Variable frequency preheating restartable fluorescent lamp electronic relay with abnormal protection

Abstract

A variable frequency preheating fluorescent lamp electronic ballast enabling to restart up and being equipped with abnormal protection consists of metal shell. EMI filter suppressing power supply electromagnetic interference, power supply bridge stack ¿C rectifying circuit, boosting transformer APFC, MOSFET semibridge inverter, lamp tube load circuit, abnormal protection control circuit. It features that three steps of cathode preheating, frequency going up from low to high and lighting ¿C up lamp tube are applied to increase service life of lamp tube.

Description

technical field [0001] The invention relates to the technical field of electronic energy-saving lighting electric light sources, in particular to an electronic ballast for fluorescent lamps with variable frequency preheating and restartable protection against abnormalities. Background technique [0002] At present, the widely used fluorescent lamps belong to the cathode preheating start-up electric light source. Many advertisements and promotions of electronic ballasts often use the "one-point light" quick start method as an advantage to publicize. A major defect of the ballast is that the space charge around the cathode of the fluorescent lamp is very thin before starting. If it is started quickly, voltage and current are applied to the filament of the cathode of the lamp and both ends of the lamp at the same time. The cathode emission material is far from It reaches a thermoelectric emission state higher than 700°C, and the high voltage cannot ionize ...

AI Technical Summary

Problems solved by technology

[0002] At present, the widely used fluorescent lamps belong to the cathode preheating start-up electric light source. Many advertisements and promotions of electronic ballasts often use the "one-point light" quick start method as an advantage to publicize. A major defect of the ballast is that the space charge around the cathode of the fluorescent lamp is very thin before starting. If it is started quickly, voltage and current are applied to the filament of the cathode of the lamp and both ends of the lamp at the same time. The cathode emission material is far from It reaches a thermoelectric emission state higher than 700°C, and the high voltage cannot ionize and breakdown the lamp tube in a short period of time, resulting in a transition from glow discharge to arc discharge, which causes severe sputtering of the cathode emitting material of the fluorescent lamp, making its lamp The tube wall around the filament at both ends of the tube is blackened and damaged prematurely, which greatly shortens the service life of the lamp tube

In the prior art, the preheating and starting of fluorescent lamps generally adopts the PTC thermistor method, which has a simple structure and low price, but the main problem is poor consistency and reliability.

In addition, since the electronic ballast is matched with the power specification of the fluorescent lamp, the electronic ballast cannot be damaged when various abnormal conditions occur during use. If the electronic ballast does not take corresponding protection measures, it will cause damage. Although there are many main schemes for abnormal protection in the existing technology, such as current limiting protection, overcurrent protection, Overvoltage protection and other types, the circuits are mostly designed and installed separately, lacking the function of comprehensive protection

Images