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Switched reluctance motors will save the planet?
WattsThat:
What an absolute load of marketing wank.
As someone on the front lines of VFD technology, all I can say is, thanks for the laugh.
Switched reluctance motors have been around for years in appliances. Fine for low power, constant torque applications.
On much larger, industrial scale, synchronous reluctance motors (synRM) and their drives have been built for years by ABB. Here’s a video that goes back to 2013, the drive has since been a replaced by the ACS880 which can control asynchronous, permanent magnet and synRM motors, all with the same firmware. 0.5 to several thousand kilowatts. Same drive. They’ve been building them for years. The only difference is that synRM is a variable torque, not constant torque machine. Power savings over standard induction machines is worthwhile, it does provide a quick payback.
Yawn. Nothing to see here. Move along.
bdunham7:
--- Quote from: Jay_Diddy_B on July 28, 2020, 04:30:07 am ---They are very similar to stepper motors. They tend to by noisy and have pulsating torque, the rotor tends to 'snap' from one position to another.
--- End quote ---
My car has a version of the switched reluctance motor. They don't say much about it, and it is sometimes referred to as a 'synchronous motor' but it has that characteristic little quiver if you creep very slowly up a steep incline like my driveway. Other than that it is very smooth and efficient, which I assume is due to the tweaking of the very large liquid-cooled electronic motor drive module.
Jay_Diddy_B:
--- Quote from: bdunham7 on July 28, 2020, 04:48:28 am ---
--- Quote from: Jay_Diddy_B on July 28, 2020, 04:30:07 am ---They are very similar to stepper motors. They tend to by noisy and have pulsating torque, the rotor tends to 'snap' from one position to another.
--- End quote ---
My car has a version of the switched reluctance motor. They don't say much about it, and it is sometimes referred to as a 'synchronous motor' but it has that characteristic little quiver if you creep very slowly up a steep incline like my driveway. Other than that it is very smooth and efficient, which I assume is due to the tweaking of the very large liquid-cooled electronic motor drive module.
--- End quote ---
There are some techniques in the motor design that can reduce the torque pulsation. There are also some techniques that can be applied to the driver, similar to micro-stepping in a stepper motor to reduce the pulsations.
In the conditions you describe, high torque, low speed, the output power is low, since power = torque x angular velocity. The efficiency is low under these conditions.
Jay_Diddy_B
tom66:
I've noticed an interesting phenomenon with my Golf GTE (plugin hybrid.) In electric mode, if you creep up a hill at very low speed, it will eventually stop. In this mode it seems to use about 5kW. It seems as if the electric drive does not like you using creep for long periods of time. You can press the pedal again and it will creep once more but stop after 10 seconds. Whereas it will creep endlessly on flat surfaces. If you actively use the accelerator it will always go faster than this creep setting, so I wonder if it is microstepping and that is inefficient and there is a thermal/time limit here for a reason.
tszaboo:
Different appliances have different design goals for the motors. For example I have a blender, that is probably used a few hours over it's entire lifetime. So, you can design in a very powerful, efficient motor, with diagnostic, variable drive, controller etc. Or find the cheapest rotating thing, and attach a blade for it. The first one would be acceptable for a blender for an ice cream factory I guess, but I'm using mine maybe once a week.
Actually the EU commission recently have been spending a lot of time optimizing the efficiency of white goods. They had new lays for vacuum cleaners and the controversial kettle law. So there is a push to reduce wasted energy.
These guys probably found out that many 20-30 year old building appliances, HVAC could be more efficient with these motors. (I've studied about them in university BTW) Good for you, start replacing old motors, make money. It's actually very nice, that they correctly identified the market niche for their product.
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