I wouldn´t think that you need additional deadtime with IR2113 because the internal deadtime is at least 30ns. I use HIP2101 which has about 3ns deadtime and I have applied a diode, resistor, capacitor circuit giving about 20ns deadtime. Instead of IRF540N I use 540Z which has a much faster body diode (decreases the shoot through rapidly) with a 20ohm gate resistor combined with a BAS32L turn off diode. This way I achieve 25ns rise and fall times with +/-40V supply voltage.
Hi AmpMan!
Is there a reason why you do not use the IR21094?
IR21094 offers an adjustable dead time in the range between
0.54µs...5µs with just one resistor.
Do you need the possibilty to control the ON-time of the upper
and lower MosFet in separate? Then forget the IR21094.
But a traditional PWM-amp should be possible without fancy
conrol mechanisms and the drive signals of the upper and lower MosFets contain simply the inverted information + some dead time.
For this the logic of IR21094 should work fine.
Bye
Markus
Is there a reason why you do not use the IR21094?
IR21094 offers an adjustable dead time in the range between
0.54µs...5µs with just one resistor.
Do you need the possibilty to control the ON-time of the upper
and lower MosFet in separate? Then forget the IR21094.
But a traditional PWM-amp should be possible without fancy
conrol mechanisms and the drive signals of the upper and lower MosFets contain simply the inverted information + some dead time.
For this the logic of IR21094 should work fine.
Bye
Markus
Hi Pabo!
Thanks. Your answer matches exactly to some upcoming doubts.
I am thinking about a high power pwm-amp for a subwoofer with
two Sadhara drivers.
First ideas:
Full bridge, switching frequency about 70kHz, passive LC output low pass filter 25kHz/2nd order.
Rail voltage around 130V (regulated SMPS), PWM control with Unitrode UC 3823A, halfbridge driver IR2109, FET Drivers Unitrode UC 3710T, MosFets: Semikron MOSFET Modules SKM120B020.
Stop!
Don't ask me if I am going for an audio amp or some traction application...
I already downgraded the project from two TUMULTs to two SADHARAs... (hope I will manage to get them from Adire...)
All comments welcome. I did not start up to now and this project will keep me busy the next year anyway.
I am not in hurry because that older beast still is working fine, but
the two sadhara will offer about ten times more volume displacement.... about 100times more acoustic power .... about 20db more max. output...
I must admit, it is more some sort of "research" or curiosity than a real demand
.
Bye
Markus
Thanks. Your answer matches exactly to some upcoming doubts.
I am thinking about a high power pwm-amp for a subwoofer with
two Sadhara drivers.
First ideas:
Full bridge, switching frequency about 70kHz, passive LC output low pass filter 25kHz/2nd order.
Rail voltage around 130V (regulated SMPS), PWM control with Unitrode UC 3823A, halfbridge driver IR2109, FET Drivers Unitrode UC 3710T, MosFets: Semikron MOSFET Modules SKM120B020.
Stop!
Don't ask me if I am going for an audio amp or some traction application...
I already downgraded the project from two TUMULTs to two SADHARAs... (hope I will manage to get them from Adire...)
All comments welcome. I did not start up to now and this project will keep me busy the next year anyway.
I am not in hurry because that older beast still is working fine, but
the two sadhara will offer about ten times more volume displacement.... about 100times more acoustic power .... about 20db more max. output...
I must admit, it is more some sort of "research" or curiosity than a real demand
.Bye
Markus
the old beast
...forgot that link in my last post....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25015&highlight=
...forgot that link in my last post....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25015&highlight=
ChocoHolic
I have designed a 500W/4ohm classd amp for subwoofer apps and it runs at 250kHz which was the frequency that I reached the lowest bias current. Below 250kHz the ripple current in the output choke became too high and above 250kHz the switching losses became too high. It is a fullbridge with +70V supply and it uses a simple voltage hysteresis regulation from before the output filter.
What I am trying to say is that it is not obvious that it is better to go down in frequency when you are designing a sub amp. If you want to limit the ripple current to a couple of amps you will have to use a 200uH inductor or something which has to handle 30A or so. That is a pretty hefty inductor!!
I have designed a 500W/4ohm classd amp for subwoofer apps and it runs at 250kHz which was the frequency that I reached the lowest bias current. Below 250kHz the ripple current in the output choke became too high and above 250kHz the switching losses became too high. It is a fullbridge with +70V supply and it uses a simple voltage hysteresis regulation from before the output filter.
What I am trying to say is that it is not obvious that it is better to go down in frequency when you are designing a sub amp. If you want to limit the ripple current to a couple of amps you will have to use a 200uH inductor or something which has to handle 30A or so. That is a pretty hefty inductor!!
Hi Pabo!
Yes, the output filter is one of the keys for success or not.
My first approach is a 2nd order filter with around 50uH and
1uF and a 10 Ohms (parallel to 1uF). If the two Sadharas would be pure resistors the HF current would still be very high.
4.6A in sum for the paralleled Sadharas, making 14W steady state losses in each speaker. Not immediately destructive, but not nice.
(Sadhara: each nominal 4 Ohms, DC: each 2.6 Ohms)
But the speakers Le (1.3mH each speaker) theoretically will bring this down dramatically to about 300mA in sum, making some milliwatt in each speaker. Do I miss something?
But I am thinking also about the resulting resonance modes of the
filter in combination with the drivers. I fear that they are in the audiable range.....
From this side I would prefer a simple inductor (200uH) in series to the paralleled speakers, no cap, and a 10 Ohms non inductive resistor paralleled to the speakers .
Losses in the speaker: some milliwatts.
Losses in the 10 Ohms around 30 Watt.
Choke: challenging....
...inductor for such currents is a certain sort of fun for itself....
or better "pretty hefty" ?
But don't worry about the magnetic...
...one of the parts, where I am confident that I will manage it...
Yes, the output filter is one of the keys for success or not.
My first approach is a 2nd order filter with around 50uH and
1uF and a 10 Ohms (parallel to 1uF). If the two Sadharas would be pure resistors the HF current would still be very high.
4.6A in sum for the paralleled Sadharas, making 14W steady state losses in each speaker. Not immediately destructive, but not nice.
(Sadhara: each nominal 4 Ohms, DC: each 2.6 Ohms)
But the speakers Le (1.3mH each speaker) theoretically will bring this down dramatically to about 300mA in sum, making some milliwatt in each speaker. Do I miss something?
But I am thinking also about the resulting resonance modes of the
filter in combination with the drivers. I fear that they are in the audiable range.....
From this side I would prefer a simple inductor (200uH) in series to the paralleled speakers, no cap, and a 10 Ohms non inductive resistor paralleled to the speakers .
Losses in the speaker: some milliwatts.
Losses in the 10 Ohms around 30 Watt.
Choke: challenging....
...inductor for such currents is a certain sort of fun for itself....
or better "pretty hefty" ?
But don't worry about the magnetic...
...one of the parts, where I am confident that I will manage it...
Don't know how applicable this observation is, but when I was playing with open reel tape bias oscillators several years ago, I found that the audible fidelity subjectively improved as I increased the bias frequency up to at least 400 khz. If I was designing a high quality class D amplifier (I'm not at this point), I would probably accept some switching losses to run at a higher frequency than at the minimum for overall thermal losses if it improved achievable performance in other areas such as high frequency damping factor & distortion, frequency extension and phase linearity, etc.
....things are getting interesting...
Up to now I am a beginner in switch mode amps.
But I got the speakers today ==> no way back.
DIY direction for my next year is clear. I will have to learn
about switch mode amps
I am faithfull that a subwoofer is less critical with respect to the switching frequency than a full range application.
If I consider that my max signal frequency that I want reproduce is around 50Hz, then 70kHz give a frequency ratio of 1400.
An amp for the full audio frequency range which must reproduce
20kHz and would operate at 1MHz (who can handle? In my percepting 1MHz is the entry to Voodoo Land).... well even you would run a full range amp at 1MHz the frequency ratio would only be 50.
So I felt quite comfortable with a factor of 1400 for my sub.
But I must admit: I have no practical idea in this field...
Let's see what will happen!
Up to now I am a beginner in switch mode amps.
But I got the speakers today ==> no way back.
DIY direction for my next year is clear. I will have to learn
about switch mode amps
I am faithfull that a subwoofer is less critical with respect to the switching frequency than a full range application.
If I consider that my max signal frequency that I want reproduce is around 50Hz, then 70kHz give a frequency ratio of 1400.
An amp for the full audio frequency range which must reproduce
20kHz and would operate at 1MHz (who can handle?
In my percepting 1MHz is the entry to Voodoo Land).... well even you would run a full range amp at 1MHz the frequency ratio would only be 50.So I felt quite comfortable with a factor of 1400 for my sub.
But I must admit: I have no practical idea in this field...
Let's see what will happen!
Nice looking mono blocks!- Status
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