| With the development of society,people’s requirements for the environment are getting higher and higher,and the traditional LED power supply system also needs to change as people pay more attention to high-frequency pollution.Therefore,using modern electronic technology to realize the green and intelligent lighting system has become an inevitable development trend.The existing two-wire lighting system rectifies 220V alternating current and drives the LED lamp group in a constant current mode through a high-frequency converter,which generates EMI electromagnetic radiation and electromagnetic interference,and cannot directly control the lamp groups of each zone directly through the two wires.If the power line carrier technology is used to implement the partition control,the cost increases and the power loss is large.In view of the above problems,a low-EMI lighting system based on a non-sine wave power supply is designed.The system is mainly divided into a main part and an extension part.The first is the design of the main part of the lighting system.The non-sine wave generator is designed by using single chip microcomputer and digital to analog conversion technology to generate the non-sine wave reference voltage with a period of 3ms and an amplitude of 4V～5V.The non-sinusoidal reference voltage is modulated by the PWM controller,and then driven by a high-voltage bidirectional converter into a non-sinusoidal voltage with a period of 3ms and an amplitude of 206V～260V,providing N extensions of the system.The second is the circuit design of the signal separator and the working power supply of the extension part.Differential technology is used to differentiate the non-sinusoidal power supply rising part provided by the host to obtain the low-voltage working power required by the extension.Using the characteristics of the non-sinusoidal power supply voltage with different slopes,the falling part is differentiated to obtain logic 1 and 0.Therefore,the two lines can not only communicate with the host and the extension,but also transmit energy.Finally,the LED lamp group driving circuit obtains different working voltages required for the operation of the LED lamp group by chopping,and detects the working current of the LED lamp group to achieve the purpose of constant current driving.The experimental results show that the subject realizes the two-wire communication between the host and the extension.The host can stably output the low-frequency and high-voltage non-sine wave voltage to the extension.The extension can successfully receive the command sent by the host to realize the partition control of the extension by the host,and the LED lamp group driving circuit can work stably.Because the entire lighting system does not have high-frequency and high-voltage pulses,only has a low-frequency current of about 300Hz.The extension does not need a DC-DC high-frequency converter,only has a simple chopper circuit.What’s more,all extensions work synchronously.Therefore,the green lighting system is favorable for mass production,greatly reduces electromagnetic radiation,and has the characteristics of simple circuit and low cost. |
