JP2009044837A - Insulating type switching power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an insulating type switching power supply device capable of transmitting signals, using a transformer for transmitting power. <P>SOLUTION: The insulating type switching power supply device insulating the primary winding side and the secondary winding side by the transformer is provided. There are provided a signal output means for outputting a signal transmitted from the primary winding side to the secondary winding side; a switching control means changing the frequency of a control pulse switching on or off a switching element, in response to the signal output from the signal output means; and a signal extracting means extracting the signal output by the signal output means from a pulse voltage, induced in a secondary winding for the transformer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an insulated switching power supply device in which a primary winding side and a secondary winding side are insulated by a transformer.

FIG. 10 is an explanatory diagram of power transmission and signal transmission in a conventional insulated switching power supply device, and FIG. 11 is a waveform diagram for explaining the operation of the conventional insulated switching power supply device.
A push-pull converter will be described as an example of an insulated switching power supply device. The primary side and the secondary side of the push-pull converter are insulated by a transformer TR1.

  By switching the switching elements SW1 and SW2, the voltage applied to the primary windings Np1 and Np2 of the transformer is controlled, and the output Vo of the DC voltage is output from the secondary winding Ns of the transformer via the rectifying and smoothing circuit U21. Take out.

  The oscillator U11 outputs pulse signals POUT1 and POUT2 having a constant duty ratio as shown in FIG. 11, and the switching elements SW1 and SW2 perform on / off operations according to the pulse signals POUT1 and POUT2, respectively. The switching elements SW1 and SW2 are constituted by transistors, FETs, and the like, for example.

The switching element SW1 and the switching element SW2 operate in opposite directions. When the switching element SW1 is on, the switching element SW2 is off, and when the switching element SW1 is off, the switching element SW2 is on.
In the secondary winding Ns, the voltage Vi × Ns / Np1 is generated on the positive side when the switching element SW1 is on, and the voltage Vi × Ns / Np2 is generated on the negative side when the switching element SW2 is on. The rectified and smoothed circuit U21 rectifies and smoothes and outputs a DC voltage output Vo.

  Signal transmission from the primary side to the secondary side is performed via the photocoupler PC1. The signal from the logic signal generator U12 is changed from an electric signal to an optical signal by the LED in the photocoupler PC1, and is electrically insulated by returning the optical signal to an electric signal by the light receiving element.

Japanese Patent Laid-Open No. 6-153531

  In an isolated switching power supply device, in order to transmit a primary signal to the secondary side, an insulating element such as a photocoupler must be used for signal transmission, and insulation is performed according to the amount of signal data. It was also necessary to increase the number of elements.

  In addition, these signal transmission components must be arranged in an insulating portion, and there is a problem that the mounting density on the printed circuit board cannot be made uniform.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to realize an insulating switching power supply device that can also transmit a signal using a power transmission transformer.

In order to achieve such a subject, the present invention is configured as follows.
(1) The primary winding side and the secondary winding side are insulated from each other by the transformer, and the voltage applied to the primary winding of the transformer is turned on and off by the switching element, thereby making the secondary winding of the transformer In an isolated switching power supply device that extracts a DC voltage output from a rectifying and smoothing circuit from
Signal output means for outputting a signal transmitted from the primary winding side to the secondary winding side;
Switching control means for changing the frequency of a control pulse for turning on and off the switching element in accordance with a signal output from the signal output means;
Signal extraction means for extracting a signal output by the signal output means from a pulse voltage induced in the secondary winding of the transformer;
An insulating switching power supply device comprising:

(2) The signal output means outputs n-ary data, and the switching control means generates and outputs a control pulse having a frequency corresponding to each value of the n-ary (1). The insulated switching power supply device described.

(3) The signal output means outputs a command indicating data attributes, and the switching control means generates and outputs a control pulse having a frequency determined for each command (1) or (2) The insulated switching power supply device according to (2).

(4) The signal output means outputs an analog value, and the switching control means generates and outputs a control pulse having a frequency determined according to the level of the analog value. Isolated switching power supply.

(5) The insulation according to any one of (1) to (4), wherein the switching control means outputs a control pulse having a predetermined frequency when there is no signal from the signal output means. Type switching power supply.

(6) The insulated switching power supply device according to any one of (1) to (5), wherein the switching control means adjusts a duty ratio of a control pulse in accordance with an output voltage supplied to a load.

The present invention has the following effects.
In addition to power transmission by the transformer, signal transmission can be performed, and the parts of the insulating portion can be reduced.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining signal transmission in FIG. The same parts as those in the previous figure are given the same reference numerals.
A push-pull converter will be described as an example of an insulating switching power supply device.
The primary side and the secondary side of the push-pull converter are insulated by a transformer TR1.

  By switching the switching elements SW1 and SW2, the voltage applied to the primary windings Np1 and Np2 of the transformer is controlled, and the output Vo of the DC voltage is output from the secondary winding Ns of the transformer via the rectifying and smoothing circuit U21. Take out.

The switching control means U31 receives the logic signals “0” and “1” from the signal output means U32 and converts the logic signals into pulse signals.
As shown in FIG. 2, the switching control means U31 generates a pulse of frequency F0 when the logic signal from the signal output means U32 is “0”, and outputs a pulse of frequency F1 when the logic signal is “1”. Generate pulse signals POUT1 and POUT2 to the switching elements SW1 and SW2.

  A pulse voltage synchronized with the pulse signals POUT1, POUT2 is generated in the secondary winding Ns of the transformer. The signal extraction unit U22 receives the pulse voltage VNs generated in the secondary winding Ns of the transformer and converts the pulse voltage VNs into a logic signal. The signal extraction unit U22 extracts a signal as a logic signal “0” if the frequency of the pulse voltage VNs is F0 and a logic signal “1” if the frequency of the pulse voltage VNs is F1.

FIG. 3 is a block diagram showing an example of voltage control in the insulated switching power supply device of the present invention, and FIG. 4 is a waveform diagram for explaining the voltage control of FIG.
A difference between the output voltage Vo and the reference voltage Vr is detected by an error amplifier U23 arranged on the secondary side of the insulation type switching power supply device, and the difference signal is fed back to the primary side via the insulation element U24. The output voltage Vo is controlled by the pulse width modulation (PWM) circuit of the switching control means U31 so as to coincide with the reference voltage Vr, and the output voltage Vo becomes a stable voltage that does not depend on the input voltage Vi or the load.

  As shown in FIG. 4, the PWM circuit of the switching control unit U31 controls the on-duty which is the short-circuit time (ton) of the switching elements SW1 and SW2 with the frequencies F0 and F1 being constant. When the output voltage Vo is smaller than the reference voltage Vr, control is performed so that ton becomes longer, and when the output voltage Vo is larger than the reference voltage Vr, control is performed so that ton becomes shorter.

  In this way, by controlling the frequency and on-duty of the pulse signal supplied to the switching element by the switching control means U31, it becomes possible to transmit power and transmit information with one insulating transformer TR1. Therefore, it is not necessary to provide an insulating element specially for transmitting the current.

FIG. 5 is a waveform diagram showing another example of signal transmission of the present invention.
In order to continue outputting the output voltage Vo via the rectifying / smoothing circuit U21, the switching control means U31 needs to output some pulse even when there is no signal from the signal output means U32. For this reason, when the logic signals “0” and “1” are not output from the signal output means U32, the switching control means U31 generates and outputs a pulse signal having a frequency F2 other than the frequencies F0 and F1. .

  Thereby, even if there is no logic signal from the signal output means U32, the power supply device can be controlled normally. Further, if the frequency detected by the signal extraction means U22 is F2, it can be recognized that there is no logic signal, and the beginning and end of the signal sequence of the logic signals “0” and “1” can be clarified.

FIG. 6 is a waveform diagram showing another example of signal transmission of the present invention.
A case will be described in which the signal output means U32 is a processor or the like and generates and outputs data and instructions indicating their attributes.
Switching control means U31 generates a pulse of frequency F0 when the data is “0”, generates a pulse of frequency F1 when the data is “1”, and converts the command to a pulse of a frequency other than F0 and F1. Then, data and a command are output to the switching elements SW1 and SW2 as pulse signals POUT1 and POUT2.

In FIG. 6, the switching control unit U31 generates a pulse of frequency F2 when the command received from the signal output unit U32 is a read command, and generates a pulse of frequency F3 when the command is a write command.
The voltage VNs of the secondary winding Ns of the transformer is followed by a pulse of frequency F3 indicating a write command, followed by a pulse train of address data indicating a place to be written and frequencies F0 and F1 of the data to be written. A pulse train of address data frequencies F0 and F1 indicating a place to be read follows the pulse of the frequency F2 shown.

  By detecting the frequency of the pulse of the voltage VNs generated in the secondary winding Ns by the signal extraction means U22, data and a command can be transmitted using a power transmission transformer.

FIG. 7 is a waveform diagram showing another example of signal transmission of the present invention.
A case where the signal output means U32 is a processor or the like and generates and outputs n-ary data will be described.
The switching control unit U31 converts each of n-ary data into pulses of n frequencies from frequencies F0 to Fn, corresponding to 0 to n of n-ary data, and converts the n-ary data as pulse signals POUT1 and POUT2 as switching elements. Output to SW1 and SW2.

In FIG. 7, pulses having a frequency of F0 to F7 are assigned to data of 0 to 7.
In this way, n-ary data can be transmitted as it is without being converted to binary, so that complicated processing is eliminated and transmission efficiency can be improved.

  Further, the signal output means U32 may output an analog value. In this case, the switching control means U31 generates and outputs a control pulse having a frequency determined according to the level of the analog value.

FIG. 8 is a diagram showing an embodiment in which the insulated switching power supply devices of the present invention are connected in parallel.
The outputs of the insulated switching power supply device of the present invention are connected in parallel via a butt diode. The butt diode prevents the output current from flowing to each power supply device.

By connecting the power supply devices of the present invention in parallel, a multi-bit signal can be transmitted as parallel transmission. In addition, a signal to be transmitted for each power supply device can be determined and transmitted for each role.
Further, the validity of the transmitted signal can be determined by transmitting the same signal in each power supply device and comparing the signal received on the secondary side.

FIG. 9 is a block diagram showing another example of the power supply system of the present invention.
The circuit example at the time of using a half bridge system as an insulation type switching power supply device is shown. Since the signal is transmitted by controlling the switching frequency, the present invention can be applied to converters of other systems such as a full bridge system, a forward system, and a flyback system.

It is a block diagram which shows one Example of this invention. It is a wave form diagram for demonstrating the signal transmission of FIG. It is a block diagram which shows the voltage control example in the insulation type switching power supply device of this invention. It is a wave form diagram for demonstrating the voltage control of FIG. It is a wave form diagram which shows the other example of signal transmission of this invention. It is a wave form diagram which shows the other example of signal transmission of this invention. It is a wave form diagram which shows the other example of signal transmission of this invention. It is a figure which shows the Example which connected the insulation type switching power supply device of this invention in parallel. It is a block diagram which shows the other example of a power supply system of this invention. It is explanatory drawing of the electric power transmission and signal transmission in the conventional insulation type switching power supply device. It is a wave form diagram for demonstrating operation | movement of the conventional insulation type switching power supply device.

Explanation of symbols

Np1, Np2 Primary winding Ns Secondary winding SW1, SW2 Switching element TR1, TR2 Transformer U21 Rectification smoothing circuit U22 Signal extraction means U31 Switching control means U32 Signal output means

Claims (6)

The primary winding side and the secondary winding side are insulated by the transformer, and the voltage applied to the primary winding of the transformer is turned on and off by the switching element, thereby rectifying and smoothing from the secondary winding of the transformer. In an isolated switching power supply device that extracts a DC voltage output through a circuit,
Signal output means for outputting a signal transmitted from the primary winding side to the secondary winding side;
Switching control means for changing the frequency of a control pulse for turning on and off the switching element in accordance with a signal output from the signal output means;
Signal extraction means for extracting a signal output by the signal output means from a pulse voltage induced in the secondary winding of the transformer;
An insulating switching power supply device comprising:   2. The insulation according to claim 1, wherein said signal output means outputs n-ary data, and said switching control means generates and outputs a control pulse having a frequency corresponding to each value of n-ary. Type switching power supply.   3. The signal output means outputs a command indicating data attributes, and the switching control means generates and outputs a control pulse having a frequency determined for each command. Isolated switching power supply.   2. The insulation type according to claim 1, wherein the signal output means outputs an analog value, and the switching control means generates and outputs a control pulse having a frequency determined according to the level of the analog value. Switching power supply.   5. The insulated switching power supply device according to claim 1, wherein the switching control means outputs a control pulse having a predetermined frequency when there is no signal from the signal output means.   6. The insulated switching power supply device according to claim 1, wherein the switching control means adjusts a duty ratio of a control pulse in accordance with an output voltage supplied to a load.

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