CN205845633U - A high-power and small-volume boost inductor and boost circuit - Google Patents

Abstract

The utility model discloses a high-power and small-volume boosting inductor and a boosting circuit. The high-power and small-volume boosting inductor includes a magnetic core, and the magnetic core includes a first E-shaped magnetic core and a second E-shaped magnetic core. Both the first E-shaped magnetic core and the second E-shaped magnetic core include two outer columns and a central column, the first E-shaped magnetic core and the second E-shaped magnetic core are arranged oppositely, and the first E-shaped magnetic core The two outer columns of the magnetic core are in contact with the two outer columns of the second E-shaped magnetic core, and a gap is formed between the central column of the first E-shaped magnetic core and the central column of the second E-shaped magnetic core. The two outer columns of the first E-shaped magnetic core and the second E-shaped magnetic core of the utility model are in contact with each other to form a closed-loop magnetic circuit with inductive work, and make full use of the electromagnetic induction of the coil, leaving a gap at the central column. When the number increases, by increasing the gap distance, the inductance is kept constant, and the magnetic saturation can be effectively avoided when the current increases, which is conducive to improving the power of the inductance using the magnetic core.

Description

A high-power and small-volume boost inductor and boost circuit

technical field

The utility model relates to the technical field of inductance, in particular to a high-power and small-volume step-up inductor and a step-up circuit.

Background technique

The existing backlight boost inductor uses a ring inductor, which is large in size and high in cost, and it is not easy to realize automatic production of machines, and the boost energy is stored in the magnetic core, which is easy to saturate and make the temperature higher; while the I-shaped inductor is used , although the volume is small and the cost is low, but the boost energy is stored in the magnetic core, there is no closed-loop magnetic circuit, the power that the magnetic core can achieve is small, and the temperature rise is high.

Utility model content

The utility model provides a high-power and small-volume step-up inductor and a step-up circuit, which have small volume, low cost, high realized power and good EMC performance.

The utility model adopts the following technical solutions:

The utility model provides a high-power and small-volume step-up inductor, which includes a magnetic core, the magnetic core includes a first E-shaped magnetic core and a second E-shaped magnetic core, and the first E-shaped magnetic core and the second E-shaped magnetic core The magnetic cores all include two outer columns and a middle column, the first E-shaped magnetic core and the second E-shaped magnetic core are arranged oppositely, and the two outer columns of the first E-shaped magnetic core and the second E-shaped magnetic core The two outer legs of the core are in contact, and a gap is formed between the middle leg of the first E-shaped magnetic core and the middle leg of the second E-shaped magnetic core.

Further, a skeleton is also included, the skeleton includes a beam for winding a coil, a through hole is provided through the beam, and the central pillars of the first E-shaped magnetic core and the second E-shaped magnetic core are connected from the beam The opposite ends of the two ends are inserted into the through hole.

Preferably, glue is injected into the gap.

Specifically, the two ends of the crossbeam are respectively provided with side walls for preventing the winding from falling out of the crossbeam.

Specifically, brackets for supporting the first E-shaped magnetic core and the second E-shaped magnetic core are symmetrically provided on the lower sides of both ends of the beam.

Specifically, the lower ends of the brackets are respectively provided with pins.

Preferably, an EMC shielding layer is provided outside the skeleton, the first E-shaped magnetic core and the second E-shaped magnetic core.

Specifically, the coil is wound with multi-strand wires.

In the second aspect, the utility model provides a boost circuit, including the above-mentioned high-power and small-volume boost inductor, a PWM controller, a MOS switch circuit, a first capacitor, a second capacitor and a diode; the first capacitor The positive pole of the power supply is connected, and the negative pole is grounded; the input pin of the high-power small-volume boost inductor is connected to the power supply, the output pin is connected to the drain of the MOS switch circuit, and the ground pin is grounded; The source of the MOS switch circuit is grounded, and its gate is connected to the PWM controller; the anode of the diode is connected to the drain of the MOS switch circuit, and its negative pole is connected to the positive pole of the second capacitor, and the second capacitor The negative pole is grounded.

Specifically, the MOS switch circuit is an NMOS switch tube.

The technical scheme provided by the utility model brings the following beneficial effects:

The two outer columns of the first E-shaped magnetic core and the second E-shaped magnetic core are in contact with each other, forming a closed-loop magnetic circuit with inductive work, making full use of the electromagnetic induction of the coil, and leaving a gap at the central column. When the number of turns of the coil increases , by increasing the gap distance, the inductance is kept constant, and magnetic saturation can be effectively avoided when the current increases, which is beneficial to increase the power used by the inductance using the magnetic core.

Description of drawings

In order to illustrate the technical solution in the utility model more clearly, the accompanying drawings that need to be used in the description of the utility model will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the utility model. For those skilled in the art, other drawings can also be obtained according to the content of the utility model and these drawings without any creative effort.

Fig. 1 is a structural schematic diagram of the magnetic core of the high-power and small-volume boost inductor provided by the utility model.

Fig. 2 is a front view of the magnetic core of the high-power and small-volume boost inductor provided by the utility model.

Fig. 3 is a schematic structural view of the skeleton of the high-power and small-volume boost inductor provided by the present invention.

Fig. 4 is a circuit schematic diagram of the boost circuit provided by the utility model.

Fig. 5 is a schematic view looking up along X-X' section in Fig. 3 provided by the utility model.

detailed description

In order to make the technical problem solved by the utility model, the technical solution adopted and the technical effect achieved clearer, the technical solution of the utility model will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiment is only the utility model. Some of the embodiments are novel, but not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present utility model.

Fig. 1 is a structural schematic diagram of the magnetic core of the high-power and small-volume boost inductor provided by the utility model. Fig. 2 is a front view of the magnetic core of the high-power and small-volume boost inductor provided by the utility model. As shown in Figures 1 and 2, the high-power and small-volume boost inductor includes a magnetic core 1, and the magnetic core 1 includes a first E-shaped magnetic core 10 and a second E-shaped magnetic core 11, and the first E-shaped magnetic core 1 Both the magnetic core 10 and the second E-shaped magnetic core 11 include two outer columns 12 and a middle column 13, the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 are arranged oppositely, and the first E-shaped magnetic core The two outer columns 12 of the magnetic core 10 are in contact with the two outer columns 12 of the second E-shaped magnetic core 11, and the central column 13 of the first E-shaped magnetic core 10 and the central column of the second E-shaped magnetic core 11 are in contact with each other. Spaces 14 are formed between 13 .

The magnetic core 1 of the high-power and small-volume step-up inductor provided by the utility model is an E-shaped magnetic core, and the two outer columns 12 of the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 are in contact with each other to form an inductive working The closed-loop magnetic circuit makes full use of the electromagnetic induction of the coil, leaving a gap 14 at the center column 13. When the number of turns of the coil increases, by increasing the distance of the gap 14, the inductance remains constant, and the magnetic field can be effectively avoided when the current increases. Saturation is beneficial to increase the power used by the inductance using the magnetic core.

In this embodiment, the specification of the magnetic core is EF16, and the material is NH2CA or PC47 grade material, which improves the efficiency of the magnetic core. Here, it is only an example to illustrate the specific specifications and materials of the magnetic core, and it is not as a limitation to the present utility model. .

Fig. 3 is a schematic structural view of the skeleton of the high-power and small-volume boost inductor provided by the present invention. As shown in FIG. 3 , the high-power and small-volume boost inductor also includes the skeleton 2 described above. The skeleton 2 includes a crossbeam 20 for winding a coil, and a through hole 200 is provided through the crossbeam 20 . The central pillars 13 of the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 are relatively inserted into the through hole 200 from both ends of the beam 20 .

The skeleton 2 provided by the utility model can be inserted into the automatically driven winding rod in the through hole 200 of the skeleton 2 to automatically carry out winding. After winding the wire, the first E-type magnetic core 10 and the second E-type The central column 13 of the magnetic core 11 is relatively inserted into the through hole 200 from both ends of the beam 20 to realize the machine winding of the coil, which reduces the labor cost of manufacturing a high-power and small-volume boost inductor and improves production efficiency. Moreover, the design of the E-shaped magnetic core makes the high-power small-volume boost inductor effectively avoid the problem of magnetic saturation caused by large magnetic flux, which is conducive to improving the power of the high-power small-volume boost inductor.

Preferably, glue is injected into the gap 14 . Glue is injected into the gap 14 between the central pillars 13, which is beneficial to reduce the working noise of the inductor.

In this embodiment, the two ends of the crossbeam 20 are respectively provided with side walls 21 for preventing the winding from falling out of the crossbeam 20 . The sidewalls 21 at both ends of the beam 20 plus the outer columns of the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 wrap the coil on the beam 20 to seal the coil and increase the service life of the inductor.

Specifically, brackets 22 for supporting the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 are symmetrically provided on the lower sides of both ends of the beam 20 . The structure of the bracket 22 matches the structure of the first E-type magnetic core 10 and the second E-type magnetic core 11, so that the first E-type magnetic core 10 and the second E-type magnetic core 11 are inserted into the through hole 200 of the beam 20 , it can be stuck on the bracket 22, making the inductance structure stronger and more stable.

Specifically, the lower ends of the brackets 22 are respectively provided with pins 23 . Pins are set at the lower end of the bracket 22 for easy use. Preferably, since the two rows of pins of the inductor are symmetrical, in order to avoid mis-insertion when inserting the inductor, the pins of the two rows are set in an asymmetrical form, that is, the pins are designed to be fool-proof, and it is more convenient to use.

Preferably, the skeleton 2 , the first E-shaped magnetic core 10 and the second E-shaped magnetic core 11 are provided with an EMC shielding layer on the outside. Specifically, the EMC shielding layer is grounded, and the magnetic core and the coil are all wrapped with copper foil, which improves the EMC performance of the high-power small-volume boost inductor.

Preferably, in this embodiment, the coil is wound with multi-strand wires. According to the size of the power, multi-strand coils are used to reduce the skin effect of the wire when the high-frequency alternating current passes through the inductor, and further make the temperature rise lower.

Fig. 4 is a circuit schematic diagram of the boost circuit provided by the utility model. As shown in FIG. 4, the boost circuit includes the aforementioned high-power and small-volume boost inductor L0D2, a PWM controller 30, a MOS switch circuit 40, a first capacitor C0B8, a second capacitor C0B7, and a diode D1. The positive pole of a capacitor C0B8 is connected to the power supply Vin, and its negative pole is grounded; the input pin of the high-power and small-volume boost inductor L0D2 is connected to the power supply Vin, and its output pin is connected to the drain 2 of the MOS switch circuit 40, Its grounding pin is grounded; the source 3 of the MOS switch circuit 40 is grounded, and its grid 1 is connected to the PWM controller 30; the anode of the diode D1 is connected to the drain 2 of the MOS switch circuit 40, Its negative pole is connected to the positive pole of the second capacitor C0B7; the negative pole of the second capacitor C0B7 is grounded.

The working principle of the boost circuit provided by the utility model is: after the PWM controller 40 controls the MOS switch circuit 40 to be turned on, the input voltage of the power supply Vin flows through the high-power and small-volume boost inductor L0D2 to charge the high-power and small-volume boost inductor L0D2 , the diode D1 prevents the second capacitor C0B7 from discharging to the ground. Since the input is DC, the current on the inductor increases linearly at a certain ratio. This ratio is related to the size of the high-power and small-volume boost inductor L0D2. As the current of the high-power and small-volume boost inductor L0D2 increases, the high-power and small-volume boost Energy is stored in the inductor L0D2; when the PWM controller 40 controls the MOS switch circuit 40 to cut off, the high-power and small-volume boost inductor L0D2 starts to charge the second capacitor C0B7 through the diode D1, and the voltage across the second capacitor C0B7 rises. When the voltage is already higher than the input voltage, the boost is complete.

The inductance of the boost circuit remains constant, and magnetic saturation can be effectively avoided when the current increases, and the boost effect is better.

Specifically, the MOS switch circuit 40 is an NMOS switch transistor Q1B0.

The high-power and small-volume step-up inductor provided by the utility model can be designed with reference to the examples of the following design methods.

Fig. 5 is a schematic diagram looking upwards of the cross-section along XX' in Fig. 3 provided by the present invention. As shown in Figure 5, known conditions: input voltage Vinmin=42V, operating frequency f=140kHz, effective cross-sectional area of the magnetic core Ae=20mm ² , saturation magnetic flux density Bmax=0.4T, linear current density Im=8A/mm2, Maximum output voltage Voutmax=60V, inductance L=100uH, output current Iout=1.2A, efficiency η=0.9, window length a=3.4mm, height h=10mm.

First, find the duty cycle: On time

According to the on-time Ton, the maximum inductor current in CCM mode is obtained as:

$\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2.355</span>}\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ;</span>$

According to the maximum current ILpeak of the inductor, the number of turns of the coil is obtained: by magnetic induction It is known that the larger the number of coil turns N, the smaller the value of the magnetic induction intensity B, and the less likely the magnetic core will be saturated. According to the actual winding space of the magnetic core window and the temperature rise test, the actual number of coil turns N'=50 turns;

After selecting the frame, evaluate the wire diameter, as shown in Figure 5, the window area Aw=a·h=34mm ² , and then calculate the maximum cross-sectional area of the wire diameter based on 1.15 times the window area Aw: In order to meet the temperature rise requirement, according to the line current density, the line area of electrical requirement is: It can be seen from this that if S line 1<Smax, then 50 turns can be wound under this window. The coil used is a multi-strand wire. Here, a multi-strand wire with a wire diameter of 0.1mm is used, and the number of multi-strand wires is calculated according to the required area. When the inductor passes high-frequency alternating current, the skin effect of the wire is reduced, and the temperature rise is further reduced. In addition, because the coil needs to be wrapped with tape, 25 coils are actually used, and the temperature rise is good according to the experiment. Due to the limitation of the winding process, the existing toroidal inductor can only use a thicker single-strand wire, which is affected by the skin effect and the utilization efficiency of the wire area is low.

Finally, verify that the magnetic saturation

Magnetic induction: (100℃,, Bmax: PC44: 0.4T, PC40: 0.39T), it can be concluded that this design meets the margin of 0.6 for magnetic saturation.

The above content is only a preferred embodiment of the present utility model. For those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation and scope of application. The content of this specification should not be understood as Limitations on the Invention.

Claims (10)

1. A high-power small-volume boost inductor, comprising a magnetic core, characterized in that the magnetic core comprises a first E-shaped magnetic core and a second E-shaped magnetic core, and the first E-shaped magnetic core and the second E-shaped magnetic core Each E-shaped magnetic core includes two outer columns and a middle column, the first E-shaped magnetic core and the second E-shaped magnetic core are arranged oppositely, and the two outer columns of the first E-shaped magnetic core and the second E-shaped magnetic core The two outer columns of the E-shaped magnetic core are in contact, and a gap is formed between the central column of the first E-shaped magnetic core and the central column of the second E-shaped magnetic core. 2. The high-power and small-volume boost inductor according to claim 1, characterized in that it also includes a skeleton, the skeleton includes a crossbeam for winding a coil, a through hole is provided through the crossbeam, and the first The E-shaped magnetic core and the center post of the second E-shaped magnetic core are relatively inserted into the through hole from both ends of the beam. 3. The high-power and small-volume boost inductor according to claim 2, characterized in that glue is injected into the gap. 4. The high-power and small-volume boost inductor according to claim 2, characterized in that, the two ends of the crossbeam are respectively provided with side walls for preventing the winding from falling out of the crossbeam. 5. The high-power and small-volume boost inductor according to claim 4, characterized in that, the lower sides of both ends of the beam are symmetrically provided with supports for supporting the first E-shaped magnetic core and the second E-shaped magnetic core. stand. 6 . The high-power and small-volume boost inductor according to claim 5 , wherein the lower ends of the brackets are respectively provided with pins. 7. The high-power and small-volume boost inductor according to claim 6, wherein an EMC shielding layer is provided on the outside of the skeleton, the first E-shaped magnetic core and the second E-shaped magnetic core. 8 . The high-power and small-volume boost inductor according to claim 3 , wherein the coil is wound with multi-strand wires. 9. A boost circuit, characterized in that it comprises a high-power and small-volume boost inductor as claimed in any one of claims 1 to 8, a PWM controller, a MOS switch circuit, a first capacitor, a second capacitor and a diode ; The positive pole of the first capacitor is connected to the power supply, and its negative pole is grounded; the input pin of the high-power and small-volume boost inductor is connected to the power supply, and its output pin is connected to the drain of the MOS switch circuit, and its grounding The pin is grounded; the source of the MOS switch circuit is grounded, and its gate is connected to the PWM controller; the anode of the diode is connected to the drain of the MOS switch circuit, and its cathode is connected to the positive pole of the second capacitor , the negative electrode of the second capacitor is grounded. 10. The boost circuit according to claim 9, wherein the MOS switch circuit is an NMOS switch tube.