KR20080004615U - Protection circuit for power supply adopting Royer converter - Google Patents

Abstract

The present invention relates to a protection circuit applied to an output terminal of a power supply device for a vacuum fluorescent display (VFD) applied to a vehicle audio device, in particular, a Royer converter. The present invention is a protection circuit inserted between a boosting transformer and an output terminal of a power supply device employing a lower converter to protect the power supply device from an output short circuit and an overcurrent. It is characterized in that the circuit does not flow more than a predetermined current. The protection circuit may include a first damping coil for protecting against a short circuit and an overcurrent of a DC output terminal of the power supply device, and a second damping coil for protecting against a short circuit and an overcurrent of an AC output terminal of the power supply device. The first damping coil is connected in series between the first output terminal and the DC output terminal of the boosting transformer of the power supply device, and the second damping coil is connected to one of the first terminal and the AC output terminal of the second output terminal of the boosting transformer of the power supply device. The first winding may be connected in series, and the second winding may be connected in series to another one of the second terminal and the AC output terminal of the second output terminal of the boost transformer.

Description

Protection circuit for power supply adopting Royer converter

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a power supply device employing a conventional Royer converter having AC and DC outputs.

Fig. 2 is a block diagram of a power supply device employing a conventional converter of DC and DC having a DC output.

3 is an exemplary circuit diagram illustrating an actual configuration of the power supply device of FIG. 1.

4 is an exemplary circuit diagram illustrating an actual configuration of the power supply device of FIG. 2.

5 is a block diagram of a power supply unit employing a lower converter having AC and DC outputs according to an embodiment of the present invention.

6 is a block diagram of a power supply device employing a lower converter having a DC, DC output according to an embodiment of the present invention.

7 is an actual configuration circuit diagram of the power supply device of FIG.

8 is an actual configuration circuit diagram of the power supply device of FIG.

9 is a block diagram of a power supply device employing a lower converter having AC and DC outputs according to another embodiment of the present invention.

10 is a block diagram of a power supply device employing a lower converter having a DC, DC output according to another embodiment of the present invention.

11 is an actual configuration circuit diagram of the power supply device of FIG.

12 is an actual configuration circuit diagram of the power supply device of FIG.

The present invention relates to a protection circuit applied to an output terminal of a power supply device for a vacuum fluorescent display (VFD) applied to a vehicle audio device, in particular, a Royer converter.

Among the various types of converters applied to the power supply, the Royer converter is based on a self-supporting push-pull method and is mainly used for a power supply such as a VFD driver for car audio. Since VFD requires both DC / AC (or DC) power, the output is a secondary power supply. The primary power supply is a DC power supply, and the secondary power supply is a DC power supply with an AC or rectifier circuit.

1 and 2 are block diagrams of a power supply device employing a conventional lower converter. FIG. 1 illustrates an example in which one rectifier circuit is provided as an AC power source and a DC power source, and FIG. 2 illustrates an example in which two rectifier circuits are provided as two DC power sources.

3 and 4 are exemplary diagrams of actual circuits of the block diagram shown in FIGS. 1 and 2, respectively. In Fig. 3, since the DC power is output from the Vdc_OUT terminal and the AC power is output from the FL + and FL-, the rectifier circuit consisting of diodes D1 and D2 is inserted into the Vdc_OUT side. In Fig. 4, since the DC power is output from both the Vdc_OUT terminal and the FL + / FL- terminal, rectifier circuits consisting of diodes D1, D2, and D3 and D4 are inserted in each.

However, when the output is short-circuit and overcurrent in the power supply device employing the conventional lower converter, the back ripple is increased to increase the current flowing through the capacitor C1 and the transistors Q1 and Q2 and the oscillation frequency is increased. Eventually these capacitors and transistors are destroyed. In particular, since the secondary DC voltage of the VFD in recent years is very high, when the VFD is mounted on the test jig in the VFD production process, the spark occurs due to instantaneous contact, and the VFD is frequently damaged. In this case, turn off the power, remove the faulty VFD, discharge it, and then test another VFD. Therefore, there are problems such as an increase in production cost due to breakage of the VFD and a decrease in productivity due to the removal of the failed VFD. Conventionally, circuits including protection circuits have been developed to solve these problems, but since these protection circuits are complicated, it is difficult to apply due to their size in the case of products such as car audio.

In other words, the existing protection circuits cannot be applied to the car audio that has to be developed in a small size due to its complicated configuration, and it is more necessary in the situation where the specifications of the VFD are various and high power is required. In particular, as the inspection regulations of automobiles become more demanding and the demand for converter reliability is even greater, existing basic protection circuits are not enough.

In order to solve the above problems, the present invention, by adding a protection circuit to the power supply device of the VFD table market value, particularly the lower converter applied to the car audio, and the like, an output short circuit and Protection circuit of the power supply device that adopts the lower converter which prevents the VFD and the converter from being damaged due to the over current and the spark generated during the inspection and protects the converter from over current due to the abnormality of the VFD. The purpose is to provide.

In order to achieve the above object, a protection circuit inserted between a boosting transformer and an output terminal of a power supply device employing a lower converter according to the present invention, to protect the power supply device from an output short circuit and an overcurrent, the output short circuit and overcurrent Is characterized in that the rear ripple does not flow more than a predetermined current to the oscillation circuit riding the boost circuit.

The protection circuit may include a first damping coil for protecting against a short circuit and an overcurrent of a DC output terminal of the power supply device, and a second damping coil for protecting against a short circuit and an overcurrent of an AC output terminal of the power supply device. The first damping coil is connected in series between the first output terminal and the DC output terminal of the boosting transformer of the power supply device, and the second damping coil is connected to one of the first terminal and the AC output terminal of the second output terminal of the boosting transformer of the power supply device. The first winding may be connected in series, and the second winding may be connected in series to another one of the second terminal and the AC output terminal of the second output terminal of the boost transformer.

Preferably, the first winding and the second winding of the second damping coil are integrally manufactured by a drum-type core.

On the other hand, in another aspect, the protection circuit includes a first winding to protect the short circuit and overcurrent of the DC output terminal of the power supply device, and a second winding to protect the short circuit and overcurrent of the AC output terminal of the power supply device. It may include a damping coil, wherein the first winding of the damping coil is connected in series between the first output terminal and the DC output terminal of the boosting transformer of the power supply device, the second winding of the damping coil of the boosting transformer of the power supply device It can be connected in series between any one of the second output stage and the AC output stage connected to this terminal.

Here, the first winding and the second winding is preferably produced integrally by a two-layer drum-type core.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

5 is a block diagram of a power supply device employing a lower converter having an AC, DC output according to an embodiment of the present invention, Figure 6 is a lower converter having a DC, DC output according to an embodiment of the present invention Is a block diagram of a power supply device employing the following. It can be seen from FIG. 5 and FIG. 6 that the protection circuits are inserted into the AC and DC output terminals, respectively.

7 is an actual configuration circuit diagram of FIG. 5, and FIG. 8 is an actual configuration circuit diagram of FIG. 6. A summary of each part used in FIGS. 7 and 8 is as follows.

R1, R2, R3, C1, Q1, Q2, L1, C5: oscillation and starting circuit, bias circuit

T1: boost circuit (transformer)

Q3, ZD1: Feedback Back Circuit

R4, ZD2: VFD bias circuit. Since resistor R4 applies a high voltage to the zener diode (ZD2), it is preferable to use a metal oxide film resistor (METAL OXIDE FILM RESISTOR) with good insulation.

R5: current limiting and damping resistance

R6: Load resistance (dummy resistance). For discharging the electric charge charged in the circuit at no load

D1 ~ 4, C3, C4: rectifier circuit

C6 ~ 8: Rectifier Circuit

L2, L3: Damping coil for circuit protection

In Figs. 7 and 8 (although the same as with Figs. 3 and 4), the current limiting resistor R5 and the electric charge charged in the capacitor under no load are provided to prevent the converter and VFD from being damaged during output short-circuit and overcurrent. The power supply circuit and VFD are basically protected by the load resistor R6, which allows discharge. In addition, ZD1 and Q3 are used as a feedback circuit for maintaining a constant output and a circuit for maintaining a constant output voltage under no load and load.

The protection circuit according to the present invention shown in Figs. 7 and 8 includes damping coils L2 and L3, which are connected in series between the output terminal of the boost transformer T1 and the final power output terminal, respectively. That is, L2 is connected in series before the rectifying diodes D1 and D2 between the first output terminal (terminal 1) of T1 and the Vdc_OUT output terminal. L3 is a combination of the first winding and the second winding, both ends (terminals 4 and 3) of the first winding is connected between the first terminal (terminal 2) and the FL + output of the second output terminal of T1, respectively. Both ends (terminals 1 and 2) of the second winding are connected between the second terminal (terminal 4) and the FL- output of the second output terminal of T1, respectively. In Fig. 7, since the FL + and FL- terminals are AC output terminals, the damping coil L3 is directly connected to these terminals. In Fig. 8, since the DC is output between the FL + and FL- terminals, there are diodes D3 and D4 which are rectifier circuits.

These output stage damping coils L2 and L3 prevent the parts from being damaged by increasing the oscillation current and frequency by increasing the rear ripple during short circuit and overcurrent of the power output. These are the smallest and simplest circuits and are the most economical way.

These protective actions will be described. If there is no damping coil L2, L3 in the circuit if the DC and AC output terminals are shorted and overcurrent, the current continues to increase and C1, Q1 and Q2 are destroyed. The damping coils L2 and L3 reduce the output ripple and rear ripple during overcurrent so that no more than a certain current flows in the circuit. The limit value of the current is determined by the capacitance value of the damping coil. Therefore, the capacity of Q1, Q2 and damping coil may be determined and used based on the required current value. The damping coil L3 can be manufactured by using a drum core of two layers.

On the other hand, Figures 9 to 12 show another embodiment of the present invention, Figure 9 is a block diagram of a power supply employing a lower converter having an AC, DC output according to another embodiment of the present invention, Figure 10 Block diagram of a power supply device employing a lower converter having a DC, DC output according to an embodiment of the invention. Although the protection circuits described with reference to FIGS. 5 and 6 are provided for each output terminal, according to the present embodiment, it can be seen that the protection circuits work in common for all outputs.

11 is an actual configuration circuit diagram of FIG. 9, and FIG. 12 is an actual configuration circuit diagram of FIG. 10. According to FIG. 11, the damping coil L2 is removed from the circuit of FIG. 7 and the first windings (windings 4 and 3) and the second windings (windings 1 and 2) of the damping coil L3 are respectively replaced by the DC output terminal and the AC output terminal. It is used as a protection circuit. In addition, according to FIG. 12, the damping coil L2 is removed from the circuit of FIG. 8, and instead, the first windings (4 and 3 windings) and the second winding (1 and 2 windings) of the damping coil L3 are protected to all DC output stages. It has a structure to be used as a circuit. Rectification diode D4 is also deleted in FIG. 12.

As mentioned above, L3 can be manufactured with a drum-type core. In the DC / AC output device of FIG. 11, L3 is manufactured with a two-layer drum-type core to maximize the effect of preventing AC noise from flowing into the DC side. It is desirable to. In the circuit of Fig. 11, there is no functional problem even if L3, which is applied to T1, is connected to 5 of T1. On the other hand, since the influence of noise is small in the DC / DC output device, it is sufficient to produce the damping coil L3 as a general drum type core instead of a two-layer drum type core.

13 to 17 are waveform diagrams for testing the performance of the power supply protection circuit according to the present invention, Figure 13 is a normal resonance frequency waveform of the resonant circuit is not applied to the protection circuit of the present invention, Figure 14 is the protection of the present invention Resonant frequency waveform when the output is short-circuited to the resonant circuit to which the circuit is not applied, FIG. 15 is a resonant frequency waveform when the failure of the resonant circuit eventually occurs in the state of FIG. 14, and FIG. 16 is a resonant circuit to which the protection circuit of the present invention is applied. The normal resonant frequency waveform of the furnace, Fig. 17 shows the resonant frequency waveform when the output is short-circuited in the resonant circuit to which the protection circuit of the present invention is applied.

As shown in the waveform above, before the waveform of the resonant circuit is improved, the oscillation frequency at the output short circuit increases from 66 kHz (Fig. 13) to 166 kHz (Fig. 14), and is overheated due to the continuous increase of the current and frequency of the resonant circuit. Then, a defect such as C is generated (Fig. 15), but after the circuit is improved as in the present invention, the waveform between both ends of the resonant circuit capacitor only slightly rises to a waveform of 90kHz at the initial resonance frequency of 66kHz (Fig. 16). It can be seen that the current is kept steady (Fig. 17) to protect the circuit by preventing the breakage of the component.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

The present invention is to protect the VFD power supply applied to the car audio, in particular, the power supply device using the lower converter, to improve the problems of output (AC, DC) short-circuit of the VFD and overcurrent and defects in the VFD inspection process As a circuit, it can be implemented in a simple circuit to reduce the size of the product, which makes the price competitive.

Claims (5)

A protection circuit inserted between the step-up transformer and the output stage of the power supply unit employing the lower converter to protect the power supply unit from output short-circuit and overcurrent, wherein the protection circuit A protection circuit for a power supply device employing a lower converter, characterized in that a rear current ripple during an output short circuit and an overcurrent do not flow a predetermined current or more through a boost circuit. 2. The protection circuit of claim 1, wherein the protection circuit comprises: a first damping coil for protecting against a short circuit and an overcurrent of a DC output terminal of the power supply; and a second damping coil for protecting against a short circuit and an overcurrent of an AC output terminal of the power supply. Including, The first damping coil is connected in series between the first output terminal and the DC output terminal of the boosting transformer of the power supply device, The second damping coil has a first winding connected in series to one of a first output terminal of the boost output transformer of the power supply and one of the AC output terminal, and the other of the second terminal and AC output terminal of the second output terminal of the boost transformer. And a second winding connected in series to the circuit. 3. The protection circuit according to claim 2, wherein the first winding and the second winding of the second damping coil are integrally manufactured by a drum core. 2. The protection circuit of claim 1, wherein the protection circuit includes a first winding that protects against a short circuit and an overcurrent of a DC output terminal of the power supply device, and a second winding that protects against a short circuit and an overcurrent of an AC output terminal of the power supply device. Including damping coils, The first winding of the damping coil is connected in series between the first output terminal and the DC output terminal of the boosting transformer of the power supply device, The second winding of the damping coil is connected in series between any one of the second output terminal of the boosting transformer of the power supply unit and the AC output terminal connected to the terminal, the protection circuit of the power supply device employing the lower converter. . 5. The protection circuit according to claim 4, wherein the first winding and the second winding are integrally manufactured by a two-layer drum core.

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