有源钳位的优点及与其它电路的相比较的不同点:
SIGNIFICANT BENEFITS:
&& "recycles" transformer magnetizing energy instead of
dissipating it in a resistor
&& facilitates Zero Voltage Transition of the main switch
for higher efficiency
&& uses lower voltage MOSFET and diodes
compared to the RCD
&& reduced EMI/RFI via soft switching
&& eliminates lossy snubber network on primary
&& operates at fixed frequency
&& allows much higher frequency operation && similar
power transfer to conventional square wave switching
&& duty cycles beyond 50% max are obtainable
&& actively resets main transformer to third quadrant of
BH curve
DIFFERENCES AND SIMILARITIES:
This new approach requires a few more parts than
the other forward choices to achieve the benefits
listed previously. Differences include:
&& an additional high voltage MOSFET
clamp/reset switch
&& an isolated, variable duty cycle gate drive for the
clamp/reset switch
&& a modified PWM control technique to properly
program the associated delays between gate
drives to achieve the zero voltage transitions
&& a new gate drive technique to extract the
proper clamp/reset drive pulse
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