CN201251985Y

CN201251985Y - Magnetic core of transformer

Info

Publication number: CN201251985Y
Application number: CNU200820301280XU
Authority: CN
Inventors: 张�雄; 杨森林; 任云强; 张耐久
Original assignee: Sichuan Changhong Electric Co Ltd
Current assignee: Sichuan Changhong Electric Co Ltd
Priority date: 2008-06-24
Filing date: 2008-06-24
Publication date: 2009-06-03
Anticipated expiration: 2018-06-24

Abstract

The utility model relates to a pulse transformer, and in particular to a magnetic core of the pulse transformer. The utility model discloses a magnetic core of the pulse transformer, which can further reduce the volume of the magnetic core and reduce the cost. The utility model adopts the technical proposal that a permanent magnet is arranged inside the magnetic core, and the magnetic field direction of the permanent magnet in the magnetic core is opposite to that of the magnetic core when in work. The magnetic core is used for producing a pulse transformer, and can reduce the surplus magnetic induction strength of the magnetic core, and reduces the coercive force of the magnetic core; under the pulse status, higher magnetic induction strength gain and higher pulse magnetic conductivity can be obtained; and under the condition of the same output power and output voltage, the volume of the magnetic core and the pulse transformer product can be reduced, and the weight can be reduced, and the cost of the product can be reduced.

Description

Magnetic core of transformer

Technical field

The utility model relates to pulse transformer, particularly magnetic core of pulse transformer.

Background technology

Pulse transformer by its type of drive, is divided into single end driver and both-end (recommending) driver transformer.During single end driver transformer work, magnetic core is subjected to folk prescription to excitation, and magnetic field in the magnetic core (excitation field) direction does not change.In order to improve the electromagnetic parameter of magnetic core of pulse transformer, also, generally all be provided with air gap in the magnetic core for the ease of the assembling coil windings, most of magnetic cores all have 2～3 place's air gaps.

Based on reducing the electronic product cost, and the needs of miniaturization development trend, more and more high requirement has been proposed for the miniaturization of electronic devices and components.Pulse transformer, particularly the power-type pulse transformer as kickback transformer (FBT), Switching Power Supply output transformer etc., is the very general electronic component of a kind of use, the bigger proportion of occupation ratio in the complete machine cost, its miniaturization development has actual significance.The miniaturization of pulse transformer is subjected to power output and the isoparametric restriction of output voltage, and the former has limited the core volume of pulse transformer and the size in winding wire footpath, and the latter has influence on winding volume (number of turn) size.The limited principal element of conventional power type pulse transformer volume is the volume size of used magnetic core in the market.With FBT is example, its working method belongs to single-ended reverse exciting and encourages formula, owing to be subjected to the restriction of CRT (cathode ray tube) input power, traditional F BT core volume is selected can not be too little, for example: the FBT magnetic core cross-sectional diameter Φ of 29 inches CRT correspondences reaches 14.5mm (magnetic core of different magnetic permeabilitys is slightly variant), cause whole kickback transformer small product size bigger, cost is higher.

The utility model content

Technical problem to be solved in the utility model just provides a kind of magnetic core of pulse transformer, can further dwindle core volume, reduces material usage, reduces cost.

The utility model solve the technical problem, and the technical scheme of employing is, magnetic core of transformer is characterized in that, in described magnetic core permanent magnet is installed, and the excitation field direction of the magnetic direction of described permanent magnet in magnetic core during with described magnetic core work is opposite.

The beneficial effects of the utility model are, can reduce the residual magnetic flux density of magnetic core, reduce the magnetic core coercive force, under pulse condition, can access higher magnetic flux density increment and higher pulse permeability, under same power output and output voltage condition, can dwindle magnetic core and pulse transformer volume, weight reduction reduces product cost.

Description of drawings

Magnetic core work schematic diagram under Fig. 1 pulse condition;

Fig. 2 is the schematic diagram of embodiment 1;

Fig. 3 is the schematic diagram of embodiment 2;

Fig. 4 is the schematic diagram of embodiment 3;

Fig. 5 is that the A of Fig. 4 is to view;

Fig. 6 is the schematic diagram of embodiment 4;

Fig. 7 is the schematic diagram of embodiment 5.

Among the figure: 1 is magnetic core; 2 is the magnetic core air gap; 3 is permanent magnet; 10 excitation field directions when working for magnetic core; 30 is the magnetic direction of permanent magnet.

Embodiment

Below in conjunction with drawings and Examples, describe the technical solution of the utility model in detail.

According to the law of electromagnetic induction: U=N * S * dB/dt 1.1

Wherein:

U: primary winding voltage, the waveform of supposing U are rectangular pulse (t＜0, U=0; 0≤t≤tk, U=U1; T〉tk, U=0);

N: primary umber of turn;

B: magnetic flux density;

S: magnetic core cross-sectional area.

Can be obtained by formula 1.1, (N * S), so magnetic flux density increment Delta B linear growth in time, and when Δ t=tk reach Δ B=U1 * tk/ (N * S) to Δ B=U1 * Δ t/.

Under the consecutive pulses effect, the initial working point of magnetic core rises to the residual magnetic flux density value (B=Br of limit magnetic hysteresis loop, H=0) till, if the magnetic flux density increment is Δ B, then the magnetic flux density in the magnetic core is B3=Br+ Δ B, and during afterwards each end-of-pulsing, original point (B=Br is all got back in the magnetic core working point, H=0), as shown in Figure 1.Among the figure, abscissa is magnetic field intensity H, and Hc is a coercive field strength; Ordinate is a magnetic induction density B, and Bs is a saturation induction density, and Br is a residual magnetic flux density.

In order to estimate the magnetic permeability of whole minor loop, utilize the average pulse magnetic permeability:

μ＝ΔB/μ ₀×ΔH

Wherein:

μ: average pulse magnetic permeability; μ ₀: initial permeability.

Therefore the residual magnetic flux density Br of core material is high more, and possible magnetic flux density increment Delta B is low more, and the average pulse magnetic permeability of minor loop is just more little.

Proportional relation (L ∝ μ * S * N) can learn according to transformer magnetizing inductance L and average pulse magnetic permeability μ, when adopting higher magnetic material of residual magnetic flux density and winding space to be restricted, for the magnetizing inductance that is fixed, must increase the magnetic core cross-sectional area, otherwise, then can reduce the magnetic core cross-sectional area.

The utility model just is being based on above-mentioned principle, employing is at magnetic core (ferrite, ferrocart core, amorphous alloy and silicon steel sheet etc.) the last method that permanent magnet is installed, reduce the magnetic core residual magnetic flux density Br that works under the pulse condition, increase magnetic flux density increment Delta B, and then reduce core volume, reduce product cost.

Embodiment 1

Be illustrated in figure 2 as the output transformer magnetic core of Switching Power Supply, magnetic core 1 adopts soft magnetic material to constitute, and energisation mode is that single-ended reverse exciting is encouraged mode.This routine magnetic core 1 is shaped as " EI " type, and three place's air gaps 2 are arranged in the magnetic circuit, and permanent magnet 3 is installed in the both sides of magnetic core 1 near air gap 2 places.This example is at the one-sided installation permanent magnet 3 of magnetic core 1 and air gap 2.According to test, this mounting means can be obtained better effect---at the same terms (magnetic core initial permeability μ ₀, cross-sectional area S, Transformer Winding number of turn N etc.) under, bigger magnetizing inductance L can be obtained.The magnetic pole of permanent magnet 3 is selected, and the excitation field direction in the time of should making its magnetic direction in magnetic core 1 with magnetic core 1 work is opposite.The value of the parameter of permanent magnet 3 (Hc, Bs) determines that according to the physical circuit parameter the concrete application load of main foundation is chosen, and finally makes magnetic core saturated being as the criterion not occur, and the selection of its overall dimensions should not influence the assembling of transformer.

Embodiment 2

This example is a " UI " type magnetic core, as shown in Figure 3.This magnetic core has two place's air gaps 2, and the polarity that this example has respectively been installed 3, two permanent magnets of a permanent magnet at two place's air gaps is selected, and the excitation field direction in the time of all should working with magnetic core 1 is opposite.

Embodiment 3

This routine transformer is a kickback transformer, and its core shapes as shown in Figure 4.The kickback transformer magnetic core has two place's air gaps, and Transformer Winding is contained on the air gap 2 of magnetic core 1, and another air gap 2 is outside winding, and permanent magnet 3 sticks on this air gap next door by adhesive, as shown in Figure 5.Among Fig. 5, excitation field direction when arrow 10 is worked for kickback transformer, arrow 30 is the magnetic direction of permanent magnet 3 in magnetic core 1.2 permanent magnets of this example are installed in the one-sided of magnetic core 1, the both sides of air gap 2, and the polarity of 2 permanent magnets 2 is opposite, and the excitation field of their magnetic field that produces when working with magnetic core 1 is opposite.

Embodiment 4

Referring to Fig. 6, this routine permanent magnet 3 adopts Embedded mounting means.According to the size and the shape of the permanent magnet of selecting for use 3, on magnetic core 1, dug groove earlier near air gap 2 places, then permanent magnet 3 coated with adhesive are embedded in the above-mentioned groove.This Embedded mounting means does not change the profile of magnetic core, is convenient to the hookup wire ring framework.2 permanent magnets 3 of this example are installed in the both sides of magnetic core 1, air gap 2 one-sided.The polarity of 2 permanent magnets 3 is opposite, and the excitation field of their magnetic field that produces when working with magnetic core 1 is opposite.

Embodiment 5

This routine permanent magnet 3 is installed in the air gap of magnetic core 1, link to each other with magnetic core 1 by adhesive, as shown in Figure 7, permanent magnet 3 should select shape of cross section identical with magnetic core 1 shape of cross section, and the cross-sectional area of the cross-sectional area≤magnetic core 1 of permanent magnet 3, the advantage of this mounting means is that technology is simple, makes things convenient for the assembling of transformer, and the installation of permanent magnet 3 does not influence the face shaping of magnetic core.

Claims

[claim 1] magnetic core of transformer is characterized in that, in described magnetic core permanent magnet is installed, and the excitation field direction the when magnetic direction of described permanent magnet in magnetic core worked with described magnetic core is opposite.
[claim 2] magnetic core of transformer according to claim 1 is characterized in that described magnetic core has air gap, and described permanent magnet installation site is near described air gap.
[claim 3] magnetic core of transformer according to claim 2 is characterized in that, described permanent magnet be installed in described magnetic core and/or air gap one-sided.
[claim 4] magnetic core of transformer according to claim 2 is characterized in that described permanent magnet is installed in the described air gap.
[claim 5] magnetic core of transformer according to claim 4 is characterized in that, described permanent magnet shape of cross section is identical with described magnetic core shape of cross section; Described permanent magnet cross-sectional area≤described magnetic core cross-sectional area.
[claim 6] magnetic core of transformer according to claim 1 is characterized in that described permanent magnet sticks on the described magnetic core.
[claim 7] magnetic core of transformer according to claim 1 is characterized in that described permanent magnet embeds described magnetic core.
[claim 8] magnetic core of transformer according to claim 1 is characterized in that, described transformer is a kickback transformer.
[claim 9] magnetic core of transformer according to claim 1 is characterized in that, described transformer is the Switching Power Supply output transformer.