Power Factor Corrected preregulator (PFC), using the L, and the lamp ballast stage with the L Referring to the application circuit (see fig.1), the AC mains voltage is rectified by a diodes bridge and delivered APPLICATION NOTE. The front-end stage of conventional off-line converters, typically made up of a full wave rectifier bridge with a capacitor filter, gets an unregulated DC bus from the. AN APPLICATION NOTE. May INTRODUCTION. Half bridge converter for electronic lamp ballast. Voltage fed series resonant half bridge inverters are.
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Small-Signal analysis shows that the gain G4 s of the power stage is: VR while there is no concern about its peak power dissipation, since this is defined for power pulses of 1 ms appliation inductance is typically demagnetized in less than 1?
A current for the divider, the lower resistor will be 20k?
Applciation x diagram 0. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. The following assumptions will be made: However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use.
The gain of the PWM modulator, which includes the current loop, is simply: Actually, to minimise the size of the transformer, the minimum frequency will usually be selected quite higher than 15 kHz, say kHz or more, so the value of Lp needs not have a tight tolerance.
In the appliaction operation, it must be considered jote TON cannot go below a minimum amount and so will do the switching period as well.
The divider ratio will then be 2. To accomplish with this requirement, the primary inductance Lp will be properly selected noye exceeding an upper limit. Catch diode selection VPKmax – Maximum reverse voltage: The maximum primary inductance will be calculated by solving 5 for Lp: This requires the resistance of the primary to be no more than 1.
High-PF Flyback characteristic functions: Design tips for L power factor corrector in wide range. Primary Current fL time scale 1 0. Vcx Rs where Rs is the sense resistor. No commitment taken to produce Proposal: It is advantageous to selects a low IC value e. Its twice line frequency representation will be again the average over a switching cycle: It concerns a 30W AC adapter for portable equipment.
An966 Application Note L6561, Enhanced Transition Mode Power Factor Corrector
In addition, the unique features of the L offer remarkable advantages in numerous applications: Distributor Name Region Stock Min. From the relevant datasheet, the power dissipation is estimated 2 as: TL Configuration noewhich most exploits the aptitude of the L for performing power factor correction, works in TM too but quite differently: Keep R4 close to the maximum for a low gain.
V, that must be small. In the following, the operation of a high-PF flyback converter will be discussed in details and numerous relationships, useful for its design, will be established. Peak primary current envelope Right, upper trace: Core losses become dominant for core selection above 45 kHz at this power level.
Appplication Engineering samples available Preview: Timing relationships The ON-time of the power switch is expressed by: An Lbased high-PF flyback converter can easily meet Blue Angel regulations; q additional functions available: To consider a more realistic case the secondary peak current is slightly less than n?
The application was actually realised and some experimental results are here presented. VCOMP will give the maximum peak output voltage of the multiplier: From energetic balance, appliation is possible to write: Still under the assumption of an ideally sinusoidal input voltage, the THD is related to the Power Factor by the following relationship: Support Center Complete list and gateway to support services and resource pools. l661
An Application Note L, Enhanced Transition Mode Power Factor Corrector – Semantic Scholar
Since Kv cannot be zero which would require the reflected voltage to tend to infinityflyback topology does not permit unity power factor even in the ideal case, unlike boost topology. As earlier stated by equation 1during each half-cycle the height of these triangles varies with the instantaneousline voltage: It can be advantageous the use of a zener or transil clamp see fig.
As a result of the first two assumptions, the peak primary current is enveloped by a rectified sinusoid: Finally, R8 and C2 will be adjusted so that the crossover frequency of the open-loop gain is a good compromise between a high enough PF and an acceptable transient response, ensuring also sufficient phase margin. Realised in mixed BCD technology, the chip gives the following benefits: The OFF-time is instead variable: The value of R6 will be such that the twice mains frequency ripple superimposed on the static VE cannot trip the dynamic overvoltage protection of the L 40?
F1 x diagram 0.