JPS602071A - Magnetic control type switching regulator - Google Patents

Abstract

PURPOSE:To simplify the construction, and to reduce the size and weight of a switching regulator by connecting a magnetic control choke coil to the midpoint of the secondary winding of a transformer, and controlling the output by one choke coil. CONSTITUTION:An AC voltage is applied to the primary winding of a transformer 3. Diodes 9, 10 are respectively provided at the terminals of the secondary winding of the transformer 3 to conncet the cathodes of the diodes 9, 10. A DC output is obtained from the midpoint of the secondary winding of the transformer 3 and the connecting points of the cathodes of the diodes 9, 10. The primary winding 281 of a magnetic control reactor 28 is provided at the neutral point of the secondary winding of the transformer 3, the saturated time is controlled by the output of a control circuit 16, thereby controlling the output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetically controlled switching regulator, and particularly to a magnetically controlled switching regulator of a push-pull type or a half abscission type.

[Background of the invention]

FIG. 1 shows an example of the configuration of a push-pull type magnetically controlled switching regulator.

In the figure, resistors 1 and 2 and a winding 3 installed in a transformer 3
3. The circuit composed of 34 is the main switching element 4, 4
This circuit is for self-oscillation, and is well known as the Royer oscillation circuit.

6 is a DC power supply, windings 31 and 32 are primary windings provided in the transformer 3, and windings 35 and 36 are secondary windings.

The output control method using this method is as follows.

When the transistor 4 is turned on, a voltage is applied to the magnetic control reactor 7 with the polarity shown. The magnetic control reactor 7 is a saturable reactor and has a high impedance until it is saturated, so that almost no current flows. When a voltage is applied to the magnetic control reactor 7 in this state, the magnetizing force j advances by 1 and becomes saturated at a certain point. After saturation, the impedance is small and current flows.

When the transistor 4 is turned off, the current flowing through the magnetic control reactor 7 is also cut off, and the current starts flowing from the control circuit 16 through the diode 14, the reactor 7, and the winding 35. At this time, the reactor 7 is magnetized in the opposite direction to when the transistor 4 is turned on. Therefore, depending on the degree of magnetization, the time from when the transistor 4 is turned on until the reactor 7 is saturated can be controlled, and the output can be stabilized. Transistor 5 is cool/
The same operation occurs when the magnet is turned on and a voltage of the polarity shown is applied to the magnetic control reactor 8. The control circuit 16 is a control circuit that detects the output voltage of the switching regulator, and is configured as shown in FIG. 2. In FIG. 2, the diode 17 rectifies the output of the winding 35;
A current is supplied to the capacitor 18 and used as a power source for the control circuit 16. Reference numeral 19 denotes an error amplifier that amplifies the voltage obtained by comparing the reference voltage 20 and the detection signal voltage, and a current corresponding to the output of this amplifier 19 flows to the diode 14.15 via the transistor 23.25. This current becomes a current that magnetizes the reactor 7.8.

As described above, the push-pull system and the half-abscission system require two magnetic control reactors to control the output, which has the drawback of preventing the switching regulator from being made smaller and lighter.

[Purpose of the invention]

An object of the present invention is to provide a magnetically controlled switching regulator that can be configured with only one magnetically controlled reactor.

[Summary of the invention]

The gist of the present invention is that a magnetic control choke coil is connected to the middle point of the secondary winding of a transformer, and all output control is performed with one magnetic control choke coil.

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention.

In the figure, 28 is a reactor for magnetic control, 281 is 1
The next winding, 282, is the reset winding of 28. A voltage is induced in the reactor 28 while the switching element 4.degree. During the non-conducting periods 4 and 5, the output of the control circuit 16 induces a voltage that makes the black circles positive. A period during which a voltage whose polarity is positive as indicated by a black circle in the figure is applied is a reset period of the winding 28. During the reset period, winding 282 carries current from control circuit 16 through diode 40, 282. This current releases the excitation energy stored in 28,
This is a reset mechanism that performs a reset operation.

The number of windings of 281 is tn2st, and the number of windings of 282 is n28
2, if n281 is constant, 0282
In other words, n2B2/12810
The smaller the turns ratio is, the shorter the reset time will be depending on the turns ratio, and the faster the reset operation can be performed.

That is, in a push-pull type or a half abscission type switching regulator, the time ratio in which the winding output voltage is applied to the magnetic control reactor 28 is large;
The time to reset 28 is short compared to the time when transistor 4 or 5 conducts and magnetizes. However, by providing a reset winding in the magnetic control reactor as in this method, the reactor 28 can be reset even if the reset time is short, and the output can be controlled even with - number of magnetic control reactors. becomes possible.

FIG. 4 shows a modification of the embodiment. FIG. 4 shows an example of the configuration of a multi-output switching regulator.

4.5 is the main switching element, 6 is the DC power supply, 30 is the main transformer, 301, 302 is the primary winding, 303, 304 is the secondary winding of output A, 305, 306
is the secondary winding of output B.

Output B is controlled by control circuit 75 to be a constant output.

The control circuit 75 detects the output voltage of output B and inputs it as 8. A pulse signal is generated from the control circuit 75 in response to the detection signal v8, and the switching regulators 4 and 5 are driven via the transformer 50 and the transformer 60, thereby controlling the voltage supplied to the load to be constant.

An example of the configuration of the control circuit 75 is shown in FIG. 76°77.7
8 is a widely used timer.

The timer 76 operates at a constant frequency, and timers 77 and 78 also operate in synchronization with this operation.

However, the timers 77 and 78 perform a simple constant operation of outputting a pulse width corresponding to the output of the error amplifier 79 that amplifies the voltage obtained by comparing the reference voltage 94 and V8.

The operations of the timers 76, 77, and 78 are well known and will therefore be omitted.

When the output voltage becomes higher than a constant voltage by the control circuit 75, the output voltage of the error amplifier 79 becomes high and the output pulse width of the p1 timer 77, 78 becomes narrower, so that the output is held at a constant voltage.

When the output voltage decreases, the voltage is controlled to be constant by performing the operation opposite to that described above.

Through the above operation, even if the load connected to output B changes, the output voltage is maintained at a constant voltage.

However, if output A does not have a circuit that controls the output voltage to a constant level, output A will cause voltage fluctuations called cycloregulation due to load fluctuations on output B and load fluctuations on output A. Magnetic control reactor 28 explained in the diagram
The output voltage is held constant by

FIG. 6 shows another embodiment.

The embodiment shown in FIG. 6 is an application of the present invention to a multi-output switching regulator in which the transformer of the embodiment shown in FIG. 3 is provided with a plurality of secondary windings. The operation of each part is similar to the embodiment shown in FIG. In addition, in the figure, 9 to 11, 40, 70 to 72 are diodes, 12°73 is a choke coil, 13, 74
,83,85゜87.89.91 is a capacitor, 21,
22゜24.80,81,82,84,86,88゜9
0.92.93 is resistance, 501,502°601.60
2 is a winding, and 95.96 is a transistor.

[Effect of enlightenment]

According to the present invention, one magnetic control reactor is provided on the open side.
This reduces the reset current.

Therefore, the power of the control circuit can be reduced.

[Brief explanation of drawings]

Figure i1 is a circuit diagram of a conventional example, Figure 2 is a detailed diagram of Figure 1, Figure 3 is a circuit diagram of one embodiment of the present invention, Figure 4 is a circuit diagram of another embodiment, and Figure 5 is a circuit diagram of another embodiment. Details of Figure 4 3rd Country 3 Fist 4 Figure

Claims (1)

[Claims] 1. Apply an alternating current voltage to the primary winding of the transformer, provide a diode at each terminal of the secondary winding, connect the cathode terminals of the diodes to each other, and connect the secondary winding to the secondary winding. In a switching regulator that obtains a DC output from a connection point between a midpoint and the cathode terminal of the diode, a magnetic control choke coil provided at the neutral point of the secondary winding and non-saturation of the magnetic control choke coil. 1. A magnetically controlled switching regulator comprising means for obtaining a constant output through full time control. 2. The magnetically controlled switching regulator according to claim 1, wherein the magnetically controlled choke coil is provided with a reset winding.