Dual power system

Abstract

The application relates to a dual-power system and belongs to the technical field of power switching. The dual-power system comprises a power-off detection unit for detecting whether the main power of the dual-power system is powered off, the input end of a rectifier bridge of the power-off detection unit is used for being connected with the main power, the output end of the rectifier bridge is connected with the input end of a comparator through a connecting circuit for outputting a pulse waveform, the other input end of the comparator is used for inputting a reference value, the output end of the comparator is connected with a controller, and the controller is used for controlling the switching of the main power and the standby power in the dual-power system according to the output of the comparator. The signal output by the connecting circuit after the alternating current signal of the main power is rectified by the power-off detection unit is used as the analog value of the comparator, the set judgment value is used as the reference value of the comparator, the comparator compares the analog value and the reference value and outputs high and low levels, whether the main power is powered off is judged according to the time length of the high and low levels output by the comparator in a set period, and the controller timely switches the standby power.

Description

TECHNICAL FIELD

[0001] The present application relates to a dual power supply system, belonging to the technical field of power supply switching. BACKGROUND

[0002] The dual-path AC 220V high-speed automatic switching control circuit is the most important part of power supply redundancy design, which can output fast switching to ensure that the sensitive equipment in the rear stage does not stop after the main power (the main power supply in the dual power supply) is powered off. In many special application environments, users pay more attention to power failure. Not only do they require accurate and stable dual power supply switching, but they also require switching time to be less than 15ms.

[0003] The existing dual power supply switching circuit determines whether the power supply as the main power supply in the dual power supply is powered off through the conduction or shutdown of the optocoupler. When the main power supply is detected to be powered off, the controller controls the relay to switch the power supply from the main power supply to another power supply as the backup power supply in the dual power supply. However, when there is a capacitive load in the load, after the main power supply is powered off, the capacitive load will discharge for a period of time, resulting in a certain time difference between the time when the main power supply is detected to be powered off and the actual time when the main power supply is powered off. The main power supply cannot be detected to be powered off in time, and thus the power supply cannot be switched to the backup power supply in time. SUMMARY

[0004] The purpose of the present application is to provide a dual power supply system to solve the problem that the existing power supply cannot be switched from the main power supply to the backup power supply in time due to the detection time of power failure being later than the actual power failure time.

[0005] To achieve the above-mentioned purpose, the scheme of the present application includes:

[0006] The dual power supply switching circuit of the present application includes a power failure detection unit for detecting whether the main power supply in the dual power supply is powered off. The power failure detection unit includes a rectifier bridge, the input end of the rectifier bridge is connected with the main power supply, the output end of the rectifier bridge is connected with the input end of the comparator through a connection circuit for outputting a pulse waveform, the other input end of the comparator is used for inputting a reference value, the output end of the comparator is connected with a controller, and the controller is used for controlling the switching of the main power supply and the backup power supply in the dual power supply according to the output of the comparator.

[0007] Further, the connection circuit includes an amplification circuit.

[0008] Further, the amplification circuit is a differential amplification circuit, the output end of the rectifier bridge is connected with the input end of the differential amplification circuit through a voltage division circuit for outputting a differential signal, and the output end of the differential amplification circuit is connected with the input end of the comparator.

[0009] Further, the voltage division circuit includes a voltage division resistor connected in series between the output ends of the rectifier bridge, and the two sides of the voltage division resistor are connected with the input ends of the differential amplification circuit as the outputs of the voltage division circuit.

[0010] Further, a plurality of resistors in series are further included, and a connection point between any two adjacent resistors is connected to an input of the comparator to output a level at the connection point of the two adjacent resistors to the comparator as a reference value.

[0011] Further, an opto-coupler isolation circuit is further included, and the controller outputs a control signal for switching the main power supply and the backup power supply through the opto-coupler isolation circuit.

[0012] Further, a power conversion unit for supplying power for operation of the dual power supply switching circuit is further included, the power conversion unit includes a main power taking unit with an input connected to the main power supply and a backup power taking unit with an input connected to the backup power supply, an output of the main power taking unit is connected to the power supply end of the first power supply of the dual power supply switching circuit, and an output of the backup power taking unit is connected to the power supply end through a diode with the same direction as the output thereof.

[0013] Further, the power conversion unit further includes a conversion circuit for reducing the first power supply to the second power supply, the second power supply is connected to the controller through a light emitting side of an opto-coupler in the opto-coupler isolation circuit, and the first power supply is connected to an output end of the controller for outputting the control signal through a coupling side of the opto-coupler.

[0014] The dual power supply system of the present application includes a first input end for connecting a main power supply as a main power supply, a second input end for connecting a backup power supply as a backup power supply, and a power transmission end for outputting power supply, further includes the dual power supply switching circuit as described above and a first relay and a second relay connected between the first input end, the second input end and the power transmission end respectively, and an output end of the controller in the dual power supply switching circuit controls closing or turning off of the first relay and the second relay respectively.

[0015] Further, a manual-automatic switching unit is further included, the manual-automatic switching unit includes two double-pole double-throw switches, the first input end and the second input end are connected to two common terminals of a first double-pole double-throw switch respectively, two terminals on one side of the first double-pole double-throw switch are connected to two common terminals of a second double-pole double-throw switch, two terminals on the other side of the first double-pole double-throw switch are connected to output ends of the first relay and the second relay respectively, a first terminal of two terminals on one side of the second double-pole double-throw switch is connected to the power transmission end, and a second terminal of two terminals on the other side of the second double-pole double-throw switch is short-circuited with the first terminal.

[0016] The present application has the following beneficial effects:

[0017] The application is an open invention, and provides a dual power supply switching circuit and a dual power supply system. The main power supply as a commonly used power supply in the main and standby power supply is collected and detected by a power failure detection unit, and whether the main power supply is powered off is determined in time according to the detection result, and then the main power supply is switched to the standby power supply in time through a controller, so as to avoid the shutdown of the sensitive equipment in the next stage caused by the power failure of the main power supply and the failure of the standby power supply to supply power in time. The dual power supply switching circuit specifically comprises a power failure detection unit for detecting whether the main power supply in the dual power supply is powered off, the power failure detection unit comprises a rectifier bridge, an input end of the rectifier bridge is used for being connected with the main power supply, an output end of the rectifier bridge is connected with an input end of a comparator through a connecting circuit for outputting a pulse waveform, another input end of the comparator is used for inputting a reference value, and an output end of the comparator is connected with a controller, and the controller is used for controlling the switching of the main power supply and the standby power supply in the dual power supply according to the output of the comparator. Wherein, the AC signal of the main power supply is rectified by the power failure detection unit to obtain a pulse signal with only a positive half cycle, the judgment value is set as the reference value of the comparator, the signal output through the connecting circuit after rectification is used as the analog value of the comparator, the comparator compares the analog value with the reference value and outputs high and low levels, whether the main power supply is powered off is determined by the length of the digital signal output by the comparator in the set period (the length of the high and low levels output in the set period), and when the length of the high level in the set period is too long or too short, it is considered that the main power supply is powered off, and the main power supply is switched to the standby power supply in time through the controller. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the principle diagram of the dual power supply switching control of the dual power supply system of the embodiment of the application;

[0019] Figure 2 is the power conversion circuit diagram of converting AC 220V into DC 12V in the embodiment of the application;

[0020] Figure 3 is the power conversion circuit diagram of converting DC 12V into DC 3.3V in the embodiment of the application;

[0021] Figure 4 is the power failure detection circuit diagram of the embodiment of the application;

[0022] Figure 5 is the circuit diagram of outputting the reference value in the embodiment of the application;

[0023] Figure 6 is the optical coupling isolation circuit diagram of the embodiment of the application;

[0024] Figure 7 is the waveform diagram of the main power supply power-on signal in the embodiment of the application;

[0025] Figure 8 is the waveform diagram of the main power supply power-off signal in the embodiment of the application;

[0026] Figure 9 is a waveform diagram of a main power-off process of an embodiment of the present application;

[0027] Figure 10 is a waveform diagram of a main-standby power switching process of an embodiment of the present application. DETAILED DESCRIPTION

[0028] To solve the problems in the background art, the present application provides a dual power switching circuit and a dual power system. The main power as the commonly used power among the main and standby power is collected and detected by a power-off detection unit, and whether the main power is powered off is determined in time according to the detection result, and then the main power is switched to the standby power in time by a controller, so as to avoid the shutdown of the sensitive equipment in the later stage caused by the power-off of the main power and the failure of the standby power to compensate in time. Wherein, the AC signal of the main power is rectified by the power-off detection unit to obtain a pulse signal with only a positive half cycle, a set judgment value is set as the reference value of the comparator, and the signal outputted by the connection circuit after rectification is set as the analog value of the comparator. The comparator compares the analog value with the reference value and outputs high and low levels. Whether the main power is powered off is determined by the length of the digital signal outputted by the comparator in the set period (the length of the high and low levels outputted by the comparator in the set period). When the length of the high level in the set period is too long or too short, it is considered that the main power is powered off, and the main power is switched to the standby power in time by the controller.

[0029] To make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below with reference to the drawings and embodiments.

[0030] An embodiment of a dual power switching circuit:

[0031] A dual power switching circuit, comprising a power conversion unit, a power-off detection unit and an optical coupling isolation unit.

[0032] The power conversion unit converts the input main and standby power into control power for powering the operation of the dual power switching circuit.

[0033] Specifically, as shown in the power conversion circuit as the power conversion unit Figure 2 , the power chip U6 for converting AC 220 volts (AC 220V) into direct current 12 volts (DC 12V) is used as the power module U6, the input end of which is connected to the main power. In order to protect the chip, a fuse (fuse is also called a fuse) F1 and a resistor R24 are connected in series in the line connected to the live wire, and a pressure-sensitive resistor RV1 is connected in parallel to the input end of the power chip U6. The power chip U7 for converting AC 220V into DC 12V is used as the power module U7, the input end of which is connected to the standby power (standby power or auxiliary power). In order to protect the chip, a fuse F2 and a resistor R25 are connected in series in the line connected to the live wire, and a pressure-sensitive resistor RV2 is connected in parallel to the input end of the power chip U7.

[0034] The live wire L of the main power supply ( Figure 2 The AC220L-1 is connected to one end of fuse F1, the other end of fuse F1 is connected to varistor RV1 and the 24th resistor R24, the other end of the 24th resistor R24 ​​is connected to the AC-L pin (pin 2 of power module U6), and the neutral line N of the main power supply is connected to the AC-L pin (pin 2 of U6). Figure 2 The AC220N-1 is connected to the other end of the varistor RV1 and the AC-N pin (pin 1 of U6) of the power module U6. The output terminal of the power module U6 (the -V0 pin of U6 corresponds to pin 4 of U6 and the +V0 pin of U6 corresponds to pin 5 of U6) is connected in parallel with the tenth capacitor C10 and the eleventh capacitor C11. After the tenth capacitor C10 and the eleventh capacitor C11 are connected in parallel at the output terminal of the power module U6, a +12V control voltage is output.

[0035] Auxiliary power live wire L ( Figure 2 The AC220L-2 is connected to one end of fuse F2, the other end of fuse F2 is connected to varistor RV2 and the 25th resistor R25, the other end of the 25th resistor R25 is connected to the AC-L pin (pin 2 of power module U7), and the auxiliary power neutral line N ( Figure 2 The AC220N-2 is connected to the other end of the varistor RV2 and the AC-N pin (pin 1 of U7) of the power module U7. The output terminal of the power module U7 (the -V0 pin of U7 corresponds to pin 4 of U7 and the +V0 pin of U7 corresponds to pin 5 of U7) is connected in parallel with the twelfth capacitor C12 and the thirteenth capacitor C13. The negative terminal of the output terminal of the power module U7 after connecting the twelfth capacitor C12 and the thirteenth capacitor C13 in parallel is grounded. The positive terminal of the output terminal of the power module U7 after connecting the twelfth capacitor C12 and the thirteenth capacitor C13 in parallel is connected to output +12V control voltage through diode D1.

[0036] In order to enable the power conversion circuit to draw power mainly from the main power, a diode D1 with the same direction as the output is set on the positive terminal of the power chip U7. When the main power is on, the DC12V of the dual power supply switching circuit is provided by the main power, while preventing the reverse input of U7 when the output of U6 is higher than that of U7. When the main power is off, the DC12V is provided by the auxiliary power.

[0037] The power conversion circuit further converts DC12V to DC3.3V via power chip U8 for use by the dual power supply switching circuit. The specific conversion circuit within the power conversion unit is as follows: Figure 3As shown, the power supply chip U8 for converting DC 12V to DC 3.3V is taken as the power module U8, the positive pole of the input end of the power module U8 (the 4th pin of U8 corresponds to the Vin pin) is connected to +12V, the negative pole of the input end of the power module U8 (the 1st pin of U8 corresponds to the GND pin) is grounded, the output end of the power module U8 (the 5th pin and the 7th pin of U8) is connected in parallel with the fourteenth capacitor C14 and the fifteenth capacitor C15, the positive terminal of the output end of the power module U8, the positive pole of the fourteenth capacitor C14 and one end of the fifteenth capacitor C15 output +3.3V control power, and the negative terminal of the output end of the power module U8, the negative pole of the fourteenth capacitor C14 and the other end of the fifteenth capacitor C15 are grounded.

[0038] Among them, the pressure sensitive resistor RV1 and the pressure sensitive resistor RV2 are taken as voltage limiting protection devices, mainly used for voltage clamping when the circuit is subjected to overvoltage, and absorbing excess current to protect sensitive devices. Figure 2 and Figure 3 The circuit of the input main and standby power is converted into control power with voltages of 12V and 3.3V respectively for powering the operation of the dual power supply switching circuit.

[0039] Of course, in actual use, the required control power can be obtained by adjusting according to actual needs.

[0040] Among them, the power failure detection unit for detecting whether the main power in the dual power supply is powered off includes a rectifier bridge, a connection circuit and a comparator; the input end of the rectifier bridge is connected with the main power as the main power supply, the output end of the rectifier bridge is connected with the input end of the comparator through the connection circuit for outputting pulse waveform, the other input end of the comparator is used for inputting a reference value, and the output end of the comparator is connected with a controller, which is used for controlling the switching of the main power and the standby power in the dual power supply according to the output of the comparator.

[0041] Specifically, the connection circuit is an amplification circuit, when the amplification circuit adopts a differential amplification circuit, the power failure detection unit includes a rectifier bridge, a differential amplification circuit and a comparator; the input end of the main power is connected with the input end of the rectifier bridge for full-wave rectification, and then outputs an AC signal of the main power as a pulse signal with a positive half cycle, that is, the sine wave waveform of the main power is output as a sine wave with a positive half cycle after rectification, and then the output end of the rectifier bridge is output through the differential amplification circuit and the comparator to obtain a pulse signal of the main power power failure (main power power failure) or main power power on, and the pulse signal is given to the controller, and the controller outputs a drive signal, and the controller outputs a drive signal through an optical coupling isolation unit to drive the relay to realize the control of the relay, and the main power is switched to the standby power in time when the main power is powered off.

[0042] Specifically, the power supply power failure detection circuit as the power failure detection unit is as shown in Figure 4As shown, the output of the rectifier bridge B1 generates a differential signal through a voltage dividing circuit composed of resistors R2, R3, R4, R5 and R7, the differential signal is input into a differential amplification circuit, the waveform after differential amplification is compared with a reference value in a comparator, and then a pulse signal Si-01 is output. The controller detects the change of high and low levels of the pulse signal Si-01 to determine the main power on / off.

[0043] The positive output of the rectifier bridge B1 is connected to the second resistor R2, the negative output of the rectifier bridge B1 is connected to the ground GND and the seventh resistor R7, the other end of the second resistor R2 is connected to the third resistor R3 and the fourth resistor R4, the other end of the fourth resistor R4 is connected to the fifth resistor R5 and the other end of the seventh resistor R7, the other end of the third resistor R3 is connected to the first resistor R1 and the non-inverting input terminal of the operational amplifier U3A, the other end of the fifth resistor R5 is connected to the sixth resistor R6 and the inverting input terminal of the operational amplifier U3A, the other end of the sixth resistor R6 is connected to the output terminal of the operational amplifier U3A and the non-inverting input terminal of the operational amplifier U3D, and the inverting input terminal of the operational amplifier U3D is connected to the comparison level Vref.

[0044] The input terminal of the differential amplification circuit is connected to the output terminal of the rectifier bridge, and the output terminal of the differential amplification circuit is connected to the positive input terminal of the comparator; the differential amplification circuit includes the second resistor, the fourth resistor and the seventh resistor connected in series between the positive and negative outputs of the rectifier bridge, the connection point of the seventh resistor and the negative output of the rectifier bridge is connected to the ground, the connection point of the second resistor and the fourth resistor is connected to the input pin of the operational amplifier and the positive power supply pin of the operational amplifier through the third resistor, the first resistor is connected between the third resistor and the positive power supply pin of the operational amplifier, and the connection point between the first resistor and the positive power supply pin of the operational amplifier is connected to the ground; the connection point of the fourth resistor and the seventh resistor is connected to the output pin of the operational amplifier and the output terminal of the operational amplifier through the fifth resistor, the sixth resistor is further provided between the fifth resistor and the output terminal of the operational amplifier, the negative power supply pin of the operational amplifier is connected to the power supply, and the output terminal of the operational amplifier serves as the output terminal of the differential amplification circuit.

[0045] The reference value of the comparator is obtained through a voltage dividing circuit as shown in Figure 5 . Specifically, as shown in Figure 5 , the tenth resistor R10, the eighteenth resistor R18 and the twentieth resistor R20 are connected in series, the other end of the tenth resistor R10 is connected to +12V, the twentieth resistor R20 is connected to the ground GND, and the level at the connection point of the tenth resistor R10 and the eighteenth resistor R18 is taken as the comparison level Vref, which serves as the reference value of the comparator in the power failure detection unit.

[0046] The analog value obtained after the rectification and differential amplification of the voltage value of the main power collected by the power failure detection unit is compared with the reference value through the comparator, and then transmitted to the controller in the form of digital signal.

[0047] The application sets the judgment value as the reference value of the comparator, and the comparator compares the analog value and the reference value to output high and low levels. The length of the high and low levels output by the comparator in the set period is used to determine whether the main power is powered off, and the controller switches the backup power in time.

[0048] The basic principle of power failure detection is as follows:

[0049] The power failure detection unit rectifies the AC signal of the main power to obtain a signal with only a positive half cycle. The set judgment value is used as the reference value of the comparator, and the signal output by the connection circuit after rectification is used as the analog value of the comparator. The comparator compares the analog value and the reference value to output high and low levels. Specifically, the length of the digital signal output by the comparator in the set period (the length of the high and low levels in the set period) is used to determine whether the main power is powered off. When the length of the high level in the set period is too long or too short, it is considered that the main power is powered off, and the controller switches the main power to the backup power in time.

[0050] For example, the frequency of the AC voltage as the power supply is 50 Hz, and the period is 20 ms. The main power is rectified to output a positive half cycle of a sine wave (a signal with only a positive half cycle), and then a differential amplifier circuit as the connection circuit is used to obtain a square wave. A judgment value is set so that the time occupied by the high and low levels in the half cycle is equal. The comparator compares the judgment value and the square wave. The high level is output when the square wave is greater than or equal to the judgment value, and the low level is output otherwise. It is considered that the main power is powered off when the length of the high level in the set period is too long or too short, or the relationship between the time of the high level and the time of the low level in the set period is used to determine whether the main power is powered off.

[0051] As another embodiment, the connection circuit in the power failure detection unit can also be a wire for connecting the output end of the rectifier bridge and the input end of the comparator. The wire is used to output the pulse waveform output by the rectifier bridge to the comparator.

[0052] Specifically, the power supply switching circuit (opto-isolating circuit) as the power supply switching unit (opto-isolating unit) is as follows: Figure 6As shown, one end of the eleventh resistor R11 is connected with +3.3V, the other end is connected with the 7th pin of the optocoupler U5, the 8th pin of the optocoupler U5 is connected with the MCU control pin OUT2, one end of the twelfth resistor R12 is connected with +3.3V, the other end is connected with the 5th pin of the optocoupler U5, the 6th pin of the optocoupler U5 is connected with the MCU control pin OUT1, one end of the thirteenth resistor R13 is connected with +3.3V, the other end is connected with the 3rd pin of the optocoupler U5, the 4th pin of the optocoupler U5 is connected with the MCU control pin OUT1. One end of the seventeenth resistor R17 is connected with +12V, the other end is connected with the 14th pin of the optocoupler U5, the 13th pin of the optocoupler U5 is connected with the output OUT-F and the nineteenth resistor R19, the other end of the nineteenth resistor R19 is connected with GND. The 12th pin of the optocoupler U5 is connected with the 9th pin of the optocoupler U5, the 11th pin of the optocoupler U5 is connected with GND, the 10th pin of the optocoupler U5 is connected with one end of the twenty-first resistor R21, the other end of the twenty-first resistor R21 is connected with +12V, the 9th pin of the optocoupler U5 is connected with the output OUT-Z and one end of the twenty-second resistor R22, the other end of the twenty-second resistor R22 is connected with GND.

[0053] The OUT-Z in the optocoupler isolation circuit is controlled by the two-way control pin OUT1 and OUT2 of the MCU, so as to avoid the simultaneous conduction of OUT-Z and OUT-F, and realize the hardware protection.

[0054] The control power converted by the power conversion circuit is used by the optocoupler isolation circuit.

[0055] The control signal (driving signal) output by the controller (MCU) in the optocoupler isolation circuit and the other end of the light-emitting diode in the optocoupler form a voltage difference (potential difference), so as to make the light-emitting diode conduct.

[0056] The control voltage provided by the power conversion unit cooperates with the driving signal output by the controller to drive the optocoupler isolation unit, and the driving signal output by the optocoupler isolation unit can drive the relay to be closed or turned off.

[0057] Specifically, the two-way AC220V high-speed automatic switching controller of the present application is used as a dual power switching circuit, which comprises a power conversion circuit as a power conversion unit, a power failure detection circuit as a power failure detection unit and a power switching circuit as a power switching unit.

[0058] The power conversion circuit converts the input main and standby power into 12V and 3.3V control power, which is used to supply power for the dual power switching module, and the circuit diagram is shown as Figure 2 and Figure 3 .

[0059] Among them, the power supply power failure detection circuit 1 in the power failure detection circuit, as shown in Figure 4 The main electric signal is converted into a pulse signal of 0~5V DC through a rectifier bridge, a differential amplification circuit and a comparison circuit; the power supply power failure detection circuit 2 in the power failure detection circuit, as shown in Figure 5 Provides a voltage reference for the comparison circuit; the circuit diagrams are shown in Figure 4 and Figure 5 .

[0060] Among them, the power supply switching circuit, i.e. the optical coupling isolation circuit, converts the 0~3.3V driving signal output by the single-chip microcomputer into a 0~12V driving signal, which is used to drive the solid-state relay, and the circuit diagram is shown in Figure 6 .

[0061] The application provides a double-path AC220V high-speed automatic switching controller which is accurate, stable, high-speed and has phase detection, wherein the main electric switching process is as follows:

[0062] a) After the main electric power is cut off, the power supply power failure detection circuit transmits the power-off signal to the MCU;

[0063] b) The MCU judges the main electric power cut-off by comparing the power-off signal with the normal signal;

[0064] c) The MCU outputs an instruction to the power supply switching circuit;

[0065] d) The power supply switching circuit controls the main electric solid-state relay to be disconnected, and simultaneously controls the standby electric relay to be turned on, and the switching is completed.

[0066] The standby electric switching process is as follows:

[0067] a) After the main electric power is turned on, the power supply power failure detection circuit transmits the power-on signal to the MCU;

[0068] b) The MCU judges the main electric power turn-on by comparing the power-on signal with the normal signal;

[0069] c) The MCU outputs an instruction to the power supply switching circuit;

[0070] d) The power supply switching circuit controls the standby electric solid-state relay to be disconnected, and simultaneously controls the main electric relay to be turned on, and the switching is completed.

[0071] The application has the following beneficial effects:

[0072] a) The switching time of the main and standby electric power in the application is less than 15ms;

[0073] b) The application can be applied to the situation that one path of commercial power and one path of inverter output are used, and the over-current protection caused by the phase difference during switching can be avoided.

[0074] The AC220V AC main electric power is converted into a pulse signal of 0~5V DC through a rectifier, a filter and a comparison circuitFigure 4 、 Figure 5 As shown in FIG. 1, the AC signal is converted into a pulse signal of 0-5V, as shown in FIG. 2, wherein the yellow waveform Ch1 in the figure is the converted waveform, and the blue waveform Ch2 is the waveform before conversion. Figure 7 and Figure 8 As shown in FIG. 2, the yellow waveform Ch1 in the figure is the converted waveform, and the blue waveform Ch2 is the waveform before conversion.

[0075] The single-chip microcomputer collects the pulse signal, judges the main power state by analyzing the high and low level time, thereby controlling the main and standby power solid-state relay switch, and realizing the main and standby power switching.

[0076] When the single-chip microcomputer detects that the main power is powered off, the main power solid-state relay is immediately controlled to be closed, so that the power-off detection time is from the main power being powered off to the main power solid-state relay control signal output. According to the detection time of the software writing, the theoretical detection time should be less than or equal to 8.5ms due to the different amplitudes of the main power (AC220V±10%). The actual detection time (actual power-off detection time) is Figure 9 , ,which is less than 7.8ms, and meets the design index. The waveform diagram is shown in FIG. 3. Figure 9

[0077] The main and standby power switching time is the process time of the output switching from the main power to the standby power, so that the output state is detected by the oscilloscope, and the time from the output power-off to the output power-on is measured. After 120 hours of continuous operation detection, the main and standby power actual switching time is Figure 10 , , is the power-on time, is the power-off time, and the main and standby power actual switching time is less than or equal to 14.5ms, which meets the design requirements. The waveform diagram is shown in FIG. 4. Figure 10

[0078] The present application mainly solves the problem of long switching time of the two-way AC220V power-off automatic switching, adopts the MCU real-time detection, and the solid-state relay switching technology to ensure that the power supply switching is completed within 15ms after power-off.

[0079] The traditional switching device is too slow, and mis-switching may occur in the low load condition. Meanwhile, the device does not have the phase detection function, and when the output is switched from the standby power to the main power, the over-current protection is easily triggered to cause the power supply to be cut off. Therefore, it is urgently needed to provide an accurate, stable and high-speed dual-power switching device.

[0080] An embodiment of a dual-power system:

[0081] A dual-power system, as shown in FIG. 5.​​​Figure 1 As shown, it includes a first input terminal L1 for connecting to the main power supply (constant power supply) as the primary power source. Figure 1 Terminal L1 in terminal block XT1), and the second input terminal L2 for connecting to the backup power supply (as a backup power source). Figure 1 Terminal L2 in terminal block XT1), and power supply terminal L (for output power supply) Figure 1 Terminal L in terminal block XT1), dual power supply switching circuit (i.e., set in...) Figure 1 The circuit board AP1 includes a dual power supply switching circuit, a first relay K1 connected between the first input terminal L1 and the power transmission terminal L, and a second relay K2 connected between the second input terminal L2 and the power transmission terminal L. The output terminals of the controller in the dual power supply switching circuit (including port Z and port F, where port Z includes a positive terminal Z+ and a negative terminal Z-, and port F includes a positive terminal F+ and a negative terminal F-) respectively control the opening or closing of the first relay K1 and the second relay K2. The first relay K1 and the second relay K2 are used to control the main / standby power switching.

[0082] The dual power supply switching circuit has been described in detail in one embodiment of the dual power supply switching circuit, and will not be repeated here.

[0083] The dual power supply system also includes a manual-automatic switching unit, which includes two double-pole double-throw switches. The first input terminal and the second input terminal are respectively connected to the two common terminals of the first double-pole double-throw switch. Two terminals on one side of the first double-pole double-throw switch are connected to the two common terminals of the second double-pole double-throw switch. Two terminals on the other side of the first double-pole double-throw switch are respectively connected to the output terminals of the first relay and the second relay. The first terminal of the two terminals on one side of the second double-pole double-throw switch is connected to the power transmission terminal, and the second terminal of the two terminals on the other side of the second double-pole double-throw switch is short-circuited to the first terminal.

[0084] Specifically, such as Figure 1 As shown, the manual-automatic switching unit includes two double-pole double-throw switches: a first double-pole double-throw switch S1 (first switch S1) and a second double-pole double-throw switch S2 (second switch S2). The side with the common terminals of the two double-pole double-throw switches is used as one side of the double-pole double-throw switch, and the other side with the common terminals of the two double-pole double-throw switches is used as the other side of the double-pole double-throw switch.

[0085] The two common terminals (common terminal 1 and common terminal 2) of the first switch S1 are connected with the first input terminal L1 and the second input terminal L2 respectively, the two terminals (terminal 1A and terminal 2A) on the same side of the two common terminals of the first switch S1 are connected with the first relay K1 and the second relay K2 respectively, the two terminals (terminal 1B and terminal 2B) on the other side of the first switch S1 are connected with the two common terminals (common terminal 1 and common terminal 2) of the second switch S2 and the one terminal (first terminal, i.e. terminal 1A in the second switch S2 on the same side of the two common terminals) of the second switch S2 on the other side (second terminal, i.e. terminal 2B in the second switch S2 on the other side of the two common terminals) is connected with the power supply terminal. Figure 1 The two common terminals (common terminal 1 and common terminal 2) of the first switch S1 are connected with the first input terminal L1 and the second input terminal L2 respectively, the two terminals (terminal 1A and terminal 2A) on the same side of the two common terminals of the first switch S1 are connected with the first relay K1 and the second relay K2 respectively, the two terminals (terminal 1B and terminal 2B) on the other side of the first switch S1 are connected with the two common terminals (common terminal 1 and common terminal 2) of the second switch S2 and the one terminal (first terminal, i.e. terminal 1A in the second switch S2 on the same side of the two common terminals) of the second switch S2 on the other side (second terminal, i.e. terminal 2B in the second switch S2 on the other side of the two common terminals) is connected with the power supply terminal. Figure 1 Figure 1 The terminal on the same side of the common terminal 1 is terminal 1A and the terminal on the other side is terminal 1B; the terminal on the same side of the common terminal 2 is terminal 2A and the terminal on the other side is terminal 2B.

[0086] The two terminals on the same side of the second switch S2 are defined as the first terminal and the second terminal in the same direction. That is, the first terminal on the same side of the second switch S2 and the second terminal on the other side of the first switch S1 are not on the same side and the order in the same direction is also reversed.

[0087] When the common terminal 1 and the common terminal 2 of the first switch S1 and the terminal 1A and the terminal 2A on the same side of the first switch S1 are connected, the common terminal 1 and the common terminal 2 of the first switch S1 and the terminal 1B and the terminal 2B on the other side of the first switch S1 are disconnected, at this time, the first switch S1 is opened to automatically control the switching of the main power supply and the standby power supply.

[0088] When the common terminal 1 and the common terminal 2 of the first switch S1 and the terminal 1B and the terminal 2B on the other side of the first switch S1 are connected, the common terminal 1 and the common terminal 2 of the first switch S1 and the terminal 1A and the terminal 2A on the same side of the first switch S1 are disconnected, at the same time, when the common terminal 1 and the common terminal 2 of the second switch S2 and the terminal 1A and the terminal 2A on the same side of the second switch S2 are connected, the second switch S2 is manually switched to the main power supply, when the common terminal 1 and the common terminal 2 of the second switch S2 and the terminal 1B and the terminal 2B on the other side of the second switch S2 are connected, the second switch S2 is manually switched to the standby power supply.

Claims

1. A dual power supply system comprising a first input terminal for connecting a main power supply as a main power supply, a second input terminal for connecting a backup power supply as a backup power supply, and a power output terminal for outputting a power supply, characterized by, The double power supply switching circuit further comprises a manual-automatic switching unit, the manual-automatic switching unit comprises two double-pole double-throw switches, the first input end and the second input end are connected to two common terminals of the first double-pole double-throw switch, two terminals on one side of the first double-pole double-throw switch are connected to two common terminals of the second double-pole double-throw switch, and two terminals on the other side of the first double-pole double-throw switch are connected to the output terminals of the first relay and the second relay respectively; a first terminal of two terminals on one side of the second double-pole double-throw switch is connected to the power supply end, and a second terminal of two terminals on the other side of the second double-pole double-throw switch is short-circuited with the first terminal.

2. The dual power system of claim 1, wherein, The double power supply switching circuit comprises a power failure detection unit for detecting whether the main power supply in the double power supply is powered off, the power failure detection unit comprises a rectifier bridge, the input end of the rectifier bridge is used for being connected with the main power supply, the output end of the rectifier bridge is connected with the input end of a comparator through a connection circuit for outputting a pulse waveform, the other input end of the comparator is used for inputting a reference value, and the output end of the comparator is connected with a controller, the controller is used for controlling the switching of the main power supply and the standby power supply in the double power supply according to the output of the comparator.

3. The dual power system of claim 2, wherein, The connection circuit comprises an amplification circuit.

4. The dual power system of claim 3, wherein, The amplification circuit is a differential amplification circuit, the output end of the rectifier bridge is connected with the input end of the differential amplification circuit through a voltage dividing circuit for outputting a differential signal, and the output end of the differential amplification circuit is connected with the input end of the comparator.

5. The dual power system of claim 4, wherein, The voltage dividing circuit comprises voltage dividing resistors connected in series between the output ends of the rectifier bridge, and the two sides of the voltage dividing resistors are connected with the input end of the differential amplification circuit as the output of the voltage dividing circuit.

6. The dual power system of claim 2, wherein, A plurality of resistors connected in series are further included, and the connection points between any two adjacent resistors are connected with the input end of the comparator to output the voltage level at the connection points of the two adjacent resistors as the reference value to the comparator.

7. The dual power system of claim 2, wherein, The controller outputs a control signal for switching the main power supply and the standby power supply through an optical coupling isolation circuit.

8. The dual power system of claim 7, wherein, The power supply conversion unit further comprises a conversion circuit for converting the first power supply into a second power supply, the second power supply is connected with the controller through the light-emitting side of an optical coupling in the optical coupling isolation circuit, and the first power supply is connected with the output end of the controller for outputting the control signal through the coupling side of the optical coupling.

9. The dual power system of claim 8, wherein, ​

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