IMHO C-H has described the key problem.

The motors in these units are _probably_ induction motors. The magnetic field strength in an induction motor is directly proportional to the applied voltage, and _inversely_ proportional to the applied frequency. These motors are being operated at about 72% of nominal magnetic field strength. This reduces the _peak_ torque that the motor can produce by about 50%.

At the same time, these motors are going to try to spin at 6/5 normal speed, which will _increase_ the torque required by the compressor pumps. Depending upon the application, the torque required by a pump will increase as the _square_ of shaft speed, though I don't know if this applies for AC compressors. Certainly the torque required will be going up substantially.

IMHO you are behind the 8 ball. The motors will be producing less than rated torque. The compressors will require more than rated torque.

If you boost the voltage high enough to properly magnetize the motors, then you may run into issues with the maximum voltage of the control system, and life issues with the pumps running faster and at higher pressure. Or you might just get the system to run reliably in a somewhat 'supercharged' fashion [Linked Image]

Reno's points about cooling and charging are relevant, but IMHO second order effects. Solve the voltage problem first, the frequency problem second, and the cooling problem third.

Just MHO. I'm not out there in the field.

-Jon