CN108005869A - An Ignition Circuit for Semiconductor Spark Plug of Miniature Pulse Plasma Thruster - Google Patents

Abstract

Aiming at the technical problems of optimizing the quality and the volume of an ignition system, improving the electrical efficiency and the time control precision of the ignition system, reducing the heating and the thermal stress of a semiconductor spark plug and the like, the invention designs an ignition circuit aiming at a micro pulse plasma thruster ignited by the semiconductor spark plug on the basis of not increasing the complexity of an external circuit and not changing the basic configuration of the spark plug, and designs the installation and fixing modes of a central anode of the semiconductor spark plug.

Description

An Ignition Circuit for Semiconductor Spark Plug of Miniature Pulse Plasma Thruster

technical field

The invention relates to a semiconductor spark plug and its ignition system, which is especially suitable for inducing the main discharge of a micro-pulse plasma thruster to generate thrust.

Background technique

At present, the development of satellite system networking and miniaturization has put forward extensive demands on micro electric propulsion. Micro-Pulsed Plasma Thruster (μPPT) is a kind of Pulsed Plasma Thruster (PPT), which uses capacitor pulse discharge to generate electromagnetic field, working fluid ablation and ionization to generate plasma, and then accelerates through electromagnetic force plasma to generate thrust. Usually, a PPT with a system mass of less than 1kg is called μPPT, and the quality, volume and power consumption of μPPT are at least one order of magnitude lower than that of PPT. According to the physical state of the working fluid, μPPT can be divided into μPPT using gas working fluid, using liquid working fluid and μPPT using solid working fluid. Compared with μPPT using gas working fluid and using liquid working fluid, μPPT using solid working fluid The propellant supply and the thruster body are combined into one module, which saves the complicated propellant storage system and supply system, and avoids the limitation of valve life and the problem of working medium leakage. In addition to the traditional PPT thrust density, specific impulse In addition to the advantages of high thrust, small and precise thrust, high control precision, simple structure, and high reliability, it also has the advantages of low power consumption, low cost, light weight, and small size. It is very suitable for space applications and high-precision execution of micro-nano satellites. controlled propulsion tasks.

The ignition system is one of the key components of μPPT, which directly determines the success or failure of μPPT ignition, and also directly affects the quality and performance of the entire thruster. For the μPPT with parallel plate configuration using solid working fluid, the main discharge of the thruster is generally induced by an external excitation discharge method: the spark plug is controlled by a separate ignition circuit, and the main discharge is discharged by a capacitor energy storage. The ignition voltage of the spark plug is generally low, Semiconductor spark plug with better ignition stability. Under the control of the ignition system, the semiconductor spark plug ignites, induces the main discharge and generates an arc, and ablates, ionizes and accelerates the working fluid to generate thrust. This μPPT ignition circuit has the advantages of high control precision, good reliability, simple structure, and low cost, but there are also some problems:

A separate ignition circuit is required, which increases the mass, volume and complexity of the system to a certain extent.

There is a large thermal stress in the semiconductor spark plug, so that the life of the propulsion system is limited by the life of the spark plug. Continuous long-term discharge of semiconductor spark plugs in a vacuum will generate temperature accumulation, resulting in an increase in the temperature of the spark plugs. In addition, the large temperature difference between day and night in the space environment (up to 300 ° C), resulting in the widespread phenomenon of thermal expansion and contraction of spark plugs, resulting in large thermal stress. It may lead to partial discharge or non-standard discharge, which intensifies the ablation, corrosion and failure of the spark plug to a certain extent.

The use of semiconductor spark plugs will affect the electrical efficiency of conventional ignition systems and the charging time of capacitors. When the ignition circuit is not working, the cathode and the center electrode of the traditional metal spark plug are completely isolated, and the circuit is equivalent to an open circuit; while the semiconductor spark plug will conduct the circuit, consume a certain amount of electric energy and generate heat (its own internal resistance Equivalent to a static equivalent resistance), at the same time, the static equivalent resistance is equivalent to a parallel connection with the charging resistance, which will affect the charging time of the capacitor, thereby affecting the control accuracy.

Contents of the invention

Based on this, the present invention is to overcome the defects of the prior art and provide a semiconductor spark plug and its ignition system, aiming at optimizing the quality and volume of the ignition system, improving the electrical efficiency and time control accuracy of the ignition system, reducing the heat generation and thermal stress of the semiconductor spark plug, etc. Technical problem, on the basis of not increasing the complexity of the external circuit, a semiconductor spark plug and an ignition circuit for the semiconductor spark plug are designed.

A kind of semiconductor spark plug, used for micro-pulse plasma thruster, the spark plug is a gap spark plug, including a central anode, a grounded shell, an insulator and a semiconductor coating; the central anode and the grounded shell are respectively insulated and isolated by an insulating ceramic component and a semiconductor Coating discharge; the lower end of the insulating ceramic is sealed with a ring-shaped, chip-type semiconductor ring; the upper end of the central anode of the spark plug is a connecting bolt, which is connected to the positive electrode of the ignition circuit power supply through the bolt, and the lower end of the grounding cathode of the spark plug is a bolt, which is connected to the cathode plate of the thruster through the bolt connected to form a loop;

On the ignition end face, a ring-shaped, sheet-type semiconductor coating is installed between the central anode and the outer cathode, and a certain assembly gap L is left between the central anode and the semiconductor coating, so that the central anode can slide axially; assembly The gap L is determined with reference to the circumferential expansion ΔR=αRΔT, where α is the coefficient of thermal expansion, R is the diameter of the central anode, and ΔT is the change in temperature;

In the non-semiconductor coating area, there is an assembly gap L1 between the central anode and the insulating ceramic.

In one embodiment, the insulator is an insulating ceramic, and the lower end surface of the insulating ceramic is sealed with a ring-shaped, chip-type semiconductor ring.

The present invention also provides a kind of ignition system of semiconductor spark plug, comprises above-mentioned semiconductor spark plug, also comprises power supply unit, ignition starting unit; (C4), the first main energy storage capacitor (C1), the second main energy storage capacitor (C2), and the third main energy storage capacitor (C3); The energy of the first main energy storage capacitor (C1), the second main energy storage capacitor (C2) and the third main energy storage capacitor (C3) is instantly released to the spark plug. Spark plugs are used to generate charged particles.

In one of the embodiments, the power supply unit includes an on-board power supply (V) and a transformer (T1); wherein, the on-board power supply (V) is connected in series with the primary coil of the transformer (T1), and the transformer (T1) converts the on-board DC The power supply (V) is boosted, and the secondary coil of the transformer (T1) is used as the main power supply to the subsequent stage.

In one of the embodiments, the ignition start unit includes a breakdown trigger capacitor (C4), a first main energy storage capacitor (C1), a second main energy storage capacitor (C2), a third main energy storage capacitor (C3) , isolation coupling capacitor (C5), voltage divider resistor (R1), first diode (D1), second diode (D2) and third diode (D3), first switch (K1) and second Two switch (K2), switching transistor (IGBT), +5V ignition power supply, ignition frequency controller (N); wherein, the trigger circuit is composed of +5V ignition power supply and ignition frequency controller (N) in series; the secondary transformer (T2 )’s secondary coil is connected in series with the isolation coupling capacitor (C5) and then connected in series with the second diode (D2); the first diode (D1) is connected in parallel with the primary coil of the secondary transformer (T2) and connected with the third diode The tube (D3) and the switching transistor (IGBT) are connected in series, and then connected in parallel with the breakdown trigger capacitor (C4), and then connected in series with the voltage dividing resistor (R1) to form branch one; the first main energy storage capacitor (C1 ), the second main energy storage capacitor (C2), and the third main energy storage capacitor (C3) are connected in parallel to form branch two; the secondary coil of the secondary transformer (T2) is connected in series with the isolation coupling capacitor (C5) and then connected to the spark plug (M) Parallel, and then connected in parallel with the second diode (D2) in series to form branch three; branch one, branch two, and branch three in parallel, and then connected in parallel with the secondary coil of the transformer (T1) in series .

The invention improves the structure of the spark plug, which can reduce the thermal stress of the semiconductor spark plug due to the wide range of temperature changes, and is beneficial to the improvement of the life of the spark plug;

The pulse transformer is used to realize the mutual isolation between high voltage and low voltage, which reduces the impact on the star-loaded voltage; the pulse high voltage discharge is triggered through the trigger signal interface to trigger ignition, and the ignition can be ignited and manually ignited through a separate control system, and the ignition frequency can be controlled. Accurate; multiple main energy storage capacitors are used in parallel, the number of energy storage capacitors is controlled by the switch knife, the ignition energy is adjusted independently, and the breakdown capacitor is independent from the ignition main capacitor, which improves the energy utilization rate; and for the semiconductor spark plug The working characteristics introduce an isolation diode, which can prevent the semiconductor spark plug from consuming energy and heating due to its inability to isolate itself (it has an equivalent static resistance) when the ignition circuit is on standby;

The invention has the advantages of simple structure, light weight and small volume of components and the ignition system composed of them, and can adapt to the strict quality and space requirements of μPPT.

Description of drawings

Figure 1 is a schematic diagram of the front view of the semiconductor spark plug;

Fig. 2 is a schematic diagram of the structure of the semiconductor spark plug viewed from above;

Fig. 3 is a schematic diagram of a cross-sectional structure of a semiconductor spark plug;

Fig. 4 is a schematic diagram of the structure of the central anode of the semiconductor spark plug;

Fig. 5 is a schematic circuit diagram of the circuit of the present invention.

1—outer cathode,

2—insulating ceramics,

3—semiconductor ring,

4—central anode,

5—the matching gap between the central anode and the insulating ceramic,

6—the fit gap between the central anode and the semiconductor ring,

7—connection nut,

8—connecting thread,

Onboard 28V—onboard power supply is 28V,

T1—primary transformer,

K1/K2—main capacitor switch,

C1/C2/C3—main energy storage capacitor,

R1—voltage divider resistor,

IGBT—transistor,

D1/D2/D3—diodes,

T2—secondary transformer,

C5—discharge breakdown capacitor,

M—spark plug.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific embodiments described here are only used to explain the present invention, and do not limit the protection scope of the present invention.

It should be noted that when an element is referred to as being “fixed on”, “disposed on” or “installed on” another element, it may be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intervening element at the same time; the specific way that one element is fixedly connected to another element can be realized through existing technologies, and will not be discussed here. To repeat it again, it is preferable to adopt a fixing method of threaded connection.

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 of the invention. The terminology used herein in the description of the present invention is only for the purpose of describing specific embodiments, and is not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The "first" and "second" mentioned in the present invention do not represent specific numbers and sequences, but are only used to distinguish names.

The invention provides a semiconductor spark plug, the inside of which is equivalent to a solid insulated metal transmission line, the ground shell and the central anode are coaxially arranged in parallel, ceramic materials are used as the insulating medium between the two electrodes, and the central anode is connected to the insulating material and the semiconductor coating. There are gaps between them, which can eliminate and absorb the expansion and contraction of the central anode, semiconductor coating and insulator to a certain extent, realize the flexible interaction between the three, and achieve the purpose of reducing the internal thermal stress of the semiconductor spark plug.

As shown in Figure 1, it is a schematic diagram of the front view structure of a semiconductor spark plug. Its main structure includes: a central anode, a grounded cathode, an insulator and a semiconductive coating; the central anode and the outer cathode are respectively insulated and isolated by insulating ceramic components and discharged by the semiconductive coating. . The lower end of the insulating ceramic is sealed with a ring-shaped, chip-type semiconductor ring; the upper end of the central anode of the spark plug is a wiring bolt, which is connected to the positive electrode of the ignition circuit power supply through the bolt, and the lower end of the ground cathode of the spark plug is a bolt, which is connected to the cathode plate of the thruster through the bolt to form a circuit .

Figure 2 is a schematic view of the structure of the gap-type semiconductor spark plug. A certain assembly gap, the assembly gap L is determined by referring to the size of the circumferential expansion ΔR=αRΔT, where α is the coefficient of thermal expansion, R is the diameter of the central anode, and ΔT is the amount of temperature change.

Figure 3 is a schematic cross-sectional structure diagram of a semiconductor spark plug, the structure of which is: in the non-semiconductor coating area, an assembly gap L1 is left between the central anode and the insulating ceramic, and in the semiconductor coating area, between the central anode and the semiconductor coating There is a certain assembly gap L2, so that the central anode can slide axially, and the axial position of the central anode during installation is determined by the notch on the ignition end face and the nut on the terminal end.

Figure 4 is a schematic diagram of the central anode structure of the gap-type semiconductor spark plug. The structure is: the central anode is cylindrical, and the diameter of the ignition end is slightly larger, which acts as a position limiter.

The present invention also provides an ignition system for a semiconductor spark plug, as shown in FIG. 5 , mainly composed of a power supply unit, an ignition starting unit and a spark plug (M), as shown in FIG. 1 .

The power supply unit is used to convert the low-voltage DC power supply (V) on the satellite into high-voltage pulses and charge the breakdown trigger capacitor (C4) and main energy storage capacitors (C1, C2, C3).

The ignition start unit is used to instantly release the energy of the capacitors (C1, C2, C3, C4) to the spark plug (M).

The spark plug (M) is used to generate charged particles.

The power supply unit includes an on-board power supply (V) and a transformer (T1); wherein, the on-board power supply (V) is connected in series with the primary coil of the transformer (T1), and the transformer (T1) boosts the on-board DC power supply (V) , the secondary coil of the transformer (T1) is used as the main power supply to the subsequent stage.

The ignition starting unit includes a breakdown trigger capacitor (C4), a main energy storage capacitor (C1, C2, C3) and an isolation coupling capacitor (C5), a voltage dividing resistor (R1), diodes (D1), (D2) and ( D3), switch (K1) and (K2), switching transistor (IGBT), +5V ignition power supply, ignition frequency controller (N); wherein, the trigger circuit is composed of +5V ignition power supply and ignition frequency controller (N) in series ; The secondary coil of the secondary transformer (T2) is connected in series with the isolation coupling capacitor (C5) and then connected in series with the diode (D2); the diode (D1) is connected in parallel with the primary coil of the secondary transformer (T2) and connected with the diode (D3), the switch Transistors (IGBT) are connected in series, and then connected in parallel with the breakdown trigger capacitor (C4), and then connected in series with the voltage dividing resistor (R1) to form branch one; main energy storage capacitors (C1), (C2), (C3 ) in parallel to form branch two; the secondary coil of the secondary transformer (T2) is connected in series with the isolation coupling capacitor (C5) and then connected in parallel with the spark plug (M), and then connected in parallel with the diode (D2) in series to form branch three; The first branch, the second branch and the third branch are connected in parallel, and then connected in series with the secondary coil of the transformer (T1).

Described spark plug (M) is gap type semiconductor spark plug, and it comprises central anode, ground cathode, insulator and semiconductor coating; Wherein, the secondary coil of isolation coupling capacitor (C5), secondary transformer (T2) is connected in series with spark plug (M) in parallel.

The ignition circuit converts the low-voltage direct current (V) on the satellite into a high-voltage pulse and charges the breakdown trigger capacitor (C4) and the main energy storage capacitor (C1, C2, C3). When the switching transistor (IGBT) receives the ignition trigger signal , the breakdown trigger capacitor (C4) forms a discharge circuit with the switching transistor (IGBT), diode (D3), and the primary coil of the secondary transformer (T2), and passes the energy stored by itself through the secondary coil of the secondary transformer (T2) Released to the spark plug to make it break down and discharge. After the spark plug breaks down, the main energy storage capacitor (C1, C2, C3) forms a discharge circuit with the diode (D2), switch tube (IGBT) and spark plug, and the isolation coupling capacitor (C5) Under the action of isolation coupling, the main energy storage capacitors (C1, C2, C3) instantly release the energy stored by themselves to the spark plug, so as to realize the ignition of the spark plug. The energy of the main energy storage capacitors (C1, C2, C3) does not need to pass through the secondary coil of the secondary transformer (T2), which improves the utilization rate of energy; an isolation diode (D3) is introduced in the circuit to prevent ignition circuit standby When the semiconductor spark plug cannot be isolated independently (it has an equivalent static resistance), it will consume energy and generate heat, and at the same time improve the control accuracy; the number of main capacitors participating in the discharge in the circuit can be controlled by the switch (K1, K2) to achieve The ignition energy is adjustable.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (5)

1. a kind of semiconductor spark plug, for miniature pulsed plasma thruster, it is characterised in that the spark plug is intermittence Spark plug, including center anode, grounding shell, insulator and coated semiconductor；Lead to respectively between center anode and grounding shell Cross insulator and be dielectrically separated from and discharge with coated semiconductor；Spark plug center anode upper end is connection bolt, passes through bolt and igniting Circuit feeder ear cathode is connected, and spark plug ground cathode lower end is bolt, is connected by bolt with thruster minus plate, formed back Road；

In igniting end face, equipped with ring-type, the coated semiconductor of chip between center anode and outer layer cathode, center anode is with partly leading Certain fit-up gap L is left between body coating so that center anode can slide axially；Fit-up gap L refers to circumferential expansion The size of amount Δ R=α R Δs T determines, wherein, α is thermal coefficient of expansion, and anode diameter centered on R, Δ T is the change of temperature Amount；

In non-semiconductor coating area, fit-up gap L1 is left in center anode and insulating ceramics.

2. semiconductor spark plug according to claim 1, the insulator is insulating ceramics, the insulating ceramics lower face Using ring-type, chip-Size semiconductor ring seal mouth.

3. a kind of ignition system of semiconductor spark plug, including semiconductor spark plug as claimed in claim 1, further include power supply Unit, start unit of lighting a fire；Power supply unit is used for the low-voltage dc power supply (V) on satellite being converted to high-voltage pulse and to breakdown Trigger capacitance (C4), the first main storage capacitor (C1), the second main storage capacitor (C2), the 3rd main storage capacitor (C3) charging；Point Fiery start unit is used for breakdown triggering capacitance (C4), the first main storage capacitor (C1), the second main storage capacitor (C2) and the The energy abrupt release of three main storage capacitors (C3) is to spark plug.

4. a kind of ignition system of semiconductor spark plug according to claim 3, the power supply unit includes spaceborne power supply (V) and transformer (T1)；Wherein, spaceborne power supply (V) is connected with the primary coil of transformer (T1), and transformer (T1) will be spaceborne straight (V) boosts in galvanic electricity source, and the secondary coil of transformer (T1) is supplied to rear class as main power source.

5. a kind of ignition system of semiconductor spark plug according to claim 4, the igniting start unit includes breakdown Capacitance (C4), the first main storage capacitor (C1), the second main storage capacitor (C2), the 3rd main storage capacitor (C3) are triggered, isolates coupling Capacitance (C5) is closed, divider resistance (R1), the first diode (D1), the second diode (D2) and the 3rd diode (D3), first opens Close (K1) and second switch (K2), switching transistor (IGBT) ,+5V priming supplies, spark rate controller (N)；Wherein, trigger Circuit is composed in series by+5V priming supplies and spark rate controller (N)；The secondary coil of secondary transformer (T2) is with isolating coupling Connect after closing capacitance (C5) series connection with the second diode (D2)；The primary coil of first diode (D1) and secondary transformer (T2) Connect after parallel connection with the 3rd diode (D3), switching transistor (IGBT), it is in parallel with breakdown triggering capacitance (C4) again after series connection, and Connect again with divider resistance (R1) after connection, form branch one；First main storage capacitor (C1), the second main storage capacitor (C2), Three main storage capacitors (C3) are in parallel, form branch two；The secondary coil of secondary transformer (T2) is gone here and there with isolation coupling capacitance (C5) It is in parallel with spark plug (M) again after connection, connect again with the second diode (D2) after in parallel, form branch three；Branch one, branch two, Branch three is in parallel, and the secondary coil after parallel connection again with transformer (T1) is connected.