DE4100719A1 - Stabilised high-voltage pulse generator - has resonant transformer fed by diode which is bypassed during voltage doubling by set point comparator of capacitor voltage - Google Patents

Abstract

A three-phase AC supply is connected to a rectifier bridge (G1-G6) with smoothing capacitors (C1, C2). A choke (D) and reverse-blocking diode (2), charging the storage capacitor (C3) to twice the DC voltage in less than 1 ms, are preceded and followed by differently delayed (1) thyristors (V1,V2) with inverse-parallel diodes (G8,G9). Another thyristor (V3) shorting the choke (D) is fired by the comparator (3) of an adjustable input (E) with a voltage (R6) proportional to the transformer sec. pulse driving the load (L). USE/ADVANTAGE - Pref. with pulsed lasers or flashlamps highly efficient circuit gives good voltage stability and low susceptibility to interference.

Description

The invention relates to a circuit in the preamble of claim 1 specified Art.

The invention relates to a circuit for stabili based pulsed high-voltage supply, preferably  for repeated charging of capacitors during operation pulsed lasers, flash lamps or other pulsed Consumers who need high energy densities for a short time These devices are known to be high voltage capacitors fed. From your repeated Charging with as constant a voltage as possible is included Lasers greatly increase the stability of their light emission from.

Circuits for stabili are already from the literature known repeated charging of capacitors. However, these devices are with good stabilization and middle to high performance very much in terms of circuitry agile.

Statically well stabilized power supplies for High voltage with series resistors and high voltage scarf ters (spark gaps, thyratrons) are due to their be limited efficiency, the high static load of high-voltage capacitors and low repeaters tion rate, especially in the case of medium performance from one gen kilowatts, unsuitable.

The throttle step-up converter has disadvantages due to the Generation of unwanted interference signals in the radio frequency rich. These capacitor charging devices, which by means of Im pulse generator, pulse amplifier, pulse transformer and High voltage rectifier with regulation of the pulse wide modulation for high voltage stabilization work (as known for example from DE-OS 32 35 502 are very well stabilized, but quite open  manoeuvrable in production and only for small performances and low repetition rates.

The stabilization of the charging of capacitors through the counting of highly transformed high-frequency pulses by means of appropriate digital circuits, at most except for the charge associated with a pulse (1 bit) or a corresponding quantum of energy take place exactly. On Because of the upper frequency limit of the radio frequency used This stabilization is above all less than 20 kHz very high at repetition rates of more than 100 Hz nau, because then only a few impulses until the next bar can be counted and thus the relative inaccuracy gets very big.

The efficiency is a few kilowatts in the previously known stabilized power supplies bad, so that for intensive cooling of the components to be worried. The technological effort for the sta accounting electronics grows with the middle to educate performance.

An unstabilized pulsed high voltage supply for the charging of capacitors from which the invention comes from the publication Pribori i technika experimenta No. 5 (1985), pages 107 to 109. Due to the strong dependence on the mains voltage swan This process has not been successful so far Zen. So far, there has only been a certain amount of pre-stabilization on the mains side thanks to large magnetic voltage stabilizers to reach.  

Another conceivable variant, the mains voltage swan kungen on the regulation of the leading edge in one compensate thyristor controlled rectifier bridge, has, apart from the necessary elaborate control electronics tronik, the disadvantage that due to the large phases cutting angles that are necessary to get into the control range a strongly pulsating DC voltage arises, through additional elaborate screening measures is smooth.

The invention has for its object a circuit for stabilized, pulsed high voltage supply, preferably to develop capacitors for charging which are characterized by high efficiency, good Stability of the pulse voltage, low susceptibility to interference, simple construction both with high power requirements as well at high repetition rates.

This task is carried out with the characteristic features of the Claim 1 solved.

The invention is based on the knowledge that - starting from a DC voltage source with a downstream one controllable switching element via a choke with span doubling the voltage charges a capacitor, which then by a subsequent switching element via the primary winding at least one subsequent pulse transformer T is discharged and thus a voltage pulse on the secondary side generates - this voltage pulse a particularly high sta bility when a stabilized charge of the capacitor by controlling the voltage doubling  in the throttle through which the charging current flows follows, the control signal for the switching element that shorts the choke or parts of it, from ver same signal between the current voltage at the condenser gate and the adjustable setpoint to be stabilized tension is gained.

The choke and the charging capacitor form a series re sonanzkreis, by the switching elements for one Vibration is excited by means of the pulse Increase the transformer to the desired voltage leaves. Although the control is on in a favorable way the low-voltage side of the pulse transformer can, there is a precisely adjustable pulse amplitude de on the high voltage side. Any tension swan kungen the DC voltage source or the supply network zes can be precisely regulated.

The circuit according to the invention for a pulsed high voltage Power supply allows the demands for effec tiv energy transfer, low technological and mate rial effort, small space requirements and good stabilization connection. Due to the low losses of the Ver complex cooling systems can be omitted.

Due to the simple and interference-free construction, the High voltage supply easily in other devices such as Pulse lasers can be integrated.

The stabilization of the pulse high voltage works in the loading range of doubling the DC output voltage  voltage source. For example, if you use a sixth the maximum value for regulating the mains voltage fluctuations, so is the stabilized high voltage in the Set the upper third by changing the setpoint E. bar, or easy to control via a computer.

The high voltage capacitors remain between the Aufla high voltage free cycles. The compared to others Power supplies very short-term impulse effects beneficial to the life of high voltage components out.

The maximum value of the high voltage is determined by the output voltage of the DC voltage source and the translation ratio of the pulse transformer is determined.

The pulse transformer is operated as a step-down regulator or if it is omitted entirely, the inventive method can be used Process also stabilized, low-voltage current impulses are generated. In further training the Erfin can be checked by appropriate load-side control measurements controlled and a further high voltage generation high security standards can be guaranteed.

The principle of the invention allows very small com compact pulse power supplies with medium power in 10 kW area to build. Pulse repetition frequencies up to approx. 1 kHz are possible. Also for higher medium outputs and higher pulse repetition frequencies is that of the invention Suitable circuit. A synchronization of the power supply and the laser pulse with other devices is down to the nano  range of seconds possible via an internal trigger input Lich.

Individual modules of the circuit according to the invention can each with two or different configurations be provided several times in parallel in this way for example circuits with an even higher output power to generate or at the same time stabilized high chip generate impulses of different amplitudes.

Other advantageous developments of the invention are in the subclaims or are identified below along with the description of the preferred embodiment the invention with reference to the figures. These show a preferred embodiment of the Invention appropriate circuit. Show it:

Fig. 1 shows an embodiment of the inventive circuit in a block diagram,

FIG. 2 shows a detailed illustration of the exemplary embodiment according to FIG. 1 and FIG. 3 shows a variant of the exemplary embodiment according to FIG. 2 .

In the embodiment shown in FIG. 1, the high-voltage pulse supply according to the invention is integrated in a pulse gas laser source.

The output of a DC voltage source G is connected via a switch element V 1 to a choke D and this can be short-circuited in whole or in part by means of a further switch element V 3 . The second connection of the choke D is at the input of a rectifier element 2 , which is connected on the output side to a capacitor K. A voltage doubler circuit is hereby formed, since the energy stored in the inductor D charges the capacitor K to a value which is up to twice the voltage of the DC voltage source G. The value of the voltage across the capacitor K, (charging voltage U _k ), together with an adjustable, highly stabilized setpoint voltage E, serves as an input variable for a control circuit S for controlling the switch element V 3 . The capacitor K is connected to the primary winding of a pulse transformer T via a further scarf element V 2 . The switch elements V 1 and V 2 are activated one after the other at a predetermined time interval by the output signal of a control circuit 1 .

In operation, in the illustrated embodiment, the high-voltage supply integrated in a pulse gas laser - starting from the 6-pulse diode rectifier terbrücke G with filter capacitor (1.5 mF) through the thyristor V 1 (with protective diode) and the choke D (1 , 25 mH) and the rectifier diode 2 , the capacitor K (66 µF) are charged to a maximum of twice the input DC voltage G in up to approx. 900 µs. Since the inductor D represents part of a resonant circuit through the connection to a capacitor, a partial oscillation is formed.

If a partial voltage U _t derived by voltage division from the charging voltage U _k reaches the value of the comparative voltage E, the charging process is interrupted by igniting the fast thyristor V 3 which switches off the choke and thus stabilizes the charging voltage U _k regardless of mains voltage fluctuations. The energy of the capacitor K is resonantly transmitted to the high-voltage capacitor (70 nF) of the downstream pulse gas laser via the pulse transformer T (transformation ratio approx. 1:30) by a time-delayed (around 1 ms) triggered fast thyristor V 2 .

The target voltage of the high-voltage pulses to be observed is connected to the capacitor K by a factor of one Output voltage divider multiplied by the over setting ratio of the pulse transformer is greater than that Comparative voltage E. This allows the amplitude of the high voltage pulses with a low, easy to handle voltage can be influenced.

By igniting the laser, the high voltage condenser Discharge sator so that the high voltage is only about 30 µs long is present. The only brief impulse load of the high chip Components have a favorable effect on their service life. The maximum possible repetition rate of execution game is almost 1 kHz. The high voltage supply is located directly next to the laser discharge unit arranges, making the laser head no long high voltage supply lines required and the dangers due to high reduce tension. Interference from the laser discharges have no influence on the operation of the high voltage ver care.  

The efficiency of the high voltage supply is better than 85%. The fluctuations in high voltage from pulse to The impulse is less than 1%. The setting range of the stabilized output voltage is between 18 and 27 kV. Also the exact triggering of the laser impulses easily caused by other lasers or events be solved. Building the stabilized pulsed high Power supply as an independent device is also possible.

The circuit shown in Fig. 2 shows in more detail form the embodiment which is shown in Fig. 1 as a block diagram. The DC voltage source G is designed as a power supply unit, wherein chokes Dr ₁ to Dr _{3 are} each connected to one phase of a three-phase network. A filter capacitor C ₁ / C _{2 is} charged via a rectifier bridge G ₁ to G ₆ , which for voltage reasons consists of two capacitors C ₁ and C ₂ connected in series, each of which has a resistor R ₁ and R ₂ connected in parallel. The controllable rectifiers V ₁ and V ₂ , which are arranged upstream of the inductor D ₃ or behind a capacitor C ₃ , are each provided with an antiparallel connected diode G ₈ or G ₉ , which reloads on the corresponding voltage peaks Capacitors C ₁ / C ₂ or C ₃ allows. The diode 2 between the inductor D ₂ and the capacitor C ₃ blocks the current reflux from the capacitor C ₃ in the capacitor C ₃ discharging direction.

The thyristor V ₃ is controlled via an isolating transformer Tr when an adjustable comparative voltage on a comparator 3 is equal to the voltage voltage divider falling on a part of a voltage divider (resistors R ₄ to R ₆ ) forming resistor R ₆ . The partial voltage at the resistor R ₆ corresponds to the supply voltage of the high-voltage pulses present on the secondary side of the pulse transformer T, taking into account the translation ratio of the pulse transformer T and the division ratio of the voltage divider R ₄ to R ₆ .

The amplitude of the high-voltage pulses can thus be changed by changing a substantially lower reference voltage (arrow towards block E). The output of the pulse transformer T is connected to the laser source L via an identical rectifier diode G ₇ . The secondary winding of the pulse transformer T is grounded to a center tap. The laser source L is combined with the power supply circuit to form an assembly, so that the connection between the pulse transformer T and the laser source can be kept very short. The entire assembly is only to be connected to the supply network with a power cable.

In the embodiment shown in FIG. 2, the choke is connected to the potential of the filter capacitors C ₁ / C ₂ only during the times in which the thyristor V _{1 is switched} through. In the embodiment shown in Fig. 3, a simplification is provided, which can be made when no potential separation between the inductor D and the capacitors C ₁ / C _{2 is} necessary. In this case, the thyristor V _{1 is combined} with the diode 2 of the embodiment of FIG. 2. There is also no G ₈ judge.

As a further variant, a return from the laser source L to the control part 1 is provided, the number of pulses, ie the number of control cycles, for the circuit being able to be varied as a function of load parameters. In this way, the high-voltage power provided can be adapted to actual requirements within wide limits. For example, the number of stabilized pulses made available can be changed between 0 and the required maximum number.

The invention is not restricted in its implementation to the preferred embodiment given above game. Rather, a number of variants are conceivable which of the solution shown also in principle makes use of different types.

Claims (15)

1. Circuit for the stabilized generation of high-voltage impulses at a predetermined rate, starting from a DC voltage source (G) with a first switch element (V 1 ), the clocked at the predetermined rate via a choke (D) a downstream capacitor (K) in ei ner voltage doubler circuit thus formed, which is then discharged via a subsequent further switch element (V 2 ) and delayed also in time with the predetermined rate via the primary winding of a pulse transformer (T), on the secondary side the high voltage pulses are present, characterized in that for Charging the capacitor (K) to a constant voltage below twice the voltage of the DC voltage source, a circuit for controlling the choke (D) through which the charging current flows is provided in a freewheeling state as soon as this voltage has reached a predetermined value, taking into account the Translation ratio ltnisses of the pulse transformer (T) corresponds to the nominal voltage of the high voltage pulses. 2. Circuit according to claim 1, characterized in that the free-running state of the inductor (D) by short-circuiting the entire winding or parts thereof by means of a switch element (V ₃ ), controlled by a control signal derived from the charging voltage of the capacitor (K), is produced. 3. A circuit according to claim 2, characterized in that the control signal for the switch element (V ₃ ), which shorts the inductor (D) or parts of it, by means of a comparator ( 3 ) from the comparison signal between the current voltage at the capacitor (K) and an adjustable stabilized setpoint voltage (E) is derived. 4. Circuit according to one of the preceding claims, characterized in that the Se secondary winding of the pulse transformer (T) is divided. 5. Circuit according to one of the preceding claims, characterized in that an An tapping the secondary winding of the downstream pulse transformer (T) is grounded. 6. Circuit according to one of the preceding claims, characterized in that the Kon capacitor (K) in its capacity switchable and preferred is resonantly adapted to the load. 7. Circuit according to one of the preceding claims, characterized in that as  DC voltage source (G) a battery, a solar cell device or a mains rectifier circuit with sieve capacitors is provided. 8. Circuit according to one of the preceding claims, characterized in that the highly stabilized setpoint voltage (E) digital or analog is adjustable. 9. Circuit according to one of the preceding claims, characterized in that the switch elements (V ₁ , V ₂ and V ₃ ) are formed by at least one controllable semiconductor component, in particular a thyristor, or at least one electron tube. 10. Circuit according to one of the preceding claims, characterized in that at least one switch element (V ₁ , V ₂ ) is an opposite polarity to the forward direction of the switch element diode (G ₈ , G ₉ ) is connected in parallel. 11. Circuit according to one of the preceding claims, characterized in that the rate the impulses change depending on a load parameter is derbar.   12. Circuit according to one of the preceding claims, characterized in that high On the voltage side, at least one more, one controllable Throttle having freewheeling circuit is provided. 13. Circuit according to one of the preceding claims, characterized in that with a laser source (L) a common spatially together summarizes assembled assembly forms. 14. Circuit according to one of the preceding claims, characterized in that the at closed load one with the high voltage pulses has to be charged capacitor. 15. Circuit according to one of the preceding claims, characterized in that the Im pulse transformer works in resonance.