JPS63171169A - High-frequency high-voltage power source - Google Patents

Abstract

PURPOSE:To prevent accidents when output terminals of this apparatus are opened, by connecting between said output terminals a fixed protecting capacitor in parallel with a load. CONSTITUTION:Both terminals M, N of a power capacitor 6 with electrostatic capacity C0 sufficiently larger than that of a capacitive load 5 composed of small resistance part RK and comparatively large nonlinear capacity part CK connected with output terminals 3 to 4 of secondary winding 2 of a high-frequency boosting transformer 1 are connected with a charging DC power 9 composed of low-frequency AC power 7 and full-wave rectifier 8. Said terminal M is connected with the middle point O of a transformer primary winding 10 and provided with vibrating inductances L1 to L2 and silicon controlled rectifiers S1 to S2, and said rectifiers S1 to S2 are alternately turned ON by a control power 13. Then, a protective capacitor 18 is connected between the output terminals 3 and 4, and its capacity CP is set to about one-fourth to one-fifth of the load electrostatic capacity CK or more. Thus, said mechanism performs protection from any accidents by overcurrent and by opening and short-circuiting of the output terminals together with a fuse F1 for protection from overcurrent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention provides efficient, stable and highly reliable high frequency application to non-linear capacitive loads such as creeping discharge ozonizers whose capacitance changes with voltage. This invention relates to a power source for applying high voltage.

[Prior Art] Conventionally, a combination of a high frequency oscillator and a high frequency step-up transformer has been used as this type of power source. At that time, the capacitance of the load changes due to discharge, etc. within one cycle of the AC voltage, so the reactive power cannot be compensated for by using a series or parallel inductance. Both transformers are large and expensive, with increased losses and extremely low power efficiency. However, there is an unstable phenomenon peculiar to nonlinear circuits in which the current suddenly jumps to an excessive value when the voltage exceeds a certain value, making stable driving difficult.

On the other hand, the inventor of the present invention has developed a separate invention, "High Frequency High Voltage Power Supply" (Patent Application No. 81-3040, hereinafter referred to as "separate invention"), in which the center point A' is located on the low voltage side, the next winding and both ends. Connect one end of a power supply capacitor equipped with a DC power supply for charging to the midpoint of the primary winding of a high-frequency step-up transformer that has a high-voltage side secondary winding with the output terminal, and connect both ends of the primary winding. connected in series to a suitable externally controlled switching element such as a silicon-controlled rectifying element (thyristor) that makes the discharging direction of the capacitor charge voltage the conduction direction, respectively, and the other end of the capacitor, and the external A diode element is connected in antiparallel to each of the control type switch elements, and a control signal for conduction trigger is alternately supplied from the control power source to the control terminal of the external control type switch element, so that the external control type switch element is alternately connected. We proposed to create a power supply that can stably apply high frequency and high voltage with the highest power efficiency even if the capacitance of the load is non-linear and changes depending on the voltage. .

However, the term "externally controlled switching element" here generally refers to an element that maintains an off state when no control signal is supplied to its control terminal, and conducts current from the anode terminal to the cathode terminal when the control signal is supplied. .

[Problem to be Solved by the Invention] The present invention attempts to solve the problems in use of the above-mentioned "separate invention." In order to clarify this problem, first of all, the problems of the "r. different invention" are explained in advance. The contents and operation will be explained with reference to FIGS. 1 and 2.

In FIG. 1, the primary-side equivalent capacity of a capacitive load 5 consisting of a small resistance Rk and a relatively large nonlinear capacitance Ck connected to the output terminal 3.4 of the secondary winding 2 of the high-frequency step-up transformer 1. ] (Both terminals M and N of the power supply capacitor 6, which has a capacitance Go that is sufficiently larger than aCk, are connected to a charging DC power supply 9 consisting of a low frequency AC power supply 7 and a double-wave rectifier 8. , the capacitor 6 is charged to a voltage Vo with positive polarity on the M side and negative polarity on the N side (N is grounded).The terminal M is connected to the midpoint O of the primary winding 10 of the step-up transformer 1. Both terminals A and B of 10 are connected to vibration inductances Ll and L2, respectively, and an externally controlled switching element Sl, which is made of a silicon-controlled rectifier connected in series with this in the forward direction (in the discharge direction of the capacitor 8). It is connected to the terminal N via S2 and grounded.Diode elements DI and D2 are connected antiparallel to St and S2, respectively.11.12 is a small inductance connected in series to DI and D2,
Upon reversal of the current through ni,[12, a small voltage drop in the opposite direction is created across Sl,32 to ensure recovery of its off state. 13 is a control power supply, which is connected to control terminals 18.17 of S1 and S2 via conductor 14.15.
A control current is alternately supplied to St and S2 to make them conductive alternately. First, the externally controlled switching element S1 to which the control signal is supplied to its control terminal immediately becomes conductive, so that the - part of the charging voltage Vo of the power supply capacitor is 1
One end M of the capacitor → midpoint O of the primary winding of the step-up transformer
→ The relevant primary winding terminal A → The relevant vibration inductance L1
→The switch element S1 in a conductive state →Discharges through the circuit at the other end Nj of the capacitor.

At this time, an electromotive force is induced in the secondary winding of the step-up transformer, and this electromotive force is applied to both ends of the nonlinear capacitive load connected thereto. In this case, the voltage and current on the primary and secondary sides are the capacitance Co of the power supply capacitor and the inductance 10 of the vibration inductance L1. Leakage impedance Zl on the primary and secondary sides of a step-up transformer
, Z2, it becomes a transient oscillation in the fast-forming series circuit via the step-up transformer of the electrostatic capacitance Ck of the capacitive load and its resistance Rk, and in the case of Go) a Ck, Ck is thereby once charged to near 2aVo. (However, a=turn ratio of secondary winding to primary winding 0-A). Next, Ck is discharged through the secondary winding, and along with this, an electromotive force is generated in the opposite direction (in the direction of charging the power supply capacitor) that is larger than Vo between the midpoint O of the primary winding and the terminal A, and this Accordingly, a reverse voltage is applied to the externally controlled switching element S1, and the non-conducting state is restored.

However, since the diode element connected in antiparallel with this becomes conductive, the transient vibration continues and the other end N of the capacitor → the diode element D1 → the vibration inductance L1 → the primary of the step-up transformer. A reverse current flows in the direction of winding terminal A → midpoint O of the primary winding → one end M of the capacitor, charging the capacitor CO and increasing the load Ck.
The reactive power supplied to Go is recovered to Go. The temporal changes in the voltages v2 and 12 across the capacitive load during this process are shown by solid lines and dotted lines during time t1→t3 in FIG. However, tl and t2 are the times when the externally controlled switching element is turned on and off, and t3 is the end of discharge due to transient vibration of Ck, and after t3, Ck turns into a slow discharge. The change in primary current i1A during this period is as shown by the solid line, and the period from t1 to t2 is 1'M+o+A +
Ll→S1→N" circuit, period t2→t3 is FN+D
Flows through the circuit 1-Ll→A→0→Mj. Next, time t4
, a control signal is supplied to the current externally controlled switching element S2, and when it becomes conductive, a transient vibration exactly similar to that described above occurs in the circuit including S2, i.e.
'M→0→terminal B on the S2 side of the primary winding→vibration inductance L2→S2→N on the S2 side'' and diode D2→L2→B+O+Mj connected in antiparallel to FN+32
voltage V2 of the secondary winding of the step-up transformer and the capacitive load connected to it.
++2 goes in the opposite direction, and follows the course shown by the solid line and dotted line in the period t4→t6 in FIG.

The change in the primary current I during this period is as shown by the solid line. Next, at time t7, Sl is triggered again and becomes conductive, and by repeating this process, the high-frequency, high-voltage ma2 force, whose cycle is To from t1 to t7, is transferred from the capacitive terminals 3 and 4. It is applied to the load 5.

In this case, it is generally preferable to select Go)) a Ck because v2 can be maximized. When the resistance of the -order and secondary windings and the load resistance Rk are negligibly small, one period of the transient oscillation from t1 to t3 is approximately given by the following equation.

k at T = 2fT” (1) L = Sentence 0 + Sentence 1 + Sentence 2° (2) However, 1-primary winding OA,
Or OB leakage inductance, sentence 2' - Secondary winding leakage inductance 2's primary side converted value at first glance 2/a''
, Ck' - primary side conversion value of 〇 = aCk.

Therefore, in the present invention, the time interval θ=t4−tl of the control signals supplied to Sl and S2 generally needs to be set to θ≧T with respect to the transient vibration period T given by equation (1). , Therefore, the effective period To=t7-tl of the AC output high voltage consisting of each positive and negative half-wave becomes To>27.

As a result, in invention 1 according to r, Sl,
Two circuits including S2 1rM-0-A-Nj and lrM
-0-B-Nj are alternately ilA of FIG. 2,
A current indicated by i(B flows through the capacitive load 5 at both ends 3-
A high frequency high voltage given by M2 in the figure is applied between M4 and M4.

However, if the connection between the load 5 and the output terminal 3.4 is broken due to an accident such as a disconnection, and both ends of the output terminal 3.4 become open, the transient vibration shown in FIG. 2 will no longer occur. S
If one or both of S1 and S2 continues to be conductive, a short-circuit current will immediately flow from the power supply, burning out these elements and the rectifier 8, and seriously damaging the power supply. Since this burnout accident occurs instantaneously, it cannot be prevented by ordinary fuses, etc., and this has been a major practical problem when using the r-separate power supply J. An object of the present invention is to completely prevent the above-mentioned accident when the output end is opened in another invention.

[Means for solving the problem] The present invention solves the above problem by connecting a fixed protective capacitor in parallel with the load 5 between the output terminals 3.4.

[Function] Since a protective capacitor is connected between output terminals 3 and 4, even if load 5 is disconnected from 3.4, the transient vibration shown in Figure 2 will always occur. Therefore, the above-mentioned accident is prevented from occurring. In this case, during normal operation, formula (1)
The primary side converted value Ck'' of the load capacitance used for When it expires, the next value must be used for Ck''.

C'=a Cp (4) [Example] An example of the present invention is shown in FIG. 17 from l in the figure
The elements numbered up to and including Ck, Rk.

A, B, M, N, O, L1, L2. S1
, S2. The names and functions of the elements designated by the symbols DI and D2 are the same as those of the elements designated by the same numbers and symbols in FIG. Further, the basic operation regarding high frequency and high voltage generation of the present invention is no different from the basic operation of the "another invention" shown in FIGS. 1 and 2, so a description thereof will be omitted.

In FIG. 3, 18 is a protective capacitor which is a feature of the present invention and is connected between the output terminals 3 and 4, and its capacitance cp is at least a fraction of the load capacitance Ck. Fl is a fuse for overcurrent protection inserted between terminals M and O, F2 and F3 are low-voltage AC current li; output terminal 19.20 of i7 and input terminal 21 of double wave rectifier 8,
This is a fuse that can be inserted between the
A double-wave rectifier 8. Externally controlled switch elements St, S2,
Protects step-up transformer 2. The special switch F1 is extremely effective in protecting against short circuits, and its insertion position is not simply between M and O, but may also be inserted between the other end N of CO and the ground terminal N'. Also, separately from F1 or Fl
Instead, fuses may be inserted between N' and St and between N' and S2, respectively. Furthermore, generally M-〇-
A-8t-N'-N and t-0-B-S2-N'
It is absolutely necessary to insert a fuse in at least one of the -N circuits, preferably both, to prevent short-circuit damage.

[Effects of the Invention] Since the present invention has the above-mentioned effect, the connection between the output terminals 3 and 4 of the protective capacitor 18 allows the main power to be maintained even if the terminals 3 and 4 are in an open state as described above. It can completely prevent the power supply from being damaged. Further, by using the fuse Fl, even if the terminals 3 and 4 are short-circuited, the power supply can be completely prevented from being damaged.

In addition, in the power supply of the present invention, the externally controlled switching element S1,
As S2, a power transistor (FET), Runsistor, TRIAC, GT is used instead of the silicon-controlled rectifier.
Any suitable switch may be used, such as an O switch.

Furthermore, a combination of three-phase or multi-phase diode bridges can also be used as the charging DC power source 9.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the principle of another invention, Fig. 2 is a diagram showing the output voltage of the power supply of the other invention and the present invention, and waveforms of the step-up transformer - primary and secondary current, and Fig. 83 is a diagram showing the waveforms of the primary and secondary current of the step-up transformer. FIG. 2 is a circuit diagram showing an example. v2・・・・・・・・・Output voltage 12・・・・・・
......Output current i1A, i1B...Step-up transformer - next current l......High frequency step-up transformer 2... ...Secondary winding 5...Capacitive load 6...
・・・・・・Power capacitor 8・・・・・・・・・
...Charging DC power supply lO...Primary winding St, S2...Silicon controlled rectifier element 01, D2...Diode element Ll,
L2... Vibration inductance 13...
......Control power supply 18...
Protective capacitors Fl, F2, F3...Fuses and above 1 Step-up transformer 2 Secondary winding 3.4 Output terminal 5 J-type load 6 Power supply capacitor 7 Low-voltage AC power supply 8 Double-wave rectifier 9 DC power supply for charging , 10-Primary winding 11.12 Small inductance 13 Control power supply 14.15 Conductor 46.17 Control terminal 18 A capacitor for 49.20, 21.22 Terminal 8, B, H, N, N' Explosion A Ck Load capacity Rk Load resistance 1 point, primary current flowing through 11B terminals A and B 12 Secondary current (output current) ■2 Two wings (output voltage) 0 Center tap 1.1.12 Vibration inductance 5LS2 silicon 4-switch rectifier element 01, 2 diode element FL F2. F3 Hughes Konsai 3 figure

Claims (1)

[Claims] 1. A low voltage side primary winding 10 with a middle point and an output terminal 3 at both ends,
One end M of a power supply capacitor 6 equipped with a DC power source 9 for charging is connected to the middle point O of the primary winding of a high-frequency step-up transformer 1 having a high-voltage side secondary winding 2 of 4, and the primary winding Both ends A and B of are connected in series to vibration inductances L1 and L2, respectively, and externally controlled switching elements S1 and S2 whose conduction direction is the discharging direction of the capacitor charging voltage,
Diode elements D1 and D2 are connected to the other end N of the capacitor 6 and in antiparallel to each of the externally controlled switching elements S1 and S2, and a control signal for conduction trigger is applied from the control power supply 13 to the switching element S1. A protective capacitor was connected between the output terminals 3 and 4 in a high-frequency high-voltage power supply that alternately supplies power to the control terminals 16 and 17 of the externally controlled switching elements S1 and S2 to turn on and off the externally controlled switching elements S1 and S2. A high frequency, high voltage power supply characterized by: 2. In the device according to claim 1, from one end M of the power supply capacitor 6 to the middle point O of the primary winding, the terminal A,
A circuit that goes through the ground terminal N' to the other end N of the capacitor 6, and another circuit that goes from M to O, and through the terminals B and N' to N. A high-frequency high-voltage power supply characterized in that at least one fuse is inserted into the high-frequency high-voltage power supply. 3. In the device according to claim 2, the terminal pair M
, O and between at least one pair of medium and small terminals between N' and N. 4. In the device according to claim 3, the terminal pair M
, O, and the fuse is inserted between O and O. 5. In the device according to claim 3, the terminal pair N
A high frequency high voltage power supply characterized in that the fuse is inserted between ' and N. 6. In the device according to claim 2, from A to N.
A high-frequency, high-voltage power source characterized in that the fuse is inserted in series in both the circuit section leading to the circuit section B and the circuit section extending from B to N. 7. In the device according to claim 6, S1 and N
A high-frequency, high-voltage power supply characterized in that the fuses are inserted between S2 and N. 8. A high-frequency high-voltage power source in the device according to any one of claims 1 to 7, characterized in that the externally controlled switching element is a silicon-controlled rectifying element. 9. A high-frequency, high-voltage power supply according to any one of claims 1 to 7, wherein the externally controlled switching element is an FET transistor. 10. In the device according to any one of claims 1 to 9, small inductances 11 and 12 are connected in series to the diode elements D1 and D2, respectively, and these are connected to the externally controlled switching element S1, A high frequency high voltage power supply characterized by being connected in antiparallel to S2.