Patent ID: 12237660

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below with reference to the drawings. These drawings and descriptions explain embodiments of the invention but do not limit the invention. The described embodiments are not all possible embodiments of the present invention. Other embodiments are possible without departing from the spirit and scope of the invention, and the structure and/or logic of the illustrated embodiments may be modified. Thus, it is intended that the scope of the invention is defined by the appended claims.

Before describing the embodiments, some terms used in this disclosure are defined here to help the reader better understand this disclosure.

In this disclosure, terms such as “connect”, “couple”, “link” etc. should be understood broadly, without limitation to physical connection or mechanical connection, but can include electrical connection, and can include direct or indirection connections. Terms such as “a” and “one” do not limit the quantity, and refers to “at least one”.

In the descriptions below, terms such as “including” are intended to be open-ended and mean “including without limitation”, and can include other contents. “Based on” means “at least partly based on.” “An embodiment” means “at least one embodiment.” “Another embodiment” means “at least another embodiment,” etc.

A main technical problem solved by leakage current detection and interruption devices according to embodiments of the present invention is: How to interrupt power connection when certain electrical components (e.g., solenoid, semiconductor switch) in the device is faulty, without the user's manual intervention, thereby enhancing safety of the device.

To solve the above problem, embodiments of the present invention provide a leakage current detection and interruption device which includes: a switch module configured to control electrical connection between input and output ends of power supply lines; a leakage current detection module configured to generate a leakage fault signal in response to a leakage current in the power supply lines; a leakage-responsive drive module configured to drive the switch module to disconnect the electrical connection in response to the leakage fault signal; a fault-responsive drive module configured to drive the switch module to disconnect the electrical connection in response to a fault in the leakage-responsive drive module; and a self-test module configured to generate a self-test signal and to generate a self-test fault signal in response to a fault in the leakage current detection module and/or the leakage-responsive drive module.

First Embodiment

FIG.1is a circuit diagram of a leakage current detection and interruption device according to a first embodiment of the present invention. As shown inFIG.1, the leakage current detection and interruption device includes a switch module1, a leakage current detection module2, a leakage-responsive drive module4, a fault-responsive drive module5, a self-test module3, and a first contact switch SW1.

The power supply lines include hot and white lines. The switch module1includes a reset switch RESET coupled between the input end LINE and output end LOAD of the power supply lines, configured to control the electrical connection between the input end and the output end.

The leakage current detection module2includes: a neutral detection coil CT2, a leakage current detection coil CT1, a leakage current detection unit (processor chip) U1, a rectifier (diode bridge) DB, and various related resistors and capacitors. The first and second power supply lines (HOT and WHITE) pass through the leakage current detection coil CT1, and the coil CT1detects any leakage current on the two power supply lines and outputs a signal to the leakage current detection unit U1. The leakage current detection unit U1generates a leakage fault signal in response thereto. The diode bridge DB is coupled to the first power line HOT, second power line WHITE, the leakage current detection unit U1, and ground.

The leakage-responsive drive module4includes: first solenoid SOL1, second semiconductor switch Q2(e.g., a silicon-controlled rectifier, SCR), first semiconductor switch Q1(e.g., an SCR), and resistor R4. The first solenoid SOL1is coupled to the input end LINE (e.g., to the first power supply line HOT), the second semiconductor switch Q2and the fault-responsive drive module5. The first solenoid SOL1is configured to generate an electromagnetic force that drives the reset switch RESET and the first contact switch SW1. In this embodiment, the input end of the second semiconductor switch Q2is coupled to the first solenoid SOL1, its control electrode is coupled to the self-test module3, and its output end is coupled to the input end of the first semiconductor switch Q1. The control electrode of the first semiconductor switch Q1is coupled to the first contact switch SW1and to an output of the leakage current detection unit U1. Resistor R4is coupled between the first solenoid SOL1and the control electrode of the second semiconductor switch Q2.

The fault-responsive drive module5includes: a second solenoid SOL2, a third semiconductor switch Q3(e.g., an SCR), a fourth semiconductor switch Q5(e.g., a transistor), a capacitor C8, and resistors R5, R8and R10. The second solenoid SOL2is coupled to the input end LINE of the power supply lines (e.g., to the first power supply line HOT), the third semiconductor switch Q3, and the leakage-responsive drive module4. The second solenoid SOL2is configured to generate an electromagnetic force that drives the reset switch RESET and the first contact switch SW1. In this embodiment, the input end of the third semiconductor switch Q3is coupled to the second solenoid SOL2, its control electrode is coupled to the collector of the fourth semiconductor switch Q5, and its output end is coupled to the emitter of the fourth semiconductor switch Q5. The base of the fourth semiconductor switch Q5is coupled between resistors R5and R8. Capacitor C8is coupled between the emitter and collector of the fourth semiconductor switch Q5. Resistor R5is coupled between the input end of the second semiconductor switch Q2and the base of the fourth semiconductor switch Q5. Resistor R8is coupled between the base of the fourth semiconductor switch Q5and the output end of the first semiconductor switch Q1. Resistor R10is coupled between the second solenoid SOL2and the control electrode of the third semiconductor switch Q3.

The self-test module3includes: a fifth semiconductor switch Q4(e.g., a transistor), a Zener diode or TVS (Transient Voltage Suppressor) diode ZD1, first diode D1, second diode D2, resistors R14, R9and R7, and capacitor C9. The input end of the first diode D1is coupled to input end LINE of the power supply lines (e.g., first power supply line HOT), and its output end is coupled via resistor R7to both one end of the Zener diode ZD1and the input end of the second diode D2. The output end of the second diode D2is coupled between the first semiconductor switch Q1and the second semiconductor switch Q2. The other end of the Zener diode ZD1is coupled to resistor R14, and also coupled via resistor R9to pass through the leakage current detection coil CT1and then to ground. The base of the fifth semiconductor switch Q4is coupled via resistor R14to the other end of the Zener diode ZD1; its emitter is coupled to the output end of the third semiconductor switch Q3; and its collector is coupled to the control electrode of the second semiconductor switch Q2. Capacitor C9is coupled between one end of the Zener diode ZD1and the emitter of the fifth semiconductor switch Q4.

The working principles of the leakage current detection and interruption device of this embodiment are as follows.

When the leakage current detection and interruption device is functioning normally, a current flows through the path HOT-SOL1-R4to trigger the second semiconductor switch Q2to be conductive. In this state, when the reset switch RESET is depressed by the user, the first contact switch SW1(which is mechanically linked to the reset switch RESET) is closed, which triggers the first semiconductor switch Q1to be conductive. As a result, a current flows through the path HOT-SOL1-Q2-Q1-DB to WHITE, causing the first solenoid SOL1to be energized to generate an electromagnetic force to unlock the reset switch RESET, so that the reset switch RESET is maintained at a closed state. In this state, the input end LINE of the power supply lines is electrically connected to the output end LOAD (which may include an electrical socket SOCKET and/or a directly connected electrical load).

When no leakage current is present on the power supply lines, the leakage current detection unit U1will not generate a leakage fault signal, so the first semiconductor switch Q1is non-conductive. Thus, a current flows through the path Q2-R5to trigger the fourth semiconductor switch Q5to be conductive. As a result, the control electrode of the third semiconductor switch Q3is at a low voltage, i.e., the third semiconductor switch Q3is non-conductive. Because the first semiconductor switch Q1and third semiconductor switch Q3are non-conductive, the first solenoid SOL1and second solenoid SOL2do not have a sufficiently high current through them, so that the reset switch RESET remains closed (i.e. not tripped).

During the self-testing of the device, a current flows through the path HOT-D1-R7to charge capacitor C9. When the voltage across capacitor C9reaches the trigger voltage of the Zener diode ZD1, the Zener diode ZD1becomes conductive, causing a current to flow through R9-CT1to ground to generate a self-test signal (a simulated leakage current). The self-test signal is collected by the leakage current detection coil CT1and processed by the leakage current detection unit U1to generate a leakage current fault signal, which triggers the first semiconductor switch Q1to become conductive. While the Zener diode ZD1is conductive, the fifth semiconductor switch Q4is triggered via resistor R14to be conductive, so that the control electrode of the second semiconductor switch Q2is at a low voltage. In other words, while the first semiconductor switch Q1is conductive, the second semiconductor switch Q2is non-conductive, so no current flows through the first solenoid SOL1. In this state, capacitor C9is discharged via D2-Q1, so the Zener diode ZD1stops, causing the second semiconductor switch Q2to become conductive again after the first semiconductor switch Q1becomes non-conductive.

When the second semiconductor switch Q2is non-conductive, no current flows through resistor R5, so the fourth semiconductor switch Q5is non-conductive. In this state, resistor R10charges capacitor C8. In this embodiment, the parameters of resistor R10and capacitor C8are adjusted so that the third semiconductor switch Q3only becomes conductive after a predetermined time period T1, but the second semiconductor switch Q2becomes conductive again within the predetermined time period T1. Thus, after the second semiconductor switch Q2becomes conductive again, the fourth semiconductor switch Q5is triggered via R5to be conductive again. As a result, capacitor C8is discharged, and the control electrode of the third semiconductor switch Q3is at a low voltage, so the third semiconductor switch Q3remains non-conductive. In other words, in the self-test process after the self-test module3generates the self-test signal, there is never a sufficiently large current that flows through the first solenoid SOL1and second solenoid SOL2, so the reset switch RESET remains closed.

On the other hand, after the self-test module3generates the self-test signal, if the leakage current detection coil CT1or the leakage current detection unit U1has a fault, then the leakage current detection module2cannot generate a leakage current fault signal, so the first semiconductor switch Q1remains non-conductive. Thus, when the first semiconductor switch Q1remains non-conductive, or when the first semiconductor switch Q1itself has an open-circuit fault, capacitor C9cannot be discharged, so the Zener diode ZD1remains triggered and conductive for a time period longer than the predetermined time period T1, causing the fifth semiconductor switch Q4becomes conductive. This in turn causes the second semiconductor switch Q2and the fourth semiconductor switch Q5to be non-conductive. Thus, resistor R10continuously charges capacitor C8, and after the predetermined time period T1, the voltage across capacitor C8triggers the third semiconductor switch Q3to become conductive. As a result, a current flows through the path HOT-SOL2-Q3-DB to WHITE, which energizes the second solenoid SOL2to drive the reset switch RESET to trip and to disconnect the power supply from the input end LINE to the output end LOAD.

Further, when the first solenoid SOL1or second semiconductor switch Q2has an open-circuit fault, no current flows through resistor R5, so the fourth semiconductor switch Q5remains non-conductive. Thus, a current through resistor R10continuously charges capacitor C8, and after the predetermined time period T1, the voltage across capacitor C8triggers the third semiconductor switch Q3to become conductive. As a result, a current flows through second solenoid SOL2, which energizes the second solenoid SOL2to drive the reset switch RESET to trip and to disconnect the power supply from the input end LINE to the output end LOAD.

In other words, when the leakage current detection module2or leakage-responsive drive module4has a fault, the leakage current detection module2generates a self-test fault signal (voltage at the input end of fifth semiconductor switch Q4) to cause the second semiconductor switch Q2to be non-conductive. When this condition continues for a time period longer than the predetermined time period T1, the third semiconductor switch Q3is triggered to conduct, so the fault-responsive drive module5drives the reset switch RESET to trip, thereby disconnecting the power supply from the input end LINE to the output end LOAD.

The leakage current detection and interruption device according to the first embodiment can effectively detect leakage current and perform self-test, and can also effectively disconnect power to the output end when a fault condition is present in the leakage current detection module2(e.g., the leakage current detection coil CT1and/or leakage current detection unit U1therein) or the leakage-responsive drive module4(e.g., the first solenoid SOL1, first semiconductor switch Q1, and/or second semiconductor switch Q2therein). This enhances the functions of the device and ensures safety of the user.

Second Embodiment

FIG.2is a circuit diagram of a leakage current detection and interruption device according to a second embodiment of the present invention. Compared to the first embodiment ofFIG.1, a main difference is that the third semiconductor switch Q3(e.g., an SCR) inFIG.2has its input end coupled to the input end LINE of the power supply lines, and its output end coupled to the second solenoid SOL2. Further, in the embodiment ofFIG.2, the second semiconductor switch Q2is a transistor. The working principles of the second embodiment are similar to those of the first embodiment and detailed descriptions are omitted here.

Third Embodiment

FIG.3is a circuit diagram of a leakage current detection and interruption device according to a third embodiment of the present invention. Compared to the first embodiment ofFIG.1, a main difference is that the in the embodiment ofFIG.3, the output end has only a socket output (SOCKET), without a directly connected electrical load. When resetting such a device, there is no need to provide a first contact switch SW1and to close it in order to drive the first solenoid SOL1to unlock the reset switch RESET (i.e., resetting is directly accomplished by the manual action only). Further, in the third embodiment, a second switch SW is coupled between the input end LINE of the power supply lines and the leakage-responsive drive module4, where the second switch SW is controlled by the first solenoid SOL1and the second solenoid SOL2. When the leakage current detection module2detects a leakage current, the solenoid SOL1and/or SOL2drives the second switch SW to open, which can prevent the solenoids from burn out. The working principles of the third embodiment are similar to those of the first embodiment and detailed descriptions are omitted here.

Fourth Embodiment

FIG.4is a circuit diagram of a leakage current detection and interruption device according to a fourth embodiment of the present invention. This device is suitable as an appliance leakage-current interrupter (ALCI). Compared to the first embodiment ofFIG.1, the device in the fourth embodiment does not have neutral line protection, and uses a half-bridge rectifier (diode D4and resistor R11) instead of a full-bridge rectifier. Further, like in the third embodiment, the first contact switch SW1is not needed, and direct manual reset is possible. During the AC half-cycle when the leakage current detection unit U1is not operating, a current flowing through the path ZD1-D4-R11to supply power to the leakage current detection unit U1, enabling it to function normally to process the leakage current signal. The working principles of the fourth embodiment are similar to those of the first embodiment and detailed descriptions are omitted here.

Fifth Embodiment

FIG.5is a circuit diagram of a leakage current detection and interruption device according to a fifth embodiment of the present invention. Compared to the first embodiment ofFIG.1, a main difference is that the in the fifth embodiment ofFIG.5, the second semiconductor switch Q2(e.g., an SCR) has its input end coupled to the input end LINE of the power supply lines, and its output end coupled to the first solenoid SOL1. Further, in the fifth embodiment, the fourth semiconductor switch Q5and the fifth semiconductor switch Q4are SCRs. The current path for the simulated current (self-test signal) is ZD1-R9-CT1-Q4-ground. The working principles of the fifth embodiment are similar to those of the first embodiment and detailed descriptions are omitted here.

Sixth Embodiment

FIG.6is a circuit diagram of a leakage current detection and interruption device according to a sixth embodiment of the present invention. As shown inFIG.6, the leakage current detection and interruption device includes a switch module1, a leakage current detection module2, a leakage-responsive drive module4, a fault-responsive drive module5, and a self-test module3.

The power supply lines include hot and white lines. The switch module1includes a reset switch coupled between the input end LINE and output end LOAD of the power supply lines, configured to control the electrical connection between the input end and the output end.

The leakage current detection module2includes: a neutral detection coil CT2, a leakage current detection coil CT1, a leakage current detection unit (processor chip) U1, a diode bridge (rectifier) DB, resistor R1, capacitor C7, and various other related resistors and capacitors. The leakage current detection coil CT1detects any leakage current on the two power supply lines HOT and WHITE and outputs a signal to the leakage current detection unit U1. The leakage current detection unit U1generates a leakage fault signal in response thereto. The diode bridge DB is coupled to the leakage-responsive drive module4, second power line WHITE, ground, and the first power line HOT via resistor R1and capacitor C7.

The leakage-responsive drive module4includes: first solenoid SOL1, second semiconductor switch Q2(e.g., an SCR), first semiconductor switch Q1(e.g., an SCR), fourth semiconductor switch Q6(e.g., an SCR), capacitor C6and first resistor R18. The first solenoid SOL1is coupled to the diode bridge DB and the leakage current detection unit U1, and is configured to generate an electromagnetic force that drives the switch in the switch module1. In this embodiment, the input end of the second semiconductor switch Q2is coupled via resistor R18to the first solenoid SOL1and the diode bridge DB, its control electrode is coupled to the self-test module3, and its output end is coupled to the input end of the first semiconductor switch Q1. The control electrode of the first semiconductor switch Q1is coupled to an output of the leakage current detection unit U1, and its output end is coupled via the fault-responsive drive module5to the input end of the fourth semiconductor switch Q6. The output end of the fourth semiconductor switch Q6is coupled to the first solenoid SOL1and the diode bridge DB, and its control electrode is coupled to the leakage current detection unit U1via resistor R16. Capacitor C6is coupled between the output end of the fourth semiconductor switch Q6and resistor R18.

The fault-responsive drive module5includes: a third semiconductor switch Q3(e.g., an SCR), a fifth semiconductor switch Q5(e.g., a transistor), a capacitor C8, and resistors R5, R8and R10. The base of the fifth semiconductor switch Q5is coupled via resistor R5to a point between the first semiconductor switch Q1and the second semiconductor switch Q2; its emitter is coupled to the input end of the fourth semiconductor switch Q6; and its collector is coupled to the control electrode of the third semiconductor switch Q3. The input end of the third semiconductor switch Q3is coupled to the input end of the second semiconductor switch Q2, and its output end is coupled to the input end of the fourth semiconductor switch Q6. Capacitor C8is coupled the control electrode of the third semiconductor switch Q3and the input end of the fourth semiconductor switch Q6. Resistor R10is coupled between the control electrode of the third semiconductor switch Q3and the input end the second semiconductor switch Q2.

The self-test module3is similar to the self-test module3of the first embodiment ofFIG.1and its detailed descriptions are omitted here.

The working principles of the leakage current detection and interruption device of this embodiment are as follows.

When the leakage current detection and interruption device is functioning normally, a current flows through the path HOT-R1-C7-DB to charge capacitor C6. The voltage across capacitor C6is divided by the first solenoid SOL1, R16and R15. When the voltage across resistor R15reaches the trigger voltage of the fourth semiconductor switch Q6, the fourth semiconductor switch Q6becomes conductive, so that a current flows through the path HOT-R1-C7-DB-SOL1-D3-U1-Q6-DB-WHITE. This current energizes the first solenoid SOL1, which generate an electromagnetic force to drive the switch module1to connect the power from the input end LINE to the output end LOAD.

When no leakage current is present on the power supply lines, the leakage current detection unit U1will not generate a leakage fault signal, so the first semiconductor switch Q1is non-conductive. Thus, a current flows through the path Q2-R5to trigger the fourth semiconductor switch Q5to be conductive. As a result, the control electrode of the third semiconductor switch Q3is at a low voltage, i.e., the third semiconductor switch Q3is non-conductive. Because the first semiconductor switch Q1and third semiconductor switch Q3are non-conductive, the first solenoid SOL1has a sufficiently high current through it to maintain the switch module1in the closed state (i.e. not tripped).

During the self-testing of the device, a current flows through the path HOT-D1-R7to charge capacitor C9. When the voltage across capacitor C9reaches the trigger voltage of the Zener diode ZD1, the Zener diode ZD1becomes conductive, causing a current to flow through R9-CT1-WHITE to generate a self-test signal (a simulated leakage current). The self-test signal is collected by the leakage current detection coil CT1and processed by the leakage current detection unit U1to generate a leakage current fault signal, which triggers the first semiconductor switch Q1to become conductive. While the Zener diode ZD1is conductive, the semiconductor switch Q4of the self-test module3is triggered via resistor R14to be conductive, so that the control electrode of the second semiconductor switch Q2is at a low voltage. In other words, while the first semiconductor switch Q1is conductive, the second semiconductor switch Q2is non-conductive, so a current continues to flow through the first solenoid SOL1. In this state, capacitor C9is discharged via D2-Q1, so the Zener diode ZD1is off, causing the second semiconductor switch Q2to become conductive again.

When the second semiconductor switch Q2is non-conductive, no current flows through resistor R5, so the fifth semiconductor switch Q5is non-conductive. In this state, resistor R10charges capacitor C8. In this embodiment, the parameters of resistor R10and capacitor C8are adjusted so that the third semiconductor switch Q3only becomes conductive after a predetermined time period T1, but the second semiconductor switch Q2becomes conductive within the predetermined time period T1. Thus, after the second semiconductor switch Q2becomes conductive again, the fourth semiconductor switch Q5is triggered via R5to be conductive again. As a result, capacitor C8is discharged, and the control electrode of the third semiconductor switch Q3is maintained at a low voltage, so the third semiconductor switch Q3remains non-conductive.

On the other hand, after the self-test module3generates the self-test signal, if the leakage current detection coil CT1or the leakage current detection unit U1has a fault, the leakage current detection module2cannot generate a leakage current fault signal, then the first semiconductor switch Q1remains non-conductive. When the first semiconductor switch Q1is non-conductive, or the first semiconductor switch Q1itself has an open-circuit fault, capacitor C9cannot be discharged, so the Zener diode ZD1remains triggered and conductive for a time period longer than the predetermined time period T1. Therefore, the semiconductor switch Q4becomes conductive, which causes the second semiconductor switch Q2and the fifth semiconductor switch Q5to be non-conductive. In this state, resistor R10continuously charges capacitor C8, and after the predetermined time period T1, the voltage across capacitor C8triggers the third semiconductor switch Q3to become conductive. As a result, a current flows through the path R18-Q3-Q6-DB to WHITE, so that the current flowing through first solenoid SOL1drops to a low level (e.g., below a threshold current level) that is not sufficient to keep the switch module1in the closed state. Therefore, the switch module1trips and disconnects the power supply from the input end LINE to the output end LOAD.

Further, when the second semiconductor switch Q2has an open-circuit fault, no current flows through resistor R5, so the fifth semiconductor switch Q5remains non-conductive. Thus, resistor R10continuously charges capacitor C8, and after the predetermined time period T1, the voltage across capacitor C8triggers the third semiconductor switch Q3to become conductive. As a result, the current flowing through first solenoid SOL1drops to a low level (e.g., below the threshold current level) that is not sufficient to keep the switch module1in the closed state, causing the switch module1to trip and disconnect the power supply from the input end LINE to the output end LOAD.

In the above-described embodiments, the various semiconductor switches may be transistors, MOSFETs (metal-oxide-semiconductor field-effect transistors), SCRs, photocouplers, or any other suitable switch devices (e.g., relays).

In the embodiments ofFIGS.1-5, the coils of the first and second solenoids may be wound around separate magnetic cores as shown in the drawings, or around a common magnetic core (not shown in the drawings).

The leakage current detection and interruption device according to the above embodiments of the present invention can not only achieve leakage current detection and interruption with a self-test function, but also trip and disconnect power when certain of its internal components (e.g., the solenoid that controls the switch module, semiconductor switches, etc.) are faulty. This ensures that the device disconnects power immediately upon occurrence of a fault condition in its internal components. This eliminates hidden safety threats and improves safety of the device.

Additional embodiments of the present invention provide an electrical power connection device, which includes a body and a leakage current detection and interruption device according to any one of the above embodiments disposed inside the body.

Other additional embodiments of the present invention provide an electrical appliance, which includes an electrical load, and an electrical power connection device coupled between a power supply and the load to supply power to the load, where the electrical power connection device employs a leakage current detection and interruption device according to any one of the above embodiments.

While the present invention is described above using specific examples, these examples are only illustrative and do not limit the scope of the invention. It will be apparent to those skilled in the art that various modifications, additions and deletions can be made to the leakage current detection and interruption device of the present invention without departing from the spirit or scope of the invention.