pure sinewave

1) phase-locked loop around a "tuned" LC-filter.
2) "yes" (for minimum phase-angle) and "no" (due to high inductive-reactance).

Some manufacturers do claim for pure sine way inverter .It is possible to closely resemble pure sine wave.But some limitations still remain.Though it is not nessecery to run induction motors on pure sine wave,it does improve its performance.Temperature rise in core due to harmonic currents will be eliminated.

I also heard from audiophiles tht the best way to drive tube amplifiers is to utilize sine wave. Does sine wave have a "good effect" on the circuitry of a tube amplifier system. If yes, where specifically?

Your question is off topic but I'll answer it anyway.

A "pure" sine wave is a single unvarying tone. There is nothing musical about a single tone though.

A music signal is a complex waveform. Some forms of music utilize sine wave and non-sine wave signals. The "fuzz" that a lot of rock musicians use is an example.

Speakers, however, seem to prefer sine waves. If you run a square wave signal through a speaker, the sound is very harsh and potentially damaging to the driver. The is especially true for tweeters or high-frequency drivers.

I'd take anything that an "audiophile" says with a large pinch of salt.

If the fable "The Emperor's new clothes" was written today, it would describe a royal audiophile (with his golden ears) being sold magic speaker cable, hifi grade batteries, "low distortion" valve amplifiers and gold connectors. ffeJ

Dear Arthur

On load, the inductance of the motor, also helps in improving the sine wave quality ( reducing the distortion ), Typically around 3% total harmonic distortion is good enough, beyond that the iron loss in the motor would increase.

Thanks

Ashok Toshniwal, Bangalore, India

Pure Sine Wave is an assumption and Volatge will be Generated in nearly similar to Pure Sine Wave.

Question 2: no, and because of that

Question 1: Sine waves can be approximated very easy by a counter with 8 bits output, each weighted by a resistor. The sum of currents nearly form a sine wave whose shape has some small steps. These are integrated and smoothed by the motors inductance.
Regards Uwe

Arthur,

En la naturaleza no existe la "pureza"... menos en la creacion tecnologica del hombre..

Aunque los artesanos se aproximan a la perfección, la masificacion de las aplicaciones te obliga a definir tolerancias. La creación quasiperfecta de un artesano es extremadamente cara.

La "no pureza" de la onda senoidal, va a depender de lo que seas capaz de tolerar en el funcionamiento no adecuado. El esfuerzo que debes aplicar en obtener "pureza" va a depender de lo que estas dispuesto a "tolerar" en funcionamiento inadecuado.

70AARcuda te da la respuesta acerca de la "pureza". Pero ella se justifica por lo que asegura Nesubra.

Si aceptas que el motor se caliente por las corrientes harmónicas asociadas a las "impurezas" de la onda senoidal..entonces no hay problemas. Pero si no lo aceptas (por daños e impacto económico), debes mejorar lo imperfecto.

Espero haber ayudado...

Luis

There are two questions here - and not necessarily related.

To get a pure sine wave from a midified one simply requires filtering out all the impurites introduced by the modifications - the inductive motor couldn't care less.

Good answers are already given. I would add just a few thoughts.

Every natural oscillation of mater is made of one or more pure sine waves. Anything is different from a pure sine (for example the output of square or step-sine inverter) has a full spectrum of frequencies that can be described with the Fourier transform. That means that the overall power of such an output is distributed on a wide spectrum of harmonics and combinations of them. This can be visualized with a spectrum analyzer. The problem is that any load (except a pure resistive one) is prepared to absorb energy in a very limited spectrum, sometimes on only one frequency. The rest of them are reflected or transformed into heat losses. For this reason it is essential to achieve an impedance match between generator and load. An ideal situation is resonance, which makes possible the optimum transfer of energy in the desired direction.

Regards,

Michael

In addition to what I already said, a highly inductive load such as a motor, transformer, relay, electromagnet, etc. reacts like a low-pass filter and can "smooth" a wide-spectrum energy up to a perfect sine. This is due to the magnetic properties of the core which has a functioning point sliding on a mini-hysteresis cycle. The higher frequencies are transformed into magnetic losses because they cannot follow the embedded magnetic hysteresis.