JPH04103628U - power transformer equipment - Google Patents

Abstract

(57) [Summary] [Objective] To provide a power transformer device having winding specifications that reduce noise terminal voltage. [Structure] A power transformer device in which a primary winding N _P and a secondary winding N ₂ are wound around a core 2, and a switching element 6 for switching a DC voltage is provided on the side of the primary winding N _P. The winding start end 7 of the primary winding N _P was placed on the switching element 6 side.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is based on power transformer equipment, especially power transformers with excellent noise isolation characteristics. Regarding equipment.

0002

[Conventional technology]

Generally, a DC voltage is switched by a switching element such as a transistor, stepped up or down by a power transformer, and then rectified again to be converted into a DC voltage, which is then used as a power source for circuits in electronic equipment. Most of the power transformer devices used in this type of power supply device have a primary coil N _P wound around a ferrite core 2 called an EI or EE core via a bobbin 3, as shown in FIGS. 1 and 2. It is constructed by winding secondary coils N ₂ , N ₃ (N ₄ ) and a control coil _NB . The designation of the beginning of the primary winding N _P of this power transformer device is shown in FIG.

0003

[Problem that the idea aims to solve]

The winding start of the conventional power transformer device described above is specified for convenience in manufacturing the transformer. It is something that can be done. By the way, in a switching power transformer device, this occurs in the switching section on the primary side. There is a problem that noise is introduced to the secondary side, but this noise is caused by the noise of the transformer. Although it is acknowledged that there are differences depending on the volume specification, the correlation with the volume specification is clear. There wasn't.

0004 This idea was created by focusing on the above problems, and was based on experiments conducted by the inventors. Based on the confirmed results, we have developed a power supply transformer with winding specifications that reduce noise terminal voltage. The purpose is to provide a

[0005]

[Means and actions for solving the problem]

The power transformer device of this invention has a primary winding and a secondary winding wound around the core. and is equipped with a switching element that switches the DC voltage on the primary winding side. In this case, the winding of the primary winding is started from the switching element side. In this power transformer device, the beginning of the primary winding is connected to the transformer on the switching element side. By starting the winding from the terminal, the influence of line capacitance between the primary and secondary windings is reduced. As a result, the noise terminal voltage is reduced, and a power transformer device with excellent noise isolation characteristics can be obtained. It will be done.

[0006]

【Example】

Hereinafter, this invention will be explained in more detail with reference to Examples. FIG. 1 is a connection diagram of a power transformer device showing an embodiment of this invention. This power transformer device 1 includes a primary winding N _P , secondary windings N ₂ , N ₃ , N ₄ , and a control winding N _B wound around a core 2 .

[0007] As shown in FIG. 2, the structure of this power transformer device 1 consists of EE type cores 2, 2. The primary winding N is connected around the central leg 2a via the bobbin 3._P, secondary winding N₂, N₃, N _Four , and further control winding N_BIt is wound in this order. In addition, the primary winding N_Pand secondary winding N₂between, secondary winding N₃/N_Fourand control winding N_P’ to ensure insulation. Ester tape 4 is wound.

However, the above-mentioned connections and structures are not particularly different from conventional ones. The feature of the present invention is that the beginning of the primary winding N _P is placed on the switching element side as shown in FIG. That is, the winding starts from the terminal 7 connected to the collector of the switching transistor 6. A specific circuit example of the primary winding N _P and the switching element is shown in FIG. Here, an FET is used as the switching element 6, and the winding start end 7 of the above-mentioned primary winding N _P is connected to the drain D of the FET 6. The terminal 7 of the primary coil N _P on the side of the switching element 6 changes at a voltage value of, for example, 0 to 600 V in synchronization with the switching frequency.

Therefore, this voltage change flows as a leakage current to the secondary side through the line capacitance C _S shown in FIG. At this time, since the terminal 8 on the power supply side of the primary coil N _P has a constant DC voltage, there is a shielding effect in the primary winding layer facing the secondary winding, and the secondary winding N ₂ has a shielding effect. The leakage current is reduced compared to the specification in which winding starts from the transformer terminal 8 on the power supply side.

0010 Next, we will discuss the power transformer device of the above embodiment and the power transformer device with a conventional configuration. Comparisons of the noise terminal voltages are shown in FIGS. 5 to 8. Figure 5 shows the above example power supply The 0 to 2 MHz characteristics of the transformer device, Figure 6 shows the 0 to 30 MHz characteristics of the same power transformer device. Hz characteristics, Figure 7 shows the power supply where the primary winding starts winding from the transformer terminal on the power supply side. The 0 to 2 MHz characteristics of the transformer, Figure 8 shows the 0 to 30 MHz characteristics of the conventional power transformer device. This is a characteristic of MHz.

[0011] As is clear from these characteristic diagrams, the power transformer device according to the embodiment of the present invention is Compared to the previous model, the noise level attenuation between 100KHz and 12MHz can be confirmed. Ru.

0012

[Effect of the idea]

According to this invention, the primary winding is conventionally configured to start winding from the power supply side. Common mode noise can be reduced at the same cost as a transformer, and the noise filter Since the transformer can be made smaller, it contributes to cost reduction and overall miniaturization of power transformer equipment. It has the effect of giving

[Brief explanation of drawings]

FIG. 1 is a winding connection diagram of a power transformer device according to an embodiment of the present invention.

FIG. 2 is a partial structural sectional view of the power transformer device of the same embodiment.

FIG. 3 is a diagram illustrating the beginning of the primary winding of the power transformer device.

FIG. 4 is a circuit diagram showing connections of the power transformer device.

FIG. 5 is a diagram showing the noise voltage characteristics of the power transformer device of the same embodiment at 0 to 2 MHz.

FIG. 6 is a diagram showing the noise voltage characteristics of the power transformer device of the same embodiment in the frequency range of 0 to 30 MHz.

FIG. 7 is a diagram showing noise voltage characteristics of a conventional power transformer at 0 to 2 MHz.

FIG. 8 is a diagram showing the noise voltage characteristics of a conventional power transformer device from 0 to 30 MHz.

[Explanation of symbols]

2 Core N _P Primary winding N ₂ , N ₃ , N ₄ Secondary winding 6 Switching element

Claims (1)

[Scope of utility model registration request] Claims: 1. A power transformer device comprising a primary winding and a secondary winding wound around a core, and a switching element for switching a DC voltage on the primary winding side; A power transformer device characterized in that winding begins from the switching element side.