The device for generating short pulses of high voltage


H03K3/57 - PULSE TECHNIQUE (measuring pulse characteristics G01R; mechanical counters having an electrical input G06M; information storage devices in general G11; sample-and-hold arrangements in electric analogue stores G11C0027020000; construction of switches involving contact making and breaking for generation of pulses, e.g. by using a moving magnet, H01H; static conversion of electric power H02M; generation of oscillations by circuits employing active elements which operate in a non-switching manner H03B; modulating sinusoidal oscillations with pulses H03C, H04L; discriminator circuits involving pulse counting H03D; automatic control of generators H03L; starting, synchronisation, or stabilisation of generators where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
H03K3/53 - PULSE TECHNIQUE (measuring pulse characteristics G01R; mechanical counters having an electrical input G06M; information storage devices in general G11; sample-and-hold arrangements in electric analogue stores G11C0027020000; construction of switches involving contact making and breaking for generation of pulses, e.g. by using a moving magnet, H01H; static conversion of electric power H02M; generation of oscillations by circuits employing active elements which operate in a non-switching manner H03B; modulating sinusoidal oscillations with pulses H03C, H04L; discriminator circuits involving pulse counting H03D; automatic control of generators H03L; starting, synchronisation, or stabilisation of generators where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

 

(57) Abstract:

The invention relates to a device for generating short pulses of high voltage, which can be used, for example, the ignition pulse periodic electrical discharges, such as pulsed corona discharge or pulsed barrier discharge. The technical result is to obtain high-voltage pulses with extremely short front rise (5-10 NS) with a high pulse repetition frequency (about 2000 Hz) with a maximum power efficiency of the device (efficiency 90%). To achieve the specified result, a device comprising a high voltage source, the working capacity, high-voltage switch, switching the working capacity to the load. When the high voltage source comprises a network rectifier, semiconductor Converter, one or more high-voltage pulse transformers, providing the charging capacity in small portions formed at each actuation of the transducer so that the frequency of the pulse charging of the working capacity of at least 3 times higher frequency response vysokovolt multiple pins, threads, needles, blades or other parts with sharp edges that may cause ignition of the corona discharge by applying to the electrodes of a spark gap voltage whose magnitude is below the breakdown. 2 C.p. f-crystals, 2 Il.

Device generation of short high-voltage pulses can be applied in various fields of modern industry and science, including the generation of pulse (pulse periodic) electric discharges [1] . Systems based on pulsed corona discharge are now one of the most promising and fastest growing areas in environmental engineering and technology. These include water treatment plants, air, furnace, fuel and vent gases, electrostatic precipitators with pulsed power, as well as systems for the production of ozone. However, the real development of these vital systems is constrained by the lack of cheap and long-lasting power sources, generating short pulses of high voltage and with the necessary for industrial applications characteristics.

For the generation of short high-voltage pulses for ignition of a pulsed corona discharge at the present time are mainly used schemes for loose connection faults. As an industrial thyratrons and managed arresters are quite expensive and have short lifetimes in the mode of generation of short pulses. In addition, the use of thyratrons and managed arresters involves additional energy costs for heating (heating) of the cathode and the formation of control pulses (start), which naturally reduces the energy efficiency pulse generator as a whole.

The use of unmanaged sameproblem arresters (which have the best timing characteristics in mode single pulse) in the standard scheme, with the ballast resistance leads to a very large loss of energy when charging capacity (ohmic loss resistance can be of the order of 50%). In addition, unmanaged discharger conventional type may not provide the frequency of operation (switching) 1000 Hz and above that normally required in practical applications of pulsed corona discharges in the gas cleaning or to generate ozone.

The prototype of our invention is a device for creating a short high-voltage pulses, described in [2], which shows the number of schemes using managed arresters of different types (razorenova discharge. However, they offer a discharger with an external control pulse is quite complex in technical terms, so as to synchronize the operation of its channels will need continuous alignment of all bit periods with high enough accuracy. In addition, the use of external control pulse applied to the main electrodes of a spark gap, implies a significant loss of energy management, reducing the efficiency of the system.

Dischargers with rotating electrodes, the proposed ibid, also technically too complex, which dramatically limits the range of their practical application. In addition, as the gaps with rotating electrodes and the arresters with external firing pulse can not provide the times of switching the front rise of the current pulse) is of the order of 10 NS is required for some practical applications.

The aim of our invention is to provide a simple, cheap, easy to use and easily scalable generator short pulses of high voltage, providing the shortest possible time switching (of the order of 10 NS), high energy efficiency and a sufficient pulse repetition frequency.

A diagram of the device generating the high voltage pulses to maintain a corona discharge, similar to the circuit of the relaxation oscillator, but has some significant differences. The working capacity of the charging small portions (steps) that are generated during each trip of the semiconductor Converter, as shown in Fig. 2. Thus the charging of the capacitor is the same as a normal rectifier ballast tomographically resistance, but in this case, the charge current is limited to no resistance, and the charging circuit, permitting the charge on the working capacity of the portions following each other in each pulse Converter. In this case, the energy loss during charging of the capacitor practically does not occur.

PNY, and the gap closes, the working capacity of the discharge chamber. The discharge chamber is charged to a certain voltage and after the corona discharge ignition (in the camera) is quickly discharged by the discharge current, with a work capacity. After the voltage on the camera and working capacity will fall below the threshold of burning corona discharge, the discharger is turned off and charging capacity (5) (Fig.1) begins again.

There is a dependence of the stability and efficiency of the system and the magnitude of charging of the working capacity of each pulse Converter. Each pulse of the Converter charges the working tank (5) for some value of u. Obviously, the smaller U, the better, as it is possible to more accurately adjust the voltage of the working capacity and to achieve more current corona discharge, preventing its transformation into a spark discharge. For stable operation of the system it is necessary that the frequency of operation of the pulse transformer was at least 3 times higher frequency operation of a spark gap.

For the stable operation unmanaged sameproblem discharger mode maximum short opening times and maksimalno switching frequency (which is especially important for closing the gap in Reinecke current through it and in that moment, when the discharger is closed. This is achieved by the fact that one or both of the electrode unmanaged sameproblem spark gap is made in the form of one or more pins, thread, needles, blades or other parts with sharp edges that can koreasouth at a voltage below the breakdown. Emerging "dark" current (closed gap) allows you to maintain some fixed concentration of electronically excited molecules of gas, which accelerates the development of breakdown in the spark gap and thereby reduces the time of switching. In addition, the "dark" current through the spark gap in the closed state, supported by weak corona discharge from the electrodes of a spark gap, a stabilising influence on the damping of a spark gap in the regime of incomplete discharge of the working capacity, since this leak compensates for the residual current of the crown through the discharge chamber pulsed corona discharge.

In some cases, the discharge chamber is pulsed corona discharge (or unmanaged improbably discharger) can be connected in parallel (shorted) high resistance to bias DC component of the voltage on the discharge chamber. This method of connection can be important for such practical is no constant voltage component). In some cases this resistance have a stabilizing effect on the system at the time of launch. The resistance value is chosen such (not too small), so that practically does not impair the efficiency of the system generating voltage pulses in General.

Examples

Example 1. In the first case, in the circuit shown in Fig. 1, was applied the following discharger design - anode consisted of a system of rods of 2 mm diameter stainless steel; the cathode is a cylindrical shape with end (working) plane parallel to the plane passing through the ends of the anode rods. Through the spark gap was insufflated air with a flow rate of from 1 to 100 l/h at a pressure of 2 ATM abs. pressure. The load acted discharge chamber pulsed corona discharge.

The ends of all the rods of a spark gap steadily koronaruli when applying to the electrodes of a spark gap voltage below the breakdown.

This spark gap is provided a switching frequency up to 2000 Hz and rise time current of about 8 NS.

Example 2. In the second case, in the circuit shown in Fig. 1, was used discharger different design: the anode consisted of a system of radial p is ez discharger was insufflated air with a flow rate of 1-100 l/h at atmospheric pressure. The load acted discharge chamber pulsed corona discharge.

The ends of all the rods of a spark gap steadily koronaruli when applying to the electrodes of a spark gap voltage below the breakdown.

This spark gap is provided a switching frequency up to 2000 Hz and rise time current of about 8 NS.

Example 3. In the third case in the circuit shown in Fig. 1, was used discharger design similar to example 1.

Through the spark gap was insufflated air with a flow rate of 1-100 l/h at atmospheric pressure. The load acted discharge chamber pulsed barrier discharge, short-circuited impedance of 1000 Ohms.

The ends of all the rods of a spark gap steadily koronaruli when applying to the electrodes of a spark gap voltage below the breakdown.

This spark gap is provided a switching frequency up to 2000 Hz and rise time current of about 8 NS.

Literature:

1. Proceedings of the XVII th International Symposium on Discharges and Electrical Insulation, Berkeley, California, 1996.

2. U.S. patent N 4541848, B 03 C 3/66, 17.09.85.

1. A generator of high voltage pulses, consisting of a source of high voltage, high voltage rectifier, working capacity and high high voltage, supply high-voltage rectifier comprises a network rectifier, semiconductor Converter, one or more high-voltage pulse transformers, providing the charging capacity in small portions formed at each actuation of the transducer, so that the frequency of the pulse charging of the working capacity of at least 3 times higher frequency operation of the high voltage switch.

2. The device under item 1, characterized in that the said high-voltage switch is an unmanaged improbably discharger, one or both electrodes which are made in the form of one or more pins, thread, needles, blades or other parts with sharp edges that may cause ignition of the corona discharge by applying to the electrodes of a spark gap voltage whose magnitude is below the breakdown.

3. The device under item 1, characterized in that the working capacity is the output capacity of the high voltage rectifier.

 

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FIELD: measurement technology; pulse stream generators.

SUBSTANCE: proposed Poisson pulse stream generator has k + 1 memory devices, comparison unit, k digital-to-analog converters, control circuit, register, counter, selector, k bell-shaped pulse generators, adder, voltage-to-current converter, and clock generator.

EFFECT: enlarged generation range of pulses adequate to ionization chamber signals.

1 cl, 2 dwg

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