JP2002142461A - High voltage generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve the problem of a conventional high voltage generator which has a limit in the secondary output voltage since the voltage across the primary coil of a transformer for generating high voltage cannot have voltage above power source voltage generated. SOLUTION: This high voltage generator comprises a DC power source, a transformer for generating high voltage having a primary coil to which one end of the DC power source is connected, a switching element, an electrolytic capacitor connected to both ends of the above DC power source, and a rectifying element whose anode is connected to the other end of the above primary coil. The anode of the rectifying element is connected to the switching element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high voltage power supply used for igniting an oil hot water heater, an oil stove, an oil bath, and the like, and for an air purifier such as an air conditioner.

[0002]

2. Description of the Related Art In FIG. 2 showing a circuit diagram of a conventional high voltage generator, a + power source of a power source 1 composed of a DC power source is
The high-voltage generating transformer 11 is connected to one end on the primary side, and the high-voltage generating transformer 11 is connected at both ends on the primary side to a capacitor 10 serving as an LC resonance circuit.

The other end of the high-voltage generating transformer 11 is connected to the drain of a second switching element 9 composed of a field effect transistor (hereinafter referred to as FET) and the like.
The source of the second switching element 9 is connected to the ground which is the negative power supply of the power supply 1. The high-voltage generating transformer
One end of the secondary side 11 is connected to the high-voltage terminal 12 and the other end is connected to the high-voltage terminal 13, and a portion between the high-voltage terminals 12 and 13 is a power supply terminal for generating a high voltage of the present circuit.

Further, a control circuit 15 composed of a microcomputer or the like is used.
Power supply for control circuit composed of DC power supply 2
Are connected to the + power supply terminal and the − power supply terminal of the control circuit 15, respectively.
-Power supply is connected to ground.

[0005] Voltage dividing resistors 3 and 4 are connected in series to the output of the control circuit 15, and one end is connected to the ground. The connection between the voltage dividing resistors 3 and 4 is connected to the base of the first switching element 5 composed of a transistor or the like. The emitter of the first switching element 5 is connected to ground, the collector is connected to a pull-up resistor 6 and a current limiting resistor 7, and the other end of the resistor 6 is connected to the + terminal of the power supply 1, The other end of 7 is connected to the gate of the second switching element 9. The cathode of the Zener diode 8 for overvoltage protection is connected to the gate of the second switching element 9, and the anode of the Zener diode 8 is connected to the ground. An electrolytic capacitor 14 is connected to both ends of the power supply 1.

Next, the operation of the circuit will be described. The control circuit 15 outputs a square wave as an ON / OFF digital signal. Upon receiving this digital signal, the first switching element 5 turns on and off, and performs an amplification operation. That is, an amplified signal is output to the collector in response to the signal from the base of the first switching element 5 and sent to the gate of the second switching element 9. Upon receiving the signal, a switching signal is output to the drain of the second switching element 9, an AC voltage waveform is generated in the primary winding of the high-voltage generating transformer 11, and the primary / secondary winding ratio is used. The boosted voltage is generated in the secondary winding, and a high voltage is generated between the high voltage terminals 12-13.

As a specific voltage, the power supply 1 uses a DC voltage of 12 V, and the output of the control circuit 15 outputs a 5 V and 0 V ON / OFF square wave digital signal. The second switching element 9 has a voltage of 10 to 12 V applied to the gate.
The switching operation is performed by the input of the digital signal. When the second switching element 9 performs a switching operation, the high-voltage generating transformer 11
A voltage waveform having a peak voltage of 12 V is applied to the primary side, and the high voltage generating transformer 11 boosts the voltage to generate an alternating high voltage of 5 KV with a peak voltage on the secondary side.

[0008]

In the above circuit configuration, the voltage supplied to the high-voltage generating transformer 11 is the second voltage.
Is determined by the gate voltage of the switching element 9, but the gate voltage is determined by the voltage of the power supply 1. FIG. 4 shows a primary coil waveform of the high voltage generating transformer of FIG. In FIG. 4, distortion is generated in the + side waveform as compared with the − side waveform. The cause of the distortion is that the switching operation of the second switching element 9 causes
The primary-side voltage of FIG. 4 is generated at both ends of the power supply 1, but the voltage is higher than the power supply voltage of the power supply 1. Therefore, the electrolytic capacitor 14 works to absorb the excess of the voltage. . Further, the voltage passes through the electrolytic capacitor 14, passes from ground to the other end of the high-voltage generating transformer 11 from the source to the drain of the second switching element 9, and forms a closed circuit. At that time, in order to prevent a voltage from being applied to the second switching element 9 in the reverse direction, the function of the second switching element 9 is controlled by the function of a rectifying element built between the source and the drain. In the switching operation, waveform distortion on the + side appears. Therefore, when the secondary voltage of the high-voltage generating transformer 11 has a peak value and the output voltage is limited to about 5 KV, and the output voltage is to be increased, the power supply voltage of the power supply 1 must be increased. There was a problem that would not be.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is capable of generating a higher voltage even when the power supply 1 is at 12 V as compared with the related art. A voltage generator is provided.

[0010]

In order to solve the above problems, a DC power supply, a high-voltage generating transformer having a primary coil to which one end of the DC power supply is connected, a switching element, and a DC power supply. A high-voltage generator includes an electrolytic capacitor connected to both ends, and a rectifier having an anode connected to the other end of the primary coil, and a cathode of the rectifier connected to the switching element. According to claim 2, a DC power supply, an anode of a rectifying element for the DC power supply, and a cathode of the DC power supply are used as one of high-voltage generating transformers.
A high voltage generator is connected to one end of the secondary coil and a switching element is connected to the other end of the primary coil.

[0011]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In FIG. 1, a + power supply of a power supply 1 composed of a DC power supply is connected to one end of a primary side of a high-voltage generating transformer 11, and both ends of the primary side of the high-voltage generating transformer 11 have LC resonance. A circuit capacitor 10 is connected. The other end of the high-voltage generating transformer 11 is a rectifying element 21.
And the cathode of the rectifier 21 is
The drain of the second switching element 9 composed of an FET or the like is connected to the drain, and the source of the second switching element 9 is connected to the ground which is the minus power supply of the power supply 1. One end on the secondary side of the high-voltage generating transformer 11 is connected to a high-voltage terminal 12.
The other end is connected to a high-voltage terminal 13, and these high-voltage terminals 12 and 13 serve as power supply terminals for generating a high voltage in this circuit.

Control circuit power supply 2 composed of DC power supply
Are connected to the + power supply terminal and the − power supply terminal of the control circuit 15, respectively.
The power supply and the negative power supply of the power supply 1 are connected as a ground.
Although the control power supply 2 is a separate power supply in the embodiment of the present invention, the same effect can be obtained by supplying a power supply voltage from the power supply 1 through a voltage dividing resistor, though not shown. Voltage dividing resistors 3 and 4 are connected in series to the output of the control circuit 15, and one end is connected to the ground. The connection between the voltage dividing resistors 3 and 4 is connected to the base of the first switching element 5 composed of a transistor or the like. The emitter of the first switching element 5 is connected to ground, the collector is connected to a pull-up resistor 6 and a current limiting resistor 7, and the other end of the resistor 6 is connected to the + terminal of the power supply 1, The other end of 7 is connected to the gate of the second switching element 9.
The cathode of the Zener diode 8 for overvoltage protection is connected to the gate of the second switching element 9, and the anode of the Zener diode 8 is connected to the ground. An electrolytic capacitor 14 is connected to both ends of the power supply 1.

Next, the operation of this circuit will be described. FIG.
, A square wave of an on / off digital signal is output from the control circuit 15. In response to this digital signal,
The switching element 5 performs an ON / OFF amplification operation.
That is, the signal is received from the base of the first switching element 5 and amplified to the collector. By the signal,
An on / off pulse-like switching signal is generated at the drain of the second switching element 9, passes through the rectifying element 21, generates an AC voltage on the primary winding of the high-voltage generating transformer 11, To generate a boosted high voltage. The Zener diode 8 is inserted for overvoltage protection, and the gate voltage is maintained at a constant voltage.

FIG. 5 shows the input waveform of the second switching element.
FIG. 3 shows the waveform of the primary coil of the high-voltage generating transformer shown in FIG. In FIG. 5, the second switching element
The signal waveform shown in FIG. 3 is applied to the primary-side terminal of the high-voltage generating transformer 11 according to the ON / OFF signal waveform input to the gate 9. When turned on in FIG. 3, the waveform becomes the same distorted waveform as that when turned on in FIG. 4, but when turned off, a + side waveform larger than the waveform when turned on can be obtained. A large waveform is obtained as compared with the conventional example. This is because the rectifying element 21 is connected to the high-voltage generating transformer.
When the input signal shown in FIG. 5 is turned off, a back electromotive force is generated in the primary coil of the high-voltage generating transformer 11 by the current flowing through the primary coil 11 and the source-drain voltage of the second switching element 9 is reduced. Via the rectifier inserted in the
A large waveform is obtained to prevent absorption by the electrolytic capacitor 14 connected in parallel with the power supply 1.

As a result, the high-voltage generating transformer 11
In the primary coil, a voltage higher than the voltage of the power supply 1 can be generated, and a primary voltage larger than that of the conventional circuit can be obtained. As a result, the secondary coil of the high-voltage generating transformer 11 Higher voltage than conventional circuits can be generated. Further, the balance between the + and-waveforms of the voltage waveform applied to the primary coil of the high-voltage generating transformer 11 is improved, and a stable voltage can be supplied to the secondary coil. As a specific voltage, a voltage between the high voltage terminals 12 and 13 is conventionally about 5 KV, but in the present invention, a high voltage of about 8 KV can be generated.

In another embodiment, the rectifying element 21 is inserted at a position where the rectifying element 21 of FIG. 1 is short-circuited and the rectifying element 21 is inserted between one end of the high-voltage generating transformer 11 and the electrolytic capacitor 14. The same effect can be obtained by inserting. This is indicated by a rectifying element 22 indicated by a dotted line in FIG. 1. The connecting direction of the rectifying element 22 is as follows. are doing.

The power supply 1 described in the above embodiment, the output waveform of the digital signal of the control circuit 15, the back electromotive force waveform generated by the coil 21, and the primary and secondary sides of the high voltage generating transformer 11 The voltage to be applied is described in the embodiment, and the same effect can be obtained even if the voltage is other than these values.

[0018]

When the power supply 1 is 12 V, a voltage higher than the conventional power supply voltage can be generated on the secondary side of the high-voltage generating transformer, and the primary-side input of the high-voltage generating transformer can be generated. The voltage waveform also becomes a sine waveform, and the efficiency of the circuit can be improved. A high voltage can be generated at the same voltage, which could not be realized unless the power supply voltage was increased in the past.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high voltage generator showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional high voltage generator.

FIG. 3 is a primary coil waveform of the high-voltage generating transformer of FIG. 1;

FIG. 4 is a primary coil waveform of the high voltage generating transformer of FIG. 2;

FIG. 5 is an input waveform of a second switching element.

[Explanation of symbols]

 The same reference numerals in the drawings denote the same or corresponding parts. DESCRIPTION OF SYMBOLS 1 Power supply 2 Power supply for control circuits 3, 4 Voltage dividing resistor 5 First switching element 6, 7 Resistance 8 Zener diode 9 Second switching element 10 Capacitor 11 High voltage generating transformer 12, 13 High voltage terminal 14 Electrolytic capacitor 15 Control Circuit 21, 22 Rectifier

Claims (2)

[Claims] A DC power supply; a high voltage generating transformer having a primary coil to which one end of the DC power supply is connected; a switching element; an electrolytic capacitor connected to both ends of the DC power supply; A high voltage generator comprising a rectifying element having an anode connected to the other end of the coil, wherein the anode of the rectifying element is connected to the switching element. 2. A DC power supply, an anode of a rectifier element connected to the DC power supply, and a cathode connected to one end of a primary coil of a high-voltage generating transformer, and a switching element connected to the other end of the primary coil. 2. The high-voltage generator according to claim 1, wherein: