JPH0537669Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a DC stabilized power supply device using a switching regulator. This invention relates to improvements in transmission circuits for transmitting data.

(Prior Art) FIG. 6 is a configuration and connection diagram showing an example of a conventional DC stabilized power supply device. In the figure, CV is DC/
In a DC converter, transformer T and input DC voltage
Consists of a switch element _Q1 that turns Ei on and off and applies it to the primary winding _n1 , and a rectifier and smoothing circuit SM that rectifies and smoothes the pulse output generated in the secondary winding _n2 to obtain an output DC voltage Eo. . For CNT, the output DC voltage Eo is
A control circuit that controls the on/off state of switch element _Q1 so that the output DC voltage is maintained at a constant value through a transmission circuit FC that includes a signal isolation transformer TF.
A signal Vf related to Eo is input.

In the transmission circuit FC, R ₁ and R ₂ are resistors that divide the output DC voltage, OP1 is an operational amplifier that detects the difference between the divided voltage Vd and the reference voltage VR, and Q ₂ is a transformer that responds to the output of the operational amplifier OP1. A transistor that regulates the current flowing through the primary winding of the TF,
D ₄ and C ₂ are diodes and capacitors that rectify and smooth the secondary winding output of the transformer TF, and the rectified and smoothed voltage Vf is applied as a control signal to the control circuit CNT.

Here, the signal isolation transformer TF is configured such that a winding _n3 is provided in the transformer T of the DC/DC converter CV, and excitation energy is supplied from the winding n3.

(Problems to be Solved by the Invention) In the conventional device having such a configuration, it is necessary to separately provide the winding _n3 in the transformer T, which poses problems in terms of the manufacturability and cost of the transformer T. Furthermore, the transistor _Q2 has problems such as the need to have a wide operating range in order to cope with changes in the magnitude of the input DC voltage Ei.

The present invention was devised in view of these problems, and its purpose is to realize a DC stabilized power supply device with a simple configuration without adding unnecessary windings to the transformer T. .

(Means for Solving the Problems) FIG. 1 is a basic configuration block diagram of the device of the present invention. In the figure, CV is a DC/DC converter that inputs DC voltage Ei, and CNT is a DC/DC converter that receives a control signal related to the output DC voltage Eo of DC/DC converter CV so that DC voltage Eo is maintained at a constant value. Turn on the switch element in the DC converter,
Control circuit that controls off, FC is output DC voltage Eo
This is a transmission circuit for providing control signals related to the control circuit CNT. In this transmission circuit,
TF is a signal isolation transformer, S ₁ is a switch driven by the output signal obtained from the secondary winding of the transformer in the DC/DC converter, and is connected to one end of the primary winding n ₁₁ of the signal isolation transformer TF. and drives the signal isolation transformer TF. VS is a variable voltage/current source connected to the other end of the primary coil _n11 of the signal isolation transformer TF, and its magnitude is equal to the output DC voltage Eo
changes in relation to

(Function) The signal isolation transformer TF is activated by switch _S1 .
Driven in synchronization with the DC/DC converter CV,
A signal related to the output DC voltage Eo applied to the primary winding _N11 is transmitted to the control circuit CNT via the signal isolation transformer TF.

(Embodiment) FIG. 2 is a configuration and connection diagram showing an embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals.

In the transmission circuit FC, R ₁ and R ₂ divide the output DC voltage Eo of the DC/DC converter CV, and
The resistor _U1 that obtains V _a is an error amplifier that compares this divided voltage V _a with a reference voltage (reference voltage) VR and outputs the error voltage ε. Its output terminal is
It is connected to one end of the primary winding _n11 of the signal isolation transformer TF. Switch _S1 uses a transistor here, and has a DC/DC converter at its base.
A voltage obtained by dividing the CV secondary winding output Es ₁ by resistors R ₃ and R ₄ is applied. The output of the secondary winding n ₂₂ of the signal isolation transformer TF is connected to the diode D ₃ resistor
rectified and smoothed by R ₅ and capacitor C ₁ ,
It becomes a control signal and is given to the control circuit CNT.

The operation of the apparatus configured as described above will be explained next with reference to the operational waveform diagram in FIG.

When the DC/DC converter CV operates, Part 2
The next winding _n2 receives a pulse signal as shown in Figure 3a.
Es ₁ is output. This pulse signal is a diode
It is rectified by D ₁ and D ₂ , and the chiyoke coil CH,
It is smoothed by the capacitor C ₀ and becomes the output DC voltage Eo. This output DC voltage Eo is determined by the resistance R ₁ ,
The voltage is divided by R ₂ , and the error amplifier U ₁ amplifies the difference between this divided voltage V _a and the reference voltage VR. This error amplifier U ₁ constitutes a variable voltage source that outputs an error ε between V _a and VR.

On the other hand, the pulse signal generated in the secondary winding _n2 is
The voltage is divided into R ₃ and R ₄ and turns the switch element S ₁ on and off. For this reason, 1 of the signal isolation transformer TF
The output voltage ε of the error amplifier U ₁ is applied to the next winding n ₁₁ in synchronization with the on/off of the switch element S ₁ . Figure 3b shows the switch element S and the primary winding.
It shows the change in voltage Vb at the connection point with _n11 .

The signal isolation transformer TF is driven by this, and signals are transmitted during the off period of the switch _S1 , and the secondary winding _n22 has a large voltage corresponding to the error voltage ε, as shown in FIG. 3C. A pulse signal _Vc of 300 m is output. This pulse signal V _c is connected to the diode D ₃ ,
It is rectified and smoothed by a resistor _R5 and a capacitor _C1 to become a control signal Vf, which is applied to a control circuit CNT.

The control circuit CNT is configured such that the control signal Vf becomes zero, that is, the input terminal voltage of the error amplifier _U1 becomes zero (V _a
= VR), and the switch element _Q1 in the DC/DC converter CV is turned on and off so that the output DC voltage Vo is maintained at a constant value.

The DC stabilized power supply device configured in this way is
The signal isolation transformer is driven by the switch _S1 , which turns the control signal transmission on and off by the output of the secondary winding _n2 , which is already in the transformer T. There is no need to provide a special winding.

FIG. 4 is a configuration and connection diagram showing another embodiment of the present invention. In this embodiment, a transistor Q ₂ is connected to the output terminal of the error amplifier U ₁ to output a current b corresponding to the error between the divided voltage Va and the reference voltage _VR .
and transistor _Q2 constitute a variable current source.

FIG. 5 is an operational waveform diagram of the device shown in FIG. 4.
The DC/DC converter is driven, and the two of the transformer T
When a pulse signal as shown in a is output to the secondary winding _n2 , the switch _S1 turns on and off, and the potential Vb at one end of the primary winding _n11 of the signal isolation transformer TF becomes as shown in b. , this transformer is driven. As a result, the primary winding _n11 has an error ε as shown in c.
A current 1b flows that gradually rises depending on the magnitude of and eventually saturates. d indicates the transmission energy (shaded area) in this case, which is expressed as 1/2·LIb ² ·f. Here, L is the inductance of the primary winding _n11 of the signal isolation transformer TF, and L is the driving frequency.

A pulse signal as shown in e is generated in the secondary winding _n22 of the signal isolation transformer TF, and is rectified and smoothed.
It becomes a control signal and is applied to the control circuit CNT.

In this embodiment, the error signal is transmitted as a current signal, and by operating the signal isolation transformer TF in saturation, its inductance L can be small, so power consumption can be further reduced. .

In each of the above embodiments, the signal for driving the switch _S1 was obtained from one end of the secondary winding _n2 of the transformer T, but in FIG.
It may also be obtained from the common connection point P ₁ of the rectifier diodes D ₁ and D ₂ .

(Effects of the invention) As explained in detail above, the present invention uses the winding output already provided in the transformer in the DC/DC converter to drive the signal isolation transformer. It is possible to provide a DC stabilized power supply device with a

[Brief explanation of the drawing]

Figure 1 is a basic configuration block diagram of the device of the present invention, Figure 2 is a configuration and connection diagram showing one embodiment of the invention, Figure 3 is its operating waveform diagram, and Figure 4 is another embodiment of the invention. FIG. 5 is an operational waveform diagram showing an example, and FIG. 6 is a configuration and connection diagram of a conventional device. CV...DC/DC converter, CNT...control circuit, FC...transmission circuit, TF...signal isolation transformer, _S1 ...switch, VS...voltage/current source,
VR...Reference voltage.

Claims (1)

[Claims for Utility Model Registration] A DC/DC converter and a DC/DC converter configured to receive a control signal related to the output DC voltage Eo of the DC/DC converter so that the output DC voltage Eo is maintained at a constant value. Control circuit CNT to control
and a transmission circuit FC for giving a signal related to the output DC voltage Eo to a control circuit, the transmission circuit comprising: a secondary winding of the main transformer of the DC/DC converter; A switch S1 that turns on and off according to the output, a signal isolation transformer TF that is driven by the on and off of this switch, and a signal isolation transformer TF that connects the output current voltage Eo and reference voltage VR to the primary winding of this signal isolation transformer. A variable voltage source or variable current source U1, Q2 that provides a voltage or current signal that changes in relation to the difference, and a voltage signal obtained by rectifying and smoothing the output of the secondary winding of the signal isolation transformer. A DC stabilized power supply device, characterized in that it is applied to the control circuit to control ON/OFF of a switch element in a DC/DC converter.