科研之友
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摘要
In order for the light emitting diode (LED) used in lighting to be successful, they must be inexpensive, small, and have a high power factor (PF). A driver with a primary-side feedback constant-current control that is capable of power-factor correction (PFC) is proposed in this paper. The principles of primary-side constant-current control under the PFC are analyzed and the process to realin soft-switching under the quasi-resonance working mode are deduced. To reduce low-frequency current ripples, a linear regulator to filter is put forward for filtration of such ripples. An LED driver prototype with an output of 33 V/300mA is built to verify the proposed theory. The experiments showed that it has greater than 86% efficiency, 0.95 PF, and less than 3% ripple within the full voltage range, proving its high application value in low-power LED lighting applications.
