Power switching circuit, power system and terminal equipment

Abstract

The utility model provides a power supply switching circuit, a power supply system and terminal equipment. The power supply switching circuit comprises a power supply selection unit, a first switching execution unit and second switching execution units which are in one-to-one correspondence with standby power supplies of the terminal equipment. A first end of the first switching execution unit is coupled with an external power supply, a first end of the second switching execution unit is coupled with a corresponding standby power supply, and a second end of the first switching execution unit and a second end of the second switching execution unit are respectively coupled with a voltage output end; the control end of the first switching execution unit and the control end of the second switching execution unit are respectively coupled with the power supply selection unit so as to switch on the corresponding power supply according to the received switch-on signal or switch off the corresponding power supply according to the received switch-off signal. According to the utility model, power supply switching can be realized by using discrete devices, so that the production cost of the power supply switching circuit can be obviously reduced; and the system has the advantages of high reliability and low power consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of power control, and particularly relates to a power switching circuit, a power supply and a terminal device. Background Art

[0002] In order to ensure the normal operation of a terminal device (such as a ventilator) and prevent abnormal power supply problems of the terminal device, for a terminal device with multiple backup power supplies, it is often necessary to select one from an external power supply (such as accessing the commercial power through an AC-DC converter) and multiple backup power supplies of the terminal device to supply power to a load. In related technologies, one commonly used solution is to use a power path control integrated chip to realize the switching of the power source. However, this method has the defect of high cost. Another solution is to use parallel Schottky diodes to realize the switching of the power source, which has the defects of low reliability and high power consumption.

[0003] It should be noted that the information disclosed in the background art part of this utility model is only intended to deepen the understanding of the general background technology of this utility model, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a power switching circuit, a power supply system and a terminal device for one or more problems such as high cost, low reliability and high power consumption existing in the prior art during power switching. The utility model can realize power switching by using discrete devices, and can significantly reduce the production cost of the power switching circuit on the premise of realizing the power switching function. Further, the utility model also has the advantages of high reliability and low power consumption.

[0005] To achieve the above purpose, the utility model is realized through the following technical solutions. A power switching circuit includes a power selection unit, a first switching execution unit, and a second switching execution unit corresponding to each backup power supply of the terminal device one by one. The first end of the first switching execution unit is coupled to an external power supply, the first end of the second switching execution unit is respectively coupled to the corresponding backup power supply, and the second ends of the first switching execution unit and the second switching execution unit are respectively coupled to a voltage output end. The control ends of the first switching execution unit and the second switching execution unit are respectively coupled to the power selection unit to conduct the corresponding power supply according to the received conduction signal or turn off the corresponding power supply according to the received turn-off signal.

[0006] The power supply selection unit is configured to, when the voltage of the external power supply is greater than or equal to a preset voltage, send the conduction signal to the first switching execution unit and send the cut-off signal to all the second switching execution units; when the voltage of the external power supply is less than the preset voltage or the voltage of the currently conducting backup power supply is less than the preset voltage, send the conduction signal to the second switching execution unit corresponding to one of the backup power supplies whose voltage is greater than the preset voltage and send the cut-off signal to the first switching execution unit and the second switching execution units corresponding to the other backup power supplies.

[0007] Optionally, both the first switching execution unit and the second switching execution unit include a switch control module and an anti-backflow module; a first end of the switch control module and a first end of the anti-backflow module are coupled to the corresponding power supply, a second end of the switch control module is coupled to a second end of the anti-backflow module, and a third end of the anti-backflow module is coupled to the voltage output end; a control end of the switch control module is coupled to the power supply selection unit to conduct the corresponding power supply according to the received conduction signal or cut off the corresponding power supply according to the received cut-off signal.

[0008] The anti-backflow module of the first switching execution unit is configured to prevent current from flowing back to the external power supply; the anti-backflow module of the second switching execution unit is configured to prevent current from flowing back to the corresponding backup power supply.

[0009] Optionally, the switch control module includes a first execution sub-circuit, a first voltage stabilizing diode, a first resistor, and a first switch. A first end of the first execution sub-circuit, a negative electrode of the first voltage stabilizing diode, and a first end of the first resistor are coupled to the corresponding power supply at a first node. A control end of the first execution sub-circuit, a positive electrode of the first voltage stabilizing diode, a second end of the first resistor, and a first end of the first switch are coupled to a second node. A second end of the first switch is grounded, a control end of the first switch is coupled to the power supply selection unit, and a second end of the first execution sub-circuit is coupled to a second end of the anti-backflow module.

[0010] Optionally, the switch control module further includes a second resistor. A first end of the second resistor is coupled to the second node, and a second end of the second resistor is coupled to the first end of the first switch.

[0011] Optionally, the anti-backflow module includes a comparison sub-circuit and an anti-backflow sub-circuit; a first input terminal of the comparison sub-circuit is coupled to the corresponding power supply, and a second input terminal of the comparison sub-circuit receives a system common output voltage; an output terminal of the comparison sub-circuit is coupled to a control terminal of the anti-backflow sub-circuit, a first end of the anti-backflow sub-circuit is coupled to a second end of the switch control module, and a second end of the anti-backflow sub-circuit is coupled to the voltage output terminal; the comparison sub-circuit is configured to continuously control the corresponding anti-backflow sub-circuit to prevent current from flowing back to the corresponding power supply.

[0012] Optionally, the anti-backflow sub-circuit includes a second execution sub-circuit, a second zener diode, and a third resistor; a first end of the second execution sub-circuit is coupled to a second end of the switch control module, a second end of the second execution sub-circuit, a first end of the third resistor, and a cathode of the second zener diode are coupled to the voltage output terminal at a third node, a control terminal of the second execution sub-circuit, a second end of the third resistor, and an anode of the second zener diode are coupled to a fourth node, and an output terminal of the comparison sub-circuit is coupled to the fourth node.

[0013] Optionally, the anti-backflow module of the first switching execution unit further includes a second switch, a first end of the second switch is coupled to the third node, a second end of the second switch is coupled to the fourth node, and a control terminal of the second switch is coupled to the power supply selection unit to be turned on or off according to a received conduction signal or a turn-off signal.

[0014] The power supply selection unit is further configured to send the turn-off signal to the second switch when the voltage of the external power supply is greater than or equal to the preset voltage; and send a conduction signal to the second switching execution unit corresponding to one of the backup power supplies whose voltage is greater than the preset voltage and the second switch when the voltage of the external power supply is less than the preset voltage, and send the turn-off signal to the second switch, the first switching execution unit, and the second switching execution units corresponding to other backup power supplies after the second switch is turned on for a preset duration.

[0015] Optionally, the anti-backflow sub-circuit further includes a fourth resistor, a first end of the fourth resistor is coupled to the fourth node, and a second end of the fourth resistor is coupled to an output terminal of the comparison sub-circuit.

[0016] To achieve the above object, the present invention further provides a power supply system, which includes the power supply switching circuit described in any one of the above and at least one power supply.

[0017] To achieve the above object, the present invention further provides a terminal device, which includes the power supply switching circuit described in any one of the above or the above power supply system.

[0018] Compared with the prior art, a power supply switching circuit, a power supply system and a terminal device provided by the present utility model have the following advantages:

[0019] The power supply switching circuit provided by the present utility model includes a power supply selection unit, a first switching execution unit, and a second switching execution unit corresponding one-to-one to the backup power supplies of the terminal device. The power supply selection unit is configured to turn on the external power supply and turn off the backup power supply when the voltage of the external power supply is greater than or equal to a preset voltage, and turn on one of the backup power supplies with a voltage greater than the preset voltage and turn off the external power supply and other backup power supplies when the voltage of the external power supply is less than the preset voltage or the voltage of the currently turned-on backup power supply is less than the preset voltage. Thus, the present utility model can achieve the power supply switching between the external power supply and the backup power supply and the power supply switching between the backup power supplies by using discrete devices, and the power supply selection unit, the first switching execution unit, and the second switching execution unit can be implemented by electronic discrete devices, which can significantly reduce the production cost of the power supply switching circuit on the premise of realizing the power supply switching function. Further, when the power supply switching circuit provided by the present utility model performs power supply switching, it adopts the method of first turning on the backup power supply and then turning off the currently turned-on power supply, which can achieve a lower output voltage drop during the power supply switching, thereby further improving the reliability and stability of the present utility model.

[0020] Since the power supply system and the terminal device provided by the present utility model belong to the same inventive concept as the power supply switching circuit provided by the present utility model, therefore, the power supply system and the terminal device provided by the present utility model at least have all the advantages of the power supply switching circuit provided by the present utility model. For the detailed content of the beneficial effects of the power supply system and the terminal device provided by the present utility model, please refer to the relevant description of the beneficial effects of the power supply switching circuit provided by the present utility model above, and will not be repeated here one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic block diagram of the power supply switching circuit provided by the present utility model;

[0022] Figure 2 is a specific example diagram of the circuit structure of the power supply switching circuit provided by one embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The power supply switching circuit, power supply system and terminal device proposed by the present utility model will be further described in detail below in conjunction with the accompanying drawings. According to the following description, the advantages and features of the present utility model will be clearer. It should be noted that the accompanying drawings are in a very simplified form and all use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the embodiments of the present utility model. In order to make the purpose, features and advantages of the present utility model more obvious and understandable, please refer to the accompanying drawings. It should be noted that the structures, scales, sizes, etc. of the drawings in this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present utility model. Any modification of the structure, change of the proportional relationship or adjustment of the size, in the case of being the same or similar to the effects that the present utility model can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed by the present utility model. The specific design features of the present utility model disclosed herein, such as specific dimensions, directions, positions and shapes, will be partially determined by the specific application and usage environment. Also, in the following described embodiments, sometimes the same reference numerals are used between different drawings to represent the same part or parts having the same function, and the repeated description thereof is omitted. In this specification, similar reference numerals and letters are used to represent similar items. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. Additionally, if the methods described herein include a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps may be omitted and / or some other steps not described herein may be added to the method.

[0024] It should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element. The singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in the sense of including "and / or", the term "several" is generally used in the sense of including "at least one", the term "at least two" is generally used in the sense of including "two or more", and in addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0025] It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected to the other element or there may be intervening elements. In contrast, when an element is referred to as being "directly connected to" another element, there are no intervening elements.

[0026] The core idea of the present utility model is to provide a power switching circuit, a power supply system and a terminal device. The present utility model can achieve power switching by using discrete devices, and on the premise of realizing the power switching function, can significantly reduce the production cost of the power switching circuit. Further, the present utility model also has the advantages of high reliability and low power consumption.

[0027] Exemplarily, please refer to Figure 1 and Figure 2 , Figure 1 which is a schematic block diagram of the power switching circuit provided by the present utility model, Figure 2 which is a specific example diagram of the circuit structure of the power switching circuit provided by one embodiment of the present utility model. From Figure 1It can be seen that the power supply switching circuit provided by the present utility model includes a power supply selection unit 110, a first switching execution unit 120, and second switching execution units 130, 140, ……, N corresponding one by one to standby power supplies Bat1, Bat2, ……, BatN of a terminal device (not labeled in the figure); a first end of the first switching execution unit 120 is coupled to an external power supply ACDC_In, first ends of the second switching execution units 130, 140, ……, N are respectively coupled to the corresponding standby power supplies Bat1, Bat2, ……, BatN, a second end of the first switching execution unit 120 and second ends of the second switching execution units Bat1, Bat2, ……, BatN are respectively coupled to a voltage output end Vout; a control end of the first switching execution unit 120 and control ends of the second switching execution units Bat1, Bat2, ……, BatN are respectively coupled to the power supply selection unit 110 to conduct a corresponding power supply according to a received conduction signal or turn off the corresponding power supply according to a received turn-off signal. The power supply selection unit 110 is configured to send the conduction signal (such as a high level) to the first switching execution unit 120 and send the turn-off signal (such as a low level) to all the second switching execution units Bat1, Bat2, ……, BatN when the voltage of the external power supply ACDC_In is greater than or equal to a preset voltage; when the voltage of the external power supply ACDC_In (at this time, the external power supply ACDC_In supplies power to the terminal device as a power supply, and all the standby power supplies Bat1, Bat2, ……, BatN are in a turned-off state) is less than the preset voltage or the voltage of the currently conducting standby power supply (for example, the standby power supply Bat1 supplies power to the terminal device as a power supply, and at this time, the external power supply ACDC_In and other standby power supplies Bat2, ……, BatN are in a turned-off state) is less than the preset voltage, send the conduction signal to the second switching execution unit (such as the second switching unit 140 corresponding to the standby power supply Bat2) corresponding to one of the standby power supplies whose voltage is greater than the preset voltage and send the turn-off signal to the first switching execution unit 120 and the second switching execution units 130, ……, N corresponding to other standby power supplies (Bat1, ……, and BatN).

[0028] The power supply switching circuit provided by the present utility model includes a power supply selection unit 110, a first switching execution unit 120, and second switching execution units 130, 140, ……, N corresponding to the backup power supplies Bat1, Bat2, ……, BatN of the terminal device one by one. The power supply selection unit 110 is configured to turn on the external power supply ACDC_In and turn off the backup power supplies Bat1, Bat2, ……, BatN when the voltage of the external power supply ACDC_In is greater than or equal to a preset voltage, and turn on one of the backup power supplies with a voltage greater than the preset voltage and turn off the external power supply ACDC_In and other backup power supplies when the voltage of the external power supply ACDC_In is less than the preset voltage or the voltage of the currently turned-on backup power supply is less than the preset voltage. Thus, the present utility model can realize the power supply switching between the external power supply ACDC_In and the backup power supplies Bat1, Bat2, ……, BatN and the power supply switching between the backup power supplies Bat1, Bat2, ……, BatN by using discrete devices, and the power supply selection unit 110, the first switching execution unit 120, and the second switching execution units 130, 140, ……, N can be implemented by electronic discrete devices, which can significantly reduce the production cost of the power supply switching circuit on the premise of realizing the power supply switching function. Further, when the power supply switching circuit provided by the present utility model performs power supply switching, it adopts the method of first turning on one of the backup power supplies Bat1, Bat2, ……, BatN to supply power to the terminal device and then turning off the currently turned-on power supply, which can achieve a lower output voltage drop during power supply switching, thereby further improving the reliability and stability of the present utility model.

[0029] It should be noted that, as can be understood by those skilled in the art, the present utility model does not impose too many limitations on the external power supply ACDC_In. For the sake of convenience of understanding, in this article, taking the connection of the mains power through an ACDC converter as the external power supply ACDC_In as an example for illustration. Further, the power supply switching circuit provided by the present utility model does not impose any limitations on the specific type of the terminal device. For example, in some applications, the terminal device may be a medical device, including but not limited to a ventilator and an anesthesia machine, etc.; in other applications, the terminal device may also be other devices with backup power supplies other than medical devices, which will not be listed one by one here. Still further, the present utility model does not impose too many limitations on the number of the backup power supplies Bat1, Bat2, ……, BatN. The number of the backup power supplies may be 1, or 2, 3 or more. For the sake of convenience of understanding and description, in the following, the power supply switching circuit provided by the present utility model will be described by taking a terminal device with backup power supplies Bat1 and Bat2 as an example. Additionally, the present utility model does not impose too many limitations on the specific value of the preset voltage. Preferably, the preset voltage is the lower limit of the operating voltage of the terminal device.

[0030] In addition, the present utility model does not overly limit the specific implementation manner of the power supply selection unit 110. For example, the power supply selection unit 110 may be, but is not limited to, a microcontroller unit (MCU).

[0031] Preferably, in some exemplary embodiments, please continue to refer to Figure 1 and Figure 2 , from Figure 1 and Figure 2 it can be seen that the structures of the first switching execution unit 120, the second switching execution units 130 and 140 are basically the same. The first switching execution unit 120 includes a switch control module 121 and an anti-backflow module 122. The second switching execution unit 130 includes a switch control module 131 and an anti-backflow module 132. The second switching execution unit 140 includes a switch control module 141 and an anti-backflow module 142,... The second switching execution unit N includes a switch control module N1 and an anti-backflow module N2. To avoid repetition, the first switching execution unit 120 coupled to the external power supply ACDC_In is taken as an example for illustration herein. For the detailed content of the second switching execution units 130, 140,..., N coupled to the backup power supplies Bat1, Bat2,..., BatN, please refer to the relevant description of the first switching execution unit 120 for adaptive understanding.

[0032] Exemplarily, please refer to Figure 1 and Figure 2 , taking the first switching execution unit 120 as an example, the first end of the switch control module 121 and the first end of the anti-backflow module 122 are coupled to the corresponding power supply (specifically, as Figure 1 and Figure 2As shown, the first switching execution unit 120 corresponds to the external power supply ACDC_In, the second switching execution unit 130 corresponds to the backup power supply Bat1, the second switching execution unit 140 corresponds to the backup power supply Bat2, ……, the second switching execution unit N corresponds to the backup power supply BatN. The second end of the switch control module 121 is coupled to the second end of the anti-backflow module 122, and the third end of the anti-backflow module 122 is coupled to the voltage output terminal Vout. The control end of the switch control module 121 is coupled to the power supply selection unit 110 to turn on the corresponding power supply according to the received turn-on signal or turn off the corresponding power supply according to the received turn-off signal (the switch control module 121 corresponds to the external power supply ACDC_In). The anti-backflow module 122 of the first switching execution unit 120 is used to prevent current from flowing back to the external power supply ACDC_In; the anti-backflow module 132 of the second switching execution unit 130 is used to prevent current from flowing back to the corresponding backup power supply Bat1, and the anti-backflow module 142 of the second switching execution unit 140 is used to prevent current from flowing back to the corresponding backup power supply Bat2.

[0033] Therefore, for the power supply switching circuit provided by the present invention, the first switching execution unit 120 coupled to the external power supply ACDC_In and the second switching execution units 130, 140, ……, N coupled to the backup power supplies Bat1, Bat2, ……, BatN all include a switch control module and an anti-backflow module. The control end of the switch control module can turn on the corresponding power supply according to the received turn-on signal or turn off the corresponding power supply according to the received turn-off signal, so as to realize the power supply switching between the external power supply ACDC_In and the backup power supplies Bat1, Bat2, ……, BatN and the power supply switching between the backup power supplies Bat1, Bat2, ……, BatN. Further, the anti-backflow module 122 of the first switching execution unit 120 can prevent current from flowing back to the external power supply ACDC_In, thus effectively protecting the external power supply ACDC_In (for example, effectively protecting the ACDC converter when using mains power supply); the anti-backflow modules 132, 142, ……, N2 of the second switching execution units 130, 140, ……, N can prevent current from flowing back to the corresponding backup power supplies Bat1, Bat2, ……, BatN, thus effectively protecting the corresponding backup power supplies Bat1, Bat2, ……, BatN, avoiding damage to the backup power supplies Bat1, Bat2, ……, BatN, and further effectively protecting the power consumption safety of the terminal device. Moreover, the circuit structure is simple and easy to implement.

[0034] In some preferred embodiments, please continue to refer to Figure 1 andFigure 2 , taking the switch control module 121 of the first switching execution unit 120 as an example, as Figure 2 shown, the switch control module 121 includes a first execution sub-circuit 1211, a first zener diode V1, a first resistor R1, and a first switch S1. The first end of the first execution sub-circuit 1211, the negative electrode of the first zener diode V1, and the first end of the first resistor R1 are coupled to the corresponding power supply (exemplarily, the power supply corresponding to the first switching execution unit 120 is an external power supply ACDC_In. Similarly, for the second switching execution unit 130, the corresponding power supply is a backup power supply Bat1) at a first node (not labeled in the figure). The control end of the first execution sub-circuit 1211, the positive electrode of the first zener diode V1, the second end of the first resistor R1, and the first end of the first switch S1 are coupled to a second node (not labeled in the figure). The second end of the first switch S1 is grounded, and the control end of the first switch S1 is coupled ( Figure 2 denoted as B1 in the figure to represent the control signal received from the power supply selection unit 110, and the control signal includes one of a turn-off signal and a turn-on signal) to the power supply selection unit 110. The second end of the first execution sub-circuit 1211 is coupled to the second end of the anti-backflow module 122. Thus, the switch control module 121 includes a first execution sub-circuit 1211, a first zener diode V1, a first resistor R1, and a first switch S1. The first execution sub-circuit 1211 and the first zener diode V1 can further improve the stability and reliability of the power supply switching circuit provided by the present invention; the first resistor R1 with a relatively large resistance value can effectively reduce power consumption; the first switch S1 that is easy to control can ensure the response efficiency of the power supply switching circuit provided by the present invention. Further, these discrete electronic devices such as the first execution sub-circuit 1211, the first zener diode V1, the first resistor R1, and the first switch S1 are inexpensive and easy to obtain, thereby ensuring that the power supply switching circuit provided by the present invention has a high cost advantage.

[0035] Exemplarily, in some preferred embodiments, please continue to refer to Figure 2 , taking the first execution sub-circuit 1211 of the switch control module 121 of the first switching execution unit 120 as an example, as Figure 2As shown, the first execution sub-circuit 1211 includes a first diode (not labeled in the figure) and a first MOS transistor Q1. The negative electrode of the first diode and the source terminal of the first MOS transistor Q1 are coupled to the first node. The control terminal of the first MOS transistor Q1 is coupled to the second node. The positive electrode of the first diode and the drain terminal of the first MOS transistor Q1 are coupled to the second terminal of the anti-backflow module 122. Thus, the first execution sub-circuit 1211 includes a first diode and a first MOS transistor Q1, which can not only make the circuit more stable but also have a simple logic and be easy to implement. Further, through the first voltage-regulating diode V1, the gate-source voltage of the first MOS transistor Q1 can be effectively prevented from being too high, thereby effectively protecting the first MOS transistor Q1 and further improving the reliability of the power supply switching circuit provided by the present invention.

[0036] It should be understood that the present invention does not overly limit the specific type of the first MOS transistor Q1. The first MOS transistor Q1 can be, but is not limited to, a PMOS transistor, an NMOS transistor, etc.

[0037] Exemplarily, in some preferred embodiments, please continue to refer to Figure 2 , still taking the switch control module 121 of the first switching execution unit 120 as an example. From Figure 2 it can be seen that the switch control module 121 further includes a second resistor R2. The first terminal of the second resistor R2 is coupled to the second node, and the second terminal of the second resistor R2 is coupled to the first terminal of the first switch S1. Thus, the second resistor R2 can not only further improve the stability of the present invention, but also significantly reduce power consumption by selecting a second resistor R2 with an appropriate resistance value. It should be noted that the present invention does not overly limit the specific value of the second resistor R2. Preferably, the resistance value of the second resistor R2 is preferably between 100 KΩ and 10 MΩ.

[0038] Exemplarily, in some preferred embodiments, please continue to refer to Figure 2 , and next, the anti-backflow module 122 of the first switching execution unit 120 will be taken as an example for illustration. From Figure 2It can be seen that the anti-backflow module 122 includes a comparison sub-circuit 1221 and an anti-backflow sub-circuit 1222; the first input terminal (such as the negative terminal input) of the comparison sub-circuit 1221 is coupled to the corresponding power supply (the anti-backflow module 122 corresponds to the external power supply ACDC_In, the anti-backflow module 132 corresponds to the backup power supply Bat1, and the anti-backflow module 142 corresponds to the backup power supply Bat2), and the second input terminal (such as the positive terminal input) of the comparison sub-circuit 1221 receives the system common output voltage (not marked in the figure, that is, the output voltage of the voltage output terminal Vout); the output terminal of the comparison sub-circuit 1221 is coupled to the control terminal of the anti-backflow sub-circuit 1222, the first end of the anti-backflow sub-circuit 1222 is coupled to the second end of the switch control module 121, and the second end of the anti-backflow sub-circuit 1222 is coupled to the voltage output terminal Vout; the comparison sub-circuit 1221 is configured to continuously control the corresponding anti-backflow sub-circuit 1222 to prevent current from flowing back to the corresponding power supply. Thus, the anti-backflow module in the power supply switching circuit provided by the present invention includes a comparison sub-circuit and an anti-backflow sub-circuit, and the comparison sub-circuit can continuously control the corresponding anti-backflow sub-circuit to prevent current from flowing back to the corresponding power supply. Thus, whether it is powered by the external power supply ACDC_In or by the backup power supplies Bat1, Bat2,..., BatN, current backflow can be effectively prevented, thereby effectively ensuring the reliability and safety of the power supply switching circuit provided by the present invention.

[0039] It should be noted that, as can be understood by those skilled in the art, the present invention does not impose excessive limitations on the specific value of the system common output voltage. Exemplarily, the system common output voltage can be, but is not limited to, 24V.

[0040] Exemplarily, in some preferred embodiments, please continue to refer to Figure 2 , and next, the anti-backflow sub-circuit 1222 of the anti-backflow module 122 of the first switching execution unit 120 will be taken as an example for illustration. From Figure 2 It can be seen that the anti-backflow sub-circuit 1222 includes a second execution sub-circuit 12221, a second zener diode V2, and a third resistor R3; the first end of the second execution sub-circuit 12221 is coupled to the second end of the switch control module 121 ( Figure 2(The middle is the drain terminal of the first MOS transistor Q1), the second terminal of the second execution sub-circuit 12221, the first terminal of the third resistor R3, and the negative electrode of the second voltage regulator diode V2 are coupled to the voltage output terminal Vout at a third node (not labeled in the figure). The control terminal of the second execution sub-circuit 12221, the second terminal of the third resistor R3, and the positive electrode of the second voltage regulator diode V2 are coupled to a fourth node (not labeled in the figure). The output terminal of the comparison sub-circuit 1221 is coupled to the fourth node. Thus, the output terminal of the comparison sub-circuit 1221 is coupled to the control terminal of the second execution sub-circuit 12221, and the comparison sub-circuit 1221 can continuously control the corresponding second execution sub-circuit 12221 to prevent current backflow to the corresponding power supply. Whether it is powered by the external power supply ACDC_In or by one of the backup power supplies Bat1, Bat2,..., BatN, current backflow can be effectively prevented, thereby effectively ensuring the reliability and safety of the power supply switching circuit provided by the present invention. Further, the anti-backflow sub-circuit 1222 includes a second execution sub-circuit 12221, a second voltage regulator diode V2, and a third resistor R3. The second execution sub-circuit 12221 and the second voltage regulator diode V2 can further improve the stability and reliability of the power supply switching circuit provided by the present invention; the third resistor R3 with a relatively large resistance value can effectively reduce power consumption. Further, these discrete electronic components such as the second execution sub-circuit 12221, the second voltage regulator diode V2, and the third resistor R3 are inexpensive and easy to obtain, thus ensuring that the power supply switching circuit provided by the present invention has a high cost advantage.

[0041] Exemplarily, in some preferred embodiments, please continue to refer to Figure 2 , taking the anti-backflow sub-circuit 1222 of the first switching execution unit 120 as an example, as Figure 2As shown, the second execution sub-circuit 12221 includes a second diode (not labeled in the figure) and a second MOS transistor Q2. The positive electrode of the second diode and the drain terminal of the second MOS transistor Q2 are coupled to the drain terminal of the first MOS transistor Q1 (i.e., the second terminal of the corresponding switch control module 121). The negative electrode of the second diode and the source terminal of the second MOS transistor Q2 are coupled to the third node, and the control terminal of the second MOS transistor Q2 is coupled to the fourth node. Thus, the second execution sub-circuit 12221 includes a second diode and a second MOS transistor Q2, which can not only make the circuit more stable but also have a simple logic and be easy to implement. Further, through the second voltage regulator diode V2, the gate-source voltage of the second MOS transistor Q2 can be effectively prevented from being too high, thereby effectively protecting the second MOS transistor Q2 and further improving the reliability of the power supply switching circuit provided by the present invention. It should be understood that the present invention does not limit the specific type of the second MOS transistor Q2 too much, and the second MOS transistor Q2 can be, but is not limited to, a PMOS transistor, etc.

[0042] Specifically, the comparison sub-circuit 1221 is used to continuously control the corresponding anti-backflow sub-circuit 1222 to prevent current from flowing back to the corresponding power supply (i.e., the external power supply ACDC_In), and includes: the comparison sub-circuit 1221 continuously controls the second MOS transistor Q2 to remain in the off state.

[0043] Preferably, in some exemplary embodiments, please continue to refer to Figure 2 , such as Figure 2As shown, the difference from the second switching execution units 130 and 140 is that the anti-backflow module 122 of the first switching execution unit 120 further includes a second switch S2. The first end of the second switch S2 is coupled to the third node, the second end of the second switch S2 is coupled to the fourth node, and the control end of the second switch S2 is coupled to the power supply selection unit 110 to be turned on or off according to the received conduction signal or turn-off signal. The power supply selection unit 110 is further configured to send the turn-off signal to the second switch S2 when the voltage of the external power supply ACDC_In is greater than or equal to the preset voltage; and send the conduction signal to the second switching execution unit (such as the second switching unit 130) corresponding to one of the backup power supplies (such as the backup power supply Bat1) whose voltage is greater than the preset voltage and the second switch S2 when the voltage of the external power supply ACDC_In is less than the preset voltage, and send the turn-off signal to the second switch S2, the first switching execution unit 120 and the second switching execution units (such as 140,..., N) corresponding to the other backup power supplies (such as Bat2,..., BatN) after the second switch S2 is turned on for a preset duration. Thus, the power supply switching circuit provided by the present invention can effectively prevent current from flowing back to the external power supply ACDC_In during the process of switching from the external power supply ACDC_In to one of the backup power supplies Bat1, Bat2,..., BatN through the short-term closing of the second switch S2, further improving the stability and reliability of the power supply switching circuit provided by the present invention.

[0044] Preferably, please continue to refer to Figure 2 , from Figure 2 it can be seen that the anti-backflow sub-circuit 1222 further includes a fourth resistor R4. The first end of the fourth resistor R4 is coupled to the fourth node, and the second end of the fourth resistor R4 is coupled to the output end of the comparison sub-circuit 1221. Thus, the fourth resistor R4 can not only further improve the stability of the present invention, but also significantly reduce the power consumption by selecting a suitable resistance value of the fourth resistor R4. It should be noted that the present invention does not overly limit the specific value of the fourth resistor R4. Preferably, the resistance value of the fourth resistor R4 is preferably between 100 KΩ and 10 MΩ.

[0045] Next, taking Figure 2 as an example, the working states of the power supply switching circuit provided by the present invention are exemplarily described as follows:

[0046] First, when powered by an external power supply (such as mains power) ACDC_In, the power selection unit 110 sends a conduction signal (such as the B1 signal being high level) to the first switch S1 to close the first switch S1, thereby turning on the first MOS transistor; and sends a turn-off signal (such as a low-level signal) to the first switches S3 and S4 to control the first switches S3 and S4 to open, thereby controlling the first MOS transistors Q3 and Q5 to turn off, so that the voltage at the voltage output terminal Vout is provided only by the external power supply.

[0047] Next, if the external power supply ACDC_In loses power (such as a power outage), the power selection unit 110 detects that the voltage of the external power supply ACDC_In is too low (such as less than a preset voltage), and sends a conduction signal (such as the B3 signal being high level) to the first switch S3 to close the first switch S3, thereby turning on the first MOS transistor Q3, and then sends a turn-off signal (such as the B1 signal being low level) to the first switch S1 to turn off the first switch S1, so that the first MOS transistor Q1 turns off; at the same time, before the power supply completely switches from the external power supply ACDC_In to the backup power supply Bat1, the power selection unit 110 quickly sends a conduction signal (such as the B2 signal being high level) to the second switch S2 to instantaneously close the second switch S2, thereby turning off the second MOS transistor Q2 to prevent the battery current provided by the backup power supply Bat1 from flowing back to the external power supply ACDC_In. At this time, the voltage at the voltage output terminal Vout is provided by the backup power supply Bat1, and the second MOS transistor Q2 can be continuously turned off through the comparison sub-circuit 1221 to prevent current from flowing back to the external power supply ACDC_In when the external power supply ACDC_In supplies power alone, the backup power supply Bat1, or the backup power supply Bat2 supplies power.

[0048] Next, when the battery power of the backup power supply Bat1 is used up to a very low level, the power selection unit 110 will detect that the power of the backup power supply Bat1 is too low, and send a conduction signal (such as the B4 signal being high level) to the first switch S4 to close the first switch S4, thereby turning on the first MOS transistor Q5; after the power selection unit 11 controls the first switch S4 to close, it sends a turn-off signal (such as the B3 signal being low level) to the first switch S3 to turn off the first switch S3, so that the first MOS transistor Q3 turns off. At this time, the voltage at the voltage output terminal Vout is provided by the backup power supply Bat2. Moreover, due to the existence of the comparison sub-circuit 1321, the second MOS transistor Q4 can be continuously turned off to prevent current from flowing back to the backup power supply Bat1.

[0049] Similarly, the comparison sub-circuit 1421 can prevent current from flowing back to the backup power supply Bat2 when the backup power supply Bat1 supplies power and the voltage is greater than the voltage of the backup power supply Bat2 by continuously turning off the second MOS transistor Q6.

[0050] Another embodiment of the present utility model provides a power supply system, which includes the power supply switching circuit described in any of the above embodiments and at least one power supply.

[0051] Since the power supply system provided by the present utility model and the power supply switching circuit provided by the present utility model belong to the same inventive concept, therefore, the power supply system provided by the present utility model has at least all the advantages of the power supply switching circuit provided by the present utility model. For the detailed content of the beneficial effects of the power supply system provided by the present utility model, please refer to the relevant description of the beneficial effects of the power supply switching circuit provided by the present utility model above. Here, it will not be repeated one by one.

[0052] Another embodiment of the present utility model provides a terminal device, which includes the power supply switching circuit described in any of the above embodiments or the power supply system described in the above embodiments. Since the basic principle of the power supply switching of the terminal device provided by the present utility model is basically the same as that of the power supply switching circuit provided by the present utility model, for the more detailed content of the power supply switching of the terminal device provided by the present utility model, please refer to the relevant description of the power supply switching circuit described above for adaptive understanding. Here, it will not be elaborated in detail.

[0053] It should be noted that the present utility model does not overly limit the specific type of the terminal device. For example, the terminal device may be, but is not limited to, a ventilator, an anesthetic machine, etc.

[0054] Compared with the prior art, a power supply switching circuit, a power supply system and a terminal device provided by the present utility model have the following advantages:

[0055] (1) The present utility model can achieve the power supply switching between the external power supply and the standby power supply and the power supply switching between the standby power supplies by using discrete devices. Moreover, the power supply selection unit, the first switching execution unit and the second switching execution unit can be implemented by using electronic discrete devices, which can significantly reduce the production cost of the power supply switching circuit on the premise of realizing the power supply switching function. Further, when the power supply switching circuit provided by the present utility model performs power supply switching, it adopts the method of first turning on the standby power supply and then turning off the currently conducting power supply, which can achieve a lower output voltage drop during the power supply switching, thereby further improving the reliability and stability of the present utility model.

[0056] (2) The power supply switching circuit provided by the present utility model, the first switching execution unit coupled to the external power supply and the second switching execution unit coupled to the backup power supply both include a switch control module and an anti-backflow module. The control end of the switch control module can turn on the corresponding power supply according to the received conduction signal or turn off the corresponding power supply according to the received turn-off signal, so as to realize the power supply switching between the external power supply and the backup power supply and the power supply switching between the backup power supplies. Further, the anti-backflow module of the first switching execution unit can prevent current from flowing back to the external power supply, thereby effectively protecting the external power supply (for example, effectively protecting the ACDC converter when using mains power supply); the anti-backflow module of the second switching execution unit can prevent current from flowing back to the corresponding backup power supply, thereby effectively protecting the corresponding backup power supply, avoiding damage to the backup power supply, and further effectively protecting the power consumption safety of the terminal device. Moreover, the logic is simple and easy to implement.

[0057] (3) In the power supply switching circuit provided by the present utility model, the switch control module further includes a second resistor and the anti-backflow sub-circuit further includes a fourth resistor. Selecting the second resistor and the fourth resistor with larger resistance values can also significantly reduce power consumption.

[0058] It should be noted that the devices and methods disclosed in the embodiments herein can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of devices, methods, and computer program products according to multiple embodiments herein. In this regard, each block in the flowchart or block diagram may represent a module, a program, or a part of code, and the module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0059] In addition, in each embodiment herein, the functional modules can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

[0060] The above description is only a description of the preferred embodiments of the power switching circuit, power supply system and terminal device provided by the present utility model, and does not limit the scope of the present utility model in any way. Any changes and modifications made by those of ordinary skill in the art of the present utility model based on the above disclosure fall within the protection scope of the present utility model. Obviously, those skilled in the art can make various changes and modifications to the present utility model without departing from the spirit and scope of the present utility model. Thus, if these modifications and variations fall within the scope of the present utility model and its equivalent technologies, the present utility model is also intended to include these modifications and variations.

Claims

1. A power switching circuit, characterized in that: The invention comprises a power selection unit, a first switching execution unit, and a second switching execution unit corresponding to the backup power supply of the terminal device one by one; the first end of the first switching execution unit is coupled to the external power supply, the first end of the second switching execution unit is respectively coupled to the backup power supply corresponding thereto, the second end of the first switching execution unit and the second end of the second switching execution unit are respectively coupled to the voltage output end; the control end of the first switching execution unit and the control end of the second switching execution unit are respectively coupled to the power selection unit, so as to turn on the corresponding power supply according to the received turn-on signal or turn off the corresponding power supply according to the received turn-off signal; The power selection unit is used to send the on signal to the first switching execution unit and the off signal to all the second switching execution units when the voltage of the external power supply is greater than or equal to the preset voltage; when the voltage of the external power supply is less than the preset voltage or the voltage of the currently turned-on backup power supply is less than the preset voltage, send the on signal to the second switching execution unit corresponding to one of the backup power supplies whose voltage is greater than the preset voltage and send the off signal to the first switching execution unit and the second switching execution units corresponding to the other backup power supplies.

2. The power switching circuit according to claim 1, characterized in that: The first switching execution unit and the second switching execution unit both include a switch control module and an anti-backflow module; a first end of the switch control module and a first end of the anti-backflow module are coupled to the corresponding power supply, a second end of the switch control module is coupled to the second end of the anti-backflow module, and a third end of the anti-backflow module is coupled to the voltage output end; a control end of the switch control module is coupled to the power selection unit to turn on the corresponding power supply according to the received on signal or turn off the corresponding power supply according to the received off signal; The anti-backflow module of the first switching execution unit is used to prevent current from backflowing into the external power supply; the anti-backflow module of the second switching execution unit is used to prevent current from backflowing into the corresponding backup power supply.

3. The power switching circuit according to claim 2, characterized in that: The switch control module includes a first execution sub-circuit, a first voltage regulator, a first resistor and a first switch. The first end of the first execution sub-circuit, the negative electrode of the first voltage regulator and the first end of the first resistor are coupled to the corresponding power supply at a first node. The control end of the first execution sub-circuit, the positive electrode of the first voltage regulator, the second end of the first resistor and the first end of the first switch are coupled to a second node. The second end of the first switch is grounded. The control end of the first switch is coupled to the power selection unit. The second end of the first execution sub-circuit is coupled to the second end of the anti-backflow module.

4. The power switching circuit according to claim 3, characterized in that: The switch control module further includes a second resistor, a first end of the second resistor is coupled to the second node, and a second end of the second resistor is coupled to the first end of the first switch.

5. The power switching circuit according to claim 2, characterized in that: The anti-backflow module includes a comparison sub-circuit and an anti-backflow sub-circuit; the first input end of the comparison sub-circuit is coupled to the corresponding power supply, and the second input end of the comparison sub-circuit receives the system common output voltage; the output end of the comparison sub-circuit is coupled to the control end of the anti-backflow sub-circuit, the first end of the anti-backflow sub-circuit is coupled to the second end of the switch control module, and the second end of the anti-backflow sub-circuit is coupled to the voltage output end; the comparison sub-circuit is used to continuously control the corresponding anti-backflow sub-circuit to prevent current from backflowing to the corresponding power supply.

6. The power switching circuit according to claim 5, characterized in that: The anti-backflow subcircuit includes a second execution subcircuit, a second voltage regulator and a third resistor; the first end of the second execution subcircuit is coupled to the second end of the switch control module, the second end of the second execution subcircuit, the first end of the third resistor and the negative electrode of the second voltage regulator are coupled to the voltage output end at a third node, the control end of the second execution subcircuit, the second end of the third resistor, and the positive electrode of the second voltage regulator are coupled to a fourth node, and the output end of the comparison subcircuit is coupled to the fourth node.

7. The power switching circuit according to claim 6, characterized in that: The anti-backflow module of the first switching execution unit further includes a second switch, a first end of the second switch is coupled to the third node, a second end of the second switch is coupled to the fourth node, and a control end of the second switch is coupled to the power selection unit to turn on or off according to the received on signal or off signal; The power selection unit is also used to send the shutdown signal to the second switch when the voltage of the external power supply is greater than or equal to the preset voltage; and to send a turn-on signal to the second switching execution unit and the second switch corresponding to one of the backup power supplies whose voltage is greater than the preset voltage when the voltage of the external power supply is less than the preset voltage, and to send the shutdown signal to the second switch, the first switching execution unit, and the second switching execution units corresponding to the other backup power supplies after the second switch is turned on for a preset period of time.

8. The power switching circuit according to claim 6, characterized in that: The anti-backflow sub-circuit further includes a fourth resistor, a first end of the fourth resistor is coupled to the fourth node, and a second end of the fourth resistor is coupled to the output end of the comparison sub-circuit.

9. A power supply system, characterized in that: The invention comprises a power switching circuit as claimed in any one of claims 1 to 8 and at least one power supply.

10. A terminal device, characterized in that: It comprises the power switching circuit as claimed in any one of claims 1 to 8 or the power supply system as claimed in claim 9.

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