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1.引言 多数电子镇流器和开关型电源(SMPS)的直流电压是通过采用桥式整流器和电容滤波器所组成的电路从交流电源获得的。这种简单的AC-DC电源变换器的主要缺点就是,虽然输入电压为正弦波形,但整流滤波后的电流波形是尖峰脉冲。该窄脉冲电流的基波极低,而高次谐波却相当丰富。这就意味着要从电网中汲取较高的伏安数才能保证电路负载的额定功率消耗。因此,功率因数很低,一般只能达到0.7的水平。为有效地抑制电子镇流器和SMPS的谐波畸变,改善其功率因数,采用先进的有源功率因数校正(PFC)技术,则可获得非常理想的效果。近年来专用功率因数控制IC的日益增多,为设计有源PFC电路提供了十分有利的条件。
1. Introduction Most dc ballast and switched mode power supply (SMPS) DC voltage is obtained from the AC power supply using a circuit consisting of a bridge rectifier and a capacitor filter. The main disadvantage of this simple AC-DC power converter is that although the input voltage is sinusoidal, the rectified filtered current waveform is spiking. The narrow pulse current fundamental low, and high harmonics is quite rich. This means that a higher volt-ampere draw from the grid can guarantee the rated power consumption of the circuit load. Therefore, the power factor is very low, generally only reach the level of 0.7. In order to effectively suppress the harmonic distortion of electronic ballast and SMPS, improve the power factor, and adopt advanced active power factor correction (PFC) technology, then the ideal result can be obtained. In recent years, the increasing use of dedicated power factor control ICs has provided very favorable conditions for the design of active PFC circuits.