RU2486671C1 - Generator of high-voltage pulses - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: generator of high-voltage pulses contains a high-voltage switching power supply source, a variable current-limiting resistor, a capacitor that does not withstand breakdown voltage with adjustable air gap between plates, a capacitor of differentiating circuit and variable resistor of differentiating circuit.

EFFECT: reduction in number of radioelements in the device and possibility to change parameters of high-voltage pulses at the generator output without changes in its circuit.

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Description

The technical solution relates to high-voltage pulse technology and can be used to generate short high-voltage voltage pulses.

An analog is a generator of high-voltage pulses (Goroshkov B.I. Elements of electronic devices: Reference book. - M.: Radio and communications, 1988. - 176 p., S.136). This device contains a source of constant high-voltage voltage, the potential and common conclusions of which are connected respectively to the power output and the general output of a series of transistors connected in series with an avalanche breakdown mode, the output of a series of transistors connected in series is the output of a generator, the control output of a chain of series-connected transistors is connected to an output control generator.

As a prototype, a high-voltage pulse generator was selected (RF patent No. 2368069 from 09/20/2009). This device contains a pulsed high-voltage voltage source, the potential and general conclusions of the high-voltage voltage source are connected respectively to the power output and the general output of the chains of series-connected transistors having an avalanche breakdown mode, the terminals of the same name are connected in parallel, the output of the chains of series-connected transistors is an output generator, the input of the control generator is connected to the control terminal of the high voltage source, you od control oscillator connected to the control terminal of the n chains of serially connected transistors, where n - the natural numbers from 1 to ∞. The value of n may be two.

The presented circuit contains a large number of radio elements, requires an accurate selection of avalanche transistors by breakdown voltage (± 2.5 V), and to change the voltage parameters at the generator output, it is necessary to change its circuit, in particular the number of series-connected transistors having an avalanche breakdown mode.

The technical problem to be solved is the reduction in the number of radioelements in the device and the possibility of changing the parameters of the high-voltage voltage pulses at the generator output without changing its circuit.

The technical problem to be solved in a high-voltage pulse generator containing a high-voltage pulse source is achieved by introducing a variable current-limiting resistor, an electrically punctured capacitor with a variable air gap between the plates, a differentiating circuit capacitor and a differentiating circuit variable resistor, and a potential output of a high-voltage pulse source voltage is connected to the first terminal of an alternating current-limiting resistor; One pulsed high-voltage voltage source is connected to the second terminal of an electrically punched capacitor with a variable air gap between the plates and to the second terminal of a variable resistor of the differentiating circuit, the first terminal of an electrically pierced capacitor with a variable air gap between the plates is connected to the second terminal of a variable current limiting resistor and to the first the derivation of the capacitor of the differentiating chain, the second output of the capacitor of the differentiating chain is connected to a first terminal of the variable resistor differentiating circuit, the second terminal of the capacitor of the differentiating circuit and a common output pulsed source of high voltage generator are the outputs high voltage pulses.

Figure 1 shows the structural diagram of the generator of high voltage pulses; figure 2 shows a diagram of a pulsed source of high voltage; figure 3 shows a graph of the voltage at the potential output of a pulsed source of high voltage; figure 4 shows a graph of the voltage at the output of the generator of high voltage pulses;

The high-voltage pulse generator (Fig. 1) contains a high-voltage pulse source 1, an alternating current-limiting resistor 2, an electrically punctured capacitor 3 with a variable air gap between the plates, a capacitor of the differentiating circuit 4 and a variable resistor of the differentiating circuit 5, a potential output of a pulsed source of high-voltage voltage 1 connected to terminal 6 of an alternating current-limiting resistor 2, a common terminal of a pulsed high-voltage voltage source 1 is connected n with terminal 7 of an electrically punched capacitor 3 with a variable air gap between the plates and with terminal 8 of a variable resistor of the differentiating circuit 5, terminal 9 of an electrically punched capacitor 3 with a variable air gap between the plates is connected to terminal 10 of a variable current limiting resistor 2 and with terminal 11 capacitor of the differentiating chain 4, terminal 12 of the capacitor of the differentiating chain 4 is connected to terminal 13 of a variable resistor of the differentiating chain 5, terminal 12 of the condensate differentiating circuit 4 and the general output of the pulse source of high voltage voltage 1 are the outputs of the generator of high voltage pulses, the control output of the pulse source of high voltage voltage 1 is not used.

The pulse source of high voltage 1 (FIG. 2) contains a constant low voltage source 14, a key 15 with two switching positions, a capacitor 16, a transformer 17 with a soft magnetic core, the primary winding of which contains the number of turns W ₁ , and the secondary winding the number of turns W ₂ , (W ₂ >> W ₁ ), a series of series-connected diodes 18 (at least ten diodes). In the initial state, the key 15 is in the lower position and connects the first terminal of the capacitor 16 to the common terminal of the source of constant low voltage 14 and the terminal 19 of the primary winding of the transformer 17, the common terminal of the source of constant low voltage 14 is grounded, in this position the capacitor 16 is discharged, the second terminal of the capacitor 16 connected to the terminal 20 of the primary winding of the transformer 17. The terminal 21 of the secondary winding of the transformer 17 is connected to the first terminal of the chain of series-connected diodes 18, the terminal 22 of the secondary winding ransformatora 17 is grounded and the common terminal of the pulsed high voltage source 1. The second terminal of the chain of serially connected diodes 18 is a potential source of high voltage output pulse voltage 1.

The high voltage pulse generator operates as follows. When the key 15 is locked to the upper position, the potential terminal of the source of constant low-voltage voltage 14 is connected and the first terminal of the capacitor 16 and the capacitor 16 begin to be charged through the primary winding of the transformer 17, due to which a pulsed positive high-voltage voltage, for example, 100 μs, is excited on the secondary winding of the transformer 17 and a value of, for example, 4 kV. To eliminate the negative high-voltage pulse voltage that occurs when the key 15 is shorted to the lower position and the capacitor 16 is discharged, a chain of diodes connected in series is used 18. In this state, there is no constant high-voltage voltage in this circuit. The pulsed high-voltage voltage has a short duration, for example, _tpit = 100 μs and is present only at the moment the generator is started. The pulsed high-voltage voltage through the potential output of the pulsed source of high-voltage voltage 1 through an alternating current-limiting resistor 2 enters the electrically punctured capacitor 3 with a variable amount of air gap between the plates and starts to charge it. At time t _p , equal voltage U ₂ at terminal 9 of the electrically punched capacitor 3 with a variable amount of air gap between the plates with U _pc the breakdown voltage of the electrically punched capacitor 3 with a variable amount of air gap between the plates, the expected breakdown of the gap between the plates occurs. At the same time, the onset of time t _p , the time of the onset of breakdown, can be controlled by changing the value of the variable current-limiting resistor 2. When the breakdown of the electrically punched capacitor 3 occurs with a variable size of the air gap between the plates, the voltage at the terminal 11 of the capacitor of the differentiating circuit 4 changes rapidly. at the output 12 of the capacitor of the differentiating chain 4, which is the output of the high-voltage pulse generator, a short high-voltage and voltage pulse.

Figure 3 shows a graph of the voltage U ₁ at the potential output of a pulsed source of high voltage voltage 1, U _{2 the} voltage at terminal 9 of the electrically punched capacitor 3 with a variable value of the air gap between the plates, where, if the voltage is U ₂ > U _pc (U _pc is the voltage breakdown of an electrically punched capacitor 3 with a variable amount of air gap between the plates) at a time t _p there is a breakdown of the gap between the plates. The time t _p , the time of the start of the breakdown, can be changed by changing the value of the variable current-limiting resistor 2. In this case, the breakdown voltage U _{pc of the} electrically punched capacitor 3 with a variable value of the air gap between the plates is determined by the size of the air gap. The breakdown voltage of the air gap (dry air, pressure 1 atm.) Between the plates is 2 kV / mm. The voltage graph U ₁ at the potential output of a pulsed source of high voltage voltage 1 in the absence of breakdown is shown by a dashed line.

Figure 4 shows a graph of the voltage at the output of the generator of high voltage pulses. For example, the duration of high voltage pulses is t _imp = 10 ns.

, где C₁ - емкость электрически пробиваемого конденсатора 3 с изменяемой величиной воздушного зазора между обкладками, C₂ - емкость конденсатора дифференцирующей цепочки 4, R₁ - сопротивление переменного резистора дифференцирующей цепочки 5. Например, при C₁=C₁=100 пФ, R₁=50 Ом, τ_раз=10 нс; C₁=C₁=100 пФ, R₁=100 Ом, τ_раз=20 нс; C₁=200 пФ, C₂=100 пФ, R₁=50 Ом, τ_раз=15 нс. Таким образом, изменяя сопротивление переменного токоограничивающего резистора 2, можно изменять момент времени возникновения коротких высоковольтных импульсов на выходе генератора. Также изменяя сопротивление переменного резистора дифференцирующей цепочки 5, емкости электрически пробиваемого конденсатора 3 с изменяемой величиной воздушного зазора между обкладками и емкости конденсатора дифференцирующей цепочки 4 можно регулировать параметры (амплитуду и длительность) коротких высоковольтных импульсов на выходе генератора без изменений в его схеме.Thus, the number of radio elements in this circuit of the high-voltage pulse generator is significantly less than in the prototype due to the absence of chains (for example, three) of transistors connected in series (for example, 20 pcs are necessary for the voltage at the output of the 2 kV high-voltage pulse generator) and the control generator. The amplitude of the generated high-voltage pulse voltage depends on the breakdown voltage of the electrically punched capacitor 3 with a variable value of the air gap between the plates, which in turn is determined by the value of the adjustable air gap between its plates. For example, the size of the adjustable air gap between the plates of the capacitor 2 may be 0.5-2 mm, with a pitch of 0.25 mm. This makes it possible to change the voltage at the output of the high-voltage pulse generator from 1 kV to 4 kV with a step of 0.25 kV, without changing its circuit. The duration of the generated high-voltage pulse depends on the resistance value of the variable resistor of the differentiating circuit 5, the capacitance of the electrically punched capacitor 3 with the variable air gap between the plates and the capacitor of the differentiating circuit 4, which determine the discharge time constant $${\tau }_{R\mathrm{but}{s}_{\mathrm{one}}}:{\tau }_{R\mathrm{but}s}=(C_{\mathrm{one}}+C_2)R_{\mathrm{one}}$$

where C ₁ is the capacitance of an electrically punched capacitor 3 with a variable amount of air gap between the plates, C ₂ is the capacitance of the differentiating circuit 4, R ₁ is the resistance of the variable resistor of the differentiating chain 5. For example, when C ₁ = C ₁ = 100 pF, R ₁ = 50 Ohms, τ _times = 10 ns; C ₁ = C ₁ = 100 pF, R ₁ = 100 Ohms, τ _times = 20 ns; C ₁ = 200 pF, C ₂ = 100 pF, R ₁ = 50 Ohms, τ _times = 15 ns. Thus, by changing the resistance of the variable current-limiting resistor 2, it is possible to change the time instant of occurrence of short high-voltage pulses at the output of the generator. Also, by changing the resistance of the variable resistor of the differentiating chain 5, the capacitance of the electrically punched capacitor 3 with the variable air gap between the plates and the capacitance of the capacitor of the differentiating chain 4, it is possible to adjust the parameters (amplitude and duration) of the short high-voltage pulses at the generator output without changes in its circuit.

Claims (1)

A high-voltage pulse generator containing a high-voltage pulse source, characterized in that an alternating current-limiting resistor, an electrically punctured capacitor with a variable air gap between the plates, a differentiating circuit capacitor and a differentiating variable resistor, a potential output of a high-voltage pulse source are connected to the first the output of a variable current-limiting resistor, the total output of the pulse source is high voltage is connected to the second terminal of an electrically punched capacitor with a variable air gap between the plates and to the second terminal of a variable resistor of the differentiating circuit, the first terminal of an electrically pierced capacitor with a variable air gap between the plates is connected to a second terminal of a variable current limiting resistor and to the first terminal of a differentiating capacitor chain, the second terminal of the capacitor of the differentiating chain is connected to the first terminal of the differentiated resistor of the differentiating circuit, the second terminal of the capacitor of the differentiating chain, and the general output of the pulsed high-voltage voltage source are the outputs of the high-voltage pulse generator.

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