JPH067222U - Power transformer roaring prevention circuit - Google Patents

Abstract

(57) [Summary] [Objective] The purpose of the present invention is to effectively reduce the roaring noise of the power transformer, and the number of parts to be inserted in the primary circuit side is also reduced compared to the conventional roaring noise prevention circuit, which is excellent in safety. It is to provide a roaring prevention circuit for a power transformer. A diode group D formed by reversely connecting diodes D1 and D2 to each other is connected to a primary winding side T1 of a power transformer T, and a secondary winding T2 of the power transformer T and a full-wave rectification circuit Z are connected. A resistor R2 is connected in parallel between them and recorded.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a roaring noise prevention circuit for a power transformer.

[0002]

[Prior art]

 When a power transformer is used, when an unbalanced AC voltage is applied to the primary side of the power transformer, a DC current due to a DC electromotive force is applied in addition to the AC current, and the core of the power transformer is magnetized in one direction. When an alternating current peak with the same polarity as that of the direct current is applied, magnetic saturation occurs and a roaring noise is generated from the power transformer. As a technique for preventing such a phenomenon, for example, there is one shown in the circuit diagram of FIG. 2, in which a diode group D in which two or more diodes are connected in antiparallel is inserted in the primary circuit of the power transformer T 1. Thus, the threshold value of the diode is used to prevent a small level of direct current from flowing, and thus the roaring noise of the power transformer T is prevented. A is an AC power supply, Z is a full-wave rectifier circuit, C is a smoothing capacitor, and L is a load. Further, as shown in the circuit diagram of FIG. 3, a diode group D in which two or more diodes are connected in anti-parallel and a circuit network in which a resistor R1 is connected in parallel to the diode group D are used as a primary circuit of the power transformer T. It has been proposed to insert a power transformer so that the roaring noise of the power transformer is not generated (for example, Japanese Utility Model Publication No. 62-9697).

[0003]

[Problems to be solved by the device]

 However, in the circuit of FIG. 2, the diode of the diode group D has a high resistance at a low level and the AC balance is deteriorated. No roaring noise is generated at power-on, but after a while, the core of the power transformer T gradually increases. It has the drawback that it is magnetized in one direction and a roaring sound is eventually produced. In the circuit of FIG. 3, the presence of the resistor R1 connected in parallel with the diode group D can improve the AC balance, which is a problem in the circuit of FIG. 2, and prevent the roar. It is necessary to insert as few parts as possible into the primary side of the power transformer T for safety reasons. Normally, in electronic equipment, most of the so-called rectified loads are used, with the secondary circuit rectified and used. In this case, since a capacitor is inserted and smoothed after rectification, current concentrates only at the peak of the AC voltage. Therefore, removing the resistor R inserted in parallel with the diode group D causes a roaring noise. Be born. It is an object of the present invention to provide a roaring noise prevention circuit for a power transformer that solves the above-mentioned conventional problems.

[0004]

[Means for Solving the Problems]

 The roaring noise prevention circuit of the power transformer according to the present invention includes a diode group formed by reversely connecting diodes to the primary winding side of the power transformer, and a secondary winding of the power transformer and a full-wave rectification circuit. A resistor is connected in parallel between the two.

[0005]

[Action]

 Connect a diode group consisting of diodes reversely connected to the primary winding side of the power transformer to prevent a small level of direct current from flowing, and connect the secondary winding of the power transformer and the full-wave rectifier circuit. By connecting a resistor in parallel between them, there is no bias in the magnetization of the power transformer and the roaring noise is reduced.

[0006]

【Example】

 1 is a circuit diagram showing an embodiment of a roaring noise prevention circuit of a power transformer of the present invention. In the figure, the noise suppression circuit of the power transformer of the present invention is connected to the primary winding T1 side of the power transformer T by connecting the diode group D formed by connecting the diodes D1 and D2 to each other in reverse. A resistor R 2 is connected in parallel between the secondary winding T2 and the full-wave rectifier circuit Z. With such a configuration, the bias of the magnetization of the power transformer T is eliminated, and the roaring noise does not occur. Moreover, since the number of parts to be inserted into the primary winding T 1 side of the power transformer T is reduced, safety is ensured.

If the resistance value of the resistor R2 is selected so that the resistance value consumes electric power of 1/1000 to 1/10 of the maximum load of the power transformer T, the roaring noise is most efficiently reduced. be able to. Further, although the resistor R2 is used in the above embodiment, it may be a lamp. Further, in the above embodiment, two diodes which are reversely connected to each other are used as the diode group. However, the present invention is not limited to this, and a diode in which a plurality of series-connected diodes are reversely connected to each other may be used. Is.

[0008]

[Effect of device]

 According to the roaring noise prevention circuit of the power transformer according to the present invention, a diode group formed by reversely connecting the diodes to each other is connected to the primary winding side of the power transformer, and the secondary winding of the power transformer and full-wave rectification are connected. Since a resistor is connected in parallel with the circuit, the roaring noise of the power transformer can be effectively reduced, and the number of parts to be inserted in the primary circuit side is less than that of the conventional roaring noise prevention circuit, and the safety is also improved. Are better.

[Brief description of drawings]

FIG. 1 is a roaring noise prevention circuit for a power transformer according to the present invention.
It is a circuit diagram which shows an Example.

FIG. 2 is a circuit diagram showing an example of a conventional roar noise prevention circuit for a power transformer.

FIG. 3 is a circuit diagram showing another example of a conventional roaring noise prevention circuit for a power transformer.

[Explanation of symbols]

 A AC power supply C Smoothing capacitor D Diode group D1, D2 Diode L Load R1, R2 Resistance T Power transformer T1 Primary winding T2 Secondary winding Z Full wave rectifier circuit

Claims (3)

[Scope of utility model registration request] 1. A primary winding side (T) of a power transformer (T).
The diode group (D) formed by connecting the diodes (D1, D2) in reverse to each other is connected to 1), and between the secondary winding (T2) of the power transformer (T) and the full-wave rectifier circuit (Z). A roaring noise prevention circuit for a power transformer, wherein a resistor (R2) is connected in parallel. 2. The power transformer according to claim 1, wherein the resistor (R2) has a resistance value that consumes 1/1000 to 1/10 of the maximum load of the power transformer (T). The roaring noise prevention circuit. 3. The roaring prevention circuit for a power transformer according to claim 1, wherein the resistor (R2) is a lamp.