JPH03103027A - Power supply - Google Patents

Abstract

PURPOSE:To prevent danger such as discharge and to lower the breakdown strength of a transformer by connecting respective outputs from output circuits, connected respectively with the outputs from a plurality of booster transformers, in series thereby controlling the input side of the booster transformer. CONSTITUTION:Inverter transformers T1, T2 are switched respectively by means of transistors Q1, Q2. Bases of the transistors Q1, Q2 are controlled based on a predetermined switching pulse. Capacitors C2-C5 and diodes D3-D6 constitute a halt-wave four fold voltage rectifier at the secondary of the inverter transformer T1. Absolute value of the output voltage on the side of the inverter transformer T1 is set high while that on the side of the inverter transformer T2 is set low thus setting the breakdown strength of the inverter transformer T1 low on the side of the feeder line 11 for a load. Consequently, an inexpensive power supply can be realized by the use of an inexpensive booster transformer having low primary and secondary breakdown strength.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a power supply device, and particularly to a power supply device that connects in series each output of an output circuit connected to the output of a plurality of step-up transformers to supply power to a load. It is. [Prior Art J] Power supplies such as DC/DC inverters that output high voltage for use in chargers of copying machines and the like have been known. When using this type of device, high voltages of various values may be required, and a method is known in which the outputs of a plurality of inverter transformers are combined in series to form a desired high voltage.

Conventionally, when the outputs of two or more transformers are superimposed in such a configuration, the insulation voltage between the primary and secondary of the inverter transformer used is set to be higher than the output voltage of the circuit. [Problem to be Solved by the Invention 1] Furthermore, in general, the breakdown voltage specifications between the primary and secondary are proportional to the cost of the transformer, and the higher the breakdown voltage, the higher the manufacturing cost of the device. However, in the above-mentioned conventional technology, when a high voltage is generated in a step-up circuit by making full use of an inverter transformer that is relatively inexpensive and has a low transformation ratio, and is output by superimposing it with a voltage similarly generated by another transformer, There was a risk of leakage and discharge due to insufficient withstand voltage between the secondary and secondary components.

Therefore, if the withstand voltage of the transformer can be reduced without the risk of discharge, even with the same output voltage, a cost reduction effect can be expected. An object of the present invention is to solve the above problems.

[Thousand steps to solve the problem] In order to solve the above problems, in the present invention, each output of an output circuit connected to the output of a plurality of step-up transformers is connected in series, and the input of the step-up transformer is connected in series. In a power supply device that supplies a composite voltage of output voltages from each output circuit to a load by controlling the side, the reference potential of the load and the reference potential of the input of the step-up transformer are set equal, and each output circuit is One end of the series circuit is connected to the reference potential, and the other end is connected to the input terminal of the load, and further, among the series-connected output circuits, the closer to the output side to the load the more the absolute value of the output voltage increases. We adopted a configuration in which the absolute value of the output voltage is set to be high, and the absolute value of the output voltage is set to be low for circuits that are closer to the reference potential. [Function J] According to the above configuration, the potential on the output side of each step-up transformer can be made lowest for any combination of output voltages, so that the voltage between the primary and secondary (input and output) coils of each step-up transformer can be The required withstand voltage can be reduced. [Example 1] Hereinafter, the present invention will be explained in detail based on an example shown in the drawings. First Embodiment FIG. 1 shows a first embodiment of the power supply device of the present invention. In the figure, the symbol TI. T2 is an inverter transformer, and transistors Ql. It is switched in Q2.
Transistor Ql. The base of Q2 is controlled by a predetermined switching pulse. When this base drive is stopped, the output of each inverter transformer is stopped. Although not shown here, it goes without saying that the load current and voltage can be controlled as desired by providing means for adjusting the waveforms and frequencies of the switching pulses of the transistors Ql and Q2. Inverter transformer TI. On the primary side of T2, the symbol Rl. R2 is a resistor to increase switching speed. Resistors R3 and R4 are inverter transformers TI and T2
Viewed from above, the capacitors C1 and C2 form a pair to form an integrator, and the inverter transformer TI. It acts as a filter to prevent the switching noise of T2 from being transmitted to the power supply line Vcc connected to the inverter transformer TI and the midpoint of the primary coil of T2. However, the resistance values of the resistors R3 and R4 are set so small that the voltage drop can be ignored. Daisaiichido D
I. D2 is an inverter transformer TI. This is for resetting T2. On the other hand, on the secondary side of the inverter transformer TI, capacitors C2 to C5 and diodes D3 to D
6 constitutes a half-wave quadruple voltage rectifier circuit. Also, on the secondary side of the inverter transformer T2, the capacitor CI
and diode DI constitute a half-wave rectifier circuit. Resistors R5 and R6 are connected to each of the rectified outputs in parallel with the line. Further, the output on the positive side of the inverter transformer T2 is grounded, and the output on one side is connected to the one side output of the inverter transformer Tl through a line 1, and power is supplied to the external load Z from the positive side of the inverter transformer TI. That is, inverter transformer TI. The secondary outputs of T2 are connected in series.

Note that resistors R5 and R6 are internal load resistors that limit the transformer output voltage when no load is applied and adjust the responsiveness of voltage rise and fall.

In the above configuration, transistor Q1. When a switching pulse is applied to the base of inverter transformer TI. If the field pressure ratio of T2 is the same, V on the secondary side
A voltage equal to cc multiplied by the boost ratio is induced. For example, when Vcc is 20V and the step-up ratio is 50, a voltage of lOOOV is induced on the secondary side of the transformer, the voltage Vl across the internal load resistor R5 is 4000V, the voltage V2 across the resistor R6 is 1000V, and the external The voltage VO applied to the load Z is 4000-1000=3000V. When the switching pulse is applied only to the base of transistor Q1, Vl = 4000V, V2 = OV
．． If the output voltage is 4000V. Moreover, when a switching pulse is applied only to the base of transistor Q2, vl=OV. V2 = 1000V, and the output VO becomes -iooov. However, external load Z
Assume that resistances R5 and R6 are sufficiently small compared to . In the above settings, the absolute value of the output voltage on the inverter transformer TI side is set high, and the absolute value of the output voltage on the inverter transformer T2 side is set low. In other words, the absolute value of the output voltage of the high voltage output section on the power supply line 11 side to the load is increased, and
The absolute value of the output voltage of the high voltage output section close to the ground side is set low. According to such output voltage setting, the withstand voltage of at least the inverter transformer TI on the power supply line 11 side to the load can be set low, as shown below.

First, according to the above configuration, when only the inverter transformer T2 is driven, IOOOV is induced in v2, and is applied to the secondary coil of the inverter transformer TI via the line l. Therefore, since there is a potential difference of about tooov between the primary and secondary coils of the inverter transformer TI, the withstand voltage between the primary and secondary coils of the inverter transformer TI must be at least 1000V. On the other hand, when only the inverter transformer TI is driven, V
1 = 4000V is induced and applied to the external load resistance Z, but since the secondary coil of the inverter transformer T2 is at ground level, the primary and secondary withstand voltages are 40V in this operating state.
00V is not necessary.

Therefore, the inverter transformer TI only needs to have a coil breakdown voltage between the primary and secondary coils that can withstand a voltage of 1,000V.
In addition, inverter transformer T2 is inverter transformer TI
, T2, the same <tooov
It can be seen that it is sufficient to have primary and secondary breakdown voltages of . To make this more clear, Figure 2 shows different connection structures. The order of series connection of the secondary side outputs of inverter transformers TI and T2 is reversed, and the inverter transformers TI and T2 are connected in series. transformer T
One end of the I side is grounded, and the output is output from the inverter transformer T2 side to the external load resistor Z.

And inverter transformer TI. Since the configuration of the rectifier circuit on the secondary side of T2 is the same as in Figure 1, in Figure 2, the absolute value of the boosted output of the transformer TI that is far from the output end (on the ground side) is larger. However, under the same input conditions as in the example of FIG. 1, the voltage applied to the external load resistor Z is the same as in the example of FIG. In other words, when looking at the power supplies as a whole, they can be considered to have similar functions. Here, under the same conditions as in Fig. 1, inverter transformer TI
Considering the case where only is driven, V1=4 0'0 0
V is induced into the external load resistance Z through the resistor R6.
00V will be applied. Therefore, 4000V is applied to the secondary coil of the inverter transformer T2, and the withstand voltage between the primary and secondary of the inverter transformer T2 must be at least 4000V or more.

Therefore, by using the configuration shown in Figure 1 instead of the configuration shown in Figure 2, the withstand voltage of the inverter transformer TI can be significantly reduced from the conventionally required 4000V to IOOOV, without the risk of leakage or discharge. , the manufacturing cost of the device can be reduced. Second Embodiment FIG. 3 shows the configuration of a more generalized power supply device as a second embodiment of the present invention.

Here, three inverter transformers Tl-T3 are used, and the primary side of each is switched by primary drive circuits 3l to 33, while step-up rectifier circuits 41 to 43 are connected to each secondary side to perform rectification. The outputs are connected in series via resistors Rll-Rl3. Here, the boost rectifier circuit 4l is connected to the output side, and the boost rectifier circuit 43 is connected to the ground side.

Here, the output of the step-up rectifier circuit 41 of the inverter transformer T3 is set to V3, and the step-up rectifier circuit 4 of the inverter transformer T4 is set to V3.
Each of the six rectifier circuits 41 to 43 has the output of step-up rectifier circuit 43 of inverter transformer T5 as v4, and the output of step-up rectifier circuit 43 of inverter transformer T5 as v5.
It consists of a voltage doubler rectifier circuit as shown in FIG. Further, the configuration of the primary drive circuits 31 to 33 on the primary side is also the same as that in FIG. 1.

With such a configuration, more voltage values can be output by combining three high voltage outputs. For example, if the external load resistance Z is +4000V. +2000V, OV. -20
00V. When applying 5 types of voltages of -4000V,
V3=4000V. V4 = -2000V. V5=-
Set to 2000V and drive the l-order drive circuits 31 to 33.
This can be achieved by controlling these voltages in a non-driving manner and combining them.

In this way, among transformer output circuits connected in series, the circuit closer to the output side is set to have a higher absolute value of the output voltage, and the circuit closer to the ground side is set to have a lower absolute value of the output voltage. Similarly to the example, the withstand voltage between the primary and secondary of the transformer can be reduced. In the case of Figure 3, 2000V withstand voltage can be used for all transformers. If you do not set the voltage as shown above in Figure 3,
To obtain the same power output, v3=-2000V
, V4 = -2000V%V5 = +4000V, but in this configuration, the withstand voltage of inverter transformers T3 and T4 must be set to 4000V as in the case of Fig. 2. No.

As shown above, even when three transformer outputs are combined, the circuit closer to the output side of the transformer output circuits connected in series has a higher absolute value of the output voltage, and the circuit closer to the ground side has a higher absolute value of the output voltage. By setting the absolute value low, it is possible to achieve the combination of the lowest primary and secondary withstand voltages for each transformer, and it is possible to provide a simple and inexpensive power supply device without risks such as leakage and discharge.

[Effects of the Invention] As is clear from the above, according to the present invention, each output of the output circuit connected to the output of a plurality of step-up transformers is connected in series, and the input side of the step-up transformer is controlled. In a power supply device that supplies a composite voltage of output voltages from each output circuit to a load, the reference potential of the load and the reference potential of the input of the step-up transformer are set equal, and one end of the series circuit composed of each output circuit is set to be equal to the reference potential of the load. The circuit is connected to the reference potential and the other end is connected to the input terminal of the load, and further, among the output circuits connected in series, the circuit closer to the output side to the load has a higher absolute value of the output voltage. Since we have adopted a configuration in which the absolute value of the output voltage is set lower for the circuit closer to the reference potential, in any combination of output voltages, the potential on the output side of each field voltage transformer can be lowest. The required withstand voltage between the primary and secondary (input and output) coils can be reduced, and an inexpensive step-up transformer with lower primary and secondary withstand voltages can be used to create a simple and inexpensive power supply without the risk of leakage or discharge. realizable.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of the main parts of a first embodiment of a power supply device according to the present invention, FIG. 2 is a circuit diagram showing the operation of the configuration of FIG. 1, and FIG. 3 is a circuit diagram of a second embodiment of the present invention. This is the circuit diagram. Rl-R6, Rll-R engineering l3...Resistance DI-D6.
...Diodes Ql, Q2...Transistors TI, T2...Inverter transformer 2 -.External load resistors 31 to 33...L-order drive circuits 4l to 4 3 -.Step-up rectifier circuit

Claims (1)

[Claims] 1) A composite voltage of output voltages from each output circuit by connecting in series the outputs of output circuits respectively connected to the outputs of a plurality of step-up transformers and controlling the input side of the step-up transformers. In a power supply device that supplies power to a load, the reference potential of the load and the reference potential of the step-up transformer input are set equal, one end of a series circuit composed of each output circuit is connected to the reference potential, and the other end is connected to the reference potential. is connected to the input terminal of the load, and further, among the output circuits connected in series, the circuit closer to the output side to the load has a higher absolute value of the output voltage, and the circuit closer to the reference potential has a higher absolute value of the output voltage. A power supply device characterized by setting a low value.