CN108462150B - Leakage protection circuit and method - Google Patents
Leakage protection circuit and method Download PDFInfo
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- CN108462150B CN108462150B CN201810143966.9A CN201810143966A CN108462150B CN 108462150 B CN108462150 B CN 108462150B CN 201810143966 A CN201810143966 A CN 201810143966A CN 108462150 B CN108462150 B CN 108462150B
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- 238000001514 detection method Methods 0.000 claims abstract description 143
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- 239000003990 capacitor Substances 0.000 claims description 12
- 238000010586 diagram Methods 0.000 description 12
- 238000005070 sampling Methods 0.000 description 3
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- 102100035007 Synaptotagmin-like protein 2 Human genes 0.000 description 2
- 238000011900 installation process Methods 0.000 description 2
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- 239000003637 basic solution Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/44—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to the rate of change of electrical quantities
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
- H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/025—Current limitation using field effect transistors
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
- Keying Circuit Devices (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention discloses a leakage protection circuit and a leakage protection method, wherein the leakage protection circuit comprises a current detection circuit, a first switching circuit and a second switching circuit, wherein the current detection circuit is used for judging whether the input end has leakage or not according to the current flowing through the first switching circuit; the contact failure detection circuit judges whether the input end is in poor contact or not according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch; the control circuit controls the first switch to be turned on and off, and the current detection circuit detects the current flowing through the first switch during the on period of the first switch, and the current detection signal is lower than a first threshold value to turn off the first switch; the current detection signal reaches a first threshold value, the first switch is continuously turned on, the contact failure detection circuit judges whether the input end is in poor contact or not, and if the contact failure occurs, the first switch is turned off. The invention protects the switch tube when the input end is in poor contact or the voltage suddenly increases.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a leakage protection circuit and a leakage protection method.
Background
In the load installation process, partial connection can occur in the installation process, and if a human body is carelessly contacted at the moment, the electric shock is easy to occur, so that the safety operation is influenced. For example, in the field of lighting, since more lamp holders also retain a double-ended interface, a double-ended input lamp is generally used when an original lamp is replaced. The double-end input refers to that connectors of an alternating current input end are respectively arranged at two ends of a lamp tube, in this case, an operator generally inserts one end of the alternating current input end into a lamp holder first and then inserts the other end of the alternating current input end into the lamp holder, and because the operator needs to grip the end of the lamp tube by hands, the operator possibly contacts with metal with conductive end parts, and electric shock is easy to occur, so that the electric leakage protection under the condition is important.
In the prior art, a switching tube is connected in a power supply and a power stage circuit, the switching tube is led to when the whole circuit is started to work, the current passing through the switching tube is detected, whether the electric leakage phenomenon occurs is judged by utilizing the magnitude of the current, when the current is smaller than a set threshold value, the switching tube is turned off when the electric leakage phenomenon occurs at an input end is judged, the whole circuit is cut off, so that the electric leakage protection is carried out, and if the current is larger than the threshold value, the conduction state of the switching tube is maintained. However, in the prior art, if the power input end is in poor contact after the whole circuit works normally, the current passing through the switching tube is large, so that the switching tube is easy to damage.
Disclosure of Invention
In view of this, the present invention provides a leakage protection circuit and a method for protecting a switching tube with less damage under the condition of poor contact of a power input end, which are used for solving the technical problem in the prior art that the switching tube is easily damaged due to the fact that the current flowing through the switching tube is large under the condition of poor contact of the input end.
The invention provides a leakage protection circuit, comprising:
The current detection circuit is used for detecting current flowing through a first switch connected to the main loop to obtain a current detection signal representing the current flowing through the first switch, and judging that the input end has a leakage phenomenon if the current detection signal is lower than a first threshold value;
The contact failure detection circuit judges whether the input end has a contact failure phenomenon according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch;
The control circuit is used for controlling the on and off of the first switch, the current detection circuit is used for detecting the current flowing through the first switch during the on period of the first switch, and if the current detection signal is lower than a first threshold value, the control circuit is used for controlling the first switch to be turned off; if the current detection signal reaches a first threshold value, the first switch is continuously turned on, the contact failure detection circuit judges whether the input end is in poor contact or not, and when the contact failure detection circuit judges that the input end is in poor contact, the control circuit controls the first switch to be turned off.
Optionally, the leakage protection circuit further includes a voltage detection circuit, the voltage detection circuit detects the voltage of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch, so as to obtain a voltage detection signal, the voltage detection signal reaches a second threshold value, the control circuit controls the first switch to be turned on, and the current detection circuit detects the current flowing through the first switch.
Optionally, after the first switch is turned off, the current detection circuit performs leakage detection again.
Optionally, the contact failure detection circuit detects a current flowing through the first switch, and when the current flowing through the first switch reaches a third threshold value, the contact failure detection circuit determines that the input end has a contact failure.
Optionally, the poor contact detection circuit includes a first comparator, a first input end of the first comparator receives a current detection signal representing a current flowing through the first switch, a second input end of the first comparator receives the third threshold value, when the current detection signal reaches the third threshold value, the first comparator turns over, and an output end of the first comparator is connected with the control circuit.
Optionally, the contact failure detection circuit detects the voltage of the input end, and when the change rate of the voltage of the input end is greater than a fourth threshold value, the contact failure detection circuit judges that the contact failure occurs at the input end.
Optionally, the poor contact detection circuit includes a first resistor, a first capacitor and a second comparator, one end of the first capacitor receives a voltage detection signal representing an input voltage, the other end of the first capacitor is connected with one end of the first resistor, the other end of the first resistor is grounded, a first input end of the second comparator is connected with a common end of the first resistor and the first capacitor, a second input end of the second comparator receives a third threshold value, and an output end of the second comparator is connected with the control circuit.
Optionally, the contact failure detection circuit detects a voltage of the first end of the first switch or a voltage difference between the first end and the second end of the first switch, and when the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch reaches a fifth threshold, the contact failure detection circuit determines that the input end has a contact failure.
Optionally, the contact failure detection circuit detects a voltage of the first end of the first switch or a voltage difference between the first end and the second end of the first switch, and when a voltage change rate of the first end of the first switch or a voltage difference change rate of the first end and the second end of the first switch reaches a sixth threshold, the contact failure detection circuit determines that the input end has a contact failure.
Optionally, the first switch is a MOS transistor, a first end of the first switch is a drain, a second end of the first switch is a source, and a control end of the first switch is a gate.
Optionally, the control circuit includes a pulse generating circuit and a logic circuit, an input end of the pulse generating circuit is connected with the logic circuit and the poor contact detecting circuit, and an output end of the pulse generating circuit is connected with a control end of the first switch.
The invention also provides a leakage protection method, which comprises the following steps:
detecting the current flowing through a first switch connected to a main loop to obtain a current detection signal representing the current flowing through the first switch, wherein the current detection signal is lower than a first threshold value, and judging that the input end has a leakage phenomenon;
judging whether the input end is in poor contact or not according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch;
Controlling the on and off of a first switch, wherein during the on period of the first switch, the current detection circuit detects the current flowing through the first switch, and if the current detection signal is lower than a first threshold value, the control circuit controls the first switch to be turned off; if the current detection signal reaches a first threshold value, the first switch is continuously turned on, the contact failure detection circuit judges whether the input end is in poor contact or not, and when the contact failure detection circuit judges that the input end is in poor contact, the control circuit controls the first switch to be turned off.
Compared with the prior art, the technical scheme of the invention has the following advantages: the invention solves the technical problem that the first switch is easy to damage caused by poor contact of the input end in the prior art, the current detection circuit judges that the input end generates the electric leakage phenomenon, the first switch is turned off, the current detection circuit judges that the input end does not generate the electric leakage phenomenon, the first switch is continuously turned on, the poor contact detection circuit detects the current flowing through the first switch or the change rate of the voltage of the input end, judges whether the input end generates the poor contact, and turns off the first switch and then carries out the electric leakage detection again if the input end generates the poor contact. According to the invention, the contact failure detection circuit is added on the basis of the prior art of the leakage protection circuit, so that the protection switch tube is less damaged under the conditions that the contact failure of the power input end and the voltage suddenly become large.
Drawings
FIG. 1 is a schematic diagram of a leakage protection circuit according to a first embodiment of the present invention;
FIG. 2 is a schematic diagram of a bad contact detection circuit according to a first embodiment of the present invention;
fig. 3 is a specific circuit of a contact failure detection circuit in the first embodiment of the present invention.
FIG. 4 is a schematic diagram of a second embodiment of the leakage protection circuit according to the present invention;
FIG. 5 is a schematic diagram of a bad contact detection circuit according to a second embodiment of the present invention;
FIG. 6 is a schematic diagram of a contact failure detection circuit according to a second embodiment of the present invention;
fig. 7 is a schematic structural diagram of a third embodiment of the leakage protection circuit of the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments only. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention.
In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate and clearly illustrate the embodiments of the present invention.
The basic solution of the present invention is that the leakage protection circuit comprises a current detection circuit, a bad contact detection circuit, a control circuit, wherein in this solution,
The current detection circuit detects the current flowing through the first switch M1 of the first switch connected to the main loop, obtains a current detection signal representing the current flowing through the first switch M1, and judges whether the input end has a leakage phenomenon according to the current detection signal.
The contact failure detection circuit judges whether the contact failure phenomenon occurs at the input end according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch;
The control circuit controls the on and off of the first switch M1, the current detection circuit detects the current flowing through the first switch M1 during the on period of the first switch M1, and if the current detection signal is lower than a first threshold value, the control circuit controls the first switch M1 to be turned off; if the current detection signal reaches the first threshold, the first switch M1 is continuously turned on, the contact failure detection circuit determines whether a contact failure occurs at the input end, and when the contact failure detection circuit determines that the contact failure occurs at the input end, the control circuit controls the first switch M1 to be turned off, so as to restart the electric leakage detection.
The main loop is a working circuit, and the first switch M1 can control the on and off of the main loop. The control end of the first switch M1 is connected with the control circuit, and the control circuit controls the on and off of the first switch M1.
In the present invention, in the current detection stage, the first switch M1 may be turned on directly by using a high level, and if it is determined that no leakage occurs, the first switch M1 may be turned on directly. The leakage detection can also be controlled by the pulse signal, and if the leakage phenomenon is judged not to occur, the first switch M1 is turned on at a high level, and the high level is triggered at a high level or a low level of the pulse signal. The continuous conduction can be continuous conduction or conduction after short pause after detection is completed.
The leakage protection circuit may further include a voltage detection circuit, where the voltage detection circuit may detect an input voltage, and then two input ends of the voltage detection circuit are respectively connected to two ends of the rectifier bridge, two ends of the ac input power source, or one output end of the rectifier bridge and one of the ac input power sources, where the power input end may be either the ac input end or the output end of the rectifier bridge, unless otherwise specified. The voltage detection circuit may also detect the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch, and then the two input ends of the voltage detection circuit are the first end of the first switch and the ground or the first end and the second end of the first switch respectively. The output end of the voltage detection circuit under two conditions is connected with the control circuit, when the voltage detection circuit detects that the voltage of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch is a second threshold value, the control circuit controls the first switch M1 to be conducted, and the current detection circuit detects the current flowing through the first switch M1. The voltage detection circuit has the advantages that a threshold value can be determined by the voltage detection circuit, namely, the detection can be carried out when the voltage detection circuit is used for detecting the second threshold value, namely, the input voltage is constant at the moment, the first switch M1 is conducted and current detection is carried out when the input voltage is constant, the obtained current detection signal actually represents the internal resistance of the circuit, and if the internal resistance is different due to the fact that whether the electric leakage exists or not (namely, whether the human body impedance is connected or not), the electric leakage condition can be represented through the current detection signal if the electric leakage condition is caused by the human body connection.
There are many ways to control the on and off of the first switch M1, and in this embodiment, a pulse generating circuit is used.
As shown in fig. 1, a block diagram of an embodiment of a leakage protection circuit to which the present invention is applied is shown, the control circuit includes a logic circuit and a pulse generation circuit, the voltage detection circuit and the current detection circuit are connected to the pulse generation circuit through the logic circuit, the contact failure detection circuit samples a current passing through the first switch M1, an output terminal is connected to the pulse generation circuit, and the pulse generation circuit is connected to a control terminal of the first switch M1.
The voltage detection circuit comprises a voltage division circuit and a comparator comp4, the voltage division circuit is formed by connecting resistors R2 and R3 in series, two input ends of the voltage division circuit are respectively connected with two ends of a rectifier bridge, two ends of an alternating current input power supply or one output end of the rectifier bridge and one end of the alternating current input power supply, and broken lines in the figure represent possible connection modes, namely the connection modes are illustrated and exemplified in the figure. The first input end of the comparator comp4 is connected with the output end of the voltage dividing circuit and is a common end of the resistors R2 and R3, the second input end of the comparator comp4 receives a signal Vref2 representing the second threshold value, when the voltage detection signal reaches Vref2, the comparator comp4 is turned over, the pulse generating circuit receives the output signal of the comparator comp4 and sends out a pulse, the first switch M1 is conducted, and the current detection circuit starts to detect.
In the first embodiment, only the case where the voltage detection circuit detects the voltage of the input terminal is given, but it is also within the protection scope of the present invention that the voltage detection circuit detects the voltage of the first terminal of the first switch or the voltage difference between the first terminal and the second terminal of the first switch. The following embodiment II and embodiment III are the same.
In addition, the voltage detection circuit detects the voltage of the input end and the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch tube respectively, and the second threshold values are different, so that the description is convenient only.
The current detection circuit comprises a sampling resistor R0 and a comparator comp3, the sampling resistor R0 is connected with the first switch M1 in series, during the conduction period of the first switch M1, the current flowing through the first switch M1 is sampled and is input into the first input end of the comparator comp3, the second input end of the comparator comp3 receives a signal Vref1 representing the first threshold value, when the current detection signal is lower than Vref1, the current detection signal represents the existence of the leakage phenomenon, the output end of the comparator comp3 is subjected to level inversion, and the first switch M1 is controlled to be disconnected through the logic circuit, so that the main loop is disconnected. If the current detection reaches Vref1, it indicates that no leakage exists, and the first switch M1 may be normally turned on.
When the main loop works normally, the poor contact detection circuit starts to work, the poor contact circuit receives the current flowing through the first switch M1, and the output end of the poor contact circuit is connected with the pulse generation circuit.
The driver in fig. 1 is used for driving the switching tube, and changes the control signal of the control circuit into a control signal suitable for controlling the switch to be turned on and off, and has no substantial effect on the circuit principle, so that the driver is omitted in the description, but the driver is generally required to realize the process of actually driving the switching tube. Those skilled in the art will recognize and be able to implement the invention in light of the description of the invention.
The detection principle of the contact failure detection circuit in the first embodiment is shown in fig. 2. Wherein V AC1 is a normal input voltage waveform, i1 is a current waveform flowing through the first switch M1 when normal, V AC2 is an input voltage waveform when the input terminal is in poor contact, and i2 is a current waveform flowing through the first switch M1 when the input terminal is in poor contact. The comparison between the current i1 flowing through the first switch M1 at normal time and the current i2 flowing through the first switch M1 when the input terminal is in poor contact can be achieved, whether the input terminal is in poor contact can be detected by detecting the current i flowing through the first switch M1, and when the current i flowing through the first switch M1 can exceed a third threshold value, the occurrence of poor contact can be considered, and the control circuit keeps the first switch M1 open.
The specific circuit diagram is shown in fig. 3. The poor contact detection circuit comprises a first comparator, the sampling resistor R0 detects the current flowing through the first switch M1 and inputs the current to a first input end of the comparator comp1, a second input end of the comparator comp1 receives a third threshold value, the output of the comp1 is connected with the pulse generation circuit, when the current flowing through the first switch M1 reaches the third threshold value, the comparator comp1 is turned over, and the pulse generator sends out pulses so that the first switch is turned off.
As shown in fig. 4, a block diagram of an embodiment to which the leakage protection circuit of the present invention is applied is illustrated. Wherein the contact failure detection circuit receives a signal indicative of the voltage at the input terminal, the output terminal is connected to the pulse generation circuit, and the rest is the same as in fig. 1.
Fig. 5 shows a schematic diagram of a bad contact detection circuit in a second embodiment of the present invention. Wherein V AC1 is a normal input voltage waveform, V SLP1 is a normal voltage change rate waveform, V AC2 is an input voltage with poor contact at the input terminal, and V SLP2 is a voltage change rate waveform with poor contact at the input terminal. Comparing the normal voltage change rate V SLP1 with the voltage change rate V SLP2 when the input terminal is in poor contact, detecting whether the input terminal is in poor contact or not by detecting the change rate V SLP of the input terminal voltage, and when the change rate V SLP of the input terminal voltage can exceed the fourth threshold value, the control circuit can consider that the poor contact is generated, and the first switch M1 is kept turned off.
Fig. 6 shows a specific circuit diagram of a contact failure detection circuit according to the principle of fig. 4. The poor contact detection circuit comprises a resistor R1, a first capacitor C1 and a third comparator comp2, wherein one end of the first capacitor C1 receives a voltage detection signal representing input voltage, the other end of the first capacitor C1 is connected with one end of the resistor R1, the other end of the resistor R1 is grounded, a first input end of the second comparator comp2 is connected with a common end of the first resistor and the first capacitor, a second input end of the second comparator receives a third threshold Vref4, and an output end of the second comparator is connected with the control circuit. When the value of the first input end of the second comparator is larger than the third threshold Vref4, the output end of the comparator comp4 is subjected to level inversion at the moment, and the first switch M1 is controlled to be turned off through the control circuit.
Fig. 7 is a schematic diagram illustrating a third embodiment of a leakage protection circuit according to the present invention, wherein an input terminal of the contact failure circuit receives a voltage at a first terminal of the first switch M1 or a voltage difference between the first terminal and a second terminal of the first switch M1, and an output terminal of the contact failure detection circuit is a pulse generating circuit of a control circuit, and the control circuit turns off the first switch M1 when the voltage at the first terminal of the first switch M1 or the voltage difference between the first terminal and the second terminal of the first switch M1 reaches a fifth threshold.
The principle of the contact failure detection circuit is that when the voltage of the first end of the first switch M1 or the voltage difference between the first end and the second end of the first switch M1 is lower than a fifth threshold value, when the voltage of the first end of the first switch M1 or the voltage difference between the first end and the second end of the first switch M1 reaches the fifth threshold value, the contact failure phenomenon can be considered to occur, and the control circuit keeps the first switch M1 open.
The specific embodiment of the pulse generator is not shown in the drawings, and may be a comparator, one end of the comparator is connected to the first end of the first switch, the second end of the comparator receives a fifth threshold, the output of the comparator is connected to the pulse generating circuit, the voltage at the first end of the first switch reaches the fifth threshold, the comparator turns over, and the pulse generator sends out a pulse, so that the first switch is turned off.
Another detection principle of the bad contact circuit shown in fig. 7 is: according to the change rate of the voltage of the first end of the first switch M1 or the change rate of the voltage difference between the first end and the second end of the first switch M1, when the change rate of the voltage of the first end of the first switch M1 or the change rate of the voltage difference between the first end and the second end of the first switch M1 reaches a sixth threshold value, the control circuit turns off the first switch M1.
It should be noted that the poor contact described in the present invention includes not only the poor contact in the conventional sense, that is, no voltage is applied for a period of time, but also the case where the voltage suddenly increases, such as the occurrence of lightning surge voltage at the input terminal. Therefore, the contact failure detection circuit of the present invention can detect the cases of the input terminal contact failure and the abrupt increase of all the input terminal voltages.
In addition, although the embodiments are described and illustrated separately above, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and that reference may be made to another embodiment without explicitly recited in one of the embodiments.
The above-described embodiments do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present invention.
Claims (11)
1. A leakage protection circuit, comprising:
The current detection circuit is used for detecting current flowing through a first switch connected to the main loop to obtain a current detection signal representing the current flowing through the first switch, and judging that the input end has a leakage phenomenon if the current detection signal is lower than a first threshold value;
The voltage detection circuit is used for detecting the voltage of an input end or the voltage of a first end of the first switch or the voltage difference between the first end and a second end of the first switch to obtain a voltage detection signal, the first switch is turned on when the voltage detection signal reaches a second threshold value, and the current detection circuit is used for detecting the current flowing through the first switch;
The contact failure detection circuit judges whether the input end has a contact failure phenomenon according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch;
The control circuit is used for controlling the on and off of the first switch, the current detection circuit is used for detecting the current flowing through the first switch during the on period of the first switch, and if the current detection signal is lower than a first threshold value, the control circuit is used for controlling the first switch to be turned off; if the current detection signal reaches a first threshold value, the first switch is continuously turned on, the contact failure detection circuit judges whether the input end is in poor contact or not, and when the contact failure detection circuit judges that the input end is in poor contact, the control circuit controls the first switch to be turned off.
2. The leakage protection circuit of claim 1, wherein: after the first switch is turned off, the current detection circuit performs leakage detection again.
3. The leakage protection circuit according to claim 1 or 2, characterized in that: the contact failure detection circuit detects current flowing through the first switch, and when the current flowing through the first switch reaches a third threshold value, the contact failure detection circuit judges that the input end is in poor contact.
4. A leakage protection circuit according to claim 3, wherein: the poor contact detection circuit comprises a first comparator, a first input end of the first comparator receives a current detection signal representing current flowing through a first switch, a second input end of the first comparator receives the third threshold value, when the current detection signal reaches the third threshold value, the first comparator turns over, and an output end of the first comparator is connected with the control circuit.
5. The leakage protection circuit according to claim 1 or 2, characterized in that: the contact failure detection circuit detects the voltage of the input end, and when the change rate of the voltage of the input end reaches a fourth threshold value, the contact failure detection circuit judges that the contact failure occurs at the input end.
6. The leakage protection circuit of claim 5, wherein: the poor contact detection circuit comprises a first resistor, a first capacitor and a second comparator, wherein one end of the first capacitor receives a voltage detection signal representing input voltage, the other end of the first capacitor is connected with one end of the first resistor, the other end of the first resistor is grounded, the first input end of the second comparator is connected with a common end of the first resistor and the first capacitor, the second input end of the second comparator receives a fourth threshold value, and the output end of the second comparator is connected with the control circuit.
7. The leakage protection circuit according to claim 1 or 2, characterized in that: the contact failure detection circuit detects the voltage of the first end of the first switch or the pressure difference between the first end and the second end of the first switch, and when the voltage of the first end of the first switch or the pressure difference between the first end and the second end of the first switch reaches a fifth threshold value, the contact failure detection circuit judges that the input end is in poor contact.
8. The leakage protection circuit according to claim 1 or 2, characterized in that: the contact failure detection circuit detects the voltage of the first end of the first switch or the pressure difference between the first end and the second end of the first switch, and when the voltage change rate of the first end of the first switch or the pressure difference change rate of the first end and the second end of the first switch reaches a sixth threshold value, the contact failure detection circuit judges that the input end is in poor contact.
9. The leakage protection circuit according to claim 1 or 2, characterized in that: the first switch is a MOS tube, the first end of the first switch is a drain electrode, the second end of the first switch is a source electrode, and the control end of the first switch is a grid electrode.
10. The leakage protection circuit according to claim 1 or 2, characterized in that: the control circuit comprises a pulse generating circuit and a logic circuit, wherein the input end of the pulse generating circuit is connected with the logic circuit and the poor contact detection circuit, and the output end of the pulse generating circuit is connected with the control end of the first switch.
11. A leakage protection method, characterized by comprising:
detecting the current flowing through a first switch connected to a main loop to obtain a current detection signal representing the current flowing through the first switch, wherein the current detection signal is lower than a first threshold value, and judging that the input end has a leakage phenomenon;
Detecting the voltage of an input end or the voltage of a first end of the first switch or the voltage difference between the first end and a second end of the first switch to obtain a voltage detection signal, wherein the first switch is conducted when the voltage detection signal reaches a second threshold value, and detecting the current flowing through the first switch;
judging whether the input end is in poor contact or not according to the current flowing through the first switch or the voltage change rate of the input end or the voltage of the first end of the first switch or the voltage difference between the first end and the second end of the first switch or the voltage change rate of the first end of the first switch or the voltage difference change rate of the first end and the second end of the first switch;
Controlling the on and off of a first switch, detecting the current flowing through the first switch during the on period of the first switch, and controlling the first switch to be turned off if the current detection signal is lower than a first threshold value; if the current detection signal reaches a first threshold value, the first switch is continuously turned on, whether the input end is in poor contact or not is judged, and when the input end is in poor contact, the first switch is controlled to be turned off.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2017100856468 | 2017-02-17 | ||
| CN201710085646 | 2017-02-17 |
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| CN108462150A CN108462150A (en) | 2018-08-28 |
| CN108462150B true CN108462150B (en) | 2024-10-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201820241918.9U Active CN208174241U (en) | 2017-02-17 | 2018-02-10 | A kind of leakage protection circuit |
| CN201810139245.0A Active CN108233332B (en) | 2017-02-17 | 2018-02-10 | Leakage protection circuit and method |
| CN201810140125.2A Active CN108270195B (en) | 2017-02-17 | 2018-02-10 | Leakage protection circuit and method |
| CN201820240165.XU Withdrawn - After Issue CN208174237U (en) | 2017-02-17 | 2018-02-10 | leakage protection circuit |
| CN201820247694.2U Withdrawn - After Issue CN208174243U (en) | 2017-02-17 | 2018-02-11 | A kind of leakage protection circuit |
| CN201810143661.8A Active CN108429236B (en) | 2017-02-17 | 2018-02-11 | Leakage protection circuit and method |
| CN201810143966.9A Active CN108462150B (en) | 2017-02-17 | 2018-02-11 | Leakage protection circuit and method |
| CN201820247590.1U Withdrawn - After Issue CN208174246U (en) | 2017-02-17 | 2018-02-11 | leakage protection circuit |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201820241918.9U Active CN208174241U (en) | 2017-02-17 | 2018-02-10 | A kind of leakage protection circuit |
| CN201810139245.0A Active CN108233332B (en) | 2017-02-17 | 2018-02-10 | Leakage protection circuit and method |
| CN201810140125.2A Active CN108270195B (en) | 2017-02-17 | 2018-02-10 | Leakage protection circuit and method |
| CN201820240165.XU Withdrawn - After Issue CN208174237U (en) | 2017-02-17 | 2018-02-10 | leakage protection circuit |
| CN201820247694.2U Withdrawn - After Issue CN208174243U (en) | 2017-02-17 | 2018-02-11 | A kind of leakage protection circuit |
| CN201810143661.8A Active CN108429236B (en) | 2017-02-17 | 2018-02-11 | Leakage protection circuit and method |
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| CN208174241U (en) * | 2017-02-17 | 2018-11-30 | 杰华特微电子（杭州）有限公司 | A kind of leakage protection circuit |
| CN111148309B (en) * | 2018-10-16 | 2023-08-25 | 卡任特照明解决方案有限公司 | Lamp driving circuit and method for operating the same |
| US10976762B2 (en) * | 2018-10-26 | 2021-04-13 | Rolls-Royce North American Technologies, Inc. | Control of an electrical power system responsive to sensing a ground fault |
| CN110601134A (en) * | 2019-09-10 | 2019-12-20 | 杰华特微电子（杭州）有限公司 | Leakage protection circuit, protection method and lighting circuit applying leakage protection circuit |
| CN110601133A (en) * | 2019-09-10 | 2019-12-20 | 杰华特微电子（杭州）有限公司 | Leakage protection circuit, protection method and lighting circuit applying leakage protection circuit |
| CN110768207A (en) * | 2019-10-12 | 2020-02-07 | 杭州士兰微电子股份有限公司 | Leakage protection circuit and drive circuit |
| CN211655982U (en) * | 2019-12-31 | 2020-10-09 | 杰华特微电子（杭州）有限公司 | Switching power supply and lighting driving circuit |
| CN111368500A (en) | 2020-03-06 | 2020-07-03 | 杰华特微电子（杭州）有限公司 | Method for establishing metal interconnection layer capacitance prediction model and model system |
| CN115441399A (en) * | 2020-05-26 | 2022-12-06 | 芯海科技（深圳）股份有限公司 | Leakage protection circuit, integrated circuit, electronic device, and method |
| CN111983440B (en) * | 2020-07-16 | 2023-03-24 | 中广核核电运营有限公司 | Socket detection method and socket detection device |
| CN113014128A (en) * | 2021-03-26 | 2021-06-22 | 安徽电气工程职业技术学院 | DCAC control circuit in domestic dc-to-ac converter |
| CN114615774B (en) * | 2021-09-22 | 2024-08-23 | 杰华特微电子股份有限公司 | Leakage protection circuit and dimming driving circuit |
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- 2018-02-10 CN CN201820240165.XU patent/CN208174237U/en not_active Withdrawn - After Issue
- 2018-02-11 CN CN201820247694.2U patent/CN208174243U/en not_active Withdrawn - After Issue
- 2018-02-11 CN CN201810143661.8A patent/CN108429236B/en active Active
- 2018-02-11 CN CN201810143966.9A patent/CN108462150B/en active Active
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Also Published As
| Publication number | Publication date |
|---|---|
| CN208174237U (en) | 2018-11-30 |
| CN208174246U (en) | 2018-11-30 |
| CN108233332A (en) | 2018-06-29 |
| CN108462150A (en) | 2018-08-28 |
| CN108270195A (en) | 2018-07-10 |
| CN208174243U (en) | 2018-11-30 |
| CN108233332B (en) | 2024-09-20 |
| CN108429236A (en) | 2018-08-21 |
| CN208174241U (en) | 2018-11-30 |
| CN108270195B (en) | 2024-10-29 |
| CN108429236B (en) | 2024-10-25 |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |
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