Real savings of inverter AC

[nike123]

Anyone know of study made in controlled conditions of two air-conditioners of same manufacturer, of same size, with same parts used with only difference in inverter driven compressor and normal ON-OFF compressor respectively. I mean same compressors used of same COP and EER at 50 (60) Hz, but one is powered and controlled by inverter and other is controlled by regular ON-OFF cycle.

I would like to see that comparison in energy savings, since claims of 30-50% in savings are way to much for my understanding of physics and construction of air-conditioners.

As far as I know, energy is consumed by air conditioned space and air-conditioner task is to convert electrical energy in to "cooling" energy or heat. Difference in power consumption can be accomplished only by difference in COP and EER off used air-conditioners. Since I strongly doubt that inverter driven and on-off controlled compressor (i mean physically same one) can have that much (30-50%) difference in COP and EER i don't see how can we achieve such savings as declared in many AC manufacturers commercials.

Therefore I would like to see study in controlled conditions where only difference between two samples is driving principle of same compressor (ON-OFF vs INVERTER)

[NiHaoMike]

At part load, the condenser and evaporator become oversized, which is what gives lot of the efficiency. PMSMs (permanent magnet synchronous motors) are also more efficient than induction motors in this application, but the advantage is much smaller than it was in the past.

What's interesting is that Copeland actually has a compressor that has a mechanism inside it to turn it on and off very quickly in order to control capacity.