Part # Application Note Power Supply And Power Management L4981 L6562 L6563A L6561 l6563 AN510 datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: CIRCUITS FOR POWER FACTOR CORRECTION WITH REGARDS TO MAINS FILTERING


Part Details:

APPLICATION NOTE CIRCUITS FOR POWER FACTOR CORRECTION WITH REGARDS TO MAINS FILTERING by J. M. Bourgeois 1. INTRODUCTION 1.1 Basic principles of operation The new European Norms EN 60555 and the A power factor corrector is basically a AC to DC international standard IEC555 will impose a limit on converter, and is usually based on an SMPS the harmonic content of the input current of mains structure. The basic functional blocks of a Power supplied equipment. In practice this will require the Factor Corrector are shown in figure 1. addition of a Power Factor Corrector (PFC) at the A standard SMPS uses Pulse Width Modulation input of many types of mains operated electronic (PWM) to adjust the amount of power it supplies to equipment, for example electronic lamp ballasts, TV the attached equipment. The Pulse Width Modulator power supplies and motor drives. A correctly controls the power switch, which chops the dc input designed PFC draws a sinusoidal input current from voltage into a train of pulses. This train of pulses is the mains supply, in phase with the mains voltage, then smoothed, producing the dc output voltage. and meets the EN60555 norm. It may also provide This output voltage is then compared with a voltage additional functions, such as automatic mains voltage reference representing the voltage desired by the selection and a regulation of the voltage supplied to equipment being supplied, and the resulting voltage the attached equipment. difference (the error voltage) is fed back to the input Size and cost optimization of PFCs must include the of the PWM, which varies the width of the pulses it RFI filter on the input, which prevents interference supplies accordingly - if the output voltage is too being fed back to the mains. The addition of the PFC high, the pulse width is reduced, and thus less power represents another switching stage in the system, is supplied, and vice versa. meaning that larger amount of high frequency noise A PFC also uses this method, but adds a further is applied to the mains than with a conventional element to ensure that the current it draws from the rectifier/capacitor front end, and so additional RFI mains is sinusoidal, and remains in phase with the filtering is required. The amount of fitering needed mains voltage. The error voltage is modulated with a can be minimized by choosing suitable modulation signal derived from the rectified AC mains, before techniques and mode of operation of the PFC. Figure 1. Block diagram of a Power Factor Corrector (PFC) RECTIFIED


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Application Note Power Supply And Power Management L4981 L6562 L6563A L6561 l6563 AN510.pdf Datasheet