Modified Sine Wave 1

[xJAyx]

Does anyone have experience running a motor on a modified sine wave? I have a motor on a valve actuator that I would like to run off of an invertor which outputs a modified sine wave, the output is more or less a square wave with some dwell on 0V, like below. I just want to know if anyone has experienced problems doing this. The invertor company says it should be fine, but I'd like to hear from the experts.

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[Skogsgurra]

It should not be a problem. Running a drive motor continously could (perhaps) lead to more heat because of the harmonics in the waveform. But a valve actuator usually only runs for short periods and the extra heating should not be a problem - unless, of course, that the valve opens/closes continously. In the latter case, I would have a look at the valve controller and try to stabilise it.

 

[xJAyx]

Thanks, that's exactly what I thought. The motor only runs for about 82 seconds to close the valve and happens only once a month or less so it should definately not be a problem.

 

[jraef]

This used to be the standard for Variable Frequency Drives (6-step inverters), but causes some long term problems that can be avioded with more modern PWM style drives, so the design has fallen out of favor. However, as skogsgura said, for a short duty cycle application like this it should be just fine, and they tend to be very rugged and reliable, desireable qualities in valve actuaters if you ask me.

"Venditori de oleum-vipera non vigere excordis populi"

 

[buzzp]

The signal you are generating is a PAM (pulse amplitude modulation) singal. These types of signals are still commonly used in oil and water wells due to the length of the cable. Granted, most are now 12 pulse or 18 pulse type signals.