Research And Design Of A One-cycle-controlled High Power Factor PFC Convertor

Since the widely use of AC/DC Switching Mode Power Supply (SMPS) in ourdaily life, the harmonic pollution become a serious threat to the AC power grid. PowerFactor Correction (PFC) technology becomes commonly used in AC/DC SMPS systemto solve the problem. With PFC technology, reducing the total harmonic distortion andsuppressing the harmonic pollution become much easier. For the outstanding advantageof PFC technology, it is extensively spread in SMPS design.This paper presents a PFC chip design basic on the One-Circle-Control (OCC)theory. The chip is used in a Boost convertor. Average Current Mode Control of theinductor ensures a steady output voltage and less electromagnetic interference. Theswitch frequency of this chip is65KHz and the duty circle changes by controllingleading edge of the switch signal. There are some circuit blocks such as Voltage Loopblock, Nonlinear Gain block, Current Loop block and PWM comparator, etc. There isno multiplier in the chip so that the circuit design becomes much easier.This paper explains the OCC theory in brief and derives the control formula of theleading edge modulation. The chip is designed and simulated based on CSMC0.5umBCD process. This paper presents you the derivation of the Current Loop’s open gainand the derivation is verified by simulation base on Matlab.With220VAC input voltage and300W load power consumption the output voltageof this chip is395±6V and the Power Factor is about0.9991while the total harmonicdistortion is4.1%. When the load power consumption changes to150W while the inputvoltage is still220VAC, the output voltage of this chip is380±3.8V and the PowerFactor is about0.9802while the THD is about12.6%. The Power Factor gets betterwhen the output power consumption increase. The performance of this chip is wellenough for power factor correction.