RU77127U1 - ELECTRONIC START-UP CONTROL UNIT FOR HIGH PRESSURE DISCHARGE LAMPS - Google Patents

Abstract

The utility model relates to electronics and lighting engineering, and in particular to devices for ignition and power of high-pressure discharge lamps with an ignition voltage of more than 3 kV. The electronic ballast contains a radio noise filter, a power factor corrector, a rectifier, a PWM controller, a half-bridge inverter on MOS transistors controlled by a half-bridge driver, loaded onto a lamp according to a resonant circuit, which provides start-up and voltage regulation on the lamp using a microprocessor and PWM controller. EFFECT: increased reliability of the apparatus, expansion of the range of suitable lamps, regulation of the radiation power of the lamp.

Description

The utility model relates to electrical and lighting engineering, namely, to devices for ignition and power of high-pressure discharge lamps with an ignition voltage of more than 3 kV. Modern electronic ballasts (high-voltage ballasts) for high-power discharge lamps are most often performed according to the scheme of bridge or half-bridge inverters [1-4]. However, to start such discharge lamps, a higher voltage is required than the inverter supply voltage, therefore, the circuit is supplemented by a pulse or other ignition device.

Known inverter [5], taken as a prototype. It contains a half-bridge driver based on CMOS - a chip that controls two transistor switches. The use of such a driver allows you to use an external master oscillator and change the frequency of the output voltage of the inverter loaded onto the lamp according to the resonant circuit.

The disadvantage of electronic ballasts using a typical half-bridge driver switching circuit is the lack of adjustment of the inverter output voltage and lamp radiation power.

The objective of the utility model is to provide the functions of starting, regulating and stabilizing the power of a discharge lamp. The task is achieved in that the electronic ballast containing a half-bridge inverter on MOS transistors controlled by a half-bridge driver with an external start, loaded on a lamp according to a resonant circuit, additionally contains a microprocessor and a PWM controller, which allow regulating the frequency and voltage of the inverter.

Figure 1 presents the structural diagram of a utility model. The circuit consists of a half-bridge inverter 1 with a control driver 2 included according to a typical circuit, and a resonant lamp ignition circuit formed by a high-frequency inductor 3 and capacitors 4, 5. The input of the half-bridge driver 2 is connected to the output of the PWM controller 6. Frequency and duty cycle of the PWM start pulses - the controller is set using microprocessor 7.

The supply voltage of the inverter is formed by a rectifier 8, connected to the network through a radio noise filter 9 and a power factor corrector 10.

The device operates as follows. When the electronic ballast is connected to the network, the inverter receives a constant voltage from the power corrector, reaching 400 V. But the inverter does not work, since in the initial state the transistor switches are closed. After the specified delay time has elapsed, the microprocessor generates triggering pulses with a frequency of 250 kHz, PWM - the controller and the half-bridge driver open the upper and lower keys of the inverter alternately, and the resonant LC circuit is created on the elements

the increased voltage is Q times greater than half the supply voltage of the inverter, where Q is the quality factor of the oscillatory circuit formed by the inductor, lamp and capacitors of the resonant circuit.

After the inverter starts operating, the frequency of the triggering pulses gradually decreases until the lamp ignites. The ignition moment is recorded using the signal from the lamp current sensor supplied to the microprocessor input. The frequency of the driving pulses drops sharply to 70 kHz and is set by the external PWM controller circuit.

Further, lamp currents are continuously monitored and maintained at a given level using a microprocessor and a PWM controller. If the microprocessor fails, the inverter does not break due to the use of a PWM controller with an external timing circuit.

In the absence or malfunction of the lamp, the process of starting the inverter at an increased frequency is repeated several times, after a given number of unsuccessful attempts, the inverter automatically shuts down.

Re-turning on the inverter resumes after disconnecting and turning on the mains voltage.

The electronic ballasts also provide protection functions against overloads, from low and high voltage, stabilization of the operating current of the lamp using a PWM controller.

The utility model is implemented in practice. The driver of the half-bridge is the IR2101 chip, the PWM controller is made on the TL494 chip, and the PIC18F25 chip is used as the microprocessor. The electronic ballasts were DNAZ-600 and DNAZ-600 super lamps. Both lamps were ignited and exited at a given radiation power.

EFFECT: increased reliability of the apparatus, expansion of the range of suitable lamps, regulation of the radiation power of the lamp.

Literature

1. Moin B.C. Stabilized transistor converters. - M .: Energy, 1986 - 138 p.

2. Application No. 2409592 (Great Britain). Discharge light controller. IPC Н05В 41/285, 41/26. Published on June 29, 2005, No. 0330019 (GB), Eng.

3. Application for invention No. 2006112322/28 (Germany). Electronic ballast for the lamp. MPK Н05В 41/00, BI No. 29, 2007

4. Ru No. 2000109104. The ballasts for sodium discharge lamps MPK Н05В 41/295. Published February 27, 2002 (Abstracts of Russian patent documents for 1994-2007 (rus.), Http://www.fips.ru).

5. Information material PD 60043 from International Rectifier on

technical specifications of the IR2101 half-bridge driver, http://www.irf.com. 2001 (prototype).

Claims (1)

An electronic ballast for high-pressure discharge lamps, containing a radio noise filter, a rectifier, a power corrector, an inverter with a half-bridge driver using powerful field effect transistors, loaded onto a lamp in a resonant circuit, characterized in that it additionally contains a microprocessor and a pulse-width modulation controller ( PWM controller).