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EP0233191B1 - Circuit for regulating the high-voltage supply of an electrostatic filter - Google Patents

Circuit for regulating the high-voltage supply of an electrostatic filter Download PDF

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Publication number
EP0233191B1
EP0233191B1 EP86902787A EP86902787A EP0233191B1 EP 0233191 B1 EP0233191 B1 EP 0233191B1 EP 86902787 A EP86902787 A EP 86902787A EP 86902787 A EP86902787 A EP 86902787A EP 0233191 B1 EP0233191 B1 EP 0233191B1
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EP
European Patent Office
Prior art keywords
voltage
current
output
arrangement according
circuit arrangement
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Expired
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EP86902787A
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German (de)
French (fr)
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EP0233191A1 (en
Inventor
Helmut Domann
Karl-Heinz HÄGELE
Hartmann Rupp
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/66—Applications of electricity supply techniques
    • B03C3/68—Control systems therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S323/00—Electricity: power supply or regulation systems
    • Y10S323/903—Precipitators

Definitions

  • the invention relates to a circuit arrangement for regulating the high voltage supply of an electrostatic filter operating in a soot switch according to the preamble of claim 1.
  • Such a circuit arrangement is known from WO 80/02583.
  • a soot separator for an internal combustion engine is described there.
  • a high voltage is generated by means of an inverter, a transformer and a rectifier.
  • the level of the DC voltage depends on the particle flow of the desired filter effect and the type of internal combustion engine.
  • the possible voltage range is 100 V - 10,000 and more (page 11, lines 13 to 17).
  • electrostatic filters which are used in industrial plants for the separation of dust particles from exhaust gases. These electrostatic filters are connected to high-voltage supplies, the voltage of which is regulated. The output voltage is fed to a regulator that controls the high voltage. A suitable high voltage can easily be generated for the electrostatic filters used in industrial plants due to the existing mains voltage.
  • These known circuit arrangements are not suitable for use in motor vehicles, where only a direct voltage of, for example, 12 volts is present as on-board voltage, for the high-voltage supply of soot switches used in industrial plants.
  • the electrostatic filter is operated in very different areas in the motor vehicle. Throughput, composition, soot loading, moisture and temperature of the exhaust gas change strongly in the entire speed and load range of the engine and in the transient operation of the engine with rapid change. The impedance of the discharge and the breakdown limit of the discharge strongly depend on these parameters and fluctuate accordingly.
  • the current fed into the filter and / or the operating voltage must be regulated accordingly to predetermined values or limited to the maximum permitted values in order to be able to guarantee proper functioning of the filter in the entire engine operating range in the long term. It should be noted that the electrostatic filters in motor vehicles, in particular, have to be operated unsteadily and with throughput fluctuations by a factor of 10, while the known filters in large-scale plants are operated essentially stationary with a fixed operating point.
  • the invention has for its object to achieve an optimal effect of the electrostatic filter in the entire operating range in a circuit arrangement of the type mentioned. This object is achieved in that the high-voltage output stage is a current source and the control circuit is designed to regulate the current fed into the filter.
  • the circuit arrangement according to the invention with the features of the main claim has the advantage that an optimal effect of the electrostatic filter in the entire engine operating range can be achieved with this control.
  • This quality criterion is met sufficiently well if it is ensured in the entire engine operating map that a certain basic current I G is always fed into the electrostatic filter.
  • the control circuit can then be designed very simply as a fixed value controller for the control variable filter operating current.
  • the regulation of the high-voltage supply is designed so that first of all attempts are made to regulate the basic current to a constant value which is largely independent of the engine operating point or other interfering influences. Only when the filter function has been fine-tuned can the output current, which forms the filter operating current, be additionally controlled as a function of the engine operating map.
  • a diode flyback converter can be used to generate a high voltage from a relatively low DC battery voltage, which enables the use of electrostatic filters in motor vehicles.
  • the high-voltage output stage is supplied on the primary side with a pulsating voltage, the pulse duty factor of which is set depending on the operating state of the soot switch. Monitoring the output voltage, the output current and the output power enables such a change in the pulse duty factor that predetermined maximum values are not exceeded, the power elements used are protected from destruction by a power limitation and the overall power consumption is kept as low as possible.
  • the diode flyback converter can be cascaded in several stages to increase the output voltage, the charging capacitor being able to be formed by the capacitance of the high-voltage cable on the output side. This eliminates the need for a special charging capacitor.
  • the primary winding of the flyback converter is preferably connected in series with a field effect transistor operated as an electrical switch, the control input (gate) of which is controlled by a pulse width modulator for setting the duty cycle.
  • the pulse width modulator changes the duty cycle so that the Output current and / or the output voltage and / or the output power of the high-voltage output stage are limited and kept within a predetermined working range.
  • the voltage drop of the switched-on, primary-side field-effect transistor can be used, since this transistor has a largely linear internal resistance when overdriven and thus the voltage drop across it between drain and source is proportional to the primary current.
  • the primary current should be limited to as high a value as possible, especially in the start-up phase. However, this must be smaller than the current that leads to the destruction of the field effect transistor. The higher the primary current during the start-up phase, the faster the output current and output voltage reach their operating values.
  • the filter is not switched off completely when a voltage breakdown occurs, but rather the operating current is reset or limited to a minimum current as quickly and briefly as possible. In this way, arcs that occur during breakdowns are quickly extinguished. However, a minimal function of the filter is still retained during the cut-off because the particles are still loaded by the minimal current.
  • limits are provided regarding the maximum current that can be fed into the filter and the maximum power and voltage that can be fed into the filter. Each of the three limits protects both the components of the high-voltage supply and the high-voltage components of the filter against overload.
  • the on-board electrical system is also protected by the power limitation from excessive power consumption by the electrostatic filter.
  • the additive feeding of the leakage current to the base current has the advantage that for each engine operating point and depending on the particular functionality of the isolator, the instantaneously, at least required operating current is fed into the filter.
  • This has the advantage that the vehicle electrical system is only loaded with the minimum required electrical power consumption by the filter.
  • the electronic power components can thus be designed for lower loads. The components are thus smaller, cheaper or can be partially saved entirely because the maximum leakage current that occurs is approximately 10 times greater than the leakage current averaged over time.
  • the additive feeding of the leakage current can be supplemented in the control circuit according to the invention in a particularly simple and therefore vehicle-compatible manner, because not the operating voltage but the filter current was selected as the control variable.
  • FIG. 1 shows the basic structure of a high-voltage supply for an electrostatic soot switch in the form of a greatly simplified block diagram.
  • An electrostatic soot switch 1 the construction of which is not the subject of the present invention, is supplied with the required high voltage by the output voltage U A of a high-voltage output stage 2.
  • the duty cycle T "of the output voltage U A, which is obtained by the ratio of pulse period T is defined with the period duration Tp, can be varied in function of the power P, the output voltage U A and the output current 1 8
  • the setting of the duty ratio T Takes place by means of a pulse width modulator 3, the output of which is connected to the control input of the high-voltage output stage 2.
  • the pulse width modulator 3 is in turn connected to a processing circuit 4 which monitors the power P, the output voltage U A and the output current I A.
  • the mode of operation of this circuit arrangement is described in more detail with reference to the more detailed block diagram shown in FIG.
  • a diode flyback converter 5 is essentially shown in FIG. transforms the voltage pulses generated on the primary side to the required high voltage on the output side.
  • the battery voltage U B is present at the primary winding P, while the other end of the primary winding P is connected to ground via a field effect transistor 6.
  • the field effect transistor 6 is operated as an electrical switch and for this purpose is switched on and off periodically by the pulse width modulator 3 at its control input G. The on and off times of the field effect transistor 6 determine the duty cycle of the primary voltage and thus also the level of the output current I A.
  • the secondary side of flyback converter 5 consists of three secondary windings S1 to S3 and three diodes D1 to D3.
  • One of the output voltage U A proportional voltage U A ' may be at the tap a voltage divider can be tapped, which consists of the resistors R1 and R2.
  • the resistor R3 is connected in series to the secondary side of the flyback converter 5.
  • a signal 1 A "proportional to the output power P A can, however, also be tapped at the drain terminal D of the field effect transistor 6.
  • the voltage occurring there during the switch-on phase T; is namely largely proportional to the current flowing on the primary side and thus also largely proportional to the secondary-side output power P A , since the volume resistance of the field effect transistor 6 between drain and source S is approximately constant in the forward mode.
  • the block diagram shown in FIG. 3 contains a high-voltage output stage 2, which consists of a power output stage 7 and a diode flyback converter 5.
  • the power output stage 7 is fed by a driver circuit 8, which in turn is controlled by a pulse width modulator 3.
  • the pulse width modulator 3 sets the pulse duty factor of the primary voltage at the diode flyback converter 5 and thus also the output power P A via the driver circuit 8, the power output stage 7.
  • the power limiter 9 operates as a function of the operating voltage U B and has a limiting effect on the pulse duty factor in the pulse width modulator 3.
  • the pulse width modulator 3 is also fed by a minimum selection circuit 11 with a control signal which is dependent on the output current and / or on the output voltage.
  • this or a signal proportional to it is fed to an impedance converter 14, which is connected on the output side to the breakdown detection circuit 12, a power limiter 15, which can be provided as an alternative to the power limiter 9, and to a differential circuit 16.
  • the power limiters 9 and 15 can each limit the power individually. It is therefore only necessary to use one of the two power limiters in a circuit.
  • the power limiter 15 receives a signal proportional to the output voltage U A as an input variable. It converts this into a current setpoint such that the output power does not exceed a certain value.
  • the difference circuit 16 forms the difference between a maximum value U Amax provided for the output voltage and the output signal of the impedance converter 14.
  • the difference signal is fed to a voltage regulator 17 which is connected on the output side to the minimum value selection circuit 11.
  • the breakdown detection circuit 12 consists of a differentiator 18 on the input side, which is followed by a comparator 19 with hysteresis.
  • the output of the breakdown detection circuit 12 is connected to an input of a start buckling control 20 and the input of an automatic best point 21.
  • the start-up break control 20 has the effect that after the voltage breakdown has occurred, the output current I A remains briefly at a value which has been reduced to such an extent that an arc which may have arisen extinguishes. At the end of the pause, the current is quickly ramped up again with a defined gradient.
  • the best-point automatic 21 causes the output current I A to be set to a somewhat lower value after the voltage breakdown than before the breakdown.
  • This best-point automatic 21 has the effect that the number of voltage breakdowns during operation is kept small and thus also the times with a reduced filter function.
  • the outputs of the best-point automatic 21 and the start-up buckling control 20 as well as the sum signal from the basic current I G and the creeping current I K occurring are fed to a second minimum value selection circuit 22 on the output side.
  • This minimum value selection circuit 22 also has two further inputs, at which the maximum value of the output current I Amax and the output of the circuit 15 serving to limit the power are present.
  • the output of the minimum value selection circuit 22 is connected to the positive input of a summer 23, at whose negative input the output current I A or a value proportional to it is present.
  • the output of the summer 23 is connected via a current regulator 24 to an input of the minimum value selection circuit.
  • the pulse width modulator 3 converts an analog voltage coming from the minimum value selection circuit 11 proportionally into a pulse of the duration T i , which is repeated at a constant repetition frequency.
  • the minimum value selection circuit 11 selects the smallest of the values present at its inputs in a manner known per se for the formation of the output signal fed to the pulse width modulator 3. In a corresponding manner, a minimum value selection takes place in the minimum value selection circuit 22. Its output signal also corresponds to the smallest input signal or is proportional to it.
  • the leakage current I K is the current flowing away at the insulator of the soot switch, while the base current I G is the portion of the current which flows off in the soot switch via the gas discharge.
  • the base current I G is responsible for the function of the soot switch, which can also be referred to as a soot filter.
  • the soot particles are charged by the base current I G and thereby agglomerated.
  • the basic current I G can be determined for a filter type and set permanently, or it can also be controlled as a function of the speed and load of the internal combustion engine.
  • the Filters the leakage current I K flowing out through the insulator can be fed in at any moment.
  • the output current I A is limited to a maximum permissible operating value by the fixed value I Amax . Depending on the dimensioning of the component, this value can be 10mA, for example.
  • the start-up kink control 20 has the task of immediately resetting the current setpoint to a minimum value Imin after a voltage breakdown. After briefly remaining at this minimum value Imin, the current setpoint I Asoll is rapidly brought up to the smallest of the current setpoints.
  • the best-point automatic 21 regulates the current setpoint as close as possible to the breakdown limit if the filter is operated close to the breakdown limit in special speed and load ranges. After each breakdown, the output of the start-up buckling control 20 is quickly lowered by a certain amount and then starts up again slowly until a new breakdown occurs. If there are no breakthroughs over a long period of time, this value becomes equal to the sum of I K and I G. In the event of a voltage breakdown, the output voltage U A collapses with a steep edge, this is detected by the differential circuit 18, which causes the comparator 19 to tilt when a threshold value is exceeded.
  • the voltage regulator 17 limits the output voltage U A to a maximum permissible value, for example to 17 to 18 kV.
  • the current-voltage diagram shown in FIG. 4 shows the maximum voltage, the maximum current and a power hyperbola P max .
  • the creeping current I K rises with increasing exhaust gas temperature, as a result of which the characteristics for the output current I A change accordingly. With increasing exhaust gas temperature or with increasing leakage current I K , the current-voltage characteristics become steeper.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Dc-Dc Converters (AREA)
  • Electrostatic Separation (AREA)
  • Control Of Voltage And Current In General (AREA)

Abstract

Circuit for regulating the high-voltage supply of an electrostatic filter for internal combustion engines, in which the high-voltage end stage (2) is controlled by a pulse width modulator (3). The high-voltage end stage (2) comprises a diode blocking oscillator-type converter which on the output side supplies an output voltage (UA) of several kV. The pulse-width repetition rate of the output voltage (UA) is modified as a function of the output current or output voltage, and taking into account a maximum permissible power. In this way the soot filter (1) can always work in an optimum operating range.

Description

Stand der TechnikState of the art

Die Erfindung betrifft eine Schaltungsanordnung zur Regelung der Hochspannungsversorgung eines in einer Rußweiche arbeitenden elektrostatischen Filters gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a circuit arrangement for regulating the high voltage supply of an electrostatic filter operating in a soot switch according to the preamble of claim 1.

Eine solche Schaltungsanordnung ist aus WO 80/02583 bekannt. Dort wird ein Rußabscheider für eine Brennkraftmaschine beschrieben. Mittels eines Wechselrichters, eines Transformators und eines Gleichrichters wird eine Hochspannung erzeugt. Die Höhe der Gleichspannung hängt dabei vom Partikelfluß der gewünschten Filterwirkung und dem Typ der Brennkraftmaschine ab. Als möglicher Spannungsbereich ist 100 V - 10 000 und mehr angegeben (Seite 11, Zeile 13 bis 17).Such a circuit arrangement is known from WO 80/02583. A soot separator for an internal combustion engine is described there. A high voltage is generated by means of an inverter, a transformer and a rectifier. The level of the DC voltage depends on the particle flow of the desired filter effect and the type of internal combustion engine. The possible voltage range is 100 V - 10,000 and more (page 11, lines 13 to 17).

Ferner sind elektrostatische Filter bekannt, die in Industrieanlagen zur Abscheidung von Staubpartikel aus Abgasen verwendet werden. Diese elektrostatischen Filter werden an Hochspannungsversorgungen angeschlossen, deren Spannung geregelt wird. Es wird die Ausgangsspannung einem Regler zugeführt, der die Hochspannung steuert. Für die in Industrieanlagen verwendeten elektrostatischen Filter kann aufgrund der vorhandenen Netzspannung auf einfache Weise eine geeignete Hochspannung erzeugt werden. Für eine Anwendung in Kraftfahrzeugen, wo als Bordspannung lediglich eine Gleichspannung von beispielsweise 12 Volt vorliegt, sind diese bekannten Schaltungsanordnungen für die Hochspannungsversorgung von in Industrieanlagen verwendeten Rußweichen nicht geeignet.Furthermore, electrostatic filters are known which are used in industrial plants for the separation of dust particles from exhaust gases. These electrostatic filters are connected to high-voltage supplies, the voltage of which is regulated. The output voltage is fed to a regulator that controls the high voltage. A suitable high voltage can easily be generated for the electrostatic filters used in industrial plants due to the existing mains voltage. These known circuit arrangements are not suitable for use in motor vehicles, where only a direct voltage of, for example, 12 volts is present as on-board voltage, for the high-voltage supply of soot switches used in industrial plants.

Das elektrostatische Filter wird im Kraftfahrzeug in stark unterschiedlichen Bereichen betrieben. Durchsatz, Zusammensetzung, Rußbeladung, Feuchtigkeit und Temperatur des Abgases ändern sich im gesamten Drehzahl- und Lastbereich des Motors stark und im instationären Betrieb des Motors mit raschem Wechsel. Die Impedanz der Entladung und die Durchschlaggrenze der Entladung hängen von diesen Parametern stark ab und schwanken entsprechend. Der ins Filter eingespeiste Strom und/oder die Betriebsspannung müssen entsprechend auf vorgegebene Werte geregelt oder auf maximal erlaubte Werte begrenzt werden, um eine ordentliche Funktion des Filters im gesamten Motorbetriebsbereich auf Dauer gewährleisten zu können. Dabei ist zu beachten, daß die elektrostatischen Filter in Kraftfahrzeugen insbesondere instationär und mit Durchsatzschwankungen um den Faktor 10 betrieben werden müssen, während die bekannten Filter bei großtechnischen Anlagen im wesentlichen stationär mit einem festen Arbeitspunkt betrieben werden.The electrostatic filter is operated in very different areas in the motor vehicle. Throughput, composition, soot loading, moisture and temperature of the exhaust gas change strongly in the entire speed and load range of the engine and in the transient operation of the engine with rapid change. The impedance of the discharge and the breakdown limit of the discharge strongly depend on these parameters and fluctuate accordingly. The current fed into the filter and / or the operating voltage must be regulated accordingly to predetermined values or limited to the maximum permitted values in order to be able to guarantee proper functioning of the filter in the entire engine operating range in the long term. It should be noted that the electrostatic filters in motor vehicles, in particular, have to be operated unsteadily and with throughput fluctuations by a factor of 10, while the known filters in large-scale plants are operated essentially stationary with a fixed operating point.

Mit diesen Anordnungen kann keine optimale Wirkung des elektrostatischen Filters im gesamten Motorbetriebsbereich erzielt werden.With these arrangements, an optimal effect of the electrostatic filter cannot be achieved in the entire engine operating range.

Der Erfindung liegt die Aufgabe zugrunde, bei einer Schaltungsanordnung der eingangs genannten Art, eine optimale Wirkung des elektrostatischen Filters im gesamten Betriebsbereich zu erzielen. Diese Aufgabe wird dadurch gelöst, daß die Hochspannungsendstufe eine Stromquelle darstellt und die Regelschaltung zur Regelung des in das Filter eingespeisten Stromes ausgebildet ist.The invention has for its object to achieve an optimal effect of the electrostatic filter in the entire operating range in a circuit arrangement of the type mentioned. This object is achieved in that the high-voltage output stage is a current source and the control circuit is designed to regulate the current fed into the filter.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Schaltungsanordnung mit den Merkmalen des Hauptanspruchs hat den Vorteil, daß eine optimale Wirkung des elektrostatischen Filters im gesamten Motorbetriebsbereich mit dieser Regelung erzielt werden kann. Dieses Gütekriterium wird ausreichend gut erfüllt, wenn man im gesamten Motorbetriebskennfeld gewährleistet, daß immer ein bestimmter Grundstrom IG ins Elektrofilter eingespeist wird. Die Regelschaltung kann dann sehr einfach als Festwertregler für die Regelgröße Filterbetriebsstrom ausgelegt werden. Die Regelung der Hochspannungsversorgung ist so ausgelegt, daß zunächst immer versucht wird, den Grundstrom auf einen vom Motorbetriebspunkt oder anderen Störeinflüssen weitgehend unabhängigen und konstanten Festwert zu regeln. Erst in einer Feinoptimierung der Filterfunktion kann auch der Ausgangsstrom, der den Filterbetriebsstrom bildet, zusätzlich in Abhängigkeit des Motorbetriebskennfeldes gesteuert werden.The circuit arrangement according to the invention with the features of the main claim has the advantage that an optimal effect of the electrostatic filter in the entire engine operating range can be achieved with this control. This quality criterion is met sufficiently well if it is ensured in the entire engine operating map that a certain basic current I G is always fed into the electrostatic filter. The control circuit can then be designed very simply as a fixed value controller for the control variable filter operating current. The regulation of the high-voltage supply is designed so that first of all attempts are made to regulate the basic current to a constant value which is largely independent of the engine operating point or other interfering influences. Only when the filter function has been fine-tuned can the output current, which forms the filter operating current, be additionally controlled as a function of the engine operating map.

Mittels eines Dioden-Sperrwandlers kann aus einer verhältnismäßig niedrigen Batterie-Gleichspannung eine Hochspannung erzeugt werden, die die Verwendung von elektrostatischen Filtern in Kraftfahrzeugen ermöglicht. Die Hochspannungsendstufe wird primärseitig mit einer pulsierenden Spannung gespeist, deren Tastverhältnis in Abhängigkeit vom Betriebszustand der Rußweiche eingestellt wird. Eine Überwachung der Ausgangsspannung, des Ausgangsstroms und der Ausgangsleistung ermöglicht eine derartige Veränderung des Tastverhältnisses, daß vorgegebene Maximalwerte nicht überschritten, die verwendeten Leistungselemente durch eine Leistungsbegrenzung vor Zerstörung geschützt werden und die Leistungsaufnahme insgesamt möglichst niedrig gehalten wird.A diode flyback converter can be used to generate a high voltage from a relatively low DC battery voltage, which enables the use of electrostatic filters in motor vehicles. The high-voltage output stage is supplied on the primary side with a pulsating voltage, the pulse duty factor of which is set depending on the operating state of the soot switch. Monitoring the output voltage, the output current and the output power enables such a change in the pulse duty factor that predetermined maximum values are not exceeded, the power elements used are protected from destruction by a power limitation and the overall power consumption is kept as low as possible.

Der Dioden-Sperrwandler kann zur Erhöhung der Ausgangsspannung mehrstufig in Kaskadenschaltung angeordnet sein, wobei der Ladekondensator durch die Kapazität des ausgangsseitigen Hochspannungskabels gebildet werden kann. Ein spezieller Ladekondensator kann dadurch entfallen.The diode flyback converter can be cascaded in several stages to increase the output voltage, the charging capacitor being able to be formed by the capacitance of the high-voltage cable on the output side. This eliminates the need for a special charging capacitor.

Die Primärwicklung des Sperrwandlers ist vorzugsweise mit einem als elektrischen Schalter betriebenen Feldeffekttransistor in Serie geschaltet, dessen Steuereingang (Gate) von einem Pulsbreitenmodulator zur Einstellung des Tastverhältnisses gesteuert wird. Der Pulsbreitenmodulator ändert das Tastverhältnis so, daß der Ausgangsstrom und/oder die Ausgangsspannung und/oder die Ausgangsleistung der Hochspannungsendstufe begrenzt und innerhalb eines vorgegebenen Arbeitsbereichs gehalten werden. Zur Überwachung und Begrenzung des Primärstroms kann der Spannungsabfall des eingeschalteten, primärseitigen Feldeffakttransistor verwendet werden, da dieser Transistor einen weitgehend linearen Innenwiderstand bei Übersteuerung besitzt und somit die an ihm, zwischen Drain und Source abfallende Spannung proportional zum Primärstrom ist. Der Primärstrom soll insbesondere in der Hochlaufphase auf einen möglichst hohen Wert begrenzt werden. Jedoch muß dieser kleiner sein, als derjenige Strom, der zur Zerstörung des Feldeffektransistors führt. Je höher der Primärstrom während der Hochlaufphase ist, desto schneller erreichen Ausgangsstrom und Ausgangsspannung ihre Betriebswerte.The primary winding of the flyback converter is preferably connected in series with a field effect transistor operated as an electrical switch, the control input (gate) of which is controlled by a pulse width modulator for setting the duty cycle. The pulse width modulator changes the duty cycle so that the Output current and / or the output voltage and / or the output power of the high-voltage output stage are limited and kept within a predetermined working range. To monitor and limit the primary current, the voltage drop of the switched-on, primary-side field-effect transistor can be used, since this transistor has a largely linear internal resistance when overdriven and thus the voltage drop across it between drain and source is proportional to the primary current. The primary current should be limited to as high a value as possible, especially in the start-up phase. However, this must be smaller than the current that leads to the destruction of the field effect transistor. The higher the primary current during the start-up phase, the faster the output current and output voltage reach their operating values.

Mittels einer Durchschlag-Erkennungseinrichtung und mittels einer Anlaufknicksteuerung ist weiterhin vorgesehen, daß das Filter nicht vollständig bei Auftreten eines Spannungsdurchschlags abgeschaltet wird, sondern es wird lediglich der Betriebsstrom möglichst rasch und kurzzeitig auf einen Minimalstrom zurückgesetzt oder begrenzt. Damit werden bei Durchschlägen entstehende Lichtbögen rasch gelöscht. Es bleibt aber trotzdem noch eine Minimalfunktion des Filters während der Abregelung erhalten, weil die Partikel durch den Minimalstrom nach wie vor beladen werden. Um die Betriebssicherheit des Filters auf Dauer zu gewährleisten, sind Begrenzungen bezüglich des ins Filter maximal einspeisbaren Stromes und der ins Filter maximal einspeisbaren Leistung und Spannung vorgesehen. Jede der drei Begrenzungen schützt sowohl die Bauelemente der Hochspannungsversorgung als auch die Hochspannungsbauelemente des Filters vor einer Überlastung. Das Bordnetz wird zusätzlich durch die Leistungsbegrenzung vor einer zu großen Leistungsaufnahme durch das elektrostatische Filter geschützt.By means of a breakdown detection device and by means of a starting kink control, it is further provided that the filter is not switched off completely when a voltage breakdown occurs, but rather the operating current is reset or limited to a minimum current as quickly and briefly as possible. In this way, arcs that occur during breakdowns are quickly extinguished. However, a minimal function of the filter is still retained during the cut-off because the particles are still loaded by the minimal current. In order to ensure the operational reliability of the filter in the long term, limits are provided regarding the maximum current that can be fed into the filter and the maximum power and voltage that can be fed into the filter. Each of the three limits protects both the components of the high-voltage supply and the high-voltage components of the filter against overload. The on-board electrical system is also protected by the power limitation from excessive power consumption by the electrostatic filter.

Die additive Einspeisung des Kriechstroms zum Grundstrom hat den Vorteil, daß für jeden Motorbetriebspunkt und in Abhängigkeit von der jeweiligen Funktionstüchtigkeit des Isolators ganz genau der jeweils augenblicklich, zumindest erforderliche Betriebsstrom in das Filter eingespeist wird. Dies hat den Vorteil, daß das Bordnetz jeweils nur mit der minimal erforderlichen elektrischen Leistungsaufnahme durch das Filter belastet wird. Die elektronischen Leistungsbauelemente können dadurch für geringere Belastungen ausgelegt sein. Die Bauelemente werden damit kleiner, billiger oder können zum Teil ganz eingespart werden, weil der maximal auftretende Kriechstrom ungefähr um den Faktor 10 größer ist als der zeitlich gemittelte Kriechstrom. Die additive Einspeisung des Kriechstroms läßt sich bei der erfindungsgemäßen Regelschaltung deshalb besonders einfach und damit Kfz-tauglich ergänzen, weil nicht die Betriebsspannung, sondern der Filterstrom als Regelgröße ausgewählt wurde.The additive feeding of the leakage current to the base current has the advantage that for each engine operating point and depending on the particular functionality of the isolator, the instantaneously, at least required operating current is fed into the filter. This has the advantage that the vehicle electrical system is only loaded with the minimum required electrical power consumption by the filter. The electronic power components can thus be designed for lower loads. The components are thus smaller, cheaper or can be partially saved entirely because the maximum leakage current that occurs is approximately 10 times greater than the leakage current averaged over time. The additive feeding of the leakage current can be supplemented in the control circuit according to the invention in a particularly simple and therefore vehicle-compatible manner, because not the operating voltage but the filter current was selected as the control variable.

Vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen gekennzeichnet.Advantageous developments of the invention are characterized in the subclaims.

Zeichnungdrawing

Die Erfindung wird nachfolgend anhand der Zeichnungen näher erläutert. Es zeigen:

  • Figur 1 ein stark vereinfachtes Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung,
  • Figur 2 die elektrische Schaltung einer Hochspannungsendstufe mit Dioden-Sperrwandler,
  • Figur 3 ein ausführlicheres Blockschaltbild der Schaltungsanordnung zur Regelung der Hochspannungsversorgung und
  • Figur 4 ein Strom-Spannungsdiagramm.
The invention is explained in more detail below with reference to the drawings. Show it:
  • FIG. 1 shows a greatly simplified block diagram of a circuit arrangement according to the invention,
  • FIG. 2 shows the electrical circuit of a high-voltage output stage with a diode flyback converter,
  • Figure 3 is a more detailed block diagram of the circuit arrangement for regulating the high voltage supply and
  • Figure 4 is a current-voltage diagram.

In Figur 1 ist der grundsätzliche Aufbau einer Hochspannungsvesorgung für eine elektrostatische Rußweiche in Form eines stark vereinfachten Blockschaltbildes angegaben. Eine elektrostatische Rußweiche 1, deren Aufbau nicht Gegenstand vorliegender Erfindung ist, wird durch die Ausgangsspannung UA einer Hochspannungsendstufe 2 mit der erforderlichen Hochspannung versorgt. Das Tastverhältnis T" der Ausgangsspannung UA, welches durch das Verhältnis von Impulsdauer T; zur Periodendauer Tp definiert ist, kann in Abhängigkeit von der Leistung P, der Ausgangsspannung UA und des Ausgangsstromes 18 variiert werden. Die Einstellung des Tastverhältnisses T" erfolgt mittels eines Pulsbreitenmodulators 3, dessen Ausgang mit dem Steuereingang der Hochspannungsendstufe 2 verbunden ist. Der Pulsbreitenmodulator 3 ist seinerseits mit einer Aufbereitungsschaltung 4 verbunden, die die Leistung P, die Ausgangsspannung UA und den Ausgangsstrom IA überwacht. Eine nähere Beschreibung der Funktionsweise dieser Schaltungsanordnung erfolgt anhand des in Figur 3 dargestellten ausführlicheren Blockschaltbildes.FIG. 1 shows the basic structure of a high-voltage supply for an electrostatic soot switch in the form of a greatly simplified block diagram. An electrostatic soot switch 1, the construction of which is not the subject of the present invention, is supplied with the required high voltage by the output voltage U A of a high-voltage output stage 2. The duty cycle T "of the output voltage U A, which is obtained by the ratio of pulse period T is defined with the period duration Tp, can be varied in function of the power P, the output voltage U A and the output current 1 8 The setting of the duty ratio T." Takes place by means of a pulse width modulator 3, the output of which is connected to the control input of the high-voltage output stage 2. The pulse width modulator 3 is in turn connected to a processing circuit 4 which monitors the power P, the output voltage U A and the output current I A. The mode of operation of this circuit arrangement is described in more detail with reference to the more detailed block diagram shown in FIG.

In Figur 2 ist im wesentlichen ein Dioden-Sperrwandler 5 dargestallt. der primärseitig erzeugte Spannungsimpulse auf die erforderliche ausgangsseitige Hochspannung transformiert. An der Primärwicklung P liegt einerseits die Batteriespannung UB an, während das andere Ende der Primärwicklung P über einen Feldeffekttransistor 6 mit Masse verbunden ist. Der Feldeffektransistor 6 wird als elektrischer Schalter betrieben und zu diesem Zweck vom Pulsbreitenmodulator 3 an seinem Steuereingang G periodisch ein- und ausgeschaltet. Die Einschaltzeiten und Ausschaltzeiten des Feldeffekttransistors 6 bestimmen das Tastverhältnis der Primärspannung und damit auch die Höhe des Ausgangsstroms IA.A diode flyback converter 5 is essentially shown in FIG. transforms the voltage pulses generated on the primary side to the required high voltage on the output side. On the one hand, the battery voltage U B is present at the primary winding P, while the other end of the primary winding P is connected to ground via a field effect transistor 6. The field effect transistor 6 is operated as an electrical switch and for this purpose is switched on and off periodically by the pulse width modulator 3 at its control input G. The on and off times of the field effect transistor 6 determine the duty cycle of the primary voltage and thus also the level of the output current I A.

Die Sekundärseite des Sperrwandler 5 besteht aus drei Sekundärwicklungen S1 bis S3 und drei Dioden D1 bis D3. Eine der Ausgangsspannung UA proportionale Spannung UA' kann am Abgriff eines Spannungsteilers abgegriffen werden, der aus den Widerständen R1 und R2 besteht. Zur Messung des Ausgangsstroms IA kann an einem Widerstand R3 ein zum Ausgangsstrom IA proportionales Signal 1A' abgegriffen werden. Der Widerstand R3 ist zu diesem Zweck in Serie zu der Sekundärseite des Sperrwandler 5 geschaltet.The secondary side of flyback converter 5 consists of three secondary windings S1 to S3 and three diodes D1 to D3. One of the output voltage U A proportional voltage U A 'may be at the tap a voltage divider can be tapped, which consists of the resistors R1 and R2. For the measurement of the output current I A is a proportional to the output current I A signal may A 1 'are tapped off across a resistor R3. For this purpose, the resistor R3 is connected in series to the secondary side of the flyback converter 5.

Ein zur Ausgangsleistung PA proportionales Signal 1A" kann aber auch an dem Drain-Anschluß D des Feldeffekttransistors 6 abgegriffen werden. Die dort während der Einschaltphase T; auftretende Spannung ist nämlich weitgehend proportional zu dem primärseitig fließenden Strom, und damit auch weitgehend proportional zu der sekundärseitigen Ausgangsleistung PA, da der Durchgangswiderstand des Feldeffekttransistors 6 zwischen Drain und Source S im Durchlaßbetrieb annähernd konstant ist.A signal 1 A "proportional to the output power P A can, however, also be tapped at the drain terminal D of the field effect transistor 6. The voltage occurring there during the switch-on phase T; is namely largely proportional to the current flowing on the primary side and thus also largely proportional to the secondary-side output power P A , since the volume resistance of the field effect transistor 6 between drain and source S is approximately constant in the forward mode.

Das in Figur 3 dargestellte Blockschaltbild enthält eine Hochspannungsendstufe 2, die aus einer Leistungsendstufe 7 und einem Dioden-Sperrwandler 5 besteht. Die Leistungsendstufe 7 wird von einer Treiberschaltung 8 gespeist, die ihrerseits über einen Pulsbreitenmodulator 3 gesteuert wird. Der Pulsbreitenmodulator 3 stellt über die Treiberschaltung 8, die Leistungsendstufe 7 das Tastverhältnis der Primärspannung am Dioden-Sperrwandler 5 und damit auch die Ausgangsleistung PA ein. Der Leistungsbegrenzer 9 arbeitet in Abhängigkeit der Betriebsspannung UB und wirkt im Pulsbreitenmodulator 3 begrenzend auf das Tastverhältnis. Der Pulsbreitenmodulator 3 wird außerdem von einer Minimum-Auswahlschaltung 11 mit einem Steuersignal gespeist, welches vom Ausgangsstrom und/oder von der Ausgangsspannung abhängig ist.The block diagram shown in FIG. 3 contains a high-voltage output stage 2, which consists of a power output stage 7 and a diode flyback converter 5. The power output stage 7 is fed by a driver circuit 8, which in turn is controlled by a pulse width modulator 3. The pulse width modulator 3 sets the pulse duty factor of the primary voltage at the diode flyback converter 5 and thus also the output power P A via the driver circuit 8, the power output stage 7. The power limiter 9 operates as a function of the operating voltage U B and has a limiting effect on the pulse duty factor in the pulse width modulator 3. The pulse width modulator 3 is also fed by a minimum selection circuit 11 with a control signal which is dependent on the output current and / or on the output voltage.

Zur Begrenzung der Ausgangsspannung UA wird diese oder ein zu ihr proportionales Signal einem Impedanzwandler 14 zugeführt, der ausgangsseitig mit der Durchschlag-Erkennungsschaltung 12, einem Leistungsbegrenzer 15, der alternativ zum Leistungsbegrenzer 9 vorgesehen sein kann, und mit einer Differenzschaltung 16 verbunden ist. Die Leistungsbegrenzer 9 und 15 können jeder für sich alleine die Leistung begrenzen. Es ist deshalb in einer ausgeführten Schaltung nur einer der beiden Leistungsbegrenzer nötig. Der Leistungsbegrenzer 15 erhält als Eingangsgröße ein der Ausgangsspannung UA proportionales Signal. Er wandelt dieses in einen Strom-Sollwert derartig um, daß die Ausgangsleistung einen bestimmten Wert nicht überschreitet. Die Differenzschaltung 16 bildet die Differenz zwischen einem für die Ausgangsspannung vorgesehenen Maximalwert UAmax und dem Ausgangssignal des Impedanzwandlers 14. Das Differenzsignal wird einem Spannungsregler 17 zugeführt, der ausgangsseitig mit der Minimalwert-Auswahlschaltung 11 verbunden ist.To limit the output voltage U A , this or a signal proportional to it is fed to an impedance converter 14, which is connected on the output side to the breakdown detection circuit 12, a power limiter 15, which can be provided as an alternative to the power limiter 9, and to a differential circuit 16. The power limiters 9 and 15 can each limit the power individually. It is therefore only necessary to use one of the two power limiters in a circuit. The power limiter 15 receives a signal proportional to the output voltage U A as an input variable. It converts this into a current setpoint such that the output power does not exceed a certain value. The difference circuit 16 forms the difference between a maximum value U Amax provided for the output voltage and the output signal of the impedance converter 14. The difference signal is fed to a voltage regulator 17 which is connected on the output side to the minimum value selection circuit 11.

Die Durchschlag-Erkennungschaltung 12 besteht aus einem eingangsseitigen Differenzierer 18, dem ein Komparator 19 mit einer Hysterese nachgeschaltet ist. Der Ausgang der Durchschlag-Erkennungsschaltung 12 ist mit einem Eingang einer Anlauf-Knicksteuerung 20 und dem Eingang einer Bestpunkt-Automatik 21 verbunden. Die Anlauf-Knicksteuerung 20 bewirkt, daß nach erfolgtem Spannungsdurchschlag der Ausgangsstrom IA kurze Zeit auf einem so weit reduzierten Wert verharrt, daß ein eventuell entstandener Lichtbogen verlöscht. Am Ende der Verharrungszeit wird der Strom mit definierter Steigung zügig wieder hochgesteuert. Die Bestpunkt-Automatik 21 bewirkt, daß nach erfolgtem Spannungsdurchschlag der Ausgangsstrom IA auf einen etwas niedrigeren Wert gesetzt wird, als vor dem Durchschlag. Danach wird der Ausgangsstrom IA langsam wieder hochgesteuert, bis zu einem eventuell erneuten Durchschlag. Diese Bestpunkt-Automatik 21 bewirkt, daß die Anzahl der Spannungsdurchschläge während des Betriebes klein gehalten wird und somit auch die Zeiten mit reduzierter Filterfunktion. Die Ausgänge der Bestpunkt-Automatik 21 und der Anlauf-Knicksteuerung 20 sowie das Summensignal aus dem Grundstrom IG und dem auftretenden Kriechstrom IK werden ausgangsseitig einer zweiten Minimalwert-Auswahlschaltung 22 zugeführt. Diese Minimalwert-Auswahlschaltung 22 besitzt noch zwei weitere Eingänge, an denen der Maximalwert des Ausgangsstromes IAmax und der Ausgang der zur Leistungsbegrenzung dienenden Schaltung 15 anliegen. Der Ausgang der Minimalwert-Auswahlschaltung 22 ist mit dem positiven Eingang eines Summierers 23 verbunden, an dessen negativen Eingang der Ausgangsstrom IA bzw. ein dazu proportionaler Wert anliegt. Der Ausgang des Summierers 23 ist über einen Stromregler 24 mit einem Eingang der Minimalwert-Auswahlschaltung verbunden.The breakdown detection circuit 12 consists of a differentiator 18 on the input side, which is followed by a comparator 19 with hysteresis. The output of the breakdown detection circuit 12 is connected to an input of a start buckling control 20 and the input of an automatic best point 21. The start-up break control 20 has the effect that after the voltage breakdown has occurred, the output current I A remains briefly at a value which has been reduced to such an extent that an arc which may have arisen extinguishes. At the end of the pause, the current is quickly ramped up again with a defined gradient. The best-point automatic 21 causes the output current I A to be set to a somewhat lower value after the voltage breakdown than before the breakdown. Then the output current I A is slowly ramped up again until a breakdown occurs. This best-point automatic 21 has the effect that the number of voltage breakdowns during operation is kept small and thus also the times with a reduced filter function. The outputs of the best-point automatic 21 and the start-up buckling control 20 as well as the sum signal from the basic current I G and the creeping current I K occurring are fed to a second minimum value selection circuit 22 on the output side. This minimum value selection circuit 22 also has two further inputs, at which the maximum value of the output current I Amax and the output of the circuit 15 serving to limit the power are present. The output of the minimum value selection circuit 22 is connected to the positive input of a summer 23, at whose negative input the output current I A or a value proportional to it is present. The output of the summer 23 is connected via a current regulator 24 to an input of the minimum value selection circuit.

Der Pulsbreitenmodulator 3 wandelt eine von der Minimalwert-Auswahlschaltung 11 kommende analoge Spannung proportional in einen Impuls der Dauer Ti um, der mit einer konstanten Wiederholfrequenz wiederholt wird. Die Minimalwert-Auswahlschaltung 11 wählt den kleinsten der an ihren Eingängen anliegenden Werte in ansich bekannter Weise für die Bildung des dem Pulsbreitenmodulator 3 zugeführten Ausgangssignales aus. In entsprechender Weise erfolgt eine Minimalwert-Auswahl in der Minimalwert-Auswahlschaltung 22. Auch deren Ausgangssignal entspricht jeweils dem kleinsten Eingangsignal oder ist zu diesem proportional.The pulse width modulator 3 converts an analog voltage coming from the minimum value selection circuit 11 proportionally into a pulse of the duration T i , which is repeated at a constant repetition frequency. The minimum value selection circuit 11 selects the smallest of the values present at its inputs in a manner known per se for the formation of the output signal fed to the pulse width modulator 3. In a corresponding manner, a minimum value selection takes place in the minimum value selection circuit 22. Its output signal also corresponds to the smallest input signal or is proportional to it.

Der Kriechstrom IK ist der am Isolator der Rußweiche abfließende Strom, während der Grundstrom IG der Stromanteil ist, welcher in der Rußweiche über die Gasentladung abfließt. Der Grundstrom IG ist für die Funktion der Rußweiche, die auch als Rußfilter bezeichnet werden kann, verantwortlich. Die Rußpartikel werden durch den Grundstrom IG geladen und dadurch agglomeriert. Der Grundstrom IG kann für einen Filtertyp ermittelt und fest eingestellt oder in Abhängigkeit von Drehzahl und Last des Verbrennungsmotors zusätzlich kennfeldgesteuert werden. Zusätzlich zum Grundstrom muß in das Filter zusätzlich zu jedem Augenblick der über den Isolator abfließende Kriechstrom IK eingespeist werden. Dieser Kriechstrom brennt den am Isolator abgelagerten Ruß ab und hat somit eine reinigende Wirkung. Der Ausgangsstrom IA wird durch den fest vorgegebenen Wert IAmax auf einen maximal zulässigen Betriebswert begrenzt. Je nach Bauteildimensionierung kann dieser Wert beispielsweise 10mA betragen.The leakage current I K is the current flowing away at the insulator of the soot switch, while the base current I G is the portion of the current which flows off in the soot switch via the gas discharge. The base current I G is responsible for the function of the soot switch, which can also be referred to as a soot filter. The soot particles are charged by the base current I G and thereby agglomerated. The basic current I G can be determined for a filter type and set permanently, or it can also be controlled as a function of the speed and load of the internal combustion engine. In addition to the basic current, the Filters the leakage current I K flowing out through the insulator can be fed in at any moment. This leakage current burns off the soot deposited on the insulator and thus has a cleaning effect. The output current I A is limited to a maximum permissible operating value by the fixed value I Amax . Depending on the dimensioning of the component, this value can be 10mA, for example.

Die Anlauf-Knicksteuerung 20 hat die Aufgabe, nach einem Spannungsdurchschlag den Strom- Sollwert sofort auf einen Minimalwert Imin zurückzusetzen. Nach kurzem Verharren auf diesem Minimalwert Imin wird der Stromsollwert lAsoll rasch an den kleinsten der Stromsollwerte herangeführt. Die Bestpunkt-Automatik 21 regelt den Stromsollwert möglichst nähe an die Durchschlagsgrenze, wenn das Filter in besonderen Drehzahl- und Lastbereichen nahe an der Durchschlaggrenze betrieben wird. Nach jedem Durchschlag wird der Ausgang der Anlauf-Knicksteuerung 20 um einen bestimmten Betrag schnell abgesenkt und läuft danach wieder langsam hoch, bis ein neuerlicher Durchschlag erfolgt. Falls es über längere Zeit keine Durchschläge gibt, wird dieser Wert gleich der Summe von IK und IG. Im Fall eines Spannungsdurchschlages bricht die Ausgangsspannung UA mit steiler Flanke ein, dies detektiert die Differenzschaltung 18, die bei Überschreiten eines Schwellwertes den Komperator 19 zum Kippen bringt.The start-up kink control 20 has the task of immediately resetting the current setpoint to a minimum value Imin after a voltage breakdown. After briefly remaining at this minimum value Imin, the current setpoint I Asoll is rapidly brought up to the smallest of the current setpoints. The best-point automatic 21 regulates the current setpoint as close as possible to the breakdown limit if the filter is operated close to the breakdown limit in special speed and load ranges. After each breakdown, the output of the start-up buckling control 20 is quickly lowered by a certain amount and then starts up again slowly until a new breakdown occurs. If there are no breakthroughs over a long period of time, this value becomes equal to the sum of I K and I G. In the event of a voltage breakdown, the output voltage U A collapses with a steep edge, this is detected by the differential circuit 18, which causes the comparator 19 to tilt when a threshold value is exceeded.

Der Spannungsregler 17 begrenzt die Ausgangsspannung UA auf einen maximal zulässigen Wert, beispielsweise auf 17 bis 18kV.The voltage regulator 17 limits the output voltage U A to a maximum permissible value, for example to 17 to 18 kV.

In dem in Figur 4 dargestellten Strom-Spannungsdiagramm sind die maximale Spannung, der maximale Strom und eine Leistungshyperbel Pmax angegeben. Mit steigender Abgastemperatur steigt der Kriechstrom IK an, wodurch sich die Kennlinien für den Ausgangsstrom IA entsprechend ändern. Mit steigender Abgastemperatur oder mit größer werdendem Kriechstrom IK werden die Strom-Spannungskennlinien steiler.The current-voltage diagram shown in FIG. 4 shows the maximum voltage, the maximum current and a power hyperbola P max . The creeping current I K rises with increasing exhaust gas temperature, as a result of which the characteristics for the output current I A change accordingly. With increasing exhaust gas temperature or with increasing leakage current I K , the current-voltage characteristics become steeper.

Claims (19)

1. Circuit arrangement for regulating the high-voltage supply of an electrostatic filter (1), which operates in a soot trap, for internal combustion engines, comprising a high-voltage output stage (2) and a regulating circuit (3, 4) which regulates the high-voltage output stage (2) connected to the filter, characterized in that the high-voltage output stage (2) represents a current source and that the regulating circuit (3, 4) is constructed for regulating the current fed into the filter (1).
2. Circuit arrangement according to Claim 1, characterized in that the high-voltage output stage (2) contains a diode-type flyback converter (5), across which a pulsating primary voltage is present which changes its duty ratio (Tv) as a function of the respective operating condition of the filter (1).
3. Circuit arrangement according to Claim 2, characterized in that the diode-type flyback converter (5) uses the capacitance of the output- side high-voltage cable as charging capacitor.
4. Circuit arrangement according to one of Claims 2 or 3, characterized in that the diode-type flyback converter (5) is constructed in several stages in a cascade circuit.
5. Circuit arrangement according to one of Claims 2 to 4, characterized in that the primary winding (P) of the flyback converter (5) is connected in series with a field-effect transistor (6) which is operated as electric switch and the gate (G) of which is controlled by a pulse-width modulator (3) for adjusting the duty ratio (Tv).
6. Circuit arrangement according to one of Claims 2 to 5, characterized in that the duty ratio (Tv) is changed in such a manner that the output current (IA) of the high-voltage output stage (2) is kept constant.
7. Circuit arrangement according to one of Claims 2 to 6, characterized in that the power is limited for the high-voltage output stage (2) by changing the duty ratio (Tv) as a function of the output current (IA) and/or output voltage (UA).
8. Circuit arrangement according to one of Claims 2 to 7, characterized in that the voltage drop during the pulse period (T;) across the primary-side field-effect transistor (6) is supplied to the regulating circuit as a measurement variable which is proportional to the output power.
9. Circuit arrangement according to one of Claims 2 to 8, characterized in that a breakdown detection circuit (12) is provided which switches off the high-voltage output stage (2) when a voltage breakdown occurs in the soot trap (1).
10. Circuit arrangement according to one of the preceding Claims, characterized in that, after a voltage breakdown occurs, a start-up knee control arrangement (20) controls the current of the filter (1) as rapidly as possible to a minimum value (Imin) which rises again to the operating current with a defined slope after a short delay time.
11. Circuit arrangement according to one of the preceding Claims, characterized in that an automatic best-point arrangement (21) limits the filter current to a value which is slightly below the value at which the breakdown had occurred, and which then allows the filter current to rise again slowly.
12. Circuit arrangement according to one of the preceding Claims, characterized in that the output current (IA) is formed from the sum of a basic current (IG) necessary for the operation of the filter (1) and the leakage current (IK) flowing away over the insulators.
13. Circuit arrangement according to one of the preceding Claims, characterized in that a power limiter (15), which is supplied with a signal proportional to the output voltage (UA), is used for forming a nominal current value and that, as a result, the output power is kept constant and/or limited.
14. Circuit arrangement according to one of Claims 1 to 11, characterized in that the output power is limited in dependence on the operating voltage (UB) with the aid of a power limiter (9).
15. Circuit arrangement according to one of Claims 5 to 14, characterized in that the voltage drop across the primary-side field-effect transistor (6), which is due to the primary current (I" A) occurring during the pulse period (T,), is measured and fed back to the pulse-width modulator (3) via a delay circuit (13) for current limiting during the run-up of the output voltage (UA)
16. Circuit arrangement according to Claim 15, characterized in that the primary current fed back to the pulse-width modulator (3) via the delay circuit (13) is limited to such a high value that the specified maximum permissible current of the field-effect transistor (6) is reached but not exceeded.
17. Circuit arrangement according to one of the preceding Claims, characterized in that, for the purpose of limiting the output voltage (UA), a voltage regulator (17) forms from a signal proportional to the output voltage (UA) in turn a signal which controls the pulse-width modulator (3) via a minimum-selection circuit (11) in such a manner that any further rise in the output voltage (UA) is prevented.
18. Circuit arrangement according to one of the preceding Claims, characterized in that the basic current (IG) for the electrostatic filter (1) is additionally controlled in the set of characteristics by the engine operating parameters of speed and load.
EP86902787A 1985-08-30 1986-04-30 Circuit for regulating the high-voltage supply of an electrostatic filter Expired EP0233191B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19853531025 DE3531025A1 (en) 1985-08-30 1985-08-30 CIRCUIT ARRANGEMENT FOR CONTROLLING THE HIGH VOLTAGE SUPPLY OF AN ELECTROSTATIC FILTER
DE3531025 1985-08-30

Publications (2)

Publication Number Publication Date
EP0233191A1 EP0233191A1 (en) 1987-08-26
EP0233191B1 true EP0233191B1 (en) 1989-08-23

Family

ID=6279762

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86902787A Expired EP0233191B1 (en) 1985-08-30 1986-04-30 Circuit for regulating the high-voltage supply of an electrostatic filter

Country Status (5)

Country Link
US (1) US4816979A (en)
EP (1) EP0233191B1 (en)
JP (1) JPS63500706A (en)
DE (2) DE3531025A1 (en)
WO (1) WO1987001306A1 (en)

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DE3817506A1 (en) * 1988-05-24 1989-12-07 Bosch Gmbh Robert CIRCUIT FOR THE HIGH VOLTAGE SUPPLY OF AN ELECTROSTATIC FILTER
IT1245165B (en) * 1991-02-15 1994-09-13 Ente Naz Energia Elettrica SYSTEM TO CONTROL AND REGULATE VOLTAGE PULSE POWER SUPPLIES FOR ELECTROSTATIC PRECIPITATORS
IT1247337B (en) * 1991-04-12 1994-12-12 Ente Naz Energia Elettrica PROTECTED POWER SUPPLY OF THE HIGH FREQUENCY SWITCHING TYPE, IN PARTICULAR FOR ELECTROSTATIC PRECIPITATORS
IT1247356B (en) * 1991-06-17 1994-12-12 Plessey Spa CONTINUOUS HIGH VOLTAGE GENERATION EQUIPMENT ESTABLISHED IN PARTICULAR FOR USE IN COMBINATION WITH AN ANTI-POLLUTION EXHAUST
DE4127577A1 (en) * 1991-08-21 1993-03-04 Bosch Gmbh Robert High voltage generation system from vehicle electrical circuit for electrostatic soot precipitator - uses voltage regulator producing theoretical value for at least one current regulator regulating flow through precipitator
SE500810E (en) * 1993-01-29 2003-04-29 Flaekt Ab Ways of regulating power supply to an electrostatic dust separator
DE19529769A1 (en) * 1995-08-12 1997-02-13 Hengst Walter Gmbh & Co Kg Method for operating an electrostatic filter or a crankcase ventilation
DE10110609B4 (en) * 2001-03-06 2013-01-03 Fludicon Gmbh High Voltage Power Supply
DE10328586A1 (en) * 2003-06-25 2005-01-20 Siemens Ag Electrostatic filter with breakdown detection
US7625424B2 (en) * 2006-08-08 2009-12-01 Oreck Holdings, Llc Air cleaner and shut-down method
EP2078563B1 (en) * 2008-01-09 2012-10-31 Alstom Technology Ltd Method and device for controlling an electrostatic precipitator
EP2172271B1 (en) * 2008-10-01 2018-08-29 General Electric Technology GmbH A method and a device for controlling the power supplied to an electrostatic precipitator
US20110030560A1 (en) * 2009-08-04 2011-02-10 Bohlen John R Air cleaner with multiple orientations
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DE102022103550B4 (en) * 2022-02-15 2024-01-04 Woco Gmbh & Co. Kg Control circuit for an electrical separator

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US4410934A (en) * 1981-07-22 1983-10-18 Masco Corporation DC Power supply for an air filter
US4479164A (en) * 1982-08-09 1984-10-23 Combustion Engineering, Inc. Control for an electrostatic treater
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US4586120A (en) * 1983-12-30 1986-04-29 At&T Bell Laboratories Current limit shutdown circuit with time delay

Also Published As

Publication number Publication date
US4816979A (en) 1989-03-28
EP0233191A1 (en) 1987-08-26
DE3665136D1 (en) 1989-09-28
WO1987001306A1 (en) 1987-03-12
JPS63500706A (en) 1988-03-17
DE3531025A1 (en) 1987-03-05

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