CN107946045A - A kind of leakage-adjustable inductance flat surface transformer of half turn winding - Google Patents

Abstract

The invention relates to an adjustable leakage inductance planar transformer with a half-turn winding, comprising an E-shaped magnetic core, an I-shaped magnetic core, a primary winding, a secondary winding U1-U2, a rectifier tube D1-D4 and filter capacitors C1-C4; The primary winding is wound on the side column and the center column of the E-shaped magnetic core. The two U-shaped windings of the secondary winding are stacked in the transformer window in reverse. The four ports of the two U-shaped windings of the secondary winding are respectively It is connected to one end of a rectifier tube, the other end of the rectifier tube is connected to one end of a filter capacitor, the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, and the E-type magnetic core and the I-type magnetic core are snapped together. The invention enables the secondary winding to be equivalent to 0.5 turns, so that the number of turns of the primary side can be reduced to half that of one turn of the secondary side, greatly reducing the winding volume and processing difficulty of the transformer, and improving the power density.

Description

An Adjustable Leakage Inductance Planar Transformer with Half Turn Winding

technical field

The invention relates to an adjustable leakage inductance planar transformer with a half-turn winding, which belongs to the field of electromagnetic technology.

Background technique

Due to its small size, planar transformers are often used in applications that require high power density. Among them, the LLC resonant converter is widely used in high-end power supplies and busbar converters because of its easy realization of soft switching, high efficiency and power density.

The LLC resonant converter generally includes a front-stage full-bridge/half-bridge inverter circuit, a resonant capacitor, a resonant inductor, a transformer and a secondary rectification and filtering circuit. LLC resonant converters are often used in applications with large voltage transformation ratios such as 400V to 12V, so the transformer transformation ratio can reach 16 or higher.

For topologies such as the LLC resonant converter, in order to reduce its volume, the transformer generally adopts a planar transformer structure, and the window area of the planar transformer is relatively small. For a transformer with a high transformation ratio, since the secondary side of the conventional winding method is at least one turn, for a transformer with a transformation ratio of 16, the minimum number of turns on the primary side is 16 turns. Excessive number of turns on the primary side may lead to insufficient window area of the transformer to wind a high-side ratio transformer, or affect the space of the secondary winding, making it impossible to use a secondary winding with a larger cross-section, which limits the capacity of the transformer.

Contents of the invention

The invention provides an adjustable leakage inductance planar transformer with a half-turn winding, which is used to solve the problem of too many primary winding turns and insufficient window area of a planar transformer with a large transformation ratio used in LLC resonant converters and other occasions.

The technical solution of the present invention is: an adjustable leakage inductance planar transformer with a half-turn winding, including an E-shaped magnetic core, an I-shaped magnetic core, a primary winding, a secondary winding U1-U2, a rectifier tube D1-D4 and a filter capacitor C1~C4;

The primary winding is wound on the side column and the center column of the E-shaped magnetic core. The two U-shaped windings of the secondary winding are stacked in the transformer window in reverse. The four ports of the two U-shaped windings of the secondary winding are respectively One end of a rectifier tube is connected, the other end of the rectifier tube is connected to one end of a filter capacitor, the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, and the E-type magnetic core and the I-type magnetic core are snapped together.

The four ports of the two U-shaped windings of the secondary winding are respectively connected to one end of a rectifier tube, the other end of the rectifier tube is connected to one end of a filter capacitor, and the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, specifically :

The four ports of the two U-shaped windings are grounded through four rectifier tubes, one end of the filter capacitor C1 and C2 is connected to the center tap T1, the other end of the filter capacitor C1 is connected to one end of the rectifier tube D1, the other end of the filter capacitor C2 is connected to the end of the rectifier tube D2, and the filter One end of capacitors C3 and C4 is connected to center tap T2, the other end of filter capacitor C3 is connected to one end of rectifier tube D3, the other end of filter capacitor C4 is connected to one end of rectifier tube D4; the center taps T1 and T2 of the two U-shaped windings are output in parallel;

or specifically:

The two ports of U1 in the two U-shaped windings are connected in parallel after passing through the rectifier tubes D1 and D2, and the two ports of U2 in the two U-shaped windings are connected in parallel after passing through the rectifying tubes D3 and D4. Connect to the center tap T1, the other end of the filter capacitor C1 is connected to one end of the rectifier tube D1, the other end of the filter capacitor C2 is connected to the end of the rectifier tube D2, one end of the filter capacitors C3 and C4 is connected to the center tap T2, the other end of the filter capacitor C3 is connected to the end of the rectifier tube D3, and the other end of the filter capacitor C3 is connected to the end of the rectifier tube D3. The other end of C4 is connected to one end of the rectifier tube D4, and the center taps T1 and T2 of the two U-shaped windings are used as the ground.

The E-type magnetic core includes side columns M1, M3, and middle column M2; the primary side winding is wound on the side columns M1, M3 and the middle column M2 of the E-type magnetic core, and the winding turns on the side columns and the middle column are changed Distribution to adjust the size of the leakage inductance; the winding direction of the side column is opposite to that of the middle column, and the winding direction of the two side columns is the same.

The change of winding turns distribution on the side column and the middle column to adjust the leakage inductance is specifically: adding one turn of the middle column winding, and correspondingly reducing the two side column windings by one turn, which can ensure that the excitation inductance remains unchanged and reduce the leakage inductance; Adding one turn each of the two side column windings corresponds to reducing one turn of the center column winding, which can increase the leakage inductance while keeping the excitation inductance unchanged.

Two of the secondary windings form a group, and one group can be used alone or multiple groups can be used in parallel.

The rectifier is a diode or a controllable device.

The beneficial effects of the present invention are: adopting a standard magnetic core, a higher transformation ratio can be realized without a fixed value, which reduces the difficulty in processing the winding of a high transformation ratio planar transformer; the reduction in the number of turns enables the use of a winding with a larger cross-section to improve The current carrying capacity of the winding is improved; compared with other half-turn transformers, the structure of the present invention is symmetrical, and each half-winding works alternately to form a complete loop, and there is no magnetic bias problem; the outgoing line is simple and can be easily connected to the rectifying and filtering circuit of the circuit part ; The leakage inductance of the primary winding can be easily debugged, which is convenient for the debugging and realization of the magnetic integration technology; the secondary winding can be equivalent to 0.5 turns, so that the number of turns of the primary side can be reduced to half of that of the secondary side, greatly The winding volume and processing difficulty of the transformer are reduced, and the power density is improved.

Description of drawings

Fig. 1 is the schematic diagram of the half-turn secondary winding structure of the present invention;

Fig. 2 is a schematic diagram of the structure of the primary winding of the adjustable leakage inductance of the present invention;

Fig. 3 is a schematic diagram of assembly of the present invention;

Fig. 4 is the structural representation of embodiment 1;

Fig. 5 is a schematic structural diagram of embodiment 2.

Detailed ways

Embodiment 1: As shown in Figures 1-4, an adjustable leakage inductance planar transformer with a half-turn winding, including an E-shaped magnetic core, an I-shaped magnetic core, a primary winding, a secondary winding U1-U2, and a rectifier tube D1 -D4 and filter capacitors C1~C4;

The primary winding is wound on the side column and the center column of the E-shaped magnetic core, and the two U-shaped windings of the secondary winding are stacked in reverse in the transformer window (stacking can be stacked up and down, or stacked side by side, As shown in Figure 4, they are stacked side by side; for the vertical stacking, W1 and W2 overlap up and down, and W3 and W4 overlap up and down, so they are not shown in the figure), the four ports of the two U-shaped windings of the secondary winding are respectively connected to a rectifier One end of the tube is connected, the other end of the rectifier tube is connected to one end of a filter capacitor, the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, and the E-shaped magnetic core and the I-shaped magnetic core are snapped together. Wherein, the secondary winding Ws includes two identical U-shaped windings, the winding W1 section and the W3 section form one of the U-shaped windings, and an intermediate tap T1 is left in the middle of the W1 and W3 sections; the winding W2 section and the W4 section Another U-shaped winding is formed, and a middle tap T2 is reserved in the middle of the sections W2 and W4; the magnetic core is a standard EI planar transformer magnetic core.

The four ports of the two U-shaped windings of the secondary winding are respectively connected to one end of a rectifier tube, the other end of the rectifier tube is connected to one end of a filter capacitor, and the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, specifically as Figure 4 shows:

The four ports of the two U-shaped windings are grounded through the four rectifier tubes, one end of the filter capacitor C1 and C2 is connected to the center tap T1, the other end of the filter capacitor C1 is connected to the gate of the MOS tube, and the other end of the filter capacitor C2 is connected to the grid of the MOS tube. One end of the capacitors C3 and C4 is connected to the center tap T2, the other end of the filter capacitor C3 is connected to the grid of the MOS tube, and the other end of the filter capacitor C4 is connected to the grid of the MOS tube; the center taps T1 and T2 of the two U-shaped windings are output in parallel.

The E-type magnetic core includes side columns M1, M3, and middle column M2; the primary side winding is wound on the side columns M1, M3 and the middle column M2 of the E-type magnetic core, and the winding turns on the side columns and the middle column are changed distribution to adjust the leakage inductance; the winding direction of the side column is opposite to the winding direction of the middle column, and the winding direction of the two side columns is the same (in Figure 2, the winding direction of the two side columns is clockwise, and the winding direction of the middle column direction is counterclockwise).

Further, it can be set to change the distribution of winding turns on the side column and the middle column to adjust the leakage inductance, specifically: increase one turn of the middle column winding, and correspondingly reduce the two side column windings by one turn, so that the excitation inductance can be guaranteed to remain unchanged At the same time, the leakage inductance is reduced; adding one turn of each of the two side column windings corresponds to reducing one turn of the middle column winding, which can ensure that the excitation inductance remains unchanged and increase the leakage inductance.

Two of the secondary windings form a group, and one group can be used alone or multiple groups can be used in parallel (the situation of one group is shown in FIG. 4 ).

Further, the rectifier is set as a MOS tube controllable device (as shown in FIG. 4 ).

Embodiment 2: As shown in Figures 1-3 and Figure 5, an adjustable leakage inductance planar transformer with a half-turn winding includes an E-shaped magnetic core, an I-shaped magnetic core, a primary winding, and a secondary winding U1-U2, Rectifier tubes D1-D4 and filter capacitors C1~C4;

The primary winding is wound on the side column and the center column of the E-shaped magnetic core. The two U-shaped windings of the secondary winding are stacked in the transformer window in reverse. The four ports of the two U-shaped windings of the secondary winding are respectively One end of a rectifier tube is connected, the other end of the rectifier tube is connected to one end of a filter capacitor, the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, and the E-type magnetic core and the I-type magnetic core are snapped together.

The four ports of the two U-shaped windings of the secondary winding are respectively connected to one end of a rectifier tube, the other end of the rectifier tube is connected to one end of a filter capacitor, and the other end of the filter capacitor is connected to the center tap of the corresponding U-shaped winding, specifically :

The two ports of U1 in the two U-shaped windings are connected in parallel after passing through the rectifier tubes D1 and D2, and the two ports of U2 in the two U-shaped windings are connected in parallel after passing through the rectifying tubes D3 and D4. Connect to the center tap T1, the other end of the filter capacitor C1 is connected to the cathode of the rectifier tube D1, the other end of the filter capacitor C2 is connected to the cathode of the rectifier tube D2, one end of the filter capacitors C3 and C4 is connected to the center tap T2, the other end of the filter capacitor C3 is connected to the cathode of the rectifier tube D3, and the other end of the filter capacitor C3 is connected to the cathode of the rectifier tube D3. The other end of C4 is connected to the cathode of the rectifier tube D4, and the center taps T1 and T2 of the two U-shaped windings are used as the ground;

The E-type magnetic core includes side columns M1, M3, and middle column M2; the primary side winding is wound on the side columns M1, M3 and the middle column M2 of the E-type magnetic core, and the winding turns on the side columns and the middle column are changed Distribution to adjust the size of the leakage inductance; the winding direction of the side column is opposite to that of the middle column, and the winding direction of the two side columns is the same.

Further, it can be set to change the distribution of winding turns on the side column and the middle column to adjust the leakage inductance, specifically: increase one turn of the middle column winding, and correspondingly reduce the two side column windings by one turn, so that the excitation inductance can be guaranteed to remain unchanged At the same time, the leakage inductance is reduced; adding one turn of each of the two side column windings corresponds to reducing one turn of the middle column winding, which can ensure that the excitation inductance remains unchanged and increase the leakage inductance.

Two of the secondary windings form a group, and one group can be used alone or multiple groups can be used in parallel (the situation of one group is shown in FIG. 5 ).

The rectifier is a diode (as shown in Figure 5).

The working principle of the present invention is:

As shown in Figure 4, for the case where the center tap is used as the positive pole, the principle is as follows:

For the primary winding structure with adjustable leakage inductance:

The primary winding is wound on the side column and the center column at the same time, and the contributions of the winding on the side column and the winding on the center column to the leakage inductance are considered respectively. For the winding column on the side column, because relatively more parts of its magnetic force lines are closed by the surrounding air, more magnetic flux leakage is generated, which contributes greatly to the leakage inductance of the primary winding. As for the winding on the central column, because it is surrounded by two side columns, most of its magnetic field lines are closed by the magnetic core, so the magnetic flux leakage generated is relatively small, and the contribution to the leakage inductance of the primary winding is small. Therefore, when we change the turns distribution of the middle column and the side column, the total leakage inductance of the primary winding can be adjusted. At the same time, it should be noted that the magnetic force lines generated by the winding on the center column of each turn are equal to the magnetic force lines generated by each turn of the two side columns.

For a half-turn secondary winding configuration:

When working, the primary side winding is fed with alternating current, which generates alternating magnetic flux in the magnetic core, and the secondary side induces current to offset the magnetic flux generated by the primary side current. Assume that the primary side is fed with a sinusoidal alternating current.

Assuming that in the positive half cycle, the direction of the magnetic field lines in the magnetic column M2 is perpendicular to the surface of the paper and the strength gradually increases, then in order to offset the increase of the magnetic flux, there will be a clockwise current in the winding composed of W2W4, but Since the rectifier tube connected to W4 is in the cut-off state at this time, only the half winding of W2 has current flowing, and the direction is from D3 to tap T1, and the voltage of tap T1 is positive at this time. At the same time, there will be a clockwise current trend in the winding composed of W1W3, but because the rectifier tube connected to W1 is in the cut-off state at this time, only the current flows in the half winding of W3, and the direction is from D2 to the center tap. T2, the tap T2 voltage is positive at this time.

Then in the negative half cycle, the direction of the magnetic force line in the magnetic column M2 is perpendicular to the paper surface and its strength gradually increases. In order to offset the increase of the magnetic flux, there will be a tendency to form an anticlockwise current in the winding composed of W2W4. However, since the rectifier tube connected to W2 is in the cut-off state at this time, only the half winding of W4 has current flowing, and the direction is from D4 to tap T1, and the voltage of tap T1 is positive at this time. At the same time, there will be a counterclockwise current trend in the winding composed of W1W3, but because the rectifier tube connected to W3 is in the cut-off state at this time, only the current flows in the half winding of W1, and the direction is from D1 to the center tap. T2, the tap T2 voltage is positive at this time.

It can be seen from the above analysis that in a complete cycle, each arm of the winding is turned on alternately, which always ensures that the tap T1T2 outputs a positive voltage. At the same time, in each half cycle, the output voltage is the parallel output of two half-turn coils, so the actual voltage of the tap is the voltage induced by the half-turn coil, thus realizing the structure of the half-turn coil.

As shown in Figure 5, for the case where the center tap is used as ground, the principle is as follows:

For the primary winding structure with adjustable leakage inductance:

The primary winding is wound on the side column and the center column at the same time, and the contributions of the winding on the side column and the winding on the center column to the leakage inductance are considered respectively. For the winding column on the side column, because relatively more parts of its magnetic force lines are closed by the surrounding air, more magnetic flux leakage is generated, which contributes greatly to the leakage inductance of the primary winding. As for the winding on the central column, because it is surrounded by two side columns, most of its magnetic field lines are closed by the magnetic core, so the magnetic flux leakage generated is relatively small, and the contribution to the leakage inductance of the primary winding is small. Therefore, when we change the turns distribution of the middle column and the side column, the total leakage inductance of the primary winding can be adjusted. At the same time, it should be noted that the magnetic force lines generated by the winding on the center column of each turn are equal to the magnetic force lines generated by each turn of the two side columns.

For a half-turn secondary winding configuration:

When working, the primary side winding is fed with alternating current, which generates alternating magnetic flux in the magnetic core, and the secondary side induces current to offset the magnetic flux generated by the primary side current. Assume that the primary side is fed with a sinusoidal alternating current.

Assuming that in the positive half cycle, the direction of the magnetic field lines in the magnetic column M2 is perpendicular to the surface of the paper and the strength gradually increases, then in order to offset the increase of the magnetic flux, there will be a clockwise current in the winding composed of W2W4, but Since the rectifier tube connected to W2 is in the cut-off state at this time, only the half winding of W4 has current flowing, and the direction is from T1 to the tap D4. At this time, the tap T1 is the ground, and the cathode voltage of the diode D4 is positive. At the same time, there will be a clockwise current trend in the winding composed of W1W3, but because the rectifier tube connected to W3 is in the cut-off state at this time, only the current flows in the half winding of W1, and the direction is from T2 to the center tap. D1, tap T2 is ground at this time, and the cathode voltage of diode D1 is positive.

Then in the negative half cycle, the direction of the magnetic force line in the magnetic column M2 is perpendicular to the paper surface and its strength gradually increases. In order to offset the increase of the magnetic flux, there will be a tendency to form an anticlockwise current in the winding composed of W2W4. However, since the rectifier tube connected to W4 is in the cut-off state at this time, only the half winding of W2 has current flowing, and the direction is from tap T1 to D3. At this time, tap T1 is ground, and the cathode voltage of diode D3 is positive. At the same time, there will be a counterclockwise current trend in the winding composed of W1W3, but because the rectifier tube connected to W1 is in the cut-off state at this time, only the current flows in the half winding of W3, and the direction is from the center tap T2 to the D2, at this time tap T2 is ground, and the cathode voltage of diode D2 is positive.

It can be seen from the above analysis that in a complete cycle, each arm of the winding is turned on alternately, which always ensures that the tap T1T2 is grounded and the diode cathode voltage is positive. At the same time, in each half cycle, the output voltage is the parallel output of two half-turn coils, so the actual voltage of the cathode of the diode is the voltage induced by the half-turn coil, thus realizing the structure of the half-turn coil.

The specific implementation of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned implementation, and within the knowledge of those of ordinary skill in the art, it can also be made Various changes.

Claims (6)

1. A kind of 1. leakage-adjustable inductance flat surface transformer of half turn winding, it is characterised in that：Including E-type magnetic core, I type magnetic cores, primary side around Group, vice-side winding U1-U2, rectifying tube D1-D4 and filter capacitor C1 ~ C4；

   Primary side winding is wound on the side column and center pillar of E-type magnetic core, and two U-shaped windings of vice-side winding are reversely stacked in transformer In window, four ports of two U-shaped windings of vice-side winding are connected with a rectifying tube one end respectively, the rectifying tube other end with One filter capacitor one end connection, the filter capacitor other end are connected with the centre cap of corresponding U-shaped winding, E-type magnetic core and I type magnetic Core fastens.
2. 2. the leakage-adjustable inductance flat surface transformer of half turn winding according to claim 1, it is characterised in that：The vice-side winding Four ports of two U-shaped windings be connected respectively with a rectifying tube one end, the rectifying tube other end and a filter capacitor one End connection, the filter capacitor other end are connected with the centre cap of corresponding U-shaped winding, are specially：

   The rectifying tube ground connection of four ports four of two U-shaped windings, filter capacitor C1, C2 mono- terminate centre cap T1, filtering Another termination rectifying tube D1 one end of capacitance C1, another termination rectifying tube D2 one end of filter capacitor C2, filter capacitor C3, C4 mono- are terminated Another termination rectifying tube D3 one end of centre cap T2, filter capacitor C3, another termination rectifying tube D4 one end of filter capacitor C4；Two Centre cap T1, T2 Parallel opertation of U-shaped winding；

   Or it is specially：

   It is in parallel after U1 two-ports rectified pipe D1, D2 in two U-shaped windings, the rectified pipe D3 of U2 two-ports in two U-shaped windings, It is in parallel after D4, exported after both parallel connections as cathode；Filter capacitor C1, C2 mono- terminates centre cap T1, and filter capacitor C1 is another One termination rectifying tube D1 one end, another termination rectifying tube D2 one end of filter capacitor C2, filter capacitor C3, C4 one end centre cap Another termination rectifying tube D3 one end of T2, filter capacitor C3, another termination rectifying tube D4 one end of filter capacitor C4, two U-shaped windings Centre cap T1, T2 as ground.
3. 3. the leakage-adjustable inductance flat surface transformer of half turn winding according to claim 1, it is characterised in that：The E-type magnetic core Including side column M1, M3, center pillar M2；Primary side winding is wound on side column M1, M3 and center pillar M2 of E-type magnetic core, change side column, in Umber of turn is distributed to adjust leakage inductance size on column；Direction of winding and center pillar direction of winding are on the contrary, two side column coilings on side column Direction is identical.
4. 4. the leakage-adjustable inductance flat surface transformer of half turn winding according to claim 3, it is characterised in that：The change side Umber of turn, which is distributed to adjust leakage inductance size, on column, center pillar is specially：Increase by a circle center pillar winding, it is corresponding reduce two side columns around Each circle of group, can guarantee that magnetizing inductance is constant while reduces leakage inductance；Increase each circle of two side column windings, it is corresponding reduce center pillar around One circle of group, can guarantee that and increase leakage inductance while magnetizing inductance is constant.
5. 5. the leakage-adjustable inductance flat surface transformer of half turn winding according to claim 1, it is characterised in that：The vice-side winding Two are one group, can one group of exclusive use or multigroup used in parallel.
6. 6. the leakage-adjustable inductance flat surface transformer of half turn winding according to claim 1, it is characterised in that：The rectifying tube is Diode or controllable devices.