DE102007046902A1 - Impulse generator for shock-wave therapy device, has capacitors charged by charging units comprising switch such that charging voltages developed at capacitors are partially compensated based on polarity of capacitors by series connection - Google Patents

Abstract

The generator (12) has a flashover unit for producing breakdown voltage. Capacitors (14.1-14.10) are connected in series and are arranged electrically in parallel to a flashover gap (13). The capacitors are charged by charging units (18.1-18.10) comprising a switch in such a manner that charging voltages (22.1-22.10) developed at the capacitors are partially compensated based on polarity of the capacitors by a series connection. Pole changing braces (15.1-15.5) are formed to change a pole of the capacitors. A damping current path is formed parallel to the capacitors.

Description

The The invention relates to a pulse voltage generator according to the preamble of claim 1 and a shock wave therapy device with a pulse voltage generator.

State of the art

at an electro-hydraulic shock wave generation is in an aqueous Medium of a therapy head generates a kind of steam explosion. This happens by an electrical discharge. This is done on two electrodes a comparatively high voltage, z. B. in the range of 5 kV-25 kV, what a sparkover entails. The energy of the spark must be so great that there is an explosive evaporation of the aqueous Medium is coming.

critical it is that a sparkover within a comparatively short time of about 0.5 μsec.-1 μsec. a comparatively high performance. For this, the currents flowing in this time must have values of a few kiloamperes.

In In practice, the flashovers are repeated at a frequency of a few Hertz up to approx. 10 Hz.

A known method for generating a sparkover is a Charge the capacitor to a high voltage. This loaded Capacitor is then over a switch on the spark gap, whereby the spark rolls over. Of the charged capacitor, the switch, the wire to the spark gap as well as the spark gap itself are referred to as "surge circuit". Of the Capacitor is also called "surge capacitor" or "surge capacity.

At a switch in the "surge circuit" are extreme requirements to deliver. It does not just have the high levels of capacitor voltage for spark release can lock but also switch through quickly and then a current pulse of lead a few kilo ampere can.

in the Interplay of the surge capacity of the surge circuit with a line inductance results in a resonant circuit with a weakly damped oscillation at the spark gap. Since the peak value of the current z. B. 5 kA can achieve cost reasons, regularly no power semiconductor switch but uses vacuum switches, called "thyratrons" or "spark gaps". Although these are cheaper than semiconductor switches, but wear it. Furthermore they are only available from a few suppliers and are subject to one Close observation, since they are also used for the construction of nuclear explosive devices can be.

to Avoidance of the extreme load of the "switch" for switching a "surge capacitor" is a circuit arrangement known, in which two high-voltage capacitors are used. The first represents a precharge capacitor, which forms the second the actual surge capacitor.

Of the Vorladekondensator is initially on a Precharge circuit charged to a high voltage, the surge capacitor then unloaded. Precharge and surge capacitor are over a Throttle and an electronic switch connected. When the electronic switch is closed, the pre-charge capacitor, the choke and the surge capacitor a resonant circuit, the so-called "Umladekreis". Due to the resonant circuit current is the Charge transferred from the pre-charge capacitor to the surge capacitor, wherein such a high voltage at the surge capacitor that arises for ignition a sparkover in the circuit leads. The vibration behavior in Umladekreis is chosen such with a resonant frequency of z. B. 20 kHz that the resonant circuit current remains at a relatively low level. The switch must then Although still be able to lock a high voltage, but far from it switch more quickly and only a comparatively small current handle. There is the possibility Power semiconductor switch, z. B. thyristors or thyristor combinations apply. Even such semiconductor switches are still comparatively expensive.

Purpose and advantages of the invention

Of the Invention is based on the object, a relatively less expensive Pulse voltage generator and a shock wave therapy device equipped therewith provide.

These The object is solved by the features of claim 1, 5 and 12.

In the dependent claims are advantageous and expedient developments of the invention.

The invention is based on a pulse voltage generator for a shock wave therapy device with a flashover path in a liquid medium, in which spark rollover means are provided for generating a flashover voltage and the spark rollover means comprise a voltage source, at least one capacitor and at least one switching element. The essence of the invention lies in the fact that several in Series switched capacitors for electrically parallel arrangement of the spark gap are provided that charging means are provided, with which the capacitors are chargeable such that seen at the capacitors charging voltages due to their polarity over the series circuit at least partially compensate, and that Umpolmittel are formed in order to be able to reverse-poling at least one of the capacitors.

This Approach is based on the basic idea, a high-voltage component, z. B. a capacitor for Replace 10,000 V with several components connected in series, thus each must be able to withstand only a portion of the high voltage.

The Another finding is that a charge of those in series switched capacitors to achieve a flashover voltage initially in a polarity of charging voltages is done in such a way that At least partially cancel charging voltages and ideally cancel them completely. This is not the amount of addition at the series circuit the charging voltages, but a much smaller value. Ideally is the Voltage value zero.

The As a result, at the spark gap in the ideal case even after the charge of the capacitors no voltage is applied, although the complete "impact energy" in the individual Capacitors are stored due to the polarity at the spark gap but does not appear.

The energy stored in the capacitors is made available for the spark gap, in the charge voltages of the capacitors are brought to the same polarity become. In this case, then add the charging voltages the individual capacitors connected in series to a total voltage, which rests against the spark gap and at the appropriate height to a Flashover leads. Since a "surge capacitor" according to the invention to several is divided into series connected capacitors and charging and Umpolmittel can also be broken down, so that circuit components Never see the full overall voltage can be significantly more cost effective Components are used.

In a particularly preferred embodiment of the invention the Umpolmittel connected in parallel to a umzupolenden capacitor Series connection of a switch and an inductance. Together with the capacitor, a resonant circuit is formed by this measure, the by closing of the switch "in Be set " can. By a vibration process in the resonant circuit, the voltage reloaded on the capacitor. Preferably, a control device is provided, with which all switches of Umpolmittel closed simultaneously can be so that with appropriate dimensioning of the components to one point in time all individual voltages at the capacitors to one Add total voltage, which causes a sparkover.

These Switching the Umlademittel has the advantage that the maximum Voltage on which the components must be designed, the charging voltage at the individual Capacitor of the series connection is. For example, 10 capacitors connected in series with an intended ignition voltage of 10,000 V. a switch instead of the 10,000 V, as in a conventional one Circuit, only 1,000V can switch. This can be conventional Semiconductor switch, z. B. use thyristors. Will the resonant circuit from capacitor and inductance with high quality designed so low ohmic losses, the amount corresponds the capacitor voltage after a Umschwingvorgang approximately the amount of voltage before the transient. Ie. the total voltage after the Umschwingvorgang results from an addition of the amounts of the charging voltages, on which the capacitors of the series connection before the Umschwingvorgang were charged.

One Another essential aspect of the invention is that parallel for at least one capacitor a damping current path is formed, which has a diode characteristic which is a primary sparkover voltage locks and includes at least one energy-absorbing element.

This Approach is based on the knowledge that training a sparkover with the desired shockwave practically only the first half-wave of the spark current contributes. Further Cause vibrations only to an undesirable Burning of the electrodes, between which the spark is formed or have a disturbing Electrolysis of the aqueous Medium and an undesirable heat input into the watery Medium result. Through the damping current path further half-waves are greatly reduced after the first half-wave, causing unwanted effects on electrodes, electrolysis and heating when used in a Therapy head are greatly reduced. The electrodes, a total of one Whole therapy head, thereby have a longer life, which cost advantages brings.

In the simplest case, the attenuation path consists of a series connection of an inductance, an ohmic resistance and a diode. The diode is poled so that the damping current path for the first quarter-wave of the voltage is unaffected, since during this time the voltage on the capacitance in the reverse direction of the diode is poled. In the second quarter period, this voltage becomes negative and the diode begins to conduct. This results in a current flow through the damping current path, which leads to a strong removal of energy from the "surge circuit" with suitable dimensioning of the inductance and the ohmic resistance.

By this procedure remains a performance in the spark gap in the first half-wave of the current practically unchanged, whereas subsequently from the "surge circle" considerably energy is removed from the brake circuit.

In A preferred embodiment of the invention is instead of the ohmic Resistance in the damping current path a capacitor is provided. The effect is similar to the ohmic inductive Damping current path. The advantage, however, is that the energy removed from the "surge circuit" is now not converted into heat in ohmic resistance, but in the capacitor is stored.

A leaves such a course itself on both a conventional Training of a "circle of shocks", consisting of a Capacitor, an inductance and a switching element and a spark transmission path as well the disjointed arrangement of capacitors with corresponding charging and Umpolmitteln apply.

In A preferred embodiment of the invention is the damping current path parallel to each two capacitors in the series circuit of Capacitors. Preferably, these are capacitors that are charged "antiparallel".

in the Further, it is preferable that each capacitor has two damping current paths assigned. By this measure can the damping current paths simultaneously to charge the capacitors to alternating charging voltages be used.

in the In the simplest case, however, the charging means comprise circuit branches with a diode so that each capacitor is connected in series with a source of energy, but different polarized capacitor voltages occur when charging via the power source.

at In one embodiment, ohmic resistances are required in the diode branches. but the disturbing heat loss cause. To heat loss to avoid, it is further suggested that the charging means Include switches that are controlled so that they during the charging process the capacitors are closed, but then open so that the full voltage the series connection of capacitors after a Umschwingvorgang can be effective.

drawings

Several Examples of the invention are shown in the drawings and will be given with further benefits and details below explained in more detail. It demonstrate

1 A first embodiment of a schematically illustrated pulse voltage generator with spark gap,

2 a further embodiment in a corresponding representation as in 1 .

3 the basic circuit of a pulse voltage generator with a spark gap and a damping current path,

4 a modified embodiment of the in 3 .

5a a voltage and current waveform of a spark gap of a shock wave therapy device for a pulse voltage generator without damping current path and

5b the current and voltage curve at the spark gap according to 5a associated course of performance.

6a and 6b the corresponding courses of current and voltage ( 6a ) as well as the performance ( 6b ) at the spark gap in the presence of a damping current path,

7 a third embodiment of a pulse voltage generator with spark-over gap and damping current paths,

8th a variant of the embodiment according to 7 .

9 one too 1 corresponding representation, wherein a possibility of the circuit-technical module formation is symbolized by hatched fields and

10 a conventional circuit for a pulse voltage generator with spark gap.

Description of the embodiments

A known embodiment of a circuit arrangement 1 according to 10 with indicated spark gap 2 for use in a shock wave Therapy device comprises two high-voltage capacitors 3 . 4 , of which the first capacitor 3 a charging circuit 5 from a voltage source 6 and a charging resistor 7 and the second capacitor 4 a circuit 8th with the spark gap 2 and a line inductance 9 assigned.

The capacitor 3 is initially at an open switch 10 over the charging resistance 7 charged to the voltage of the voltage source, z. B. to 10 kV. The capacitor 4 is still unloaded. The capacitor 3 and capacitor 4 are over a throttle 11 and the switch 10 connectable with each other. Will the switch 10 closed form the capacitor 3 , the throttle 11 and the capacitor 4 a resonant circuit. Due to the resonant circuit current, the charge from the capacitor 3 on the capacitor 4 reloaded, leaving the capacitor 4 reached an ignition voltage for a sparkover on the spark gap. This leads to the ignition of a spark at the spark gap 2 ,

In this prior art, the switch needs 10 be designed for the high voltage, to which the capacitor 3 is charged. There are also two high voltage capacitors 3 . 4 required in the circuit design.

Either the capacitors as well as the switch are comparatively expensive Components.

Such Components are avoided in a circuit structure according to the invention.

1 shows the circuit arrangement 12 a pulse voltage generator and a schematically indicated spark gap 13 , The circuit arrangement 12 includes 10 series connected capacitors 14.1 - 14:10 , Every second capacitor 14.2 . 14.4 . 14.6 . 14.8 such as 14:10 is a transhipment branch 15.1 - 15.5 assigned.

Each transshipment branch 15.1 - 15.5 consists of a throttle 16 and a thyristor 17 ,

For charging the capacitors 14.1 - 14:10 are charging branches 18.1 - 18:10 intended. Each charging branch consists of an ohmic resistor 19 and a diode 20 , About z. B. the charging branches 18.1 - 18.2 become the capacitors 14.1 . 14.2 to a voltage U _{L of} a voltage source 21 charged so that the charging voltage at the capacitor 14.1 opposite polarity to the charging voltage at the capacitor 14.2 is etc .. Overall, the polarity of the charging voltages alternates (arrows 22.1 - 22:10 ), so that after a charging process in the series circuit, the capacitors 14.1 - 14:10 the voltage is zero. The capacitor 14.1 for example, via the charging branch 18.1 charged, whereas capacitor 14.2 over the charging branches 18.1 and 18.2 is charged to reverse polarity.

Once all the capacitors 14.1 - 14:10 are charged, the thyristors 14 in the transshipment branches 15.1 - 15.5 ignited, resulting in a swinging of the charging voltages of the associated capacitors. This causes an addition of the individual charging voltages 22.1 - 22:10 to the total voltage (arrow 23 ), causing a sparkover at the spark gap 13 generated. A disadvantage of this embodiment is that with increasing distance to the voltage source 21 the charging process by adding ohmic resistors 19 is different for the different capacitors, which do not exactly compensate for the voltages on the capacitors during charging, resulting in a total voltage 23 at the spark gap, which is not exactly zero during the charge. Although this leads to no spark, but to an undesirable gas formation in the liquid medium of the spark gap.

In 2 This "unbalance" is avoided by having all diodes of one base resistor 24 starting from or are connected to such. Otherwise, the structure is the charging branches 18.1 - 18:10 identical as in 1 , This also applies to the arrangement of Umladezweige 15.1 - 15.5 ,

Around the first half-wave of a current over the spark gap essential In a circuit arrangement, a damping current path can be used to be built in.

The function of a damping current path will be described below with reference to FIG 3 and 4 respectively. 5a . 5b such as 6a and 6b illustrated.

The 3 and 4 are a section of the known circuit arrangement 1 according to 10 , wherein in the respective circuit section 25 a damping current path 26 . 27 is used.

Instead of a known solution in which one or more diodes are inserted into a surge circuit to pass the first half-wave and then block another current flow, in this solution the damping current path is switched in parallel to a "surge capacitance". The damping current path 26 In the simplest case, it consists of a series connection of an inductance 28 , a diode 29 as well as an ohmic resistance 30 , The first quarter wave of the current flow at the spark gap is not affected by the damping current path, since during this time the voltage at the surge capacity 31 > 0 and therefore the diode 29 locks. In a second quarter period will be the voltage however negative and the diode 29 begins to lead. This results in a current flow through the damping current path 26 , whereby with suitable dimensioning of the inductance 28 and the ohmic resistance 30 the surge circuit from impact capacity 31 , Spark gap 32 and a line inductance 33 Energy is withdrawn. By this measure, the spark gap 32 "Spared". Specifically, unwanted effects on electrodes, electrolysis of an aqueous medium in which the spark is formed and heating of a therapy head, in which the spark gap is used in the application, significantly reduced.

In 5a is the course 34 of the current over the spark gap 32 as well as the course 35 the voltage at the spark gap for the case without damping current path in a diagram.

Corresponding to the diagram according to 5a is 5b with the course 36 the power at the spark gap.

This picture changes dramatically when the damping current path 26 is used. 6a shows the current flow 34 as well as the voltage curve 35 at the spark gap 32 , In addition, the course 37 of the current through the damping current path 26 shown.

By the flow of current through the damping current path 26 becomes the spark gap 32 Energy deprived, which is not required for a shock wave effect, however. The course of the power at the spark gap when using a damping current path 26 is in 6b to see. The first half-wave of the performance curve is essentially unchanged. Thereafter, the power is desirably reduced to relatively small values. For example, in a surge circuit without a damping current path 26 an energy of 7.85 J implemented, which corresponds to 95% of the energy in the surge capacity 31 is stored. Using the snubber circuit, the energy dissipated in the spark gap is reduced to 2.59 J, which is 31% of the total energy.

In 4 comes a damping current path 27 for use in which instead of the ohmic resistance 30 a capacitor 38 is provided. The effect of this damping current path 27 is comparable to the damping current path 26 , The advantage is that the energy extracted from the surge circuit is not in ohmic resistance 30 is converted into heat, but storage in the condenser 38 he follows. In principle, this energy can then be recovered by additional circuit components (not shown) in an additional step.

The 3 and 4 show the application of a damping current path 26 . 27 in a circuit arrangement 1 with a surge capacitor 31 , However, a corresponding damping current path can also be used for a series circuit of capacitors, in which z. B. the damping current path is connected in parallel via two capacitors connected in series.

In such an arrangement, the damping current path can simultaneously be the task of a charging branch 18.1 - 18:10 take.

A corresponding embodiment of a circuit arrangement 39 a pulse voltage generator with indicated spark gap 13 is in 7 shown.

According as in the circuit arrangement 1 respectively. 2 are 10 capacitors 14.1 - 14:10 provided with Umladezweigen 15.1 - 15.5 , The charging branches 18.1 - 18:10 are compared to the circuit arrangements according to the 1 and 2 However, now replaced by a "two-pole", which is the task of charging the capacitors 14.1 - 14:10 and at the same time that of a damping current path 26 . 27 takes over.

For charging the capacitors 14.1 - 14:10 again serves a voltage source 21 ,

To two capacitors, z. B. 14.1 . 14.2 lie parallel connected two poles 40.1 . 40.2 , The charging circuit is over another two pole 41 , consisting of a series connection of ohmic resistors 42 to the voltage source 21 closed. The charge of the capacitor 14.1 takes place for example via the bipoles 40.1 . 40.3 . 40.5 . 40.7 . 40.9 such as 41 , The charge of the capacitor 14.2 takes place via the same two poles with the omission of the dipole 40.1 , This causes the charging voltages 22.1 and 22.2 differently poled. Overall, the charging voltages 22.1 - 22:10 polarized alternately, so that a total voltage at the spark gap 13 after loading zero.

By activating the reload branches 15.1 - 15.5 becomes the polarity at the respective capacitors 14.2 . 14.4 . 14.6 . 14.8 and 14:10 reversed, causing the spark gap 13 the full spark voltage is applied, which causes a flashover.

The two poles 40.1 - 40.9 each have a diode connected in series 29 , an ohmic resistance 30 as well as an inductance 28 on.

The diodes 29 ensure that during the construction of the breakdown voltage at the spark gap the two poles 41.1 - 40.9 lock. As soon as However, a Umschwingvorgang the capacitor voltages at the respective two-pole in the opposite polarity occurs, the two poles occur 40.1 - 40.9 as damping current paths in appearance, in which energy from the capacitors 40.1 - 40.10 in the respective two-pole 40.1 - 40.9 is consumed.

An evolution of the circuit of 7 provides 8th Here was the two pole 41 with the ohmic resistances 42 replaced by a series of thyristors 43.1 - 43.5 during a charging process of the capacitors 14.1 - 14:10 direct, but then lock. This measure can affect the resistors 42 completely dispensed with, so that the charging process can take place without loss. To not short circuit a voltage source when the thyristors 43.1 - 43.5 is the voltage source through a power source 44 replaced with impressed current. Basically, instead of a power source and a voltage source with ohmic internal resistance, an electronic circuit, for. B. a Gleichstromsteller- or DC converter circuit or a rectifier cascade circuit can be used.

The inventive procedure of dividing a single surge capacitor into a plurality of individual capacitors with a corresponding charging circuit and possibly a damping current path results in the further advantage that a modularization of a circuit arrangement 12 or 39 can be made, which greatly simplifies a realization of a circuit structure and ultimately brings cost advantages.

Based on the configuration of the circuit arrangement 12 according to 1 is in 9 illustrates a modularization of the circuit.

Out 9 is shown by hatched areas, which components of the circuit 12 Components of a module can represent, in such a way that depending on the desired spark voltage more or fewer modules are interconnected.

In 9 is the circuit arrangement 12 in five modules 45.1 - 45.5 divided, wherein in each module two capacitors, z. B. in the module 45.1 the capacitors 14.1 and 14.2 are summarized. Included in the respective module is then an associated reloading branch of the reloading branches 15.1 - 15.5 and the associated charging branches, z. B. for the first module, the charging branches 18.1 such as 18.2 ,

Each module has six contact interfaces for this division 46.1 - 46.6 , where only the module 45.5 Contact interfaces 46.4 such as 46.6 remain unused. A corresponding modular distribution is also for the circuit arrangement 39 possible or according to a circuit arrangement 8th , For example, in a module, two capacitors each, the associated Umladezweig and two associated two poles for the charge and the realization of the damping current path are included.

One Modular construction has the advantages, that modules configured, for example, each on a circuit board can be which can be cascaded. For example, a module can be designed that the capacitors are precharged to +1 kV or -1 kV and after the swinging over a voltage of 2 kV is available. One needs a high voltage pulse generator for a voltage of 10 kV, so will be five such modules connected in series. At another predetermined Voltage is simply adjusted to the number of modules. The series connection of capacitors to produce a total surge capacity with appropriate circuitry The single capacitors has the advantage that only components for one comparatively low voltage, z. <1000V, rather than 10,000V can be the easily available and cost-effective are.

In particular, instead of an expensive switch for a circuit arrangement 1 to 10 a larger number of significantly cheaper thyristors are used.

It can For example, "low-power" extremely low-cost thyristors in plastic housing be used.

When using a damping current path, in particular of several distributed damping current paths according to the 7 and 8th the "spark gap" is spared, since an electrode burn, gas formation as a result of electrolysis and heating of a therapy head, for which such a circuit arrangement is used, can be reduced.

Claims (12)

Pulse generator ( 1 . 12 . 39 ) for a shock wave therapy device with a spark gap ( 2 . 13 . 32 in a liquid medium in which spark rollover means are provided for generating a rollover voltage, the spark rollover means being a source of energy ( 6 . 21 . 44 ), at least one capacitor ( 3 . 4 . 14.1 - 14:10 . 31 ) and at least one switching element ( 10 . 17 ), characterized in that a plurality of series-connected capacitors ( 14.1 - 14:10 ) to the electrically parallel arrangement to the spark gap ( 13 ), that charging means ( 18.1 - 18:10 . 40.1 - 40.9 ) vorgese with which the capacitors ( 14.1 - 14:10 ) are chargeable in such a way that on the capacitors ( 14.1 - 14:10 ) occurring charging voltages ( 22.1 - 22:10 ) due to their polarity over the series connection at least partially compensate, and that Umpolmittel ( 15.1 - 15.5 ) are formed to at least one capacitor ( 14.2 . 14.4 . 14.6 . 14.8 . 14:10 ) to be able to reverse polarity. Generator according to claim 1, characterized in that the polarity reversal means ( 15.1 - 15.5 ) are designed to umzupolen capacitors whose voltage have the same polarity. Generator according to one of the preceding claims, characterized in that the polarity reversal means to be umzupolenden a capacitor ( 14.2 . 14.4 . 14.6 . 14.8 and 14:10 ) connected in parallel series connection of a switch ( 17 ) and an inductance ( 16 ). Generator according to one of the preceding claims, characterized in that a control device is provided, the switch ( 17 ) of the polarity reversal agent ( 15.1 - 15.5 ) to switch. Generator according to the preamble of claim 1, in particular one of the preceding claims, characterized in that parallel to at least one capacitor ( 14.1 - 14:10 ) a damping current path ( 40.1 - 40.9 ) having a diode characteristic which blocks at a primary sparkover voltage and comprises at least one energy absorbing element. Generator according to one of the preceding claims, characterized in that the damping current path ( 40.1 - 40.9 ) a consumer ( 30 ) owns. Generator according to one of the preceding claims, characterized in that the damping current path ( 40.1 - 40.9 ) an inductance ( 28 ) as well as an ohmic resistance ( 30 ) and / or a capacitor ( 38 ). Generator according to one of the preceding claims, characterized in that the damping current path ( 40.1 - 40.9 ) is parallel to two capacitors each. Generator according to one of the preceding claims, characterized in that each capacitor ( 14.1 - 14:10 ) are associated with two damping current paths. Generator according to one of the preceding claims, characterized in that the charging means comprise circuit branches ( 18.1 - 18.2 ) with a component ( 20 ) with diode characteristics, so that each capacitor ( 14.1 - 14:10 ) of the series connection with an energy source ( 21 ), but differently polarized capacitor voltages ( 22.1 - 22:10 ) at a charge via the energy source ( 21 ) arise. Generator according to one of the preceding claims, characterized in that the charging means switch ( 43.1 - 43.5 ) which are controlled so that they are closed only during the charging process. Shockwave therapy device with a pulse generator according to one of the preceding claims.