Design of PFC Switching Power Supply Circuit Based on LED Street Light

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

Overview:
The ability of LEDs to withstand surges is relatively poor, especially against reverse voltage capability. It is important to strengthen protection in this area. LED street lights should be installed outdoors to enhance surge protection. In view of this, this paper introduces the design of PFC switching power supply based on LED street light. The solution adopts an outdoor LED street lamp power supply designed with active PFC function circuit, built-in complete EMC circuit and high efficiency lightning protection circuit, which meets the requirements of safety regulations and electromagnetic compatibility. The final test results also show that the PFC switching power supply designed by this scheme has good performance, reliability, economy and high efficiency, and has achieved satisfactory results in the use of LED street lamps.

0 Preface
The LED street lamp is a low-voltage, high-current driving device. The intensity of its illumination is determined by the current flowing through the LED. If the current is too strong, the LED will be attenuated. If the current is too weak, the LED will be affected. Therefore, the LED driver needs to provide constant illumination. Stream power supply to ensure the safety of high-power LEDs while achieving the desired luminous intensity. Driving high-power LEDs with utility power needs to solve the problems of buck, isolation, PFC (power factor correction) and constant current, and also requires relatively high conversion efficiency, small volume, long-term operation, easy heat dissipation, and low cost. , anti-electromagnetic interference, and over temperature, over current, short circuit, open circuit protection. This paper introduces the design of PFC switching power supply based on LED street light. The solution adopts an outdoor LED street lamp power supply designed with active PFC function circuit, built-in complete EMC circuit and high efficiency lightning protection circuit, which meets the requirements of safety regulations and electromagnetic compatibility. The final test results also show that the PFC switching power supply designed by this scheme has good performance, reliability, economy and high efficiency, and has achieved satisfactory results in the use of LED street lamps.

1 The overall block diagram of the system uses a switching transformer, PFC control to achieve a switching power supply, output constant voltage constant current voltage, drive LED street lights. The overall block diagram of the circuit is shown in Figure 1.

The ability of LEDs to withstand surges is relatively poor, especially against reverse voltage capability. It is also important to strengthen protection in this area. LED street lights should be installed outdoors to enhance surge protection. Due to the start of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause LED damage. Therefore, the LED driving power supply should have the ability to suppress surge intrusion and protect the LED from damage. The EMI filter circuit mainly prevents harmonic interference on the power grid from entering the module and affects the normal operation of the control circuit.
After the three-phase AC is rectified by the full bridge, it becomes a pulsating DC. Under the action of the filter capacitor and the inductor, the DC voltage is output. The main switch DC/AC circuit converts DC power into a high frequency pulse voltage at the secondary output of the transformer. The high frequency pulse outputted by the transformer is subjected to high frequency rectification, LC filtering and EMI filtering to output the DC power required for the LED street lamp.
The PWM control circuit uses voltage-current double-loop control to achieve regulation of the output voltage and output current. The feedback network uses a constant current constant voltage device TSM101 and a comparator. The feedback signal is optically coupled to the PFC L6561. The power factor of the module is 0.95 due to the use of the PFC device.
(Please read the PDF for details)