Controlling the speed of air Conditioner Compressor motor by using AC TO AC conveter

hi,

I want to design a speed controller (v/f) for Air conditioner Compressor motor.

Is it possible to use the technique of AC/AC converter Matrix Cyclo-converter for this purpose.

Can i operate a compressor at 25Hz and half of the line voltage?

if you halve the voltage and frequency you get the same current, but half the power (W = V X I), will this be enough to start the compressor? It might be useful to start the motor at 230V/50HZ and ramp it down to 115V/25 HZ over 5 seconds.
Frank

While you probably -could-, will you really gain efficiency
by so doing? A/C systems seem to be pretty well optimized,
motor / compressor / air handler / blower, and you may
not win anything by reducing one piece's heat-throw -
only make all of the rest, in effect, oversized uselessly.
After all, you have the same heat load regardless, right?
So I'd expect you might cycle less but run longer and,
if the original designer did their job, at some point away
from designed peak efficiency.

There are variable (often just 2-lung) A/C compressors,
occasionally you'll see continuously variable control
on a single lung but this appears to be low value judging
from the relative rarity of the approach. The air handler
blowers, though, seem to have been moving to a more
continuously-variable control (probably because this
is something the customer can sense, while the pump
sits outside and just makes noise regardless).
rarity.

I actually built precisely that over 10 years ago for a home refrigerator.

It helps to reduce overall energy consumption if it is part of a control algorithm that takes advantage of the cycloconverter.
What I did is to replace the original thermostat with an electronic sensor and a microcontroller.

Additionally, the centrifugal switch that cuts the start capacitor, must be replaced with microcontroller operated relay.

Note, I only tested it with a reciprocating compressor.