JPH09191638A - Dc/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small, thin and lightweight DC/DC converter by comprising the DC/DC converter of an inverter circuit including two or more semiconductor switches to be connected with positive and negative potentials, a plurality of rectifiers connected in series, and a voltage multiplier rectifier circuit including a plurality of capacitors connected in series thereby eliminating a high voltage transformer. SOLUTION: A DC voltage at input terminals 1, 2 is received by a capacitor 11 and converted into an AC voltage through switching transistors 13, 14 being turned on/off by a control circuit 12. The control circuit 12 and the switching transistors 13, 14 constitute an inverter circuit. The AC voltage is further converted into a DC voltage through a voltage multiplier rectifier circuit comprising capacitors 101-140, diodes 201-280 and capacitors 301-340. Since a high voltage transformer is eliminated, the inventive DC/DC converter can deal with the requirements of reducing the size, weight and thickness of OA apparatus sufficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC converter for converting a high-voltage DC voltage. Further, for example, a developing drum of an electrostatic recording (electrophotographic) copying machine or printer is charged or charged. The present invention relates to a DC / DC converter that converts a high-voltage DC voltage to remove electricity.

[0002]

2. Description of the Related Art A general circuit configuration of a conventional high-voltage DC / DC converter is shown in FIG. In FIG. 4, the DC voltage of the input terminals 1 and 2 (voltage of the capacitor 11) is converted into AC by the switching transistor 21 and boosted to a high voltage by the transformer (transformer) 22, and the high voltage diode 2
Rectified by 3, high DC voltage (voltage of capacitor 24)
Was converted and supplied to the load terminals 3 and 4. DC / DC converter of this type is, they are generally operated at a high frequency of switching of 20KH _Z ~1MH _Z. As described above, the switching converter method is the RCC.
The flyback method shown in FIG. 4 represented by a (ringing choke converter) method is often used. As described above, the circuit operation of the conventional system shown in FIG. 4 is connected so that the DC voltage of the input terminals 1 and 2 is applied to the primary winding of the high voltage transformer 22 through the switching transistor 21. Then, when the switching transistor 21 is turned on, a reverse voltage is applied to the high voltage rectifier diode 23 connected to the secondary winding of the high voltage transformer 22, and no current flows.
At this time, an exciting current is flowing through the primary winding of the high voltage transformer 22. Then, when the switching transistor 21 is turned off, the exciting current (exciting energy) that has been flowing until now continues to flow and generates a counter electromotive force. Therefore, the exciting current due to this counter electromotive force is generated in the secondary winding of the transformer 22. The high-voltage DC voltage is supplied to the load terminals 3 and 4 through the smoothing capacitor 24 through the connected high-voltage rectifier diode 23.

[0003]

In recent years, in OA (office automation) equipment such as copiers, printers, and facsimiles, there is a strong demand for downsizing, weight reduction, and thinning. However, D used for the above applications
C / DC converter (especially D converting to high voltage DC voltage)
In the C / DC converter), the high voltage transformer provided in the DC / DC converter is a major obstacle to the demands for downsizing, weight reduction, thinning, and the like. A high-voltage transformer has a basic structure in which a copper wire is wound around a magnetic body, but simply thinning this high-voltage transformer will make the magnetic body smaller, and if the magnetic body is made smaller in this way, the voltage per turn will be reduced. As a result, the number of turns of the copper wire winding is necessarily increased. However, in the high-voltage transformer, it is essential to make the insulation distance between the winding and / or the magnetic material wide because of the high voltage, and there is a practical limit to the design for miniaturization and thinning. Therefore, the above DC / DC
There is a problem that it is not possible to meet the demands for downsizing, weight saving, and thinning of the converter. Therefore, the present invention solves the problems existing in the above-mentioned prior art, does not require a high-voltage transformer, and can sufficiently meet the demands for downsizing, weight reduction, and thinning of OA equipment. An object is to provide a DC converter.

[0004]

In order to solve the above problems, the present invention provides at least two or more semiconductor switches each including a semiconductor switch connected to a positive potential and a semiconductor switch connected to a negative potential. A DC / DC converter including an inverter circuit provided and a multiple voltage rectifier circuit including a plurality of rectifiers connected in series and a plurality of capacitors connected in series is adopted. Further, according to the present invention, an inverter circuit including at least two semiconductor switches including a semiconductor switch connected to a positive potential and a semiconductor switch connected to a negative potential, a plurality of rectifiers connected in series, and A DC / multi-voltage rectifier circuit configured by connecting one end of a plurality of capacitors connected in series to the semiconductor switch connected to the positive potential and the semiconductor switch connected to the negative potential.
DC converter is adopted. The present invention can employ a DC / DC converter having a DC / DC converter for boosting a low voltage to an intermediate voltage and a DC / DC converter for boosting a high voltage from the intermediate voltage.

According to the present invention described above, a switching transistor which is connected to the positive potential of the input DC voltage without using a winding component such as a high voltage transformer or a choke coil,
AC voltage is generated by an inverter circuit that alternately turns on a switching transistor that is connected to a negative potential, and multiple voltage rectification that includes a large number of diodes connected in series and a large number of capacitors connected in series High-voltage DC voltage can be created in the circuit and supplied to the load. For example, 20
When converting from V to 2 KV, 100 times boosting is required. In this case, the circuit configuration using 200 diodes and 200 capacitors can increase the voltage by 100 times, but is not suitable for downsizing and is not efficient. However, according to the present invention, for example, with the booster circuit configuration to the intermediate voltage of the first stage using 20 diodes and 20 capacitors, the first stage from 20V to 200V (intermediate voltage). The voltage is boosted, and then the second voltage is boosted from 200 V (intermediate voltage) to 2 KV by the voltage boosting circuit configuration to the second voltage target voltage configured by 20 diodes and 20 capacitors. be able to.
Therefore, according to the above configuration, it is possible to increase the voltage 100 times with a total of 40 diodes and 40 capacitors. Boosting circuit configuration to the first stage intermediate voltage using the above 20 diodes and 20 capacitors, and boosting to the second stage target voltage using 20 diodes and 20 capacitors A specific example having a circuit configuration will be described later with reference to FIG.

Further, according to the present invention, as shown in FIG. 3 described later, the transistor 2 having a phase opposite to that of the transistors 13 and 14 is used.
5, 26 (transistor 25 that is off when transistor 13 is on, and transistor 26 that is off when transistor 14 is on), and transistors 29 and 32 in opposite phase to transistors 15 and 16, respectively. In addition to the adoption, it is also possible to supply the DC voltage boosted 100 times, for example, with the configuration of the multiple voltage rectifier circuit using 20 diodes and 20 capacitors. As described above, according to the present invention, it is possible to supply a high-voltage DC voltage by combining medium-voltage components instead of high-voltage components. DC to convert
The DC / DC converter can be designed and manufactured to be small, thin, and lightweight.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows an example of the circuit configuration of the DC / DC converter of the present invention. In FIG. 1, the DC voltage of the input terminals 1 and 2 is received by the capacitor 11, and turned on by the control circuit 12,
It is converted into alternating current by the switching transistors 13 and 14 which are driven off. In this way, the control circuit 12 and the switching transistors 13 and 14 form an inverter circuit. Further, it is converted and rectified into a high voltage DC voltage by a multiple voltage rectifier circuit composed of capacitors 101 to 140, diodes 201 to 280, and capacitors 301 to 340. Note that, in FIG. 1, capacitors 102 to 138 and a diode 20 which are respectively connected in series.
4 to 277 and capacitors 303 to 339 are omitted in FIG. 1, for example, the capacitor 101, the diodes 201 and 202, and the capacitors 301 and 302, for example.
The capacitors 102 to 138, the diodes 204 to 277 and the capacitor 303 omitted by repeating the circuit arrangement similar to the positional relationship in which and are connected and arranged via the connection terminals A, B, C, D, E and F, respectively. 1 to 339 are arranged to configure the multiple voltage rectifier circuit of FIG.

The multiple voltage rectifier circuit of FIG. 1 will be described.
When transistor 14 is on, transistor 1
Since 3 is off, the input DC voltage of the capacitor 11 is applied to the capacitor 301 through the diode 201 and the transistor 14 and charged to the same voltage level as the capacitor 11. Next, when the transistor 13 is turned on, the transistor 14 is turned off.
Is applied to the capacitor 101 by the diode 202 and the transistor 13 to be charged to the same voltage level as the capacitor 301. Then again the transistor 14
When is turned on, the transistor 13 is turned off, so that the voltage of the capacitor 11 is applied to the capacitor 301 and further applied to the capacitor 302 through the diode 203 to be charged to the voltage level of the capacitor 101. When the transistors 13 and 14 are alternately turned on and off as described above, the capacitors 101 to 1
40 and all the capacitors 301 to 340 are charged to the same voltage level as the input voltage capacitor 11. Therefore, the load terminals 3,
The DC voltage of 41 times the input voltage is supplied to 4. When the total number of capacitors and diodes in the multiple voltage rectifier circuit of FIG. 1 is increased from 80 to 199, a voltage 100 times the input voltage can be supplied.

FIG. 2 shows another example of the configuration of the DC / DC converter of the present invention. In FIG. 2, the capacitor 101
-110, diodes 201-220, and capacitor 30
The input DC voltage is boosted to 11 times the intermediate DC voltage by the first-stage multi-voltage rectifier circuit composed of 1 to 310, that is, the booster circuit to the first-stage intermediate voltage (11 times voltage). Next, switching between the transistor 15 and the transistor 16 converts the voltage into an AC voltage of 11 times, the transistor 15 is turned on at the same time as the transistor 13 by the resistors 19 and 20, and the transistor 16 is connected to the transistor 14 by the resistors 17 and 18. Since they are turned on at the same time, capacitors 401 to 410 and diodes 501 to
The voltage is further boosted to 11 times by a second-stage multi-voltage rectifier circuit composed of 520 and capacitors 601 to 610, that is, a booster circuit to the second-stage target voltage (11-fold voltage). Therefore, it is possible to supply to the load terminals 3 and 4 a high-voltage DC voltage obtained by boosting the input DC voltage by 121 times in total. Further, when the control circuit 12 controls the transistor 14 to be turned off before reaching the input voltage level when the capacitor 301 is charged after the transistor 14 is turned on, the load voltage is set to an arbitrary voltage. Can be adjusted to. In FIG. 2, the capacitors 103 to 109, the diodes 205 to 218, and the capacitors 303 to 309 in the first-stage multi-voltage rectifier circuit.
Are omitted, and capacitors 403 to 409 and a diode 50 in the second-stage multi-voltage rectifier circuit are omitted.
5 to 518 and capacitors 603 to 609 are not shown, each of them is connected by repeating the arrangement similar to the capacitors and diodes shown in the above-mentioned multiple voltage rectifier circuit. A multiple voltage rectifier circuit is configured.

Next, an example of still another configuration of the DC / DC converter of the present invention is shown in FIG. In FIG. 3, transistors 25 and 26 (transistor 13 and 14 driven by the control circuit 12 in the opposite phase to the transistors 13 and 14) are used.
Since the transistor 26 that is turned on at the same time and the transistor 25 that is turned on at the same time as the transistor 14 are connected to the capacitors 301 to 310, when the transistors 14 and 25 are turned on, the input of the capacitor 11 is input to the capacitor 301 through the diode 201. A voltage is applied and it is charged. Next, the transistor 13
When the transistor 26 is turned on, a voltage twice the input voltage is applied to the capacitor 101 through the diode 202 by the capacitor 11, the transistor 13 and the capacitor 301. Next, when the transistors 14 and 25 are turned on, the voltage of the capacitor 101 is applied to the capacitor 302 through the diode 203.
By repeating this, the capacitors 302 to 310 and the capacitors 101 to 110 are all applied and charged to a voltage twice the input voltage, so that the input DC voltage is boosted to the intermediate voltage 22 times. Thus, the capacitors 101-110
And diodes 201-220 and capacitors 310-31
By connecting 0 and 0 as shown in the figure, a multistage voltage rectifier circuit in the first stage, that is, a booster circuit to the intermediate voltage (22 times voltage) in the first stage is configured. Similarly, transistor 1
Transistors 29 and 32 that operate in opposite phases to 5 and 16 are connected as shown, and capacitors 401 to 410 and diodes 501 to 520 are connected in series.
By connecting the capacitors 601 to 610 as shown in the figure, a multistage voltage rectifier circuit of the second stage, that is, a booster circuit of the second stage to the target voltage (22 times the voltage) is configured, and the voltage of the 22 times the voltage is further increased. Can be boosted to. Therefore, FIG.
With this configuration, it is possible to boost the voltage up to a total of 484 times. Note that, in FIG. 3, the capacitors 102 to 108 and the diode 20 in the first-stage multi-voltage rectifier circuit are shown.
4 to 215 and capacitors 303 to 308 are omitted, and capacitors 403 to 408, diodes 504 to 514, and capacitors 603 to 608 in the second-stage multi-voltage rectifier circuit are omitted. ,
Each of them is connected by repeating the same arrangement and arrangement as the capacitors and diodes shown in the above-mentioned multiple voltage rectifier circuit to form this multiple voltage rectifier circuit. As described above, the present invention, which does not use winding parts such as a transformer or a choke coil, can form a DC / DC converter with a semiconductor, a resistor, and a capacitor, and therefore is much easier to integrate (IC) than before. Is.

[0011]

According to the present invention, a large number of diodes and capacitors are used. However, since a high-voltage DC / DC converter having unique characteristics can be constructed only with resistors, capacitors and semiconductors (diodes, transistors, etc.), all elements are used. Can be incorporated inside the integrated circuit. Therefore, winding components such as a high-voltage transformer and a choke coil in the conventional DC / DC converter are not required, and it is possible to sufficiently meet the demands for downsizing, weight saving, and thinning of OA equipment, which is extremely useful. A high-voltage DC / DC converter with high power consumption can be constructed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a circuit configuration of a DC / DC converter of the present invention.

FIG. 2 is a diagram showing another example of the circuit configuration of the DC / DC converter of the present invention.

FIG. 3 is a diagram showing still another example of the circuit configuration of the DC / DC converter of the present invention.

FIG. 4 is a diagram showing a circuit configuration example of a conventional DC / DC converter.

[Explanation of symbols]

1, 2 input terminals, 3, 4 load terminals, 11, 24 capacitors, 12 control circuits, 13, 14, 15, 16,
25, 26, 29, 32 transistors, 22 transformers, 23 diodes, 17, 18, 19, 20, 2
7, 28, 30, 31 Resistance, 101-140 Capacitor, 201-280 Diode, 301-340
Capacitors, 401-410 capacitors, 501-5
20 diodes, 601 to 610 capacitors, 39
0,690 capacitor.

Claims (3)

[Claims] 1. An inverter circuit having at least two semiconductor switches, each semiconductor switch having a positive potential semiconductor switch and a negative potential semiconductor switch, and a plurality of rectifiers connected in series to each other. And a multiple voltage rectifier circuit having a plurality of capacitors connected to the DC / DC converter. 2. An inverter circuit comprising at least two or more semiconductor switches each comprising a semiconductor switch connected to a positive potential and a semiconductor switch connected to a negative potential, a plurality of rectifiers connected in series and a series. One end of each of the plurality of capacitors connected to is connected to the semiconductor switch connected to the positive potential and the semiconductor switch connected to the negative potential, and the multiple voltage rectifier circuit is configured. DC / DC converter. 3. DC / DC for boosting a low voltage to an intermediate voltage
Converter and DC / that boosts the intermediate voltage to a higher voltage
The DC / DC converter according to claim 1 or 2, comprising a DC converter.