High-power electronic ballast

Abstract

The invention relates to a high-power electronic ballast for suppressing surge current and realizing soft start by adopting an active secondary detection technology. The high-power electronic ballast comprises an EMI (Electro-Magnetic Interference) filter circuit, a rectifying circuit, an MCU (Micro-programmed Control Unit), a sampling detection circuit and a half-bridge inverter circuit, wherein the output end of the rectifying circuit is connected with one end of a first inductor L11; the other end of the first inductor L11 is connected with the drain of a field effect tube QE and the anode of a diode D11 respectively; the cathode of the diode D11 is connected with one end of a second resistor R12 and one end of a first resistor R11 respectively; and the other end of the second resistor R12 is connected with one end of a third resistor R13 and the sampling detection circuit respectively. After a power supply is switched on, startup surge current is suppressed through the resistor R11, secondary detection is performed by using a sampling circuit, and the circuit is controlled to send a command for running the half-bridge inverter circuit when the voltage reaches 400V, so that real suppression of surge current and soft start are realized.

Description

technical field [0001] The invention relates to the technical field of high-power electronic ballasts, in particular to a high-power electronic ballast which uses active secondary detection technology to suppress surge current and realize soft start. Background technique [0002] High-power electronic ballasts generally adopt active power factor correction technology. When starting up and powering on, a large surge current will be generated due to the charging of the filter capacitor. At present, there are the following three schemes for suppressing the surge current impact of startup in high-power HID electronic ballasts on the market: [0003] The first is to use a single negative temperature coefficient NTC thermistor to suppress the surge current impact at the moment the power is turned on, such as figure 1 , at the moment when the power is turned on, the NTC thermistor has a higher resistance value, which is used to generate a lower surge current when it is just turned...

AI Technical Summary

Problems solved by technology

However, with this method of connection, when the input power is turned on, the PFC circuit will increase the voltage across the electrolytic capacitor C1 to 400V in a short period of time. In order to achieve a better surge current suppression effect, the value of the resistor R is often It will reach about 10 ohms. When the moment of connection is near the peak value of the alternating current, when the voltage across the capacitor C1 reaches 400V, the instantaneous voltage amplitude across the resistor R may reach more than 100V. At this time, the source and drain of the MOSFET tube The voltage value between the poles reaches more than 500V, which exceeds the withstand voltage value of the MOSFET tube, which may damage the MOSFET tube and shorten the service life of the electronic ballast

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