JPS6389068A - High-frequency power source device - Google Patents

Abstract

PURPOSE:To improve a surge absorbing effect by mounting a plurality of capacitors combined with diodes on the output side of an LC filter. CONSTITUTION:A high frequency power source device obtains DC voltage by a rectifier 2 and an LC filter 3, the DC voltage is continued through a primary winding 7P for a transformer 7, a transistor 8 and a diode 9. and load such as an electric discharge lamp is supplied with voltage acquired from a secondary winding 7S for the transformer 7. A surge absorbing circuit 20 is set up on the output side of the LC filter 3 at that time. The surge absorbing circuit 20 is constitutes of two capacitors 21, 23 and diodes 22, 31-32 disposed between positive and negative double-sided buses P and N. Accordingly, separate capacitor 21, 23 is not charged only up to voltage divided in response to the surge absorption, thus improving a surge absorbing effect without lowering a power factor.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention converts direct current supplied from a rectifier through an LC filter into high-frequency alternating current through a single-stone blocking oscillation type inverter. The present invention also relates to a high frequency power supply device including a partial smoothing circuit for compensating for voltage in a phase section in which the output voltage of the LC filter decreases.

(Prior Art) Conventionally, as this type of high frequency power supply device, one having the configuration shown in FIG. 3 is known. A DC voltage is obtained from a commercial frequency AC power source through an LC filter 3 consisting of a rectifier 2, a reactor 4, and a capacitor 5. A varistor 6 is connected to the DC output side of the rectifier 2 as a surge absorbing element. The output DC voltage of the LC filter 3 allows a positive current to flow through the primary winding 7P of the transformer 7 via the transistor 8 and the diode 9. - A resonant capacitor 10 is connected in parallel to the next winding 7P. A secondary winding 7S of the transformer 7 is connected to a load such as a discharge lamp. The transformer 7 further has a control winding 7C, one end of which is connected to the base of the transistor 8 via a capacitor 11 and a reactor 12, and the other end connected to the DC negative electrode side of the rectifier 2. A starting base current flows to the base of the transistor 8 from the positive DC output side of the LC filter 3 via the starting resistor 13 and the above-mentioned accelerator 12 .

Further, on the output side of the LC filter 3, a relatively large capacitance partial smoothing capacitor 14 with a high resistance 15 connected in parallel is connected with a reactor 16 and a diode 17 in series. The diode 17 has a direction opposite to the DC output of the LC filter 3. Reactor 16 and diode 1
The common connection point of 7 is connected to the common connection point of the transformer-secondary winding 7P and the transistor 8 via a diode 18.

When AC power is turned on in the device shown in FIG. 3, a base current flows through the resistor 13 and reactor 12, turning on the transistor 8 and exciting the transformer 7. This induces a voltage in the control winding 7C, causing a feedback base current to flow through the transistor through the capacitor 1 and the reactor 12.

At this time, resonance occurs between the inductance of the transformer 7 and the capacitor 10 as seen from the negative winding 7P. The resonant frequency is about 20 to 50 KHz.

The part 1 self-sliding capacitor 14 is the primary winding 7 of the transformer 7.
When the voltage across P is positive, it is charged, and when the voltage of the -order winding 7P remains positive and is about to drop, a discharge current flows to compensate for the voltage drop.

(Problems to be Solved by the Invention) The device shown in FIG. 3 is provided with a varistor 6 as a surge absorbing means, but it is not sufficient to provide surge protection by itself, and may damage circuit components. There is a risk of malfunction. It is possible to increase the surge absorption effect by increasing the capacitance of the capacitor 5. However, this solution is not preferable because it causes a decrease in the power factor.

Therefore, an object of the present invention is to provide a high frequency power supply device equipped with circuit means that can improve surge resistance without causing a decrease in power factor.

[Structure of the invention]

(Means for Solving the Problems) The high frequency power supply device of the present invention includes a plurality of capacitors provided on the output side of the LC filter, and these capacitors have positive and negative polarities with respect to the forward direction of the output of the LC filter. It is characterized by the provision of a surge absorption circuit consisting of a plurality of diodes arranged so as to form a series circuit between the two poles, and to form a parallel circuit between the positive and negative poles in the opposite direction of the output of the LC filter. That is.

(Function) According to the above configuration, each capacitor is charged only up to a voltage divided according to the number of capacitors, and discharging occurs only when the filter output drops below its charging voltage. Therefore, it exhibits a partial smoothing effect, and the surge absorption effect can be improved without causing a decrease in the power factor.

(Example) FIG. 1 shows an embodiment of the present invention.

Here, the same reference numerals as those in FIG. 3 indicate the same circuit components. 20 The device is obtained by removing the varistor 6 from the device shown in FIG.
Instead, a surge absorption circuit 2 is installed on the output side of the LC filter 3.
The feature is that 0 is set.

For convenience, both the positive and negative electric circuit portions extending from the re-output end of the LC filter 3 will be referred to as a positive bus P and a negative bus N in the following description. The surge absorption circuit 20 includes a plurality (n) of surge absorption circuits arranged between the positive and negative bus bars P and N, two capacitors 21 and 23 in this embodiment, and (n-1) inserted between these capacitors. 31, 32 are connected alternately between each of the common connection points of the capacitor and the diode and the bus line P or N. In this case, when the capacitor is located on the positive side bus P side (capacitor 21), the diodes 31 and 32 are connected between the negative side bus N (diode 31) and the positive side N line P.
When a diode is located on the side (diode 22), it is placed between it and the positive side bus P (diode 32) so that the polarity is opposite to the DC output of the LC filter 3.

According to the configuration shown in FIG. 1, in the charging mode for the surge absorption circuit 20, the capacitors 21 and 23
In the discharge mode, capacitors 21 and 23 are inserted in parallel between both bus lines P and N via diodes 31 and 32, respectively. If the capacitance of each capacitor 21, 23 is equal to C, the combined capacitance in the discharge mode is C/2, and the charging voltage of each capacitor is 1/2 of the voltage between both bus lines.

In the discharge mode, each capacitor 2], 23 is connected to the bus P,
It functions effectively as a smoothing capacitor from the point at which the voltage across N is lower than the charging voltage of each capacitor.

That is, the capacitors 21 and 23 exhibit the same partial smoothing effect as the partial smoothing capacitor 14. When a surge occurs, the capacitor 21 is
．． 23 functions as a surge absorbing element.

In this way, the surge absorption circuit 20 can improve the surge absorption effect without causing a decrease in power factor.

FIG. 2 shows a surge absorption circuit 30 having three capacitors 21, 23, 25. Capacitor 21.
Diodes 22 and 24 are inserted between the capacitors 23 and 23 with forward polarity, respectively, and a diode 31 is inserted between the common connection point of the capacitor 21 and the diode 22 and the bus line N, and a diode 31 is inserted between the common connection point of the capacitor 21 and the diode 22 and the bus line N, and A diode 32 is connected between the common connection point and the bus P.
A diode 33 is connected between the common connection point of the capacitor 23 and the diode 24 and the bus bar N, and a diode 24
A diode 34 is connected between the common connection point of the capacitor 25 and the bus line P so that the diode 34 has a polarity opposite to the output polarity of the LC filter 3.

In the surge absorption circuit 30 of FIG. 2, each capacitor 2
If the capacitances of 1, 23, and 25 are equally C, the combined capacitance in charging mode is C/3, and the charging voltage of each capacitor is 1/3 of the voltage between both bus lines.
becomes. In discharge mode, each capacitor 21, 23.2
5 is the bus line P.

From the point at which the voltage across N becomes lower than the charging voltage of each capacitor, it effectively functions as a smoothing capacitor.

- If n capacitors with the same capacitance are used, the charging voltage of each capacitor will be 1/n of the peak value of the bus-to-bus type pressure, and a partial smoothing effect will be performed below 1/n of the bus-to-bus type pressure. can be set.

In this way, the surge absorption effect can be improved without causing a decrease in the power factor.

In addition, in the above explanation, the partial smoothing circuit was assumed to be a high frequency charging type, but the low frequency (ripple frequency of the rectifier)
It may be a rechargeable type. Further, a surge absorbing element such as a Zener diode or a varistor may be used together with the surge absorbing circuit of the present invention to further improve surge resistance.

〔Effect of the invention〕

According to the present invention, by providing several capacitors in combination with diodes on the output side of the LC filter, the surge absorption effect can be improved without causing a drop in the power factor.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram showing an embodiment of the present invention, Fig. 2 is a wiring diagram showing a modification of the surge absorption circuit, and Fig. 3 is a wiring diagram of a high frequency power supply device equipped with a conventional surge absorption means. . 2... Rectifier, 3... LC filter, 4... Reactor, 5... Capacitor, 7... Transformer, 7P.
...-Secondary winding, 7S...Secondary winding, 7C...Control winding, 8...Transistor, 10...Resonance capacitor, 12...Reactor, 13...Starting resistor , 14
...Partial smoothing capacitor, 20.30...Surge absorption circuit, 21°23.25...Capacitor, 22,
24,31°32.33.34...Diode. Applicant's agent Sato - Male procedural amendment October 31E1, 1985

Claims (1)

[Claims] Direct current supplied from a rectifier via an LC filter is converted into high-frequency alternating current via a single-stone blocking oscillation type inverter, and the voltage in the phase section where the output voltage of the LC filter decreases is compensated for. In a high frequency power supply device equipped with a partial smoothing circuit for the purpose of A surge absorption circuit is provided with a plurality of diodes arranged so as to form a series circuit between the LC filter and to form a parallel circuit between the positive and negative poles in the opposite direction of the output of the LC filter. High frequency power supply equipment.