Isolation electrification detection circuit and control system of circuit breaker

Abstract

The utility model provides an isolation electrification detection circuit and a control system of a circuit breaker. The isolation electrification detection circuit comprises a control signal isolation conversion unit, a switch unit, a detection signal isolation conversion unit and a detection circuit. The input end of the control signal isolation conversion unit is connected with a control signal output by the control unit, the output end of the control signal isolation conversion unit is electrically connected with the driving end of the switch unit, the input end of the switch unit is electrically connected with the output end of the circuit breaker, and the output end of the switch unit is electrically connected with the input end of the detection circuit. The output end of the detection circuit is electrically connected with the input end of the detection signal isolation conversion unit, and the output end of the detection signal isolation conversion unit outputs a detection signal to the control unit. The switch is conducted only when live detection needs to be carried out, and is kept disconnected in other time, so that power consumption caused by live detection can be greatly reduced; in addition, electrical isolation is kept, crosstalk between strong current and weak current is avoided, and the reliability of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit breakers, and particularly relates to an isolated live detection circuit and a control system of a circuit breaker. Background Art

[0002] A circuit breaker is usually connected in series between a mains power grid and an electrical load, and the power supply and power-off of the mains power grid to the electrical load are controlled by controlling the on-off of the circuit breaker. In addition, the output end of the circuit breaker is also used to be electrically connected to the output end of an inverter, and the power transmission of the inverter to the mains power grid and the stop of power transmission are controlled by controlling the on-off of the circuit breaker.

[0003] When the inverter fails to be turned off in time, it means that its output end is live. If the circuit breaker is closed at this time, the components in the inverter will be burned out because the voltage output by the inverter cannot match the voltage output by the mains power grid. Therefore, it is necessary to perform live detection on the output end of the circuit breaker and the output end of the inverter to ensure the reliability and safety of the circuit breaker closing.

[0004] However, the reliability of the existing live detection scheme is poor and the power consumption is high. Summary of the Utility Model

[0005] Aiming at the deficiencies in the prior art, the utility model provides an isolated live detection circuit and a control system of a circuit breaker.

[0006] In a first aspect, in one embodiment, the utility model provides an isolated live detection circuit, and the isolated live detection circuit includes:

[0007] A control signal isolation and conversion unit, a switch unit, a detection signal isolation and conversion unit, and a detection circuit;

[0008] The input end of the control signal isolation and conversion unit is used to access the control signal output by the control unit. The output end of the control signal isolation and conversion unit is electrically connected to the driving end of the switch unit. The input end of the switch unit is used to be electrically connected to the output end of the circuit breaker and the output end of the inverter respectively. The output end of the switch unit is electrically connected to the input end of the detection circuit. The output end of the detection circuit is electrically connected to the input end of the detection signal isolation and conversion unit. The output end of the detection signal isolation and conversion unit is used to output a detection signal to the control unit.

[0009] In one embodiment, the control signal isolation and conversion unit and the switch unit form a first optocoupler;

[0010] The anode of the light-emitting diode in the first optocoupler is used to connect to the control signal output by the control unit, the cathode of the light-emitting diode in the first optocoupler is grounded, the collector of the photo-sensitive triode in the first optocoupler is used to be electrically connected to the live wire output terminal of the circuit breaker, and the emitter of the photo-sensitive triode in the first optocoupler is electrically connected to the input terminal of the detection circuit.

[0011] In one embodiment, the isolated live detection circuit further includes a first pull-up resistor;

[0012] The anode of the light-emitting diode in the first optocoupler is used to connect to the control signal output by the control unit through the first pull-up resistor.

[0013] In one embodiment, the detection signal isolation and conversion unit includes a second optocoupler;

[0014] The anode of the light-emitting diode in the second optocoupler is electrically connected to the output terminal of the detection circuit, the cathode of the light-emitting diode in the second optocoupler is used to be electrically connected to the neutral wire output terminal of the circuit breaker, the collector of the photo-sensitive triode in the second optocoupler is used to output a detection signal to the control unit, and the emitter of the photo-sensitive triode in the second optocoupler is grounded.

[0015] In one embodiment, the isolated live detection circuit further includes a second pull-up resistor;

[0016] The collector of the photo-sensitive triode in the second optocoupler is used to output a detection signal to the control unit through the second pull-up resistor.

[0017] In one embodiment, the detection circuit includes a capacitor, a zener diode, a voltage-drop resistor, a discharge resistor, an NPN-type triode, and a PNP-type triode;

[0018] The first end of the capacitor is electrically connected to the emitter of the photo-sensitive triode in the first optocoupler, the emitter of the PNP-type triode, and the first end of the voltage-drop resistor respectively. The base of the PNP-type triode is electrically connected to the second end of the voltage-drop resistor, the cathode of the zener diode, and the collector of the NPN-type triode respectively. The collector of the PNP-type triode is electrically connected to the base of the NPN-type triode and the first end of the discharge resistor respectively. The second end of the discharge resistor is electrically connected to the emitter of the NPN-type triode and the anode of the light-emitting diode in the second optocoupler respectively. The second end of the capacitor and the anode of the zener diode are electrically connected to the cathode of the light-emitting diode in the second optocoupler respectively.

[0019] In one embodiment, the isolated live detection circuit further includes a rectification unit;

[0020] The input terminal of the rectification unit is used to be electrically connected to the output terminal of the circuit breaker and the output terminal of the inverter respectively, and the output terminal of the rectification unit is electrically connected to the input terminal of the switch unit.

[0021] In one embodiment, the rectification unit includes a rectifier diode;

[0022] The anode of the rectifying diode is used to be electrically connected to the output terminals of the circuit breaker and the inverter respectively, and the cathode of the rectifying diode is electrically connected to the input terminal of the switching unit.

[0023] In one embodiment, the isolated live detection circuit further includes a current limiting unit;

[0024] The input terminal of the current limiting unit is used to be electrically connected to the output terminals of the circuit breaker and the inverter respectively, and the output terminal of the current limiting unit is electrically connected to the input terminal of the switching unit.

[0025] In a second aspect, in one embodiment, the present utility model provides a control system for a circuit breaker, including a circuit breaker, a control unit, and the isolated live detection circuit in any one of the above embodiments;

[0026] The input terminal of the circuit breaker is used to be electrically connected to the mains power grid, the output terminal of the circuit breaker is used to be electrically connected to an electrical load and the output terminal of the inverter respectively, and the driving terminal of the circuit breaker is used to receive the driving signal output by the control unit.

[0027] Through the above isolated live detection circuit and the control system of the circuit breaker, by setting the switching unit, it can be made to conduct only when live detection is required, and remain disconnected at other times. Compared with continuous conduction, it can greatly reduce the power consumption generated by live detection; in addition, by separately setting the control signal isolation conversion unit and the detection signal isolation conversion unit, it fully ensures electrical isolation between the control unit and the output terminal of the circuit breaker, avoiding crosstalk between strong and weak currents and improving the system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 It is a schematic structural diagram of an isolated live detection circuit in an embodiment of the present utility model;

[0030] Figure 2 It is a schematic circuit implementation diagram of an isolated live detection circuit in an embodiment of the present utility model;

[0031] Figure 3 It is a schematic structural diagram of an isolated live detection circuit including a rectifying unit and a current limiting unit in an embodiment of the present utility model;

[0032] Figure 4Schematic diagram of the control system of the circuit breaker in an embodiment of the present utility model;

[0033] Figure 5 Waveform diagram of the capacitor voltage and the detection signal when the input voltage is single-phase 20Vac in an embodiment of the present utility model;

[0034] Figure 6 Waveform diagram of the capacitor voltage and the detection signal when the input voltage is single-phase 310Vac in an embodiment of the present utility model;

[0035] Figure 7 Waveform diagram of the capacitor voltage and the detection signal when the input voltage is three-phase 310Vac in an embodiment of the present utility model. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present utility model.

[0037] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" 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. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically defined. In the present application, the term "exemplary" is used to mean "serving as an example, illustration, or explanation". Any embodiment described as "exemplary" in the present application is not necessarily to be construed as more preferred or more advantageous than other embodiments. In order for any person skilled in the art to implement and use the present utility model, the following description is given. In the following description, details are set forth for purposes of explanation. It should be understood that those of ordinary skill in the art can recognize that the present utility model can be implemented without the use of these specific details. In other instances, well-known structures and processes are not elaborated in detail so as not to obscure the description of the present utility model with unnecessary details. Therefore, the present utility model is not intended to be limited to the embodiments shown, but is consistent with the broadest scope that conforms to the principles and features disclosed in the present application.

[0038] In a first aspect, as Figure 1 shown, in one embodiment, the present utility model provides an isolated live detection circuit, and the isolated live detection circuit includes a control signal isolation and conversion unit, a switch unit, a detection signal isolation and conversion unit, and a detection circuit.

[0039] The input end of the control signal isolation and conversion unit is used to access the control signal output by the control unit. The output end of the control signal isolation and conversion unit is electrically connected to the driving end of the switch unit. The input end of the switch unit is used to be respectively electrically connected to the output end of the circuit breaker and the output end of the inverter. The output end of the switch unit is electrically connected to the input end of the detection circuit. The output end of the detection circuit is electrically connected to the input end of the detection signal isolation and conversion unit. The output end of the detection signal isolation and conversion unit is used to output a detection signal to the control unit.

[0040] Among them, since the output end of the circuit breaker usually corresponds to a strong electrical environment, while the control unit corresponds to a weak electrical environment, the control signal isolation and conversion unit and the detection signal isolation and conversion unit are both used to achieve electrical isolation to avoid crosstalk between strong and weak electricity. In this embodiment, the control signal isolation and conversion unit and the detection signal isolation and conversion unit can adopt a transformer, and use the electromagnetic induction between the primary winding and the secondary winding in the transformer to achieve signal transmission. Since there is no wiring between the primary winding and the secondary winding, electrical isolation can be achieved.

[0041] Among them, when live detection is required, the control unit outputs a corresponding control signal through the control signal isolation and conversion unit to control the switch unit to conduct, so that the line between the input end of the detection circuit and the output end of the circuit breaker is connected, so that the detection circuit can perform live detection on the output end of the circuit breaker to determine whether the output end of the circuit breaker is live, and finally outputs a corresponding detection signal to the control unit through the detection signal isolation and conversion unit.

[0042] Among them, similarly, when live detection is not required, the control unit outputs a corresponding control signal through the control signal isolation and conversion unit to control the switch unit to disconnect, so that the line between the input end of the detection circuit and the output end of the circuit breaker is disconnected, so that the detection circuit cannot perform live detection on the output end of the circuit breaker.

[0043] Among them, the switch unit can adopt various typical switching devices or apparatuses. For example, in this embodiment, the switch unit can adopt mechanical switches such as contactors and relays or semiconductor switches such as MOS transistors and IGBT transistors.

[0044] Among them, the input end of the inverter can be used to be electrically connected to the photovoltaic panel or can also be used to be electrically connected to other DC power generation devices.

[0045] Through the above isolation live detection circuit, by setting the switch unit, it can be made to conduct only when live detection is required and remain disconnected at other times. Compared with continuous conduction, it can greatly reduce the power consumption generated by live detection; in addition, by separately setting the control signal isolation and conversion unit and the detection signal isolation and conversion unit, it fully guarantees electrical isolation between the control unit and the output end of the circuit breaker, avoids crosstalk between strong and weak electricity, and improves system reliability.

[0046] Such as Figure 2 As shown, in one embodiment, the control signal isolation and conversion unit and the switch unit form the first optocoupler U1.

[0047] In Figure 2Among them, the anode of the light-emitting diode in the first optocoupler U1 is used to connect to the control signal MCU_ctrl output by the control unit, the cathode of the light-emitting diode in the first optocoupler U1 is grounded, the collector of the phototransistor in the first optocoupler U1 is used to be electrically connected to the live wire output terminals (A1, B1, and C1) of the circuit breaker, and the emitter of the phototransistor in the first optocoupler U1 is electrically connected to the input terminal of the detection circuit (such as Figure 2 the emitter of the PNP-type transistor, the first end of the voltage drop resistor R17, and the first end of the capacitor CE1 in

[0048] Among them, the optocoupler can realize signal transmission and electrical isolation through the conversion from optical signal to electrical signal. Therefore, the optocoupler can meet the requirements of both electrical isolation and signal transmission at the same time. That is to say, the first optocoupler U1 can realize the functions required by the control signal isolation conversion unit and the switch unit in the above embodiments at the same time.

[0049] Among them, the anode of the light-emitting diode in the first optocoupler U1 is electrically connected to the control unit through the first pull-up resistor R19. When the control signal MCU_ctrl output by the control unit is in a high-impedance state or a high level, the operating voltage connected by the first pull-up resistor R19 can pass through the light-emitting diode in the first optocoupler U1 and then to the ground, so that the light-emitting diode in the first optocoupler U1 emits light; conversely, when the control signal MCU_ctrl output by the control unit is GND, the operating voltage connected by the first pull-up resistor R19 cannot pass through the light-emitting diode in the first optocoupler U1 and then to the ground, so that the light-emitting diode in the first optocoupler U1 does not emit light.

[0050] Such as Figure 2 shown, in one embodiment, the detection signal isolation conversion unit includes a second optocoupler U2.

[0051] In Figure 2 Among them, the anode of the light-emitting diode in the second optocoupler U2 is electrically connected to the output terminal of the detection circuit (such as Figure 2 the second end of the discharge resistor R18 and the emitter of the NPN-type transistor Q2 in

[0052] Among them, the collector of the photosensitive triode in the second optocoupler U2 is electrically connected to the control unit through the second pull-up resistor R20. When the photosensitive triode in the second optocoupler U2 is turned on, the operating voltage connected to the second pull-up resistor R20 passes through the photosensitive triode in the second optocoupler U2 and then to the ground, and the output detection signal MCU_GF is at a low level; conversely, when the photosensitive triode in the second optocoupler U2 is turned off, the operating voltage connected to the second pull-up resistor R20 cannot pass through the photosensitive triode in the second optocoupler U2 and then to the ground, and the output detection signal MCU_GF is at a high level.

[0053] Among them, similarly, in theory, the detection circuit and the detection signal isolation and conversion unit can also form an optocoupler. When two optocouplers are used, the output terminal of one optocoupler can be directly electrically connected to the input terminal of the other optocoupler. For example, in Figure 2 , the emitter of the photosensitive triode in the first optocoupler U1 is directly electrically connected to the anode of the light-emitting diode in the second optocoupler U2; however, when the voltage at the input terminal of the circuit breaker is relatively high, it is easy to exceed the breakdown voltage of the two optocouplers, resulting in damage to the two optocouplers. Therefore, the direct electrical connection method of the two optocouplers can only be applied to the case where the voltage at the input terminal of the circuit breaker is relatively small. To solve the problem that the relatively high voltage at the input terminal of the circuit breaker is likely to cause damage to the two optocouplers, a resistor with a relatively large resistance value can be connected in series between the two optocouplers. For example, in Figure 2 , the first end of the resistor is electrically connected to the emitter of the photosensitive triode in the first optocoupler U1, and the second end of the resistor is electrically connected to the anode of the light-emitting diode in the second optocoupler U2. The resistor is used to achieve voltage division and current limiting, thereby protecting the two optocouplers from being damaged; however, when the voltage at the input terminal of the circuit breaker is relatively small, the voltage on the loop may not be able to drive the optocoupler to conduct, and thus it cannot work properly. Therefore, the electrical connection method of the two optocouplers through a resistor can only be applied to the case where the voltage at the input terminal of the circuit breaker is relatively high.

[0054] To sum up, when the detection circuit and the detection signal isolation and conversion unit form an optocoupler, although the corresponding functions can be theoretically achieved, its application range has great limitations and it is difficult to be applied to the wide voltage change scenario at the input terminal of the circuit breaker, resulting in poor practical application value.

[0055] Among them, it should be noted that in Figure 2Among them, the live wire output terminals of the circuit breaker include A1, B1, and C1, and the neutral wire output terminal of the circuit breaker includes N1, which are correspondingly connected to three-phase four-wire alternating current. However, in other embodiments, the live wire output terminal of the circuit breaker may also only include L, and the neutral wire output terminal of the circuit breaker includes N, then it is correspondingly connected to single-phase two-wire alternating current. Or in other embodiments, the live wire output terminal of the circuit breaker may also only include V+, and the neutral wire output terminal of the circuit breaker includes V-, then it is correspondingly connected to direct current. That is to say, the live wire output terminal and the neutral wire output terminal of the circuit breaker do not limit the type of power supply they are connected to, including direct current and alternating current. For alternating current, it can also include three-phase electricity and single-phase electricity.

[0056] As Figure 2 shown, in one embodiment, the detection circuit includes a capacitor CE1, a zener diode D6, a voltage drop resistor R17, a discharge resistor R18, a PNP-type triode Q1, and an NPN-type triode Q2.

[0057] In Figure 2 it, the first end of the capacitor CE1 is electrically connected to the emitter of the photosensitive triode in the first optocoupler U1, the emitter of the PNP-type triode Q1, and the first end of the voltage drop resistor R17 respectively. The base of the PNP-type triode Q1 is electrically connected to the second end of the voltage drop resistor R17, the cathode of the zener diode D6, and the collector of the NPN-type triode Q2 respectively. The collector of the PNP-type triode Q1 is electrically connected to the base of the NPN-type triode Q2 and the first end of the discharge resistor R18 respectively. The second end of the discharge resistor R18 is electrically connected to the emitter of the NPN-type triode Q2 and the anode of the light-emitting diode in the second optocoupler U2 respectively. The second end of the capacitor CE1 and the anode of the zener diode D6 are electrically connected to the cathode of the light-emitting diode in the second optocoupler U2 respectively.

[0058] Among them, when the photosensitive triode in the first optocoupler U1 conducts, the circuit between the first end of the capacitor CE1 and the live wire output terminals (A1, B1, and C1) of the circuit breaker is connected. The applied voltage charges the capacitor CE1 through the first optocoupler U1. The voltage on the capacitor CE1 continuously rises until it reaches the breakdown voltage of the zener diode D6, at which point the zener diode D6 breaks down and conducts. A loop is formed among the live wire output terminals (A1, B1, and C1) of the circuit breaker, the first optocoupler U1, the voltage dropping resistor R17, and the neutral wire output terminal N1 of the circuit breaker. A current is generated on the voltage dropping resistor R17, so that there is a certain voltage difference between the first end and the second end of the voltage dropping resistor R17, and further there is a certain voltage difference between the emitter and the base of the PNP type triode Q1, which meets the biasing requirement and conducts. The energy on the capacitor CE1 is discharged through the PNP type triode, the discharging resistor R18, and the light emitting diode in the second optocoupler U2. The photosensitive triode in the second optocoupler U2 conducts. When the energy on the capacitor CE1 is discharged until its voltage is lower than the breakdown voltage of the zener diode D6, the zener diode D6 returns to the cut-off state. The base voltage of the PNP type triode Q1 is discharged through the NPN type triode Q2, so that the PNP type triode Q1 is quickly turned off, the light emitting diode in the second optocoupler U2 stops emitting light, and the photosensitive triode in the second optocoupler U2 disconnects. Due to the existence of the discharging resistor R18, the parasitic voltage between the base and the emitter of the NPN type triode Q2 is also discharged, so that the NPN type triode Q2 is also turned off.

[0059] Among them, due to the existence of the zener diode D6, regardless of whether the voltage applied to the live wire output terminals (A1, B1, and C1) of the circuit breaker is too high, as long as it reaches the breakdown voltage of the zener diode D6, the energy on the capacitor CE1 is immediately discharged through the PNP type triode, the discharging resistor R18, and the second optocoupler U2. In addition, it can also be discharged through the voltage dropping resistor R17, the NPN type triode Q2, and the second optocoupler U2, so as to control the voltage on the capacitor CE1 from never being too high, so that the voltage applied to the first optocoupler U1 and the voltage output to the second optocoupler U2 through the PNP type triode Q1 can both be controlled at a small value, and finally the first optocoupler U1 and the second optocoupler U2 can be protected from being damaged. In addition, since there is no resistor with a large resistance in series between the first optocoupler U1 and the second optocoupler U2, when the voltage applied to the live wire output terminals (A1, B1, and C1) of the circuit breaker is small, the second optocoupler U2 can also be driven to conduct. It should be noted that when the voltage dropping resistor R17 participates in discharging, it is used for current limiting to avoid the energy on the capacitor CE1 from being discharged too quickly.

[0060] In summary, through the detection circuit in this embodiment, it can be applicable to both the scenarios of too small or too high voltage, meeting the wide voltage change requirements of the output terminal of the circuit breaker.

[0061] Such asFigure 3 As shown, in one embodiment, the isolated live detection circuit further includes a rectification unit and a current limiting unit.

[0062] In Figure 3 , the input end of the current limiting unit is used to be electrically connected to the output end of the circuit breaker and the output end of the inverter respectively, the output end of the current limiting unit is electrically connected to the input end of the rectification unit, and the output end of the rectification unit is electrically connected to the input end of the switching unit.

[0063] Among them, the current limiting unit is used to limit the current output to the subsequent stage to avoid burning out the related devices in the subsequent stage.

[0064] Among them, the rectification unit is used to rectify the alternating current when the alternating current is connected to the output end of the circuit breaker, so as to output direct current to the subsequent stage, ensuring that the related devices in the subsequent stage can work normally and will not be damaged by the reverse voltage of the alternating current.

[0065] As Figure 2 shown, in one embodiment, the rectification unit includes rectifier diodes D3, D4 and D5.

[0066] In Figure 2 , the anode of rectifier diode D3 is used to be electrically connected to the live wire output end A1 of the circuit breaker, and the cathode of rectifier diode D3 is electrically connected to the input end of the switching unit (electrically connected to the collector of the photosensitive triode in the first optocoupler U1 through resistor R16). Similarly, the anode of rectifier diode D4 is used to be electrically connected to the live wire output end B1 of the circuit breaker, and the cathode of rectifier diode D4 is electrically connected to the collector of the photosensitive triode in the first optocoupler U1 through resistor R16; the anode of rectifier diode D5 is used to be electrically connected to the live wire output end C1 of the circuit breaker, and the cathode of rectifier diode D5 is electrically connected to the collector of the photosensitive triode in the first optocoupler U1 through resistor R16.

[0067] Among them, rectifier diodes D3, D4 and D5 are all used to rectify the live wire, and in Figure 2 , it further includes rectifier diodes D1 and D2 for rectifying the neutral wire. The cathode of rectifier diode D1 is used to be electrically connected to the neutral wire output end N1 of the circuit breaker, the anode of rectifier diode D1 is electrically connected to the cathode of rectifier diode D2, and the anode of rectifier diode D2 is electrically connected to the second end of capacitor CE1, the anode of zener diode D6 and the cathode of the light emitting diode in the second optocoupler U2 respectively.

[0068] Among them, a diode is used to achieve rectification, which is simple, efficient, and low in cost. However, this application is used for live detection of the output terminal of the circuit breaker, so the real-time requirement is relatively high. The diode can only achieve half-wave rectification. When live detection is required, if the negative half-wave is just connected to the output terminal of the circuit breaker, the live detection result cannot be obtained based on the negative half-wave, and only continuous detection can be performed, waiting for the positive half-wave of the next cycle, which may affect the real-time performance of the detection. The above-mentioned real-time problem may only occur theoretically. Usually, only half-wave rectification can also meet the real-time requirement. If in other embodiments, it is necessary to further improve the real-time performance, a rectifier bridge can be used to replace the diode to achieve full-wave rectification.

[0069] In one embodiment, the current limiting unit includes a first current limiting unit, a second current limiting unit, and a third current limiting unit.

[0070] Among them, in Figure 2 the first current limiting unit includes a current limiting resistor R1, a current limiting resistor R4, a current limiting resistor R7, a current limiting resistor R10, and a current limiting resistor R13 connected in series in sequence. The second current limiting unit includes a current limiting resistor R2, a current limiting resistor R5, a current limiting resistor R8, a current limiting resistor R11, and a current limiting resistor R14 connected in series in sequence. The third current limiting unit includes a current limiting resistor R3, a current limiting resistor R6, a current limiting resistor R9, a current limiting resistor R12, and a current limiting resistor R15 connected in series in sequence.

[0071] Among them, the first end of the current limiting resistor R1 in the first current limiting unit is electrically connected to the live wire output terminal A1 of the circuit breaker, and the second end of the current limiting resistor R13 in the first current limiting unit is electrically connected to the anode of the rectifying diode D3. The first current limiting unit is used to limit the current of the single-phase alternating current connected to the live wire output terminal A1 of the circuit breaker.

[0072] Among them, the first end of the current limiting resistor R2 in the second current limiting unit is electrically connected to the live wire output terminal B1 of the circuit breaker, and the second end of the current limiting resistor R14 in the second current limiting unit is electrically connected to the anode of the rectifying diode D4. The second current limiting unit is used to limit the current of the single-phase alternating current connected to the live wire output terminal B1 of the circuit breaker.

[0073] Among them, the first end of the current limiting resistor R3 in the third current limiting unit is electrically connected to the live wire output terminal C1 of the circuit breaker, and the second end of the current limiting resistor R15 in the third current limiting unit is electrically connected to the anode of the rectifying diode D5. The third current limiting unit is used to limit the current of the single-phase alternating current connected to the live wire output terminal C1 of the circuit breaker.

[0074] Second, as Figure 4 shown, in one embodiment, the present invention provides a control system for a circuit breaker, including a circuit breaker, a control unit, and the isolation live detection circuit in any of the above embodiments;

[0075] The input end of the circuit breaker is used for electrical connection with the mains power grid, the output end of the circuit breaker is used for electrical connection with the electrical load and the output end of the inverter respectively, and the drive end of the circuit breaker is used for accessing the drive signal output by the control unit.

[0076] Through the control system of the above-mentioned circuit breaker, a switching unit is set, which can be turned on only when live detection is required and remains off at other times. Compared with continuous conduction, it can greatly reduce the power consumption caused by live detection; in addition, a control signal isolation conversion unit and a detection signal isolation conversion unit are respectively set to fully ensure electrical isolation between the control unit and the output end of the circuit breaker, avoid crosstalk between strong and weak currents, and improve system reliability.

[0077] In a third aspect, in an embodiment, the present invention provides a control method for a circuit breaker. The control method for the circuit breaker is applied to the control system of the circuit breaker in any of the above embodiments; referring to Figure 4 the system structure in, the control method for the circuit breaker includes the following steps executed by the control unit:

[0078] When the circuit breaker is closed or the circuit breaker is not closed but no closing signal is received, a control signal indicating that the switching unit is off is output to the control signal isolation conversion unit.

[0079] Among them, live detection needs to be carried out before the circuit breaker is closed to ensure the reliability and safety of the circuit breaker closing. Therefore, when the circuit breaker has been closed, live detection is not required. In addition, the closing of the circuit breaker needs to be carried out according to the closing signal sent by the upper computer. Therefore, when no closing signal is received, closing is not required either, and thus live detection is not required. When live detection is not required, a control signal indicating that the switching unit is off is output to the control signal isolation conversion unit to keep the switching unit off and avoid power consumption.

[0080] When the circuit breaker is not closed and a closing signal is received, a control signal indicating that the switching unit is on is output to the control signal isolation conversion unit, so that the detection circuit performs live detection on the voltage connected when the switching unit is on and feeds back to the control unit through the detection signal isolation conversion unit.

[0081] Among them, when the closing signal is received, it means that closing is required. At this time, the circuit breaker is also in the state of not being closed. Therefore, live detection needs to be carried out to ensure the reliability and safety of subsequent closing.

[0082] If the detection signal isolation conversion unit outputs a detection signal indicating no live electricity, control the circuit breaker to close.

[0083] Among them, receiving a detection signal indicating no live electricity means that closing is reliable and safe at this time. Therefore, the circuit breaker can be controlled to close.

[0084] If the detection signal isolation and conversion unit outputs a detection signal indicating live electricity, the circuit breaker is controlled not to close.

[0085] Among them, when a detection signal indicating live electricity is received, it indicates that closing the circuit breaker is unreliable and unsafe at this time. Therefore, the circuit breaker needs to be controlled to remain open, that is, not to close, until a detection signal indicating no live electricity is received.

[0086] In one embodiment, as Figure 2 shown, when live detection is required, the control unit outputs a control signal MCU_ctrl in a high-impedance state or a high level. When the live wire output terminals (A1, B1, and C1) of the circuit breaker are live, the control unit can receive a low-level detection signal MCU_GF; conversely, when the live wire output terminals (A1, B1, and C1) of the circuit breaker are not live, the control unit can receive a high-level detection signal MCU_GF.

[0087] Among them, it should be noted that when live detection is not required, the control unit outputs a control signal MCU_ctrl of GND. At this time, regardless of whether the live wire output terminals (A1, B1, and C1) of the circuit breaker are live or not, the control unit will receive a high-level detection signal MCU_GF. At this time, the control unit can make a comprehensive judgment based on the output control signal MCU_ctrl and will not determine that the live wire output terminals (A1, B1, and C1) of the circuit breaker are not live based on the high-level detection signal MCU_GF at this time, thus avoiding misjudgment.

[0088] Based on Figure 2 the circuit structure in:

[0089] As Figure 5 shown, when the input voltage is single-phase 20 Vac, its change period is 700 ms. The control unit can receive a low-level detection signal MCU_GF indicating live electricity for 5 ms within one cycle. At this time, the power consumption of the detection circuit is 0.96 mVA.

[0090] As Figure 6 shown, when the input voltage is single-phase 310 Vac, its change period is 40 ms. The control unit can receive a low-level detection signal MCU_GF indicating live electricity for 8 ms within one cycle. At this time, the power consumption of the detection circuit is 4.7 mVA.

[0091] As Figure 7 shown, when the input voltage is three-phase 310 Vac, the control unit can continuously receive a low-level detection signal MCU_GF indicating live electricity. At this time, the power consumption of the detection circuit is 6.1 mVA.

[0092] In summary, the detection circuit basically consumes power only when the voltage-regulator diode D6 breaks down and conducts, thereby being able to further reduce power consumption.

[0093] It should be noted that in Figure 5 、 Figure 6 and Figure 7 , when the voltage signal V_CE1 on the capacitor CE1 is close to the maximum value, the voltage-regulator diode D6 breaks down and conducts. After the voltage signal V_CE1 reaches the maximum value and then drops a little, the voltage-regulator diode D6 resumes cutoff. After the voltage-regulator diode D6 breaks down and conducts, the voltage signal V_CE1 still rises a little further. This is because the applied voltage is still rising, and the combination of the rising applied voltage and the discharge on the discharge resistor R18 causes the voltage signal V_CE1 to rise only a little. Without the discharge resistor R18 and the voltage-regulator diode D6, the voltage signal V_CE1 would continue to rise until it reaches the peak voltage of the applied voltage, resulting in the capacitor CE1 being burned out. That is to say, the capacitor CE1 in this embodiment does not require too high a breakdown voltage. In addition, without the discharge resistor R18, the parasitic capacitance between the base and emitter of the NPN transistor Q2 would cause it to fail to turn off normally, resulting in the incorrect transmission of the detection signal MCU_GF.

[0094] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For the parts not described in detail in a certain embodiment, reference can be made to the detailed descriptions of other embodiments above, and they will not be elaborated here.

[0095] The above has introduced in detail an isolated live detection circuit, a control system and method of a circuit breaker provided by the present utility model. Specific examples are used herein to elaborate on the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those skilled in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

[0096] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

Claims

1. An isolated live detection circuit, characterized in that, The isolated live detection circuit includes: a control signal isolation and conversion unit, a switch unit, a detection signal isolation and conversion unit, and a detection circuit; The input end of the control signal isolation and conversion unit is used to access the control signal output by the control unit. The output end of the control signal isolation and conversion unit is electrically connected to the driving end of the switch unit. The input end of the switch unit is used to be respectively electrically connected to the output end of the circuit breaker and the output end of the inverter. The output end of the switch unit is electrically connected to the input end of the detection circuit. The output end of the detection circuit is electrically connected to the input end of the detection signal isolation and conversion unit. The output end of the detection signal isolation and conversion unit is used to output a detection signal to the control unit.

2. The isolated live detection circuit according to claim 1, wherein, The control signal isolation and conversion unit and the switch unit form a first optocoupler; The anode of the light-emitting diode in the first optocoupler is used to access the control signal output by the control unit. The cathode of the light-emitting diode in the first optocoupler is grounded. The collector of the photosensitive triode in the first optocoupler is used to be electrically connected to the live wire output end of the circuit breaker. The emitter of the photosensitive triode in the first optocoupler is electrically connected to the input end of the detection circuit.

3. The isolated live detection circuit according to claim 2, characterized in that, The isolated live detection circuit further includes a first pull-up resistor; The anode of the light-emitting diode in the first optocoupler is used to access the control signal output by the control unit through the first pull-up resistor.

4. The isolated live detection circuit according to claim 2, characterized in that, The detection signal isolation and conversion unit includes a second optocoupler; The anode of the light-emitting diode in the second optocoupler is electrically connected to the output end of the detection circuit. The cathode of the light-emitting diode in the second optocoupler is used to be electrically connected to the neutral wire output end of the circuit breaker. The collector of the photosensitive triode in the second optocoupler is used to output a detection signal to the control unit. The emitter of the photosensitive triode in the second optocoupler is grounded.

5. The isolated live detection circuit according to claim 4, wherein The isolated live detection circuit further includes a second pull-up resistor; The collector of the photosensitive triode in the second optocoupler is used to output a detection signal to the control unit through the second pull-up resistor.

6. The isolated live detection circuit according to claim 4, wherein The detection circuit includes a capacitor, a zener diode, a voltage drop resistor, a discharge resistor, an NPN-type triode, and a PNP-type triode; The first end of the capacitor is electrically connected to the emitter of the photosensitive triode in the first optocoupler, the emitter of the PNP-type triode, and the first end of the voltage drop resistor respectively. The base of the PNP-type triode is electrically connected to the second end of the voltage drop resistor, the cathode of the zener diode, and the collector of the NPN-type triode respectively. The collector of the PNP-type triode is electrically connected to the base of the NPN-type triode and the first end of the discharge resistor respectively. The second end of the discharge resistor is electrically connected to the emitter of the NPN-type triode and the anode of the light-emitting diode in the second optocoupler respectively. The second end of the capacitor and the anode of the zener diode are electrically connected to the cathode of the light-emitting diode in the second optocoupler respectively.

7. The isolated live detection circuit according to any one of claims 1 to 6, characterized in that, The isolated live detection circuit further includes a rectification unit; The input end of the rectification unit is used to be respectively electrically connected to the output end of the circuit breaker and the output end of the inverter. The output end of the rectification unit is electrically connected to the input end of the switch unit.

8. The isolated live detection circuit according to claim 7, wherein The rectifying unit includes rectifying diodes; The anodes of the rectifying diodes are respectively used for electrically connecting to the output end of the circuit breaker and the output end of the inverter, and the cathodes of the rectifying diodes are electrically connected to the input end of the switching unit.

9. The isolated live detection circuit according to any one of claims 1 to 6, characterized in that, The isolated live detection circuit further includes a current limiting unit; The input end of the current limiting unit is respectively used for electrically connecting to the output end of the circuit breaker and the output end of the inverter, and the output end of the current limiting unit is electrically connected to the input end of the switching unit.

10. A control system for a circuit breaker, characterized in that, It includes a circuit breaker, a control unit, and the isolated live detection circuit according to any one of claims 1 to 9; The input end of the circuit breaker is used for electrically connecting to the mains power grid, the output end of the circuit breaker is respectively used for electrically connecting to an electrical load and the output end of the inverter, and the drive end of the circuit breaker is used for accessing the drive signal output by the control unit.

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