ICs or comparator ICs, resulting in a high cost. This solution has the function of seamlessly switching to the backup power supply when the external power supply is unstable, without any impact on the electrical device. And when the MCU chip detects that the external power supply is lower than 6V, it will automatically start the shutdown countdown. If the voltage recovers during the countdown, then the shutdown is stopped and the original working mode is continued; if the voltage does not recover after the shutdown countdown, the MCU chip enters the shutdown mode, powering off the entire machine, so as not to exhaust the backup power supply. This solution adopts an anti-reverse connection circuit, discrete component overvoltage / undervoltage protection circuits, and a discrete component power switching circuit, which not only reduces the circuit cost but also protects the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only a part of the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a block diagram of a power seamless switching system of the present invention;

[0034] Figure 2 It is a circuit diagram of a power seamless switching circuit of the present invention;

[0035] Figure 3 It is a circuit diagram of a surge protection circuit, an anti-reverse connection circuit, a voltage detection circuit, and an overvoltage / undervoltage protection circuit of the present invention;

[0036] Figure 4 It is a circuit diagram of a DC-DC circuit of the present invention;

[0037] Figure 5 It is a circuit diagram of a battery charging circuit of the present invention;

[0038] Figure 6 It is a circuit diagram of a boost circuit of the present invention;

[0039] Figure 7 It is a circuit diagram of a voltage stabilizing circuit of the present invention.

[0040] Description of reference numerals:

[0041] 10 - Power seamless switching circuit, 20 - MCU chip, 100 - Backup battery, 200 - Surge protection circuit, 300 - Anti-reverse connection circuit, 400 - Voltage detection circuit 500 - Overvoltage / undervoltage protection circuit, 600 - DC-DC circuit, 700 - Battery charging circuit, 800 - Boost circuit, 900 - Voltage stabilizing circuit. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] Such as Figure 2As shown in the figure, a power supply seamless switching circuit 10 includes the anode of diode D9, the drain D of MOS transistor Q4 and Q3, which are simultaneously electrically connected to the voltage terminal 5V0. The cathode of diode D9, the source S of MOS transistor Q4 and Q3, one ends of resistors R23 and R30 are simultaneously electrically connected to the +5V terminal. The other end of resistor R30 is electrically connected to the voltage terminal BAT_+4V8 after the boost of the backup battery 100. The gates G of MOS transistor Q4 and Q3, the other end of resistor R23 are simultaneously electrically connected to the collector of transistor Q5. The base of transistor Q5 is electrically connected to one end of resistor R25. The other end of resistor R25 is simultaneously electrically connected to one ends of resistors R24 and R26, the collector of transistor Q6. The other end of resistor R24 is electrically connected to the anode of zener diode D11. The base of transistor Q6 is electrically connected to one end of resistor R34. The other end of resistor R34 is simultaneously electrically connected to one ends of resistors R33 and R35. The other end of resistor R33 is electrically connected to the anode of zener diode D12. The cathodes of zener diode D11 and zener diode D12 are simultaneously electrically connected to the external power supply terminal V+. The emitters of transistors Q5 and Q6, the other ends of resistors R26 and R35 are simultaneously grounded.

[0044] As Figure 1 As shown in the figure, a power supply seamless switching system includes the above-mentioned power supply seamless switching circuit 10, and also includes a surge protection circuit 200 electrically connected to the external power supply terminal V+, an anti-reverse connection circuit 300 electrically connected to the surge protection circuit 200, a voltage detection circuit 400 and an overvoltage / undervoltage protection circuit 500 simultaneously electrically connected to the anti-reverse connection circuit 300, a DC-DC conversion circuit 600 electrically connected to the overvoltage / undervoltage protection circuit 500, a battery charging circuit 700 electrically connected to the DC-DC conversion circuit 600, a backup battery 100 electrically connected to the battery charging circuit 700, a boost circuit 800 electrically connected to the backup battery 100, a voltage stabilization circuit 900 electrically connected to the boost circuit 800, and an MCU chip 20 electrically connected to the boost circuit 800, the voltage stabilization circuit 900 and the voltage detection circuit 400 respectively.

[0045] As Figure 3As shown, the surge protection circuit 200 is a transient diode D4. Its pin 1 is electrically connected to both the external power supply terminal V- and the ground, and its pin 2 is electrically connected to the external power supply terminal V+. The reverse connection protection circuit 300 includes a reverse connection protection IC U3. Pins 5 to 9 of U3 are simultaneously connected to the external power supply terminal V-, and pins 1 to 3 of U3 are electrically connected to both the ground of the system and the positive electrode of the voltage stabilizing diode D5. The negative electrode of the voltage stabilizing diode D5 is simultaneously connected to pin 4 of U3 and one end of the resistor R1. The other end of the resistor R1 is electrically connected to the external power supply terminal V+. The voltage detection circuit 400 includes one end of a resistor R31 electrically connected to the external power supply terminal V+. The other end of the resistor R31 is simultaneously connected to one end of a resistor R32, a capacitor C33, and the PWR_DET pin of the MCU chip 20. The other ends of the resistor R32 and the capacitor C33 are simultaneously connected to the ground of the system. The overvoltage / undervoltage protection circuit 500 includes the negative electrodes of voltage stabilizing diodes D1, D2, and D3, one end of a resistor R2, and the source electrode of a MOS transistor U1, all of which are simultaneously connected to the external power supply terminal V+. The drain electrode of the MOS transistor U1 is simultaneously connected to the positive electrode of the electrolytic capacitor C1, one end of a capacitor C2, and the voltage terminal POWER_IN. The gate electrode of the MOS transistor U1 is simultaneously connected to the other end of the resistor R2, the positive electrode of the voltage stabilizing diode D3, and one end of a resistor R6. The other end of the resistor R6 is electrically connected to the collector of a triode Q1. The base of the triode Q1 is simultaneously connected to one end of a resistor R4 and the collector of a triode Q2. The other end of the resistor R4 is connected to the positive electrode of the voltage stabilizing diode D2. The base of the triode Q2 is connected to one end of a resistor R3. The other end of the resistor R3 is connected to the positive electrode of the voltage stabilizing diode D1. The emitters of the triodes Q2 and Q1, the negative electrode of the electrolytic capacitor C1, and the other end of the capacitor C2 are simultaneously electrically connected to the ground of the system.

[0046] As Figure 4 shown, the DC-DC circuit 600 includes a DC-DC IC U4 and the peripheral circuit electrically connected to U4 (see the attached drawings for details). The input pin 2 of U4 is electrically connected to the voltage terminal POWER_IN, and the output pin 8 of U4 is electrically connected to the voltage terminal 5V0 through an inductor L1.

[0047] As Figure 5 shown, the battery charging circuit 700 includes a battery charging IC U2 and the peripheral circuit electrically connected to U2 (see the attached drawings for details). The input terminal pin 4 of U2 is electrically connected to the voltage terminal 5V0 through a resistor R5, and the output terminal pin 3 of U2 is electrically connected to the positive electrode BATT+ of the backup battery.

[0048] As Figure 6As shown in the figure, the boost circuit 800 includes a boost IC U5 and its peripheral circuits (see the attached drawings for details). The input terminal 13 of U5 is electrically connected to the positive pole BATT+ of the backup battery through a resistor R10. The output terminals 1 and 9 of U5 are electrically connected to the voltage terminal BAT_+4V8. The switching terminal 11 of U5 is electrically connected to the control terminal BAT_PWR_CRL of the MCU chip 20.

[0049] As Figure 7 shown in the figure, the voltage stabilizing circuit 900 includes a voltage stabilizing IC U6 and its peripheral circuits (see the attached drawings for details). The input terminal 1 of U6 is electrically connected to the +5V terminal through an isolation diode D10. The output terminal 5 of U6 is electrically connected to the ARM_3V3 terminal of the MCU chip 20. The model of the MCU chip is: GD32F205ZET6 or other replacement models. The model of the reverse connection protection IC is: MCAC53N06Y or other replacement models. The model of the DC-DC IC is: RT6365 or other replacement models. The model of the battery charging IC is: TP4067 or other replacement models. The model of the boost IC is: SY7215A or other replacement models. The model of the voltage stabilizing IC is: SCJ6230B or other replacement models.

[0050] A power seamless switching method based on the above power seamless switching system is carried out according to the following steps:

[0051] Step 1, when the external input voltage is lower than 6V or higher than 36V, through the overvoltage / undervoltage protection circuit 500, the voltage terminal POWER_IN has no voltage output. At the same time, the voltage detection circuit 400 provides the PWR_DET voltage to the MCU chip 20 for detection;

[0052] Step 2, when the input voltage is between 6V and 36V, the voltage of the voltage terminal POWER_IN is supplied to the DC-DC circuit 600 to enable it to normally output 5V0 voltage;

[0053] Step 3, the 5V0 voltage is supplied to the battery charging circuit 700 to charge the backup battery 100;

[0054] Step 4, the 5V0 voltage conducts current through the diode D9 to the +5V terminal. When the external input voltage is greater than or equal to 6V, the MOS transistors Q4 and Q3 are normally conducting, reducing the voltage drop across the diode D9;

[0055] Step 5, the +5V terminal supplies power to the voltage stabilizing circuit 900 through the diode D10. After voltage reduction, the ARM_3V3 voltage is obtained to supply power to the MCU chip 20;

[0056] Step 6, after the MCU chip 20 is started, the boost circuit 800 is turned on through the high level of the BAT_PWR_CRL pin, raising the voltage of the backup battery 100 to BAT_4V8, creating a voltage difference with the 5V0 voltage (this ensures that when the external power supply is normal, the electrical device uses the voltage provided by 5V0 to the +5V terminal and does not consume the BAT_4V8 voltage), and connecting it to the +5V terminal through the resistor R30;

[0057] Step 7, when the electrical device is working normally, if the external input voltage suddenly exceeds 36V or is lower than 6V, there is no voltage output at the voltage terminal POWER_IN, and at the same time, there is also no voltage output from the DC-DC circuit 600;

[0058] Step 8, the power seamless switching circuit 10 turns off Q3 and Q4, seamlessly switching to BAT_4V8 to continue supplying power to the +5V terminal;

[0059] Step 9, when the MCU chip 20 detects that the external voltage is not within the range of 6 - 36V, it enters the shutdown countdown program;

[0060] Step 10, within the countdown time, when the external input voltage can return to the normal range of 6 - 36V, the shutdown program is stopped and it enters the normal working mode;

[0061] Step 11, when the external input voltage does not return to the normal range of 6 - 36V during the shutdown countdown, the MCU chip 20 turns the BAT_PWR_CRL pin to a low level, turning off the boost circuit 800, causing the entire electrical device to power off automatically;

[0062] In the shutdown countdown program in Step 9, the electrical device can prevent data loss due to abnormal external voltage or power outage within the countdown time, and will not exhaust the voltage of the backup battery 100.

[0063] In summary, adopting the technical solution of the present invention has the following beneficial effects:

[0064] This solution solves the problems existing in the existing power switching circuit. The existing power switching circuit can only switch to the backup power supply and cannot automatically turn off the backup power supply. To automatically turn off the backup power supply, the implemented circuit is relatively complex. The power switching circuit mainly relies on a switching IC or a comparator IC, resulting in a high cost. This solution has the function of seamlessly switching to the backup power supply when the external power supply is unstable, without any impact on the electrical equipment. Moreover, when the MCU chip detects that the external power supply is lower than 6V, it will automatically start a shutdown countdown. If the voltage recovers during the countdown, the shutdown will stop and the original working mode will continue. If the voltage does not recover after the shutdown countdown, the MCU chip will enter the shutdown mode to cut off the power supply of the whole machine, so as not to exhaust the backup power supply. This solution adopts an anti-reverse connection circuit, an overvoltage / undervoltage protection circuit composed of discrete components, and a power switching circuit composed of discrete components, which not only reduces the circuit cost but also protects the electrical equipment.

[0065] The above-described embodiments do not constitute a limitation on the protection scope of the technical solution. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the above embodiments shall be included in the protection scope of the technical solution.

Claims

1. A power supply seamless switching circuit, characterized in that: it includes the positive electrode of diode D9, the drain D of MOS transistor Q4 and Q3, which are simultaneously electrically connected to the voltage terminal 5V0; the negative electrode of diode D9, the source S of MOS transistor Q4 and Q3, one ends of resistors R23 and R30 are simultaneously electrically connected to the +5V terminal; the other end of resistor R30 is electrically connected to the voltage terminal BAT_+4V8 after the backup battery is boosted; the gates G of MOS transistor Q4 and Q3, the other end of resistor R23 are simultaneously electrically connected to the collector of triode Q5; the base of triode Q5 is electrically connected to one end of resistor R25; the other end of resistor R25 is simultaneously electrically connected to one ends of resistor R24, R26 and the collector of triode Q6; the other end of resistor R24 is electrically connected to the positive electrode of voltage stabilizing diode D11; the base of triode Q6 is electrically connected to one end of resistor R34; the other end of resistor R34 is simultaneously electrically connected to one ends of resistor R33 and R35; the other end of resistor R33 is electrically connected to the positive electrode of voltage stabilizing diode D12; the negative electrodes of voltage stabilizing diode D11 and voltage stabilizing diode D12 are simultaneously electrically connected to the external power supply terminal V+; the emitters of triode Q5 and Q6, the other ends of resistor R26 and R35 are simultaneously grounded.

2. A power supply seamless switching system, including the power supply seamless switching circuit described in claim 1, characterized in that: it further includes a surge protection circuit electrically connected to the external power supply terminal V+, a reverse connection protection circuit electrically connected to the surge protection circuit, a voltage detection circuit, an overvoltage / undervoltage protection circuit, which are simultaneously electrically connected to the reverse connection protection circuit, a DC-DC conversion circuit electrically connected to the overvoltage / undervoltage protection circuit, a battery charging circuit electrically connected to the DC-DC conversion circuit, a backup battery electrically connected to the battery charging circuit, a boosting circuit electrically connected to the backup battery, a voltage stabilizing circuit electrically connected to the boosting circuit, and an MCU chip respectively electrically connected to the boosting circuit, the voltage stabilizing circuit and the voltage detection circuit.

3. According to the power supply seamless switching system described in claim 2, characterized in that: the surge protection circuit is a transient diode D4, its pin 1 is simultaneously electrically connected to the external power supply terminal V- and the ground, and its pin 2 is electrically connected to the external power supply terminal V+; the reverse connection protection circuit includes a reverse connection protection IC U3, pins 5-9 of U3 are simultaneously connected to the external power supply terminal V-, pins 1-3 of U3 are simultaneously electrically connected to the ground of the system and the positive electrode of voltage stabilizing diode D5, the negative electrode of voltage stabilizing diode D5 is simultaneously electrically connected to pin 4 of U3 and one end of resistor R1, and the other end of resistor R1 is electrically connected to the external power supply terminal V+.

4. According to the power supply seamless switching system described in claim 3, characterized in that: the voltage detection circuit includes one end of resistor R31 electrically connected to the external power supply terminal V+, the other end of resistor R31 is simultaneously electrically connected to one ends of resistor R32, capacitor C33 and the PWR_DET pin of the MCU chip, and the other ends of resistor R32 and capacitor C33 are simultaneously connected to the ground of the system.

5. According to the power supply seamless switching system described in claim 4, characterized in that: The overvoltage / undervoltage protection circuit includes the negative electrodes of voltage stabilizing diodes D1, D2, and D3, one end of resistor R2, and the source electrode of MOS transistor U1, all of which are electrically connected to the external power supply terminal V+ simultaneously. The drain electrode of MOS transistor U1 is electrically connected to the positive electrode of electrolytic capacitor C1, one end of capacitor C2, and the voltage terminal POWER_IN simultaneously. The gate electrode of MOS transistor U1 is electrically connected to the other end of resistor R2, the positive electrode of voltage stabilizing diode D3, and one end of resistor R6 simultaneously. The other end of resistor R6 is electrically connected to the collector electrode of triode Q1. The base electrode of triode Q1 is electrically connected to one end of resistor R4 and the collector electrode of triode Q2 simultaneously. The other end of resistor R4 is electrically connected to the positive electrode of voltage stabilizing diode D2. The base electrode of triode Q2 is electrically connected to one end of resistor R3. The other end of resistor R3 is electrically connected to the positive electrode of voltage stabilizing diode D1. The emitter electrodes of triodes Q2 and Q1, the negative electrode of electrolytic capacitor C1, and the other end of capacitor C2 are all electrically connected to the ground of the system.

6. The power supply seamless switching system according to claim 5, characterized in that: the DC-DC circuit includes a DC-DC IC U4 and an external circuit electrically connected to U4. The input pin 2 of U4 is electrically connected to the voltage terminal POWER_IN. The output pin 8 of U4 is electrically connected to the voltage terminal 5V0 through an inductor L1.

7. The power supply seamless switching system according to claim 6, characterized in that: the battery charging circuit includes a battery charging IC U2 and an external circuit electrically connected to U2. The input terminal 4 of U2 is electrically connected to the voltage terminal 5V0 through a resistor R5. The output terminal 3 of U2 is electrically connected to the positive electrode BATT+ of the backup battery.

8. The power supply seamless switching system according to claim 7, characterized in that: the boost circuit includes a boost IC U5 and an external circuit electrically connected to U5. The input terminal 13 of U5 is electrically connected to the positive electrode BATT+ of the backup battery through a resistor R10. The output terminals 1 and 9 of U5 are electrically connected to the voltage terminal BAT_+4V8. The switching terminal 11 of U5 is electrically connected to the control pin BAT_PWR_CRL of the MCU chip.

9. The power supply seamless switching system according to claim 8, characterized in that: the voltage stabilizing circuit includes a voltage stabilizing IC U6 and an external circuit electrically connected to U6. The input terminal 1 of U6 is electrically connected to the +5V terminal through an isolation diode D10. The output terminal 5 of U6 is electrically connected to the ARM_3V3 pin of the MCU chip; the model of the MCU chip is: GD32F205ZET6, the model of the reverse connection protection IC is: MCAC53N06Y, the model of the DC-DC IC is: RT6365, the model of the battery charging IC is: TP4067, the model of the boost IC is: SY7215A, and the model of the voltage stabilizing IC is: SCJ6230B.

10. A power supply seamless switching method for the power supply seamless switching system according to any one of claims 2 to 9, characterized in that, it is carried out according to the following steps: Step 1, when the external input voltage is lower than 6V or higher than 36V, through the overvoltage / undervoltage protection circuit, there is no voltage output at the voltage terminal POWER_IN. At the same time, the voltage detection circuit provides the PWR_DET voltage to the MCU chip for detection; Step 2, when the input voltage is between 6V and 36V, the voltage at the voltage terminal POWER_IN is supplied to the DC-DC circuit, enabling it to normally output 5V0 voltage; Step 3, the 5V0 voltage is supplied to the battery charging circuit to charge the backup battery; Step 4, the 5V0 voltage is used to provide freewheeling for the +5V terminal through diode D9. When the external input voltage is greater than or equal to 6V, MOS transistors Q4 and Q3 are normally turned on, reducing the voltage drop across diode D9; Step 5, the +5V terminal is supplied to the voltage stabilizing circuit through diode D10, and after voltage reduction, the ARM_3V3 voltage is obtained to supply power to the MCU chip; Step 6, after the MCU chip is started, the boost circuit is turned on through the high level of the BAT_PWR_CRL pin, raising the voltage of the backup battery to BAT_4V8, forming a voltage difference with the 5V0 voltage, and connecting it to the +5V terminal through resistor R30; Step 7, when the electrical device is operating normally, if the external input voltage suddenly becomes higher than 36V or lower than 6V, there is no voltage output at the voltage terminal POWER_IN, and at the same time, there is no voltage output from the DC-DC circuit; Step 8, the power seamless switching circuit turns off Q3 and Q4, and seamlessly switches to BAT_4V8 to continue supplying power to the +5V terminal; Step 9, when the MCU chip detects that the external voltage is not within the range of 6V to 36V, it enters the shutdown countdown program; Step 10, within the countdown time, when the external input voltage can return to the normal range of 6V to 36V, the shutdown program is stopped, and the device enters the normal working mode; Step 11, when the external input voltage does not return to the normal range of 6V to 36V during the shutdown countdown, the MCU chip turns the BAT_PWR_CRL pin to a low level, turning off the boost circuit, causing the entire electrical device to automatically power off; In the shutdown countdown program described in Step 9, the electrical device can prevent data loss due to abnormal external voltage or power outage within the countdown time, and the backup battery voltage will not be exhausted.

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