Trigger circuit of plasma discharge switch

Abstract

The invention discloses a trigger circuit of a plasma discharge switch, the trigger circuit is used for triggering a plasma switch, the trigger circuit further comprises a low-voltage input end, a trigger signal end, an electronic switch, a coupling inductor and a one-way switch, the low-voltage input end is used for providing input voltage; the trigger signal end is used for sending out one or more pulse signals, the output end of the trigger signal end is connected with a control electrode of the electronic switch, the coupling inductor is formed by coupling a primary inductor and a secondary inductor, the two ends of the primary inductor are connected with the low-voltage input end and one connecting end of the electronic switch respectively, and the other connecting end of the electronic switch is grounded. The cathode of the plasma switch is grounded, the anode of the plasma switch is connected with the high-voltage circuit at the rear end, and the trigger electrode of the plasma switch is connected with the cathode of the one-way switch. The manufacturing process is simple, and miniaturization integration is easy; the circuit is simple, and the system complexity is greatly reduced; the system is high in reliability and strong in false triggering prevention capability.

Description

Technical Field

[0001] The invention relates to the technical field of electric switches, and in particular to a trigger circuit of a plasma discharge switch. Background Art

[0002] Plasma switch is a cold cathode high voltage switch device made by gas discharge principle, which is mainly designed to control the conduction of thousands of amperes of current energy in a short time. It has the advantages of wide voltage range, high working voltage, large switch current, high channel energy, small on-resistance, short delay time, convenient use and strong environmental adaptability. It is mainly used for fuses, engine ignition, high voltage pulse generators, lasers, trigger flash lamps, medical equipment extracorporeal shock wave lithotripsy, aircraft engine ignition and protection of high voltage equipment and components.

[0003] The plasma switch relies on a high-voltage trigger pulse with a certain amplitude (≥1500V) and width (≥100ns) to generate discharge, form a triggered plasma, connect the cathode and anode with bright, multiple, intermittent spark channels, and then the circuit is turned on. When the voltage between the two electrodes drops to a certain value, the discharge will no longer be maintained, and the plasma switch will return to the normal insulation state in a very short time, forming a complete trigger tube working cycle. The triggering process during the discharge conduction has an important influence on the performance of the plasma switch. At present, direct boost trigger technology is generally used to achieve a pulse voltage of more than 1500V.

[0004] The core of the direct boost trigger technology solution is to achieve boost through a transformer. The process is briefly described as follows: the low-voltage input stores energy in a capacitor, and the switch is instantaneously grounded to form an RLC oscillation pulse signal. The signal is directly boosted by the transformer to form the trigger voltage required for the plasma switch.

[0005] Direct boost trigger technology can be divided into single-stage boost and multi-stage boost. Single-stage boost uses a transformer to directly boost the low-voltage signal to the required high voltage, while multi-stage boost first boosts the low-voltage signal to an intermediate voltage, and finally uses a transformer to boost the intermediate voltage to the required high voltage.

[0006] This direct boost triggering technical solution has the following problems: 1. Single-stage boost technology requires a high turns ratio transformer, which is large and difficult to manufacture.

[0007] The single-stage boost technology circuit is simple, but requires a large transformer turns ratio. For example, when the low-voltage power supply is 15V, to achieve an output voltage of 1500V, the transformer primary-to-secondary turns ratio must be ≥100. Assuming that the primary winding is a 10-turn coil, the secondary winding needs to be ≥1000 turns. With so many windings, the transformer is complex to process and difficult to insulate. On the other hand, the transformer is large in size and high in height, and the electromagnetic properties such as leakage inductance and distributed capacitance are seriously deteriorated.

[0008] 2. Multi-stage boost technology requires an additional high-voltage power supply, and the system is complex.

[0009] Multi-stage boost technology can use a low turns ratio transformer, but it is necessary to first boost the low voltage power supply to an intermediate voltage of 300V~400V, and then use a switch to convert the DC high voltage into an AC pulse. Finally, the AC pulse is boosted by a 1:5 transformer to a pulse of ≥1500V to trigger the plasma discharge switch. The circuit for converting the front-stage low voltage to the intermediate voltage is relatively complex, requires more components, and the system reliability is difficult to guarantee.

[0010] 3. Direct boost trigger technology is difficult to meet the requirements of integration and miniaturization. The high turns ratio transformer of single-stage boost technology is the main bottleneck and difficulty of system integration, and the high voltage power supply required by multi-stage boost technology increases the difficulty of system integration. Summary of the invention

[0011] The purpose of the present invention is to provide a solution to the above-mentioned problem, which can avoid the use of a high turns ratio transformer and has the advantages of a simple single-stage boost technology circuit, so as to achieve miniaturization and integration of plasma discharge switch components and provide a triggering method for a plasma discharge switch.

[0012] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: a trigger circuit of a plasma discharge switch, used for triggering a plasma switch, the plasma switch comprises a trigger electrode, a cathode and an anode, and also comprises a low voltage input terminal, a trigger signal terminal, an electronic switch, a coupling inductor and a unidirectional switch, wherein the electronic switch comprises a control electrode and two connection terminals, and the unidirectional switch comprises an anode and a cathode; The low voltage input terminal is used to provide an input voltage of 8V~50V; The trigger signal terminal is used to send out a single or multiple pulse signals, and its output terminal is connected to the control electrode of the electronic switch, and is used to control the electronic switch to be turned on or off through high and low levels; The coupling inductor is formed by coupling the primary inductor and the secondary inductor, wherein the two ends of the primary inductor are respectively connected to the low voltage input end and one connection end of the electronic switch, the other connection end of the electronic switch is grounded, the two ends of the secondary inductor are respectively connected to the anode of the unidirectional switch and the cathode of the plasma switch, the cathode of the plasma switch is grounded, the anode is connected to the high voltage circuit at the rear end, the trigger pole is connected to the cathode of the unidirectional switch, and the maximum trigger pole voltage Vc According to the following formula: , Where k is the transmission coefficient, 0.3≤k≤0.5, L p is the inductance of the primary inductor, C r is the equivalent capacitance of the plasma switch trigger electrode, V i is the input voltage, d t It is the high level duration of the pulse signal.

[0013] Preferably, the electronic switch is provided with a switch protection circuit for preventing the electronic switch from being broken down by overvoltage.

[0014] Preferably, the switch protection circuit is a transient suppression diode, an absorption loop composed of a resistor and a capacitor, or a clamping circuit composed of a resistor, a capacitor and a diode.

[0015] Preferably, the trigger signal is a TTL level or a CMOS level, the high level of the trigger signal is 5V, the low level is 0V, the pulse width is 3μs to 6μs, the electronic switch is turned on when the level is high, and the electronic switch is turned off when the level is low.

[0016] Preferably, the coupled inductor is manufactured by low temperature co-fired ferrite process, and the turns ratio of the primary inductor to the secondary inductor is greater than or equal to 1:4.

[0017] Preferably, the plasma switch is a gas discharge tube.

[0018] Preferably, the electronic switch is a MOSFET, a thyristor, a triode or an IGBT.

[0019] Preferably, the unidirectional switch is a high-voltage fast recovery diode or a SiC high-voltage diode with a withstand voltage of ≥5kV.

[0020] In the present invention, the coupled inductor can be a low-temperature co-fired ferrite inductor. This magnetic device has a small size, low height, high reliability, and meets the system integration requirements. It can also be a conventional structure magnetic device, which is mainly composed of enameled wire windings and a magnetic core. It is generally larger in size and higher in height, and is suitable for non-system integration applications.

[0021] The control relationship and function of each switch in the present invention are as follows: (1) When the pulse signal in the trigger signal end is at a high level, the electronic switch is turned on, and when it is at a low level, the electronic switch is turned off. (2) The electronic switch and the unidirectional switch are respectively located at the two ends of the coupled inductor. Due to the connection relationship between the same-name ends of the coupled inductor, when the electronic switch is turned on, the unidirectional switch is blocked by the reverse voltage, the subsequent circuit of the unidirectional switch is disconnected, and the coupled inductor enters the energy storage state. When the electronic switch is turned off, the unidirectional switch is turned on in the forward direction, the subsequent circuit is connected, and the coupled inductor enters the energy transmission state. (3) The equivalent capacitance of the trigger electrode of the plasma switch is very small, generally less than or equal to 15pF. When the unidirectional switch is turned on in the forward direction, the trigger electrode voltage will rise rapidly and can reach thousands of volts in a very short time. When the trigger electrode voltage reaches the turn-on voltage of the plasma switch, the plasma switch is turned on.

[0022] The working principle of the present invention is: When the pulse signal at the trigger signal end is at a high level, the electronic switch is turned on and the one-way switch is turned off. The energy at the low-voltage input end is stored in the coupled inductor. There is no voltage input to the trigger pole of the plasma switch, and the plasma switch is turned off. When the pulse signal is at a low level, the electronic switch is turned off and the one-way switch is turned on. The energy stored in the coupled inductor is transmitted to the trigger pole of the plasma switch. The voltage of the trigger pole of the plasma switch rises rapidly to the turn-on voltage, and the plasma switch is turned on.

[0023] Compared with the prior art, the advantages of the present invention are: (1) The transformer manufacturing process is simple and easy to miniaturize and integrate: The present invention is based on a low-turn ratio coupled inductor. Compared with a high-turn ratio transformer, the volume and height are greatly reduced (the volume and height are reduced to a few to several tenths), which is conducive to achieving better electromagnetic performance.

[0024] (2) The circuit is simple and the system complexity is greatly reduced: The circuit elements required by the present invention are equivalent to those of the single-stage boost technology, and a low voltage (8V-50V) input can be directly boosted to a high voltage (≥2000V) without the need for a high voltage power supply in the multi-stage boost technology.

[0025] (3) High system reliability and strong anti-false triggering capability: Generally speaking, interference signals are prone to appear in high-voltage systems. These signals generally have a pulse width of hundreds of nanoseconds. Direct boost triggering technology uses small signals to control electronic switches. When stimulated by interference signals, false triggering may occur. However, the present invention needs to maintain a wider pulse (greater than several microseconds) to output the required high voltage. Even if stimulated by interference signals, the system output voltage is difficult to reach 1500V. Therefore, the present invention has a high anti-interference capability.

[0026] In summary, the present invention can realize integration and miniaturization for the trigger circuit of the plasma switch, and has great practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the principle of the present invention; Figure 2 1 is a circuit diagram of Embodiment 1 of the present invention; Figure 3 This is a circuit diagram of Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Example 1: See Figure 1 , a trigger circuit of a plasma discharge switch, used for triggering a plasma switch, the plasma switch comprising a trigger electrode, a cathode and an anode, and also comprising a low voltage input terminal, a trigger signal terminal, an electronic switch, a coupling inductor and a unidirectional switch, wherein the electronic switch comprises a control electrode and two connection terminals, and the unidirectional switch comprises an anode and a cathode; The low voltage input terminal is used to provide an input voltage of 8V~50V; The trigger signal terminal is used to send out a single or multiple pulse signals, and its output terminal is connected to the control electrode of the electronic switch, and is used to control the electronic switch to be turned on or off through high and low levels; The coupling inductor is formed by coupling the primary inductor and the secondary inductor, wherein the two ends of the primary inductor are respectively connected to the low voltage input end and one connection end of the electronic switch, the other connection end of the electronic switch is grounded, the two ends of the secondary inductor are respectively connected to the anode of the unidirectional switch and the cathode of the plasma switch, the cathode of the plasma switch is grounded, the anode is connected to the high voltage circuit at the rear end, the trigger pole is connected to the cathode of the unidirectional switch, and the maximum trigger pole voltage V c According to the following formula: , Where k is the transmission coefficient, 0.3≤k≤0.5, L p is the inductance of the primary inductor, C r is the equivalent capacitance of the plasma switch trigger electrode, V i is the input voltage, d t It is the high level duration of the pulse signal.

[0030] The electronic switch is provided with a switch protection circuit for preventing it from being broken down by overvoltage. The switch protection circuit is a transient suppression diode, an absorption circuit composed of a resistor and a capacitor, or a clamping circuit composed of a resistor, a capacitor and a diode. The trigger signal is a TTL level or a CMOS level, the high level of the trigger signal is 5V, the low level is 0V, the pulse width is 3μs~6μs, the electronic switch is turned on at a high level, and the electronic switch is turned off at a low level. The coupled inductor is made of low-temperature co-fired ferrite technology, and the turns ratio of the primary inductor and the secondary inductor is greater than or equal to 1:4. The plasma switch is a gas discharge tube. The electronic switch is a MOSFET, a thyristor, a triode or an IGBT. The unidirectional switch is a high-voltage fast recovery diode or a SiC high-voltage diode with a withstand voltage of ≥5kV. The present invention obtains a suitable output voltage by designing a coupled inductor, and when the output voltage reaches the trigger voltage threshold, the on and off of the plasma switch can be controlled.

[0031] Example 2: See Figure 2 , based on Example 1, a specific trigger circuit of a plasma discharge switch is given.

[0032] In the present invention, the low voltage input terminal includes Vin and a capacitor C1, Vin is a 15V DC power supply, and the capacitor capacity is ≥4.7μF; The trigger signal terminal sends out a single pulse signal, the signal high level is 5V, the low level is 0V, and the pulse width is 6μs; The electronic switch Q2 is a high-voltage MOSFET tube with a withstand voltage of 400V. A switch protection circuit is provided at the electronic switch Q2. In this embodiment, the switch protection circuit is a TVS tube D2 with a clamping voltage of 300V.

[0033] The coupled inductor T1 is realized by low temperature co-fired ferrite process, with a volume of 12mm×12mm×3mm, a turns ratio of 1:16, and a primary inductance of 20μH; The unidirectional switch D1 is a high-voltage fast recovery diode with a withstand voltage of 5kV; The plasma switch Q1 is a gas discharge tube with a minimum trigger voltage of 1500V and a trigger inter-electrode capacitance of about 10pF. Figure 2 In the figure, CB1 is the load, which is usually an impact piece detonator.

[0034] When the transmission coefficient is considered to be 0.3, according to V c Formula, maximum trigger voltage V c It is 3485V. When the trigger voltage reaches 1500V, the trigger pole is turned on and the trigger voltage is clamped at 1500V, thereby realizing the switch control of the gas pipe.

[0035] It can be seen that the turns ratio of the coupled inductor used in this circuit is much smaller than that of the direct boost technology, and the volume is reduced by more than 80%. In addition, diodes, mosFETs, etc. can all be packaged in miniaturized form, thus achieving miniaturization and integration.

[0036] Example 3: See Figure 3 Based on Example 1, another specific trigger circuit of a plasma discharge switch is given.

[0037] In the present invention, the low voltage input terminal includes Vin and a capacitor C1, Vin is a 28V DC power supply, and the capacitor capacity is ≥10μF; The trigger signal terminal sends out a single pulse signal, the signal high level is 5V, the low level is 0V, and the pulse width is 3μs; The electronic switch Q2 is a high-voltage thyristor with a withstand voltage of 650V. A switch protection circuit is provided at the electronic switch Q2. In this embodiment, the protection circuit uses a high-voltage capacitor C2 with a capacity of 1500pF. When the electronic switch Q2 is turned off, the high-voltage capacitor C2 prevents the voltage from rising rapidly and reduces the maximum voltage amplitude, thereby protecting Q2 from breakdown.

[0038] The coupled inductor T1 is realized by low temperature co-fired ferrite process, with a size of 8mm×10mm×2.4mm, a turns ratio of 1:8, and a primary inductance of 20μH.

[0039] The unidirectional switch D1 is a high-voltage fast recovery diode with a withstand voltage of 5kV; The plasma switch Q1 is a gas discharge tube with a minimum trigger voltage of 1500V and a trigger inter-electrode capacitance of about 10pF. Figure 3 In the figure, CB1 is the load, which is usually an impact piece detonator.

[0040] When the transmission coefficient is considered to be 0.3, according to V c Formula, maximum trigger voltage V c It is 3253V. When the trigger voltage reaches 1500V, the trigger pole is turned on and the trigger voltage is clamped at 1500V, thereby realizing the switch control of the gas pipe.

[0041] It can be seen that the coupled inductor turns ratio (1:8) used in this circuit is much smaller than that of the direct boost technology (1:100), and the volume is greatly reduced, which is conducive to miniaturization and integration.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A trigger circuit for a plasma discharge switch, used for triggering a plasma switch, wherein the plasma switch comprises a trigger electrode, a cathode and an anode, and is characterized in that: It also includes a low voltage input terminal, a trigger signal terminal, an electronic switch, a coupled inductor and a unidirectional switch, wherein the electronic switch includes a control electrode and two connection terminals, and the unidirectional switch includes an anode and a cathode; The low voltage input terminal is used to provide an input voltage of 8V~50V; The trigger signal terminal is used to send out a single or multiple pulse signals, and its output terminal is connected to the control electrode of the electronic switch, and is used to control the electronic switch to be turned on or off through high and low levels; The coupling inductor is formed by coupling the primary inductor and the secondary inductor, wherein the two ends of the primary inductor are respectively connected to the low voltage input end and one connection end of the electronic switch, the other connection end of the electronic switch is grounded, the two ends of the secondary inductor are respectively connected to the anode of the unidirectional switch and the cathode of the plasma switch, the cathode of the plasma switch is grounded, the anode is connected to the high voltage circuit at the rear end, the trigger pole is connected to the cathode of the unidirectional switch, and the maximum trigger pole voltage V c According to the following formula: ， Where k is the transmission coefficient, 0.3≤k≤0.5, L p is the inductance of the primary inductor, C r is the equivalent capacitance of the plasma switch trigger electrode, V i is the input voltage, d t It is the high level duration of the pulse signal.

2. A trigger circuit for a plasma discharge switch according to claim 1, characterized in that: The electronic switch is provided with a switch protection circuit for preventing the electronic switch from being broken down by overvoltage.

3. A trigger circuit for a plasma discharge switch according to claim 2, characterized in that: The switch protection circuit is an absorption loop composed of a transient suppression diode, a resistor and a capacitor, or a clamping circuit composed of a resistor, a capacitor and a diode.

4. The trigger circuit of a plasma discharge switch according to claim 1, characterized in that: The trigger signal is a TTL level or a CMOS level, the high level of the trigger signal is 5V, the low level is 0V, the pulse width is 3μs~6μs, the electronic switch is turned on when the high level is high, and the electronic switch is turned off when the low level is low.

5. The trigger circuit of a plasma discharge switch according to claim 1, characterized in that: The coupled inductor is manufactured by low temperature co-fired ferrite process, and the turns ratio of the primary inductor and the secondary inductor is greater than or equal to 1:

4.

6. The trigger circuit of a plasma discharge switch according to claim 1, characterized in that: The plasma switch is a gas discharge tube.

7. The trigger circuit of a plasma discharge switch according to claim 1, characterized in that: The electronic switch is a MOSFET, a thyristor, a triode or an IGBT.

8. The trigger circuit of a plasma discharge switch according to claim 1, characterized in that: The one-way switch is a high-voltage fast recovery diode or a SiC high-voltage diode with a withstand voltage of ≥5kV.

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