Design and evaluation
The following are specifications for the application of dual-tube quasi-resonant flyback converter streetlights. The range of input voltages is broad enough to be efficient. The rated power is set at 120W to comply with the unique requirements of LED street lights. Design indicators also eliminate bulky heat sinks as much as possible. All power devices are surface mount packages with D-PAK or D2-PAK.
The minimum switching frequency is set to 45 kHz. In order to leave room for the DC, the input voltage range from 300V to 430V. Taking into account the falling time of the drain-source voltage, the maximum value of the 300V input voltage of the MOSFET is 0.45. This ensures the correct reset of the magnetizing current and the triggering of the MOSFET after the drain-source voltage drops to the input voltage. through.
Figure 2 is an efficiency measurement based on input voltage and power FET technology. Each MOSFET packaged in D-PAK is the best Rds device. The SuperFETTM technology is 600 milliohms and the SupreMOSTM technology is 385 milliohms. SupreMOS MOSFETs greatly increase system efficiency due to their small switching losses and the low energy stored in the output capacitors. SupreMOS MOSFETs can achieve at least 2% efficiency over the entire input voltage range.
Figure 2 System efficiency
The operating temperature of the device is measured using a thermal imaging camera. Since no heat sink is applied to the surface mounting device, the step of ensuring that the operating temperature is within an acceptable range becomes particularly important. As shown in Figure 3, all power devices work well at an input voltage of 90V below 70 degrees Celsius.
Figure 3. Temperature of the device under input voltage conditions of 90V AC.
to sum up:
The dual-tube quasi-resonant flyback converter provides a good solution for LED street lighting and has successfully demonstrated its performance through its unique design for LED street lighting. Topology technology is not sensitive to transformer tolerances and gate drive times, as well as a robust and reliable power supply design. With these advantages, the dual-tube quasi-resonant flyback converter is an attractive alternative to the LLC resonant converter in the field of LED lighting. (Laura translation)
Related reading: Double-tube flyback solution for LED street lamps (on)
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