Talk:H-bridge
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I must be tired, because it seems that the arrows showing current flow are actually drawn backwards in the 2 states of the H bridge drawing.
Does anyone else concur?
Anyway good article, thanks to the authors for their contributions.
- Well... I as far as I can see, the arrows indicate the voltage, not the current... CyrilB 08:34, 8 November 2006 (UTC)
- I'm pretty sure its backwards. 75.74.112.76 20:10, 18 November 2006 (UTC)
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- It would be backward if the arrows were representing the current, but it is the voltage ! CyrilB 19:38, 19 November 2006 (UTC)
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[edit] An arrow indicates current
Any time I have seen an arrow in a schematic it has represented current. To represent voltage a "+" on one side and "-" on the other is the convention. Very often they will be shown together such as: + -------> - (looks better if the arrow is a straight line rather than a bunch of minus signs).
Also in addition to MOSFETs and BJTs, IGBTs can be used in H-bridges.
Dsignoff 05:00, 10 February 2007 (UTC)dsignoff
- Usually, the arrows that indicate current are directly on the wires, not on their side. And I put what looks like a clear label to me (V). Furthermore, in most applications, a H bridge imposes the voltage to the load, not the current, so it is not possible to presume the direction of the current in the figures of the article, while it is for the voltage. If you have an idea to make the circuit more clear, please help yourself! Usually, the direction of the voltage arrows is from minus to plus (- --------> +).
- And yes, IGBT can be used too, as any other switch (e.g. relays) CyrilB 10:53, 10 February 2007 (UTC)
- The only place that I know of that labels things with real current over conventional current is High School. If you study electronic engineering the standard is to use conventional current (i.e. + -------> - current flowing from positive terminal to negative terminal). America might be an exception (but I doubt it) because they seem to do everything different to the rest of the world.
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- Dsignoff is quite right when (he/she) says that arrows are used to indicate current. It is against standards to us an arrow to represent voltage. Your statement that it is not possible to presume current direction but it is possible to presume voltage direction is also inaccurate. Using the conventional current system, current must flow from a positive terminal to a negative terminal. If you are able to write the voltage direction, you can also write the current direction. Mathematically it is possible to have current flowing in the opposite direction but in this case the current will have a negative value and therefore obeys the previous statement. --Spuzzdawg 05:24, 16 November 2007 (UTC)
An arrow certainly indicates current flow, but which type? Like many things there are two conventions concerning current flow. One called "electron flow" holds that current is the flow of electrons from negative to positive. The other "hole flow" maintains that current is the flow of open valences that flow in the opposite direction, from positive to negative. Both are technically correct and useful. —Preceding unsigned comment added by 64.15.95.49 (talk) 21:50, 1 February 2008 (UTC)
[edit] Broken Link
I removed the link:
as it is broken. If anyone can find the new address of the file please put it back. --Spuzzdawg 05:24, 16 November 2007 (UTC)
[edit] Short-circuits and Braking
From the article: Using the nomenclature above, the switches S1 and S2 should never be closed at the same time, as this would cause a short circuit on the input voltage source. The same applies to the switches S3 and S4. This condition is known as shoot-through.
From the Motor controller article: Both NPN or PNP transistors can be activated to cause a short across the motor terminals, which can be useful for slowing down the motor from the back EMF it creates.
There appears to be a conflict here. From what I understand, shorting across the motor terminals can be perfectly ok, depending on the circuit. Am I wrong? StevenBell (talk) —Preceding comment was added at 03:17, 22 January 2008 (UTC)
- I was thinking incorrectly. Closing S1 and S2 would be bad, but closing S1 and S3 would cause a braking action.
- StevenBell (talk) 17:48, 22 January 2008 (UTC)
