JPS58112462A - Switching regulator - Google Patents

Abstract

PURPOSE:To insulate between an input and an output with a simple structure by producing and feeding back a voltage feedback amount for controlling a DC output voltage from a high frequency voltage insulated from a DC output at the front stage of the DC output. CONSTITUTION:An AC input is converted by an AC rectifier 1 to a direct current, is converted via a DC/AC inverter into a high frequency electric power, and is then step-up rectified by an insulating transformer 3 and an output rectifier 4, thereby obtaining a DC output. The high frequency voltage which is produced from the output voltage detecting coil of the transformer 3 is negatively fed back to a control amplifier 5, the current amount detected by an AC current detector 11 such as a current transformer which obtain an output proportional to the high frequency current amount at the front stage of a DC output is positively fed back to the amplifier 5, thereby correcting the voltage drop due to the output current of the transformer 3, the output rectifier 4 and the DC filter belonging thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to switching regulators, and particularly to a constant voltage output device with a simple configuration and insulation between input and output.

Switching regulators are often used in light electrical equipment with unspecified DC output loads, and most require insulation between input and output, with the insulation level of the AC or DC strong current input being different from the insulation level of the load. be.

,! rt An example of a conventional device is shown in FIGS.

After rectifying the AC power through the input rectifier 1.

A DC-AC inverter section 2 that receives a drive signal from the control amplification section 5 and converts it into high-frequency coercive force using electronic switching means.
The electric power is transmitted to an output rectifier 4 by an isolation transformer 3 which steps up and down the voltage of the inverter output and provides insulation between input and output, and is rectified into a DC output. As a means of making the output voltage constant, the DC output voltage is negatively fed back to the control amplification section 5,
In comparison with a predetermined reference quantity 6, an inverter drive signal for obtaining a predetermined constant voltage DC output is applied to the inverter part 2 via an isolation transformer 7, and the ′-electronic switching means of the inverter part 2 is opened and closed. A method is known in which a predetermined constant voltage DC output is obtained by changing the period ratio.

That is, according to this configuration, in order to isolate the input and output, the control power isolation transformer 8 is provided at the front stage of the control power rectifier 9 which outputs the DC control power supply 10 of the control amplifier 5, and the inverter 2 An insulation converter such as an insulation transformer 7 provided in the drive signal section of the converter is required.

In the conventional example in which the DC output voltage is directly fed back to the control amplification unit 5, the control voltage of the control amplification unit 5 and the drive signal, etc. are connected to the equipment connected to the front stage of the isolation transformer 3, that is, the input side. However, since these insulation conversion parts cannot be omitted, there are difficulties in reducing the size and improving reliability.

The purpose of the present invention is to solve the above-mentioned difficulties, to have a simple configuration, and to
This provides a highly reliable switching regulator with isolated input and output.

FIG. 2 shows one embodiment of the present invention.

The AC input is converted to DC via the input rectifier 1, and D
After converting into high frequency power in the C-AC inverter section 2, the isolation transformer 3. The output rectifier 4 performs step-up and step-up rectification to obtain a DC output.

The means for making the DC output voltage a constant voltage is to make the high frequency voltage output from the output voltage detection winding of the isolation transformer 3 into a negative feedback amount of the control amplifier 5, and further to the high frequency current amount at the stage before the DC output. The amount of current detected by the alternating current detection section 11, such as a current transformer that obtains a proportional output, is used as the positive feedback amount of the control amplification section 5, and the isolation transformer 3, output rectification section 4. By comparing and amplifying these with a predetermined reference amount 6 to compensate for the voltage drop due to the output current in the attached DC filter section, a DC- This is done by applying it to the AC inverter section 2.

Note that 10 indicates a control power supply circuit for the control amplification section 5.

Based on the above, only the isolation transformer 3, which is originally required for insulation between input and output, eliminates the need for other insulation conversion parts.
It can be used as a small switching regulator that provides a highly reliable constant voltage output.

FIG. 3 shows another embodiment of the invention. It is shown that the high frequency "withstanding current" in the preceding stage of the DC output related to the DC output current can also be obtained by the DC current detection section 12 provided on the DC input side.

FIG. 4 shows another embodiment of the invention. An arithmetic unit 14 is provided before the feedback input of the control amplification unit 5, and, for example, an amount 13 obtained by subtracting an amount related to the amount of high-frequency voltage and the amount of load current is negatively fed back to the control amplification unit 5. , it is shown that an effect similar to that obtained by directly feeding back the amount related to the load power to the control amplification unit 5 can be obtained.

Furthermore, Figure 1-5 shows the alternating current detection section 11 in Figure 2.
Although this is an example in which the transformer is placed on the secondary side of the isolation transformer 3, similar effects can be obtained in this case as well.

Furthermore, in the embodiments shown in FIGS. 2 and 4, the alternating current detection section 11 does not need to be a current transformer with insulation capability as shown in the figures, and may be, for example, a so-called current shunt. Even in this case, the transformer that insulates the input and output of the switching regulator and the output can be isolated by 3, so there is no need for the insulation measures required in conventional devices. .

Here, the control width section 5. The calculation unit 14 is shown in the form of directly taking the difference between the current and voltage of different dimensions, but this is naturally converted into a standardized form, for example, a DC voltage of 10V in the rated operating state, and then Needless to say, calculations are performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Input rectification part, 2... DC-AC inverter part, 3... Isolation transformer, 4... Output rectification part, 5...
Control amplification part, 6... Predetermined reference amount, 7... Isolation transformer between the control amplification part and the inverter part, 8... Transformer for control power supply, 9... Control power supply rectification part, 10 ... Control power supply, 11... AC current detection section, 12... DC current detection section, 13... 4 figures for high IT eyes man 2 haze 3 figures

Claims (1)

[Claims] 1. After converting the input into high-frequency power by switching at high speed using an electronic switching means, the input is rectified by an isolation transformer and a rectifier to obtain a DC output, and the period of opening and closing of the switching means is In a switching regulator that controls the DC output voltage to a predetermined value by changing the ratio, the voltage feedback amount needed to control the DC output voltage is extracted from the high-frequency voltage isolated from the DC output in the previous stage of the DC output, and the control amplification is performed. Furthermore, a feedback amount related to the DC output current amount and insulated from the DC output is outputted from the high-frequency current amount at the front stage of the DC output or the input DC current amount and sent to the control amplifier section. A switching regulator characterized in that the DC output voltage is controlled to a predetermined value by performing positive feedback, comparing and amplifying the positive feedback with a predetermined reference amount.