JP6455368B2 - Active clamp forward type DC-DC converter circuit - Google Patents

Description

  The present invention relates to an active clamp forward type DC-DC converter circuit.

  An active clamp forward type DC-DC converter circuit having a switching circuit on the primary side of the transformer and a rectifier circuit on the secondary side of the transformer is known. For example, an active clamp forward type DC-DC converter circuit disclosed in Patent Document 1 is known.

Japanese Patent No. 2743869

  However, in the conventional active clamp forward type DC-DC converter circuit, ringing occurs in the rectifier circuit due to parasitic capacitance or leakage inductance on the secondary side of the transformer, and radio noise in the ringing frequency band is generated due to the influence.

  An object of one aspect of the present invention is to provide an active clamp forward type DC-DC converter circuit that suppresses ringing generated in a rectifier circuit provided on the secondary side of a transformer.

An active clamp forward type DC-DC converter circuit according to one embodiment of the present invention includes a transformer, a switching circuit on the primary side of the transformer, and a rectifier circuit on the secondary side of the transformer. And, in the transformer, at least one of the winding drawn from the primary winding and the winding drawn from the secondary winding between the primary winding and the secondary winding of the transformer other than the drawn portion In order to avoid contact with the primary and secondary windings .

  Further, the primary winding is provided on one side of the insulating plate, the secondary winding is provided on the other side of the insulating plate, and the conductor is provided between the primary winding and the secondary winding.

  Ringing generated in the rectifier circuit provided on the secondary side of the transformer can be suppressed.

It is a figure which shows one Example of an active clamp forward type DC-DC converter circuit. It is a figure which shows one Example of the structure of a transformer. It is a figure for demonstrating suppression of ringing. It is a figure which shows one Example of the circuit of the modifications 1-3. It is sectional drawing which shows one Example of the modification 4.

Hereinafter, embodiments will be described in detail with reference to the drawings.
<Embodiment 1>
FIG. 1 is a diagram showing an embodiment of an active clamp forward type DC-DC converter circuit. The active clamp forward DC-DC converter circuit of FIG. 1 includes a transformer T, a switching circuit 1 provided on the primary side of the transformer T, and a rectifier circuit 2 provided on the secondary side of the transformer T.

Connection of the switching circuit 1 will be described.
One terminal (positive terminal) of the DC power source P and one terminal of a capacitor C1 (a capacitor used for transformer reset) are connected to one terminal of the primary winding N1 of the transformer T. The other terminal of the primary winding N1 of the transformer T has one terminal (drain) of the switch element Q1 (main switch element) and one terminal (source) of the switch element Q2 (auxiliary switch element used for transformer reset). And are connected. The other terminal (drain) of the switch element Q2 is connected to the other terminal of the capacitor C1. The other terminal (source) of the switch element Q1 is connected to the other terminal (negative electrode terminal) of the DC power supply P.

  In FIG. 1, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are used as the switching elements Q1 and Q2. However, the switching elements are not limited to MOSFETs and may be switching semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors). Good. Further, the switching elements Q1 and Q2 are subjected to switching control such as PWM (Pulse Width Modulation) control by a control circuit (not shown). A control signal (ON / OFF signal) for controlling driving and pause is input from the control circuit to the control terminals (gates) of the switch elements Q1 and Q2, and an active clamp forward type DC-DC converter circuit is supplied according to the control signal. A desired output voltage is output. A capacitor used for zero volt switching may be connected in parallel to the switch element Q1.

  Although FIG. 1 shows the switching circuit 1 including the transformer reset circuit, the switching circuit 1 is not limited to the switching circuit 1 shown in FIG. 1, and is a switching circuit (DC-AC conversion circuit) using a switching element. I just need it.

Connection of the rectifier circuit 2 will be described.
One terminal (anode) of the diode D1 is connected to one terminal of the secondary winding N2 of the transformer T. One end of the coil L1 and one end (cathode) of the diode D2 are connected to the other end (cathode) of the diode D1. One end of the capacitor C2 and one end of the load R are connected to the other end of the coil L1. The other end of the secondary winding N2 of the transformer T is connected to the other end (anode) of the diode D2, the other end of the capacitor C2, and the other end of the load R.

The rectifier circuit is not limited to the rectifier circuit 2 shown in FIG. 1, and may be any rectifier circuit (AC-DC converter circuit) using a diode.
The structure of the transformer T will be described.

  In the transformer T, the winding N3 (conductor) formed by using a part of the primary winding N1 is not in contact with the secondary winding N2 between the primary winding N1 and the secondary winding N2. To place. Further, the winding N3 and the primary winding N1 are arranged so as not to come into contact with any place other than the portion where the winding N3 is drawn from the primary winding N1. By arranging in this way, an eddy current is generated in the winding N3, the high frequency impedance (impedance in the ringing frequency band) is increased, and the flow of current in the high frequency (ringing frequency band) can be suppressed. As a result, ringing generated in the rectifier circuit 2 can be attenuated in a short time, and radio noise due to the influence of ringing can also be reduced.

FIG. 2 is a diagram showing an embodiment of a transformer structure. A transformer T shown in FIG. 2 is a diagram showing a structure of the transformer T shown in FIG.
The core 201 may have a shape that combines an E-shaped core and an I-shaped core, or a shape that combines two E-shaped cores. The core 201 has two square or rectangular holes, and the winding 202 is wound around a central leg provided between the two holes of the core 201. However, the shape of the core 201 is not limited to the shape shown in FIG. Further, the hole of the core 201 may not be square or rectangular. As the material of the core 201, for example, a magnetic material such as ferrite can be considered.

  In the case of the first embodiment, in the winding 202, the primary winding N1, the winding N3, and the secondary winding N2 are arranged in the order shown in FIG. Further, the winding N3 may be wound once or more around the central leg, for example. Note that the winding method and arrangement of the winding N3 may be determined by, for example, experiments or simulations so as to obtain a high-frequency impedance that can attenuate ringing in a short time.

  FIG. 3 is a diagram for explaining suppression of ringing. 3A and 3B, the vertical axis indicates the voltage of the diode D2. Time is shown on the horizontal axis. 3A shows a voltage waveform of the conventional ringing, and B of FIG. 3 shows a voltage waveform in which the ringing of the present invention is suppressed. When a conventional transformer is used, as shown in FIG. 3A, the ringing time is T1 (time t0 to t1), and the ringing peak voltage is V1 [V]. However, since B in FIG. 3 is a diagram when the transformer T having the structure shown in FIGS. 1 and 2 is used, an eddy current is generated in the winding N3, and the flow of current at a high frequency is suppressed. The time during which ringing occurs can be shortened to T2 (time t0 to t2) (T1> T2), and the ringing peak voltage can also be attenuated to V2 (V1> V2). As a result, radio noise due to the influence of ringing can be reduced.

Modifications 1 to 4 will be described.
FIG. 4 is a diagram showing an embodiment of the circuits of the first to third modifications.
<Modification 1>
In Modification 1, as shown in FIG. 4A, a winding N4 (conductor) configured by using a part of the secondary winding N2 between the primary winding N1 and the secondary winding N2. Is arranged in a non-contact manner on the primary winding N1. Further, the secondary winding N2 and the winding N4 are also arranged so as not to contact other than the portion where the winding N4 is drawn from the secondary winding N2.

  In the winding 202 in the first modification, the windings N1, N2, and N4 are arranged in the order of the primary winding N1, the winding N4, and the secondary winding N2, respectively. That is, the winding N4 is arranged at the position of the winding N3 shown in FIG. For example, the winding N4 may be wound around the central leg one or more times.

According to the first modification, ringing is attenuated in a short time by generating an eddy current in the winding N4, increasing the high frequency impedance, and suppressing the flow of current at the high frequency. As a result, radio noise due to the influence of ringing can be reduced.
<Modification 2>
In the second modification, as shown in FIG. 4B, a winding N3 (conductor) constituted by using a part of the primary winding N1 between the primary winding N1 and the secondary winding N2, and A winding N4 (conductor) configured by using a part of the secondary winding N2 of the transformer is disposed in a non-contact manner on the primary winding N1 and the secondary winding N2. Further, the primary winding N1 and the winding N3 are also arranged so as not to come into contact with any place other than where the winding N3 is drawn from the primary winding N1. The secondary winding N2 and the winding N4 are also arranged so as not to contact other than the portion where the winding N4 is drawn from the secondary winding N2. Further, the winding N3 and the winding N4 are also arranged in a non-contact manner.

  In the winding 202 in the second modification, the windings N1 to N4 are arranged in the order of the primary winding N1, the winding N3, the winding N4, and the secondary winding N2. Winding N4 is arranged between winding N3 and secondary winding N2 shown in FIG.

According to the second modification, ringing is attenuated in a short time by generating eddy currents in the windings N3 and N4, increasing the high frequency impedance, and suppressing the flow of current at high frequencies. As a result, radio noise due to the influence of ringing can be reduced.
<Modification 3>
In Modification 3, as shown in FIG. 4C, the conductor N5 is disposed between the primary winding N1 and the secondary winding N2 in a non-contact manner on the primary winding N1 and the secondary winding N2. .

  In the winding 202 in the third modification, the windings N1 and N2 and the conductor N5 are arranged in the order of the primary winding N1, the conductor N5, and the secondary winding N2. That is, the conductor N5 is arranged at the position of the winding N3 shown in FIG. However, the conductor N5 is not annular, and is not made to make a round around the central leg.

According to the third modification, ringing is attenuated in a short time by generating an eddy current in the conductor N5, increasing the high-frequency impedance, and suppressing the flow of current at the high frequency. As a result, radio noise due to the influence of ringing can be reduced.
<Modification 4>
In Modification 4, as shown in FIG. 5, a winding N3 (conductor) or a winding 4 (conductor) and an insulator 501 are arranged between the primary winding N1 and the secondary winding N2. FIG. 5 is a cross-sectional view of a transformer T showing an embodiment of the fourth modification. In FIG. 5, the primary winding N <b> 1 is provided on one side of the insulating plate 501 provided in the transformer T, and the secondary winding N <b> 2 is provided on the other side of the insulating plate 501.

  In the winding 202 in the modified example 4, the windings N1 to N3 and the insulating plate 501 are arranged in the order of the primary winding N1, the winding N3, the insulator 501, and the secondary winding N2. The windings N1, N2, and N4 and the insulating plate 501 may be arranged in the order of the primary winding N1, the insulator 501, the winding N4, and the secondary winding N2.

  According to the fourth modification, ringing is attenuated in a short time by generating an eddy current in the winding N3 or the winding N4 to increase the high-frequency impedance and suppress the flow of current at a high frequency. As a result, radio noise due to the influence of ringing can be reduced.

In the fourth modification, the winding N3 may be incorporated in the insulator 501.
Furthermore, in the modified example 4, the primary winding N1 and the secondary winding N2 may be incorporated in the substrate. The primary winding N1 may be formed on the inner layer of the substrate as a wiring pattern, or the primary winding N1 may be taken into the substrate. Also, the secondary winding N2 may be formed in the inner layer of the substrate as a wiring pattern, or the secondary winding N2 may be taken into the substrate. Further, the substrate incorporating the primary winding N1 and the substrate incorporating the secondary winding N2 may be separate substrates.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Switching circuit 2 Rectifier circuit 201 Core 202 Winding 501 Insulation board C1, C2 Capacitor D1, D2 Diode P DC power supply L1 Coil N1 Primary winding N2 Secondary winding N3, N4 Winding N5 Conductor Q1, Q2 Switch element R Load T transformer

Claims (2)

With a transformer,
A switching circuit on the primary side of the transformer;
A rectifier circuit on the secondary side of the transformer;
An active clamp forward type DC-DC converter circuit comprising:
In the transformer, at least one of a winding drawn from the primary winding and a winding drawn from the secondary winding is drawn between the primary winding and the secondary winding of the transformer . An active clamp forward type DC-DC converter characterized by being arranged so as not to contact the primary winding and the secondary winding other than at a place . An active clamp forward type DC-DC converter according to claim 1 ,
The primary winding is provided on one side of the insulating plate,
Active clamp forward type DC-DC converter wherein the secondary winding, characterized in that the al provided on the other surface side of the insulating plate.