I was wondering if anyone happened to know the electrical requirements of the motor on a prius compressor. I am thinking of a project where I might like to run one or two or three with a VFD, and would like to know the voltages and current required to see if it was feasible. Basically, the information that would be available on the nameplate, if it had one.
It's driven by an inverter fed from the (unboosted) battery voltage, nominally 201.6 VDC. It's a wye configuration, I believe, with the common neutral being internal only, and only the three phase leads brought out. At least, that's the way the MGs are, and I'm assuming it's the same. So the inverter H-bridges can put a peak of 201.6 volts (nominal), plus or minus, across any two phase legs. For a sine wave, peak amplitude is RMS times the square root of 2, so that's about 143 V RMS phase to phase. Phase-to-phase in a wye is phase-to-neutral times square root of 3, so if you wanted to know the phase-to-neutral amplitudes, they'd be 116 V peak, or 82 V RMS. (I'm not sure why you'd want to know the phase-to-neutral voltages, since phase-to-phase are the only connections you've got, but anyway.) I think the compressor power tops out somewhere around 2500 to 3000 watts, so at 143 V RMS phase to phase, you'd need like 18 to 21 amps RMS phase to phase for full power. It is cooled by the refrigerant passing through it, so you probably don't want to run it at any high power levels without that. The MGs have resolvers that report back their rotor positions to a small fraction of a degree, so the inverters controlling them can compute the drive waveform to keep the magnetic field always at the wanted angle ahead of the rotor. I don't think the compressor has a resolver like that, so the compressor's inverter must be using a different algorithm that doesn't require one. I think I have heard of such algorithms but I don't know much.
