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MOSFET (Si/SiC) Forum Discussions

User19064
Level 1
First question asked
Level 1
We work in the photovoltaic industry and need to test 24 module strings, operating at 1500Vdc./10A. In order to perform the tests, we have a 1500Vdc 15kW power supply, run from a generator, that will be connected to one string at a time and would need to switch between strings remotely (wireless).

The 24 channels would need to be switch LIVE, as wee will not be able switch the power supply on and off remotely.

Would it be possible to source SSR's/Mosfet's/IGBT's that would be able to switch the voltage and current required?

Assistance with specifying the components required, circuit and PCB board design would be greatly appreciated.

Regards
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1 Solution
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
Hi Duncan,

difficult to answer. There are two concerns in using 1700 V devices in 1500 V applications due to low margin:

- switching overvoltage: a 1700 V SiC-Mosfet combined with a 1700 V SiC-diode for freewheeling will be able to manage this for low current and slow switching as in your case, provided the layout is reasonable
- cosmic radiation Fit-rate: depending on the chip design and application parameters (mainly voltage, temperature and altitude) there is always a randomly distributed failure rate due to devices losing blocking capability as a result of high energy particles originating from space.

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electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
This application bears three main challenges, two technical ones and one on the commercial side.

Technical:
- You always need a freewheeling path when turning off current. This can be a diode, another switch or some kind of overvoltage protection
- This power range is usually covered by Discretes, however discrete devices for voltages above 1700 V are rarely available, regardless if based on Si or SiC

Commercially:
Discrete devices for this voltage range are technically feasible, but if the market is only for test equipment and other niches rarely attractive for a semiconductor supplier Hence find someone willing to supply this as a subsystem, SSR or similar. Customized module solutions (e.g. in Easy1B) for such applications would only become feasible only at volumes of several 1000 parts per year.

Regards,
electricuwe
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electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
Hi Duncan,

difficult to answer. There are two concerns in using 1700 V devices in 1500 V applications due to low margin:

- switching overvoltage: a 1700 V SiC-Mosfet combined with a 1700 V SiC-diode for freewheeling will be able to manage this for low current and slow switching as in your case, provided the layout is reasonable
- cosmic radiation Fit-rate: depending on the chip design and application parameters (mainly voltage, temperature and altitude) there is always a randomly distributed failure rate due to devices losing blocking capability as a result of high energy particles originating from space.
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