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Class D Switching Power Amplifiers and Power D/A conversion

Class D amp with 300v mosfets
Class D amp with 300v mosfets
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Old 6th November 2017, 04:23 PM   #81
ionutgaga is offline ionutgaga
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Old 6th November 2017, 04:50 PM   #82
ionutgaga is offline ionutgaga
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Originally Posted by ChocoHolic View Post
...had a closer look to the data sheet of the driver.
It has a nice strong output: In terms of current capability it might
work to drive the SiC Fets directly with 6R8 for turn on and shottky+2R2 for turn off - but I guess thermal stress will be to high (did not calculate..).
Simply step into the equations of the data sheet and you will see if the driver will run hot or not.
Did your recommendation takes into account Rg=7 ohms of sct3030al? Because I not included in my calculus, means the temperature rise is much lower.
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Old 7th November 2017, 10:05 PM   #83
ChocoHolic is offline ChocoHolic  Germany
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My proposal are the values for the external resistors. For the heat calculation you have to add the Rg inside the Sic Fet.
...promising, the impedances inside the driver are low, so already without
external PNP most of the gate charge related losses are moved outside the driver towards the external resistors and gate resistance inside the SiC Fet.
Such a tiny chip...., but able to drive the fat SiCs without much external support, did not expect that. But usually such calculation results of the losses of the gate driver are fitting to reality. No hidden obstacles to be expected there.
You should also calculate how much heat you will get in the external resistors.
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Old 8th November 2017, 04:10 AM   #84
Eva is offline Eva  Spain
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This is some documentation about IGBT and SiC related to solar inverters:
- CREE guy showing 50kW solar inverter prototype 2 years ago:
YouTube
I feel at CREE they are working with funds not from previous work but from aids, and trying to aesthetically clean up switching without enough experience on which imperfections matter more, so that a 50kW inverter can be made 100khz, with single stage boosting, and straight hard switched 2 switch per phase output stage, like a 500W inverter.
- Various Infineon brochures discussing several options:
https://www.infineon.com/export/site...df/Solar_1.pdf
https://www.infineon.com/cms/cn/prod...ncent_Zeng.pdf
https://www.infineon.com/dgdl/Infine...3e6a33393f6360
I feel the ones not blindly promoting SiC have deeper experience. Infineon papers show 3-level inverters for minimization of switching loss, facts like 50kW range is lowest sales, clever combination of Si FET, SiC FET/diode and IGBT, etc. (and even SiC diodes at the output of a LLC where a Si diode is lower loss, just for marketing, with modest fooling pretensions).

And both companies still have to discover switching optimizations down to physical limits, variable-frequency "constant ripple" modulators, capacitors across switching transistors, resonant topologies, semi-resonant topologies with helper switch/network, etc. CREE also has to discover 3 level modulation, good for big inverters with slower switches and lower precision demand.

Do you figure out the problem now? Some of us, audio designers, are the actual owners of the key knowledge for making optimum solar inverters in all senses, and application-optimized semiconductors.
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Old 8th November 2017, 08:09 AM   #85
Reactance is offline Reactance  South Africa
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Do you figure out the problem now? Some of us, audio designers, are the actual owners of the key knowledge for making optimum solar inverters in all senses, and application-optimized semiconductors.
That is a forked tongue statement.

Solar inverters success (apart from the obvious that you mentioned) is the power tracking algorithm, and the new ones are moving into the machine learning space where data science will make far more predicative analysis offline inside the firmware as appose to hill climbing and perturbation detection algorithms.
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Old 8th November 2017, 08:26 PM   #86
ChocoHolic is offline ChocoHolic  Germany
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Originally Posted by Eva View Post
Do you figure out the problem now? Some of us, audio designers, are the actual owners of the key knowledge...
Why problem? - I feel
James Brown I feel good - YouTube
when I know better than others...

... but

I'm not an audio designer - it's just a hobby for fun.
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Old 11th November 2017, 03:13 AM   #87
Eva is offline Eva  Spain
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Quote:
Originally Posted by Reactance View Post
That is a forked tongue statement.

Solar inverters success (apart from the obvious that you mentioned) is the power tracking algorithm, and the new ones are moving into the machine learning space where data science will make far more predicative analysis offline inside the firmware as appose to hill climbing and perturbation detection algorithms.
Sorry ionutgaga for offtopic discussion, but this is somewhat the other side of the subject.

MPPT is solved with a self oscillating loop. Just flip sign of constant V source feeding duty cycle integrator after a certain time of negative slope on power output.

Sun can be tracked with panel orientation servos using a similar algorithm, only executed for a few oscillations every few dozen minutes or hour, for longer servo life.

Funny point Choco.
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Old 12th December 2017, 09:30 AM   #88
ionutgaga is offline ionutgaga
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