JPH0817313B2 - Pulse generator and dust collector using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulse generator and a pulse charging type dust collector using the same.

BACKGROUND ART In the case of a reactive load, such as a pulse charging type dust collector for efficiently collecting high-resistivity dust, it is desirable to regenerate the excess energy supplied from the pulse generator to the load back to the input side, thereby increasing the efficiency of the system.

Examples of such pulse generators that have the function of regenerating excess energy supplied to a load include:
A device used in a dust collecting apparatus of the pulse charging type is known, as described in Japanese Patent Publication No. 57-43062.

FIG. 14 shows an example of a dust collector of the pulse charging type described in Japanese Patent Publication No. 57-43062. 51 is an input DC power source, 52 is a
is a charging resistor of the main capacitor 53, 53 is a main capacitor for storing input energy, and 54 is a GTO (Gate Transformer) which is a main switch for discharging the charge stored in the main capacitor 53.
Turn Off Thyristor), 55 is a diode, 56 is a step-up transformer, 57 is a primary winding of the step-up transformer 56, 58 is a secondary winding of the step-up transformer 56, 59 and 60 are output terminals of the pulse generating circuit, 61 is a second input DC power supply, 62 is a reactor for suppressing surge current, 63 is a capacitor for blocking DC current, and 64 is a dust collecting electrode.

In FIG. 14, the positive electrode of the input DC power supply 61, the dust collection electrode 64,
A DC voltage E61 is constantly applied to the dust collection electrode 64 in the direction opposite to the direction of V64 in the figure through the surge current suppression reactor 62 and the negative electrode of the input DC power supply 61. In other words, a DC voltage −E61 is applied to the dust collection electrode 64 with respect to GND.

The portion enclosed by the dashed line in Fig. 14 is a pulse generating circuit, which has the function of superimposing a negative high voltage pulse on the DC voltage -E61 applied to the collection electrode 64. Its operation will be explained using Fig. 14 showing the circuit configuration, Fig. 15 showing the voltage and current waveforms of the main parts in Fig. 14, and Fig. 16 showing the voltage waveforms of the main parts in Fig. 14.

In this circuit, in order to improve the efficiency of energy transfer from the main capacitor 53 to the dust collecting electrode 64, the primary winding of the step-up transformer 56
If the turn ratio of the main capacitor 57 and the secondary winding 58 is 1:N,
It is desirable that the ratio of the capacitance of the capacitor 3, the capacitance of the DC current blocking capacitor 63 and the capacitance of the dust collecting electrode 64 is about 0.9·N ² :10:1.

When a turn-on signal is input to the gate of the GTO 54 and the GTO 54 is turned on, the charge stored in the main capacitor 53 flows from the positive terminal of the main capacitor 53 shown in the figure to the primary winding 57 of the step-up transformer 56,
14, as shown in FIG. 15. In the path of the negative pole of the GTO 54 and the main capacitor 53, a current flows in the opposite direction to i1' in FIG. 14. Therefore, a current corresponding to the turn ratio of the step-up transformer 56 flows in the secondary winding 58 of the step-up transformer 56.
A pulse current such as that shown in FIG. 15 i2' flows through the secondary winding 58 of FIG.
14, through the path of the polarity of the black circle in the figure, the dust collection electrode 64, the DC current blocking capacitor 63, and the secondary winding 58, which has the opposite polarity to the black circle in the figure.
That is, a voltage of peak value -V64 is applied to the collection electrode 64 with respect to GND as shown in FIG.

The period τ1' from when the currents i1' and i2' start to flow until they become zero again is
The leakage inductance seen from 57 is L561, the main capacitor 5
3. If the combined capacitance of the DC current blocking capacitor 63 and the dust collecting electrode 64 as viewed from the primary winding of the step-up transformer 56 is Ct, it is given by the following equation:

After τ1' from when the GTO 54 is turned on, the charge transferred to the collection electrode 64 flows in the direction of the current i2' in FIG. 14 from the positive pole of the collection electrode 64 to the secondary winding 58 of the step-up transformer 56, as shown in FIG.
14, a pulse current flows from the polarity of the black circle in the primary winding 57 of the step-up transformer 56 through the main capacitor 53, the diode 55, and a path of opposite polarity to the black circle in the primary winding 57 in the same direction as the i1' shown in the figure, and flows through the negative electrode of the dust collecting electrode 64.
The charge transferred to 64 is returned to the main capacitor 53 for storing input energy. The period τ2' until this pulse current in the same direction as i1' becomes zero again is approximately equal to τ1' determined by the above equation (1).

In this circuit, after GTO54 is turned on, τ1' to τ1' + τ
During this time up to τ2', GTO 54 is in the OFF state due to the turn-off signal input to its gate, so the charge transferred again from the collection electrode 64 to the main capacitor 53 for storing input energy is stored in the main capacitor 53 until a turn-on signal is input again to the gate of GTO 54 after τp' shown in Figure 16, turning GTO 54 on, thereby regenerating energy. At this time, the width of the pulse voltage output from output terminals 59 and 60 of the pulse generating circuit to the collection electrode 64, which is the load, is τ1' + τ2'.

Therefore, the energy input from input DC power supply 51 to main capacitor 53 is the difference between the power supply voltage −E51 of input DC power supply 51 and the regenerated voltage −V53, as shown in FIG. 16, thereby realizing a highly efficient pulse charging type dust collector.

However, this pulse generator needs to generate pulses with high voltage and large current rise rate di/dt, so the main switch is required to have high withstand voltage, large current, and di/d
Semiconductor switching elements such as GTOs with high t resistance are used, connected in series and parallel in numbers commensurate with the withstand voltage, peak current, and di/dt resistance of the elements.

However, when semiconductor switching elements are connected in series and parallel,
In order to select and use semiconductor switches with relatively uniform characteristics and to evenly share the voltage applied between each element and the current that flows when they are connected in series and parallel and operated, it is necessary to strengthen the drive circuit, devise a method for connecting the drive circuit to each semiconductor switch element and for wiring between the main electrodes of each semiconductor switch element, and insert a voltage divider circuit, etc.

This resulted in a problem of the main switch becoming more complex and larger in size, and also in the problem of increased drive power and reduced reliability as the number of semiconductor switch elements connected in series and parallel increased.

Furthermore, when a semiconductor switch element such as a GTO is used for the main switch, due to the limitations of the semiconductor element's di/dt tolerance, Watanabe and Kamejima: "Example of performance improvement of an existing electric dust collector by pulse charging," Pollution and Countermeasures Vol. 25 No. 4, pp. 349-35
3 (1989), the pulse width τ1′+
τ2' was limited to several tens of μs to about 100 μs.

In order to make the pulse width τ1'+τ2' about 10 μs or less, a diode with a large di/dt tolerance is required, as described in Japanese Patent Application Laid-Open No. 61-185350 and Yagyu, Yada, Tsuchiya, Tomimatsu, and Matsumoto, "Current Status and Development Trends of Dust Collection Technology," Mitsubishi Heavy Industries Technical Review, Vol. 27, No. 4, pp. 297-30.
The use of rotary gap mechanical switch elements and discharge tube switch elements such as thyratrons, as described in, for example, J.N.A. 2 (1990), has been considered. However, compared to semiconductor switch elements, mechanical switch elements have limitations on repetition frequency, a significantly shorter lifespan, and low reliability. Furthermore, discharge switch elements such as thyratrons can increase the repetition frequency to the same level as semiconductor switch elements, but like mechanical switch elements, they have a shorter lifespan compared to semiconductor switch elements.
There was also the problem of low reliability.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above-mentioned problems associated with the switching element in a pulse generating device that can regenerate surplus energy supplied to a load.

Another object of the present invention is to provide a dust collecting device using such a pulse generating device.

Disclosure of the Invention In order to solve the above-mentioned problems, the present invention provides a pulse generating device that has an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a saturable reactor, and supplies energy to the load means via the saturable reactor, and is provided with regeneration means that regenerates the energy supplied to the load from one end of the saturable reactor on the load side to the energy storage capacitor.

As a desirable embodiment of the pulse generator of the present invention,
There is provided a pulse generator that supplies energy to a load through a series circuit composed of an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a saturable reactor, the pulse generator including regeneration means for regenerating the energy supplied to the load from one end of the saturable reactor on the load side to the energy storage capacitor, and there is also provided a pulse generator that has an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a magnetic pulse compression circuit using a saturable reactor, the pulse generator including regeneration means for regenerating the energy supplied to the load from the energy storage capacitor via the magnetic pulse compression circuit.

The former uses a magnetic assist circuit, and the latter uses a magnetic pulse compression circuit.

The pulse generator of the present invention, which utilizes the magnetic assist circuit, can delay the rise of the current flowing between the main electrodes of the main switch after the main switch is turned on, thereby significantly reducing switching loss and increasing the di/dt of the main switch. As a result, even if a semiconductor switch element is used for the main switch, it is possible to output a pulse of approximately 10 μs or less, and when a mechanical switch element such as a rotary gap or a discharge tube switch element such as a thyratron is used, it can achieve a long life.

Furthermore, in a pulse generator of the present invention that utilizes a magnetic pulse compression circuit, the di/dt of the main switch can be significantly reduced by the action of the magnetic pulse compression circuit, thereby producing an output pulse with a large di/dt. As a result, when a semiconductor switch is used as the main switch, the number of semiconductor switch elements connected in series and parallel can be reduced, and when a mechanical switch element such as a rotary gap or a discharge tube switch element such as a thyratron is used as the main switch, its life can be extended by about two orders of magnitude.

Furthermore, the present invention achieves high system efficiency by providing energy regeneration means, and is characterized in that this regeneration means is provided at a position where it regenerates energy from one end of the load side of the saturable reactor to the energy storage capacitor.
That is, it is possible to regenerate energy via the saturable reactor, and the inventors have also investigated this, but the regenerated energy is lost in the saturable reactor, and efficient regeneration is not possible. Therefore, the present invention provides an energy regeneration means that regenerates energy from one end of the load side of the saturable reactor to the energy storage capacitor so that the regenerated energy can be regenerated to the energy storage capacitor without passing through the saturable reactor.

The energy regenerating means is preferably a combination of a rectifier and an inductance element such as a reactor.

Furthermore, the rectifier of the energy regeneration means can be realized by a series circuit of a rectifier element and a saturable reactor. In this case, after the energy supplied to the load is regenerated to the input side, the reverse recovery current generated due to the reverse voltage applied to the rectifier element can be suppressed, thereby reducing the reverse recovery loss of the rectifier element and improving reliability, and also reducing the regenerative energy lost due to the flow of the reverse recovery current.

The present invention also provides a pulse generator in which a transformer is provided on the output side of the saturable reactor, and energy is supplied from the energy storage capacitor to load means via the saturable reactor and the transformer.

By providing a transformer, it is possible to output pulses with high voltage peak values with a low input voltage, and it is possible to use a switch element with a low withstand voltage for releasing the charge stored in the energy storage capacitor.

In the pulse generator, the saturable reactor is provided with a resistor so that the saturable reactor can block a voltage pulse for a predetermined period after the main switch is turned on.
A reset circuit may be provided to reset the magnetic flux density of the magnetic core that constitutes the saturable reactor before the main switch is turned on.

By providing such a reset circuit, unstable operation such as time jitter during repeated operation can be prevented, and the saturable reactor and the operating magnetic flux density can be made larger, which also allows for miniaturization.

The pulse charging type dust collector using the pulse generator described above has a simple circuit configuration, ensures safe operation of the main switch element, obtains a large pulse current with di/dt, and can supply a steep high voltage pulse to the dust collection electrode, which is the load.
The regenerative circuit functions to regenerate most of the energy supplied to the dust collection electrode to the input side, which is preferable because it allows for high reliability, high efficiency, and compact size.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a first superposition of a high voltage pulse generator according to the present invention.

FIG. 2 is a diagram showing the concept of the operating magnetization BH loop of the saturable reactor 5 of FIG.

FIG. 3 is a diagram showing voltage and current waveforms at major parts of the circuit of FIG.

FIG. 4 shows an example of a rectifier used in the regeneration circuit of a high-voltage pulse generator according to the present invention, and is a diagram showing the circuit configuration of a rectifier 24 in which a saturable reactor 31 is connected in series with a diode 30 to improve the reverse recovery characteristics of the rectifier.

5 shows the operating magnetization B- of the saturable reactor 31 in FIG.
FIG. 1 illustrates the H-loop concept.

FIG. 6 is a diagram showing the waveform of the current i3 in the main winding 32 of the saturable reactor 31 in FIG.

FIG. 7 is a circuit diagram showing a second embodiment of a high voltage pulse generator according to the present invention.

FIG. 8 is a circuit diagram showing a third embodiment of a high voltage pulse generator according to the present invention.

FIG. 9 shows the operating magnetization B of the saturable reactor 103 in FIG.
FIG. 1 illustrates the H loop concept.

FIG. 10 is a diagram showing voltage and current waveforms at the main parts of the circuit of FIG.

FIG. 11 shows the dust collection electrode 17 and the main capacitor 3 in the circuit of FIG.
FIG.

FIG. 12 is a circuit diagram showing a fourth embodiment of a high voltage pulse generator according to the present invention.

FIG. 13 is a circuit diagram showing a fourth embodiment of a high voltage pulse generator according to the present invention.

FIG. 14 is a diagram showing a circuit disclosed in Japanese Patent Publication No. 57-43067.

FIG. 15 is a diagram showing voltage and current waveforms at the main parts in FIG.

FIG. 16 is a diagram showing voltage and current waveforms at the main parts in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

(Embodiment 1) Figure 1 shows an embodiment of a pulse generator according to the present invention, and shows an example of the circuit configuration when applied to a pulse charging type dust collector. The area enclosed by the dotted line in Figure 1 is the pulse generator, and a GTO (Gate Turn Off Thyristor), which is one of the semiconductor switch elements, is used as the main switch to discharge the charge stored in the main capacitor 3 for storing input energy.
4 is used.

In FIG. 1, 1 is an input DC power supply for a pulse generator;
2 is a charging resistor for the main capacitor 3, 3 is a main capacitor for storing input energy, 4 is a GTO which is a main switch for discharging the charge stored in the main capacitor 3, and 5
is a saturable reactor, 6 is a main winding of the saturable reactor 5, 7 is a reset winding of the saturable reactor 5, 8 and 9 are reset winding ends of the saturable reactor 5, 10 is a diode, 11 is a reactor, 12 is a reactor for limiting di/dt of the GTO 4, 16 and 17 are output ends of the pulse generating circuit, 18 is a capacitor for blocking DC current, 19 is a dust collecting electrode,
Reference numeral 20 denotes a reactor for suppressing surge current, and 21 denotes an input DC power source for applying a DC voltage to the dust collection electrode 19 .

In the figure, a DC voltage E is constantly applied to the collecting electrode 19 with the polarity shown in the figure through a path extending from the positive electrode of the input power source 21, the collecting electrode 19, the surge current suppression reactor 20, and the negative electrode of the input power source 21.

The pulse generator is used to superimpose a high voltage pulse on the DC voltage E applied to the collecting electrode 19. Its operation will be explained using the circuit configuration shown in FIG. 1, the conceptual diagram of the B-H loop operation of the saturable reactor 6 shown in FIG. 2, and the voltage and current waveforms of the main components shown in FIG. 3.

While GTO 4 is off, main capacitor 3 is charged to voltage E with the polarity shown in the figure from input power supply 1 via charging resistor 2. At this time, the operating point of saturable reactor 5 is at point a on the operating B-H loop in Figure 2.

When a gate current flows through the GTO 4 and a predetermined period called storage time determined by the characteristics of the GTO has passed, at time t=0 in FIG. 3, the impedance between the main electrodes of the GTO 4 drops suddenly, and the positive electrode of the main capacitor 3, the dust collection electrode 19,
The charge stored in the main capacitor 3 starts to flow through the DC blocking capacitor 18, the inductance 12, the main winding 6 of the saturable reactor 5, the GTO 4, and the negative electrode of the main capacitor 3. Therefore, the operating point of the saturable reactor 5 is
The operation changes from point a to point b on the BH loop in Fig. 2. During this period, the inductance of the main winding 6 of the saturable reactor 5 is extremely large, so the current flowing through the main winding
i4 is a very small value, which can significantly reduce the switching loss when turning on GTO 4. If loss is ignored, the main winding 6 blocks the voltage of peak value E with the black circle shown as the positive polarity, and becomes V6 in Figure 3.

The time τs during which the main winding 6 of the saturable reactor 5 blocks the voltage is set to a value required for the saturation voltage between the main electrodes to become sufficiently small after the GTO 4 is turned on, and is related by the following equation:

N6: number of turns of the main winding 6 of the saturable reactor 5 Ae: effective cross-sectional area of the saturable reactor 5 (m ² ) ΔBm: operating magnetic flux density of the saturable reactor 5 (T) E: input power supply voltage (V) When the operating point of the saturable reactor 5 reaches point b on the operating B-H loop in FIG. 2, the saturable reactor 5 is saturated,
The inductance of the main winding 6 of the saturable reactor 5 drops suddenly, and the current i4 flowing through the main winding 6 decreases to i12 in FIG.
Although the waveform has a peak value of I4 on the positive side, which is a pulse current with an extremely large di/dt, the voltage between the main electrodes of GTO 4 is a sufficiently low saturation voltage, so the on-state loss of GTO 4 can be sufficiently suppressed. As a result, safe operation can be achieved even if di/dt is several times larger than when saturable reactor 5 is not used. Furthermore, this pulse current causes the operating point of saturable reactor 6 to change from point b, via point C, to point d.

The pulse width τ1 of the pulse current that flows due to saturation of the saturable reactor 5 can be approximated by the following equation:

C: Capacitance of main capacitor 3, DC current blocking capacitor
L6s: Inductance of the main winding 6 of the saturable reactor 5 after saturation (H) L12: Inductance of the reactor 12 (H) This pulse current flows through the positive pole of the main capacitor 3, the dust collecting electrode
19, DC blocking capacitor 81, inductance 1
2. A high voltage pulse having a peak voltage Em indicated by V19 in FIG. 3 flows through the main winding 6 of the saturable reactor 5, the GTO 4, and the negative electrode of the main capacitor 3, and can be applied to the dust collecting electrode 19.

Since the collection electrode 19 is a capacitive load, after the time t = τs + τ1 when the charge is completely transferred to the collection electrode 19, the charge input to the collection electrode 19 becomes a pulse current in the reverse direction and flows through the positive electrode of the collection electrode 19, the main capacitor 3, and the diode.
The current flows through the path of 10, inductance 11, inductance 12, DC current blocking capacitor 18, and the negative electrode of the dust collecting electrode, and energy equivalent to the voltage E' can be regenerated in the main capacitor 3.

The pulse width τ2 of the pulse current i10 is given by the following equation:

L11: Inductance of reactor 11 (H) During this regeneration period, almost no current flows in the opposite direction to the illustrated i4 of GTO 4. If a current flows in the opposite direction, the operating point of saturable reactor 5 changes from point d to point e on the operating B-H loop in Figure 2. At this time, the inductance of main winding 6 of saturable reactor 5 is extremely high compared to the inductance of reactor 11, so
This is because most of the current flows through the i10 path.

Furthermore, during the time period up to time t=τs+τ1+τ2 in FIG. 3,
If the GTO 4 is kept in the OFF state by drawing out the gate current, the regenerated energy can be held in the main capacitor 3 as shown in FIG.

Therefore, the energy supplied from the input power supply 1 to the main capacitor 3 needs to be only the difference between the regenerated voltage E' and the input power supply voltage E.

By the above operation, the dust collecting electrode 19 is charged according to the formulas (3) and (4).
A high voltage pulse with a pulse width τ1 + τ2 calculated from the formula can be applied. The voltage waveform applied to the dust collection electrode 19 is shown as V19 in Figure 3.

Here, in order to shorten the pulse width τ1+τ2 of the high voltage pulse applied to the dust collecting electrode 19, it is more advantageous to shorten τ2 than to shorten τ1 for the following reasons.

The pulse width τ of the pulse current flowing through the main winding 6 due to the saturation of the saturable reactor 5 is maintained at a certain value while the period τs during which the main winding 6 of the saturable reactor 5 blocks the voltage is maintained at a certain value.
To shorten 1, as can be seen from equation (3),
The inductance L6s after saturation of the main winding 6 of the saturable reactor 5 must be reduced.
s is a constant value, that is, the effective cross-sectional area Ae of the saturable reactor 5
And because the number of turns of the main winding 6 is a fixed value, it is necessary to increase the average magnetic path length 1e of the saturable reactor 5. Therefore, shortening τ1 will result in an increase in the size of the saturable reactor 5. Also, shortening the pulse width τ1 increases the di/dt of the GTO 4, which has the adverse effect of increasing the switching loss when the GTO is turned on.

On the other hand, as can be seen from equation (4), in order to shorten τ2, it is sufficient to reduce the inductance L11 of the reactor 11. For example, this can be achieved by reducing the inductance L11 of the diode 10 and the reactor 12.
This can be realized with a simple configuration in which the reactor 11 between the diode 10 and the inverter 10 is omitted and only wired. Also, even if the peak value 110 of the current i10 flowing through the diode 10 increases due to the shortening of τ2, and loss due to reverse recovery current becomes a problem, loss due to reverse recovery current can be suppressed by using a rectifier 24 shown in Fig. 4 (to be described later) instead of the diode 10.

From an appropriate time t=τ3 after GTO4 has turned off until GTO4 is turned on again, a reset current is passed from 8 to 9 at the reset winding end of saturable reactor 5, thereby resetting the operating point of saturable reactor 5 to point a again via point f on the operating B-H loop in Figure 2.

By repeating the same operation, it is possible to generate a small, highly reliable pulse current with a large current rise rate di/dt using semiconductor switching elements, and high efficiency can also be achieved through the action of the regenerative circuit.

The value of the voltage E' regenerated in the main capacitor 3 is reduced by the reverse recovery current of the diode 10, which is generated by the reverse voltage applied to the diode 10 after t = τs + τ1 + τ2 in Figure 3. Therefore, it is necessary to use a diode with excellent reverse recovery characteristics for the diode 10. However, since it is difficult to obtain a diode with high breakdown voltage and excellent reverse recovery characteristics, the diode 10 shown in Figure 4
The rectifier 24 shown in the dashed line is connected to the diode 10 shown in FIG.
By using it instead of the reverse recovery characteristic can be improved.

In FIG. 4, 31 is a saturable reactor, 32 is a main winding of the saturable reactor 21, 33 is a bias winding of the saturable reactor 31, 34 is a reactor for suppressing surge current, 35 is a resistor, 36 is a DC power supply, 37 is an anode, and 38 is a cathode.

The operation of the rectifier 24 when the rectifier of FIG. 4 is used instead of the diode 10 of FIG. 1 will be explained using the circuit configuration of FIG. 4, the conceptual diagram of the B-H loop operation of the saturable reactor 31 of FIG. 5, the voltage and current waveforms of each part of FIG. 3, and the waveform of the current i3 of the main winding 32 of the saturable reactor 31 of FIG. 6.

A DC current Ic shown in FIG. 4 is always passed through the bias winding 33 of the saturable reactor 31, and the saturable reactor 31 is DC magnetized to the polarity of the black circle shown in FIG.
Therefore, the operating point of the saturable reactor 31 is the operating point B of FIG.
-It is at point a' on the H loop.

When the anode 37 and cathode 38 of the rectifier 24 are forward biased at time t=τs+τ1, a pulse width τ3 shown in FIG.
4 flows through the main winding 32 of the saturable reactor 31, magnetizing the saturable reactor 31 with the polarity of the black circle in the figure. As a result, the operating point of the saturable reactor 31 moves from point a' in Figure 5 to point b' and then back to point a' again.

At time t=τs+τ1+τ2, the anode 37 and cathode 38 of the rectifier 24 are reverse biased, and the diode 30
The charge stored in the junction capacitance of starts to flow in the direction opposite to i3 in Fig. 4. As a result, the operating point of the saturable reactor 31 changes from point a' to point d' in Fig. 5 via point c'.

The operating point of the saturable reactor 31 changes from point a' in FIG.
When the coercive force reaches the maximum at point d' via point c' and changes to point d', if its value is Hd', the peak value of the reverse recovery current -Ir3 is given by the following equation (5):

Ie': average magnetic path length (m) of the saturable reactor 31 N32: number of turns of the main winding 32 of the saturable reactor 31 When the charge stored in the diode 30 is lost, the DC magnetizing force caused by the DC current Ic flowing through the bias winding 33 causes the operating point of the saturable reactor 31 to return from point d' to point a' again via point e'.

The above operations are repeated.

As a result, by using the rectifier 24 shown in FIG. 4, the reverse recovery current can be suppressed as shown by the solid line in FIG. 6 compared to when the diode 11 shown by the dotted line in the same figure is used, and the reverse recovery loss of the rectifier can be significantly reduced, and the loss of energy regenerated in the main capacitor 3 due to the flow of the reverse recovery current can also be suppressed.

As a result, while ensuring safe operation of the main switch, it is possible to repeatedly generate a pulse current with a large current rise rate di/dt, and by the action of the regenerative circuit,
High efficiency can also be achieved.

(Embodiment 2) Figure 7 shows another embodiment of the high-voltage pulse generator according to the present invention, and shows an example of the circuit configuration when applied to a pulse-charging electrostatic precipitator. The pulse generator is enclosed within the wavy line in the figure. Note that the same parts as in embodiment 1 are given the same reference numerals.

The basic operating principle of the pulse generating circuit of this embodiment is the same as that of the first embodiment, except that a step-up transformer 13 is provided so that a high-voltage pulse having a peak value higher than the input DC power supply voltage 1 can be applied to the dust collecting electrode 19.

That is, after the GTO 4 is turned on, the saturable reactor 5 is saturated, and a pulse current flows from the side of the primary winding 14 of the step-up transformer 13 opposite in polarity to the black circle in the figure, and flows from the side of the secondary winding 15 of the transformer 13 opposite in polarity to the black circle in the figure to the dust collecting electrode 19, the DC current blocking capacitor 18, and the secondary winding 15.
In addition to the power supply voltage of the input DC power supply 1 that is preliminarily applied with the polarity shown in the figure, a high voltage pulse with a peak value according to the turn ratio of the step-up transformer 13 with the polarity shown in the figure is superimposed on the dust collecting electrode 19.
Since the dust collecting electrode 19 is a capacitive load, after the charge is completely transferred to the dust collecting electrode 19, the charge transferred to the dust collecting electrode 19 becomes a pulse current in the reverse direction, and flows through the positive pole of the dust collecting electrode 19 and the step-up transformer 13.
secondary winding 15, DC blocking capacitor 18, dust collecting electrode
Therefore, the current flows through the negative pole of the primary winding 14 of the step-up transformer 13.
The black circle and reverse polarity of the main capacitor 3 and diode 1
0, inductance 11, inductance 12, step-up transformer 1
A pulse current flows through the path of the polarity indicated by the black circle in the primary winding 14 of 3, and energy can be regenerated in the main capacitor 3.

Furthermore, when the step-up transformer 13 is not used as in the first embodiment, the input DC power supply 21 for applying a DC voltage to the collecting electrode 19 and the input DC power supply 1 of the pulse generator must be separate, and the power supply voltage of the latter must be higher than that of the former. However, when the step-up transformer 13 is provided in the pulse generator, the input DC power supply voltage for applying a DC current to the collecting electrode 19 and the input DC power supply voltage of the pulse generator can be the same as shown in this embodiment, and therefore the input DC power supply 1 of the pulse generator can also be used as the input DC power supply for applying a DC voltage to the collecting electrode 19.

(Embodiment 3) Figure 8 is a diagram showing one embodiment of a pulse generator using a magnetic pulse compression circuit according to the present invention, and shows an example of the circuit configuration when a GTO, which is a type of semiconductor switch element, is used as the main switch for discharging the charge stored in the main capacitor 3 for storing input energy and is applied to a pulse charging type dust collector.

In FIG. 8, 1 is an input DC power supply, 2 is a charging resistor for a main capacitor 3, 3 is a main capacitor for storing input energy, 4 is a GTO which is a main switch for discharging the charge stored in the main capacitor 3, 101 is a diode, 12
is a reactor for limiting di/dt of GTO4, 102 is a capacitor for configuring a magnetic pulse compression circuit, 103 is a saturable reactor for configuring a magnetic pulse compression circuit,
Reference numeral 104 denotes a resistor, 10 denotes a diode, 11 denotes a reactor, 16 and 17 denote output terminals of the pulse generating circuit, 21 denotes a second input DC power supply, 20 denotes a reactor for suppressing surge current, 18 denotes a capacitor for blocking DC current, and 19 denotes a dust collecting electrode.

In FIG. 8, the positive electrode of the input DC power supply 21, the dust collecting electrode 19,
A DC current E21 is constantly applied to the dust collection electrode 19 in the direction opposite to the direction of V19 in the diagram through the surge current suppression reactor 20 and the negative electrode of the input DC power supply 21.
A DC voltage -E21 is applied to GND.

The portion enclosed by the dashed line in Fig. 8 is the pulse generator, which has the function of superimposing a negative high voltage pulse on the DC voltage -E21 applied to the collection electrode 19. Its operation will be explained using Fig. 8, which shows the circuit configuration, Fig. 9, which shows the B-H loop concept of the operation of the saturable reactor 103 in Fig. 8, and Fig. 10, which shows the voltage and current waveforms of the main parts in Fig. 8.

In this embodiment, in order to achieve high efficiency, the ratio of the capacitance of the main capacitor 3, the capacitance of the capacitor 102, the capacitance of the DC current blocking capacitor 18, and the capacitance of the dust collecting electrode 19 is set to 1.
The time was 1:11:120:12.

During the period when the GTO 4 is off, the main capacitor 3 is charged from the input power supply 1 through the charging resistor 2 to a voltage E1 in the opposite polarity to V3 shown in the figure, that is, to -E1 with respect to GND.

At this time, the operating point of the saturable reactor 103 is at point a on the operating BH loop in FIG.

At time t=0 in FIG. 3, when a gate current flows through GTO 4 and a predetermined period called storage time determined by the characteristics of the GTO has passed, the impedance between the main electrodes of GTO 4 drops suddenly, and the current flows from the GND side of main capacitor 3 to capacitor 1.
8 through the path opposite to GND of main capacitor 3, through reactor 12, GTO 4, and main capacitor 3, the charge stored in main capacitor 3 is transferred to capacitor 102, and capacitor 102 is charged with a polarity opposite to V102 shown in the figure.

Therefore, the operating point of the saturable reactor 103 changes from point a to point b on the operating BH loop in Fig. 9. Since the inductance of the saturable reactor 103 during this period is extremely large, the inductance of the saturable reactor 103 is changed to point i in Fig. 8.
10, the current i2 flowing in the opposite direction to current 2 is very small, and the saturable reactor 103 blocks a voltage that is almost the same as voltage V102 of capacitor 102 shown in FIG.
That is, the saturable reactor 103 blocks a voltage substantially equal to the voltage V102 in FIG. 10, with the black circle in FIG. 8 as the negative pole.
Therefore, the switching loss when the GTO 4 is turned on can be significantly reduced.

The peak value of the current i1 flowing through GTO4, −I1, and di1/dt are
The time τ1 during which the saturable reactor 103 blocks the voltage V102 is set so that the voltage V102 is within the rated value of O4, and this τ1 can be approximated by the following formula.

N103: Number of turns of saturable reactor 103 Ae: Effective cross-sectional area of saturable reactor 103 ( ^m2 ) ΔBm: Operating magnetic flux density of saturable reactor 103 (T) E1: Input power supply voltage (V) In order for the charge stored in main capacitor 3 at this time to be completely transferred to capacitor 102, the following equation must be satisfied.

C: capacitance of main capacitor 3 (F) L12: inductance of reactor 12 (H) When the operating point of saturable reactor 103 reaches point b on the operating B-H loop in Figure 9, saturable reactor 103 is saturated, the inductance of saturable reactor 103 drops sharply, and an extremely large pulse current with a peak value of -I2, pulse width τ2, and di/dt flows through saturable reactor 103, as shown by the solid line in Figure 10. This pulse current also changes the operating point of saturable reactor 103 from point b to point c
It changes through point d to point d.

Here, τ2 is given by the following formula:

C: capacitance of capacitor 102 (F) L103s: inductance after saturation of saturable reactor 103 (H) Also, pulse width τ1 of current i1 and pulse width τ2 of current i2
The ratio τ1/τ2 is called the compression ratio, and the following equations (9) and (10) hold true.

I2/I1=τ1/τ2 (9) di2/dt=(τ1/τ2) ² ·(di1/dt) (10) Therefore, by using a magnetic pulse compression circuit that uses saturable reactor 103, it is possible to supply pulses with di/dt that are the square of the compression ratio τ1/τ2 to the collection electrode, which is the load, compared to when a magnetic pulse compression circuit is not used.

This pulse current i2 flows from the GND side of capacitor 102 through collection electrode 19, DC current blocking capacitor 18, saturable reactor 103, and the path opposite to the GND side of capacitor 102, and a pulse voltage of opposite polarity to V19 in FIG. 8 can be applied to collection electrode 19.

The impedance of the resistor 104 is sufficiently larger than the impedance of the series circuit of the DC blocking capacitor 18 and the dust collecting electrode 19, so the current flowing through the resistor 104 is negligibly small compared to the pulse current i2.

Since the collection electrode 19 is a capacitive load, after the time t = τ1 + τ2 when the charge is completely transferred to the collection electrode 19, the charge input to the collection electrode 19 becomes a pulse current with a pulse width τ3 shown by the dashed line i3 in FIG. 10 in the opposite direction to the pulse current i2, and flows from the GND side of the collection electrode 19 to the main capacitor 3,
The current flows through the diode 10, reactor 11, DC current blocking capacitor 18, and the path opposite to the GND of the dust collection electrode 19. As a result, energy equivalent to the voltage −V3′ shown in FIG. 10 can be regenerated in the main capacitor 3.

τ3 is given by the following equation 11.

C: capacitance of capacitor 3 (F) L11: inductance of reactor 11 (H) During the period when this pulse current i3 is flowing, a voltage with a positive polarity indicated by the black circle in FIG. 8 is applied to saturable reactor 103, and the operating point of the saturable reactor 103 is the same as that of operation B in FIG.
The voltage changes from point d to point e on the -H loop. At this time, the inductance of the saturable reactor 103 is extremely large, so that almost no current flows through the saturable reactor 103.

Furthermore, during the time period up to time t=τ1+τ2+τ3 in FIG. 10,
If GTO4 is turned off by drawing out its gate current, the regenerated energy can be held in the main capacitor 3 as shown in Figure 10, and the energy supplied from the input power supply 1 to the main capacitor 3 will be just the difference between the regenerated voltage -V3' and the input power supply voltage -E3.

An appropriate time t after time t=τ1+τ2+τ3 in FIG.
=τ4, the time t to turn on GTO4 again is t=τp
During this time, the saturable reactor 103 and the operating point must be reset to point a again via points e and f in Figure 9. The energy required for this reset is often obtained from the minute energy that could not be regenerated from the dust collection electrode 19 to the main capacitor 3, but if necessary, it can be obtained by resetting the saturable reactor 103 and the operating point to point a again via points e and f in Figure 9.
A reset circuit may be provided to reset the polarity of the saturable reactor 103 to the polarity of the black circle shown in the figure.

By repeating the same operation thereafter, a voltage V19 in Figures 10 and 11, which is a superimposed pulse voltage with a pulse width τ+τ3 calculated using Equations 8 and 11, can be applied to the collection electrode 19. The voltage of the main capacitor 3 becomes V3 in Figures 10 and 11.

The absolute value of the regenerated voltage -V3' of the main capacitor 3 is the reverse voltage applied to the diode 10 after the time t=τ1+τ2+τ3 in FIG.
Therefore, similarly to the first embodiment, the reverse recovery characteristic can be improved by using a rectifier 24 shown in the dashed line in FIG. 4 instead of the diode 10 shown in FIG. 8.

As a result, it is possible to repeatedly generate a pulse current with a large current rise rate di/dt while ensuring safe operation of the main switching element, and high efficiency can also be achieved through the action of the regenerative circuit.

(Embodiment 4) Figure 12 shows another embodiment of a pulse generator using a magnetic pulse compression circuit according to the present invention, and shows an example of the circuit configuration when applied to a pulse charging type dust collector in which a GTO is used as the main switch for discharging the charge stored in the input energy storage capacitor 3, and a pulse voltage is applied to the dust collection electrode 19 via a step-up transformer 13 provided on the output side of the magnetic pulse compression circuit.
The same parts are denoted by the same reference numerals.

In FIG. 12, 1 is an input power supply, 2 is a charging resistor for a main capacitor 3, 3 is a main capacitor for storing input energy,
4 is a GTO which is a main switch for discharging the charge stored in the main capacitor 3, 101 is a diode, and 12 is a GT
A reactor for limiting di/dt of O4, 102 a capacitor for configuring a magnetic pulse compression circuit, 103 a saturable reactor for configuring a magnetic pulse compression circuit, 13 a step-up transformer, 14 a primary winding of the step-up transformer 13, 15 a secondary winding of the step-up transformer 13, 11 a diode, 10 a reactor,
Numerals 16 and 17 are output terminals of the pulse generating circuit, 18 is a capacitor for blocking direct current, 19 is a dust collecting electrode, and 20 is a reactor for suppressing surge current.

In this embodiment, taking efficiency into consideration, the capacitances of the main capacitor 3, the capacitor 102, the DC current blocking capacitor 18, and the dust collection electrode 19 are set to 175:175:120:12
In addition, the primary winding 14 and the secondary winding 15 of the step-up transformer 13 are
The turns ratio was set to 1:4.

In FIG. 12, in the path of the positive electrode of the input power supply 1, the dust collection electrode 19, the surge current suppression reactor 20, and the negative electrode of the input power supply 1, the DC voltage E1 flows in the opposite direction to the direction of V19 shown in the figure.
That is, a DC voltage −E1 is applied to the collection electrode 19 with respect to GND.

The pulse generating circuit is shown within the broken line in FIG. 12, and is used to superimpose a high voltage in a pulsed manner on the DC voltage E1 applied to the dust collecting electrode 19. The basic operation of the pulse generating circuit is the same as that of the third embodiment, and the step-up transformer 13
The difference is that the boosted pulse voltage is applied to the dust collection electrode 19 .

The time τ1 during which the saturable reactor 103 blocks the voltage is
In the same manner as in the third embodiment, the setting is made so as to satisfy the formula 6.

In order for the charge stored in the main capacitor 3 to be completely transferred to the capacitor 102, the above-mentioned formula 7 must be satisfied, as in the third embodiment.

After the saturable reactor 103 is saturated, the saturable reactor 1
The pulse width τ2′ of the pulse current i2′ flowing through O3 is given by the following equation:

C: capacitance of capacitor 102 (F) L103s: inductance after saturation of saturable reactor 103 (H) L131: leakage inductance seen from primary winding 14 of step-up transformer 13 (H) When this pulse current i2' is input to primary winding 14 of step-up transformer 13, it flows from the opposite polarity side of secondary winding 14 of step-up transformer 13 to collecting electrode 19, DC blocking capacitor 18, and the black circle side of secondary winding 15, and a high-voltage pulse with a voltage peak value according to the turns ratio of step-up transformer 13 can be applied to collecting electrode 19.

Because the collection electrode 19 is a capacitive load, after the time t = τ1 + τ2' when the charge has been completely transferred to the collection electrode 19, the charge input to the collection electrode 19 flows as a pulse current from the GND side of the collection electrode 19 through the main capacitor 3, the secondary winding 15 of the step-up transformer 13, the DC blocking capacitor 18, and the path opposite the GND side of the collection electrode 19.

This pulse current flowing through the secondary winding 15 of the step-up transformer 13 causes a pulse current i
12, flows from the side of the primary winding 14 of the step-up transformer 13 indicated by the black circle in the figure, opposite in polarity, through the main capacitor 3, the diode 10, the reactor 11, and the black circle side of the primary winding 14 of the step-up transformer 13, and energy can be regenerated in the main capacitor 3.

The pulse width τ3′ of the pulse current i3′ is given by the following equation:

C: capacitance of capacitor 3 (F) L11: inductance of reactor 11 (H) At this time, the operating point of saturable reactor 103 changes from point d to point e on the operating B-H loop in Figure 9 due to the voltage applied to saturable reactor 103 via step-up transformer 13. Since the inductance of saturable reactor 103 at this time is extremely large, almost no current flows through saturable reactor 103.

Furthermore, if the gate current is drawn out to keep GTO 4 in the OFF state until time t=τ1+τ2'+τ3', the regenerated energy can be held in the main capacitor 3.

Therefore, the energy supplied from the input power supply 1 to the main capacitor 3 needs to be only the difference between the regenerated voltage and the input power supply voltage E1.

An appropriate time t after time t=τ1+τ2'+τ3'
From τ4 to the time t=τp when GTO4 is turned on again, the operating point of the saturable reactor 103 becomes
It is necessary to reset the voltage to point a again via points f and f. The energy required for this reset is often obtained from the minute amount of energy that was not regenerated from the dust collection electrode 19 to the main capacitor 3, but if necessary, a reset circuit for resetting the polarity to the black circle shown in Figure 12 for the saturable reactor 103 during the period from time t = τ4 to t = τp may be provided.

By the above operation, a high voltage pulse having a pulse width τ2'+τ3' calculated from the formulas (12) and (13) can be superimposed on the dust collection electrode 19.

By repeating the same operation, the current rise rate di
It is possible to generate a large pulse current with a frequency of 1/dt, and the regenerative circuit also makes it possible to achieve high efficiency.
Furthermore, by using the step-up transformer 13 in combination, a high voltage pulse can be superimposed on the dust collecting electrode 19 using a main switch with a low withstand voltage, which has the advantage of simplifying the configuration of the main switch and improving reliability even if a semiconductor switch element is used for the main switch.

In the above embodiment, an example of application of a pulse generating circuit using a single-stage magnetic pulse compression circuit according to the present invention to a pulse dust collector has been described. However, it goes without saying that the same effect can be obtained in the case of a multi-stage magnetic pulse compression circuit, or in the case of other loads in which surplus energy is supplied to the load.

(Embodiment 5) FIG. 13 shows an embodiment of a high voltage pulse generator using a magnetic pulse compression circuit according to the present invention. A GTO (Gate Tolerance) is used as a main switch for discharging the charge stored in the main capacitor 3 for storing input energy.
1 shows an example of a circuit configuration when a pulse charging type dust collector is used with a turn-off thyristor (Turn-Off Thyristor) 4.

The same parts as those in the fourth embodiment are denoted by the same reference numerals.

In FIG. 13, 1 is an input power supply, 2 is a charging resistor for the main capacitor 3, 3 is a main capacitor for storing input energy, and 4
indicates a GTO which is a main switch for discharging the charge stored in the main capacitor 3, 101 indicates a diode, 105 indicates a saturable reactor, 102 indicates a capacitor for configuring a magnetic pulse compression circuit, 103 indicates a saturable reactor for configuring a magnetic pulse compression circuit, 13 indicates a step-up transformer, 14 indicates a primary winding of the step-up transformer 13, 15 indicates a secondary winding of the step-up transformer 13, and 16 indicates a
and 17 is the output terminal of the pulse generating circuit, 10 is a diode,
11 is a reactor, 18 is a capacitor for blocking DC current, 19
denotes a dust collecting electrode, and 20 denotes a reactor for suppressing surge current.

The basic operation of this embodiment is the same as that of the fourth embodiment, but a saturable reactor is connected in series with the GTO4, which is the main switch.
The difference is that saturable reactor 105 is provided. By connecting saturable reactor 105 in series with GTO 4, it is possible to reduce the switching loss that occurs when GTO 4 is turned on.
Therefore, when a GTO of the same rating is used, the current rise rate di/dt can be increased by several times or more compared to the fourth embodiment, and an output pulse with greater energy can be obtained.

In this embodiment, an example of application of the present invention to a pulse dust collector has been described, but it goes without saying that the same effect can be obtained in the case of other loads in which impedance matching cannot be achieved between the pulse generating circuit and the load.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the surplus energy supplied to the load can be regenerated in the input energy storage capacitor without passing through a saturable reactor, thereby providing a highly efficient pulse generator.

In particular, when the high voltage pulse generator according to the present invention is used in a dust collector of the pulse charging type, it is possible to dramatically improve the efficiency and reliability that have been problems in conventional devices.

Claims (15)

[Claims] [Claim 1] A pulse generator having an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a saturable reactor, which supplies energy to the load means via the saturable reactor, and which is characterized in that it further includes regeneration means for regenerating the energy supplied to the load from one end of the saturable reactor on the load side to the energy storage capacitor. 2. The pulse generator according to claim 1, wherein said regenerating means comprises a rectifier and an inductance element. [Claim 3] A pulse generator that supplies energy to a load through a series circuit consisting of an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a saturable reactor, characterized in that the pulse generator is provided with regeneration means that regenerates the energy supplied to the load from one end of the load side of the saturable reactor to the energy storage capacitor. [Claim 4] A pulse generator that supplies energy to a load through a series circuit consisting of an energy storage capacitor, a main switch for releasing the charge stored in the energy storage capacitor, a saturable reactor, and a transformer, characterized in that the pulse generator is provided with regeneration means that regenerates the energy supplied to the load from one end of the saturable reactor on the load side to the energy storage capacitor via the transformer. [Claim 5] A pulse generator that supplies energy to a load through a series circuit consisting of an energy storage capacitor, a main switch for discharging the charge stored in the energy storage capacitor, and a saturable reactor, characterized in that the pulse generator is provided with regeneration means consisting of a rectifier and an inductance element for regenerating the energy supplied to the load in the energy storage capacitor. 6. The rectifier according to claim 5, wherein the rectifier is configured by connecting a rectifying element and a saturable reactor in series for limiting the reverse recovery current of the rectifying element.
Item 1. A pulse generator according to item 1. [Claim 7] A pulse generator that supplies energy to a load through a series circuit consisting of an energy storage capacitor, a main switch for releasing the charge stored in the energy storage capacitor, a saturable reactor, and a transformer, characterized in that it further comprises regeneration means consisting of a rectifier and an inductance element that regenerates the energy supplied to the load into the energy storage capacitor via the transformer. 8. The pulse generator according to claim 7, wherein the rectifier is configured by connecting a rectifying element and a saturable reactor in series for limiting the reverse recovery current of the rectifying element. [Claim 9] A pulse generating device comprising: an energy storage capacitor; a main switch for discharging the charge stored in said energy storage capacitor; and a magnetic pulse compression circuit using a saturable reactor; said pulse generating means supplies energy from said energy storage capacitor to a load means via said magnetic pulse compression means; and further comprising regeneration means for regenerating the energy supplied to said load from one end of the load side of the saturable reactor constituting said magnetic pulse compression circuit back into the energy storage capacitor. 10. A pulse generating device comprising: an energy storage capacitor; a main switch for discharging the charge stored in said energy storage capacitor; and a magnetic pulse compression circuit using a saturable reactor; said pulse generating means supplies energy from said energy storage capacitor to a load means via said magnetic pulse compression means; and further comprising regeneration means consisting of a rectifier and an inductance element for regenerating the energy supplied to said load from one end of the load side of the saturable reactor constituting said magnetic pulse compression circuit back into the energy storage capacitor. 11. The pulse generator according to claim 10, wherein the rectifier is configured by connecting a rectifying element and a saturable reactor in series for limiting the reverse recovery current of the rectifying element. [Claim 12] A pulse generator having an energy storage capacitor, a main switch for releasing the charge stored in the energy storage capacitor, a magnetic pulse compression circuit using a saturable reactor, and a transformer, which supplies energy to load means via the magnetic pulse compression circuit and the transformer, characterized in that the pulse generator further comprises regeneration means for regenerating the energy supplied to the load via the transformer from one end on the load side of the saturable reactor constituting the magnetic pulse compression circuit to the energy storage capacitor. [Claim 13] A pulse generator having an energy storage capacitor, a main switch for releasing the charge stored in the energy storage capacitor, a magnetic pulse compression circuit using a saturable reactor, and a transformer, and supplying energy to load means via the magnetic pulse compression circuit and the transformer, characterized in that the pulse generator further comprises regeneration means consisting of a rectifier and an inductance element for regenerating the energy supplied to the load via the transformer from one end on the load side of the saturable reactor constituting the magnetic pulse compression circuit to the energy storage capacitor. 14. The rectifier according to claim 1, wherein the rectifier is configured by connecting a rectifying element and a saturable reactor for controlling a reverse recovery current of the rectifying element in series.
14. A pulse generator according to item 13. 15. A pulse charging type dust collector, characterized in that the pulse generator according to any one of claims 1 to 14 is used and the load is a dust collecting electrode.