Silicon Controlled Rectifier Failure Detection and Alarm Device, System and Testing Method

Abstract

The invention discloses a thyristor failure detection and alarm device, which includes a control circuit, a detection circuit electrically connected to the control circuit, and a normally closed switch circuit; the detection circuit is used for sampling the current value in the circuit and transmitting it to the control circuit; the control circuit is used for receiving and processing the current value transmitted by the detection circuit, obtaining the waveform state corresponding to the current value within a preset time, and sending a control signal to the normally closed switch circuit when it is confirmed that the thyristor is in a breakdown failure state according to the waveform state; the normally closed switch circuit is used for controlling the normally closed switch circuit to disconnect and cut off the circuit current after receiving the control signal of the control circuit. The invention effectively protects the safety of the circuit, prevents the negative impact brought by the short circuit and overcurrent of the thyristor, improves the work efficiency of personnel, and reduces the risk level of accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices, and particularly to a thyristor failure detection and alarm device, system, and test method. Background Art

[0002] In recent years, as the requirements for the EMC (lightning and surge immunity performance) of the whole machine have been continuously improved, it has become necessary to conduct corresponding lightning and surge immunity performance tests on thyristors, which are key electronic switching components. However, the original thyristors were not tested for any performance parameters in this regard, which means that the thyristors need to be tested for lightning and surge according to the national standard (GB / T 17626.5-1999) test conditions to understand the thyristors' ultimate lightning and surge resistance ability and provide reference for circuit designers.

[0003] However, the test schemes required in the current national standard are all for testing the whole machine, and there is no separate test scheme for thyristors. The current mainstream thyristor lightning and surge performance test scheme consists of a lightning and surge generator, a high-power load, and the thyristor to be tested. During the test, the tester needs to judge and handle various abnormal changes of the thyristor in a timely manner and perform corresponding operations when the thyristor is struck by lightning.

[0004] At the same time, the existing basic thyristor lightning and surge test scheme can only generate a lightning and surge signal through the lightning equipment and apply it to the thyristor. Specifically, during the process of testing the thyristor lightning performance, it does not have the function of thyristor failure detection and protection of the lightning equipment.

[0005] For the current basic test scheme, if you want to quickly understand whether the thyristor is damaged by lightning and surge, and do not affect the accuracy of the test results and protect the lightning equipment, only manual real-time monitoring can be adopted: that is, external detection equipment (such as an oscilloscope, a clamp ammeter, etc.) is connected, and the tester monitors the readings of the equipment in real time to judge whether the thyristor is misfired or damaged. And on the premise that the thyristor is damaged, the power supply of the lightning equipment is manually disconnected to prevent the equipment from being short-circuited and burning out the lightning equipment.

[0006] In addition, if the existing leakage protector is used for protection, due to the high sensitivity and weak lightning resistance of the leakage protector itself, as long as there is a misoperation of the thyristor or the test lightning voltage is too high, the leakage protector may trip and open the circuit, or even fail, and it cannot play an effective circuit protection and test function at all. Summary of the Invention

[0007] The present invention proposes a thyristor failure detection and alarm device, system, and test method for one or more of the above existing problems.

[0008] According to a first aspect of the present invention, a thyristor failure detection and alarm device is provided, including: a control circuit, a detection circuit electrically connected to the control circuit, and a normally closed switch circuit;

[0009] The detection circuit is configured to sample the current value in the circuit and transmit it to the control circuit;

[0010] The control circuit is configured to receive and process the current value transmitted by the detection circuit, obtain the waveform state corresponding to the current value within a preset time, and send a control signal to the normally closed switch circuit when it is confirmed according to the waveform state that the thyristor is in a breakdown failure state;

[0011] The normally closed switch circuit is electrically connected to the detection circuit and is configured to control the normally closed switch circuit to open and cut off the circuit current after receiving the control signal from the control circuit.

[0012] In some possible design modes, an alarm circuit and a power supply circuit are further included, and the power supply circuit is electrically connected to the control circuit and the alarm circuit. The alarm circuit is configured to give an alarm prompt after receiving the control signal from the control circuit.

[0013] In some possible design modes, a reset circuit is further included, and the reset circuit is electrically connected to the control circuit.

[0014] In some possible design modes, the alarm device further includes a first input terminal IN1 and a second input terminal IN2. The detection circuit uses a current transformer. The first input terminal IN1 is connected to the normally closed switch circuit through the magnetic ring of the current transformer, and the second input terminal IN2 is connected to the other end of the normally closed switch circuit.

[0015] In a second aspect, the present invention provides a thyristor failure detection and alarm system, including:

[0016] The above detection and alarm device, a lightning strike device, a thyristor to be measured, and a voltage control resistor R,

[0017] The lightning strike device is configured to provide a power supply signal with a frequency and amplitude in a sinusoidal alternating cycle to the detection and alarm device, and superimpose a combined wave of an analog lightning strike voltage and current with an adjustable amplitude on the power supply signal,

[0018] One end of the lightning strike device is electrically connected to the normally closed switch circuit in the detection and alarm device through the thyristor to be measured, and the other end of the lightning strike device is electrically connected to the input terminal of the detection and alarm device.

[0019] In some possible design modes, a load current limiting circuit is further included, and the load current limiting circuit is connected in series between the lightning strike device and the detection circuit in the detection and alarm device.

[0020] In some possible design methods, a voltage control resistor R is further included. The voltage control resistor R is connected in parallel across the control electrode and the cathode of the thyristor under test or across the control electrode and the first anode, and is used to ensure that the thyristor is in a normal and effective off state.

[0021] In a third aspect, the present invention provides a test method for a thyristor failure detection and alarm system. Using the above-mentioned thyristor failure detection and alarm system, the method includes the following steps:

[0022] Use a lightning strike device to output a valid AC power signal;

[0023] Use the lightning strike device to simulate and output a voltage wave for testing and superimpose it on the AC power signal, and apply it to the cathode and anode or the first anode and the second anode of the thyristor under test;

[0024] Obtain the current state flowing through the thyristor under test;

[0025] Control the on / off of the normally closed switch circuit according to the current state flowing through the thyristor under test and confirm whether to give an alarm prompt.

[0026] In some possible design methods, the detection and alarm device controls the on / off of the normally closed switch circuit according to the state of the thyristor under test and confirms whether to give an alarm prompt. Specifically, it includes:

[0027] When it is detected that the thyristor under test generates a corresponding induced current only when the corresponding lightning strike device conducts a lightning strike, and no current flows at other times, the normally closed switch circuit does not cut off the circuit and does not give an alarm prompt;

[0028] When it is detected that the thyristor under test is conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, but is turned off at the zero point of the next AC power signal, that is, the conduction time of the thyristor is less than the preset time, the normally closed switch circuit does not cut off the circuit and does not give an alarm prompt;

[0029] When it is detected that the thyristor under test is broken down and conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, and is in a continuously conducting state, and the conduction time is greater than the preset time, the control of the detection and alarm device disconnects the normally closed switch circuit and cuts off the circuit current.

[0030] The beneficial effects of the present invention are:

[0031] The thyristor failure detection and alarm device provided by the present invention converts a large short - circuit current into a tiny current through an isolated current transformer and sends it to the control circuit for identification. The control circuit receives and processes the current value transmitted by the detection circuit, and obtains the waveform state corresponding to the current value within a preset time. When it is confirmed that the thyristor is in a failed state of being broken down according to the waveform state, a control signal is sent to the normally - closed switch circuit. After receiving the control signal from the control circuit, the normally - closed switch circuit controls the disconnection of the normally - closed switch circuit, cuts off the circuit current and alarms. Thus, the safety of the circuit is effectively protected, the negative impacts caused by thyristor short - circuit over - current (such as secondary explosion of the already - failed thyristor caused by over - current, damage to lightning strike test equipment, etc.) are prevented, the work efficiency of personnel is improved, and the risk level of accidents is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the principle structure of the thyristor failure detection and alarm device;

[0033] Figure 2 It is a schematic diagram of the structure of the thyristor failure detection and alarm system;

[0034] Figure 3 It is a schematic diagram of the circuit of the thyristor failure detection and alarm device;

[0035] Figure 4 It is a flowchart of the test method of the thyristor failure detection and alarm system;

[0036] Figure 5 It is a schematic diagram of the current waveform of the thyristor under test in the test method of the thyristor failure detection and alarm system.

[0037] Through the above - mentioned drawings, the clear embodiments of the present disclosure have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present disclosure in any way, but to illustrate the concept of the present disclosure to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The technical solution of the application will be further described in detail below with reference to the drawings.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments may be combined with each other. For the same or similar concepts or processes, they may not be repeated in some embodiments.

[0042] Embodiment 1

[0043] Figure 1 FIG. is a schematic structural diagram of a thyristor failure detection and alarm device provided by an embodiment of the present invention; this embodiment provides a thyristor failure detection and alarm device, Figure 1 The normally closed switch in it refers to the normally closed switch circuit in this application, and the power supply refers to the power supply circuit in this application, including: a control circuit 1 and a detection circuit 2 and a normally closed switch circuit 3 electrically connected to the control circuit 1;

[0044] The detection circuit 2 is used to sample the current value in the circuit and transmit it to the control circuit 1;

[0045] The control circuit 1 is used to receive and process the current value transmitted by the detection circuit, obtain the waveform state corresponding to the current value within a preset time, and send a control signal to the normally closed switch circuit when it is confirmed according to the waveform state that the thyristor is in a failed state of being broken down;

[0046] The normally closed switch circuit 3 is electrically connected to the detection circuit and is used to disconnect the normally closed switch circuit and cut off the circuit current after receiving the control signal of the control circuit 1. By using the normally closed switch circuit, the circuit is normally in a normally closed state, and when receiving the action signal sent by the control circuit, the entire test circuit loop can be disconnected.

[0047] In some possible design manners, it further includes an alarm circuit 4, a power supply circuit 5 and a reset circuit 6. The alarm circuit 4 is configured to give an alarm prompt after receiving the control signal of the control circuit; the power supply circuit is electrically connected to the control circuit and the alarm circuit and is used for power supply; the reset circuit 5 is electrically connected to the control circuit 1 and the normally closed switch circuit 3 and is used to make the entire failure detection and alarm device work normally again after the failed thyristor under test is excluded. Specifically, the alarm circuit 4 is used to remind the tester in two forms of sound and light after the thyristor under test is broken down and short-circuited and conducted by a lightning strike signal.

[0048] Such as Figure 3As shown, the detection circuit 2 can adopt a current transformer TA, which is used for non-contact sampling of the current value flowing through the main circuit and providing it to the control circuit. A regulating resistor RZ is connected in parallel across both ends of the current transformer TA. The control circuit includes a rectifying circuit, a filtering circuit, a main control chip, and an AC optocoupler circuit. The rectifying circuit uses a rectifier bridge, and the filtering circuit uses a filtering capacitor C4. Both ends of the output side of the current transformer TA are connected as the AC input terminals to the AC input terminals of the rectifier bridge. The DC output terminal of the unidirectional pulsating voltage of the rectifier bridge is connected in parallel with the filtering capacitor C4. In this embodiment, the filtered detection signal is input into the main control chip U1, and compared with the internal preset value. When certain conditions are met, a control signal is output through the I / O port of the main control chip U1 to the base of R2 and the triode Q1. The collector of the triode Q1 is pulled up to the 5V power supply through the resistor R3, and the triode Q1 is in a saturated conduction state. As shown in the figure, the AC optocoupler circuit uses an AC optocoupling chip U2. The AC optocoupling chip U2 is supplied with power and an electrical signal to make the light-emitting diode emit light. Specifically, the light-emitting diode of the AC optocoupling chip U2 is used as the input terminal. One end of the light-emitting diode is connected to the emitter of the triode Q1, and the other end of the light-emitting diode is connected to GND. One end of the output terminal of the AC optocoupling chip U2 is connected to the anode or the second anode of the thyristor switch through the resistor R4, and the other end of the output terminal of the AC optocoupling chip U2 is connected to the control electrode of the thyristor switch. The cathode or the first anode of the thyristor switch is connected to the normally closed switch circuit. The AC optocoupling chip U2 can adopt the MOC3052 series or the MOC3062 series or a replacement chip with equivalent functions. Using the AC optocoupling chip U2 enables mutual isolation between the input and output circuits, and has advantages such as unidirectionality of electrical signal transmission. Therefore, the optocoupler has good anti-electromagnetic wave interference ability and electrical insulation ability, and is safer.

[0049] As Figure 3As shown in the figure, a schematic diagram of the power supply structure is provided. The power line N represents the neutral line, and L represents the live line. The power supply uses the most common full-bridge rectifier circuit plus a three-terminal voltage regulator for voltage stabilization. The L terminal, N terminal, and X terminal represented in different figures represent the same terminal information. The normally closed switch circuit uses a double-pole double-throw linked normally closed switch. One end of the relay coil KA of the normally closed switch is connected to the power line N, and the other end of the relay coil is connected to a thyristor switch. The alarm device also includes a first input terminal IN1 and a second input terminal IN2. IN1 is connected to the switch contact 2 after passing through the magnetic ring of the current transformer through a wire, IN2 is connected to the switch contact 6, the switch contact 6 is connected in a closed manner to the contact 2, and the switch contact 5 and the contact 1 are connected in a closed manner. The reset circuit uses a lighted touch normally closed switch, including a power indicator light and a reset switch. First, it realizes the function of power indication. Second, after pressing, the reset device allows the device to work normally again. In this embodiment, the output terminal of the contact 1 is electrically connected to the power indicator light of the reset circuit, the other end of the power indicator light is electrically connected to the power line N, one end of the normally closed switch of the reset circuit is electrically connected to the live line L, and one end of the normally closed switch is connected to the switch contact 5 and the thyristor switch Q2.

[0050] In the normal state, the power is turned on to make the circuit in the working state. The normally closed switch circuit is always in the normally closed state, that is, the switch contact 6 is connected in a closed manner to the contact 2, and the thyristor under test is in an effective off state. However, after the thyristor under test is broken down by the lightning test voltage, there is always current flowing between IN1 and IN2. After the current transformer TA detects the current signal, it is rectified and filtered and then given to the main control chip U1 for comparison and judgment. A signal is output to drive the triode Q1 to amplify the signal and then given to the AC optocoupler U2, prompting the switch thyristor Q2 to conduct, so that the coil of the relay KA is energized and the corresponding normally closed switch (switch contact 6 and contact 2) is disconnected, cutting off the main circuit current. At the same time, the corresponding normally open switch (switch contact 5 and contact 3) is closed, triggering the alarm circuit to be powered on and work, thus reminding the operator.

[0051] After removing the failed thyristor under test and replacing it with a new one, press the touch switch KM of the reset circuit, so that the normally closed switch of KM is instantaneously disconnected, making the voltage drop across the thyristor switch Q2 zero volts, automatically powering off the thyristor switch Q2, prompting the relay KA coil to power off, and automatically resetting the entire detection and alarm device, and a new round of testing can start again.

[0052] In this embodiment, the device converts a large short-circuit current into a tiny current through an isolated current transformer and sends it to the control circuit for identification. The control circuit receives and processes the current value transmitted by the detection circuit, obtains the waveform state corresponding to the current value within a preset time, and sends a control signal to the normally closed switch circuit when it confirms that the thyristor is in a failed state of being broken down. After receiving the control signal from the control circuit, the normally closed switch circuit controls the normally closed switch circuit to open, cutting off the circuit current and giving an alarm.

[0053] Thereby, the safety of the circuit is effectively protected, preventing negative impacts caused by thyristor short-circuit overcurrent (such as secondary explosion of a failed thyristor caused by overcurrent, damage to lightning strike test equipment, etc.), improving the work efficiency of personnel, and reducing the risk level of accidents.

[0054] Embodiment 2

[0055] As Figure 2 shown, the present invention provides a thyristor failure detection and alarm system. Figure 2 In it, A is the thyristor failure detection and alarm device provided in Embodiment 1. The system includes: the thyristor failure detection and alarm device of Embodiment 1, a lightning strike device, a thyristor under test, and a voltage control resistor R.

[0056] The lightning strike device is configured to provide a power supply signal with a sinusoidal alternating period of frequency and amplitude to the thyristor under test, and superimpose a combined wave of an analog lightning strike voltage and current with adjustable amplitude on the basis of the power supply signal.

[0057] One end of the lightning strike device is electrically connected to the normally closed switch circuit in the detection and alarm device through the thyristor under test, and the other end of the lightning strike device is electrically connected to the input end of the detection and alarm device. Among them, the thyristor under test can be any known thyristor, including but not limited to unidirectional thyristors, bidirectional thyristors, etc.

[0058] As Figure 2 shown, it further includes a load current limiting circuit, and the load current limiting circuit is connected in series between the lightning strike device and the detection circuit in the detection and alarm device.

[0059] As Figure 2 shown, it further includes a voltage control resistor R, and the voltage control resistor R is connected in parallel between the control electrode and the cathode of the thyristor under test or between the control electrode and the first anode, for ensuring that the thyristor is in a normal and effective off state.

[0060] The thyristor failure detection and alarm system provided by this embodiment uses the cooperative connection of a lightning strike device and a detection and alarm device, enabling the lightning strike device to provide a power supply signal with a frequency and amplitude in a sinusoidal alternating cycle to the detection and alarm device, as well as a combined wave superimposing an analog lightning strike current with an adjustable amplitude on the basis of this power supply signal. By measuring the current flowing through the thyristor under test, the detection and alarm device controls the on-off of the normally closed switch circuit. Thus, when it is determined that the thyristor fails due to short-circuit damage, the test circuit is immediately automatically cut off and an alarm is issued to prevent the negative impact brought by the thyristor short-circuit overcurrent.

[0061] Embodiment III

[0062] As Figure 4 shown, the present invention provides a test method for a thyristor failure detection and alarm system, including the following steps:

[0063] S100. Use a lightning strike device to output a valid AC power supply signal;

[0064] S200. Use the lightning strike device to simulate and output a voltage wave for testing and superimpose it on the AC power supply signal according to a preset angle, and apply it between the cathode and anode or the first anode and the second anode of the thyristor under test;

[0065] S300. Obtain the current state of the thyristor under test;

[0066] S400. The detection and alarm device controls the on-off of the normally closed switch circuit according to the current state of the thyristor under test and confirms whether to give an alarm prompt.

[0067] As shown in the figure, using the above-mentioned thyristor failure detection and alarm system, the step of the detection and alarm device controlling the on-off of the normally closed switch circuit according to the state of the thyristor under test and confirming whether to give an alarm prompt specifically includes:

[0068] It is detected that the thyristor under test generates a corresponding induced current only when the corresponding lightning strike device conducts a lightning strike, and no current flows at other times. The normally closed switch circuit does not cut off the circuit current and does not give an alarm prompt;

[0069] It is detected that the thyristor under test is conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, but is turned off at the zero point position of the next AC power supply signal, that is, the conduction time of the thyristor is less than the preset time. The normally closed switch circuit does not cut off the circuit current and does not give an alarm prompt;

[0070] It is detected that the thyristor under test is broken down and conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, and the conduction time is greater than the preset time. The control of the detection and alarm device disconnects the normally closed switch circuit and cuts off the circuit current.

[0071] As shown in the figure, under the test conditions of the national standard (GB / T 17626.5-1999), when the lightning strike equipment generates a voltage wave (Vmax) of a certain amplitude and superimposes it on the AC power supply signal, and applies it to both main poles of the thyristor under test, it is found that the thyristor will present three states: State 1, the thyristor under test does not act, and only a large lightning strike induced current will flow through the thyristor under test instantaneously; State 2, the thyristor misoperates and conducts until the AC power supply signal passes through zero and then turns off; State 3, the thyristor under test is broken down and conducts, and the current continues continuously.

[0072] For example, taking the lightning strike equipment to generate a 220V / 50Hz AC signal, and the frequency of the lightning strike surge signal is 1 time per minute, and each time is a positive lightning strike surge signal. In this embodiment, taking the 90° superimposed on the AC signal as an example, the working principle of the thyristor failure detection and alarm system in the three states of the thyristor under test is described.

[0073] As Figure 5 shown: Figure 5 It is the current waveform diagram flowing through the thyristor under test. Uin is the AC power supply waveform after superimposing the lightning strike voltage signal. lout1 is the waveform diagram of the lightning strike current wave in State 1. lout2 is the waveform diagram of the lightning strike current wave in State 2. lout3 is the waveform diagram of the lightning strike current wave in State 3.

[0074] State 1: When the lightning strike voltage appears at 90° of the AC signal, the thyristor under test is forced to conduct for an instant. At this time, a spike current with a peak value of Imax1 will flow through the thyristor. The magnitude of the current depends on the lightning strike voltage and the resistance value of the high-power load. The thyristor under test remains in the off state at other times, and the effective value of the current flowing through the thyristor is zero. The current transformer only detects this instantaneous current signal formed after the lightning strike and transmits it to the control circuit. The control circuit determines that this instantaneous current is a normal lightning strike induced current and is a normal phenomenon, and does not take any action. The alarm circuit remains in the standby state.

[0075] State 2: When the lightning strike voltage appears at 90° of the AC signal, the thyristor under test is forced to conduct for 5ms. After the thyristor under test starts from the appearance of the lightning strike signal until the current flowing through the thyristor under test is less than the holding current of the thyristor itself, it automatically turns off. At this time, a spike current with a peak value of Imax2 will flow through the thyristor under test. The peak value of the current depends on the lightning strike voltage and the high-power load resistance value. Except for the 5ms when the thyristor is forced to conduct and there is current flowing through the thyristor, the thyristor remains in the off state at other times, and the effective value of the current flowing through the thyristor is zero. The current transformer only detects that there is a current signal generated within 5ms after the lightning strike and transmits it to the control circuit. The control circuit determines that this current value is the normal misoperation current of the thyristor and is a normal phenomenon, and does not take any action. The alarm circuit remains in the standby state.

[0076] Status 3: When the lightning strike voltage appears at 90° of the AC signal, the thyristor under test is broken down by this lightning surge voltage, resulting in the failure of the thyristor under test. Therefore, the thyristor under test loses its most basic zero-crossing turn-off function and remains in a conducting state all the time, generating an effective current signal that varies with the AC signal. The magnitude of its effective current value depends on the AC voltage value and the resistance value of the high-power load. Its working duration far exceeds 5 ms. At this time, after the current transformer detects this AC effective current, it is transmitted to the control circuit. The control circuit determines that this current value is the short-circuit working current generated after the thyristor fails, which is an abnormal phenomenon. Immediately, a control signal is sent to the normally closed switch circuit to turn off the main circuit, and at the same time, a signal is sent to the alarm circuit for alarm prompt to notify the tester to eliminate the abnormal state.

[0077] Therefore, according to the model of the thyristor under test, the high-power load resistance value is selected. After the circuit is properly connected, the thyristor failure detection and alarm device is connected in series into the loop. After the device is powered on and the lightning strike signal output by the lightning strike device is set according to the test requirements, the waveform starts to be output. The current flowing through the loop is detected in real time by the current transformer. When the current in the circuit shows the first and second waveform states, the device does not act; only when the third state is detected, the control circuit acts, outputs a signal to disconnect the normally closed switch, and at the same time outputs a signal to the alarm circuit for alarm prompt to notify the tester that the thyristor of the measured component is broken down and conducted due to lightning surge.

[0078] In addition, by adjusting the amplitude of the lightning surge voltage, the lightning strike resistance ability of the thyristor under test can be effectively quantified.

[0079] The waveforms of the lightning strike signals mentioned in this application are all given according to the IEC61000-4-5 standard as shown in the figure. Among them, the AC signal generated by the lightning strike device, the frequency of the lightning strike signal, and the angle of each superposition can all be adjusted according to the actual test requirements, and are not limited to the above example values.

[0080] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

[0081] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the creative concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A test method for a thyristor failure detection and alarm system, characterized in that, Adopt a thyristor failure detection and alarm system, the thyristor failure detection and alarm system includes: a detection and alarm device, a lightning strike device, a thyristor to be measured, and a voltage control resistor R. The detection and alarm device includes: a control circuit (1), a detection circuit (2) electrically connected to the control circuit (1), and a normally closed switch circuit (3); The detection circuit (2) is used to sample the current value in the circuit and transmit it to the control circuit (1); The control circuit (1) is used to receive and process the current value transmitted by the detection circuit, obtain the waveform state corresponding to the current value within a preset time, and send a control signal to the normally closed switch circuit (3) when it is confirmed that the thyristor is in a breakdown failure state according to the waveform state; The normally closed switch circuit (3) is electrically connected to the detection circuit, and is used to disconnect the normally closed switch circuit and cut off the circuit current after receiving the control signal of the control circuit (1); The lightning strike device is configured to provide a power supply signal with a sinusoidal alternating cycle of frequency and amplitude to the thyristor to be measured, and superimpose a combined wave of an analog lightning strike voltage and current with adjustable amplitude on the power supply signal; One end of the lightning strike device is electrically connected to the normally closed switch circuit in the detection and alarm device through the thyristor to be measured, and the other end of the lightning strike device is electrically connected to the input end of the detection and alarm device; The test method includes the following steps: Use the lightning strike device to output an effective AC power supply signal; Use the lightning strike device to simulate and output a voltage wave for testing and superimpose it on the AC power supply signal, and apply it between the cathode and anode or the first anode and the second anode of the thyristor to be measured; Obtain the state of the current flowing through the thyristor to be measured; Control the on / off of the normally closed switch circuit according to the state of the current flowing through the thyristor to be measured and confirm whether to give an alarm prompt, specifically including: It is detected that the thyristor to be measured only generates a corresponding induced current when the corresponding lightning strike device conducts a lightning strike, and no current flows at other times. The normally closed switch circuit does not cut off the circuit and does not give an alarm prompt; It is detected that the thyristor to be measured is conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, but is turned off at the zero point position of the next AC power supply signal, that is, the conduction time of the thyristor is less than the preset time. The normally closed switch circuit does not cut off the circuit and does not give an alarm prompt; It is detected that the thyristor to be measured is broken down and conducted by the lightning strike voltage when the corresponding lightning strike device conducts a lightning strike, and the conduction time is greater than the preset time. The control of the detection and alarm device disconnects the normally closed switch circuit and cuts off the circuit current.

2. The test method of the thyristor failure detection and alarm system according to claim 1, characterized in that, The detection and alarm device further includes an alarm circuit (4) and a power supply circuit (5). The power supply circuit (5) is electrically connected to the control circuit (1) and the alarm circuit (4). The alarm circuit (4) is configured to give an alarm prompt after receiving the control signal of the control circuit (1).

3. The test method of the thyristor failure detection and alarm system according to claim 1, characterized in that, The detection and alarm device further includes a reset circuit (6), and the reset circuit (6) is electrically connected to the control circuit (1) and the normally closed switch circuit (3).

4. The test method of the thyristor failure detection and alarm system according to claim 1, characterized in that, The detection and alarm device further includes a first input terminal IN1 and a second input terminal IN2. The detection circuit (2) uses a current transformer. The first input terminal IN1 is connected to the normally closed switch circuit (3) through the magnetic core of the current transformer, and the second input terminal IN2 is connected to the other end of the normally closed switch circuit (3).

5. The test method of the thyristor failure detection and alarm system according to claim 1, characterized in that, It further includes a load current limiting circuit, and the load current limiting circuit is connected in series between the lightning strike device and the detection circuit in the detection and alarm device.

6. The test method of the thyristor failure detection and alarm system according to claim 4, characterized in that, It further includes a voltage control resistor R, and the voltage control resistor R is connected in parallel across the control electrode and the cathode of the thyristor to be measured or across the control electrode and the first anode, for ensuring that the thyristor is in a normal and effective off state.

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