Leakage protection circuit and leakage protection method

Abstract

The present invention proposes a leakage protection circuit and a protection method. The leakage protection circuit is respectively applied to N parallel lighting circuits. The leakage protection circuit includes a reference generation circuit and a leakage detection circuit. The reference generation circuit generates a reference voltage, and the reference voltage is greater than a first threshold value and less than a second threshold value. When the input voltage reaches the reference voltage, the leakage detection circuit detects whether the load input terminal is leaking. If the load input terminal is leaking, the load switch is controlled to be turned off or the load is not enabled. If the load input terminal is not leaking, the load switch is controlled to be turned on or the load is enabled. The N reference voltages generated by the N leakage protection circuits are distributed between the first threshold value and the second threshold value. The present invention can avoid the leakage detection of multiple lamps at the same time and increase the number of multiple lamps in parallel.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and in particular to a leakage protection circuit and a leakage protection method. Background Art

[0002] In the prior art, for a leakage detection circuit with multiple lamps connected in parallel, its working waveform is as follows: Figure 1 As shown, when the input voltage reaches a fixed threshold, leakage detection is performed to obtain the detection current. When the detection current I D When it is less than the reference signal, it indicates that there is leakage at the load input, and leakage protection is then performed. However, when multiple lamps are connected in parallel, when multiple lamps are tested for leakage at the same time, the leakage test results are easily wrong due to the influence of line impedance and AC power supply impedance, and normal detection cannot be completed. Summary of the invention

[0003] The object of the present invention is to provide a leakage detection circuit capable of increasing the number of multiple lamps connected in parallel, so as to solve the problem in the prior art that the leakage detection result is prone to error when multiple lamps are connected in parallel.

[0004] To achieve the above object, the present invention provides a leakage protection circuit, which is applied to N parallel lighting circuits respectively, and comprises:

[0005] A reference generating circuit generates a reference voltage, wherein the reference voltage is greater than a first threshold value and less than a second threshold value;

[0006] A leakage detection circuit, when the input voltage reaches the reference voltage, the leakage detection circuit detects whether the load input terminal is leaking; if the load input terminal is leaking, the load switch is controlled to be turned off or the load is controlled to be disabled; if the load input terminal is not leaking, the load switch is controlled to be turned on or the load is controlled to be enabled;

[0007] The N reference voltages respectively generated by the N leakage protection circuits are distributed between the first threshold and the second threshold.

[0008] Optionally, the N reference voltages respectively generated by the N leakage protection circuits obey a normal distribution, approximately obey a normal distribution, or obey a random distribution.

[0009] Optionally, the leakage protection circuit generates a reference voltage each time the leakage protection circuit is connected to an input power supply.

[0010] Optionally, each time the leakage protection circuit is connected to an input power source, the reference voltage generated is the same.

[0011] Optionally, the reference generating circuit includes a fixed threshold generating circuit and a first threshold generating circuit, the fixed threshold generating circuit generates a fixed threshold voltage, and the first threshold generating circuit generates a first threshold voltage; the reference voltage is obtained after the fixed threshold voltage and the first threshold voltage are calculated.

[0012] Optionally, the first threshold generating circuit includes one or more operational amplifier units and a first signal processing circuit, two input terminals of each operational amplifier are short-circuited, and the output signal of each operational amplifier generates the first threshold voltage through the first signal processing circuit.

[0013] Optionally, the first threshold generating circuit includes one or more unit modules and a second signal processing circuit, and the output signals of the one or more unit modules are processed by the second signal processing circuit to generate the first threshold voltage; each unit module includes two inverters, the input end of one inverter is connected to the output end of another inverter, and the output of one inverter is the output of each unit module.

[0014] Optionally, the leakage detection circuit includes a current detection circuit and a first comparator, the first input terminal of the first comparator receives an input voltage, the second input terminal of the first comparator receives the reference voltage, and the first comparator outputs a signal to control the current detection circuit; the first end of the current detection circuit is connected to a high potential output terminal of a rectifier circuit or one end of an input power supply, and the second end of the current detection circuit is connected to a low potential output terminal of a rectifier circuit; when the input voltage reaches the reference voltage, the current detection circuit detects the current flowing through the first resistor to obtain a current detection signal, and if the current detection signal is lower than a first threshold value, it indicates that there is leakage at the load input terminal.

[0015] Optionally, the current detection circuit includes a first switch tube and a second comparator, the first end of the first switch tube is directly or indirectly connected to the high-potential output end of the rectifier circuit or one end of the input power supply, and the second end of the first switch tube is connected to the low-potential output end of the rectifier circuit through a first resistor; when the input voltage reaches the reference voltage, the first switch tube is briefly turned on, and the voltage at the second end of the first switch tube is the current detection signal; the first input end of the second comparator is connected to the second end of the first switch tube, the second end of the second comparator receives a first threshold, and the output signal of the second comparator indicates whether the load input end is leaking.

[0016] The present invention also provides a leakage protection method, which is based on a leakage protection circuit. The leakage protection circuits are respectively applied to N parallel lighting circuits, and the leakage protection circuit generates a reference voltage; when the input voltage reaches the reference voltage, it is detected whether the load input terminal is leaking; if the load input terminal is leaking, the load switch is controlled to be turned off or the load is controlled not to be enabled; if the load input terminal is not leaking, the load switch is controlled to be turned on or the load is controlled to be enabled; the N leakage protection circuits respectively generate N reference voltages distributed between a first threshold and a second threshold.

[0017] Compared with the prior art, the present invention has the following advantages: the leakage protection circuit is applied to N parallel lighting circuits respectively, and the leakage protection circuit generates a reference voltage; when the input voltage reaches the reference voltage, it detects whether the load input terminal is leaking; if the load input terminal is leaking, the load switch is controlled to be turned off or the load is controlled not to be enabled; if the load input terminal is not leaking, the load switch is controlled to be turned on or the load is controlled to be enabled; the N leakage protection circuits respectively generate N reference voltages dispersedly distributed between the first threshold and the second threshold. The present invention can avoid the leakage detection of multiple lamps at the same time and increase the number of multiple lamps in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a working waveform diagram of the leakage detection circuit in the prior art;

[0019] Figure 2 This is a working waveform diagram of the leakage detection circuit of the present invention;

[0020] Figure 3 This is a schematic diagram of the leakage detection circuit of the present invention;

[0021] Figure 4 is a schematic diagram of a first threshold value generating circuit embodiment 1 of the present invention;

[0022] Figure 5 This is a schematic diagram of a second embodiment of a first threshold value generating circuit of the present invention; DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0024] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0025] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportions, in order to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0026] like Figure 2 As shown, a working waveform diagram of the leakage detection circuit of the present invention is illustrated. Within a certain detection window of the input voltage, the leakage detection time of the leakage detection circuits in different lighting circuits is relatively random, which reduces the probability of simultaneous leakage detection and increases the number of parallel connections of multiple lighting circuits.

[0027] like Figure 3 As shown, the principle diagram of the leakage detection circuit of the present invention is illustrated, including a reference generating circuit U00, a comparator U01, a driving circuit U03, a switch tube Q1, a resistor R1, a comparator U02 and a driving circuit U03. The reference generating circuit U00 includes a fixed threshold generating circuit and a first threshold generating circuit. The fixed threshold generating circuit generates a fixed threshold voltage V1, and the first threshold generating circuit generates a first threshold voltage V2; the fixed threshold voltage V1 and the first threshold voltage V2 are calculated to obtain the reference voltage Vref1. The comparator U01 receives the reference voltage Vref1 at its in-phase input terminal, receives the input voltage sampling signal VCS at its inverting input terminal, and outputs the first comparison signal VC1 at its output terminal. The input voltage is an AC power supply, or is obtained after the AC power supply is rectified. The first end of the switch tube Q1 is connected to the high potential end of the rectifier circuit or one end of the AC input, and the second end of the switch tube Q2 is grounded through the resistor R1. The first comparison signal VC1 drives the switch tube Q1 to turn on and off through the driving circuit U03. The comparator U02 has a non-inverting input terminal connected to the second terminal of the switch tube Q1, an inverting input terminal thereof receives a threshold signal Vref2, and an output terminal thereof outputs a second comparison signal VC2. When the sampling signal VCS reaches Vref1, the first comparison signal VC1 controls the switch tube Q1 to be turned on briefly, and the voltage at the second terminal of the switch tube Q1 is a current detection signal. When the current detection signal is less than the threshold signal Vref2, it indicates that the load input terminal is leaking, and the second comparison signal VC2 controls the load switch M00 to be turned off or controls the load to be disabled.

[0028] like Figure 4 As shown, a schematic diagram of a first embodiment of the first threshold generating circuit of the present invention is illustrated, including multiple operational amplifiers, two input terminals of each operational amplifier are connected, and the output signal of each operational amplifier is calculated by the operation circuit to obtain the first threshold voltage V2. Each time the leakage protection circuit is powered on, the generated first threshold voltage V2 is the same, but the multiple first threshold voltages V2 generated by multiple different leakage protection circuits can obey a certain distribution, such as obeying a normal distribution, approximately obeying a normal distribution, or a random distribution.

[0029] like Figure 5As shown, the schematic diagram of the second embodiment of the first threshold generating circuit of the present invention is illustrated, including multiple unit modules, each unit module includes two inverters, the input end of one inverter is connected to the input end of another inverter, the output signal of one inverter is used as the output signal of the unit module, and the output signal of each unit module is calculated by the operation circuit to obtain the first threshold voltage V2. Each time the leakage protection circuit is powered on, the first threshold voltage V2 is randomly generated, but the first threshold voltage V2 generated by multiple different leakage protection circuits can obey a certain distribution, such as obeying a normal distribution, approximately obeying a normal distribution, or a random distribution.

[0030] Although the embodiments are described and illustrated separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments can be replaced and integrated. If the content is not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0031] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A leakage protection circuit, which is applied to N parallel lighting circuits, characterized in that: The leakage protection circuit comprises: A reference generating circuit generates a reference voltage, wherein the reference voltage is greater than a first threshold value and less than a second threshold value; A leakage detection circuit, when the input voltage reaches the reference voltage, the leakage detection circuit detects whether the load input terminal is leaking; if the load input terminal is leaking, the load switch is controlled to be turned off or the load is controlled to be disabled; if the load input terminal is not leaking, the load switch is controlled to be turned on or the load is controlled to be enabled; The N reference voltages respectively generated by the N leakage protection circuits are distributed between the first threshold and the second threshold.

2. The leakage protection circuit according to claim 1, characterized in that: The N reference voltages respectively generated by the N leakage protection circuits obey normal distribution, approximately obey normal distribution or randomly distribute.

3. The leakage protection circuit according to claim 1 or 2, characterized in that: The leakage protection circuit randomly generates a reference voltage each time it is connected to an input power supply.

4. The leakage protection circuit according to claim 1 or 2, characterized in that: Each time the leakage protection circuit is connected to the input power supply, the reference voltage generated is the same.

5. The leakage protection circuit according to claim 1 or 2, characterized in that: The reference generating circuit comprises a fixed threshold generating circuit and a first threshold generating circuit. The fixed threshold generating circuit generates a fixed threshold voltage, and the first threshold generating circuit generates a first threshold voltage. The reference voltage is obtained after the fixed threshold voltage and the first threshold voltage are calculated.

6. The leakage protection circuit according to claim 5, characterized in that: The first threshold voltage generating circuit includes one or more operational amplifier units and a first signal processing circuit. Two input terminals of each operational amplifier are short-circuited, and the output signal of each operational amplifier generates the first threshold voltage through the first signal processing circuit.

7. The leakage protection circuit according to claim 5, characterized in that: The first threshold generating circuit includes one or more unit modules and a second signal processing circuit, and the output signals of the one or more unit modules are processed by the second signal processing circuit to generate the first threshold voltage; each unit module includes two inverters, the input end of one inverter is connected to the output end of the other inverter, and the output of one inverter is the output of each unit module.

8. The leakage protection circuit according to claim 1, characterized in that: The leakage detection circuit includes a current detection circuit and a first comparator, wherein the first input terminal of the first comparator receives an input voltage, the second input terminal of the first comparator receives the reference voltage, and the first comparator outputs a signal to control the current detection circuit; the first terminal of the current detection circuit is connected to a high potential output terminal of a rectifier circuit or one terminal of an input power supply, and the second terminal of the current detection circuit is connected to a low potential output terminal of the rectifier circuit; when the input voltage reaches the reference voltage, the current detection circuit detects the current flowing through the first resistor to obtain a current detection signal, and if the current detection signal is lower than the second reference voltage, it indicates that there is leakage at the load input terminal.

9. The leakage protection circuit according to claim 8, characterized in that: The current detection circuit includes a first switch tube and a second comparator, wherein the first end of the first switch tube is directly or indirectly connected to the high potential output end of the rectifier circuit or one end of the input power supply, and the second end of the first switch tube is connected to the low potential output end of the rectifier circuit through a first resistor; when the input voltage reaches the reference voltage, the first switch tube is briefly turned on, and the voltage at the second end of the first switch tube is the current detection signal; the first input end of the second comparator is connected to the second end of the first switch tube, the second end of the second comparator receives the second reference voltage, and the output signal of the second comparator indicates whether the load input end is leaking.

10. A leakage protection method, based on a leakage protection circuit, wherein the leakage protection circuit is applied to N parallel lighting circuits, characterized in that: The leakage protection circuit generates a reference voltage; when the input voltage reaches the reference voltage, it detects whether the load input terminal is leaking; if the load input terminal is leaking, the load switch is controlled to be turned off or the load is controlled to be disabled; if the load input terminal is not leaking, the load switch is controlled to be turned on or the load is controlled to be enabled; N leakage protection circuits respectively generate N reference voltages dispersedly distributed between a first threshold and a second threshold.

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