Switching losses of SiC-Mosfet power modules in 3rd quadrant operation

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ergin
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5 replies posted First reply posted 5 sign-ins

Hi all,

I built a PLECS simulation of a LC-SRC(Series Resonant Converter) for bi-directional power flow. And I am going to use one of Infenion's SiC-Mosfet power module (62mm) (1.2kV and 500A). 

As you can also see from figure, what I attached below, SRC consists of two H-Bridges, one operates in inverter-mode to supply square wave Voltage across LC-resonant tank and the other one operates in synchronous rectifier mode. In 2. H-bridge (synchronous rectification) there is a negative current flowing through the switches (reverse current), which is indicated as 3rd quadrant operation of the MOSFET in datasheets. Both H-bridges switches synchronous. So the switches in 2nd H-Bridge (synchronous rectification) are switched-on and -off while negative current flowing through them. Which means that current will flow through the body diode and the MOS-Channel of the MOSFET. Therefore I expect that there will be switching losses.

By using the related figures with 3rd quadrant operation one can approximately calculate the conduction losses, but there are no information or publication about switching losses during 3rd quad operation! 

My question is, would switching losses arise in 3rd quadrant operation ? if yes what would be the characteristic of it (same as first quadrant switching losses)? 

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Jingwei
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Hello ergin,

Turning on is ZVS, if proper control (Timing) can be obtained, only has very small part of losses, due to diode conducting. For switching off losses you should consider the dynamic Id and Uds during turning off in order to get the losses.

The PLECS model does not calculate negative values, so it will show 0 losses.

Steven

 

 

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Jingwei
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250 sign-ins 10 likes given 100 solutions authored

Hello ergin,

Turning on is ZVS, if proper control (Timing) can be obtained, only has very small part of losses, due to diode conducting. For switching off losses you should consider the dynamic Id and Uds during turning off in order to get the losses.

The PLECS model does not calculate negative values, so it will show 0 losses.

Steven

 

 

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