阅读说明：本技术 一种用于主动防护的浪涌检测电路及检测装置 (Surge detection circuit and detection device for active protection ) 是由 饶超 陈少磊 李闯鹏 赵东升 于 2021-08-19 设计创作，主要内容包括：本发明提供一种用于主动防护的浪涌检测电路及检测装置。浪涌检测电路包括：加速电路、整流电路、采样电路,处理器。其中,加速电路用于将电源端输入的交流信号加载到采样电路中,并对电源端输入的交流信号进行分压。整流电路用于对加速电路输出的交流信号,或者电源端输入的交流信号进行整流。采样电路用于对整流电路输出的直流信号进行采集,并输出采样信号。处理器用于根据采样电路输出的采样信号,确定是否开启浪涌保护。在本申请中,浪涌检测电路直接与AC电源的输入端相连,能够在浪涌信号作用于功率器件之前进行保护,提高了系统的可靠性。(The invention provides a surge detection circuit and a detection device for active protection. The surge detection circuit includes: accelerating circuit, rectifier circuit, sampling circuit, treater. The accelerating circuit is used for loading the alternating current signal input by the power supply end into the sampling circuit and dividing the voltage of the alternating current signal input by the power supply end. The rectifying circuit is used for rectifying the alternating current signal output by the accelerating circuit or the alternating current signal input by the power supply end. The sampling circuit is used for collecting the direct current signal output by the rectifying circuit and outputting a sampling signal. The processor is used for determining whether to start surge protection according to the sampling signal output by the sampling circuit. In the application, the surge detection circuit is directly connected with the input end of the AC power supply, so that the surge detection circuit can be protected before a surge signal acts on a power device, and the reliability of the system is improved.)

1. A surge detection circuit for active protection, comprising:

the accelerating circuit consists of at least one capacitive device and is used for dividing the voltage of the alternating current signal input by the power supply end;

the rectifying circuit is used for rectifying the alternating current signal output by the accelerating circuit or the alternating current sampling signal input by the power supply end;

the sampling circuit is used for collecting the direct current signal output by the rectifying circuit and outputting a sampling signal; when a surge signal exists in an alternating current signal input to the detection circuit from a power supply end, the acceleration circuit quickly loads the surge signal into the sampling circuit;

and the processor is used for judging whether to start surge protection according to the strength of the sampling signal output by the sampling circuit.

2. The method according to claim 1, characterized in that at least two capacitive elements are included in the accelerating circuit, said at least two capacitive elements being connected in series and/or in parallel.

3. A method according to claim 2 or 3, wherein the capacitive device is a capacitor.

4. The method of claim 1, wherein the rectification circuit is comprised of a plurality of diodes or a bridge stack, the plurality of diodes constituting a rectification bridge.

5. The method of claim 4, wherein the rectifier circuit is a bridge rectifier circuit; the rectifier circuit comprises a first diode, a second diode, a third diode and a fourth diode, wherein the anode of the first diode and the cathode of the second diode are respectively connected with one end of the accelerating circuit, the cathode of the first diode is connected with the cathode of the fourth diode and the sampling circuit, the cathode of the third diode is respectively connected with the anode of the fourth diode and the other end of the power supply, and the anode of the third diode is connected with the anode of the second diode and the sampling circuit.

6. The method of claim 1, wherein the sampling circuit is comprised of at least one resistive device, at least one capacitive device, and an amplifier.

7. The method of claim 6, wherein the at least one resistive device and at least one capacitive device comprise a sampling cell; the at least one resistive device and the amplifier form a differential amplification circuit;

the first input end of the sampling unit is connected with the rectifying circuit; the first output end of the sampling unit is connected with the forward input end of the differential amplification circuit, and the second output end of the sampling unit is connected with the reverse input end of the differential amplification circuit and the rectification circuit; and the output end of the differential amplification circuit is connected with the processor.

8. The method of claim 7, wherein the sampling unit comprises a first resistor, a second resistor, and a third capacitor;

one end of the second resistor, which is connected in parallel with the third capacitor, is connected to one end of the first resistor and the positive input end of the differential amplifier circuit, respectively;

the other end of the second resistor connected in parallel with the third capacitor is connected with the reverse input end of the rectifying circuit and the reverse input end of the differential amplifying circuit respectively.

9. The method according to claim 7, wherein the power terminal inputs an alternating current signal, and when the alternating current signal is in a positive half wave of the alternating voltage, the current signal input by the power terminal flows into the sampling circuit through the first input terminal of the sampling unit and flows out of the sampling circuit through the second output terminal of the sampling unit after passing through the accelerating circuit and the rectifying circuit;

when the sampling circuit is in the negative half wave of the alternating voltage, the power supply end inputs a current signal, the current signal flows into the sampling circuit through the first input end of the sampling unit after passing through the rectifying circuit, and the current signal flows out of the sampling circuit through the second output end of the sampling unit.

10. The method of claim 1, wherein the processor is configured to:

and when the intensity of the sampling signal output by the sampling circuit is greater than a set threshold value, starting surge protection.

11. A surge detection device for active protection, characterized in that it comprises a detection circuit according to any of claims 1-10.

Technical Field

The invention relates to the technical field of circuit system protection, in particular to a surge detection circuit and a detection device for active protection.

Background

Alternating Current (AC) power supplies are widely used in various occasions requiring reliable power supply, such as servers, data centers, base stations, etc., and generally, AC power supplies are used to convert power-frequency AC of a power grid into dc power to supply power to various loads, and an AC power supply system of a battery cell is shown in fig. 1.

The AC power supply is generally composed of five parts: the EMI circuit, AC-DC circuit, DC-DC circuit, auxiliary power circuit and former secondary side control circuit constitute. The AC-DC circuit mainly comprises a rectification circuit and a PFC circuit, and is used for converting power frequency alternating current into a direct current circuit and boosting the direct current circuit to required bus voltage (400V); the DC-DC circuit is used for converting the bus voltage into the required load voltage to supply power to the load.

The AC power supply is mainly applied to data centers, base stations and other scenes using server power supplies, although the AC power supply is indoors, the requirements on surge protection are high, and the AC power supply generally needs to meet the requirements of a differential mode +/-2000V and a common mode +/-2000V. And the whole process of surge, the power supply is not allowed to have any mode of alarm, reset or output interruption, and can not be damaged.

Disclosure of Invention

The embodiment of the application provides an active protection surge detection circuit and detection device, which can protect a surge signal before the surge signal acts on a power device, and improve the reliability of a system.

In a first aspect, an embodiment of the present application provides a surge detection circuit for active protection, including: the accelerating circuit consists of at least one capacitive device and is used for dividing the voltage of the alternating current signal input by the power supply end; the rectifying circuit is used for rectifying the alternating current signal output by the accelerating circuit or the alternating current sampling signal input by the power supply end; the sampling circuit is used for collecting the direct current signal output by the rectifying circuit and outputting a sampling signal; when a surge signal exists in an alternating current signal input to the detection circuit from a power supply end, the acceleration circuit quickly loads the surge signal into the sampling circuit; and the processor is used for judging whether to start surge protection according to the strength of the sampling signal output by the sampling circuit.

In the above scheme, the surge detection circuit is formed by the acceleration circuit, the rectification circuit, the sampling circuit and the processor, and is directly connected to the input terminal of the AC power supply. When the ac signal input from the power source terminal includes a surge signal, protection can be performed before the surge signal acts on the power device.

In one possible implementation, the speed-up circuit includes at least two capacitive devices, and the at least two capacitive devices are connected in series and/or in parallel.

That is, in this implementation, since the capacitive device has a characteristic that a voltage lags a current. Therefore, when the alternating current signal input by the power supply end flows through the capacitive element in the accelerating circuit, the alternating current voltage input by the power supply end can be quickly loaded on the sampling circuit to achieve the aim of acceleration because the voltage of the capacitive element in the accelerating circuit cannot be suddenly changed. Further, the accelerating circuit is formed by capacitive devices, but the number of the capacitive devices forming the accelerating circuit may be one or more, and when the number of the capacitive devices forming the accelerating circuit is plural, the plural capacitive devices may be connected in series or in parallel, or some of the capacitive devices may be connected in series or in parallel and then connected in parallel or in series with other capacitive devices.

In one possible implementation, the capacitive device is a capacitor.

That is, in this embodiment, the capacitor is one of the capacitive devices, and has a characteristic that a voltage lags behind a current, so that the ac voltage input from the power supply terminal can be quickly applied to the sampling circuit.

In one possible implementation, the rectifier circuit is composed of a plurality of diodes or a bridge stack, wherein the plurality of diodes form a rectifier bridge.

That is to say, in this implementation, the rectifying circuit rectifies the ac signal input by the power supply terminal into a dc signal and outputs the dc signal to the sampling circuit, and the rectifying circuit is composed of a bridge or a rectifying bridge composed of a plurality of diodes, so that the sampling circuit can collect and detect the electrical signals input by the power supply terminal in different directions.

In one possible implementation, the rectifier circuit is a bridge rectifier circuit; the rectifying circuit comprises a first diode, a second diode, a third diode and a fourth diode; the anode of the first diode and the cathode of the second diode are respectively connected with one end of the accelerating circuit, the cathode of the first diode is connected with the cathode of the fourth diode and the sampling circuit, the cathode of the third diode is respectively connected with the anode of the fourth diode and the other end of the power supply, and the anode of the third diode is connected with the anode of the second diode and the sampling circuit.

That is, in this implementation, the bridge rectifier circuit is composed of four diodes, so that the voltage input from the power source terminal is input to the sampling circuit from the same input terminal after passing through the rectifier circuit no matter whether the voltage is in a positive half-wave or a negative half-wave. So that the sampling circuit can realize the detection of signals in different directions.

In one possible implementation, the sampling circuit is composed of at least one resistive device, at least one capacitive device, and an amplifier.

In one possible implementation, the at least one resistive device and the at least one capacitive device constitute a sampling unit; the at least one resistive device and the amplifier form a differential amplification circuit; the first input end of the sampling unit is connected with the rectifying circuit; the first output end of the sampling unit is connected with the forward input end of the differential amplification circuit, and the second output end of the sampling unit is connected with the reverse input end of the differential amplification circuit and the rectification circuit; the output end of the differential amplifying circuit is connected with the processor.

That is, in this implementation, after the collected voltage across the second resistor is amplified, it can be determined whether a surge signal is present in the circuit. When the surge signal exists, the sampling circuit can judge before the surge signal acts on the power device, and carry out surge protection, so that the reliability of the system is improved.

In one possible implementation, the sampling unit includes a first resistor, a second resistor, and a third capacitor; one end of the second resistor, which is connected in parallel with the third capacitor, is connected to one end of the first resistor and the positive input end of the differential amplifier circuit, respectively; the other end of the second resistor, which is connected with the third capacitor in parallel, is connected with the rectifier circuit and the reverse input end of the differential amplifier circuit respectively.

In one possible implementation, the sampling unit includes a first resistor, a second resistor, and a third capacitor; one end of the second resistor, which is connected in parallel with the third capacitor, is connected with one end of the first resistor and the positive input end of the differential amplification circuit respectively; the other end of the second resistor and the other end of the third capacitor which are connected in parallel are respectively connected with the reverse input ends of the rectifying circuit and the differential amplifying circuit.

In one possible implementation mode, the power supply end inputs an alternating current signal, and when the alternating current signal is in a positive half wave of an alternating voltage, a current signal input by the power supply end flows into the sampling circuit through the first input end of the sampling unit after passing through the accelerating circuit and the rectifying circuit, and flows out of the sampling circuit through the second output end of the sampling unit; when the sampling circuit is in the negative half wave of the alternating voltage, a power supply end inputs a current signal, the current signal flows into the sampling circuit through a first input end of the sampling unit after passing through the rectifying circuit, and the current signal flows out of the sampling circuit through a second output end of the sampling unit.

That is, in this implementation, the positive half-wave and the negative half-wave of the alternating voltage are described as an example, respectively. The direction of the current flowing into the sampling circuit after the current input from the power supply terminal passes through the rectifier circuit is the same regardless of whether the current is in the positive half wave or the negative half wave of the alternating voltage. Therefore, the sampling circuit can realize the detection of signals in different directions.

In one possible implementation, the processor is further configured to: and when the intensity of the sampling signal output by the sampling circuit is greater than a set threshold value, starting surge protection.

In a second aspect, the present application provides a surge detection device for active protection, where the surge detection device includes the surge detection circuit of the first aspect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of an AC power supply;

fig. 2 is a schematic diagram of a conventional surge detection circuit;

fig. 3 is a schematic structural diagram of a surge detection circuit provided in the present application;

fig. 4 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 5a is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 5b is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 6 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 7 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 8 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 9 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 10 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 11 is a schematic structural diagram of another surge detection circuit provided in the present application;

fig. 12 is a schematic structural diagram of another surge detection circuit provided in the present application;

Detailed Description

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

In the description of the embodiment of the present application, the term "and/or" is only one kind of association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, B exists alone, and A and B exist at the same time. In addition, the term "plurality" means two or more unless otherwise specified. For example, the plurality of systems refers to two or more systems, and the plurality of screen terminals refers to two or more screen terminals.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit indication of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.

At present, the surge protection circuit of the AC power supply is simpler, and the more mature scheme in the industry is as follows: the bus voltage or the current of a PFC part is sampled through Digital Signal Processing (DSP), when a surge signal arrives, the bus voltage is increased due to huge surge energy, and the current flowing through a PFC sampling resistor is increased.

As shown in fig. 2, when a surge signal arrives, the surge signal flows through the first loop and the second loop, the sampling values at two ends of the current sampling resistor R become large due to huge surge energy, and whether the surge comes can be judged after amplification by the operational amplifier and sampling processing by the DSP. Similarly, when the surge flows through the loop II, the bus capacitor C is also charged to increase the voltage at two ends of the bus capacitor C, and the bus capacitor C is compared with a set value after being sampled and amplified to judge whether the surge comes or not.

The passive protection + active protection is adopted in the surge detection scheme shown in fig. 2. The surge signal can still flow through a power switch device in the system, namely the power switch device is required to be hard to resist for 10-20 us, and 1-2 switching cycles are carried out on the current platform. At present, the working frequency of most power supplies is lower, the inductance is larger, so that the surge impact current is not too high, and the switching device can resist the past. However, with the implementation of high power density, the volume inductance of the magnetic device is limited, the frequency is increased, and the impulse current is increased, for example, for MHz, 10 switching cycles have passed, which is equivalent to that the power device should be protected after 10 switching cycles, thereby greatly reducing the reliability of the system.

Fig. 3 is a schematic structural diagram of an actively-protected surge detection circuit according to an embodiment of the present invention, and as shown in fig. 3, the actively-protected surge detection circuit includes: the device comprises an AC power supply, a surge detection circuit, a PFC circuit, a DC-DC circuit and a load circuit.

The L line and the N line of the AC power supply are respectively connected to a PFC circuit, and the PFC circuit is connected with a load through a DC-DC circuit. A surge detection circuit is also connected between the AC power supply and the PFC circuit. The surge detection circuit is composed of an acceleration circuit, a rectification circuit, a sampling amplification circuit and a DSP. One end of the AC power supply is connected with the rectifying circuit through the accelerating circuit, and the other end of the AC power supply is directly connected with the rectifying circuit; the rectification circuit is connected with the sampling amplification circuit, and the sampling amplification circuit is connected with the DSP.

In one possible example, the L line of the AC power source is connected to the first end of the rectifying circuit through the acceleration circuit, the N line of the AC power source is directly connected to the second end of the rectifying circuit, the third end of the rectifying circuit is connected to the input end of the sampling amplification circuit, the second end of the rectifying circuit is connected to the first output end of the sampling amplification circuit, and the second output end of the sampling amplification circuit is connected to the DSP.

The accelerator circuit may be connected to the AC power source L line or may be connected to the AC power source N line. And need not be so limited.

Further, the AC power source may be a commercial power or an alternating current input power source.

The speed-up circuit may consist of one capacitive element or of at least two capacitive elements to increase the speed of the overall detection circuit. When the speed-up circuit is composed of two capacitive devices, the two capacitive devices may be connected in series or in parallel. When the accelerating circuit is composed of more than two capacitive devices, the more than two capacitive devices can be connected in series or in parallel, or part of the more than two capacitive devices can be connected in parallel and then connected in series with the rest capacitive devices, or part of the more than two capacitive devices can be connected in series and then connected in parallel with the rest capacitive devices.

The rectifier circuit is a circuit for converting alternating current into direct current. The rectifying circuit mainly comprises rectifying diodes, and the voltage passing through the rectifying circuit is not alternating current voltage but mixed voltage containing direct current voltage and alternating current voltage, which can be called unidirectional pulsating direct current voltage. Specifically, the rectifying circuit is composed of a plurality of diodes or a bridge stack, wherein the plurality of diodes constitute a rectifying bridge, so that the sampling circuit can sample and detect signals in different directions.

The sampling circuit may be composed of a plurality of resistive devices, capacitive devices, and op amps. The at least one capacitive device and the at least one resistive device form a sampling unit, and the at least one resistive device and the amplifier form an amplifying circuit. The first input end of the sampling unit is connected with the rectifying circuit, the first output end of the rectifying circuit is connected with the forward input end of the amplifying circuit, the second output end of the sampling circuit is connected with the reverse input end of the amplifying circuit and the rectifying circuit, and the output end of the rectifying circuit is connected with the processor.

In one possible example, the at least one capacitive device and the differential amplifier constitute a differential amplification circuit.

In the embodiment of the application, the principle that the voltage leads the current and the voltage of the capacitor cannot change suddenly is adopted. An accelerating circuit composed of a capacitive device is connected in series between the rectifying circuit and the AC power supply, and the passive and active protection mode of the original surge detection circuit is changed into active protection, so that when a surge signal arrives, the surge signal can be detected before the surge signal reaches a load, and the protection on the surge signal is started.

Fig. 4 is a schematic circuit diagram of a specific example of the surge detection circuit shown in fig. 3. As shown in fig. 4, the acceleration circuit includes a first capacitor C1 and a second capacitor C2, the rectifier circuit includes four diodes connected to each other to form a bridge rectifier circuit, and the sampling circuit includes a sampling unit and a differential amplifier circuit.

The sampling unit comprises a first resistor R1, a second resistor R2 and a third capacitor C3. The first resistor R1 and the second resistor R2 divide the voltage output by the rectifying circuit through serial voltage division to realize the output of the sampling signal, and the voltage divided on the second resistor R2 is the sampling signal of the sampling unit. The voltage division ratio of the first resistor R1 and the second resistor R2 can be adjusted by adjusting the resistance values of the first resistor R1 and the second resistor R2, and further the sampling signal output by the sampling unit is adjusted. The third capacitor C3 is used for filtering out the alternating current component in the direct current power supply rectified by the rectifying circuit, and the sensitivity of the surge protection circuit to surge signals can be adjusted by adjusting the capacity of the third capacitor C3 according to the frequency selection and filtering characteristics of the third capacitor C3.

In the surge detection circuit shown in fig. 4, a first capacitor C1 and a second capacitor C2 are connected in series, the other end of the first capacitor C1 is connected to the L line of the AC power supply, the other end of the second capacitor C2 is connected to the anode of a first diode D1 and the cathode of a second diode D2, respectively, one end of the cathode of a first diode D1 connected to the cathode of a fourth diode D4 is connected to one end of a first resistor R1, the anode of a fourth diode D4 is connected to the cathode of a third diode D3 and the connected end is connected to the N end of the AC power supply, and the anode of a third diode D3 is connected to the anode of the second diode D2; one end of the second resistor R2 and one end of the third capacitor C3 which are connected in parallel are respectively connected with the first resistor R1 and the same-direction input end of the differential amplification circuit, and the other end of the second resistor R2 and the other end of the third capacitor C3 which are connected in parallel are respectively connected with the anode of the second diode D2 and the reverse-direction input end of the differential amplification circuit; the output end of the differential amplifying circuit is connected with the DSP.

When the AC signal is at the positive half wave of the voltage of the AC output, as shown in fig. 5a, after the AC signal flows through the first capacitor C1, the second capacitor C2, the first diode D1, the first resistor R1, the second resistor R2 and the third capacitor C3, part of the current flows back to the power supply terminal through the third diode D3.

When the voltage is at the negative half wave of the AC output, the AC signal returns to the power source terminal after passing through the fourth diode D4, the first resistor R1, the second resistor R2, the third capacitor C3, the second diode D2, the second capacitor C2, and the first capacitor C1, as shown in fig. 5 b.

When the voltage value of the AC output of the AC power supply is normal, namely no surge signal occurs. Since the frequency of the alternating current signal output from the power source terminal AC is low, the resistances of the first capacitor C1 and the second capacitor C2 are large. Therefore, most of the voltage output by the AC power supply is applied to the first capacitor C1 and the second capacitor C2, so that the voltage divided by the first resistor R1 and the second resistor R2 is small, i.e., the voltage sampled by the sampling circuit is small.

When a surge signal arrives, the voltage on the first capacitor C1 and the second capacitor C2 cannot change suddenly, so that the surge voltage is quickly applied to the first resistor R1 and the second resistor R2, the voltage on the first resistor R1 and the second resistor R2 is quickly increased, and the voltage signal sampled by the sampling unit is also quickly increased. When a surge signal arrives, the voltage on the second resistor R2 is collected to judge whether the surge signal exists.

Further, a reference voltage value may be preset, and when the collected voltage value is smaller than the reference voltage value, it may be determined that no surge signal is present in the circuit. When the voltage value collected by the sampling circuit is greater than the preset reference voltage value, the surge signal in the circuit can be judged, and then the surge protection of the circuit is triggered and started through the DSP.

In the embodiment of the application, the rapid detection of the surge signal in the circuit is realized by coupling an accelerating circuit between the AC power supply and the rectifying circuit. When no surge signal exists in the circuit, the frequency of an alternating current signal in the circuit is lower, so that the resistance value of a capacitor in the acceleration circuit is larger, most of voltage in the circuit is loaded on the capacitor in the acceleration circuit, and the voltage collected by the sampling unit is lower. When surge signals exist in the circuit, because the capacitor voltage in the accelerating circuit can not change suddenly, the voltage output by the AC power supply can be quickly loaded on the resistor in the sampling circuit connected with the accelerating circuit in series, so that the sampling circuit can quickly acquire larger voltage signals to judge whether the surge signals arrive or not, and the detection speed of the detection circuit on the surge is improved.

In one possible embodiment, when the surge signal is a positive surge of a positive half wave, the flow of the AC signal output by the AC power source AC is as shown in fig. 5 a.

When the surge signal is a negative surge of a positive half wave, the flow of the AC signal output by the AC power source AC is as shown in fig. 5a before the surge signal arrives. At the moment when the surge signal arrives, the flow of the AC signal output by the AC power supply AC is as shown in fig. 5b because the surge signal is sufficiently large. When the surge passes, the flow direction of the AC signal output by the AC power supply AC is restored again as shown in fig. 5 a.

When the surge signal is a positive surge of a negative half wave, the flow of the AC signal output by the AC power source AC before the arrival of the surge signal is as shown in fig. 5 b. At the moment when the surge signal arrives, the flow of the AC signal output by the AC power supply AC is as shown in fig. 5a because the surge signal is sufficiently large. When the surge passes, the flow direction of the AC signal output from the AC power source AC is restored again as shown in fig. 5 b.

When the surge signal is a negative surge of a negative half wave, the flow of the AC signal output by the AC power source AC is as shown in fig. 5 b.

In one possible example, when the surge signal is at the positive half of the input voltage, the loop of the current is: flows out of the L line, passes through a first capacitor C1, a second capacitor C2, a first diode D1, a first resistor R1, a second resistor R2, a third capacitor C3 and a third diode D3, and then returns to the N line. When the input voltage is in a negative half wave, the current loop is as follows: flows out of the N line, passes through a fourth diode D4, a first resistor R1, a second resistor R2, a third capacitor C3, a second diode D2, a second capacitor C2 and a first capacitor C1, and returns to the L line.

Wherein, the capacitance reactancef is frequency and C is capacitance.

Parallel resistance of resistor R2 and capacitor C3

Loop current

Capacitor voltage V_C＝I·X_C；

The voltage across the sampling resistor R2 can then be expressed as: v_R2＝V_C3＝V_in-V_C1-V_C2-V_D1-V_D3-V_R1；

Because the surge duration is short, it is equivalent to a high frequency signal. Therefore, by adjusting the parameters, the partial pressure value of the whole loop depends on the capacitive reactance of C1, C2 and C3. Specifically, the capacitance values of the first capacitor C1 and the second capacitor C2 may be set to be smaller than the capacitance value of the third capacitor C3, and the capacitance reactance of the first capacitor C1 and the second capacitor C2 is larger at this time. When the circuit generates surge, most of voltage can be applied to the first capacitor C1 and the second capacitor C2, so that the protection capability of the circuit to the surge is improved, and the protection capability to the surge is improved to 3kv even 4kv from the original 2 kv.

In the embodiment of the present application, the current rectified by the rectifying circuit flows into the sampling circuit through the first resistor R1 in the sampling circuit regardless of whether the surge signal is in the positive half wave or the negative half wave of the input voltage. Therefore, the sampling circuit is ensured to collect current or voltage signals in all directions, and detection of surge signals in all directions is realized.

In one possible embodiment, as shown in fig. 6, the acceleration circuit is connected in parallel by a first capacitor C1 and a second capacitor C2, one end of the parallel connection of the first capacitor C1 and the second capacitor C2 is connected to the power supply, and the other end of the parallel connection of the first capacitor C1 and the second capacitor C2 is connected to the rectifying circuit.

In a possible embodiment, the accelerating circuit is composed of 3 capacitors, and three capacitors may be connected in series with each other, or any two capacitors of the three capacitors may be connected in parallel and then connected in series with the remaining one capacitor, or any two capacitors of the three capacitors may be connected in series and then connected in parallel with the remaining one capacitor. As shown in fig. 7, the acceleration circuit includes a first capacitor C1, a second capacitor C2, and a fourth capacitor C4 connected in series with each other, one end of the first capacitor C1 is connected to the power supply, and one end of the fourth capacitor C4 is connected to the rectifier circuit. As shown in fig. 8, the second capacitor C2 and the fourth capacitor C4 are connected in parallel, the second capacitor C2 and the fourth capacitor C4 after being connected in parallel are connected in series with the first capacitor C1, one end of the first capacitor C1 is connected to a power supply, and one end of the second capacitor C2 and the fourth capacitor C4 after being connected in parallel are connected to a rectifying circuit. As shown in fig. 9, the first capacitor C1 and the second capacitor C2 are connected in series, and then the first capacitor C1 and the second capacitor C2 which are connected in series are connected in parallel with the fourth capacitor C4.

It should be noted that one or more capacitive devices may be included in the acceleration circuit, and the plurality of capacitive devices included in the acceleration circuit may be connected in series with each other, may also be connected in parallel with each other, or may be connected in series with the remaining capacitive devices after some of the capacitive devices are connected in parallel. Further, the capacitive device may be a capacitor or other capacitive device. The type, number and connection mode of the capacitive devices in the acceleration circuit are not limited in the embodiments of the present application.

In one possible embodiment, the surge detection circuit shown in fig. 4 is simulated. When the generated surge signal is a positive surge of a positive half wave, the simulation circuit is as shown in fig. 10. The obtained simulation result is shown in fig. 11, when the surge signal comes, the output voltage on the resistor R7 changes from 0V to 0.68V, the time is 2.89us, and the maximum voltage is 1.41V.

When the surge signal is a negative surge of a positive half wave, a simulation result is obtained as shown in fig. 12, the output voltage on the resistor R7 is changed from 0V to 0.7V, the time is 1.31us, and the maximum voltage value is 1.3V.

Similarly, in the case of a negative half-wave positive surge, the output voltage of the sampling circuit changes from 0V to 0.7V for 3.2us, and the maximum voltage value is 1.39V.

Under the negative surge condition of the negative half wave, the output voltage of the sampling circuit is changed from 0V to 0.77V, the time is 1.28us, and the maximum voltage value is 1.29V.

Therefore, the surge detection circuit provided by the invention can complete detection within us under all surge conditions, and parameters can be adjusted according to the actual surge conditions to enable the voltage output by the detection circuit to be within an acceptable range.

In the embodiment of the present application, there is also provided a surge detection device for active protection, the device includes a surge detection circuit, and the specific structure of the surge detection circuit refers to the above-mentioned embodiment. Further, since the surge detection device in the embodiment of the present application adopts all technical solutions of all embodiments of the surge detection circuit, all beneficial effects brought by the technical solutions of the embodiments of the surge protection circuit for active protection are at least achieved, and are not described in detail herein.

In an embodiment of the present application, there is also provided an electrical apparatus including a surge detection circuit, and the specific structure of the surge detection circuit refers to the above-described embodiment. Since the electrical equipment in the embodiment of the present application adopts all technical solutions of all embodiments of the above surge detection circuit, all beneficial effects brought by the technical solutions of the above surge protection circuit embodiment for active protection are at least achieved, and are not described in detail herein.

In one possible example, the electrical device may be a battery stove, a rice cooker, a television, or other household electrical devices, and is not limited herein.

Those skilled in the art will recognize that, in one or more of the examples described above, the functions described in this invention may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made on the basis of the technical solutions of the present invention should be included in the scope of the present invention.