Alternating current three-phase voltage monitoring circuit, switching converter and power switching system
By designing an AC three-phase voltage monitoring circuit, and combining the three-phase voltage acquisition and neutral voltage acquisition circuits with transistor control, the abnormal state detection and switching of the three-phase voltage is realized. This solves the problem that existing technologies cannot detect simultaneous loss of voltage or phase failure of the three phases, and ensures that the load switches to the backup power supply under abnormal conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DELIXI ELECTRIC
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-21
AI Technical Summary
The monitoring circuits of existing ATS dual power supply products cannot detect that the three-phase voltage is simultaneously in a state of undervoltage or phase loss, which makes it impossible to effectively switch to the backup power supply.
Design an AC three-phase voltage monitoring circuit, including a three-phase voltage acquisition circuit, a neutral voltage acquisition circuit, first and second control circuits, and first and second transistors. The abnormal state detection and switching of the three-phase voltage is realized by controlling the switching state of the transistors.
It enables the detection of any one, two, or three phases of the three-phase voltage undervoltage or phase loss, ensuring that the power supply is switched to the backup power source in abnormal conditions to prevent the load from failing to work properly.
Smart Images
Figure CN122430591A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of AC voltage monitoring technology, and in particular to an AC three-phase voltage monitoring circuit, a switching converter, and a power switching system. Background Technology
[0002] In power systems, ATS dual-power products generally refer to Automatic Transfer Switches, or switch converters for short. The input of a switch converter is used to connect to both the primary and backup power supplies, while the output is electrically connected to the electrical equipment. The switch converter is used to switch between the primary and backup power supplies. ATS dual-power products typically require the ability to monitor the three-phase voltage status of the primary power supply and, when any one, two, or all three phases of the primary power supply are in a state of undervoltage or phase loss, be able to control relays to switch the primary power supply to the backup power supply. An undervoltage state refers to a voltage less than 0.3 times the rated voltage.
[0003] The monitoring circuit in current ATS dual power supply products can only detect that one or two phases of voltage are undervoltage or out of phase, but cannot detect that all three phases of voltage are undervoltage or out of phase at the same time. Summary of the Invention
[0004] This application provides an AC three-phase voltage monitoring circuit, a switching converter, and a power switching system to detect whether any one phase voltage, two phase voltages, or all three phase voltages are in a state of undervoltage or phase loss.
[0005] In a first aspect, this application provides an AC three-phase voltage monitoring circuit, the AC three-phase voltage monitoring circuit comprising: a three-phase voltage acquisition circuit, a neutral voltage acquisition circuit, a first control circuit, a second control circuit, a first transistor, and a second transistor; The three-phase voltage acquisition circuit is electrically connected to the neutral voltage acquisition circuit and the first control circuit, respectively. The neutral voltage acquisition circuit is electrically connected to the second control circuit. The first control circuit is electrically connected to the second transistor. The second control circuit is electrically connected to the first transistor. The first transistor is electrically connected to the second transistor. The supply voltage flows through the load, the second transistor, and the first transistor before being grounded. The three-phase voltage acquisition circuit is used to output a first voltage based on any one of the phase voltages of phase A, phase B, and phase C. The neutral voltage acquisition circuit is used to output a second voltage based on the N-phase voltage; The first control circuit is used to output a first control signal according to the first voltage to control the switching state of the second transistor, so that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and is connected to ground; so that when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load and is not connected to ground. The second control circuit is used to output a second control signal according to the second voltage to control the switching state of the first transistor, so that when the AC three-phase voltage is in the normal state, the supply voltage flows through the load and is connected to ground; so that when the AC three-phase voltage is in the abnormal state, the supply voltage flows through the load and is not connected to ground. The abnormal states include: a first abnormal state and a second abnormal state. The first abnormal state is that all three phases of the AC three-phase voltage are in a state of undervoltage and the voltage is balanced. The second abnormal state is that any one or two phases of the AC three-phase voltage are in a state of undervoltage or phase loss and the voltage is unbalanced.
[0006] In one possible design, the first control circuit is specifically used to output the first control signal according to the first voltage, controlling the second transistor to be in the on state when the AC three-phase voltage is in the normal state, and in the off state when the AC three-phase voltage is in the first abnormal state.
[0007] In one possible design, the second control circuit is specifically used to output a second control signal based on the second voltage, controlling the first transistor to be in a conducting state when the AC three-phase voltage is in the normal state; in a turning-off state when the AC three-phase voltage is in the second abnormal state; and in a conducting state when the AC three-phase voltage is in the first abnormal state.
[0008] In one possible design, the three-phase voltage acquisition circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor; The first end of the first resistor is connected to the A-phase voltage, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the sixth resistor and the second end of the ninth resistor, respectively. The first end of the fourth resistor is connected to the B-phase voltage, the second end of the fourth resistor is electrically connected to the first end of the fifth resistor, and the second end of the fifth resistor is electrically connected to the first end of the sixth resistor. The first end of the seventh resistor is connected to the C-phase voltage, the second end of the seventh resistor is electrically connected to the first end of the eighth resistor, and the second end of the eighth resistor is electrically connected to the first end of the ninth resistor. The first and second ends of the ninth resistor serve as the output terminals of the three-phase voltage acquisition circuit, used to output the first voltage.
[0009] In one possible design, the neutral line voltage acquisition circuit includes: a first diode, a tenth resistor, and an eleventh resistor; The anode of the first diode is electrically connected to the second terminal of the third resistor, the cathode of the first diode is electrically connected to the first terminal of the tenth resistor, and the second terminal of the tenth resistor is electrically connected to the first terminal of the eleventh resistor. The second end of the eleventh resistor is connected to the N-phase voltage, and the first and second ends of the eleventh resistor serve as the output terminals of the neutral line voltage acquisition circuit for outputting the second voltage.
[0010] In one possible design, the first control circuit includes: a second diode, a twelfth resistor, a first optocoupler, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a third transistor, and a second capacitor; The anode of the second diode is electrically connected to the first terminal of the ninth resistor, the cathode of the second diode is electrically connected to the first terminal of the first optocoupler, the first terminal of the twelfth resistor is electrically connected to the second terminal of the ninth resistor, and the second terminal of the twelfth resistor is electrically connected to the second terminal of the first optocoupler. The fourth terminal of the first optocoupler is electrically connected to the second terminal of the twentieth resistor and the collector of the third transistor, respectively, and the first terminal of the twentieth resistor is connected to the power supply voltage; The third terminal of the first optocoupler is electrically connected to the first terminal of the nineteenth resistor and the base of the third transistor, respectively. The second terminal of the nineteenth resistor is electrically connected to the second terminal of the twenty-first resistor, the second terminal of the second capacitor, the first terminal of the second transistor, and the second terminal of the first transistor, respectively. The first end of the 21st resistor is electrically connected to the emitter of the 3rd transistor, the first end of the 2nd capacitor, and the first end of the 22nd resistor, respectively. The second terminal of the twelfth resistor is electrically connected to the control terminal of the second transistor, and the second terminal of the second transistor is electrically connected to the load.
[0011] In one possible design, the second control circuit includes: a second optocoupler, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a first transistor, a second transistor, and a first capacitor; The first end of the second optocoupler is electrically connected to the first end of the eleventh resistor, and the second end of the second optocoupler is electrically connected to the second end of the eleventh resistor. The fourth terminal of the second optocoupler is electrically connected to the second terminal of the thirteenth resistor and the collector of the first transistor, respectively, and the first terminal of the thirteenth resistor is connected to the power supply voltage; The third end of the second optocoupler is electrically connected to the first end of the fourteenth resistor and the base of the first transistor, respectively. The emitter of the first transistor is electrically connected to the first end of the fifteenth resistor, the first end of the first capacitor, and the first end of the sixteenth resistor, respectively. The second end of the sixteenth resistor is electrically connected to the base of the second transistor, and the collector of the second transistor is electrically connected to the second end of the seventeenth resistor, the first end of the eighteenth resistor, and the control terminal of the first transistor, respectively. The first terminal of the seventeenth resistor is connected to the power supply voltage; The second terminal of the fourteenth resistor, the second terminal of the fifteenth resistor, the second terminal of the first capacitor, the emitter of the second transistor, the second terminal of the eighteenth resistor, and the first terminal of the first transistor are all grounded.
[0012] In one possible design, both the first transistor and the second transistor are Darlington transistors.
[0013] In a second aspect, this application provides a switching converter, including: an AC three-phase voltage monitoring circuit as described in the first aspect.
[0014] Thirdly, this application provides a power switching system, including: a switching converter as described in the second aspect.
[0015] The beneficial effects of the embodiments of this application are as follows: In this embodiment, the AC three-phase voltage monitoring circuit includes: a three-phase voltage acquisition circuit, a neutral voltage acquisition circuit, a first control circuit, a second control circuit, a first transistor, and a second transistor. The three-phase voltage acquisition circuit is electrically connected to the neutral voltage acquisition circuit and the first control circuit, respectively. The neutral voltage acquisition circuit is electrically connected to the second control circuit. The first control circuit is electrically connected to the second transistor, and the second control circuit is electrically connected to the first transistor. The first transistor is also electrically connected to the second transistor. The supply voltage flows through the load, the second transistor, and the first transistor before being grounded. The three-phase voltage acquisition circuit outputs a first voltage based on any one of the A-phase, B-phase, and C-phase voltages. The neutral voltage acquisition circuit outputs a second voltage based on the N-phase voltage. The first control circuit outputs a first control signal based on the first voltage to control the switching state of the second transistor, so that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and is connected to ground; and when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load and is not connected to ground. The second control circuit outputs a second control signal based on the second voltage, controlling the switching state of the first transistor. This ensures that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and connects to ground; conversely, when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load but does not connect to ground. When the AC three-phase voltage is in a normal state, controlling the switching states of the first and second transistors ensures that the supply voltage flows through the load and connects to ground, allowing current to flow through the load and enabling normal operation. When any one, two, or all three phases of the AC three-phase voltage are in a state of undervoltage or phase loss, the supply voltage flows through the load but does not connect to ground, no current flows through the load, and it cannot operate normally. This achieves the function of detecting any one, two, or all three phases of the three-phase voltage being in a state of undervoltage or phase loss. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.
[0017] Figure 1 A schematic diagram of the circuit structure of an AC three-phase voltage monitoring circuit provided in an embodiment of this application; Figure 2 A circuit diagram of an AC three-phase voltage monitoring circuit provided in an embodiment of this application. Detailed Implementation
[0018] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0019] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0020] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.
[0021] See Figure 1 , Figure 1 A circuit structure diagram of an AC three-phase voltage monitoring circuit provided in an embodiment of this application is shown below. Figure 1 As shown, the AC three-phase voltage monitoring circuit may include: a three-phase voltage acquisition circuit 100, a neutral voltage acquisition circuit 200, a first control circuit 300, a second control circuit 400, a first transistor T1, and a second transistor T2.
[0022] The three-phase voltage acquisition circuit 100 is electrically connected to the neutral voltage acquisition circuit 200 and the first control circuit 300, respectively. The neutral voltage acquisition circuit 200 is electrically connected to the second control circuit 400. The first control circuit 300 is electrically connected to the second transistor T2. The second control circuit 400 is electrically connected to the first transistor T1. The first transistor T1 is electrically connected to the second transistor T2. The +12V power supply voltage flows through the load, the second transistor T2 and the first transistor T1 and is then grounded.
[0023] The three-phase voltage acquisition circuit 100 is used to output a first voltage based on any one of the phase voltages LA, LB, and LC. The neutral line voltage acquisition circuit 200 is used to output a second voltage based on the N-phase voltage LN.
[0024] The first control circuit 300 is used to output a first control signal according to the first voltage to control the switching state of the second transistor T2, so that when the AC three-phase voltage is in a normal state, the supply voltage +12V flows through the load and is connected to ground; so that when the AC three-phase voltage is in an abnormal state, the supply voltage +12V flows through the load and is not connected to ground.
[0025] The second control circuit 400 is used to output a second control signal according to the second voltage to control the switching state of the first transistor T1 so that when the AC three-phase voltage is in a normal state, the supply voltage +12V flows through the load and is connected to ground; so that when the AC three-phase voltage is in an abnormal state, the supply voltage +12V flows through the load and is not connected to ground.
[0026] The abnormal states include: a first abnormal state and a second abnormal state. The first abnormal state is that all three phases of the AC three-phase voltage are in a state of undervoltage and the voltage is balanced. The second abnormal state is that any one or two phases of the AC three-phase voltage are in a state of undervoltage or phase loss and the voltage is unbalanced.
[0027] The three-phase AC voltage includes: phase A voltage LA, phase B voltage LB, and phase C voltage LC. The magnitude of each phase voltage is the voltage difference between that phase voltage and the N-phase voltage LN. For example, the magnitude of phase A voltage LA is the voltage difference between phase A voltage LA and phase N voltage LN.
[0028] This embodiment of the application uses a three-phase voltage acquisition circuit 100 and a neutral line voltage acquisition circuit 200 to detect the A-phase voltage LA, B-phase voltage LB, C-phase voltage LC and N-phase voltage LN. The first voltage output by the three-phase voltage acquisition circuit 100 and the second voltage output by the neutral line voltage acquisition circuit 200 are used to control the subsequent circuits.
[0029] Specifically, the first control circuit 300 outputs a first control signal based on the first voltage to control the switching state of the second transistor T2, and the second control circuit 400 outputs a second control signal based on the second voltage to control the switching state of the first transistor T1.
[0030] See Figure 1 In this application, the +12V power supply voltage flows through the load, the second transistor T2, and the first transistor T1 before being grounded. By controlling the switching states of the first transistor T1 and the second transistor T2, it is possible to control whether the +12V power supply voltage is connected to ground after flowing through the load. For example, when both the first transistor T1 and the second transistor T2 are in the on state, the +12V power supply voltage is connected to ground after flowing through the load, and current flows through the load, allowing it to operate normally. When either the first transistor T1 or the second transistor T2 is in the off state, the +12V power supply voltage is not connected to ground after flowing through the load, and no current flows through the load, preventing it from operating normally.
[0031] The first control circuit 300 outputs a first control signal based on the first voltage to control the switching state of the second transistor T2, so that when the AC three-phase voltage is in a normal state, the +12V supply voltage flows through the load and is connected to ground. Simultaneously, the second control circuit 400 outputs a second control signal based on the second voltage to control the switching state of the first transistor T1, so that when the AC three-phase voltage is in a normal state, the +12V supply voltage flows through the load and is connected to ground. When the AC three-phase voltage is in a normal state, by controlling the switching states of the first transistor T1 and the second transistor T2, the +12V supply voltage flows through the load and is connected to ground, allowing current to flow through the load and enabling normal operation. When the three-phase AC voltage is in a normal state, it means that all three phases of the three-phase AC voltage are at normal voltage, that is, there is no loss of voltage or undervoltage, and the phases of the three phases are all in a normal state, that is, there is no phase loss. Under normal circumstances, if one phase of the three-phase voltage is in a phase loss state, the voltage of that phase is zero; if one phase of the three-phase voltage is in a loss of voltage state, the voltage of that phase is less than 0.3 times the rated voltage.
[0032] In addition, the first control circuit 300 outputs a first control signal based on the first voltage to control the switching state of the second transistor T2, so that when the AC three-phase voltage is abnormal, the +12V supply voltage flowing through the load is not connected to ground. Simultaneously, the second control circuit 400 outputs a second control signal based on the second voltage to control the switching state of the first transistor T1, so that when the AC three-phase voltage is abnormal, the +12V supply voltage flowing through the load is not connected to ground. When the AC three-phase voltage is abnormal, by controlling the switching states of the first transistor T1 and the second transistor T2, the +12V supply voltage flowing through the load is not connected to ground, and no current flows through the load, preventing it from operating normally.
[0033] The abnormal states include: the first abnormal state and the second abnormal state. The first abnormal state is that all three phases of the AC three-phase voltage are in a state of undervoltage and the voltage is balanced. That is, all three phases of the AC three-phase voltage are in a state of undervoltage, which means that the voltage of each phase of the AC three-phase voltage is less than 0.3 times the rated voltage, but the voltage of each phase is balanced.
[0034] The second abnormal state is that any one or two phases of the three-phase AC voltage are in a state of undervoltage or phase breakage, and the voltage is unbalanced. That is, any one or two phases of the three-phase AC voltage are in a state of undervoltage or phase breakage, which indicates that the voltage of any one or two phases of the three-phase AC voltage is less than 0.3 times the rated voltage, but the voltage of each phase is unbalanced.
[0035] The first control signal output by the first control circuit 300 controls the switching state of the second transistor T2, and the second control signal output by the second control circuit 400 controls the switching state of the first transistor T1. This ensures that when the AC three-phase voltage is in a first or second abnormal state (i.e., any one, two, or all three phases of the three-phase voltage are undervoltage or have a phase loss), the +12V supply voltage flowing through the load does not connect to ground. This achieves the function of detecting any one, two, or all three phases of the three-phase voltage being undervoltage or having a phase loss.
[0036] In this embodiment, the AC three-phase voltage monitoring circuit includes: a three-phase voltage acquisition circuit, a neutral voltage acquisition circuit, a first control circuit, a second control circuit, a first transistor, and a second transistor. The three-phase voltage acquisition circuit is electrically connected to the neutral voltage acquisition circuit and the first control circuit, respectively. The neutral voltage acquisition circuit is electrically connected to the second control circuit. The first control circuit is electrically connected to the second transistor, and the second control circuit is electrically connected to the first transistor. The first transistor is also electrically connected to the second transistor. The supply voltage flows through the load, the second transistor, and the first transistor before being grounded. The three-phase voltage acquisition circuit outputs a first voltage based on any one of the A-phase, B-phase, and C-phase voltages. The neutral voltage acquisition circuit outputs a second voltage based on the N-phase voltage. The first control circuit outputs a first control signal based on the first voltage to control the switching state of the second transistor, so that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and is connected to ground; and when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load and is not connected to ground. The second control circuit outputs a second control signal based on the second voltage, controlling the switching state of the first transistor. This ensures that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and connects to ground; conversely, when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load but does not connect to ground. When the AC three-phase voltage is in a normal state, controlling the switching states of the first and second transistors ensures that the supply voltage flows through the load and connects to ground, allowing current to flow through the load and enabling normal operation. When any one, two, or all three phases of the AC three-phase voltage are in a state of undervoltage or phase loss, the supply voltage flows through the load but does not connect to ground, no current flows through the load, and it cannot operate normally. This achieves the function of detecting any one, two, or all three phases of the three-phase voltage being in a state of undervoltage or phase loss.
[0037] See Figure 1 In one possible embodiment, the first control circuit 300 is specifically used to output a first control signal according to the first voltage, and control the second transistor T2 to be in the on state when the AC three-phase voltage is in the normal state, and to be in the off state when the AC three-phase voltage is in the first abnormal state.
[0038] In one possible embodiment, the second control circuit 400 is specifically configured to output a second control signal based on the second voltage, controlling the first transistor T1 to be in a conducting state when the AC three-phase voltage is in a normal state; in a turning-off state when the AC three-phase voltage is in a second abnormal state; and in a conducting state when the AC three-phase voltage is in a first abnormal state.
[0039] See Figure 1When the AC three-phase voltage is in a normal state, the first control signal controls the second transistor T2 to be in the conducting state, and the second control signal controls the first transistor T1 to be in the conducting state. Under this condition, the supply voltage +12V flows through the load and then through the second transistor T2 and the first transistor T1 to be connected to ground in sequence. Current flows through the load, and it can work normally.
[0040] When the AC three-phase voltage is in the first abnormal state, the first control signal controls the second transistor T2 to be in the off state, and the second control signal controls the first transistor T1 to be in the on state. Under this condition, the +12V supply voltage does not conduct to ground after flowing through the load, and no current flows through the load, so it cannot work normally.
[0041] When the AC three-phase voltage is in the second abnormal state, the second control signal controls the first transistor T1 to be in the off state. Under this condition, the +12V supply voltage does not conduct to ground after flowing through the load, and no current flows through the load, so it cannot work normally.
[0042] By using the first control signal output from the first control circuit 300 and the second control signal output from the second control circuit 400, when the AC three-phase voltage is in a normal state, the first transistor T1 and the second transistor T2 are controlled to be in a conducting state, so that the supply voltage flows through the load and is connected to ground, and current flows through the load, allowing normal operation. When the AC three-phase voltage is in a first abnormal state or a second abnormal state, the second transistor T2 or the first transistor T1 is controlled to be in a turned-off state, so that the supply voltage flows through the load and is not connected to ground, and no current flows through the load, preventing normal operation. This achieves the function of detecting any one phase voltage, two phase voltages, or three-phase voltage undervoltage or phase loss states.
[0043] In one possible embodiment, see Figure 2 , Figure 2 A circuit diagram of an AC three-phase voltage monitoring circuit provided in an embodiment of this application is shown below. Figure 2 As shown, the three-phase voltage acquisition circuit 100 includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9.
[0044] The first terminal of the first resistor R1 is connected to the A-phase voltage LA. The second terminal of the first resistor R1 is electrically connected to the first terminal of the second resistor R2. The second terminal of the second resistor R2 is electrically connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is electrically connected to the second terminals of the sixth resistor R6 and the ninth resistor R9, respectively.
[0045] The first terminal of the fourth resistor R4 is connected to the B-phase voltage LB. The second terminal of the fourth resistor R4 is electrically connected to the first terminal of the fifth resistor R5. The second terminal of the fifth resistor R5 is electrically connected to the first terminal of the sixth resistor R6.
[0046] The first terminal of the seventh resistor R7 is connected to the C-phase voltage LC. The second terminal of the seventh resistor R7 is electrically connected to the first terminal of the eighth resistor R8. The second terminal of the eighth resistor R8 is electrically connected to the first terminal of the ninth resistor R9.
[0047] The first and second ends of the ninth resistor R9 serve as the output terminals of the three-phase voltage acquisition circuit 100, used to output the first voltage.
[0048] See Figure 2 It should be noted that, Figure 2 The three-phase voltage acquisition circuit 100 in this paper, taking the C-phase voltage LC as an example, illustrates the case where the first voltage is output through the first and second terminals of the ninth resistor R9. The three-phase voltage acquisition circuit 100 can output the first voltage based on any one of the A-phase, B-phase, and C-phase voltages. Specifically, this application can also output the first voltage based on the first and second terminals of the sixth resistor R6 (taking the B-phase voltage as an example), or based on the first and second terminals of the third resistor R3 (taking the A-phase voltage as an example). This application will not provide further examples for each phase.
[0049] In one possible embodiment, see Figure 2 The neutral line voltage acquisition circuit 200 includes: a first diode D1, a tenth resistor R10, and an eleventh resistor R11.
[0050] The anode of the first diode D1 is electrically connected to the second terminal of the third resistor R3, the cathode of the first diode D1 is electrically connected to the first terminal of the tenth resistor R10, and the second terminal of the tenth resistor R10 is electrically connected to the first terminal of the eleventh resistor R11.
[0051] The second terminal of the eleventh resistor R11 is connected to the N-phase voltage LN. The first and second terminals of the eleventh resistor R11 serve as the output terminals of the neutral line voltage acquisition circuit 200, used to output the second voltage.
[0052] In one possible embodiment, see Figure 2 The first control circuit 300 includes: a second diode D2, a twelfth resistor R12, a first optocoupler U1, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a third transistor Q3, and a second capacitor C2.
[0053] The anode of the second diode D2 is electrically connected to the first terminal of the ninth resistor R9, the cathode of the second diode D2 is electrically connected to the first terminal of the first optocoupler U1, the first terminal of the twelfth resistor R12 is electrically connected to the second terminal of the ninth resistor R9, and the second terminal of the twelfth resistor R12 is electrically connected to the second terminal of the first optocoupler U1.
[0054] The fourth terminal of the first optocoupler U1 is electrically connected to the second terminal of the twentieth resistor R20 and the collector of the third transistor Q3, respectively. The first terminal of the twentieth resistor R20 is connected to the power supply voltage +12V.
[0055] The third terminal of the first optocoupler U1 is electrically connected to the first terminal of the nineteenth resistor R19 and the base of the third transistor Q3, respectively. The second terminal of the nineteenth resistor R19 is electrically connected to the second terminal of the twenty-first resistor R21, the second terminal of the second capacitor C2, the first terminal of the second transistor T2, and the second terminal of the first transistor T1, respectively.
[0056] The first terminal of the twenty-first resistor R21 is electrically connected to the emitter of the third transistor Q3, the first terminal of the second capacitor C2, and the first terminal of the twenty-second resistor R22.
[0057] The second terminal of the 22nd resistor R22 is electrically connected to the control terminal of the second transistor T2, and the second terminal of the second transistor T2 is electrically connected to the load.
[0058] In one possible embodiment, see Figure 2 The second control circuit 400 includes: a second optocoupler U2, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a first transistor Q1, a second transistor Q2, and a first capacitor C1.
[0059] The first end of the second optocoupler U2 is electrically connected to the first end of the eleventh resistor R11, and the second end of the second optocoupler U2 is electrically connected to the second end of the eleventh resistor R11.
[0060] The fourth terminal of the second optocoupler U2 is electrically connected to the second terminal of the thirteenth resistor R13 and the collector of the first transistor Q1, respectively. The first terminal of the thirteenth resistor R13 is connected to the power supply voltage +12V.
[0061] The third terminal of the second optocoupler U2 is electrically connected to the first terminal of the fourteenth resistor R14 and the base of the first transistor Q1, respectively. The emitter of the first transistor Q1 is electrically connected to the first terminal of the fifteenth resistor R15, the first terminal of the first capacitor C1, and the first terminal of the sixteenth resistor R16, respectively.
[0062] The second terminal of the sixteenth resistor R16 is electrically connected to the base of the second transistor Q2, and the collector of the second transistor Q2 is electrically connected to the second terminal of the seventeenth resistor R17, the first terminal of the eighteenth resistor R18, and the control terminal of the first transistor T1.
[0063] The first terminal of the seventeenth resistor R17 is connected to the power supply voltage +12V.
[0064] The second terminal of the fourteenth resistor R14, the second terminal of the fifteenth resistor R15, the second terminal of the first capacitor C1, the emitter of the second transistor Q2, the second terminal of the eighteenth resistor R18, and the first terminal of the first transistor T1 are all grounded.
[0065] In one possible embodiment, see Figure 2 Both the first transistor T1 and the second transistor T2 are Darlington transistors.
[0066] When both the first transistor T1 and the second transistor T2 are Darlington transistors, the control terminal of the first transistor T1 is the base of the Darlington transistor, the first terminal of the first transistor T1 is the emitter of the Darlington transistor, and the second terminal of the first transistor T1 is the collector of the Darlington transistor; the control terminal of the second transistor T2 is the base of the Darlington transistor, the first terminal of the second transistor T2 is the emitter of the Darlington transistor, and the second terminal of the second transistor T2 is the collector of the Darlington transistor.
[0067] See Figure 2 Based on the electrical connection relationships of the components in the above circuits, the following describes the working process under normal and abnormal AC three-phase voltage conditions.
[0068] The connection point between the three-phase voltage acquisition circuit 100 and the neutral line voltage acquisition circuit 200, that is, the connection point between the second end of the third resistor R3 and the anode of the first diode D1, is defined as node LN1; the connection point between the second end of the eleventh resistor R11 and the second end of the second optocoupler U2 is defined as node LN0.
[0069] For the three-phase AC voltage consisting of phase A voltage LA, phase B voltage LB, and phase C voltage LC, the rated voltage is set to AC230V. If the three-phase AC voltage is in a voltage balance state, the voltage difference from node LN1 to node LN0 through the first diode D1, the tenth resistor R10, and the eleventh resistor R11 is almost zero. At this time, the input diode inside the second optocoupler U2 is not conducting, which makes the output transistor inside the second optocoupler U2 not conducting. Therefore, the first transistor Q1 and the second transistor Q2 are also not conducting. The +12V supply voltage is divided by the seventeenth resistor R17 and the eighteenth resistor R18, which makes the first transistor T1 conduct.
[0070] When all three phase voltages of the AC three-phase voltage are normal, the voltage of phase C voltage LC reaching node LN1 after passing through resistors R7 (seventh), R8 (eighth), and R9 (ninth) is large enough. The first voltage output from the first and second terminals of resistor R9 is also large enough, causing the input diode inside the first optocoupler U1 to conduct and the output transistor inside the first optocoupler U1 to conduct. At this time, the third transistor Q3 also conducts, and the supply voltage +12V charges the second capacitor C2. When the voltage of the second capacitor C2 rises to a sufficient voltage, the second transistor T2 conducts.
[0071] When all three phases of the AC three-phase voltage are normal and in a voltage balance state (i.e., when the AC three-phase voltage is in a normal state), both the first transistor T1 and the second transistor T2 are in the conducting state, so that the +12V supply voltage flows through the load and is connected to ground, and current flows through the load, allowing it to work normally.
[0072] When any one or two phases of a three-phase AC voltage are in a state of undervoltage or phase loss, and the voltage is unbalanced, the voltage difference between node LN1 and node LN0 is large. At this time, the input diode inside the second optocoupler U2 is turned on, which causes the output transistor inside the second optocoupler U2 to be turned on. Then the first transistor Q1 is also turned on, and the supply voltage +12V charges the first capacitor C1. When the voltage of the first capacitor C12 rises to a sufficient voltage, the second transistor Q2 is turned on. The collector voltage of the second transistor Q2 is pulled down, and it cannot drive the first transistor T1. At this time, the first transistor T1 is not turned on and is in the off state.
[0073] When the AC three-phase voltage is in the second abnormal state (i.e., any one or two phases of the AC three-phase voltage are in a state of undervoltage or phase loss, and the voltage is unbalanced), the first transistor T1 is in the off state. Under this condition, the supply voltage +12V does not conduct to ground after flowing through the load, and no current flows through the load, so it cannot work normally.
[0074] When all three phases of the AC three-phase voltage are simultaneously undervoltage and the three-phase voltage is still in a voltage balance state, the voltage difference between node LN1 and node LN0 is almost zero. At this time, the input diode inside the second optocoupler U2 is not conducting, which makes the output transistor inside the second optocoupler U2 not conducting. Therefore, the first transistor Q1 and the second transistor Q2 are also not conducting. After the supply voltage +12V is divided by the seventeenth resistor R17 and the eighteenth resistor R18, the first transistor T1 is turned on.
[0075] However, at the same time, since the three phases of the AC three-phase voltage (i.e., phase A voltage LA, phase B voltage LB, and phase C voltage LC) are simultaneously undervoltage, the phase C voltage LC, after passing through the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9, does not reach node LN1 sufficiently. The first voltage output from the first and second terminals of the ninth resistor R9 is not large enough to drive the input diode inside the first optocoupler U1 to conduct, and the output transistor inside the first optocoupler U1 also cannot drive the third transistor Q3 to conduct. At this time, after the charge of the second capacitor C2 is consumed, it cannot drive the base of the second transistor T2, so the second transistor T2 does not conduct and is in the off state.
[0076] When the AC three-phase voltage is in the first abnormal state (i.e., all three phases of the AC three-phase voltage are undervoltage and the voltage is balanced), the first transistor T1 is in the conducting state and the second transistor T2 is in the off state. Under this condition, the supply voltage +12V does not conduct to ground after flowing through the load, and no current flows through the load, so it cannot work normally.
[0077] In summary, the AC three-phase voltage monitoring circuit provided in this application, when the AC three-phase voltage is in a normal state, controls the first transistor T1 and the second transistor T2 to be in a conducting state, so that the supply voltage flows through the load and is connected to ground, and current flows through the load, allowing normal operation. When the AC three-phase voltage is in a first abnormal state, controls the first transistor T1 to be in a conducting state and the second transistor T2 to be in a turning-off state, so that the supply voltage flows through the load and is not connected to ground, and no current flows through the load, preventing normal operation. When the AC three-phase voltage is in a second abnormal state, controls the first transistor T1 to be in a turning-off state, so that the supply voltage flows through the load and is not connected to ground, and no current flows through the load, preventing normal operation. This achieves the function of detecting any one phase voltage, two phase voltages, or three-phase voltage in a state of undervoltage or phase loss.
[0078] This application also provides a switching converter, including: the AC three-phase voltage monitoring circuit as described above.
[0079] The switching converter can be used for ATS dual-power products.
[0080] This application also provides a power switching system, including the switching converter as described above.
[0081] The power switching system may also include a backup power supply and a primary power supply, which are used to switch between the backup power supply and the primary power supply through a switching converter.
[0082] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An AC three-phase voltage monitoring circuit, characterized in that, The AC three-phase voltage monitoring includes: a three-phase voltage acquisition circuit, a neutral voltage acquisition circuit, a first control circuit, a second control circuit, a first transistor, and a second transistor; The three-phase voltage acquisition circuit is electrically connected to the neutral voltage acquisition circuit and the first control circuit, respectively. The neutral voltage acquisition circuit is electrically connected to the second control circuit. The first control circuit is electrically connected to the second transistor. The second control circuit is electrically connected to the first transistor. The first transistor is electrically connected to the second transistor. The supply voltage flows through the load, the second transistor, and the first transistor before being grounded. The three-phase voltage acquisition circuit is used to output a first voltage based on any one of the phase voltages of phase A, phase B, and phase C. The neutral voltage acquisition circuit is used to output a second voltage based on the N-phase voltage; The first control circuit is used to output a first control signal according to the first voltage to control the switching state of the second transistor, so that when the AC three-phase voltage is in a normal state, the supply voltage flows through the load and is connected to ground; so that when the AC three-phase voltage is in an abnormal state, the supply voltage flows through the load and is not connected to ground. The second control circuit is used to output a second control signal according to the second voltage to control the switching state of the first transistor, so that when the AC three-phase voltage is in the normal state, the supply voltage flows through the load and is connected to ground; so that when the AC three-phase voltage is in the abnormal state, the supply voltage flows through the load and is not connected to ground. The abnormal states include: a first abnormal state and a second abnormal state. The first abnormal state is that all three phases of the AC three-phase voltage are in a state of undervoltage and the voltage is balanced. The second abnormal state is that any one or two phases of the AC three-phase voltage are in a state of undervoltage or phase loss and the voltage is unbalanced.
2. The AC three-phase voltage monitoring circuit according to claim 1, characterized in that, The first control circuit is specifically used to output the first control signal according to the first voltage, and control the second transistor to be in the conducting state when the AC three-phase voltage is in the normal state, and in the off state when the AC three-phase voltage is in the first abnormal state.
3. The AC three-phase voltage monitoring circuit according to claim 2, characterized in that, The second control circuit is specifically used to output a second control signal according to the second voltage, and control the first transistor to be in the on state when the AC three-phase voltage is in the normal state; in the off state when the AC three-phase voltage is in the second abnormal state; and in the on state when the AC three-phase voltage is in the first abnormal state.
4. The AC three-phase voltage monitoring circuit according to claim 3, characterized in that, The three-phase voltage acquisition circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor; The first end of the first resistor is connected to the A-phase voltage, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the sixth resistor and the second end of the ninth resistor, respectively. The first end of the fourth resistor is connected to the B-phase voltage, the second end of the fourth resistor is electrically connected to the first end of the fifth resistor, and the second end of the fifth resistor is electrically connected to the first end of the sixth resistor. The first end of the seventh resistor is connected to the C-phase voltage, the second end of the seventh resistor is electrically connected to the first end of the eighth resistor, and the second end of the eighth resistor is electrically connected to the first end of the ninth resistor. The first and second ends of the ninth resistor serve as the output terminals of the three-phase voltage acquisition circuit, used to output the first voltage.
5. The AC three-phase voltage monitoring circuit according to claim 4, characterized in that, The neutral line voltage acquisition circuit includes: a first diode, a tenth resistor, and an eleventh resistor; The anode of the first diode is electrically connected to the second terminal of the third resistor, the cathode of the first diode is electrically connected to the first terminal of the tenth resistor, and the second terminal of the tenth resistor is electrically connected to the first terminal of the eleventh resistor. The second end of the eleventh resistor is connected to the N-phase voltage, and the first and second ends of the eleventh resistor serve as the output terminals of the neutral line voltage acquisition circuit for outputting the second voltage.
6. The AC three-phase voltage monitoring circuit according to claim 4, characterized in that, The first control circuit includes: a second diode, a twelfth resistor, a first optocoupler, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a twenty-second resistor, a third transistor, and a second capacitor; The anode of the second diode is electrically connected to the first terminal of the ninth resistor, the cathode of the second diode is electrically connected to the first terminal of the first optocoupler, the first terminal of the twelfth resistor is electrically connected to the second terminal of the ninth resistor, and the second terminal of the twelfth resistor is electrically connected to the second terminal of the first optocoupler. The fourth terminal of the first optocoupler is electrically connected to the second terminal of the twentieth resistor and the collector of the third transistor, respectively, and the first terminal of the twentieth resistor is connected to the power supply voltage; The third terminal of the first optocoupler is electrically connected to the first terminal of the nineteenth resistor and the base of the third transistor, respectively. The second terminal of the nineteenth resistor is electrically connected to the second terminal of the twenty-first resistor, the second terminal of the second capacitor, the first terminal of the second transistor, and the second terminal of the first transistor, respectively. The first end of the 21st resistor is electrically connected to the emitter of the third transistor, the first end of the second capacitor, and the first end of the 22nd resistor, respectively. The second terminal of the twelfth resistor is electrically connected to the control terminal of the second transistor, and the second terminal of the second transistor is electrically connected to the load.
7. The AC three-phase voltage monitoring circuit according to claim 5, characterized in that, The second control circuit includes: a second optocoupler, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a first transistor, a second transistor, and a first capacitor; The first end of the second optocoupler is electrically connected to the first end of the eleventh resistor, and the second end of the second optocoupler is electrically connected to the second end of the eleventh resistor. The fourth terminal of the second optocoupler is electrically connected to the second terminal of the thirteenth resistor and the collector of the first transistor, respectively, and the first terminal of the thirteenth resistor is connected to the power supply voltage; The third end of the second optocoupler is electrically connected to the first end of the fourteenth resistor and the base of the first transistor, respectively. The emitter of the first transistor is electrically connected to the first end of the fifteenth resistor, the first end of the first capacitor, and the first end of the sixteenth resistor, respectively. The second end of the sixteenth resistor is electrically connected to the base of the second transistor, and the collector of the second transistor is electrically connected to the second end of the seventeenth resistor, the first end of the eighteenth resistor, and the control terminal of the first transistor, respectively. The first terminal of the seventeenth resistor is connected to the power supply voltage; The second terminal of the fourteenth resistor, the second terminal of the fifteenth resistor, the second terminal of the first capacitor, the emitter of the second transistor, the second terminal of the eighteenth resistor, and the first terminal of the first transistor are all grounded.
8. The AC three-phase voltage monitoring circuit according to claim 3, characterized in that, Both the first transistor and the second transistor are Darlington transistors.
9. A switching converter, characterized in that, include: The AC three-phase voltage monitoring circuit as described in any one of claims 1-8.
10. A power switching system, characterized in that, include: The switching converter as described in claim 9.