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PWM Controllers

This article needs to be extended especially voltage regulation section. PWM controller can be used in AC-DC as well as DC-DC conversion.I'll add some text in the voltage regulation and u can get some idea Kundojjala 17:32, 24 May 2006 (UTC)[reply]

Distributed PWM

Should we include distributed pulse width modulation, in which the pulse is broken up into a series of small pulses? This might not fall under pulse density modulation since a known duty cycle is output. Furthermore, there is no sigma-delta modulation going on. 128.151.161.49Iain (imarcuso@mail.rochester.edu)

Natural and Uniform Sampling?

There is no mention of natural and uniform sampling. A complete discussion of PWM would include these two different methods of implementing PWM (and information, perhaps, about the frequency-domain consequences). --TedPavlic | talk 18:35, 18 February 2008 (UTC)[reply]

Pulse Width Modulation vs Duty Cycle Modulation

The introductory statement is misleading: "Pulse-width modulation uses a square wave whose duty cycle is modulated". If you modulate the duty cycle (ie. freedom to move both the positive and negative edges, only ensuring that the ratio pulse width to pulse period matches the modulated signal) then you have duty cycle modulation. Pulse width modulation fixes one of the edges so you have a fixed period, and varies only the pulse width. The correct statement should be "Pulse-width modulation uses a square wave whose pulse width is modulated", but my change keeps getting reverted... —Preceding unsigned comment added by 129.215.215.162 (talk) 15:20, 1 April 2008 (UTC)[reply]

In my experience, a square wave is specifically a pulse with a 50% duty cycle; if you adjust the ratio of the time axis to the amplitude axis in a display or diagram, you can make each half cycle a square. I changed "square" to "pulse" throughout, because duty cycle varies. "Square" does not refer to the shape of the corners of the waveform! Including "rectangular" would be a good idea, but doing so increases verbal clutter. Perhaps my strong feeling is partially influenced by spending years with analog music synthesizers, in which a square wave definitely has a 50% dufy cycle. (You might want to remove the bit about setting 50% duty cycle by ear.) Regards, Nikevich (talk) 09:30, 26 July 2009 (UTC)[reply]

Try to use edit summaries, and mention that you'll be adding your reasoning to the talk page. As far as I could see, you were removing valuable context from the article with no clear explaination. Yngvarr (c) 15:22, 1 April 2008 (UTC)[reply]

This needs an mp3 sample

What's the point of learning about synths if you can't hear it? —Preceding unsigned comment added by 75.57.186.23 (talk) 20:41, 27 November 2008 (UTC)[reply]

Servos?

Almost all the servos I've seen are controlled by a PWM signal. Why is it, then, that this article doesn't even mention the word "servo" once? Salvar (talk) 14:01, 6 June 2009 (UTC)[reply]

Thats because most hobby servos are controlled by pulse position modulation, not pulse width modulation http://en.wikipedia.org/wiki/Pulse-position_modulation

97.65.61.9 (talk) 12:57, 27 October 2010 (UTC)[reply]

Afaik that is not true. Servos are controlled by PWM signals. Simpler DC motors translate PWM into voltage by their mechanical inertia acting as LPF. Modern servos have inner electronics, such that a certain pulse width and duty cycle PWM keeps them in the still position, a lower duty cycle causes rotation in one direction (with speed corresponding to the difference in duty cycle) while a higher duty cycle results in the other direction for rotation.

See Servo_motor , [1]. I've used a [2] servo and it also works on PWM. Hoemaco (talk) 17:12, 27 February 2011 (UTC)[reply]

Power Delivery

Should the line: "In this case the PWM duty cycle is defined by the frequency of the AC line voltage (50 Hz or 60 Hz depending on the country)" actually refer to period rather than duty cycle? —Preceding unsigned comment added by 134.225.210.40 (talk) 14:17, 3 July 2009 (UTC)[reply]

Class D amplifiers used in cell. phones?

I strongly suspect that PWM amplifiers are used for the earphone/speaker in a cell. phone, to economize on battery power. However, I'm not sure, so I didn't add such a comment. Nevertheless, if true (likely), this must be the most commonplace application of PWM technology.

Regards, Nikevich (talk) 09:38, 26 July 2009 (UTC)[reply]

Lamp dimmers at 2x power line frequency

They work on both half-cycles, unless I'm quite-badly misinformed. (Fairly sure a typical triac dimmer switches on at a variable point, and switches off when the load current comes close to zero.)

Regards, Nikevich (talk) 09:38, 26 July 2009 (UTC)[reply]

Deprecated title?

According to this source pulse-width modulation is deprecated terminology, preferring pulse-duration modulation. Does anyone know if this is officially deprecated and by whom? The term pulse-width was certainly standard in my day but pulse-duration certainly now seems to have growing popularity. SpinningSpark 16:53, 31 January 2011 (UTC)[reply]

inertial electrical devices

Inertial electrical devices; Explanation needed. I don't see an example of an inertial elecrical device in wiki. We should explain. I couldn't find anything. Could anyone help? Longinus876 (talk) 16:50, 1 September 2012 (UTC)[reply]

It's a simple concept, although I've not heard it described in this literal term before. It could certainly benefit from explanation.

PWM is applied to load device that have "inertia", either mechanical inertia such as a motor driving a flywheel, or thermal inertia such as a heating element housed in firebricks. This means that the time constant for their response (which depends on the ratio between the power of the motor or heater, vs. the inertia effects of the load) is longer than the pulse rate of the PWM signal. They thus respond slowly to the average of the PWM signal, rather than a fast response device (like a meter needle) that might flutter visibly through the PWM cycle time. Andy Dingley (talk) 18:41, 1 September 2012 (UTC)[reply]

Main Graphic demonstrating PWM

@Dicklyon:

In my opinion, the main graphic demonstrating PWM is dangerously vague. The sine wave is obvious, but its application to AC induction motors requires arguably advanced understanding of how AC induction motors work, and on its surface seems invalid.

I attempted to add a sentence explicitly confirming the validity of the graph in regards to ideal AC induction motors. However, my modification was reverted.

I would like to find a simple, concise way to give a hint to the reader regarding the validity of the graph as a description of an idealized AC induction motor.

Any suggestions?

I may take the time to attempt to simplify my proposed addition to the caption, in order to save others time who may also be confused - just to have something in there clarifying that this isn't a meaningless diagram specifically in relation to AC motors.

Daniel347x (talk) 21:07, 6 December 2014 (UTC)[reply]

Your addition to the caption read: Note that in this idealized plot, the current (and hence magnetic field) in the corresponding coil of the motor remain essentially constant when the voltage over the coil is zero (i.e., there is no significant energy drain); but this idealization is roughly correct if the switching frequency of the PWM is high enough. As an EE who knows a bit about magnetics, I still find this roughly uninterpretable in this context, as there's no info in the lead saying anything about the motor, or what the idealization is, or anything about energy transfer. I didn't understand how to interpret the "but" introducing the second part. In general, I think that as a clarification, this is a failure. I agree there's a problem. Probably it could be addressed better by making a section about motor control and moving the figure into it, so that some context for understanding the figure could be established. Dicklyon (talk) 22:38, 6 December 2014 (UTC)[reply]

How about: Note that the plot shown is idealized for the case of a motor that is drawing no power (so that the motor's internal magnetic fields remain constant when voltage is switched off during the PWM cycle).? — Preceding unsigned comment added by Daniel347x (talk • contribs) 22:55, 6 December 2014 (UTC)[reply]