JPH0937465A - High-power factor electronic stabilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maximum power factor by feeding back a high-frequency voltage taken in by utilizing a lamp to the output terminal of a rectifier circuit, coupling a high-frequency filter at the pre-stage of the rectification circuit in advance for matching to a power factor improving feedback circuit for high-frequency switching and adjusting a phase difference. SOLUTION: A high-frequency filter 30 is connected next to a noise elimination circuit 20. A capacitor 33 of the high-frequency filter 30 not only plays a roles of the high-frequency filter but also a role for adjusting a power factor phase angle. A rectifier circuit 40 is provided at the later stage of the high-frequency filter 30. An input AC current in converted to a DC current for a lamp 70 and for a power factor improving feedback circuit 50. The anode of a diode 51 is connected to the lamp 70. A vibration circuit 60 is connected to both terminals of a capacitor 53 of the feedback circuit 50. The vibration circuit 60 consists of transistors 61 and 62 and flywheel diodes 63 and 64 and a high frequency is fed back to the output terminal of the rectification circuit 40 via the lamp 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power factor electronic ballast. In particular, there is no need to use an existing LC filter device for the entire circuit, and a power factor of 0.98 or higher can be achieved. In addition, the weight of the ballast is greatly reduced, and it is free from the noise generated by general LC filters. In addition, it also reduces the consumption of virtual work and achieves a reduction in power consumption. Also, because this ballast is protected, it is protected from high voltage breakdown caused by lamp failure and the quality and life of the ballast is improved.

[0002]

2. Description of the Related Art A circuit diagram of a conventional electronic ballast currently used is shown in FIG. 1, in which a low frequency LC filter 10, a bridge type rectifier 11, an electrolytic capacitor are mainly used.
12 exerts a filter function, and a circuit is constituted by these and the DC / AC conversion circuit 13, and finally, the lamp 14 is activated and turned on. However, since this type of ballast uses only the electrolytic capacitor 12 for charging / discharging and a low frequency filter, the ballast always emits noise. Moreover, in this type of filter method, the phase of the current greatly exceeds the phase of the voltage (as shown in Fig. 2), so the power factor is about 0.
It has fallen to around 6, which obviously consumes virtual work and wastes power.
Also, since the ballast protection circuit is not installed in this existing circuit, if the lamp 14 is damaged, a large current will flow in the circuit composed of the ballast and the lamp, and the switching transistors 130 and 131 will burn out. When the lamp 14 is broken, the ballast is also destroyed, which is extremely uneconomical and has a practical problem.

[0003]

Therefore, as a result of repeated research and development in consideration of the fact that the present electronic ballast has the above-mentioned drawbacks, the present inventor finally found that The present invention, which is an improvement of the above, is realized. The main object of the present invention is to improve the phase delay of AC input voltage and current, increase power factor, and save power consumption.

Another object of the present invention is to reduce ballast manufacturing costs and to provide a high quality, noise free ballast. Another object of the present invention is to provide a protective circuit that operates reliably and to improve the life and quality of the ballast.

[0005]

The main features of the present invention are as follows.
The high frequency voltage captured by using the lamp is fed back to the output terminal of the rectifier circuit, and the high frequency filter installed in front of the rectifier circuit is also coupled to the power factor correction feedback circuit to match the high frequency switching function. Adjusting the phase difference and achieving the highest power factor.

The next feature of the present invention is that a silicon controlled rectifier and a coil are connected between the transistor base and the emitter of the vibration circuit. In addition, a bidirectional diode connected in series with the feedback coil and the gate electrode of the silicon control rectifier is also used.When the lamp fails, the high voltage generated in the feedback circuit triggers the bidirectional diode to control the silicon. It activates the rectifier and exerts a protective effect from high pressure.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to the circuit diagrams shown in FIGS. 3 and 4, the present invention provides a set of a noise elimination circuit 20 composed of inductances 21 and 22 and a capacitor 23 at a power input terminal. It is installed. The device of this noise elimination circuit 20 is purely for noise reduction, and if omitted it does not significantly affect the integrity of the circuit. After the noise elimination circuit 20, a high frequency filter 30 is connected. This high-frequency filter 30 uses a pair of small transformers made of high-frequency iron powder for two inductances 31 and 32. The placed capacitor 33 functions as a high-frequency filter and also has a power factor phase angle. Will also play a role of coordination.
A rectifier circuit 40 is installed after the high frequency filter 30. This rectifier circuit 40 can be a bridge type rectifier and is a full-wave rectifier or a half-wave rectifier. In this embodiment, the bridge type rectification is adopted to convert the input AC current into the DC current for the lamp 70 and the power factor correction feedback circuit 50. Along with this, the anode of the diode 51 and the lamp 70 are connected to each other to form a minus half cycle circuit. Also, the power factor improvement feedback circuit 50 capacitor
A vibrating circuit 60 is connected to both ends of 53. This vibration circuit
60 is a transistor 61,62 and a flywheel diode
The high frequency frequency generated by using 63, 64 is supplied to the lamp 70 and fed back to the output terminal of the rectifier circuit 40. In addition, coils 65 and 66 are installed between the bases and emitters of the transistors 61 and 62, respectively. A protection circuit 80 is installed between the vibration circuit 60 and the power factor correction feedback circuit 50. This protection circuit 80 is mainly a vibration circuit.
It is connected between the base and emitter of a transistor 62 in 60. Silicon controlled rectifier 81 is installed in this circuit, and feedback coil 82 and silicon controlled rectifier are installed.
A bidirectional diode 83 connected in series to the gate electrode of 81 is also used, and an electric resistance 85, a capacitor 86 and several diodes 87, 88 and 89 are also installed to form a protection circuit. ing.

The power factor correction principle of the present invention is briefly described as follows: The high frequency voltage provided by the oscillating circuit 60 passes through the lamp 70 to the output point of the rectifying circuit 40 (that is, the left end of the diode 51). Since the voltage is fed back, when the voltage at the left end of the diode 51 is higher than the voltage at the right end, the diode 51 is in the ON state, filters and charges the electrolytic capacitor 53, and provides sufficient energy for the load. When the voltage at the left end of the diode 51 is lower than the voltage at the right end, the diode is turned off, and the electrolytic capacitor 53 provides the energy required for the lamp 70 and the load. Since it is not necessary for the power input terminal to supply energy to the electrolytic capacitor 53, the effect of adjusting the phase angle is generated and the power saving effect is also exhibited. Further, the electrolytic capacitor 53 and the lamp 70 also form a discharge circuit.
When the voltage discharged from the electrolytic capacitor 53 to the left end of the diode 51 is higher than the voltage at the right end, the diode 51 is immediately turned on again, and the power input terminal starts charging again toward the electrolytic capacitor 53 and the load Provide enough energy. Charging and discharging are repeated in this way,
The frequency of the discharge will determine the operating frequency of the lamp 70. Therefore, the high-frequency voltage fed back by the lamp 70 contains a high-frequency component in the low-frequency waveform output by the rectifier circuit 40 (as shown in FIGS. 5, 6, and 7). The circuit 50 has a high-frequency switching effect, and the switching frequency and the vibration frequency of the circuit are synchronized. Further, the high-frequency filter 30 arranged in the preceding stage reinforces the high-frequency component filter and the adjustment of the phase angle (as shown in FIG. 5), and can bring the difference between the phase angles of the input voltage and the current to the minimum ( As shown in Fig. 8, the power factor of this circuit is
Achieved 0.98 or more), can increase the power factor.

The operating principle of the protection circuit of the present invention is as follows: after the lamp 70 fails, the feedback coil
82 is sensitive to a relatively high voltage and its current
And via electrical resistance 85 to charge capacitor 86. If the charging voltage of the capacitor 86 is higher than the collapse voltage of the bidirectional diode 83, it immediately causes the bidirectional diode 83 to conduct, triggers the gate electrode of the silicon controlled rectifier, activates the silicon controlled rectifier 81, and keeps the conductive state at all times. Put on. However, this conduction state puts the diodes 87, 88 and 89 in a short circuit state, and at the same time, the capacitors 86 to
And the voltage discharged via the silicon controlled rectifier 81,
In other words, the voltage on the capacitor 86 also becomes 0, and the coil
Since 65 also short-circuits via the diode 88, the base trigger signal of the transistor Q2 becomes 0 ', and the line voltage on the anode of the diode 89 also short-circuits via the diode 89 and the silicon-controlled rectifier 81, and the line voltage becomes 0. Therefore, the cut state of the transistor is secured, and the ballast is finally placed in the protection state (as shown in FIGS. 9 and 10). However, even if the lamp 70 is replaced with a new one and the power supply is activated again, the silicon-controlled rectifier 81 remains in the OFF state because the gate electrode of the silicon-controlled rectifier 81 has not received the high voltage trigger. Therefore, the transistors 61 and 62 can maintain the normal switching operation.

Still referring to FIG. 11, this figure illustrates the voltage change on the feedback coil 82 during normal operation in an embodiment of a high power factor electronic ballast having a protection circuit of the present invention. . In the state where the power supply is started and the lamp is not yet lit shortly after, the current is flowing through the capacitors 71 and 72, so that the current and voltage of the feedback coil 82 are relatively large, and from the point D to the point E in the figure. As shown. The inventor has installed an electric resistance 85 especially between the gate electrode and the feedback coil of the silicon controlled rectifier in order to avoid that this high voltage for a short time at the time of starting the lamp 70 triggers the silicon controlled rectifier 81 to cause a malfunction. This electric resistance 85 is matched with the capacitor 86 to adjust the RC time constant, and this RC time constant is made larger than the sequence from the point D to the point E to prevent the malfunction of the silicon controlled rectifier 81 and to prevent the present invention. It ensures certainty when executing.

[0011]

From the above description, the advantages of the present invention are as follows: The phase delay between AC input voltage and current is improved, power factor is increased, and power consumption is saved. 2. By replacing the existing low-frequency filter method with a high-frequency filter method, the parts can be made compact and noise can be eliminated. 3. Manufacturing costs are reduced by constructing the simplest and most practical circuit with the most economical components. 4. Specially designed protection circuit improves ballast quality and life.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a prior art electronic ballast.

FIG. 2 is a diagram showing voltage and current waveforms at an AC input terminal of a conventional electronic ballast.

FIG. 3 is a block diagram of an embodiment of the present invention.

FIG. 4 is a circuit diagram of an embodiment of the present invention.

FIG. 5 is a diagram showing a current waveform of a diode on the rectifier circuit according to the embodiment of the present invention.

FIG. 6 is a diagram showing a voltage waveform of a diode between the rectifier circuit and the electrolytic capacitor according to the embodiment of the present invention.

FIG. 7 is a diagram showing a current waveform of a diode between the rectifier circuit and the electrolytic capacitor according to the embodiment of the present invention.

FIG. 8 is a diagram showing waveforms of current and voltage of an AC input terminal according to an embodiment of the present invention.

FIG. 9 is a diagram showing a voltage waveform on a feedback coil during a lighting period and a diagram showing a voltage waveform after lighting according to an embodiment of the present invention.

FIG. 10 is a diagram showing a voltage waveform on the feedback coil when the lamp of the embodiment of the present invention is abnormal and a diagram showing a voltage waveform after the protection circuit is activated.

FIG. 11 is a feedback coil 82 during normal operation in an embodiment of a high power factor electronic ballast having a protection circuit of the present invention.
It is a figure which shows the above voltage change.

[Explanation of symbols]

 10 Low frequency LC filter circuit 11 Bridge rectifier 12 Electrolytic capacitor 13 DC / AC converter circuit 14 Lamp 20 Noise signal elimination circuit 30 High frequency filter 40 Rectifier circuit 50 Power factor improvement feedback circuit 51,84,87,88,89 Diode 21, 22,31,32 Inductance 23,33,52,53,86,71,72 Capacitor 60 Oscillation circuit 130,131,61,62 Transistor 63,64 Flywheel diode 65,66 Coil 70 Lamp 80 Protection circuit 81 Silicon controlled rectifier 82 Feedback Coil 85 Electrical resistance 83 Bidirectional diode

Claims (6)

[Claims] 1. A high frequency filter comprising an inductance and a capacitor between an input terminal of a power supply and a rectifier circuit.
Installed as a set, a power factor correction feedback circuit composed of a diode and an electrolytic capacitor was installed between the rectifier circuit and the vibration circuit, and the high frequency voltage captured by the lamp was used as the output terminal of the rectifier circuit and the diode of the power factor correction feedback circuit. High-power that is configured to achieve the best power factor by adjusting the phase angle of the input current and voltage by feeding back between the anodes of the Rate electronic ballast. 2. A set of protection circuits is installed between the vibration circuit and the power factor correction feedback circuit, and the protection circuit comprises a silicon controlled rectifier and a bidirectional diode and a feedback coil between the base and emitter of the transistor in the vibration circuit. A high power factor electronic ballast that consists of a circuit composed of, and the high voltage that the feedback coil of the oscillating circuit responds to when the lamp fails to trigger the bidirectional diode, keeping the silicon controlled rectifier conductive at all times. 3. The high power factor electronic ballast according to claim 1, wherein a diode is connected in series between the rectifier circuit and the electrolytic capacitor. 4. The high power factor electronic ballast according to claim 1, wherein the inductance of the high frequency filter is a transformer constituted by a high frequency iron powder core. 5. The high power factor electronic ballast according to claim 2, wherein several diodes are connected in series above the anode of the silicon controlled rectifier to ensure the discharge effect. 6. The high power factor electronic ballast according to claim 2, wherein an electric resistance and a capacitor are installed between the gate electrode and the feedback coil of the silicon controlled rectifier to control the time constant of the silicon controlled rectifier.