KR20040095877A - Nanosecond pulse generator with nonlinear capacitors and magnetic power compressions - Google Patents

Abstract

PURPOSE: A nano second pulse voltage generator using a non-linear capacitor and a magnetic compression method is provided to generate a high-voltage and high-speed pulse by coupling a linear pulse transformer or a non-linear capacitor to a conventional pulse generator. CONSTITUTION: A nano second pulse voltage generator using a non-linear capacitor and a magnetic compression method includes a high-voltage basic pulse generator, a linear pulse transformer, a plurality of non-linear capacitors, and a load. The linear pulse transformer includes a plurality of primary coils connected serially to an output terminal of the high-voltage basic pulse generator and a plurality of secondary coils. The non-linear capacitors are coupled in parallel to the secondary coils of the linear pulse transformer. The load is connected to both ends of the non-linear capacitors. The non-linear capacitors are serially coupled to each other. The internal pulse voltages of the non-linear capacitors are applied to both ends of the load.

Description

NANOSECOND PULSE GENERATOR WITH NONLINEAR CAPACITORS AND MAGNETIC POWER COMPRESSIONS}

The present invention relates to a high voltage nano pulse generator, and more particularly, to an apparatus for generating a high voltage nanosecond pulse including a plurality of linear pulse transformers and nonlinear capacitors respectively coupled to a secondary side thereof.

A device for purifying harmful gases such as an exhaust gas treatment device or an acid rain purifier of an automobile requires a high voltage having an extremely short pulse width to efficiently decompose a large amount of harmful gases (eg, SOx and NOx). For example, when sulfur dioxide (SO ₂ ) is decomposed into sulfur ions (S ²⁺ ) and oxygen ions (O ₂ ^2- ), a high intensity electric shock must be applied to the gas to decompose the gas. In this case, a short pulse of high power is needed to overcome the bonding force between the ions. At this time, the higher the power and the shorter the pulse (i.e., the higher the peak voltage and the product of the current and the shorter the duration of the pulse), the more effective the ion separation.

Attempts to produce high voltage nanosecond pulses use semiconductor switches and high voltage discharge pulse switches (eg thyratron, spark gap switch, vacuum tube switch, etc.). There is this.

First, the semiconductor switch has the advantages of long life and high reliability, but there is a problem that can not be directly used to generate a high-speed, high-voltage pulse voltage because of the limitation of the operating voltage.

Secondly, among high voltage discharge pulse switches, in environmental applications such as purification of noxious gases, pulsed corona streamer discharges have been widely attempted to generate periodic pulses with a high voltage nanosecond pulse range. Traditionally, pulse generators using high voltage transformers and magnetic compression systems are widely used. "High Voltage and Short Rise-Time Pulse Transformer with" by N. Kobayashi, published on the 11th IEEE International Pulse-Power Conference (Baltimore, MD, 1997), vol. Amorphous Cores "shows a pulse circuit using a pulse power transformer and magnetic pulse compression circuit. This paper relates to a pulse circuit for generating a gas laser. In the pulse power transformer, it is difficult to obtain a pulse having both high voltage characteristics and short characteristics because the loop inductance increases due to the increase in dielectric breakdown length and the size of the transformer. We have proposed that a cobalt amorphous alloy core with a large magnetic flux density can provide a high pressure, fast rise time, high frequency, and high speed (short cycle) pulse power transformer through good heat sink design. The device provides pulse power with 80 kV output voltage and 65 ns rise time under optimal conditions. However, even in the optimum state, the transformer has a problem that the energy efficiency of the entire device is much lower than that of the transformer because the transmission efficiency is low as 73% to 83%. Have.

As both the semiconductor switching device and the high voltage discharge pulse switch have problems as described above, recently, a study of making a high voltage high speed pulse using a voltage amplification effect of a nonlinear ceramic capacitor has been conducted. Non-linear capacitors used to generate high-voltage high-frequency pulse power have a characteristic that the capacitance (capacity C) value decreases by about one tenth when a predetermined amount or more of charge passes, and when the capacitance C decreases, it is stored in the capacitance. Since the energy (1/2 CV ² ) is constant (for example, 1/2 C / 4 * (2V) ² when the capacitance value is 1/4, the voltage across the capacitor doubles). As a result, the voltage between the capacitors increases rapidly. "Voltage Amplification Effect of Nonlinear Transmission Lines For Fast," by Shinji Ibuka and others, published on the 11th IEEE International Pulsed Power Symposium (Baltimore, MD, 1997). High Voltage Pulse Generation "describes the process of obtaining a high voltage pulse power with a width of 11 ns of 76 ns using the voltage amplification effect of soliton collision and arrangement in a nonlinear transmission line with ferroelectric ceramic capacitors. It is. In the case of the pulse transformer using the self-compression technique, there is a problem in low transmission efficiency and a large volume of the device. In this paper, this paper tries to solve the problem by utilizing the voltage amplification effect of the nonlinear transmission line (NLTL). In this paper, the pulse sharpening effect of a nonlinear transmission line is used to obtain a high rise pulse of fast rise time. In addition, the realization of high voltage nonlinear capacitance is achieved by a BaTiO ₃ ferroelectric ceramic capacitor, and when two solitons are collided, a soliton having twice the size and a shorter pulse width is used.

In addition, as another attempt to improve energy efficiency, IEEE Trans on Plasma Science No. 28 No. 5 (October 2001), pages 1362 to 1367, the inventors of the present invention, EP Pavlov, etc. This written "Fast High Voltage Pulse Generation Using Nonlinear Capacitors" is disclosed. The high-speed, high-voltage pulse disclosed in this paper includes a semiconductor switch and a nonlinear capacitor, and uses the characteristic that the capacity of the nonlinear capacitor is reduced to 1/10 when a predetermined amount or more of charge passes through the nonlinear capacitor. The circuit shown in Fig. 1 uses the IGBT as an open switch among the circuits published in this paper, and shows a rectifier, an IGBT, an inductance, a nonlinear capacitor, and a load. The nonlinear capacitor used in this design is DE1207F103Z2K, manufactured by Murata, with a capacity of 10 nF and rated voltage of 2 kV, capable of withstanding approximately 5-6 kV for a short period of time, and the IGBT has a rated voltage of 3300 V. Used as a first open switch. The energy of the low capacitor C1 voltage is stored in the inductor L1 via the IGBT. The current rise time in the inductor L1 is 55 mA and the magnitude of the current is 370 A. When the IGBT switch is open, the current in the inductor L1 starts to charge to the capacitor C2, and the second inductor L2 is energized through the capacitor C3. When the nonlinear capacitor C3 is saturated, the currents from the inductors L1 and L2 and the capacitor C2 pass through the capacitor C3, thereby applying a high voltage pulse to the load. The output voltage has a size of 4.3kV and a pulse width of 300ns.

By the way, the device using the nonlinear capacitor alone cannot produce a high-speed pulse of extremely high voltage required for a high-performance harmful gas purification device or the like. In order to be used for a high-performance noxious gas purification device, the pulse width should be at least 50kV and its pulse width should be 120nS (FWHM) or less. Here, FWHM (Full Wave Half Magnitude) refers to the pulse width at 1/2 of the maximum pulse.

Therefore, in order to use a nonlinear capacitor to generate a high voltage pulse, it may be considered to increase the rated voltage by connecting a plurality of nonlinear capacitors in series. However, simply connecting a plurality of capacitors in series causes a problem due to overlapping in the nonlinear operating section. This is because a change in capacity occurs in the nonlinear operating period, because the change in capacity in each nonlinear capacitor is not only non-simultaneous but also the size change is not non-identical. Since the capacitance or voltage of each of the different capacitors must be uniformly distributed to produce the desired waveform, if non-uniform voltages occur in multiple capacitors connected in series, one or some breakdowns can occur before the required voltage is reached. This will occur. At this time, it may be considered to equalize the non-uniform voltages between the capacitors with the resistor, but the problem occurs that the efficiency of the system is lowered due to the substantially reduced energy transfer amount due to the resistance.

In an attempt to remedy the above problem, the inventors devised a method of equalizing the voltage of each output nonlinear capacitor by connecting a pulse generator to each nonlinear capacitor separately from the method of simply connecting a plurality of capacitors in series. Paper presented at the 15th KIEE Conference, Honam University, Korea, April 25, 1988, "A Nonlinear Capacitor Based Pulse Genertor".

FIG. 2 shows an example of a pulse generator that is operated at one time at a common load as a stacked pulse generator in which a pulse generator is coupled to three nonlinear capacitors, respectively. 3 shows the waveform of the output voltage by the pulse generator. However, according to the experimental results, although each pulse generator can provide a pulse of 2.4 kV voltage and 0.53 kHz (FWHM) pulse width for a load of 50 Ω, an output proportional to the number of pulse generators could not be obtained. . The experiment resulted in a pulse of approximately 6.3 kV and a pulse width of 0.53 kW (FWHM). That is, a 7.2 kV voltage pulse could not be generated. The reason that the output does not appear in direct proportion to the number of pulse generators is that there are device parameters that cannot be matched exactly the same for each pulse generator and nonlinear capacitor, and moreover, as shown in the waveform shown in FIG. It is analyzed that there is time jittering.

As a result, it can be seen that it is difficult to derive an optimal system for obtaining a high voltage pulse only by connecting a pulse generator to each of a plurality of nonlinear capacitors. The system also has the practical problem of complicated control and high manufacturing costs.

Accordingly, the inventors have devised an apparatus for generating a high voltage high speed pulse by combining a linear pulse transformer and a nonlinear capacitor with a basic pulse generator.

The present invention is to improve the problems of the conventional high voltage high speed pulse generator as described above, the pulse generator capable of generating a pulse of higher voltage compared to the prior art to be effectively used in high-performance harmful gas purifier, etc. It aims to provide.

Another object of the present invention is to provide a pulse generator capable of generating a pulse having a shorter pulse width at a high voltage required for a high performance noxious gas purifier.

It is still another object of the present invention to provide a pulse generator that adopts a structure that can be easily changed in design according to a voltage required by a load, and is easy to control and has excellent efficiency.

1 is a circuit diagram of a pulse generator according to the prior art,

2 is a system circuit diagram as an example in which a basic pulse generator is superimposed;

3 is a waveform diagram of pulses generated by the system of FIG.

Figure 4 is a graph showing the characteristics of the nonlinear capacitor used in the present invention,

5 is a circuit diagram showing an example of a high voltage nano-pulse generator according to the present invention;

6 is a waveform diagram of pulses generated by the pulse generator of FIG. 5.

The present invention has been made in order to achieve the above object, by coupling the primary pulse generator in series by connecting the primary side of the plurality of linear pulse transformer and connecting the non-linear capacitors in each of the secondary windings in series to connect the non-linear capacitors in series To generate a high voltage (nanosecond) pulse voltage.

That is, the high voltage nano pulse generator according to the present invention includes a high voltage basic pulse generator (PPG); A plurality of linear pulse transformers (LPTs) having independent primary windings and secondary windings; A plurality of nonlinear capacitors (NLCs) in which nonlinear capacitors are coupled in parallel at each end of each of the secondary windings of the linear pulse transformer; And a load connected to both ends of the nonlinear capacitor, and the plurality of nonlinear capacitors are coupled in series to superimpose the internal pulse voltages of the respective nonlinear capacitors to be applied to both ends of the load.

In addition, the nonlinear capacitor NLC is characterized in that its capacity decreases to about 1/10 in proportion to the passage of a predetermined amount of charge.

In addition, the basic pulse generator is a high-voltage charger, a cyclone coupled to both ends and an inductor coupled as a pitch circuit at both ends of the cyclone, two capacitors, and a shunt connected to one end of the capacitor. And a flexible inductor, wherein the output terminal of the satutable inductor is coupled to a primary side of a linear pulse transformer connected in series.

A nonlinear pulse transformer (LPT) consists of a plurality of independent cores, and the primary side is connected in series to minimize the occurrence of circuit inductance and time jittering. In order to minimize the leakage inductance, it is desirable to design a low inductive circuit with a minimum gap between the windings and the cores and a minimum number of turns of each core (for example, n = 1). Minimizing the circuit inductance and parallax can minimize the charging time of the nonlinear capacitor and achieve the maximum pulse power.

Installing a saturable inductor (MS-1) at the output side of the basic pulse generator produces a current compression effect. The capacitor is placed in front of the satable inductor, and the voltage of the capacitor is doubled through the polarity change of the voltage of the capacitor. In the satutable inductor, the instantaneous current when voltage is amplified is also compressed and amplified (V = L.di / dt), and this compressed and amplified current is supplied to the primary side of the linear pulse transformer LPT.

The high voltage pulse current supplied from the basic pulse generator (PPG) flows in the primary winding of the linear pulse transformer (LPT), and a voltage proportional to the number of turns of the transformer also flows in the secondary winding. This voltage is applied to the nonlinear capacitors NLC which are respectively connected in parallel to the secondary coil. In the nonlinear capacitor NLC adopted in the present invention, a capacity of approximately 1/10 is reduced when a predetermined amount of charge passes. However, since the energy value stored in the capacitance C does not change (E = 1/2 CV ² ), the changed voltage V 'according to the changed capacitance value C' is V '= (C / C') ^{1 /. There is also a 2} V relationship, and conversely, as the voltage increases, its capacity also rapidly decreases (Fig. 4). That is, when the nonlinear capacitor saturates, voltage compression occurs and shorter pulses (110 nS (FWHM) or less) are generated. As the capacitance decreases and the pulse width (time) becomes shorter, the voltage per unit time increases rapidly in the relationship of i = C.dv / dt. This short pulse is added to the voltage of each of the 160nF nonlinear capacitors connected in series and then applied to a 50Ω load.

Since the pulse voltage generated in each capacitor of the last stage is short, the effect of minimizing each pulse width and time difference can be obtained even if these short voltages are superimposed. In addition, since the voltage applied to each capacitor is determined by the output voltage of the linear pulse transformer and is evenly divided, it is possible to prevent nonuniformity in which the voltage is concentrated only on one or some of the plurality of capacitors. In addition, by changing the number of linear pulse transformer output stage and the number of nonlinear series capacitors, the design can be easily changed according to the voltage required at the load.

Hereinafter, with reference to the drawings will be described in more detail the configuration of the present invention with the most preferred embodiment of the present invention.

5 is a circuit diagram showing an example of a high voltage nano pulse generator according to the present invention.

The left side shows a charging device and a thyratron coupled to both ends thereof, and two capacitors and an inductor coupled as a pitch circuit are connected to both ends of the thyrahron. In addition, a saturable inductor is connected to the upper capacitor. The output stage of the satutable inductor is coupled to the primary side of the linear pulse transformer to supply certain basic high voltage pulses to the linear pulse transformer (LPT).

The basic pulse generator PPG raises the voltage applied to each of the nonlinear capacitors NLC to 20 kV according to the turns ratio (here 1: 1) of the primary side and the secondary side of the linear pulse transformer LPT. First, the charging device supplies a high voltage of direct current 10kV. The inductor (0.3 μH) between cyiratron and two capacitors (80nF) is the charge current limiting inductor. The 10kV voltage from the charger charges two capacitors to a high voltage of 10kV through the charge current limiting inductor. At this time, if the polarity of the lower capacitor is inverted by turning on the cyclotron switch, the voltage applied to the satutable inductor MS-1 is doubled (20 kV) to saturate the MS-1. At this time, the flowing current undergoes a compression in which the magnitude of the current per unit time increases, as can be seen from the relationship of V = L · di / dt. This current flows through the primary side of the linear pulse transformer (LPT). A voltage proportional to the number of turns of the transformer is induced on the secondary side of the linear pulse transformer, and this voltage is applied to eight non-linear capacitors 160 nF connected in parallel to the secondary winding.

Each of these eight nonlinear capacitors are connected in parallel to each coil for the secondary windings, but all eight nonlinear capacitors are connected in series. When the voltage is induced in the nonlinear capacitor, as shown in FIG. 4, the capacity of the nonlinear capacitor decreases rapidly. When the capacity decreases, from the relationship E = 1/2 CV ² = 1/2 C'V ' ² , the voltage changes rapidly, i.e., voltage amplification due to saturation of the nonlinear capacitor. During the short pulse width time, the voltage becomes larger and the voltage is compressed to generate a pulse with a short pulse width of high voltage, which is applied to a load of 50 Ω after being applied to the voltage of each 160nF capacitor connected in series.

According to the experiment, as shown in FIG. 6, a pulse having a voltage of 52 kV and a pulse width of 110 nS (FWHM) was generated. In observing FIG. 6, it is noted that in FIG. 3, a vertical column representing voltage represents 1 kV, and a horizontal column representing time represents 1 μS, whereas in FIG. 6, each column has 10 kV and 200 nS, respectively. Is the point.

In this way, the scale is greatly different, and it can be seen that the scale output from the high speed nanopulse generator according to the present invention has an excellent effect of the remarkably increasing pulse size and the remarkably narrowing of the pulse width. . Since the pulse voltage generated in each capacitor of the final stage is short, even if they overlap, there is an effect of minimizing the overall pulse width and time difference.

Since the voltage applied to each capacitor is determined by the output voltage of the linear pulse transformer and is evenly distributed among the plurality of coils, the phenomenon of voltage biasing or time jittering in one or a part of several capacitors is minimized.

The number of output windings of the linear pulse transformer and the number of nonlinear series capacitors can be varied to obtain the characteristics (pulse size and pulse width) of the pulse required by the load. For example, the magnitude of the pulse can be increased or decreased by decreasing or increasing the number of secondary output windings and non-linear series capacitors of the linear pulse transformer. In this case, however, care must be taken in the design so as not to exceed the threshold voltage that each device can withstand.

As described above, the configuration of the present invention has been described through preferred embodiments with reference to the accompanying drawings. However, the above embodiment merely shows an example of the nano-pulse generator according to the present invention, and the scope of the present invention is not limited to the above embodiment, as well as the technical idea of the present invention defined by the appended claims. Additions, reductions, changes, and modifications of some of the components as long as they are included in the scope of the present invention cannot be denied.

In the above configuration, the inventors experimented with eight nonlinear capacitors. As a result, the pulse voltage measured at the output load of 50? Was 52 kV, and the pulse width was 110 nS (FWHM).

Therefore, according to the non-linear capacitor and the nano-pulse generator using the magnetic compression according to the present invention, it is possible to generate a pulse of a higher voltage with a shorter pulse width compared to the prior art. Therefore, it can be effectively used for a high-performance noxious gas purifier with easy control and excellent efficiency.

In addition, by changing the number of the secondary coil of the linear pulse transformer and the series nonlinear capacitor of the output terminal, it is possible to easily change the design according to the voltage required by the load.

Claims (3)

A high voltage elementary pulse generator; A linear pulse transformer including a plurality of independent primary side windings and a secondary side windings, the primary windings being coupled in series to an output terminal of the basic pulse generator; A plurality of nonlinear capacitors coupled in parallel to each of the plurality of secondary windings of the linear pulse transformer; A load connected to both ends of the plurality of nonlinear capacitors in series, and And the plurality of nonlinear capacitors are coupled in series to superimpose the internal pulse voltages of the respective nonlinear capacitors and apply them across the load. The method of claim 1, The non-linear capacitor is a high voltage nano pulse generator, characterized in that the capacity is reduced to approximately 1/10 in proportion to the passage of a predetermined amount of charge. The method according to claim 1 or 2, The basic pulse generator includes a charging device, a cyclone coupled to both ends, an inductor coupled as a pitch circuit at both ends of the cyclone, two capacitors, and a satutable inductor connected to one end of the capacitor. And the output terminal of the satutable inductor is coupled to the primary side of the linear pulse transformer.