JP2002345263A - Power supply unit for silent discharge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit for silent discharge capable of suppressing noise and loss at turning off a switching device. SOLUTION: This power supply unit includes a power supply 2 for supplying direct current; a silent discharge electrode 3; a transformer 5 whose power supply 2 is connected to a primary coil 6, the silent discharge electrode 3 is connected to a secondary coil 4 with a choking coil 10; a switching device 7 which controls power supply with the power supply 2 to the primary coil 6; a detection means which detects the current of the primary coil 6; and a control circuit 9 which detects a changing rate of the current detected by the detection means and which performs the off-control of the switching device 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for silent discharge used for an ozone generator having a silent discharge electrode.

[0002]

2. Description of the Related Art Conventionally, in an ozone generator provided with a rectangular wave inverter type silent discharge power supply device without using a choke coil, the silent discharge electrode is a capacitive load immediately after a voltage is applied to the silent discharge electrode. Therefore, an inrush current containing many harmonic components flows to the silent discharge power supply device, and so-called noise is generated. Further, after the inrush current flows, the primary current value of the transformer of the silent discharge power supply device gradually increases, so that a loss during control for turning off the switching element (hereinafter, referred to as “switching loss”). ) Is a problem. Here, the switching loss is a heat loss represented by a product of a current value and a voltage value flowing through the switching element. On the other hand, in an ozone generator equipped with a power supply for silent discharge using a choke coil, the oscillation occurs between the choke coil and the silent discharge electrode while the inrush current is reduced by the choke coil. Has a pseudo-sinusoidal waveform having a rising tendency. But at this time,
If control is performed to turn off the primary current value when the primary current value is relatively large, the switching loss increases and noise is generated due to a surge voltage.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply for silent discharge which can reduce generation of noise and switching loss of a switching element.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 comprises a power supply for supplying a direct current, a silent discharge electrode, and A transformer connected to the secondary coil, the silent discharge electrode connected to the secondary coil, and a choke coil, a switching element for controlling the supply of power to the primary coil, and a current flowing through the primary coil. And a control circuit for controlling a turning-off of the switching element by detecting a change rate of the current value detected by the detecting means.

[0005]

Next, an embodiment of the present invention will be described. In the following description, a silent discharge power supply device used for an ozone generator will be described as a preferred embodiment.

A power supply apparatus for silent discharge in this embodiment includes a transformer having a choke coil, a switching element for controlling supply of power to a primary coil of the transformer, and detecting a current value of the primary coil. The control device includes a detecting unit and a control circuit that detects a rate of change of the current value detected by the detecting unit and controls on / off of the switching element. Here, there are three embodiments of the detection means.

First, the detecting means in the first embodiment is constituted by means for detecting the current value of the primary coil, for example, electromagnetic induction type detecting means. This electromagnetic induction type detecting means can obtain an output proportional to the rate of change of the current value of the primary coil.

The ozone generator can eliminate noise by turning off the switching element at the point where the current of the primary coil crosses zero (point where the current value becomes zero). If the current value on the primary side of the transformer fluctuates greatly, and zero crossing does not occur, it is necessary to perform control to turn off the current value at an optimal timing in order to reduce noise and switching loss. For this reason, in this embodiment, when the current value detected by the electromagnetic induction detecting means is at a minimum, the open signal supplied from the controller to the gate of the switching element is closed. Control to switch to a signal and to turn off the switching element. Thereby, the generation of the noise and the switching loss are reduced.

Next, a second embodiment will be described. The second embodiment is a modification of the first embodiment. That is, a current-voltage converter is used in place of the electromagnetic induction type detection means. The converter-type detecting means in the second embodiment is constituted by, for example, a Hall element or a resistance element.

[0010] Then, by the conversion device type detection means,
The current value of the primary coil is converted into a voltage value, the rate of change of the voltage value is input to a differential operation circuit, and at a timing according to an output signal from the differential operation circuit, that is, the conversion device type detection means When the current value of the primary coil detected by the control circuit becomes minimum, the open signal supplied to the gate of the switching element is switched to the close signal by the control circuit. Thereby, the generation of the noise and the switching loss are reduced.

Next, a third embodiment will be described. The third embodiment is a further modification of the second embodiment. That is, the change rate of the current value (change rate of the converted voltage value) in the second embodiment.
When calculating, a differential operation circuit as an independent circuit is provided, a current value of the primary side coil is input to the differential operation circuit, an output signal from the differential operation circuit is further input to the control circuit, The open signal supplied to the gate of the switching element is switched to a close signal.

When the current value of the primary coil detected by the converter type detecting means is at a minimum, the open signal supplied from the controller to the gate of the switching element is converted to a closed signal. The switching is performed, and control for turning off the switching element is performed.
Thereby, the generation of the noise and the switching loss are reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. The following description specifically describes a case where the present invention is applied to an ozone generator. The first embodiment will be described in detail with reference to FIGS. FIG. 1 is a schematic electric circuit diagram of a first embodiment of the present invention.

In FIG. 1, the power supply device 1 for silent discharge is shown.
Is connected to a power supply 2 for supplying a direct current, a silent discharge electrode 3 for performing a silent discharge to generate ozone, and the power supply 2 to a primary coil 6, and connecting the silent discharge electrode 3 to a secondary coil 4. A transformer 5 which is connected and has a choke coil 10, a switching element 7 for controlling the power supply of the power supply 2 to the primary coil 6, and a detection coil for detecting a current value of the primary coil 6 (symbols are omitted) ), And a control circuit 9 for controlling the switching element 7 to turn on and off.

The positive line of the power supply 2 (symbol omitted)
Is connected to one end (not shown) of the primary coil 6 and a positive power supply terminal (not shown) of the control circuit 9. The negative side line (symbol omitted) of the power supply 2 is
It is connected to a negative power supply terminal (symbol omitted) of the control circuit 9. A negative line (reference number omitted) of the power supply 2 penetrates a detection coil of the electromagnetic induction detecting means 8 and is connected to a minus terminal (reference number omitted) of the switching element 7.

Here, the configuration of the choke coil 10 will be described. This configuration has two configuration examples. First, as a first configuration example, the leakage inductance of the transformer 5 is a choke coil component, and is not a specific substance. The transformer 5 has a configuration in a so-called parasitic state. Next, as a second configuration example, a choke coil 10 externally attached to the transformer 5 is combined. In any case, on the schematic electric circuit diagram of FIG.
It can be described that the choke coil 10 is connected to the primary coil 6 in series. That is,
The transformer 5 includes the primary side coil 6 and the choke coil 10 connected in series on a primary side, and includes the secondary side coil 4 on a secondary side.

The silent discharge electrode 3 is an electrode for performing a silent discharge. The silent discharge is performed between a pair of electrodes (in FIG. 1, reference numerals 11 and 12). In addition, since the discharge is uniformly performed over the entire surfaces of the two electrodes 11 and 12, the discharge does not emit a sound such as a spark discharge. The insulator functions as a dielectric, and the pair of electrodes 11 and 12 have a so-called capacitance (capacitor) component. And this pair of electrodes 1
Reference numerals 1 and 12 are connected to the secondary coil 4 for boosting via electric wires (symbols are omitted).

The switching element 7 controls the supply of the power source 2 to the primary coil 6, and is composed of a semiconductor element, for example, a MOSFET. The negative terminal of the switching element 7 is connected to the negative line of the power supply 2 via the electromagnetic induction detecting means 8. The plus side terminal (symbol omitted) of the switching element 7 is connected to the choke coil 10.
Is connected to The switching element 7 includes a gate 13 that receives an open / close signal from the control circuit 9.

The electromagnetic induction type detecting means 8 is a means for detecting a current value of the primary side coil 6 flowing through the switching element 7, and detects a current with the detecting coil. That is, the electromagnetic induction type detection means 8 can obtain an output proportional to the rate of change of the current value of the primary side coil 6 flowing through the detection coil. Both ends (reference numerals omitted) of the detection coil are connected to the control circuit 9 via lines (reference numerals omitted).

The control circuit 9 determines the rate of change of the current value according to a set determination program stored in a built-in control computer (not shown) and controls the switching element 7 to turn on and off. I do. The control circuit 9 is connected to a frequency trigger pulse generator 14 for adjusting the amount of ozone generated from the silent discharge electrode 3 via a connection line (omitted by reference numerals).

Here, the power supply device 1 for silent discharge is provided.
Is provided with an attenuator 15 for attenuating a pulse applied to the switching element 7. This attenuator 15 is configured by connecting a first resistance element 16 and a diode 17 in series. One end of the first resistance element 16 (symbol omitted)
Are the choke coil 10 and the switching element 7
Is connected to the connection point (the symbol is omitted). The minus side (reference number omitted) of the diode 17 is connected to a connection point (reference number omitted) between the primary side coil 6 and the plus side line.

Next, the operation of this circuit will be described. When the power supply 2 is turned on and an open signal is supplied to the gate 13 by the control circuit 9 to turn on the switching element 7, the capacitance of the silent discharge electrode 3 and the inductance of the choke coil 10 are reduced. A vibration of a transient response having a frequency determined by the above occurs. Then, a high voltage pulse of the secondary coil 4 generated by the vibration of the transient response starts a silent discharge between the two electrodes 11 and 12 to generate ozone. Further, control is performed to switch the open signal supplied from the control circuit 9 to the gate 13 to a close signal and to turn off the switching element 7.

The ozone generator (not shown) can eliminate noise by turning off the switching element 7 at a point where the current of the primary coil 6 crosses zero (a point where the current value becomes zero). Although possible, the current value of the primary coil 6 fluctuates greatly due to operating conditions, and when zero crossing does not occur, noise and loss of the switching element 7 are reduced. Is necessary.

For this reason, in the first embodiment, when the current value detected by the detection means 8 is at a minimum, the open signal supplied from the control circuit 9 to the gate 13 is output. The control is performed to switch to the close signal and to turn off the switching element 7. Specifically, the current value of the primary coil 6 is input to the control circuit 9 by the electromagnetic induction type detection means 8 as an output signal proportional to the rate of change of the current value of the primary coil 6.
The control circuit 9 switches the open signal supplied to the gate 13 to a closed signal. As a result, generation of noise and loss during control for turning off the switching element 7 (hereinafter, “switching loss”)
) Is reduced.

Next, a more specific description of the first embodiment will be given. FIG. 2 is a graph illustrating a relationship between a primary current flowing through the switching element 7 and a secondary voltage of the secondary coil 4. In FIG. 2, a primary current flowing through the switching element 7, that is, a primary current flowing through the primary coil 6, is shown in an upper graph. The vertical axis of the upper graph in FIG. 2 represents the primary current, and the horizontal axis represents the passage of time. The waveform of the primary current is obtained by inputting a signal output from the frequency trigger pulse generator 14 to the control circuit 9,
3 is formed. A pulse current having a pseudo sine wave waveform flows in the cycle of the frequency trigger pulse generator 14. The waveform of the primary current is boosted by the transformer 5 and becomes a response waveform of the secondary voltage shown in the lower graph of FIG. The vertical axis of the lower graph in FIG. 2 indicates the secondary voltage, and the horizontal axis indicates the passage of time.

FIG. 3 is a graph illustrating the relationship between the primary current and the rate of change of the primary current. put it here,
The waveform of the primary current shown in the upper graph of FIG. 2 is enlarged by one, and is shown in the upper graph of FIG. The vertical axis of the upper graph of FIG. 3 indicates the primary current, and the horizontal axis of FIG.
Similarly to the above, the time passage is shown, and the time interval is expanded for explanation. In the lower graph of FIG. 3, the rate of change of the primary current is shown on the vertical axis, and the horizontal axis shows the passage of time. For the sake of explanation, the time interval is enlarged as in the upper graph.
The timing at which the current value detected by the electromagnetic induction type detection means 8 becomes a minimum will be described with reference to FIG.

In the lower graph of FIG. 3, the control circuit 9 distinguishes between a region where the change rate of the primary current is "positive" and a region where the change rate of the primary current is "negative", in order to determine the change rate of the primary current. Recognize separately. Further, a reference time A is set as a maximum time limit for counting (measuring) the elapsed time in the elapsed time shown on the horizontal axis. Here, the interval of the reference time A is set such that its end point is between the time when one cycle has elapsed from the start of the waveform of the primary current shown in the upper graph and the time when the next one cycle starts. Is set to

Next, a case where an off signal is output from the control circuit 9 to the gate 13 based on the two regions and the reference time A recognized in FIG. 3 will be described with reference to FIG. FIG. 4 is a state transition diagram for explaining a control method of the control circuit 9. Here, there are three types of patterns for outputting the off signal.

First, in FIG. 4, when the signal output from the frequency trigger pulse generator 14 is input while the control circuit 9 is in a standby state, the control circuit 9 turns on the gate 13. A signal (open signal) is output, and a built-in time timer (not shown) is set to start counting until the reference time A is reached.

Next, a first intermediate state is established waiting for the rate of change of the primary current to become "negative". At this time, as the first pattern, the time-out timer expires,
That is, if the reference time A has expired and the control circuit 9 has expired, the control circuit 9 outputs to the gate 13 a signal to turn off (close signal) instead of the open signal.

When the rate of change of the primary current once becomes "negative", a transition is made to the next second intermediate state. The second intermediate state is a state where the change rate of the primary current becomes “positive”. At this time, as a second pattern, if the timed timer expires after expiration, the control circuit 9 sets the gate 13
A signal to turn off (close signal) is output instead of the open signal.

Further, in this state, when the rate of change of the primary current becomes "positive" earlier than the reference time A, that is, when the point indicated by the symbol B in FIG. The control circuit 9 outputs to the gate 13 a signal to turn off (close signal) instead of the open signal. In any of the patterns, the process returns to the standby state and waits until the next cycle. As described above, the switching signal is transmitted to the gate 13 in accordance with each of the patterns, thereby preventing generation of noise and the switching loss.

Next, a second embodiment of the present invention will be described in detail with reference to FIGS. The second embodiment is a modification of the first embodiment. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 5 is a schematic electric circuit diagram of the second embodiment of the present invention.

In FIG. 5, the power supply device 1 for silent discharge is shown.
Is a converter type detecting means 18 constituted by a current-voltage converter instead of the power source 2, the silent discharge electrode 3, the transformer 5, the switching element 7, and the electromagnetic induction type detecting means 8. And the converting device type detecting means 1
The control circuit 9 includes a differential operation circuit 19 for the current value detected by the control circuit 8 and the control circuit 9.

The converting device type detecting means 18 is constituted by a Hall element or a resistance element.

The differential operation circuit 19 calculates the rate of change of the increase and decrease of the current value with the passage of time, and outputs a signal having a waveform of the rate of change to the control circuit 9. put it here,
The differential operation circuit 19 is incorporated in the control circuit 9 and performs arithmetic processing by software of a microcomputer (not shown). That is, the primary current value before the predetermined time is stored, compared with the primary current value after the predetermined time has elapsed, and the rate of change is output to the control circuit 9.

Next, the operation of the power supply device 1 for silent discharge constructed as described above will be described. With the power supply 2 turned on, ozone is generated as in the first embodiment.

Then, the current value of the primary coil 6 is converted into a voltage value by the conversion device type detecting means 18 and the rate of change of the voltage value is inputted to the differential operation circuit 19, and the differential operation circuit 19 At the timing according to the output signal from the converter, that is, when the current value of the primary side coil 6 detected by the converter type detecting means 18 becomes a minimum,
The control circuit 9 switches the open signal supplied to the gate 13 to a closed signal. This allows
The generation of the noise and the switching loss are reduced.

Next, a more specific description of the second embodiment will be given. FIG. 6 is a graph illustrating the relationship between the primary current and the rate of change of the primary current. Here, the waveform of the primary current shown in FIG. 2 is enlarged by one, and is shown in the upper graph in FIG. The vertical axis of the upper graph in FIG. 6 represents the primary current, and the horizontal axis represents the passage of time, as in FIG. 2, and the time interval is enlarged for explanation. In the lower graph of FIG. 6, the rate of change of the primary current is shown on the vertical axis, and the horizontal axis shows the passage of time.

In the lower graph of FIG. 6, two reference levels are additionally provided for determining the rate of change of the primary current. First, the first reference level C is set as a predetermined threshold value that is lower than the rate at which the change rate is zero, that is, on the minus side. Next, the second reference level D is set as a threshold higher than the threshold of the first reference level C and on the negative side near zero. For the sake of explanation, in FIG. 6, the rate of change of the vertical axis near zero is enlarged and shown. That is, the second reference level D is set to almost zero. Further, in the time passage shown on the horizontal axis, the reference time A is set as the maximum time limit of the time passage as in the first embodiment. Here, the second reference level D is
The threshold value on the positive side near zero can also be used.

Next, when outputting an off signal from the control circuit 9 to the gate 13 based on the first reference level C, the second reference level D, and the reference time A set in FIG. A description will be given based on FIG. FIG. 7 is a state transition diagram for explaining a control method of the control circuit 9. Also in this case, there are three types of patterns for outputting the off signal.

First, in FIG. 7, when the control circuit 9 is in a standby state and a signal output from the frequency trigger pulse generator 14 is input, the control circuit 9 turns on the gate 13. A signal (open signal) is output, and the built-in timer is set to start counting until the reference time A is reached.

Next, a third intermediate state waits for the output of the differential operation circuit 19 to fall below the first reference level C. At this time, as a first pattern, if the time-out timer expires after the time-out timer expires, the control circuit 9 outputs to the gate 13 a signal to turn off (close signal) instead of the open signal. That is, in this case, the output of the differential operation circuit 19 never falls below the first reference level C.

When the output of the differential operation circuit 19 once falls below the first reference level C, a transition is made to the next fourth intermediate state. In the fourth intermediate state, it waits for the output of the differential operation circuit 19 to become equal to or higher than the second reference level D. At this time, as a second pattern, if the time-out timer expires after the time-out timer expires, the control circuit 9 outputs a signal (close signal) to the gate 13 to turn off instead of the open signal.

In the fourth intermediate state, when the output of the differential operation circuit 19 becomes higher than the second reference level D earlier than the time of the reference time A, the control circuit is used as a third pattern. Reference numeral 9 outputs a signal to turn off (close signal) to the gate 13 instead of the open signal. By transmitting a switching signal to the gate 13 in accordance with each of the patterns, generation of noise and switching loss are prevented.

Further, a third embodiment of the present invention will be described in detail with reference to FIGS. This third embodiment,
It is a further modified example of the second embodiment. In the description of the third embodiment, the same components as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG.
FIG. 7 is a schematic electric circuit diagram of a third embodiment of the present invention.

Referring to FIG. 8, the power supply device 1 for silent discharge
Are the power supply 2, the silent discharge electrode 3, the transformer 5, the switching element 7, and a resistance element 20 (hereinafter, referred to as a "second resistance element 2"
0)), an external differential operation circuit 21 for the current value detected by the second resistance element 20 externally attached to the control circuit 9, and the control circuit 9.

When detecting the current value of the primary coil 6, the second resistance element 20 generates a voltage on both sides when the current flows.

The external differential operation circuit 21 calculates the rate of change of the increase / decrease of the current value with the passage of time, and outputs a signal having a waveform of the rate of change to the control circuit 9. That is,
When calculating the change rate of the current value, the external differential operation circuit 21 is provided as an independent circuit, and the primary coil 6
Is input to the external differential operation circuit 21. The external differential operation circuit 21 converts the current value of the primary coil 6 into a signal having a differentiated waveform, and outputs the signal to the control circuit 9. The external differential operation circuit 21 includes a noise filter 22 that reduces noise to the external differential operation circuit 21.

The noise filter 22 is configured as a smoothing circuit of the third resistance element 23 and the first capacitor 24. A connection point (symbol omitted) between the second resistance element 20 and the negative terminal (symbol omitted) of the switching element 7 is connected to the third resistance element 23. A connection point (symbol omitted) of the third resistance element 23 and the first capacitor 24 is a second input terminal (symbol omitted) of the control circuit 9 and an input side of the external differential operation circuit 21. It is connected to a capacitor 25. The negative terminal (symbol omitted) of the first capacitor 24 is connected to the negative line.

The detailed configuration of the external differential operation circuit 21 is as follows. The second capacitor 25 and the fourth resistance element 26
And an amplifier 27 generally called an operational amplifier. A connection point (symbol omitted) of the second capacitor 25 and the fourth resistance element 26 is connected to an input terminal (symbol omitted) of the amplifier 27. A connection point (symbol omitted) between the fourth resistance element 26 and an output terminal (symbol omitted) of the amplifier 27 is connected to a second input terminal (symbol omitted) of the control circuit 9. The amplifier 2
A ground terminal 7 (symbol omitted) is connected to the negative line.

The control circuit 9 in the third embodiment
Determines the current value by a preset determination program stored in the control computer,
On / off control of the switching element 7 is performed. The control circuit 9 includes the frequency trigger pulse generator 14
And a connection line (not shown).

Next, the operation of this circuit will be described. With the power supply 2 turned on, ozone is generated as in the second embodiment. Then, the open signal supplied from the control circuit 9 to the gate 13 is switched to a close signal,
Control for turning off the switching element 7 is performed.

Next, a more specific description of the third embodiment will be given. FIG. 9 is a graph illustrating the relationship between the primary current and the output of the external differential operation circuit 21. Here, the waveform of the primary current shown in FIG. 2 is enlarged by one, and is shown in the upper graph in FIG. The vertical axis of the upper graph in FIG. 9 represents the primary current, and the horizontal axis represents the passage of time, as in FIG. 2, and the time interval is enlarged for explanation. In the lower graph of FIG. 9, the output waveform of the external differential operation circuit 21 (hereinafter, referred to as “differential circuit output”)
Is shown on the vertical axis. The abscissa indicates the passage of time as in FIG. 2, and the time interval is enlarged for explanation. Here, the output of the differentiating circuit is obtained by converting the primary-side current into a voltage by the external differentiating operation circuit 21 and is shown as a scale of the voltage waveform. The waveform indicating the output of the differentiating circuit is a so-called smoothed waveform by the noise filter 22.

In the lower graph of FIG. 9, two reference levels are additionally provided for determining the voltage value of the output of the differentiating circuit. First, the third reference level E is set lower than the zero voltage, that is, as a predetermined voltage on the negative side. Next, the fourth reference level F is set as a voltage higher than the voltage of the third reference level E and on the negative side near zero voltage. For the sake of explanation, in FIG. 9, the output of the differentiating circuit on the vertical axis near zero is enlarged and shown. That is, the fourth reference level F is set to be nearly zero. Further, in the time passage shown on the horizontal axis, the reference time A is set as the maximum time limit of the time passage, as in the second embodiment. Here, the fourth reference level F may be a threshold value on the plus side near substantially zero.

Next, based on the third reference level E, the fourth reference level F, and the reference time A set in FIG. 9, when the control circuit 9 outputs an off signal to the gate 13, A description will be given based on FIG.
FIG. 10 is a state transition diagram for explaining a control method of the control circuit 9. Also in this case, there are three types of patterns for outputting the off signal.

First, in FIG. 10, when the signal output from the frequency trigger pulse generator 14 is input while the control circuit 9 is in a standby state, the control circuit 9 turns on the gate 13. A signal (open signal) is output, and a built-in time timer (not shown) is set to start counting until the reference time A is reached.

Next, a fifth intermediate state is established, waiting for the output of the differentiating circuit to fall below the third reference level E. At this time, as the first pattern, if the time-out timer expires after expiration, the control circuit 9
Outputs an off signal (close signal) to the gate 13 instead of the open signal. That is, in this case, the output of the differentiating circuit never falls below the third reference level E.

When the output of the differentiating circuit once falls below the third reference level E, the state transits to the next sixth intermediate state. In the sixth intermediate state, it waits until the output of the differentiating circuit becomes equal to or higher than the fourth reference level F. At this time,
As a second pattern, if the time-out timer expires after the time-out timer expires, the control circuit 9 sets the gate 1
A signal to turn off (close signal) is output to 3 in place of the open signal.

Further, in the sixth intermediate state, when the output of the differentiating circuit reaches or exceeds the fourth reference level F earlier than the time of the reference time A, as a third pattern, the control circuit 9 A signal to turn off (close signal) is output to the gate 13 instead of the open signal. As described above, the switching signal is transmitted to the gate 13 in accordance with each of the patterns, thereby preventing noise and the switching loss.

[0061]

As described above, according to the present invention, it is possible to provide a silent discharge power supply device capable of reducing noise generation and switching loss of a switching element.

[Brief description of the drawings]

FIG. 1 is a schematic electric circuit diagram of a first embodiment of the present invention.

FIG. 2 is a graph illustrating a relationship between a primary current flowing through a switching element and a secondary voltage of a secondary coil of a transformer in the first embodiment.

FIG. 3 is a graph illustrating a relationship between a primary current and a rate of change of the primary current in the first embodiment.

FIG. 4 is a state transition diagram for explaining a control method of the control circuit in the first embodiment.

FIG. 5 is a schematic electric circuit diagram of a second embodiment of the present invention.

FIG. 6 is a graph illustrating the relationship between the primary current flowing through the switching element and the rate of change of the primary current in the second embodiment.

FIG. 7 is a state transition diagram for explaining a control method of the control circuit in the second embodiment.

FIG. 8 is a schematic electric circuit diagram of a third embodiment of the present invention.

FIG. 9 is a graph illustrating the relationship between the primary current and the output of the differentiating circuit in the third embodiment.

FIG. 10 is a state transition diagram illustrating a control method of the control circuit in the third embodiment.

[Explanation of symbols]

2 power supply 3 silent discharge electrode 4 secondary side coil 5 transformer 6 primary side coil 7 switching element 8 electromagnetic induction type detection means (detection means) 9 control circuit 10 choke coil 18 conversion device type detection means (detection means) 20 second resistor Element (detection means) A Reference time B Point indicating when the rate of change of the primary current becomes "positive" earlier than the reference time C First reference level D Second reference level E Third reference level F Fourth reference level

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G042 CA01 CB23 CD03 5H730 AA02 AA14 AS04 BB23 BB57 DD04 DD41 FD41 FF09 FG01 5H790 BA00 BB15 CC01 DD06 EA01 EA02 EA07 EA16 EA26 EB06

Claims (1)

[Claims] 1. A power supply 2 for supplying a direct current, a silent discharge electrode 3, and the power supply 2 is connected to a primary coil 6; the silent discharge electrode 3 is connected to a secondary coil 4; 10, a switching element 7 for controlling the supply of power to the primary coil 6, and detection means for detecting the current value of the primary coil 6, the current value detected by the detection means A power supply device for silent discharge, comprising a control circuit 9 for detecting a rate of change of the switching element 7 and controlling the switching element 7 to be turned off.