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发表于 2013-4-19 19:38:55
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Easy.
think of the driver / mosfet's gate as a R (driver's output impedance) / C (gate capacitance) network: the (ideal) driver charges up the gate capacitance through its output impedance, or discharges it. And that process takes time - during that process, the mosfet isn't fully turned on / off - working in a "linear mode" or its "saturation region". The amount of time in this transition is higher with a higher R or higher C (the "rc" constant). This is the source of the switching loss.
As you increase the drive frequency, the proportion of time the mosfet stays in this transition increases -> switching loss increases.
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