Re: [WheelCommander] WC-132

Milton Street <miltst@xxxxxxxxxxx> · Sat, 28 Nov 2009 15:39:02 -0600

Hey Pete,

I may be wrong, but wouldn't using a HIP-4080A (instead of the HIP-4081A) be able to directly connect with 3 lines directly to the WC-132 (for each motor control side)?

In any case, the whole problem Hank has been having from the start was that he started out with a simple generic H-bridge design that did not have the needed logic to work with PWM correctly.

For the motors he wants to use he needs a really high current H-bridge. So, Pete, maybe you could give him some other alternative "high power" H-bridge (or H-bridge driver chip) solutions that do not require adding even more extra logic circuitry.

It would be much nicer if he could use something simpler that could connect directly (with 3 lines per side) to the WC-132 (like some of the lower power H-bridge chips that are mentioned in the Wizard manual).

SIDE NOTE: If I recall correctly, for the motors Hank wants to use I believe the H-bridge needs to be able to handle at least 80 Amps at 12 Volts... which is getting way to high powered and out of my knowledge range to even think about. If they were not so expensive, I had suggest it would be easier for him to just buy a pre-built H-bridge motor controller instead. That would be the easiest solution, although I think he is learning a lot of things (possibly the hard way) by trying to build it all himself LOL.

My main concern with what he's trying to do though is the lack of proper over-current and over-heat protection with a "home built" H-bridge for that high power level.

So, Pete, if you've got any kind of "low cost" solution that might work better (or easier) for Hank I'm sure he'd appreciate any suggestions you could give him.

-Milt

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> Date: Sat, 28 Nov 2009 11:37:03 -0800
> From: plskeggs@xxxxxxxxxxxxxxxx
> To: wheelcommander@xxxxxxxxxxxxxxxxx
> CC: wheelcommander@xxxxxxxxxxxxxxxxx
> Subject: Re: [WheelCommander] WC-132
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> Hank,
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> None of our example H-bridge configurations will work as-is with the
> HIP-4081A, though the dual-dir version is the place to start:
>
> http://nubotics.com/products/wc132/dual-dir-h-bridge.pdf
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> The direction line control can be wired according to that diagram to
> the high side control pins, BHI and AHI. The low side, however, cannot
> be wired directly to the PWM output.
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> Instead, you will need to add some logic between the WC-132 and the
> HIP-4081A to control which pin, BLI or ALI, receives the PWM signal
> based on the logic levels of the direction lines (L_DIR or R_DIR).
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> You can implement this many different ways. One way is to get one quad
> 2 input AND gate package, such as the 74HC08. You will need to use two
> gates for each H-bridge. (Another way is to use two quad 2 input NAND
> gate packages to build AND gates out of NAND gates).
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> Take the left wheel's H-bridge as an example, and assume the four gates
> in the AND package are designated A, B, C, D. Say you use AND gates A
> and B for the left wheel, and C and D for the right.
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> The outputs of gates A and B would connect to the left wheel's
> HIP-4081A ALI and BLI pins respectively; we will selectively control
> these gates to only send the PWM signal to the side of the H-bridge we
> want to drive with the PWM signal; the other side will see a logic low
> on the lower FET input of the H-bridge but a logic high on the upper
> FET input. Now for the inputs to the gates.
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> Connect L_PWM to one input of each gate A and B. Connect the L_DIR to
> the unused input on gate A, and /L_DIR (WC-132 DIO3, pin J4.4) to the
> unused input on gate B.
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> For this to work, you need to have /L_DIR connected to AHI and L_DIR
> connected to BHI, with gate A's output is connected to ALI and gate B's
> output is connected to BLI. This way, when L_DIR is high, BHI's FET
> and ALI's FET will turn on when L_PWM is high, spinning the motor one
> way. When /L_DIR is high, AHI's FET and BLI's FET will turn on when
> L_PWM is high, spinning the motor the other way. When L_PWM is low,
> neither low-side FET will be on, allowing the motor to coast.
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> You would do the same thing for the right H-bridge, only using gates C
> and D and the corresponding R_PWM, R_DIR, and /R_DIR signals.
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> Hope this helps. I can do a diagram if you need it.
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> -Pete
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> Hank van Buuren wrote:
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> Hi Pete,
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> I have two high powered H-Brides
> there driver consist of the HIP-4081A and I am working on interfacing
> the HIP-4081A H-Bridge driver to your WC-132.
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> I want to use the dual-dir-h-bridge
> capability on the WC-132 but the
> schematic dated 2/172008 is not quit clear to me on how the reverse
> would have to work.
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> This is a schematic of the H-Bridge
> I intent to use Page 108, stamp BS2 is excluded, see attachment
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> I hope you can help me. Regards,
> Hank van Buuren.
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