Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

MOSFET (Si/SiC) Forum Discussions

User17810
Level 1
First question asked
Level 1
Hi guys I would like to know if anyone has any experience with SiC in motor drives. If so, could you share the pro's and the con's?
0 Likes
1 Solution
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
When considering the use of SiC in drives, you have a clear target in mind.

Usually an increase of switching frequency (compared to today's drives using IGBTs) will not provide a benefit. Motor current harmonics and related losses are already at a quite low level. On the other hand you will not be able to utilize a higher switching speed, as motor windings and bearing imply a limit on dV/dt.

Hence, when converting a drive from IGBT to SiC-Mosfet, switching frequency and dV/dt should be considered as not subjected to change. However, even at same dV/dt there will be a saving in switching loss (e.g. no tail current, no reverse recovery loss) and with sufficient active area there will also be a saving on forward losses. Utilizing this will lead to a benefit on system level, e.g. enabling a design with natural cooling and high ingress protection or enabling motor integration.

View solution in original post

0 Likes
3 Replies
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
When considering the use of SiC in drives, you have a clear target in mind.

Usually an increase of switching frequency (compared to today's drives using IGBTs) will not provide a benefit. Motor current harmonics and related losses are already at a quite low level. On the other hand you will not be able to utilize a higher switching speed, as motor windings and bearing imply a limit on dV/dt.

Hence, when converting a drive from IGBT to SiC-Mosfet, switching frequency and dV/dt should be considered as not subjected to change. However, even at same dV/dt there will be a saving in switching loss (e.g. no tail current, no reverse recovery loss) and with sufficient active area there will also be a saving on forward losses. Utilizing this will lead to a benefit on system level, e.g. enabling a design with natural cooling and high ingress protection or enabling motor integration.
0 Likes
Fränce
Moderator
Moderator 5 sign-ins 5 replies posted 10 questions asked
Moderator
Good morning,
Is there a possibility to estimate the lifetime of TO-247 in servo drives?

Thanks!
0 Likes
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
Hi Fränce, sorry for the delay in answering due to holidays season

yes, it is possible to calculate lifetime in such an application. Under the Assumtion that our recommendations for gate drive have been considered, the main degradation mechanism for a servo drive will be power cycling. The temperature profile has to be calculated based on a realistic mission profile. Then the junction temperature excursions have to be evaluated using the power cycling data and the rainflow algorithm. Power cycling data are available on request if the device under consideration is specified.


Compared to Si devices SiC devices usually will exhibit a lower number of cycles for a given delta T, but if sized properly, a reduction in delta T is possible compensating this drawback.
0 Likes