Help designing a dual H-Bridge controller
Help designing a dual H-Bridge controller
(OP)
I am trying to build a circuit to control 2 H-bridges. The H-bridges outputs must be 90 degrees out of phase with each other. I was thinking about using a sg3524 signal to control one H-Bridge and using the same signal as an input to 2 556 timers acting as a delay and trigger signal to the other H-bridge. The H-Bridges will be driving coils. I don't believe I have the skills to use a microcontroller unless I am thinking it is more complicated than it is. If anyone has any ideas as to how I can control this setup more effectively please give me some guidance.
Chad
Chad





RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
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RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
Then you need a laptop or PC and about an hour of time and you can have it any way you want it. You can also adjust things with a few taps of the keyboard.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Help designing a dual H-Bridge controller
Figure 22 page 3-61. Did something similar a while ago.
I used 2 uc3846 chips and a flip/flop to an external
clock. The f/f gives a square wave 180 out. The resultant
outputs out of the chips where 90 degrees out.
Should work the same for a uc3524 chip.
Now, I would agree with itsmoked and use a micro.
RE: Help designing a dual H-Bridge controller
http://varedan.com/
makes some nice linear current mode amplifiers that can be factory configured to drive voice coils. Linear means no PWM switching noise. The current is proportional to the command signal and is bidirectional. You would also need a servo chassis to power the amplifiers.
RE: Help designing a dual H-Bridge controller
Thanks again
Chad
RE: Help designing a dual H-Bridge controller
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Help designing a dual H-Bridge controller
Now you've got your 90 out-of-phase.
RE: Help designing a dual H-Bridge controller
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
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If we learn from our mistakes I'm getting a great education!
RE: Help designing a dual H-Bridge controller
Regards,
Benta.
RE: Help designing a dual H-Bridge controller
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If we learn from our mistakes I'm getting a great education!
RE: Help designing a dual H-Bridge controller
For an IC like the 3524 The sycn pulse current would be sent to the ramp capactior and must be higher than the ramp-discharge current. This isn't specified in some IC's so it has to be high to make sure it works. I'd use a 3525 PWM instead of the 3524. The sync methods are specified and more straigtforward.
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
dead time, bi-phase outputs, dual feedback inputs, etc.
<als>
RE: Help designing a dual H-Bridge controller
A reasonable copy of the pwm with 90 deg. phase delay would be to send the signal through a single pole low pass filter. The pole would be designed at the frequency of pwm giving you 45 deg. of phase and then sending it through another single LPF just like the first to pick up the other 45 deg. Paying attention to the impedance input so as not to tap off to much current from the sg5324 and the necessary gain to get back the 6 dB dropped by filter.
This would require a single chip with a couple of op amp on a single chip some resistors and capcitors. A potentiometer or two to vary where the pole actually ends up and viola a 90 deg. phase shift of the sg5324 output. Anyone disagree.
Best Regards
RE: Help designing a dual H-Bridge controller
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If we learn from our mistakes I'm getting a great education!
RE: Help designing a dual H-Bridge controller
Good luck with it!
Regards,
Gonzalo
RE: Help designing a dual H-Bridge controller
Feed that into a pair of flip flops, but they need to be connected in a special way. Google "twisted ring counter" or "Johnson counter". That will give you four output phases arranged in exact 90 degree phase quadrature.
Take any two of these phases that have a 90 degree relationship, and drive a pair of the commercial H bridge driver chips. Some of these drivers have the feature of adding dead time, so the upper and lower drive signals do not overlap.
RE: Help designing a dual H-Bridge controller
I don't know what are your voltage and current requirements, but to have a quickly working driver section here is an integrated H-bridge chip that is very good and virtually foolproof. It takes care of shoot-thru itself. ST Micro model VNH2SP30E. It is good up to 30 amps. I had a good success with it in an automotive application.
RE: Help designing a dual H-Bridge controller
I only ever see under 10A ones mostly ~5A.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
RE: Help designing a dual H-Bridge controller
That seems to be a brilliant yet simple solution to the problem of shoot through. I was not familiar with this method. Do you happen to know an easy method to determine what is the appropriate inductance to use but also not really interfere with the maximum power available to the H bridge?
Chad
RE: Help designing a dual H-Bridge controller
Please note that a bigger inductance will keep the shoot-thru current low for longer time, though it will also rise the voltage spikes if the clamp diode protections of your H-bridge aren't fast enough.
Also pay attention when choosing filter caps. and PWM frequency, to prevent ringing and resonance issues.
Good Luck!
Gonzalo
RE: Help designing a dual H-Bridge controller
Chad, sorry I had not seen your post until now.
I have seen this method of putting an inductance in series used very widely in smaller electronics like inverters for fluorescent lights etc. It is simple and cheap but maybe in larger things it might make sense to use other methods if the inductance becomes too big and can be replaced by a different design of the controlling circuit.
I suppose the characteristics of the inductor would have to be studied and determined by the specific circuit. You would need to determine not only the inductance but resistance and other parameters, including cost.
RE: Help designing a dual H-Bridge controller
These consist of a series inductor, usually along with a diode and a resistor to dissipate the stored energy in the inductor.
RE: Help designing a dual H-Bridge controller
With the good IC solutions suggested earlier. I guess you're done
Good Luck!
RE: Help designing a dual H-Bridge controller