JPS6236367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the characteristics of a magnetic amplifier system as one of the constant voltage systems of a switching regulator.

An example of this type of switching regulator is shown in FIG. In the figure, 1 is the switching element, 2 is the main transformer, 3; 4 is 1 of the main transformer 2.
These are the next winding and the secondary winding. 5 is a saturable reactor, 6 is a rectifier circuit, 7 is a constant voltage control circuit, 8
a; 8b is a DC output terminal.

Next, the operation of this circuit will be explained.

A pulse-like voltage is induced in the secondary winding 4 of the main transformer 2 by turning on and off the switching element 1 connected to the primary winding 3 to which a DC voltage is applied. This voltage passes through the saturable reactor 5, a rectifier circuit, and appears as a DC voltage at the output terminals 8a; 8b. At this time, the saturable reactor 5 reaches the saturation point A in FIG. 4a due to the positive pulse current i ₁ and returns to the Br point when i ₁ becomes zero. The negative pulse current i ₂ is changed by the control circuit 7 in approximately inverse proportion to the set value of the output DC voltage. That is, the negative pulse current _i2 is a control current, and as this value increases, the operating point to be reset gradually shifts from point B to point C. When i ₂ increases and the operation between point C and point A is repeated, the impedance of the saturable reactor is at its maximum and the voltage drop is also at its maximum.
The magnetic amplifier method is a method in which the voltage drop due to the saturable reactor is changed by the control current i ₂ and the output DC voltage is kept constant.

An important design issue for this system is the selection of the material for the saturable reactor. As for material performance, (i)
(ii) The residual magnetic flux Br in Figure 4 a is large;
It is required that the coercive force Hc be small, and (iii) that the plate be as thin as possible. Until now, 50% Ni-based permalloy has been the mainstream as a material that satisfies the above performance. As shown in FIG. 2, this type of magnetic core has a toroidal shape in which a thin plate of about 25 μm is spirally wound. This is heat-treated at a high temperature of about 1000°C while it is in a spiral shape, so MgO is applied to the surface by electrophoresis or the like before forming it into a spiral shape. This ultimately becomes an insulator between the upper and lower layers of the spiral permalloy plate, and serves to reduce eddy current loss during high frequency operation. The magnetic core is housed in a toroidal bobbin such as 10 as shown in FIG. 3, and is designed so that stress during winding by the winding 11 is not directly transmitted to the magnetic core. The B-H curve of this type of material is Hc = 0.1 Oe, as shown in Figure 4a, but it is a material that is sufficiently practical up to several KHz. However, the frequency of the switching regulator ranges from several tens of kilohertz to several
As the frequency increased to 100KHz, iron loss increased significantly and it became impossible to prevent severe temperature rises. In addition, it becomes difficult to ignore eddy current loss,
Demand for ultra-thin materials of 15μ or less has become stronger. For this reason, not only has the difficulty in handling during heat treatment etc. become noticeable, but also the cost of the material has increased considerably.

It is an object of the present invention to overcome the limitations of the prior art and provide a switching regulator using a magnetic amplifier system that causes less temperature rise and is easy to assemble.

In order to achieve the above object, the switching regulator of the present invention includes a switching element connected in series to the primary winding of the transformer and periodically intermittent, and a switching element connected in series to the secondary winding of the output of the transformer. A magnetic amplifier method is provided in which the control current of the saturable reactor is controlled by a saturable reactor, a rectifier circuit connected in series with the saturable reactor, and a control circuit for keeping the DC voltage at the output end of the rectifier circuit constant. In the switching regulator used, the composition of the magnetic core for the saturable reactor is expressed as Co _a M _b X _c , where Co is a cobalt element, M is a metal element other than Co,
X represents a nonmetallic element, each with an atomic percent of 50
a, 30b, 30c, and a+b+c=
It is characterized by using a cobalt-based amorphous metal magnetic material of 100%.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 4b is a B-H curve of a 25μ thick amorphous metal magnetic material used in the switching regulator of the present invention. As is clear from this figure, when this material with the composition (〓〓〓〓) ₇₈ Si ₁₃ B ₉ is used as a saturable reactor, Hc is extremely small compared to 50% Ni-based permalloy. It is expected that iron loss will decrease significantly. The amorphous metal magnetic material referred to here is made by injecting a molten liquid with the above composition onto the surface of one or both rolls rotating at high speed and rapidly cooling it.
It refers to something that is instantly created in a spiral shape as shown in Figure 2. Subsequent heat treatment in a magnetic field or ordinary heat treatment is required, but the temperature is at most 300°C to 500°C.
℃ range, which is significantly lower than conventional materials. Therefore, unlike conventional 50% Ni-based permalloy, there is no need for an interlayer insulator to prevent welding, but an insulator may be inserted between the layers to reduce eddy current loss. Generally, the surface of amorphous metal magnetic materials is slightly oxidized during rapid cooling and solidification, so interlayer insulators are not required in many cases. Finally, as with the prior art, it is housed in the toroidal bobbin 10 shown in Fig. 3 and wound to form a saturable reactor, but it is not as sensitive to stress as the conventional product. Including this, the assembly work as a whole becomes extremely simple. Figure 5 shows 50KHz
These are the results of measuring the surface temperature of a saturable reactor operated at a switching frequency of . 14 shows the temperature rise on the surface of the bobbin portion when the conventional 50% Ni-based permalloy is used, and 15 shows the amorphous metal material used in the present invention. As can be seen from this figure, the conventional 25μ thick 50% Ni-based permalloy exceeds a temperature rise of 40°C in about 10 minutes, whereas the 25μ thick amorphous metal magnetic material used in the present invention , it can be seen that the temperature rise can be suppressed to about 1/2 to 1/3 of the former. The main reason for this is that, as shown in the B-H curve of the amorphous metal magnetic material in FIG. 4b, Hc = 0.01 Oe, which is about 1/10 times that of the conventional product. In addition, the specific electrical resistance of amorphous metal magnetic material is 130×
10 ^-6 [Ω-cm] is several times larger than that of 50% Ni-based permalloy, and since a thin oxide coating is created on the surface of amorphous metal, the interlayer resistance when using a wound iron core is Another major reason is that insulation is maintained and eddy current losses are significantly reduced.

As explained above using the embodiments of the present invention,
By using the method of the present invention using an amorphous metal magnetic material, the temperature rise of the saturable reactor can be extremely suppressed, and a highly reliable and highly efficient magnetic amplifier type switching regulator can be realized.

[Brief explanation of the drawing]

Figure 1 is a known circuit diagram, Figure 2 is a known magnetic core shape, Figure 3 is a known saturable reactor shape, and Figure 4 is a known saturable reactor shape.
Figure a shows the characteristics of a known magnetic core, Figure 4b shows the characteristics of an amorphous material used in the method of the present invention, and Figure 5 shows a comparison of the temperature characteristics of the present invention and a known example.

Claims (1)

[Claims] 1. A switching element connected in series to the primary winding of the transformer and periodically intermittent, a saturable reactor connected in series to the secondary winding of the output of the transformer, and further connected in series with the saturable reactor. A switching regulator using a magnetic amplifier method that controls the control current of the saturable reactor by a rectifier circuit and a control circuit for keeping the DC voltage at the output end of the rectifier circuit constant,
The composition of the magnetic core for _the saturable reactor is expressed as Co _a M _b , 30b, 30c
A switching regulator characterized in that it uses a cobalt-based amorphous metal magnetic material in which a+b+c=100.