Power switching circuit of an LED lighting device and its control method

Abstract

The present invention provides a power supply switching circuit for an LED lighting device and a control method thereof. In the power supply switching circuit, a plurality of input branches, a bias power supply circuit, and an energy storage circuit are sequentially arranged from high to low in priority; the access of the input power supply is only related to its own priority and whether the voltage is greater than a preset threshold value. The circuit setting is more flexible, and the adaptable power supplies are more extensive; at the same time, the present invention is provided with a switching control circuit connected to each other, which ensures that only one input power supply is connected at the same time, avoiding short circuits caused by multiple input power supplies being connected and resulting in unstable operation of the lighting device; in addition, by flexibly adjusting the preset threshold values of each detection circuit, a power supply higher or lower than the current priority power supply can be connected at any time according to requirements, greatly improving the flexibility of switching; and thermal switching can be realized, and there will be no power failure of the lighting device during the switching process, further improving the working stability of the lighting device.

Description

Technical Field

[0001] The present invention relates to the technical field of lighting, and more particularly, to a power supply switching circuit and a control method thereof for an LED lighting device. Background Art

[0002] Lighting devices are generally powered by multiple power supplies such as mains power and batteries. When one of the power supplies is powered off, the power supply switching circuit switches to enable the lighting device to be powered by other power supplies, thereby ensuring the stable operation of the lighting device.

[0003] In order to be able to be continuously used for a long time, the power supply switching circuit generally preferentially uses mains power to supply power to the light source. When the mains power is powered off, the power supply switching circuit switches to a battery or other power supply for power supply.

[0004] However, when multiple power supplies are used for power supply at the same time, since the multiple power supply input terminals are directly connected to the light source, it will cause short circuits of the multiple power supply input terminals, resulting in unstable operation of the lighting device.

[0005] In addition, when the mains power is powered off and the existing power supply switching circuit is used to switch to other power supplies for power supply, there will be a short-term power-off phenomenon during the switching process, resulting in unstable operation of the lighting device.

[0006] An existing patent document (CN 112769225 A) discloses a lighting device, a power supply switching circuit and a power supply switching method for a lighting device. The power supply switching circuit therein ensures a priority relationship between multiple power supply input circuits, and at the same time, avoids current flowing back from the light source to the high-priority power supply input circuit after the power supply connected to the low-priority power supply input circuit supplies power to the light source, improving the working stability of the lighting device. However, the power supply switching flexibility of this solution is not high. On the one hand, only when all high-priority power supplies are disconnected can low-priority power supplies be connected, and at the same time, the high-priority power supply voltage must be greater than the low-priority power supply voltage to be preferentially used, and it is impossible to switch arbitrarily between power supplies of different priorities; on the other hand, this existing technology cannot achieve hot switching of power supplies of different priorities, and it is impossible to switch power supplies during the normal operation of the lighting device. There will still be a power-off phenomenon after power-off switching, and it will still cause unstable operation of the lighting device. Summary of the Invention

[0007] In order to overcome the defects of low power supply switching flexibility and inability to achieve hot switching in the above-mentioned existing technologies, the present invention provides a power supply switching circuit and a control method thereof for an LED lighting device. When a high-priority input power supply is connected, it is not affected by low-priority power supplies, and the switching flexibility is high. Moreover, during the normal operation of the lighting device, a power supply higher or lower than the current priority power supply can be connected at any time to achieve hot switching, and there will be no power-off phenomenon of the lighting device, further improving the working stability of the lighting device.

[0008] To solve the above technical problems, the technical solution of the present invention is as follows:

[0009] A power supply switching circuit for an LED lighting device, comprising: a plurality of input branches arranged in order of decreasing priority from high to low, as well as a bias power supply circuit and an energy storage circuit;

[0010] Each of the input branches includes: an input power supply, a detection circuit, a switching control circuit, and a switching circuit;

[0011] Inside each of the input branches, the output terminal of the input power supply is electrically connected to the input terminals of the detection circuit and the switching circuit respectively; the switching control circuit receives a first electrical signal output from the output terminal of the detection circuit; the first output terminal of the switching control circuit is electrically connected to the control terminal of the switching circuit; the output terminal of the switching circuit serves as the output terminal of the corresponding input branch;

[0012] The switching control circuit with a lower priority also receives the first electrical signals output from the detection circuits of each higher priority respectively;

[0013] Each of the switching control circuits also receives a second electrical signal output from the second output terminal of other switching control circuits respectively;

[0014] The output terminal of each of the input power supplies is also electrically connected to the input terminal of the bias power supply circuit respectively, and the output terminal of the bias power supply circuit provides a bias voltage for each detection circuit and switching control circuit respectively;

[0015] The energy storage circuit is connected in parallel with the output terminal of each of the input branches; the output terminal of each of the input branches is electrically connected to the power supply terminal of the lighting device respectively.

[0016] Preferably, the types of the input power supply include: mains power, storage battery, AC-DC power supply, DC-DC power supply, and battery box.

[0017] Preferably, each of the detection circuits includes: a comparator, first to fifth resistors, first and second capacitors, a zener diode, and a switch;

[0018] The non-inverting input terminal of the comparator is connected to one end of the first resistor, one end of the second resistor, one end of the first capacitor, one end of the third resistor, and one end of the switch respectively; the other end of the first resistor is connected to the input power supply; the other ends of the second resistor, the first capacitor, and the switch are all grounded; the other end of the third resistor is connected to one end of the second capacitor and the output terminal of the comparator respectively; the other end of the second capacitor is grounded;

[0019] The inverting input terminals of the comparator are respectively connected to the cathode of the voltage stabilizing diode and one end of the fourth resistor; the anode of the voltage stabilizing diode is grounded; the other end of the fourth resistor is connected to the output terminal of the bias power supply circuit;

[0020] The output terminal of the comparator is connected to one end of the fifth resistor and serves as the output terminal of the detection circuit to output a first electrical signal; the other end of the fifth resistor is connected to the output terminal of the bias power supply circuit;

[0021] The positive power supply terminal of the comparator is connected to the output terminal of the bias power supply circuit, and the negative power supply terminal is grounded.

[0022] Preferably, each of the switching control circuits includes: a sixth to a twelfth resistor, a first and a second NMOS transistor, an NPN transistor, a third capacitor, and a first diode;

[0023] One end of the sixth resistor is connected to the output terminal of the detection circuit of the corresponding input branch for receiving the first electrical signal inside the input branch; the other end of the sixth resistor is respectively connected to the drain of the first NMOS transistor, one end of the seventh resistor, and the base of the NPN transistor; the source of the first NMOS transistor, the other end of the seventh resistor, and the emitter of the NPN transistor are all grounded;

[0024] The gate of the first NMOS transistor is respectively connected to one end of the eighth resistor, one end of the ninth resistor, and one end of the third capacitor, and the other end of the eighth resistor is respectively connected to the second electrical signal output from the second output terminal of other switching control circuits; the other ends of the ninth resistor and the third capacitor are both grounded;

[0025] The collector of the NPN transistor is connected to the control terminal of the switch circuit and serves as the first output terminal of the switching control circuit;

[0026] The collector of the NPN transistor is also connected to the negative electrode of the first diode, and the positive electrode of the first diode is respectively connected to the gate of the second NMOS transistor, one end of the tenth resistor, and one end of the eleventh resistor; the other end of the tenth resistor is connected to the output terminal of the bias power supply circuit; the source of the second NMOS transistor and the other end of the eleventh resistor are both grounded;

[0027] The drain of the second NMOS transistor is respectively connected to one end of the twelfth resistor and the other end of the eighth resistor in other switching control circuits, and serves as the second output terminal of the switching control circuit to output a second electrical signal; the other end of the twelfth resistor is connected to the output terminal of the bias power supply circuit.

[0028] Preferably, except for the switching control circuit with the highest priority, other switching control circuits further include: a thirteenth and a fourteenth resistor, and a third NMOS transistor;

[0029] The gate of the third NMOS transistor is respectively connected to one end of the thirteenth resistor and one end of the fourteenth resistor. The other end of the thirteenth resistor is respectively connected to the output terminals of all detection circuits with a higher priority than this switching control circuit, for receiving the first electrical signal of the high-priority input branch; the source of the third NMOS transistor and the other end of the fourteenth resistor are both grounded;

[0030] The drain of the third NMOS transistor is connected to the other end of the sixth resistor.

[0031] Preferably, for each of the switching control circuits, when the second electrical signal of other switching control circuits is input to the eighth resistor of this switching control circuit, and when the first electrical signal of the high-priority input branch is input to the thirteenth resistor of this switching control circuit, the signal is input after passing through a forward diode.

[0032] Preferably, each of the switching circuits includes: the fifteenth and sixteenth resistors, and the fourth and fifth NMOS transistors;

[0033] The source of the fourth NMOS transistor is connected to the input power supply and serves as the input terminal of the switching circuit;

[0034] The gate of the fourth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The other end of the fifteenth resistor is respectively connected to the drain of the fourth NMOS transistor and the drain of the fifth NMOS transistor; the other end of the sixteenth resistor is connected to the first output terminal of the switching control circuit and serves as the control terminal of the switching circuit;

[0035] The gate of the fifth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The source of the fifth NMOS transistor is connected to the input terminal of the energy storage circuit and serves as the output terminal of the switching circuit.

[0036] Preferably, the bias power supply circuit includes: a TX4139 power chip, the seventeenth to twenty-first resistors, the fourth to ninth capacitors, a second diode, and an inductor;

[0037] The ILIM pin of the TX4139 power chip is connected to one end of the seventeenth resistor; the other end of the seventeenth resistor is respectively connected to one end of the fourth capacitor, one end of the fifth capacitor, the VIN pin of the TX4139 power chip, one end of the eighteenth resistor, and the output terminals of all input power supplies. The other end of the seventeenth resistor serves as the input terminal of the bias power supply circuit, and each input power supply inputs the power signal after passing through a forward diode; the other end of the eighteenth resistor is connected to the EN pin of the TX4139 power chip; the other ends of the fourth capacitor and the fifth capacitor are both grounded;

[0038] The SW pin of the TX4139 power chip is respectively connected to one end of the sixth capacitor, one end of the inductor, and the cathode of the second diode. The other end of the sixth capacitor is connected to one end of the nineteenth resistor, and the other end of the nineteenth resistor is connected to the BS pin of the TX4139 power chip; the anode of the second diode is grounded; the other end of the inductor is respectively connected to one ends of the seventh to ninth capacitors, one end of the twentieth resistor, and the detection circuit and the switching control circuit, and serves as the output terminal of the bias power supply circuit to output a +12V bias voltage;

[0039] The other end of the seventh capacitor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twentieth resistor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twenty-first resistor, and the other ends of the eighth and ninth capacitors are all grounded;

[0040] The POK pin of the TX4139 power chip is left open, and the GND pin of the TX4139 power chip is grounded.

[0041] Preferably, the energy storage circuit includes a plurality of energy storage capacitors connected in parallel. One end of each energy storage capacitor is respectively connected to the output terminals of all input branches and the power supply terminal of the lighting device; the other end of each energy storage capacitor is grounded.

[0042] The present invention also provides a method for controlling a power switching circuit of an LED lighting device. Based on the above-mentioned power switching circuit of the LED lighting device, it includes the following steps:

[0043] For each of the input branches, when an input power supply is connected and the detection circuit detects that the voltage input by the input power supply is greater than or equal to a preset threshold, the detection circuit outputs a high-level first electrical signal to the switching control circuit and all switching control circuits with a lower priority than this input branch; when the switching control circuit of this input branch receives the high-level first electrical signal and the second electrical signals output by other switching control circuits are all low-level, it outputs a high-level second electrical signal to control the switch circuit to open, so that the input power supply supplies power to the energy storage circuit and the lighting device. At the same time, all switching control circuits with a lower priority than this input branch receive the high-level first electrical signal and control all switch circuits with a lower priority than this input branch to close;

[0044] S1: Automatic power-off switching: When the input power supply with a higher priority loses power, the detection circuit of the input branch where the power is lost detects that the input power supply is disconnected. At this time, the detection circuit outputs a low-level first electrical signal to the switching control circuit and all switching control circuits with a lower priority than this input branch; when the switching control circuit of this input branch receives the low-level first electrical signal, it controls the switch circuit to close, and at the same time, this switching control circuit outputs a low-level second electrical signal to the switching control circuits of other input branches;

[0045] Judge whether other input power supplies are connected in turn from high to low priority, control other input power supplies with higher priority to supply power to the energy storage circuit and the lighting device, and at the same time turn off all the switch circuits of other input branches to complete the automatic power-off switching;

[0046] S2: Manual switching: During the normal operation of the lighting device, according to the preset requirements, manually increase the preset threshold of the detection circuit of the current input branch, so that the detection circuit of the current input branch outputs a first electrical signal of low level, and the switching control circuit outputs a second electrical signal of low level, thereby shielding the input power supply of the current input branch;

[0047] At the same time, lower the preset threshold of the detection circuit of the input branch to be connected, so that the detection circuit of the input branch to be connected outputs a first electrical signal of high level; after the switching control circuit of the input branch to be connected receives the first electrical signal of high level and the second electrical signal of low level of the current input branch, control the switch circuit of the input branch to be connected to open, thereby connecting the input power supply of the input branch to be connected to complete the manual switching.

[0048] Compared with the prior art, the beneficial effect of the technical solution of the present invention is:

[0049] The present invention provides a power supply switching circuit and a control method thereof for an LED lighting device. The access of the input power supply is only related to its own priority and whether the voltage is greater than the preset threshold. The power supply voltage of the higher priority can be greater than, less than or equal to the voltage of the lower priority. The circuit setting is more flexible and the adaptable power supply is more extensive;

[0050] Secondly, the present invention also sets a switching control circuit to ensure that at most one input power supply can be connected at the same time, avoiding short circuits caused by multiple input power supplies being connected, resulting in unstable operation of the lighting device;

[0051] In addition, during the normal operation of the lighting device, by flexibly adjusting the preset thresholds of each detection circuit, a power supply higher or lower than the current priority power supply can be connected at any time according to the requirements, greatly improving the flexibility of switching; at the same time, hot switching is realized, and there will be no power-off phenomenon of the lighting device during the switching process, further improving the working stability of the lighting device. Description of the Drawings

[0052] Figure 1 It is the overall architecture diagram of a power supply switching circuit for an LED lighting device provided in Embodiment 1.

[0053] Figure 2 It is the circuit structure diagram of the first input branch provided in Embodiment 2.

[0054] Figure 3The circuit structure diagram of the second input branch provided in Embodiment 2

[0055] Figure 4 The circuit structure diagram of the third input branch provided in Embodiment 2

[0056] Figure 5 The circuit structure diagram of the bias power supply circuit provided in Embodiment 2

[0057] Figure 6 The circuit structure diagram of the energy storage circuit provided in Embodiment 2 Detailed implementation manners

[0058] The accompanying drawings are only for illustrative purposes and should not be construed as limitations on this patent;

[0059] To better illustrate this embodiment, some components in the accompanying drawings are omitted, enlarged or reduced, and do not represent the dimensions of actual products;

[0060] For those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0061] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0062] Embodiment 1

[0063] As Figure 1 shown, this embodiment provides a power supply switching circuit for an LED lighting device, including: a plurality of input branches arranged in descending order of priority, as well as a bias power supply circuit and an energy storage circuit;

[0064] Each of the input branches includes: an input power supply, a detection circuit, a switching control circuit, and a switching circuit; the types of the input power supply include: mains power, a storage battery, an AC-DC power supply, a DC-DC power supply, and a battery box;

[0065] Inside each of the input branches, the output end of the input power supply is electrically connected to the input ends of the detection circuit and the switching circuit respectively; the switching control circuit receives a first electrical signal output from the output end of the detection circuit; the first output end of the switching control circuit is electrically connected to the control end of the switching circuit; the output end of the switching circuit serves as the output end of the corresponding input branch;

[0066] The switching control circuit with a lower priority also receives the first electrical signals output from the detection circuits of each higher priority respectively;

[0067] Each of the switching control circuits also receives second electrical signals output from the second output ends of other switching control circuits respectively;

[0068] The output terminal of each of the input power supplies is also electrically connected to the input terminal of the bias power supply circuit respectively, and the output terminal of the bias power supply circuit provides bias voltages for each detection circuit and the switching control circuit respectively;

[0069] The energy storage circuit is connected in parallel with the output terminal of each input branch; the output terminal of each input branch is electrically connected to the power supply terminal of the lighting device respectively.

[0070] In the specific implementation process, in Figure 1 In the circuit shown, there are N input branches in total from the first to the Nth, where N is a positive integer; the N input branches are arranged in descending order of priority, the priority of the first input branch is higher than that of the second input branch, the priority of the second input branch is higher than that of the third input branch, and so on; the working scenarios and circuit working processes of the power supply switching circuit in this embodiment mainly include:

[0071] 1) When the first input power supply is connected, the first detection circuit detects that there is power input from the first input power supply, and the input voltage of the first power supply is higher than the preset threshold of the first detection circuit, the first detection circuit outputs a high-level first electrical signal to the first switching control circuit and all the subsequent switching control circuits;

[0072] When the first switching control circuit receives the high-level signal output by the first detection circuit, it controls the first switch circuit to open, so that the first input power supply supplies power to the energy storage circuit and the lighting device. At the same time, all the subsequent switching control circuits receive the high-level signal output by the first detection circuit and control all the subsequent switch circuits to close;

[0073] 2) When the first input power supply is not connected or the voltage is lower than the preset threshold of the first detection circuit, it is then judged whether the second input power supply is connected;

[0074] Similar to the access process of the first input power supply, when the second input power supply is connected, the second detection circuit detects that there is power input from the second input power supply, and the input voltage of the second power supply is higher than the preset threshold of the second detection circuit, the second detection power supply outputs a high-level first electrical signal to the second switching control circuit and all the subsequent switching control circuits after the second one. When the second switching control circuit receives the high-level signal output by the second detection circuit, it controls the second switch circuit to open, so that the second input power supply supplies power to the energy storage circuit and the lighting device. At the same time, all the subsequent switching control circuits after the second one receive the high-level signal output by the second detection circuit and control all the subsequent switch circuits after the second one to close;

[0075] 3) After the first input power supply is connected, it takes precedence over the second input power supply, the second input power supply takes precedence over the third input power supply, and so on. When the first input power supply is connected to the mains power, that is, the mains power takes precedence over other power supplies, the mains power is preferentially used for power supply;

[0076] 4) When multiple power supplies are connected simultaneously and the first input power supply (mains power) loses power midway, it is possible to switch to other power supplies. The first detection circuit detects the disconnection of the first input power supply and outputs a first electrical signal of low level to the first switching control circuit and all subsequent switching control circuits. When the first switching control circuit receives the low-level signal output by the first detection circuit, it controls the first switch circuit to close. After the first switch circuit is closed, the first switching control circuit outputs a second electrical signal of low level to all other switching control circuits;

[0077] When other switching control circuits receive the low-level signal from the first switching control circuit, they will first determine whether the second input power supply has power connected. If there is power connected, the second switching control circuit controls the second switch circuit to open. If there is no power connected, the second switch circuit remains closed and determines whether the third input power supply has power connected, and so on;

[0078] Since the switching control circuit will only open the corresponding switch circuit for power connection when all second electrical signals are low level and the first electrical signal of the corresponding input branch is high level, when the high-priority power supply (the first input power supply) is switched to the low-priority power supply (the second input power supply), the connection between the high-priority power supply and the lighting device is preferably closed (the closing method can be actively or passively disconnecting the power connection, and raising the preset threshold of the high-priority detection circuit for shielding), and then the connection between the low-priority power supply and the lighting device is opened, avoiding short circuit caused by the high-priority power supply and the low-priority power supply being connected to the light source simultaneously, which may cause unstable operation of the lighting device;

[0079] 5) The circuit in this embodiment can also perform manual switching. During the normal operation of the lighting device, according to the preset requirements, the preset threshold of the detection circuit of the current input branch is manually raised, so that the detection circuit of the current input branch outputs a first electrical signal of low level, and the switching control circuit outputs a second electrical signal of low level, thereby shielding the input power supply of the current input branch;

[0080] At the same time, the preset threshold of the detection circuit of the input branch to be connected is lowered, so that the detection circuit of the input branch to be connected outputs a first electrical signal of high level; after the switching control circuit of the input branch to be connected receives the high-level first electrical signal and the low-level second electrical signal of the current input branch, it controls the switch circuit of the input branch to be connected to open, thereby connecting the input power supply of the input branch to be connected and completing the manual switching, realizing the connection of any priority power supply;

[0081] Since there is some power stored in the energy storage circuit, during the switching, the lighting device is powered by the energy storage circuit, so there will be no short-term power failure phenomenon, nor will it cause the problem of unstable operation of the lighting device, thus realizing hot switching;

[0082] In this embodiment, the access of the input power supply is only related to its own priority and whether the voltage is greater than the preset threshold of the detection circuit. The voltage of the high-priority power supply can be set arbitrarily and has no relation with the voltage of the low-priority power supply. That is, the voltage of the high-priority power supply can be greater than, less than or equal to the voltage of the low-priority power supply. The circuit setting is more flexible and the adaptable power supplies are more extensive.

[0083] Secondly, this embodiment also sets a switching control circuit to ensure that at most only one input power supply can be accessed at the same time, avoiding short circuits caused by multiple input power supplies being accessed and resulting in unstable operation of the lighting device.

[0084] In addition, during the normal operation of the lighting device, by flexibly adjusting the preset thresholds of each detection circuit, a power supply higher or lower than the current priority power supply can be accessed at any time according to requirements. The flexibility of switching is greatly improved, and at the same time, hot switching is realized, improving the working stability of the lighting device.

[0085] Embodiment 2

[0086] This embodiment provides a power supply switching circuit for an LED lighting device, including: a plurality of input branches arranged in order of decreasing priority from high to low, and a bias power supply circuit and an energy storage circuit;

[0087] Each of the input branches includes: an input power supply, a detection circuit, a switching control circuit, and a switching circuit; the types of the input power supply include: mains power, battery, AC-DC power supply, DC-DC power supply, and battery box;

[0088] Inside each of the input branches, the output end of the input power supply is electrically connected to the input ends of the detection circuit and the switching circuit respectively; the switching control circuit receives the first electrical signal output from the output end of the detection circuit; the first output end of the switching control circuit is electrically connected to the control end of the switching circuit; the output end of the switching circuit serves as the output end of the corresponding input branch;

[0089] The switching control circuit with a lower priority also receives the first electrical signals output from each detection circuit with a higher priority respectively;

[0090] Each of the switching control circuits also receives the second electrical signals output from the second output ends of other switching control circuits respectively;

[0091] The output end of each of the input power supplies is also electrically connected to the input end of the bias power supply circuit respectively, and the output end of the bias power supply circuit provides bias voltages for each detection circuit and switching control circuit respectively;

[0092] The energy storage circuit is connected in parallel with the output end of each of the input branches; the output end of each input branch is electrically connected to the power supply end of the lighting device;

[0093] Each of the detection circuits includes: a comparator, first to fifth resistors, first and second capacitors, a zener diode, and a switch;

[0094] The non-inverting input terminal of the comparator is respectively connected to one end of the first resistor, one end of the second resistor, one end of the first capacitor, one end of the third resistor, and one end of the switch; the other end of the first resistor is connected to the input power supply; the other ends of the second resistor, the first capacitor, and the switch are all grounded; the other end of the third resistor is respectively connected to one end of the second capacitor and the output terminal of the comparator; the other end of the second capacitor is grounded;

[0095] The inverting input terminal of the comparator is respectively connected to the cathode of the zener diode and one end of the fourth resistor; the anode of the zener diode is grounded; the other end of the fourth resistor is connected to the output terminal of the bias power supply circuit;

[0096] The output terminal of the comparator is connected to one end of the fifth resistor and serves as the output terminal of the detection circuit to output a first electrical signal; the other end of the fifth resistor is connected to the output terminal of the bias power supply circuit;

[0097] The positive power supply terminal of the comparator is connected to the output terminal of the bias power supply circuit, and the negative power supply terminal is grounded;

[0098] Each of the switching control circuits includes: sixth to twelfth resistors, first and second NMOS transistors, an NPN transistor, a third capacitor, and a first diode;

[0099] One end of the sixth resistor is connected to the output terminal of the detection circuit of the corresponding input branch for receiving the first electrical signal inside the input branch; the other end of the sixth resistor is respectively connected to the drain of the first NMOS transistor, one end of the seventh resistor, and the base of the NPN transistor; the source of the first NMOS transistor, the other end of the seventh resistor, and the emitter of the NPN transistor are all grounded;

[0100] The gate of the first NMOS transistor is respectively connected to one end of the eighth resistor, one end of the ninth resistor, and one end of the third capacitor, and the other end of the eighth resistor is respectively connected to the second electrical signal output from the second output terminal of other switching control circuits; the other ends of the ninth resistor and the third capacitor are both grounded;

[0101] The collector of the NPN transistor is connected to the control terminal of the switch circuit and serves as the first output terminal of the switching control circuit;

[0102] The collector of the NPN transistor is also connected to the negative electrode of the first diode, and the positive electrode of the first diode is respectively connected to the gate of the second NMOS transistor, one end of the tenth resistor, and one end of the eleventh resistor; the other end of the tenth resistor is connected to the output end of the bias power supply circuit; the source of the second NMOS transistor and the other end of the eleventh resistor are both grounded;

[0103] The drain of the second NMOS transistor is respectively connected to one end of the twelfth resistor and the other end of the eighth resistor in other switching control circuits, and serves as the second output end of the switching control circuit to output a second electrical signal; the other end of the twelfth resistor is connected to the output end of the bias power supply circuit;

[0104] In this embodiment, except for the switching control circuit with the highest priority, other switching control circuits further include: a thirteenth and a fourteenth resistor, and a third NMOS transistor;

[0105] The gate of the third NMOS transistor is respectively connected to one end of the thirteenth resistor and one end of the fourteenth resistor. The other end of the thirteenth resistor is respectively connected to the output ends of all detection circuits with a higher priority than this switching control circuit, for receiving the first electrical signal of the high-priority input branch; the source of the third NMOS transistor and the other end of the fourteenth resistor are both grounded;

[0106] The drain of the third NMOS transistor is connected to the other end of the sixth resistor;

[0107] For each switching control circuit, when the second electrical signal of other switching control circuits is input to the eighth resistor of this switching control circuit, and the first electrical signal of the high-priority input branch is input to the thirteenth resistor of this switching control circuit, the signal is input after passing through a forward diode;

[0108] Each switching circuit includes: a fifteenth and a sixteenth resistor, and a fourth and a fifth NMOS transistor;

[0109] The source of the fourth NMOS transistor is connected to the input power supply and serves as the input end of the switching circuit;

[0110] The gate of the fourth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The other end of the fifteenth resistor is respectively connected to the drain of the fourth NMOS transistor and the drain of the fifth NMOS transistor; the other end of the sixteenth resistor is connected to the first output end of the switching control circuit and serves as the control end of the switching circuit;

[0111] The gate of the fifth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The source of the fifth NMOS transistor is connected to the input end of the energy storage circuit and serves as the output end of the switching circuit;

[0112] The bias power supply circuit includes: a TX4139 power chip, the seventeenth to the twenty-first resistors, the fourth to the ninth capacitors, a second diode, and an inductor;

[0113] One end of the ILIM pin of the TX4139 power chip is connected to one end of the seventeenth resistor; the other end of the seventeenth resistor is respectively connected to one end of the fourth capacitor, one end of the fifth capacitor, the VIN pin of the TX4139 power chip, one end of the eighteenth resistor, and the output terminals of all input power supplies. The other end of the seventeenth resistor serves as the input terminal of the bias power supply circuit, and each input power supply inputs a power signal after passing through a forward diode; the other end of the eighteenth resistor is connected to the EN pin of the TX4139 power chip; the other ends of the fourth capacitor and the fifth capacitor are both grounded;

[0114] The SW pin of the TX4139 power chip is respectively connected to one end of the sixth capacitor, one end of the inductor, and the cathode of the second diode. The other end of the sixth capacitor is connected to one end of the nineteenth resistor, and the other end of the nineteenth resistor is connected to the BS pin of the TX4139 power chip; the anode of the second diode is grounded; the other end of the inductor is respectively connected to one end of the seventh to the ninth capacitors, one end of the twentieth resistor, and a detection circuit and a switching control circuit, and serves as the output terminal of the bias power supply circuit, outputting a bias voltage of +12V;

[0115] The other end of the seventh capacitor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twentieth resistor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twenty-first resistor, and the other ends of the eighth and ninth capacitors are all grounded;

[0116] The POK pin of the TX4139 power chip is left unconnected, and the GND pin of the TX4139 power chip is grounded;

[0117] The energy storage circuit includes a plurality of energy storage capacitors connected in parallel. One end of each energy storage capacitor is respectively connected to the output terminals of all input branches and the power supply terminal of the lighting device; the other end of each energy storage capacitor is grounded.

[0118] In the specific implementation process, this embodiment takes the power supply switching circuit with 3 input branches as an example for illustration; as Figures 2 to 4 shown, they are respectively the circuit structure diagrams of the first to the third input branches; the input power supplies of the three input branches are respectively the commercial power, the storage battery, and the DC-DC power supply, and the priorities of the first to the third input branches decrease in sequence;

[0119] As Figure 5 and 6As shown, they are respectively the circuit structure diagrams of the bias power supply circuit and the energy storage circuit;

[0120] In this embodiment, the switch circuit is used to connect or disconnect the input power supply from the lighting device and is controlled by the switching control circuit; the detection circuit is used to detect whether the input power supply voltage is greater than a preset threshold; the switching control circuit is used to control the switch circuit to conduct or disconnect; the energy storage capacitor is used to store electricity; the bias power supply circuit is used to provide a stable bias voltage to the switching circuit and the detection circuit.

[0121] In this embodiment, "DC1-EN, DC2-EN, and DC3-EN" are respectively the first electrical signals of three input branches. When they are at a high level, it means that the corresponding input power supply voltage is greater than or equal to the preset threshold of the detection circuit; when they are at a low level, it means that the corresponding input power supply voltage is lower than the preset threshold of the detection circuit.

[0122] "DC1_Off_Rst, DC2_Off_Rst, and DC3_Off_Rst" are respectively the second electrical signals of three input branches. When they are at a high level, it means that the corresponding switch circuit is conducting; when they are at a low level, it means that the corresponding switch circuit is cut off.

[0123] When the first input power supply is connected, the first detection circuit detects whether the first power supply voltage is greater than the preset threshold. If the first power supply voltage is greater than or equal to the preset threshold, DC1-EN outputs a high level. If the first power supply voltage is less than the preset value (the first input power supply is disconnected or the preset threshold is manually increased), DC1-EN outputs a low level.

[0124] a): When the first switching control circuit receives a high level output from DC1-EN, if one of DC2_Off_Rst or DC3_Off_Rst is at a high level at this time, Q6 is made to be in a conducting state, so that Q9 is in a cut-off state, so that the first switch circuit remains in a cut-off state, waiting for both DC2_Off_Rst and DC3_Off_Rst to be at a low level, then Q6 is made to be in a cut-off state, so that Q9 is in a conducting state, so that the first switch circuit conducts and connects the first input power supply for power supply; at this time, Q15 is in a cut-off state, so that DC1_Off_Rst is at a high level.

[0125] This design of the switching control circuit enables only one input power supply to be connected at the same time, avoiding short circuits caused by multiple power supplies being connected simultaneously and unstable operation of the lighting device.

[0126] b): When the first switching control circuit receives a low level output of DC1-EN, regardless of whether DC2_Off_Rst and DC3_Off_Rst are high level or low level, Q9 is in a cut-off state, thus making the first switching circuit in a cut-off state, and at the same time making Q15 in a conducting state, so that DC1_Off_Rst outputs a low level;

[0127] c): When the second switching control circuit receives a high level output of DC1-EN, regardless of the state of DC2-EN, Q1 is in a conducting state, thus making Q10 in a cut-off state, so that the second switching circuit is in a cut-off state, and at the same time making Q16 in a conducting state, so that DC2_Off_Rst is at a low level, thus achieving the access of only the highest priority power supply at the same time;

[0128] d): When manually switching, only need to adjust Figure 2 the values of resistors R43, R46 and R49 in, so as to increase the preset threshold, make the first detection circuit output a first electrical signal of low level, and the first switching control circuit output a second electrical signal of low level, thus shielding the first input power supply;

[0129] At the same time, adjust Figure 3 the values of R44, R47 and R50 in, so as to lower the preset threshold of the second detection circuit, make the second detection circuit output a first electrical signal of high level; after the second switching control circuit receives the first electrical signal of high level and the second electrical signal of low level from the first detection circuit, it controls the second switching circuit to open, thus accessing the second input power supply and completing the manual switching;

[0130] In the actual application process, considering the adjustment of resistors, it is difficult for users to operate and inconvenient to switch. Therefore, in this embodiment, a switch is added to the detection circuit for switching; in the detection circuit, adding a switch can achieve the function of manual switching;

[0131] The working principle of the third switching control circuit is the same as that of the second switching control circuit, and the working processes of the second input branch and the third input branch are also the same as that of the first input branch, which will not be elaborated here;

[0132] In this embodiment, since there is some electric energy stored in the energy storage circuit, during switching, the lighting device is powered by the energy storage circuit, so there will be no phenomenon of short-term power failure, nor will it cause the problem of instability of the lighting device, thus realizing hot switching;

[0133] In this embodiment, the connection of the input power supply is only related to its own priority and whether the voltage is greater than the preset threshold of the detection circuit. The power supply voltage of the high priority can be set arbitrarily and has no relation with the voltage of the low priority power supply. That is, the power supply voltage of the high priority can be greater than, less than or equal to the voltage of the low priority, making the circuit setting more flexible and adaptable to a wider range of power supplies.

[0134] Secondly, the switching control circuit designed in this embodiment can ensure that at most only one input power supply with the highest priority can be connected at the same time, avoiding short circuits caused by multiple input power supplies being connected and resulting in unstable operation of the lighting device.

[0135] In addition, during the normal operation of the lighting device, by flexibly adjusting the preset thresholds of each detection circuit, a power supply with a higher or lower priority than the current power supply can be connected at any time according to requirements, greatly improving the flexibility of switching. At the same time, hot switching is also achieved, improving the working stability of the lighting device.

[0136] The same or similar reference numerals correspond to the same or similar components.

[0137] The terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation of this patent.

[0138] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A power supply switching circuit for an LED lighting device, characterized in that, Including: A plurality of input branches set in order of decreasing priority, as well as a bias power supply circuit and an energy storage circuit; Each of the input branches includes: an input power supply, a detection circuit, a switching control circuit, and a switching circuit; Inside each of the input branches, the output terminal of the input power supply is electrically connected to the input terminals of the detection circuit and the switching circuit respectively; the switching control circuit receives a first electrical signal output from the output terminal of the detection circuit; the first output terminal of the switching control circuit is electrically connected to the control terminal of the switching circuit; the output terminal of the switching circuit serves as the output terminal of the corresponding input branch; The switching control circuit of the low priority level also receives the first electrical signals output from the detection circuits of each high priority level respectively; Each of the switching control circuits also receives a second electrical signal output from the second output terminal of other switching control circuits respectively; The output terminal of each of the input power supplies is also electrically connected to the input terminal of the bias power supply circuit respectively, and the output terminal of the bias power supply circuit provides a bias voltage for each detection circuit and switching control circuit respectively; The energy storage circuit is connected in parallel with the output terminal of each of the input branches; the output terminal of each of the input branches is electrically connected to the power supply terminal of the lighting device respectively; Each of the switching control circuits includes: a sixth to twelfth resistor, a first and a second NMOS transistor, an NPN transistor, a third capacitor, and a first diode; One end of the sixth resistor is connected to the output terminal of the detection circuit of the corresponding input branch for receiving the first electrical signal inside the input branch; the other end of the sixth resistor is connected to the drain of the first NMOS transistor, one end of the seventh resistor, and the base of the NPN transistor respectively; the source of the first NMOS transistor, the other end of the seventh resistor, and the emitter of the NPN transistor are all grounded; The gate of the first NMOS transistor is connected to one end of the eighth resistor, one end of the ninth resistor, and one end of the third capacitor respectively, and the other end of the eighth resistor is connected to the second electrical signal output from the second output terminal of other switching control circuits; the other ends of the ninth resistor and the third capacitor are both grounded; The collector of the NPN transistor is connected to the control terminal of the switching circuit and serves as the first output terminal of the switching control circuit; The collector of the NPN transistor is also connected to the negative electrode of the first diode, and the positive electrode of the first diode is connected to the gate of the second NMOS transistor, one end of the tenth resistor, and one end of the eleventh resistor respectively; the other end of the tenth resistor is connected to the output terminal of the bias power supply circuit; the source of the second NMOS transistor and the other end of the eleventh resistor are both grounded; The drain of the second NMOS transistor is connected to one end of the twelfth resistor and the other end of the eighth resistor in other switching control circuits respectively, and serves as the second output terminal of the switching control circuit to output a second electrical signal; the other end of the twelfth resistor is connected to the output terminal of the bias power supply circuit.

2. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that The types of the input power supply include: mains power, storage battery, AC-DC power supply, DC-DC power supply, and battery box.

3. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that, Each of the detection circuits includes: a comparator, a first to fifth resistor, a first and a second capacitor, a zener diode, and a switch; The non-inverting input terminals of the comparator are respectively connected to one end of the first resistor, one end of the second resistor, one end of the first capacitor, one end of the third resistor, and one end of the switch; the other end of the first resistor is connected to the input power supply; the other ends of the second resistor, the first capacitor, and the switch are all grounded; the other end of the third resistor is respectively connected to one end of the second capacitor and the output terminal of the comparator; the other end of the second capacitor is grounded; The inverting input terminals of the comparator are respectively connected to the cathode of the zener diode and one end of the fourth resistor; the anode of the zener diode is grounded; the other end of the fourth resistor is connected to the output terminal of the bias power supply circuit; The output terminal of the comparator is connected to one end of the fifth resistor and serves as the output terminal of the detection circuit, outputting a first electrical signal; the other end of the fifth resistor is connected to the output terminal of the bias power supply circuit; The positive power supply terminal of the comparator is connected to the output terminal of the bias power supply circuit, and the negative power supply terminal is grounded.

4. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that, Except for the switching control circuit with the highest priority, the other switching control circuits further include: the thirteenth and fourteenth resistors, and the third NMOS transistor; The gate of the third NMOS transistor is respectively connected to one end of the thirteenth resistor and one end of the fourteenth resistor. The other end of the thirteenth resistor is respectively connected to the output terminals of all the detection circuits with a higher priority than this switching control circuit, for receiving the first electrical signals of the high-priority input branches; the source of the third NMOS transistor and the other end of the fourteenth resistor are both grounded; The drain of the third NMOS transistor is connected to the other end of the sixth resistor.

5. The power supply switching circuit of an LED lighting device according to claim 4, wherein, For each of the switching control circuits, when the second electrical signals of other switching control circuits are input to the eighth resistor of this switching control circuit, and the first electrical signals of the high-priority input branches are input to the thirteenth resistor of this switching control circuit, the signals are input after passing through a forward diode.

6. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that, Each of the switch circuits includes: the fifteenth and sixteenth resistors, and the fourth and fifth NMOS transistors; The source of the fourth NMOS transistor is connected to the input power supply and serves as the input terminal of the switch circuit; The gate of the fourth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The other end of the fifteenth resistor is respectively connected to the drain of the fourth NMOS transistor and the drain of the fifth NMOS transistor; the other end of the sixteenth resistor is connected to the first output terminal of the switching control circuit and serves as the control terminal of the switch circuit; The gate of the fifth NMOS transistor is respectively connected to one end of the fifteenth resistor and one end of the sixteenth resistor. The source of the fifth NMOS transistor is connected to the input terminal of the energy storage circuit and serves as the output terminal of the switch circuit.

7. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that, The bias power supply circuit includes: a TX4139 power chip, the seventeenth to twenty-first resistors, the fourth to ninth capacitors, the second diode, and an inductor; The ILIM pin of the TX4139 power chip is connected to one end of the seventeenth resistor; the other end of the seventeenth resistor is respectively connected to one end of the fourth capacitor, one end of the fifth capacitor, the VIN pin of the TX4139 power chip, one end of the eighteenth resistor, and the output terminals of all input power supplies. The other end of the seventeenth resistor serves as the input terminal of the bias power supply circuit, and each input power supply inputs a power signal after passing through a forward diode; the other end of the eighteenth resistor is connected to the EN pin of the TX4139 power chip; the other ends of the fourth capacitor and the fifth capacitor are both grounded; The SW pin of the TX4139 power chip is respectively connected to one end of the sixth capacitor, one end of the inductor, and the cathode of the second diode. The other end of the sixth capacitor is connected to one end of the nineteenth resistor, and the other end of the nineteenth resistor is connected to the BS pin of the TX4139 power chip; the anode of the second diode is grounded; the other end of the inductor is respectively connected to one end of the seventh to ninth capacitors, one end of the twentieth resistor, and the detection circuit and the switching control circuit, and serves as the output terminal of the bias power supply circuit, outputting a bias voltage of +12V; The other end of the seventh capacitor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twentieth resistor is respectively connected to the FB pin of the TX4139 power chip and one end of the twenty-first resistor; the other end of the twenty-first resistor, and the other ends of the eighth and ninth capacitors are all grounded; The POK pin of the TX4139 power chip is left unconnected, and the GND pin of the TX4139 power chip is grounded.

8. The power supply switching circuit of an LED lighting device according to claim 1, characterized in that, The energy storage circuit includes a plurality of energy storage capacitors connected in parallel. One end of each energy storage capacitor is respectively connected to the output terminals of all input branches and the power supply terminal of the lighting device; the other end of each energy storage capacitor is grounded.

9. A power supply switching circuit control method for an LED lighting device, based on the power supply switching circuit of the LED lighting device described in any one of claims 1 to 8, characterized in that, Including the following steps: For each of the input branches, when an input power supply is connected and the detection circuit detects that the voltage input by the input power supply is greater than or equal to a preset threshold, the detection circuit outputs a high-level first electrical signal to the switching control circuit and all switching control circuits with a lower priority than this input branch; when the switching control circuit of this input branch receives the high-level first electrical signal and the second electrical signals output by other switching control circuits are all low-level, it outputs a high-level second electrical signal to control the switch circuit to turn on, so that the input power supply supplies power to the energy storage circuit and the lighting device. At the same time, all switching control circuits with a lower priority than this input branch receive the high-level first electrical signal and control all switch circuits with a lower priority than this input branch to turn off; S1: Automatic power-off switching: When the input power supply with a higher priority loses power, the detection circuit of the power-off input branch detects the disconnection of the input power supply. At this time, the detection circuit outputs a first electrical signal with a low level to the switching control circuit and all switching control circuits with a lower priority than this input branch; when the switching control circuit of this input branch receives the first electrical signal with a low level, it controls the switch circuit to close, and at the same time, this switching control circuit outputs a second electrical signal with a low level to the switching control circuits of other input branches; Judge in turn from high to low according to the priority whether there is any other input power supply connected, control other input power supplies with a higher priority to supply power to the energy storage circuit and the lighting device, and at the same time, all the switch circuits of other input branches are closed to complete the automatic power-off switching; S2: Manual switching: During the normal operation of the lighting device, according to the preset requirements, manually increase the preset threshold of the detection circuit of the current input branch, so that the detection circuit of the current input branch outputs a first electrical signal with a low level, and the switching control circuit outputs a second electrical signal with a low level, thereby shielding the input power supply of the current input branch; At the same time, lower the preset threshold of the detection circuit of the input branch to be connected, so that the detection circuit of the input branch to be connected outputs a first electrical signal with a high level; After the switching control circuit of the input branch to be connected receives the first electrical signal with a high level and the second electrical signal with a low level of the current input branch, it controls the switch circuit of the input branch to be connected to open, so as to connect the input power supply of the input branch to be connected and complete the manual switching.

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