Based on input voltage regulation

in the energy crisis db500ffb34c7cc94ef22a7536dcd after the energy conversion efficiency and the effectiveness of increasingly high regard. Thus, countries are also diverse formulate a lot of energy norms. From the early full load efficiency to today's four o'clock uniform efficiency. Desktop power converter, for example, more 80Plus gold, silver and bronze medal in the 20%, 50%, 100% load efficiency norms. However, in many other certification specification, the most troubled of R & D staff is often light load and half load effect. This article first volume of half bridge resonant converter the basic operation Plateau reasonable, and clarifies how through regulating reactive the modify stage PFC output voltage in order to progress in the LLC-SRC half-bridge resonant converter light load and half load effect.

to the current use of high-efficiency power converter, for example, conventional hard-switching techniques Hard-Switching helpless satisfaction of the request in the the 80Plus Gold Medal or higher. The major power supply manufacturers diverse inputs developed soft switching techniques Soft-Switching. Which more half-bridge LLC-SRC series resonant converter Half-Bridge Series Resonant Converter most by the blue eyes. Important Plateau due to its easily reached zero voltage switching to reduce switching loss and the the progressive conversion efficiency, a decrease of such as electromagnetic annoyance EMI.

LLC Highland reasonable dissect
The half-bridge series resonant converter in
LLC-SRC structure shown in Figure 1, can be divided into the triplet part. Square wave generator Square wave generator, resonant network Resonant network output rectifier filter Rectifier network.

A square wave generator by the conduction period of nearly 50% Duty cycle drive power switch MosFETQ1 with Q2 to reach output voltage regulation and by gripping the switching frequency square wave voltage to occur,Grid tie inverter.

B resonant network portion is mainly composed by the resonant capacitor Cr, resonant inductor Lr and magnetizing inductance Lm. This series resonant network can be higher harmonic current filter, and the the current angle outdated voltage reached zero voltage switching.

C application of full-wave bridge rectifier or transformer center tap rectifier type with output filter capacitor, the exchange current is converted to DC voltage output. Exchange for the equivalent circuit is as follows



which



when the input voltage changes or output load changes, to adhere to the output voltage of the solid, required by the swap resonant network voltage gain Gain to achieve. Wherein the gain M may be defined as



which



thereby be noted that the resonant network has two resonant frequencies, one composed by Lr and Cr, while the other by the LP and Cr. And gain with the resonant frequency shift from the load change impact. If the operating frequency w = resonant frequency w0 available



Therefore, when the operating frequency is close to the resonant frequency, all of the resonant impedance of the network is simply will that is output impedance. Here is more similar to the traditional series resonant converter,power inverter. The following picture shows the LLC series resonant converter voltage gain curve.



here with the traditional series resonance is the LLC series resonant converter exist two resonant point, and allow the converter between two resonant point.
FIG 4
, when the operating frequency is less than the resonant frequency FS "F0, primary switching crystal MosFET and secondary-side rectifier diode Rectifier are operating in a soft handover Soft-Switching position, in this case, the secondary side rectifier diodes have no reverse reply time trr of loss. But also because of its the current emerging non-continuous conduction scene,www.12vgridtiepowerinverters.com, its said Ripple Current ripple current in the output filter capacitor, so the analogy useful in the output of the current use of high voltage.

when the operating frequency is greater than the resonant frequency fs f0, characterized more similar to the traditional series resonant converter Series Resonant Converter. Fs more on the verge of f0, its smaller side of reincarnation current Circulating Current, thereby so aptly characterized reduce reincarnation current primary side, to reach efficiency optimization. Secondary side output rectifier diode current than last, the tables had absolutely smaller filter capacitor ripple current. So the operating range is more practical in the output of the use of low voltage and high current.